GEOCHEMISTRY OF MAJOR AND TRACE ELEMENTS FROM QUARTERNARY VOLCANOES IN JAVA ISLANDS

• Main Author: Chrysant Sekar Arum , Regina
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/23874
• Institution: Institut Teknologi Bandung

Java island is located at the south part of Indonesia with 5o56’41” – 8o50’23” S and 105o14’15” – 114o39’47” E as geographic coordinate, close to the boundary between Australia plate and Eurasia plate. Writer approached this study with learn how the geochemical relation works from volcanic rocks to know some factor that effected and controlled the distribution of Quarternary volcanic in Java. Study area is divided into three parts such as west, center, and east of Java. Writer used major and trace elements of volcanic rocks from previously study by another researcher. The abundances of elements in eighteen volcanoes normalized at SiO2 = 55%. Early identification for the series of magma from the studied volcanoes showed us that there are tholleite, calc alkaline, calc alkaline high-K, and shoshonite series. The analysis of normalization from major and trace elements shows us that the abundaces of K2O and Sr increased gradually with the distance from trench while MnO decreased. Other elements content also increase and decrease gradually on their own environment as a part of Java. However, for the center part, there is no reduction in abundances for trace elements. Furthermore, for lateral variation (from west to east), K2O, TiO2, Fe2O3, MnO, MgO, Cr, and Ni tend to decrease while Al2O3, P2O5, CaO, Na2O, Sr, Ba, Th, Y Zr, Nb increase. Distribution of major and trace elements affected by variant subduction angle which tend to become bigger to the east, crustal thickness that become thinner to the east, and crustal contamination derived from upper crust dominantly, also recycling of subducted sediments.