283 by Ki-Cheol Shin1, Ryo Anma2, Takanori Nakano1, Yuji Orihashi3 and Shin-ichi Ike2,* The Taitao ophiolite-granite complex, Chile: Emplacement of ridge-trench intersection oceanic lithosphere on land and the origin of calc-alkaline I-type granites 1 Research Institute for Humanity and Nature, Motoyama 457-4, Kamigamo, Kita-Ku, Kyoto 603-8047, Japan 2 University of Tsukuba, Ten-nodai 1-1-1, Tsukuba 305-8572, Japan. Corresponding author E-mail:
[email protected] 3 Earthquake Research Institute, University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo 113-0032, Japan * Present address: Medical Device Supply Chain Asia Pacific, Johnson & Johnson K.K. Medical Company, 3-5-2 Nishikanda, Chiyoda-ku, Tokyo 101-0065, Japan DOI: 10.18814/epiiugs/2015/v38i4/82424 The late Miocene – early Pliocene Taitao ophiolite is emplaced onto continental crust (Anonymous, 1972). Once it was exposed ~30 km southeast of the Chile triple junction, presumed that this allochthonous material invariably formed at a mid- ocean spreading ridge. Today, most ophiolites are thought to form in where a spreading center of the Chile ridge system is supra-subduction zone (SSZ) settings in an island-arc or back-arc subducting underneath the South America plate. This spreading environment (Miyashiro, 1973; Pearce and Robinson, 2010; unique tectonic setting provides an excellent opportunity Dilek and Furnes, 2011, 2014). However, even for extensively exposed to study the emplacement mechanism of a ridge-trench and intensively studied examples like the Semail ophiolite, Oman, disagreement persists between ridge-origin scholars (Boudier et al., intersection ophiolite and the complex magmatic inter- 1996; MacLeod and Yaouancq, 2000; Miyashita et al., 2003; Adachi actions between the subducting ridge, overlying crust and Miyashita, 2003; Boudier and Nicolas, 2011) and SSZ-origin and sediments,and the mantle wedge.