557 IL6gui 1991-A GUIDE TO THE GEOLOGY OF WAYNE COUNTY FAIRFIELD AREA, Field Trip Guide Leaflet 1991A, April 20, 1991 Department of Energy and Natural Resources ILLINOIS STATE GEOLOGICAL SURVEY Coverphotos byD. R. Reinertsen (top to bottom) Pond Creek in flood stage, March 1991 Oil well pumpjack, western Wayne County Flooded Skillet Fork, flowing along a low sandstone bluff GEOLOGICAL SCIENCE FIELD TRIPS are free tours conducted by the Educational Extension Unit of the Illinois State Geological Survey to acquaint the public with the geology, landscape, and mineral resources of Illinois. Each is an all-day excursion through one or more Illinois counties. Frequent stops are made to explore, explain, and collect rocks and fossils. People of all ages and interests are welcome. The trips are especially helpful to teachers preparing earth science units. Grade-school students are welcome, but each must be accompanied by a parent or other responsible adult. High-school science classes should be supervised by at least one adult for each ten students. A list of available earlier field trip guide leaflets for planning class tours and private outings may be obtained by contacting the Illinois State Geological Survey, Natural Resources Building, 615 East Peabody Drive, Champaign, Illinois 61820. Phone (217) 244-2407 or 333-7372. Printedby authority ofthe State of lllirKJis/1991/300 O printed on recycled paper GUIDE TO THE GEOLOGY OF THE FAIRFIELD AREA, WAYNE COUNTY C. Pius Weibel David L. Reinertsen Field Trip Guide Leaflet 1991A, April 20, 1991 ILLINOIS STATE GEOLOGICAL SURVEY Morris W. Leighton, Chief Natural Resources Building 615 East Peabody Drive Champaign, Illinois 61820 1 CONTENTS GEOLOGIC FRAMEWORK OF THE FAIRFIELD AREA 1 Bedrock 1 Stmctural and Depositional History 3 Glacial History 6 Physiography 8 Drainage 8 Relief 8 MINERAL PRODUCTION 10 GROUNDWATER GUIDE TO THE ROUTE—STOPS 15 1 Backwater deposits filling larger valleys in the area 16 2 Exposure of glacial deposits 18 3 Uplands and some drainage features 20 4 Lunch in French Memorial Park 23 5 Uplands (discuss topography) 24 6 Restored saltwater disposal pit (discuss land surveys) 25 7 Pennsylvanian-age cyclothem and Pleistocene deposits 32 8 Pennsylvanian-age sandstone outcrop, Rock Bluff Bridge 36 9 Oil well pump 38 REFERENCES 39 MISSISSIPPIAN DEPOSITION DEPOSITION HISTORY OF THE PENNSYLVANIAN ROCKS IN ILLINOIS PLEISTOCENE GLACIATIONS IN ILLINOIS FIGURES Rock succession column iv 1 Location of some major structures in the Illinois region 1 2 Generalized geologic column of southern Illinois 2 3 Structural features of Illinois 3 4 Stylized north-south cross section of the structure of the Illinois Basin 4 5 Bedrock geology of Illinois 5 6 Glacial deposits in Illinois 7 7 Physiographic divisions of Illinois 9 8 Oil fields of the Illinois Basin 10 9 Stratigraphic traps—subsurface occurrences of oil in Illinois 11 10 Annual crude oil production in Illinois, 1905-1988 12 1 Schematic diagram of a common type of oil production unit used in Illinois 19 12 Classification of McLeansboro Group of the Pennsylvanian System 24 13 Aerial views of Stop 6 27 14 Principal meridians and base lines of Illinois and surrounding states 28 15 Index map 28 16 Exposed section of strata (rock layers) at Stop 7 33 PeriodorSystem Age Era andThickness (yearsago) GeneralTypesof Rocks \ OuoternarHyoloc0cVe)n<«oe>^ 10,000 RGleocceinotl—tialll,lugvliaucimalinoruitvwerasvha,llgeyrsavel,sand,silt, 0-500' lake deposits of clay and silt, loess and sand dunes ; covers nearly all of stole aO except norttiwest cornerond southern tip Pliocene - 51..63mm.. Chearntdgwreovsetle,rnpreIlsleinntoisin northern, southern, 36.6m.