皖南宁国竹溪岭钨银矿床赋矿岩体地球化学特征及成岩成矿年代学研究

发布时间：2018-08-20 13:07

【摘要】：宁国竹溪岭钨银矿床是近些年来在皖南发现的一个与花岗岩类关系密切的矽卡岩型钨银矿床。基于对竹溪岭钨银矿床地质特征的研究,本文对竹溪岭钨银矿床赋矿岩体花岗闪长岩的地球化学特征进行了研究,同时应用现代同位素定年技术开展了该矿床及其相关侵入岩体的同位素地质年代学研究,获得主要的认识和成果如下:竹溪岭钨银矿床的矿体主要赋存于南华-震旦系沉积地层、竹溪岭岩体及其接触部位,矿体呈似层状、透镜状产出。矿区发育花岗闪长岩、花岗闪长斑岩和花岗斑岩等3种中酸性侵入岩,LA-ICP MS锆石U-Pb年龄分别为139.8±1.8Ma、140.2±1.7Ma、143.3±1.9Ma,它们在误差范围内一致,为燕山晚期早白垩世岩浆活动的产物。其中,花岗闪长岩为矿区主要岩浆岩体,也是主要赋矿岩体,与成矿密切相关。赋矿花岗闪长岩主量元素特征表明其属于高钾钙碱性系列过铝质花岗岩。微量元素和稀土元素特征显示富集La、Hf、Sm、Y,亏损Nb、Ta、P、Ti。(87Sr/86Sr)i值为0.70655~0.70806,εSr(t)为31.5~52.9,εNd(t)值为-6.1~-7.6,Sr-Nd-Pb同位素特征表明赋矿花岗闪长岩具有壳幔混源特征,以壳源物质成分为主。对矿床矿石中的辉钼矿进行了Re-Os年龄测试,获得两件辉钼矿Re-Os模式年龄分别为142.7±2.1Ma和142.9±2.1Ma,显示矿床成矿年龄与岩浆岩成岩年龄基本一致,成矿也为燕山晚期早白垩世。矿石矿物辉钼矿中Re的含量为63.2×10-6、66.7×10-6,指示成矿物质来源为壳幔混合来源,显示出与与竹溪岭花岗闪长岩成岩物质来源一致的特征。区域岩浆岩及矿床对比表明,与之相邻的长江中下游地区、浙西地区和赣东北地区乃至整个华南地区这一时期都发生了大规模的岩浆作用和钨锡多金属成矿作用,显示扬子板块在此阶段处在一个岩浆-成矿大爆发时期,皖南地区的成矿时代对应于华南中生代三次大规模成矿作用的第二阶段。
[Abstract]:The Ningguo Zhuxiling tungsten silver deposit is a skarn type tungsten silver deposit found in the south of Anhui province in recent years. Based on the study of the geological characteristics of the Zhuxiling tungsten silver deposit, the geochemical characteristics of granodiorite in the ore-bearing rock body of the Zhuxiling tungsten silver deposit have been studied in this paper. At the same time, the isotopic geochronology of the deposit and its associated intrusive rock bodies has been carried out using modern isotopic dating techniques. The main results are as follows: the orebody of Zhuxiling tungsten silver deposit mainly occurs in the sedimentary strata of Nanhua-Sinian system, the Zhuxiling rock body and its contact position, and the orebody is layered and lenticular. The LA-ICP-MS zircon U-Pb age of three intermediate-acid intrusive rocks, granodiorite, granodiorite and granodiorite are 139.8 卤1.8 Ma-140.2 卤1.7 Ma-143.3 卤1.9 Ma. they are consistent within the range of errors and are the product of early Cretaceous magmatic activity in the late Yanshanian. Among them, granodiorite is the main magmatic rock body in the ore area, and is also the main ore-bearing rock mass, which is closely related to mineralization. The main element characteristics of granodiorite indicate that the granodiorite belongs to high potassium calc-alkaline series peraluminous granites. The characteristics of trace elements and rare earth elements show that they are enriched in LahfhfSm (Y), depleted (87Sr/86Sr) I is 0.70655 (0.70806), 蔚 Sr (t) is 31.5 (52.9), 蔚 Nd (t) is -6.1 ~ (-1) -7.6GN ~ (d-Pb) isotopic characteristics, indicating that granodiorite is characterized by crustal and mantle migmatism, mainly crustal material composition. The Re-Os age of molybdenum ore in the deposit is measured. The Re-Os model ages of two molybdenum ores are 142.7 卤2.1Ma and 142.9 卤2.1 Ma.The results show that the metallogenic age of the deposit is basically the same as that of magmatic rocks, and the mineralization is also the early Cretaceous of late Yanshanian. The content of re in molybdenum ore is 63.2 脳 10-6 + 66.7 脳 10-6, indicating that the source of ore-forming material is the mixed source of crust and mantle, which shows the same characteristics as the source of diagenetic material of Zhuxi ridge granodiorite. The regional magmatic rocks and their ore deposits show that large-scale magmatism and tungsten-tin polymetallic mineralization took place in the middle and lower reaches of the Yangtze River, the western Zhejiang region, the northeast Jiangxi area and the whole South China during this period. It is shown that the Yangtze plate is in a period of magma-metallogenic eruption in this stage, and the metallogenic age in southern Anhui corresponds to the second stage of three large-scale metallogenic processes in the Mesozoic of South China.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P597.3;P618.67;P618.52

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