Bulletin of the Geological Society of Malaysia, Volume 80, November 2025, pp. 119 – 131
Mineralisation styles and sulfur isotopes of the Kon Ra Cu-Au deposits, Kon Tum Massif: Implication for deep mineralisation potential
Truong Xuan Le*,1,2, Khang Quang Luong1, Thanh Xuan Ngo1, Dzung My Tran3, Charles Makoundi4
1 Faculty of Geosciences and Geoengineering / Economic Geology and Sustainable Development Research Team (EGSD), Hanoi University of Mining and Geology, 18 Vien St, Dong Ngac, Hanoi, Vietnam
2 Centre for Excellence in Analysis and Experiment, Hanoi University of Mining and Geology, 18 Vien St, Dong Ngac, Hanoi, Vietnam
3 Vietnam Department of Geology and Minerals, 6 Phạm Ngu Lao, Phan Chu Trinh, Hoan Kiem, Hanoi, Vietnam
4 CODES Centre of Ore Deposits and Earth Sciences, University of Tasmania, Private Bag 126, Hobart, Tasmania 7001, Australia
* Corresponding author email address: lexuantruong@humg.edu.vn
Abstract: The Kon Ra Cu-Au deposit is located in the central Kon Tum Massif, a region renowned for its geological complexity and metallogenic significance in Southeast Asia. This deposit is a notable example of skarn mineralisation, hosted within the Neoproterozoic Kham Duc sequence of metamorphic rocks, including pyroxenite, amphibolite and metacarbonates, which have been intruded by Ordovician-Silurian and Permian-Triassic magmatic events. Detailed core logging and field investigations have identified multi-stage mineralisation, including pre-ore, syn-ore, and post-ore phases. Pre-ore metasomatism is characterised by skarn formation dominated by pyroxene, amphibole, and magnetite, with minimal garnet, suggesting a distal setting relative to intrusion contacts. During the syn-ore stage, retrograde metasomatism facilitated hydrothermal fluid activity, resulting in the precipitation of chalcopyrite, pyrite, and pyrrhotite alongside altered minerals such as quartz, actinolite, epidote, chlorite, sericite and carbonate. The common ore textures include disseminated, patchy and stockwork forms with localized fabric-aligned magnetite corresponding to the S1 foliation of the host rocks. The δ³⁴S values of the ore-bearing stages ranging from -7.3‰ to 0.31‰, indicate a predominantly magmatic sulfur source with possible minor contribution from sedimentary host rocks. While Re-Os molybdenite dating is still pending, the timing of mineralisation is assumed by a ~3 m-wide hornblende-bearing granite dyke associated with skarn alteration. This dyke is interpreted to be correlated with the Ordovician-Silurian Dien Binh or the younger Permian-Early Triassic Ben Giang-Que Son intrusion in the vicinity.
Keywords: Kon Ra, Kon Tum Massif, Cu-Au mineralisation, sulfur isotope, U-Pb apatite, Ordovician-Silurian
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Manuscript received 3 January 2025;
Received in revised form 28 March 2025;
Accepted 9 June 2025
Available online 28 November 2025
https://doi.org/10.7186/bgsm80202509
0126-6187; 2637-109X / Published by the Geological Society of Malaysia.
© 2025 by the Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC-BY) License 4.0.
