John B. Droste

Middle Devonian paleogeography of the Wabash platform, Indiana, Illinois, and Ohio

During middle Paleozoic time, a broad shallow-water shelf, here named the Wabash platform, occupied nearly all but the southwest part of Indiana and extended at least as far as central and northern Illinois and western Ohio. This shelf was as predominant a sedimentational-structural feature as were the bordering protobasins in Iowa, Illinois, Michigan, and Ohio. The Middle Devonian rock record serves to show how intimately interrelated were the sedimentational histories of these major provinces. At the time of the Tioga ash fall (late early Middle Devonian), a broad carbonate flat, which included both sabkha and lagoonal environments, covered the platform. During late Middle Devonian time, the shallow-water portion of the platform was narrowed somewhat, but shallow-water normal-marine environments broadly prevailed so that the present basin-separating arches were not at all as divisive as their present eroded crestal areas suggest.

Jeffersonville Limestone (Middle Devonian) of Indiana: Stratigraphy, Sedimentation, and Relation to Silurian Reef-Bearing Rocks

The Jeffersonville Limestone (lower Middle Devonian) occupies an area south and west of the Kankakee and Cincinnati arches that is about half the size of Indiana. Its spatial and lithologic characters are described conveniently in three facies units: (1) a southern Indiana facies, 0 to more than 200 ft thick, comprising the highly fossiliferous, normal marine biozones, extending from outcrop at the Falls of the Ohio southwestward to far southwest Indiana and northward to cover about 20 counties; (2) a west-central Indiana facies, the Geneva Dolomite Member (new rank), 0 to more than 60 ft thick, consisting of brown, vuggy, pelletoidal, and bioclastic dolomite and mostly restricted in Indiana to 20 counties in the central and central-western parts of the state; and (3) the facies newly named here as the Vernon Fork Member, 0 to more than 80 ft thick, consisting variably of cyclically deposited fine-grained thin-bedded dolomite, brown granular vuggy dolomite, and nearly lithographic laminated limestone and dolomite. This facies extends beyond the Geneva facies both north and south. Facies 2 and 3 together, 3 being superjacent to 2, are northern lateral equivalents of facies 1. Fine-grained quartz sand in a carbonate matrix is present at various levels, including the concentration of sand in the somewhat restricted Dutch Creek Sandstone Member in the basal Jeffersonville. The Pendleton Sandstone Bed (new rank) is a local bed in the base of the Vernon Fork Member. In southwest Indiana the Jeffersonville lies both on Lower Devonian rocks and a basin facies of Upper Silurian rocks. In the remainder of the study area, the Jeffersonville lies on a large basin-fringing reef bank of Silurian age that has associated pinnaclelike highs both on the bank and basinward of the banks main expression (called the Terre Haute bank, a new name); also, the formation lies on back-reef and(or) on shelf-deposited interreef Silurian rocks that surround probably hundreds of discrete reefs. The Jeffersonville facies are spatially and genetically related, in both thickness and lithologic expression, to the underlying differentiations among the Silurian rocks. The southern Jeffersonville facies represents essentially continuous normal-marine deposition in deeper water that in far southwest Indiana was continuous from the time of Clear Creek deposition (Early Devonian), but some fluctuation of this depositional regimen is recorded in tongues of the Amphipora and Paraspirifer acuminatus Zones among rocks of the northern facies. The Geneva Member represents shallow-water, even shoaling, normal-marine deposition over the Silurian reef bank and reef platform. The Vernon Fork represents even shallower, at least more restricted environments that led to carbonate-flat, sabkha, and lagoonal-shelf deposition. During the time of Vernon Fork deposition, central Indiana had mostly hypersaline marine connection with the Michigan basin. The southern Jeffe sonville area was maintained under normal marine conditions and had continuous connection with the Appalachian basin through Kentucky. The Devonian drape structure (over the Silurian surface) is potentially the result of complex interaction of several factors. Among them are depositional and(or) erosional relief on the Silurian reef bank and pinnaclelike reefs, differential compaction of Silurian reef and interreef rocks (including such differentiation brought about by dolomitization of these rocks), settling of reef masses en masse into their substrate, and deposition of Devonian rocks in differing thicknesses over reef highs and interreef lows. Dolomitization and porosity development in the Geneva facies of the Jeffersonville, in contrast to nondolomitization of most of the southern facies, resulted from hypersaline Vernon Fork waters acting upon porous bioclastic sediments that had been deposited over the shallow ilurian reef platform.

