SUBSURFACE ANALYSIS OF THE MIDDLE DEVONIAN SYLVANIA SANDSTONE IN THE MICHIGAN BASIN Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY RYAN GLENN KEMPANY 1976 ABSTRACT SUBSURFACE ANALYSIS OF THE MIDDLE DEVONIAN SYLVANIA SANDSTONE IN THE MICHIGAN BASIN By Ryan Glenn Kempany The Sylvania sandstone is of Lower Middle Devonian age and represents a basal transitional formation into the overlying Detroit River Group of lower Michigan and north- western Ohio. Wild (1958) was the last person to attempt research on this stratigraphic unit but the most extensive study was completed by Grabau and Scherzer in 4907. In view of the availability of additional sample data as well as mechanical logs, a restudy of the unit was considered advisable, especially as increased interest is being shown on the part of some petroleum/gas companies. Information for analysis was acquired by examination of well cuttings, gamma ray-neutron logs and printed driller-geologist logs supplied by the Michigan Geological Survey. Regional iSOpaCh and structure contour maps were constructed employing approximately one hundred control wells. Tops are derived predominantly from samples but when drill cuttings were not available for key wells, gamma ray-neutron logs were used to supplement the data. Ryan Glenn Kempany Lithofacies trends were delineated from subsurface samples and displayed as sand, carbonate, chert and evaporite percentage maps, and also as a clastic ratio map generated to determine the paleoenvironment and history during Sylvania time. From this investigation it can be concluded that fluvial and perhaps some eolian processes supplied sand to the seaway where it was reworked, redistributed and redeposited by marine currents and waves within a persis- tent shore line environment, predominately along with carbonates of the Sylvania age sea. The St. Peter sand- stone of Lower Middle Ordovician age in the Wisconsin Highland area to the northwest, the Findlay Arch area to the east and southeast, and the Canadian Shield area to the northeast are considered to be chief sources for the Svlvania sandstone. SUBSURFACE ANALYSIS OF THE MIDDLE DEVONIAN SYLVANIA SANDSTONE IN THE MICHIGAN BASIN By Ryan Glenn Kempany A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Geology 1976 ACKNOWLEDGMENTS I gratefully express my thanks to Dr. Prouty, Chairman of the guidance committee, who devoted much of his time and interest in this problem and in the critical review of this manuscript. Thanks are extended to Dr. Carmichael and for and the the her Dr. Stonehouse, other members of the guidance committee, their helpful suggestions and review of the thesis text illustrations. Acknowledgment is extended, also, to the members of Michigan Geological Survey for their c00peration in use of well samples and mechanical logs. Further appreciation must go to Sherryl E. Frank for patience and skill in typing this thesis from.barely legible c0pies, in addition to doing other tasks which allotted me valuable time to complete the more demanding aSpects of this investigation. ii TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES LIST OF CHARTS INTRODUCTION 'Scope and Purpose of Investigation Previous Work TECTONIC FRAMEWORK OF THE MICHIGAN BASIN Regional Structures Intrabaslnal Structures GENERAL STRATIGRAPHY Pre—Sylvania Geologic History METHOD OF INVESTIGATION DETAILED STRATIGRAPHIC ANALYSIS Lithology Contact Relationships Distribution and Thickness Mineral Variation Maps ENVIRONMENTAL INTERPRETATION Origin of Sediments Sedimentary and Geologic History ECONOMIC CONSIDERATIONS SUMMARY AND CONCLUSIONS BIBLIOGRAPHY APPENDICES Appendix A Appendix B iii Page iv vi A 0000me ’I6 25 23 29 35 40 49 49 51 54 55 57 61 6’1 65 \D 11. 12. 15. 11+. 15. 16. LIST OF FIGURES Stratigraphic Succession in Michigan Major Structural Trends in the Michigan Basin and Adjacent Areas Structural Contour Map on Top of the Sylvania Sandstone Nomenclature of Michigan Formations Areal Distribution of Formations Beneath the Sylvania Sandstone Sylvania Cross—Sectional Locations Sylvania Sandstone Cross-Section A—A' Sylvania Sandstone Cross—Section B—B' Distribution of Coarse and Silt Sized Grains Facies Map of the Sylvania Carbonate Fraction Isopach Map of the Sylvania Sandstone Sandstone Percentage Map Carbonate Percentage Map Clastic Ratio Map Chert Percentage Map Evaporite Percentage Map iv Page ’13 15 2O 21 22 25 26 57 41 42 45 46 47 LIST OF TABLES Page 1. Typical Sylvania Sandstone Lithologic Column 30 2. Wells Used in Construction of the Structural Contour and Is0pach Maps 61 5. Wells Used in Construction of the Percentage and Ratio Maps 65 LIST OF CHARTS Page 1. Stratigraphic Succession of Upper Silurian through Middle Devonian Units in Michigan 13 vi INTRODUCTION Scope and Purpose of Investigation The Sylvania sandstone is of Lower Middle Devonian age and represents a basal transitional formation into the overlying Detroit River Group in southeast Michigan and northwest Ohio (Figure 1). Recent wells drilled, involving the sandstone, are encountering difficulty in determining the contact relationships and stratigraphic position relative to underlying units. In addition, lateral gradations are questionable. Wild (1958) was the last person to attempt research on this thus-far econom- ically unproductive formation and the only truly extensive study was completed by Grabau and Scherzer in 1907. Since that time, the Sylvania sandstone has been discussed only as a component part of the Detroit River Group to which it'belongs. In view of additional sample data as well as mechanical logs the Sylvania sandstone needs restudy. The purpose of this investigation has therefore been to: 1) establish subsurface relationships of the sandstone to the under— lying Bois Blanc and Bass Island disconformable units, 2) analyze the lithology and determine the distribution mm mm . STRATIGRAPHIC SUCCESSION IN MICHIGAN svsm sans sue! U meow: mom" «can 6 1.0": b“ N v".- nua- 9-d- n H O aunumv woe-u chi-'- a, u G Z I“ u. “I *W U “M OUTCROP NOMENCLATURE SUBSURFACE NOMENCLATURE ‘/ “$3,“ wustumumc mourn-W noasmmunoc “W'I‘xm 8 3 romnou Imml caouv nun-mu— : 5 smss cnouv romnon mm w... ........ ..” _ ._ d m. ,_,, wt Inn-nun... lm E 3'. W‘ m” III-M new W w‘h‘dfi-hh— ~11 D h bonny-q ”cm.d--wmd#- wlddfih. “I (mwdhfl’h Hw“h-dfl~’w “a!” Wlflh—bil‘ub-v MIWIHHI—xhob— "mm middfim-JIh-d’ baud-undu- *dehuhdmumub o SMMW mm PAYS laid—Id Wk.._ ha.- """'~‘" ‘33:. W -~¢w- In I-u in. “C. Wu n-oa w...- (nfllwfi ”all 6- Ian-ad“ bout-Id HI- _I-‘Il---hvi_oulu has: I-dh-hid-u..u Ian-Ink ion-I- au- luv-v04 "I-‘h- [mo-c..- Ina—u- u..- H Inna-- one ”Ital. COC- Mh ouc- Mountb- mdluuul-n Hou- ouc- *d ’h‘ on... b ~_ bl“- .I-sunufiyt- hun- uu... moc— ml— bu- MdH-n .— Guolu— c-‘:—' ll Mil? (ab-- —_ ““- o- w.— ' "'"‘ “(club—nu.— onlo- ”fld 5—” II S . {on COG-I ~— o—u- hnd'ln-u-h'n— nun-tun Iva-man. auc- “bl-— th—‘flhfi I._ou¢- '0'“— OI-IIN (- mummhflb-WHMWI “I‘d“kWINWW’Hh‘QWJ wmw'*.w'*~-MJ~ —|Hhhfl”‘-4‘ r~’ . -.. .,‘.. .— .0»- I." pattern, 5) establish a relationship of the Sylvaniatx> the overlying carbonate section, 4) gather information adding to a better understanding of the nature and direc- tion of the source, 5) develop a model concerning the depositional environment as deduced from composition and physical properties, 6) update structure and isopach interpretations, and 7) make observations concerning clastic ratio, sandstone, carbonate, evaporite, and chert distribution patterns. Previous‘Work The Sylvania sandstone was named by Edward Orton in 1888, but has been recognized and discussed in literature since 1857 when John L. Riddell (1837, p. 9) reported the occurrence of a calcareous sandstone along the Maumee River in Ohio. In 1896, J. S. Newberry (1870, p. 16) recognized a correlation of the white saccharoidal sand- stone, not more than 20 feet thick in the northwestern part of Ohio, with the Oriskany sandstone, lowest member of the Devonian in New York. In 1888, Orton (1888, pp. 18- 20), then State Geologist of Ohio, considered the Sylvania sandstone an Upper Silurian sandstone, correlated it with the sand deposits of Monroe County, Michigan, but named it after its exposure near Sylvania, Ohio. A. W. Grabau (1907, p. 832), on the basis of field work in Michigan with Scherzer on the Sylvania and Upper Monroe, presented evidences of the eolian origin of the Sylvania sandstone 4 and included it as part of the Monroe formation. This formation (Lane, Prossar,.Sherzar, and Grabau, 1908, pp. 553-556) was divided into the Lower Monroe, represented by the Bass Island series; the Middle Monroe, represented by the Sylvania sandstone; and the Upper Monroe, represen- ted.by the Detroit River series. The age of the Monroe formation was given as Silurian (Sherzer and Grabau, 1908, pp. 540-553). They also postulated a northwestern and eolian origin for the Sylvania sandstone which possessed such purity and rounding it was considered to "out-Sahara the Sahara." In 1927, J. E. Carman (1927, pp. 481—506) concluded on the basis of geographical distribution of the members, stratigraphical relations, and faunas, that the Upper and Middle Monroe were of Lower Devonian age. German (1927, p. 506) further stated that the Sylvania is strati- graphically and faunally so closely related to the over- lying Detroit River formation that both must be included in the same age. S. W. Alty (1952, pp. 289-300) studied the heavy mineral content of the Sylvania rocks from Michigan oil wells and found that the heavy minerals seemed to decrease from southeast to northwest. Carman (1956, pp. 253-266) studying the Sylvania sandstone of northwestern Ohio postulated that the Sylvania represents the basal member of the Detroit River dolomite in a transgressive overlap by the Sylvania sea toward the southeast. He thus questioned the eolian origin of the Sylvania as proposed by Grabau and Sherzer giving evidence for marine deposition of the Sylvania. R. L. Enyert (1949) on the basis of sedimentary analysis of outcrop samples, subsurface well samples, and well logs concluded that the Sylvania sandstone is the product of a wind-transported, water reworked sand probably deposited in a marine environment. The St. Peter sandstone, of Lower Ordovician age, in the Wisconsin Highlands to the 'northwest was considered to be the chief source of the Sylvania sandstone. Landes (1951) placed this sandstone within the Detroit River Group, and considered it to be a member of the Amherstburg formation because of the general transition between the sandstone and the overlying lime- stone or dolomite of the.Amherstburg at the outcr0p and in well samples. Landes further considered the sand of the Sylvania as having accumulated.by current action like modern beach and barrier sands. R. C. Wild (1958) alSo showed the Sylvania sandstone to be marine in origin with waves and currents selectively distributing, reworking, and sorting the sand, but whose major source area was to the southeast of lower Michigan. TECTONIC FRAMEWORK OF THE MICHIGAN BASIN Regional Structures The Michigan Basin is a slightly irregular circular structural depression, regarded as the type example of an autogeosyncline (Kay, 1951) or an intracratonic basin. Its center is located near the central part of southern Michigan and contains approximately 14,000 feet of Paleo- zoic rocks overlying Precambrian igneous and metamorphic units.’ The Basin's flanks are essentially located in eastern Wisconsin, northeastern Illinois, northern Indiana, northwestern Ohio, southwestern Ontario, and northern Michigan. Several arches border the Basin including the Algonquin Arch to the northeast, the Findlay Arch to the east and southeast, the Wisconsin Arch to the west, the Kankakee Arch to the southwest, and the Cincinnati Arch to the south (Figure 2). Prior to Sylvania deposition, a sag developed in the Findlay Arch (Chatham Sag) which persisted during Sylvania time. The deepest portion of the Chatham Sag was near the Lake St. Clair region of Michigan and Ontario. To the west, in central Wisconsin, a positive feature referred to as the Wisconsin dome was uplifted following the deposition of Silurian beds in Michigan. To the north, northeast, and east are exposed Precambrian rocks of the North American Shield whose three 6 U ,,-+_‘ .—_— Iiuoul. ‘fi.~ _. —. I L... I I I '- I \ ' \ I l .. l I I ' 0‘ \\.S.© ‘ ' 0 \ 3 "\. V »-.1 o ' \ 2 "x I o \\ . \ i : l\- ‘ I ” ‘\ 3...... E . '0 ’ 3 . N, 1| ’1 ,. I \. -;/ I I. l f \ / //CII0I|I¢III 30¢ ‘ . -‘-- ‘--——-- -“.‘ ‘ EXPLANATIONS 1:...‘Mroo of pro-Muenucn «newton I Ana 0! pen-050.!" “mun" _.*_Iuior synclinol "CC. .. ' MAJOR STRUCTURAL TRENDS-MICHIGAN BASIN AND ENVIRONS . ' —-‘—-Bord¢r "I'IMCI oxls I § Progeny"? An , _ , / :2 »---FW" W" =. ,z - t . 2r; ' '5‘. Q Outflow-0M. PIloHom; . /.~. mmFoun.hchIuru on Gov-Munch m. . . “I" r '2 ’ ' F / x I FOIIIHSQ, ; ;‘ I. = . 5 I [‘3‘ % «In! an E ' I z ' I ‘. ‘ ‘ _ I - | I ; ‘ \{a'r'o'ls‘L . . -/{ ' _ P.‘ Pinconnlng Held : '0 .1. f ' " . I ; ‘ '3 I ? \‘\ I ‘I ,’ 3 : . . . -.‘ I I . :\ I .,,._ - ~: = ; . .2 . I L. I I_.___ : y . - .._ I Nod-II "or IISIIQOQ 40 no no Igo I93 I90 1 L j Kn. M} Flour. '2 provinces meet under the Michigan Basin and comprise the basement rocks (Stonehouse, 1969). Intrabasinal Structures The structure contour map (Figure 5), based on the top of the Sylvania sandstone, illustrates that the Basin has a symmetrical oval shape with a slight northwest- southeast elongation and many structural features follow this major trend. The deepest part of this pre-Mississippian Basin is in Clare, Gladwin and Midland Counties. The regional dip into the center averages 50 to 55 feet (9 to 11 meters) per mile (1.6 Kilometers) with minor structural variations. Contours show a relief of about 5000 feet (1,500 meters). The largest feature shown on the structural contour map is the Howell anticline, a northwestward plunging fold trending through Livingston and Monroe Counties of south— eastern Michigan. It is an asymmetrical anticline with the steeper dips on the southwestern flank. Structural relief on the Howell anticline is about 1000 feet (500 meters). Three minor southward trending synclines are discernible in Lapeer, Lenawee, and Barry Counties. 0 STRUCTURE CONTOUR p 0 MAP On Top of Sylvania Sea Level Datum \ S) .— _I I-_I * Q ’ I I 6, G ‘ AIIL'II‘IINO O .I‘i L.- ‘3 *I ;,I I I-+»1 _c 05 I 3AL$OIIAII ‘ ‘ fiCP‘PI "anr‘ I m: In H“I '" ”' SE .A I :Iopco \ - P I r I '_,LI LAKE (RIF J FIGURE 3. Dots represent well locations 0 I I2 Cain = 200' GENERAL STRATIGRAPHY The Sylvania, of Lower Middle Devonian age, is usually a sandstone, but beds of dolomitic or limy sandstone and sandy dolomite or limestone may be present. It occurs throughout most of lower Michigan, northern Indiana, north- western Ohio, and eastern Ontario. The Sylvania sandstone extending throughout the Southern Peninsula of Michigan generally unconformably overlies either the Bass Island rocks of Upper Silurian age, or the Bois Blanc formation of Lower Onondaga age (Figure 5). In addition, according to descriptive logs there are a few well locations in south and southwestern Michigan where the Sylvania may also overlie the Salina of Upper Silurian age, or the Garden Island of Lower Oriskany age. Erratic distribution of the Garden Island and Salina as underlying formations is probably due to differential emergent erosion rather than nondeposition. The isopach map (Figure 11) seems to indicate a low lying shelf in this area during Sylvania time. Chert is present in some wells throughout the Sylvania's vertical extent but generally is restricted to the basal beds as a representation of reworked cherty units of the underlying Bois Blanc formation. It is the presence of this basal chert that offers a more identifiable contact than exhibited by the overlying carbonate section. 10 11 The Sylvania sandstone, where present, is strati- graphically closely related to the overlying Detroit River formation and in most places grades upward into the car- bonate rocks without a sharp break as observed in the sub- surface and at the outcrop. It will typically change into a dolomitic or limy sandstone, then into arenaceous lime- stone or dolomite, than a dolomite or limestone, not as a uniformly gradual change but with alternating layers of more sandy and less sandy material in a general upward decrease of the sand content. In one area only (Hillsdale County of southern Michigan), where the Lucas formation rests conformably on the Sylvania sandstone (Landes, 1951), it is not overlain by carbonate rocks of the Amherstburg. The Sylvania sandstone crops out in quarries of Monroe and'Wayne Counties in southeastern Michigan, and Lucas County in northwestern Ohio, and represents the oldest exposed formation of the Devonian System. The out— crop area varies in.width from one to two miles at the northernmost exposure in Wayne County, to less than 200 yards at the southernmost exposure at the Maumee River in Lucas County. The sandstone beds dip toward the center of the Michigan Basin with a maximum depth of 4,400 feet below sea level occurring in Clare and Midland Counties. In the subsurface, evidence of the Sylvania sandstone can be found throughout most of lower Michigan but it pre- dominantly occupies a linear trough trending northwest— southeast with a maximum depth of at least 410 feet, 12 partially eroded during pre-Sylvania time in the under- lying Bass Island and Bois Blanc rocks. As indicated by the sand percentage map (Figure 12), this linear pattern extends from southeast Michigan into the northern half of the lower Peninsula where it terminates in Missaukee County. The sandstone thins from this area and grades laterally into the surrounding carbonates. Figure 5 shows the areal distribution of the Sylvania sandstone and its relationship to the underlying beds. Pre—Sylvania Geologic History The pertinent history of the Sylvania sandstone begins with Bass Island time. When the Bass Island sea withdrew, the area was covered with the youngest sedi- mentary rocks of the Bass Island dolomite. These late Silurian deposits were wide spread. During the period of emergence prior to the encroachment of the earliest Devonian sea there was some erosion that removed sediments of the Bass Island either completely or in part. Therefore, in isolated areas the underlying uppermost Salina Group was exposed. By the time the earliest Devonian sea Spread over the area that is now the Southern Peninsula of Michigan the topography was moderately rolling and the rocks of different ages were exhibited from place to place. The earliest Devonian sea, Oriskany, deposited the Garden ' Island formation. Emergence occurred later and erosion removed the Garden Island formation everywhere in Michigan ’13 Nomenclature of Michigan Formations Lane, Prosser, Sherzer, Classification Used in and Grabau-#1909 This Study Lucas dolomite Q Anderdon limestone mh tb E 3' FM' Upper Aaoiiiitfim g a M g (5 Lucas dolomite onroe g 8 FM. or Anderdon .3 , 3-; D etroi limestone g 3 .3 Amherstburg River a cc 9 a) 4: I dolomite a, co .3 Series '53 'g jg Sylvania IS. '3 g Sandstone c, . S Bois Blanc 5’ 0 ' Disconformity-—-—-J .3 E Mlddle Sylvania Pg ' cu . g eI Monroe . Sandstone a». 