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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 66 (1982)

Issue: 8. (August)

First Page: 1168

Last Page: 1168

Title: Distribution of Layer-Parallel Shortening Fabrics in Appalachian Foreland of New York and Pennsylvania: Evidence for Two Non-Coaxial Phases of Alleghany Orogeny: ABSTRACT

Author(s): Peter Geiser, Terry Engelder

Article Type: Meeting abstract

Abstract:

A structural interpretation of a part of the central and northern Appalachian foreland, uses the correlation of mechanical twinning, solution cleavage, crenulation cleavage, pencils, joints, and deformed fossils. Such a correlation suggests that within the central Appalachians, the Alleghanian orogeny consists of two major phases: a deformation possibly as old as Pennsylvanian, herein called the Lackawanna phase, and a second deformation, termed the Main phase, which is Permian or younger in age.

The Lackawanna phase affects mainly the eastern parts of the foreland, such as the Hudson River Valley and Pocono Plateau, while the Main phase affects most of the Valley and Ridge and Alleghany Plateau. The Lackawanna phase is interpreted as the product of strike-slip motion possibly between the Avalon microcontinent and North America. The Main phase may record the final convergence of Africa against North America and its accredited microcontinents.

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