COLLABORATIVE RESEARCH: Tectonic Reconstructions of Southwestern North America

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9725829 Farmer The precambrian and lower paleozoic continental crust of southwestern United States has been involved in extensive paleozoic, Mesozoic and Cenozoic deformation caused by a variety of plate interactions. Many large-transport faults have been proposed for these younger events, but attempts to prove or quantify them is hampered by the lack of knowledge of the original spatial distribution of the older rocks. This project will utilize a new approach to establish paleo-proximity of now separated terranes. Recent studies have identified a 1.1 by granite with a very unique Nd isotopic signature, erosion products of which can be identified in sediments deposited in the suspect terranes. Proximity to this unique source can be estimated by looking for l.1 by zircon detritus and the Nd spike in candidate sediments. Such data from several key terranes will help establish their original spatial relationship thus allowing the subsequent translations to be determined. Results are expected to assist in resolving several regional problems in the reconstruction of the southwest US craton.