【作者】 何进忠；

【导师】 姚书振；

【作者基本信息】 中国地质大学 ， 矿物学、岩石学、矿床学， 2008， 博士

【摘要】 全文以造山带成矿学、地球化学及自组织临界成矿理论为指导,以前人对区内的基础地质及矿床地质研究成果、西秦岭区域地球化学资料、矿床地球化学资料为依据,系统论述了本地区各地质单元的物质组成、金属矿床成矿规律、成矿地球化学过程、矿床地球化学场结构、矿床区域地球化学成矿预测模式及典型矿床的大中比例尺成矿地球化学预测模式。取得了一系列成果。1.区域成矿地质背景1.1地层物质成份秦岭群、蓟县系、青白口系、丹凤群、中志留统舟曲组、中泥盆统舒家坝组、中石炭统下加岭-东扎口组物质组成相对复杂,包含了深源基性元素、陆源碎屑岩元素及热水沉积元素组合;中秦岭的晚古生代地层富集蒸发盐建造的元素组合,其中的Pb、Hg、Cd具有临界沉积特征;南秦岭的Fe、Mn、Zn、Mo、Ba等有临界沉积特征;新元古代以来,生物及热水沉积作用参与了部分地层的沉积过程。1.2侵入岩物质成份晋宁期中基性侵入岩富集Cu、Pb、Zn、Ni、Fe等成矿元素。加里东期中性侵入岩富集相容元素。海西期侵入岩均富集气水热液蚀变岩元素,大部分岩体富集高场强元素,部分岩体富集相容元素。印支期侵入岩石英二长闪长岩及温泉花岗岩等岩体富集相容元素,柏家庄等二长花岗岩富集偏碱性元素Nb、K、Y等。燕山期,中秦岭西段的岩体富集铁族元素和亲硫元素,东段富亲石元素和亲硫元素。1.3地壳演化与深部构造据对地层的以惰性元素为变量的Q型聚类分析、La/Th比值、La/Y—La/Co图解,花岗岩类的R1-R2和Nb-Y图解,岩石圈结构,及前人观点,认为加里东期以来至泥盆纪的花岗岩类可能是对早晋宁期扬子板块与华北板块碰撞过程的延续性响应,早泥盆世后随着勉略洋的消减,扬子与华北开始汇聚造山,碰撞点历经自东向西迁移,直至中生代陆内造山。中生代以来中秦岭的岩浆活动及有关的成矿作用与断离、拆沉的松潘-甘孜地块发生的构造热侵蚀有关。碧口群中的蓟县系阳坝组和秧田坝组,是在印支运动后才出露的。2.成矿规律2.1成矿年龄统计结果显示,沉积成矿作用成矿峰期为志留纪和泥盆纪,并且主要集中于中晚志留世和中泥盆世;热液成矿作用仅显示于石炭纪以后,成矿峰期为三叠纪和侏罗纪。相对岩脉,成矿并不总是滞后的,但发生于断裂剧烈活动开始10Ma之后。2.2矿床空间分布利用矿床的空间信息定量地圈定出夏河、临潭、宕昌、武都、李子园、成县及伐子坝等7个矿床集中区,其中以成县集中区呈现金属矿床集中区的面积及强度为最,其次为临潭集中区和夏河集中区。以中秦岭所占比例相对较高。有相当一部分矿床处于距离深断裂0-10km的范围内,大部分金属矿床分布于距离侵入体5km的距离以内,具有多（五）标度分形特征;大多数矿床（点）之间的距离集中于小于6km的范围内,具有面型分布。均具有多标度分形特征,多因素协同作用特征。2.3金属矿床成矿系列与成矿系统在陈毓川等所界定的成矿系列概念的基础上,本文根据具体情况制定了划分原则,进而将西秦岭金属矿床划分为10个成矿系列、13个亚系列、30个矿床式,其中铁成矿系列3个、铁铜多金属成矿系列2个、铜（钼）成矿系列2个、铅锌成矿系列1个、汞锑成矿系列1个、金成矿系列1个。在翟裕生所界定的成矿系统概念的基础上,本文根据具体情况制定了划分原则,进而将该区的成矿系统划分为6个成矿系统大类、9个成矿系统类、11个成矿系统。2.4矿床资源量生长过程矿床资源量的吨品位关系能用指数函数或直线方程更好地拟合,吨品位的双对数图由三条线段组成,k矿体资源量双对数图由四条线段组成等事实及数学推导证明,矿床吨-品位关系方程应表述为由非线性增殖过程线性叠加而实现的指数函数。3.成矿地球化学过程3.1成矿物理化学条件次火山热液亚系列钼矿处于100-420℃之间;热水沉积铅锌矿系列和热液金矿系列较为接近,处于60-480℃之间,其中沉积铅锌矿系列集中于80-120℃,热液金矿系列集中于150-300℃;沉积改造锰矿系列的成矿温度为25-32℃。利用CO₂体系的MRK方程和NaCl-H₂O体系的盐度、密度、温度等和压力的关系估计的所有矿种的压力值均处于1km以内。改造型铅锌矿床形成的压力普遍高于沉积型铅锌矿床,但改造成矿作用有伴随压力突然降低的减压和不混溶过程。各矿种产出的Eh-pH条件范围的大小,基本与相应矿种的矿产地数量正相关。3.2成矿地球化学过程根据矿石物质成份、成矿流体成份、成矿物理化学条件,以文字及化学方程的形式描述了区内不同成因的铁、锰、铜、铅锌、金、汞、锑等金属的成矿过程。不同矿种、不同成矿亚系列的成矿过程不尽相同。矿床地球化学场具有多重分形特征。按双对数曲线的拐点数,将39种元素的地球化学场分为单富集、两重富集、三重富集、四重富集、五重富集等5个类型。大中型矿床与三重以上富集过程有关。4.金属矿床的区域地球化学场结构从线性和非线性两种角度描述了铁、锰、铜、铅锌、金、汞、锑等矿床的区域地球化学场结构。总体看来,尽管各矿床地球化学场的组份特征不同,但主要成矿元素的结构参数有一定的相似性。如矿床所处部位一般为中等含量的异常区,除少数矿床外,一般与峰值不对应;半变异函数的变程一般为0.7—0.9,具有明显的随机场特征;南北向静态斑图熵小于东西向静态斑图熵,南北向布朗分数维大于东西向布朗分数维,指示南北向的变化程度相对复杂;除极少数铁矿外,几乎所有矿床均处于奇异指数小于2.0的地带,铅锌、金、汞锑矿床的奇异指数一般小于1.8,该指数对圈定不同矿种的成矿区域确实具有成效。对部分金属矿床的地球化学场,求解的Lyapunov指数表明,Pb、Zn等成矿元素的区域地球化学场具有临界特征,但表生条件下的活动性元素Cu、Mo趋于稳定结构,人工采矿污染使Hg、Sb等的区域地球化学场具有明显的混沌特征。5.区域地球化学场成矿预测模式建模方法有效性评估结果表明,线性回归效果相当好,可以很好地区分出不同规模等级的矿床;其次为逻辑信息法,再次为本文提出的因子计量模型重构法,证据权法显示的元素组合看起来很合理,但模型的应用结果很不理想。进一步以线性回归法为主建立了区内沉积改造型铁矿、沉积变质型铁矿、风化淋滤型铁矿、沉积改造型锰矿、矽卡岩型铜矿、斑岩型铜矿、热液型铜矿、VMS型铜矿、沉积型铅锌矿、改造型铅锌矿、岩浆热液型金矿、沉积改造型金矿、汞矿、锑矿等14个区域地球化学成矿预测模式。6.大比例尺成矿地球化学模型及矿产勘查中的重正化问题6.1代家庄铅锌矿床原生晕沉积成矿作用形成的原生晕分带是:自中心向外Fe-Au-Bi-Sr-W-Cr-Pb-Hg-Co-Sb-Ni-V-Mo,由中心的热水沉积物过渡到外侧的还原环境下的正常沉积组份;改造成矿作用形成的原生晕分带是:自中心向外Cu-Zn-Mo-Pb-Sn-W-Hg-Ni-Co,由中心的多金属硫化物过渡到外侧的热水沉积建造的组份。Lyapunov指数显示,中低温热液成矿组份Hg等具有时空自组织临界性:中高温热液成矿组份Cu、Zn、Bi等仅具频率域的自组织临界性,在空间域表现为稳定的地球化学场结构。采用其组合指标[PB*W]/Cu²及幂函数拟合得到的深部资源量预测模型,其方差贡献达99.526%,拟合精度较高。6.2代家庄铅锌矿床土壤地球化学晕利用分带指数法计算得到的测向分带顺序是:由里向外Sn-Cu-W-Mo-Ag-Zn-Pb-As-Sb,与热液矿床中元素的分带顺序基本一致。Lyapunov指数显示,成土作用使大部分成矿元素的地球化学场趋于稳定结构。但元素在土壤中的功率谱特征对岩石具有继承性。建立了以土壤Ag异常面积为变量的数学模型,验证效果较为理想。6.3 1∶5万水系沉积物晕地球化学晕Lyapunov指数、频率域的1/f现象指示,地表流水的冲刷会使一些原生晕中处于稳定结构的元素趋于临界或混沌状态,从而产生一些可能与矿化无关的异常,使水系沉积物的找矿应用复杂化。成矿元素及其亲硫指示元素在频率域的低频段普遍呈现相对1/f现象的偏移,而个别元素Cu则在频率域表现为混沌无序。多元素组合异常图显示出以Pb为中心的元素分带,自中心向外为Pb-Cu-Zn-Mo-As-Hg-Ag;而铅的单元素异常图则表现为以代家庄铅锌矿床为中心且与地层走向近于垂直的近NEE向的环状分带模式表明,这些近环状分布的铅异常主要由改造成矿作用形成。依据成矿及指示元素表生条件下的地球化学性质,及自组织临界现象的论述,选择与成矿元素关系密切、且稳定性相对较高的Pb、Zn、As、Sb、Hg等元素的异常面积为建模变量,建立了预测模型,验证结果较为理想。6.4矿产勘查中的重正化群问题通过矿产勘查中的重正化群问题研究表明,对于1/20万、1/5万和1/1万等三种勘查尺度,在进行勘查工程的布置时,在不考虑其它因素的情况下,应该在已圈定的异常的基础上,向外分别扩延6.5km、0.16km和0.002km。当异常点的频率小于10%时,异常频率对异常的关联长度影响不大,对关联长度起决定作用的是工作比例尺。更多还原

【Abstract】 Under the guidances of Orogenic Metallogeny, Geochemistry, and Self-Organized Criticality, and on the basis of previously basic geology, geology of mineral resources, and the data of regional geochemistry and mineral geochemistry, this paper had given a systematic state and acquired a number of results about a series of topics in west Qinling, such as composition of all geological units, metallogenic regularities, geochemical processes of ore-forming, patterns of geochemical fields of metallic deposits, geochemically metallogenic forecast models of mineral deposits, and large-middle scale of forecast models of typical ore deposits.1. Regionally geological backgrounds1.1 The compopsitions of strataSome strata, such as Qinling Gr, Jixian System, Qinbaikou System, Danfeng Gr, meso-Silurian Zhouqu Fm, meso-Devonian Shujiaba Fm, meso-Carbonaceous combined Xiajialing-Dongzakou Fm, have diversified compositions in which there are basic elements from depth, clastic elements from continents, and the elements from hydrothermal sediments. Upper Palaeozoic Erathem in mid-Qinling is richer in the assemblage of evaporate, and has characteristics of critical mineralization of the element Pb, Hg, and Cd. South Qinling has that of the element Fe, Mn, Zn ,Mo, and Ba. Since Neoproterozoic Era, organism had anticipated in the processes of part of strata.1.2 The compositions of intrusive rocksJinning intermediatie-basic intrusive rocks are rich in the metallogenic elements Cu, Pb, Zn, Ni, and Fe. Caledonian intermediate rocks are rich in the elements from hydrothermal alteration, most of which are rich in HFSE, and part of which are rich in compatible elements. Indosinian quartz monzonite and Wenquan granites are rich in compatible elements, and the monzonitic granites of the same ages such as Baijiazhuang rock mass are rich in alkaline elements as Nb, K, and Y. The Yanshanian rock mass in western section of mid-Qinling are rich in Ferrous group elements, and that in the eastern section are rich in lithophile elements and thiophile elements.1.3 The crustal evolvement and deep structuresOn account of the strata with their diagram of claster analysis from immobile element, their diagram of La/Y—La/Co, and their ratio of La/Th, the intrusive rocks with their diagrams of R1-R2 and Nb-Y , the lithospheric tectonic, and previous points of view, it was thought that, the granitoid formed from Caledonian to Devonian were probably the durative responses to early Jinning convergency of Yangtse plate and north China plate. From early Devonian to Mesozoic, Yangtse plate and north China plate had gradually converged companied by shrinking of Mianlue ocean, the collided point had migrated from east of Devonian to west of Mesozoic until incontinental orogenesis of Mesozoic occurred. The magmatism in mid-Qinling and involved mineralization since Mesozoic were related to tectono-thermal erosion from subducted and ruptured Songpan plate. The Yangba Fm of Jixian System and Yangtianba Fm of Qinbaikou System in