Geology of Joppa Quadrangle, Massac County, Illinois
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Illinois Geologic Quadrangle Map IGQ Joppa-G Geology of Joppa Quadrangle Massac County, Illinois W.J. Nelson and J.M. Masters 2008 Illinois Department of Natural Resources ILLINOIS STATE GEOLOGICAL SURVEY William W. Shilts, Chief Natural Resources Building 615 East Peabody Drive Champaign, IL 61820-6964 http://www.isgs.uiuc.edu ii Introduction Structural Geology The Joppa Quadrangle contains three major types of geo- The limestone bedrock and younger sediments in the Joppa logic materials. Oldest and at greatest depth is the bedrock, Quadrangle originally were laid down in more or less hori- which dates from the Mississippian Period (about 330 to 350 zontal layers. As a result of earth movements through geo- million years before present). The Mississippian bedrock is logic time, these strata are locally tilted, folded, and broken dominantly limestone that was deposited in a warm, shal- and offset along faults. low sea that covered much of North America at that time. Bedrock is not exposed in the Joppa Quadrangle, but it is at Generally, the bedrock strata of western Massac County are the surface in nearby areas to the north, east, and west, and tilted gently toward the northeast. This tilt reflects regional many wells within the quadrangle penetrate limestone. Data upwarping of a structure called the Pascola Arch, centered from these wells have been used to construct the Mississip- in the “bootheel” of Missouri, coupled with downwarping of pian bedrock geologic map included here (fig. 1). Figure 1 the Illinois Basin, centered in Wayne County in southeastern shows the formation at the bedrock surface and indicates Illinois. These gradual earth movements took place between the topography of the bedrock surface by means of contour the Permian and Jurassic Periods, approximately 150 to 290 lines. million years ago. As a result, wells drilled near the north- eastern corner of the Joppa Quadrangle encounter younger Overlying the bedrock are deposits of weakly lithified clay, bedrock formations than do wells drilled near the Ohio silt, sand, and gravel that range in age from late Cretaceous River. The approximate distribution of bedrock formations is through early Tertiary (about 60 to 80 million years ago). illustrated on the bedrock geology map (fig. 1). At that time, the Gulf of Mexico extended northward into southern Illinois, forming the Mississippi Embayment. The A second round of regional earth movements beginning in Cretaceous and lower Tertiary sediments, which comprise the Cretaceous Period produced the Mississippi Embay- the Post Creek, McNairy, Clayton, and Porters Creek Forma- ment. The embayment was an elongate trough open to the tions, accumulated mainly in shallow, near-shore settings, Gulf of Mexico, and it is now a northward extension of the such as deltas, bays, and tidal flats. Only the McNairy For- Gulf Coastal Plain. The axis of the embayment lay close to mation (Cretaceous) is widely distributed in the map area. It the present position of the Mississippi River, and its north- underlies the rolling hills that separate the lowlands of the ern end borders the Shawnee Hills just north of the map Ohio River to the south from those of the Cache Valley to area. Cretaceous and early Tertiary marine and near-shore the north. sediments were deposited within the Embayment. The bedrock geologic map (fig. 1) shows that the upper surface The youngest geologic materials in the quadrangle date from of bedrock generally becomes deeper toward the south. The the late Tertiary and Quaternary Periods and are less than 10 southward deepening of bedrock reflects greater southward million years old. The Mounds Gravel, the reddish brown subsidence of the Mississippi Embayment. chert gravel that is quarried for road-surfacing material, caps many hills in the quadrangle and also is found at lower el- Several fault zones cross the Joppa Quadrangle. These faults evation in wells near the Ohio River. This gravel apparently are part of the Fluorspar Area Fault Complex, an intricate was laid down by large rivers during the late Tertiary and array of fractures that affect a