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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 49 (1965)

Issue: 3. (March)

First Page: 340

Last Page: 340

Title: Tectonic Chronology of Pennsylvanian Borderlands: ABSTRACT

Author(s): John C. Ferm, Robert Ehrlich

Article Type: Meeting abstract


Pennsylvanian sedimentary rocks that are exposed in the eastern United States were deposited as a broad undulating blanket from highly deformed borderlands--Appalachia on the east and Ouachita on the south. These rocks were universally involved in borderland folding. Two separate sedimentological investigations of essentially undeformed rocks closely adjoining the borderland indicate that regionally distinct segments affected depositional patterns at various times during the Pennsylvanian, and that other segments were not active until latest Pennsylvanian or Permian time.

The first study indicates that the Ouachita deformed belt, now buried beneath Gulf Coastal Plain sediments, was one of the earliest Pennsylvanian tectonic welts and provided the major source of sediments for the Black Warrior basin of northern Alabama and Mississippi. Contrasts in mineral composition of these sediments as compared with correlative sediments in northern Arkansas indicate that this tectonic welt probably plunged northwestward, with the deepest portions of the structure thus being exposed at the southeastern terminus. Exposed Appalachian structures in the southeast are definitely post-early Pennsylvanian and did not affect Pennsylvanian sedimentation in this area.

A second study of paleogeographic patterns in Allegheny and late Pottsville sediments of Pennsylvania, Ohio, West Virginia, and Kentucky shows that major source areas lay to the south, probably related to a tectonic highland paralleling the present Pine Mountain fault. Major structural deformation in the classical fold area of Pennsylvania and northern West Virginia is clearly post-Pennsylvanian and Permian.

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Copyright 1997 American Association of Petroleum Geologists