A MECHANICAL AND CHEMICAL ANALYSES OF ME MlQDEE D'WONIAN DETROIT RIVER GROUP ABOVE THE SYLVANHA N THE MECHBGAN BASEN T519333 gov €312 Degree c? M. S. MICHEGAN STATE UNIVERSITY David; E. Dewey 1958 If“; C J ovzaous FINES: T lngiua§fim. E: 25¢ par day per item RETURNING LIBRARY MATERIALS: Place in book return to remove _\ 7 . charga from circulation records Siouu'” A MECHANICAL AND CHEMICAL ANALYSIS OF THE MIDDLE DEVONIAN DETROIT RIVER GROUP ABOVE THE SYLVANIA IN THE MICHIGAN BASIN By DAVID E. DEWEY A THESIS Submitted to the College of Science and Arts of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Geology 1958 AC KNOWLEDG MENTS The author wishes to thank and express his sincere appreci- ation to Dr. B. T. Sandefur, under whose direction this problem was undertaken. Dr. Sandefur's interest, encouragement, and helpful suggestions aided greatly in the completion of this paper. He also wishes to thank the other members of the geology staff at Michigan State University for their helpful suggestions on various phases of this project. The cooperation given by the members of the Michigan Geo- logical Survey in helping to select and furnish well samples was also appreciated. The writer is indebted to his wife Pat, who not only typed the initial drafts of this manuscript, but gave constant encourage- ment throughout the writer's educational program. ii A MECHANICAL AND CHEMICAL ANALYSIS OF THE MIDDLE DEVONIAN DETROIT RIVER GROUP ABOVE THE SYLVANIA IN THE MICHIGAN BASIN DAVID E. DEWEY ABSTRACT This sedimentary lithofacies study was undertaken to show the environmental, depositional, and tectonic conditions existing during the deposition of the "Upper Detroit River" sediments. Composite samples representing the complete "Upper Detroit River” section were obtained from twenty-six wells located in the Lower Peninsula of Michigan. These samples were acidized, dis- aggregated, and sieved to determine their lithologic character. Facies maps were then constructed from the numerical data obtained from the mechanical and chemical analysis. The clastic ratio map indicates the variations between the elastic and nonclastic material; the sand-shale ratio map shows the variations in the elastic material, the evaporite ratio map depicts the relation be- tWeen the evaporites and carbonates, the Mg/Ca ratio map indicates iii A the variations in the carbonates, and the anhydrite percentage map locates the depositional areas of anhydrite. The lithofacies maps were interpreted by studying the pat- terns formed when an isopach map is superimposed on the various ratio maps. The information acquired from this investigation aided in reconstructing the geologic history of "Upper Detroit River" tune. This sedimentary facies analysis indicates that during "Upper Detroit River" time, the basin received elastic sediments from four source areas, the north, west, southwest, and southeast. Deposition began and ended quietly and there were no major crustal distur- bances in or around the basin. It was shown that although the structural features surrounding the basin were stable and lowlying, they were emergent for periods of time due to subsidence within the basin. iv INTRODUC TION ...... CONTENTS aaaaaaaaaaaaaaaaaaaaaaaaa Description of the Michigan Basin ................ Facies Analysis . . . . Purpose of Study . . . aaaaaaaaaaaaaaaaaaaaaaaaa WELL SELECTION AND DISTRIBUTION .............. Stratigraphy of the Analyzed Section ............... Selection of the Top and Bottom of the Upper Detroit River ....................... Selection of Wells . . ooooooooooooooooooooooooo LABORATORY PROC EDURE ...................... Sampling Methods . . . Removal of Water Solubles ..................... Removal of Carbonates Disaggregation ..... Sieving ......... Removal of Anhydrite ........................ aaaaaaaaaaaaaaaaaaaaaaaaa Magnesium/Calcium Analysis .................... Accuracy of the Data 10 16 16 17 18 19 19 2.0 -21 24 Results of Laboratory Analysis oooooooooooooooooo LITHOLOGIC INTER PRE T A TIONS Lithologic Ratios ............................ Construction of Facies Maps -------------------- Methods of Geologic Interpretation ............... . Lithofacies Interpretations ...................... REGIONAL TECTONICS AND CONCLUSIONS ........... Structures Related to the Michigan Basin Sedimentary and Tectonic Interpretations ........... C onclu sions aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa REFERENCES 27 3O 3O 33 43 43 44 49 51 TABLE III. IV. FIGURE ILLUSTRATIONS Generalized Devonian C olumn of Michigan .................... Well Descriptions ................ Quantitative Analysis ............. Lithologic Ratios ................ Relations of Isopachs (Solid) and Facies Lines ................ Upper Detroit River Outcrop Area . . . . Location of Wells Used in the Analysis County Locations ................ Isopach ....................... Clastic Ratio ................... Sand-Shale Ratio ................ Evaporite Ratio ................. Magnesium/Calcium Ratio .......... Anhydrite Percentage ............. Page ........ 6 ........ 12 ........ 25 ........ Z6 ........ 31 ........ Pocket ........ Pocket ........ Pocket ........ Pocket ........ Pocket A MECHANICAL AND CHEMICAL ANALYSIS OF THE MIDDLE DEVONIAN DETROIT RIVER GROUP ABOVE THE SYLVANIA IN THE MICHIGAN BASIN INTRODUC TION Description of the Michigan Basin Due to the extensive cover of Pleistocene glacial deposits. little subsurface information concerning the Michigan basin was available until extensive oil and gas exploration was undertaken some thirty-five years ago. This subsurface information along with outcrop studies have added greatly to our present knowledge of the basin. The Paleozoic strata form an elliptical pattern in the basin with the major axis trending northeast-southwest. Sediments were deposited in the shallow marine seas occupying the Michigan basin during Paleozoic time. These range in age from the younger Penn- sylvanian, deposited in the center. to the older Ordovician and Cambrian sediments found at the periphery of the basin. Newcombe (1933) described the areal extent of the Michigan basin in this manner: The area comprising the Michigan basin includes about 106.700 square miles and stretches from Fort Wayne. Indiana. on the south. to Whitefish point. near Sault Ste. Marie. Michi- gan. on the north and from west to east about 370 miles. In the center of the basin. which coincides with the geographic center of the Lower Peninsula of Michigan. the Paleozoic sediments attain a thickness of approximately 15.000 feet. Pirtle (1932) described the structures bounding the Michigan basin as follows: The Wisconsin arch to the west. the two limbs of the Cincinnati arch in the south. the Kankakee arch in the southeast. the Canadian Shield to the north. and the Algonquin arch. an exten- sion of the Findlay arch. to the east. Pirtle further states that the development of the Michigan basin is due to uplift around the rim and that the northwest-trending folds in the east-central portion of the basin are related to the pre-existing Precambrian zones of weakness. Folds within the Paleozoic sediments of southwest Michi- gan trend northeast and are related to the Kankakee arch. Green (1957), in discussing the structure and geologic history of the basin. made the following statements which are not in accord with those presented by Pirtle (1932): "The stru'ctural development 0f the Michigan Basin has resulted from the subsidence of the basin during post-Niagaran Silurian time rather than uplift around the rim. . . . the term 'Kankakee