基于航空高光谱遥感的沉积变质型铁矿找矿预测—以北祁连镜铁山地区为例

沉积变质型铁矿是北祁连山西段重要的矿床类型,一直以来都是该地区矿产勘查的重要对象,区内产有知名的镜铁山铁矿床。由于北祁连山地区山势陡峻、交通不便,地质工作程度相对较低,开展传统的地质调查工作难度较大。航空高光谱遥感具有高空间分辨率和高光谱分辨率特点,其在矿物信息识别上较多光谱遥感有了质的提升,同时在该地区开展航空高光谱遥感调查是发挥遥感技术的高效性和先行性优势所在。本文基于调查区内沉积变质型铁矿床地质特征,利用航空高光谱遥感数据提取的赤铁矿、菱铁矿信息开展针对沉积变质型铁矿找矿预测。结果表明,提取的赤铁矿信息或直接指示铁（化）体产出位置,或指示含赤铁矿地层产出信息,这为直接或间接寻找铁矿床提供了重要信息;菱铁矿信息同样可作为寻找铁矿床的重要依据,分布范围较大的菱铁矿信息可直接指示富菱铁矿的铁（化）体产出位置。     

蒙库铁矿床与镜铁山铁矿床的对比研究

蒙库铁矿床被认为是与海底喷流沉积作用有关的铁矿床,但存在很大的争议.文章将其与典型的喷流沉积型铁矿--镜铁山铁矿床对比,并结合野外的第一手资料,发现蒙库铁矿床的喷流沉积特征并不明显,而热液成矿作用比较明显,但是热液的性质和来源、成矿时间等尚不明了,蒙库铁矿的成因机理仍有待深入研究.     

塔什库尔干地区赞坎铁矿矿物学特征与成因

赞坎铁矿石西昆仑成矿带近年来新发现的一处超大型铁矿床,矿区内广泛出露古元古代布伦阔勒变质岩层,矿体主要赋存于布伦阔勒岩群角闪斜长片岩和黑云石英片岩内部,部分产于霏细岩与黑云石英片岩接触带内。矿床由Ⅰ~Ⅶ号矿体组成,其中Ⅰ号和Ⅲ号矿体为主要矿体。根据矿石组构、矿物共生关系等特征,成矿过程可划分为早期沉积期、中期变质期及晚期岩浆热液期3个成矿期,其中,岩浆热液期可进一步划分为矽卡岩阶段、热液改造阶段和硫化物阶段。早期沉积期磁铁矿呈微细粒他形晶结构,被变质期石英颗粒包裹,以较低含量的TFeO、MgO、MnO和较高含量的TiO2、Al2O3为特征;中期变质期磁铁矿分布于条带状矿石内,他形晶粒状结构,与早期相比,TFeO、MgO、MnO等含量相对升高而TiO2、Al2O3等含量相对降低;晚期岩浆热液期矽卡岩阶段磁铁矿分布于块状矿石内,自形晶粒状结构,以相对富TFeO、MgO、MnO而贫TiO2、Al2O3为特征;晚期热液改造阶段磁铁矿分布于浸染状矿石中,半自形-自形粒状结构、交代残余结构为主,TFeO、Al2O3、TiO2、MnO等含量变化较大。认为赞坎铁矿是沉积变质型铁矿床,遭受后期岩浆热液作用交代改造。     

甘肃镜铁山矿床构造新认识

甘肃镜铁山铁矿是我国西北地区重要的钢铁基地,目前保有铁矿石4亿吨,因同时具有中等规模铜矿床而倍受关注.原矿山勘探资料认为镜铁山矿床是向斜构造,铁矿体受向斜控制,下部已无矿,基于该认识,自20世纪90年代至今,除一些生产性勘探外,深部及外围找矿基本停滞,并有Ⅲ,Ⅳ矿体,Ⅵ,Ⅶ矿体先后闭坑.笔者最近在此工作期间,依据桦树沟矿区开采现状,黑沟矿区控矿特点以及节理与千枚理关系,推测镜铁山矿并不是向斜,以黑沟矿区为代表,可能主要为断层控矿,深部和外围找矿潜力巨大.     

从磁铁矿的标型特征论天湖铁矿的成因

本文通过对天湖铁矿磁铁矿的标型特征(化学成分、晶格常数、反射率、氧同位素)研究后认为天湖铁矿为沉积变质成因,该矿床的磁铁矿在每个矿体及各个矿层内的特征基本一致,反映成因类似,而且其磁铁矿的标型特征既不同于岩浆矿床也不同于接触交代矿床和热液交代矿床,而与火山沉积矿床和变质矿床相近。     

甘肃北祁连西段镜铁山铁矿外围勘查实践——以卡瓦铁矿富集区找矿突破为例

张新虎等人在区域成矿地质背景研究过程中,通过对比研究甘肃北祁连西段镜铁山铁矿外围成矿条件和物化探异常特征,认为祁连山西段具有形成沉积变质型铁矿的地质条件,镜铁山铁矿外围是最有利找矿靶区,建议在其东延带部署"丰乐河—西插山地区1∶5万矿产远景调查"。通过该项目实施,进一步理清了"镜铁山式"铁矿含矿岩系空间展布,先后发现了卡瓦铁矿、沙梁铁矿、光滑岭铁矿等一批铁矿点,实现了铁矿勘查新突破,成为甘肃北祁连西段找矿战略突破行动典型实例。通过前期勘查,目前已获铁矿石资源量达5亿吨。本文从区域成矿背景、含矿层位对比、勘查找矿成果及工作部署思路等方面进行初步总结,对该区铁矿勘查规划和找矿部署具有指导意义。     

