Diagenetic history of Cotton Valley limestone at Teague Townsite field, Freestone County, Texas
The Cotton Valley lime was deposited during a regressive phase of the Late Jurassic, in a shallow sea with an extensive platform. Mild salt tectonism has modified depositional and diagenetic environments through time. Petrographically observed diagenetic features include products of neomorphism, compaction and pressure-solution, cementation, leaching, and replacement intergranular porosity was occluded early by rim and pore-filling cements. Intragranular porosity was produced as a result of early meteoric leaching, a feature abundant in porous zones, and occasionally accompanied by equant cement. Compaction is expressed mainly as pressure-solution features and stylolitization. It is inferred that early mineralogic stabilization and meteoric cementation armored grains in porous intervals against burial effects. Hydrothermal baroque dolomite is most abundant in porous intervals, and occurs as void-filling cement precipitated in interparticle porosity, fracture porosity, along stylolites, and also as a replacement mineral after anhydrite. During diagenetic dissolution and reprecipitation events, certain elements substitute for Ca/sup 2 +/ in the CaCO/sub 3/ lattice in proportion to the composition of the diagenetic fluids. It also implies that much of the observed diagenetic alteration occurred in a closed diagenetic system. During diagenesis the isotopic content of a carbonate will re-equilibrate with that of surrounding pore fluids. The depletion of O/sup 18/ implies precipitation at elevated temperatures or from subsurface fluids, while C/sup 13/ consistency reflects original carbon composition. Petrography and geochemistry indicate that diagenesis occurred in the marine phreatic, mixed phreatic, meteoric phreatic, and subsurface diagenetic environments.
- Research Organization:
- ARCO Exploration, Houston, TX
- OSTI ID:
- 6535896
- Report Number(s):
- CONF-8310301-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:9; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580100* -- Geology & Hydrology-- (-1989)
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
CARBONATE ROCKS
DIAGENESIS
DISSOLUTION
FEDERAL REGION VI
GEOLOGIC HISTORY
LIMESTONE
LITHOLOGY
NORTH AMERICA
PETROGRAPHY
PRECIPITATION
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
TEXAS
USA