| Geodynamic significance of the A-type granites in the Sawuer region in west Junggar, Xinjiang: Rock geochemistry and SHRIMP zircon age evidence |
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| 基金项目： | 国家重点基础研究发展计划(973计划) |
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| 摘 要： | Northern Xinjiang has been an idea and focus re-gion for post-collisional tectonic-metallogenic re-search. The time span of post-collisional stage, as well as the time span of extrusion and extension gyration of a post-collisional stage, and the process and dynamicssetting of Paleozoic continental growth are the key problems1-7]. According to the definition by Liegeois8], Wang et al. (in press)1) proposed that the taphrogeosyncline sedimentary formation that unconformably overliesthe main c…
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| 收稿时间： | 18 March 2005 |
| 修稿时间： | 10 August 2005 |
Geodynamic significance of the A-type granites in the Sawuer region in west Junggar, Xinjiang: Rock geochemistry and SHRIMP zircon age evidence |
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| Authors: | ZHOU Taofa YUAN Feng TAN Lugui FAN Yu YUE Shucang |
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| Institution: | 1. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
2. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China;Department of Geography and Environment Science, Wanxi College, Liuan 237012, China |
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| Abstract: | Sawuer region is located in west Junggar, Jimunai County of Altay district and Hefeng County of Tacheng district, Xinjiang.
The region is along the north margin of Kazakstan-Junggar plate. The intrusions (mainly acid) are widespread. Qiaqihai and
Kuoyitasi intrusions are important in the region, with the characteristics of A-type granite. Further investigations indicate
that they belong to A2-type granite that formed in extension tectonic setting of post collision. The REE chondrite-normalized
patterns of the intrusions show LREE enrichment and the δEu values are lower. The Nd, Sr, Pb isotope compositions of the intrusions indicate a mantle source, while the low δ
18O values resulted from the isotope exchange between intrusion and meteoric water. According to SHRIMP U-Pb age analysis results,
the crystallization age of Qiaqihai intrusion is 290.7 ± 9.3 Ma (1σ), and that of Kuoyitasi intrusion is 297.9 ± 4.6 Ma (1σ), corresponding to the beginning of early Permian. The A2-type granites indicate that the region was in the extension period
of the post-collisional stage at the beginning of early Permian in the Sawuer region. The A-type granites in the Sawuer region
in west Junggar discovered from this work is analogous to the A-type granites found in east Junggar of the Ulungur alkali
granites belt. The confirmation of post-collisional A-type granites of early Permian in the Sawuer region provides new evidence
for the regional vertical continental crust growth in early Permian. The former proposed Ulungur alkali granites belt can
extend from east Ulungur through west Ulungur and to Zhaisang in Kazakstan westwards. |
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| Keywords: | A-type granite zircon SHRIMP age post-collision Junggar Xinjiang |
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