Influence of continental crust in the magmatic process in the Sunda - Tangkubanperahu Volcanic Complex, West Java, Indonesia Keisha Prillia Qayyima (a*), I G.B. Eddy Sucipta (b), Kurnaemi Fadelia Hasan (c), Idham Andri Kurniawan (b), Mirzam Abdurrachman (b), Asep Saepuloh (b), Very Susanto (b), Muhammad Rais Abdillah (d)
a) Department of Geological Engineering, Bandung Institute of Technology, Jl. Ganesha No. 10, Bandung 40132, Indonesia
* keishapq[at]hotmail.com
b) Petrology, Volcanology, and Geochemistry Research Group, Department of Geological Engineering, Bandung Institute of Technology, Jl. Ganesha No. 10, Bandung 40132, Indonesia
c) Laboratory of SEM-EDS UPP Chevron, Bandung Institute of Technology, Jl. Ganesha No. 10, Bandung 40132, Indonesia
d) Atmospheric Science Research Group, Department of Meteorology, Bandung Institute of Technology, Jl. Ganesha No. 10, Bandung 40132, Indonesia
Abstract
The Sunda Arc may possibly be one of the most complex volcanic systems in the world. While it is thought to result from the convergence between the Indo-Australian Plate and the Eurasian Plate, the understanding of the characteristics of the underlying crust, however, is still an enigma. This research was carried out to comprehend the characteristics of this arc. One of the volcanoes comprising this arc is the Sunda - Tangkubanperahu Volcanic Complex, in West Java. This volcanic complex consists of Sunda Volcano, Bukittunggul - Manglayang Cone Complex, and Tangkubanperahu Volcano. Analyses of the lava showed medium to high K calc-alkaline affinity in SiO2 vs. K2O diagram, but generally tholeiitic in SiO2 vs. FeO*/MgO diagram. The difference in affinity is due to the relative Fe enrichment in the majority of the samples, most notably in the Tangkubanperahu Volcano products. The abundance of K is accompanied by the enrichment of other incompatible elements such as Sr, Rb, Ba, Th, and Ce, also depletion in Ta, Nb, Zr, Hf, Ti, Y, and Yb, using MORB as a standard. These geochemical signatures indicate a possible (continental) crustal contamination during the magmatic processes. Other tectonic setting classifications using trace elements support that this volcanic complex is an active continental margin. The primary magmatic source is the melting of the oceanic crust of the Indo-Australian Plate, followed by a crustal contamination (continental crust fragment) during its activity. The parent magma undergoes three distinct differentiation processes, with a magma mixing playing a significant role before eruption.
Keywords: Sunda - Tangkubanperahu Volcanic Complex- magmatic process- crustal contamination
