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Expedition 370 summary

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      Abstract

      International Ocean Discovery Program (IODP) Expedition 370 explored the limits of the biosphere in the deep subseafloor where temperature exceeds the known temperature maximum of microbial life (~120°C) at the sediment/basement interface ~1.2 km below the seafloor. Site C0023 is located in the protothrust zone in the Nankai Trough off Cape Muroto at a water depth of 4776 m, in the vicinity of Ocean Drilling Program (ODP) Sites 808 and 1174. In 2000, ODP Leg 190 revealed the presence of microbial cells at Site 1174 to a depth of ~600 meters below seafloor (mbsf), which corresponds to an estimated temperature of ~70°C, and reliably identified a single zone of elevated cell concentrations just above the décollement at around 800 mbsf, where temperature presumably reached 90°C; no cell count data was reported for other sediment layers in the 70°–120°C range because the detection limit of manual cell counting for low-biomass samples was not low enough. With the establishment of Site C0023, we aimed to detect and investigate the presence or absence of life and biological processes at the biotic–abiotic transition utilizing unprecedented analytical sensitivity and precision. Expedition 370 was the first expedition dedicated to subseafloor microbiology that achieved time-critical processing and analyses of deep biosphere samples, conducting simultaneous shipboard and shore-based investigations. Our primary objective during Expedition 370 was to study the relationship between the deep subseafloor biosphere and temperature. We comprehensively studied the controls on biomass, activity, and diversity of microbial communities in a subseafloor environment where temperatures increase from ~2°C at the seafloor to ~120°C and thus likely encompasses the biotic–abiotic transition zone. This included investigating whether the supply of fluids containing thermogenic and/or geogenic nutrient and energy substrates may support subseafloor microbial communities in the Nankai accretionary complex. To address these primary scientific objectives and questions, we penetrated 1180 m and recovered 112 cores of sediment and across the sediment/basalt interface. More than 13,000 samples were collected, and selected samples were transferred to the Kochi Core Center by helicopter for simultaneous microbiological sampling and analysis in laboratories with a super-clean environment. In addition to microbiological measurements, we determined the geochemical, geophysical, and hydrogeological characteristics of the sediment and the underlying basement and installed a 13-thermistor sensor borehole temperature observatory into the borehole at Site C0023.

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      Microbial diversity in the deep sea and the underexplored "rare biosphere".

      The evolution of marine microbes over billions of years predicts that the composition of microbial communities should be much greater than the published estimates of a few thousand distinct kinds of microbes per liter of seawater. By adopting a massively parallel tag sequencing strategy, we show that bacterial communities of deep water masses of the North Atlantic and diffuse flow hydrothermal vents are one to two orders of magnitude more complex than previously reported for any microbial environment. A relatively small number of different populations dominate all samples, but thousands of low-abundance populations account for most of the observed phylogenetic diversity. This "rare biosphere" is very ancient and may represent a nearly inexhaustible source of genomic innovation. Members of the rare biosphere are highly divergent from each other and, at different times in earth's history, may have had a profound impact on shaping planetary processes.
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        • Record: found
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        Prokaryotes: The unseen majority

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          • Record: found
          • Abstract: not found
          • Article: not found

          A model for the motion of the Philippine Sea Plate consistent with NUVEL-1 and geological data

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            Author and article information

            Journal
            10.14379/iodp.proc.370.2017
            Proceedings of the International Ocean Discovery Program
            International Ocean Discovery Program
            2377-3189
            23 November 2017
            10.14379/iodp.proc.370.101.2017

            This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

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            Self URI (journal page): http://publications.iodp.org/

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