沉积变质-热液交代型稀土、铁矿床的成因特征

我们研究了一种特殊类型的稀土和铁的矿床,它是由于沉积变质作用以及后期来自岩浆的热液交代作用的迭加而形成的。     

冀东杏山沉积变质型铁矿床富铁矿成因探讨

本文在野外勘查和岩(矿)相学基础上,对杏山铁矿块状富矿和条带状普通矿石进行主量元素、微量元素和稀土元素等系统研究。杏山铁矿石主要由磁铁矿和石英组成,其中块状富铁矿石相较于条带状普通矿石含有较多的镁铁质矿物,另外块状富矿(XS-60)手标本可见绿泥石化,但镜下蚀变程度较弱,其富矿成因与后期热液蚀变相关度不高;条带状贫矿(XS-10)遭受较强的后期热液蚀变,有一定程度的铁质富集,但仅限于富铁条带,富硅条带未蚀变。矿石中低Al2O3+Na2O含量和Zr、Sc、Th、Hf等含量特征表明杏山铁矿在沉积过程中很少有陆源碎屑加入。微量元素和稀土元素配分模式表明条带状普通矿石和块状富铁矿有共同的成矿物质来源,富铁矿和贫矿都是在缺氧环境下,通过海底热液与海水混合后同沉积形成的,而后期褶皱变形作用使贫矿层加厚的同时,也使富铁层加厚。     

镜铁山桦树沟铜矿床地质特征,成因及形成机制探讨

介绍了镜铁山式铜矿床的地质特征,分析了其成因,并对其形成过程进行理论推导。认为该矿床为火山作用有关的中－低温热液改造层控矿床。     

海南省后万岭铅锌矿床控矿因素、矿床成因及成矿模式探讨

后万岭铅锌矿床是近年来海南省找矿的一项重要进展,探明的铅锌金属量大于29万吨(Pb 4.4万吨,Zn 24.6万吨),平均品位为锌2.23%、铅0.95%。该矿床产于千家超单元岩体内,后者是中-晚侏罗世在后造山期地壳大面积伸展减薄的构造背景下,由壳-幔混源岩浆间歇性多期侵入的产物。千家岩体各单元花岗岩属于壳-幔混合型的高钾钙碱性岩石或钾玄岩,具有明显的成分及结构演化的连续性。其稀土元素总量较高,但变化范围较大〔ΣREE=(122.61～410.58)×10^-6〕,具有显著至中等的负铕异常(δEu=0.13～0.69),其稀土元素配分曲线呈右倾型(LREE/HREE=6.74～16.32),并强烈亏损Ba、Nb、Ta、Sr、P、Ti,相对富集Rb、K、Pb等。千家岩体花岗质岩浆演化过程中存在大量的热液流体,同时,其造岩矿物中Pb、Zn的含量远高于地壳丰度值,深部热能及浅部放射性生热元素的高含量促使浅部热液对流循环,在较长时间内不断萃取成矿物质,有利于在断裂带内富集成矿。后万岭铅锌矿床严格受到千家岩体及发育于其内的NNW向-近SN向扭张性断裂的控制,矿体以充填、交代的方式就位于NNW向-近SN向扭张性断裂带内及附近。矿相学分析和矿区地质资料揭示出该矿床至少经历了4期热液成矿作用:① 成矿早期,为粗粒黄铁矿形成阶段;② 成矿中期,是闪锌矿主要成矿阶段;③ 成矿中-后期,是黄铜矿主要形成阶段;④ 成矿后期,是方铅矿主要成矿阶段,其成矿热液可能受到斑岩岩浆的控制。矿区内的NNW向-近SN向断裂活动过程对应了后万岭铅锌矿的成矿过程,成矿早期与成矿中期归入左旋张扭性断裂活动阶段,成矿中-后期和成矿后期归入右旋压扭性断裂活动阶段。据此笔者认为,后万岭铅锌矿属于燕山晚期后造山环境下严格受NNW向-近SN向扭张性断裂约束的热液脉型矿床,就位于千家岩体斑岩成矿系统的顶端或远端,最终归纳总结出了后万岭铅锌矿床成矿模式图。     

再论蛇屋山红土型金矿的成因

蛇屋山金矿是我国第一个大型红土型金矿床。它具有规模大、品位低、易采、易选、经济效益好等特点,是黄金矿业中建设大型露采堆浸场的理想基地。这个矿床的成矿物质来自奥陶系碳酸盐岩硅化破碎带,成矿活动以第四纪化学风化作用为主。在中更新世热带雨林条件下,在岩石的红土化过程中,金从原岩中析出,与风化产生的铁质水溶液一起,沿着红土裂隙向下渗透,停积于地下潜水面,形成似层状矿体。     

