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Petrography and Environmental Analysis of Some Pennsylvanian Limestones from Central Texas

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Petrography and Environmental Analysis of Some Pennsylvanian Limestones from Central Texas ftfflse Memorial Library Petrography and Environmental Analysis of Some Pennsylvanian Limestones from Central Texas GEOLOGICAL SURVEY PROFESSIONAL PAPER 315-E Prepared in cooperation with the Bureau of Economic Geology The University of Texas Petrography and Environmental Analysis of Some Pennsylvanian Limestones from Central Texas By ROBERT T. TERRIERE PENNSYLVANIAN AND LOWER PERMIAN ROCKS OF PARTS OF WEST AND CENTRAL TEXAS GEOLOGICAL SURVEY PROFESSIONAL PAPER 31S-E Prepared in cooperation with the Bureau of Economic Geology The University of Texas UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963 UNITED STATES DEPARTMENT OF THE INTERIOR STEW ART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. - 20402 CONTENTS Page Page Abstract-____--_______ ______ 79 Constituents of the limestone Continued Introduction ________________ 80 Authigenic constituents Continued Purpose of the study. ____ 80 Other minerals _____________________________ 94 Geologic setting. ________ 80 Description of limestone units of the Graham formation.. 94 Methods of study. _______ 85 Limestone unit A of the Bluff Creek shale member__ 94 Constituents of the limestone.. 87 Limestone unit B of the Bluff Creek shale member. _ 96 Calcite ooze___ ______ ____ Limestone unit C of the Bluff Creek shale member__ 97 Sparry calcite ___________ Limestone unit D of the Bluff Creek shale member._ 98 Fossils. _ ---____--_______ Limestone unit CD of the Bluff Creek shale member__ 99 Algae ______________ Limestone unit A of the Gunsight limestone member.. 100 Smaller Foraminifera. 90 Limestone unit fiof the Gunsight limestone member._ 102 Fusulinids __________ 90 Limestone unit C of the Gunsight limestone member.. 103 Corals ______________ 90 Sandstone and the sand fraction of the limestone.______ 105 Bryozoans- _________ 91 Shale and the clay fraction of the limestone________-_-_ 106 Brachiopods_______-_ 91 Clay minerals in insoluble residues of limestone_____ 107 Mollusks ___________ 91 Clay minerals in shale.__________________________ 107 Echinoderms ________ 91 Quantitative study of heights of 10-A and 7-A peaks __ 108 Other fossils_----___,, 91 Summary of conclusions-__---_----__-__--------- 108 91 Distribution and interrelations of constituents. _________ 109 Pellets___ _ ___________ 92 Insoluble residues.._____________________________ 109 Limestone fragments. 92 Associations of constituents______________________ 111 Terrigenous constituents _ 93 Limestone varieties and their depositional environ­ Authigenic constituents. _ 93 ments -_____-___-_________---__-____-_-_-__-_ 117 93 Geologic history____________________________________ 121 Barite_ ______ 93 References cited__-__-_-________-___________--__---- 123 Iron minerals 93 Index _____________-_-_-______-__-_____-----__--_-_ 125 ILLUSTEATIONS [Plates 31 and 32 in pocket. Plates 33-38 follow index] PLATE 31. Graphs of amounts of fossil and insoluble constituents in limestone samples from the Bluff Creek shale and Gunsight limestone members of the Graham formation. 32. Graphs of amounts of fossil and insoluble constituents in samples of limestone unit A of the Gunsight limestone member of the Graham formation. 33. Algal types seen in thin section. 34. Sparry calcite "balls," pellets, and reworked limestone fragments. 35. Reworked fusulinid and authigenie minerals. 36. Thin sections of limestone units A, B, and CD of the Bluff Creek shale member of the Graham formation. 37. Thin section of limstone units C and D of the Bluff Creek shale member of the Graham formation and limestone unit A of the Gunsight limestone member of the Graham formation. 38. Thin sections of limestone units B and C of the Gunsight limestone member of the Graham formation. ill IV CONTENTS FIGURE 13. Index map of central Texas showing the location of the Grosvenor quadrangle in relation to outcropping rocks__ 81 14. Composite stratigraphic section of the Graham formation in the Grosvenor quadrargle______________________ 82 15. Map of the eastern part of the Grosvenor quadrangle showing sample localities in relation to the generalized out­ crop of limestone unit B of the Bluff Creek shale member and limestone units A and C of the Gunsight lime­ stone member of the Graham formation_____________________________________________________________ 95 16. Scatter diagram of percentage of carbonate cement versus grain size in calcareous sandstone and very sandy limestone ______________----____--____-______________-___------_------_-------_----_----_-________ 106 17. Cumulative curves of amounts of insoluble residue in each limestone unit in the Bluff Creek shale