Isolated highstand shelf sandstone body of turbiditic origin, lower Kenilworth Member, Cretaceous Western Interior, Book Cliffs, Utah, USA

An isolated highstand shelf sandstone body of turbiditic origin has been identified in the lower Kenilworth Member, Hatch Mesa area, Book Cliffs, Utah. Relative to most other marine mudstone-encased isolated sandstone bodies, the Hatch Mesa succession has an abundance of Bouma-like turbidite beds, a greater proportion of mudstone and siltstone, is thinner (6-20 m), and is weakly coarsening-upward. These attributes, in combination with locally abundant hummocky cross stratified sandstones, a paucity of wave ripples in the background fair-weather deposits, carbonaceous matter in all facies, a lack of clinoforms, and a low diversity/abundance trace fossil suite, suggest deposition in a prodelta environment, between fair weather and storm wave base. A three-component shoreface to shelf model, consisting of delta-front, subaqueous channel and prodelta turbidite deposits, is proposed to explain the depositional environment and setting of the Hatch Mesa succession. Regional correlation has demonstrated that the Hatch Mesa succession is time equivalent with the second parasequence in the Kenilworth (KPS2), which is characterized by inner shelf turbidite bodies at a number of other localities. Paleogeographic reconstructions reveal that the Hatch Mesa succession was deposited at least 16 km basinward of the KPS2 lower shoreface, in approximately 20 m of water. The KPS2/Hatch Mesa sandstone body package is part of the early highstand systems tract, indicating that isolated or stray sandstone bodies are not solely restricted to the failing stage or lowstand systems tracts. (c) 2005 Elsevier B.V All rights reserved.