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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 67 (1983)

Issue: 3. (March)

First Page: 411

Last Page: 411

Title: Depositional Microfacies and Burial Diagenesis of Upper Jurassic Cotton Valley Limestone, Teague Townsite Field, Central Texas: ABSTRACT

Author(s): Wayne M. Ahr, R.C. Faucette, C. Steffensen

Article Type: Meeting abstract


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 the 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 fiel 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. Interparticle porosity was filled early by equant and bladed cements. 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 ^dgrO18/^dgrC13 values plot within the range of published data for "typical Jurassic cements." The ave age ^dgrO18 values are -5 and the ^dgrC13 values are +2.5 PDB. A tendency toward "heavier" isotopic composition with increasing depth is interpreted to be the result of subsurface fluid influx during burial diagenesis.

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