Journal of Conference Abstracts

Syn-depositional Faulting, Folding, Fracturing and Paleokarst Development in the Capitan-Equivalent Seven Rivers and Yates Formations, Slaughter Canyon, Southern New Mexico: Implications and Applications

David Hunt (dhunt@fs1.ge.man.ac.uk)¹ & William Fitchen (William.M.Fitchen@EXXON.sprint.com)²

¹ Department of Earth Sciences, The University of Manchester, Oxford Road, Manchester, UK

² Exxon Production Research Co., Houston, Texas, USA

The depositional profile and stratigraphic architecture of the Permian Capitan Reef and its equivalent platform succession (represented by the Seven Rivers, Yates and Tansill Formations) in west Texas and New Mexico has long proven the subject of debate. Whereby many workers have interpreted the characteristic 'rollover' stratal geometries of the Capitan Reef and platform strata to preserve primary platform morphology, others have argued that these stratal patterns are largely secondary in origin. We present new data documenting the role of syn-depositional tilting, faulting, folding, and fracturing of the Capitan Reef and its equivalent platform succession in Slaughter Canyon, New Mexico, where the platform architecture observed today is largely secondary. Syn-depositional flexuring and fracturing substantially modified the platform, the sandstone fill of fractures indicates that basinward tilting occurred during 4th-order lowstands. Large fractures can be traced up to 165 m vertically, at least 2 km along strike and have a maximum displacement of 27 m. They acted as important conduits for lowstand sands (piped up to 50 m below the depositional surface to fill primary pore space in the Capitan Reef), localized penetrative paleokarstic fissures and caverns with associated fault and breakdown breccias, and acted as conduits for later dolomitizing fluids. We discuss the likely causes of the deformation with reference to outcrop and 3D seismic data from other parts of the Permian Basin, and examine implications of the study for (i) correlation of stratal surfaces, (ii) interpretation of the platform profile and paleoecology of the Capitan Reef, (iii) construction of relative sea-level curves, (iv) diagenesis, (v) platform structure, and (vi) reservoir heterogeneity.

Key Words: carbonates, fractures, Capitan Reef

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