arch' found in earlier literature should be dropped, as no structural connection between the Wisconsin and the Cincinnati arches is indicated. In place of the Kankakee arch, Green (1957) suggested that the southwest boundary of the Michigan basin be the Francesville arch, which lies between the Wisconsin and Cincinnati arches, and is not structurally related to either. It is left to the reader to choose between the ideas of Green and those of Pirtle, but in either event both authors presented the same general picture of the Michigan basin. A negative area rimmed by positive features, receiving sediments throughout the Paleozoic era. Facies Analysis Moore (1949) defines sedimentary facies as "any areally re— stricted part of a designated stratigraphic unit which exhibits char- acteristics significantly different from those of other parts of the unit involved." Three types of facies, namely lithofacies, biofacies, and tec- tofacies have been defined. Moore (1949) defines lithofacies as "groups of strata demonstrably different in lithologic aSpect from laterally equivalent rocks." Krumbein and Sloss (1951) describes biofacies as "lateral variations in the biologic aspect of a stratigraphic unit" and tectofacies as "laterally varying tectonic as- pects of a stratigraphic unit." The results of various facies analyses may be expressed as contours on maps. Lithofacies and biofacies maps express varia- tions in the sedimentary environment, and tectofacies maps show tectonic variations in the stratigraphic unit. Purpose of Study The purpose of this study is to determine the depositional and environmental conditions which prevailed in the Michigan basin during ”Upper Detroit River" time. This information will be gained by mechanical and chemical analysis of samples taken from twenty- six selected wells. The data obtained will form the basis for the construction and interpretation of lithofacies maps. Similar investigations have been carried out on other Devonian formations from the Michigan basin. It is the desire of the author that the information gained from this report will shed additional light on the picture of the Devonian sedimentation in the Michigan basin. WELL SELECTION AND DISTRIBUTION Stratigraphy of the Analyzed Section The section analyzed includes the Lucas and Amherstburg formations of the Detroit River Group. Table I shows the gener- alized Devonian section in the Michigan basin. The lower forma- tion of the Detroit River Group, the Sylvania sandstone, was not included in the analysis because of its entirely different lithologic type. Krumbein (1952) states that when dealing with radically dif- ferent sections in lithofacies studies it is best to divide the interval into two or more parts for separate analysis. Throughout the re- mainder of this paper the term ”Upper Detroit River" will be used to refer to the section analyzed, the Lucas and Amherstburg forma- tions. The Detroit River Group, sometimes called the "Middle Monroe," has been tentatively correlated with the Onondaga of New York, the Ulsterian of Ontario, and the Columbus limestone (Ulsterian) Of Ohio. These correlations are based on both faunal and lithologic elements. GENERALIZED TABLE I DEVONIAN COLUMN OF MICHIGAN Remarks Name of Unit Thickness(') Descriptions TRAVERSE loo-875 Limestone 8 shale ROGERS cm 0.425 3m" limestone DUNDEE 0-460 Mm" limestone 2. Dolomite, u. 58-”24 anhydrite a) 8 salt < o 0-: , , Dolomite with D .1 RICI'lfIEId 0-80 0 sandstone I: o m O-l50 IDark limestone J 8 dolomite Q a: m 53 2 2 a: Filer Lentil O—lOO Sandstone o I: 3 Dark black 55 0—200 limestone m g or dolomite *- Lu 3; Sandstone q Sylvania 0-300 with dolomite 8 chert a: Chert m BOIS BLANC O-IOOO limes one i or dolomite O 4 GARDEN ISLAND 0-30 Dolomite Bell shale- at base Erasianal unconformity Absent in SW Michigan Absent in SW Michigan Erasianal unconformity Subsurface only. Mainly in central 8 S. Michigan Erasianal unconformity Erratic distribution; thickest in w. Michigan Only in eastern Michigan Erasianal ungonformity Absent in SE 8. SW Michigam Erasianal ungonf'ormity Patchy distribution MODIFIED AFTER H. L. MARTIN The Upper Detroit River underlies most of the Lower Pen- insula of Michigan and crOps out (Map I) between Detroit and Monroe (Michigan) and in the vicinity of Sylvania, Ohio. The sec- tion varies in thickness from a few hundred feet to 1,300 feet; the thickest section is located in the center of the basin in Clare County. A committee from the Michigan Geological Society (1948) de- scribed the Upper Detroit River as: . typically fine-grained gray to buff thin—bedded dolomite with abundant carbonaceous partings and with some limestone members mainly in the upper part, anhydrite throughout: an evaporite series of dolomite, anhydrite, and several beds of salt are in the middle part in central Michigan, where the for- mation is thickest: sandstone sandy dolomite and chert in the lower part, and some black limestone members. The Lucas formation ranges from 20 to 1,125 feet in thick- ness. It is a light-colored dolomite which includes a thick evapo- rite section. Dolomite, anhydrite, salt, limestone, and sandstone, named in order of abundance, make up the formation. The upper member, the Anderdon dolomite, is found above the Lucas in outcrop but cannot be traced in the subsurface section. The Richfield mem- ber at the base of the Lucas is a porous dolomite with lenticular sandy phases. These sandstone lenses are sometimes referred to as the "Freer sandstone.” The Richfield can be recognized in sub- surface only within a 50- mile radius of Roscommon County. MAP I “an , K2550 .5 'o . . “h _I___-_I_I_ The Amherstburg formation found in all parts of the Lower Peninsula except in the southeast and southwest corners ranges in thickness from 0 to 450 feet. In the north and east parts of the Lower Peninsula the Amherstburg, except for local sandstones, is composed of dark brown to black limestones with subordinant amounts of dolomite, but in the south and west portions dolomite predominates. The "Filer" sandstone lentil, which is found in the middle of the formation, ranges in thickness from 0 to 100 feet. It is found in a belt three counties wide extending in an east-west direction from Saginaw Bay to Lake Michigan. Selection of the Top and Bottom of the Upper Detroit River The top of the Upper Detroit River underlies the Dundee formation except in southwest Michigan, but where the Dundee is absent the Upper Detroit River is overlain by the Traverse group. The criteria used for picking the contact between the Dundee or Traverse and the t0p of the Lucas are the following: lack of an— hydrite in the Dundee and Traverse; the absence of sand and chert at the top of the Lucas; and in general, the carbonate section at the top 0f the Lucas is lighter in color than the overlying formations. 