中亚造山带中段南缘圆包山组碎屑锆石U-Pb年龄、物源及其构造演化意义

发布时间：2018-03-30 02:13

本文选题：中亚造山带　切入点：阿拉善北部　出处：《地质学报》2017年10期

【摘要】：取自圆包山组砂岩样品中的碎屑锆石作LA-ICP-MS U-Pb定年,获得两个数据年龄区间:409~431Ma(峰值420Ma)和458~488Ma(峰值488Ma)。圆包山组底部发育的笔石化石和420Ma的锆石峰值年龄将圆包山组的时代限定为早志留世后,通过与兴蒙造山带的构造演化对比,认为圆包山组时代为早志留世至早泥盆世。对圆包山组中发育的沉积构造进行古流向分析,认为圆包山组物源区位于杭乌拉北西方向。结合区域岩浆演化资料分析,圆包山组物源区为呼和套尔盖地区。在圆包山组中还检测到继承锆石,新元古代分布于559~952Ma,中元古代分布于1011~1460Ma,古元古代分布于1629~2490Ma。从前人对西伯利亚板块南部、塔里木板块以及南蒙古微板块的相关锆石年龄结果总结发现,华北板块与周围板块最主要的区别在于没有或者很少有中元古代晚期至新元古代早期的锆石年龄记录,阿拉善地块也缺少1.0~1.2Ga锆石年龄记录。综上,认为研究区在古生代构造位置属于南蒙古微板块南部的一部分,元古代物源来自塔里木板块。另外由碎屑锆石年龄在地层中分布特征来看,研究区在早泥盆世后隆升作用明显,构造活动性增强,受到塔里木板块影响逐渐加强。
[Abstract]:The zircon from sandstone samples of Yuanbaoshan formation was used as LA-ICP-MS U-Pb dating. Two data age ranges of: 409 ~ 431 Ma (peak value 420 Ma) and 4588 Ma-488 Ma (peak 488 Ma) were obtained. The peak ages of graptolite fossils developed at the bottom of the Yuanbaoshan formation and the zircon of 420Ma limit the age of Yuanbaoshan formation to that of early Silurian, and were compared with the tectonic evolution of the Xingmeng orogenic belt. It is considered that the age of Yuanbaoshan formation is early Silurian to early Devonian. Based on the analysis of paleodirection of sedimentary structures developed in Yuanbaoshan formation, it is considered that the source region of Yuanbaoshan formation is located in the northwest direction of Hangwula. The source region of the Yuanbaoshan formation is Huhe Tuoergai area. Inherited zircon was also detected in the Yuanbaoshan formation. Neoproterozoic was distributed at 559 ~ 952 Ma, Mesoproterozoic at 1011 ~ 1460 Maand Paleoproterozoic at 1629 ~ 2490 Ma. A summary of the zircon ages of the Tarim plate and the southern Mongolia microplate shows that the most important difference between the North China plate and the surrounding plate is that there are no or few zircon ages from the late Mesoproterozoic to the early Neoproterozoic. The Alashan block also lacks 1.0~1.2Ga zircon age records. In summary, it is considered that the tectonic location of the study area in the Paleozoic is part of the southern part of the Southern Mongolia microplate. The proterozoic provenance came from the Tarim plate. In addition, according to the distribution characteristics of clastic zircon age in the strata, the uplift of the study area was obvious after the early Devonian, the tectonic activity was enhanced, and the influence of the Tarim plate was gradually strengthened.
【作者单位】：中国地震局第一监测中心;中国地质大学地球科学与资源学院;有色金属矿产地质调查中心;北京市地质研究所;
【基金】：中国综合地球物理场观测—大华北地区项目(编号:201508009) 中国地震局监测预报司专项(编号:17A37ZX228) 中国地质调查局项目(编号:基[2010]矿评01-09-11)联合资助的成果
【分类号】：P542;P597.3

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