\Lfc“ Lr ‘2‘) 1‘?“ flute, -|.~'.§‘_"qu i ‘3. I‘: t‘_‘ L 1-“ I‘D i " ‘l'\‘#é %__" u. , 4, L I G;VC¥:; «y This is to certify that the thesis entitled Stratigraphic Analysis of the Prairie du Chien Group, Lower Peninsula, Michigan presented by Steve Rohr has been accepted towards fulfillment of the requirements for Master's degree in Geology 6/sz o2: Major professor oateZKaey Mk / ¢ is" 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES ‘ RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. fiét’é 2 is LW Q " LL) STRATIGRAPHIC ANALYSIS OF THE PRAIRIE DU CHIEN GROUP LOWER PENINSULA, MICHIGAN By Steven Anthony Rohr A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Geological Sciences 1985 ABSTRACT STRATIGRAPHIC ANALYSIS OF THE PRAIRIE DU CHIEN GROUP LOWER PENINSULA, MICHIGAN By Steven Anthony Rohr The Lower Ordovician Prairie du Chien Group of the Michigan Basin has become a realistic target for hydrocarbon exploration since the discovery of natural gas in the sandstones of this Group beneath the Falmouth Field, Missaukee County. The New Richmond sandstone equivalent of the Prairie du Chien Group is an extensive, thick sheet sand that extends well southward into the Lower Peninsula of Michigan. Several distinct lithofacies are observed in these sandstones including lagoonal, near-shore, offshore. and barrier-bar facies. An offshore barrier-bar facies model is interpreted to best represent the depositional environment for these sands. Thus far, Prairie du Chien production has been limited to struc- tural traps. However, sandstone porosity does not appear restricted to structure as previously believed. Porosity in the Prairie du Chien sandstones appears to be entirely retained primary depositional porosity that escaped silica cementation. Porosity is not secondary in nature and is not relatedto the post-Knox erosional episode or to ascending basinal fluids. DEDICATION To my paienia; ihcii haven ending ioue, encouiagemeni, and unaeiéiah giving and Adaiifiice made aii 06 ihia pOAbibie. ii ACKNOWLEDGMENTS Very special thanks goes to Dr. C. E. Prouty, Thesis Committee Chairman, for taking me as a student of his. I will be forever indebted to him. He taught me a great deal of how geology should be. Thanks also goes to Dr.'s A. T. Cross and J. Trow. The "old school” profs showed me about the real world of geology. Thanks goes to Dr. William Harrison, Western Michigan University, for making the Prairie du Chien cores available to me, for allowing me to sample "whatever" I wanted and for some interesting and helpful discussions about the Prairie du Chien and Michigan Basin. Thanks also goes to Stuart Jennings, Jennings Petroleum, for making available some cutting samples. Special thanks goes to Marathon Oil Company for providing funding. Thanks goes to all the friends that I made while at State; I figure most of them to be lifelong friends--Keith "3-iron and putter" Hill, John E. N. Nelson, Jerry "rebel" Grantham, John "Josepi” Gillespie, Kurt "down-hill" Stepnitz, Mike "Savoir” Serafini, big Bob Dedoes, Tim "Guinness" Flood, my workout buddy Jim "Rico" Carty, and to my newest friend, Therese Burzynski. To everyone else not mentioned within and outside geology, who has in some way touched my life-- thanks! Special thanks also goes to the Department of Natural Resources, Petroleum and Subsurface Division for their help with log picks and details about specific wells. Thanks also to Dr. Michael Velbel for the use of his microscope and for showing me how to take photos with it. Also, my buddies in Indy--Jim Osborn, Steve Burke, and Bob Lee-- deserve thanks, along with my brother Mike, for always asking about my progress on the thesis. And lastly, the largest thanks goes to my Parents and Family. iv TABLE OF CONTENTS Page LIST OF TABLES .......................... vii LIST OF FIGURES ......................... viii LIST OF PLATES .......................... x INTRODUCTION ........................... l PURPOSE AND METHODOLOGY OF STUDY ................. 7 AREA OF STUDY .......................... ll PREVIOUS WORK .......................... l4 STRUCTURE OF THE MICHIGAN BASIN ................. l7 PRAIRIE DU CHIEN STRATIGRAPHY .................. 32 Regional Stratigraphy .................... 32 Michigan Basin Stratigraphy ................. 35 Sand Source ......................... 44 PRAIRIE DU CHIEN FACIES ..................... 46 Gross Lateral Facies Relations ............... 46 Facies Within the Prairie du Chien Sand ........... 53 Lagoonal Facies .................... 56 Near-shore Facies ................... 56 Offshore Facies .................... 59 Barrier-bar Facies ................... 59 PRAIRIE DU CHIEN PETROLOGY .................... 63 Mineralogy and Lithology .................. 63 Lithologic Descriptions ................... 73 Sedimentary Structures ................... 8O PRAIRIE DU CHIEN POROSITY .................... 86 Discussion of Secondary Porosity .............. 88 Discussion of Data ..................... 97 SUMMARY AND CONCLUSION ...................... APPENDICES A. A DETAILED DESCRIPTION OF THE TYPE PRAIRIE DU CHIEN GROUP .......................... B. PRAIRIE DU CHIEN SANDSTONE CORE DESCRIPTIONS ...... C. DESCRIPTION OF REPRESENTATIVE THIN SECTIONS OF PRAIRIE DU CHIEN GROUP SANDSTONES OF THE MICHIGAN BASIN ..................... D. WELL LOG DATA ...................... BIBLIOGRAPHY ........................... vi Page ll4 119 121 I30 I37 I46 LIST OF TABLES Table Page l. Discovery wells in the Prairie du Chien Group sandstones of the Michigan Basin ............ 6 2. Generalized regional correlation chart for Lower Ordovician Series .................... 36 vii Figure 10. ll. 12. l3. T4. 15. 16. LIST OF FIGURES Stratigraphic succession in Michigan ........... Sample distribution of Prairie du Chien Group ...... Area of study ...................... Michigan Basin and surrounding structural elements . . Structural trends in Michigan Basin and structural elements framing the Michigan Basin ........... Isopach map of Prairie du Chien Group .......... Isopach map of Black River Group ............. Isopach map of Trenton Group ............... Structure contour map of Prairie du Chien Group ..... Structure contour map of Black River Group ........ Structure contour map of Trenton Group .......... Gamma-ray log of State-Foster #l (T24N RZE Sec. 28), Ogemaw County. This illustrates the characteristic log response of the Prairie du Chien Group sandstones in the middle Michigan Basin ............... Gamma-ray log of Battle Creek Gas Company Bd #l53 (TlN R8W Sec. l4), Barry County. This illustrates the characteristic log response of the Prairie du Chien Group in the southern portion of the study area Sandstone iSOpach map of Prairie du Chien Group ..... Facies map of Prairie du Chien Group ........... Gamma-ray cross-section in Michigan Basin. Illustrates lithologic changes in Prairie du Chien Group ....... viii Page 2 18 I9 23 24 25 26 27 28 39 4O 47 49 50 Figure 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. Gamma-ray cross-section in Michigan Basin. Also illustrates lithologic changes in the Prairie du Chien Group ..................... Gamma—ray cross-section in Michigan Basin. Again, illustrates the lithologic changes in the Prairie du Chien Group .................... Illustration of offshore barrier-bar facies model Genetic classes of secondary sandstone porosity Textural development of hybrid pores ......... Petrographic criteria for recognition of secondary sandstone porosity ................. Diagenetic processes creating secondary sandstone porosity ....................... Structure contour of Prairie du Chien in Falmouth Field, Missaukee County ............... Structure contour of Trenton in Falmouth Field, Missaukee County ................... Structure contour of Dundee in Falmouth Field, Missaukee County . . .......... . . ..... ix Page 51 52 57 9O 92 94 96 115 116 117 Plate 11. 12. 13. 14. 15. 16. LIST OF PLATES Scolithus burrows in Prairie du Chien sandstone ..... Diplocraterion burrow in Prairie du Chien sandstone . . . . Glauconitic sandstone in Prairie du Chien Group ..... Near-shore sandstone in Prairie du Chien Group ..... Tight, fine-grained sandstone of Prairie du Chien Group . . Photomicrograph of sandy-dolomite sample ........ Photomicrograph of tight sandstone ........... Photomicrograph of tight sand with syntaxial silica overgrowths ....................... Photomicrograph of tight sandstone sample ........ Photomicrograph of Prairie du Chien sandstone with syntaxial silica overgrowths .............. Photomicrograph of Prairie du Chien sandstone with dolomite cement ..................... Photomicrograph of sandstone tight with syntaxial silica overgrowths ................... Photomicrograph of sandstone in the Prairie du Chien Group illustrating pressure solution .......... Photomicrograph of Prairie du Chien sandstone framework grains with sutured contacts because of pressure solution .................. Photomicrographs (A and B) of isolated clay-lined pores in Prairie du Chien sandstones .......... Photomicrographs (A and B) of isolated clay-lined pores in Prairie du Chien sandstones .......... Page 54 55 58 6O 6T 64 65 66 67 7O 72 74 75 76 79 82 Plate 17. 18. 19. 20. 21. 22. 23. Example of low angle cross beds from the Prairie du Chien Group ...................... Example of laminated sandstone in the Prairie du Chien Group ...................... Example of cross-laminated sandstone in the Prairie du Chien Group .................... Photomicrographs (A and B) of isolated clay-lined pore in Prairie du Chien sandstone .......... Photomicrographs (A and B) of isolated clay-lined pore in Prairie du Chien sandstone .......... Photomicrographs (A and B) of inhibiting affects on diagenesis of hydrocarbons in Prairie du Chien sandstones ...................... Photomicrographs (A and B) of inhibiting affects on diagenesis of hydrocarbons in Prairie du Chien sandstones ...................... xi Page 83 84 85 106 108 110 112 INTRODUCTION Since the discovery of natural gas in late 1980, in the deep Lower 0rdovician--Prairie du Chien Group sandstones of the Michigan Basin (Figure 1), exploration for hydrocarbons in this interval has been sporadic at best. The sandstones, and dolomites of the Prairie du Chien Group had previously been considered too tight to produce good petroleum reservoir rocks (Syrjamaki, 1977). Consequently, the Prairie du Chien Group had remained relatively untested for its hydrocarbon potential especially in the northern counties of the Lower Peninsula. However, the discovery of natural gas in Prairie du Chien sands beneath the Falmouth Field of Missaukee County, Michigan has changed the exploration attitude towards the deep strata of the Michigan Basin. The Dart Oil and Gas/PPG Industries--Edwards 7-36 discovery well (SW, NE, NE, Sec. 36, T22N, R7W, Reeder Township) in Missaukee County was originally intended as a deeper pool test beneath the Falmouth Field (Mississippian and Devonian production). Much to the surprise of the operator, however, dry, sweet natural gas was encountered with an initial production rating of 12.3 Mmcfgd (Bricker, 1982). The Edwards 7-36 produces from the sandstone facies of the Prairie du Chien in an interval ranging in depth from 10,548 to 10,695 feet (Bricker, 1982). Production was confined to the top 150 feet of the Prairie du Chien, directly below the "Lower Glenwood" formation [also known as the mm... mum-m STRATIGRAPHIC SUCCESSION IN MICHIGAN DMIOKX ‘MOLO‘ "(INT OUAHINAIV human-l INIORMAI TIRMS hv-p‘r-uv» ~~~_. 4.,” ....-.~.-—1--r-—.—........~ M. mar-mad now-o- m rum rm .0"va” m.“— Figure l. Stratigraphic succession in Michigan. "Zone of Unconformity" (Bricker et a1., 1983)]. Following the discovery at the Edwards 7-36, exploration and testing of the Prairie du Chien increased rapidly because of the initial excitement of other deep play possibilities. However, exploration diminished rather rapidly as follow-up drilling was rather disappointing. Some workers in the Michigan Basin considered that the Edwards 7-36 discovery was a fluke and not representative of the hydrocarbon potential of the deep basin [Montgomery (ed.), 1984]. During the initial stages of exploration for Prairie du Chien gas reservoirs the "highly variable and unpredictable porosity” [Montgomery (ed.), 1984] of the Prairie du Chien sands was considered to be the major cause of the very low wildcat success rate. Sandstone porosities range from essentially zero to approximately 15%, with these extremes being observed in the same well. Later, during the years 1981-82, following the Edwards 7-36, more than 30 Prairie du Chien test wells were drilled with only three dis- coveries, one of them significant. Hunt Energy's Winterfield Deep Unit l-A (NE, SE, NW, Sec. 30, T20N, R6W, Winterfield Township), in Clare County was initially completed at 190 Mcfgd producing from the Prairie du Chien sands. Like the Edwards 7-36 discovery, the Winterfield l-A test was drilled on a shallow, younger productive structure. This well was later abandoned as dry. A third discovery was made in 1982 by WainocoCHl and Gas in Otsego County at the Johannesburg 3-16 (SW, SW, SE, Sec. 16, T30N, R1W, Charlton Township). This well also produced from the sandstone facies of the Prairie du Chien and was initially rated at 625 Mcfgd plus 30 bcpd and 3 bwpd. The Johannesburg 3-16 has also recently been abandoned. Following these discoveries, Jennings Petroleum made a significant discovery in Newaygo County. The Anderson 1-8A (NE, NE, SE, Sec. 8, Tl4N, RllW, Goodwell Township) was initially rated at 10 Mmcfgd plus 26 bcpd, also producing from the Prairie du Chien sandstone interval. These latest discoveries confirmed that there is indeed good potential for commercial quantities of hydrocarbons in the Prairie du Chien Group sandstones and that the Edwards 7-36 discovery was not a fluke. Most recently, Amoco Production Company has made a significant discovery in Gladwin County in the South Buckeye Field (Devonian pro- duction) at the Letts Unit 2-36 (SE, SE, SW, Sec. 36, T18N, R1W, Buckeye Township). Again natural gas was encountered in the Prairie du Chien rated at 4.4 Mmcfgd plus 72 barrels of condensate per day (rated at 60 degrees API) from the interval 11,218 to 11,252 feet, making the well Michigan's deepest producing gas well. Again, the Prairie du Chien production is closely related to structure (L. Tolletson and M. Przywara, 1984) and beneath a shallow, productive structure. Surprisingly, however, this well has produced condensate even at the great depth of discovery. This illustrates that condensate may be discovered in the deep basin and is not restricted to shallower Prairie du Chien production like that at the Anderson 1-8A and Johannesburg 3-16. Even though several significant and encouraging discoveries have been made in the Prairie du Chien Group sandstones of the Michigan Basin (Table l), the possibilities of hydrocarbons in this and deeper intervals are still poorly understood. Many operators are taking a very tentative approach to the deep Prairie du Chien plays considering that not enough is yet known about the deep basin to justify the cost of exploratory wells on the basis of the low wildcat success rate. Many have taken the approach to let more data become available before an enthusiastic exploration strategy can be developed for the Prairie du Chien reservoirs. Overall, the variable porosity of the sands is believed to be the main problem with which to be concerned when testing the Prairie du Chien interval. In general, the porosity of the Prairie du Chien sands "appears" to be closely associated with deep structures, with production being confined to the uppermost 100 to 150 feet of the sands. It is hoped that this study may add to the understanding of the Prairie du Chien interval. However, it is believed that it will be a matter of time before enough data have been accumulated before conclu- sive information is available concerning the variable porosity of the Prairie du Chien sands and the potential for hydrocarbons in this and other deeper strata of the Michigan Basin. Aw_oc osmwuv mppmz mam cmg052m mzmzmm FF .umm meg zem va» xucaou xmm ppmcm aukem za FP-F “mo>mca Gaza Fm zzzzzm NF .uwm 38m zomh ocean za ~_-P .Fa pm + umeuz wok xucaoo mempu xmcmcm was: acmemmmcmz mummA anon Nu 3mmmmm om .umm 3pm zm_k mmmkm za + BLUES; .358 £325 895 TN Es 88.3 vase m + vgun om mmzmzm op .umm 3pm zom» ouocwmz MFPmm za + ammo: mmo zuczou ommmpo imam “mm: oplm mcznmmccmzoc ugua om mmmzmz m .umm 3—Pa ze— sampocumm mmoom zq + vmwuez op xuczou omzmzmz mmcwccmw oumwa .P mpnmh PURPOSE AND METHODOLOGY OF STUDY As mentioned previously, the major problem encountered by explorationists searching for Prairie du Chien hydrocarbon reservoirs has been the highly variable and unpredictable porosity of these sands. Many theories have been proposed concerning the development of porosity in these sands (these theories will be discussed later), but to-date a concerted effort has not been made to bring together as much information as possible to test these theories. The purpose of this study, there- fore, is to attempt to bring together these data in an effort to draw some conclusions about the origin of porosity in the Prairie du Chien sands of the Michigan Basin. A structural, stratigraphic and petro- graphic approach is being used in this study to determine if any relation exists between porosity, structure, and stratigraphy. Several types of data were collected for this study. First, more than 220 electric logs were studied at the Michigan State Geological Survey, Petroleum and Subsurface Division in Lansing, Michigan. From these logs formation tops were picked for the Trenton Group, Black River Group, Glenwood formation, "Lower Glenwood" formation (also known as the "Zone of Unconformity" by Bricker et a1., 1983), Prairie du Chien Group and Trempealeau Formation. Typically, the best results were achieved when gamma ray-~1ithodensity logs were studied together. However, many of the older well logs studied possessed only gamma-ray logs. In these instances drillers logs were also used to determine the best formation top pick. From these data, isopachous and structure contour maps were prepared for each of the above formations. Also, lithofacies distribution of the Prairie du Chien was mapped in an effort to understand the lateral relationships of the Group. Sandstone isopachous and clastic ratio maps were also prepared for this study. Formation top picks are listed in Appendix D of this thesis. The second form of information gathered for this study was the description of 14 Prairie du Chien cores stored at the Western Michigan University, Department of Geology Core Laboratory. Dr. William Harrison made these cores available for this study along with sample chips from these cores. Descriptions of the cores are also included in Appendix 8. Figure 2 illustrates the distribution over the study area of the cores examined for this study. Also, shown is the location of cuttings samples donated by Mr. Stuart Jennings of Jennings Petroleum, Flint, Michigan. Third, selected samples from the described Prairie du Chien cores were thin sectioned for petrographic study. Over 50 thin sections were prepared and studied for this thesis. These thin sections were point counted (150 counts per slide) to determine the type and percent of framework grains, percent porosity, and percent clay matrix. Also determined were cement types and abundance, grain sizes and shapes, and pore geometry and type (i.e., primary versus secondary porosity). Representative thin section descriptions appear in Appendix C. 4' Ic‘rlc‘ l I __I_ E ___E l ! - -_I_- I -4 ! | . “Zitii‘zjgfiéirrj ! _ ___I- - .fl - an em: goal in? I j jfllullf ITO—T T l I l FI , ‘iL—I:*+_‘I"I ' j“ 7"“??? 