Geochemistry of Gede Volcanic Complex West Java, Indonesia, Compared to Salak Volcano as its Proximity and how The Ciletuh Mélange Complex Lineament Affected It

Abstract

‘Mélange’ has been used to indicate a larger spectrum of chaotic rock bodies formed in various and different tectonic settings (rift–drift cycles, oceanic subduction, continental collision, and intracontinental deformation) by tectonic, sedimentary, and diapiric processes and their mutual interaction. Two well-known mélanges in Java Island are Ciletuh mélange in Sukabumi and another in Karangsambung, Kebumen. Previous studies suggest those mélanges are connected and indicate the Early Cretaceous Sundaland boundary elongated from Ciletuh, Karangsambung, and up until Meratus in Southeast Kalimantan. The Gede Volcanic Complex (GVC) and Salak Volcano of the Sunda island arc (West Java, Indonesia) are Quaternary volcanoes that lie geographically on the Early Cretaceous Sundaland boundary. An indication of crustal assimilation related to the Ciletuh Mélange complex has been observed by previous research. Therefore, this research intended to further investigate whether GVC and Salak are affected by that boundary through an igneous petrogenetic approach. This research uses geochemical data (major and trace elements) proceeded by various discrimination diagrams to account for the tectonic conditions of the Gede Volcanic Complex and Salak Volcano. Products from both GVC and Salak are all sub-alkalis rocks that came from active continental plate margins. Geochemical analysis shows that one metabasalt sample from Ciletuh Mélange Complex has the same characteristics to anomalies found at GVC by being an island arc tholeiite. Meanwhile, anomalies at Salak could be explained by its location being on top of the Meratus lineament that might contain granitic deposits.