This proposal seeks to characterize fluid chemistry at several sites across the Costa Rica subduction zone. Fluids will be analyzed for Si, B, Br, F, 18O, deuterium, 11B and 7Li. This information will be used to determine the temperatures of the fluid sources and constrain the low-grade metamorphic/diagenetic reactions that produce the fluids. These reactions may have implications for stick-slip behavior along the plate boundary fault. This work represents part of an effort to characterize the fluid flow and faulting behavior along an erosive subduction zone and is complementary to work currently being done on an accretionary subduction zone off of Japan. The work is critical to the completion of the objectives of IODP expeditions 334 and 344.
Broader impacts include a better understanding of fault with the potential to produce large earthquakes and, possibly, tsunamis. A graduate student will be taking part in an international collaboration, including travel to and work in a laboratory in Taiwan. The project also involves undergraduate students, including a senior thesis, incorporation of results into undergraduate classes, and presentation of results to a conference specifically designed to attract persons from under-represented groups to science.
