Letter abstract


Nature Geoscience 1, 380 - 384 (2008)
Published online: 11 May 2008 | doi:10.1038/ngeo200

Subject Categories: Geochemistry | Structural geology, tectonics and geodynamics

Geochemical evidence for enhanced fluid flux due to overlapping subducting plates

Hitomi Nakamura1,4, Hikaru Iwamori2 & Jun-Ichi Kimura3,6

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Aqueous fluids released from subducting plates play an important role in magma generation in many arc settings1, 2, 3, 4. However, different hypotheses have been proposed for the origin of these fluids, the extent to which they mix with the mantle wedge and spatial variations in their composition2, 3, 4, especially at complex settings involving more than one subducting plate. Central Japan is one such setting, where the Pacific and Philippine Sea plates subduct underneath the North American and Eurasian plates and cause extensive arc magmatism to the west and north of Tokyo. Here, we use geochemical data for rocks from 28 Quaternary volcanoes in central Japan to quantify the relative contribution of fluids originating from the two subducting plates and their spatial distribution. We find that the fluid originating from the Philippine Sea plate is chemically distinct and its flux is localized, as compared with the larger-scale flux from the Pacific plate. In the regions where these two plates overlap, the Philippine Sea plate does not seem to significantly inhibit fluid flow from the Pacific plate below; instead, this geometry leads to enhanced fluid flux. Regional variations in fluid flux and composition are controlled primarily by the geometry and configuration of the subducting plates.

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  1. Department of Geosystem Engineering, University of Tokyo, Hongo, Tokyo 113-0033, Japan
  2. Department of Earth and Planetary Science, University of Tokyo, Hongo, Tokyo 113-0033, Japan
  3. Department of Geoscience, Shimane University, Matsue city, 690-8504, Japan
  4. Present address: Institute of Geoscience and Geoinformation, Geological Survey of Japan (AIST), Tsukuba, Ibaraki, 305-8567, Japan
  5. Present address: Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan

Correspondence to: Hitomi Nakamura1,4 e-mail: hitomi-nakamura@aist.go.jp



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