T*Ranch Sedimentology




Doggett, Turner

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Turner Doggett


3 Abstract: TRanch is located 15 miles north of San Angelo, TX on the edge of the Permian basin and the Edwards Plateau, in the North Concho River drainage basin. The area of study is around 10,000 acres. Rocks in the subsurface consist of Permian Guadalupian and Ochoan series mixed siliciclastic, carbonate, and evaporite strata (Ferring, 2007). Cretaceous rocks exposed at the surface are characterized as shallow-marine, lagoon, beach shoals, and peri-tidal depositional environments deposited in a global transgressive sequence throughout the Comanchean Epoch (Rose, 1972). The depositional environments of the Cretaceous western-interior seaway were characterized by sedimentation patterns that affected the geometry of the seaway caused by regional tectonics related to the Laramide Orogeny (Blakey, 2014). Key signatures of the paleo-climate and depositional environment can be obtained from isotopic geochemistry stable isotope analysis, thin-section analysis, and certain fossil and trace fossil assemblages in the carbonate rocks on the Turner Ranch. Cretaceous surface exposures underwent burial from max global transgression, the seaway retreated due to Laramide uplifts, much erosion occurred affecting the Cretaceous rocks exposed and creating an unconformity. Quaternary alluvial and playa deposits gently covered Permian rocks and some of the Cretaceous rocks in the area of study. Surface geology on the TRanch consists of Cretaceous: (Kft) Fort Terrett and (Ka) Trinity Antler Sands formations as well as later Quaternary: (Qau) Alluvium Undivided and (Qal) recent stream deposits. Basin and Range extensional systems have affected the regional geology.



Geology, Sedimentology