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Depositional microfacies and burial diagenesis of Upper Jurassic Cotton Valley Limestone, Teague Townsite field, central Texas

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6375406

The Cotton Valley Limestone, like the older Smackover, was deposited on a ramp where the monotonous regional topography was punctuated by salt-generated and basement highs that greatly influenced local depositional environments. Teague Townsite field is located above a salt ridge that was once divided into several domes where Cotton Valley grainstones were deposited. Open marine wackestones and packstones surrounded those oolite shoals and, updip, shaly wackestones were deposited in a more restricted environment. An overall increase upward in the carbonate grain/mud ratio resulted from a Late Jurassic regional regression. Nine smaller, shoaling-upward cycles are present in the study area; they probably reflect local salt movements. The reservoir at Teague Townsite field is mainly intraparticle porosity formed by early leaching of metastable allochems in the meteoric phreatic environment that was contemporaneous with several of the periods of local emergence. Neomorphism and replacement were common in early diagenesis. Subsequently, compaction, stylolitization, sparite cementation, and introduction of saddle dolomite occurred. Whole-rock analyses indicate that the present-day trace element distribution reflects (1) early cementation and flushing of porous zones; (2) comparatively less flushing of muddy zones; and (3) introduction of subsurface fluids. Whole-rock deltaO/sup 18//deltaC/sup 13/ values plot within the range of published data for typical Jurassic cements. A tendency toward heavier isotopic composition with increasing depth is interpreted to be the result of subsurface fluid influx during burial diagenesis.

Research Organization:
Texas A and M Univ., College Station
OSTI ID:
6375406
Report Number(s):
CONF-8304200-
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:3; ISSN AAPGB
Country of Publication:
United States
Language:
English