10 The Upper Detroit River overlies three different formations: the Sylvania sandstone, Bois Blanc cherty limestone, and the Silurian Bass Island formation found in the southwest. The contact between the Amherstburg and the Sylvania sand- stone in some places is gradational, but in most cases the contact could be picked easily by the increase of sand in the upper carbon- ate section of the Sylvania formation. Where the underlying Sylvania is absent the contact between the Amherstburg and the Bois Blane is gradational. The top of the Bois Blanc and the bottom of the Am- herstburg is limestone. The contact between the two formations was established by comparing the dark brown to black carbonates found at the bottom of the Amherstburg to lighter carbonates in the Bois Blanc. The obvious lithologic differences between the Bass Island, when overlain by the Amherstburg, was either yellow, gray, or bluish dolomite or light green shale, as compared to the dark brown to black limestone or dolomite of the Amherstburg formation. Selection of Wells The following four criteria were used to pick the wells for this investigation: (1) Every well penetrated the complete Upper Detroit River section. (2) Whenever possible, samples obtained by cable tool methods were used to insure more accuracy and less 11 contamination. (3) To insure a more reliable Mg/Ca ratio, explora- tory wells were analyzed in place of field well. Tinkelpaugh (1957) stated that samples taken from field wells producing from porous dolomites give abnormally high Mg/Ca ratios. Of the twenty- six wells studied only three were field wells. (4) The last criterion was to pick wells that were prOperly spaced to insure adequate con- trol. Well spacing in a regional lithofacies study should be far enough apart to show broad regional trends in lithology. Close well Spacing can confuse and disorganize the general regional pat- tern by overemphasizing chal irregularities (Krumbein, 1952). Table II lists and describes the wells used in this investiga— tion. Map 2 gives the location of the analyzed wells. Map 3, a county reference map, is included for the convenience of the reader. TABLE II WE LL DE SC RI PT IONS 12 Thick- Well County and . Land ness of . D 11 d No. Township r1 er an Farm Description Section (feet) 1 Shiawassee Panhandle Eastern 23-5N- 2E 400 Perry S. Nemcik #1 2 Lapeer Brazos Oil and Gas l4-7N-11E 505 Attica G. Smith #1 3 Midland Dow Chemical Co. Zl-l4N-2E 700 Midland Fee #8 4 Sanilac M. JOy and Black 35-10N-16E 361 Lexington John Tomczyk #1 5 Livingston Panhandle Eastern 25-2N-5E 258 Genoa G. Baver #1 6 Muskegon Taggart Brothers Gas 20-12N-17W 320 Montague C. W. Nelson #1 7 Wayne Basin Oil Co. 22-18-8152 250 Plymouth E. Raetzel #1 8 Huron Pure Oil Co. 22-17N-15E 486 Rubicon J. Stapleton #1 9 Tuscola Shell Oil Co. 16—13N-11E 493 Novesta F. Woiden #l 10 Van Buren Little Four Oil Co. 23-28‘16W 208 Bangor J. Getz #1 11 Mason Brazos Oil and Gas 26-19N-18W 790 Hamlin Genson and Wheaton #1 12 Antrim Ohio Oil Co. l4-31N—8W 665 Central Lake H. Chamberlain #1 13 Hillsdale Clifford A. Perry 10—SS-R3W 264 Scipio Fern House Knecht #1 TABLE II (Continued) l3 Thick— Well County and Land ness of '1 No. Township Dn 1er and Farm Description Section (feet) 14 Alpena C. W. Teater 18—3ZN-6E 690 Long Rapids Nevins #1 15 Roscommon J. O. Mutch 2-24N-1W 935 Au Sable E. B. Hollwell #1 16 Manistee Carter Oil Co. 35-24N-15W 855 Pleasanton F. Crook #1 l7 Kalkaska John Neyer 27-27N-5W 1,275 Clearwater State—Clrwtr. #1 18 Isabella Cities Service 33-16N-3W 1,115 Wise Methner #B-1 1‘) Cheboygan Roosevelt Oil Co. 1-34N-2W 317 Ellis Ormsbee #1 20 Iosco Ray W. Matlock 1-22N- BB 660 Baldwin J. C. Johnson #1 21 St. Joseph Ora A. Avery 13-6S-11W 156 Lock Port S. Dunworth #1 22 Ottawa Voorhees Drilling 36-7N-16W 180 Grand Haven Reible #1 23 Lenawee Voorhees Drilling 8-55- 4E 250 Clinton Irving Grove #1 24 Barry Sun Oil Co. 8-T3N—9W 414 Rutland W. L. Kidder #1 25 Newaygo Sun Oil CO. 11—T12N-13w 57o Garfield Glen Bradley #4 26 Osceola OHW Oil Co. 29-18N-10w 1,290 Lincoln P. N. Stedman #3 DESCRIPTION OF ADDITIONAL WELLS USED TABLE II (Continued) FOR ISOPACH CONTROL 14 as County State Permit Desi-firpiion Thzfittfss Calhoun 18542 6-4S-5W 310 Grand Traverse 18512 9-25N-10W 1,160 Kalamazoo 32-1S-12W 230 Kent 9166 30- 7S-12W 405 Clinton 19272 27- 8N-4W 800 Gratiot 5067 24- 12N-3W 620 Berrien 13879 2-7S-17W 140 Leelanau 10103 5—29N-12W 710 Oscoda 11995 30- 25N- 3E 1,200 Otsego 16920 15-29N-2W 950 Bay 10551 34-15N-4E 780 -===:=== MAP 2 15 inf: — 0 LOCATION OF WELLS USED FOR FACIES ANALYSIS + LOCATION OF ADDITIONAL WELLS USED FOR ISOPACH CONTROL _:L_ , + f: , LABORA TORY PROC EDURE Sampling Methods Samples for the twenty-six wells were Obtained from either the Michigan Geological Survey or the Gulf sample collection at Michigan State University. Wells were selected which had a complete Upper Detroit River section; tops and bottom of the formations were picked on their lithologic characteristics. The Upper Detroit River was represented by four to ten trays of twenty-five vials each containing ten grams of sample. The number of samples selected varied from well to well. This Variation was caused by: (l) the difference in the sample interval 0f each sample set. which was usually from two to ten feet; (2) the Variation in the formation thickness which ranged from 200 feet to 1'300 feet. Wentworth (1926) states that in making a mechanical analysis of sedimentary samples about a 125-gram sample should be used. To achieve this sample weight a weight-per-foot factor was deter- mined for each of the wells studied. This varied from well to well 16 17 due to the different sample interval and vertical range. but was a constant in each individual well. In most cases it was possible to form a composite sample of 125 grams or more. but in a few wells. due to small formational thickness and the need to conserve the initial sample for future use. less than 125 grams were removed for analysis. Before the final weighing the sample was cleared of drilling "junk" by an electromagnet. The sample was then placed in a weighed 400-milliliter beaker and ready for the following treatments. Removal of Water Solubles Wiegner (1927) outlined a method by which soluble salts may be removed from a sample by treatment with water. The method involved boiling the sample in water to cause the ionic particles to gO i nt 0 solution. The sample was immersed in 250 milliliters of tap water and allowed to boil for approximately two hours. After the suspended material settled a lO-milliliter sample of the clear water was Pipetted off and placed in a test tube. The salinity of which water was Compared with an equal amount of tap water by the addition of a few crystals of silver nitrate to each. If the amount of precipi- tate fOrmed was greater in the sample than in the tap water. the 18 boiling procedure was repeated until the sample precipitate matched or was less than the tap water standard. - The clear solution was siphoned off. the sample washed in tap water. dried. and weighed. The difference in weight before and after the treatment gave the amount of water solubles present. Removal of Carbonates The removal of calcium carbonate and dolomite was carried out in the following manner. About 200 milliliters of a 25-percent solution of hydrochloric acid was slowly added to the sample. After effervescence ceased the solution was allowed to settle. A 10-milliliter sample of the supernatant liquid was pipetted Off for future testing of Mg/Ca ratios. The remaining supernatant liquid was then siphoned off. The process was repeated with hydrochloric acids at 50-percent and 1 00-percent strengths. The three acid treatments were used to retard the violent reaction that would result from an initial treat- ment with lOO-percent strength acid. After the loo-percent acid treatment the sample was heated in a Sand bath for one hour to remove the less soluble carbonates. The Mg/Ca sample was removed as before. and water added t0 l9 facilitate settling. The Clear solution was siphoned off and the sample washed with water until neutralized. Disaggregation Although the Upper Detroit River is predominately dolomite. limestone. anhydrite. and salt. small amounts of shale were noted in me sample after acid treatment. In order to facilitate sieving. the shale particles were disaggregated. Krumbein and Pettijohn (1938) define disaggregation as "the breaking down of aggregates into smaller clusters or into individual grains. " The method of disaggregation used was suggested by Krumbein and Pettijohn (1938); Cooke (1956) discussed this method in detail. The sample was treated with a supersaturated solution of Potassium hydroxide (KOH) and allowed to boil for six hours. In- Spection and a little experimenting showed that this was ample time to disaggregate the shale. After washing with water to neutralize the potassium hydroxide the sample was ready for sieving. Sieving In order to compute sand—shale and elastic ratios it was necessary to Separate the silt and clay particles from the remainder of the sample. 