Abstract
Previous studies on the Tholeiitic (TH) and calc-alkaline (CA) magma series at Adatara volcano showed that the two series were derived from distinct parent magmas with independent evolutionary processes. The TH and CA magmas erupted concurrently about 0.35 Ma were investigated in detail, to reveal their temporal compositional variations. Petrological features for a series of TH magmas which erupted successively from a common vent are basically reconciled with the idea that the TH series were related through fractional crystallization, with minor supply of primitive magma or local heterogeneity within the reservoir. Petrology of the cognate inclusions and heterogeneous CA lavas indicates that a magma mixing acted a crucial role in the compositional variation of the CA series.
