A.W. Erxleben, G. Carnahan, 1983. "Slick Ranch Area, Starr County, Texas", Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces, A. W. Bally
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The Slick Ranch area is interpreted to be a gravity slide (slump structure) developed contemporaneously with rapid Early Oligocene clastic sedimentation. Seismic data illustrates a classic rollover anticline onto an east-dipping regional glide plane. Slick Ranch is located along the east central boundary of Starr County, Texas, approximately 40 km (25 mi) northeast of Rio Grande City.
In 1978, Tenneco drilled the Slick Ranch No. 66 discovery which encountered multiple objectives in Frio (Upper Oligocene) and Vicksburg (Lower Oligocene) sandstones. The Slick Ranch structure is one of several similar features developed basinward of the Vicksburg Flexure system as thick accumulations of Oligocene age sediments were deposited downdip from the Jackson (Late Eocene) shelf edge.
The Vicksburg Formation (Lower Oligocene) of south Texas consists of laterally stacked wedges of regressive coarse terrigenous clastics separated locally by intervening transgressive marine shales. The area in eastern Starr, western Hidalgo, and southern Brooks counties (see index map) was a sub-basin or a localized clastic depocenter of the larger Rio Grande Embayment during Early Oligocene time. in this area, numerous down-to-the-coast syndepositional (growth) faults formed in conjunction with rapid sedimentation (see cross section). Development of these syndepositional faults was aided by the formation of an extensive "glide plane" or detachment surface coincident with the surface of older Jackson and Yegua formation (Eocene) shales.