The role of geological factors in controlling primary gold ore in the Tam Ky - Phuoc Son belt

Abstract

The Tam Ky - Phuoc Son belt is one of the potential metallogenic structure in Southeast Asia, hosting numerous hydrothermal gold deposits and occurrences, including explored and mined ones.             To enhance the efficiency of geological surveys and exploration for hydrothermal gold ore in this region, studying the role of mineralisation constraints is crucial. This research helps define key indicators for mineral prospecting and explore the potential of gold deposits in the Tam Ky - Phuoc Son belt.

Research findings indicate that the sub-atitude fault system, tensional fractures associated with strike - slip faults, and northwest-southeast trending shear zones are favorable pathways and traps for the ore deposition. The gold ore in the Tam Ky - Phuoc Son belt is not genetically related to the granitoids of the Ba Na Complex. Instead, it was formed in a post-orogenic setting just after the Indosinian orogeny and younger than the granitoid formations of the Ba Na Complex. In terms of lithostratigraphic constraint, hydrothermal gold mineralization in the study area is primarily influenced by the Kham Duc Formation, which consists of quartz - plagioclase - biotite schist, biotite gneiss, biotite -hornblende gneiss, quartz - biotite schist, plagioclase - hornblende - biotite schist, amphibolite, muscovite - garnet gneiss, and other rock types. The main units hosting gold mineralization include biotite gneiss and plagioclase - gneiss - amphibolite. Hydrothermal alteration associated with the mineralisation, including sericitization, chloritization, epidotization, beresitization, and argillization, played a significant role in ore formation in this region.