53" I" ‘ I JINL _'_ . T "w r—_ —-r--I'--r "1. - L--—r—-I'—-. I ! ! {—4-1 I ' I 4‘4“?“ I___ u CM" 0 CW“ ~O.I I” '0'. ”0.1!. a con: ms mm W 01!! «out I cutting up“; MUM: Damnation an“ atom. ovu- u on“ I M“ Figure 2. Sample distribution of Prairie du Chien Group. 10 In an effort to better determine clay mineral types present in the sands, clay was separated from the matrix of several porous and friable sand samples and studied by the x-ray diffraction technique. AREA OF STUDY The northern two-thirds of the Lower Peninsula was delimited as the area of study for this thesis. An arbitrary southern limit for the study area was chosen along the Township and Range system base-line for Michigan. This base-line trends east-west from Lake St. Clair to the shore of Lake Michigan and forms the southern boundary for Allegan, Barry, Eaton, Ingham, Livingston, Macomb, and Oakland Counties. The study area is shown in Figure 3. There are several reasons for choosing this study area. As the sandstone facies of the Prairie du Chien Group is best developed in this area and some impressive production from a few wells would likely lead to further testing of the deeper section, this appeared the ideal part of Michigan to focus this study. Preliminary investigation indicated that the sands of the Prairie du Chien pinch out north of the base-line defined above. Well distri- bution in the study area was sufficient to enable the mapping of the distribution of the sandstone and omitting the area of distribution of the carbonate facies as much as possible. The study area also was designed to include the known Prairie du Chien sandstone productions up to the time of this study. The most concentrated well distribution in the study area is along the southern and southeastern edge (Figure 3) where the Prairie du Chien 11 12 (4“- suptfi’ok \ DOMINION or CANADA :1. MIG“ Y n In . C “4.0(4, mu It m TIA" I“ uuou “(MC .. ,/ of LA“ “(IRA cunt “COSTA noun 0 IMCKA taut W who! was! un- LAP“. “It!“ J! an Inna-INK cum muo- CANADA uni-u III-not LAKE (RI! Figure 3. Area of study. 13 is found at fairly shallow depths. Along the south and southeast areas of the study location the Prairie du Chien is dominated by carbonate/ shale lithologies. Therefore, it was concluded that extending the area any farther south into the region of carbonate facies would be beyond the immediate scope of this study. However, work in progress by Nelson (1985) is being directed toward a detailed study of the Prairie du Chien carbonates of the southern shelf area in an effort to determine the hydrocarbon potential of the Group in this portion of the Michigan Basin. Excluding the shelf area, the concentration of wells in the central and northern portions of the Basin is scattered and generally sparse. The enormous cost of the deep test wells pre- cludes the drilling of a large number of exploratory wells in the deeper basin. Furthermore, the deep Michigan Basin had not been considered worth testing for its hydrocarbon potential, until recently. But with the Devonian strata of Michigan well within the "stripper" stage of production and the northern Silurian Reef trends production leveling out, explorationists are beginning to look toward and test the deeper strata of the basin like the Ordovician Trenton, Black River and Prairie du Chien Groups. The near future should see numerous wells being drilled to these strata, and possibly to the basement, adding to our knowledge of the hydrocarbon potential and structure of the deep Michigan Basin. PREVIOUS WORK Owing to the lack of deep-well control in the Lower Peninsula of Michigan, the work dealing with Ordovician stratigraphy has been sparse in previous years. Cohee (1945, 1946, and 1948) was one of the earliest workers to study the Ordovician system in the Michigan Basin. He was the first to recognize and, on the basis of lithology and subsurface stratigraphy, subdivide the Prairie du Chien Group in the Lower Peninsula into the Oneota dolomite, New Richmond sandstone, and Shakopee dolomite, in ascending order. Cohee (1945, 1947, and 1948) made numerous corre- lations to the strata in areas surrounding the Michigan Basin. Much of the nomenclature that he introduced is still used today. Using gamma-ray logs and similar lithologies between wells, Ells (1967) was able to prepare a stratigraphic cross-section of Cambro-Ordovician strata in the Upper and Lower Peninsulas of Michigan. Syrjamaki (1977) made a regional study of the Lower Ordovician Prairie du Chien Group in the Lower Peninsula of Michigan. Based on well samples, and geophysical logs he was able to determine the Prairie du Chien boundary contacts and define the extent, distribution, and lithology of the Group in the Southern Peninsula. Syrjamaki divided the Oneota dolomite into a lower sandy dolomite unit and an upper argillaceous dolomite unit. Because of difficulties in recognizing 14 15 individual units, Syrjamaki believed that the New Richmond sandstone and Shakopee dolomite should be combined in this area into the New Richmond-Shakopee Interval. The Oneota dolomite is described (Syrjamaki, 1977) as a buff to brown, fine to coarsely-crystalline dolomite with white chert and floating sand grains. The Oneota is more argillaceous and sandy at its base where it is interbedded occasionally with green, red, and gray, mottled shales and sandstones. The New Richmond-Shakopee Interval is described as a fine-to-medium-grained, subrounded to rounded, frosted to slightly frosted to clear, gray sandstone, often stained pink, with silica and dolomite cement. According to Syrjamaki (1977) the sandstones of the Interval are best developed in northwest Michigan and basinward are often associated with chert, green to gray shale, buff to tan siltstone, limestone, and dolomite. The dolomites are commonly buff to brown, very finely-to- finely-crystalline and sandy, alternating with beds of sandstone and thin shale. A brown, very fine-to-finely-crystalline, silty and argillaceous limestone is found basinward. The Prairie du Chien group ranges in thickness from zero in southeast Michigan to approximately 1050 feet in the west central portion of the Lower Peninsula according to Syrjamaki (1977). However, more recent well data indicate that the Prairie du Chien Group is greater than 1300 feet in the middle-basin area (Figure 6, of this report). 16 At the time of Syrjamaki‘s work (1977) the Prairie du Chien Group as a whole had not proved to be a significant hydrocarbon producer. Overall, the Prairie du Chien sandstones and dolomites appeared to be too tight to have sufficient porosity for a good reservoir, although a few scattered porosity zones had been found toward the edges of the basin (Syrjamaki, 1977). However, his restored section of the Prairie du Chien north-south across the Lower Peninsula showing the increased quartz sand content apparently created considerable interest to the explorationists. Stelzer (1982) reported on studies of samples from Missaukee County deep tests and suggested that hydrocarbon occurrences in the Prairie du Chien are related to clay mineral content of the sandy dolomite, with clay believed to coat quartz grains thereby curtailing silica overgrowth development which would tend to close pores decreasing porosity. Bricker et a1. (1983) have recently published a set of cross- sections indicating Upper Cambrian and Lower Ordovician correlations in the Michigan Basin based on the most up—to-date mechanical logs available. Zwicker (1983) used over 200 well logs to analyze the distribution of Cambro-Ordovician sandstones, the deeper (Ordovician) structure of the Michigan Basin, and the possible relationship of the deeper petro- leum occurrences to structure. Zwicker concluded that future explora- tion for Prairie du Chien (for "Knox Sandstone") gas is good and will depend not only on finding structural highs, but also on findings favorable zones of porosity. STRUCTURE OF THE MICHIGAN BASIN The Michigan Basin is a circular to ovate sedimentary basin located in the Central Interior physiographic province of the United States. It is approximately 122,000 square miles in areal extent and encompasses all of Michigan, and portions of the States of Wisconsin, Illinois, Indiana, Ohio, and the western portion of the province of Ontario, Canada. Geologically, the Michigan Basin is surrounded by several well-known framework structures (Figure 4) including: the Kankakee Arch to the south and southwest; the Findlay Arch to the southeast; the Algonquin Arch to the east; the Canadian Shield to the northeast and north; the Wisconsin Dome to the northwest; and the Wisconsin Arch to the west. Workers in the Michigan Basin have tried previously to relate the surrounding framework structures to the occurrence, origin, and predominant NW-SE trend of many smaller intra-basin structures (the producing anticlines and fractures) (Figure 5). It is believed that an understanding of the origin of the large framework structures may aid in understanding the origin and occurrence of the smaller intra-basin structures. Robinson (1923) proposed that the structural features observed in the Michigan Basin are the result of vertically directed forces and not the result of horizontal compressional forces. He describes five types of folds that are the result of vertically acting forces: 17 y..— L 18 MICHIGAN BASIN “t . - 915995532 , . KL'NO'S mm.“ In mama's-auto“- __ I- _._. hon .0 mun-a- ._.-+-—m«-—Iu- m iota-nc-uDWon. 0.00 I"! Dunc-Ow...“ H.057 Moo-In,” .00 Cool “'01 m an... In U1MI “coo-av“-.. H-”W~I~.I.U Figure 4. Michigan Basin and surrounding structural elements (from £115, 1969). 19 .Amem_ .upmxuod Lautav =_mam gnaweow: \ \ \ \ -\*" » “-¢-&" / A“. if mu wu- 0;..t is t- tests. Wine-w \,\ asp mcwEmcm mgcmEmpm chzuozcum vcm :wmmm cmmmzuw: cw mucosa .mgzuuzcum .m mesa?» 20 (l) domes and quaquaversal folds; (2) radial linear folds; (3) concentric terrace folds; (4) linear terrace folds; and (5) monoclinal folds related to deep-seated faulting. Of these five types only one, the dome or quaquaversal fold, is typically due to an upward acting force. Pirtle (1932) believed that the Michigan Basin probably originated in Precambrian time and its sedimentary and structural history is closely related to the large framework structures surrounding it (the Cincinnati, Kankakee, and Wisconsin Arches). Pirtle postulated that the Wisconsin and Kankakee arches are the remnants of large Precambrian mountains. These mountains were base- leveled before the Paleozoic with the sediment accumulating in a proto-Michigan Basin that paralleled the Precambrian mountains in an elongate, trough-like manner. He suggested that old lines of structural weakness in the basement (probably Precambrian in age), with accompanying vertical acting forces and subsequent periodic horizontal compressions through time, could account for the development of the folds in the Michigan Basin. These lines of weakness probably closely paralleled the trend of the adjacent Precambrian mountains and therefore produced sufficient basin subsidence in Precambrian time to accommodate sediment from erosion of the mountains. Lockett (1947) also believed that the structural features surrounding the Michigan Basin are underlain by the cores of Precambrian mountains. He also stated that these features remained more or less positive and that the principal movement during the Paleozoic was the 21 continued subsidence of the basin into which the sediments from erosion of these mountains were deposited. During the Paleozoic, three sides of Michigan Basin were more or less held stationary by the surrounding framework structures, however, the southeast side of the basin, in the vacinity of Lake St. Clair, continued to subside. Lockett considered that this condition produced a system of lines of weakness (or frac- tures) in the basement through the unsupported end of the basin parallel to the northeast and southwest sides which remained positive. With increasing sediment load, differential basin subsidence was initiated along these lines of basinal weakness. Sediment accumulation was believed to be greater on the basinal side of these faults forming a stepfaulting situation into the central portion of the basin. Lockett (1947) further considered that the parallel trends of struc- tures in the Michigan Basin were due to movements along these lines of weakness in the basement under the basin and that the structures are to be considered the result of basinal subsidence. Compressional orogenic forces were believed to have played little or no role in the development of anticlinal structures or fractures in the Michigan Basin. Rudman et a1. (1965) postulated that much of the strata in the midwestern United States is underlain by basement that is highly faulted. They suggest that the prominent NW-SE trend of structures in the Michigan Basin is similar to trends of gravity anomalies in the basin, i.e., the mid-Michigan gravity anomaly, further indicating some kind of basement control over the development of these structures. 22 Fisher (1969) postulated that faults have controlled the development of many of the large structures in the Michigan Basin, including the Howell Anticline, Lucas-Monroe Monocline, and Albion— Scipio Field. He also suggested that the rectilinear fault pattern observed on the surface of the Canadian Shield could be a model for that of the basement of the Michigan Basin which may also exhibit this same type of rectilinear fault pattern and that this was probably developed during the Precambrian and was subjected to periodic movements through the Paleozoic era. On the basis of systematic isopachous mapping of successive strata, Fisher (1969) postulated that the Michigan Basin was created in Ordo- vician time with the major subsidence occurring in the Middle Ordovician (Mohawkian Series) and Upper Ordovician (Cincinnatian Series) time. Catacosinos (1972) suggested that the Michigan Basin was initially created in Cambrian time, at least. The data assembled in this study indicate that, indeed, a proto- basin was developed in early Ordovician time and was undergoing very active susidence. More than 1300 feet of Prairie du Chien sediments occupy the depocenter (Figure 6). This supports the suggestion of Catacosinos (1972) that the Michigan Basin was initiated by Late Cambrian time, at the latest. However, as pointed out by Fisher (1969), it was not until Middle Ordovician time that the basin configuration with which we are most familiar became evident (Figures 7 and 8). The position of the basin center during Ordovician time was northwest of the Saginaw Bay area (Figures 9, 10, and 11). 23 "AIM! W CHIEN GIOU’ I’mcfl III an..- an... n-u I. Figure 6. Isopach map of Prairie du Chien Group. 24 BLACK RIVER GROUP ISOPACH MAP - an... or Figure 7. Isopach map of Black River Group. 25 00 TRENTON GROUF P A M H c A P 0 K. dig—1 ‘ ' ‘ "IXO'OI' ~ ml ...u Isopach map of Trenton Group. Figure 8. 26 v1. 0‘ 16¢ '7500 "[500 rut-- r - nu.” u. L‘QIII “up u... ... .. "III N “I m t. m wfl mg w my m... Structure contour map of Prairie du Chien Group. Figure 9. 27 ILACI ”VII «our SVWCTIDE CWYWI I» .I~ - .~...a Figure 10. Structure contour map of Black River Group. 28 . % a I I p f’ 3 ——I- " -2500 I - _ , _ V“ ~zsoo ‘ '7’ ’ I l L, 1 . I fl RI I \a ‘2, B ,‘ I '5000 o . I, _- 1 \ .x V I .u 1 , 4500 nun--r - u-ua n. n nnnnn VIINYM Gm' IVIUCYM GMT” I» o .u... 590... u... n. u... -- m." LA_.I_.I’ J Figure 11. Structure contour map of Trenton Group. 29 E115 (1969) prepared an excellent summary of the information available on the architecture and origin of the Michigan Basin. Because of the lack of deep well control and geophysical data, he was, however, not able to draw any conclusive answers about the basement structure over the entire Michigan Basin, the persistence of folds with depth, and the presence of Howell-type structures in the mid-basin area. Prouty (1970) summarized the notable trends in the Michigan Basin, including: (1) the predominant northwest--southeast and northeast-- southwest folds, both sets of folds exhibiting evidence of lateral faulting; (2) a fairly definite radial fold pattern; (3) a rather persistent joint pattern; (4) a shift in structural and isopach basin center in each system up to the Mississippian System. He also suggested that basement lineations (fractures) are inherited from the Precambrian basement. 