Bikou Gr didn’t outcropped there until Indosinian movement.2.Metallogenic regularities2.1 Metallogenic agesThe statistics about metallogenic ages showed that, the peak period of sedimentary mineralization was Silurian and Devonian, in which was principally meso-late Silurian and meso Devonian. The hydrothermal mineralizations occurred mainly after Carbonaceous in which peak period of mineralization was Triassic and Jurassic. Behind veins mineralizations didn’t always lagged, but lagged 10 Ma later behind faults functioned.2.2 Mineral distribution in spaceBy making use of mineral space information, 7 concentrational areas, such as Xiahe, Lintan, Dangchang, Wudu, Liziyuan, Chengxian, and Faziba, are delineated, of which the Chengxian area presents itself as the maximum in area and intensity, and subsequently the Lintan and Xiahe. In tectonic units, the mid-Qinling takes the maximum of concentrational areas.A large amount of deposits or occurences stand in the range of 0-10Km away from deep faults, most of which in the range of 5Km away from intrusive masses, and most of which occur in the range of 6Km away from each other and has a plannar distribution model. The distances from deep faults, intrtusive masses to deposits or occurences, and from deposits or occurences each other are respectively characterized by multifractals.2.3 Metallogenic series and metallogenic system of metal mineral depositsA rule for compartmentalizing metallogenic series was concretely set up on the basis of concept of metallogenic series defined by Chen Yuchuan, and eventually all metallic mineral deposits were divided into 10 metallogenic series, 13 sub-metallogenic series, and 30 types, in which there are 3 for iron, 2 for iron, copper, and multimetals, 2 for copper or molybdenum, 1 for lead and zinc, 1 for mercury and antimony, and 1 for gold.Also was concretely set up a rule for compartmentalizing metallogenic system on the basis of concept of metallogenic system defined by ZHAI Yusheng, and finally the metallogenic system in west Qinling were divided into 6 big clasters of metallogenic system, 9 clasters of metallogenic system, and 11 metallogenic system.2.4 The growing processes of mineral resourcesThe facts of tonnage to grade of mineral resources can be fitted by exponential and linear functions, double logarithm plots of tonnage to grade and that of orebody resources consist of 3 or 4 line sections, and deductive results from maths born out that, the equation of tonnage to grade of mineral deposits can be described as exponential equation from linear addition of nonlinear multiplication processes.3. Geochemical processes of ore-forming3.1 Physical and chemical qualifications of ore-formingThe metallogenic temperatures of subvolvanic hydrothermal subseries of molybdenum ores were 160-180℃; those of hydrothermal sediment series of lead-zinc ores and hydrothermal series of gold ores were all between 60℃and 480℃, but the concentrative temperatures of lead-zinc series of ores and hydrothermal series of gold ores were 80-120℃and 150-300℃respectively; and those of sedimentary manganese ore series were 25-32℃.With the help of MRK equation of CO₂ system, and the relation of salty, density, and temperature to pressure of NaCl-H₂O system, the lithostatic pressures estimated are all within 1 Km, that of reconstructed ores were generally higher than that of sedimentary