Intellectual Merit: This proposal is to conduct a number of hydrogeologic experiments in ocean crust on the east flank of the Juan de Fuca Ridge in the Northeast Pacific Ocean. The aim of the experiments is to study the movement of fluids, chemicals and microbes within the ocean crust between drill holes completed by the Integrative Ocean Drilling Program. The work will be the first to run a long-term cross-drill-hole test in the ocean crust. One and two years following the Integrative Ocean Drilling Program expedition in 2010, the down hole instruments will be serviced and samples collected from multiple depths in the hole. Three-dimensional numerical modeling will evaluate how flow works within the oceanic crust. Taken together, the proposed work will constrain heat transport, chemical transport, and sub-seafloor microbiology making the results of value to many communities. Broader Impacts: This project will train graduate and undergraduate students and will leverage off of an existing education and outreach program already in place for the Integrative Ocean Drilling Program expedition in 2010.
PI-Team: Lead PIs: Andrew Fisher (UCSC) and Geoff Wheat (Moss Landing/MBARI/U of Alaska-Fairbanks) Co-PIs Becker, Keir (U of Miami) Clark, Jordan (UCSB) Cowen, James (U of Hawaii) Edwards, Katrina (USC) Orcutt, Beth (Bigelow Marine Lab) Rappé, Mike (U of Hawaii) UCSB Students Nicole Neira (MS, UCSB 2014) Menso de Jong (Ph.D., expected 2016) Objective: The primary objective of UCSB’s portion is to understand the hydrologic properties of the upper ocean (3.5 Ma) crust on the eastern flank of the Endeavor segment of the Juan de Fuca Ridge using a multi-borehole tracer test. The work is being conducted to support heat flow and microbiology measurements other PI groups are making. Much of the work has focused on the development of new technologies for future studies. Main results: It worked. We were able to detect tracer up to 550 m away from the injection hole showing that the hydrology of the upper ocean crust is very complicated and best explained as a dual porosity system. I expected to never see the tracer away from the injection hole but the gods smiled upon us and Nicole was able to get a great thesis out of this study and graduate on time at the end of 2014. She is now working for the sanitation district in Calabasas, CA. Future work: This past summer, I collected the final samples that Menso, who enrolled at UCSB in January 2015, will be working on for his Ph.D. thesis. I expect that he will interpret the tracer data more quantitatively so that hydrologic parameters can be estimated for the upper ocean crust on the flank of the Juan de Fuca Ridge.