0n the basis of LANDSAT satellite imagery studies, Prouty (1976 and 1980) concluded that: (l) lineaments in the Michigan Basin are shear faults which show lateral offset in some cases; (2) shear faults have formed shear folds; (3) the principal faulting and folding was pre-Marshall (Mississippian) time; (4) the depocenter shifted west to its present position in post-Osage Mississippian time, Coincident with the time of the major compression; (5) north-northwest elliptical shape of the basin is the result of simple shear (strain ellipse); (6) faults were the channelways for the migration of hydrocarbons and ascending dolomitizing fluids; (7) basement shear fault patterns are attributed to stresses from a general east-southeast direction 3O (Appalachian orogen). Even more recently, Prouty (1984) showed that lineaments (shear fractures and faults) in the Presque Isle County, Michigan area have controlled the development of Karst topography and surface drainage patterns. Prouty's summary includes pre-LANDSAT detection of Michigan Basin structures, the development and use of LANDSAT imagery in mapping of intrabasin structures, and development of a simple shear model in the Michigan Basin which can account for the folds and fractures in the basin. Prouty believes that the wrenching model for the Michigan Basin is a valuable tool for future exploration of hydrocarbons in the Basin. Other hypotheses about the origin of structures within the Michigan Basin also have been proposed in recent years. They include: (1) fault block tectonics with associated drape sediments over the blocks (Fisher, 1983) and (2) deep seated faulting produced during an episode of Keweenawan rifting in the Michigan area, now interpreted to be represented by the mid-Michigan gravity high (Chase and Gilmer, 1973). Like other hypotheses these must address the problems of: (l) channelways for petroleum migration and ascending dolomitizing fluids; (2) lateral offset observed along many folds and faults in Michigan, etc. As more drill data becomes available these theories may be further tested. From the previous discussion it is evident that the hypotheses concerning the geology of the Michigan Basin have developed at a slow, methodical pace. Until 1980, deep drilling was a very rare occurrence in Michigan because of the belief that deep strata were economically 31 unimportant as they were thought to be barren of hydrocarbons. However, with the recent natural gas discoveries in the deeper strata of the Michigan Basin more of these data will become available. PRAIRIE DU CHIEN STRATIGRAPHY Regional Stratigraphy The regional stratigraphic nomenclature dealing with strata of Lower Ordovician (Canadian) age is fairly well accepted. Syrjamaki (1977) summarized the evolution of this nomenclature. Therefore, this report will only briefly discuss the regional stratigraphic correlates of the Michigan Basin Prairie du Chien Group. Lower Ordovician sedimentation in the eastern half of the United States was dominated by widespread carbonate deposition. Lower Ordovician carbonate lithologies are observed from the Appalachians west to Missouri, northwest to Wisconsin and Michigan, and north to New York. Both dolomite and limestone lithologies are observed. Some structural control over lithofacies appears to be present in the Appalachian Valley and Ridge Province. Prouty (1948) demonstrated that the Chepultepec dolomite (basal formation of the Canadian Series in Virginia and Tennessee) is predominantly a limestone facies to the southeast of the Adirondack Arch. On the other hand, however, dolomite is the predominant lithology northwest of the Arch, and persists to the west, northwest, and north to Missouri, Wisconsin, and New York, respectively. The facies control by structure is also observed to the north along the Adirondack Arch into Pennsylvania. Prouty (1948) suggested that the area northwest of the Adirondack Axis 32 33 was restricted from the circulating waters of the geosynclinal area to the southeast. The restriction of ocean waters west of the Adirondack Arch allowed evaporation to concentrate these waters. Penecontemporaneous replacement of the deposited limestone by dolomite therefore occurred. The area of restricted ocean waters is presumed to have extended throughout the eastern half of the United States, westward of the Adirondack Axis. This is suggested by the great volume of dolomite lithologies observed in Lower Ordovician strata. The lithology of the Beekmantown Group (Lower Ordovician) of Virginia and Tennessee was described by Butts (1940) and Prouty (1948). The Beekmantown is described as a thick bedded, bluish-gray, fine to medium grain crystalline dolomite. Chert is abundant and is usually brown, soft, coarse, and cavernous. White chert, similar to the chert in the Oneota dolomite of Wisconsin (Prouty, 1985) is occasionally observed. Siliceous oolites and oolitic chert is common in the lower portion of the Beekmantown. Thin limestone units are occasionally seen in the lower Beekmantown also. Well-rounded grains are observed, and in some cases sandstones lenses are present, but rare. The Beekmantown weathers to a light to dark brown color. Prouty (1948) described two thin sandstone beds near the contact of the Copper Ridge Formation (Upper Cambrian) and Chepultepec dolomite (Lower Beekmantown) in northwest Virginia and Tennessee. These sands are three to ten feet thick and separated by 15 to 20 feet of dolomite. Prouty observed a steady westward and northwestward increase in the median sand grain size of these two sandstones which suggested a 34 west-northwest source for the sand, possibly the Wisconsin Dome area. A similar source has been suggested for the Upper Cambrian sandstones (Prouty, 1948). As suggested previously (Syrjamaki, 1977), the sands of the Prairie du Chien Group in the Michigan Basin also have a north-northwest source. Several distinct fossil assemblages are observed in the Beekmantown Group, which are useful in stratigraphic correlation throughout the region. Generally, fossils in the dolomites of Lower Ordovician strata are completely obliterated by processes of dolomitization. However, some very well-preserved fossils are recovered from the cherts. Lecanospira beds have been correlated largely on the gastropod fauna with the Nittany dolomite of Pennsylvania, the Longview dolomite of Alabama, and the Roubidoux Formation of Missouri (Prouty, 1948). Helicotoma uniangulata is the chief guide fossil for the Chepultepec dolomite of Alabama, Gasconade Formation of Missouri, Oneota dolomite of Wisconsin, and a cherty zone considered to be the top of the Little Falls dolomite in New York (Butts, 1940). Other paleontologic evidence indicates that these strata are correlates. A Ceratopea zone in the Beekmantown has been shown to have common fossils in the Newala limestone of Alabama and southeast Tennessee; to the Jefferson City and Cotter formations of Missouri; to the Shakopee dolomite of the Upper Mississippi Valley; and to the Bellefonte (and possibly Axemann) formation of central Pennsylvania (Prouty, 1948). 35 The general stratigraphic correlations are shown in Table 2. Throughout the entire area, the Lower Ordovician lithologies remain strikingly similar which further supports these stratigraphic correlations. Following Lower Ordovician time a eustatic drawdown of the Ordovician seas caused the development of a worldwide erosion surface. The post-Knox Unconformity, as it is often referred to, is developed on the Beekmantown and other regional correlates (Table 2). The post- Knox Unconformity is often marked by a very masked contact with the overlying Chazyan strata, extensive solution features and erosional relief of 200-300 feet in some instances (Cooper and Prouty, 1943, and Prouty, 1948). Locally up to 600 feet of strata are missing in parts of central Pennsylvania, where transitional beds may occur at the contact when the missing units are present (Chafets, 1967 and 1969). Following development of the post-Knox Unconformity, a massive transgression of Middle Ordovician seas brought about deposition of Champlanian sediments. Michigan Basin Stratigraphy Lower Ordovician stratigraphy in the Michigan Basin is fairly well established. The Prairie du Chien type section in Wisconsin (Bain, 1906) (Appendix A; after Stark, 1949) is divided into three units. In ascending order they are: the Oneota dolomite (McGee, 1891), New Richmond sandstone (Wooster, 1878), and Shakopee dolomite (Winchell, 1874). The Michigan Basin Geological Society (1964; Figure 1 of this report) accepts this terminology in the Michigan Basin. 36 m allot as: 3‘ N or... 0‘3 08.. cl .5: ll! :55... . 0.. u it it» £00 hits :00 £031.... ‘9. Iva-II it: coll-n, gal Jo. I... so. I... It. . [Goals-£0 too—Ins {on :9 W .0. 0 on?! w .8 Doc)! .7. :1:- ‘IQ’DO. [5.8.0: 3.3!. w i n _ c _ u pl... m m In... 8.3.8 1.3.7. :6 .31. m :6 .t.» m III...- I. .. II...- .9. 3|... m :8 3": 3 in t S m m loan-.0. I36 I. u h. Sui R. M. i nil-v an... i 515 u Sony M £00 a u... U. ot—I‘ M . . C .2738 ..8 «In! 8-8:... :3... ole-la MK Boa-8 . r\1 )II) \Il‘l)‘ Fri-\Izll I I 5 S!!! .341” . 51 .3 so; 3. r8 J. .5 pool .3. .u. . . . . .. .. u n. .- uu Seat—no ‘ 303:; is o In. .13... 2c»! .51. ‘38.". III; 1.8.88 .2... golf... .8... a u “ .IIF " '5 go .95 '3‘ . £0 to N m. 1 to u out... Btu . . . . so... i... S... 1:. I... i:- r. to: in: .8... 11. I... 38. .31. S... ta. Br... I... i... r. 8.13.... r c is . I:.: w inc—II it". Eel—CI P. i .5 Ball» to lulu .5 330'; .5 i 05...: :5 I33...— 3 i .uu Il-oo ‘ :3: .335 8.3. 5-9:. .3: . a: .53. . anti... .3... .3... =8. :8. 3.... {I}. {I}. .7 .o 3...... II . .11.}. .II}. J. o. :19... .u. a. 51‘. ..¢ a. tail. :0: :0": i a {:1 in... a... 0.8 :U..|- silt... ‘00.... 1.1000:- I'!‘ .03...— coal—:— .l..lo £32! Son. mmwcwm cmwuw>ouco LmZoA Lo. ucmzu cowumpmccoo Pacowmmc vawpmcmcmw .N mpamh 37 Carbonate lithologies of the Prairie du Chien have been known to be present in the Michigan Basin for some time (Cohee, 1945, 1947, and 1948). However, the lack of well data in the center of the Michigan Basin precluded Cohee from making the correlations of Lower Ordovician strata there. More recently, several deep tests showed that not only are the dolomite lithologies present, but a very thick, massive sand was also developed in the Prairie du Chien Group. This massive sand is probably equivalent to the New Richmond. This sandstone has become the target of many wells over the past few years, and more information about its distribution and character is, therefore, available. A widespread transgression during New Richmond time resulted in a large amount of sand being deposited in the Michigan Basin. Con- comitant with this sand influx, the Michigan Basin was undergoing an episode of active subsidence. The sediment influx kept pace with or slightly exceeded the rate of basin subsidence and, therefore, the sand spread into the southern portion of Michigan instead of being restricted to accumulation in the continually deepening basin. Over 1000 feet of sand plus sandy dolomites are observed in the Lower Ordovician depocenter (Figure 13 of this report). The deposition of the sand was the dominant sediment accumulating in the middle and northern Michigan Basin area through the end of Prairie du Chien time. However, carbonate and shale deposition was taking place contemporaneously in the southern part of the Basin as sand deposition thinned southward. A series of small scale transgressions and regres- sions produced an interfingering of sand, shale, and carbonate near the 38 margin of the sand deposition. Elsewhere, carbonate and shale deposition took place exclusive to the deposition of sand. The Prairie du Chien Group will differ lithologically depending on location within the Michigan Basin. Therefore, geologists must recognize the various lithologic characters of the different facies of the Prairie du Chien in order to identify top (and bottom) of this unit. In the deep basin area, the top of the Prairie du Chien is placed below the Glenwood Shale or below the "Lower Glenwood" formation (Zone of Unconformity, Bricker et a1., 1983) when it is present. The massive sand of the Prairie du Chien possesses a very distinct and distinguish— able gamma-ray signature compared to the Glenwood and "Lower Glenwood" (Figure 12). Generally, the top of the Prairie du Chien is placed at the first clean sand below the Glenwood or “Lower Glenwood." In the south and southeast portion of the study area the assignment of the Prairie du Chien top is a bit more problematical. The carbonate and shale lithologies of the Group are more prevalent here than in the north and thus the contrast with the overlying Glenwood Shale is not as distinctive. However, as the Glenwood is found at the base of the Black River Group the top of the Prairie du Chien can still be identi- fied with confidence directly below the Glenwood Shale (Figure 13). Even though the Prairie du Chien Group and underlying Trempealeau Formation are similar lithologically, the bottom of the Praier du Chien is also identified with confidence. It is generally accepted that the top of the Trempealeau is placed below the lower most highly radioactive 39 Brown, Sun 6 Super to New Oqu- In 80¢ ll. Ill-.3 1! .Amwm_ .._m um meowLm EOLLV cwmmm :mm.zo.2 m_nu.5 mzu :. mmcoumucmm aaoco cmwnu an mwcwmca mg» Lo mmcoammc mo. u.»m.cmpumcmsu one mmpmcums... mmch .auczou zmemmo .Amm .omm umm zempv .3 LmumoLumumum .0 mo. xmcnmEEmw .N. mczme W m . w m m . m m . M m/ m . m . u _ _ . _ m- . .. a .w .m . . a 3 n mu _ H . . _ . o L... var. _ L... a a. _.__ _,. 3:: . u . x. : W L ,. f . 9L. L r . 31:... L. . P 3 it 4 . 5. _ <1.» MEL“ c .\o\ _.\- L‘.e.)o-¢u|a)l\ll)nl) \Ii)\I»\II5\.91)1\ gian/MitfrImf . «It? 7. I v 3 gale/KICIILI.’ <£<<fi7flbr1r> S; I? #4:.— .. (I HLJ/Nvaac ’5: 3}" oi _ (if) Dun Duos-g '1...“ an Figure 13. 40 Bull. Cvul Gas Co. UD-Io I” su 14,! n: a u m Loud than ”0' “III I“ O "I all! .30 .J ._.. _-..—. Gamma-ray 109 of Battle Creek Gas Company 80 #153 (TlN R8W Sec. 14), Barry County. This illustrates the characteristic log response of the Prairie du Chien Group in the southern portion of the study area (from Bricker et a1., 1983). 41 zone of the Prairie du Chien and above the cleaner and less radioactive sand of the Trempealeau (Lilienthal, l978). As mentioned previously, a eustatic lowering of sea levels occurred following Lower Ordovician time which produced the post-Knox erosional surface in eastern North America. The eustatic sea-level lowering may have been, in part, associated with the Blountian Disturbance in the southern Appalachians. The effect of this erosion is easily recognized in the Michigan Basin. It is generally accepted that the top of the Prairie du Chien is marked by the post-Knox Unconformity. In the southern portion of the Basin, cut and fill channel deposits are present in the Prairie du Chien carbonates. In one instance approximately 230 feet of sand has been observed to fill one of these channels (Nelson, John, oral comm., 1985). The presence of the post-Knox Unconformity in the mid-basin region appears to be more problematic, however. In several of the cores described in this study (Appendix B), the position of the post-Knox Unconformity was not recognized by a clearly demarcated contact at the top of the Prairie du Chien sandstone. The transition always appeared gradational in the wells studied, with interfingering relations often observed. The lack of evidence for the presence of the post-Knox Unconformity in the mid-basin area suggests that: (l) the Michigan Basin was not sufficiently drained by the lowered sea-level to cause subaerial exposure with intense erosion of the Prairie du Chien; or (2) the deep basin topography was highly irregular with only higher provinces being affected by post-Knox erosion. In the 42 southeast portion of the study area, intense erosion, coupled possibly with some small amount of tectonic activity along the northern portion of the Findlay Arch, did take place, totally removing the Prairie du Chien (Figure 7). A similar situation is reported for the Northern Ohio Platform area, where the Lower Ordovician strata has been totally removed by erosion and hydrocarbon production is related to the post- Knox Unconformity and Copper Ridge erosional "knobs” (Whiting, 1965; Stelzer, 1966; Benedict, l967; and Dolly and Busch, 1972). In the middle Michigan Basin area, a series of carbonate, shale, and sand facies exists between the Glenwood and Prairie du Chien. This body of sediments has been informally named the "Zone of Unconformity” by workers at the Michigan State Geological Survey, Petroleum and Sub- surface Division (Bricker et al., l983). This "Zone" is considered to represent sediments accumulated from the erosion of units on the basin rim during the development of the post-Knox Unconformity. The area of accumulation may not itself have been exposed to the erosional effects at the end of Prairie du Chien time. Rather, the drawdown of the seas in the Michigan Basin may not have occurred in the middle basin area where these sediments later accumulated. The nomenclature used by Bricker et al. (l983) does not, however, appear to be very useful and therefore should be rejected. The writer prefers the use of the term "Lower (allenwood'l formation for the unit between the Glenwood Shale and Prairie du Chien. This nomenclature was also used by Zwicker (1983). It is interesting to speculate about the actual stratigraphic relationship of the "Lower Glenwood" to the Glenwood Shale and Prairie 43 du Chien Group. Does the "Lower Glenwood” represent the youngest Prairie du Chien strata or the oldest Glenwood? Because the presence of the Shakopee dolomite in the middle basin is problematic, Syrjamaki (l977) grouped the New Richmond sandstone and Shakopee dolomite into the New Richmond-Shakopee Interval because of difficulties in distin- guishing between them on the geophysical logs. The writer concurs with this because strata with recognized Shakopee-type lithology was not found in every core described. The "Lower Glenwood" perhaps could represent atypical Shakopee sedimentation in a basin that was possibly slowly becoming very restricted and stagnant from the eustatic lowering of sea level that was beginning to occur towards the close of the Lower Ordovician. The "Lower Glenwood" depocenter was located to the north- west of Saginaw Bay. If this were the case, the post-Knox Unconformity might have occurred (timewise) between the "Lower Glenwood" and Glenwood formations. Transitional beds similar to these of the "Lower Glenwood" are observed on top of the Beckmantown Group of Pennsylvania (Chafetz, l967 and l969). He further concluded that this transitional zone represents continuous sedimentation between Lower and Middle Ordovician strata on the basis that no physical evidence was observed above, below, or within these transitional beds to mark the position of the post-Knox Unconformity. Another possibility is that the "transitional beds" represent uneroded beds of uppermost Prairie du Chien which are in other areas eroded along the Unconformity. Alternatively, however, the "Lower Glenwood” sediments may simply represent older Glenwood strata that filled erosional channels on top of the Prairie du Chien and post-Knox Unconformity. 44 Following the development of the post-Knox Unconformity Middle Ordovician seas advanced on the craton and began sedimentation of the St. Peter sandstone (in the southwestern part of the basin and farther west) and then Champlanian carbonates. Sand Source Syrjamaki (1977) believed that several areas might be the source of the Prairie du Chien sands. First, the Canadian Shield may be the principal source. The exposure of the gneissic and granitic rocks there would have permitted weathering and erosion to produce the sand. A second source could be the Wisconsin Dome which had rock similar to those of the Canadian Shield. A third source to be considered would be the exposed Precambrian and Cambrian sandstones in the Lake Superior and Upper Peninsula region (i.e., the Jacobsville Sandstone; Munising Formation, and possibly, Trempealeau Formation). These could have been eroded and reworked to form the sands of the Prairie du Chien. Study of Recent sands as indicators of provenance (Blatt, l967; Basu et a1., 1975; Young, 1976) suggest that source rock determinations may be made on the nature of quartz grains, proportion of feldspar and rock fragments, and heavy mineral types. Sands derived from plutonic sources are believed to contain higher proportions of monocrystalline. non-undulose quartz grains, while sands from metamorphic sources are believed to contain significant amounts of polycrystalline, undulose quartz. Feldspar and rock fragment types may also be used as provenance indicators by use of composition and nature. 