| Description |
Five detailed measured sections (each >175 m), two outcrop gamma ray logs, 2100 paleocurrent measurements, and detailed facies interpretation of high-resolution composite photographs were used to document the vertical and lateral variations of the alluvial architecture of the John Henry Member of the Upper Cretaceous Straight Cliffs Formation (southwest Kaiparowits Plateau, southern Utah). These data interpretations correlate to 24 measured sections and logged cores from previous work in fluvial and paralic facies in the John Henry Member and complement previous correlation to marginal marine facies ~60 km basinward of the study area. The proximal fluvial strata of the ~230 m-thick member is divided into seven depositional units (DU) from stratigraphic base to top: DU-0, tidally-influenced channel belts; DU-1, highly amalgamated, laterally accreting channel belts with tidally-influenced channel belts in the upper section; DU-2, laterally extensive (>1.2 km wide), laterally accreting channel belts; DU-3, isolated channel belts (<150 m) embedded within thick floodplain muds; DU-4, clusters of laterally restricted (<500 m), laterally accreting channel belts and isolated channel belts; DU-5, laterally extensive, locally amalgamated, downstream accreting channel belts; and DU-6, highly amalgamated, downstream accreting channel belts. An unconformable surface at the base of DU-1 demonstrates a basinward shift in facies and is interpreted to represent erosion during base level fall. |
