【作者】 张国见；

【导师】 倪师军； 张成江；

【作者基本信息】 成都理工大学 ， 地球化学， 2013， 博士

【摘要】 马脑壳金矿床位于中国重要的“川、甘、陕”成矿远景区的川西北地区,是川西北地区与构造蚀变带有关的微细浸染型金矿的典型代表。近年来深部勘查、外围找矿和矿山开采发现了许多与原有认识不一致的地质现象,特别是越往深部,构造控矿和热液流体活动的迹象明显增强。本文根据对矿床地质特征的进一步研究,分析了矿床控矿因素,总结了成矿规律,探讨了矿床成因,指出了进一步找矿的方向。认为马脑壳金矿床以构造控矿为主,构造破碎岩带是主要矿体赋存部位,构造变形程度控制着矿体的空间分布、产出形态和矿化富集程度。多组构造复合部位是重要的赋矿部位,虽然矿(化)体总体呈北西向展布,但北北东向构造、北西向以及南北向构造复合部位是寻找富大矿体的主要方向。矿床表现出的层控性特点,主要是与不同物理化学性质岩层的岩石组合有关,成能干性(渗透障)与非能干性(不渗透障)岩层的交互叠置和有序排列,导致所有金矿体都产于能干性和非能干性的转换部位,即砂、板岩的接触部位。马脑壳矿床的成矿与传统的卡林型金矿有较大的差异,构造—岩浆活动对成矿起了重要的控制作用,有深部流体参与成矿的迹象,属多因复式成矿特征的大型中低温热液金矿床。马脑壳金矿床是川西北地区与构造蚀变带有关的微细浸染型金矿的典型代表。矿区在大地构造位置上处于华北板块、扬子板块和印度板块三大构造单元衔接部位,区域性玛曲—略阳深大断裂带控制了马脑壳韧—脆性剪切带的空间展布。金矿体受马脑壳韧—脆性剪切带内多期次不同方向断裂、裂隙、节理的控制,构造蚀变岩带是主要矿体赋存部位。由于长期以来受层控矿床观念的束缚,对深部流体与成矿的关系等未引起重视。近年来研究发现,这类金矿床的空间产出与构造—岩浆活动和深部流体的关系极为密切。本论文依托作者负责完成的全国危机矿山接替资源找矿项目“四川省九寨沟县马脑壳金矿接替资源勘查”和四川九寨沟马脑壳金矿开发有限责任公司委托的“马脑壳金矿床成矿规律及找矿方向综合研究”项目,引入深部流体成矿理论和研究方法,在矿床地质特征研究的基础上,采用微量元素地球化学、稀土元素地球化学和同位素地球化学等方法,探讨了矿床成矿流体的来源及成矿作用,总结了成矿规律,指出了进一步找矿的方向。取得以下主要成果和认识：(1)马脑壳金矿床具有一定层控性的特点,无论在区域上还是局部地段,矿体往往倾向于赋存在特定的岩层组合中,表明成矿与地层具有一定的成因关系。我们认为,这除与地层中成矿元素的丰度及元素赋存状态等(即矿源岩)有一定的关系外,更多的是与不同物理化学性质岩层的岩石组合相联系。区内岩石组合在剖面上呈板、砂岩类的互层与韵律排列,因而形成非能干性(不渗透障)与能干性(渗透障)的有序排列与交互叠置。区域内,几乎所有金矿床(体)都产于非能干性和能干性的转换过渡部位,即板岩、砂岩的接触过渡部位。(2)马脑壳金矿床以构造控矿为主。金矿体受马脑壳韧—脆性剪切带内多期次不同方向断裂、裂隙、节理的控制。构造破碎岩带是主要矿体赋存部位,构造变形程度控制着矿体的空间分布、产出形态和矿化富集程度。金矿体(矿化)在矿化构造破碎岩带内呈透镜状、脉状、复脉状产出,膨缩、分枝复合较频繁,金矿体不严格受地层的制约。首次提出多组构造复合部位是重要的赋矿部位,虽然矿(化)体总体呈北西向展布,但北北东向构造、北西向以及南北向构造复合部位是寻找富大矿体的主要方向。(3)马脑壳矿床的地质地球化学特征显示出,成矿与传统的卡林型金矿有较大的差异,构造—岩浆活动对成矿起了重要的控制作用,有深部流体参与成矿的迹象。热液矿物石英、方解石等的微量、稀土元素地球化学研究表明,马脑壳金矿床的成矿物质和成矿热液,既有通过改造沉积建造来自浅部的,也有通过区域深大断裂来自于深部的。马脑壳金矿床成因主要是由混合型变质成矿流体与岩浆热液成矿流体叠加形成,具有多因复式成矿特征的大型中低温热液金矿床。(4)马脑壳地区成矿地质背景有利,成矿条件良好,矿化信息显著,具备了形成超大型微细浸染型金矿矿集区的成矿条件,其外围及深部找矿潜力巨大。马脑壳韧—脆性剪切带的东端和西端具有较好的找矿远景,是该区外围找矿的主要靶区；矿区北部F1断裂紧邻北部的洋布梁子断裂,构造—流体活动强烈,具有较好的找矿前景；马脑壳成矿带以东地区的八顿、小神沟、绕腊沟一带邻近荷叶断裂,成矿地质条件与马脑壳成矿带相似,且该区岩浆活动明显强于马脑壳地区,并发现有金矿点和矿化点存在,化探异常也较好,是今后找矿工作的重点地区；加大马脑壳矿区深部找矿力度,探寻深部富大矿体,是该区今后找矿的主要方向。更多还原