45 The sands of the Prairie du Chien Group appear to be multi-cycle in nature, derived possibly from pre-existing sandstones. The quartz grains are predominantly monocrystalline, non-undulose grains. However, undulose and polycrystalline quartz is also occasionally observed. Feldspar comprises less than 1% of the framwork grains. Rock fragments, likewise, make up less than 1% of the framwork grains. Unstable ferro- magnesian and other ingenous/metamorphic minerals are conspicuous by their absence from the non-quartz mineral suite. Some such grains are observed to possess a high degree of rounding. These characteristics indicate that a pre-existing sandstone was the most likely source for the Prairie du Chien sands. The Precambrian Jacobsville and Cambrian Munising and Trempealeau Formations of the Lake Superior/Upper Peninsula of Michigan are the most likely sources. The Wisconsin Dome and Canadian Shield may have contributed small amounts of sand to the Prairie du Chien sediments. Further work on this topic is still needed. PRAIRIE DU CHIEN FACIES There are two aspects with which to deal when considering the facies relationships of the Prairie du Chien sands. First, the gross lateral facies changes are important to understand in the southern portion of the Michigan Basin where sandstones thin, interfingering, or are replaced in their distribution by correlative shale and carbonate facies; and second, developed within the massive sand of the Prairie du Chien Group are smaller, micro—facies. These relationships should also be studied. Gross Lateral Facies Relations At the beginning of Lower Ordovician deposition in the Michigan Basin, a widespread regional carbonate shelf existed with deposition occurring from the Appalachians to Wisconsin. This inundation of the Canadian Shield, Lake Michigan and Lake Superior regions, and Wisconsin Highlands progressed to the north and northwest across the Michigan Basin area depositing the Oneota dolomite. A lowering of the sea level brought New Richmond sands to the southeast of the craton, followed by transgression toward the source area in Upper New Richmond and Shakopee time. Although this sand is not continuous across the continent, it is well developed in Wisconsin and in the Michigan Basin. The New Richmond sandstone in the Michigan Basin exists as a massive sand, in places appearing greater than 1000 feet thick (Figure 14). At the southern 46 47 "All! N can: I”? I‘m?“ 50"?! I» a...” . ...... on" o. a Figure 14. Sandstone isopach map of Prairie du Chien Group. 48 edge of sand deposition in the Basin, shale and carbonate sediments were deposited. Apparently, a series of small scale transgressions and regressions occurred producing an interfingering relationship between sands, shales, and carbonates. This is best illustrated in the south and southeast portion of the study area (Figure 15). Still farther to the south and southeast the Prairie du Chien lithologies become dominated by carbonate lithologies (Figure 15). Following the extensive New Richmond sand deposition in the Michigan Basin, much of the area became the site of carbonate deposition again which is represented by the Shakopee dolomite. However, many places of the deep basin do not appear to possess typical Shakopee dolomite perhaps owing to its removal by post-Knox erosion, simply lack of deposition everywhere in the basin, or an interfingering with sands giving a mixed facies not readily distinguished from the New Richmond. The uncertainty of recognizing a distinct New Richmond, as mentioned earlier, led Syrjamaki (1977) to speak of a New Richmond/ Shakopee interval. Several gamma-ray log cross-sections illustrating the contact relationships and log response of the Prairie du Chien Group and Upper Cambrian have been published (Lilenthal, 1978; and Bricker et a1., 1983). Several of these sections are located in this study to illustrate these relationships (Figures 16, 17, and 18). 49 .1: a ‘ ‘ a . 4_—4—— _A w A .——-—4 -_"_.L 1 l - r L. ‘ . - v ‘ J I r ‘ r l . "All! DU CM“ “00' ”C11. IA! or... nu... Figure 15. Facies map of Prairie du Chien Group. [D] Enerq Acqululon Corp Jam Pelrolauom Corp Jam Palroloum Gov? N m I; - Tho Upjohn Co Ohio NW.DevolopmelIl.I1c Dom: Polmloum Corp “TWE'LUWYS; 50:17 W m. N w 5.: .“ NagasaRZn l .5. 2, ‘2 w .3933? 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J”) E ”000 JIOD .3700 \ .7100 \ f?) .9900 f .m 2 \ ' 2; .lotou ‘ i 3 -m\ < C3§f3 . .m .m \ i a ,,.. -- I ._. I V V . I 3— "°°°° Pnirie du Chien - ( * :5 a; \ ‘300 _IO’00 . —‘ L.)— Q “’00 I made 9. Ci 3 E: E NM <\ .0100 <- I l \3 5 ...., é c; PLATE 2 [{waw £7. "m moo STRATIGRAPHIC (57) MM cnoss sacnon c—o i E. 51 Joscw counv ~\ I; -ma / cumwxxoumv \ moo 3 I MIDDLE ORDOVlCIAN € \ i .3 ”no é THROUGH \ E .1 m, P PRECAMBRIAN (p {3 RL Imam. I }— 3 3 / : .nzoo ‘ Scull-l Flaunlull d “WWI : g "”00 ii mm g ; "'°° .moo non .Inoo 1 7 I . > L... . .. 4 GENO l Caulk-mun Lm. ) Pol-mu Cunlalmn ————— J (m lumnlmmly W / onmmmul "no." ~./,._/,_ / .uwa / / SCALE m.ml sum um Vulcan Seal. 0 .nsoo 50‘ J IN‘ .2000 r < . L..~___ _____> h“ . Figure 16. Gamma- ray cross— —section in Michigan Basin. Illustrates litholo ic chan es in Prairi d Chien Group (from Bricker et a1., 1983). g g e u 61,50 3 I Hun! EM oy Corp Well BoyExplomlIon Nonhun MIchiqan ' ' Hun! Enov Co! 1010!“ Supacv 8 WaInoco COILloIIm a. Block :fi?‘u3‘:f?mw gags-lugwgilwcfi Mom-mo la usmn Na 1- lo: p gunning?“ No I z E 5.5: A. an: Crul umIEI gnaw-3:3)“ “um: :46 5. V I? K . I: gfif‘ilzfivz." sn' i:f.,'3.;.l...'" (hm-on 8656 ::fIy:Im'.I::Iu~EI:« m 5 K:l‘lyl emu-«q 0.1;: m 7345' Romy sumac EIIEIIIM I416' mu, 95:1"; :l‘nanon Ins u." ”'"EJEIZ‘J‘ZL?" m.- GINN fl (I‘INAIA FAY 6110(4)’ CAN”! ‘7 p N 1; NHS 1)! [1%ng A, 4N mm: (50 u/ {yrs ”J" q (510 ’f "I arm 75 ‘7‘?" ‘1 V .4 [jug/rs ’90 ‘0 15:0 (90 on” _ A; L ,7 N . 7 ,, .. I . ‘7 v 5 .1) ‘ IIIOO Glaniood . iv , mo VVVVVV K 5000 i g <. \ I I ,_ 2‘ "00 .mo -<" .Ioaoo kfimaw 5 *3 , q ,7 _.\. . .\ ..‘ ‘77 1’ , ? \‘\\\)\\\\\\I.1‘I-u- / M” 1 “m s .00 "7:, f .. .I. ' ' ‘ j; '7 .awu { 1 (4‘ ‘9 K. (3' 7, 1: ga— “I 5 won JPrairie dII Chien <4: .HSOD ”we ( 44> 7 ) «no woo woo ,woo ‘1 . I '3 7 Prune du Chien me (E W, ,m {K g z .ozoo ,A "m 5 % moo {E (C k X 1 <3 1 ,L» g ‘ \ ) I .200 7' *fi—i fl? “ ? VIISOD Ioluo (‘- i (T: r? é é , . , (3. € .m 4} , g gs m g "m“ ’7‘ S?DO ' i { I? 33> Q L Tempe-lean S ”we I “Wm 27 non ? <7 ‘; FOR . . ‘L, ,- A Jm if g <: We 59.. Juan ""’° I i / ’ a ’ ‘1 ffE§;,_ ,uon ‘F— _ ll roo _ ”mo k / >5 8 g L",_ *7 / ~\%— ”00 {J Insoo q\;= "on a; _ q: . — .1200 g 1: /y—— Z,\_ ,i :‘1 > .5 ‘> r: ‘~’—‘ mo Mo K , W i i 6%: ' f lama i 5300 l!“ -7 E ? Trempealeau .Imoo .Il200 . ,9 E?’ q Iowa ( 12”— 5-00 ’ cfi a: «on g ,l % (7.? ‘5 «c, I ——-—4~— % -'1°°° g .vao «5—: I E ’ A a / g: “22., "J 3 low, I /“ am 55 / J2. STRATIGRAPHIC 2; CROSS SECTION E- F i _ moo mum JACKSON com" _7 2 Yo 43:80ma com“ n‘“; , "mo MIDDLE ORDOVICIAN THROUGH PRECAMBRIAN l C? 5 .lle :5_ ‘2: L' Imoo Inca Izaoo / I ‘ moo §—> ? com) {3% ”M E. ; Colllllli LI ._ A) amm- cIIInInIII-I ————— g ,. [mm I I um 35 é DumummI Puncrul ———/,—/— _ (‘4: a mum NI! Hum“ 15 é T“ Wlmnhl sw. .IZSOO “'00 FigUre 17. no». vauI Sui. 0 Gamma-ray cross—section in Michigan Basin. du Chien Group (from Bricker et al., 1983) r—\ Also illustrates lithologic changes in the Prairie [9 M-avulhon OI! Co Mobil Oil Corp McClur a on Ca Dom! Pelroleum Com. Hun! Enarqrd Carp. JEMM Petroleum Cow EE'M filing": (Egrp S‘hallsgi’l £02 1‘ mama- 50 NH II J nun-um Nul Sam-I in: lime: :ngnllllml 5 am»; >4»nyst 6w 2a.. "$1“ ‘9” 7w 3::- Ion" IIZI-Nua In W a. R 9 w 5"“. ' MN. I: H :‘d‘lyzzlul'h1: [ling-EM 6094' :f|y.la‘vhl’rrz (7.5.5.. 9902' KfilyaéuIYNInoaNU-w“; 75' 5 any aiIIIIIIIq imam». II2I‘ K‘l‘lly auIII nq Eisullm met IIIIIy Bul'hllq :ImI-on I4o7' x2, "Luz; (:IIIIII III Iozz‘ “”1 Bv-;::‘:“-;:"-°' 9'5 6M1“ ‘Zmifl 6mm 5177.7: 517%,?! m Ii." , a w 0 A; .5,” .9 a [go 200 7 W :70 g _/30 I“... g ‘7“; 7E 5’ . L?” ,,I ._ ,,, ’I . H- A I . . . r.-. m ,, L; E E > ‘7 < ‘2 . I. k "' “E. I; A s , __ W7 ,H ,4: . . . . . __ (p ,H _\ Aw , 7 M ul\1-«I»l I, GI M E” g Glenwood pdg‘éxrw \,.» »7 "V " ” enwood \ g I. /"—Vf~—- M ” ‘5‘: r ‘ 3’ ;‘:jnv_.om r' "'7/ K: - tin—J— mm II . ;} aéir‘ ~\~_» 5-S'I'rempu_\leau ~""° ‘ \‘T‘ 3 ,. \ 3% mm , / Lg ‘ %, "d‘lkfxlxl-u —\_nno “00 \ 4?; Z F /'/€ “”0 <" m,“ g... . . « ' Prairie du Chien é ‘\ i). u . ,/§ " ‘” A > i ,> ,3,“ Unconformn . ' f I , My} 5 _mw '“ ":9 f m, ’ ‘ 1:; k .mm g .Iosuo 5; ,Ioam) ”00 ,uoc i, l . IOSDU \ wL~~—:;—~ 5 2' 01 g N Rx“? Anne 3000 I900 7 .IOEOO i 3100 ‘I' 7 “ * ES: :— ! ‘5 1:3 ”7"” - moo moo 8;?— 4‘3?) .Imo ' , ” "W Pfuirie du Chien E?” E ‘ ‘1; A“, a» A/\ , moo .IIoo . 4 ~ : €3— INN I PLATE 6 E) 7 l 1' gr V300 I STRATIGRAPHIC 5:3 I CROSS SECTION J—l i i ‘ Imam: couer q» (:7 51- .Io9oc ,Im ‘ 1° 5 b d ”I“? GRAND mavens: cow" 2 -"°° I MIDDLE ORDOVIClAN ~‘°"°° l THROUGH .Iwo l PRECAMBRIAN I . .. _ -. ‘[ .Imou JIOD I > r’ ,, . uom ‘ ‘ % .I’OO 1 MM $5 i .m % f A mm a? ,7 l ”no I L) I ‘ 0° _lIZ “00 IE“: 5) LL.“ <:_\~ __ j?» _mw .» E; .c? a 2 s» f; b .noa b- (a D E saw _. ‘5: ¢;:::§%41 \ I... I. .. L I 5 ”300 g 2",“ .Im .' Pen-.m- coIIlIuIImI ______ “fin—T, / . ( Ever-emu warmly W {) ~ »_ —__-‘ (,4 Olga-IIIIWI PWIEMUI +1,— Eb ' I—IuwIwme W _=—‘ _..—W « » SCALE " Mfl/ r,,__, "w” " \ffi "guardian 32:: me— ,1" % ~°~ a . ‘5:— . e. mm: 5‘... % IIIoa a, _ _ r, ~ I], W Jane \A, (g : w 2) (f I E— %3; mm J.” I00 1? A: Tmmpenluu fl- : f" Figure l8. Gammajray cross—section in Michigan Basin. Again, illustrates the lithologic changes in the Prairie du Chien Group (from Bricker et al., l983). 53 Facies Within the Prairie du Chien Sand Elsewhere in the Michigan Basin the sandstones of the Prairie du Chien Group exhibit several interesting micro-facies developed within the massive sand sheet. Based on the characteristics of lithologies, sedimentary structure, trace fossils, etc., the most reasonable facies model for these micro-facies in the Prairie du Chien appears to be an offshore barrier-bar system. During the extensive deposition of the New Richmond sandstone, sand influx into the Michigan Basin was very great. The currents were apparently strong enough to preclude the development of deltaic facies to the north closer to the sand source. Rather, a widespread massive sand sheet formed over the Michigan Basin. Presumably sediment influx into the Michigan Basin kept pace with the subsidence of the Basin producing an equilibrium situation. Water depth was therefore probably fairly shallow with restricted to normal marine depositional environment indicators present in the Prairie du Chien sands. In some instances, the sands are extensively bioturbated, with the feeding movements of organisms completely obliterating any depositional sedimentary structures. These burrows are typically horizontal feeding burrows, but other burrow types are present. Vertical Scolithus burrows have been observed (Plate 1) and in one instance a Diplocraterion burrow (Plate 2) was observed. These vertical burrow types suggest that very shallow water organisms were present and in the case of Scolithus burrows an intertidal setting may be even suggested. On the other hand, horizontal burrows suggest deeper water 54 Plate l. Scolithus burrows in Prairie du Chien sandstone. Sample is from Glide l-25 well core, Missaukee County, from approximately l0,573' 6" in depth. Plate 2. 55 Diplocraterion burrow, in Visser 3-35 well core, Missaukee County. Approximate depth of sample is l0,879'. Also note Scolithus burrows and well indurated nature of the sample. 56 environments (Rhoads, l975). Typically, the vertical burrows are more extensively cemented with silica overgrowths than the surrounding sand. These burrows are readily distinguished from the surrounding sediment by their lighter, whitish color and well indurated character. Sedimentary structures also suggest that the sands were deposited in a shallow, restricted to normal marine depositional setting. In places, the Prairie du Chien sandstones are horizontally laminated while other sandstones possess low to medium angle cross beds. Shallow, high energy depositional environments could probably create these kinds of bed forms. Figure l9 illustrates how the lithofacies observed fit into the suggested facies model for the Prairie du Chien sands. Lagoonal Facies. Lagoonal Facies are consistently greenish to green-gray to green-brown sands. These sediments are usually greatly bioturbated, with Scolithus burrows commonly observed. The sediments are fine-to-coarse-grained owing to the low energy depositional envi- ronment plus spillover from barrier-bars. These sands are typically glauconitic, with some finely disseminated pyrite observed occasionally. The typical lithologies of the lagoonal facies are siltstones and silty-sandstones (Plate 3). Near-shore Facies. The near-shore facies is fine-to-coarse- grained, also a consequence of normal sedimentation, sorting, and spillover from barrier-bars. However, they are light in color, usually white to yellow to beige and extensively indurated with silica cement. 57 .ANmm— .>.m_._.wm EOLHV Uwuambmv PmUOE mmwumw LmnIwaLLmn mLocmn—Jpo we :prmLHmsp—H .m— mLzmwm $.22 umozmtollv m a... 442000 $63. $64» .330 :30 mummy; \\ 53.35 $3.335 .26.. com 58 Plate 3. Glauconitic sandstone in Prairie du Chien Group. This sand is interpreted to represent a restricted lagoonal depositional environment. Note abundant Scolithus burrows and some pyrite. Sample from Roseville Gun Club "B" l-l7, Roscommon County from approximately ll,644' depth. 59 The light color and lack of glauconite suggests that they are not restricted lagoonal sediments, but rather they were deposited on the oceanward side of a barrier-bar in contact with open marine waters. Again, Scolithus burrows are observed and low to medium angle cross beds are present. The lithologies of the nearshore facies range from silty sandstones to quartz arenites. Orthoquartzities may also be observed (Plate 4). Offshore Facies. This facies is believed to represent the typical Prairie du Chien sediment when it was deposited in the Basin prior to the effects of reworking and sorting. These sands are generally fine- to-medium—grained but some coarse grains are observed occasionally. These sediments are light colored, white to yellow to beige, and again, greatly indurated with silica. Sedimentary structures are generally absent but some sand laminations are present. Also, no trace fossils are evident in this environment. The lithologies of the offshore facies (Plate 5) range from silty sandstone to orthoquartzities. Barrier-bar Facies. This facies is characteristically coarser than the offshore facies. The higher energy depositional environment has winnowed most of the fine sediments while reworking the coarse sediments. The residual sand is better rounded, sorted, and coarser than any other sediments. These sandstones are generally without traces of fossils. High-energy, medium-angle cross-beds are also observable in this facies. The lithologic composition includes quartz arenites. 60 Plate 4. Near-shore sandstone in Prairie du Chien Group. This sand is interpreted to represent near-shore sedimentation of an open marine environment. Note Scholithus burrows. Sample from Gernaat 2-19, Clare County, from approximately 10,475' depth. 6l Plate 5. Tight, fine-grained sandstone of Prairie du Chien Group. This sand is interpreted to represent off- shore, open marine sedimentation. Note small, black "dead" oil blobs. Sample from Dalrymple l-16, Roscommon County, from approximately ll,070' depth. 62 It is interesting to note that there may be some sort of basin (tectonic) influence upon the develOpment of certain types of Prairie du Chien sandstone facies. However, with the sparse amount of data present any discussion would be speculative in nature. As more data become available some relation between Prairie du Chien sandstone facies and structure might be tested. PRAIRIE DU CHIEN PETROLOGY Mineralogy and Lithology The lithologies of the Prairie du Chien Group sandstones are highly variable ranging from siltstone, silty sandstones, quartz arenites, orthoquartzites, dolomitic sandstones to sandy dolomites. However, some outstanding petrologic characteristics can be described in the sands. The sands of the Prairie du Chien are mineralogically dominated by the presence of quartz grains. The quartz grains are typically monocrystalline exhibiting unit extinction. However, some undulose quartz grains and occasional polycrystalline quartz grains are present. Overall, quartz ranges in abundance from 43% to 95%, this was determined through point counting of over 50 thin sections. The dolomitic sands and sandy dolomites contain floating quartz grains in a dolomitic matrix (Plate 6). On the other hand, many examples of orthoquartzites are observed. These sands contain greater than 90% quartz grains with silica cement completely closing pore space (Plates 7, 8, and 9). Other framework grains include feldspar plus gneissic and schistose rock fragments. These framework grains generally comprise less than l% of the matrix. Grain shapes are also highly variable in the Prairie du Chien sands. Grain sphericity ranges from oblong and ovate to nearly 63 64 Plate 6. Photomicrograph of sandy-dolomite sample from McCormick 2-27 well core, Osceola County. From an approximate depth 9841'. Photograph frame is 2.5 mm x 3.8 mm. Some grains are identified as follows: q= quartz grain; d= dolomite matrix. 65 Plate 7. Photomicrograph of tight sandstone from Visser 3-35 well core, Missaukee County, and from approximately 10,843' 7" depth. Photograph frame is 2.5 mm x 3.8 mm. 66 Plate 8. Photomicrograph of tight sand with syntaxial silica overgrowths from Fruedenberg l-3l well core, Osceola County, and from approximately 9657' depth. Photograph frame is 1.0 mm x 1.5 mm. Labelled grains are indicated by: q= quartz grain; O= syntaxial silica overgrowth. 67 Plate 9. Photomicrograph of tight sandstone sample from Roseville Gun Club "B" l-l7 well core, Roscommon County, and from approximately ll,772' depth. Photograph frame is 1.0 mm x 1.5 mm. Quartz grains are indicated by the letter q. 68 spherical, with most grains ovate to nearly spherical. Grain roundness ranges from angular to rounded, with most from subangular to subrounded. Grain sizes are also highly variable, depending on: (1) distance from source; (2) facies; and (3) diagenetic processes. As expected, farther south in the study area (Newaygo County) the sand grains are generally smaller than to the north. Here, the sand grains occur in the fine sand size fraction, however some medium size grains are also observed. To the north, however, grains are observed to range mostly from fine to medium sand sizes. In a few instances, some cross-bedded sandstones were observed to possess 2 mm sand grains. The type of depositional facies, as described earlier, also appears to effect grain size through differences in energy of the depositional environment. The lagoonal and offshore facies described already gen- erally have poorly sorted sediments with a wide range of grain sizes. These depositional environments characterized by lower energy condi- tions would not have been winnowed by strong water currents. On the other hand, the near shore and barrier-bar facies would leave coarser sediments reflecting their higher energy conditions. Extensive silica cementation in the Prairie du Chien sandstones has produced grains which appear coarser because of syntaxial overgrowth. Heavy minerals in the Prairie du Chien sands are infrequently observed. The most often observed heavy mineral is rutile, occurring in a needle-like form. Other observed heavy minerals include tourmaline and an occasional biotite flake. 