9614726 Isachsen A large area of southern Arizona is underlain by a family of rocks called the Pinal Schist terrane. These rocks are poor understood, and this inhibits the regional syntheses of Precambrian tectonics. Isachsen's proposal requests funds to characterize there rocks by isotope geochemical and dating methods. The results will help establish whether the rocks of this terrane correlate to adjacent terranes, or whether they constitute a new unique crustal block. This in-turn will constrain models for the tectonic development of the SW United States.