'H o I> d ”3 F" 3 fl Garden Island :4 o m a g ”a a CI EC 2: Disconformity——-q haisin River ,U . . . Lower dolomite g Raisin River M nr ,4 dolomite ° °‘ Put-in—Bay dol. a 3+ , or g g m a Put-ineBay Bass Tymochtee beds was 3‘9 dolomite I a) an Island Greenfield 5.3”) Series dolomite mg a. St. Ignace 2*, m g dolomite .Q-IE: H mm (5 Do as )3 Pt. Aux Chenes u—l shale as m FIGURE 1+. 14 except for patches on Garden Island and elsewhere on the northern flank of the Basin. in addition to those areas shown in southwestern Michigan on Figure 5. The post- Oriskany emergence and erosion interval was followed by widespread inundation by the Onondage sea. In Michigan, the Bois Blanc was deposited on the floor of this sea, covering both remnants of the Garden Island formation and the twice-eroded Bass Island Group. The withdrawal of the Onondaga sea from this area subsequently produced erosion of such magnitude that the Bois Blanc formation was completely removed from the flanks of the Kankakee and Findlay arches (Landes, 1951). The areal geology at the time of the inundation by the Sylvania age sea is shown on the pre-Sylvania geologic map (Figure 5). The limit of the Bois Blanc formation and the locations of the Bass Island, Garden Island, and Salina formations vary in position from place to place owing to pre—Sylvania structural and erosional variability. This moderately rolling subsurface thus accounts for the differential thicknesses exhibited by the Sylvania sand— stone isopach map (Figure 12). A downwarp and erosional surface along a northwest-southeast axis from central Michigan across southeastern.Michigan into northern Ohio permitted the entrance of marine waters through the Chatham Sag which marked the beginning of Sylvania time. It was during this period that the Sylvania sandstone began deposi— tion throughout most of lower Michigan. "1.688 3.: 1.... FIGURE 5. Areal Distribution of Formations Beneath the Sylvania Sandstone 0 C H ICON” a: Sylvania Sandstone found in Michigan below this line 0 Garden Island ‘ Salina LII! 8L Cllll Clllfll. LAKE (RI! METHOD OF INVESTIGATION Information for analysis was acquired by examination of well cuttings, gamma ray-neutron logs, and printed driller-geologist logs supplied by the Michigan Geological Survey. Subsurface samples from wells drilled in search of oil and gas in Michigan were of great assistance in determining the lithology, thickness, and areal extent of this Lower Middle Devonian sandstone. Well cuttings (rotary and cable tool) were obtained from the Michigan State University Department of Geology and the Michigan Geological Survey sample libraries. These samples are in trays containing phials of sediment selected from the drilled interval. Each phial consists of five to eight grams of cuttings representing from five to twenty foot drilling intervals. The samples are well washed and therefore contain few clay materials. Regional lithofacies variations were determined after examination of eighty wells that were selected throughout the State on a limiting basis of one well per section. Since most of the oil and gas produced in Michigan has been from formations above the Sylvania (excepting the Ordovician producers as from the Albion- Scipio Trend), few wells have penetrated into or through this rock unit. Because of this limiting factor the writer has found the major concentration of wells occurs in the southern half of lower Michigan, thus resulting in 16 17 somewhat poor geologic control in the North. Every available northern Sylvania sample interval was used in this investigation. Examination of well cuttings was achieved through the use of a reflected light binocular microscope with a magnification range between 7X and 40X. A Micrometer Occular was used to determine quartz grain size frequencies and the percentages of sample constituents. Where a mixed lithology, as sandy dolomite, was encountered, the per- centages of sand and dolomite for the sample interval were estimated and placed within their respective grade size categories. By totaling the percentage of each rock type from individual phials and dividing by the total number of phials for each well sampled, an average was computed for the amount of rock constituents. From this data, percentage maps showing major lithologies from the Sylvania were constructed. Quartz prOperties examined included color, grain size, shape, degree of sorting, type of cementation, and presence of frosting or pitting. For carbonate facies, semi-quantitative acid analyses (Colorado School of Mines Technique) were used for lithologic determinations. By this method samples were tested using cold hydrochloric acid, diluted with distilled water, at a water to acid ratio of 7:1. The lithology of the intervals for each well was recorded with conclusions based largely on these data. Sylvania tOps indicated in the descriptive 18 logs were previously established by the Michigan Geological Survey but were modified as deemed necessary from sample analyses. Regional isopach and structure contour maps were constructed employing about one hundred control wells from a possible one hundred thirty—five. Where drill cuttings were not available for key wells, gamma ray-neutron logs were used to supplement the sample study. In addition, tops picked by microsc0pic sample analyses were compared to those appearing on the logs to achieve greater accuracy. Gamma ray~neutron logs measure and record emanations from strata traversed. All rocks contain small but measurable amounts of gamma ray-emitting radioactive elements, and in most cases a detectable increase or decrease of radio- active intensity occurs at each formation boundary. Identification of different rock types can be made where a lithologic change occurs at the contact of two formations. Upper and lower contacts were picked in accordance with the manner adopted.by the Geologic Survey. The top of the Sylvania formation is usually picked as being higher in deflections compared to the overlying carbonate section. A black limestone marker bed, producing a distinctively large outward kick, is usually located within eighty feet above the Sylvania sandstone and may be used as a general reference to orientation of the Sylvania top. The bottom of the sandstone is usually identified by shorter deflec- tions compared to the underlying carbonate section as ’19 exhibited by cross-sections (Figures 7 and 8). Cross- sectional well locations are indicated by Figure 6. 20 L!!! 8'. CLAIR LAII’ (fill FIGURE 6. Sylvania Cross— Sectional Locations 21 mm>nso woq ham assmw .¢I¢ doapomwlmmomo onopmoawm wfinm>ahm 9‘ .. a as a an is $252 _ "I 5 ~- \. n D...’ I I~ . o ..I‘ g w...“- 'x'!‘|.§.\l.\.l\.~* “ I ~‘ “.'.‘~~‘ “..'.. ' '.5 I' H.‘ _ is .‘ :0 . d I . m. ".55me must? aflu‘ 3.1m m <. mmbHso molH 5mm wasmw .mIm soapemmnmmoao weepmeaem waeweaam .w mmseHm 8 u n , x ‘ .._ m memm rm .5 ”a... _ A I. 350 , w$ mm < mam . .. k E. was: w was N muses... W . 3.5... A «523 I muses“ 2.3a. Lima 33?. 2%. a .22 m DETAILED STRATIGRAPHIC ANALYSIS Lithology The Sylvania sandstone has several distinctive proper— ties which are present throughout its area of distribution in the Lower Peninsula of Michigan. In outcrop, the Sylvania is typically a massive, white, friable sandstone, with variable amounts of dolomitic cement (Enyert, 1949). Hatfield, Rohrbacker, and Floyd (1968) demonstrated a northwestward inclination of cross beds in northwestern Ohio and southeastern Michigan corresponding to regional dip and thickening into the Michigan Basin. Preferred orientation of the long dimensions of the grains is also in that direction. Results of subsurface analyses show that the Sylvania is commonly a clear, white or light gray pure quartz sand- stone, but may be brown, orange or yellow due to iron staining. Grains are often loosely cemented with dolomite, silica, or calcite, although they are so friable that loose grains are quite common. Samples show that the Sylvania is very well sorted, with great variation both horizontally and vertically in the maximum frequency of grain size. Although there is marked change, the average medium diameter appears to be slightly more than a quarter millimeter, but any given well may contain a range of between one—sixteenth 23 24 and one millimeter in diameter. Usually grains less than one—eighth or greater than three-fourths of a millimeter will represent 20 percent or less of the sample, with another 20 percent falling between one-eighth and one- fourth millimeter grain size. There is a slight tendency toward smaller quartz sizes downward stratigraphically. Deviations toward larger grains occur in southeastern and western Michigan where appreciable quantities of coarse sandstone (up to one millimeter) may be found (Figure 9). The Sylvania.sandstone might have all gradations from a sandstone, through dolomitic sandstone and arenaceous dolomite to dolomite; or from a sandstone, through limy sandstone and arenaceous limestone to limestone. Figure 10 shows the sandstone occurring with limestone in northern and eastern Michigan but with dolomite in western and southern Michigan. There is a general decrease upward of sand percentages. A correlation is noted between the percentage of carbonate and the size of the sand grains in some wells. Generally the higher the percentage of car- bonates the smaller the clastic grain size. This is particularly observable in northwestern Michigan, around Kalkaska County, where limestone approaches an average of 97 percent and silt grains of approximately one-fortieth of a millimeter occur (Figure 9). This is normal if it is assumed that elastic grain size percentage, and pr0portions of magnesium salts decrease away from a postulated south- eastern source. LAKE IL Cllll CAIIOI. LAKE (RI! L- FIGURE 9. Distribution of Coarse. o . a mu” . (up to 1 mm) and Silt ==== . Coarse Clastics Sized (1/20 mm-1/4O mm) Grains x Silt Clastics FIGURE 10. L..