内蒙古巴彦敖包地区宝力高庙组火山岩地球化学特征、锆石U-Pb年龄及地质意义

发布时间：2018-03-17 09:07

本文选题：宝力高庙组　切入点：火山岩　出处：《中国地质》2017年06期 　论文类型：期刊论文

【摘要】：内蒙古东乌旗巴彦敖包一带出露的宝力高庙组地层可划分为三段,可对应于查干敖包剖面二、三、四段。二段为一套杂色中酸性火山熔岩和火山碎屑岩类,火山喷发以喷溢相为主;三段为一套灰黄、灰白色火山-沉积碎屑岩类和陆源沉积岩,含Annularia植物化石,为火山间歇期沉积;四段为一套灰色、浅灰色酸性熔岩夹少量火山-沉积碎屑岩,火山喷发以溢流相为主。四段紫红色含晶屑流纹岩和二段灰黑色流纹岩锆石LA-ICP-MS U-Pb年龄分别为(305±4.1)Ma和(315.2±4.6)Ma,结合所含化石确定地层时代为晚石炭晚期—早二叠世早期。宝力高庙组中酸性火山岩为安山质、英安质、流纹质高钾钙碱性-钾玄岩系列火山岩组合,岩石呈现富硅、碱,贫钙、镁,A/NK值和Fe Ot/Mg O值高,富Rb、Nb,贫过渡族元素,并具有显著的铕负异常,为A2亚类花岗岩类,其可能是幔源岩浆底侵形成的晚古生代新生下地壳物质部分熔融而成,岩浆演化经历了钛铁矿物、铁镁矿物及斜长石分离作用。宝力高庙组中酸性火山岩形成于后碰撞构造背景环境,其特征揭示兴蒙造山带内蒙古东乌旗地区晚石炭世—早二叠世已处于同碰撞-碰撞后阶段,早二叠世已经进入碰撞后伸展阶段。
[Abstract]:The strata of the Baoligaomiao formation exposed in the area of Bayan Aobo, Dongwu Banner, Inner Mongolia, can be divided into three sections, corresponding to the second, third and fourth sections of the Chagan Aobo section. The second member is a set of variegated intermediate-acid volcanic lava and pyroclastic rocks. The third member consists of a set of greyish yellow, grayish-white volcanic-sedimentary clastic rocks and land-based sedimentary rocks, containing Annularia plant fossils, which are deposited intermittently in volcanoes, and the fourth member is a set of gray. Light gray acid lava with a small amount of volcanic-sedimentary clastic rock, The LA-ICP-MS U-Pb age of zircon from the fourth member of the fuchsia and the second member of the gray-black rhyolite is about 305 卤4.1 Ma and 315.2 卤4.6 Ma, respectively. The late late Carboniferous to early Permian age was determined by the fossils. The intermediate-acid volcanic rocks of Ligaomiao formation are Anshan. A series of volcanic rock assemblages rich in silicon, alkali, calcium, magnesium, and Fe Ot/Mg O, rich in RB and NB, poor in transition elements, and with significant europium negative anomalies, belonging to A _ 2 subtype granitoids, the rocks are rich in silicon, alkali, calcium, magnesium, and Fe Ot/Mg _ O, and are characterized by negative europium anomalies. It may be formed by the partial melting of the materials of the lower crust formed by the late Paleozoic magma transgression, and the magma evolution has undergone the ilmenite material. The intermediate-acid volcanic rocks of the Baoligaomiao formation were formed in the post-collision tectonic setting. Their characteristics indicate that the late Carboniferous to early Permian in the Dongwuqi area of the Xingmeng orogenic belt is already in the same collision-post-collision stage. The early Permian has entered the post-collision extension stage.
【作者单位】：中国地震局地质研究所;北京市地质调查研究院;北京市地质矿产勘查开发局;
【基金】：中国地质调查局项目“内蒙古1∶5万巴彦塔拉幅、苏勒敖包(恩格尔珠如和音呼都格)幅、巴彦敖包幅、巴彦呼勒幅区域地质调查(1212011120699)资助~~
【分类号】：P588.14

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