Skip to Main Content
Book Chapter

Diagenesis

By
Donald L. Gautier
Donald L. Gautier
Search for other works by this author on:
Published:
January 01, 1983

Abstract

Diagenesis includes all physical and chemical changes undergone by sediments from the time of deposition until that of metamorphic transformation. Hydrocarbon source-bed potential and limestone and sandstone reservoir quality are controlled by diagenesis. During the Cretaceous, organic matter exceeded oxygen supply and sediments served as a sink for organic carbon in the Western Interior. In marine sediments with an excess of organic matter, early diagenesis is a depth-zoned process with three principal metabolic zones: (1) aerobic oxidation, (2) sulfate reduction, and (3) methane generation. Products of these zones may be used to reconstruct the early burial history of the sediment. Shales in the Western Interior have a composition similar to Tertiary mudstones of the Gulf Coast, with a clay suite dominated by mixed-layer illite-smectite (I/S). These I/S clays have undergone temperature-related burial diagenesis. In the principal transformation, smectite was converted to illite through a series of discrete steps, with the addition of K+ and the loss of Si4+. Reactions have occurred within the organic matter of the Cretaceous shales simultaneously with the clay transformations. Waters expelled from the shales during early diagenesis and during thermal transformations of organic matter and clays controlled water chemistry in the basin. Most reservoir rocks are sandstones made up of derived from orogenic highlands. Diagenesis in these reservoir sandstones was controlled by the starting composition and by fluids introduced from adjacent shales. As a group, the Cretaceous sandstones have low porosity and permeability. Most porosity loss resulted from compaction of ductile grains and from quartz

You do not currently have access to this article.

Figures & Tables

Contents

SEPM Short Course Notes

Patterns of Sedimentation, Diagenesis, and Hydrocarbon Accumulation in Cretaceous Rocks of the Rocky Mountains

Dudley D. Rice
Dudley D. Rice
U.S. Geological Survey Denver, Colorado
Search for other works by this author on:
Donald L. Gautier
Donald L. Gautier
U.S. Geological Survey Denver, Colorado
Search for other works by this author on:
SEPM Society for Sedimentary Geology
Volume
11
ISBN electronic:
9781565762404
Publication date:
January 01, 1983

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal