--> ABSTRACT: Bituminous Coals of the Texas Gulf Province, by J. R. Sanfilipo, R. W. Hook, P. D. Warwick, and S. S. Crowley; #91021 (2010)

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Bituminous Coals of the Texas Gulf Province

SANFILIPO, J. R., R. W. HOOK, P. D. WARWICK, and S. S. CROWLEY

There are two known occurrences of bituminous coal in the Gulf Coal Province, both differing from the more commonly occurring lignites of the province in age as well as rank. The Eagle Pass area of Maverick County, Texas, was a major producer of high volatile C bituminous coal until World War I. The coal occurs in rocks of presumably deltaic origin in the middle part of the Upper Cretaceous (Maastrichtian) Olmos Formation. Analyses of 38 underground mine samples (some washed) recorded between 1889 and 1923 indicate 6.3% average moisture (as rec'd), 18.8% ash, 1.3% sulfur, and 10,600 Btu/lb. Stratigraphically equivalent raw coal being mined near Piedras Negras, Mexico, is reported (DNAG P-3, p.123) to yield 33.3% ash (1% sulfur); mean vitrinite reflectance is reported as 0.58%. Permit files for a planned surface mine on a tract about 4 mi northeast of Eagle Pass show three minable seams of 2, 3 and 5 ft average thickness, respectively.

At the second area, the Santo Tomas field in Webb County, Texas, about 600,000 tons per year of high volatile A bituminous coal is being surfaced mined from two zones in the lower middle (Lutetian) part of the Eocene Claiborne Group, mostly for export as lump coal for household use. The coal is cannel-like, consisting of about 71% gelified groundmass, with an algal-rich liptinite fraction of about 23%, which probably accounts for the anomalously high calorific value of 12,315 Btu/lb (as rec'd). Four channel samples of three beds currently being mined (2.3, 0.7, and 1.812.0 ft thick, where sampled) averaged 3.8% moisture, 14% ash, 1.2% sulfur, 34.8% fixed carbon, and 0.53% R[max].

Resource estimates of 525 and 115 million tons in-place, made respectively for these two areas by Mapel (1967, USGS Bulletin 1242-D), are currently being revised for the Gulf Coast Region of the USGS National Coal Assessment.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.