Geology Library Development of the Mississippian­ Pennsylvanian Unconformity in Indiana By JOHN B. DROSTE and STANLEY J. KELLER DEPARTMENT OF NATURAL RESOURCES GEOLOGICAL SURVEY OCCASIONAL PAPER 55 fi,.: AUTHORS OF THIS REPORT John B. Droste is a faculty member in the Department of Geology, Indiana University, 1005 East Tenth Street, Bloomington, IN 47405, and Stanley J. Keller is a staff member in the Petroleum Section of the Geological Survey, a division of the Department of Natural Resources, 611 North Walnut Grove, Bloomington, IN 47405. Development of the Mississippian­ Pennsylvanian Unconformity in Indiana By JOHN B. DROSTE and STANLEY J. KELLER DEPARTMENT OF NATURAL RESOURCES GEOLOGICAL SURVEY OCCASIONAL PAPER 55 PRINTED BY AUTHORITY OF THE STATE OF INDIANA BLOOMINGTON, INDIANA: 1989 STATE OF INDIANA Evan Bayh, Governor DEPARTMENT OF NATURAL RESOURCES Patrick R. Ralston, Director GEOLOGICAL SURVEY Norman C. Hester, State Geologist For sale by Publications Section, Geological Survey, 611 North Walnut Grove, Bloomington, IN 47405 Price $2.50 CONTENTS Page Abstract ....................................................................................... 1 Introduction . 1 Methods and scope . 1 Evolution of the Mississippian-Pennsylvanian unconformity ........................................... 3 Geomorphology of the sub-Pennsylvanian surface ................................................... 6 Williamsport Region .......................................................................... 6 Rockville Ridges . 7 Spencer Slope ................................................................................ 8 Washington Slope . 8 Princeton Slope . 8 Mt. Vernon Uplands .......................................................................... 9 Discussion .....................................................................................10 References cited ................................................................................11 ILLUSTRATIONS Page Figure 1 Index map of part of Indiana showing the area of study ................................... 2 2 Chart showing the stratigraphic nomenclature of the Mississippian System used in this report .. 2 3 Map showing the drainage system developed on the sub-Pennsylvanian surface .............. 3 4 Map showing the named rivers in Indiana and their projected drainage into the sub-Pennsylvanian valleys of Illinois and Kentucky .................................... 5 5 Map showing a generalized paleogeographic reconstruction for Indiana and adjacent states during the highest stand of sea level in Late Mississippian time ............ 6 6 Map showing the major physiographic regions in Indiana about 325 million years ago ......... 7 7 Diagram showing the time of erosion associated with the Mississippian-Pennsylvanian unconformity in Indiana ...........................................................10 TABLE Page Table Name, source, and description of rivers shown in figure 3 ................................. 4 Development of the Mississippian-Pennsylvanian Unconformity in Indiana By John B. Droste and Stanley J. Keller ABSTRACT Gray, 1979). It is our purpose here to describe the general geomorphology of this landscape as it is In very early Pennsylvanian time the place now preserved throughout 8,000 square miles in the sub­ called Indiana was the locus of subaerial erosion. surface of western Indiana (fig. 1). About 8,000 square miles of this landscape is In Indiana the Mississippian-Pennsylvanian sur­ preserved in western Indiana beneath the rocks of the face of unconformity crops out along the eroded limit Pennsylvanian System. Data from 20,000 wells of the Pennsylvanian System from the Ohio River in provide the evidence to reconstruct this surface and Perry County northwestward to the Illinois state line to describe its geomorphology. in northwestern Warren County (fig. 1). The eleva­ Six ancient physiographic regions that show clear tion of this surface in Indiana ranges from more than relationships of landform to outcropping Mississip­ 900 feet above sea level in Monroe County to more pian bedrock have been identified. From north to than 1,500 feet below sea level in Posey County south a distinctive topography is associated with each (Keller, in preparation). The rock-stratigraphic of the ancient outcrop areas of ( 1) the Borden Group, hiatus in Indiana ranges throughout the entire Mis­ (2) the Sanders and Blue River Groups, (3) the West sissippian System (fig. 2). Baden Group, (4) the Stephensport Group, (5) the Tar Springs Formation through the Menard Lime­ METHODS AND SCOPE stone, and ( 6) the Palestine Sandstone through the Grove Church Shale. Most of the data used in this study were derived In northern Indiana the Mississippian-Pennsyl­ from petroleum- test