TIOGA BENTONITE (MIDDLE DEVONIAN) OF INDIANA

The petrography of shale partings in carbonate rocks from eleven cores in the Illinois (Jeffersonville Formation) and Michigan Basins (Detroit River Formation) of Indiana indicates the presence of a K-bentonite which is interpreted as the Tioga Bentonite, an important stratigraphic marker in the middle Devonian rocks throughout the central and eastern United States. The clay mineral composition of the Tioga Bentonite of Indiana is interstratified illite and smectite, usually with admixed kaolinite. This composition stands in striking contrast to the simple illite suite without kaolinite in the normal terrigenous shale partings in the Devonian rocks of Indiana. Euhedral sanidine, high temperature albite, zircon, apatite, and the angularity of quartz grains found associated only with the interstratified clay mineral suite support the volcanic origin of these clay partings.RésuméL’étude pétrographique des filons de schiste dans les roches carbonatées provenant de onze carottages dans les bassins de l’Illinois (Formation de Jeffersonville) et du Michigan (Formation de Detroit River) dans l’état d’Indiana, indique la présence d’une bentonite K, qu’on interprète comme la bentonite de Tioga; cette argile est un marqueur stratigraphique important dans les roches du Dévonien moyen dans tout le centre et l’est des Etats-Unis. La composition en minéraux argileux de la Bentonite de Tioga de l’Indiana est celle d’un interstratifié illite et smectite, comprenant généralement en mélange de la kaolinite. Cette composition présente un contraste frappant avec celle de la série simple de l’illite, qui ne comporte pas de kaolinite dans les filons de schiste détritique des roches dévoniennes de l’Indiana. La présence de sanidine holoédrique, d’ablite haute température, de zircon, d’apatite et le caractère angulaire des grains de quartz trouvés seulement en association avec la série du minéral argileux interstratifié, constituent des arguments pour l’origine volcanique de ces filons argileux.KurzreferatDie Petrographie der Schiefertonschieferungen in Karbonatgestein von elf Punkten der Illinois (Jeffersonville Formation) und Michigan Becken (Detroit River Formation) von Indiana weist darauf hin, daß ein K-Bentonit vorhanden ist. Dieses wird als Tioga Bentonit betrachtet und bildet eine wichtige stratigraphische Markierung in dem mitteldevonischen Gestein, das in den mittleren und östlichen Teilen der Vereinigten Staaten weit verbreitet ist. Was die Tongesteinzusammensetzung des Tioga Bentonits von Indiana anbelangt, finden wir Einlagerungen von Illit und Smektit, in der Regel mit Beimischungen von Kaolinit. Diese Zusammensetzung unterscheidet sich auffällig von dem einfachen Illit ohne Kaolinit in den normalen terrigenen Schiefertonschieferungen der devonischen Gesteine von Indiana. Idiomorphes Sanidin, gegen hohe Temperaturen beständiges Albit, Zirkon, Apatit und die winkelige Beschaffenheit der Quarzkörner, die sich nur bei dem Tongestein mit Einlagerungen finden, erhärten die Auffassung, daß diese Tonschieferungen von vulkanischem Ursprung sind.РезюмеПетрография прослоек одиннадцати колонок глинистого сланца в карбонатной горной породе в Иллинойс (формация Джефферсонвилл) и в бассейне Мичиган, Индиана (формация реки Детройт), указывают на присутствие К-бетонита, расшифровываемого как тиога-бетонит, являющимся важным стратиграфическим напластованием в горных породах центральных и восточных Штатов Америки. Строение глинистого минерала тиога-бетонита Индианы — это переслаивающийся иллит и смектит, обычно с примесью каолинита. Это строение резко отличается от простого иллита без каолинита в нормальных терригенных прослойках глинистого сланца в девонских горных породах Индианы. Санидин, высокотемпературный альбит, цикрон, апатит и скосы зерен кварца, находимые в ассоциации только с переслаивающимися глинистыми минералами подтверждают вулканическое происхождение этих глинистых прослоек.

Clay Mineral Composition of Sediments in Some Desert Lakes in Nevada, California, and Oregon

X-ray analyses of some Recent desert lacustrine sediments in Nevada, California, and Oregon show that illite and montmorillonite are the most abundant clay minerals and that chlorite and kaolinite are present in subordinate amounts in the sediments of many of the lakes. These clay suites are derived from source rocks.

Recognition of Buried Silurian Reefs in Southwestern Indiana: Application to the Terre Haute Bank

In Indiana the buried Terre Haute Bank extends from the west-central part of the state to the south-central part. It consists of Silurian carbonate rocks several hundreds of feet thick that are dominated by dolomitized reef-derived sediments. More than 100 discrete reef bodies are recognized along what was a broad structural hinge line peripheral to the proto-Illinois Basin. At least two reef generations arose during Middle and Middle-to-Late Silurian time. The reefs, therefore, collectively have Silurian and Devonian (Lower or Middle) covers. Because deep drilling is sparse and limited seismic surveys in the bank area are confidential, mostly indirect evidence must be used for reel interpretation, consisting especially of structural deformation (broad sense) of the rocks encasing the reefs and composing the reef flanks. This deformation was a long-term process that affected even the youngest Paleozoic rocks preserved in this area, and it possibly continued to the present. Diagenesis, including differential compaction, is the most important factor, a conclusion that tempers the sometimes popular ideas on tectonic processes and on early diagenesis. Probably many reefs still await discovery. The range of circumstances that apply to these reefs (in paleogeographic setting, genesis and abortion, and erosion and burial), together with sparseness of deep drilling, suggests that this province is inadequately explored at sub-Mississippian depths for hydrocarbon potential.

