Zircon U-Pb and Pyrite Re-Os Geochronology of the Zhibo Fe Deposit in Western Tianshan, Xinjiang, China

The Zhibo iron deposit is a large iron-rich deposit located in the Awulale iron metallogenetic belt (AIMB) in Western Tianshan, Xinjiang, China. Owing to its huge resources and high grade (FeT>50%), the Zhibo iron deposit has attracted much attention and is regarded as a representative example for the study of regional metallogeny and mineral exploration. In this study, zircon U-Pb and pyrite Re-Os isotopic dating methods were used to determine the mineralization age. Pyrite, which is closely associated with magnetite, was selected from five massive magnetite ores in the eastern segment of the deposit. Re-Os isotopic dating of the five pyrite samples yielded an isochron age of 307±12 Ma. Meanwhile, zircon U-Pb dating of the least altered wall-rock andesite yielded a weighted average age of 312.0±3.4 Ma, further confirming that the iron deposit was formed during the Late Carboniferous. The andesitic agglomerate representing explosive facies near the volcanic center in the Zhibo deposit has a zircon U-Pb weighted average age of 317.8±2.5 Ma. Two quartz diorite samples from the deposit have zircon U-Pb weighted average ages of 317.0±2.2 Ma and 315.4±0.9 Ma, respectively. It can be concluded that the volcanic eruption, magmatic intrusion, and iron ore formation were almost simultaneous during the early Late Carboniferous, which may have been different manifestations of the same magmatichydrothermla event. This paper speculates that the area of “Late Carboniferous crater + magmatic emplacement + hydrothermal alteration” may be the site where the iron ores are located, and should be an important exploration target for the AIMB. © 2024 Science Press. All rights reserved.