Tectonic evolution of two paleo arc-trench systems in Hokkaido, northern Japan

Abstract

The Paleo-Japan and Paleo-Kuril arc-trench systems that developed during late Cretaceous to early Paleocene have been studied by using paleomagnetics and sediment petrology in the axial zone and western part of Hokkaido, Northeast Japan. The sedimentary rocks in the southern part of the Hidaka Belt defme three petroprovinces (zones I to III). The sediment petrologic characteristics of zone I are similar to those of forearc basin deposits in the Paleo-Kuril arc region. The modal component of sandstone from zone III is similar to the forearc deposits of the Paleo-Japan arc region. Zone II has properties intermediate between zone I and Ill. The sediments of the Hidaka Belt were thus derived from two different arc-trench systems during Paleocene. Paleomagnetic data suggests that more than 70° clockwise rotation may have occurred in Eastern Hokkaido since late Eocene. Possible plate tectonic reconstructions are discussed in relation to the spreading of the Kuril basin.