HR: 1400h
AN: V23B-08    [Abstracts]
TI: Characteristics of Mineralized Volcanic Centers in Javanese Sunda Island Arc, Indonesia
AU: * Setijadji, L D
EM: lucas@mine.kyushu-u.ac.jp
AF: Department of Earth Resources Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
AU: * Setijadji, L D
EM: lucas@mine.kyushu-u.ac.jp
AF: Department of Geological Engineering, Gadjah Mada University, 2 Grafika, Bulaksumur, Yogyakarta, 55281, Indonesia
AU: Imai, A
EM: imai@mine.kyushu-u.ac.jp
AF: Department of Earth Resources Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
AU: Watanabe, K
EM: wat@mine.kyushu-u.ac.jp
AF: Department of Earth Resources Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
AB: The subduction-related arc magmatism in Java island, Sunda Arc, Indonesia might have started in earliest Tertiary period, but the distinctively recognizable volcanic belts related with Java trench subduction occurred since the Oligocene. We compiled geoinformation on volcanic centers of different epochs, distribution of metallic mineral deposits, petrochemistry of volcanic rocks, geologic structures, and regional gravity image in order to elucidate characteristics of the known mineralized volcanic centers. Metallic deposits are present in various styles from porphyry-related, high-sulfidation, and low-sulfidation epithermal systems; all related with subaerial volcanism and subvolcanic plutonism. Only few and small occurrences of volcanigenic massive sulfides deposits suggest that some mineralization also occurred in a submarine environment. Most locations of mineral deposits can be related with location of Tertiary volcanic centers along the volcanic arcs (i.e. volcanoes whose genetic link with subduction is clear). On the other side there is no mineralization has been identified to occur associated with backarc magmatism whose genetic link with subduction is under debate. There is strong evidence that major metallic deposit districts are located within compressive tectonic regime and bound by coupling major, deep, and old crustal structures (strike-slip faults) that are recognizable from regional gravity anomaly map. So far the most economical deposits and the only existing mines at major industry scale are high-grade epithermal gold deposits which are young (Upper Miocene to Upper Pliocene), concentrated in Bayah dome complex in west Java, and are associated with alkalic magmatism-volcanism. On the other hand, known porphyry Cu-Au deposits are associated with old (Oligocene to Upper Miocene) stocks, and except for one case, all deposits are located in east Java. Petrochemical data suggest a genetic relationship between porphyry mineralization with low- to moderate-K, high Sr/Y, and low K2O/Na2O magmatism. In turn these features suggest genetic relationship between porphyry Cu-Au mineralization and partial melting of subducted slab.
DE: 1031 Subduction zone processes (3060, 3613, 8170, 8413)
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 3613 Subduction zone processes (1031, 3060, 8170, 8413)
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly