Chemical element analysis of Arjuno-Welirang igneous rocks

Mount Arjuno-Welirang has a geological structure consisting of volcanic breccia, lava, tufan breccia, and tuff. This research focuses on exploring the chemical content of Arjuno-Welirang igneous rocks. The mapping of chemical element content is carried out to provide information on the distribution of Arjuno-Welirang dominant elements which are very important for exploitation and industry. The results of X-ray fluorescence (XRF) analysis of seven igneous rock samples showed that there were Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Sr, Ba, Eu, and Re. The dominant elements (Wt% > 10%) are Si (44.4-51.6%), Al (14-19%), Ca (12.1-17.1%), and Fe (12.4-20.4%). In addition, rare earth element REE europium (Eu) content was also found with an average of 0.23 Wt%. The discovery of REE Eu indicates the presence of other REE elements and needs further analysis. The presence of several oxide elements SiO₂ and K₂O was compared to the surrounding mountains, where SiO₂ indicates a greater content of Bromo-Semeru, while K₂O is larger than Semeru and smaller than Bromo. This provides an overview of the difference in magma properties, where the results of Arjuno-Welirang igneous rock analysis show alkaline properties while Bromo-Semeru ultrabase. The Fe₂O₃ content of Arjuno-Welirang shows a smaller tendency than Bromo-Semeru. This shows that Arjuno-Welirang magma is magnetically higher than Bromo-Semeru. The average depth of magma from igneous rocks is calculated between ± 147.7 and ± 225.1 km below the earth's surface. These results correlate significantly with K₂O compounds where the deeper the magma origin of the sample, the higher the K₂O content.