An integrated study of petrology, zircon U-Pb geochronology, whole-rock geochemistry and in-situ zircon Hf isotopic compositions for the Middle Permain granitic rocks from the northern accretionary zone of North China Craton（NCC） has been implemented, with the aim of investigating their precise geochronological framework, petrogenesis, sources and tectonic significance. The studied granitic rocks are widely distributed on the south side of the Changchun-Yanji suture belt and composed of syengranite, monzogranite and granodiorite. New laser ablation inductively coupled plasma mass spectrometry（LA-ICP-MS） zircon U-Pb dating yields weighted mean ages ranging from 260.2±1.3 Ma to 262.9±2.7 Ma, representing the emplacement age of the Middle Permain. Geochemically, these granitic rocks possess SiO2（60.5–73.3%） and K2O（1.31–8.10%）, low MgO（0.22–2.28%） and CaO（0.38–4.78%） and exhibit weakly peraluminous（A/CNK=0.86–1.00） and high-K calc-alkaline affinities, which possess the attributes of Ⅰ-type granites. They are also characterized by enrichment in large ion lithophile elements（LILEs; e.g., Rb, Th, Ba, K） and light rare earth elements（LREEs）, and depletion in high field strength elements（HFSEs; e.g., Nb, Ta, Ti and P） and heavy rare earth elements（HREEs）, which bear resemblances to arc igneous rocks that form in active continental margin settings. Magmatic zircons from the studied granitic rocks show homogeneous Hf isotopic compositions（εHf（t）=–1.4 to +15.1）, with corresponding two-stage model（TDM2） ages varying of 1839–348 Ma, indicating that primary magma were generated by partial melting of Paleoproterozoic to Phanerozoic and accreted lower crust, with minor contributions of ancient crustal materials. In combination with previous geological evidences, it is reasonable to propose that the generation of the Middle Permain granitic rocks in the northern accretionary zone of the NCC were related to the southward subduction of the Paleo-Asian oceanic plate beneath the NCC, suggesting the Paleo-Asian Ocean（PAO） had not closed before the Middle Permian.
类型: 国际会议
作者: JING Yan,GE Wenchun,YANG Hao,DONG Yu,JI Zheng,HE Yue,ZHAO Di
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学
专业: 地质学,地质学,地质学
单位: Jilin UniversityKey Laboratory of Mineral Resources Evaluation in Northest Asia, Ministry of Land and Resources of China
分类号: P534.46;P588.121;P542
DOI: 10.26914/c.cnkihy.2019.028389
页码: 196
总页数: 1
文件大小: 129k
下载量: 3
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