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Project Progress

Two ongoing eruptions were discovered in the NE Lau Basin during a cruise in November 2008. Understanding the early stages of magmatism and hydrothermal activity influenced by these magmatic fluids is essential to understanding the evolution of these hydrothermal systems. In addition, the ability of macro- and micro- fauna to colonize these new sites may rely on the evolutionary state of these systems. A response cruise, including the remotely operated vehicle, JASON, was mounted in May 2009 to investigate the eruptions. The eruption at West Mata was still on going, providing spectacular visuals of explosive eruptive activity and unprecedented opportunities to sample rocks and fluids associated with nascent deep sea floor eruptions.

Organic carbon (TOC) and OC components (e.g., amino acids) in hydrothermal vent fluids and plumes provide key biogeochemical indicators of the state of the local subsurface biosphere, reflecting both recent historic and contemporary processes. Dissolved organic carbon (DOC) should be depleted, relative to bottom seawater, in low temperature (<100oC) diffuse effluents associated with newly erupted lava flows, but should increase in concentration as subseafloor communities develop with time. Basalt surfaces scavenge DOC, so new basalts should be a sink for seawater DOC. In established hydrothermal systems with a well developed subsurface microbial community, DOC and labile OC compounds such as amino acids, are depleted in high temperature (>100oC) effluents, but enriched in low temperature (<100oC), diffuse vent effluents. Hence, the export of DOC and labile organics from new lava flows should be exceedingly low initially, but increase over time with increasing microbial activity. The well-constrained time stamp of these new eruptions provide an unprecedented opportunity to observe the transition of a new lava flow from initial organic carbon sink to eventual OC source, in conjunction with parallel time series observations of changes in microbial community parameters, and geochemical fluxes.