Lakota Paleogeography and Search for Paleogeomorphically Entrapped Hydrocarbons--A Second Look: ABSTRACT

Abstract

Fair to excellent-quality Lower Cretaceous Lakota sands and chert pebble conglomerates unconformably overlie the Jurassic Morrison Formation over most of northern, central, and eastern Wyoming. This apparent uniform blanket of reservoir facies has discouraged stratigraphic exploration. Most Lakota production has been established within structural closure. A regional look at the landscape of the Lower Cretaceous of Wyoming provides a model whereby this apparent blanket of sand and gravel masks attractive regional exploration objectives. The initial Lakota sedimentary event in central Wyoming was the deposition of Lakota sands and gravels on a northward-sloping pediment. Paleocurrent and rock provenance evidence support the theory that many of the isopach thicks observed in the Lakota interval represent second-stage dissection of this older pediment surface. Regional drainages cut across the state, some deflected eastward by the forebulge developed in response to thrust-loading the Sevier orogenic belt. Tributaries to this through-going regional drainage network also incised into the pediment surface.