On the geographical association of strata-bound ore deposits with evaporites

Upwelling leads on the one hand to an enrichment of trace metals in marine sediments, on the other hand to a lack of precipitations in the coastal area. This explains the geographical association between strata-bound ore deposits and evaporites.

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Zusammenfassung Kaltes Auftriebswasser führt einerseits zu einer Anreicherung von Spurenmetallen in marinen Sedimenten, andererseits zu Trockenheit im Küstenbereich. In dieser Weise wird die geographische Assoziation von horizontbeständigen Erzen mit Evaporiten verständlich.

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Presented at the St. Andrews meeting of the International Association on the Genesis of Ore deposits, September 1967.     

Thallium in Low Temperature Ore Deposits,China

is paper deals with thallium in typical low-temperature deposits of Au,Tl,As,Sb and Hg in South China with respect to its mode of occurrence,minerals and geochemical correlations with many other coexisting major and trace elements,Criteria are proposed for identifying independent thallium deposits and thallium-bearing deposits and the Nanhnu realgar deposit is classified for the first time as an independent thallium deposit,Tl,F.Cl.I and B are suggested as indicators for low-temperature mineralization with examples furnished for their applications.     

界面矿床与峨眉山玄武岩

文章称发育在下二叠统茅口灰岩与覆盖其上的上二叠统峨眉山玄武岩之间界面上的众多矿床为界面矿床,并列出了各类代表性界面矿床的地质特征.从这些地质特征可以看出:界面是成矿的有利空间.富含成矿物质的峨眉山玄武岩的多期次喷发以及喷发-成岩-风化-喷发的多旋回机制使成矿物质得以逐渐富集而成矿,形成了一个以玄武岩为中心的Cu-Ag-Sb-S-Fe-Mo的成矿序列.     

Proximal and distal stratabound ore deposits

Stratiform ore deposits associated with calc-alkaline and tholeiitic volcanism form as chemically precipitated sediments and, like other sediments, display facies variations. An attempt to characterise these vertical and lateral facies variations and to relate them to distance in time and space from the volcanic centre is presented here. With increasing distance in time and space from a volcanic centre, the proportions of volcanics to sediments and intensity of hydrothermal alteration decrease. Footwall alteration pipes, stringer and disseminated ore zones dominated by quartz-, sericite- and Mg-rich assemblages are spatially associated with proximal stratiform base metal deposits whereas slight alteration to quartz-, sericite- and Fe(Mn)-bearing assemblages are present associated with distal stratiform base metal deposits. With increasing distance in time and space from the volcanic centre the Fe, Cu and S content of base metal deposits decreases and the Zn, Pb, Ag, Mn, Ba and F content increases. The trend from copper-dominated to zinc-lead-dominated iron sulphide ores is probably a result of the increasing mixing of seawater with metal-bearing hydrothermal fluid with increasing distance from the volcanic centre.     

姻袭成矿与特大型矿床

姻袭成矿与特大型矿床ＡｆｉｌｉａｔｉｏｎａｌＭｅｔａｌｏｇｅｎｙａｎｄＧｉａｎｔＯｒｅＤｅｐｏｓｉｔｓ裴荣富（中国地质科学院矿床地质研究所，北京）烟袭成矿或称亲缘成矿。这一成矿概念早在中世纪（１６世纪中期以前）的矿石成因猜想年代就已萌芽［１］。例如当...     

