THE SOURCE-TO-SINK UPPER DEVONIAN SYSTEM OF THE ACADIAN FORELAND BASIN: INSIGHTS FROM THE GORDON SAND OF THE VENANGO GROUP OF WEST VIRGINA

The Upper Devonian coarse-grained clastic succession that infilled the Acadian foreland basin of WV preserves a source-to-sink system that is generally regarded as a consequence of maximum basinward progradation of synorogenic detritus. Exposed in the Alleghany fold-thrust belt of eastern WV, this succession includes marine sandstones and shales (Canon Hill Fm.) overlain by redbed terrestrial facies (Rowlesburg Fm.). To the west, these Hampshire Group units are correlative to marine strata of the Venango Group in the subsurface of central WV. Further westward, these units transition into marine shales of the Ohio Shale, including the Chagrin Shale and possibly the organic-rich Cleveland Member of NE OH. The Gordon Sand of the Venango Group has been extensively drilled across WV, offering an opportunity to generate a high-resolution stratigraphic correlation, with which to model sediment export and accumulation as a response to tectonic, climatic, and biological drivers. We examined 10 Gordon Sand cores from 2 fields in central WV that are ~10 miles apart. Analysis of 4 cores from the Jacksonburg-Stringtown field reveals 7 lithofacies: pebble-granule conglomerate, conglomerate-sandstone interbeds, sandstone with granules/pebbles, fine- to medium-grained sandstone, mudstone with sand laminae, interlaminated siltstone-mudstone, and dark gray mudstone. In contrast, the 6 cores from the Wileyville field mainly contain sandstone and dark gray mudstone, with rare sandstone with granules/pebbles, indicating a more distal depositional setting. Preliminary hand-held XRF analysis of mudstones of a Wileyville field core indicates enrichment in Co, suggesting anoxia was induced through the decay of organic material produced from primary biological productivity, possibly akin to the formation of Mediterranean sapropels. These mudrocks occur as thin- to medium-bedded intervals with sharp basal and upper contacts, interbedded with generally well sorted, fine-grained sandstone. Further work to integrate elemental composition information to correlate Gordon Sand may be able to reconstruct a process-based model for mudrock deposition that is linked to changes in sedimentation patterns driven by eustasy, tectonism or possibly some biogenic driver during Late Devonian time.