Oxygen uptake during marine diagenesis of fresh volcanic material

Arc volcanism generally occurs in close proximity to the oceans. In such cases, >90% of erupted volcanic material may be deposited in the ocean by various means. Bio- geochemical effects of volcanic ash in surface seawater have previously been addressed, but the majority of submarine volcanic deposits are delivered directly to the sea floor. These rapidly emplaced deposits of fresh volcanic material can blanket many km2 of seafloor. Little is known of the early diagenesis of this material, but it is likely to have a significant regional biogeochemical effect. The ongoing eruption of Montserrat, Lesser Antilles, provides an excellent case study for these processes. Microelectrode profiles taken in cores from close to the island show dissolved oxygen penetration depths ranging from