Deposition, stratigraphy and diagenesis of Ordovician carbonates of Maury County, Tennessee.

摘要

Research focuses on depositional environment, stratigraphy, and diagenesis of the Upper Middle Ordovician carbonates from the Catheys, Bigby-Cannon, and Hermitage Formations and Carters Limestone (M6, M5, and M4 sequences) within Maury County, Tennessee of the Central Basin. These carbonates occur in the Nashville Dome, which is part of the forelands adjacent to the Appalachian and Ouachita Mountains. Central Tennessee has been subject to Early Cambrian rifting, climate change, and orogenic events, which have affected the regional structure, deposition of strata, and erosional processes within the Nashville Dome Region. Eventually, erosion became dominant within central Tennessee, causing the peripheral bulge to transform into an erosional basin. These upper middle Ordovician rocks of the Mohawkian series are mostly comprised of carbonates, with varying amounts of siliciclastic mudstone.;Stratigraphic sections were conducted throughout Maury County of the Catheys, Bigby-Cannon, Hermitage Formations and Carters Limestone (M6, M5, and M4 sequences) in order to evaluate variations in depositional environment and microfacies. Thin sections were created and a full classification was conducted in the lab to develop diagenetic models for Ordovician carbonates in Maury County, TN. Twenty-one microfacies were identified throughout all four formations with the Bigby-Cannon Formation making up 19 of the 21 microfacies observed. The Bigby-Cannon Formation was the most diverse of the four formations studied due to spatial variability in depositional environment; such as, microhabitat changes within the shallow subtidal depositional environment.;Due to the level of continuous and repeated change the Nashville Basin has sustained, 27 petrographic characteristics were observed that delineate a complex diagenetic history. Therefore, the final results indicate spatial variability in depositional and diagenetic characteristics of the M6, M5, and M4 sequences throughout Maury County, including preferential zones of depositional and secondary porosity development that may be utilized to better interpret fluid, both water and hydrocarbon, within these Ordovician strata.