【作者】 蔡明海；

【导师】 战明国； 彭松柏；

【作者基本信息】 中国地质科学院 ， 构造地质学， 2002， 博士

【摘要】 本文通过对桂东-粤西地区成矿地质背景、典型矿床、矿床时空分布、中生代构造变形以及中生代花岗岩类岩石学、地球化学特征研究，获得了桃花金矿、东桃铅锌矿和长坑-富湾金银矿的成矿年龄数据：总结了区内矿床的时空分布规律，划分了成矿区带，厘定了矿床成矿系列：探讨了成矿动力学机制，提出了区域热流值增高是区内构造动力学机制转换和成矿的动力来源的新认识。长坑-富湾金银矿石英Rb-Sr等时线测年值（长坑金矿128±3Ma，富湾银矿62±1.7Ma）表明其成矿时代属燕山晚期。控矿构造特征研究表明，长坑金矿受早白垩纪（K₁）滑脱构造控制，富湾银矿则与晚白垩（K₂）控矿构造进一步伸展滑脱有关。金银矿是同期不同阶段的产物，控矿构造的差异导致了金银矿体的空间分离。通过桂东大瑶山隆起区内桃花金矿成矿地质背景、矿床特征、S、Pb、H、O同位素地球化学特征以及稀土和微量元素研究，提出了桃花金矿属沉积-改造成因，成矿过程经历了早寒武世沉积富集、加里东晚期岩浆热液成矿和后期热液改造成矿，后者为主成矿期的新认识。主成矿期石英脉中流体包裹体Rb-Sr等时线年龄为148±10Ma，属燕山早期。金浸取试验结果表明，桃花金矿矿石中的金以微细-超微细金为主。桃花金矿成因的新认识对大瑶山隆起区找金工作具有重要指导意义。通过野外调查和同位素年代学研究表明，东桃铅锌矿区构造活动经历了加里东期逆掩推覆（Rb-Sr等时线年龄为426±15Ma）和燕山早期滑覆作用，成矿受产于奥陶系砂岩和页岩中的层间滑脱构造控制。矿石全岩Rb-Sr等时线年龄为152±3Ma，代表了热液改造成矿时代。东桃铅锌矿的成矿过程经历了中奥陶世初始沉积富集和燕山早期热液改造成矿作用，矿床类型为沉积-改造型。早期推覆、后期滑覆，成矿受滑覆构造控制的构造模式在桂东-粤西地区具有普遍意义。通过野外调查，本项目组在富贺钟古生代拗陷区发现了一种新类型锡矿（观音山锡矿），锡矿体严格受近SN向断裂构造控制，并以少硫化物为特征，其矿床类型为构造蚀变岩型。这种构造蚀变岩型锡矿在南岭地区具有较好的找矿前景。通过成矿年龄数据和矿床空间分布特征研究，作者将研究区划分为2个成矿单元（湘桂成矿单元和华夏成矿单元）和6个成矿区带（富贺钟W、Sn、Sb、Pb、Zn成矿区、三水Au、Ag、Cu、Pb、Zn成矿区；大瑶山-怀集Au、Cu、Pb、Zn成矿带：博白-岑溪-罗定-广宁Au、Ag、Cu、Pb、Zn成矿带；信宜-廉江Au、Cu、Pb、Zn、Sn成矿带：新兴-阳春Cu、Pb、Zn、Sn成矿带）。燕山早期和燕山晚期是区内2个最重要的成矿期，且自北西至南东（大瑶山隆起区→云开隆起及周缘→粤中三水盆地）中生代成矿时代总体显示出由老到新的演化趋势（150Ma±→70Ma±）。研究区内有色、贵金属矿床可分为7种类型，即：剪切带型、构造蚀变岩型、斑岩型、夕卡岩型、热液脉型、微细浸染型和沉积-改造型。本文厘定了7个矿床成矿系列和3个成矿系列组合。其中，湘桂成矿单元有：Ⅰ-燕山早期中酸性花岗岩类有关的W、Sn、Sb、Pb、Zn矿床成矿系列：Ⅱ-燕山晚期酸性花岗岩类有关的W、Sn矿床成矿系列；Ⅲ-燕山早期构造-热事件有关的Au、Ag、Cu、Pb、Zn矿床成矿系列。上述三个成矿系列可归并为一个成矿系列组合，即燕山期岩石圈构造转换-伸展剪切有关有色的、贵金属金属成矿系列组合。华夏成矿单元有：Ⅰ-燕山早期中酸性花岗岩类有关的Au、Ag、Cu、Mo、W、Sn矿床成矿系列：Ⅱ-燕山晚期中酸性-酸性花岗岩类有关的Au、Ag、Cu、Mo、Pb、Zn、W、Sn矿床成矿系列：Ⅲ-韧性剪切带有关的Au、Ag矿床成矿系列：Ⅳ-加里东晚期构造-热事件有关的Au矿床成矿系列。上述4个成矿系列进一步归并为2个成矿系列组合，即：1-加里东晚期岩石圈挤压收缩有关的Au矿床成矿系列组合；Ⅱ-燕山期岩石圈构造转换-伸展剪切有关的有色、贵金属金属成矿系列组合。通过桂东-粤西地区中生代花岗岩类岩石的岩石学、矿物学和地球化学以及区域构造变形特征研究表明，区内岩石圈构造经历了201×10⁶～277×10⁶a之间碰撞挤压、152×10⁶a～163×10⁶a间由挤压到伸展的构造转换及80×10⁶a～120×10⁶a之间伸展剪切三个阶段的演化过程。成矿作用集中于中侏罗纪和白垩纪，分别与区内构造转换和伸展剪切构造阶段相对应，区域构造动力学机制转换是中生代大规模成矿的一级控制因素，矿床定位则受局部动力学转换部位控制。根据中生代花岗岩放射性生热元素含量分析数据进行了热流值的计算，前加里东期平均热流值为A=2.33μw／m³，海西-印支期A=3.07μw/m³，燕山早期A=4.52μw／m³，燕山晚期A=4.47μw／m³，表明中生代时期区内热流值大幅度增高，热流值的增高导致了岩浆的底辟侵位和岩石圈的减薄，区内构造动力学机制转换和成矿的动力主要源自岩石圈自身热流值增高。更多还原

【Abstract】 Through detailed studies on the geological background, tectonic features, representativedeposits, spatial-temporal distribution characteristics of deposits and Mesozoic granite ineastern Guangxi and western Guangdong, the metallogenetic epoch of Taohua gold deposit,Dongtao lead-zinc deposit and Changkeng-fuwan gold-silver deposit was determined. Theauthor also sums up the regularity of spatial-temporal of deposits in the studied area,establishes metallogenetic series and discusses mineralization dynamic mechanism.According to Rb-Sr isochron age of quartz （Changkeng gold deposit: 128±3Ma; Fuwansilver 62±1.7Ma）, the minerogenetic epoch of Chengkeng-Fuwan gold-silver depositbelongs to later Yenshan movent. Study on the ore-controlling tectonics indicates that the golddeposit controlled by early stretching during early Cretacceous （K₁）, the silver depositcontrolled by latterly stretching during late