Subaqueous Gravity Flows in the Rader Member, Capitan Reef Complex (Permian), Delaware Mountains, West Texas
Published:January 01, 1989
Ellen C. Lawson, 1989. "Subaqueous Gravity Flows in the Rader Member, Capitan Reef Complex (Permian), Delaware Mountains, West Texas", Subsurface and Outcrop Examination of the Capitan Shelf Margin, Northern Delaware Basin, Paul M. Harris, George A. Grover
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The Rader Member contains coarse, allochthonous carbonate debris deposited on low-angle slopes (<10°) basinward of a ~500 m, higher-angle (30°) foreslope (Rigby, 1953; King, 1948). Subaqueous gravity flows fill channels which have up to 40 m of relief. Bed thickness for a single flow ranges from <1 m to as much as 15 m. Some mass flows are traceable >6.5 km parallel to depositional strike and extend >17 km southeast from the toe-of-slope into the Delaware Basin. A previously undocumented, prominent basin-sloping erosion surface occurs at the base of the mass flows and truncates 55 m of section in the toe-of-slope (Fig. 1). The angle of truncation is as high as 7° in the toe-of-slope and diminishes to <1° along the basin slope.
Subaqueous gravity flows in the Rader section exhibit features which suggest deposition from debris flows, turbidity flows, and possibly from density-modified grain flows (or grain flow-debris flow (Hampton, 1979)). Features which imply a debris-flow origin include poorly sorted and graded debris, a wide range of clast sizes, chaotic orientation of clasts, matrix support, and some large rafted clasts near the top of the bed. Atypical features observed are a fine, quartz-rich sand matrix with a small amount of mud (<1%) and appreciable rounding of the clasts. Rader debris flows were competent to carry limestone boulders up to 10 m across in their longest exposed dimension.
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Subsurface and Outcrop Examination of the Capitan Shelf Margin, Northern Delaware Basin
Shelf sandstone reservoirs are becoming a more and more common exploration target. What they are, how they may be characterized, and how they differ from shoreline and deep-water deposits in the subject of this publication. Shelf sands and sandstone reservoirs are among the more poorly understood types of sandstones. Continental, shoreline and deep water sandstones have all been studied in much more depth than have shelf sands and sandstones. However, during the last fifteen years significant progress has been made in understanding shelf sands and sandstones. Studies of modern sediments have allowed us to understand many of the depositional processes active on the shelf. This book is intended to be an up-to-date summary of shelf processes and products. The papers are intended for those new to shelf sands and sandstones as well as the shelf specialist.