Depositional environments of Schuler Formation (Cotton Valley Sands), Upshur County, Texas
Exploration for tight gas (FERC Section 107) production from the Schuler Formation (Cotton Valley sands) has provided recent data for the recognition of the lower Schuler (Shongaloo member) shoreface facies and delineation of the upper Schuler (Dorcheat member) delta plain complex in Upshur County. Shoreface facies within the lower Schuler have a typical funnel-shaped log pattern (coarsening-upward clastic). In core, the corresponding coarsening-upward sequence grades from offshore to upper shoreface facies. Upper offshore sediments are dominated by a heavily bioturbated and intercalated sandstone/shale sequence with numerous trace fossils, escape traces, and shell debris. Associated facies overlying the upper shoreface are lagoonal. Subaerially exposed mottled red and green siltsone and red mudstone show evidence of root penetration and are interpreted as coastal plain to tidal flat. The marsh deposits (green siltstones and red mudstones) gradationally interbed with a subtidal lagoonal facies containing dark gray, fossiliferous, argillaceous, limestone containing oysters, echinoid fragments, and annelid worm tubes. In an effort to tie the limited core data (4 wells) to a countywide environmental interpretation, sand percent interval slice maps were constructed above and below the ubiquitous subtidal lagoonal marker. These maps and core data in the lower Schuler delineate a strike-oriented, linear clastic shoreline (ENEWSW). Within Upshur County, lower Schuler sediments were deposited as interdeltaic, shoreface facies. The upper member is characterized by a dip-oriented sandstone trend interpreted as an aggradational delta plain complex associated with the Lone Oak delta system.
- Research Organization:
- Universal Resources Corp., Dallas, TX
- OSTI ID:
- 6321483
- Report Number(s):
- CONF-8304200-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:3; Conference: Annual AAPG/SEPM/EMD/DPA convention, Dallas, TX, USA, 17 Apr 1983
- Country of Publication:
- United States
- Language:
- English
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