Kastner, Miriam; Elderfield, Henry; Jenkins, William J; Gieskes, Joris M; Gamo, Toshitaka (1993): Geochemical and isotopic composition of pore fluids of ODP Hole 131-808C [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.785296, Supplement to: Kastner, M et al. (1993): Geochemical and isotopic evidence for fluid flow in the western Nankai subduction zone, Japan. In: Hill, IA; Taira, A; Firth, JV; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 131, 397-413, https://doi.org/10.2973/odp.proc.sr.131.143.1993
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Abstract:
At the Western Nankai Trough subduction zone at ODP Site 808, chemical concentration and isotopic ratio depth profiles of D, O, Sr, and He do not support fluid flow along the décollement nor at the frontal thrust. They do, however, support continuous or periodic lateral fluid flow: (1) at the base of the Shikoku Basin volcanic-rich sediment member, situated ~140 m above the décollement, and particularly (2) below the décollement. The latter must have been rather vigorous, as it was capable of transporting clay minerals over great distances. The fluid at ~140 m above the décollement is characterized by lower than seawater concentrations of Cl- (>=18% seawater dilution). It is 18O-rich and D-poor and has a non-radiogenic, oceanic, or volcanic arc Sr isotopic signature. It originates from "volcanic" clay diagenesis. The fluid below the décollement has also less Cl- than seawater (>20% dilution), is more enriched in 18O and depleted in D than fluid, but its Sr isotopic signature is radiogenic, continentalterrigenous. The source of this fluid is located arcward, is deep-seated, where illitization of the subducted clay minerals, a mixture of terrigenous and volcanic clays, occurs. The 3He/4He ratio below the décollement points to an ~25% mantle contribution.
The nature of the physical and chemical discontinuities across the décollement suggests it is overpressured and is forming a leaky "dynamic seal" for fluid flow. In contrast with the situation at Barbados and Peru, where the major tectonic features are mineralized, here, although the complex is extremely fractured and faulted, mineralized macroscopic veins, fractures, and faults are absent. Instead, mineralized microstructures are widespread, indicating a diffuse mode of dewatering.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Latitude: 32.352800 * Longitude: 134.944300
Date/Time Start: 1990-04-16T04:00:00 * Date/Time End: 1990-05-02T14:40:00
Event(s):
131-808C * Latitude: 32.352800 * Longitude: 134.944300 * Date/Time Start: 1990-04-16T04:00:00 * Date/Time End: 1990-05-02T14:40:00 * Elevation: -4686.0 m * Penetration: 1327 m * Recovery: 572.43 m * Location: Philippine Sea * Campaign: Leg131 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 108 cores; 1028.5 m cored; 0 m drilled; 55.7 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets
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Datasets listed in this publication series
- Kastner, M; Elderfield, H; Jenkins, WJ et al. (1993): (Table 4) Oxygen and carbon isotopic compositions of diagenetic calcites from ODP Hole 131-808C. https://doi.org/10.1594/PANGAEA.785293
- Kastner, M; Elderfield, H; Jenkins, WJ et al. (1993): (Table 3) Oxygen and hydrogen isotopic compositions of pore fluids from ODP Hole 131-808C. https://doi.org/10.1594/PANGAEA.785292
- Kastner, M; Elderfield, H; Jenkins, WJ et al. (1993): (Tables 1, 2) Chemical and Sr isotopic composition of pore fluids from ODP Hole 131-808C. https://doi.org/10.1594/PANGAEA.785291