Kamuikotan Metamorphics Gr

Kamuikotan Belt

Synonym:

The Kamuikotan Zone is characterized by the occurrence of rocks recording HP-LT metamorphism (Kamuikotan metamorphism) and serpentinites, exposed in the cores of anticlines within the Yezo forearc basin. Although the geological structure of these exposures is complicated, the HP-LT rocks occur mainly either as coherent masses of crystalline schist and lower-grade accretionary complexes, or as blocks in serpentinite mélanges (Sakakibara & Ota 1994). In addition to these HP-LT rocks, fault-bounded sheets and blocks of ophiolitic rocks such as serpentinized peridotite, metagabbro and amphibolite of low-pressure series correlative with the Horokanai Ophiolite also occur (Ishizuka et al. 1983a; Nakagawa & Toda 1987; Kawamura et al. 1998).
The Kamuikotan metamorphic rocks can be grouped into at least three types in terms of protolith, metamorphic condition and ages. In ascending order (names are tentative): The first Kamuikotan Complex Fm, Iwashimizu Complex Fm, The third Kamuikotan Complex Fm.

The age of pre-metamorphic rocks is not sure. The age span used here is tentative and inferred from the age span from Naizawa complex Fm and Yezo Super Gr.