GEOCHEMICAL CHARACTERISTICS OF WEATHERING PRODUCTS IN GRANITOID ROCKS AND RARE EARTH ELEMENTS IN PARMONANGAN AREA, NORTH TAPANULI

• Main Author: Nurul Hidayati, Ana
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/69752
• Institution: Institut Teknologi Bandung

Technology has developed quite rapidly, especially in the 20th century. High technology uses rare earth elements (REE) as supporting material for a technology. The General Exploration Team (2011) has investigated the REE content of weathered granitoid at Parmonangan and found several significant elements such as Ce (600 – 1400 ppm), La (400 – 1000 ppm), and Pr (600 – 1400 ppm) which have areas the anomaly is to the west of the area. Therefore, REE exploration needs to be carried out west of the research location in 2011. This study aims to determine the characteristics of granitoid, weathering patterns, and REE content profiles in the Parmonangan area, North Tapanuli. The data used are petrography, drill descriptions, and geochemical data. Petrographic data consists of 7 samples. Geochemical data consists of XRF (X-Ray Fluorescence) data (15 rock samples and 164 weathered samples) and ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) (2 rock samples and 20 weathered samples). The weathering of granitoid in the Parmonangan area comes from biotite granite and hornblende biotite granite. The geochemical characteristics of weathering results, namely Na2O, CaO, K2O, SiO2, P2O5, and MnO are soluble and mobile during weathering, indicating a decrease in the soil to bedrock. Meanwhile, Al2O3, Fe2O3, TiO2, and LOI showed an increase in the weathering results. Al2O3, Fe2O3, and TiO2 underwent residual enrichment. The content of the weathered granitoid in the Parmonangan area shows the relative enrichment of ????LREE to ????HREE. The content of ????LREE is influenced by the distribution of lanthanum and cerium elements contained in monazite minerals. The content of ????HREE is controlled by the distribution of the element yttrium. Based on the Spearman correlation, the minerals titanite and apatite also affect the abundance of ????LREE. While the carrier mineral for HREE is zircon. Sampling was in the REE washing zone so that the concentration of REE obtained in the soil was lower than the bedrock.