摘要
中条山前寒武纪涑水杂岩主要由西姚和寨子英云闪长质-奥长花岗质-花岗闪长质(TTG)片麻岩、横岭关和北峪钙碱性花岗质岩石组成。SHRIMP锆石U-Pb年代学研究表明,西姚石英闪长质片麻岩^(207)Pb/^(206)Pb加权平均年龄为2536±8Ma,是新太古代的产物;西姚和寨子TTG片麻岩及横岭关和北峪钙碱性花岗质岩石岩浆锆石Hf同位素组成ε_(Hf)(t)全为正值,且在t-ε_(Hf)(t)图解上,落在2.6～3.1Ga地壳演化线范围内。北峪钙碱性花岗质岩石中三个继承锆石核的^(207)Pb/^(206)Pb加权平均年龄为2633±84Ma,其锆石ε_(Hf)(t)值为-2.0～+5.6。前寒武纪涑水杂岩中花岗质岩石的SHRIMP锆石U-Pb年代学和锆石Hf同位素特征揭示它们最可能形成于新太古代到古元古代,岩浆主要来源于约2650Ma初生地壳的部分熔融,并有更古老的地壳物质的加入。
The Precambrian Sushui Complex in Zhongtiao Mountain is composed principally of Xiyao and Zhaizi TTG gneisses, Henglingguan and Beiyu calc-alkaline granitoids. SHRIMP zircon U-Pb dating for Xiyao TTG gneiss yield the weighted mean 207Pb/206Pb age of 2536 ± 8Ma, revealing that it was formed in the Neoarchean. In-situ zircon Lu-Hf isotopic analyses of Xiyao and Zhaizi TTG gneisses and Henglingguan-Beiyu calc-alkaline granitoids show that the magmatic zircons have positive εHf（t） values, and these εHf（t） values are plotted within the revolution areas of the 2600 - 3100Ma old continental crust in the age vs. εHf（t） diagrams. The analytical spots of three inherited zircon cores from the Beiyu calc-alkaline granitoid yield a weighted mean 207Pb/206Pb age of 2633±84Ma,and the εH（t） values of these inherited cores of magmatic zircon gains are, -2.0 - ＋5.6. The characteristics of zircon SHRIMP U-Pb ages and Hf isotope compositions of these TTG gneisses and calc-alkaline granitoids from the Precambrian Sushui Complex indicate that they were possibly formed in the Neoarchean to Paleoproterozoic tectonic settings of Andes-type continent margin, and the magmas could be derived from the partial melting of juvenile crust materials from the depleted mantle and more older continental crust materials.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第1期139-148,共10页
Acta Petrologica Sinica
基金
国家自然科学基金重大国际合作项目(资助号:40412012035)
国家自然科学基金面上项目(资助号:40472096)
国家自然科学青年基金(资助号:40602022)联合资助
