Stern The Arabian-Nubian Shield (ANS) in northeast Africa and western Arabia contains a large portion of Earth's Neoproterozoic (1000-544 Ma) juvenile crust. This crust formed by processes indistinguishable from those of modern plate tectonics, as witnessed by well-defined tectonostratigraphic terranes separated by ophiolite-decorated sutures. The ANS is therefore ideal for testing the central controversy facing our understanding of continental crust formation: the importance of magmatic contributions at convergent margins vs. those of mantle plumes, either as accreted oceanic plateaux or as underplated material. This project will test the viability of the plume model for continental growth in the ANS by focusing on the origin and evolution of the terranes adjacent to the Bi'r Umq suture in western Saudi Arabia. The primary objective is to combine locally detailed structural, lithostratigraphic, and petrological information with comprehensive geochemical, isotopic, and geochronological constraints on the tectonic setting and source regions of major volcanic and magmatic units. Intellectual Merit: The proposed research promises to contribute fundamentally to scientific understanding of the mechanisms and timing of continental crust formation in the Neoproterozoic, with significant implications for modern processes. Broader Implications: This project was developed by and for a doctoral student and so is a confluence of research and education. Understanding Neoproterozoic crustal growth has important implications for understanding global atmospheric, hydrospheric, and biospheric changes during this time, and so will contribute to understanding Earth systems and processes. The results of this study will also contribute to the MARGINS "Rupturing Continental Lithosphere" experiment, as the opening of the Red Sea (a MARGINS focus site) is largely controlled by reactivation of Precambrian structures such as the Bi'r Umq suture. The project also promotes international collaboration between scientists from the U.S. and the newly formed Saudi Geological Survey.
