Subdivision of Wilcox group (sabinian) argillaceous sediments using particulate organic matter

Abstract

Abstract Maceral analysis of a thick, argillaceous dominated‐section from the Wilcox Group of western Louisiana revealed that these litho‐logically homogeneous sediments can be differentiated based on maceral spectra. Analysis of the data using quantitative univari‐ate and multivariate statistical techniques resulted in the definition of eight maceral facies. Comparison of the maceral facies with those from modern environments, coupled with a lithostratigraphic model, resulted in a refined paleoenvironmental interpretation: the sediments in the studied section were deposited on the Sabinian continental shelf to the upper continental slope environments and show evidence of deposition influenced by a fluvial plume associated with the western lobe of the Holly Springs delta complex and correlative Upper Wilcox delta complexes. Based on maceral facies, the stratigraphic section can be subdivided into an upper heterogeneous unit and a lower homogeneous unit. The upper unit reflects shallower water depths and more oxic bottom conditions than the lower unit. Maceral facies present in the upper unit may reflect either changing degradational environmental conditions, or may be a result of a change in the source of the terrestrial (phytoclastic) material. The organic matter is comprised predominantly of terrestrial macerals indicating a Type III kerogen. Thermal Alteration Indices (TAI) range from 2‐ to 2, indicating that the material is marginally mature.