Preliminary Analysis of Volcanic Sediment Sources in Copeland Creek Sonoma County, California

Abstract

Copeland Creek is a small tributary of the Russian River watershed that drains areas underlain by volcanic rocks of the Sonoma Volcanics. This project investigates the volcanic provenance of Copeland Creek sediments through detailed geological mapping and analysis of volcanic material along the channel. • Field mapping focused on identifying lithologic units, tracking the spatial distribution of volcanic materials, and constraining source regions Sediment samples were collected at multiple locations outside of Fairfield Osborn Preserve to capture downstream changes in composition. • Samples were analyzed using grain size measurements and visual identification of lithic fragments, with emphasis on distinguishing volcanic units. The abundance and distribution of volcanic material were quantified and used to construct a provenance map, identifying dominant source areas and trends in volcanic sediment contribution. • Results highlight consistent volcanic signatures within the watershed and constrain the likely source region to the north of distinct volcanic materials observed in Copeland Creek sediments.

Results

Key Terms: datasonde,  Copeland Creek, Russian River watershed, Fairfield Osborn Preserv, Sonoma Volcanics, geological mapping, rhyolitic tuff, perlite, volcanic glass