— Facies Map of the Sylvania Carbonate Fraction 0 O I! lO-flu == LAX! If. ‘Lllfl CAIIDO. [All (fill 27 Many of the sand grains show secondary enlargement with perfect crystal facets and sharp edges, giving the sand a fresh sparkling appearance. These granules received their secondary enlargement subsequent to deposition probably from percolating water carrying silica in solution. Evidence of this view is furnished by the lack of abrasion on the faces and edges of the enlarged crystals. The surfaces of the Sylvania grains without over- growth do not show the vitreous luster of quartz fragments, but under the microsc0pe, are seen to be frosted or pitted. This is a characteristic found today in desert or beach sands which have been transported by the wind and/or in dune phase at some time. Since all sand grains lacking overgrowth are frosted, this may have been a result of chemical etching by percolating waters, but the high degree of rounding and sorting of the quartz is more indicative of beach sands. Occasionally, perfectly rounded grains are to be seen, especially amongst the coarser fragments. The sand sizes of highest frequency and the smaller grade sizes have a tendency toward greater angu- larity than the coarser fragments. Angularity is mainly a result of secondary enlargement rather than from a lack of transporting distance or as a result of drilling Operations. The Sylvania is a very pure quartz sandstone con- taining only a few grains of other minerals, which are located mostly in southeastern Michigan. Heavy minerals 28 that do occur become more prominent toward the base of the formation. The persistent minerals, in decreasing order of importance, include chert, gypsum, anhydrite, pyrite, tourmaline, hornblende, epidote, zircon and limonite. Chert is present in some wells throughout the whole ver- tical section, but generally it is restricted to the basal beds. The lower units often contain a high percentage (up to 35 percent) of weathered chert probably representing the reworked cherty beds of the underlying Bois Blanc formation. In southern Michigan chert persists throughout the section as indicated by the chert percentage map (Figure 15). S. W. Alty (1932, pp. 289—300) studied the heavy mineral content in oil well samples and found that the heavy minerals seemed to decrease from southeast to northwest. Sylvania fossils exist predominantly in the grada- tional limy sandstones and arenaceous limestones of eastern lower Michigan. The fossils occurring in these transitional beds, and even those near the base of the sandstone, are the same as those in the overlying member of the Detroit River formation and are not related to the fossils of the underlying Bois Blanc and Bass Island formations (Carman, 1936). Fossils observed in this investigation include pelcypod shells, crinoid stems, bryozoans, foraminifera, ostracods, cephalopods-tentaculities, fossil corals, and brachiopods. 29 To attempt to establish typical limestone or dolomite lithologic characteristics within the Sylvania sequence would be unproductive. Individual sandstone beds cannot be traced for any distance, except in a few areas where the beds are traceable between two or three closely spaced wells (Figures 7 and 8). Even within a single vertical column (Table 1), a wide variation in limestone and dolo— mite color, crystallinity and percentage relationships with quartz is observable and it becomes difficult to identify a classic Sylvania unit. Contact Relationships The Sylvania sandstone lies stratigraphically between the Lower Middle Devonian Amherstburg formation of the Detroit River Group above, and the lower Onondaga age Bois Blanc formation or late Silurian Bass Island Group below (Figures 1 and 4). Deviations from this regional pattern occur in southwestern Michigan where thin units of the Sylvania are overlain by the Lucas formation of the Detroit River evaporite section and in a few isolated locations where the sandstone may overlie the early Devonian Garden Island formation or late Silurian Salina Group (Figure 5). The sandstone is generally conformable with the overlying carbonate or evaporite sequence, but unconformably overlies either the Bass Island or Bois Blanc carbonates. Where the Sylvania is absent along the northern flank of the Michigan Basin, the Bois Blanc is overlain by the Amherstburg. BO TABLE 1 Sylvania Sandstone Lithologic Column Unit T4N-R8E-22 Permit No. 15072 Detroit River-Amherstburg Dolomite, calcitic, brown to gray, sucrosic, medium grained, 90 percent; limestone, dark to light brown, aphanitic, fine grained, soft, 10 percent; trace of sandstone, frosted, sub- rounded, 1/2 mm. 5480-5498 Upper Contact—Sylvania Dolomite, calcitic, dark brown to brown, medium grained, 85 percent; limestone, white, aphanitic, fine grained, 8 percent; sandstone, white, frosted, subrounded to well rounded, fairly well sorted, 1/2 mm - 1/4 mm, mostly 1/4 mm, 7 percent, a few aggregates contain dolomite cement, a few grains approach spheri- city; trace chert, white, porcelain; trace gypsum, white, soft. 5499-3550 Dolomite, calcitic, light brown to gray, medium sucrosic, 60 percent; limestone, gray to white, fine sucrosic, fine grained, 15 per— cent; sandstone, white, frosted, well rounded, well sorted, 1/8 mm - 5/4 mm, mostly 1/4 mm, 23 percent; chert, white, porcelain, 5 percent. 3550-3590 Limestone, dolomitic, light gray to brown, sucrosic, 55 percent; dolomite, calcitic, tan to gray, finely crystalline, fine grained, 15 percent; sandstone, grayish white, clear, subangular due to secondary enlargement, poorly sorted, most 1/4 mm, 28 percent; chert, white, weathered, traces of pyrite inclusions, 2 percent. 3590-5630 51 TABLE 1 (Continued) Unit Defifh Limestone, dolomitic, brown to white, medium sucrosic, 100 percent; trace chert, white; fossil crinoid stems, bryozoans, brachiopod fragments. 5650-5660 Limestone, dolomitic, brown to white, medium sucrosic, fine grained, 50 percent; sandstone, clear, subrounded to subangular, secondary enlargement, moderate sorting, mostly 1/2 mm, 50 percent; trace chert. 5660—5690 Sandstone, clear, subrounded to subangular, moderate sorting, 1/4 - 1/2 mm, mostly 1/4 mm, 99 percent; limestone, dolomitic, brown to white, sucrosic, 1 percent; trace chert, white. 3690-3770 Limestone, dolomitic, gray to light brown, fine sucrosic, 44 percent; dolomite, cal- citic, tan to gray, dense, 52 percent; sandstone, white, frosted, moderately sorted, well rounded, 1/4 mm - 1 mm, mostly 1/2 mm, 20 percent; chert, milky white, porcelain to weathered, a few dolomite rhom inclusions, 4 percent; trace shale. 3770-5795 Bois Blane—Contact Dolomite, calcitic, light brown to light gray, very finely crystalline, some pore filling gypsum crystals, 50 percent; lime- stone, dolomitic, light gray, medium sucrosic, 6 percent; chert, white, all weathered, dolomite rhom inclusions, 44 per— cent; trace pyrite. 3795-5810 52 One of the chief problems in the Sylvania section is its relationship with the Detroit River sequence. The contact of the Sylvania sandstone with the overlying dolomite and limestone is difficult to determine, because few lithologic changes and some sandy beds are present in the basal part of the overlying carbonate rocks. Because the Contact is gradational, the carbonate rocks are con- sidered to be conformable with the Sylvania and, therefore, the Sylvania is included in the carbonate sequence of the Detroit River Group. The basal Amherstburg is primarily composed of lime- stone with lesser amounts of dolomite in the northern and eastern parts of the Southern Peninsula of Michigan. It becomes a dolomite in the western and southern parts of the lower peninsula with the exception of the southwestern corner where the Detroit River evaporite section directly overlies the Sylvania. The characteristic feature of the basal Amherstburg carbonate rocks is a relatively darker color in contrast to the somewhat lighter colored under- lying arenaceous Sylvania carbonates. Many geologists have referred to the Amherstburg as the "Black Lime" because of its dark color. This peppered dark brown appearance was only observed in the basal units of the northern lower peninsula. Upper contacts were chosen on the basis of slight color changes and significant dif— ferences in quartz percentages with the exception of southwestern Michigan where the light colored