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Magmatic sequence of Early Palaeozoic granitic intrusions and its tectonic implications in north Altay orogen,Xinjiang
Author(s): Dong LH, Qu X, Zhao TY, Xu SQ, Zhou RH, Wang KZ and Zhu ZX.1.Bureau of Xinjiang Geology and Mineral Resources Development, Urumqi 830000, China 2.Xinjiang Institute of Geological Survey, Urumqi 830000, China
Pages: 2307-
2316
Year: 2012
Issue:
8
Journal: Acta Petrologica Sinica
Keyword: 花岗岩; TTG组合; 洋脊俯冲; 早古生代; 阿尔泰; 新疆;
Abstract: 新疆阿尔泰早古生代造山带侵入岩占构造带面积50%以上,近年大量高精度SHRIMP和LA-ICP-MS锆石U-Pb年代学资料反映其构造属性为奥陶纪碰撞前序列和中志留-早泥盆世后碰撞序列。碰撞前序列岩石组合为(石英)闪长岩-英云闪长岩/奥长花岗岩/花岗闪长岩-二长花岗岩序列,类似TTG组合,锆石U-Pb同位素年龄峰值为450~465Ma。后碰撞由二长花岗岩-正长花岗岩及少量碱长花岗岩组成,属于广义的GG组合,同位素年龄峰值390~415Ma。前者主要分布在中南部,后者主要分布中北部,分布的极性显示俯冲带在南侧。而区域南侧的阿尔曼太蛇绿岩带同位素年龄与北阿尔泰奥陶纪碰撞前序列时代相同,本文推测该蛇绿岩带与北阿尔泰岩浆链带构成洋脊俯冲带模式;其间的南阿尔泰晚古生代增生带、额尔齐斯强变形带、北准噶尔晚古生代洋内弧带都是后来的上叠产物。
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