Citation:

odp.proc.sr.195.106.2005

Name: Geochemistry of pore fluids and bulk solids of ODP Site 195-1200, South Chamorro Seamount
Published: 2005
License: https://creativecommons.org/licenses/by/3.0/

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Published: 2005 (exact date unknown) • DOI registered: 2012-04-27

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Abstract:

At the South Chamorro Seamount in the Mariana subduction zone, geochemical data of pore fluids recovered from Ocean Drilling Program Leg 195 Site 1200 indicate that these fluids evolved from dehydration of the underthrusting Pacific plate and upwelling of fluids to the surface through serpentinite mud volcanoes as cold springs at their summits. Physical conditions of the fluid source at 27 km were inferred to be at 100°-250°C and 0.8 GPa. The upwelling of fluid is more active near the spring in Holes 1200E and 1200A and becomes less so with increasing distance toward Hole 1200D. These pore fluids are depleted in Cl and Br, enriched in F (except in Hole 1200D) and B (up to 3500 µM), have low 11B (16-21), and have lower than seawater Br/Cl ratios. The mixing ratios between seawater and pore fluids is calculated to be ~2:1 at shallow depth. The F, Cl, and Br concentrations, together with B concentrations and B isotope ratios in the serpentinized igneous rocks and serpentine muds that include ultramafic clasts from Holes 1200A, 1200B, 1200D, 1200E, and 1200F, support the conclusion that the fluids involved in serpentinization originated from great depths; the dehydration of sediments and altered basalt at the top of the subducting Pacific plate released Cl, H2O, and B with enriched 10B. Calculation from B concentrations and upwelling rates indicate that B is efficiently recycled through this nonaccretionary subduction zone, as through others, and may contribute the critical missing B of the oceanic cycle.

Project(s):

Ocean Drilling Program (ODP)

Coverage:

Median Latitude: 13.783685 * Median Longitude: 146.003013 * South-bound Latitude: 13.783350 * West-bound Longitude: 146.002850 * North-bound Latitude: 13.784060 * East-bound Longitude: 146.003300

Date/Time Start: 2001-03-10T21:00:00 * Date/Time End: 2001-03-29T02:00:00

Event(s):

195-1200A * Latitude: 13.783410 * Longitude: 146.003100 * Date/Time Start: 2001-03-10T21:00:00 * Date/Time End: 2001-03-13T15:35:00 * Elevation: -2910.3 m * Penetration: 147.2 m * Recovery: 11.56 m * Location: North Pacific Ocean * Campaign: * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 16 cores; 147.2 m cored; 0 m drilled; 7.9 % recovery

195-1200B * Latitude: 13.783400 * Longitude: 146.003300 * Date/Time Start: 2001-03-13T15:35:00 * Date/Time End: 2001-03-14T14:30:00 * Elevation: -2911.3 m * Penetration: 98 m * Location: North Pacific Ocean * Campaign: * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 0 cores; 0 m cored; 0 m drilled

195-1200D * Latitude: 13.784060 * Longitude: 146.002850 * Date/Time Start: 2001-03-26T05:00:00 * Date/Time End: 2001-03-27T12:30:00 * Elevation: -2931.0 m * Penetration: 44.4 m * Recovery: 22 m * Location: North Pacific Ocean * Campaign: * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 10 cores; 21.9 m cored; 22.5 m drilled; 100.5 % recovery

License:

Creative Commons Attribution 3.0 Unported (CC-BY-3.0)

Size:

2 datasets

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Datasets listed in this publication series

Wei, W; Kastner, M; Deyhle, A et al. (2005): (Table T2) Halogen, sulphate, boron and boron isotope composition of bulk solids from ODP Site 195-1200. https://doi.org/10.1594/PANGAEA.778486
Wei, W; Kastner, M; Deyhle, A et al. (2012): (Table T1) Halogen, sulphate, boron and boron isotope composition of pore fluids from ODP Site 195-1200. https://doi.org/10.1594/PANGAEA.778485