dolomites 53 offered little lithologic color change. In northern and northwestern Michigan the uppermost Sylvania sandstone is typically a light brown to brown, dense, arenaceous lime- stone that grades into the overlying peppered dark brown, finely sucrosic limestone of the Amherstburg. In eastern Michigan the upper Sylvania is represented by a very arenaceous limestone that is often dark gray or brown to buff, dense, and may contain a trace of chert. This normally grades upward into a slightly arenaceous lime— stone that becomes dark brown to brown, aphanitic, with an absence of chert. Chert is rarely present in the basal beds of the Detroit River carbonate section. The upper contact in central and southeastern Michigan shows two types of lithologic breaks. There may be a sharp break from a pure white sandstone unit into a calcitic dolomite which is brown to buff and microcrystalline. Secondly, there is a gradational change from a gray to buff, micro- crystalline, arenaceous calcitic dolomite into a dark gray to brown, dense, calcitic dolomite. Definite, easily recognizable lithologic breaks between the Sylvania and overlying Amherstburg only occur in the high sandstone percentage zones of central and southeastern Michigan. Southern Michigan shows a gradual change from a light gray to white, dense, dolomite into a buff to medium-brown dolomite. ~Because quartz grains are of small quantity in southwestern and western Michigan, in addition to carbonate units showing no lithologic differences, upper contacts 34 are based upon a total absence of sand in the overlying Detroit River carbonate section to the west or evaporite sequence in the southwest. In southwestern Michigan, a green sandy shale with interbedded gray dolomite represents a facies of the Sylvania and in the western area it is typically a brown to buff, dense, arenaceous dolomite. At or near the top of the Detroit River carbonate sequence is a black limestone or dolomite. The black limestone has proved to be a reliable marker bed when tracing the Sylvania sandstone from gamma ray—neutron logs. According to Landes (1945, p. 68) this marker bed is present throughout Michigan. The top of the "black limestone" is 200 to 500 feet above the base of the Detroit River carbonate section in eastern and northern Michigan, and 20 to 100 feet above the base in western and southern Michigan. In wells where the contact between the Sylvania and the overlying carbonate bed cannot be readily determined, the "black limestone" serves as a marker on gamma ray- neutron logs from which the contact can be roughly estimated. The lower contact of the Sylvania is easily determined when the cherty section of the underlying Bois Blanc is present. The Sylvania basal beds often contain white weathered chert representing the reworked cherty units of the underlying formation. Bois Blanc subsurface samples show a substantial increase in the presence of chert com- pared to the overlying sandstone units. The upper five feet of the Bois Blanc is typically a gray sandy cherty 55 dolomite. The sand residue is usually poorly sorted and often subangular to angular in all size fractions. In western Michigan, the underlying brown, buff and gray dolomites are called Bois Blanc if chert is present, or Bass Island if the carbonate is not cherty. Bois Blanc and Bass Island carbonates, therefore, are differentiated on the basis of chert content. The locations where Garden Island or Salina are subjacent to the Sylvania were taken from the Michigan Geological Survey descriptive logs, and occur in small isolated patches to the south and southwest of the Basin. The feather edge of the Bois Blane formation varies widely along its border due to local variations in the depth of erosion (Figure 5). In these areas where the Sylvania sequence overlies Bass Island, Garden Island or Salina rocks, the contact between the two is difficult to distinguish in the subsurface since color changes are rare. The break was chosen as the point where the sandstone became absent below the Sylvania beds. Distribution and Thickness The Sylvania sandstone appears to be restricted to an area north and west of the Findlay Arch. On the basis of the isopach map (Figure 11) it can be seen that the sand- stone thins southward in southeastern Michigan and the zero thickness location does not extend far into northern Ohio, indicating that the Findlay Arch probably formed the southern shore of the Sylvania age sea. In the subsurface, 56 the Sylvania sandstone is found throughout most of the Southern Peninsula of Michigan with the exception of the extreme northern and northeastern regions. The sandstone is also found in northern Indiana, northwestern Ohio and eastern Ontario, with outcrops occurring in southeastern Michigan and northwestern Ohio. The outcrop area varies in width from one to two miles at the northernmost ex- posure in Wayne County, Michigan, to less than 200 yards at the southernmost exposure at the Maumee River, Lucas County, Ohio. The Sylvania sandstone dips toward the center of the Michigan Basin from the outcrops at an average rate of 50 to 55 feet (9 to 10 meters) per mile (1.6 Kilometers) and in Clare, Midland, and Gladwin Counties the structure contour map (Figure 5) shows a depth of about 4,400 feet (1,520 meters) below sea level and a structural relief of approximately 5,000 feet (1,500 meters). The isopach map shows a shallow.linear trough lying in a northwest—southeast axis extending from northwestern through southeastern Michigan toward northern Ohio. Most of the Sylvania sandstone accumulated in this "trough." Thickness lines indicate that very little of the sand- stone has been eroded in the outcrop area. Within this large linear basin the isopach map (Figure 11) shows maximum thicknesses occurring in Sanilac County to the east, Clare County in the central area, and Livingston County to the southeast. Each of these counties represents 377 ISOPACH MAP II I | I firth I I l ginngc ‘— OQI? _@HI . I._” B “IRIHIRFII '4- -1 I—I- ' ~. ill-9'41”. . . I ; ; i I _‘_..._.T.T_. ”I“T6I§§F‘jsv‘ "I’I‘1I"°”II .- I I I ~. I II I “rm “Ti FIGURE 11. Dots Represent Well Locations 0 s n ICOH“ 22:: between 58 I a thickness of 410, 528*, and 556 feet, respectively, reflecting greater subsidence along the "trough" into the Bois Blanc. Apparently, in post Bois Blanc time there was a northwestward trending basinal subsidence allowing an epicontinental sea to enter and deposit the sandstone. This is compatible with Cohee and Landes (1958, p. 490) who point out that one of the principal times of down~ warping in the Michigan Basin took place during Sylvania time with incipient folding occurring intermittently throughout the Paleozoic. Gardner (1974) points out that his Sylvania isopach shows parallelism to the Bouguer gravity and magnetic anomaly maps of Kinze and Merritt (1969) suggesting a pre-existing basement control of sedimentation. If this were the case the Sylvania "trough" would be a delayed isostatic sinking due to the added mass of Keweenawan mafic rocks incorporated into the basement complex during pre- Cambrian time. Depocenters of most pre-Mississippian isopach maps also show a general northwest-southeast orientation; however, they are offset eastward toward the Saginaw Bay area. This would indicate a very indirect effect to the Mid Michigan high, but along with sediment loading by sandstone deposition it cannot be excluded as a plausible explanation for downwarp movement of the Sylvania "trough." To the north and east of the sandstone depocenter, the Sylvania thins rapidly from 500 to 400 feet to zero in 39 Charlevoix, Ogemaw and Huron Counties. The southern thick— ness is more gradual as thinning continues into northwestern Ohio. To the west the sandstone decreases to 50 feet in Clinton County and continues in a thickening and thinning pattern throughout all of western and southwestern Michigan. Within this area are several isopach highs and an isopach low, generally trending in northwest to southeast and north- east to southwest directions. Structural patterns in the Michigan Basin often show these alignments denoting possible zones of weakness in the basement along which folding or sinking has taken place. Therefore, isopach thicknesses are mainly a result of partial subsidence with perhaps prior erosion occurring on the pre-Sylvania surface, and thins appear to have been structurally controlled by sub- surface folding. The isopach would imply that the trough has a relief of 500 feet throughout its northwest-southeast lineation with a central diameter of approximately 55 miles broadening to over 70 miles to the northwest and southeast. The south— eastern area develops a tributary-type pattern with ex— tensions to the east and south. Such an outline might be attributed to entrenchment of the subsiding trough by the encroaching Sylvania age sea. Since the southeastern tributary extension occurs over the present day Howell Anticline, this would imply the absence of that structure, and activity shaping its develOpment must have been in post-Sylvania time. Kilbourne (1947), in his study on the 4O origin and history of the Howell Anticline, pointed out there had been a local trough in this area throughout the early and middle Paleozoic. He further assumes sediments collected in this trough until the beginning of Goldwater time as all formations thin out in a southwesterly direction, as the isopachs imply. The lithologic cross sections (Figures 7 and 8) show that although upper and lower contacts of the Sylvania sandstone can be located throughout the lateral extent of the Michigan subsurface, individual sandstone lenes are not easily traceable and do not extend laterally for any appreciable distance except between closely spaced wells. Mineral Variation Maps Facies changes represent lateral variations in a rock unit. One of the most effective ways of portraying variation is by the use of percentage maps. subsurface sample analy- sis indicates that there is a close relationship between the carbonate and quartz grain content (Figures 12 and 15). The percentage maps are identical in pattern, but directly opposite in numerical values, implying an inverse relation— ship throughout the sylvania areal extent. The most notice- able feature is the gradual decrease of quartz and increase of carbonate northwestward, with changes more quickly in all other directions. The clastic percentage map also shows considerable parallelism with the isopach map (Figure 11). Where the LAX! If. CLAIR LAX! (RI! FIGURE 12. Sandstone Percentage o o u mum Map 10 percent Interval LARI 3L CLAIR CAIIDA. LARI (RI! 1. FIGURE 15. Carbonate Percentage °==.