T he Proterozoic orogenic belt of southwestern North America provides a rare opportunity to gain insight into the evolution of continental lithosphere. The rapid formation, accretion, and stabilization of Proterozoic lithosphere; the interaction of Archean and Proterozoic lithopshere; and the subsequent modification of the crust make this area an outstanding field laboratory for the processes of lithospheric development. Proterozoic provinces (the Mojave, Yavapai, and Mazatzal) accreted to each other and to the Archean Wyoming Craton between 1.8 and 1.6 billion years ago, resulting in a belt of northeast striking provinces and boundaries (see map below). Between 1.6 and 1.4 billion years ago the terranes experienced slow, near-isobaric cooling and stabilization. From 1.4 billion years ago and on, the Proteozoic belt experienced a number of reactivation events, mostly concentrated along the northeast-striking Proterozoic province boundaries, suggesting a long-term correlation between the mantle and Proterozoic structures. It is the relationship between the mantle and the lithospheric-scale Proterozoic structures of the southwest that are the primary focus of the Continental Dynamics - Rocky Mountain project, a multidisciplinary, collaborative effort of researchers from fifteen institutions.

Scientitsts from 14 US universities and one from Germany are involved in this project. They put in place approximately 1,200 seismic instruments and 50 earthquake recording instruments stretching from Wyoming to New Mexico. The 1,200 seismometers recorded vibrations from mine blasts, smaller explosions, and the activities of specially designed vibrating trucks. This information was used to create profiles up to 30 miles deep, going right through the Earth's crust.

Funding: National Science Foundation