International Ocean Discovery Program; Expedition 385 scientific prospectus; Guaymas Basin tectonics and biosphere; feedbacks between continental rifting, magmatism, sedimentation, thermal alteration of organic matter, and microbial activity

Online Access: Get full text
doi: 10.14379/iodp.sp.385.2018
Author(s): Teske, Andreas; Lizarralde, Daniel; Höfig, Tobias W.
Author Affiliation(s): Primary:
University of North Carolina-Chapel Hill, Department of Marine Sciences, Chapel Hill, NC, United States
Woods Hole Oceanographic Institution, United States
Texas A&M University, United States
Source: Scientific Prospectus (International Ocean Discovery Program), Vol.385, 30p. Publisher: International Ocean Discovery Program, College Station, TX, United States. ISSN: 2332-1385
Note: In English. 82 refs.
Summary: The Guaymas Basin in the Gulf of California is a young marginal rift basin characterized by active seafloor spreading and rapid deposition of organic-rich sediments from highly productive overlying waters. The high sedimentation rates in combination with an active spreading system produce distinct oceanic crust where the shallowest magmatic emplacement occurs as igneous intrusion into overlying sediments. The intrusion of magma into organic-rich sediments creates a dynamic environment where tightly linked physical, chemical, and biological processes regulate the cycling of sedimentary carbon and other elements, not only in a narrow hydrothermal zone at the spreading center but also in widely distributed off-axis venting. Heat from magmatic sills thermally alters organic-rich sediments, releasing CO2, CH4, petroleum, and other alteration products. This heat also drives advective flow, which distributes these alteration products in the subsurface and may also release them to the water column. Within the sediment column, the thermal and chemical gradients created by this process represent environments rich in chemical energy that support microbial communities at and below the seafloor. These communities may play a critical role in chemical transformations that influence the stability and transport of carbon in crustal biospheres. Collectively, these processes have profound implications for the exchange of heat and mass between the lithosphere and overlying water column and may determine the long-term fate of carbon accumulation in organic-rich sediments. The fate of carbon deposited in Guaymas Basin, throughout the Gulf of California, and more broadly within similar marginal seas throughout the world, depends on the relative efficiencies of interacting physical, chemical, and microbial processes, some working to sequester carbon and others working to release carbon back to the ocean and the atmosphere. Drill core samples from Expedition 385 to Guaymas Basin will enable us to study these processes, their interactions, and their ultimate effects on carbon cycling. Samples obtained from scientific drilling are crucial to these goals, which include: - Quantifying the sedimentary and elemental inputs to the system through time and their variation with oceanographic and climatic conditions; - Sampling igneous sills and the surrounding sediments to determine the products and efficiency of alteration and key hydrologic factors such as sediment type, faulting, and permeability evolution; and - Studying subsurface microbial communities hosted by alteration products to determine their efficiency at capturing carbon-bearing alteration products and to further our understanding of the conditions that limit life in the deep biosphere.
Year of Publication: 2018
Research Program: IODP2 International Ocean Discovery Program
Key Words: 16 Structural Geology; 20 Geophysics, Applied; Basins; Boreholes; Carbon; Cores; Drilling; East Pacific; Ecosystems; Geophysical methods; Geophysical profiles; Geophysical surveys; Guaymas Basin; Gulf of California; International Ocean Discovery Program; Marginal basins; Marine drilling; Marine sediments; Mexico; Microorganisms; North Pacific; Northeast Pacific; Pacific Ocean; Planning; Rift zones; Sea-floor spreading; Sediments; Seismic methods; Seismic profiles; Surveys; Tectonics
Coordinates: N270000 N280000 W1111000 W1120000
Record ID: 2018094264
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.