Influence of provenance and sediment supply on sandstone composition and depositional styles: Pennsylvanian upper Morrowan and Cherokee, Oklahoma
Pennsylvanian (Cherokee) fluvio-deltaic complexes prograded southward toward the Arkoma and Anadarko basins and contain channel-fill, delta-fringe and delta-plain environments. During lowstand, sediment was transported across the exposed shelf and deposited on the basin slope or floor, or redistributed as shallow-marine bars. In contrast, upper Morrowan sandstones form linear trends interpreted as valley fills and contain evidence of increased marine influence toward the top. It is proposed that drainage-basin size and paleoclimate influenced sediment supply. Cherokee fluvio-deltaic complexes were well supplied with sand derived from an extensive drainage basin with shield areas that provided a distinct metamorphic detrital compositional signature. In contrast, upper Morrow valleys were undersupplied with sand. Lowstand deposits are thin clay-clast-rich channel-lag conglomerates. The incomplete filling of valleys with sand reflects a smaller drainage basin predominantly on sedimentary rocks that weathered mostly to mud, but provided chert as an important detrital grain. Sand transported across the shelf was diluted with mud in the Morrowan Sea. During transgression, sand was trapped in the valleys, but the limited volume was insufficient to fill valleys and estuarine and marine deposits dominate the upper portions of valley fills. Wetter climate and the Wichita-Arbuckle orogenic belt possibly heightened seasonal storm intensity, facilitating Cherokee sediment transport.
AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015