Cretacceous （K₂）. The gold and silver depositswere formed in the same epoch, but in different stages, the different structural pattern resultsin the separation between gold and silver bodies.Based on the studies of geological background, deposit characteristics, S, Pb, H, Oisotope geochemistry, rare earth and trace elements of Taohua gold deposit in Dayaoshanuplift, eastern Guangxi, the author points out the genesis of Taohua gold deposit belong tosedimentary enrichment-hydrothermal reformation type. Ore-forming process has undergonesedimentary enrichment during early Cambrian, magmatic hydrothermal mineralizationduring latterly Caledonian movement, and later hydrothermal rework which is the mainmineralization period. Rb-Sr isochron age of fluid inclusion in quartz formed in mainmineralization period is 148±10Ma, belong to early Yenshan movement. The experiment ofgold lixiviation indicates the gold of Taohua deposit mainly occurred as fine-superfine grain.The new point view of the ore genesis of Taohua deposit has a significant bearing on oreprospecting in Dayaoshan uplift.Field investigation and isotopic geochronology indicates the structural movement inDongtao lead-zinc deposit underwent early napping during Caledonian affiliation （Rb-Srisochron age of granite is 426±15Ma） and late stretching. The stretch fault betweenOrdovician sandstone and shale controls the distribution of orebodies. The Rb-Sr isochron ageof total ore is 152±3Ma, the age represents the minerogenetic epoch of latterly thermal fluidsuperimposed mineralization. The ore-forming process of Dongtao lead-zinc depositunderwent initial concentration during Ordovician and thermal fluid superimposedmineralization during early Yanshan movement. The type of ore genesis belongs tosedimentary reformation. The early napping and late stretching and stretch fault controllingthe distribution of orebodies have a widespread significance in eastern Guangxi and westernGuangdong.Through field investigation, a new type tin deposit was discovered in FuhezhongPalaeozoic sag （Guanyinshan tin deposit）. The tin orebodies are strictly controlled by SNdirection faults, and contain minor amount of sulfide, belong to tectonic alteration tin deposit. The tectonic alteration tin deposit has shown a good prospecting potential Huanan area.Based on the age data analysis and spatial distribution characteristic of deposits, theauthor divides the area into two metallogenic units （Xianggui metallogenic unit, Hhuaxiametallogenic unit） and six mineralization belts or region （there are Fuhezhong W, Sn, Sb, Pb,Zn mineralization region; Sanshui Au, Ag, Cu, Pb, Zn mineralization; Dayaoshan-Huaiji Au,Cu, Pb, Zn mineralization belt; Bobai-Cenxi-Luoding-Guangning Au, Ag, Cu, Pb, Znmineralization belt; Xinyi-Lianjiang Au, Cu, Pb, Zn, Sn mineralization belt;Xinxing-Yangchuen Cu, Pb, Zn, Sn mineralization belt） in eastern Guangxi and westGuangdong. Early Yanshan movement and late Yanshan movement are the mainmineralization epoch in this area.The deposits