Geology and venting characteristics of the Mothra hydrothermal field, Endeavour segment, Juan de Fuca Ridge

The 500-m-long Mothra hydrothermal field is the largest venting site in are al extent on the Endeavour segment of the Juan de Fuca Ridge. Within this f ield, there are at least five actively venting sulfide complexes, spaced 40 to 200 m apart along a trend of 020. The clusters are composed of multiple steep-sided pinnacles that rise up to 20 m above the seafloor. Most of the sulfide structures are awash in diffusely venting fluids (30-200 degreesC) that support rich and diverse macrofaunal and microbial communities. Isola ted black smoker chimneys vent 302 degreesC fluids. The linear arrays of su lfide complexes delineate a zone of active faulting near the western wall o f the axial valley. This fault network serves as the conduit for the rising fluids.