Sulfidation and gold precipitation in the Jugan gold deposit in Bau, Sarawak, East Malaysia: Insights from correlation plots and factor analysis

Villareal-Tirona, Aubrey Marie and Balangue-Tarriela, Maria Ines Rosana and Shaw, Ray (2022) Sulfidation and gold precipitation in the Jugan gold deposit in Bau, Sarawak, East Malaysia: Insights from correlation plots and factor analysis. Bulletin of the Geological Society of Malaysia (74). pp. 55-67. ISSN 2637-109X

Abstract

The Jugan Gold Deposit (JGD) is part of the Bau Mineral District (BMD) in Bau, Sarawak, East Malaysia. Although the mineral district is well studied, limited studies were conducted on the JGD. This paper presents the results of statistical studies using the multi-element geochemical data emphasizing the trace elements association with gold, alteration- mineralization, and the precipitation mechanism of the gold-bearing sulfide minerals. The correlation matrix displays positive correlation associations, particularly those associated with gold mineralization, i.e., arsenic, sulfur, antimony, and bismuth. Factor analysis grouped the trace elements into eight factors that reflect lithologies, mineralization, alteration, and geological processes in the JGD. Elements comprising the gold mineralization assemblage have the most significant factor (Factor 1) with the highest variance. The mineral assemblage was enriched during the alteration-mineralization process, as confirmed by the isocon plot. The barren samples (<0.01g/t) and gold-bearing samples (>0.2 g/t) plotted in a Fe vs. S diagram indicate that sulfidation is the precipitation mechanism of gold-bearing sulfide minerals. The immobility of iron and the vertical trajectory trend in the Fe vs. S diagram suggest that the possible source of Fe for gold-bearing sulfide minerals is the sedimentary host rock. Collectively, characteristics such as (1) the association of gold-bearing sulfide minerals with carbonate mineral assemblage and (2) high bismuth loadings on the main mineralization stage suggest a distinct geochemical characteristic of JGD relative to both Carlin-type deposits (CTD) and Carlin-like deposits (CLD); hence it is inferred to be a sedimentary-hosted gold deposit (SHGD). Establishing the JGD characteristics will contribute to a better understanding of the deposit and the BMD. Exploration-wise, it will assist future exploration work in delineating Au mineralization zones.

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