Field Characteristic of Metamorphic-Hosted Gold Deposit in Sulawesi, Indonesia: An insight into Awak Mas Prospect, South Sulawesi

Abstract

Metamorphic-hosted gold deposit is found in Awak Mas, South Sulawesi. This area is characterized by mountainous topography in the western part and relatively flat area in the eastern part and consists of Pre-Tertiary, Tertiary and and Quaternary rocks. Some samples including host-rock, basement and quartz vein were collected and observed during 4 days field work. Mineralization is recognized by the occurrence of pyrite and irregular body of silicified breccia vein. Two main styles of mineralization consists of 1) broad and shallow-dipping zones of sheeted and stockwork quartz veining and associated alteration that conform to the shear fabric, especially within the dark, graphitic mudstones; 2) steeper dipping zones of quartz veining and breccias associated with high-angle faults cutting both the flyschoid cover sequence and basement metamorphic rocks. Gold mineralization is considered as mesothermal deposit which is characterized by albite-pyrite-silica-carbonate alteration overprinted the ductile fabric associated with deformation and metamorphism. The gold is commonly hosted within the flysch sequence and associated with abundant quartz veining and silica albite-pyrite alteration. However, the association of gold and quartz is not ubiquitous and some vein zones are locally barren of mineralization.