VOLCANOSTRATIGHRAPHY AND PETROGENESIS OF SADAKELING KARAHA COMPLEX, TASIKMALAYA DISTRICT, WEST JAVA PROVINCE
Azrie Ezziat Putera Muhammad (a*), Mochammad Nugraha Kartadinata (b), Mirzam Abdurrachman (c), Wilfridus FS Banggur (d)

a) Department of Geological Engineering, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
*azriezziat20[at]gmail.com
b) Center for Volcanology and Geological Hazard Mitigation
Jalan Diponegoro 57, bandung 40122, Indonesia
c) Department of Geological Engineering, Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
d) Center for Geological Disaster Research
Jalan Sangkuriang, Bandung 40135, Indonesia

Abstract

The Sadakeling Karaha Volcano Complex is a type-C volcano in West Java Province. Based on the tectonics, this area can be a continuous fragment of the Australian Continent Argoland, which controls the magmatism process. This study aims to map this complex with volcanostratigraphy, the history of the formation and evolution of magma, and determine the tectonic setting and continuity of Argoland using petrogenesis studies. The type of data for this study uses Landsat-8 imagery to help with volcanostratigraphy, as well as rock samples by analyzing texture, plagioclase microtexture, and their geochemical content. Based on the volcanostratigraphy analysis, the Sadakeling Karaha complex consists of 4 Khuluks and 12 Volcanic Gumuks formed during 7 phases with fairly complex magma evolution characteristics. Specifically, characterized by repeated differentiation, magma assimilation and primitive magma injection as reflected by fluctuations in anorthite content, texture in each lava unit, and Harker diagrams between major oxide compounds and silica. The evolution of magma can be reflected from the plagioclase microtexture, which includes the crystal fractionation process, the decompression process due to primitive magma, the self-mixing process due to convection, heating due to primitive magma mixing, cooling due to eruption, and decompression process during the eruption. The geochemical studies reveal that the tectonic aspect of the Sadakeling Karaha Complex is part of a volcanic arc influenced by subduction processes and crustal contamination so that it is included in the active continental margin with magma series is tholeiitic - alkaline calc. Moreover, the Sr and Nd content and their comparisons show that contamination from the southeastern Australian continental crust influences the magma source formation process.

Keywords: Volkanostratigraphy, Petrogenesis, Sadakeling Karaha Complex, Magma Evolution, Argoland.

Topic: Solid Earth Sciences