摘要
研究区红石泉位于龙首山成矿带西部,本次研究对区内正长岩进行系统的元素地球化学和年代学分析测试,理清其岩石成因,探讨其构造意义。结果显示,红石泉正长岩样品的w(SiO_(2))为57.15%-65.03%,w(Al_(2)O_(3))为14.31%-18.46%,相对高钾w(K_(2)O)=4.55%-11.30%和富碱w(K_(2)O+Na_(2)O)=10.48%-13.10%,K_(2)O/Na_(2)O比值为0.64-4.22,可归类为准铝质高钾碱性系列。岩石相对富集Rb,Th等大离子亲石元素与轻稀土,相对亏损Nb,Ta,P和Ti等高场强元素与重稀土,Eu(均值0.66)呈轻微负异常。锆石U-Pb定年指示其结晶年龄为416.00±0.17 Ma(MSWD=0.88)。综合分析认为,红石泉正长岩的形成与壳幔岩浆混合作用密切相关。晚志留纪至早泥盆纪时,祁连—柴达木板块和阿拉善板块的碰撞造山作用进入后碰撞伸展阶段,地幔岩浆的底侵作用诱发了地壳熔融,从而形成壳源岩浆,而幔源岩浆与壳源岩浆的混合作用形成了红石泉正长岩的母岩浆。
The syenite in the west of Longshoushan metallogenic belt is systematically analyzed and tested by element geochemistry and chronology in order to clarify its petrogenesis and discuss its tectonic significance.The results show that the contents of SiO2 and Al2O3 in Hongshiquan syenite are 57.15%-65.03%,14.31%-18.46%and the rock is relatively rich in potassium(w(K_(2)O)=4.55%-11.30%)and alkali(w(K_(2)O+Na_(2)O)=10.48%-13.10%).The ratio of K_(2)O/Na_(2)O ranges from 0.64 to 4.22,showing the characteristics of quasi-aluminum high-k alkaline series.The rocks are enriched in large ion lithophile elements(Rb,Th)and LREE,depleted in high field strength elements(Nb,Ta,P,Ti)and HREE,with a slight negative anomaly of Eu(mean 0.66).Zircon U-Pb dating for the syenite indicates that its crystallization age is 416±0.17 Ma(MSWD=0.88).Comprehensive analysis shows that the formation of Hongshiquan syenite is closely related to the mixing of crust-mantle magma.During the late Silurian to Early Devonian,the collisional orogeny of Qilian-Qaidam plate and Alxa plate entered the post collisional-extension stage,and the basal emplacement of mantle magma induced crust melting,which resulted in the formation of crust-derived magma,and the mixing of mantle and crust-derived magma formed the parent magma of Hongshiquan syenite.
作者
冷天赐
刘文恒
余驰达
刘晓东
王伟
李炎兴
Leng Tianci;Liu Wenheng;Yu Chida;Liu Xiaodong;Wang Wei;Li Yanxing(School of Earth Sciences,East China University of Technology,Nanchang,Jiangxi 330030,China;Jiangxi Provincial Key Laboratory of Digital Land,East China Institute of Technology,Nanchang Jiangxi 330030,China;State Key Laboratory of Nuclear Resources and Environment,East China Institute of Technology,Nanchang,Jiangxi 330030,China;Research Institute of No.203 Nuclear Industry,Xianyang 712000,Shanxi,China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2021年第3期72-83,共12页
Mineralogy and Petrology
基金
中国核工业地质局铀矿勘查项目(编号:201619)。
