Stratigraphy and Sedimentology of the Back-Reef Upper Queen-Lower Seven Rivers Strata, Goat Seep-Capitan Reef Complexes (Middle-Late Guadalupian, Permian), Southeast New Mexico
Published:January 01, 1989
J. F. (Rick) Sarg, 1989. "Stratigraphy and Sedimentology of the Back-Reef Upper Queen-Lower Seven Rivers Strata, Goat Seep-Capitan Reef Complexes (Middle-Late Guadalupian, Permian), Southeast New Mexico", Subsurface and Outcrop Examination of the Capitan Shelf Margin, Northern Delaware Basin, Paul M. Harris, George A. Grover
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The uppermost 27 m of the Shattuck Member of the Queen Formation (Middle Guadalupian) and the lower 156 m of the overlying Seven Rivers Formation (Late Guadalupian) represent portions of two depositional sequences (Fig. 1). A subaerial sabkha surface near the top of the Shattuck Member is interpreted to be a sequence boundary and separates the two sequences. This disconformity is widespread over the Permian Basin, correlates with a toplap surface at the Goat Seep platform margin, and suggests a major sea-level drop at the end of Goat Seep deposition. Deposition of the basin-restricted Manzanita Member of the Cherry Canyon Formation is interpreted to have occurred during this lowstand in sea level. The immediately overlying 7 to 11 m of the topmost Shattuck contains fossilized and dolomitized Permian soil caliche (dolocalcrete). The dolocalcrete occurs in a repeated series of soil profiles overlain by evaporite solution residues. These dolocalcrete cycles are interpreted to have been deposited during a time of slowly rising sea level toward the end of the Manzanita lowstand and just prior to deposition of the Capitan Reef Complex (Sarg, 1985).
The dolocalcretes consist of nodular, massive, and mottled textures containing clotted and fractured micrite, microspar, equant spar-filled solution channels, coated fractures, and pisolites similar to modern caliche fabrics. Profiles are thin (approximately 0.5 m) and incomplete, and record short-lived soil-forming conditions with little external addition of CaCO3. The upper surfaces of the dolocalcretes are hard and undulatory, and erosional in part. The overlying evaporite solution residues are composed of interbedded green/red clayey siltstone and thin, discontinuous zones of red calcitic dolomite. The dolomite consists of small angular clasts of microcrystalline dolomite in a coarsely crystalline calcite matrix. Overlying dolomite beds are commonly brecciated (Sarg, 1977, 1985).
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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.