SMITH, Gerald J., and ROBERT D. JACOBI
Department of Geology, State University of New York at Buffalo, Amherst, NY

Abstract: Syndepositional fault-controlled reservoir formation: Lowstand shoreface deposits in southwestern New York State

Detailed stratigraphic and structural studies in southwestern New York State have refined the southern extent and movement history of the Clarendon-Linden Fault System (CLF). Based on surficial exposures in Allegany County, New York, deposition of the Famennian Rushford Formation (equivalent to the Bradford Third Sand) was controlled, in part, by fault block motion on the CLF.

Correlations of lithofacies between 76 outcrops located in approximately 1000 km² display growth-fault geometries that coincide with observed and inferred faults of the CLF. Lithofacies in 3 stacked, shoreface successions document reversals in relative fault motion during the deposition of the lower Rushford Formation. The results of the interplay between the active fault blocks and relative sealevel include: 1) variable preservation of the lowstand shoreface; 2) the creation of erosional unconformities and Glossifungities firmgrounds; 3) deposition and preservation of a coarser transgressive lag and 4) the creation of petroleum reservoirs that are laterally variable in thickness, grain-size and storage capacity.

The apparent ubiquitousness of CLF activity allows reinterpretation of Late Devonian - Pennsylvanian age sandstones and lenticular conglomerate deposits. The areas of syndepositional faulting provide better understanding of the relation of fractures and lowstand sandstones to the occurrence of historic petroleum seeps and plays in southwestern New York.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas