Europole Mer : research consortium on marine science and technology in Brittany

It is now well recognized that seafloor hydrothermal systems support diverse and unique biological communities capable of using dissolved chemical species, such as Iron (Fe), as well as mineral substrates as sources of metabolic energy. The Loihi Seamount hydrothermal field, near Hawaii, provides an important example of deep-sea environments where both chemical and biological oxidation of Fe can occur simultaneously and provides an ideal system in which to test hypotheses on biotic vs. abiotic origin of seafloor iron-oxide deposits preserved in the geological record. A total of 16 discrete ROV dives (Jason2) were conducted within the Loihi Summit area over four cruises between 2006 and 2009. Here, we applied Fe isotope systematics of hydrothermal vent fluids and Fe-oxide precipitates to study biogeochemical cycling of iron and provide new constraints on the formation mechanisms and evolution of microbial mats at the seafloor.