Controls of faulting and reaction kinetics on serpentinization and double Benioff zones.

Iyer, Karthik, Rüpke, Lars H., Phipps Morgan, Jason and Grevemeyer, Ingo (2012) Controls of faulting and reaction kinetics on serpentinization and double Benioff zones. Geochemistry Geophysics Geosystems, 13 . Q09010. DOI 10.1029/2012gc004304.

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Abstract

The subduction of partially serpentinized oceanic mantle may potentially be the key geologic process leading to the regassing of Earth's mantle and also has important consequences for subduction zone processes such as element cycling, slab deformation, and intermediate-depth seismicity. However, little is known about the quantity of water that is retained in the slab during mantle serpentinization and the pattern of serpentinization that may occur during bending-related faulting; an initial state that is essential for quantifying subsequent dehydration processes. We present a 2-D reactive-flow model simulating hydration processes in the presence of faulting at the trench outer-rise. We find that the temperature dependence of the serpentinization rate in conjunction with outer-rise faulting results in plate age and speed dependent patterns of hydration. Serpentinization also results in a reduction in surface heat flux toward the trench caused by advective downflow of seawater into the reaction region. Observed heat flow reductions are larger than the reduction due to the minimum-water downflow needed for partial serpentinization, predicting that active hydrothermal vents and chemosynthetic communities should also be associated with bend-fault serpentinization. Our model results agree with previous studies that the lower plane of double Benioff zones can be generated due to dehydration of serpentinized mantle at depth. More importantly, the depth-dependent pattern of serpentinization including reaction kinetics predicts a separation between the two Benioff planes consistent with seismic observations.

Document Type: Article
Additional Information: WOS:000309135100002
Keywords: double seismic zones; numerical modeling; outer rise faulting; serpentinization; subduction; water cycle; TRENCH-OUTER RISE; MIDDLE AMERICA TRENCH; DOUBLE SEISMIC ZONES; MANTLE SERPENTINIZATION; HEAT-FLOW; ARC LAVAS; HYDROTHERMAL CONVECTION; OCEANIC LITHOSPHERE; HYDRATION REACTIONS; SUBDUCTION ZONES
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-JRG-B3 Seabed Resources
OceanRep > SFB 574 > C5
OceanRep > SFB 574
OceanRep > The Future Ocean - Cluster of Excellence
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
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1029/2012gc004304
ISSN: 1525-2027
Related URLs:
Projects: Future Ocean
Date Deposited: 16 Oct 2012 06:41
Last Modified: 01 Mar 2018 12:50
URI: http://oceanrep.geomar.de/id/eprint/15464

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