Sm-Nd Dating and In-Situ LA-ICP-MS Trace Element Analyses of Scheelite from the Longshan Sb-Au Deposit, Xiangzhong Metallogenic Province, South China

Zhiyuan Zhang,Wengang Liu,Wei Li,Guiqing Xie,Jingwen Mao,Paul Olin

doi:10.3390/min9020087

Zhiyuan Zhang, Wengang Liu + Show 4 more

Open Access

https://doi.org/10.3390/min9020087

Copy DOI

Abstract

Longshan is an important Sb-Au ore deposit (3.7 Mt @4.5 wt. % Sb and 4.6 g/t Au) in the Xiangzhong metallogenic province (XZMP), South China. In the present work, trace element composition, Sm-Nd isotope dating, and Sr isotope of scheelite from the Longshan Sb-Au deposit are used to constrain the genesis of the deposit. Based on mineral assemblages and geological characteristics, two types of scheelites can be distinguished (Sch1 and Sch2). Sch1 is granular and cemented by stibnite, while Sch2 is commonly present in stibnite, pyrite, calcite, and quartz veins, indicating that Sch2 is later than Sch1. The Sm-Nd isochron age defined by Sch1 is 210 ± 2 Ma (MSWD = 1.0, n = 4). This age is interpreted as the age of Sb-Au mineralization and overlaps with the 201–228 Ma granitic rocks in the XZMP. Sch1 exhibits high ΣREE + Y contents (43.5 to 104 ppm), low Sr values (2687 to 6318 ppm, average of 4018 ppm), and a narrow range of 87Sr/86Sr values (0.7209 to 0.7210, average of 0.7209). In contrast, the elevated Sr abundance (4525 to 11,040 ppm, average of 6874 ppm) and wide 87Sr/86Sr ratios (0.7209 to 0.7228, average of 0.7214) in Sch2 were possibly caused by fluid-rock interaction mixing with Sr-enriched basement rocks. Sulfides have a narrow range of δ34S values of −1.8‰ to 3.2‰, with an average value of 1.1‰ (n = 7). Geochronological, geochemical and isotopic data suggest that the Longshan Sb-Au deposit is possible genetically related to the Late Triassic granitic intrusion in the XZMP.

Highlights

Scheelite (CaWO4 ) is a common accessory mineral that occurs in many gold deposits hosted by metamorphic rocks
A total of 38 LA-inductively-coupled plasma mass spectrometer (ICP-MS) rare earth elements (REEs) analyses were carried out on four samples of scheelite from the Longshan Sb-Au deposit, and the results are presented in Tables 1 and 2
Considering that all Sch1 samples were collected from the same ore vein and should be regarded as products of the same hydrothermal event, the scheelite is chemically and should be regarded as products of the same hydrothermal event, the scheelite is chemically homogeneous (Figure 8) and the variation range of the calculated εNd(t) for Sch1 is relatively narrow homogeneous (Figure 8) and the variation range of the calculated εNd(t) for Sch1 is relatively narrow

Summary

Introduction

Scheelite (CaWO4 ) is a common accessory mineral that occurs in many gold deposits hosted by metamorphic rocks. The Sm-Nd isotopes of scheelite can potentially be a powerful geochronometer for dating gold deposits [7,8,9,10,11,12,13]. Due to their similar electron configurations and ionic radii, elements such as rare earth elements (REEs), Sr and. The REE composition of scheelite can provide information about the source and mineralization conditions of ore-forming fluids [4,15,19,20,21]

Methods

Results

Conclusion