Low sulfidation epithermal gold mineralization at Tambang Sawah, Lebong, Bengkulu Province, Indonesia

Abstract

The Tambang Sawah area, Lebong, Bengkulu Province, is geologically located in the Barisan mountain range and the Sumatran fault zone and is composed of igneous rocks of the Sunda – Banda magmatic arc. This study is aimed to elucidate geological framework and characteristics of the low sulfidation epithermal gold at Tambang Sawah. Gold mineralization is hosted by the lithology of granite and andesitic breccia rocks, and controlled by faults, especially the Ketahun fault which forms a fracture and extensional zone. Hydrothermal fluid filled the structure found to form gold-bearing quartz veins. Hydrothermal alteration recognized at the study area is a typical type of alteration found in epithermal gold deposits, namely, argillic, silicified and propylitic. The characteristic sulfide minerals are low sulfidation epithermal gold deposits in the Sawah Mine area which are found, pyrite, chalcopyrite, covelite, sphalerite and galena with vein textures of colloform banded, cockade-crustiform, moss, and brecciated texture. Gold is interpreted to be coevally deposited with sulfides within quartz veins. Gold grade in rocks and veins varies from 0.07 ppm to 21.3 ppm.