Project: Microbiology and biogeochemistry of Juan de Fuca Ridge flank borehole fluids

Extracted from the NSF award abstract:

Hydrothermally heated fluids circulate everywhere within the permeable basement rock of the upper ocean crust, providing warm temperatures and chemical gradients that support a deep subsurface marine biosphere. The volume of oceanic lithosphere habitable by microbial life is thought to be a substantial portion of the Earth’s crust - extending thousands of meters below the seafloor. During expeditions from 2008 to 2014 we repeatedly sampled basalt-hosted, deep subseafloor crustal fluids from four different boreholes drilled along the Juan de Fuca Ridge flank in the Northeast Pacific Ocean using pumps and samplers capable of collecting whole water and filtered particulates in situ. The instrumented boreholes, sitting at 2600 m depth, penetrate ~100 to 260 m of bottom sediments and another ~48 to 300 m of igneous basement where they tap into hot (up to 65 degrees C), anoxic fluid within Earth’s largest deep subsurface aquifer. Nearby bottom seawater and sediments were sampled as controls. Associated data sets include small subunit ribosomal RNA and functional gene amplicon DNA sequences, metagenome sequences, single cell genome sequences, direct counts of microbial cells and viruses, and a wide range of associated biogeochemical measurements including dissolved gases, particulate and dissolved organic carbon, sulfate, nitrate, and others.