Cenozoic Volcanism of Southeast Asia

This paper presents an analysis of published and our own data on the geochemistry and isotopic sys- tematics of the Cenozoic volcanic complexes of southeastern China, Vietnam, and Thailand and the adjoining East China and South China seas. Three large periods of volcanic activity were distinguished: Early Tertiary, Miocene, and Pliocene-Quaternary. The first period was characterized by the development of potassic basalt (absarokites and cocites in Vietnam) and tholeiitic bimodal (basalts and trachytes in southeastern China) volca- nism, and the subsequent periods were dominated by intraplate-type tholeiitic and alkaline volcanism and minor occurrence of bimodal tholeiitic magmatism (basalts and rhyolites of the Okinawa Trough). The Ceno- zoic magmatic and geodynamic events were correlated over the region. It was shown that lateral and temporal variations in the compositions of the Miocene and Pliocene-Quaternary rocks reflect strong isotopic and geochemical heterogeneity of deep-seated magma sources.