(Table 1) Heavy minerals at DSDP Legs 56-57 Holes@en

Heavy-mineral assemblages in the cored sediments from DSDP Legs 56 and 57 show a distinct change of source rocks, from older sedimentary rocks during the Oligocene to volcanic rocks during the Miocene through Pleistocene. The former might have been supplied by the \"Oyashio ancient landmass,\" and the latter from the volcanic areas in Hokkaido and northeast Honshu. This indicates a shift of the Japanese Islands toward the continent.

深海钻探计划（Deep Sea Drilling Project, DSDP）第56、57航次获取的岩芯沉积物中的重矿物组合，清晰反映出物源岩的显著转变：渐新世时期的物源为古老沉积岩，中新世至更新世时期则转变为火山岩。前者的物源可能由亲潮古陆块（Oyashio ancient landmass）提供，后者则源自北海道与本州东北部的火山活动区域。该现象表明日本列岛正向大陆方向迁移。