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High‐ P metamorphism, pattern of induced flow in the mantle wedge, and the link with plutonism in paired metamorphic belts
Author(s) -
Aoya Mutsuki,
Mizukami Tomoyuki,
Uehara Shinichi,
Wallis Simon R.
Publication year - 2009
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.2008.00860.x
Subject(s) - geology , metamorphic rock , metamorphism , geochemistry , mantle wedge , mantle (geology) , subduction , petrology , metamorphic core complex , slab , crust , plutonism , oceanic crust , seismology , magmatism , geophysics , tectonics , extensional definition
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.