STUDY OF SOIL GEOCHEMICAL AND MINERALOGY OF THE SITE OF A LAND MOVEMENT AT TALAGASARI VILLAGE, KAWALI DISTRICT, CIAMIS REGENCY

• Main Author: Shiddiq Abdussalam, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/72183
• Institution: Institut Teknologi Bandung

Talagasari Village, Kawali District, Ciamis Regency is an area that experiences frequent land movement events. In early 2021, such events caused houses to crack and even collapse, roads to sink, and fishponds to crack. The soil properties that lead to soil movement, such as high plasticity, good water-binding ability, and cracking if it dries out, can be attributed to clay minerals’ geochemical and mineralogical characteristics. This study aims to identify the causes of soil having specific characteristics that cause ground movement in the area. Andosol soil samples from horizons A and B were collected from the ground movement area. The samples were prepared through drying, coning and quartering, grinding, and sieving (200 mesh). X-ray diffraction analysis was performed for mineral identification, and X-ray fluorescence analysis was performed to identify geochemical composition. The study results showed that the commonly encountered minerals in the soil were kaolinite (13–83%), cristobalite, and muscovite, while other minerals found were dickite, gibbsite, and magnetite. The presence of kaolinite and gibbsite is thought to be the result of further weathering of old parent material affected by heavy rainfall. The major dominant oxides are SiO2 (38–54,7%), Al2O3 (33,5–49,2%), and Fe2O3 (9,88–15,7%). Additionally, TiO2, K2O, MgO, P2O5, MnO, Na2O, ZrO2, V2O5, Cr2O3, SrO, NiO, Cl, SO3, CaO, CuO, ZnO, Ga2O3, and Rh2O3 were also found. The presence of Fe2O3 is thought to affect the reddish color of the soil. Based on these findings, it is suggested that the soil conditions dominated by kaolinite clay minerals, which are loose at the top and somewhat firm at the bottom, relatively steep slopes, land loading at high elevations, and heavy rains for several days favor land movement in the area.