COMPARISON OF MAGMA CHARACTERISTICS CONTROLLING PORPHYRY COPPER MINERALIZATION IN BATU HIJAU (WEST NUSA TENGGARA) AND TANA DARO (EAST NUSA TENGGARA) BASED ON GEOCHEMICAL DATA

• Main Author: Bagus Manggadyta, Arda
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53778
• Institution: Institut Teknologi Bandung

The Sunda-Banda Arc is a magmatic arc rich in mineral deposits in Indonesia, one of which is porphyry copper deposits. However, the distribution of the deposit in this arc is uneven. The research area is located in two different locations, the first location is the Batu Hijau Intrusion Complex located on Sumbawa Island, West Nusa Tenggara Province while the second location is in the Tana Daro Intrusion Complex located on Sumba Island, East Nusa Tenggara Province. The Batu Hijau and Tana Daro Intrusion Complexes are Tertiary intrusion complexes located on the Sunda-Banda Arc. However, the magma fertility of the two complexes is different. Batu Hijau is an intrusion complex associated with porphyry copper deposit, while Tana Daro is a barren intrusion complex. The aim of this study is to compare the petrogenesis and characteristics of magma which affect the differences in magma fertility in the two locations based on geochemical data so that it is expected to be a tool for regional exploration vectoring in Indonesia. The method used is secondary data analysis using the element variation diagrams. The result of the petrogenesis analysis shows that Batu Hijau and Tana Daro complexes are located in island arc tectonic setting. The Batu Hijau complex contains tholeiitic and calc-alkaline magma series while Tana Daro is calc-alkaline. The magma source of the two complexes comes from the metasomatized mantle wedge but there is a source modification in Batu Hijau. This differentiates the crystal fractionation behavior of the two complexes as indicated by the increasing Sr/Y value in Batu Hijau and decreasing Sr/Y value in Tana Daro along with differentiation. The distinguishing magma characteristic of mineralization fertility in the two complexes is the water content and oxygen fugacity in the magma. The Batu Hijau complex has higher water content and oxygen fugacity up to FMQ+2 than the Tana Daro complex.