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The AAPG/Datapages Combined Publications Database

AAPG Special Volumes


Pub. Id: A065 (1990)

First Page: 25

Last Page: 44

Book Title: M 49: Prediction of Reservoir Quality through Chemical Modeling

Article/Chapter: Facies Controls on Early Diagenesis: Wilcox Group, Texas Gulf Coast

Subject Group: Reservoirs--Sandstones and Carbonates

Spec. Pub. Type: Memoir

Pub. Year: 1990

Author(s): S. A. Stonecipher, J. A. May


In the Paleocene-Eocene Wilcox Group of the Texas Gulf Coast, early diagenetic patterns appear to be related to factors such as original water chemistry, sediment texture, detrital composition, and organic content which were, in turn, related directly or indirectly to depositional environment. Rapid lateral and vertical changes in depositional environments produced markedly different early diagenetic patterns in sand units only a few feet or even inches apart.

One of the most important controls was the chemistry of the original pore waters. Flushing by fresh meteoric water produced early mica-derived kaolinite. Fresh, but anoxic, water resulted in abundant siderite. Saline marine pore waters typically led to the development of chlorite rims. Reducing or mildly reducing marine waters yielded pyrite or glauconite. Mixing of fresh and marine waters resulted in chamosite/berthierine ooids or illite, depending on oxygen content.

These patterns suggest that lateral and vertical variations in diagenetic facies defined on the basis of sediment texture, detrital composition, and early authigenic cements can be used to complement, and test, traditional sedimentologic methods of interpreting depositional environment.

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