Skip to Main Content
Book Chapter

Large-scale Tectonic Controls on the Origin of Paleozoic Dark-shale Source-rock Basins: Examples from the Appalachian Foreland Basin, Eastern United States

By
Frank R. Ettensohn
Frank R. Ettensohn
Department of Earth and Environmental Sciences, University of Kentucky, 101 Sloan Bldg., Lexington, Kentucky, 40506, U.S.A. (e-mail: f.ettensohn@uky.edu)
Search for other works by this author on:
R. Thomas Lierman
R. Thomas Lierman
Department of Geography and Geology, Eastern Kentucky University, 521 Lancaster Ave., Richmond, Kentucky, 40475, U.S.A. (e-mail: tom.lierman@eku.edu)
Search for other works by this author on:
Published:
January 01, 2013

Abstract

Recent plays like the Middle Devonian Marcellus Shale and possible prospects like the Upper Ordovician Utica Shale point out the significance of dark-shale source rocks in the Appalachian Basin. Mapping the distribution of such shales in space and time throughout the basin shows that periods of dark-shale deposition coincided with orogenies and the related formation of foreland basins. The fact that foreland basins form and become repositories for organic-rich dark-shale source rocks is mostly the result of deformational loading in the adjacent orogen. Tectonism mostly exerts its control through the flexural effects of deformational loading and subsequent relaxation in the orogen. These flexural processes generate sedimentary responses in the foreland basin that are reflected in a seven-part unconformity-bound cycle, of which dark shales are a major component. Because orogenies comprise a series of smaller deformational events, or tectophases, and each tectophase generates a similar cycle, many foreland basins typically exhibit a cyclic array of dark-shale and intervening clastic units, called tectophase cycles. Thirteen such third-order tectophase cycles, formed during four orogenies, are present in the Appalachian Basin. Using examples of foreland-basin dark-shale units formed during the Ordovician-Silurian Taconian and Devonian-Mississippian Acadian/Neoacadian orogenies, the timing of cycles and migration of successive dark-shale units within them relative to the progress of orogeny are presented as evidence of causal relationships between tectonism and dark-shale sedimentation. However, tectonic influence may extend well beyond the confines of the foreland basin in the form of far-field tensional and compressional forces. This may impel the yoking of foreland and intracratonic basins as well as the reactivation of foreland basement structures—the former allowing dark-shale depositional conditions to move from one basin to the other, and the latter, inaugurating new basins for dark-shale accumulation.

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables

Contents

AAPG Memoir

Tectonics and Sedimentation: Implications for Petroleum Systems

Dengliang Gao
Dengliang Gao
Search for other works by this author on:
American Association of Petroleum Geologists
Volume
100
ISBN electronic:
9781629810010
Publication date:
January 01, 2013

GeoRef

References

Related

A comprehensive resource of eBooks for researchers in the Earth Sciences

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Subscribe Now