ores but reconstructed ores acompanied by abrupt decompression and exsolution processes. The ranges of pH and Eh of diversified ore deposits are positively correlative to their amount of ore deposits or occurrences.3.2 Geochemical processes of ore-fomingFrom the composition of ore and metallogenic fluids, and the physical and chemical qualifications of minerlalization, the geochemical processes of mineralization of different genesis of metallic ore deposits, concretely, that of iron, manganese, copper, leadand zinc, gold, mercury, and antimony, had been described. The metallogenic processes varied with metals and metallogenic subseries.The geochemical fields of 39 elements are characterized by their multifractals, which wre further divided into single concentration, double concentrations, triple concentrations, fourfold concentrations, and quintupling concentrations, and the large-mid size of deposits were all from more than triple concentrating processes.4.Patterns of regionally geochemical fieldsThe patterns of metallic geochemical fields, i.e. that of iron, manganese, copper, lead and zinc, gold, mercury, and antimony, were depicted from the angles of linearity and nonlinearity. Generally, though the compositions of geochemical fields vary with elements, the pattern parameters of which present themselves analogous to each other, for examples, the places where ore deposits stand are anomalous areas of moderate contents, and don’t correspond to anomalous peaks except few ore deposits; the varied extents of semivariogram are between 0.7 to 0.9 with the characteristics of random fields; the static pattern entropies in the orientation from south to north are less than that from east to west, and Brown Fractal Dimensions are just inverse, that indicate the variations from south to north are more complicated; almost all ore deposits locate in the zones where the singular indexes are less than 2.0, especially that of lead, zinc, gold, mercury, and antimony are generally less than 1.8, and that proved the singular index is effecvtive to contour metallogenic areas of different kinds of mineral resources.The Lyapunov indexes of geochemical fields of part of metallic deposits showed that, the regionally geochemical fields of Pb and Zn are characterized by their criticalities, that of soluble elements as Cu and Mo tended to be stabilized patterns, and man-made pollutions made geochemical fields of Hg and Sb have the characteristics of chaos.5.Regioinally geochemical Models for metallogenic prognosisAbout effective estimation of modeling methods showed that linear regression is quite effective, with capability of discriminating of different size ore deposits, the secondary is logical information method, the third is reconstruction of factor model method, and the Evident Weight method gave a reasonable metallogenic assemblage but gave a bad verified result. Finally, 14 regionally geochemical models for prospecting were found by the method of linear regression, they are that of sedimentary iron deposits, sedimentary and metamorphosed iron deposits, weathering and leaching iron deposits, sedimentary and reconstructed manganese deposits, skarn copper deposits, porphyry copper deposits, hydrothermal copper deposits, VMS copper deposits, sedimentary lead-zinc deposits, reconstructed lead-zinc deposits, magmatic hydrothom type of gold deposits, sedimentary