20 According to Wentworth's (1922) Partical Classification Table. fine sand will be retained on a sieve having a mesh opening of 1/16 millimeter. This mesh size corresponds to a 230 Tyler Sieve. The washed disaggregated sample was wet-sieved by passing a light stream of water over the sample which flushed the silt and clay material through the 230 Tyler Sieve leaving fine sand and larger material on the sieve. After drying and weighing. the amount of the silt and clay fraction was determined by the difference in weight before and after disaggregation and sieving. Removal of Anhydrite Inspection of the sample contained on the sieve showed it to be a mixture of anhydrite and fine sand. The anhydrite seemed to be little affected by the previous processes. as the fragments were. for the most part. angular and showed little evidence of solution by the acid and water treatments. As all samples were treated in a like manner. the author felt that the anhydrite content in each sample. if plotted on a base map in the form of a percentage. would give a good indication of its areal distribution. 21 Concentrated nitric acid removed the anhydrite from the sand fraction in the remaining sample. About 150 milliliters of concen- trated nitric acid (HNO3) was added slowly to the sample. When effervescence ceased the sample was allowed to boil on a sand bath for one hour to make sure all the anhydrite was dissolved. The sample was allowed to cool. then washed with water until the nitric acid was neutralized. The weight of the anhydrite fraction was determined by drying and weighing the remaining sand. The weight of the sand fraction was recorded for computing the sand-shale and elastic ratios. Magne sium/ C alcium Analysis For the Mg/Ca analysis the author used the formulas and laboratory techniques developed by Jodry (1955). The following are excerpts from Jodry's report to show how he accomplished his titra- tion analysis. Jodry (1955) stated. "In its simplest form. the formula for determining the Mg/Ca ratio for a given sample may be expressed as follows: Percent Mg_(_)_ __ D-B Pgrcent CaO 1.39B 22 B = Milliliters of Versenate solution used in titration. with Murexide as indicator. D = Milliliters of Versenate solution used in titration. with F 241 as indicator. This basic formula permits the ratio computation without use of a specific weight of sample (1.000 grams in the original formula) and without standardizing the versenate sOlution near the strength described only because these proportions give an optimum reaction without waste of reagents." As stated before under "Removal Of Carbonates." after acid treatments by 25-percent, 50-percent. and lOO-percent strength acids. a lO-milliliter sample from each was saved for the Mg/Ca determin- ation. The three 10-milliliter samples were mixed with 200 milli- liters of distilled water; the solution thus formed the sample to be tested in the following manner to obtain the Mg/Ca ratio. Jodry (1955) states: Determination of Calcium Reagents Versenate solution. Dissolve 4 grams of disodium salt of (ethylefinedinitrilo) tetraaCetic acid in 1 liter of water. Standard- ize this solution against a standard calcium solution with Ver- senate in the manner described below. Standard calcium solution. Dissolve 2.500 grams of re- agentg—Eade calcium carbonate in approximately 5 milliliters of ' .. I2 $334“ 23 l-to-l hydrochloric acid (warm gently if necessary) and dilute to exactly 1 liter with water. This solution contains 1 milligram of calcium per milliliter. Potassium hydroxide. Use a 20-percent aqueous solution. Calcium indicator powder. Mix thoroughly 40 grams of powdered potassium sulfate and 0.2 gram of Murexide. Titration l. Pipette a lO-milliliter aliquot of the solution to be analyzed into a ZOO-milliliter porcelain dish. then add approxi- mately 20 milliliters of water. 1 milliliter of potassium hydroxide. and a tiny scoop (20 to 30 mg.) of calcium indicator powder. 2. Stir the solution and titrate with the standardized Ver- senate. The end point is reached when the color of the solution changes from pink to violet. Determination of Magnesium Reagents Versenate solution. Prepare as above. Buffer solutionf Dissolve 60 grams of ammonium chloride in approximately 200 milliliters of water; add 570 milliliters of concentrated ammonium hydroxide, and dilute to 1 liter with water. Potassium cyanide. Prepare a lO-percent aqueous solution. F 241 indicator. , Dissolve 0.15 gram of Eriochrome Black T-(F 241) and 0.5 gram of sodium borate in 25 milliliters of methanol. Titration 1. Pipette a lO-milliliter aliquot of the solution to be analyzed into a ZOO-milliliter porcelain dish. then add 25 milli- liters of water. 2 to 3 milliliters of buffer solution. a few drops of potassium cyanide solution and 8 drops of F 241 indicator. 2. Stir. and titrate with the Versenate solution. The end point is reached when the color of the solution changes from winered to clear blue. By substituting the values gained by titration into the formula MgO _ D-B - the M Ca ratios were obtained. CaO 1.3913 g/ 24 Accuracy of the Data By transferring samples only when necessary and using pipetting techniques instead of filtering methods. sample loss was held to a minimum. Each sample was handled and treated in the same manner so any errors that were inherent to the laboratory procedure were con- stant in all samples, thus minimizing their effect. In regard to the accuracy of the Mg/Ca data. Jodry (1955) states tha reasonable care in this analysis should give values for CaO and MgO within 0.5 percent accuracy. Results of Laboratory Analysis Table III shows the results of the laboratory analysis. These data were used to compute the ratios shown in the following section. and the results are given in Table IV. TABLE III QUANTITATIVE ANALYSIS 25 Well Sample Water Ac1d Solubles Sand 3121:;(1 . ' ht S l bl s ' No Weig o u e HCl HNO3 Fraction Fraction 1 119.777 0.592 89.372 6.593 0.459 32.319 2 124.578 0.773 78.734 8.212 1.408 43.663 3 133.819 0.969 95.880 13.142 2.543 34.426 4 123.958 0.737 109.581 5.494 1.898 11.736 5 125.200 1.771 94.878 9.077 0.467 28.084 6 121.540 0.923 85.454 15.590 1.903 33.240 7 130.602 0.494 116.467 3.230 1.017 12.624 8 120.209 0.784 109.392 8.539 0.209 9.811 9 127.358 0.192 85.941 11.365 0.759 40.465 10 107.209 0.928 47.440 6.233 2.155 56.686 11 93.570 3.937 60.753 8.667 14.710 14.171 12 108.982 0.312 83.198 10.019 1.515 23.858 13 123.429 0.615 105.156 3.675 1.979 15.678 14 103.179 0.916 82.102 6.223 0.788 19.474 15 116.670 15.285 83.367 7.220 1.279 16.738 16 115.061 0.352 75.037 15.919 2.633 37.042 17 125.143 15.630 89.362 7.469 1.558 18.602 18 130.534 0.230 94.288 16.212 3.148 32.867 19 113.185 0.751 84.231 0.119 2.627 25.576 20 81.685 1.263 70.558 2.705 0.788 9.076 21 103.443 1.516 85.833 9.373 4.111 12.982 