Geochronological and sulfur isotopic evidence for the genesis of the post-magmatic, deeply sourced, and anomalously gold-rich Daliuhang orogenic deposit, Jiaodong, China

Kai Feng, Hong Rui Fan, David I. Groves, Kui Feng Yang, Fang Fang Hu, Xuan Liu, Ya Chun Cai

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The Daliuhang gold deposit (> 20 t gold) is located in the central Penglai-Qixia belt of the giant Jiaodong gold province, eastern China. The ore-hosting Guojialing granodiorite and pegmatite were formed at 129.0 ± 0.6 Ma and 126.2 ± 0.6 Ma, respectively. Syn-ore monazite, with a U–Pb age of 120.5 ± 1.7 Ma, represents the timing of gold mineralization. Given at least 5 m.y. between magmatism and mineralization, a genetic relationship to magmatic-hydrothermal activity is negated. Noble gas isotopes of pyrite have crust-mantle-mixed 3 He/ 4 He (1.13 to 1.50 Ra) and air-like 40 Ar/ 36 Ar (327–574). Together with the broadly positive correlation between 3 He and 36 Ar, it is inferred that the initial ore-forming fluids were deeply sourced from the sedimentary wedge overlying the subducted plate and overlying mantle during early Cretaceous paleo-Pacific plate subduction. The pre-ore and post-ore pyrites have low δ 34 S values (3.7–5.6‰ and 5.3–6.4‰, respectively), whereas ore-related pyrites have higher δ 34 S values, especially in As–Au-rich domains (7.8–8.3‰). These positive δ 34 S values also suggest that the initial ore fluid and some of the sulfur component were derived via subduction-related devolatilization. The elevated δ 34 S values of the ore-related pyrite are partly ascribed to mass fractionation and partly to a contribution from sulfur leached from crustal host rocks. This interpretation is also supported by neodymium isotope ratios of monazite (ε Nd (~ 120 Ma) = − 13.7 to − 11.6), which correlate well with the ore-hosting Guojialing granodiorite. This study highlights the combined roles of deeply derived fluids and intense interaction with upper crustal rocks in the formation of Jiaodong gold deposits.

Original languageEnglish
JournalMineralium Deposita
DOIs
Publication statusE-pub ahead of print - 15 Apr 2019

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