Upper Jurassic microbolite buildups in the little cedar creek and Brooklyn fields in SW Alabama
This study investigates the stratal relationships of a pure microbolite within the Upper Jurassic strata at the Little Cedar Creek, and Brooklyn Fields, or complex, for the development of a refined exploration model of Smackover reefal buildups in the eastern Gulf Coast. During the Jurassic, southwestern Alabama was divided by Appalachian ridges into three sub-basins: the Conecuh Embayment, Manila Embayment, and the eastern extension of the Mississippi Interior Salt Basin. The complex is located in the Conecuh Embayment of southeastern Conecuh County, Alabama, and is the largest accumulation of hydrocarbons discovered in the state of Alabama. As of January of 2014 hydrocarbon production is currently over 31 million barrels of oil and over 34 billion cubic feet of gas. The microbolite buildups formed in an inner ramp setting of the Upper Jurassic (Oxfordian) Smackover Formation.The Little Cedar Creek and Brooklyn Fields are anomalous discoveries compared to other oil and gas fields in the region. Previous studies observed that microbial nucleation occurred on Paleozoic crystalline basement highs where depositional fabrics were heavily modified by dolomitization. Instead, the complex's microbolite buildups developed on mudstones, have no apparent association with paleo-highs, and have retained a large percentage of original depositional fabrics.This study found thrombolitic reefs develop on paleotopographic highs that were indicated by a thinning of underlying transgressive lime mudstones.
Thesis (M.S.)--Wichita State University, Fairmount College of Liberal Arts and Sciences, Dept. of Geology