Typomorphic Characteristics of Gold-Bearing Pyrite and Its Genetic Implications for the Fang’an Gold Deposit, the Bengbu Uplift, Eastern China

Abstract

The Fang’an quartz-vein gold deposit is located in the eastern part of the Bengbu uplift. The eastern part of the Bengbu uplift is considered to be the western extension of the Zhaoyuan gold mineralization zone in the Jiaodong area of Shandong Province and has huge mineralization potential. The Fang’an deposit was a newly discovered, small-sized gold deposit, and the research in the area is relatively weak. In this study, samples of quartz-vein type ore were collected from the ZK141, ZK1549, and ZK1665 drill holes of the Fang’an gold deposit. Based on the study of the geological characteristics, the major and trace elements of pyrite in different stages were analyzed by electron probe microanalyzer (EPMA), to explore the compositional characteristics of pyrite, the occurrence of gold, and the source of ore-forming fluid. The studies indicate that the deposit experienced four ore-forming stages: the quartz stage, the quartz-pyrite stage, the polymetallic sulfide stage, and the carbonate stage. The pyrites are grouped into three stages, corresponding to the first three ore-forming stages. The EPMA analyses showed that the major elements of pyrite were high Fe and low S, indicating that the formation was hydrothermal. The high content of Ni indicated that the metallogenic materials were derived from between the mantle and the lower crust. The general Co/Ni ratio of >1, with an average of 5.34, indicated that the ore-forming fluid was derived from the magmatic–hydrothermal fluid and wall rock. The Fang’an gold deposit mainly contains nano-gold.

Geology, fluid inclusions, mineral and (S-O) isotope chemistry of the Badran orogenic Au deposit, Yana-Kolyma belt, eastern Siberia: implications for ore genesis

“…Such negatively charged pyrite according to data (Large and Maslennikov, 2020) mainly attracts gold. For most of the analyzed grains, Co/Ni>1, which according to (Zhang et al, 2014;Roman et al, 2019) is characteristic of hydrothermal fluids (Figure 8A). Considering the As-Co-Ni system, it is possible to judge the conditions of pyrite formation.…”

Rb–Sr Pyrite Dating and S–Pb Isotopes in the Fang’an Gold Deposit, Wuhe Area, Eastern Anhui Province

“…A combination of drill core observation and microscopic analysis was used to determine mineral assemblages, structures, texture, and crosscutting relationships between ore veins. The detailed paragenesis was described by Wang et al (2022) [16]. Four stages of mineralization were noted in the Fang'an deposit (Figure 5), including the quartz-sericite stage (I), which is defined by sericite-quartz altered rocks, or pyrite-milky white quartz veins in places (Figure 3a,b).…”

“…Recently, gold mineralization at Wuhe area has been generally constrained as 113-134 Ma corresponding to the Early Cretaceous as deduced from Rb-Sr, Re-Os, K-Ar, and Ar-Ar geochronology [4,5,7,9]. The ore-forming materials were related to the Early Cretaceous magmatism [5,9,16]. Despite many previous studies, the ore-forming materials sources remain debated in the Wuhe gold deposit, including mantle-derived materials, wall rock sources, and magmatic sources [4,5,9,[13][14][15][16].…”

“…The ore-forming materials were related to the Early Cretaceous magmatism [5,9,16]. Despite many previous studies, the ore-forming materials sources remain debated in the Wuhe gold deposit, including mantle-derived materials, wall rock sources, and magmatic sources [4,5,9,[13][14][15][16]. The Fang'an gold deposit was first explored in 2018 by Geological Team 312 of the Anhui Geological and Mineral Exploration Bureau, China.…”