member of the Graham formation-_______________________________________________________________________________ 109 18. Cumulative curve of amounts of insoluble residue in each limestone unit in the Gunsight limestone member of the Graham formation ____________________________________________________________________________ 109 19. Average amounts of insoluble residue in each limestone unit____________________________________________ 110 20. Scatter diagram of the percentage of the terrigenous insoluble residue of sand and silt size versus the totrl per­ centage of terrigenous insoluble residue._____________________________________________________________ 111 21. Scatter diagram of percentage of insoluble residue versus percentage of coralline and recrystallized algae__. _____ 111 22. Scatter diagram of percentage of sand and silt versus percentage of coralline and recrystallized algae__________ 112 23. Scatter diagram of percentage of insoluble residue versus percentage of fusulinids___________________________ 112 24. Scatter diagram of percentage of smaller Foraminifera versus percentage of fusulinids_______________________ 112 25. Scatter diagram of percentage of fusulinids versus percentage of echinoderms_____________________________ 112 26. Scatter diagram of percentage of fusulinids versus average grain size of terrigenous sand and silt_____________ 113 27. Scatter diagram of percentage of insoluble residue versus percentage of smaller Foraminifera_________________ 113 28. Scatter diagram of percentage of insoluble residue versus percentage of echinoderms_______________________ 113 29. Scatter diagram of percentage of coralline and recrystallized algae versus percentage of bryozoans__ __________ 114 30. Scatter diagram of percentage of mollusks versus percentage of brachiopods_______________________________ 114 31. Composition oi limestone samples from units A and B of the Bluff Creek shale member of the Graham formation in terms of cement, microcrystalline-calcite matrix, and particles________________-_-__-_-__________. _____ 115 32. Composition of limestone samples from units C, CD, and D of the Bluff Creek shale member of the Graham formation in terms of cement, microcrystalline-calcite matrix, and particles._____________________________ 116 33. Composition of limestone samples from the Gunsight limestone member of the Graham formation in terms of cement, microcrystalline-calcite matrix, and particles___________.______________________________________ 117 34. Relative proportions of fusulinids, smaller Foraminifera, and coralline algae and oncolites in samples fro^n the Bluff Creek shale member of the Graham formation_________________________________________________ 118 35. Relative proportions of fusulinids, smaller Foraminifera, and coralline algae and oncolites in samples fro^n the Gunsight limestone member of the Graham formation____________________________________________ ____ 119 TABLES Page TABLE 1. Check list of megafossils and ostracodes collected from the Graham formation in the Grosvenor quadrangle____ 83 2. Percentage composition of limestone unit B of the Gunsight limestone member of the Graham formation from point counts of three samples from locality 828______________________'_-______--____-_______---___--____-----_ 86 3. Graphic mean and standard deviation of grain sizes of calcareous sandstone and very sandy limestone associated with the limestone units of the Bluff Creek shale and Gunsight limestone members of the Graham formation_ 106 PENNSYLVANIAN AND LOWER PERMIAN ROCKS OF PARTS OF WEST AND CENTRAL TEXAS PETROGRAPHY AND ENVIRONMENTAL ANALYSIS OF SOME PENNSYLVANIAN LIMESTONES FROM CENTRAL TEXAS By ROBERT T. TERRIERE ABSTRACT The ooliths have both radial and concentric structure. They seem to have been especially susceptible to later replacement by Limestone units form a small part of the dominantly shale barite. Pellets are ovoid aggregates of microcrystalline cal­ sequence that constitutes the Upper Pennsylvania!! section of central Texas; they are important and distinctive marker beds cite that may be mostly fecal pellets of invertebrates. Lime­ stone fragments seem to consist of locally reworked pieces only for distinguishing and correlating stratigraphic units. Seven limestone units in the lower part of the Cisco group, slightly older than the rocks in which they occur. Some of the fossils and ooliths show evidence of reworking and may which seemed from field examination to be representative of the Upper Pennsylvanian limestone strata, were selected for detailed also be considered rock fragments. study. These limestone units are within the Bluff Creek shale Terrigenous sand and silt consist of quartz and very small member and the Gunsight limestone member of the Graham amounts of chert, feldspar, and heavy minerals. The ultimate formation. Each
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