Petrology and Depositional Environments of Upper Tannehill (Frye) Sandstone, Fastbreak Field, Stonewall County, Texas

HUGHES, F., A. JONES, V. KING,* and C. LANG, Hardin Simmons University, Abilene, TX, R. STILLWELL, Polk and Patton, Abilene, TX, and G. WESTBROOK, Hardin Simmons University, Abilene, TX

A core of the upper Tannehill (Frye) Sandstone was taken from the 2 Polk and Patton Everett (Fastbreak field, Stonewall County, Texas) to study sandstone petrology and depositional environments. The Tannehill Sandstone in north-central Stonewall County represents the distal

part of a fluvial-deltaic channel system with a source to the east and northeast. Evidence for a distal position includes a mature, quartzose mineralogy and well-sorted texture; poorly sorted and mineralogically immature conglomeratic lenses characteristic of more proximal sandstones are missing.

Detrital composition of the Tannehill Sandstone primarily is quartz with minor feldspar and chert fragments. Sandstone lithification was primarily accomplished by quartz-overgrowth cementation, with intergranular porosity reduced to a thin-section average of 10%. Calcite cementation is patchy; siderite cement and authigenic clays are uncommon. Vertical permeability barriers exist in the form of thin clay interbeds and patchy calcite cement. Optimum horizontal permeabilities range from 400-500 md.

AAPG Search and Discovery Article #91011©1991 AAPG Southwest Section Meeting, Abilene, Texas, February 9-12, 1991 (2009)