22 124.888 0.505 104.505 11.947 3.092 16.787 23 124.469 0.217 114.157 5.186 2.949 7.136 24 122.528 1.346 91.545 7.037 2.585 20.016 25 65.123 0.682 42.493 1.843 1.425 18.681 26 121.759 3.436 81.025 3.738 7.426 26.124 W w TABLE IV LITHOLOG IC RATIOS 26 Sample Sand- Shale Clatic Evaporite Mg/Ca Anhydrite Number Ratio Ratio Ratio Ratio Percentage 1 0.053 0.354 0.083 0.591 5.504 2 0.033 0.514 0.114 0.305 6.592 3 0.074 0.336 0.147 0.435 9.821 4 0.162 0.117 0.057 0.347 4.434 5 0.017 0.270 0.114 0.708 7.250 6 0.057 0.345 0.193 0.659 12.827 7 0.081 0.113 0.035 0.605 2.473 8 0.021 0.084 0.085 0.528 7.107 9 0.019 0.423 0.134 0.360 8.924 10 0.038 1.007 0.150 0.935 5.814 11 1.04 0.393 0.207 0.720 9.263 12 0.064 0.271 0.124 0.261 9.193 13 0.124 0.161 0.041 0.577 2.971 14 0.035 0.226 0.087 ----- 6.031 15 0.076 0.170 0.269 '---- 6.188 16 0.071 0.431 0.216 0.599 13.835 17 0.084 0.179 0.258 0.240 5.968 18 0.096 0.325 0.174 0.270 12.420 19 0.103 0.331 0.010 0.077 0.105 20 0.087 0.132 0.048 0.419 3.312 21 0.317 0.178 0.115 0.634 9.061 22 0.184 0.169 0.119 0.667 9.566 23 0.413 0.084 0.047 0.685 4.166 24 0.129 0.226 0.092 0.625 5.743 25 0.076 0.447 0.059 0.626 2.830 26 0.284 0.381 0.089 0.445 3.070 LITHOLOGIC INTERPRE TA TIONS Lithologic Ratios By its very nature. the areal extent and variation of lithology in geologic sections are best portrayed on a lithofacies map. Most lithofacies maps are based on numerical data which can be expressed as percentage. thicknesses of various lithologies. or as lithologic ratios. The writer used ratio and percentage maps in preparing the lithofacies maps for this report. Krumbein (1952) states: "The ratio method is based on the use of the end-member concept which contrasts the relations among end-members present. In essence the ratios yield easily visualized values of numerator type rock per foot of denominator type rock." The following are the ratios used by the author in this investigation. The Clastic ratio is expressed by the formula: Clastic Ratio = Conglomerates + Sandstone + Sha1e Limestones + Dolomites + Evaporites A ratio of "one" would represent equal amounts of clastic and nonclastic material. A ratio greater than one indicates a greater amount of clastic than nonclastic material; values less than One indicate more nonclastic than elastic material. 27 28 Variations in elastic material are represented by the sand- shale ratio. The formula for this ratio is computed as follows: Conglomerate + Sandstone Sand-Shale Ratio = - Silt + Clay A formation containing only sandstone is expressed by a sand- shale ratio of infinity; a formation containing only shale has a ratio of zero. In order to show variation within nonclastic material an evaporite ratio is used and computed in this manner: Evaporite Limestone + Dolomite Evaporite Ratio = A section containing an equal amount of evaporite and lime- stone is represented by a ratio of one. With an increasing amount of evaporites the ratio approaches infinity; an increase in carbonates will produce a ratio which approaches zero. Due to drilling techniques and the washing of samples prior to their use in this investigation, there was loss of the more soluble evaporites such as salt. The writer feels an evaporite ratio can still be of value in this investigation if the inaccuracies caused by This evaporite loss are kept in mind when interpreting the evaporite facies map. 29 A magnesium/calcium ratio showed the variations in the car— bonate material in the formation. The general formula for this ratio can be represented by: . _ %M Mg/Ca R8110 - 70% The use of this formula produces a ratio that varies between zero and one for limestones and dolomites. With an increase of dolomite over limestone the ratio approaches one; an increase of limestone over dolomite produces a ratio which approaches zero. A percentage anhydrite facies map was constructed to point out the depositional areas of the relatively large amounts of anhydrite found in the Upper Detroit River. The anhydrite percentages were obtained by the formula: Weight of Anhydrite Weight of Total Sample. Anhydrite Percentage = From the above formula it is easily seen the higher-the an— hydrite content the higher the anhydrite percentage. Table IV lists the ratio or percentage values for each of the wells analyzed. 30 Construction of Facies Maps To construct facies maps of lithologic ratios or percentages the numerical data found in Table IV were plotted at each well lo— cation on a base map of Michigan. Isopleth lines of equal ratio or percentage values were then .drawn connecting points of equal value. The isopleth spacing was based on arithmetic rather than geometric intervals. The Isopach map was constructed on semitransparent paper; the ratio maps were drawn on opaque paper. Using this method the isopach map may be superimposed on the various facies maps when using Krumbein's (1952) method of lithofacies interpretation. Maps 4. 5, 6. 7. 8. and 9. found in the "pocket" of this re- port. are the isopach. Clastic. sand-shale. evaporite. Mg/Ca. and anhydrite lithofacies maps. respectively. Methods of Geologic Interpretation To aid in the interpretation of facies mape Krumbein (1952) proposed a systematic method. This method of interpretation is based on the relation between isopleth and isopach lines. By super- imposing the isopach map on the lithofacies map. Krumbein found the Six types of patterns as shown in Figure I. FIGLIRE I RELATIONS OF ISOPACHS (SOLID) AND FACIES LINES KRUMDEIN (I952) / \\\ / / \ \ \ /// \ ./ / // \ / LINEAR UNEAR SUBPARALLEL DISOORDYANT ——\—‘<’/ CURVILINEAR CONCENTRIO DISOORDANT OVATE OVATE SPOTTY I DISOORDANT - IRREGULAR 32 Describing some of the patterns. Krumbein (1952) states: The linear sub-parallel pattern may occur under conditions where clastic sediments are spread over a subsiding area in de- creasing amount away from the sources. so that the elastic ratio lines tend to decrease as the isopachs increase because of in- creasing lime deposition. The curvilinear discordant pattern may arise when a local concentration of clastics is poured into a subsiding area. such as a delta. Here the Clastic ratio lines may project farther into the basin than normally. The con- centric ovate pattern is characteristic of evaporites in an intra- cratonic basin. The irregular spotty pattern occurs near the deteriorating edges of sheet sands. where the accumulation be- comes patchy or spotty. Krumbein also states that three of the patterns are normally associated with intracratonic basin conditions. such as found in the Michigan basin. The interpretation of these patterns indicate and locate the tectonics which controlled sedimentary deposition. The three patterns are: 1. Curvilinear discordant patterns-indicate either a nearby orogenic or epeirogenic source. 2. Concentric-ovate patterns--infer either a nearby orogenic or epeirogenic source or a distant orogenic source. 3. Discordant-ovate patterns--indicate either a nearby orogenic or nearby epeiorgenic source. Using Krumbein's (1952) methods of facies analysis. the writer presents the following interpretations of the facies maps constructed from this investigation. 