辽宁营口虎皮峪地区古元古代岩浆事件及地质意义

发布时间：2018-03-20 19:33

本文选题：古元古代　切入点：辽吉活动带　出处：《地质学报》2017年11期 　论文类型：期刊论文

【摘要】：辽宁营口虎皮峪地区存在3期古元古代侵入岩浆活动:早期虎皮峪辽吉花岗岩成岩时代为2119±16Ma,富硅、富碱、低铝、低钙及负Eu异常显示其具有类似A型花岗岩的地球化学特征,非常低Sr高Yb的特点指示其形成压力很低,与减薄的地壳有关;第二期后松树沟奥长花岗岩成岩时代为1892±16Ma,富硅、富钠、高铝,Na2O/K2O1.35及无Eu异常或正Eu异常显示其具有埃达克质岩石的特征,中—高Sr低Yb的特点指示其形成压力较高、深度较大,与碰撞后加厚地壳底侵玄武岩的部分熔融有关;晚期南台子石英二长岩成岩时代为1850±11Ma,富碱(Na2O+K2O=11.32%~11.93%),里特曼指数δ=4.78~7.20,属碱性岩,低Sr低Yb的特点指示其形成压力中等,深度大概40~50km,是造山作用完成后板内伸展背景下的产物。上述3期岩浆事件对整个辽吉古元古代活动带的构造演化具有重要指示意义:早期辽吉花岗岩可能形成于辽吉古元古代活动带早期弧后伸展阶段;后松树沟奥长花岗岩则代表古元古代晚期碰撞后地壳加厚阶段的产物;南台子石英二长岩属后造山花岗岩,标志着辽东地区克拉通化的完成,开始进入后造山伸展演化阶段。
[Abstract]:In Hupiyu area, Yingkou, Liaoning Province, there are 3 ancient intrusive magmatic activities: the diagenetic age of Liaoji granite in early Hupiyu is 2119 卤16Ma.The anomalies of rich silicon, alkali, low aluminum, low calcium and negative EU show that they have geochemical characteristics similar to A-type granite. The characteristics of very low Sr and high Yb indicate that the formation pressure is very low, which is related to the thinning crust, and the diagenetic age of the Songshugou Ordovician granite after the second stage is 1892 卤16 Ma, which is rich in silicon and sodium. High-alumina Na _ 2O / K _ 2O _ 1.35 and no EU anomaly or positive EU anomaly show that they have the characteristics of adakitic rocks. The characteristics of medium-high Sr and low Yb indicate that the formation pressure is high and the depth is high, which is related to the partial melting of the crust underplating basalt after collision. The diagenetic age of the late Nantaizi quartz monosite is 1850 卤11Ma. the alkali-rich Na 2O K _ 2O _ 2 is 11.32 ~ 11.93, and the Ritman index 未 ~ (4.78) ~ (7.20) belongs to the alkaline rock. The characteristics of low Sr and low Yb indicate that the formation pressure is moderate. The depth is about 40 ~ 50km, which is the product of intraplate extension after orogeny. The three magmatic events mentioned above are of great significance to the tectonic evolution of the entire Liaoji-Ji-Paleoproterozoic active belt: the early Liaoji granites may have been formed in the early Liaoji granite. The early back-arc extension stage of the Liaojiguo Proterozoic active belt; The post-Songshugou granite represents the product of the post-collision crustal thickening stage of late Gu Yuan, and the Nantaizi quartz monzonite belongs to the post-orogenic granite, which marks the completion of the cratonization in the eastern part of Liaoning Province and begins to enter the stage of post-orogenic extension and evolution.
【作者单位】：中国地质调查局天津地质调查中心;
【基金】：中国地质调查局地质调查项目(编号1212011120154和12120114034201)资助成果
【分类号】：P534.3;P588.1

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