large area of southernmost early Quaternary Periods, before the advent of continental Illinois and western Kentucky. These faults have undergone glaciers in Illinois. Although glaciers never reached as far repeated periods of activity (Kolata and Nelson 1991, Weibel south as Massac County, their influence is recorded in many et al. 1993, Potter et al. 1995). They may have originated deposits of the Pleistocene Epoch (early Quaternary). These during an episode of crustal rifting in the Cambrian Period, deposits include the Metropolis Formation (fluvial silt, sand, some 500 to 550 million years ago. Widespread fault move- and gravel found near the Ohio River); the Henry Formation ments took place during the Pennsylvanian and Permian Pe- (fluvial sand) and Equality Formation (lacustrine silt and riods, some 250 to 325 million years ago, and possibly also clay) in the Cache Valley; and the Loveland, Roxana, and during the Jurassic Period, 150 to 205 million years ago. Re- Peoria Silts (wind-blown silt known as loess). The youngest newed movements occurred after the end of the Cretaceous geologic unit in the area is the Cahokia Formation, which period (65 million years ago), displacing the bedrock surface consists of stream and river sediments deposited in the post- along with the Cretaceous McNairy Formation. Some faults glacial Holocene Epoch (the last 10,000 years). Loess units in the Joppa Quadrangle were active during the Pleistocene, are not shown on the large geologic map in order to depict yet we have found no evidence that any have moved within the underlying materials clearly. the last 75,000 years (Nelson et al. 1997, 1999). A geologic map (Finch 1967) covering the Kentucky portion Lusk Creek Fault Zone of the Joppa Quadrangle is available from the Kentucky The Lusk Creek Fault Zone, in the western part of the map Geological Survey in Lexington. area, is the westernmost major fault zone in the Fluorspar Area Fault Complex. This fault zone continues more than 30 1 N J J e" N J N 48 e" 208 ault " e" N J e 28 213 220 220 ault Zone 220 J H 240 N N G 7 91 "20 260 J J e N 1 N 4 J e" 6 N N J 3 2 J 5 162 3 N J Raum F Lusk Creek F 150 e" 150 230 e" 190 e" 24 e" N 202 Msg 136 170 J e" e" e" N J 20 N e" J J N " J e e"N 24 0 83e" 32 140 N J e" N 0 J 200 300 265 280 N " " 147 N e" J e ee"e"e"e" N J N J 140 N J e"e" J e" Msl 320 0 260 26 J 240 N N J J e" N 280 280 290 J N 30 N J 220 260 e" N J N J N e" 0 J J 0 32 175 76 N e" N J e" H 42 G 331 11 J 7 8 N J 362 N " 283 e J 7 N N e" J 160 N 10 J N J e" 12 9 10 e"202 G 7 159 N J H e" 7 J J N 194 N 133 e" J N e" 66J N 194 e" e" J N " 66 e" e" 265 375 e N J J 215 e" e" N J 166 N 52 160 J N J e" e" e" N 220 e" 200 J 180 N " N e 0 J 280 0 0 18 160 13 140 22 J 280 N 95 22 240 e" 315 260 e" 112 59N J J N J 200 N N 156 e" J e" N J Msl J " e" N e" e 107 e"405 103e" 220 e"47 200 Msl e" 16 J N N 17 200 J 232 15 Mu 15 14 400 " 215 180 e e" J e" N 53J 18 N N e" 160 J N " 138 G 7 J e 200 235 H N e" J 350 7 J N e" N e" J N J 97 J e"e" 305 625 N e"e" e" 265 e" 87 N J " 230 37 ª 122 e" e 230 N e" J 23N 0 e" 51 e" 137 150 196 J 205 e" " 250 e" e" e" e" N J e"125 e 23 e" Msm 97 J N N J 234 57 e" 180 e" e" 205 75 J N 95 e" 19 N e" 49 N J J 21 e"220 e"e" 20 308 22 24 J N e" e" N J 160 188 ault Zone Msg 220 N J Raum F 140 N J 72 e" N 30 J 120 e" 243 Ste. Genevieve Limestone N Msg 100 J and Pope Group 29 28 Msl e" 402 27 658 e" e" N 80 J 665 Msl St. Louis Limestone N J e"412 Msm Salem Limestone 33 455 e" e" 500 460 e" 34 100 Mu Ullin Limestone 3 Drill Holes Line Symbols from which subsurface data were obtained dashed where inferred, dotted where concealed e" Water well, with depth in feet Normal fault; bar and ball on downthrown side e" Engineering boring, with depth in feet G Syncline H e" Startigraphic boring, with depth in feet H Anticline G ª Dry oil test hole Contour and elevation of bedrock surface in feet. 220 Contour interval 20 feet. Complexly faulted areas not contoured. 012 MILES Figure 1 Bedrock geology of Joppa Quadrangle. Scale 1:48,000. 2 miles northeast of Joppa into Pope County, where it merges Maple Grove Site with the east-west trending Rough Creek-Shawneetown Detailed studies near Maple Grove School, 2 miles north- Fault System.