Geochronology and geochemistry of the intrusive rocks in Yucun Au deposit, Jiangnan Transition Belt, Eastern China: Constraints on their petrogenesis, geodynamical setting and mineralization

Shanshan Chen; Xiaoyong Yang; Zhuang Zhao; Huasheng Qi; Lei Shi

Solid Earth Sciences (Dec 2020)

Geochronology and geochemistry of the intrusive rocks in Yucun Au deposit, Jiangnan Transition Belt, Eastern China: Constraints on their petrogenesis, geodynamical setting and mineralization

Shanshan Chen,
Xiaoyong Yang,
Zhuang Zhao,
Huasheng Qi,
Lei Shi

Affiliations

Shanshan Chen: CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; CAS Center for Excellence in Comparative Planetology, Hefei, 230026, China
Xiaoyong Yang: CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; CAS Center for Excellence in Comparative Planetology, Hefei, 230026, China; Corresponding author. CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026. China.
Zhuang Zhao: CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; CAS Center for Excellence in Comparative Planetology, Hefei, 230026, China
Huasheng Qi: CAS Key Laboratory of Crust–Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China; CAS Center for Excellence in Comparative Planetology, Hefei, 230026, China
Lei Shi: No. 311 Geological Team, Anhui Bureau of Geology and Mineral Exploration, Anqing, 246003, China

Journal volume & issue: Vol. 5, no. 4
pp. 258 – 281

Abstract

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A large number of Au polymetallic deposits have been mined in the Jiangnan Transition Belt (JTB), Eastern China. However, the formation and genesis of these Au polymetallic deposits remain unclear. Based on geochronological, geochemical, in-situ Lu–Hf and S isotopic compositions of the Yucun Au deposit, combined with other Au deposit databases in the JTB (e.g., Zhaceqiao, Zhaojialing and Huashan), this study systemically reveals the petrogenesis of the granodiorite porphyries and granite porphyries related to gold deposits, as well as constrain the process of Au mineralization. Results show that all granodiorite porphyries and granite porphyries have high alkalis content and FeO/MgO ratios, low CaO, Al2O3, P2O5 and 10000 × Ga/Al contents, indicating the I-type granite affinity. Moreover, they are enriched in large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depleted in high field strength elements (HFSEs) and heavy rare earth elements (HREEs), with weak negative Eu anomalies. Zircon 206Pb/238U ages indicate that the Yucun ore-related intrusion rocks were emplaced ca.150 Ma, which are consistent with the first stage magmatic activity in eastern China. The Yucun intrusion rocks present high zircon Ce4+/Ce3+ and Eu/Eu∗ ratios, suggesting the high magmatic oxygen fugacity, which is conducive to the Cu–Au mineralization. The geochemical and Lu–Hf isotopic compositions indicate that intrusion rocks associated with Au deposit in JTB may come from the metasomatized mantle-derived magmas mixing with Proterozoic crustal materials. The δ34S values of pyrite of ores in Yucun Au deposit indicate a magmatic-derived source, resembling in other porphyry-skarn Au deposits in the JTB.

Published in Solid Earth Sciences

ISSN: 2451-912X (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Geology
Website: http://www.journals.elsevier.com/solid-earth-sciences/

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