Water input and water release from the subducting Nazca Plate along southern Central Chile (33°S-46°S)

Völker, David and Stipp, Michael (2015) Water input and water release from the subducting Nazca Plate along southern Central Chile (33°S-46°S) Geochemistry, Geophysics, Geosystems, 16 (6). pp. 1825-1847. DOI 10.1002/2015GC005766.

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Abstract

The age of the subducting Nazca Plate off Chile increases northward from 0 Ma at the Chile Triple Junction (46°S) to 37 Ma at the latitude of Valparaíso (32°S). Age-related variations in the thermal state of the subducting plate impact on (a) the water influx to the subduction zone, as well as on (b) the volumes of water that are released under the continental fore arc or, alternatively, carried beyond the arc. Southern Central Chile is an ideal setting to study this effect, because other factors for the subduction zone water budget appear constant. We determine the water influx by calculating the crustal water uptake and by modeling the upper mantle serpentinization at the outer rise of the Chile Trench. The water release under fore arc and arc is determined by coupling FEM thermal models of the subducting plate with stability fields of water-releasing mineral reactions for upper and lower crust and hydrated mantle. Results show that both the influx of water stored in, and the outflux of water released from upper crust, lower crust, and mantle vary drastically over segment boundaries. In particular, the oldest and coldest segments carry roughly twice as much water into the subduction zone as the youngest and hottest segments, but their release flux to the fore arc is only about one fourth of the latter. This high variability over a subduction zone of <1500 km length shows that it is insufficient to consider subduction zones as uniform entities in global estimates of subduction zone fluxes.

Document Type: Article
Keywords: Chile; Mantle serpentinization; Oceanic crust dehydration; Subduction zone metamorphism; Subduction zone water budget; Thermal modeling
Research affiliation: OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1002/2015GC005766
ISSN: 1525-2027
Projects: SFB574
Contribution Number:
ProjectNumber
SFB 574272
Date Deposited: 25 Jun 2015 10:56
Last Modified: 12 Apr 2017 10:05
URI: http://eprints.uni-kiel.de/id/eprint/29060

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