GEOCHEMICAL STUDY OF NICKEL LATERITE DEPOSITS AND THE PRESENCE OF RARE EARTH ELEMENT (REE) IN NORTH KONAWE, SOUTHEAST SULAWESI PROVINCE

• Main Author: Manatap Manurung, Kevin
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/69838
• Institution: Institut Teknologi Bandung

Laterite is the product of intense weathering in humid and tropical climates for a long time that is associated with chemical weathering, groundwater levels fluctuation, and secondary enrichment. Laterite deposits can produce commodities such as Ni, Fe, Al, Mn, Co, Au, and rare earth element (REE). The study area is located in North Konawe, Southeast Sulawesi Province with an area of ±231 km2 and bounded in the extent of 393851 – 411714 mE and 9609622 – 9622586 mN zone 51S with WGS1984 datum. The study area is formed from continental pieces of Southeast Sulawesi and oceanic crust with nickel laterite deposit is the product of weathered ultramafic rocks. This study aims to determine the geological conditions and characteristics of nickel laterite deposits and their correlation with the abundance of REE associated with topographic and lithological factors. The used data are secondary data from articles such as X-Ray Fluorescence (XRF) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) from 4 nickel laterite deposit locations (Asera, Andowia, Wawolimbue, and Marombo) and 7 bedrock locations. This study uses element diagrams and Spearman correlation. By that analysis, it is estimated that there are two different bedrocks in laterite nickel deposits, lerzolite and olivine websterite. Weathering of rocks in the study area form top soil, limonite, and saprolite zones with the bedrock zone is not exposed. There are differences in the abundance of elements based on lithology with the highest abundance of Fe2O3, MnO, Cr2O3, and NiO come from lherzolite. Based on the lithology, it is also estimated that the pH and Eh in nickel laterite deposits are different. It is estimated that nickel laterite with lherzolite bedrock has a pH of 7-9 and nickel laterite with olivine websterite bedrock has a pH of 4-7 with both in an oxidizing condition. In general, Ni is enriched in the saprolite zone while REE is enriched in the limonite zone. Based on the Spearman correlation analysis, REE has a positive correlation with Al2O3, Fe2O3, Cr2O3, TiO2, and MnO.