大兴安岭北段小柯勒河地区辉长岩锆石U-Pb年龄及岩石地球化学特征  

Zircon U-Pb dating and petrogeochemical characteristics of the gabbro in the Xiaokelehe area,northern segment of the Great Xing’an Range

作　　者：高俊宝 张燕 刘观红 赵凌云 孙永刚 GAO Junbao;ZHANG Yan;LIU Guanhong;ZHAO Lingyun;SUN Yonggang(Geological Team No.1,Xinjiang Bureau of Geology and Mineral Resources,Changji 831100,China;School of Resources and Civil Engineering,Suzhou University,Suzhou 234000,China)

机构地区：[1]新疆维吾尔自治区地质矿产勘查开发局第一地质大队,新疆昌吉831100 [2]宿州学院资源与土木工程学院,安徽宿州234000

出　　处：《世界核地质科学》2024年第5期898-908,共11页World Nuclear Geoscience

基　　金：宿州学院博士(后)科研启动基金项目(编号:2022BSK009,2023BSH001)资助。

摘　　要：鉴于大兴安岭地区早白垩世时期伸展环境形成机制的不确定性,针对大兴安岭北段小柯勒河地区辉长岩进行锆石U-Pb年代学和岩石地球化学特征研究。锆石U-Pb定年显示,辉长岩形成于早白垩世晚期(123.7±0.9 Ma)。岩石地球化学分析显示样品低硅,高镁,轻重稀土元素分馏较弱,富集大离子亲石元素(如Ba、Sr和U),亏损高场强元素(如Th、Ti和Zr),具有弱Eu正异常(δEu=1.03~1.27)。研究认为:小柯勒河辉长岩形成过程中分离结晶、地壳混染作用较弱,其岩浆源区来自于受俯冲板片流体改造的岩石圈地幔。结合区域构造演化资料,认为早白垩世晚期小柯勒河辉长岩形成于古太平洋板块俯冲作用所引起的伸展环境。The formation mechanism of Early Cretaceous extensional environment in the Great Xing’an Range is uncertainty yet.In this paper,zircon U-Pb geochronology and pedogeochemical characteristics of the gabbro in the Xiaokelehe area,northern segment of the Great Xing’an Range were studied.Zircon U-Pb dating show that the gabbro was formed in the late Early Cretaceous(123.7±0.9 Ma).Results of petrogeochemical analysis show that the samples are low in Si and high in Mg.The fractionation between light and heavy rare earth elements in the samples is weak.The samples are enriched in large-ion lithophile elements(e.g.,Ba,Sr,and U),depleted in high-field-strength elements(e.g.,Th,Ti,and Zr),and shown weak Eu positive anomalies(δEu=1.03~1.27).It was concluded that the fractional crystallization and crustal contamination during the formation of the Xiaokelehe gabbro were weak,and the magma was derived from the lithospheric mantle source that had previously been metasomatized by slab-derived fluids.Combined with the regional tectonic evolution data,it was concluded that the late Early Cretaceous Xiaokelehe gabbro was formed in an extensional environment caused by the subduction of the Paleo-Pacific Plate.

关 键 词：大兴安岭北段 小柯勒河 辉长岩 岩石地球化学 伸展环境 

分 类 号：P595[天文地球—地球化学]