Sedimentary Depositional Environments:
The following tables provide a brief description of the typical characteristics of depositional environments found in Upper Paleozoic rocks of southwestern Pennsylvania. it is summarized from Donaldson (1974b).
The following diagrams are included here to provide the reader a guide to the kinds of depositional systems in which the Pennsylvanian and Permian rocks of southwestern Pennsylvania were deposited.
This diagram, from Fisher and others (1969), depicts the four main delta types and the kinds of depositional environments associated with each. Click on image for a larger version.
Environments of deposition in a deltaic sequence (from Horne and others, 1978).
Development of a delta sequence (from Frazier and Osanik, 1969).
Back Barrier typical section (from Horne and others, 1978).
Back Barrier Island depositional environments (from Horne and others, 1978).
Distributary Environment (from Horne and others, 1978).
Lower Delta Plain Environment (from Horne and others, 1978).
Typical Sections from the lower delta plain, bottom section with crevass splay (from Horne and others, 1978)..
Typical Sequence from lower delta plain (from Horne and others, 1978).
Upper Delta Plain Environment (from Horne and others, 1978).
Typical Section from Upper Delta plain (from Horne and others, 1978).
An example of facies relationships in deltaic sequences from the Virgin and Wolfcamp rocks of Stephens County, Texas (From Brown, 1969). Note the lateral variations in facies due to the shifting positions of the delta lobes. Pennsylvanian and Permian rocks in southwestern Pennsylvania exhibit similar lateral relationships, although the paucity of outcrops usually precludes such definition.
Model for the deposition of adjacent channel systems. New channels form in the interdstributary areas due to subsidence by compaction and dewatering. From Ferm and Cavaroc (1968).
Model for the deposition of adjacent channel systems. Note offsetting channels through time. From Ferm and Cavaroc (1968).
Here are the facies relationships in the Upper Pennsylvanian Uniontown Formation and the Permian Waynesburg Formation in southern Pennsylvanian and Northern West Virginia. Note the similarities to the Pennsylvanian of Texas (above). This is from an untitled late 1970's guidebook by A. C. Donaldson (West Virginia University, retired).
Section running NW - SE across the Pittburgh 15' quadrangle showing the relationships of sandstone bodies. Section covers the Upper Allegheny Group into the Lower Conemaugh Group. the Mahoning sandstone is at the top. Original data from Johnson (1928). From Ferm and Cavaroc (1968).
Beerbower, J. R., 1961, Origin of cyclothems of the Dunkard Group (Upper Pennsylvanian - Lower Permian) in Pennsylvania, West Virginia, and Ohio: Geological Society of America Bulletin, v. p. 1029-1050.
Brown, S. L., 1969, Late Pennsylvanian paralic sediments, in Guidebook to the Late Pennsylvanian Shelf Sediments, North-Central Texas: Dallas Geological Society, p. 21-33.
Donaldson, A. C., 1974a, Pennsylvanian Sedimentation of central Appalachians: in Briggs, G., ed., Carboniferous of the Southeastern United States, Geological Society of America Special paper148, p. 47-78.
Donaldson, A. C., 1974b, Ancient deltaic depositional environments recognized in Pennsylvania rocks of northern Ohio River valley: in Doanhue, J., and Rollins, H. B., eds., Conemaugh (Glenshaw) Marine Events, Field Guidebook, Pittsburgh Geological Society, p. F-1 to F-11.
Donaldson, A. C., and Shumaker, R. C., 1981, Late Paleozoic molasse of the central Appalachians: in Miall, A. D. ed., Sedimentation and Tectonics in Alluvial Basins, Geological Association of Canada Special Paper 23, p. 99-124.
Ferm, J. C., and Cavaroc, V. V., Jr., 1968, A nonmarine sedimentary model for the Allegheny rocks of West Virginia in Klein, G. deVries Klein, ed., Late Paleozoic and Mesozoic Continental Sedimentation, Northeastern North America, Geological Society of America Special paper 106, p. 1-20.
Fisher, W. L., Brown, L. F., Jr., Scott, A. J., and McGowen, J. H., 1969, Delta systems in the exploration for oil and gas: A research colloquium: Bureau of Economic Geology, The University of Texas at Austin, Austin, Texas, August 27-29, 1969.
Frazier, D. E., and Osanik, A., 1969, Recent peat deposits - Louisiana coastal plain: in Dapples, E. C., and Hopkins, M. E., eds., Environments of Coal Deposition, Geological Society of America Special paper 114, p. 63-86.
Horne, J. C., Ferm, J. C., Caruccio, F. T., and Baganz, B. P., 1978, Depositional models in coal exploration and mine planning in Appalachian region: American Association of Petroleum Geologists Bulletin, v. 62, p. 2379-2411.
Johnson, M. E., 1928, Geology and Mineral Resources of the Pittsburgh Quadrangle, Pennsylvania: Pennsylvania Geological Survey Bulletin A 27, 236 p.