=' " """" Map '10 percent Interval 43 unit is thicker, higher percentages of sand are found. Departure from this general relationship is observed only in southeastern Michigan where sand percentages are greater with decreasing thicknesses, inferring the proximity of a sedimentary source to the southeast. The carbonate per— centage map shows that carbonate content decreases where the formation is thicker and with an increase in sand content. At various times, the carbonates were deposited simultaneously with the Sylvania sands under marine conditions. The most fundamental lithologic indicator is the clastic ratio, which is obtained by dividing all clastics by non-clastics within the desired well interval. Since sandstone and carbonates dominate the vertical extent of the Sylvania unit, these rocks would be expected to pro— duce a clastic ratio map (Figure 14) similar in outline to the percentage maps of each. The ratio map shows that clastics are concentrated in southeastern Michigan and decrease quite rapidly in all directions except northwestward. The chert percentage map (Figure 15) reveals a general decrease of chert in all directions away from the highest values recorded in Ingham, Eaton and Jackson Counties. Only traces of chert are found elsewhere in Michigan. Landes (1951) concluded that most of the chert in the Sylvania was probably derived from the underlying cherty Bois Blanc formation. The high chert concentration does not coincide 44 with underlying areas of maximum Bois Blanc erosion (Figure 5). However, residual chert from the southwest and west where the Bois Blanc was completely removed as an underlying formation may have been carried eastward by stream and/or wind activity and incorporated into the Sylvania stratigraphic units. In addition, there may have been secondary silicious processes operating in chert pro- duction as would be indicated by the presence of quartz secondary enlargement. In view of the fact that most of the chert was of a weathered milky white appearance it would more likely be residual in nature. Chert concentra— tions also occur in an area of high carbonate percentage (Figure 15) with a similar distribution pattern, as well as an area relatively near the Sylvania Shore. In the evaporite percentage analysis (Figure 16), wells investigated show relatively high evaporite values (greater than 2 percent) located to the east and southwest. This would seem to indicate these near-margin areas were sufficiently restricted to prove favorable for evaporite deposition. Jodry (1954) noted lagoonal conditions around the southwest Michigan area in the Traverse Group. He suggested lagoonal control based on the coincidence of the "West Michigan barrier" and the high regional gravity map of the area after Logue (1954). Runyon (1976) and Newhart (1976) produced dolomite percentage maps showing increases of magnesium toward the west from the postulated barrier during Traverse and Ordovician times, respectively. This LAR! 3'. CLRIR LAX! (RI! L. L... ' ' M ‘l=:—_—".='."'"” Ra io Interval 0.5 FIGURE 14. Clastic Ratio ap up to 305 Above 5.5 Interval is 20 . W I C 4 g I Q !-- ‘. LAN! J'.¢LRIR GAIL... LAR! (RI! I 0 __,I_. l..— 1. FIGURE 15. Chert Percentage 0:0 mgr-um Map -5 percent Interval . D *. V i u l . I -*-d——-b- Greater than 2 percent _. 8‘ LAKI 37.CLAIR '7: o «1“» U th z CAIIDA. “1.. 1.4!! (RI! .+~ FIGURE 16. Evaporite Percentage Map 0 0 I1 ICIWN c=:=::= 48 would seem to indicate the presence of the Wisconsin Arch during Sylvania time which added to the restrictive envi— ronment in southwestern Michigan. The area to the east is not easily explainable and because of a strong probability that rotary wells provided contamination from the over- lying Detroit River evaporite section (Figures 1 and 4) and because the percentages involved are much smaller, the writer is reluctant to draw conclusions. Because of rotary well contamination a shale percen— tage map would not have been reliable (shale percentages were under 4 percent) and, therefore, has been excluded from this investigation. But, Wild (1958) found the largest percentages of shale occurring in Ingham County, a general area of nearly maximum carbonate content (Figure 13). ENVIRONMENTAL INTERPRETATION Origin of Sediments The origin of the Lower Middle Devonian Sylvania sand- stone presents a problem which may be explored by an investigation of the sedimentary and lithologic character- istics, the areal distribution and thickness and the paleogeography at the time of deposition. From the writer's data it is apparent that the Sylvania may have been deposited in a near shore shallow carbonate producing marine environ— ment migrating northwestward from the Chatham Sag and southeastern Michigan. Indications for a southeastern source are exhibited by the following: (1) seven wells located in eastern and southeastern Michigan contain appreciable quantities of coarse quartz grains (up to 1 mm) within some units of the Sylvania sequence (Figure 9), indicating a closeness to source since large size grains do not occur elsewhere in Michigan, with the exception of wells located to the extreme northwest and west; (2) three wells located in and near Kalkaska County contain only silt size quartz (1/40 mm) exhibiting a lateral gradation of large to finer grains from southeast to northwest and away from the westerly source area; (3) the clastic ratio map (Figure 14) shows the highest clastic concentration occurring in southeastern 49 50 Michigan, which would be expected since more clastic material tends to be deposited closer to source; and (4) heavy mineral content decreases from the southeast toward the center of Michigan. This evidence is supported by Hatfield's (1969) observations regarding crossbedding with a northwestward inclination in the Sylvania in northwestern Ohio and southeastern Michigan, with preferred orientation of the long dimensions of grains also in that direction. Some of the Sylvania sand may also have been trans- ported bv prevailing westerly winds and/or running water from a northwestern or western direction as indicated by the following evidence: (1) there are five wells located in western and northwestern Michigan which contain coarse quartz grains (up to 1 mm) indicating a closeness to source (Figure 9); and (2) these coarse grains are better rounded and sorted than those located in eastern and south- eastern Michigan which might be resultant of a more per- sistent abrasion in beach phase but could conceivably imply reworking of older sandstone exposed in the Wisconsin Highland region. Paleogeographic maps suggest an arid climate in the area during Lower Devonian time so prevailing Westerlies and/or streams could easily have picked up this sand and redeposited it in the Michigan Basin. There exist two possibilities as to the origin of these southeastern derived sediments. First, Chung (1973) in his study on the Goldwater Formation and Asseez (1969) in his analysis of the Bedford-Berea sequence indicate the 51 presence of a rising eastern landmass during those periods. Chung (1973) created a paleogeographic map which depicts this as a low lying peninsula in the Findlay Arch area. In addition, in comparing isopach maps of the Bois Blanc and Sylvania formations produced by Brigham (1971) it can be seen that the zero thickness line closes in toward southeastern Michigan from western Ontario during Sylvania time. This would imply the existence of this low lying emergent area during Sylvania deposition. Second, the Canadian Shield to the northeast was exposed during Sylvania time and may have contributed sediments brought down by fluvial processes or beach transport along the Algonquin Arch. Sedimentary and Geologic History The pertinent sedimentary and geologic history of the Sylvania sandstone begins with the withdrawal of the Bois Blanc sea from the Michigan Basin. During the regression erosion completely removed the Bois Blanc formation from southwestern Michigan as well as from the flanks of the Kankakee and Findlay Arches. Closing this interval, sub- sidence of a northwest-southeast