33 Lithofacies Interpretations The elastic ratio map. This map indicates the Michigan basin received elastic sediments from four sources during Upper Detroit River time. The highest elastic concentration is in the southwest section of the state. in Berrien. Van Buren. and Cass counties. Applying Krumbein's facies analysis techniques. a com- bination of linear subparallel to curvilinear discordant patterns are noted. These patterns indicate elastic sediments derived from a nearby orogenic or epeirogenic source spreading over a subsiding area. This spreading. coupled with the fact that the elastic ratios are decreasing in value to the northeast. indicates a possible source area to the southwest. High elastic ratios are found in the southeast section of the state in Lapeer. Macomb. and Saint Clair counties. The elastic isopleth lines open to the southeast and close to the northwest. They decrease in value towards the center of the basin. A curvi- linear discordant pattern is noted in the southeast which indicates a nearby orogenic source. A third elastic high is in the western part of the Lower Pen- insula in Mason and Manistee counties. The isopleth lines open to the west and close to the southeast. and show a decrease in clastics 34 in a general southeast trend. This trend. along with a curvilinear discordant pattern. indicates a source area to the west or northwest. A fourth area of moderately high elastic ratios is found in the north section of the state. with its center in southern Cheboygan County. A source area to the north is indicated by a curvilinear discordant pattern and a decrease in clastics to the south. A summary of the inferred structural features determined from the elastic ratio map is: l. A broad ridge Of elastic material extending in a northeast direction from Saint Clair County to Clare County. The trend of this ridge indicates a source area to the southwest. possibly the Findlay arch. 2. A ridge of high elastic content originates at the west side of the Lower Peninsula in Mason and Manistee counties and trends southeast to Barry County. Its location and development indicate a source area to the west or northwest. possibly from the Wisconsin dome. 3. A broad elastic ridge. in the north part of the state. showing a curvilinear discordant pattern with a south trend. indicates a Canadian Shield source area. 4. A shelf area having a rapid decrease in elastic material 10 the northeast is in the southwest section of the state. ' Subparallel 35 discordant to curvilinear discordant patterns. with a decrease in elastic material northeast. indicate a source area to the southwest. possibly the Kankakee arch. The sand-shale map. Inspection Of the sand-shale ratio values on the map indicates three different relations exist between the sand and shale deposition. In the west part of the state the ratio value of 1.004 indicates equal amounts of sand and fine elastic material were deposited. In the north a low ratio of 0.100 indicates a preponderance of fine elastic material. Ratio values of 0.300 to 0.400 found in a band following the southern border of the state from Saint Clair County to Allegan and Ottawa counties indicate moderate amounts of sand compared to fine elastic material. The highest sand-shale ratio is in Mason County. The sand fraction decreases to the southeast with the isopleth lines closing to the east and opening to the west. This feature extends in a belt three counties wide from Mason County in the west to Clinton and Shiawassee counties. The curvilinear discordant pattern covering this area indicates a nearby epeirogenic source to the west or northwest. Another area of moderately high ratios is located in the north part of the Lower Peninsula extending from Charlevoix and lower 36 Cheboygan counties to Iosco County. The lithofacies lines close to the south and open to the north. The curvilinear discordant patterns and the decrease in sand to the southeast indicates a nearby epei- rogenic source area to the north or northwest. There is also a band of moderately high ratios found in the southern part Of the state. These ratios decrease in value toward the center of the basin. A linear subparallel pattern in this area indicates a possible subsiding shelf area with an epeirogenic source to the southwest. south. and southeast. A summary of the features indicated by the sand-shale facies map: 1. There is a ridgelike feature of high sand-shale ratios striking southeast from Mason County to Clinton County; the source area is to the west or northwest. 2. A south to southwest trending ridge in the northern por- tion of the state indicates a possible source from the Canadian Shield. 3. A band of moderate sand-shale ratios paralleling the Southern border of Michigan indicates the sediments were derived from the southwest. south. and southeast. 4. Variations in the sand-shale ratios indicate the structural features surrounding the basin during Upper Detroit River time did 37 not have equal relief. The higher sand content in the west—central portion of the state indicates the Wisconsin dome area had slightly higher relief than the other tectonic features bordering the basin during the deposition Of the Upper Detroit River sediments. The evaporite ratio map. The highest concentration of evaporites is in Roscommon County near the geographical center of the basin. The evaporite ratios decrease in value from this high and delineate an ovate pattern extending from Otsego County in the north to Kent County in the south. and from Saginaw Bay in the east to a position in Lake Michigan west of Mason County. The concentric ovate pattern found in this area indicates the deposition of evaporites in an intracratonic basin. A bar or ridgelike feature Of low evaporite values is sur- rounded by an area of higher ratios in Newaygo and Osceola counties. This pattern indicates a topographic high in a restricted evaporite basin. A minor evaporite high is in the southwest part of the state in Berrien. Van Buren. and Cass counties. This feature trends northeast-southwest and decreases in evaporite content to the north- east. A curvilinear discordant pattern suggests a nearby epeirogenic source. possibly to the southwest. 38 Another moderate evaporite high in Genesee and Lapeer counties in the Thumb Area of Michigan is elliptical in shape and trends northeast-southwest. A curvilinear discordant pattern indi- cates a nearby epeirogenic source. A summary of the structural features represented by the evaporite ratio map are: 1. A large evaporite basin is located in the northern half of the Lower Peninsula. 2. A ridgelike feature in Newaygo and Osceola counties strikes northeast. This feature indicates a topographic high not suitable for evaporite deposition. An alternative explanation might be nondeposition due to the inflow of fresh water. The writer re- jected this last hypothesis because the high evaporite ratios which completely isolate the area give no indication of a fresh water inlet. 3. A minor evaporite high in the southwest section of the state indicates possible local conditions favorable for the deposition of evaporites. 4. A third evaporite high located in the Thumb Areaiof Michigan also indicates local conditions favorable for the deposition of evaporites. Conditions which could cause local evaporite deposi- tion are local subsidence. topographically low areas. and high 39 concentrations of evapororite salts due to isolation from a source of fresh water. The anhydrite percentage map. An oval-shaped anhydrite concentration in Clare County. the center of the Michigan basin. covers an area which includes the northeast. central. southeast. and southwest parts of the Lower Peninsula. This ovate pattern. with decreasing anhydrite values toward the periphery. indicates a re- stricted evaporite basin in an intracratonic depositional area. A barrier or ridgelike feature indicated by low anhydrite values surrounded by higher anhydrite concentration is found in Newaygo, Osceola. and Missaukee counties. This feature trends northeast-southwest and corresponds to a similar feature shown on the evaporite ratio map. Two areas having high anhydrite concentrations. separated by an area with lower anhydrite values. are located near the shore of the present Lake Michigan in the west-central part of the state. One of the anhydrite highs is in Manistee County; the other. in Oceana County. The area of low anhydrite concentration separating the two highs is in Mason County. A pattern of this type indicates a possible coalescing of two lagoonal areas favorable to anhydrite deposition. 