GEOCHEMICAL INVESTIGATION OF SEDIMENTS DERIVED FROM THE ACADIAN HINTERLAND OF THE DEVONIAN APPALACHIAN BASIN

As part of a larger investigation to characterize the Acadian hinterland of the Devonian Appalachian basin, trace element and major element analyses have been conducted on time-equivalent shales and silts along an east-west transect perpendicular to the Devonian paleo-shoreline. Samples were collected from late Frasnian and early Famennian aged rocks from 5 counties in West Virginia. Based on a paleo-shoreline reconstruction, the rocks at this location should have been derived from a single sediment source. As a result, this shoreline to basin transect was selected in order to assess the geochemical variability of sediment derived from a single source area with in the central Appalachian Basin.

Zr/Sc and Th/Sc ratios from the rocks in this investigation demonstrate a trend of decreased sedimentary sorting and increased geochemical uniformity with proximity to the shoreline. The range in both Zr/Sc and Th/Sc increases with distance from the shoreline suggesting a decrease in the amount of detrital zircon present and possibly an increase in the contribution of other sediment sources (i.e. lateral sediment transport). Y/Ni, Cr/V and Th/U ratios indicate the dominance of an upper-crustal type source similar to other like-aged deposits in the basin.

Based on the geochemical results of this investigation, the Acadian hinterland in the central Devonian Appalachian basin is likely composed of recycled sedimentary component and likely Greenvillian aged source rocks. Furthermore, trace element data indicate that sediment located near the Devonian shoreline is most representative of the local source, with increasing influence from lateral transport from east to west.