Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Depositional Settings for Upper Jurassic and Lower Cretaceous Microbial Carbonate Buildups and Associated Reservoir Facies, Northern Gulf of Mexico
(1) Department of Geology and Geophysics, Texas A&M University, College Station, TX.
(2) Geology and Geography Department, Wichita State University, Wichita, KS.
Microbial carbonate buildups and associated reservoir facies developed in Jurassic to Lower Cretaceous mixed carbonate, siliciclastic, and evaporite depositional systems in the northern Gulf of Mexico. These deposits formed in inner to middle carbonate ramp environments, in transitional settings from distally steepened carbonate ramps to rimmed carbonate shelves, and in upper slope environments on rimmed carbonate shelves. They commonly occur in low-energy environments that were subject to fluctuations in depositional conditions. Nucleation of the microbial buildups was typically initiated on firm to hard substrates (encrusted and cemented sedimentary surfaces or on crystalline basement rocks) during relative sea level transgressions that were accompanied by low background sedimentation. In the northeastern Gulf of Mexico, microbial carbonates occur in inner to middle carbonate ramp settings in the Upper Jurassic Smackover Formation. Microbialites developed in slope environments on rimmed carbonate shelves in the Upper Jurassic to Lower Cretaceous Cotton Valley Group of northeast Texas. Microbial carbonates, including Lower Cretaceous thrombolitic buildups of the pre-Sligo and Sligo Formation of western Louisiana, developed in upper slope settings on rimmed carbonate shelves. Understanding the depositional settings and stratigraphic sequences in which these microbial buildups and associated reservoir facies were formed will provide new information for exploration aimed at microbial carbonate reservoirs in the northern Gulf of Mexico.