Pt-Os isotopic constraints on the age of hydrothermal overprinting on the Jinchuan Ni-Cu-PGE deposit, China
|Author:||Yang, Shenghong1,2,3; Yang, Gang1,2,4; Qu, Wenjun1;|
1Key Laboratory of Re-Os Isotope Geochemistry, Chinese Academy of Geological Sciences, Beijing, China
2Department of Earth and Space Science, University of Science and Technology of China, Hefei, China
3Oulu Mining School, University of Oulu, Oulu, Finland
4AIRIE Program, Department of Geosciences, Colorado State University, Fort Collins, USA
5Geological Survey of Finland, Espoo, Finland
|Online Access:||PDF Full Text (PDF, 0.7 MB)|
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe202001202608
|Publish Date:|| 2020-01-20
Platinum group element (PGE) mineralization occurs associated with mafic-ultramafic rocks in different environments. Although the PGE enrichment is primarily caused by magmatic processes, remobilization of Pd and Pt by hydrothermal fluids has likely been an important mechanism in increasing the precious metal grade in many cases. However, the timing of PGE enrichment by hydrothermal fluid processes is commonly difficult to constrain. The Jinchuan ultramafic intrusion in Northwest China is ranked the world’s third largest magmatic Ni-Cu sulfide deposit. Besides the main ore body consisting of net-textured and disseminated sulfides, there is hydrothermal mineralization associated with sheared contact zones of the intrusion, which shows elevated Cu and Pt concentrations. The unusually high Pt is hosted mainly in sperrylite within altered silicates. In this study, we applied the Pt-Os geochronometer to a Cu-Pt-rich ore body, yielding an isochron age of 436 ± 23 Ma. This age is significantly younger than the main ore formation age of ca. 825 Ma, but similar to that of the continental collision event between the Qaidam-Qilian Block and Alax Block of North China. This indicates that the intrusion may have been uplifted during the Paleozoic orogenic processes from deeper crust, resulting in the generation of the Cu-Pt-rich hydrothermal ore body. Our new data provide the first strong age constraints on the hydrothermal PGE enrichment, showing that the Pt-Os isotope system is potentially a powerful tool for dating hydrothermal overprinting on Ni-Cu-PGE sulfide deposits.
|Pages:||757 - 774|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
This work is supported by the NSFC (grant nos. 40373010, 40534020, and 40972070), the Academy of Finland (nos. 276614 and 281859), and the Renlund Foundation.
|Academy of Finland Grant Number:||
276614 (Academy of Finland Funding decision)
281859 (Academy of Finland Funding decision)
© Springer-Verlag GmbH Germany, part of Springer Nature 2017. This is a post-peer-review, pre-copyedit version of an article published in Mineralium deposita.
The final authenticated version is available online at: http://dx.doi.org/10.1007/s00126-017-0775-z.