【作者】 伍光英；

【导师】 侯增谦；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2005， 博士

【摘要】 湘东南多金属矿集区是南岭多金属成矿带的一个重要组成部分。丰富的多金属矿产床与燕山期的岩浆活动存在密切的联系;柿竹园、骑田岭、香花岭、黄沙坪和宝山、水口山、铜山岭等大型-超大型多金属矿床,均产于花岗岩类岩体或其周围之中。笔者通过查明研究区燕山期主要成矿花岗岩类的地质构造和岩相学特征,完成同位素年代学、矿物化学、岩石化学、微量元素分析测试及稳定同位素地球化学示踪的基础上,对不同成矿花岗岩类的岩石组合类型的划分、地球化学特征背景、地质构造对矿体时空制约、花岗质岩浆物质来源、形成机制及区域壳-幔作用过程、成矿规律和找矿方向等进行了研究,获得如下主要认识:　1、通过研究区花岗岩类岩石的锆石SHRIMP 等方法的定年,建立了成矿花岗岩年代格架。将花岗岩成岩时代大致划分为4 个岩浆活动幕,认为成矿时代峰期是中侏罗世的燕山早期(约155±10　Ma)。　2、厘定了燕山期17 个典型成矿花岗岩体的岩石谱系单位。并按地幔物质参与的程度和花岗岩类与矿化系列的关系,提出了成矿花岗岩岩石组合谱系类型与矿化系列,将花岗岩类划分为MS 型、SM 型、C 型铝质A 型和S 型强过铝质的4 个岩石组合谱系类型与矿化系列。　3、研究了不同岩石组合谱系类型的成矿花岗岩的造岩矿物成分和岩石的主元素、稀土元素、微量元素、同位素地球化学及矿化等特征,探讨了岩石成分变异,尤其是成矿花岗岩富F、C1 等挥发组分导致MS 型和SM 型早期次单元准铝质花岗岩有大型-特大型Cu、Pb、Zn、Sb 等多金属矿化,而重稀土与Sn、W、Nb、Ta 等元素则于SM 型晚期次单元和C 型铝质花岗岩中富集成矿的成因意义。4、发现了壳幔混合作用的标志实体——微粒包体,并结合不同岩石组合谱系类型的成矿花岗岩体岩石的地质构造、岩相学的特征和岩石地球化学示踪,揭示了成矿花岗岩类的壳幔源岩浆混合成因的特点,改变了前人对研究区燕山期花岗岩成因的认识,为壳幔混合型花岗岩类与成矿关系的研究提供了新的依据。5、揭示了不同岩石组合谱系类型成矿花岗岩类的岩浆源岩主要是地壳物质,具有地幔和地壳双重物源的特征。模拟计算出MS 型和SM 型花岗岩的混合岩浆中碱性玄武岩基性端元分别为大于20%和小于15%,C 型铝质A 型小于10%;　6、通过壳-幔相互作用成因分析,发现同序列早次形成的单元岩石,其岩浆混合程度低,由残余的基性岩浆团的固结而成的包体含量高;而晚次单元岩石,其岩浆混合彻底,包体含少量和规模小,并认为同序列花岗岩石岩浆混合作用发生后,又发生了较高程度的结晶分离作用;早期的岩浆混合和晚期的结晶分离作用的共同作用可能是研究区成矿岩体形成的主要机制。　7、探索了燕山期花岗岩的形成与区域构造演化的关系,认为研究区燕山早期的花岗质岩石,其成因与玄武岩浆的底侵作用密不可分。在燕山早期早阶段,研究区发生陆陆挤压碰撞造山作用导致在茶郴深大断裂两侧存在明显差异后,在燕山早期的晚阶段后碰撞造山的环境下,研究区东面隆起区可能由于具有更厚的陆壳和地幔岩石圈之故,岩石圈根发生大规模拆沉,导致玄武岩浆底侵作用造成中地壳结晶片岩大量熔融,形成大规模岩浆房。同时,相对少量的源于地幔的基性岩浆也沿深部断裂上侵,侵入中地壳源岩浆房中,形成了混合岩浆。8、总结了各岩石组合谱系类型花岗岩类的成矿专属性,建立了找矿标志,分析了找矿潜力,提出了找矿方向。更多还原

