【作者】 韩振哲；

【导师】 赵海玲；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2011， 博士

【摘要】 小兴安岭东南段属于兴蒙造山带东端的规模巨大的东北中生代“花岗岩海”一部分,本论文在探讨研究区内早中生代花岗岩的时空演化、成因及其形成构造背景,以及成岩成矿作用基础上,划分出矿床成矿系列,建立了成岩成矿模型,圈定了成矿远景区,进行了找矿潜力评价,取得了以下主要成果和认识:1、似斑状二长花岗岩、二长花岗斑岩中普遍发育微细粒闪长质包体(MME型)、同深成作用岩墙—(辉石)闪长(玢)岩等中基性脉岩群,及宏微观和主微量元素、同位素等特征,提出岩石具显著的壳幔岩浆混合成因的新认识,并取得似斑状二长花岗岩LA-ICPMS锆石U-Pb年龄为191.4~231Ma、同深成作用岩墙—(辉石)闪长岩186.3~207Ma年龄(全岩Rb-Sr等时线)、二长花岗斑岩U-Pb锆石年龄为190.8~202.08Ma的新成果。2、首次厘定出晚三叠—早侏罗世铝质A2型正长—碱长花岗岩,岩石U-Pb锆石年龄为175.1~214Ma,岩石成因与基性岩浆底侵作用下的地壳古老变质基底物质的部分熔融作用和一定程度的壳幔岩浆混合、分异作用参者共同控制有关,形成于大陆碰撞后跨塌、伸展构造环境。3、研究区早中生代花岗岩类由似斑状二长花岗岩、二长—正长花岗斑岩向铝质A2型正长—碱长花岗岩、A型碱性花岗岩演化,岩石形成于晚三叠—早侏罗世,说明研究区经历了古亚洲洋闭合后的大陆碰撞—碰撞后向碰撞后崩塌的大陆动力学构造背景的有序演化,暗示该地区从此进入滨太平洋构造域的陆缘增生构造环境,这对确定古亚洲洋和古太平洋构造域的转换时间具有重要的意义。4、依据早中生代花岗岩类时空演化、成因及其构造背景、成岩成矿特征划分出:碰撞—碰撞后构造转变期似斑状二长花岗岩—二长花岗斑岩有关Mo-Au-Pb-Zn-Fe成矿亚系列和碰撞后崩塌型正长—碱长—碱性花岗岩有关Fe-Pb-Zn-Mo成矿亚系列;提出两个矿床成矿亚系列中成矿作用的差异性与成岩成矿构造背景、岩浆源区物质、岩浆侵位深度和岩体中壳幔岩浆物质混合比例、混合强度等有关的新认识,并首次在建立了底侵作用下的早中生代花岗岩成岩成矿模型。5、在小西林铅锌铁矿田中,取得与成矿关系密切的细中粒似斑状二长花岗岩锆石LA-ICPMS年龄为197~207Ma的新成果,并提出叠加晚三叠—早侏罗世铅锌成矿作用的新认识。6、总结了研究区地层、岩浆岩、构造控矿的成矿条件分析、成矿规律和找矿标志等,并结合物化探、遥感等综合研究基础上,圈出与早中生代花岗岩有关的铁多金属、金等Ⅰ级成矿远景区4个,Ⅱ级成矿远景区1个,Ⅲ级成矿远景区1个,对成矿远景区进行了多金属成矿规律、找矿潜力分析。更多还原

【Abstract】 The Southeastern XiaoXing’An Mountains are a part of grand- scale of“Sea of Granites”in Northeast Mesozoic located in Eastern XingMeng orogenic belt. In this dissertation, based upon the research in the temporal and spatial evolution of Early Mesozoic Granites、genesis and the formation of tectonic background and petrogenesis and mineralization in the region, the metallogenic series of ore deposits were divided, diagenetic and metallogenic model were established, and metallogenic prospective zones were enclosed and also prospecting potentiality was evaluated. It had the following main achievements and understandings:1. Through the research of Porphyritic monzonitic granites、generally grown mafic microgranitoid enclave(MME)among porphyritic monzonitic granites、catagenesis rock dyke - pyroxene diorite and diorite porphyrite etc intermediate-basic dykite group as well as macroscopical and microcosmic、major- trace elemental and isotope characteristics, it had new understandings that the rocks had obvious crust-mantle magma mixing genesis and also it had new achievements that Zircon U-Pb dating age of Porphyritic monzonitic granite LA-ICPMS was 191.4~231Ma、dating age of hypomagmatic dyke - pyroxene diorite was 186.3~207Ma (/bulk Rb-Sr isochron), and Zircon U-Pb dating age of Porphyritic monzonitic granites was 190.8~202.08Ma.2. Aluminium type A2 syenite - alkali feldspar granite in Late Triassic-Early Jurassic period were firstly determined and Zircon U-Pb dating age was 175.1~214Ma, the genesis of the rocks was related to partial melting of materials from ancient modification of crust under the basic magma underplating and common control in a certain crust-mantle magmatic mixing and differentiation and so formed the tectonic environment of collapse and expansion after continental collision.3. In the research area the granites in Early Mesozoic was evolved from porphyritic monzonitic granite、monzoporphyry - orthophyre to aluminum type A2 syenogranite - alkali feldspar granite and type-A alkali granite. The rocks were formed in the Late Triassic-Early Jurassic period. This explained that this area had experienced the sequential evolution of tectonic background of continental geodynamics from continental collision to the collapse after collision after the final closure of the Paleo-Asian Ocean, it implied that this region had entered into an epicontinental accretion tectonic setting in marginal-pacific tectonic domain, and it brought huge significance in ensuring the conversion time between Paleoasian tectonic domain and Paleo-Pacific tectonic domain.4. Based upon the granites in Early Mesozoic in temporal and spatial evolution、genesis and tectonic background and the characteristics of petrogenesis and mineralization, the metallogenic series of ore deposits were divided into two sub-class metallogenic series of ore deposits which were Mo-Au-Pb-Zn-Fe sub-class metallogenic series of porphyritic monzonitic granite from collision-transition period after collision and Fe-Pb-Zn-Mo sub-class metallogenic series of alkali feldspar granite from collapse after collision; and it was indicaated that the differentiation of mineralization of two sub-class metallogenic series of ore deposits was related to ore-forming tectonic background and the properties of magmatic source, petrogenesis, the blending ratio of magmatic material in crust mantle, intensity of blending, emplacement depth of magma and so forth, and for the first time the model of petrogenesis and mineralization was established from the underplating granites in Early Mesozoic.5. Among Xiaoxilin lead-zinc orefield, it had been achieved the LA-ICPMS Zircon dating age of fine - medium granule porphyritic monzonitic granite which was closely related to mineralization was 197~207Ma and indicated new understandings of overlaying lead-zinc mineralization in Late Triassic-Early Jurassic period.6. In conclusion, in summarizing the strata、igneous rocks、geological analysis of structural ore-control、metallogenic regularity and various types of prospecting indicator in the research area and in combination with the comprehensive characteristic research of geology, geophysical prospecting, geochemical prospecting and remote sensing, four Grade-I and one Grade-II and one Grade-III metallogenic prospective zones of Fe polymetallic deposit and gold deposit were enclosed, which were related to the Early Mesozoic granites. The analysis of metallogenic regularity and prospecting potentiality was conducted in the metallogenic prospective zones.更多还原