Pre-Pennsylvanian paleokarst at the top of the upper Pennington Formation, central Tennessee
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences
- Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Earth Sciences
Outcrop-scale features occurring at the top of the Pennington Fm. (latest Chesterian, Mississippian) suggest one or more episodes of subaerial exposure and accompanying karstification preceding deposition of basal Pennsylvanian siliciclastic strata. The Mississippian-Pennsylvanian systematic boundary in central Tennessee therefore constitutes a disconformity that can be interpreted as a 3rd-order sequence boundary. A regionally correlative, 4--6 m thick package of subtidal to intertidal marine carbonates hosts the paleokarst and occurs in the uppermost Pennington Fm. Paleokarst features were studied in detail at three outcrop sections in TN along a 100 km, northeast to southwest transect. Karst processes resulted in development of up to 30 to 35 m of local paleorelief, the evidence for which is seen in the variable stratigraphic placement of Lower Pennsylvanian units on top of the Pennington Fm.: for paleotopographic highs, either the Warren Point Ss. or Sewanee Ss. lie disconformably on the Pennington, whereas in lows, the basal Pennsylvanian Raccoon Mountain Fm. is present. Evidence of paleokarst includes: (1) dolines, filled by paleokarst breccias or by red vertic claystone paleosols, (2) discontinuous bodies of limestone clast breccias, possibly representing paleokarst collapse breccias, (3) reddening and micritization of limestone lining doline and subaerial exposure surfaces, (4) various types of karren (meso-scale dissolution) features, (5) solution-enlarged joints filled with clay, (6) synsedimentary collapse features (collapsed paleocaverns ), which deformed overlying Pennsylvanian sediments, and (7) thin-section scale fractures and dissolutional features filled with clay material and iron oxides.
- OSTI ID:
- 6786548
- Report Number(s):
- CONF-9404221-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:4; Conference: 43. annual meeting of the Southeastern Section of the Geological Society of America, Blacksburg, VA (United States), 7-8 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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