【Abstract】 As a typical representative of the fine-disseminated gold deposits related with the tectonic alteration zone, Manaoke Gold Deposit is located in the northwestern Sichuan province. Geotectonically, the Manaoke Gold Deposit lies in the junction of North China Plate, Yangtze Plate and Indian Plate, where the spatial distribution of the Manaoke brittle-ductile shear zone is controlled by the regional Maqu-Lueyang deep fractured zone.The location of ore bodies are controled by the multi-stage fracture, cracks and joints of different directions, and the tectonic alteration zone is the mainly favorable parts for bonanza ores.In the past, the research on the connection between the mineralization and the fluid derived from the depth of the Earth is ignored for a long time, as a result of manacle by the traditional idea of the stratabound deposit theory. Recently, research has found that the deposits of this type is close in space with the tectonic-magmatic activities and the deep fluid.Based on the Project of Superseding Resources Exploration for the State Crisis Mine-"Superseding Resources Exploration to the Manaoke Gold Deposit in Jiuzhaigou County, Sichuan Province" and the cooperative item of "Comprehensive research on the Metallogenic Regularities and Ore-prospecting Direction of Manaoke Gold Deposit in Sichuan Province" from Manaoke Gold Mine Development Co., LTD in Jiuzhaigou County, Sichuan Province, this doctoral dissertation intends to introduce the theory and research method of the deep fluid mineralization. With systematically study on the stable isotopes and the geochemistry of the trace and rare earth elements, the source of the ore-forming fluid and the mineralization are identified on basis of the study of the geological feature of deposit, the metallogenic regularities the deposit are summarized, and prospecting orientation is outlined.The doctoral dessertation achieves the following main results and understanding:(1) Manaoke Gold Deposit has certain layer-controlled characteristics. No matter in regional or in isolated areas, the gold-rich ore bodies tend to locate in a special combination of different stratums, which shows that the mineralization is related to the stratum. Outside the abundance and the occurrence state of the metallogenic elements, stratums combination of different physicochemical properties should assume more responsibility for this. In profile, the lithology association is rhythm of sandstone and slate, which help to form superimposed relationship and ordered arrangement of competent (permeable barrier) and incompetent (impermeable barrier). Almost all of the gold ore bodies occur in transfer sites between competent and incompetent, that is the contact belt of sandstone and slate.(2) Manaoke Gold Deposit is primarily controlled by the structure. The location of ore bodies are controled by the multi-stage fractures, cracks and joints of different directions in the Manaoke brittle-ductile shear zone, and the tectonic alteration zone is the mainly favorable part for bonanza ores. Without strict restriction by the stratum, the gold ore (mineralized) bodies, where the expansion and shrinkage with branching complex are a familiar phenomenon, occur mainly as nervation, net nervation, podiform in the tectonic alteration zone. For the first time, the compound positions of polytectonic faults, which is the mainly favorable parts for bonanza ores, is presented in this paper. Although the occurrence of the ore bodies are mainly NW, the compound positions of the NNE, NW and NS structures are the favorable position to find the rich and large ore bodies.(3) The geological and geochemical characteristics of Manaoke Gold Deposit show obvious difference with the traditional "Carlin-type Au deposit". The tectonic-magmatic activities play an important role in controlling ore bodies, as well as obvious signs of deep source fluid involved in metallogenesis. The geochemistry of trace and rare earth elements in hydrothermal minerals, such as quartz, calcite, etc. indicate that the ore forming materials and ore forming hydrothermal solution have multi source, part from the deep through the deep and large faults, part from the shallow through the transformation of sedimentary formations. The formation of ore bodies is closely related to the Mixed metamorphic ore-forming fluid and superposition by the magmatic hydrothermal fluid. Manaoke Gold Deposit belongs to a large scale medium-low temperature hydrothermal gold deposit of polygenetic compound characteristics.(4) With favorable geological mineralization setting, favourable metallogenetic conditions and significant mineralization information, the Manaoke Gold Deposit, whose depth and periphery are enormously potential for ore prospecting, possesses the prerequisite of super large ore concentration area of the microfine disseminated gold deposits. The west and east of the Manaoke brittle-ductile shear zone, as the prospecting direction and targets of the periphery, have a good exploration prospect. The North of the ore area, where the F1fracture is adjacent to the northern Yangbuliangzi fault, with the features of intense tectonic movements and fluids, are prospecting potential. Near the east Manaoke metallogenic belt and adjacent to Heye fault, with the similar metallogenic characteristics and favourable geochemical prospecting anomaly, the Badui, Xiaoshengou and Raolagou area, where magmatism are obviously more violent and gold occurrences (mineralized points) have been found, is the key place for prospecting henceforth. A great effort for ore prospecting for the deep large orebody in Manaoke gold ore field is the main prospecting object for the future.更多还原