[BCG06-06] Ankaramite-andesite-basalt (ANANBA) model of arc evolution
Keywords:ankaramite, andesite, basalt
Olivine-bearing phenocryst-poor andesites found in older submarine lavas from the flanks of the volcano have been used to develop a model for the genesis of andesitic lavas from Nishinoshima (Tamura et al., 2019). Primary andesite magmas originate directly from the mantle as a result of shallow and hydrous melting of plagioclase peridotites. Andesites erupted from Nishinoshima that were produced in the recent history of the volcano have been generated by olivine fractionation of primary andesitic magmas (Tamura et al., 2019).
When crust becomes thicker than 30 km like northern parts of the Izu-Ogasawara arc (Izu-Oshima volcano, Miyake-jima volcano etc), only basalt magmas are produced in the mantle wedge of subduction zones.We present here the evolution model of oceanic arc volcanoes, which start from ankaramites through andesites to basalts (ANANBA model).