GEOLOGY AND MINERALIZATION OF ADA RAYE AREA, MOUNT SERUYUNG, SEBUKU SUBDISTRICT, NUNUKAN DISTRICT, NORTH KALIMANTAN PROVINCE

• Main Author: Kusuma Ayu, Adelia
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/20715
• Institution: Institut Teknologi Bandung

The study was conducted in Ada Raye area, an eastern block of mining concession belongs to PT. J Resources, which is located in Mount Seruyung, Subdistrict Sebuku, District Nunukan, North Kalimantan Province, with 500 x 500 m2 in total area. The area is geographically located at 526904-527404 mN and 431791-432291 mE (UTM Zone 50 N). The objective of the research is to identify the geological properties and mineralization process in the area. Research methods were consist of field mapping, borehole logging, and laboratory analysis such as petrography, mineragraphy, XRD, and Fire Assay. From the results of the research, lithology units that were identified in the area are andesite, lapilli tuff, lithic tuff, and crystal tuff formed in Pliocene-Pleistocene. Geological structure developed in the area is NE-SW fault. Lithology in the Ada Ada Raye mostly have been altered. Based on its alteration minerals association, there are three zones of alteration in Ada Raye, such as silica zone, quartz-alunite zone, and kaolinite-montmorillonit-alunite zone. The alteration occurred at pH 4-5 and temperature 100-200oC. The alteration pattern controlled by the fault and by the permeable lithology like tuff. The alteration characteristics are indicating that the area is in epithermal system. Analyzing from the alteration minerals association, alteration pattern, vuggy texture, ore minerals found in the area (such as covellite and enargite), the deposit type in Ada Raye is a high sulphidation epithermal system. Gold mineralization is associated with silica zone alteration which its pattern controlled by the fault structure and permeable lithology as the center of hydrothermal fluid pathway.