Basalts from the Louisville Seamount Chain (cores) Targeted Locus (Loci)

Starting in the 1980''s, microbiologists accompanying Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) expeditions have documented the presence of microbial life in deeply buried sediments and the basaltic basement (Fisk et al., 1998; Parkes et al., 1994). Active microbial life has been detected in sediments as far below the seafloor as 1626 m (Roussel et al., 2008), and the introduction of molecular biology into marine ecology led to great advances in our understanding of microbial life below the seafloor (Biddle et al., 2008; Cowen et al., 2003; Inagaki et al., 2006; Mason et al., 2010). However, the majority of the microbiology performed on ODP and IODP expeditions thus far concentrated on sediments (for example, ODP Leg 201 to the Peru Margin), with the notable exception of expeditions to the Juan de Fuca Ridge (Cowen et al., 2003; Lever et al., 2006) and the Atlantis Massif (Mason et al., 2010). Additionally, previous expeditions that did include basement sampling tended to focus on young sites - the Juan de Fuca Ridge is 3.5 Ma and the Atlantis Massif is <2 Ma. Evidence from stable isotopes (Rouxel et al., 2008) and microbial fossils (Fisk et al., 1998) suggest that there is a subsurface biosphere that may be active in older basement rocks as well. One of the objectives of Integrated Ocean Drilling Program (IODP) expedition 330, Louisville Seamount Trail, was to sample and learn about the subsurface biosphere in the Louisville Seamount Chain (LSC). This seamount chain consists of submerged, inactive volcanoes formed at the Louisville hotspot, one of three primary hotspots in the Pacific Ocean (Courtillot et al., 2003). The drilled seamounts range in age from 65 to 77 Ma (Koppers et al., 2004) and basement composition at all three consists of alternating layers of massive lava flows and basaltic breccia.