High-P metamorphism, pattern of induced flow in the mantle wedge, and the link with plutonism in paired metamorphic belts |
| |
| Authors: | Mutsuki Aoya Tomoyuki Mizukami Shin-ichi Uehara Simon R Wallis |
| |
| Institution: | Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, Tsukuba 305-8567, Japan;;Earth Science Course, School of Natural System, College of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan;;Department of Earth &Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan |
| |
| Abstract: | The convex form of subduction-stage pressure–temperature ( P–T ) paths up to c. 2.0 GPa implies the Sambagawa high- P metamorphic belt, Japan, formed a few million years before ridge subduction. Additional compilation of P–T conditions for higher- P Sambagawa rocks ( c. 2.0–2.5 GPa) reveals that the thermal profile along the slab surface shows a remarkable high- T -ward warping at c. 2.0 GPa ( c. 65 km). Previous thermal models indicate that this warping corresponds to the onset of induced mantle flow towards the subducting slab. If a normal thickness continental crust of c. 30 km was present, this implies the hangingwall region between 30 and 65 km depth was occupied by serpentinized wedge mantle isolated from large-scale mantle flow. Subsequent arrival of the spreading ridge, reheating and dehydration of the serpentinized wedge probably supplied the water necessary for causing granitic magmatism in the Ryoke high- T metamorphic belt, which is paired with the Sambagawa belt. |
| |
| Keywords: | |
|
|
