Zircon U-Pb chronology, Petrochemistry characteristics and Metallogenic significance of Granodiorite porphyry in the Ban
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ORIGINAL PAPER
Zircon U-Pb chronology, Petrochemistry characteristics and Metallogenic significance of Granodiorite porphyry in the Banmiaozi gold deposit in the NE margin of the North China Craton Xue Li 1 & Guosheng Sun 1 & Fengyue Sun 1 & Jiuda Sun 1 & Qinghai Wang 1 & Guangwei Wang 2 Received: 5 December 2019 / Accepted: 10 September 2020 / Published online: 18 September 2020 # Saudi Society for Geosciences 2020
Abstract The timings of subduction of the Palaeo-Pacific Plate beneath the North China Craton and of associated mineralisation remain unresolved. We studied a granodiorite porphyry in the Banmiaozi gold mining area, located along the northeastern margin of North China Craton, to shed light on these timings. Using zircon U–Pb geochronology, major- and trace-element geochemistry, Sr–Nd isotopes, and biotite compositions, we show that the granodiorite porphyry formed during the early Middle Jurassic and has a composition similar to those of ‘C-type adakites’ from eastern China. The granodiorite rocks have initial Sr isotopic compositions of 0.713418–0.713694, εNd(t) values of −15.9 to −16.69, and depleted-mantle single-stage model ages of 2.70–2.49 Ga, implying that the parental magma originated via subduction of the Palaeo-Pacific Plate beneath the North China Craton and resulted also in the generation of basaltic magmas and partial melting of thickened lower crust. As the Archaean basement rocks were rich in Au and magnetite, the magma was characterized by high Au contents and oxygen fugacity (fO2 = 10−13 bar). Subsequent mixing with, or contamination by, partially melted Proterozoic marine strata, such as the marble-bearing Laoling Group, played an important role in mineralisation. These country rocks provided large quantities of Cl−, CO32−, and SO42− to the magma, which formed soluble complexes with ore-forming elements such as Au, allowing enrichment and migration of the metals. Our data show that the Banmiaozi gold deposit is an orogenic gold deposit associated with subduction-related adakitic magmatism. Keywords The Banmiaozi gold deposit . The North China Craton . Granodiorite porphyry . Metallogenic significance . Petrochemistry . U–Pb dating
Introduction According to data from 1572 gold deposits in China, the spatial distribution of gold deposits in China is uneven, and the metallogenic epoch was explosive. The margins of continental blocks are the most common setting for these deposits, and Responsible Editor: Domenico M. Doronzo * Guosheng Sun [email protected] 1
College of Earth Sciences, Jilin University, No. 2199, Jianshe Street, Changchun 130061, China
2
Liaoning Geological and Mineral Survey Institute Co., Ltd., Shenyang 110032, China
Mesozoic intermediate to acid plutonic and subvolcanic rocks are the most important hosts of gold deposits (Xue et al., 2017). The margin of the North China Craton hosts a high concentration of gold deposits. The deposits in this margin are located mainly in the Ural–Daqingshan, Yinshan– Yanshan, and Qingyuan–southern Jilin regions along the northeaster
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