Abstract

Along-strike variations in sediment supply and process regime may result in different facies distributions, preservational biases, and stratigraphic architectures in shallow-marine strata. Data from a large (c. 100 km), nearly continuous outcrop belt aligned oblique to depositional strike was integrated with nearby subsurface well data and petrological analysis of distal fine-grained deposits, to analyze along-strike variations in stratigraphic architecture in a single parasequence in the upper Cretaceous Star Point Sandstone, Wasatch Plateau, central Utah, USA.

The parasequence comprises wave-dominated shoreface deposits in the southern part of the study area and represents a single episode of shoreline regression and transgression. Four progradationally stacked bedsets (BS1–BS4) in the distal deposits of the parasequence are the expression of minor variations in relative sea level, sediment supply, and/or wave climate. The four bedsets can be traced to river-dominated deltaic deposits (Panther Tongue) in the northern part of the study area. We interpret the parasequence on the scale of the Wasatch Plateau outcrop belt as the record of deposition in a regressive river- and wave-influenced delta deflected asymmetrically towards the SSW, subparallel to the regional paleo-shoreline trend, and a coeval wave-dominated strandplain. The lateral transition from river- to wave-dominated facies is attributed to the localization of a major river acting as a sediment point source in the north, with wave-induced longshore transport to the south. Our results imply that characterizing lateral facies distributions and the expression of bedsets is vital for interpreting along-strike variability in controlling mechanisms of stratigraphic architecture, and that external forcing may be recorded differently along depositional strike.