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TitleSharp thermal transition in the forearc mantle wedge as a consequence of nonlinear mantle wedge flow
AuthorWada, I; Rychert, C A; Wang, K
SourceGeophysical Research Letters vol. 38, L13308, 2011, 5 pages,
Alt SeriesEarth Sciences Sector, Contribution Series 20110061
Mediapaper; on-line; digital
File formatpdf
Subjectstectonics; mantle; earth thermal history; thermal conductivity; flow velocities
Illustrationscross-sections; graphs
ProgramTargeted Hazard Assessments in Western Canada, Public Safety Geoscience
AbstractIn the forearc mantle wedge, the thermal field depends strongly on slab-driven mantle wedge flow. The flow is in turn affected by the thermal field via the temperature dependence of mantle rheology. Using thermal modeling, we show that the nonlinear feedback between the thermal and flow fields always leads to complete stagnation of the mantle wedge over a shallow, weakened part of the slabmantle interface and an abrupt onset of mantle flow further down-dip. The abrupt increase in flow velocity leads to a sharp thermal transition from a cold stagnant to a hot flowing part of the wedge. This sharp thermal transition is inherent to all subduction zones, explaining a commonly observed sharp arc-ward increase in seismic attenuation.