Sulfur and lead isotope geochemical characteristics of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam, and their significance

Hung The Khuong,Nguyen Thi Hoang Linh,Pham Nhu Sang,Nguyen Thi Cuc,Ta Dinh Tung,Do Quoc Binh,Quach Duc Tin

doi:10.7494/geol.2021.47.3.143

Abstract

In northeastern Vietnam, the Khau Loc zone is considered to have high potential for lead-zinc mineralization. The lead isotope data for 18 galena samples and 18 ones of δ34S isotope data (including galena and pyrite samples) were collected from lead-zinc ore deposits in some areas in the Khau Loc zone, including Phia Dam, Khuoi Man, Ban Lin, Lung Dam, and Ta Pan. These were employed to investigate the sulfur and lead isotope geochemical characteristics of Pb-Zn deposits and their significance in this study. The samples were analyzed using the LA-ICP-MS to show that the Pb isotopic ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in the galena samples range from 17.8908 to 18.6012, 15.5794 to 16.1025, 38.4420 to 39.2118, with the average values of 18.296, 15.749, and 38.812, respectively. The pyrite and galena samples had the δ34S isotope, ranging from 9.0 to 15.106. The sulfur isotope systematics implies that most of the lead-zinc ore formations originated from marine sedimentary evaporation deposits and magmatic intrusion-volcanic eruption sources rich in silica. The distribution of lead isotopic ratios had a well-defined cluster for each deposit, indicating the formation of lead-zinc deposits and lower crust and orogen trends. In addition, these findings of lead isotopic ratios and δ 34S isotopes proved that the Khau Loc zone is an activated structure with continuous growth in continental crust thickness during the early Proterozoic and Cenozoic periods. Furthermore, the study results also presented the evolution of material sources involved in the formation of lead-zinc ores in the Khau Loc zone.

Highlights

In northeastern Vietnam, the Khau Loc zone is one with high potential for lead-zinc mineralization and has attracted considerable attention from geologists (Tri et al 2011, Hung et al 2020)
Most of the Pb-Zn deposits were found in the middle of the Khau Loc zone that is mainly restricted in the strata-bound brecciated dolostone (i.e., Du Tien, Lung Dam, Ta Pan, Ban Lin, Phieng Phat, and Yen Tho deposits), with minor terrigenous bearing quartz sediments (i.e., Ban Bo, Khuoi Man, and Phia Dam deposits) and rhyolite formation (i.e., Na Son deposit) (Duong 1990, Binh et al 2005, 2010, Bac 2011; Fig. 2)
The sulfur and lead isotopes of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam have been used to investigate the genesis of lead-zinc deposits and ore-forming material sources

Summary

Introduction

In northeastern Vietnam, the Khau Loc zone is one with high potential for lead-zinc mineralization and has attracted considerable attention from geologists (Tri et al 2011, Hung et al 2020). Most of the Pb-Zn deposits were found in the middle of the Khau Loc zone that is mainly restricted in the strata-bound brecciated dolostone (i.e., Du Tien, Lung Dam, Ta Pan, Ban Lin, Phieng Phat, and Yen Tho deposits), with minor terrigenous bearing quartz sediments (i.e., Ban Bo, Khuoi Man, and Phia Dam deposits) and rhyolite formation (i.e., Na Son deposit) (Duong 1990, Binh et al 2005, 2010, Bac 2011; Fig. 2).

Results

Conclusion