WHAT IS THE NATURE OF THE CRUST IN THE NORTHERN GULF OF CALIFORNIA AND SALTON TROUGH?

The nature of the crust in the northern Gulf of California and Salton Trough has been debated for decades. Existing models include an oceanic crust, transitional crust (stretched continental crust with magmatic intrusions), and continental crust, all underlying a layer of metasediments. Recent geophysical surveys that collected seismic reflection and refraction data have not resolved this debate, but provide constraints on sediment thickness and Moho depth that allow us to use potential field data to find the nature of the crust. We chose one transect that crosses the Wagner Basin region in the northern Gulf, and three transects that cross the Salton Trough. For all transects, a series of models was built with different crustal compositions, and corresponding gravity anomalies were calculated. In all transects, we find that the models in which stretched continental crust is overlain by a layer of metasediments and sediments, fit the gravity data best. This finding has consequences for surface heat flow (which is locally extremely high) and magmatism in the northern Gulf. We provide an explanation for both.