Recent cruise results from the Lau back-arc basin documents hydrothermal fluid compositions that differ greatly from the well-studied vents along the global Mid-Ocean Ridge (MOR) system. Moreover, systematic local and regional variations in fluid composition within this back-arc environment have also been observed. Back-arc hydrothermal systems are likely controlled by a number of unique geologic variables, including the presence of felsic volcanic rocks in the subsurface and the much greater likelihood that fluids of magmatic origin contribute to fluid composition. It is these complex geologic factors that likely account for both the large differences between MOR and back-arc hydrothermal fluids and the regional variations in fluid composition observed within a single back-arc system. As a consequence of these complexities, models for the origin and evolution of hydrothermal fluids in back-arc environments are, at present, poorly constrained because the chemical processes associated with the reaction of seawater-derived hydrothermal fluids and volcanic rocks of felsic composition have not been systematically studied. This study is a laboratory investigation of the specific chemical processes that occur during the interaction of seawater-derived hydrothermal fluids with rocks of andesitic, dacitic, and rhyolitic compositions. These experiments will provide fundamental information necessary to identify key processes that regulate fluid chemistry in back-arc hydrothermal systems. The Lau Basin has been designated as a RIDGE Integrated Study Site and the proposed research will further our understanding of this complex hydrothermal environment.
This NSF-RUI investigation is a novel integration of research and education through a laboratory-based collaboration between the Woods Hole Oceanographic Institution (WHOI) and Bridgewater State College (BSC). The project will allow Dr. Saccocia to conduct laboratory-based research relevant to the RIDGE initiative and thereby participate in cutting-edge research that would not otherwise be possible without a WHOI collaborator. Second, the research agenda will form the basis of an undergraduate research course in Earth Science at BSC. This course will enroll anywhere from 5-10 students and will be offered each spring semester over the three year grant period. Each student will 1) read relevant articles from the peer-reviewed literature to learn about the background of the proposed research, 2) actively participate in the analytical work (at WHOI) associated with the experiments by working in teams, 3) interpret the results as the data is generated, 4) write reports describing the significant scientific results from their analytical team, and 5) contribute to the production of a single manuscript that emulates the format of a journal article. Thus, this RUI grant will provide a unique undergraduate research experience for up to 30 geology students at BSC, making them more competitive applicants to high quality graduate programs and enhancing the likelihood that they will pursue careers in the geosciences. In addition to the research course, this project provides an opportunity for up to 6 undergraduate students at BSC to perform more intensive research in the hydrothermal laboratory at WHOI during the summer months.
