GEOLOGIC PROBLEM SOLVING WITH MICROFOSSILS IV
AN INTEGRATED REEVALUATION OF WILCOX/CARRIZO STRATIGRAPHY, BASTROP COUNTY, TEXAS: REFINED CHRONOSTRATIGRAPHY AND REVISED PALEOENVIRONMENTS
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Published:January 01, 2019
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CiteCitation
THOMAS D. DEMCHUK, CHRISTOPHER N. DENISON, JENNIFER M.K. O’KEEFE, 2019. "AN INTEGRATED REEVALUATION OF WILCOX/CARRIZO STRATIGRAPHY, BASTROP COUNTY, TEXAS: REFINED CHRONOSTRATIGRAPHY AND REVISED PALEOENVIRONMENTS", GEOLOGIC PROBLEM SOLVING WITH MICROFOSSILS IV, RICHARD A. DENNE, ALICIA KAHN
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Abstract:
An integrated palynological and sedimentological study of Wilcox/Carrizo outcrops in and near Tahitian Village, Bastrop County, Texas, has led to a reevaluation of their chronostratigraphic significance and depositional environments. Strata at the well-known Pine Forest Golf Course and nearby Red Bluff outcrops, together with lesser-known outcrops in the vicinity, are important for source-to-sink linkages with coeval downdip Wilcox Group strata in the deep-water Gulf of Mexico (GOM).
This updip succession is fragmentary, with erosional breaks between lithologic units. It represents nearshore shallow-marine to coastal environments throughout, with widespread evidence of tidal influence. Shallow-marine trace fossils are present, and although these are generally sporadic in sandstones, the Calvert Bluff Formation includes extensive Ophiomorpha galleries. Sabinetown Formation parasequences are mostly mud-dominated tidalites with locally common marine trace fossils in more arenaceous intervals. A bioturbated siltstone immediately above the Sabinetown Formation yielded the first Texas record of common to abundant Apectodinium, an acme potentially indicating the Paleocene–Eocene Thermal Maximum (PETM), and thereby providing a correlation with PETM intervals in GOM wells. At all locations, the base of the Carrizo Formation is a marine Glossifungites surface. Siltstone rip-up clasts draped on sigmoidal cross-beds and robust Ophiomorpha indicate the Carrizo Formation probably represents a tidal delta, not fluvial channels.
- assemblages
- Bastrop County Texas
- biostratigraphy
- Calvert Bluff Formation
- Carrizo Sand
- Cenozoic
- Dinoflagellata
- Eocene
- lithostratigraphy
- marine environment
- microfossils
- middle Eocene
- miospores
- morphology
- Paleocene-Eocene Thermal Maximum
- paleoenvironment
- Paleogene
- palynomorphs
- pollen
- shallow-water environment
- Tertiary
- Texas
- tidalite
- United States
- Wilcox Group
- Sabinetown Formation
- Bastrop Texas