- Terfiory Mostly micaceous sond with some silt and cloy, 0-500' ^ present only in southern Illinois - 57.8m. Poleocene Mostly cloy,little sand;present only in southern 66.4m Illinois Mostlysand,somethinbedsofcloy and,locally, Mo * Cretaceous 144m. gravel)presentonly in southern Illinois 0-300' \- 286m. 55 Pennsylvanion 0-3,000' Largely shale and sandstone with bedsof coal, limestone,and clay ("CoolMeasures") 320m. Black andgray shaleat bose;middle zoneof Mississippian thick limestone thot grades to siltstone, 0-3,500' chert,andshale,upper zone of interbedded sandstone,shole,ond limestone 360m. Thick limestone,minor sondstones ondshales; Devonian largely chert ond cherty limestonein southern 0-1,500' Illinois; block shale ot top 408m. 1 I x£z Silurian Principolly dolomite ond limestone 0-1.000' 438m Ordovician Lorgely dolomiteond limestone but contains I 1 500-2,000' sandstone,shole,and siltstone formotions 505m Combnon Chiefly sandstones with some dolomite and shale; ,500-3,000' exposedonly in snDoll areasin north-central Illinois 570m ARCHEOZOIC and Igneous and melomorphic rocks; known in / N / jv PROTEROZOIC Illinois only from deep wells Rock succession chart GEOLOGIC FRAMEWORK OF THE FAIRFIELD AREA Location The Fairfield geological science field trip area lies within Wayne County, slightly northeast of the center of southern Illinois. About 260 miles south-southwest of Chicago, nearly 105 miles east-southeast of St. Louis, and about 105 miles northeast of Cairo, this area is one of the nen/e centers of the oil industry in Illinois. Bedrock Through hundreds of million years of geologic time (see rock succession column, facing page), the Wayne County area has undergone many changes. The ancient Precambrian basement composed of granitic igneous, and possibly metamorphic, crystalline rocks undenwent deep erosion that produced a landscape similar to parts of the present-day M—issouri Ozarks. During a — period when the continental plate the early North-American continent ^was beginning to rip apart (plate tectonic movements), rift valleys formed in what is now southernmost Illinois, near the Kentucky-Illinois Fluorspar IVIining District. (Evidence for these plate movements and structural changes in the earth's crust comes from surface mapping, gravity and magnetic field measurements, and seismic exploration for oil.) These rift valleys, now referred to as the Rough Creek Graben and the Reelfoot Rift (fig. 1), filled with sands and gravels shed from the adjacent uplands and with sediments deposited in lakes that formed along the valley floors. Around the beginning of the Paleozoic Era, some 525 million years ago, the rifting stopped and the hilly Precambrian landscape began to slowly sink on a broad, regional scale. This permitted a shallow sea to invade from the south and southwest. During the several hundred millions of years of the Paleozoic Era, what is now the southern Illinois area continued to receive sediments deposited in shallow seas that repeatedly covered the area. This part of Illinois and adjacent areas of Indiana and Kentucky continued to slowly sink until at least 15,000 feet of sedimentary strata had accumulated (fig. 2). These strata range from about 523 million years old (Cambrian Period) to 288 million years old (Pennsylvanian Period). In Wayne County, Paleozoic sedimentary strata reach thicknesses in excess of 10,500 feet in the northwest and about 13,300 feet in the southeast. Rocks of the Devonian and Mississippian Periods have been successfully drilled for their petroleum resources in Wayne County. At times during the Paleozoic Era, the seas withdrew and the sediments previously deposited were weathered and eroded. As a result, the sedimentary record in Illinois has some gaps. Figure 1 Location of some major structures in the Illinois region: (1) La Salle Anticlinal Belt, (2) Illinois Basin, (3) Ozark Dome, (4) Pascola Arch, (5) Nashville Dome, and (6) Cincinnati Arch. , GROVE CHURCH KINKAID . /A /£> /A ///a,//a.7/^ /. /. /. i m: ':/, /, T^z \• WALTERSBURG D~ VIENMA :/a /a/a/ -._^ :2=--\ • TAR SPRINGS X7K', GLEN DEAN /Za;//a7/a;r\-' iRnoccClhuA,dReCsBubAOenN,viDlALE HARDINSBURG y/^,/^?'7'7/;^,-^i UDudley, OjP1solytmeheosOsstftoronoU»t,»wSjniio.eqkwge.inCsf BigHFRC(AlGAiNofIE'iLycY,EoJnYadSco(ksGlooinmle)sh) i/a/,'.V/a,.v//;,.,//' SPOON BEECH CREEK ////./.././ IBnrciIdgBeeplolrO'tr,600. (Barlow,bosoiGot} -^'.^/.M/.