Slab segmentation, anomalous arc volcanism, and giant porphyry copper deposits in Indonesia

Abstract

Most Holocene volcanoes in Indonesia display geochemical and geophysical properties characteristic of formation via mantle wedge metasomatism. However, some volcanoes (Toba, Ungaran, Muriah, Rinjani, Tambora, Sangeang Api, and Batu Tara) are anomalous, showing alkaline geochemical affinities, anomalously violent recent eruptions, and/or positioning above sections of slab generally considered too deep to induce mantle melting via slab dehydration. These anomalous volcanoes are spatially and temporally associated with giant Pliocene–recent porphyry Cu deposits (in thin continental or oceanic crust), contrary to global occurrences of porphyry Cu deposits that are typically restricted to thick (..