摘要
对张广才岭南部一面坡花岗岩的地质学、岩石学、地球化学及锆石U-Pb年龄研究表明,岩石富硅富铝,属于过铝质岩石(A/CNK=1.04~1.07),全碱(K2O+Na2O)含量为8.24%~8.85%,K2O/Na2O值为1.58~1.68,属于高钾钙碱性系列I型花岗岩。岩石富集LREE、Rb、Th、U、K,相对亏损Nb、Ta、P、Ti,具有明显的Eu负异常,LA-ICP-MS锆石206Pb/238U年龄加权平均值为211Ma±4Ma(MSWD=1.4,2σ),代表了花岗岩的结晶年龄。岩石具有相对亏损的锆石Hf同位素组成(εHf(t)=+1.75^+13.81),TDM2为367~1136Ma。结合区域构造环境分析,认为一面坡晚三叠世花岗岩属于I型花岗岩,可能形成于后碰撞伸展构造环境,是岩石圈伸展阶段新增生下地壳物质发生部分熔融的产物。
This paper has reported the field geology,petrography,major and trace elements,zircon U-Pb age and Lu-Hf isotopic data for the granite from Yimianpo area,Zhangguangcai Mountain.The granite is high in SiO2 and Al2O3.A/CNK=1.04～1.07,（K2O＋Na2O）=8.24%～8.85%,and K2O/Na2O=1.58～1.68,belonging to peraluminous and I-type high-K calc-alkaline series.The granite is enriched in LREE,Rb,Th,U,K and depleted in Nb,Ta,P,Ti with significant negative Eu anomalies.It has ^206Pb/^238 U weighted mean age of 211Ma±4Ma（MSWD=1.4,2σ）,which represents the crystallization age of the granite.Zircon Hf isotope composition is εHf（t）=＋1.75～＋13.81,TDM2=367～1136Ma.Therefore,the I-type granite in the study area might have been formed in a typical post-collsional tectonic setting and resulted from partial melting of juvenile basaltic lower crust in an extensional setting.
出处
《地质通报》
CAS
CSCD
北大核心
2014年第9期1333-1341,共9页
Geological Bulletin of China
基金
中国地质调查局项目(编号:1212011121085
12120113096400)
国家自然科学基金项目(批准号:41102037
41072052)
