Geochronology and Geochemistry of the Yaergenchu I Type Granites in Northern the Greater Hinggan Mountains Range and Its Geodynamic Implications
详细信息
- 责任者：Xu Jiulei (College of Earth Science ; Jilin University ; Changchun 130061 ; China) ; Zheng Changqing
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(9)
- 关键词：I型花岗岩 ; I-type granite ; 大兴安岭 ; Greater Hinggan Mountains
- 页码：p.1311-1323
- 图表：8 illus., 2 tables, 27 refs.
- 分类号：0801
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The study of the Yaergenchu granites in northern Da Hinggan Range indicates that the granites consist of syenogranite,mylonitized granite in lithology.Analysis of zircon U-Pb LA-ICP-MS dating yielded three concordant ages of 226.8±2.2Ma,230.2±1.3Ma and 233.6±1.5Ma,indicating intrusive time of the granites is the late Triassic.The chemical analyses（XRF）show that the granites have high SiO2,K2O contents,A/CNK ratios ranging from 0.81to 1.10.The REE patterns are characterized by enrichment of LREEs relative to HREEs with negative Eu anomalies in chondrite-normalized REE diagram.The trace elements are relatively enrichment of large ion lithophile elements（LILE）,depletion of high field strength elements（HFSE）.These features are similar to the island arc granites and I type granites.Integrated study shows that these I type granites formed in the whole extensional setting.The decreasing pressure of lithosphere mantle resulted in upwelling of the mantle,and the melted residual oceanic crust provided fluid,thus causing the emplacement of this pluton.