二连—东乌旗地区岩浆演化及与成矿作用的关系

发布时间：2018-01-23 09:05

本文关键词： 岩浆岩构造组合构造背景成矿作用二连-东乌旗中亚造山带　出处：《中国地质大学(北京)》2016年博士论文　论文类型：学位论文

【摘要】：二连-东乌旗地区位于二连-贺根山构造混杂岩带以北,处于古亚洲域和滨太平洋域两大构造域的叠加交汇部位,岩浆岩分布广泛、矿产资源丰富,以岩浆岩构造组合作为探索构造演化的“标尺”和揭示深部过程的“探针”,对再塑该区构造演化过程、厘定主要成矿构造环境有重要的理论意义。集成研究区近乎全覆盖的1:5万区域地质调查成果资料,编制了区域地质图,对岩浆岩时空分布梳理发现,岩浆活动集中在四个时段:早古生代(470~430Ma)、晚古生代(370~260Ma)、早中生代(250~210Ma)及晚中生代(180~110Ma)。其中,岩浆活动最强烈的时代集中在330-290Ma、170-120Ma两个时段。按上述4个时段,以侵入世代为基本单元,对岩浆岩的空间分布、组成进行了梳理,研究了各时代典型岩浆岩地球化学特征,并尝试利用集成的1:5万区调海量数据,进行全区性的地球化学对比,将研究区岩浆岩划分为三大构造组合:①早古生代岩浆岩构造组合(470~430Ma):包含中奥陶世岛弧岩浆组合、晚奥陶世岛弧-后造山过渡环境岩浆组合及早志留世后造山岩浆组合;②晚古生代-早中生代岩浆岩构造组合(370~210Ma):早-中泥盆世岛弧(弧后)火山岩、晚泥盆世岛弧背景局部伸展形成岩石组合、早石炭世大陆边缘弧(内弧)岩石组合、晚石炭世-早二叠世岛弧扩张海陆交互相火山岩组合、晚石炭世-早二叠世后碰撞-后造山岩浆岩组合、早二叠世-中晚三叠世后造山岩石组合、晚三叠世板内岩浆岩组合;③晚中生代岩浆岩构造组合(180~110Ma):中晚侏罗世后碰撞-后造山岩浆岩组合、早白垩世后造山岩浆岩组合。结合区域资料得出,早古生代岩浆演化与南蒙古洋有关,晚古生代-早中生代岩浆构造组合与古亚洲洋密切相关,晚中生代岩浆构造组合与古太平洋有关,后两者间的转换时期可能为晚三叠世。通过对已知矿床与岩浆岩时空关系的总结,发现成矿作用集中在三个重要的岩浆演化时期:晚石炭世-早二叠世(320~270Ma),后碰撞-后造山转换期岩浆演化,是主导该期钼铜及其它多金属成矿的根本性因素;早中生代中-晚三叠世(237Ma±),古亚洲洋闭合之后的后造山岩浆作用,形成了铁锌、铅锌银等多金属矿化;晚中生代早白垩世(130Ma±),古太平洋演化的后造山阶段,随岩浆演化伴发了大规模的成矿作用,是研究区最重要多金属成矿期。
[Abstract]:Erlian-Donwuqi area is located in the north of Erlian-Hegen Mountain tectonic melange belt, and is located at the superimposed intersection of the two tectonic domains of Paleo-Asia and the riparian Pacific. The magmatic rocks are widely distributed and rich in mineral resources. The magmatic tectonic assemblage is used as the "scale" to explore the tectonic evolution and the "probe" to reveal the deep process to remodel the tectonic evolution process in this area. It is of great theoretical significance to determine the main metallogenic tectonic environment. The regional geological map has been compiled by integrating the 1: 50 000 regional geological survey results of the nearly full coverage in the study area and the temporal and spatial distribution of magmatic rocks has been combed and discovered. Magmatic activity is concentrated in four periods: early Paleozoic 470g 430Ma, late Paleozoic 370g 260Ma. The early Mesozoic (250 ~ 210 Ma) and the late Mesozoic (180-110 Ma), in which the most intense magmatic activity occurred at 330-290 Ma. According to the four periods mentioned above, the spatial distribution and composition of magmatic rocks were combed and the geochemical characteristics of typical magmatic rocks were studied according to the four periods of 170-120 Ma and taking the intrusive generation as the basic unit. And try to use the integrated 1: 50 000 regional survey massive data to carry on the whole area geochemical contrast. The magmatic rocks in the study area are divided into three major structural assemblages: Wei 1 early Paleozoic magmatic assemblage, 470U 430 Ma, including the Middle Ordovician island arc magma assemblage. Late Ordovician island arc post-orogenic transition environment magma assemblage early Silurian post-orogenic magma assemblage; (2) the late Paleozoic to early Mesozoic magmatic rock assemblages: the early and middle Devonian island arc (back-arc) volcanic rocks, and the late Devonian island arc local extension to form a rock assemblage. The early Carboniferous continental margin arc (internal arc) rock assemblage, the late Carboniferous and early Permian island arc extensional oceanic and continental intercalation volcanic rock assemblages, the late Carboniferous and early Permian post-Permian collision-post-orogenic magma assemblages. Early Permian-Middle-Late Triassic post-orogenic rock assemblage and late Triassic intraplate magmatic assemblage; (3) late Mesozoic magmatic tectonic assemblage: late Jurassic post-collision post-orogenic magmatic assemblage, early Cretaceous post-orogenic magmatic assemblage, combined with regional data. The early Paleozoic magmatic evolution is related to the Southern Mongolian Ocean, the late Paleozoic to early Mesozoic magmatic tectonic assemblages are closely related to the Paleo-Asian Ocean, and the late Mesozoic magmatic tectonic assemblages are related to the Paleo-Pacific Ocean. The transition period between the latter two may be the late Triassic. The temporal and spatial relationship between known deposits and magmatic rocks is summarized. It is found that the mineralization occurred in three important magmatic evolution periods: late Carboniferous and early Permian (320 ~ 270 Mai), post-collision and post-orogenic transition magmatic evolution. It is the fundamental factor that dominates molybdenum copper and other polymetallic mineralization in this period. During the early Mesozoic to the late Triassic, the post-orogenic magmatism after the closure of the Paleo-Asian Ocean resulted in iron-zinc, lead-zinc-silver and other polymetallic mineralization. The late Mesozoic early Cretaceous (130Ma 卤), the post-orogenic stage of paleo-Pacific evolution, accompanied by large-scale mineralization with magmatic evolution, is the most important metallogenic period in the study area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P611;P588.1

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