Possibility of Abnormally High Fluid Pressures During Folding and Faulting in Eastern West Virginia: ABSTRACT

Abstract

The abundance of calcite- and quartz-filled extension fractures (veins) in brittle rocks below the thick Middle to Upper Devonian shale sequence indicates that abnormally high fluid pressures, sufficient to fracture hydraulically Lower Devonian and older rocks or to open preexisting fractures, may have existed during folding and faulting in eastern West Virginia. The geometry and orientation of the fractures indicate formation by tectonic stresses. Geologic field relations indicate a depth of burial greater than 2,500 m for the intensely fractured Lower Devonian and older sandstones and limestones during tectonism. Abnormally high fluid pressures during tectonism would be responsible for the locally high degree of fracture porosity in the Lower Devonian and older sandstone reservoirs in the area, but also may have affected the petroleum potential of the more deeply buried rock sequence.