Integrated U–Pb, Lu–Hf and (U–Th)/He analysis of zircon from the Banxi Sb deposit and its implications for the low-temperature mineralization in South China

• Published in: Di xue qian yuan. 2020-07, Vol.11 (4), p.1323-1335
• Main Authors: Li, Huan, Danišík, Martin, Zhou, Zhe-Kai, Jiang, Wei-Cheng, Wu, Jing-Hua
• Format: Article
• Language: English
• Subjects: Antimony; Basement rocks; Crystallization; Crystals; Deposits; Fluid circulation; Hydrothermal systems; Integrated approach; Low temperature; Magma; Mineralization; Radiometric dating; Rocks; Sb (Au–Hg) deposits; Stibnite; U–Pb - Lu–Hf - (U–Th)/He triple-dating; Zircon
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2020.01.004

Low-temperature Sb (Au–Hg) deposits in South China account for more than 50% of the world’s Sb reserves, however, their genesis remains controversial. Here we report the first study that integrates U–Pb and Lu–Hf analysis by LA-(MC)-ICPMS and conventional (U–Th)/He analysis, all applied to single zircon crystals, in an attempt to constrain the origin and timing of world-class Sb (Au–Hg) deposits in Banxi (South China). Zircon separated from a quartz-stibnite ore and an altered country rock samples revealed similar U–Pb age spectra defining two major populations – Paleoproterozoic (~1900–2500 ​Ma) and Neoproterozoic (~770 ​Ma), which are characterized by variable εHf(t) values (–10.7 to 9.1 and –16.5 to 11.2, respectively) and Hf crustal model ages (TDMC) (2.48 to 3.24 ​Ga and 0.97 to 2.71 ​Ga, respectively). The U–Pb age and Hf isotopic features of the zircons are consistent with the Banxi Group in the region, indicating that the zircons involved in the low-temperature hydrothermal system were originally from the Banxi Group country rocks. Thirty-three mineralization-related zircon crystals yielded a mean (U–Th)/He age of 123.8 ​± ​3.8 ​Ma, which is interpreted to represent the timing of the latest low-temperature mineralization stage of the Banxi Sb deposit. The combined U–Pb, Lu–Hf and (U–Th)/He data suggest that Precambrian basement rocks were the major contributors to the low-temperature mineralization, and that Early Cretaceous (130–120 ​Ma) could be the most important ore-forming epoch for the Sb deposits in South China. This study also demonstrates the analytical feasibility of integrated U–Pb - Lu–Hf - (U–Th)/He “triple-dating”, all applied to single zircon crystals. This approach reveals the full evolution of zircon, from its origin of the magmatic source, through its crystallization and low-temperature cooling. Although this study demonstrates the usefulness of this integrated approach in dating low-temperature mineralization, it has great potential for zircon provenance and other studies that may benefit from the large amount of information that can be extracted from single zircon crystals. [Display omitted] •Banxi Group played an important role in providing ore-forming materials.•Zircon (U–Th)/He ages define a tight cluster at 123.8 ​± ​3.8 ​Ma.•The Early Cretaceous could be the most important Sb mineralization epoch.•Multiple isotopic analysis constrains the full thermal and genetic evolution of zircon.