STREAM SEDIMENT COMPOSITION IN A WATERSHED OF VARIABLE LITHOLIGIES: FATE OF CO, CR AND NI RELEASED FROM WEATHERED DUNITE.

WILLIAMS, Carrie L., Department Geological Sciences, Clemson University, Clemson SC 29634-1908, clwilli@clemson.edu; ANDERSEN, Brannon C., Department of Earth and Environmental Sciences, Furman University, Greenville SC 29613-0440; DAVIES, Brian E., Department Geological Sciences, Clemson University, Clemson SC 29634-1908

The transport and fate of heavy metals in fluvial systems is important in both geochemical and pollution studies. The Buck Creek watershed in western North Carolina contains one of the larger outcrops of peridotite in the state. The ultramafic body and associated amphibolite is, through weathering, a source of Co, Cr and Ni for the fluvial sediments which are otherwise derived from the country rock (hornblende and mica gneisses). The watershed may therefore serve as a model for the fate and transport of metals in fluvial systems.

Bank soils and channel bed sediments have been collected from Buck Creek starting in the country rock, crossing onto the mafic/ultramafic complex, and re-entering the gneiss. Data are presented for total major and minor elements of rock, soil and stream bed sediment. Normalization of the data on the oxides of Al and Ti allows for the quantification of trace metal gains and losses during weathering and sediment transport. Other properties of the data set reveal the influence of each rock type on sediment composition. Metal content of sediments along the stream illustrate the extent of the influence of the dunite source downstream. Data are also presented for the abundance of chromite as a heavy mineral physical tracer of dunite-derived sediment and through a chemical phosphate test, the abundance of monazite as a similar tracer for gneiss.