RUI: Collaborative Research: Early Cenozoic basin development in the southwestern US: a record of extensional collapse following subduction of an oceanic plateau?

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Subduction zones represent some of the most tectonically active regions on earth. Changes in the angle of the downgoing plate can control volcanism, faulting, and basin development in the overlying continental crust. The Maniobra and Goler Formations, exposed in the Mojave Desert in southern California, provide evidence for the development of extensional basins on the overriding continental plate related to low-angle subduction in Late Cretaceous to Eocene time (~80-50 million years ago). This research will test the hypothesis that Late Cretaceous extension resulted in the development of the Maniobra and Goler Basins, while simultaneously introducing more than 50 undergraduate and 2 Masters students to the techniques of basin analysis. The field sites in the Mojave Desert, located within 3 hours of Los Angeles, provide a natural laboratory to train the next generation of geoscientists. Students from a Hispanic-serving institution will learn modern geologic techniques, such as geologic mapping, geochronology, paleomagnetism, and thermochronology, that can be applied to their graduate and post-graduate careers. Analytical data from this research will be made available on community databases, and results of the proposed research will be used to construct a publicly-available online learning module.Recent tectonic models of the southwestern US Cordillera have invoked the subduction of an oceanic plateau, the conjugate Shatsky Rise, as a driver of slab flattening, subduction erosion and arc cessation in Late Cretaceous to Eocene time. Subduction, and subsequent passage of the plateau, likely promoted extension and associated regional paleogeographic changes, such as basin development and block rotations. This study targets the Goler and Maniobra Formations, which are the only Late Cretaceous to Eocene basinal strata located along the interpreted subduction pathway. This research will test the hypothesis that gravitational collapse in the wake of plateau subduction was widespread across the Mojave region in the Late Cretaceous to early Cenozoic and led to the development of supra-detachment basins and the exhumation of relict subduction complexes. This research will incorporate new mapping of stratigraphic and structural relationships, combined with magnetostratigraphy, detrital zircon provenance analysis, and basement and detrital thermochronology. This data will constrain the timing and duration of basin formation and enable the evaluation of different tectonic models of basin development. New basin analysis results from the Late Cretaceous to Eocene Goler and Maniobra Formations will provide a crucial link between plateau subduction processes and related surface deformation and will highlight the complexity of tectonic evolution along a highly segmented margin over time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.