of eastern Guangxi and western Guangdong can be classified as seven types（shear-zone deposit; tectonic alteration deposit; porphyry deposit; skarn deposit; hydrothermalvein deposit; micro-disseminated deposit; sedimentary-reformation deposit） and seven depositmetallogenetic series. In Xianggui metallogenic unit, there are:Ⅰ) W, Sn, Sb, Pb, Zn depositmetallogenetic series, it is related to early Yanshan movement intermediate-acid granite;Ⅱ)W, Sn deposit metallogenetic series, related to late Yanshan movement acid granite;Ⅲ) Au,Ag, Cu, Pb, Zn deposit metallogenetic series, related to early Yanshan movementtectonic-thermal event. All of these three metallogenetic series can be merged as one group ofmetallogenetic series, i.e. precious metal and nonferrous metal metallogenetic series grouprelated to tectonic dynamic mechanism transform in Yenshan movement. In Huaxiametallogenic unit, there are:Ⅰ) Au, Ag, Cu, Mo, W, Sn deposit metallogenetic series, it isrelated to early Yanshan movement intermediate-acid granite;Ⅱ) Au, Ag, Cu, Mo, Pb, Zn, W,Sn deposit metallogenetic series, related to late Yanshan movement intermediate-acid and acidgranite;Ⅲ)Au, Ag deposit metallogenetic series, related to ductile shear-zone;Ⅳ)Audeposit metallogenetic series, it is related to late Caledonian tectonic-thermal event. All ofthese four deposit metallogenetic series can be merged as two groups of metallogenetic series,i.e. gold metallogenetic series group related to the lithospheric compression in LateCaledonian and nonferrous and precious metal metallogenetic series group related to thelithospheric tectonic transformation in Yanshanian epoch.The study on the petrology, mineralogy and geochemistry of the Mesozoic granite andanalysis on the features of tectonic transmutation in Eastern Guangxi and Western Guangdongindicate that lithosphere in the studied area has undergone three evolution phases: thecollision between 224～265Ma, the tectonical transformation from compression to extensionbetween 154～160Ma and the extension between 80～100Ma. The metallogenesis wasconcentrated in mid-Jurassic and Cretaceous, and controlled by the tectonical transformationof lithosphere in early Yanshanian and by the shear-extension in the late Yanshanianrespectively. The tectonic dynamics transformation is the first order of ore-controlling factorfor the Mesozoic massive mineralization in this area. The distribution and localization of thedeposits were controlled by the transformation of local dynamic system.According to granitic rock heat flow value （A） calculating, the average heat flow value（A） is 2.33μw/m³, 3.07μw/m³, 4.52μw/m³, 4.47μw/m³ in Hercynian-Indo-chinese epoch,early Yenshan and latterly Yenshan respectively. These data indicate regional heat flow value increased greatly in Mesozoic, and the heat flow value increasing results in magmaunderplating and lithosphere thinning. The geodynamic mechanism for the tectonictransformation is related to the increasing of heat flow value in lithosphere itself.更多还原