Salt Creek Field of the Horseshoe Atoll of West Texas: A Core Record of Lowstand to Highstand Carbonate Sequence Stratigraphy

Abstract

The Salt Creek field is one of a number of carbonate reef-mound complexes of Late Pennsylvanian to Early Permian age that make up the Horseshoe Atoll of west Texas. The Salt Creek reef is composed of limestone with minor amounts of shale and reaches a maximum thickness of 280 m, averaging 96 m. Eustatic sea level changes were the dominant control of sedimentation. Eleven depositional sequences, bounded by unconformities, are recognized ranging from the late Late Strawn, through the Canyon to early Early Cisco zone. The sequences appear to coincide with established fusulinid biostratigraphic zonations for the Permian basin. Over 320 wells have been drilled at Salt Creek. Thirty wells have been cored with 20 of those analyzed for biostratigraphy. One depositional sequence is of particular interest: the early Midlle Canyon zone defined by the fusulinid Triticites primarius. Fourteen wells in the Salt Creek area have cored this zone. The depositional systems range from the lowstand wedge through the transgressive to the highstand systems tract. The lowstand wedge is composed of both allochthonous debris and in-situ carbonates. The transgressive systems tract is composed of a combination of erosional debris and skeletal grainstone-packstone shoals overlain by increasingly mud-rich wackestones representing themore » maximum flooding surface. Shallowing-upward parasequences of wackestones and baffle-boundstones with packstones and oolitic grainstone shoals characterize the highstand systems tract. Paleotographic relief from the top of the lowstand wedge to the highstand is 128 m.« less