Sm–Nd Isochron Age Constraints of Au and Sb Mineralization in Southwestern Guizhou Province, China

Zepeng Wang,Chengfu Yang,Qinping Tan,Yong Xia,Qiquan Pan,Xiaoyong Wang,Faen Chen,Dafu Wang,Junhai Li,Jianzhong Liu,Songtao Li

doi:10.3390/min11020100

Abstract

Southwestern Guizhou, China, is famous for hosting clusters of Carlin-type Au, Sb, and Hg-Tl deposits. These deposits are thought to be the products of a low-temperature hydrothermal metallogenic event. Calcite and fluorite are common and widespread gangue minerals in Au and Sb deposits, respectively. Ore-related calcite commonly coexists with stibnite, realgar, and orpiment at the periphery of high-grade orebodies in Au deposits, while ore-related fluorite is generally intergrown with stibnite in Sb deposits. In this study, ore-related calcite and fluorite samples from representative Au (Zimudang) and Sb (Dachang) deposits, respectively, were separated, and the rare earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm–Nd isochron ages were analyzed. This study aims to determine the formation ages of the calcite and fluorite and to constrain the age of low-temperature metallogenic event in Southwestern Guizhou. The calcite and fluorite samples contain relatively high total concentrations of REEs (8.21–22.5 μg/g for calcite, 21.7–36.6 μg/g for fluorite), exhibit variable Sm/Nd ratios (0.51–1.01 for calcite, 0.35–0.49 for fluorite), and yield Sm–Nd isochron ages of 148.4 ± 4.8 and 141 ± 20 Ma, respectively. These ages are consistent with the age range constrained by the low-temperature thermochronology of zircon (132–160 Ma), crosscutting relationships of stratigraphy or intrusions (96–160 Ma), and previous dating results (135–150 Ma) in Southwestern Guizhou. Collectively, the ages obtained in this study add new evidence to previous geochronology studies, such that the low-temperature hydrothermal mineralization in Southwestern Guizhou can be constrained to 135–150 Ma, corresponding to the Yanshanian orogeny, which was associated with a weak extensional tectonic environment.

Highlights

The Youjiang basin hosts clusters of Carlin-type Au, Sb, and Hg-Tl deposits (Figure 1)[1,2,3,4,5,6,7,8], such that it is the second largest low-temperature Carlin-type Au mineralized area in the world, after Nevada, USA [9,10,11,12,13]
The Au and Sb deposits in the Youjiang Basin are primarily located within Southwestern Guizhou and account for more than 70% of the deposits and endowments
Accurate geochronology is a crucial tool for understanding the genesis of ore deposits

Summary

Introduction

The Youjiang basin hosts clusters of Carlin-type Au, Sb, and Hg-Tl deposits (Figure 1). Many studies have reported ages for Au and Sb deposits in Southwestern Guizhou, but the true ages remain controversial because the results span a large age interval, i.e., 235–195 [14,15], 135–150 [16,17,18,19,20], and Minerals 2021, 1813, –x1F0O6R MPEEaR[2R1EV,2IE2W]. This uncertainty hampers our understanding of the genesis of Au and.

La Ce Pr Nd

AAuu aanndd SSbb MMeettaallllooggeennicc Age in Southwestern Guizhou

Findings

Conclusions