摘要 : The Sanbagawa belt is a "coherent" oceanic subduction-type metamor-phic region representing a rock package predominantly derived from oceanic crust and accreted at depths of 20-80 km (300-700 ℃). The thermal structure and litholo... 展开 The Sanbagawa belt is a "coherent" oceanic subduction-type metamor-phic region representing a rock package predominantly derived from oceanic crust and accreted at depths of 20-80 km (300-700 ℃). The thermal structure and lithological layers are complexly deformed but semi-continuous, in contrast to more commonly reported subduction-related domains dominated by melange. The coeval Shimanto accretionary complex records accretion at depths ＜15 km and the rocks are primarily terrigenous sediments. The Sanbagawa belt has a greater proportion of mafic rocks than the Shimanto complex, implying progressive peeling-off of oceanic plate stratigraphy with more basaltic oceanic crust slices accreted at deeper levels. Tectonic exhumation can be explained by three separate phases dominated by buoyancy-driven upflow, ductile thinning, and normal faulting. 收起