Deep-Sea Fans in Permian Delaware Mountain Group, Delaware Basin, West Texas and New Mexico: ABSTRACT

Abstract

Ancient deep-sea fans, consisting of channel, overbank, and fringe deposits, are recorded in the Permian Brushy Canyon, Cherry Canyon, and Bell Canyon Formations (Guadalupian) of the Delaware basin. Sediment economics and depositional processes that characterized the Delaware basin were very similar to those operating in modern continental borderland basins off southern California. Margins of the Delaware basin were incised by numerous submarine canyons. During times of low-standing sea-level, concurrent with glaciation, large volumes of clastic sediment were prograded across constricted shelf lagoons, swept into heads of submarine canyons by longshore and tidal currents, and introduced into the Delaware basin through the channel-levee-over-bank system. Carbonate production and reef growth ceased on the outer platform. As sea-level rose during de-glaciation, shelf lagoons expanded and the volume of clastic sediment reaching the outer platform progressively diminished; carbonate production and reef growth resumed. Basinward from the margin, where channels are narrow and deeply incised, channel width increases and amount of incision decreases. Major flow units (3-10 feet thick), restricted to deep-sea channels, commonly consist upward from the base of the following units: (a) massive, (b) large current-ripple cross-bedded sets (sand waves), (c) plane-parallel-laminated sandstone, (d) small current-ripple cross-bedded sets, and (e) plane-parallel laminae consisting of sandstone, siltstone, and shale laminae. Both large and small ripples consist predominantly of climbing End_Page 471------------------------------ ripples (ripple drift). Minor flow units (less than 3 feet thick), consisting of many different combinations of massive, laminated, small current-rippled, and silty or shaly intervals, are found in channels, over-bank deposits, and as a peripheral aureole of fringe deposits. Flow-unit thickness, velocity, and distance of travel were controlled by the volume of sediment initially released as cataclysmic avalanches and mud flows in submarine canyons. End_of_Article - Last_Page 472------------