【Abstract】 The southeast Hunan polymetallic mineralized concentration area is one important part of the Nanling polymetallic mineralized belt. The abundant polymetallic deposits were related closely with Yanshanian magmatic activities; large and Super scale polymetallic ore deposit, as the Shizhuyuan, Qitianling, Xianghualing, Huangshaping, Baoshan, Shuikoushan and Tongshanling deposit etc.are found in granitic bodies and country rocks. On the basis of researching the features of geological structure and facieology, isotope chronology, mineral chemistry, petrochemistry, microelement analysis and test, isotopic chemistry tracing of the main Yanshanian metallogenetic granitoids, the author studied the classification of rock assemblage and background of geochemistry of different metallogenetic granites, the ore body time-space controls of geological structure as well as the source formation mechanism of granitic magma, the process of regional crust-mantle interaction, mineralization and ore finding orientation etc. and obtained some recognitions as follows: 1. Confirmed rock age by Zircon SHRIMP and other ages, the author founded the chronological framework of metallogenetic granites, The period of granide diagenesis is divided into 4 episodes and the main metallogenetic times is the early Yanshanian, with metallogenetic fastigium of Middle Jurassic(155±10 Ma). 2. Calibrated the lithodemic units of 17 typical metallogenetic granitic bodies. According to proportion of mantle material and the relationship between granitoids and mineralization systems, the author brings forward that the type of metallogenetic granitic assemblages and mineralization systems, which is classified into 4 granitic rock assemblage hierarchies and series of mineralization, namely MS-type, SM-type, C-typical aluminous A-type and strong prealuminous S-type granite. 3. The author studied the components of main rock-froming minerals, major and trace elements geochemistry and mineralization of different metallogenetic granitic assemblages types. 4. Found the mark of crust-mantle mixing effect—mafic microgranular enclaves, revealed the characteristics of the crust-mantle mixed magma based on the geological structure, character of petrography, lithogeochemical tracer of the different types of petrosal assemblages of memtallogenetic granitic bodies, remodeled the former understands about the genesis of Yanshanian granites, and provided new foundation for the research of the relationship crust-mantle mixed granitoids and mineralization. 5. It is revealed that the source of different types of metallogenetic granitic assemblages is mainly crustal materials, with mantle material adding. According to simulative calculation, the proportion of alkali basaltic magma in MS-type, SM-type and C-typical aluminous A-type granites is apart ﹥20%,﹤15% and ﹤10%. 6. based on the analysis of crust-mantle interaction, the author discovered that the earlier units of same granite sequence have lower degree magma mixing, with more mafic microgranular enclaves; and the later units have higher degree magma mixing, with less mafic microgranular enclaves. The author considered that there existed high degree crystal detaching after magma mixing, and the early magma mixing and later crystal detaching were probably the primary forming mechanism of metallogenetic bodies. 7. searched the relationship between granitic forming and regional tectonic evolution, and considered that the genesis of early Yanshanian granitic rocks was related closely to the bottom intrution of basalt magma. In the early stage of early Yanshanian, intercontinental collision mountain-making caused obvious structural difference between two sides of Chaling-Chenzhou Fault; and in the late stage of early Yanshanian with post-orogenic tectonic environment; since the crust and mantle is thicker in east upwarping Region, the lithosphere was delamilated, which caused basalt underplating and brought about melting of a huge amount of crystallized schist in made the middle crust, and large-scale magma room formed. At the same time, relatively less basaltic magma from mantle up-intrusived to middle crustal magma room along the abyssal faults, and fromed the mixed magma. 8. Summarized the metallogenic specialization of each petrosal assemblage type , created marker for ore finding and analyzed ore finding potential and favorable trend.更多还原