The metamorphic host rocks of pegmatites can help to decipher their geodynamic setting and emplacement conditions. The Jiajika lithium deposit, located in the Songpan-Ganze orogenic belt, eastern Tibet, is one of the largest hard-rock type lithium deposits in China. The lithium-enriched pegmatites in Jiajika are hosted in the amphibolite facies metasedimentary rocks in the mantle of the Jiajika gneiss dome. However, the metamorphic evolution of Jiajika is poorly constrained. In this study, we carried out detailed fieldwork, petrological observation, mineral chemical analysis, phase equilibria modeling, and geochronological studies on the Jiajika gneiss dome and the borehole JSD-1 (with a total depth of 3211 m) of the Jiajika Scientific Drilling Project (JSD). Structural data outlined two subdomes within the Jiajika gneiss dome. Two main stages of regional metamorphism and deformation are documented in Jiajika: an early Barrovian metamorphism (M1) in ca. 237−221 Ma caused by crustal thickening (D1), which has a peak condition of 6.7−8.3 kbar and 649−694 °C; a late Buchan metamorphism (M2) induced by the emplacement of granites and pegmatites during doming (D2) with a peak condition of 3.4−4.3 kbar and 570−612 °C at 210−206 Ma. The superimposition of the M2 isograds upon the M1 isograds resulted in a composite metamorphic sequence around the Jiajika gneiss dome. The overlapping of the Barrovian metamorphism and the Buchan metamorphism is related to crustal thickening during continental collision and later decompression through doming, which facilitated lithium mineralization.
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Research Article|
October 01, 2024
Early Publication
The composite metamorphic sequence in the Jiajika gneiss dome, Songpan-Ganze orogenic belt, eastern Tibet: P-T-D-t evolution and implications for lithium mineralization
Junyue Zhu;
Junyue Zhu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Wenbin Zhu;
Wenbin Zhu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Zhiqin Xu;
Zhiqin Xu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Bihai Zheng;
Bihai Zheng
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Guangwei Li;
Guangwei Li
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Hefeng Lin;
Hefeng Lin
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
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Jianguo Gao
Jianguo Gao
2
Research Institute of Exploration and Development, Sinopec Southwest Oil and Gas Company, Chengdu 610041, China
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Junyue Zhu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Wenbin Zhu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Zhiqin Xu
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Bihai Zheng
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Guangwei Li
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Hefeng Lin
1
State Key Laboratory for Mineral Deposits Research, Institute of Continental Geodynamics, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
Jianguo Gao
2
Research Institute of Exploration and Development, Sinopec Southwest Oil and Gas Company, Chengdu 610041, China
Publisher: Geological Society of America
Received:
28 Apr 2024
Revision Received:
05 Aug 2024
Accepted:
03 Sep 2024
First Online:
01 Oct 2024
Online ISSN: 1943-2674
Print ISSN: 0016-7606
© 2024 Geological Society of America
GSA Bulletin (2024)
Article history
Received:
28 Apr 2024
Revision Received:
05 Aug 2024
Accepted:
03 Sep 2024
First Online:
01 Oct 2024
Citation
Junyue Zhu, Wenbin Zhu, Zhiqin Xu, Bihai Zheng, Guangwei Li, Hefeng Lin, Jianguo Gao; The composite metamorphic sequence in the Jiajika gneiss dome, Songpan-Ganze orogenic belt, eastern Tibet: P-T-D-t evolution and implications for lithium mineralization. GSA Bulletin 2024; doi: https://doi.org/10.1130/B37747.1
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