Evolution of the Hidaka metamorphic belt, northern Japan

The Hidaka metamorphic belt is a tilted island-arc assembly of crustal layers developed during early to middle Tertiary age. The P-T estimates of metamorphic rocks in the amphibolite and granulite facies reveal a relatively high geothermal gradient (40°C km^-1), possibly caused by the large amount of gabbroic intrusions, at an early evolutional stage of the crust. The crust was subsequently displaced subhorizontally from north to south, giving rise to detachment of lower to upper crustal layers from the lowest crust, and to the formation of a duplex of crustal metamorphic layers. This was followed by dextral transgression in which the crustal layers were uplifted and tilted steeply eastward. -Authors