The subduction zone water cycle revisited with novel 2D and 3D numerical models.

Rüpke, Lars, Iyer, Karthik, Hasenclever, Jörg and Morgan, Jason P. (2010) The subduction zone water cycle revisited with novel 2D and 3D numerical models. [Talk] In: SFB 574 Subduction Workshop. , 04.- 07.11. 2010, Pucón, Chile .

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Abstract

The subduction zone water cycle, i.e. the hydration and dehydration of subducting oceanic lithosphere, is a key process in understanding arc magmatism and volatile recycling processes. Hydration of oceanic crust begins at mid-ocean ridges through hydrothermal alteration and continues more slowly as the seafloor ages. Finally, there is now robust evidence that bend-faulting at the outer rise leads to serpentinization of the cold lithospheric mantle. Dehydration occurs deeper within the subduction zone by fluid releasing metamorphic reactions. These rising fluids flux the mantle wedge where they trigger arc melting. Adiabatic mantle decompression, which requires an upward velocity component in the solid-state mantle flow, may
also contribute to sub-arc melt generation.
This study uses two- and three-dimensional numerical models to explore plate hydration at the outer rise and consequences of plate dehydration for mantle wedge dynamics. Hydration reactions are simulated with a 2D reaction transport model that resolves for seawater circulation as well as serpentinization. We find that bend-faults are likely to be highly serpentinized.
Background serpentinization is most intense around the 270°C isotherm where the reaction rate is at its maximum. 3D mantle flow calculations are used to elucidate mantle wedge dynamics. Here we find that threedimensional diapiric upwellings, fueled by buoyant slab fluids, dominant the
mantle wedge flow for a wide parameter range. These calculations clearly show that findings and intuition built upon 2D pictures will need to be revised as high resolution simulations become more feasible with the development of
new codes and the availability of better hardware.

Document Type: Conference or Workshop Item (Talk)
Keywords: Geodynamics; subduction zone
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-JRG-B3 Seabed Resources
OceanRep > SFB 574 > C5
OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
Date Deposited: 10 Dec 2010 09:58
Last Modified: 01 Feb 2017 09:51
URI: http://oceanrep.geomar.de/id/eprint/10414

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