trending Sylvania "trough" occurred on the eroded Bois Blanc surface permitting en— trance of marine waters through the Chatham Sag of the Findlay.Arch. Sylvania sandstone deposition began through- out most of lower Michigan sometimesconcurrently with carbonates. The sand may have been carried to the 52 encroaching Sylvania sea by three delivery systems: (1) quartz grains mav have been brought down from the eroding Canadian Shield area to the northeast by a fluvial or beach current transport system paralleling the Algonquin Arch; (2) the grains may have been eroded off a postulated low lying peripheral landmass surrounding the Findlay Arch area; and (3) wind and/or stream activity from the Wisconsin Highlands to the northwest may have carried sand from older eroding exposed sandstone into the Basin. Typical characteristics of the sand grains are their exceptionally well rounded appearance, the uniformity of size, and extreme purity, the frosting and the high degree of sorting. These attributes all point to a long continued wind and wave abrasion probably in a shallow coastal environment. These qualities were developed in a beach phase while being transported downward along the Algonquin Arch and/or were created by the northwestward trending currents carrying sands into a persistently transgressive shore line zone where waves and possibly wind actively reworked and redeposited the sediments. With further transgression of the Sylvania sea came additional carbonate accumulations (Figure 10). The Wisconsin, Kankakee and Findlay Arches and the "West Michigan Barrier" probably restricted the shallow marine environment in the western and southern areas of Michigan for dolomite deposition to predominate in the arid climate postulated. To the north and.northeast a deeper sea and 53 lower salinity environment produced fossiliferous limestone deposition. The zero thickness line located to the north- east on the iSOpach map (Figure 11) either indicates the Sylvania shoreline was here during this period or was further back and the limestone subsequently eroded. The zero thickness to the south would be indicative of the transgressing sea being limited southward by the Findlay Arch. Following Sylvania sandstone deposition, the Basin probably subsided allowing the sea to transgress farther leaving a thick carbonate layer of the (Amherstberg) Detroit River Group. As the carbonate depositing marine waters spread over the Michigan Basin, the upper Sylvania sands were reworked and in most cases incorporated into the basal units of the overlying limestone and dolomite, resulting in a gradational upper Sylvania contact. The contact relations between the Sylvania sands and fossili- ferous Amherstburg carbonates above and to Bois Blanc cherty carbonates below may be readily seen on the litholo— gic cross—section$(Figures 7 and 8). These provide an excellent example of the obvious predominate marine deposi- tional environment of the sandstone and demonstrate inter— bedding with limestone and dolomite. ECONOMIC CONSIDERATIONS The purity of the Sylvania and superiority as glass sand has been recognized since the early reports of Houghton (1858, p. 7). It is the only glass sand produced from quarries in Michigan. Because of its extreme purity, averaging only 0.015 percent iron oxide, all sand used by the U.S. Government for optical purposes during the first World War (Martin, 1920, p. 172) was from Michigan. The Sylvania sandstone has also been discussed by Sherzer (1911, p. 256) as a source of water in and adjacent to the out- crop area in southeastern Wayne and northern Monroe Counties, Michigan. The oil and gas fields presently discovered and produced commercially from the Detroit River Group are anti- clinal accumulations within dolomites of the Lucas formation. The Sylvania sandstone member has yielded good showings of oil in several wells (Landes, 1945) but no production as yet. However, most wells penetrating the Sylvania sand- stone have been off structure within the central area of the Basin. It would be reasonable to assume that many new fields in the Detroit River Group will be discovered by exploring the Detroit River sequence of rock from top to bottom, including the basal Sylvania sandstone, on anticlines, stratigraphic traps, due to porosity pinch outs in the dolomite zone, and also due to sand lenticu~ larity are additional possibilities. 54 SUMMARY AND CONCLUSIONS The Sylvania rests disconformably upon the eroded surface of the Bass Island and Bois Blanc formations. It is concluded that there may have been three source areas for the Sylvania sandstone: first, the exposed Canadian Shield area to the northeast could have con— tributed sediments brought down into the Chatham Sag area by fluvial processes or beach transpost along the Algonquin Arch; second, erosion of a postulated low lying peripheral landmass around the Findlay Arch area may have deposited material into the encroaching sea; third, there is some minor evidence that the St. Peter sandstone from the Wisconsin Highland region to the northwest was carried into Michigan by prevailing westerlies and/or streams. The lithologic percentage maps, clastic ratio map, isopach map and distribution of coarse and silt size grains map can be interpreted as evidence that sand carrying encroaching marine waters were coming into Michigan from the southeast. Northwestward trending currents of these transgressive marine waters, which came through the Chatham Sag of the Findlay Arch, were an influential force governing 56 the distribution and deposition of the Sylvania sand- stone in Michigan. The marine phase probably resulted in transportation to a shallow coastal environment along the Sylvania Shoreline where wind, wave and current activity reworked, redistributed and continuously redeposited the sandstone, predominately along with carbonates of the sea. Most of the Sylvania sandstone was deposited in a southeast~northwest trending trough with sand percen- tage decreasing and carbonate percentage increasing in all directions away from this linear depression except southeastward. The water~laid phase of the Sylvania grades conformably into the overlying Detroit River carbonates, which in this region is of Amherstburg age. B IBLIOGRAPHY BIBLIOGRAPHY Alty, S. W., 1932, Report of an Investigation of Sylvania Rocks in Oil Wells of the Michigan Basin: Papers of the Michigan Academy of Science, Arts, and Letters, Vol. 18, pp. 289-300. Asseey, L. 0., 1969, Paleogeography of Lower Mississippian Rocks of the Michigan Basin: Am. Assoc. Petro. Geologist Bull., Vol. 53, pp. 127-135. Blatt, H., Middleton, G., and Murray, R., 1972, Origin of Sedimentary Rocks: Englewood Cliffs, New Jersey, Prentice Hall. Bottoms, K. P., 1959, A Study of the Middle Devonian Strata Based on a Well Core from Grosse Ile, Michigan: Unpublished Master's Thesis, University of Michigan. Briggs, L. I., 1959, Physical Stratigraphy of Lower Middle Devonian Rocks in the Michigan Basin: Michigan Basin, Geological Society Guidebook, Ann Arbor Geological Excursion, 1959. Brigham, R. J., 1971, Structural Geology of Southwestern Ontario and Southeastern Michigan: Ontario Bureau of Mines and Northern Affairs, Petroleum Resources Section, Paper 71-2. Carman, J. E., 1927, The Monroe Division of Rocks in Ohio: Jour. Geology, Vol. 35, No. 6, pp. 481-506. , 1936, Sylvania Sandstone of Northwestern Ohio: Geol. Soc. Amer. Bull., Vol. 47, pp. 253-265. Chung, P. K., 1973, Mississippian Goldwater Formation of the Michigan Basin: Unpublished Doctoral Disser- tation, Michigan State University. Cohee, G. V., 1965, Geological History of the Michigan Basin: Journal of the Washington Academy of Sciences, Vol. 55, 1965. Cooper, G. A., 1942, Correlation of the Devonian Sedementary Formations of North America: Geol. Soc. Amer. Bull., Vol. 55, pp. 4729-1794. 57 58 Dorr, J. A., and Eschman, D. F., 1971, Geology of Michigan: The University of Michigan Press, Ann Arbor, pp. 113- 120. Ehlers, G. M., 1950, Revised Classification of the Middle Devonian Detroit River Group, Geol. Soc. Amer. Bull., Vol. 61, No. 12, Pt. 2, pp. 1455—1456. , 1951, Devonian Rocks of Southeastern Michigan and Northwestern Ohio: Geol. Soc. Amer. Bull., 1951. Ehman, D. A., 1964, Stratigraphic Analysis of the Detroit River Group in the Michigan Basin: Unpublished Master's Thesis, University of Michigan. Ells, G. D., 1969, Architecture of the Michigan Basin: Mich. Basin Geol. Soc. Annual Field Excursion, pp- 89—95- Enyert, R. L., 1949, Middle Devonian Sandstones of the Michigan Basin: Unpublished Doctoral Thesis, University of Michigan. Fisher, J. H., 1969, Early Paleozoic History of the Michigan Basin: Mich. Basin Geol. Soc. Annual Field Excur- sion, pp. 89-93. Friedman, G. M., 1961, Distinction Between Dune, Beach, and River Sands from their Textural Characteristic: Jour. Sed. Petrol., Vol. 31, pp. 514-529. Gardner, W. C., 1974, Middle Devonian Stratigraphy and Depositional Environments in the Michigan Basin: (Special Papers) Mich. Basin Geol. Soc. Grabau, A. W., 1909, A Revised Classification of the North American Lower Paleozoic: Science, N.S., Vol. 29, pp- 551-556. , and Sherzer, W. H., 1909, The Monroe Formation of Southern Michigan and Adjoining Regions: Mich. Geol. and Biol. Survey, Publ. 2, Geol. Ser. 1, pp. 61-86. Grieve, R. O., 1951, A Subsurface Study of the Detroit River Group in Southwestern Ontario: Unpublished Master's Thesis, University of Michigan. Jodry, R. L., 1957, Reflection of Possible Deep Structures by Traverse Group Facies Changes in Western Michigan: Am. Assoc. of Petroleum Geologists Bull., Vol. 41, pp. 2677—2694. 