ALTERASI DAN MINERALISASI CONTO BATUAN SUMUR SGD 01, SGD 03, DAN SGD 04 DAERAH SELODONG, LOMBOK BARAT NUSA TENGGARA BARAT

• Main Author: Didit Haryanto, Agus
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/5030
• Institution: Institut Teknologi Bandung

<b>Abstract:<p align="justify"> <br /> The Selodong area is located in Central Sekotong, West Lombok, Nusa Tenggara Barat province. The investigation based on core samples from Well SGD 01, SGD 03, and SGD 04, PT Newmont Nusa Tenggara. The method of analysis have been done using petrography, mineragraphy, and PIMA. <br /> <br /> There are five strong-intensive altered lithologies of these wells, consist of volcanic breccia, fault breccia, dacite and andesite volcanics, and microdiorite intrusive rocks. Alteration occuring in the Selodong area can be classified into four groups of mineral assemblages. Actinolite+biotite+K-feldspar zone (temperature >300 °C, pH neutral), illite+sericite+quartz zone (temperature 230-400 °C, pH near-neutral), Illite+chlorite+epidote zone (temperature 200-300 °C, pH near-neutral), and illite+smectite+quartz zona (temperature < 230 °C, pH acid). Mineralization in Selodong area dominated by dissemination of pyritechalcopyrite associated with covelit, chalcocite, and limonite. <br /> <br /> Based on mineral assemblage paragenesis, texture and structure of mineralisation, it is concluded that alteration and mineralization processes in the Selodong area might be occurred in porphyry system which correlate with type of high sulphidation epithermal.