The ~500 Ma Asaji ultramafic–mafic intrusion in Kyushu, southwest Japan: Implications for boninitic magmatism in a late Cambrian nascent arc

It is thought that the continental crust that ultimately became Japan (i.e., proto-Japan) formed during the early Cambrian near the margin of the South China block following its separation from the Australian block. However, the onset of timing of subduction and details of the magmatic evolution of the region are poorly understood, due mainly to the sporadic occurrence of Cambrian rocks. A high-temperature metamorphic complex is distributed...