摘要
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 chon-drite-normalized patterns of the intrusions show LREE enrichment and the δ Eu 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 Per-mian. The former proposed Ulungur alkali granites belt can extend from east Ulungur through west Ulungur and to Zhaisang in Kazakstan westwards.
Sawuer region is located in west Junggar, Jimunai County of Altay districtand Hefeng County of Tacheng district, Xinjiang. The region is along the north margin ofKazakstan-Junggar plate. The intrusions (mainly acid) are widespread. Qiaqihai and Kuoyitasiintrusions are important in the region, with the characteristics of A-type granite. Furtherinvestigations indicate that they belong to A2-type granite that formed in extension tectonicsetting of post collision. The REE chon-drite-normalized patterns of the intrusions show LREEenrichment and the δEu values are lower. The Nd, Sr, Pb isotope compositions of the intrusionsindicate a mantle source, while the low δ^(18)O values resulted from the isotope exchange betweenintrusion and meteoric water. According to SHRIMP U-Pb age analysis results, the crystallization ageof Qiaqihai intrusion is 290.7 ±9.3 Ma (1 σ), and that of Kuoyitasi intrusion is 297.9 ± 4.6 Ma(1 σ), corresponding to the beginning of early Permian. The A2-type granites indicate that theregion was in the extension period of the post-collisional stage at the beginning of early Permianin the Sawuer region. The A-type granites in the Sawuer region in west Junggar discovered from thiswork 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 providesnew evidence for the regional vertical continental crust growth in early Permian. The formerproposed Ulungur alkali granites belt can extend from east Ulungur through west Ulungur and toZhaisang in Kazakstan westwards.
作者
ZHOU Taofa1, YUAN Feng1, TAN Lugui1,2, FAN Yu1 & YUE Shucang1 1. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
2. Department of Geography and Environment Science, Wanxi College, Liuan 237012, China