40 A triangular-shaped area in Calhoun. Jackson. and Eaton counties. containing low anhydrite percentages surrounded by higher anhydrite concentrations. indicates a topographic high or shelf area in an evaporite depositing environment. A deltaic pattern of low anhydrite concentration is centered in Cheboygan County. The isopleth lines closing to the south and opening to the north have increasing anhydrite values toward the center of the basin. This depositional pattern may indicate an inflow of fresh marine water from the north which lowered the anhydrite concentration in the area. The features indicated by the anhydrite facies map are: 1. An oval-shaped pattern with a high anhydrite concentration in Clare County covers all but the north. northwest. and west-central parts of the Lower Peninsula. This ovate pattern is indicative of evaporite deposition in an intracratonic basin. 2. A ridgelike feature in west-central Michigan is indicated by low anhydrite concentration. 3. Two coalescing lagoonal areas of high anhydrite concen- tration. located in the west-central part of the state. extend into the area now occupied by Lake Michigan. The location of these lagoonal areas indicates the western limit of the Michigan basin was farther 41 west than the present-day Lake Michigan shore line during Upper Detroit River time. 4. Low anhydrite concentrations indicate a topographic high. possibly a shelf area. in south-central Michigan. 5. A deltaic feature of low anhydrite concentration in north- ern Michigan indicates a possible inflow of fresh marine water from the north. 6. A general picture of the Michigan basin during the depo- sition of the Upper Detroit River evaporite sequence is not that of a smoothly sloping basin. but one containing local relief or raised places, which tends to retard the deposition of evaporite in these areas. The magnesium/calcium ratio map. According to Briggs (1957) and Landes (1951). the normal sequence of carbonate and evaporite precipitation in a marine environment is: limestone fol- lowed by dolomite. gypsum. anhydrite. and halite. Chilingar and Bissell (1957) state that a high magnesium content in a carbonate rock indicates shallow and warm water conditions. and a high cal- cium content can be interpreted as a gradual subsiding or deepening in a depositional area. 42 Examination of the Mg/Ca ratio map indicates that north Of a line running diagonally across the state from Benzie County to Macomb County. limestone is more abundant. than dolomite. whereas south of this line the ratios indicate a higher percentage of dolomite. Thie depositional pattern indicates shallow water shelf condi- tions in the southwest part of the state. North of a line extending from Benzie to Macomb counties. the increase of limestone over dolomite indicates deeper water conditions. This may be caused by greater subsidence of the Michigan basin in this area during Upper Detroit River time. REGIONAL TECTONICS AND CONCLUSIONS Structures Related to the Michigan Basin The structural features which led to the development of the Michigan basin were in existence long before Middle Devonian time. The Precambrian Shield complex confined the basin in the north. The Wisconsin dome. which was developed by uplift in Ordovician time. bordered the basin to the west (Eardley. 1951). According to Pirtle (1932) and other investigators. the south— east. south. and southwest limits of the basin were defined by the Findlay and Kankakee arches. The Findlay arch strikes northeast from central Ohio to southwest Ontario. and is related in age to the Cincinnati dome formed during Ordovician time. A gap in the Findlay arch, the Chatham sag. located in the vicinity of Lake Saint Clair. was a con- necting link between the Appalachian Geosyncline and the Michigan basin for periods of time during their development (Landes. 1951). (The Kankakee‘ arch extends northwest from northwest Indiana to southeast Wisconsin. This connection between the Wisconsin and 44 Cincinnati domes is believed to be more closely related to the Wis- consin dome in age (Pirtle. 1932). Keeping in mind the geological setting prior to Middle De- vonian time. and using the formation gained from the interpretation of the lithofacies maps. the following tectonic and sedimentary rela- tions were indicated during the deposition of the Upper Detroit River sediments. Sedimentary and Tectonic Interpretations Clastic ratio map. The elastic material deposited in the Michigan basin was not supplied by one area. but was derived from four areas surrounding the basin. This indicates the Michigan basin was a topographic depression. surrounded by topographically higher areas. for some times during development of Upper Detroit River sediments. The highest elastic values were found in southwest Michigan, indicating a source area to the southwest. The area of lowest elastic accumulation was in Cheboygan County; and the sediments were derived from the north. Source areas for the two intermediate elastic accumulations in southeast and west-central Michigan are northwest and southeast. respectively. 45 It is interesting to note that the Chatham sag and. the source of the Clastic material found in southeast Michigan coincide. This may indicate the Chatham sag was emergent at times during Upper Detroit River deposition. A summary of conclusions gained from the clastic ratio map are: 1. The basin received elastic sediments from four different sources in Upper Detroit River time—-the Wisconsin dome. Kankakee arch. Findlay arch. and the Canadian Shield. located in the west. southwest. southeast. and north. respectively. 2. The four areas of Clastic accumulation did not receive equal amounts of clastic material. indicating the structural features bounding the basin varied in relief. 3. The Chatham sag was emergent from time to time during the basin's development. Sand-shale map. The variation between the sand-shale ratios in the four areas of Clastic accumulation show that the sources which supplied these sediments were of unequal relief. The sand- shale ratios indicated the following: 1. The Wisconsin dome supplied the highest percentage of sand-size material and had a moderate relief. 46 2.. The Findlay and Kankakee arches were relatively stable and low in relief. 3. The Canadian Shield supplied the least amount of coarse. elastic material and had little relief. A summary of conclusions based on the sand-shale ratio map is: 1. The basin received clastic sediments from four sources during Upper Detroit River time. 2. The Findlay arch. Kankakee arch. and the Canadian Shield area were relatively stable and low-lying. 3. The Wisconsin dome had moderate relief during Upper Detroit River time. Evaporite ratio map. The evaporite ratios show the existence of a large evaporite basin in the geographic center of the Lower Peninsula. Two small evaporite concentrations are found in southern Michigan: one located in the Thumb Area. the other in the south- west corner of the state. The existence of a northeast-trending ridge in west-central Michigan is indicated by a concentration of low evaporite values en- closed within an area of higher evaporite ratios. 