Supergene enrichment-dominated gold mineralization in the Phayaung Taung deposit, Myanmar

초록

The Phayaung Taung gold deposit is situated within the Late Proterozoic Chaung Magyi Group, located in the southern segment of the Mogok Metamorphic Belt (MMB), also recognized as the Mergui Belt (MB). The fluid inclusion data indicates that the deposit is from an orogenic origin with the salinity range of 3.4 wt% to 12.9 wt% NaCl equivalent and the homogenization temperature of 218.0 degrees C to 450.0 degrees C for the bi-phase liquid-rich fluid inclusions. And it shows local upgrading of gold mineralization by supergene enrichment processes in which gold occurs with the secondary sulfide minerals, such as digenite, djurleite, stromeyerite, covellite, etc. Gold initially precipitated during hypogene mineralization within the orogenic system was subsequently remobilized in acidic aqueous solutions, formed by the oxidation of primary sulfide minerals by meteoric water. Gold occurs in the quartzite and phyllite units but major mineralization is concentrated within the quartzite units, owing to the inherently brittle nature of quartzite. This brittleness enhances its susceptibility to fracturing, thereby facilitating the formation of conduits for ore-bearing fluids. Consequently, the lithological interface between quartzite and phyllite units represents a significant target for gold exploration. Primary copper sulfide minerals, such as chalcopyrite and bornite, have been economically upgraded to more copper-rich secondary sulfide minerals like covellite, digenite, and djurleite. Therefore, at the Phayaung Taung deposit, the recovery of copper should be strategically considered as a by-product alongside gold extraction. This comprehensive understanding of the deposit's characteristics and mineralization mechanisms is crucial for developing effective exploration strategies and evaluating economic viability.

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