69 Prairie du Chien sandstone matrix is also highly variable in abundance and mineralogy. Clay is present between the framework grains in many of the sandstones observed. The overall abundance of clay, determined by point counting, ranges from 0% to 35%. Typically, however, clay constitutes 5% to 10% of the clastic matrix. Clay is observed in some instances to be associated with presence of pressure solution and sutured framework grain contacts. In other instances, clay is observed as authigenic clay rims on framework grains. Clay mineralogy is also variable. X-ray diffraction data reveal that several clay minerals are present in the Prairie du Chien sand- stones. Clay separations were prepared from several of the porous and friable sand samples. In each sample, illite was present in some quantity. However, kaolinite and chlorite were sometimes observed to be present with the illite. The depths and temperatures from where the Prairie du Chien sandstone samples were taken preclude the existence of smectite and vermiculite type clay. Several cement types are present in the Prairie du Chien sand- stones. The most abundant cement type is syntaxial silica overgrowths (Plate 8 and 10). In many instances, silica cementation is very perva- sive and produces very dense, tight sandstones. In these sandstones, effective porosity has been reduced essentially to zero. Typically, fine-grained poorly sorted, quartz sandstones have been observed to be more extensively cemented than are the coarser sandstones. The reasons for this are not altogether clear, but probably are related to the initiation of pressure solution in fine-grained lithologies, as previously suggested by Heald (l956) and Thomson (1959). 70 Plate 10. Photomicrograph of Prairie du Chien sandstone with syntaxial silica overgrowths. Sample from Dowker 2-21 well core, Otsego County, from approximately 7908' depth. Photograph frame is 1.0 mm x 1.5 mm. Labelled are: q=quartz grains; O= syntaxial silica overgrowths. 71 Clay minerals also appear to have acted as cement in some of the sandstones, but such sandstones are very friable and possess good porosity. Dolomite cement is also present in the Prairie du Chien sandstones. Its distribution is erratic and somewhat problematic as it is usually observed in the upper portion of cores, close to the top of the Prairie du Chien. However, when dolomite cement is present it completely fills the pore spaces. Such dolomite cement is commonly coarsely crystalline, anhedral and is characterized by undulose extinction. The dolomite crystals are usually interlocking and very tight, with no observable porosity between them (Plate ll). The distribution of dolomite cement in the Prairie du Chien sand- stones suggests several possible origins for the dolomite. First, the dewatering of the overlying Glenwood and/or "Lower Glenwood" formations may represent a local source for the carbonate. Second, during sand deposition, some carbonate may have been forming also, filtering into the sands and becoming cement. And third, the dolomite cement may represent remnant Shakopee dolomite that was later significantly reduced in volume by pressure solution, and therefore is observed as dolomite between grains. Further work is needed here. The porosity in the Prairie du Chien sandstones is highly variable. Overall, the growth of silica cement has the most influence on the loss of sandstone porosity. The porosity observed in the sandstones is exclusively intergranular and appears associated with the presence of clay minerals. Pores are typically less than 0.25 mm in diameter. 72 Plate ll. Photomicrograph of Prairie du Chien sandstone with dolomite cement, from Gilde l-25 well core, Missaukee County, from approximately 10,547' depth. Photograph frame is 1.0 mm x 1.5 mm. Dolomite cement is indicated with the letter d, while q indicates quartz grains. 73 Lithologic Descriptions A number of selected representative thin section descriptions are presented in Appendix C of this report. These demonstrate a wide variety of lithologies present in the Prairie du Chien Group sandstones. Four types of sandstones based on these thin sections are described below: (1) a sandstone tight with syntaxial silica overgrowths; (2) a sandstone showing pressure solution; (3) a sandy dolomite; and (4) a sandstone with some porosity. Sandstones tight with syntaxial silica overgrowths are a very common lithology in the Prairie du Chien Group. A representative sample of this is illustrated in Plate 12. This sample is from the Roseville Gun Club "B" l-l7 well core, Roscommon County, from a depth of approximately ll,772'. Quartz is the predominant framework grain and comprises over 95% of the sample. Other framework grains include feldspar and rock fragments, but together they account for less than l% of the sand. The remaining portion of the sample is silica cement. Mean grain size is 0.20 mm. Grain shapes range from subangular to subrounded. A rounded tourmaline grain is observed. Abundant silica cement is observed. This sample has no observable porosity. The effects of pressure solution are also observed in some of the sandstones of the Prairie du Chien (Plates l3 and 14). This sample is from a depth of lO,l66'Er' in the Bruggers 3-7 well, Missaukee County. Quartz predominates the framework grains comprising 90% of the sample, and is observed to be mostly monocrystalline, non-undulose in nature. Rock fragments and feldspar make up less than 1% of the framework 74 Plate 12. Photomicrograph of sandstone tight with syntaxial silica overgrowths from Roseville Gun Club "B" l-l7 well core, Roscommon County, from approximately ll,772' depth. Photograph frame is 2.5 mm x 3.8 mm. The grains are predominantly quartz, with one tourmaline grain observed in the center of the photomicrograph. 75 Plate 13. Photomicrograph of sandstone in the Prairie du Chien Group illustrating pressure solution. Sample from Bruggers 3-7 well core, Missaukee County, from approximately 10,167' depth. Photograph frame is 1.0 mm x 1.5 mm. Note clay between grains and the sutured grain contacts of framework grains. Quartz grains are indicated by the letter q. 76 Plate 14. Photomicrograph of Prairie du Chien sandstone framework grains with sutured contacts because of pressure solution. Sample from Brinks 1-3 well core, Missaukee County, from approximately 10,785' depth. Photograph frame is 1.0 mm x 1.5 mm. The letter q indicates quartz grains. Note clay between framework grains. 77 grains. Mean grain size is 0.32 mm, and the sorting is considered to be poor. Sand grains are subangular to subrounded. There is no observable porosity. Clay is abundant, constituting 10% of the sample. Grain edges appear sutured probably due to pressure solution. The most interesting lithologies in the Prairie du Chien sandstones are the sandy dolomites (Plate 6). A good example of this is from 9841' depth in the McCormick 2-27 well, Osceola County. Monocrystalline, non- undulose quartz is the most abundant grain type. However, these grains are "floating" in a dolomite matrix. Quartz makes up only 34% of this sample. The mean grain size is 0.26 mm, and they are subangular to subrounded in shape. The dolomite is medium to finely-crystalline, anhedral, and tightly interlocking, with no observable porosity pres- ent. This lithology might be interpreted by some to represent typical Shakopee dolomite of the Prairie du Chien Group. The only other exam- ples of this type lithology were observed in the Fruedenberg 1-31 and Gray 1-31 well cores (also in Osceola County). Cuttings samples of the Anderson 1-8A and Michigan Consolidated Gas Co. 1-9 (Newaygo County) indicate that dolomite lithologies are also present. Porous sandstones are also observed in the Prairie du Chien Group. Plate 15 is an example of this. This sample is from 10,831' in the Workman 1—31 well core, Missaukee County. Quartz is the predominant framework grain making up 93% of the sample and is observed to be mostly monocrystalline, and non-undulose. Mean grain size is 0.35 mm. The sorting is considered to be fair. Grains are subangular and sub- rounded. Porosity is measured by point counting to be 3%, however, 78 Plate 15A. Example of isolated, clay-lined pores in Prairie du Chien sandstones. Sample is from Workman 10-31 well core, Missaukee County, from approximately 10,831' depth. Photograph frame is 1.0 mm x 1.5 mm. Plate 158. Same as above, except under uncrossed nicols. Labelled are: q= quartz grains, p= pore. Note clay rims on framework grains. 79 80 this figure appears to be low. Pores appear to be clay-lined. Some dolomite cement is observed in this sample. Plate 16 illustrates clay-line pores and this sample is also from the Workman 10-31 well core, but from approximately 10,963' depth. Sedimentary Structures Many sedimentary structures are observed in the Prairie du Chien sandstones. These features include: (1) low angle cross-beds (Plate 17); (2) laminations (Plate 18); (3) cross-laminated sandstone (Plate 19); and (4) some graded bedding. 81 Plate 16A. Example of isolated, clay-lined pores in Prairie du Chien sandstones, from Workman 10-31 well core, Missaukee County, from approximately 10,963' depth. Photograph frame is 1.0 mm x 1.5 mm. Plate 16B. Same as above, except under uncrossed nicols. Labelled are: q= quartz grains, p= pore. Note clay rims on framework grains. 82 83 Plate 17. Example of low angle cross beds from the Prairie du Chien Group. Sample is from Gilde 1-25 well core (Missaukee County), and from approximately 10,636' depth. 84 Plate 18. Example of laminated sandstone in the Prairie du Chien Group. Sample is from Gilde 1-25 well core (Missaukee County), and from approximately 10,598' depth. 85 Plate 19. Example of cross-laminated sandstone in the Prairie du Chien Group. Sample is from Gilde 1-25 well core (Missaukee County), and from approximately 10,598' depth. PRAIRIE DU CHIEN SANDSTONE POROSITY Sandstone diagenesis has been the topic of much study in recent years, with most emphasis being placed on porosity retention, destruc- tion, and development in relation to hydrocarbon reservoirs. Schmidt, McDonald, and Platt (1977) and Schmidt and McDonald (1979a, 1979b, and 1980) have stated that the amount of primary porosity in sandstones has been greatly overestimated because of the lack of recognition of secon- dary porosity in sandstones. The recognition of porosity types is of utmost importance in petroleum geology in order to understand reservoir history characteristics and quality. The origin of porosity in the sandstone facies of the Prairie du Chien Group in the Michigan Basin is extensively debated at present. Because little previous work has been done on these sands, Opinions concerning the Prairie du Chien sandstone porosity have been divided between two groups [Montgomery (ed.), 1984]. One group believes that the sandstone porosity is entirely retained depositional (primary) porosity. The primary porosity has escaped the detrimental effects that some types of diagenetic processes (compaction, pressure solution, and cementation) have on sedimentary rock pores. Another group, how- ever, believes that secondary porosity development has produced the Prairie du Chien hydrocarbon reservoirs. Secondary porosity is here defined (Schmidt, McDonald, and Platt, 1977; Schmidt and McDonald, 86 87 l979a and l980) as porosity produced by the removal of soluble rock constituents (mostly carbonate minerals) by acidic surface and ground water before effective burial began or after effective burial ended. Between the above two groups, several theories concerning how the Prairie du Chien sandstone porosity was developed, have remained relatively untested. It is hoped that this study might be able to develop some conclusive information to explain the porosity of these sands, and from this an improved exploration strategy might be developed and implemented. The first theory states that the porosity is secondarily developed and is directly related to the downward leaching effects of surface waters during the development of the post-Knox Unconformity [Montgomery (ed.), l984]. The second theory (Syrjamaki, l977) states that basinal fluids ascending along fractures also produced secondary porosity through leaching of the Prairie du Chien sands. A third theory, somewhat similar to the first (above), contends that porosity may be secondarily developed by descending leaching fluids during the post-Knox erosional event but that production is limited to erosional "knobs" similar to the Copper Ridge (Cambrian) production in Morrow County, Ohio (Whiting, l965; and Dolly and Busch, l972). These three theories require the presence of soluble sedimentary rock constituents and the movement of fluids with sufficient acidity to dissolve these constituents. 88 A fourth theory (Stelzer, 1982) postulated that porosity in the Prairie du Chien sands is retained depositional (primary) porosity which was preserved by the presence of clay minerals presumably inhibiting the nucleation and/or growth of pore-occluding silica cement. A fifth theory [Montgomery (ed.), 1984] suggests that detrital chlorite rims (girders) hold apart the quartz sand grains thereby reducing the effects of silica cementation by pressure solution. In order to establish which theory (or theories) is/are correct and to ascertain what geologic factors controlled the origin of the present porosity, it is necessary to first characterize the porosity as either primary or secondary. Following this, one may attempt to explain porosity development and distribution using geological phenomena which is considered to be most reasonable. Discussion of Secondary Porosity In recent years, secondary porosity has been considered more prevalent in sandstones than previously thought. In some instances secondary porosity forms the predominant type of porosity in hydro- carbon reservoirs. Schmidt and McDonald (l979a and 1980) have clas- sified secondary sandstone porosity types into five classes, each of which can be recognized in thin-section. The five genetic-textural classes of secondary sandstone porosity can be differentiated on the basis of process of origin and textural relations (Schmidt and McDonald, l980; Figure 20 of this report): 89 porosity_created by fracturing--this type includes any newly formed fractures including those created by stresses resulting from the shrinkage of rock constituents or whole rocks; shrinkage porosity--this porosity type is formed through the dehydration and/or recrystallization of a number of minerals such as glauconite and hematite. Shrinkage fractures are not included here, but in the above textural class. Shrinkable constituents occur in rocks as framework grains, parts of grains, matrix, authigenic cement, or authigenic replacement. It perhaps should be mentioned here that shrinkage porosity which occurs in the epigenetic dolomitization process of limestone according to some workers is not under consideration here as the Prairie du Chien dolomite (matrix here) is consid- ered early diagenetic in origin and therefore preconsolidation where any potential shrinkage would not be manifest as voids in the non-rigid carbonate muds; porosity created by dissolution of sedimentary material--this type of porosity results from the selective removal of soluble grains and/or soluble matrix. The dissolution of carbonate constituents is by far the most common form of this type of secondary sandstone porosity; porosity originating from dissolution of authigenic cement-- this type of porosity is possibly the most important textural class of secondary porosity developed in sandstones. The majority of dissolved cements consist of the mineral calcite, dolomite, and siderite; y———. lllwl I ‘llo.’ 9O FRACTURING 1 » ‘ SHRINKAGE .- n .. .b "O .I Carbonate or SLHiate fir .Matrix 0“?“2 Porosity grams "/ Soluble replacement material Figure 20. Genetic classes of secondary sandstone porosity (after Schmidt and McDonald, l980). 91 porosity resulting from dissolution of authigenic replacive minerals--this type also forms a significant portion of secondary porosity in sandstones. It is formed by the selective dissolution of soluble minerals, dominantly calcite, dolomite, and siderite that previously had replaced sedimentary framework constituents, matrix, and/or authigenic cements. Combinations, or hybrids, of these pore classes may also occur in sandstones (Figure 2l; Schmidt and McDonald, l980). Schmidt and McDonald (l979a and l980) further recognize five types of secondary sandstone porosity textures. These pore textures can be differentiated in sandstones and was based, in part, on the nomenclature used to describe carbonate pore textures (Choquette and Pray, l970). These groups include the following (Schmidt and McDonald, l979a and l980): l. intergranular pore textures--this includes pores between grains. The pores may be lined by cement. Three types of intergranular pore texture are observed: (a) regular intergranular; (b) reduced intergranular; and (c) enlarged intergranular. oversized pore textures--this includes pores that are larger than adjacent grains by a factor of l.2. This does not include fracture porosity. Two types of oversized pore textures are described: (a) oversized fabric-selective; and (b) oversized cross-cutting. 92 DEPOSITION AUTHIGENESIS DISSOLUTION . Hybrid pores Primary Incomplete of primary 8: POYOSIIY cementation secondary origin I... *9 0 “Linda . C , Hybrid secondary Primary ementatlon pores of complex porosuty 8: replacement origin 4:) <2 4/T\ \ng .349: [11mm Carbonate Quartz grains |:] Porosity Figure 21. Textural development of hybrid pores (from Schmidt and McDonald, 1980). 93 3. moldicApore textures--this pore class shows the outline of dissolved rock constituents. Three types of moldic pore textures are recognized: (a) grain molds; (b) cement molds; and (c) replacement molds; 4. intra-constituent pore textures--this includes all pores contained within the sedimentary rock constituents. Four types have been recognized: (a) intragranular; (b) intra- matrix; (c) intra-cement; and (d) intra-replacement; 5. fracture pore textures--this includes all parting or separation by fracturing of a rock. Three types of fracture pore textures are recognized: (a) open rock fractures; (b) open grain fractures; and (c) open intergranular fractures. Recognition of secondary sandstone porosity is very critical in determining what factors controlled porosity deveIOpment. However, as stated previously, secondary porosity has been little recognized in sandstones possibly owing to its misidentification as primary porosity (Schmidt, McDonald, and Platt, l977; and Schmidt and McDonald, l979a, l979b, and 1980). As a consequence, Schmidt and McDonald developed a list of criteria used to recognize secondary sandstone porosity (Figure 22; Schmidt and McDonald, l980). To help in recognition of these criteria, Schmidt and McDonald recommend vacuum impregnation of sandstone samples with blue stained epoxy. The carbonate minerals calcite, dolomite, and siderite are the most commonly affected sedimentary rock constituents. Feldspar dis- solution also occurs but plays a subordinate role by volume to the (1) Partial dissolution (2) Molds (3) lnhomogeneity of packing and 'floating' grains (4) Oversized pores Figure 22. Petrographi sandstone porosity ( l980). 