The Horokanai ophiolite is a geological complex located in the Kamuikotan tectonic belt about 30 km northwest of Asahikawa city, Hokkaido, Japan.
Finally, the upper basaltic pillow lavas and tuff flows have metamorphosed to amphibolite schists and “metabasalt.”[1] Asahina et al. (1979)[1] presents two theories for the metamorphism of the Horokanai complex.
The first theory claims that metamorphism takes place at a mid-ocean ridge with a high geothermal gradient, accompanied by shear and plastic flow.
The distinction was made by examining the Chromium, Nickel and Titanium abundances in the ophiolite, as well as relic spinel chemistry in Horokanai pillow basalts.
They base this conclusion on the presence of picrite (with back-arc-associated pyroclastic and turbidite deposits) and high-Mg basaltic-andesite (commonly associated with fore-arc and back-arc settings) within the Gokurakudaira Formation.