Abstract
Late Cenozoic magmatism in Kyushu shows the complex temporal, spatial and geochemical patterns. For example, the Hisatsu volcanic province is a northwor curved belt of about 100km in length from northwest to southwest and 25km wide in southern Kyushu. The Hisatsu volcanic rocks are divided into three stages. In the first stage(7.6-2.5Ma), the low-K andesites occurred in the west side and the high-K andesites in the east side of the province. In the second stage(2.5-2Ma), the high-K andesites widely erupted throughout the area(flood andesite). In the third stage(2-0.4Ma), the loe-K andesites erupted in the west side again, and the high-K andesites in the east saide. These volcanic activities have some characteristics differing from those of subduction zone magmatism, so it is assumed that the Hisatsu volcanic rocks originated from an ascending heterogeneous mantle. Recently, Shimono et al.(2006) reported that the late Miocene to Pleistocene magmatism in southern Kyushu are not associated with plate subduction on the basis of boron contents in volcanic rocks.