94 (5) Elongate pores d .- ..... c - u uuuuuu (6) Corroded grains Carbonate or sulphate l ‘ .v ,...' e. . ,- . 'o 'I u... .. ....O D . O .,. ' ' 'Ie . 0 ~‘ ..I'e. ‘ ('e ’e.°u - on. e ' .0 o". '0 h ' I l .t.'e‘ e o 3 no. ' l .' elu' ...'..n “:I.-- -‘ o." I I."°"' e p.oo| '0 '.IUI... ,cII. . '0'..... . a ._o.. .' - l ' (7) Honeycombed grains ''''' 00000 ..... ..... AAAAAAAAAAAAA grains Quartz 333333.51." agains Feldspar grains (8) Fractured .____1 . Porosity c criteria for recognition of secondary after Schmidt and McDonald, amount of carbonate dissolution in secondary sandstone porosity. Most other minerals are not dissolved significantly enough to produce an appreciable amount of secondary sandstone porosity (Figure 23; Schmidt and McDonald, l980). Secondary sandstone porosity may occur anywhere in the Earth's crust. Following the nomenclature of Choquette and Pray (l970), Schmidt and McDonald (1979a and l980) described three diagenetic environments, which include: (I) diagenesis before effective burial in the environment of deposition (eogenetic); (2) diagenesis of any depth of burial above the zone of metamorphism (mesogenetic); and (3) diagenesis during exposure following a period of burial (felo— genetic). Further, Schmidt and McDonald (l979a, l979b, and 1980) pointed out that most secondary sandstone porosity is developed during the deep burial of rocks (mesogenetic environment) and is possibly closely related to the maturation and migration of hydrocarbons. It has been shown empirically (Tissot and Welte, 1978) that during hydro- carbon generation, significant amounts of carbon dioxide may also be produced. Additional C02 in subsurface brines would adjust solution pH's significantly enough to cause the dissolution of carbonate and feldspar minerals. In this way, the migration of hydrocarbons and development of secondary sandstone porosity may occur simultaneously. To test the role that secondary sandstone porosity may have played in the development of Prairie du Chien Group reservoirs, one must first determine sandstone petrology. This subject has been discussed in the previous section. Then, after rock constituents are identified and 96 .Aowm_ .u_m=oouz new “auscum Sacco xgwmocoa meowmccmm xgmucoomm mcwpmmgo mmmmmooga ovumcmmmpa .mm oczmwu $.22: U_Ia52. z. moz52 . .82.... >mm> mEUszoz mmxpo / «02:2 Em; 9.335 mozzz . outmOaSG 51.8 .62.: . mbESm W no 295635 :02: 3.555 52: mtsgoo :02: mtuio \ mozzz . 35.25:"... l ".02.: 02.555: 225 mozi . 02.55%“. zoom tawnwoubmmmuuoomm mmmmmooca ofimzmoso 97 their abundances determined (identifying constituents that would have most likely been affected by dissolution, shrinkage, or fracturing), it may be able to assess the significance of secondary sandstone porosity development. Using the criteria for the recognition of secondary porosity it should be possible to determine if secondarily formed pores are present and what relations pores have with surrounding rock constituents. If these criteria cannot be observed, i.e., those which indicate the presence of secondary sandstone porosity, then some alternative geologic interpretation must be considered to explain porosity in the sands, suggesting what factors may have controlled porosity development. Discussion of Data The presence of secondary porosity in the Prairie du Chien sandstones was evaluated in this study in order to test several of the theories concerning porosity in these sands (already discussed). Several of these theories were based on the presumption that porosity is secondarily formed by either descending or ascending fluids leaching dissolvable rock constituents. Rock constituent shapes, grain edges and contacts, and observable diagenetic effects were observed to test the possibility of secondary porosity development in the Prairie du Chien sands. The framework constituents of the Prairie du Chien sands are predominantly quartz grains with minor amounts of feldspar grains. No detrital carbonate clasts were observed. These framework grains are observed to vary in roundness from angular to rounded; however, 98 most occur in the range of subangular to subrounded. These grain shapes appear to be the result of: (l) transportation; (2) compaction; (3) pressure solution; and (4) silica cementation. These processes also have affected grain sphericity ranging from bladed and oblong to oval. Several diagenetic processes are observed to affect the Prairie du Chien sands. The most pervasive process is the cementation of sand grains with syntaxial silica overgrowths. Silica cementation is observed in many instances and appears to be the process that has the most destructive effects on Prairie du Chien sandstone porosity. Other diagenetic processes include cementation by dolomite cement with occasional embayment of quartz grains by dolomite, and formation of authigenic clay rims of framework grains. No dissolution phenomena were observed to have affected the framework grains of the sands. In all instances, grain edges are very distinct forming sharp contacts with the surrounding rock constituents. In several instances, dolomitic sands and sandy dolomite lithologies were observed. The dolomite crystals are anhedral, tightly interlocking and coarsely, crystalline with undulose extinc- tion. Overall, these lithologies are very tight with no visible porosity. Dissolution of the dolomite was not observed. Several cement types are observed in the Prairie du Chien sands. As previously mentioned, silica cementation has produced in some lithologies, a very dense, tight sandstone. In many instances, the sandstone porosity has been completely occluded by silica cement. Dolomite cement is also observed in the sands; however, it is secondary in abundance to silica cement. Dolomite cement, when present, is also observed to completely occlude sandstone porosity. A third cement type is clay cement. Some lithologies contain a significant amount of clay between grains with little or no silica or dolomite cement present. Clay mineral species observed in the Prairie du Chien sands include illite (glauconite), kaolinite, and chlorite. The clay cement is presumed to be authigenic in nature. Again, dissolution is not observed to have affected the cements in the Prairie du Chien sands. The amount of porosity in the Prairie du Chien sands is highly variable. Point counting reveals that porosity ranges from O to 8%. However, on compensated neutron porosity logs sand porosity is observed to be as high as 20%. Intergranular porosity is the only type observed in thin-section. The pore shapes and sizes are controlled by compac- tional effects and the shapes of surrounding framework grains and the presence of clay minerals and other types of cements. Pores appear to be clay lined (Plates l5 and l6). Pore size is variable, however usually less than 0.25 mm in diameter. From the grain shape, grain edge, pore geometry and pore location data, secondary sandstone porosity does not appear to be important in the development of the Prairie du Chien sandstone reservoirs. The Prairie du Chien sand constituents are dominated by the presence of quartz framework grains, with significant amounts of syntaxial over- growths present. These two constituents are not soluble enough to appreciably dissolve forming secondary porosity. Carbonate cement, 100 when present, shows no evidence of dissolution. Also the dolomitic sands and sandy dolomites likewise show no secondary porosity devel- 0pment. Overall, porosity in the Prairie du Chien sands does not appear to have been formed by the dissolution of sandstone constit- uents. It appears that the presence or non-presence of syntaxial silica overgrowths in the Prairie du Chien sands is what determines whether the sands are dense, tight and non-porous or friable and porous. As porosity is found entirely as intergranular porosity, and appears to be closely associated with the presence of clay minerals, the data suggest that the Prairie du Chien sand porosity is retained primary (depositional) porosity that escaped the pore occluding effects of silica cementation (Stelzer, 1982). Stelzer believed that clay minerals inhibited the growth of silica cement. Several factors have apparently acted to destroy or retain primary porosity in the Prairie du Chien sandstones. First, compactional effects in the Michigan Basin cannot be overlooked. As overburden stresses increased from sediment loading, the sandstones of the Prairie du Chien were subjected to mechanical and chemical porosity reduction processes. Mechanical compaction, pressure solution and cementation are processes that can significantly alter the amount of primary porosity retained or destroyed in a sand- stone (Houseknecht, I984). Primary porosity may be reduced through mechanical compaction by one-third in some quartzose sandstones from an original porosity of 35% to 50% (Pryor, I973). The two processes of mechanical compaction that reduce porosity are the reorientation l0] and repacking of competent (brittle) framework grains and the plastic deformation of ductile grains like lithic fragments. As the sediment load increases, pressure solution and cementation may close pores, further reducing effective porosity to nearly zero. The process of pressure solution is well documented by Sibley and Blatt (l976). Pressure solution has been studied extensively for some time. Taylor (1950) showed that the number of grain contacts increased with increasing depth of burial as a result of pressure solution. Heald (l956) illustrated that laminae of fine-grained clastic sands are more susceptible to pressure solution than are laminae of coarser-grained sands. It was suggested further that a small amount of clay between framework grains may promote the process of pressure solution (Heald, l956; and Thomson, 1959). Maxwell (l964) suggested a decrease in quartzose sandstone perosity, with increasing burial depth and further suggested that the porosity loss was in part due to intergranular pressure solution. Pressure solution had been considered for years to be a viable source of silica that precipitated as cement in some sandstones. However, Sibley and Blatt (l976) demonstrated that only one-third of the volume of silica cement in the Tuscarora sandstone of Pennsyl- vania can be accounted for by pressure solution. On the basis of that study, many workers have considered pressure solution to be a small contributor of silica to the cementation of sands, and therefore, many have looked elsewhere for cement sources. As observed in many of the samples of the Prairie du Chien sand- stones, the sandstones are highly indurated with silica cement in the l02 form of overgrowths. Still, some effective porosity is observed in some of the sandstones. Compactional differences, even from the sparse sample distribution in this study, can be suggested for the Prairie du Chien snads based on the depth of burial. The sandstones of the Jennings Petroleum discovery well (Anderson l-8A) in Newaygo County show less compactional effects than those sandstones in the deeper basin. Porosity is reported to reach 20% in the Anderson l-8A, with 240 milidarcies permeability [Montgomery (ed.), 1984]. Stuart Jennings (oral communication, 1985) has suggested that silica cementation (and perhaps pressure solution) is less pervasive in the sands of Newaygo County compared to the deeper basin sands. These differences may not be so much related to burial pressure as to the temperature and time of burial. Houseknecht (l984) postulated that for a given grain size, porosity is higher in sandstones of lower thermal maturity. As the Newaygo County Prairie du Chien sands are shallower than the deeper basin sands they should be expected to be less thermally mature (this is of course, assuming a fairly constant geothermal gradient over the Michigan Basin). The effect of pressure solution in these sands is presumed here to account for the difference observed in deeply buried versus shallower sands. It has been proposed (Houseknecht, 1984) that temperature exerts a fundamental influence on the occurrence of pressure solution in sandstones and, hence, porosity loss. Thus, a dichotomy of opinion could exist when this last observa- tion is contrasted to the observation of Schmidt and McDonald (1979a, l979b, and 1980) mentioned previously that secondary sandstone porosity 103 is developed during deep burial. In any event the silica produced by pressure solution may remain locally in the sand and become a source for the silica overgrowths observed in the Prairie du Chien sandstones. Pressure solution effects are frequently observed in the Prairie du Chien sandstones (Plates l3 and l4) and may represent the silica source for the syntaxial overgrowths also observed in the sandstones (Plate 8). Grain size, is a second factor that must be considered important for pore retention in the Prairie du Chien sandstones. Houseknecht (l984) has proposed that at any given sample locality, coarser sands will retain higher amounts of primary porosity than finer-grained sands, even though the coarser-grained sands contained a greater volume of cement. In general, this appears to be the case in the Prairie du Chien sands. The offshore facies recognized in this study are generally characterized by fine-to-medium-grained sands which have porosity greatly reduced by pressure solution and silica cementation. On the other hand, the coarser-grained lithologies, like barrier-bar facies and some lithologies of near-shore facies are less cemented, more friable and less indurated with silica. If less thermally mature, coarser-grained sandstones are more porous than thermally more mature or finer-grained sandstones, an ideal region in which to explore for good Prairie du Chien reservoir rocks would be in the northwest portion of the study area. In this region, the sandstones are closer to their source and, therefore, coarser than distal sands, and they are less deeply buried and therefore less thermally mature. The sands in this area would be expected to have 104 retained a significant portion of their primary porosity, escaping some of the pore reduction effects of pressure solution. Also, the southwest portion of the study area offers an excellent area in which to explore for Prairie du Chien reservoirs based on present production in the area and that these sandstones are also expected to be thermally less mature than deeper buried sandstones. A third factor that has apparently played a role in retaining porosity, especially in the deep basin sandstones, is the presence of authigenic clay rims on the sand grains. As noted before, porosity appears closely associated with the presence of clay minerals. On the basis of x-ray diffraction data illite, chlorite, and kaolinite are found to be the only clay minerals present. Clay usually appears as clay rims on framework grains. Stelzer (l982) was the first to con- clude that the porosity observed in the Prairie du Chien sandstones was related to the presence of clay minerals, and this report concurs with that conclusion. The clay rims have apparently acted to preclude the pore reduction effects of silica concentration by inhibiting the nucleation and/or growth of silica overgrowth (Plates 20 and 2l). Fourthly, the presence of hydrocarbons in the sands has also acted to inhibit the pore destroying effects of silica cementation. As the clay rims "coated" framework grains, hydrocarbons also "coated" some grains and inhibited the nucleation and/or growth of silica overgrowths (Plates 22 and 23). The early migration of hydrocarbons along shear fractures (Prouty, l970, l976, 1980, and 1984) into shear folds in the basin might account for production being limited to the uppermost IDS Plate 20A. Close-up photomicrograph of isolated clay lined pore in Prairie du Chain sandstone. Sample is from Dalrymple l-l6, Roscommon County, and from approximately ll,155' depth. Photograph frame is 0.39 mm x 0.60 mm. Plate 20B. Same as above, except under uncrossed nicols. Frame is slightly rotated compared to above photomicrograph. l07 Plate 2lA. Close-up photomicrograph of isolated clay-lined pore in Prairie du Chien sandstone. Sample is from Dalrymple l-l6 well core, Roscommon County and from approximately ll,l55' depth. Photograph frame is 0.39 mm x 0.60 mm. Plate 2lB. Same as above, except under uncrossed nicols. 108 109 Plate 22A. Example of inhibiting effects on diagnesis of the presence of hydrocarbons in Prairie du Chien sandstones. Sample is from Dalrymple l-l6 well core, Roscommon County, from ll,057'4" depth. Note the high degree of angularity of some of the grains, likely brecciated along a fault and offering a porous reservoir rock for the hydrocarbons. Photograph frame is 2.5 mm x 3.8 mm. Plate 22B. Same as above, except under uncrossed nicols. The hydrocarbon is located beneath sand grains on the right hand side of the photomicrograph. IIO Ill Plate 23A. Example of hydrocarbon inhibition on diagenesis of Prairie du Chien sandstone. Sample is from Roseville Gun Club "B" l-l7, Roscommon County, from approximately ll,723'. Note brecciated zone of angular fragments also a "reservoir rock" for hydrocarbons as observed in Plate 22A and B. Photograph frame is 2.5 mm x 3.8 mm. Plate 23B. Same as above, except under uncrossed nicols. The hydrocarbon between grains is best observed in the upper right hand portion of the photomicrograph. IIZ lSO feet of the Prairie du Chien sandstones [Bricker et al., l983 and Montgomery (ed.), I984]. The hydrocarbons may have migrated into these structures before the time of extensive pressure solution and silica cementation of the Prairie du Chien sandstones in other areas. As this study represents a reconnaissance study of the few avail- able samples of the Prairie du Chien sandstones of the Michigan Basin, it is not intended to provide definitive answers regarding the porosity of the Prairie du Chien sandstones. SUMMARY AND CONCLUSIONS The theories about the origin of porosity in the Prairie du Chien sandstones can be tested by observing petrographic character of pore types and geometry, framework grains and their margins, and rock matrix and cement. On a larger scale the observation of cores can also help examine these theories. From these observations it appears that secondary sandstone porosity does not play a principal role in the deve10pment of porosity in the Prairie du Chien sands. In the Gilde 1-25 well (the only producing-well core studied), the post-Knox Unconformity was not observed. No clear cut discontinuity was seen between the Prairie du Chien and overlying "Lower Glenwood" formation. Therefore, there does not appear any support for the con- cept that sandstone reservoir porosity is related to the post-Knox erosional event here, or secondary porosity development by leaching of descending fluids. To date, Prairie du Chien production has been restricted to the uppermost 150 feet of the sand, and is closely associated with structure (Figures 24, 25, and 26). However, porosity is not restricted to structure as previously thought. In 13 of the 14 cores examined, good zones of porosity were observed. The possibility that these sands might also have been hydrocarbon producers if on structure must be considered. 