Controls, characterization and small scale chemical variations of a Karst system: A geochemical assessment of Tuscarora Creek watershed, West Virginia

Tuscarora Creek watershed is located in the Appalachian Great Valley in Berkeley County, West Virginia. Thirteen springs and seven creek locations were sampled to evaluate spatial and temporal variability in major ion geochemistry. The controlling chemical signature was carbonate dissolution; distinctions could not be made between carbonate units and little evidence was seen for the recharge from adjacent clastic rocks. The springs in the upper watershed had greater temporal variability that may be due to enhanced transmissivity associated with a creek-parallel thrust fault. Discharge data indicate the creek is supplied directly from ground water (>50%) as well as from the springs. Geochemically, the springs and creek are similar except that the creek samples typically have a lower partial pressure of CO2 and are closer to equilibrium with calcite. The distinction may be partly attributed to degassing when ground water reaches atmospheric conditions.