9805013 Bickford The Paleoproterozoic of southwestern United States consists of a series of accreted terranes attached to the Superior province. The assumption that these terranes are juvenile arcs and represent essentially new mantle-derived crust has had a major impact on calculations of crustal growth. However, some of these rocks contain a distinctly bimodal volcanic suite which are intruded by calcalkaline plutons. This association is more consistent with a rifting tectonic environment, bringing up the possibility of the presence of older material, not just juvenile. This project will study rocks in the Central Colorado region to explore this possibility. Results will very significant to regional reconstructions and crustal studies.