59 Kilbourne, D. C., 1947, The Origin and DevelOpment of the Howell Anticline in Michigan: Unpublished Master's Thesis, Michigan State University. Krumbein, W. C., 1948, Lithofacies Maps and Regional Sedimentary Stratigraphic Analysis: Amer. Assoc. Petrol. Geologists Bull., Vol. 32, pp. 1909-1923. , and Sloss, G. F., 1951, Stratigraphy and Sedi- mentation: W. H. Freeman and Company, San Francisco. Landes, K. K., 1951, Detroit River Group in the Michigan Basin: U.S. Geol. Survey Circular 133. LeRoy, L. W., 1951, subsurface Geologic Methods: Colorado School of Mines (A Symposium), Golden, Colorado. Lockett, J. R., 1947, Development of Structures in Basin Areas in Northeastern United States: Amer. Assoc. Petroleum Geologists Bull., Vol. 31, pp. 429—446. Lusk, L. D., 1958, Genesis of Chert in the Middle Devonian Bois Blanc Formation of Michigan and Southwest Ontario: Unpublished Master's Thesis, University of Michigan. Majedi, M., 1969, Subsurface Study of the Detroit River Group of Southeast Michigan: Unpublished Master's Thesis, Michigan State University. McCammon, R. B., 1956, Stratigraphy and Paleontology of a Core Penetration Upper Silurian and Middle Devonian Strata in Wayne County, Michigan: Unpublished Master's Thesis, University of Michigan. Newcombe, R. B., 1933, Oil and Cass Fields of Michigan: Michigan Geol. Survey Pub. 38, G. Ser. 32. Orton, E., 1888, The Geology of Ohio Considered in its Relation to Petroleum and Natural Gas: Ohio Geol. Survey, Vol. 6, pp. 1-59. Prouty, C. E., 1972, Michigan Basin Development and the Appalachian Foreland: (abst.), International Geological Congress, 24th. Annual Session, Montreal, Canada, Aug. 1972. , 1976, Oral Communication. Runyon, S. L., 1976, A Stratigraphic Analysis of the Traverse Group of Michigan: Unpublished Master's Thesis, Michigan State University. 6O Sherzer, W. H., and Grabau, A. W., 1906, The Sylvania Sandstone, its Distribution, Nature and Origin: Michigan Geol. Survey Pub. 2, Chapter 3, pp. 61-86. , 1910, Criteria for the Recognition of the Various Types of Sand Grains (and Origin of the Sylvania Sandstone): Geol. Soc. Amer. Bull., Vol. 21, pp. 625—662. Taylor, D. W., 1951, Stratigraphy and Fauna of the Detroit River Group: Unpublished Master's Thesis, Univer- sity of Michigan. Tharp, Marie, 1944, Subsurface Studies of the Detroit River Series: Unpublished Master's Thesis, University of Michigan. Twenhofel, W. H., 1945, The Rounding of Sand Grains: Jour. Sed. Petrology, Vol. 15, No. 2, pp. 59—72. Wild, R. C., 1958, Sedimentary Analysis of the Middle Devonian Sandstone in the Michigan Basin: Unpub- lished Master's Thesis, Michigan State University. ADDENDUM Hatfield, C. B., 1968, Directional Properties, Paleoslope, and Source of the Sylvania Sandstone (Middle Devonian) of Southeastern Michigan and Northwestern Ohio: Jour. Sed. Petrology, Vol. 38, pp 224—228. APPENDICES APPENDIX A 61 obmi mwdd rmm UGwHUflZ mmrom Wm l2#vlwr warm mmms mew cusses: soon mmuzsru m comm msmm omm mammoo omm zmvuZmrumm .. nu mmu nonsm mmrmv Mmruvaumm onmm comm msm ws88 ommrr :mruZGVumm 60mm soon sum MWs88 smrmv zmruZoruor +osmm mrmm wmm mano scam as uZurum 0mm: mmms mmvr mHomomo mommr soVuZmrumm cows 3mm: ems owqmas mesa Mm Izmrumm nu. omsm mmm exam omvm 3svuzom-rv +mmmm ommm more onwao comm 3m uZom-m mmmm mmmm mes oopmaamz mmwmm awr-zrm:m menm mmmm emu mopmaawz smmmm 3mr-2mm-m ommm mmmm mms ompmasm: nvsmm sar:2mmnom 0mm: was: ommv snomzmno Orrmm gs -me-em .. u- mmev wsoomo marmm Mm :me-om noon mmmm were msmwsamm mommm 35 -zmm-mm mmod mmmm ermr mammsawm mmmmm 3m :zwmnr mmnm mmmm name owmmpo roemm 3m -Zomnmm ll . I... MrN—x wGOHQ< wémwm Mm IZmVNImV mmmm moan ammv omompo mummm 3m -zOm-mr II II mrvr Ewnpfi¢ mmmwm 3m Ival#r .. -u mmo mcmnsa roomm mm -zmm-mr acme moss rmm mHmH asumonm mmowm mm -meumm come Once omm mHmH oswmmnm mqoz Mm -zsmum mfism> % wflsm>ahm pooh . mo BOMPwm mo mos dompm>mwm hpsdoo oz pasnom soapmoon .HobmH mom m>opm pmmm com: commp maOHpm>mHm .mmms nommomfl was Adopsoo HmRSpodspm mo soaposnpmsoo How vows mpmc HHmB .m mnmae 4 Nanmmm¢ 62 mmcm mcmm cscm mmsm msmm ommm moms crow comm comm some worm comm ccnm mmsm some mmrm smsm ccom came cscm rmcm cmmm ccsm scam csmm mccm cmcm +m¢m¢ mmcm mmmc sues mfiaw>amm mo aoppom mmmm cmmm msom cram smmm cmmm more mace mcmm mmmm mace nmcm mmem scam cmmm came emcm ccmm ccmm come mccm mmmm come comm amcm mmcm cmcm cmcm cos: moan cams mmo: madm>awm mo 909 com cam. 3cm can mus 6cm com mum cmc mes cmc cum smcv sccv mac can mew vac mew cmc mmn son was cmm mom mmm mos awn ans can mmu crce cmc 3...? downw>mam dopmmnflbfla amnde awnwsH nmwoaa< hnnmm sopmm 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cccmoc .pm mmmu zernmc umv some case more cchmHHsm ocvrm 3r umc umv ccm cor emc mango: mmcm mm umc ucr came mcmr mom cczcacg cccm Mm umc -cm mmmv mmmr can mmcc mcmm 3mrnmm um came cemv mum sccmoc .pm mammm so umm use mccv came cmcr scamnm mmmcm 3m umm umm mmmr acme vmcr cmwcmaaam mrcrm 3m umm ucc mace cmc can cozmncq urmmm Mm umm use meme emse vac acccamc cmsmm 36 um: urm accm cmcm mace somscws ucmcr 3e um: umr mum cmr 5mm cuss: svmmr mm ums ucm mmmv come cmm smacpcmmz sauce ms um: umm mrrm cccm cccv acmscmc cccmm we um: use muse move mmu scannmm mcmcm 3mvumm ucm meme mmmv com nsocawc vsmcm 3m umm umm ccm cm: mmc cuss: sumac scrumm In rcmr some mcc ccncm cm> swam 3cv-mm umm mcmm msmm mac csocamc cmmmm 3m -mm umr scam mmam cmcr acmsomc mcmrm 3m -mm -mr mom crc mmc mass: mrmm Mm 1mm .mm mcmr cmcr mew swampcmmz vcmce ms :mm :mm mode race one ccssm aw> mmxc zmrcmv cox cvmm cmcm mmo acccamc cmsmm 3m smr cc mcmv mmsr uccr smacpnmms msmcr Mn :mr sn same some mac ammoaas mnmmm scrizv um mcsm mcsm soc copmm cm: 3c szr :mm mmmm csmm ccc acpmm cccrm 3m czr :mr madmpahm mmmMMMNm Apmomv Npfldoo .oz pflsHmm sowpmoog mo 50ppom mo mos soapm>mam 64 mcmc come mum mccv race wficm>ahm mo aoppom mamr NBOV mmmr #30 0mm moo crm mac mmcv rmm mammbahm Apmomv mo ace soflpm>mam mHmCmHHHm mamcmaawm mossoz mmsmsmm oozmcog hpddoo mmmrm marmm mscmm ummmm crmrm .oz pmsncm 3: 3e mm Mm me twa um :mm 1m amm orm 1mm use Iwm tom Cowpmoog APPENDIX B 65 mmma Ho pdoohoa v moumowcsH * nn nn 5. c.¢r m. n.¢m mcmcr wernZMVnmv waoomse nu nn nn nn un nu mower 3m nzcvnm mpmocoz nu v.e nu 0.6 r. r.mm cmmcm mm nzsvumm «accuse nn nn nn nn un un mmvcm um nzcvncr camsca: nu nn 5.5 m.ms c.c r.mr sccm mm uzsvnum ccchaz nn nu nn nn nu nn cmm 3mvn2mrumm camooc nn nn nn nn nn un corms mmanmrnmm ccncm nn nn nn nn un nn mmmrv sceanvnmm chscoc nn nn m.¢ m.r cc. r.mm cmvmr sceanrncr camccc un nn nn nn nn nn scam 33 nznrnm cnmac nn nn nn as m. mm mcmmr scrnzmruom wHoccmc un nn nn nn nu nn mmcm Mm namrncm caucus nn nn nn nn nn nn cmec ssrnzcmnre mama nn nn nn nn nn nu comm 3m nzcmnx cacao nu nu nn nn nn un mmmcm 3mvuzrmum ccpmscc: nn nu nn nn nn nn acmmm 3mrn2mmnc ccpmasc: nu nn nn nn nu nn cvscm scruZKmucm cccmmcw: nn c.r nu .r vc. ¢.nc crvmm 3s nammnvm cncmscnc nn nu nn nn nn nu mcrmm mm nammncw accomc nu m.r nn .r so. u.um commm as nammnmm msmwxamm nn s.v nu .v rc. m.uc mmmmm 3m nammnv msmmsawm nn nu nn un nu nu vcecm 3m nacmnmm omcmpc nn nn nn nn nn nu csmmm Mm uzcmnm mamma< nn un nn nn nn nn mummm 3m nzcmumv cwcmpc nn nn un nn nn nn mommm 3m nzemndr aanpn< nn nu nn nu nn nn rccmm mm nammnmr mumcad nu nu nu nn nu nu mmomm mm nammnmm chH cscmcnm nu nn m.mm 3.6 r. c.0m cccz mm uzsmnm chH cscmcnm Hmnwsfiz mpflkwmm>m pkwno mphflfid ospmm Rmpw oz flowpwooq hpdfioo cflpmwao unopnmo pfianom mam: oapmm cam mmmpcoopmm map mo dospodnpmcoo ma comb mHHmB .m mqmde m Nanmmm< 66 Hmhoaflz I L\U\K\ ION?“ mpfisommbm pamso spamsm v0. 0‘ M ‘— r0 0\ 3- mCDNN V'NNO N\ T‘ LR I \OLROLROOLRBVTLRGDNCD capmm. oapmwac 6pm Isopsmo 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N II' 'II II II .3 o m nn 6.3 V ll 0 . .II V. nn $.06 nn nn w.rv m '-l lu' Illl v 'II II. III w 0R. III m III. II' loll r I 'l. m 0N. .I' mmnodflz muflnommam psmflo ‘— O L(\U\CIS U\U\KO L{\ U\ U\ * TWDNROHOC3V |C\QHRV‘§ O\ Lf\ o** [Av-V G\ Nd 66v *v 0.08 *r mpnwsm N\ NV c5 V V?— O o o o a V- KO #V—v-mW‘OH3U\MKDNNVWDCDOVDCDQKDGDDJD T" 'r EKUV' CHDCD do. N'\O 0‘ M 00. r0. N.rm r. mo v. m.m NO. cfipmm oapmmac 5.66 6.mc m.mm v.03 6pm nsonswo mmmrm marmm m¢6mm mmmmm 68 em mmsvm cums cmcwm cmmcr m¢6sm mmmc morem mmmm 66km 6cm» mammm mmmcm mvcrm crmmm 6c¢mm ncmnv armor sauce 66cmm 66mam rcmcm sumcr scam c66mm m6crm nemm ecmmv mmm6 663mm mammv mummm Ooz pasncm 3s nmm n6 3r n66 um m6 n66 nrm m6 n66 use me n66 nmm 36 nmm um m6 nmm nmv m6 nmm n6m 3cvum6 us 36enm6 nmm 3evnm6 nxv 3v n66 ume m6 n66 ncv m6 n66 nsm 36en66 um 36 n66 use 36 nmm n6m 3m n66 ncr m6 nmm use 36 n6: nrm 3e nms nmv mm n6: n6m ms n6: n6m me n6: nee 36rnmm n6m 36 nmm nmm mornmm n3 36vu6m nmm 3m n6m nmv 3m n6m nmr m6 u6m n6m ms n6m nmm 36rn6r n6m 36 n6: n6 Mu nmr um 30rn2r 1w GOH PmOOH oawcmaawm mamcmaafim condo: oozmsmg mmswsog nosmhm mozmsmg mozmsmg smwssmm mmmo cccmcc .pm mamcmaawm cosmos omzmsmq mmmo cacmcc .pm nocmhm mamcmaafim mozmsma anomamo domxomb mnhmz zmsmpnmmz somxomb doflHHmm adonawo mdhmB smhdm d6> ddonamo momxomh odth zwsopnmmz dossm dm> smonamo swsmpnmmz nmwoaad nuanco HICHIGQN STQTE UNIV. 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