西藏多龙矿集区典型矿床(点)矿化特征与成矿作用对比研究

西藏多龙矿集区是近年来中国新发现的具有世界级潜力的铜金矿集区。该矿集区现已查明多不杂、波龙、拿若和铁格隆南4个大型-超大型矿床,并新发现地堡那木岗和拿顿矿点。文章对上述矿床(点)脉体、蚀变、矿化和流体特征开展了系统研究和对比。结果表明,多不杂、波龙和拿若矿床矿化类型以斑岩型为主,同时钾硅酸盐化、绢英岩化、青磐岩化等蚀变广泛发育,而铁格隆南矿床除上述蚀变类型外,还叠加有高级泥化蚀变,并发育与之相关的浅成低温热液型矿化。根据脉体特征对比和流体包裹体温压计算推测,上述4个矿床矿化类型的差异可能由剥蚀深度的差异所引起(前三者剥蚀深度约为2～3 km,后者约为1～1.5 km)。此外,地堡那木岗矿点蚀变类型以绢英岩化、泥化为主,该矿点发育与斑岩型金矿中类似的深色条带状石英脉,指示该地区可能存在斑岩型金矿。拿顿矿点为典型的高硫型浅成低温热液型矿化,铜金矿体赋存于角砾岩筒中。野外地质调查表明,上述矿点地表蚀变岩盖(Lithocaps)发育,并且蚀变岩盖空间分布位置与下伏铜金矿体表现出良好的匹配关系,可有效地指导找矿勘查工作。流体包裹体实验进一步表明,铜金元素在斑岩型矿化中的沉淀可能与温度降低和氧逸度的变化有关,而在浅成低温热液型矿化中的沉淀则受控于温度的降低和流体的不混溶作用。最后,在前人年代学研究基础上,结合本次实验结果构建了该地区与成矿作用有关的时空演化模型。     

Formation Conditions and ore potential of black shales of the Udokan Group,East Siberia

Peculiarities of formation and ore potential of black shales of the Paleoproterozoic Udokan Group are considered. They are compared to the stratotype (Khokholma Formation, Sukhoi Log gold deposit). The black shales are confined to lower parts of the Paleoproterozoic sequence of the Udokan Group. They are observed in sections of the Chitkanda, Inyr, Ayan, and Ikab’ya formations. The black shale complex of the Udokan Group is divided into three levels of Au concentration. The first level with background Au contents is typical of barren shales; the second level is confined to sulfidized rocks; and the third level is related to sulfide-quartz veins in the black shales. The average Au content is 0.12 g/t in the sulfidized shales and 0.28 g/t in the sulfide-quartz veins. Black shales of the Udokan Group and Khokholma Formation were formed in a relatively deep shelf zone, while those of the Shaman Formation precipitated in a shallow zone. Protoliths of black shales of the Udokan Group contained graywackes, diorites, syenites, basic rocks, and tuffites. Protoliths of black shales of the Khokholma Formation were produced by the intense weathering of basic and ultrabasic rocks.     

重庆武隆-南川地区铝土矿地质特征及找矿方向浅析

重庆武隆-南川地区铝土矿资源丰富。其主要含矿层位为下二叠统梁山组,通过对重庆地区已有铝土矿地质资料的分析,笔者总结了该地区铝土矿产出的地质特征,为今后铝土矿的找矿工作提供了重要依据。     

Geology and ore genesis of the manganese ore deposits of the Postmasburg manganese-field,South Africa

The Postmasburg Mn/Fe-ores occur exclusively in dolomitic Precambrian sinkhole structures with siliceous breccias and shales as hostrocks. The main manganese minerals are braunite and bixbyite, apart from secondary alteration products of the psilomelane-manganomelane family. Various generations of ore minerals could be identified. The ore mineralization is subdivided into three different genetic types. They are classified either as pure karst deposits or as combined formations of karst origin and shallow marine sedimentation due to the transgression of the Banded Iron Formation (BIF) sea. Post-sedimentary metamorphism is identified as very low grade. The development of the different ore types is illustrated schematically.     

Gold-quartz ore deposits of Yana-Kolyma belt

Types of ore deposits, their regional distribution, mineral associations, textures and structures are described. Ores are of Cretaceous age, posterior to batholithic granite intrusions (Jurassic). Mineralizing solutions originated in consequence of metamorphism and dehydration of sedimentary geosynclinal rock masses, and are not directly related to granitoids. Ore matter was transferred by hypogene solutions in colloidal state, and vein bodies necessarily passed through the state of water-saturated gel. --B. V. Brajnikov.