ALTERASI DAN MINERALISASI BERDASARKAN TUJUH SUMUR BOR PADA PROSPEK TOR ULUALA, KECAMATAN BATANGTORU, KABUPATEN TAPANULI SELATAN, PROVINSI SUMATRA UTARA

• Main Author: Ash-Shiddieqi, Hasbi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/56477
• Institution: Institut Teknologi Bandung

The research location is administratively located in Aek Pining Village, Batangtoru Subdistrict, South Tapanuli, North Sumatra Province, and geographically located at 507.050–507.400 mE dan 167.400–169.600 mN. Tor uluala prospect is one of the contract of work area of PT Agincourt Resources that is currently in exploration phase. This research aim to determine geological condition, hydrotermal alteration, mineralization, dan association relationship of Au, Ag, Cu, and As. Some methods used to answer the objectives such as detailed bore cores logging from 7 different wells, petrographic analysis of 9 samples, mineragraphic analysis of 9 samples, clay mineral analysis with ASD (Analytical Spectral Device), and data analysis of assay Au, Ag, Cu, As, and SCIS (Sulphur Content in Sulphide). Lithostratifraphic units of research area consist of two units, ther are Hornblende Andesit Unit and Sandy Matrix Breccia Unit. Both of them are pervasively altered. Alteration zoning in the research area, based on its mineral assemblage, can be divided into five zones, Vuggy-Massive Silica Zone, Alunite – Dickite ± Quartz ± Kaolinite Zone, Dickite – Kaolinite ± Quartz Zone, Smectite/Illite – Kaolinite ± Smectite ± Quartz, and Illite – Kaolinite ± Quartz. Mineralization in the form of enrichment of Au-Ag-Cu-As element is related to the high sulphidation epithermal system and is associated with Vuggy-Massive Silica Zone. The sulfide ore minerals consist of pyrite, enargite, covellite associated with hypogenous mineralization. Placement of Sandy Matrix Breccia Unit, hydrothermal alteration process, and mineralization are controlled by geological structure fault with NNE orientation which are interpreted as normal faults. Based on the results of data analysis, it was concluded that the deposition of gold was related to the formation of enargite.