Abstract: Fence Diagram of the Coahuila and Comanche Series (Lower Cretaceous), Texas

By

L. E. Aten

A fence diagram of formations comprising the Lower Cretaceous Coahuila and Comanche Series in Texas, was prepared as part of a stratigraphic study of the Lower Cretaceous for Dr. Walter Sadlick's course "Regional Stratigraphy of North America", at the University of Houston. Because no comparable diagram was found during an extensive search of the literature, one is presented here.

It is schematic to a degree, but useful nevertheless, in that it illustrates the regional distribution of these strata in the state of Texas. Formation boundaries, where known, are included, but only the Coahuila Series and the groups comprising the Comanche Series are identified. 

The Trinity, Fredericksburg, and Washita Groups were originally defined as rock sequences (Wilmarth, 1938), but as additional data was accumulated, biostratigraphic correlations were made away from the type areas and across lithofacies boundaries. In this manner, these names have come to have a time-stratigraphic usage rather than a strictly stratigraphic usage. Murray (1961) attempted to clarify the situation by referring to the Trinity, Fredericksburg, and Washita as stages -- to include all strata which could reasonably be demonstrated to be of equivalent age to the type sequence of the unit in question. The groups are used in this sense on the fence diagram. A tabulation of the sections is presented below. It is recognized that legitimate arguments can be made against some of the correlations, however space does not permit justification of those correlations actually used here. 

Section 1: Composite section, Franklin Mountains, El Paso Co., Texas (West Texas Geological Society, 1958).

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Section 2: Composite Section, Kent Quadrangle, Culberson Co., Texas (Brand and De Ford, 1958).

(Note: Grayson (Del Rio) may be represented by either an unconformity between the Buda Fm. and the Boracho Ls., or by a discontinuous sandstone at the base of the Buda Fm.)

Section 3: Composite section, Van Horn Mountains, Culberson Co., Texas (Permian Basin Section, S.E.P.M., 1958).

Section 4: Composite section, northern Sierra Pilares, Chihuahua, Mexico (Permian Basin Section, S.E.P.M., 1958).

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Section 5: Composite Section, Glass Mountains, Brewster Co., Texas (King, 1938).

Section 6: Composite Section, Big Bend National Park, Brewster Co., Texas (West Texas Geological Society, 1965).

Section 7: Composite section, Lynn and Borden Co.'s, Texas. Modified from Brand (1953).

Section 8: Killiam No. 1, Parker, southeast Val Verde Co., Texas (South Texas Geological Society, 1960).

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Section 9: Humble No. 2, Pryor, west-central Zavalla Co., Texas (Zink, 1957).

Section 10: Stanolind No. 1, Schmidt, western Guadalupe Co., Texas (Tucker, 1962).

Section 11: Woodward No. 1, Nelson, southern Travis Co., Texas (Tucker, 1962).

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Section 12: Mobil No. 1, Kahanek, central Lavaca Co., Texas (Tucker, 1962).

 Section 13: Magnolia No. 1, Doremus, northwest Robertson Co., Texas (Zink, 1957).

Section 14: Skelly No. 1, Martin, southeast Houston Co., Texas (Coon, 1956). 

Section 15: Composite section, southwest Tarrant Co., Texas modified from Lozo, et al (1959) and Perkins (1960).

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Section 16: Raley No. 1, Morris, near Grand Prairie, Texas (Dallas Petroleum Geologists, 1941).

Section 17: Unidentified Humble well, north-central Smith Co., Texas. Modified from Coon (1956).

Section 18: Unidentified Placid well, east-central Harrison Co., Texas. Modified from Coon (1956).

References Cited

Brand, John P., 1953, Cretaceous of Llano Estacado of Texas: Univ. of Texas, Bureau of Econ. Geol., Rept. of Inv. No. 20.

Brand, John P. and DeFord, Ronald K., 1958, Comanchean Stratigraphy of the Kent Quadrangle, Trans-Pecos Texas: Am. Assoc. Petroleum Geologists Bull. v. 42, no. 2, p. 371-386.

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Coon, Lester A., 1956, Tertiary-Cretaceous Growth of the East Texas Basin: Trans., Gulf Coast Assoc. Geol. Societies, v. 6, p. 85-90. 

Dallas Petroleum Geologists, 1941, Geology of Dallas County, Texas.

King, P. B., 1938, The Geology of the Glass Mountains, Texas, Part I, descriptive geology: Univ. of Texas Bull, 3038, 167 pp., map.

Lozo, F. E., et al, 1959, Symposium on Edwards Limestone in Central Texas: Univ. of Texas, Bureau of Econ. Geol. Publ. No. 5905.

Murray, Grover E., 1961, Geology of the Atlantic and Gulf Coastal Province of North America: Harper; 692 pp.

Perkins, Bob F., 1960, Biostratigraphic Studies in the Comanche (Cretaceous) Series of northern Mexico and Texas: Geological Society of America, Memoir 83.

Permian Basin Section, S.E.P.M., 1958, Cretaceous Platform and Geosyncline, Culberson and Hudspeth Counties, Trans-Pecos Texas: Guidebook 1958 Field Trip.

South Texas Geological Society, 1960, Geological Section Taylor to Glen Rose: Field Trip Guidebook.

Tucker, Delos R., 1962, Subsurface Lower Cretaceous Stratigraphy, Central Texas: in Contributions to the Geology of South Texas, W. L. Stapf (ed.), publ. by South Texas Geol. Society.

West Texas Geological Society, 1958, Franklin and Hueco Mountains, Texas: 1958 Field Trip Guidebook.

West Texas Geological Society, 1965, Geology of the Big Bend area, Texas: Field Trip Guidebook.

Zink, Edman, R., 1957, Resume of the Lower Cretaceous of South Texas: Trans., Gulf Coast Assoc. Geol. Societies, v. 7, p. 13-22.

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Unnumbered Figure. Fence Diagram of Coahuila and Comanche Series (L. Cretaceous) in Texas.

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