【作者】 朱玉娣；

【导师】 张德会；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2014， 博士

【摘要】 桐村中型斑岩钼铜矿床地处江山—绍兴断裂带北侧的浙西拗陷，邻近江南台隆。桐村矿区隶属钦州—杭州成矿带，该带汇集了德兴、金山和银山等一大批矿床，是我国重要的多金属成矿区。浙江金属矿规模小且贫乏，桐村矿床的发现为浙江多金属找矿提供了现实的研究靶区，深入研究桐村矿床有利于提高对浙西中生代斑岩型矿床的认识。在野外考察的基础上，本文利用岩相学、元素地球化学、Rb-Sr、Sm-Nd同位素地球化学、SHRIMP锆石U-Pb年代学、锆石原位Hf同位素地球化学及H、O、S、Pb稳定同位素地球化学等多种手段，研究桐村矿床的地质、地球化学特征及成岩成矿作用，评价花岗岩含矿性的制约因素，并将其与德兴斑岩铜矿进行全面对比，取得以下进展：（1）SHRIMP锆石U-Pb结果表明，桐村3个岩体形成于中—晚侏罗世，年龄分别为169±2Ma、166±2Ma、157～168Ma。含矿岩体为I型高钾钙碱性花岗岩，富集Rb、Ba、K、U、Th等，亏损Nb、Ta、Zr、Hf、HREE等，具弱Eu负异常，显示岛弧特征；（2）桐村花岗岩具低εNd（t）（–5.8～–0.8）、低TDM（0.80～1.95）、高初始87Sr/86Sr比值（0.7038～0.7143）、宽泛的εHf（t）值（–16.1～15.2）和TDM值（0.60～1.79Ga），表明桐村花岗岩形成于中—晚侏罗世岩石圈伸展体制下，热的软流圈地幔加热新元古代岛弧下地壳使其发生部分熔融；（3）流体包裹体与稳定同位素显示，桐村矿床成矿流体为低温、低盐度的水盐流体和CO2三相流体，成矿物质以下地壳为主，部分来自地幔；（4）桐村岩石偏酸、强氧化、高分异、高分离结晶程度，钼铜矿化潜力大；（5）与德兴铜矿的对比表明，岩石偏酸、高分异与较多地壳混染导致桐村矿床以钼为主，低温、低盐度、缺乏沸腾的成矿流体、较低的岩浆温度与较大的成矿深度限制了桐村矿床的规模。本文的主要创新有发现了古元古代（2.3～1.8Ga）及新元古代（～0.8Ga）地壳增生的同位素证据；将中型钼铜矿与超大型铜钼矿进行全面对比，确定了限制矿床矿种与规模的主要因素；提出了岩浆岩成矿偏爱性。总的来说，桐村矿床的3个杂岩体深部相连，实为同一岩浆源区幕式侵位的结果，形成于中生代岩石圈减薄、下地壳增厚的陆内背景下。成矿深度较大，产出Mo的潜力大于Cu。矿床低温热年代学和熔融包裹体等方面尚待研究。更多还原

【Abstract】 Tongcun medium-sized porphyry Mo-Cu deposit locates in West Zhejiang Depressionand near Jiangnan Orogen, north of Jiangshan-Shaoxing suture zone. It belongs toQinzhou-Hangzhou metallogenic belt, where plenty of ore deposits are distributed such asfamous Dexing, Jinshan, Yinshan deposits. Metallic mineral deposits in Zhejiang arecharacterized by a limited scale and reserves. The discovery and thorough investigation ofTongcun deposit help to better understand the petrogenesis and metallogeny of Mesozoicporphyry deposits in West Zhejiang. Furthermore, based on the research on igneousore-bearing potential, comprehensive contrast on Tongcun and super-sized, neighbourhoodDexing ore deposit has been done to search the essential differences on mineralization typesand scale, and the factors controlling metallogenic potential for granites.On the basis of field investigation, lithology, elemental geochemistry, Rb-Sr、Sm-Ndisotopic geochemistry, SHRIMP zircon U-Pb geochronology, zircon in-situ Hf geochemistryand H、O、S、Pb stable geochemistry are applied in research on characteristics of geology,geochemistry and petrogenisis and metallogeny of Tongcun deposit, evaluation of factorseffecting the granitic metallogenic potential, and considerable comparison with Dexing oredeposit, and the following conclusions are withdrawn:(1) SHRIMP zircon U-Pb geochronology analysis implies that the crystallization ages ofTongcun granites are separately169±2Ma、166±2Ma、157～168Ma, which form as WPG inmedium-late Jurassic lithospheric extension setting. The ore-bearing granites are considered tobe I-type, high K, calc-alkali granites, and rich in large lithophile elements such as Rb、Ba、K、U、Th, depleted in high strength elements as Nb、Ta、Zr、Hf、HREE, with a weak abnormityin Eu and an feature of arc granites;(2) Tongcun granites has low εNd(t)(–5.8～–0.8), low TDM(0.80～1.95), high initial87Sr/86Sr ratio (0.7038～0.7143), broad εHf(t) value (–16.1～15.2) and TDMvalue (0.60～1.79Ga), suggesting that Shuangxiwu Group contributes a lot to the original magma. Siginificantcrust growth of Palaeoproterozoic (2.3～1.8Ga) and Neoproterozoic (～0.8Ga) arediscovered here. Tongcun granites formed in a lithospheric extention setting during medium tolate Jurassic. Neoproterozoic arc and lower crust are heated and melt by underplate hot asthenospheic materials;(3) Fluid inclusions and stable isotopic stydy show that metallogenic fluids are mainlyH2O-NaCl and CO2thriple-faces fluids with low temperature and salinity. Mo originates fromlower crust and Cu is extracted from Neoproterozoic arc and asthenosphere mantle.(4) Tongcun granites have fine potential of Mo-Cu mineralization as the granites arefeatured by more acid, strong oxidation state, fraction and crystallization degree.(5) Comprehensive contrast to Dexing deposit indicates that, Mo-major mineralizationare caused by the feature of granites and more contanmination of crust materials,and thereason of a limited scale is ineffective metallogenic fluids, lower magma temperature andlarger depth of Tongcun ore deposit.Major innovation of the thesis are that:(1) isotopic proof are found in Tongcun deposit ofcrust growth of Palaeoproterozoic (2.3～1.8Ga) and Neoproterozoic (～0.8Ga) time;(2)Main factor controlling the metallic types and scale of deposits are ensured based oncomparison medium-to super-large sized deposits;(3) magma partiality is proposed to betterdescribe the genesis relation between granites and mineralization.Above all,3composit plutons are connected in depth and from episodic intrusion of thesame magma region, forming in a intraplate setting of lithospheric reduction and crustdeepening. The depth of Tongcun deposit is lager and has a better potential for Momineralization relative to Cu. Low temperature geochronology and melt-inclusions areremains to be studied.更多还原