114 115 .aucsou wmxammmwz ZNNP .upmwm canoe” cm cmwzu :u mwcwmgm co Lzopcou weapoacum .vm mcamwu :ON 20 was ~ 0 s. u. ._ o. m 5-. ux¢mt= 32.28 33.2.3“. 32-23» is... 20 z: :50. as: magma: . NN..¢ I II I o. a //I I I III! ‘\ \\\l..l / a \.\\V\ \I I: \ \ \. I \ ~ \ \xknw .nquuIIAIvWIIIuV. ~ ~ ‘\ —\ / I \\ \. \\\ \ , .. , , . veasmvx «an x / / / .. x \ / l/ / . ~ . \ / ’l/ a .. q u - / / . . w \ _ / / . _ .. / / .. . \ «N / on 25.5.: ea $8.33.: / \ ,/ x / 3m... :5055. x . \ c In .9: 5m: /omm. ” . 3h cmwumw 33-32.14 33.23» , / 118 The porosity observed in the Prairie du Chien sands appears to be retained primary depositional porosity that escaped the detrimental, pore destroying effects of silica cementation. Porosity appears entirely intergranular and is closely associated with the presence of clay minerals, like illite, chlorite, and kaolinite. The clay is observed as authigenic clay rims on framework grains. This association suggests that clay minerals have inhibited the nucleation and/or growth of pore-occluding silica cement, as first suggested by Stelzer (1982). This report strongly supports Stelzer's work. Other factors that may have affected the retention of porosity in the Prairie du Chien sands include compactional effects, grain size, and the presence of hydrocarbons. In conclusion, the hydrocarbon potential of the Prairie du Chien sandstones of the Michigan Basin appears good. More data will continue to accumulate with further testing of these strata. Deeper testing of shallow producing structures will remain the exploration strategy employed by explorationists until more data have accumulated to develop another technique. APPENDICES APPENDIX A A DETAILED DESCRIPTION OF THE TYPE PRAIRIE DU CHIEN GROUP APPENDIX A A DETAILED DESCRIPTION OF THE TYPE PRAIRIE DU CHIEN GROUP A deiaiied mcaaaaed aeotion aéiea Stank, 1949 i4 Ahown in Michigan Baain Geoiogicai Society Annuai Fieid Excuaaion, 1960, C. E. Paoaty led.) A description of the Prairie du Chien Group type section, exposed in a quarry on north side of County Highway X in the NW9 NW9 Sec. 31, T.6 N., R.(iW., Elkader Quadrangle, Wisconsin. Description modified after George Stark, 1949, Master‘s Thesis, University of Wisconsin. Canadian Series Prairie Du Chien Group Shakopee dolomite Feet Inches Dolomite gray massive dolomite with some stringers of sandstone; gnarled appearance; in well developed one foot beds ..................... lO -- Dolomite, gray, massive, brecciated throughout ..... -- ll Dolomite, gray, very fine grained, in thin beds separated by green shale partings ........... l -- Dolomite, gray with buff mottling, in beds six inches thick and separated by gray shale ...... 4 6 Dolomite, fine grained, light gray with orange- stained areas ..................... -- 11 Dolomite, gray, fine grained, thinly bedded and with green shale partings; floating grains of quartz sand ...................... 12 -- Dolomite, green, glauconitic, coarse grained ...... -- 6 Dolomite, gray to reddish, fine grained; weathers to irregular surface .................. 7 -- 119 120 New Richmond sandstone: Sandstone, white, weathers brown, in beds 4 inches to 1% feet thick with interbedded fine grained dolomite ................ Oneota dolomite: Dolomite, light buff with dark specks throughout, in beds 3 to 6 inches thick separated by green clay partings .................... Dolomite, gray, fine grained, weathers to irregular surface; some algal structures ....... Dolomite, buff, relatively soft; algal structures profusely developed; in beds 3 to 4 feet thick with stringers of chert throughout; basal foot is weathered chert .................. Dolomite, conglomeratic with dark gray pebbles embedded in buff colored matrix; well bedded with some green shale partings and some clean white quartzose beds several inches thick ......... Sandstone, white, clean quartz grains of medium size; some green specks ............... Dolomite, gray, non-cherty, relatively soft, very massive; encloses some areas up to 15 feet in diameter of fine grained, gray-buff dolomite ..... Dolomite, very fine grained, undulating beds; includes white, gray, and black chert; cavernous . . . . Dolomite, gray to buff, coarse grained; in 4 inch beds ..................... Dolomite, gray to buff to orange colored, massive; includes some white chert and near the top some clay pockets ..................... Feet Inches 4 4 2 2 2 -- 29 4 20 -- 1 8 54 -- 3 4 1 6 25 2 APPENDIX B PRAIRIE DU CHIEN SANDSTONE CORE DESCRIPTIONS APPENDIX B PRAIRIE DU CHIEN SANDSTONE CORE DESCRIPTIONS Brinks 1-3 PN 36786 Sun Exploration T21N R6W Sec. 3 CNNENE Very sharp contact exists between Prairie du Chien and overlying "Lower Glenwood" formation; top of the Prairie du Chien is picked in the core at 10,783' 5". 10,783' 5" to 10,818' 3” sandstone, green to green-gray to gray to orange to orange-brown; fine to coarse grained; quartz sand; silica cement present; friable sand with some porosity; scattered glauconite (?) throughout, but very glauconitic at 10,787‘ 11" to 10,790' 8", 10,794' 7" to 10,799' 3", and 10,812' 11" to 10,814' 1”; laminated in places; vertical burrows observed; iron staining throughout; pyrite is observed at top of Prairie du Chien sand probably associated with erosional event. Bruggers 3-7 PN 34078 JEM Petroleum Corp. T24N R6W Sec 7 NESWNE Top of Prairie du Chien picked in core at 10,157'. The contact with the overlying "Lower Glenwood" formation is gradational. 10,157' to 10,160' sandstone, gray to black to brown to orange; fine to medium grained; coarse grained in places; quartz sand; tight with silica cement; no observable porosity; vertical burrows present; pyrite in top 1 inch of sand. 10,160' to 10,166' 6" sandstone, gray to gray-pink to tan to brown; fine to medium grained; quartz sand; tight sand with silica cement; no observable porosity; vertical burrows present. 122 10,166' 6" to 10,170' 4” sandstone, green to green-gray to gray to brown; fine to medium grained; quartz sand; silica cement; glauconitic (?); laminated; vertical burrows present; shale partings also present. 10,170' 4” to 10,202” sandstone, green to green-gray to gray to pink to orange; fine to medium grained quartz sand; tight with silica cement; little observable porosity; finely disseminated glauconite (?) in places; laminated and cross bedded sand; some shale partings; vertical burrows and bioturba- tions present; iron staining also observed. Dalrymple l-16 PN 34537 JEM Petroleum Corp. T22N R4W Sec. 16 NWNESE 11,012' to 11,052' sandstone, green to green-gray to gray to white to pink to tan; fine to coarse grained; quartz sand; little cement; fair porosity; very glauconitic (?) from 11,012' 9" to 11,046' (corresponds to gamma-ray Kicks on 109); some sand lamination present; some shale partings; burrowed and bioturbated sand; possible dead oil present. 11,052' to 11,157' sandstone, white to yellow to tan to pink to rust/red to maroon; fine to medium quartz sand; well indurated with silica cement; little porosity; no observable clay; good cross bedding observed; some sand laminations also present; burrowed sand; heavily iron stained in places. Dowker et a1. 2-21 PN 35922 Reef-West Bay-Wainoco T30N R1W Sec. 21 NWSWSE Top of Prairie du Chien picked at 7891' in core, but has gradational contact with overlying "Lower Glenwood" formation. 7891' to 7902' sandstone, green to gray-green to yellow to orange to tan; fine to medium grained; quartzose sand; tight sand (in places) with silica cement; fair porosity elsewhere; some clay present; laminations observed, also some low angle cross beds are present; bioturbation is observed. 7902' to 7928' sandstone, white to white—yellow to yellow to tan; fine to medium grained; quartz sand; tight with silica cement, however some scattered porosity is observed; laminated and cross bedded. 123 Fruedenberg_l—31 PN 34558 JEM Petroleum Corp. T17N R8W Sec. 31 SENENE Top of Prairie du Chien picked in core at 9589' 11" (9590'); however, this is not a sharp contact, rather it appears very gradational with the overlying "Lower Glenwood" formation. 9590 to 9595' sandstone, green to green-gray; fine to medium grained; quartz sand; little cement; friable sand; some porosity; glauconiteic (?) (corre- sponds well with gamma-ray Kicks on logs); some lamination present; burrowed and bioturbated; disseminated dead oil observed. 9595' to 9647' sandstone to dolomitic sand to sandy dolomite, white to yellow-white to gray to brown; fine to coarse grained, very coarse in places; quartz sand; little porosity; fairly tight, clean sand; very well indurated with silica cement; scattered porosity appears associated with the presence of clay (glauconite ?); cross bedded and laminated in places; vertical burrows throughout and better cemented than surrounding sediment; some dead oil observed; dolomitic sand in places. 9647' to 9693' 3" sandstone, green to green-gray to green-pink to pink; fine to medium quartz sand; little cement, friable sand; porosity throughout; clay present (glauconite ?); laminated sand; some burrows; traces of iron staining present. 9693' 3" to 9703' 8" sandstone, pink to pink-green to green; very fine grained lithology, sandy in places; sand is quartzose; cement type is undifferentiable; no porosity is observed; scattered glauconite (?) and glauconitic chips; laminated in places. 9703' 8” to 9726' sandstone, white to yellow-white to tan-yellow; fine to coarse grained; quartz sand; no observable porosity; fairly tight, clean sand; very well indurated with silica cement; cross bedded and laminated; vertical burrows observed. 124 Gernaat 2-19 PN 35781 ROM Energy T20N R6W Sec. 19 SWSWNE Prairie du Chien top 10,434' on drillers log 10,435' to 10,438' 6" siltstone, black to gray-black to gray; very fine grained; bioturbated in places; shale partings in places. 10,438' 6" to 10,471' sandstone, gray to gray-green to tan mottled sand; fine to coarse grained; quartz sand; not very indurated, friable sand; some silica cement; scattered porosity, associated with glauconite (?); glauco- nitic (?) from 10,445' 6" to 10,449'; bioturbated and well indurated burrows; shale interbeds and partings present. 10,471' to 10,533' sandstone, yellow to brown to pink, white and gray; fine to medium grained; quartz sand; fairly tight sand with silica cement; some low angle cross beds; laminated in places; well indurated burrows. Gilde et al. l-25 PN 35899 Patrick Petroleum T22N R7W Sec. 25 SESESW 10,540' to 10,542' 4" sandstone, green-gray to gray to grapy-ink; fine to medium grained; quartz sand; tight with silica cement; no observable porosity; finely disseminated glauconite (?); bioturbated; patchy iron staining; possible pressure solution seams. 10,542' 4" to 10,545' sandstone, green-gray to gray to pink-gray to pink to tan; fine grained; quartz sand; finely disseminated glauconite (?); bioturbated. 10,545' to 10,545' 5" sandstone, green to green-pink to pink-gray to pink; fine to coarse grained; quartz sand; silica cement; disseminated glauconite (?); bioturbated. 10,545' 5” to 10,547' sandstone, gray-green to gray to gray-black; fine to medium grained; occasionally coarse grained; quartz sand; silica cement; tight, with no observable porosity; disseminated glauconite (?) sometimes patchy; bioturbated; some iron staining observed. 10,547' to 10,547' 11" sandstone, gray to brown; coarse grained; quartz sand; friable sand with little silica cement; good porosity; vertical burrows are well indurated. 10,547' 11" to 10,549' 4" sandstone, green to green-gray to pink; fine to medium grained quartz sand; silica cement; fair porosity; glauconitic (?); burrowed and bioturbated. 10,549' 4" to 10,550' 9" sandstone, gray to gray-brown to borwn; medium to coarse grained; quartz sand; silica cement; good porosity; vertical burrows are tightly indurated with silica. 10,550' 9" to 10,551' 5" Absent section. 10,551' 5" to 10,552' 10" sandstone, green to green-gray to gray; fine to medium grained quartz sand; silica cement; tightly indurated, no visible porosity; glauco- nitic (?) in places (especially from 10,552' to 10,552' 11"); bioturbated and burrowed. 10,552' 10" to 10,553' 1'' sandstone, green to green-gray to green-orange; medium grained; quartz sand; silica cement; tightly indurated with no observable porosity; disseminated glauconite (?); bioturbated; finely disseminated iron staining observed. 10,553' 1" to 10,554' same as above, but green to green-gray to gray. 10,554' to 10,556' 7" sandstone, gray; fine to coarse grained; quartz sand; very tightly induated with silica; friable in places; no observable porosity; finely disseminated glauconite from 10,555' 8" to 10,556' 2"; vertical burrows; iron staining observed. 10,556' 7" to 10,565' sandstone, green to green-gray to orange-green to pink; fine to medium grained; quartz sand; fairly tightly indurated with silica cement; no observable porosity; disseminated glauconite (?); burrowed and bioturbated. 10,565' to 10,568' 6" sandstone, gray to brown-gray to brown; fine to coarse grained; quartz sand; silica cement; fair porosity; slightly glauconitic (?); vertical burrows are well cemented with silica; bioturbated also; iron stain occurs as blobs. 126 10,568' 6" to 10,575' 10" sandstone, gray to brown; medium to coarse grained; quartz sand; silica cement; good porosity in places; vertical burrows are observed; disseminated iron staining. 10,575' 10" to 10,576' 6" sandstone, green to green-orange; fine to medium grained quartz sand; tightly indurated with silica cement; slightly glauconitic (?); laminated sand; bioturbated. 10,576' 6" to 10,589' sandstone, green to green-orange to gray to pink-gray to pink; medium to coarse grained; quartz sand; silica cement; some porosity; patchy glauconite (?); burrowed and bioturbated. 10,589' to 10,596' sandstone, green to gray-green to gray to gray-pink to pink to brown; medium to coarse grained; quartz sand; silica cement; tightly cement in places, friable and porous elsewhere; disseminated glauconite (?); laminated; burrowed. 10,596' to 10,658' sandstone, white to yellow-white to yellow to orange to pink to pink- gray; fine to medium grained; quartz sand; silica cement; very tightly indurated; no observable porosity; finely disseminated glauconite (?); laminated and cross bedded; vertical burrows observed. Gray 1-31 PN 35800 Willmet Oil and Gas T17N R8W Sec. 31 NENWNW 9564' to 9586' dolomite sand to sandy dolomite; gray to gray-green to pink to white; fine to medium grained; quartz grains; no observable porosity; bioturbated and burrowed; disseminated dead oil observed. Koetje 1-25 PM 34927 JEM Petroleum Corp. T22N R7W Sec. 25 SENWNW Prairie du Chien top picked at 10,653' in core with gradational contact with overlying "Lower Glenwood" formation. 10,653' to 10,679' sandstone, green to green-gray to yellow to pink; fine to medium grained quartzose sand; some silica cement; some porosity observed; glauconite (?) present; bioturbated with well induated burrows. 127 10,679' to 10,692' sandstone, white to yellow-white to yellow to tan; fine to medium grained; quartz sand; tightly cemented with silica; no observable porosity; finely disseminated glauconite; laminated sand; some iron staining present. McCormick 2-27 PN 34536 JEM Petroleum Corp. T18N R8W Sec. 27 SWSENW 9725' to 9773' sandstone, green to green-gray to gray to black to pink; fine to medium quartzose sand; little cement present; friable sand; glauconitic (?) (corresponds well with gamma-ray log response); some shale partings; burrowed and bioturbated; some disseminated dead oil present. 9773' to 9878' sandstone to dolomitic sand to sandy dolomite, green to gray-green to gray to white to yellow-white to tan to pink; fine to medium grained; quartz sand; generally tightly indurated with silica cement but some scattered porosity is observed; some dolomite observed; slightly glauconitic (?); solution seams observed; laminated and cross bedded; some shale partings present; burrowed and bioturbated. Roseville Gun Club "8" 1-17 PN 37409 Newport Petroleum TZlN RlW Sec. 17 ESSWNW 11,631' to 11,704' 6" sandstone, green to green-brown to green-gray to gray; fine to coarse grained sand; very coarse in places; quartz sand; little cement; generally friable; good porosity; abundant clay (glauconitic ?); some low angle cross beds; bioturbated and burrowed; disseminated pyrite; some dead oil present; very glauconitic (?) from 11,636' 8" to 11,640' 6" and 11,644' to 11,645. 11,704' 6" to 11,772' sandstone, yellow to white to yellow-white to yellow-green; fine to medium grained; quartz sand; heavily cemented with silica; very tight sand (little or no porosity); little observable clay, however some glauconite scattered, with associated porosity low and medium angle cross beds; some laminations present; very intensely burrowed; some bioturbation. 128 Visser 3-35 PN 34606 JEM Pet., Woods Pet., & Joutel Pet. T22N R6W Sec. 35 NWSESE 10,836' 1" to 10,967' sandstone, white to white-yellow to yellow-tan to tan-gray to pink; fine to medium grained; some coarse grained sections; quartz sand; tight sand; well indurated with silica cement; no observable porosity; scattered occurrence of glauconite (?); some laminations and cross beds; vertical burrows and bioturbation; Diplocraterion burrow observed at 10,879'; some shale partings present; finely disseminated iron staining throughout. Weingartz 1-7 PN 34611 JEM Petroleum Corp. T17N R4W Sec. 7 NENENE 10,747' to 10,795' sandstone, green to green-black to tan; fine to medium grained; quartz sand; generally friable; spotty porosity with silica cement; glauconitic in places, especially from 10,776 to 10,787; laminated; some shale partings present; burrowed. 10,795' to 10,848' sandstone, white to pink; fine to medium grained; quartz sand; heavily cemented with silica; little or no porosity, tight sand; some shale partings; bioturbated and burrowed. 10,848' to 10,855' sandstone, green to green-gray to tan-gray to gray; fine to medium grained; quartz sand; friable porous sand; little silica cement; glauconitic in places; burrows present and well cemented with silica. Workman 10-31 PN 34357 JEM Petroleum Corp. T22N R6W Sec. 31 SWNENE Top of Prairie du Chien picked in core at 10,738'. Contact with overlying "Lower Glenwood" formation. 10,728' to 10,733' sandstone, green to green-gray to pink-gray; fine to medium grained; quartz sand; fairly tight with silica cement; finely disseminated glauconite (?); burrowed; some finely disseminated iron staining observed. 129 10,733' to 10,783' Absent section. 10,783' to 10,838' sandstone, gray to yellow to tan to pink; fine to medium sand; quartz sand; fiarly tight and dense with silica cement; porous and friable section from 10,801' 6" to 10,810'; few shale partings observed; some lamination present; vertical burrows and some bioturbation. 10,838' to 10,842' Absent section. 10,842' to 10,956' sandstone, white to gray-white to gray-yellow to yellow to pink-gray to pink; fine to medium grained; quartz sand; silica cement present; highly variable porosity in this section; fairly friable and porous sands; laminated sands; some thin shale partings; vertical burrows observed; finely disseminated iron staining. 