华北克拉通东部辽河群中两类斜长角闪岩年代学、地球化学特征及其地质意义  

Chronology, geochemical characteristics and geological significanceof the two types of amphibolites within the Liaohe Groupin the eastern block of the North China Craton

作　　者：杨玉伟 于海峰 石玉学 吴奇 孙海洋 韩雪 张言珑 余超 YANG Yuwei;YU Haifeng;SHI Yuxue;WU Qi;SUN Haiyang;HAN Xue;ZHANG Yanlong;YU Chao(Geophysical Measuring Exploration Institute of Liaoning Province,Shenyang,Liaoning110031,China;Liaoning Survey Academy of Geology and Mineral Resources Investigation,Shenyang,Liaoning110031,China)

机构地区：[1]辽宁省物测勘查院有限责任公司,沈阳110031 [2]辽宁省地质矿产调查院有限责任公司,沈阳110031

出　　处：《地质学报》2021年第12期3705-3720,共16页Acta Geologica Sinica

基　　金：中国地质调查局地质调查项目(编号DD20160049-9)资助的成果。

摘　　要：对辽东桓仁地区辽河群高家峪组中出露的斜长角闪岩进行岩石学、地球化学及年代学研究,显示高家峪组中的斜长角闪岩原岩为基性玄武岩,可划分为低Ti-E-MORB及高Ti-OIB两种类型:低Ti型样品原岩属拉斑玄武岩系列,轻微亏损Nb、Ta、Zr,明显亏损P,弱轻稀土富集、重稀土亏损,具有E-MORB地球化学特征;高Ti样品原岩属碱性玄武岩系列,富集Rb、Th、U等大离子亲石元素,轻稀土富集、重稀土亏损,具有OIB地球化学特征。两类斜长角闪岩具有较低的MgO、Cr、Ni含量及Mg;值,说明它们原岩不是原始岩浆,而是通过不同矿物相分离结晶作用形成。锆石U-Pb测年表明低Ti型和高Ti型斜长角闪岩成岩年龄分别为2158±15 Ma、2173±12 Ma,变质年龄分别为1870±6 Ma、1861±7 Ma。区域地质特征及岩石成因研究共同指示两类斜长角闪岩形成于弧后盆地环境,辽吉地区在古元古代早期可能处于活动大陆边缘弧后盆地构造环境,辽吉造山带的形成与弧-陆碰撞有关。Petrology, geochemistry and zircon U-Pb chronology of the amphibolite in the Gaojiayu Formation of the Liaohe Group in the Huanren area, eastern Liaoning Provincewere studied. The results show that the original rock of amphibolite is basalt and can be divided into two types: low Ti and high Ti. The original rock of the low-Ti sample belongs to tholeiite series, with slight loss of Nb, Ta and Zr, obvious loss of P, and weak light rare earth elements enrichment, heavy rare earth elements loss, showing the geochemical characteristics of E-MORB. The original rock of the high Ti sample belongs to alkaline basalt series, with enrichment of large ionic lithophile elements such as Rb, Th and U, and enrichment of rare earth and loss of heavy rare earth, showing the geochemical characteristics of OIB. The two types of amphibolites have low contents of MgO, Cr, Ni and Mg;values, indicating that their protoliths are not primitive magma, but were formed by separate crystallization of different mineral phases. The U-Pb dating of zircon indicates that the diagenetic ages of the low Ti type and the high Ti type are 2158±15 Ma and 2173±12 Ma, and the metamorphic ages are 1870±6 Ma and 1861±7 Ma respectively. There are obvious differences in the geochemical characteristics of the two types of amphibolite indicating that there is no transitional relationship between them. The regional geological characteristics and petrogenetic studies jointly indicate that the two types of plagioclase were formed in the back-arc basin environment. Based on the available petrology, geochemistry and isotopic characteristics, the Liaoji area may have been in the tectonic environment of the back-arc basin of the active continental margin in the early Paleoproterozoic, and the formation of the Liaoji orogenic belt is related to the arc-land collision.

关 键 词：辽河群 锆石U-PB 斜长角闪岩 弧后盆地 辽吉造山带 

分 类 号：P588.125[天文地球—岩石学]