Clay Mineral Alteration in Some Indiana Soils1

X-ray analyses of samples from thirteen soil profiles that were formed on glacial till, loess, and Mississippian limestones of Indiana indicate that (1) in some soil profiles chlorite of the parent material is changed completely to montmorillonite with intermediate stages of random mixed layers of chlorite-vermiculite-montmorillonite; (2) some of the illite of the parent material produces montmorillonite through random mixed layering of illite-montmorillonite, but the illite is not entirely altered in any profile; and (3) kaolinite may be produced as a weathering product, or it may remain unchanged from the parent material.

Middle Devonian Bentonite in Michigan Basin: DISCUSSION

We agree with Baltrusaitis that the thin bentonite bed that he has described as the Kawkawlin Bentonite in the Michigan basin and the Tioga Bentonite Bed that others have described in New York and in the Appalachian and Illinois basins represent one and the same ashfall. However, contrary to his view, we believe that the bentonite bed described by Droste and Vitaliano on the flank of the Michigan basin in northern Indiana is also the Tioga and thus is equivalent to the Kawkawlin. The relations of the northern Indiana bentonite bed to standard conodont zones, the beds position in a Middle Devonian physical stratigraphy thoroughly studied throughout Indiana, and the mineralogy and petrography of the bentonite all seem to indicate that the northern Indiana bentonite should not be considered as a lower (than Tioga and Kawkawlin) bentonite that would have no known equivalent elsewhere.

Stratigraphy and Sedimentation of Mississippian Ste. Genevieve-Cedar Bluff Interval, Southwestern Indiana: ABSTRACT

The Ste. Genevieve Limestone and Cedar Bluff Group of Mississippian age, both important sources of hydrocarbons in the Illinois basin, were traced from a subsurface stratigraphic section in White County, Illinois (described by Swan in 1963, across Gibson and Daviess Counties, Indiana, using electric logs and sample descriptions from 84 wells. The Ste. Genevieve Limestone is subdivided into four members and the Cedar Bluff Group into three formations. Six cross sections and nine isopach maps based on 300 wells show that these units comprise a succession of alternating fine- and coarse-grained carbonate rocks with only minor interruptions of sandstone and shale. Two complete coarsening-upward cycles are apparent, and a third cycle is incomplete. Each cycle consists of a low r sequence of lime mudstones and wackestones, and an upper sequence of oolitic and skeletal grainstones. These cycles are the record of successive shoaling-upward cycles of sedimentation on a shallow marine platform. The lower mudstone-wackestone sequence represents deposition in a shallow subtidal environment, and the upper oolitic-skeletal grainstone unit represents development of oolite shoals and tidal channels in very shallow waters. Terrigenous clastic sediments brought into the basin by the Michigan River periodically encroached into the marine environment. Dolomitization of the fine-grained carbonate sediments is largely restricted to areas which are overlain by oolitic grainstones. In eastern Daviess County, identification of the individual stratigraphic units in this interval i somewhat tenuous, but tracing the units from eastern Illinois into Indiana made correlation and identification of the individual stratigraphic units possible by using electric logs and sample descriptions. End_of_Article - Last_Page 1453------------

Structural Interpretation of Buried Silurian Reefs in Southwestern Indiana: ABSTRACT

End_Page 1283------------------------------Two or more generations of buried Silurian reefs are present in southwestern Indiana. Possibly all the larger reefs grew until Devonian time. Some may have attained thicknesses greater than those of any other group of Silurian reefs. Strata topping the reefs range from Middle or Late Silurian to Middle Devonian in age. Deep drilling is sparse in southwestern Indiana, and limited geophysical surveys are mostly confidential. Interpretation of the reef province then relies heavily on evaluation of structural deformation (broad sense) of the rocks both encasing and overlying these and other Silurian reefs and of the reefs-proper and their flanks. The amounts of suprareef drape in strata as young as Pennsylvanian are related to reef thickness, kind of reef, erosion of reef and postreef rocks, height above reef, and counterproductive subreef sagging. Both suprareef draping and subreef sagging are expectable for any given reef. Long-continued diagenesis, even to the present time, was the most significant cause of such structural deformation; subreef soft-sediment deformation penecontemporaneous with reef growth also was a factor. Differential compaction between reef and contemporaneously deposited interreef rocks was the most important diagenetic process. Differential compaction in rocks far above the reefs, acting in concert with lithologic and thickness differences brought about by continued growth of drape structure, had a min r role. Differential solution and recrystallization could have contributed especially to subreef sagging. These interpretations temper some ideas that localized tectonic uplifts influenced both reef siting and suprareef draping and that early cementation resulted in structural stabilization of substrate, reef, and reef flank penecontemporaneous with growth. The ranges in geologic circumstances that apply--in setting, reef genesis and abortion, erosion or nonerosion and burial of reefs, and postreef attainment of structural clues to reef recognition--suggest that southwestern Indiana has a reef-related reservoir potential that applies differentially within the reef province. The differential extends to the reefs themselves and to individual formations draped over the reefs. This province, surely, is inadequately explored for hydrocarbon potential in sub-Mississippian rocks. End_of_Article - Last_Page 1284------------