Magnetic characterization of soil to determine the source origin. Case study: Soil around Bromo Volcano, Tengger Volcanic Complex

Abstract

The research on soil characteristics is very important in Indonesia. Indonesia is a well-known country for its volcanoes in the world. Many lush areas around the volcano are still active. One of the famous and still active volcanic complexes is the Tengger Volcanic Complex. The aim of this research is to analyze the magnetic characteristic of four volcanic soils around Bromo Volcano. The sample consists of soil from Gubug Glakah (GGK), Ngadirejo (NDJ), Nongko Jajar (NKJ), and Waringinanom (WAN) Village. Rock magnetism method combine with geochemical analysis are applied in this study. The results of this research are a significant difference in magnetic susceptibility value of WAN soil (1976.4 × 10-8 m3/kg) with magnetic susceptibility value of three other soils (between 900-1200 × 10-8 m3 / kg). Meanwhile, X-Ray Fluorescence (XRF) analysis showed that FeO concentration on WAN soil was lower than other soils. This indicates that the concentration of magnetite minerals (Fe3O4) on WAN soil is higher than other soils. The difference of magnetite mineral concentrations in the soil may be due to difference sources. Based on these results, it is concluded that WAN soil may not come from a similar source. This study still needs further research.