and reconstructed gold deposits, mercury deposits, and antimony deposits.6. Large scale of geochemical models and the problems of renormalization for prospecting6.1 Primary halos of Daijiazhuang lead-zinc ore depositThe zoning formed in sedimentary mineralization is, from centre to outside, Fe-Au-Bi-Sr-W-Cr-Pb-Hg-Co-Sb-Ni-V-Mo, respectively that means from hydrothermal sediments to normal sediments under reduction.The zoning formed in reconstructed mineralization is, from centre to outside, Cu-Zn-Mo-Pb-Sn-W-Hg-Ni-Co, respectively that means from multi-metallic elements to hydrothermal construction composition.Lyapunov indexes showed that, Hg from meso-low temperature mineralization has self-organized criticality in both time and space, and meso-high temperature composition as Cu, Zn, and Bi have self-organized criticality while behave stabilized geochemical pattern.With the combined index [PB*W]/Cu², and its fitted power function, deep resources prediction model, which has a high proportion of variance and a high fitted level, was acquired.6.2 Pedogeochemistrical halos of Daijiazhuang lead-zinc depositThe zoning calculated by zoning index method is, from centre to outside, Sn-Cu-W-Mo-Ag-Zn-Pb-As-Sb, which is consistent with hydrothermal deposits.Lyapunov index showed that, the processes of soil-forming made geochemical fields of most of metallogenic elements stabilized, but the power spectrum of elements in soils inherited to that in rocks.A mathematic prediction model which is varying with the area of Ag anomalies, was set up, and ideally verified.6.3 Geochemical halos of stream sediments in the scale of 1:50000Lyapunov indexes, and 1/f phenomina in frequent domain indicated that, fluviation in the surface would make some elements with stabilized pattern in primary halos tend to be ctritical or of chaos, bring about anomalies irrespective to mineralization, and complex stream sedimentary anomalies for prospecting. Metallogenic elements and their indicator elements present excursion to 1/f phenomena in the low frequency, individual element as Cu behaves out-of order in frequent domain, all these show us its complicated genesis and unreliable of applying its data to resources evaluation.The combined anomalous map of multi-elements showed a zoning centered on Pb, and from centre to outside is Pb-Cu-Zn-Mo-As-Hg-Ag. The Pb anomalies presents a ringed zoning model with centering on Daijiazhuang lead-zinc ore deposit and being vertical to the trend of strata in NEE orientation, that imply these ringed anomalies were derived from reconstructed mineralization.On the states of geochemistry and self-organized criticalities of metallogenic elements and their indicator elements under the surface, selecting areas of Pb, Zn, As, Sb, and Hg as variables, which are affinitive to mineralization and more stable, prediction model for prospecing was set up, and well verified.6.4 The problems of renormalization in mineral explorationBy research of the problems of renormalization in mineral exploration, we thought that, in the 3 explorative scales of 1/200000, 1/50000, and 1/10000, the explorative engineering should be extended respectively to about 6.5Km, 0.16Km, and 0.002Km. While the frequency of anomalous data is less than 10%, which has few influences on correlative length, and it is the scale that play a decive role to correlative lengths.更多还原