10,956' to 10,971' same as above but becomes very rust colored. 10,971' to 11,018' sandstone, same as above, however, loses rust color becoming yellow to white to yellow-green again; some cross-bedding. APPENDIX C DESCRIPTION OF REPRESENTATIVE THIN SECTIONS OF PRAIRIE DU CHIEN GROUP SANDSTONES OF THE MICHIGAN BASIN APPENDIX C DESCRIPTION OF REPRESENTATIVE THIN SECTIONS OF PRAIRIE DU CHIEN GROUP SANDSTONES OF THE MICHIGAN BASIN Well: Brinks 1-3 Sample Depth: 10,785'3" Grain Mineralogy: predominantly quartz with unit extinction; monocrystalline Grain Size: 7’: .54 mm o = .23 mm Sorting: poor Rounding: subangular to subrounded (mostly subangular) Porosity: no observable porosity Sedimentary Structures: some compactional alignment of grains Accessory Minerals: clay present between grains Comments: tight sand; pressure solution effects present; silica overgrowths observed; sutured grain contacts; small amount of dolomite cement present; possibly some "dead" oil; less than 1% feldspar + rock fragments; 92% quartz grains (+ silica) + 8% clay. 130 131 Well: Brinks 1-3 Sample Depth: 10,793' Grain Mineralogy: quartz predominantly, with unit extinction; monocrystalline Grain Size: X'= .24 mm o = .10 Sorting: poor to fair Rounding: subangular to subrounded Porosity: fair porosity Sedimentary Structures: vague lamination, possibly compactional in nature Accessory Minerals: some clay present Comments: small amount of dolomite cement present; silica overgrowths observed; clay in pores appears to have inhibited silica cementation; 84% quartz (+ silica) + 6% clay + 3% dolomite cement + 7% porosity. Well: Bruggers 3-7 Sample Depth: 10,166' 8" Grain Mineralogy: quartz predominates with unit extinction; monocrystalline Grain Size: X'= .32 mm o = .19 Sorting: poor Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: none evident Accessory Minerals: some clay present Comments: some pressure solution observed; few silica overgrowths; less than 1% feldspar + rock fragments; 90% quartz grains (+ silica) + 10% clay. 132 Well: Dalrymple 1-16 Sample Depth: 11,057' 4” Grain Mineralogy: quartz predominates; unit extinction; monocrystalline Grain Size: X'= .38 mm o = .21 Sorting: -- Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: none evident Accessory Minerals: none observed Comments: very tight sand; silica overgrowths present; some pressure solution with sutured grain contacts; very small amount of "dead" oil observed, appears to have inhibited silica cementation; less than 1% rock fragments; 100% quartz grains + silica. Well: Dowker et al. 2-21 Sample Depth: 7897' Grain Mineralogy: quartz predominantly; unit extinction and monocrystalline Grain Size: X'= .13 mm o = .08 Sorting: poor Rounding: angular to subrounded Porosity: no observable porosity Sedimentary Structure: vague lamination, possibly due to compaction Accessory Minerals: lots of clay present Comments: clay appears to choke pores; less than 1% feldspar; possible "dead" oil along solution seam; 65% quartz grains + 35% clay. 133 Well: Fruedenberg 1-31 Sample Depth: 9596' Grain Mineralogy: predominantly quartz grains with unit extinction; monocrystalline Grain Size: X'= .48 mm o = .34 Sorting: poor to fair Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: none evident Accessory Minerals: none observed Comments: sandy dolomite lithology, possible "dead” oil present; most often quartz grains are observed to be "floating" in a dolomite matrix; 47% quartz grains + 53% dolomite matrix. Well Gilde 1-25 Sample Depth: 10,598' 11" Grain Mineralogy: quartz grains predominate; monocrystalline quartz with some undulose grains Grain Size: X'= .45 mm o = .15 Sorting: -- Rounding: subangular to rounded Porosity: tight sand, no observable porosity Sedimentary Structures: none evident Accessory Minerals: no clay observed Comments: very tight sand; highly compacted; quartz overgrowths present; less than 1% feldspar; 99% quartz grains (+ silica) + 1% rock fragments. 134 Well: Gray 1-31 Sample Depth: 9566' Grain Mineralogy: quartz grains, with unit extinction; monocrystalline Grain Size: X'= .25 mm o = .10 Sorting: fair Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: none evident Accessory Minerals: none observed Comments: sandy dolomite to dolomitic sand lithology; 58% quartz grains + 42% dolomite matrix. Well: McCormick 2-27 Sample Depth: 9766' Grain Mineralogy: quartz predominates, with unit extinction and monocrystalline Grain Size: X'= .41 mm o = .31 Sorting: fair to poor Rounding: subangular to subrounded Porosity: some porosity observed Sedimentary Structures: some compactional alignment of grains Accessory Minerals: small amount of clay Comments: some dolomite cement present; some silica overgrowths observed, with possible pressure solution and suturing of grains; overall, sand appears fairly porous; 90% quartz grains (+ silica) + 6% dolomite cement. 135 Well: McCormick 2-27 Sample Depth: 9841' Grain Mineralogy: quartz; monocrystalline, unit-extinction Grain Size: X'= .26 mm o = .11 Sorting: poor to fair Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: none observed Accessory Minerals: none evident Comments: dolomitic sand to sandy dolomite; 34% quartz grains + 66% dolomite matrix. Well: Roseville Gun Club ”B” 1-17 Sample Depth: 11,772' Grain Mineralogy: quartz exclusively; unit extinction; monocrystalline quartz Grain Size: X'= .20 mm o = .10 Sorting: -- Rounding: subangular to subrounded Porosity: no observable porosity Sedimentary Structures: compactional lamination Accessory Minerals: tourmaline grain Comments: very tight sand; silica overgrowths observed; sutured grain contacts, less than 1% feldspar plus rock fragments; less than 1% tourmaline; 99% quartz (+ silica) + 1% feldspar. 136 Well: Workman 10-31 Sample Depth: 11,083' 10” Grain Mineralogy: predominantly quartz, with unit extinction; monocrystalline Grain Size: X'= .35 mm o = .14 Sorting: fair Rounding: subangular to subrounded Porosity: fair amount of porosity Sedimentary Structures: none evident Accessory Minerals: some clay present, in the form of rims on framework grains Comments: some pressure solution observed; sutured contacts; silica overgrowths present; small amount of dolomite cement observed; 90% quartz grains (+ silica) + 2% clay + 5% dolomite cement + 3% porosity. 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N. wacaou ozouuo ..N ...N 3..N 3.N .NN ..N .>m.. . m . .... a . ......QN ms.3 ...3 3. 1115 w—u— o_m.w nu Nom.m «mo.m con.m Nmo— zmzwzm w— 3¢ sz .aum tad hugonvgumaoum omomm om~.o_ mc—.o— Nv—.o— nom.¢ omc.m ~_v— Imzmzz c— :0 z—m .90; tua c—o— camcmm ~.mvn Nucao. v.0.xo: ov—.a nu mm—.o «po.m mp—.m can Imzmzu o— u—— zm— .5.u .comaswm — .nxh ouuo>oz ooomw :3. NNo.m no e—o.a mom.m mmw.m w.o u2u2mz a ma 2m. vco .6.u .c0on_m — mgvnw—uuom ommmw Nassau N_o..:. o—m.. .- mem.~ mm_.~ voo.c mm. 2 z z m u— 29 .09 __o .zu_x mu— acwga—ommo: .msom mm~.~ an omm.m ncm.e 0mm.m woo swamzu Nm “N zm moo vca —.c cemvo: — Luoc_w>o osmmw _ ...... .mm.o u- mmm.o cmm.o wo_.o new :zummm m “N 2m —_nox axm:._0w ~om.~ mm~.o :- m_~.o .vm.o mam.m 0mm mzwmzu m mm zm .<.u .mma p mwsgou o.m- qummmxwmwmmmmzw N.-. ..... awm.~ u- ~mm.~ mmx.o c.m.o was wmzmzu om mm— zw— .m.z.x ace mus—uuz vco uumxo: vNoOM cem.~ mm..o -- m...o emm.w voo.m mu. mmumwm em mm— zp— .09 —mo Omsw>cgh emu. u_umouu asnmm .e. 3:. N.... .N... - .N... .N... ..... ... .232.3 .. ... 3N. ..N ......a<-..3 ..-. .....oo3 ..... ..... -- ..... .N... N.... ... ....z. . ... 3N. .... .co..e.. . ...co3 ....N mem.o .. mmm.o ....m mm_.m om. mzzzzz kw um— 2a .u:_ ...wx—_o: — qucwam cxvcw omo.o -u moc.c mw..c mco.m ow. m2uzzu c— um— zw pmo w—osax p —e:ucmanoz smmmm .Nmmmmmle—wcem L .o ...N 3.. 3.. .NN ..N ..... x . . .... . . .......N 95.3 ...3 3. BIBLIOGRAPHY BIBLIOGRAPHY Bain, H. F., 1906, Zinc and Lead Deposits of the Upper Mississippi Va11ey, U.S. Geo1. Surv. Bu11. 294, p. 18. Ba1ombin, M. T., 1974, The St. Peter Sandstone in Michigan, Unpub1ished Master's Thesis, Michigan State University. Basu, A., Young, S. N., Suttner, L. J., James, W. G., and Mack, G. H., 1975, Re-eva1uation of the use of undu1atory extinction and po1ycrysta11inity in detrita1 quartz for provenance interpretation, Jour. Sed. Petro1., v. 45, p. 873-82. Benedict, E. N., 1967, A Subsurface Study of the Pre-Knox Unconformity and Re1ated Rocks in the State of Ohio, Unpubiished Master's Thesis, Michigan State University. B1att, H., 1967, Provenance determinations and recycling of sediments, dour. Sed. Petro1., v. 37, p. 1031-44. , 1979, Diagenetic processes in sandstones: ifl_Aspects of Diagensis, Scho11e, P. A., and Schluger, P. R. (eds.), Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub. 26, p. 141-57. , Midd1eton, G., and Murray, R., 1980, Origin of Sedimentary Rocks, Prentice-Ha11, Inc., New Jersey, 782 p. Bricker, D. M., 1982, 0i1 and gas deve1opments in Michigan in 1981, Amer. Assoc. Petro1. Geo]. Bu11., v. 66, p. 1827-32. , Mi15tein, R. L., and Reska, C. R., 1983, Se1ected Studies of Cambro-Ordovician Sediments within the Michigan Basin, Michigan State Geo]. Surv. Rept. Invest. 26, 54 p. Buschbach, T. C., 1964, Cambrian and Ordovician Strata of Northeastern 111inois, I11inois State Geo1. Surv. Rept. Invest. 218, 90 p. Butts, C., 1940, Geo1ogy of the Appa1achian Va11ey of Virginia, Virginia Geo1. Surv. Bu11., v. 52, 568 p. Catacosinos, P. A., 1972, Cambrain Statigraphy of the Lower Peninsu1a of Michigan, Ph.D. Thesis, Michigan State University. 146 147 Chafetz, H. S., 1967, Petrography and Stratigraphy of the Strata of the Lower-Midd1e Ordovician Contact, Centra1 Pennsy1vania, Master's Thesis, Michigan State University. , 1969, Carbonates of the Lower and Midd1e Ordovician in Centra1 Pennsy1vania, Pennsy1vania Geo1. Surv. Bu11. G58, 39 p. Chase, C. G., and Gi1mer, T. H., 1973, Precambrain p1ate tectonics: The Midcontinent gravity High, Earth and P1anetary Science Letters, v. 21, p. 70-78. Cohee, G. V., 1945, 0i1 and Gas Investigations, U.S. Geo1. Surv. Pre1. Chart. No. 9. , 1946, Cambrain and Ordovician rocks in recent we11s in southeastern Michigan, Amer. Assoc. Petro1. Geo1. Bu11., v. 31, p. 293-307. , 1948, Cambrain and Ordovician rocks in Michigan Basin and adjoining areas, Amer. Assoc. Petro1. Geo1. Bu11., v. 32, p. 1417-48. , 1965, Geo1ogic history of the Michigan Basin, Jour. Nash. Acad. Sci. Cooper, 8. N., and Prouty, C. E., 1943, Stratigraphy of the Lower Midd1e Ordovician of Tazewe11 County, Virginia, Bu11. Geo1. Soc. America, v. 54, p. 819-86. Dapp1es, K. S., 1955, Genera1 1ithofacies re1ationship of St. Peter sandstone and Simpson Group, Amer. Assoc. Petro1. Geo1. Bu11., v. 39, p. 444-67. Dixon, G. E., 1961, Litho1ogic Study of a Cambro-Ordovician Core, De1ta County, Michigan, Unpub1ished Master's Thesis, Michigan State University. Do11y, E. D., and Busch, D. A., 1972, Stratigraphic and geomorpho1ogic factors conto11ing 0i1 accumu1ation in Upper Cambrain Strata in centra] Ohio, Amer. Assoc. Petro1. Geo1. Bu11., v. 56, p. 2335-68. E115, G. D., 1967, Corre1ation of Cambro-Ordovician rocks in Michigan, in_Michigan Basin Geo1. Soc. Ann. Fie1dtrip Excur. Guidebook, p. 42-57. , 1969, Architecture of the Michigan Basin: in Michigan Basin Geo1. Soc. Ann. Fie1dtrip Excur. Guidebook, p. 60-88. Fisher, J. H., 1969. Ear1y Pa1eozoic history of the Michigan Basin: jn_Michigan Basin Geo1. Soc. Ann. Fie1dtrip Excur. Guidebook, p. 89-93. 148 , 1983, Tectonic evqution of the Michigan Basin, Geo1. Soc. America, Abs. w/Prgms., v. 15, p. 573. Frey, R. w. (ed.), 1975, The Study of Trace Fossi1s: A Synthesis of Princip1es, Prob1ems and Procedures in Ichno1OQY. Springer-Ver1ag, New York, 562 p. Hamb1in, N. K., 1958, Cambrain Sandstones of Northern Michigan, Michigan State Geo1. Surv., Pub1. 51, 146 p. Hayes, J. 8., 1979, Sandstone diagenesis--The ho1e truth: in Aspects of Diagenesis, Scho11e, P. A., and Sch1uger, P. R. (edET, Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub1. 26, p. 127-39. Hea1d, M. T., 1956, Cementation of Simpson and St. Peter sandstone in parts of Ok1ahoma, Jour. Geo1., v. 64, p. 16-30. Hecke1, P. H., 1972, Recognition of ancient sha11ow marine environments: in_Rigby, J. K., and Hamb1in, w. K. (eds.), Recognition of Ancient Sedimentary Environments, Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub1. 16, p. 226-86. Hinze, H. J., and Merritt, D. N., 1969, Basement rocks of the Southern Peninsu1a of Michigan: jn_Michigan Basin Geo1. Soc. Ann. Fie1dtrip Excur. Guidebook, p. 28-59. Horowitz, M. M., 1961, The St. Peter-G1enwood Prob1em in Michigan, Unpub1ished Master's Thesis, Michigan State University. Houseknecht, D. H., 1984, Inf1uence of grain size and temperature on intergranu1ar pressure so1ution, quartz cementation, and porosity in quartzose sandstone, Jour. Sed. Petro1., v. 54, p. 348-61. Jennings, S., 1985, ora1 comm., Jennings Petro1eum, F1int, Michigan. Krumbein, H. C., and 51055, L. L., 1958, Stratigraphy and Sedimentation, Wm. H. Freeman and Co., San Francisco, 497 p. Li1ientha1, R. T., 1978, Stratigraphic Cross-Sections of the Michigan Basin, Michigan State GeoT. Surv. Rept. Invest. 19. Lockett, J. R., 1947, Deve1opment of structures in basin areas of northeastern United States, Amer. Assoc. Petro1. Ge01. Bu11., v. 31, p. 429-46. Maxwe11, J. C., 1964, Inf1uence of depth, temperature, and geo1ogic age on porosity in quartzose sandstones, Amer. Assoc. Petro1. Geo1. Bu11., v. 48, p. 697-709. McGee, w. J., 1891, E1eventh Ann. Rept., U.S. Geo1. Surv., pt. 1, pp. 331, 332. 149 Michigan State Geo1ogica1 Survey, 1964, Stratigraphic Succession in Michigan, Michigan State Geo1. Surv., Chart No. 1. Montgomery, S. L. (ed.), 1984, Michigan Basin: Expanding the deep frontier, Petro1eum Frontiers, v. 1, no. 3. NeTSon, J. R., 1985, ora1 comm., Michigan State University. Pettijohn, F. J., Potter, P. E., and Siever, R., 1972, Sand and Sandstone, Springer-Ver1ag, New York, 618 p. Pirt1e, G. N., 1932, Michigan structura1 basin and its re1ationship to surrounding areas, Amer. Assoc. PetroT. Geo1. Bu11., v. 16, p. 145-52. Pittman, E. D., 1979, Porosity, diagenesis and productive capabiTity of sandstone reservoirs: in Aspects of Diagenesis, Sch011e, P. A., and Sch1uger, P. R. (ed.), Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub1. 26, p. 159-73. Prouty, C. E., 1946, Lower Midd1e Ordovician strata of southwest Virginia and northwest Tennessee, Amer. Assoc. PetroT. Geo1. Bu11., v. 30, p. 1140-91. , 1948, Trenton and sub-Trenton stratigraphy of northwest be1ts of Virginia and Tennessee, Amer. Assoc. Petro1. Geo1. Bu11., v. 32, p. 1596-1626. (ed.), 1960, Lower Pa1eozoic and P1eistocene Stratigraphy across Centra1 Wisconsin: in_Michigan Basin Geo1. Soc. Ann. Fie1dtrip Guidebook, 95 p. , 1970, Michigan Basin--Pa1eozoic evo1utionary deve1opment, Geo1. Soc. America Abs., v. 2, pt. 7, p. 657-58. , 1976, Michigan Basin--A wrenching deformation mode1? Geo1. Soc. America Abs., v. 8, pt. 4, p. 505. , 1980, Petroieum exp1oration and wrenching mode1, Michigan Basin (abs.), Amer. Assoc. Petro1. GeoT. Bu11., v. 64, p. 768. , 1984, The tectonic deve1opment of the Michigan Basin intrastructures: in_Michigan Basin Geo1. Soc. Ann. Fie1dtrip Guidebook, p. 36-81. , 1985, ora1 comm., Michigan State University. Pryor, w. A., 1973, Permeabi1ity-porosity patterns and variations in some Ho1ocene sand bodies, Amer. Assoc. PetroT. GeoT. Bu11., v. 57, p. 162-89. 150 Przywara, M., 1984, ora1 comm., Amoco Production, Houston, Texas. Reineck, H. E., and Singh, 1. B., 1980, 0epositiona1 Sedimentary Environments, Springer-Ver1ag, New York, 549 p. Rhoads, D. C., 1975, The pa1eoTogica1 and environmentaT significance of Trace Fossi1s: ifl_Frey, R. w. (ed.), The Study of Trace Fossi1s, Springer-Ver1ag, New York, 562 p. Robinson, w. 1., 1923, Fo1ds resu1ting from vertica11y acting forces, Jour. Geo1., v. 31, p. 336-43. Rudman, A. J., Summerson, C. H., and Hinze, H. J., 1965, Geo1ogy of basement in midwestern United States, Amer. Assoc. Petro1. GeoT. Bu11., v. 49, p. 894-904. Schmidt, V., and McDona1d, D. A., 1979a, The r01e of secondary porosity in the course of sandstone diagenesis: in Aspects of Diagenesis, Scho11e, P. A., and Sch1uger, P. R. (edsTT, Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub1. 26, p. 175-208. and , 1979b, Texture and recognition of secondary porosity in sandstones: in Scho11e, P. A., and Sch1uger, P. R. (eds.), Soc. Econ. Pa1eonto1. Minera109., Spec. Pub1. 26, p. 209-26. and , 1980, Secondary Reservoir Porosity in the Course of Sandstone Diagenesis, Amer. Assoc. PetroI. Geo1. Continuing Education Course Note Series 12, 125 p. Schmidt, V., McDona1d, D. A., and P1att, R. L., 1977, Pore geometry and reservoir aspects of secondary porosity in sandstones, Bu11. Canadian Petro1. Geo1., v. 25, p. 271-90. Se11ey, R. C., 1978, Ancient Sedimentary Environments (2nd Ed.), Corne11 University Press, Ithaca, New York, 287 p. , 1982, An Introduction to SedimentoTOQY. Academic Press, New York, 417 p. SeyTer, D. J., 1974, Midd1e Ordovician of the Michigan Basin, Unpub1ished Master's Thesis, Michigan State University. Sib1ey, D. F., and B1att, H., 1976, Intergranu1ar pressure so1ution and cementation of the Tuscarora orthoquartzite, Jour. Sed. Petro1., v. 46, p. 881-96. Ste1zer, N. J., 1966, A Subsurface Study of the Midd1e Ordovician Sequence in Ohio, Unpub1ished Master's Thesis, Michigan State University. 151 , 1982, A Look at the Centra1 Michigan Basin Deep Exp1oration. Conference and TechnoTogica1 Workshop, U.S. 0i1 and Gas Techno1ogy Conference/Expo, Detroit, Michigan. Syrjamaki, R. M., 1977, The Prairie du Chien Group of the Michigan Basin, Unpub1ished Master's Thesis, Michigan State University. Tay1or, J. M., 1950, Pore-space reduction in sandstones, Amer. Assoc. PetroT. Geo1. Bu11., v. 34, p. 701-16. Temp1eton, J. S., and Wi11man, H. B., 1963. Champ1anian Series (Midd1e Ordovician) in I11inois, 111inois State Geo1. Surv. Bu11. 89, 260 p. Thomas, G. E., 1974, Lineament-b1ock tectonics: Wi11iston-B1ood Creek Basin, Amer. Assoc. PetroT. Geo1. Bu11., v. 58, p. 1305-22. Thomson, A., 1959, Pressure so1ution and porosity: jn_Ire1and, H. A. (ed.), Si1ica in Sediments, Soc. Econ. Pa1eonto1. Minera1og., Spec. Pub1. 7, p. 92-110. Tissot, B. P., and We1te, D. H., 1978, Petro1eum Occurrence and Formation, Springer-Ver1ag, New York, 538 p. To11efson, L., 1984, ora1 comm., Amoco Production, Houston, Texas. Wa1ker, R. G. (ed.), 1979, Facies Mode1s, Geoscience Canada Reprint Series 1, 211 p. Whiting, W. M., 1965, A Subsurface Study of Post-Knox Unconformity and Re1ated Rock Units in Morrow County, Ohio, Unpub1ished Master's Thesis, Michigan State University. Winche11, N. H., 1874, Second Ann. Rept., Minnesota Geo1. Nat. Hist. Surv., p. 138-47. Woodward, H. P. (ed.), 1959, A Symposium on the Sandhi11 Deep We11, Wood County, West Virginia, West Virginia State Geo1. Surv. Rept. Invest. 18, 182 p. Wooster, C., 1878, Ann. Rept. for 1877, Wisconsin Geo1. Surv., p. 36-41. Young, S. W., 1976, Petrographic textures of detrita1 po1ycrysta11ine quartz as an aid to interpreting crysta11ine source rocks, Jour. Sed. Petro1., v. 46, p. 595-603. Zwicker, D. L., 1983, Cambro-Ordovician Sandstones of the Northern Michigan Basin, Unpub1ished Master's Thesis, Michigan State University. o: . .0. ‘ . 3:1, "‘11111111111111?