Paleo-mantle wedge preserved in the Sambagawa high-pressure metamorphic belt and the thickness of forearc continental crust

Research Article| April 01, 2013 Paleo-mantle wedge preserved in the Sambagawa high-pressure metamorphic belt and the thickness of forearc continental crust Mutsuki Aoya; Mutsuki Aoya 1Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, Tsukuba 305-8567, Japan *Current address: Institute of Socio-Arts and Sciences, University of Tokushima, Tokushima 770-8502, Japan. Search for other works by this author on: GSW Google Scholar Shunsuke Endo; Shunsuke Endo 1Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, Tsukuba 305-8567, Japan Search for other works by this author on: GSW Google Scholar Tomoyuki Mizukami; Tomoyuki Mizukami 2Earth Science Course, School of Natural System, College of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan Search for other works by this author on: GSW Google Scholar Simon R. Wallis Simon R. Wallis 3Department of Earth Paleo-mantle wedge preserved in the Sambagawa high-pressure metamorphic belt and the thickness of forearc continental crust. Geology 2013;; 41 (4): 451–454. doi: https://doi.org/10.1130/G33834.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract There are two possible origins for ultramafic rocks in subduction-type high-pressure metamorphic terranes: (1) they are derived from the subducted slab or footwall, or (2) they are derived from the mantle wedge in the hanging wall. The origin of ultramafic rock bodies in a classic high-pressure metamorphic belt, the Sambagawa belt of southwest Japan, is assessed based on wide-ranging field studies covering an area of 23 × 30 km2 and corresponding to metamorphic pressures of 5–25 kbar. Peridotite and/or serpentinite bodies are common in the higher pressure part of the belt, but no occurrence is known in the low-pressure part (the chlorite zone). If the ultramafic rocks originated in the footwall, they should be metamorphosed together with the subducted material and their distribution should not show any correlation with metamorphic pressure. The restricted distribution of mantle rocks to the high-pressure part is strong evidence for a mantle-wedge origin of the ultramafic blocks. The presence of subducted metasediments surrounding the mantle rocks indicates that the subducted slab can tectonically entrain and transport substantial amount of hanging-wall material to the Earth's surface. The first appearance of ultramafics occurs within the garnet zone, which has a peak metamorphic pressure of 8.0–9.5 kbar, and the corresponding depth (∼30–35 km) represents the thickness of the forearc continental crust in the Cretaceous Sambagawa subduction zone. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.