The submarine magmatic record of the transition from arc magmatism to continental rifting and seafloor spreading at the Gulf of California MARGINS focus site

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The study will improve the understanding of processes that accompany the transition from continental to oceanic crust, and the Gulf of California provides one of the most accessible locations for studying this transition. Recent imaging of the Gulf of California reveals new information about the rifting history and transition to sea floor spreading. However, only direct sampling will be able to provide the age models, lithology and chemistry as much of the Gulf seafloor lacks clear magnetic anomaly signatures. An initial cruise of dredging by the PIs recovered a variety of rock types related to older continental crust, the preexisting arc and synrift volcanism, including older basalts. Placing these samples in geologic framework will require the type of detailed sampling planned for an ROV sampling and multibeam bathymetry cruise. The research will significantly advance our understanding of the magmatic history of the Gulf of California rift system, and provide insights regarding several significant issues: how the source of the volcanic rocks has varied laterally and temporally and how this relates to processes in the mantle; and how the volcanism and magmatism has affected the rift kinematics. The broader impacts include strong international collaboration; development of a project web site for research dissemination to community and public, links to the San Diego Museum, and training of two graduate students. The project will collect an important suite of samples for the use of the broader MARGINS community.