wells. Almost all of the 20,000 vanian unconformity may represent as much as 8 mil­ well records examined have a geophysical log or a lion years of erosion. In southern Indiana that same sample set or both. Driller's logs were used only if no unconformity may represent less than 3 million years other information was available. All the data were of erosion. obtained from studying well information on file at the Indiana Geological Survey in Bloomington. Work INTRODUCTION maps showing well locations, generally at a scale of 1 inch to 1 mile, were used in plotting the data. These About 325 million years ago the rocks of the Mis­ data include the elevation of the Mississippian­ sissippian System lay exposed by subaerial erosion in Pennsylvanian unconformity, the Mississippian parts of Indiana, Illinois, and Kentucky. Subsequent stratigraphic unit (fig. 2) at the unconformable sur­ burial of this surface by sedimentation during face, and the thickness of the youngest formation Pennsylvanian time created the regional Mississip­ preserved beneath the unconformity. pian-Pennsylvanian unconformity. In the Midwest The elevations of the sub-Pennsylvanian surface the rocks of the Pennsylvanian System lie superjacent show the present regional slope of the unconformity, to strata as old as Ordovician (St. Peter Sandstone); call immediate attention to local variation and ir­ for example, see Willman and others (1975, p. 170). regularity of the unconformity due to post-Mississip­ In Indiana the Pennsylvanian strata lie on rocks as old pian structural activity, and at the local level in many as Late Devonian; for example, see Gray and others areas display configurations that mimic the ancient (1987). The geology, including stream-drainage pat­ topography before burial by sedimentation during terns, of this pre-Pennsylvanian landscape has been Pennsylvanian time. discussed for more than 35 years (Siever, 1951; Wan­ For the subcrop area of Borden strata no effort less, 1955; Gray and others, 1960; Potter and Des­ was made to determine the stratigraphic rank of the borough, 1%5; Bristol and Howard, 1971, 1974; and Mississippian rocks below group status because 2 INDIANA GEOLOGICAL SURVEY OCCASIONAL PAPER 55 .-330M.Y. Grove Church Shale Goreville Ls. Mbr. Kinkaid Cave Hill Mbr. Limestone Negli Ck. Ls. Mbr. BUFFALO Degonia Sandstone WALLOW Clore Limestone GROUP Palestine Sandstone Menard Limestone Waltersburg Sandstone Vienna Limestone Tar Springs Formation :iE w Glen Dean Limestone 1-en STEPHENS Hardinsburg Formation >- Haney Limestone INDEX MAP en -PORT z GROUP Big Clifty Formation <( 0:: Beech Creek Limestone a. Cypress Formation 1i) en WEST Reelsville Limestone 1i) en BADEN Sample Formation :ill GROUP Beaver Bend Limestone Bethel Formation -340 M.Y. BLUE Paoli Limestone RIVER Ste. Genevieve Limestone GROUP St. Louis Limestone Salem Limestone SANDERS Harrodsburg Limestone GROUP Muldraugh Formation BORDEN -355M.Y. GROUP Rockford Limestone New Albany Shale (upper part) -365M.Y. Figure 2. Chart showing the stratigraphic nomenclature of the Mississippian System used in this report. Dates arc from Shaver and others (1985). The Goreville Lime­ stone Member and the Cave Hill Shale Member arc in­ formally recognized in Indiana. (Sec Shaver and others, 1985.) 25 Miles II 0 40 Km valleys and uplands, and the outline of a drainage Figure 1. Index map of part of Indiana showing the area of system. study. The approximate eroded limit of Pennsylvanian Well spacing in many parts of southwestern In­ rocks is from Gray and others (1987). diana where very extensive drilling for petroleum has occurred provides control for every 10 acres. Par­ ticularly for these areas, data on the thickness of the lithologic variations among formations in the Borden Mississippian formation remaining below the uncon­ Group arc subtle and not easily recognized formity can help depict direction and magnitude of everywhere in the subsurface. For all other subcrop slope on hillsides and can indicate position of stream locations the Mississippian formation at the uncon­ valleys across the outcrop (subcrop) of each forma­ formitywas plotted. These data were used to produce tion. For areas where control is at least one well per an elevation map and a geologic map of the sub­ section, the position of valleys and valley-to-upland Pennsylvanian surface (Keller, in preparation). The relief can be estimated by using the elevation of the elevation of the unconformity and the geologic map unconformity and the thickness of each Mississip­ of the sub-Pennsylvanian surface were used together pian formation preserved below the unconformity. in interpreting topographic relief, the morphology of Where the well control is reduced to les~ than one MISSISSIPPIAN-PENNSYLVANIAN UNCONFORMITY IN