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540374 
Journal Article 
Geodynamic significance of the A-type granites in the Sawuer region in west Junggar, Xinjiang: Rock geochemistry and SHRIMP zircon age evidence 
Zhou, TF; Yuan, F; Tan, LG; Fan, Y; Yue, SC 
2006 
1 
Science in China Series D: Earth Sciences
ISSN: 1006-9313
EISSN: 1862-2801 
49 
2 
113-123 
English 
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 delta Eu values are lower. The Nd, Sr, Pb isotope compositions of the intrusions indicate a mantle source, while the low sigma O-18 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 (1 sigma), and that of Kuoyitasi intrusion is 297.9 +/- 4.6 Ma (1 sigma), 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. 
A-type granite; zircon; SHRIMP age; post-collision; Junggar; Xinjiang; phanerozoic crustal growth; tectonic implications; continental growth; nw china; northwest china; altai orogen; petrogenesis; evolution; deposits