International Ocean Discovery Program; Expedition 366 preliminary report; Mariana convergent margin and South Chamorro Seamount; 8 December 2016 to 7 February 2017

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doi: 10.14379/
Author(s): Fryer, Patricia B.; Wheat, C. Geoffrey; Williams, Trevor; Albers, Elmar J.; Bekins, Barbara; Magalhaes, Vitor; Debret, Baptiste P. R.; Deng Jianghong; Dong Yanhui; Eickenbusch, Philip; Frery, Emanuelle A.; Ichiyama, Yuji; Johnson, Kevin; Johnston, Raymond M.; Kevorkian, Richard T.; Kurz, Walter; Mantovanelli, Simone S.; Menapace, Walter; Menzies, Catriona D.; Michibayashi, Katsuyoshi; Moyer, Craig L.; Mullane, Kelli K.; Park, Jung-Woo; Price, Roy E.; Ryan, Jeffrey G.; Shervais, John W.; Sissmann, Olivier J.; Suzuki, Shino; Takai, Ken; Walter, Bastien; Zhang Rui
International Ocean Discovery Program, Expedition 366 Scientists, College Station, TX
Author Affiliation(s): Primary:
University of Hawaii at Manoa, Hawaii Institute of Geophysics and Planetology, United States
University of Alaska at Fairbanks, United States
Texas A&M University, United States
University of Bremen, Germany
U. S. Geological Survey, United States
Instituto Portugues do Mar e da Atmosfera, Portugal
University of Cambridge, United Kingdom
University of Science and Technology of China, China
State Oceanic Administration, Second Institute of Oceanography, China
Eidgenössische Technische Hochschule Zürich, Switzerland
CSIRO, Australia
Chiba University, Japan
University of South Florida-Tampa, United States
University of Tennessee, United States
University of Graz, Austria
Sao Paulo University, Brazil
University of Southampton, United Kingdom
Shizuoka University, Japan
Western Washington University, United States
Scripps Institution of Oceanography, United States
Seoul National University, South Korea
State University of New York at Stony Brook, United States
Utah State University, United States
Institut Français du Pétrole, Energies Nouvelles, France
Japan Agency for Marine-Earth Science and Technology, Japan
Université de Lorraine, France
Xiamen University, China
Source: Preliminary Report - International Ocean Discovery Program, Vol.366, 40p. Publisher: International Ocean Discovery Program, College Station, TX, United States. ISSN: 2372-9562
Note: In English. 45 refs.
Summary: Geologic processes at convergent plate margins control geochemical cycling, seismicity, and deep biosphere activity in subduction zones and suprasubduction zone lithosphere. International Ocean Discovery Program (IODP) Expedition 366 was designed to address the nature of these processes in the shallow to intermediate depth of the Mariana subduction channel. Although no technology is available to permit direct sampling of the subduction channel of an intraoceanic convergent margin at depths up to 18 km, the Mariana forearc region (between the trench and the active volcanic arc) provides a means to access this zone. Active conduits, resulting from fractures in the forearc, are prompted by along- and across-strike extension that allows slab-derived fluids and materials to ascend to the seafloor along associated faults, resulting in the formation of serpentinite mud volcanoes. Serpentinite mud volcanoes of the Mariana forearc are the largest mud volcanoes on Earth. Their positions adjacent to or atop fault scarps on the forearc are likely related to the regional extension and vertical tectonic deformation in the forearc. Serpentinite mudflows at these volcanoes include serpentinized forearc mantle clasts, crustal and subducted Pacific plate materials, a matrix of serpentinite muds, and deep-sourced formation fluid. Mud volcanism on the Mariana forearc occurs within 100 km of the trench, representing a range of depths and temperatures to the downgoing plate and the subduction channel. These processes have likely been active for tens of millions of years at this site and for billions of years on Earth. At least 10 active serpentinite mud volcanoes have been located in the Mariana forearc. Two of these mud volcanoes are Conical and South Chamorro Seamounts, which are the furthest from the Mariana Trench at 86 and 78 km, respectively. Both seamounts were cored during Ocean Drilling Program (ODP) Legs 125 and 195, respectively. Data from these two seamounts represent deeper, warmer examples of the continuum of slab-derived materials as the Pacific plate subducts, providing a snapshot of how slab subduction affects fluid release, the composition of ascending fluids, mantle hydration, and the metamorphic paragenesis of subducted oceanic lithosphere. Data from the study of these two mud volcanoes constrain the pressure, temperature, and composition of fluids and materials within the subduction channel at depths of about 18 to 19 km. Understanding such processes is necessary for elucidating factors that control seismicity in convergent margins, tectonic and magma genesis processes in the forearc and volcanic arc, fluid and material fluxes, and the nature and variability of environmental conditions that impact subseafloor microbial communities. Expedition 366 centered on data collection from cores recovered from three serpentinite mud volcanoes that define a continuum of subduction-channel processes defined by the two previously cored serpentinite mud volcanoes and the trench. Three serpentinite mud volcanoes (Yinazao, Fantangisna and Asut Tesoro) were chosen at distances 55 to 72 km from the Mariana Trench. Cores were recovered from active sites of eruption on their summit regions and on the flanks where ancient flows are overlain by more recent ones.
Year of Publication: 2017
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 05 Petrology, Igneous and Metamorphic; 18 Geophysics, Solid-Earth; Aliphatic hydrocarbons; Alkanes; Boreholes; Cores; Crust; Ethane; Expedition 366; Gases; Geochemistry; Heat flow; Hydrocarbons; Hydrogen; IODP Site U1491; IODP Site U1492; IODP Site U1493; IODP Site U1494; IODP Site U1495; IODP Site U1496; IODP Site U1497; IODP Site U1498; Igneous rocks; International Ocean Discovery Program; Magnetic properties; Magnetic susceptibility; Major elements; Mariana Trench; Marine sediments; Metaigneous rocks; Metamorphic rocks; Metasomatic rocks; Methane; Mud volcanoes; North Pacific; Northwest Pacific; Ocean floors; Oceanic crust; Organic compounds; Pacific Ocean; Paleomagnetism; Plate convergence; Plutonic rocks; Seamounts; Sedimentary rocks; Sediments; Serpentinite; South Chamorro Seamount; Subduction zones; Trace elements; Ultramafics; West Pacific
Coordinates: N154000 N180800 E1471400 E1470800
Record ID: 2017094577
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute.