Rhyolite characterization and distribution in central Alaska

Abstract

Fine grained volcanic rocks are common in lithic assemblages of interior Alaska and are amenable to geochemical characterization using a variety of analytical techniques. Our study focuses on rhyolite with the intent of identifying and delineating geochemical groups that may correlate to specific geological source areas. PXRF technology was used to analyze 676 rhyolite artifacts from 123 sites in interior Alaska. Our preliminary results recognize ten distinct geochemical groups that appear to correlate with distinct geological sources. While geological origins of eight of the ten groups identified remain unknown, two geological sources have been pinpointed, one (represented by Group H) is located in the central Alaska Range and the second (Group G) is in the Talkeetna Mountains. The provisional framework of geochemical variation among tool quality rhyolite sources in this region is an important first step toward a more robust understanding of prehistoric landuse in interior Alaska.