布青山地区上二叠统格曲组物源特征分析

发布时间：2018-09-05 07:35

【摘要】：布青山-阿尼玛卿构造带布青山地区内格曲组海相磨拉石(即格曲组砾岩段)沉积组合是晚二叠世-早中三叠世古特提斯洋的向北的俯冲的重要的一次沉积响应。研究区内格曲组地层主要出露在布青山北部的洪水川、托索河和得力斯坦沟地区。在对洪水川、托索河和得力斯坦沟地区的格曲组沉积地层进行U-Pb年代学、构造地质学、地球化学研究基础上,本文分析总结了格曲组沉积地层物源特征。本研究取得的认识和结论主要有:1.分别对布青山北部洪水川、托索河和得力斯坦沟地区的格曲组沉积地层岩石样品进行碎屑锆石U-Pb年代学LA-ICP-MS测试。三个地区的碎屑锆石年龄特征如下:(1)洪水川地区格曲组地层的岩石样品的碎屑锆石同位素年龄值主要分为以下五组:335.9~578.5Ma、742.9~1192.4Ma、1318.7~1607.5Ma、2334.6~2496Ma、2925.1~3143.7Ma。(2)托索河地区格曲组地层的岩石样品的碎屑锆石同位素年龄值主要分为以下五组:400.3~555.6Ma、723.5~1275.6Ma、1408~1547.3Ma、1696.3~1740.7Ma、2479.1~2896.3Ma。(3)在得力斯坦沟地区格曲组地层的岩石样品的碎屑锆石同位素值主要分为以下三组:409~499Ma、619~744Ma、2443Ma。2.布青山-阿尼玛卿构造带布青山地区格曲组物源最主要的时期在加里东期,布青山北部洪水川和托索河碎屑锆石年龄在新元古代-中元古代、古元古代-太古宙都有出现,而南部的得力斯坦沟地区只出现在新元古代和古元古代,未出现中元古代和太古宙年龄,且北部格曲组的年龄老于南部格曲组的年龄。3.加里东期年龄信息反映了格曲组沉积地层的物质来源和早古生代原特提斯洋向北俯冲挤压所伴生的构造岩浆热事件有关。俯冲挤压所形成的岩浆弧是格曲组重要的碎屑物质来源。4.新元古代-中元古代年龄信息反映了格曲组沉积地层的物质来源于Rodinia超大陆汇聚和裂解所产生构造岩浆热事件中的岩浆产物。5.古元古代-太古宙年龄信息反映了发生在2400~2500Ma最早的一次区域性构造岩浆热事件即古元古代结晶基底形成相对应。
[Abstract]:The Sedimentary assemblage of the Neigequ formation (i.e. the Gequ formation conglomerate) in the Buqingshan-Animaching structural belt is an important sedimentary response to the northward subduction of the PaleoTethys ocean in the late Permian and early Middle Triassic. The formation of Gequ formation in the study area is mainly located in the north of Buqingshan, the Toso River and the Delistegou area. On the basis of the U-Pb geochronology, tectonic geology and geochemistry of the Gequ formation sedimentary strata in the Huanghuanchuan, Toso River and Delistegou areas, the source characteristics of the Gequ formation sedimentary strata are analyzed and summarized in this paper. The main findings and conclusions of this study are: 1. 1. The sedimentary rock samples of Gequ formation in Huanchuan, Toso River and Delistegou area in northern Buqingshan were measured by U-Pb chronology LA-ICP-MS. The age characteristics of detrital zircons in the three regions are as follows: (1) the isotopic ages of detrital zircons in the Gequ formation of the Flood Sichuan area are mainly divided into five groups: 1: 335.9 / 578.5Ma-742.92.4Ma1 1318.7N 1607.5MaHU 2334.62496Ma2925.13143.7Ma. (2) the clastic zirconium of the Gequ formation of the Tossohe region. (2) the clastic zirconium of the Gequ formation in the Toso River area. The isotopic age values of stone isotopes are divided into five groups: 400.3n 555.6Ma 723.5N 1275.6Ma 1408 1547.3MU 1696.337.71740.7 Ma-2479.1276.3Ma. (3) the zircon isotopic values of the rock samples in the Gequ formation of the Delitstangou region are mainly divided into the following three groups: 409,499Ma-619Ma-744Ma-2443Ma.2.The isotopic values of zircons in the Gequ formation of the Delitstangou region are mainly divided into the following three groups. The main source of Gequ formation in Buqingshan-Animaching tectonic belt was Caledonian period. The age of detrital zircon of Flood Chuan and Toso River in the north of Buqingshan appeared in Neoproterozoic and Mesoproterozoic, and Paleoproterozoic to Archean. However, in the southern Delistegou area, only Neoproterozoic and Paleoproterozoic, no Mesoproterozoic and Archean ages were found, and the northern Gequ formation was older than that of the southern Gequ formation. Caledonian age information reflects the source of material in the sedimentary strata of the Gequ formation and the tectonic-magmatic thermal events associated with the northward subduction of the early Paleozoic Tethys ocean. The magmatic arc formed by subduction and compression is an important source of clastic material in the Gequ formation. The information of Neoproterozoic to Mesoproterozoic ages indicates that the material of the sedimentary strata of the Gequ formation originates from the magmatic products of the tectonic magmatic thermal events caused by the convergence and splitting of the Rodinia supercontinent. The age information of Paleoproterozoic to Archean indicates that the earliest regional tectonic magmatic thermal event occurred in 2400~2500Ma, that is, the formation of the ancient crystalline basement of Gu Yuan.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.46

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