Recognition of the Shimanto HP metamorphic belt within the traditional Sanbagawa HP metamorphic belt: New perspectives of the Cretaceous-Paleogene tectonics in Japan

Publication year: 2011
Source: Journal of Asian Earth Sciences, In Press, Accepted Manuscript, Available online 13 June 2011

Kazumasa, Aoki , Shigenori, Maruyama , Yukio, Isozaki , Shigeru, Otoh , Shuichi, Yanai

The Sanbagawa metamorphic belt in SW Japan has been traditionally referred as a typical subduction-related high-pressure (HP) metamorphic belt. This belt extends E-W direction for more than 800 km from the Kanto Mountains to Kyushu Island. In part, protoliths of many HP metamorphic rocks formed as an accretionary complex after ca. 90–80 Ma and suffered a blueschist-facies metamorphism at 66–61 Ma. This metamorphic event clearly postdates the Sanbagawa metamorphism of 120–110 Ma. This newly recognized HP rocks occur extensively in the traditional Sanbagawa (HP-) metamorphic belt throughout Shikoku, Kii Peninsula and Kanto Mountains, thus it was named as the Shimanto…

 Highlights: ► The Shimanto metamorphic rocks are newly recognized in Japan. These rocks suffered a HP metamorphism which clearly postdates the Sanbagawa HP metamorphism. Moreover, these rocks occur extensively in the traditional Sanbagawa metamorphic belt. Thus, the traditional Sanbagawa metamorphic belt comprises two independent HP metamorphic belts.