广西河池市北香银-锌多金属矿床地质特征及成因探讨

北香是丹池成矿带上的一个重要构造隆起区,成矿条件良好,但是近四十年的地质勘查未能实现找矿的重大突破。通过对矿区成矿特征及控矿条件的分析,认为矿床明显受NW向同生沉积断层的控制,具有喷流沉积和后期热液叠加改造的两期成矿特征。目前发现的矿体仅是矿床上部脉状矿,其下部的下泥盆统中应存在层状似、层状的厚大矿体。     

祁连山白银厂黄铁矿型矿床成因探讨

The Baiyinchang mining area, an important industrial base of base metals in China, consists of five pyrite type deposits of different sizes, four of which have already been worked. These five deposits might be grouped into two types: Cu-bearing (predominatingly Cu) pyrite type deposits, such as Zheyaoshan, Huoyanshan and Tongchanggou, and polymetallic pyrite deposits containing principally Cu, Pb and Zn, such as Xiaotieshan and Sigejuan. These two types of deposits occur close to each other in the same formation-Baiyinchang spilite-keratophyre sequence and have similar structures and petrofacies, suggesting the possibility of forming two different types of deposits in the same tectonic unit and volcanic rock series. The deposit lies in the eastern part of the volcanic complex within the Qilian eugeosyncline, its genesis remains a problem of much controversy. Ln recent years, the author has made an integrated study and analysis of the data accumulated over the past thirty years and also performed some field investigation to check up these references. The results acquired have led him to postulate the hypothesis that the deposit was formed by the concentration of volcanic hydrothermal fluids in depression and the activity of subvolcano-magmatic fluids. The formation of the massive pyrite in the main ore body of Zheyaoshan is believed to be the result of the lateral effusion from the Qingshanbao vent of the third subcycle appearing presently as silicic rock formation, i.e., the result of the accumulation in the second subcycle crater depression of the ore material effused from the pyrrhotite ore chimney. This might be borne out by the existence of abundant massive copper-bearing pynhotite ore with well-developed textures of corrosion and replacement in the chimney as well as by the ring-like distribution of the metallic minerals around the chimney caused by the spread of the fluids from this center. Geological mapping and analyses of the data of drill core and petrofacies support the claim that the ore body is located at the crater depression. Minerals in massive pyrite ore body are coarse in the west and fine in the east, suggesting also the migration of ore fluids from east to west into the center of depression. The massive ore body cutting obliquely the strata, the relatively weak alteration of country rocks and the remarkable variation in copper content of the ore body all seem to have resulted from the ascending movement of the copper-bearing ore fluids brought by subvolcanic activity along the ore chimney and its fracture zone formed during the crustal reversion. The Xiaotieshan polymetallic pyrite deposit is of subvolcano-magmatic fluids type. Its ore-forming processes were strictly controlled by late subvolcanic activity which, in turn, was governed by fracturing. The ore body overlies the hanging wall of quartz albitophyre and shows close relationships with subvolcanic rocks in dimension and grade while the texture and structure of ore and the mineral constituents vary in accordance with the diverse country rocks. The examination of the structure of volcanos, fractures, variation in petrofacies, regularity of subvolcanic activity, the extent of wall rock alteration and characteristics of mineralization, therefore, makes up the prerequisite for the search of such concealed ore deposits. The Jinfangou ore belt expends along a EW striking fracture zone characterized by complex lithological characters and petrofacies as well as by frequent subvolcanic activities. Mineralization and ore bodies are exclusively confined to the fracture zone. The repeated crustal reversion during: the late stage of the development of rock formation resulted in the folding and faulting of the strata, thus facilitating the differentiation and migration of the magma. The intrusion of the subvolcanic magma not only brought sufficient ore-bearing fluids for mineralization, but supplied heat for their migration. This is due to the fact that heat: accelerated the circulation of the ore fluids, which dissolved ore elements dispersed in the volcanic rock and unceasingly infiltrated into and replaced the country rocks as well. As a result ore fluids concentrated to form ore deposits at places with favorable structure and country rock conditions.     

祁连山白银厂黄铁矿型矿床成因探讨

白银厂黄铁矿型矿区,共有五个矿床,已相继开采四个。其中有以铜为主的含铜黄铁矿型矿床,如折腰山、火焰山、铜厂沟;有以铜-铅-锌为主的多金属黄铁矿型矿床,如小铁山。这两种类型矿床均赋存在白银厂细碧-角斑岩内,且矿体相距很近,构造、岩相相似。说明在同一构造单元、同一火山岩系内可以生成两种不同类型的矿床。该区矿床位于北祁连加里东地槽东部火山岩系内,对其成因一直有争议。有人认为矿床     

逊克县东安金矿矿床成因及找矿标志

通过对黑龙江省逊克县东安金矿床区域地质特征和矿床地质特征的分析,阐述了矿化与蚀变的分带性和成矿元素的富集规律.明确了成矿地质背景,研究了矿床成因,得出了找矿标志.确定了该矿床成因类型为浅成次火山热液石英脉型金矿床.