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LA-ICP-MS U-Th-Pb dating and trace element geochemistry of allanite: implications on the different skarn metallogenesis between the giant Beiya au and Machangqing Cu-Mo-(Au) deposits in Yunnan, SW China
Citation
Fu, Y and Sun, X and Li, D and Lin, H and Lai, C, LA-ICP-MS U-Th-Pb dating and trace element geochemistry of allanite: implications on the different skarn metallogenesis between the giant Beiya au and Machangqing Cu-Mo-(Au) deposits in Yunnan, SW China, Minerals, 7, (12) Article 251. ISSN 2075-163X (2017) [Refereed Article]
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Copyright Statement
Copyright 2017 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) Attribution 4.0 International (CC BY 4.0)
Abstract
The giant Beiya Au skarn deposit and Machangqing porphyry Cu-Mo-(Au) deposit are located in the middle part of the Jinshajiang–Ailaoshan alkaline porphyry metallogenic belt. The Beiya deposit is the largest Au skarn deposit in China, whilst the Machangqing deposit comprises a well-developed porphyry-skarn-epithermal Cu-Mo-(Au) mineral system. In this paper, we present new allanite U-Th-Pb ages and trace element geochemical data from the two deposits and discuss their respective skarn metallogenesis. Based on the mineral assemblage, texture and Th/U ratio, the allanite from the Beiya and Machangqing deposits are likely hydrothermal rather than magmatic. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) allanite U-Th-Pb dating has yielded Th-Pb isochron ages of 33.4 ± 4.6 Ma (MSWD = 0.22) (Beiya) and 35.4 ± 9.8 Ma (MSWD = 0.26) (Machangqing), representing the retrograde alteration and magnetite skarn mineralization age of the two deposits. The Beiya and Machangqing alkali porphyry-related mineralization are synchronous and genetically linked to the magmatic hydrothermal activities of the Himalayan orogenic event. Major and trace element compositions reveal that the Beiya allanite has higher Fe3+/(Fe3+ + Fe2+) ratios, U content and Th content than the Machangqing allanite, which indicate a higher oxygen fugacity and F content for the ore-forming fluids at Beiya. Such differences in the ore-forming fluids may have contributed to the different metallogenic scales and metal types in the Beiya and Machangqing deposit.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | allanite, giant Beiya Au skarn deposit, machangqing porphyry Cu-Mo deposit, sanjiang region (SW China), trace elements, U-Th-Pb dating |
| Research Division: | Earth Sciences |
| Research Group: | Geology |
| Research Field: | Mineralogy and crystallography |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the environmental sciences |
| UTAS Author: | Lai, C (Dr Chun Lai) |
| ID Code: | 125966 |
| Year Published: | 2017 |
| Web of Science® Times Cited: | 11 |
| Deposited By: | CODES ARC |
| Deposited On: | 2018-05-17 |
| Last Modified: | 2018-08-27 |
| Downloads: | 90 View Download Statistics |
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