Abstract

In this paper coal rank trends on both sides of the Pine Mountain thrust in eastern Kentucky are used to place constraints on thrust evolution. Vitrinite reflectance () measurements on a single Pennsylvanian coal horizon (Fire Clay coal) in eastern Kentucky increase from 0.5% in the north to about 1.0% toward the SE in front of the Pine Mountain thrust. The same horizon in the hangingwall of the thrust displays lower Rmax values (0.8-0.85%). The reflectance isograds are subparallel to the thrust within approximately 10 km of the trace of the fault. We attribute thermal maturation to (1) pre-orogenic maturation by burial to a depth of about 2 km followed by (2) maturation due to conductive relaxation in the footwall after thrusting. Isotherms would not have been offset unless the thrust velocity was >> 10km / Mα. Assuming no erosion, the emergent thrust would have been approximately 3 km thick. In order to explain the relatively low reflectance values observed in the footwall, rapid uplift (>3 km/Ma) after thrust emplacement is required. Alternatively, if erosion kept pace with thrusting, the thrust sheet would have been substantially thinner (<1 >km), and thermal equilibrium would be rapidly attained in the footwall. Localized frictional heating may have caused elevated reflectance values observed in sheared coals from outcrop scale faults.

Document Type

Article

Publication Date

1-1990

Notes/Citation Information

Published in The Journal of Geology, v. 98, no. 1, p. 43-51.

© 1990 by The University of Chicago. All rights reserved.

The copyright holder has granted the permission for posting the article here.

Digital Object Identifier (DOI)

https://doi.org/10.1086/629373

Funding Information 

Work at the Center for Applied Energy Research supported by grants from the Kentucky Energy cabinet, Commonwealth of Kentucky.

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