Browsing by Subject "Yoakum Canyon"
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Item Morphology, paleogeographic setting, and origin of the Middle Wilcox Yoakum Canyon, Texas Coastal Plain(1987-12) Dingus, William Frederick, 1959-; Galloway, William E.The Yoakum Canyon is the largest of the Gulf Coast Eocene erosional gorges and is interpreted as a buried submarine channel. It can be traced for 67 miles from the Wilcox fault zone, which defines the position of the early Eocene shelf edge, nearly to present outcrop. This paper expands on previously published descriptions of the canyon using a more extensive subsurface data base. Decompaction of the canyon shale-fill reveals that original depths of the canyon exceeded 3500 ft (1067 m). Apparent canyon wall slump scarps and a peripheral chaotic zone, interpreted as an incipient slump feature, are comparable to similar features of the late Quaternary Mississippi submarine canyon. The Yoakum canyon formed within the Garwood subembayment to the west of and adjacent to the Middle Wilcox continuation of the Rockdale delta system. Quantitative mapping of facies adjacent to the Yoakum shale indicate the following sequence of events: 1) Muddy, distal deltaic and shelf facies of the lower Middle Wilcox were deposited during a retrogradation. 2) A resurgence of progradation deposited the upper Middle Wilcox deltaic sands atop the unconsolidated, lower Middle Wilcox continental margin muds creating a density inversion which initiated slump failure of the continental margin sediments. 3) Headward erosion of the canyon across the shelf occurred contemporaneously with a subsidence-induced transgression caused by a decrease in the sediment supply. The Yoakum canyon was excavated by a combination of slumping and current scour. 4) The canyon was filled with hemipelagic and prodelta muds. 5) Progradation of the Upper Wilcox (Carrizo) deltaic sands capped the sequence.Item Paleogeographic evolution during the Eocene Upper Wilcox in the Houston embayment with consideration of the Yoakum Canyon fill(2015-05) Conwell, David Andrew; Steel, R. J.; Olariu, Cornel; Mohrig, DavidThe Eocene Upper Wilcox clastic wedge represents the second major pulse of terrigenous material into the Gulf of Mexico basin. Recent interest in the Wilcox has been reinvigorated by the drilling of the Baha prospect in 2001, and the associated discovery of 2.5 billion barrels of producible oil in deepwater Wilcox aged turbidite deposits. To better characterize and understand the deepwater deposits, research in the delivery systems that transported sediment from the Laramide uplift to the deep Gulf of Mexico is required, with a special focus on the Wilcox shelf margin. This study incorporates over 300 well logs, and outcrop to analyze the Upper Wilcox shelf deposits in the Houston Embayment. The area of this study extends from the outcrop belt in the north-northwest of the embayment down into the subsurface to the limit of down dip well control, around 150 km to the south-southeast. From west to east it extends from Gonzales County to Grimes County, around 200 km. In the Houston embayment the Upper Wilcox was previously interpreted as mainly being fluvial deposits that prograded across the relatively stable substrate provided by the underlying delta complexes of the Lower Wilcox. Previous authors have asserted that the Yoakum Canyon (Middle Wilcox) in the southwest of the field area had its entire 3,000’ filled with prodelta muds prior to the progradation of the Upper Wilcox. However, the present work shows that upper reaches of the Yoakum Canyon were filled by the sandstone units of the Upper Wilcox. Paleogeography maps, generated by differentiating between marine and terrestrial log signatures identify five distinct sequences in the Upper Wilcox. Each sequence shows linear sand trends across the shelf, generally in a north to south direction. A majority of sand was deposited in sequences three and four, through aggradation in the east and progradation in the west over the Yoakum Canyon region. The corresponding shorelines for sequences one through four remain largely pinned along the inherited shelf edge of the Lower Wilcox in the east, whereas the shorelines strongly prograde in the southwest over the Yoakum Canyon. With this new interpretation, that the Yoakum Canyon was not completely filled at the time of Upper Wilcox deposition, it is possible that the canyon delivered 2.86-7.15*106t/yr of sediment to the deepwater reservoirs. Outcrop measurements of cross strata, taken in Bastrop County, confirm the fluvial well log interpretation and provided a base for the volume calculations.