Konrad-Schmolke, M, Halama, R ORCID: https://orcid.org/0000-0002-9770-6784 and Manea, VC (2016) Slab mantle dehydrates beneath Kamchatka – yet recycles water into the deep mantle. Geochemistry Geophysics Geosystems, 17 (8). pp. 2987-3007.

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Abstract

The subduction of hydrated slab mantle is the most important and yet weakly constrained factor in the quantification of the Earth's deep geologic water cycle. The most critical unknowns are the initial hydration state and the dehydration behavior of the subducted oceanic mantle. Here we present a combined thermomechanical, thermodynamic, and geochemical model of the Kamchatka subduction zone that indicates significant dehydration of subducted slab mantle beneath Kamchatka. Evidence for the subduction of hydrated oceanic mantle comes from across‐arc trends of boron concentrations and isotopic compositions in arc volcanic rocks. Our thermodynamic‐geochemical models successfully predict the complex geochemical patterns and the spatial distribution of arc volcanoes in Kamchatka assuming the subduction of hydrated oceanic mantle. Our results show that water content and dehydration behavior of the slab mantle beneath Kamchatka can be directly linked to compositional features in arc volcanic rocks. Depending on hydration depth of the slab mantle, our models yield water recycling rates between 1.1 × 103 and 7.4 × 103 Tg/Ma/km corresponding to values between 0.75 × 106 and 5.2 × 106 Tg/Ma for the entire Kamchatkan subduction zone. These values are up to one order of magnitude lower than previous estimates for Kamchatka, but clearly show that subducted hydrated slab mantle significantly contributes to the water budget in the Kamchatkan subduction zone.

Item Type: Article
Uncontrolled Keywords: deep water subduction, Kamchatka, slab mantle dehydration, thermodynamic modeling, global geochemical cycles
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Depositing User: Symplectic
Date Deposited: 17 Jun 2016 09:43
Last Modified: 11 Apr 2019 09:07
URI: http://eprints.keele.ac.uk/id/eprint/1894

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