47 A summary of the conclusions based on the evaporite map is: 1. The relatively high evaporite concentrations which were precipitated in the basin indicate the structural features surrounding the basin were emergent for periods of time during the development of the Upper Detroit River group. 2. The thick evaporite section found in the center of the basin indicates subsidence was contemporaneous with deposition. 3. A barrier or ridgelike feature in west-central Michigan separates the central basin from a similar basin located farther to the west. 4. Two local depressions favorable to evaporite precipitation are found in southern Michigan--one in the Thumb Area. the other in the southwest corner of the state. 5. Local relief in the Michigan basin effected the precipita- tion of the evaporites during Upper Detroit River time. finhydrite percentage map. The center of a large oval- shaped anhydrite concentration was found in Clare County, the geo- graphical center of the Michigan basin. In west-central Michigan two coalescing lagoonal areas con— taining high anhydrite concentrations extend into an area now oc- cupied by Lake Michigan. 48 A northeast-trending ridge in west-central Michigan corre- sponds to the one shown on the evaporite map. A triangular area of low anhydrite values. in the south-central part of the state. reveals a topographic high not suited to anhydrite deposition. A summary of the conclusions based on the anhydrite per— centage map is: 1. The center of the evaporite sequence formed during Upper Detroit River time is located in the central portion of the Michigan basin. 2. A ridge or barrier in west-central Michigan separates the main evaporite basin in central Michigan from two coalescing evapo- rite basins found farther to the west. 3. The location of anhydrite basins in and on the shore of Lake Michigan indicates the western limit of the basin was farther west than the present Lake Michigan shore line during Upper Detroit River time. Magnesium/calcium ratio map. The carbonates deposited north of a line extending from Benzie to Macomb counties are pre- dominately limestones; south of this line dolomites predominate. Summary of conclusions based on the Mg/Ca ratio map is: 49 1. The northeast and central portions of the Michigan basin were subsiding at a greater rate than the other sections of the basin during Upper Detroit River time. 2. The southwest section of the state was a shallow shelf area little affected by subsidence during Upper Detroit River time. Conclusions W This investigation indicates the following environmental and tectonic features influenced the deposition of Upper Detroit River sediments. 1. The structural features surrounding the basin were stable and low-lying. Z. Clastic sediments entered the basin from four areas--the north. west, southeast. and southwest. 3. The Wisconsin dome was higher in relief than the other structural features bounding the basin. 4. There were no major crustal disturbances in or around the basin. 5. Deposition began and ended quietly with the encroachment of warm limestone-precipitating seas. 6. Subsidence and deposition of the thick evaporite series. particularly in the center of the basin. were contemporaneous. 50 7. The basin was restricted from other areas for periods of time due to the emergence of the positive structural features sur- rounding it. 8. The topographic features within the basin helped control the deposition of nonclastic material. 9. Lagoonal-type basins in west-central Michigan indicate the western limit of the Michigan basin was farther west than the present Lake Michigan shore line. In studying the Traverse group (Upper Devonian). Jodry (1957) indicated the presence of a barrier in west-central Michigan which separated a large area of western Michigan from the main basin to the east. He indicates this barrier is related to pre-Devonian fold- ing. The results of this investigation indicate that such a barrier existed during Upper Detroit River time. Landes (1951) stated the gap in the Findlay arch (the Chatham sag) was emergent for periods of time during the development of the Detroit River group. The results of this study support this belief. This investigation indicates the feasibility of using chemically derived Mg/Ca ratios in a regional sedimentary facies analysis. The writer feels more work along this line would result in a better under- standing of the environmental conditions necessary for the precipita- tion of limestone and dolomite. REFERENCES Baltrusaitis. E J . et al. (1948). A summary of the stratigraphy of the southern peninsula of Michigan. pp. 1-16. mimeographed. Briggs. L. I. (1956). Quantitative Aspects of Evaporite Deposition. Michigan Academy of Science. Arts and Letters. Vol. XLII. pp. 115-123. fl WP“ Cooke. L. W.. Jr. (1956). Unpublished thesis. A Quantitative Sedi- mentary Analysis of the Ordovician Deposits in the Michigan Basin. Michigan State University. Eardley. A. J. (1951). Structural Geolog of North America. Harper Bros. New York. pp. 2.4-37.fi E ‘ Epis. R. C.. and C. M. Gilbert (1957). Mississippian Joana Lime- stone of Cordilleran Miogeosyncline and Use of Mg/Ca Ratio in Correlation. Am. Assoc. Petrol. Geol. Bull. Vol. 41. pp 2257 2274. ' Green, D. A. (1957). Trenton structure in Ohio. Indiana. and north- ern Illinois. Am. Assoc. Petrol. Geol. Bull., Vol. 41, pp. 627-643. *T' ‘ ’“* '5 ‘ Jodry. R. L. (1955), Rapid Method for Determining Mg/Ca Ratios of Well Samples and Its Use in Predicting Structural and Sec- ondary Porosity in Calcareous Formations. Am. Assoc. Petro. Geol. Bull.. Vol. 39. pp. 493-511. h C m Jodry. R. L. (1957). Reflections of Possible Deep Structures by Traverse Group Facies Changes in Western Michigan. Am. Assoc. Petro. Geol. Bull. Vol. 41. pp. 2677-2693. Krumbein. W. C. (1952). Principles of facies map interpretation. Jour. Sed. Petrolfl. Vol. 22, pp. 200-211. Krumbein. W. C. . and F. J. Pettijohn (1938). Manual of Sedimentary Petrography. Appleton- Century- -Crofts. New York. 51 52 Landes. K. K. (1951). Detroit River Group in the Michigan Basin. US. Geol. Survey Circular 133. Landes. K. K., G. M. Ehlers. and G. M. Stanley (1945), Geology of the Mackinac Straits Region. Mich. Geol. Survey Bull. 44. Moore. R. C. (1949). The meaning of facies. Geol. Soc. Am.. Men 391 pp. 1'34. '—'— f Newcombe. R. J. B. (1933). Oil and gasfields of Michigan. Mich. Geol. Survey Div” Pub. 38. Geol. Ser. 32. Pettijohn. F. J. (1956). Sedimentary Rocks. 2d Edition. Harper and Bros. New York. Chapters 9-15..- Pirtle. G. W. (1932). Michigan structural basin and its relationship to surrounding areas. Am. Assoc. Petrol. Geol. Bull.. Vol. 16. pp. 145-152. M V fi‘ Tinklepaugh. B. M. (1957). Unpublished thesis. A Chemical Statistical and Structural Analysis of Secondary Dolomitization in the Rogers City-Dundee Formation of the Central Michigan Basin. Michigan State University. Wentworth. C. K. (1922). A scale of grade and class terms for clastic sediments. Jour. Geology. Vol. 30, pp. 377-392. Wentworth. C. K. (1926). Methods of mechanical analysis of sedi- ments. Univ. Iowa Studies in Nat. History. Vol. 11. No. 11. Wiegner. G. (1927). Method of preparation of soil suspension and de- gree of dispersion as measured by the Wiegner-Gessner ap- paratus. Soil Sci.. Vol. 23, pp. 377—390 (translated by R. M. Barnette). .1. nv.ll.\-‘ 1 llllll (is! 11.x! VOCQb-k knit / fiéLJ/é (W‘M‘o 3’ a) "Illlllllllllll'llllls