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| Titel |
The fate of fluids released from subducting slab in northern Cascadia |
| VerfasserIn |
K. Ramachandran, R. D. Hyndman |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 3, no. 1 ; Nr. 3, no. 1 (2012-04-17), S.121-129 |
| Datensatznummer |
250000841
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| Publikation (Nr.) |
 copernicus.org/se-3-121-2012.pdf |
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| Zusammenfassung |
| Large amounts of water carried down in subduction zones are driven
upward into the overlying forearc upper mantle and crust as increasing
temperatures and pressure dehydrate the subducting crust. Through seismic
tomography velocities we show (a) the overlying forearc mantle in northern
Cascadia is hydrated to serpentinite, and (b) there is low Poisson's ratio
at the base of the forearc lower crust that may represent silica deposited
from the rising fluids. From the velocities observed in the forearc mantle,
the volume of serpentinite estimated is ∼30 %. This mechanically
weak hydrated forearc region has important consequences in limits to great
earthquakes and to collision tectonics. An approximately 10 km thick lower
crustal layer of low Poisson's ratio (σ = 0.22) in the forearc is
estimated to represent a maximum addition of ∼14 % by volume of
quartz (σ = 0.09). If this quartz is removed from rising
silica-saturated fluids over long times, it represents a significant addition
of silica to the continental crust and an important contributor to its
average composition. |
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