KL6

From Magma to Microbe: The Subsurface Biosphere of Guaymas Basin

Andreas Teske1, Paraskevi Mara2, David Geller-McGrath2, Diana Bojanova3, John E. Hinkle1, Gustavo A. Ramírez4, Daniel Lizarralde2, Yuki Morono5, Virginia P. Edgcomb2

  1. Dept. of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, USA 
  2. Dept of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, USA
  3. Dept of Earth Sciences, University of Southern California, Los Angeles, CA, USA
  4. Dept of Biological Sciences, California State University, Los Angeles, CA, USA
  5. Kochi Institute for Core Sample Research, Institute for Extra-cutting-edge Science, and Technology Avantgarde Research (X-STAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe, Nankoku, Kochi, Japan

The Guaymas Basin in the Gulf of California is a young marginal rift basin characterized by active seafloor spreading and hydrothermal venting. High plankton production in surface waters and terrigenous sedimentation from the Sonoran mainland combine to rapidly deposit organic‐rich sediments, which are permeated by extensive thermal and geochemical gradients. Deeply emplaced hot volcanic sills extend across the basin and alter the surrounding sediments by transforming buried sedimentary carbon into hydrocarbons, especially methane. The rapid mobilization and re-injection of these hydrocarbons into the biosphere impact the carbon cycle of the basin and provide a model system that illuminates climate perturbations. Subsurface microbial populations potentially intercept and process these hydrothermally generated and mobilized carbon sources, but their depth extent, cell numbers and phylogenetic composition are controlled by the steep geothermal gradients that are characteristic of Guaymas Basin. Here I will provide an overview on this fascinating hydrothermal geo-ecosystem, and on IODP drilling expedition 385 to Guaymas Basin (Sept. 16 to Nov. 16, 2019) with JOIDES Resolution.  The expedition scientists and drilling crew recovered 4 km of sediment core and >350 m of sill core from eight drilling sites across Guaymas Basin, measured geothermal gradients in diverse settings ranging from recently emplaced hot sills to cold seep sites, and probed the highly diverse biogeochemistry and microbiology of the Guaymas Basin subsurface sills and sediments. Highlights will be presented as appropriate for recently concluded and for ongoing investigations.

[Research in the lab of the PI has been supported by IODP, NSF Biological Oceanography, and NASA Exobiology.]