島弧-海溝系逆転温度構造回復速度の数値実験 : 造山プロセスの新しい制約条件  [in Japanese] Numerical experiments for recovery of reversed thermal structure in arc-trench system : new constraints on orogenic process  [in Japanese]

Numerical experiments on recovery of reversed thermal structure in arc-trench system which have been formed during active subduction of oceanic plate under the arc, were carried out by solving a 2-D heat conduction equation after the decease of subduction. The results showed that the reversed structures of low temperature part up to 600℃ disappear in a short period up to 5 Ma, making it possible to exhume high P/T metamorphic rocks formed between wedge mantle peridotitc and oceanic basaltic slab by buoyancy of the slab. However, in this model, high temperature (about 1000℃) in wedge mantle above Wadati-Benioff zone under the fore arc region, which leads the fluid rich peridotite to partial melting, was never achieved by the recovery of the isotherm. Thus, the formation of high Mg andesite magma in wedge mantle under the forearc region requires high temperature heat source such as subduction of mide-oceanic ridge.