Stacked Island Facies in Tansill Outer-Shelf Platform, Dark Canyon, Guadalupe Mountains, New Mexico
Published:January 01, 1989
S. J. Mazzullo, W. D. Bischoff, C. L. Hedrick, 1989. "Stacked Island Facies in Tansill Outer-Shelf Platform, Dark Canyon, Guadalupe Mountains, 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 Tansill Formation (Permian, Guadalupian) comprises the youngest back-reef platform facies of the Capitan Reef in the Guadalupe Mountains of New Mexico and Texas (Fig. 1). Here the Tansill is divided into "outer-shelf" and "shelf-crest" facies which pass landward into coeval bedded evaporites and sandstones (Pray, 1977; Mazzullo and Hedrick, 1985). The shelf-crest facies, consisting of peritidal dolomites with conspicuous pisolites, tepees, and some sandstones, is interpreted as a linear, low-lying island complex situated 1.6 km (1 mile) landward of the Capitan Reef (Pray, 1977; Mazzullo and Hedrick, 1985). It is therefore analogous to other island complexes of the Tansill in the subsurface (Ordonez, 1984) as well as to modern outer-shelf islands in Belize (Mazzullo and Reid, 1986). The outer-shelf facies consists mainly of biograins tones and, locally, patch-reefs deposited in shallow, high-energy environments (Mazzullo and Hedrick, 1985). Outcrops in an abandoned quarry near the mouth of Dark Canyon include spectacular exposures of stacked island deposits in the outer-shelf facies tract of the middle Tansill platform (Fig. 2A and B). These exposures lie within 0.8 km (0.5 miles) of the subsurface Capitan Reef shelf margin and are physically separated from contiguous shelf-crest facies (Fig. 2D). The occurrence of these islands is of particular significance in interpreting the depositional history of the Tansill platform, and their study provides critical information on sedimentation and diagenesis as they are related to relative sea-level fluctuations.
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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.