///. IPBp2seo'naotOdblfKe,oil,no,Lri.RKnoLiDgb-uc_idkSCnloiIsepOgoyovg,no-m,,s, CWLoeii'nClideyYlrle,PeyR,KiBEerSlklwSooirod9,00, Sil(MSurrTOeieCafnCC,LA<NASiIaIgRNbroSnPRINGS mV^iX^SB, EAU CLAIRE W-lson SomRpIlDeEINPHCOrW.SEdR,(EUIIPIICI KEAONGKEAWKOEOED/SECXRTEOENK ABBOTT BETHEL Inci Beiioif800, DOIPWoiNnlEYCSrSdB.LWUilFlF) Burtschi,Cosey, (L.PC,U Ren.) Monsdeld,Dogiey YANKEETOWN Porflow, BflnoisI 3r0.4thS"gg<ns RENAULT(L-Ren.) AUX VASES STEGENEVIEVE ^Aux Voses lime CASEYVILLE OhofO includes B>er>i. Spor Mountain BJourcdhaonn.on, (Rosiclore) Pottsvilte, McCloshy c R'dgley lODIOng) « DUTCHTOWN L MCCIOShy ,^ ST. PETER Figure 2 Generalized geologic column of southern Illinois. Black dots indicate oil and gas pay zones. Formation names are in capitals; other pay zones are not. About 4,000 feet of lower Ordovician and upper Cambrian rocks under the St. Peter are not shown. (Originally prepared by David H. Swann.) The Pennsylvanian-age bedrock that lies directly beneath the cover of glacial till in Wayne County consists of strata or layers of sandstone, siltstone, shale, limestone, coal, and underclay deposited in shallow seas and swamps between about 320- and 288-million years ago. Some of these rocks are exposed in readouts and stream banks. The Pennsylvanian strata thicken from slightly less than 1,800 feet in northwestern Wayne County to approximately 2,400 feet in the southeastern. A description of these rocks and their occurrence may be found in Depositlonal History of the Pennsylvanian Rocks (at the back of this guide booklet). Pennsylvanian rocks younger than those exposed at the bedrock surface in Wayne County are known from other Illinois localities. These strata, and perhaps younger Permian strata overlying them, may have been deposited across this area. However, during the nearly 245 million years between the close of the Paleozoic Era and the onslaught of the Pleistocene ice sheets 1 to 2 million years ago, ample time passed to erode as much as several thousand feet of strata and remove all traces of their presence from this region. Fault, downthrown side indicated -t- Anticline Syncllne Monocline 40mi 50km """2ooe Figure 3 Structural features of Illinois. Mississippi Embayment Structural and Depositional History Near the close of the Mississippian Period, gentle arching of the rocks in eastern Illinois initiated the development of the La Salle Anticlinal Belt (figs. 1 and 3). Gradual arching apparently continued through Pennsylvanian time. The La Salle Anticlinal Belt is a complex structure that has smaller structures such as domes, anticlines, and synclines superimposed on the broad upwarp of the belt. It extends from La Salle County in northern Illinois southeastward as far south as Lawrence County. Because of the absence of the youngest Pennsylvanian strata from the area of the anticlinal belt, we cannot know just when movement ceased along the belt. Indirect evidence suggests that the folding and faulting had stopped by about the end of the Pennsylvanian, or perhaps a little later during the Permian Period, near the close of the Paleozoic Era. After the Paleozoic Era, during the Mesozoic Era, the rise of the Pascola Arch (fig. 1) in southeastern Missouri and western Tennessee separated the Illinois Basin from other basins to the south. The Illinois Basin is a broad, subsided region covering much of Illinois, southern Indiana, and western Kentucky (figs. 1 and 4). Development of this arch in conjunction with the earlier sinking of the deeper parts of the Illinois Basin, gave the Illinois Basin its present asymmetrical, spoon-shaped configuration. The geologic map (fig.5) shows the distribution of the rock systems of the various geologic time periods as they would appear if all the glacial, windblown, and surface materials were removed. The Fairfield field trip area is located in the southeastern part of the Illinois Basin, which extends into southwestern Indiana and western Kentucky. Smaller subsidiary structures, such as the Fairfield Basin, were superimposed on the larger basin structure at different times during Chicago Rockfo Figure 4 Stylized north-south cross section shows structure of the Illinois Basin. To show detail, the thickness of the sedimentary rocks is greatly exaggerated and the younger, unconsolidated surface deposits have been eliminated. The oldest rocks, Precambrian (Pre-C) granites, form a depression filled with layers of sedimentary rocks of various ages: Cambrian (0). Ordovician (O), Silurian (S), Devonian (D), Mississippian (M), Pennsylvanian (P), Cretaceous (K), and Tertiary (T). The scale is approximate.