关于金矿矿物质来源的初步探讨

近年来“矿源层”这一概念被广大地质学家所接受，他们认为矿床中的金是从夺中萃取的，本文认为矿床中金来源于岩浆残余热液。在地壳深部，当丰度值高的基性央域 其他岩石，在深熔作用下产生花岗质岩浆时，同时带出许多金，当岩浆侵入到上部地壳冷凝结晶时，其中的大部金进入残余热液，量后富集成矿。     

贵州镇远地区铅锌矿同位素地球化学特征及矿床成因

通过对镇远地区金堡、都坪、小溪铅锌矿床开展碳、氧、硫同位素地球化学特征研究.结果显示：都坪和小溪矿床成矿物质来自于海相蒸发岩或沉积地层,金堡矿床成矿物质很有可能来自于地壳深部的岩浆源.结合区域构造及矿床特征分析,可以认为镇远地区铅锌矿床可分为与海相沉积地层及深部岩浆作用有关的两种成因类型的矿床.     

矿床及其组合是地壳演化的标志物──右江幔隆的发生、发展与滇黔桂卡林型金矿关系探讨

现代金成矿地球动力学的研究，揭示了矿床及其组合与构造变动、岩浆活动一样，是地壳变革的一个事件，因此从成矿环境地质方面可反演矿床及其组合的形成史，正确划分出与区域地壳演化阶段相适应的矿化类型；滇黔桂卡林型金矿的形成与右江幔隆的发生、发展息息相关，本文借用金成矿地球动力学的一些思想，用地幔隆起的观点分析了本区卡林型金矿的形成。     

矿床及其组合是地壳演化的标志物

现代金成矿地球动力学的研究，揭示了矿床及其组合与构造变动，岩浆活动一样，是地壳变革的一个事件，因此从成矿环境地质方面可反演矿床及其组合的形成史、正确划分出与区域地壳演化阶段相适应的矿化类型；滇黔桂卡林型金矿的形成与右江幔隆的发生，发展息息相关，本文借用金成矿地球动力学的一些思想，用地幔隆起的观点分析了本区卡林型金矿的形成。     

新疆穷布拉克铜矿床成矿模式

穷布拉克铜矿床地质研究表明，该矿床为火山热液、次火山热液和沉积－改造作用成矿。认为岩浆和成矿物质来源于深部地壳，成矿与火山—次火山作用密切相关，是同一岩浆源分异演化不同阶段的产物，矿床成因属中低温火山—次火山热液型和沉积—改造型矿床，并建立了矿床成矿模式     

Thermal doming-extension metallogenic system of Jiaodong type gold depositsSCIEI北大核心CSCD

胶东型金矿具有独特的成矿特征和成因机制,不同于国际已知金矿类型。为了深化认识控制矿床形成、变化和保存的地质要素及成矿过程,本文综合分析了胶东半岛晚中生代岩浆作用、构造活动和成矿特征及其构造背景,提出该区深部岩浆活动与地壳快速隆升及浅部变质核杂岩、张性断层、断陷盆地等伸展构造,共同控制了以Au为主的矿床成矿系列及成矿演化过程,谓之热隆-伸展成矿系统。阐明了晚中生代岩浆演化过程中的元素变化规律,发现了金矿化蚀变带中的低Ba、Sr含量异常及早白垩世胶东地壳中金丰度的显著变化,揭示了壳幔物质混合和伟德山型花岗岩岩浆活动对金成矿的贡献。认为这一成矿系统形成于古太平洋板块俯冲后撤的后俯冲伸展环境,由于软流圈上涌导致岩石圈地幔性质由富集向亏损转化,从而引起岩浆岩地球化学特征变化,地球化学元素重新调整,幔源含金流体与由重熔下地壳析出的壳源含金流体混合形成富金流体库,并产生贫金花岗岩。大规模岩浆活动为成矿元素的活化、迁移提供了热动力条件,上地壳伸展产生的断裂构造则为成矿元素聚集提供了良好空间。热隆-伸展成矿系统是中国东部晚中生代重要的成矿系统。     

铼－锇同位素体系对揭示矿质来源的作用

近几年以来，由于铼－锇同位素体系逐渐应用于基性－超基性岩有关的岩浆型矿床中，对这类矿床的成矿物质来源有了更为深刻的认识。许多过去被认为是由幔源物质形成的岩浆型矿床（例如Ｂｕｓｈｖｅｌｄ、Ｓｕｄｂｕｒｙ等），其实地壳物质占有相当大的比例。同时，由于铼－锇同位素体系揭示了源于地壳之放射性成因锇的存在，新的成矿观点也就应运而生。例如，一些学者用热液成矿作用来解释Ｂｕｓｈｖｅｌｄ矿床中地壳成因的锇同位素特征；陨石撞击成因被再次用来解释Ｓｕｄｂｕｒｙ的成因，因为陨石撞击能有效提供形成Ｓｕｄｂｕｒｙ复式岩体所必须的地壳物质（地壳物质所占比例大于６０％）。     

自然界酸性溶液的形成和向成矿溶液演化机理──表生循环水向成矿溶液演变机理之(二)

对成矿溶液性质的认识是矿床成因和预测矿床的理论基础。到目前为止，讨论“酸性成矿溶液成矿机理”的报导甚少。作者认为，既然火山气体冷暖水是强酸性的，地壳中的岩浆气液冷凝水必然也是强酸性的，其pH接近于零，由岩浆气液冷凝水演变成的合矿溶液及其成矿作用在地质中可能是相当普遍的现象。本文讨论了岩浆气液冷凝水向含矿溶液转变的条件和机理、含矿溶液成矿的条件和机理，以及随后溶液又向近中性卤水成分演变的规律。本文以扬子地块西南缘低温热液交代改造型矿床为例，揭示地壳中酸性含矿溶液成矿的普遍规律及地质证据。     

东秦岭地区中生代金钼多金属矿C-H-O同位素组成研究

文章在系统收集近年来东秦岭地区主要的钼、金、铅锌银矿C-H-O同位素数据分析的基础上,对区内的C-H-O同位素组成进行了综合研究。其结果认为东秦岭钼金多金属矿床的成矿流体来源极为相似,初始成矿流体均为与岩浆活动有关的高温深源流体,随着岩浆活动和成矿作用的进行,大气降水与地壳岩石水岩反应作用后的浅源流体不断加入其中,使得矿床的成矿流体表现深源流体和具有雨水性质的浅部流体的混合特征;富含成矿物质的成矿流体聚集在地壳下部的拆离带,与下部地壳岩石相互作用,形成复杂的流体-岩浆混合体系,受构造运动控制,在不同的地球物理化学边界层沉淀成矿。     

冀北地区脉金成矿作用与地台活化区富碱热流体活动

本文通过冀北金矿化集中区的地质背景，矿床地质、地球物理特征及地球化学特征的综合研究，提出了富碱热流体在古老地壳深大断裂系中活动对地台活化，岩浆作用乃至成金作用的重要意义，将产于变质岩中金矿床与岩浆岩中金矿床的成因统一起来。它们的金活化条件及成矿机制是相同的，成矿物质来源为中生代地幔与古老地壳的混合来源。     

Suppression of swelling associated with ettringite formation in lime stabilized sulphate bearing clay soils by partial substitution of lime with ground granulated blastfurnace slag (GGBS)

Ettringite related swelling in lime-stabilized sulphate bearing clay soil systems has only been reported within the last decade although similar expansive behaviour has been reported in concrete over many years. The use of ground granulated blastfurnace slag (GGBS), an industrial by-product, is well established as a binder in many cement applications where it provides enhanced durability and high resistance to sulphate attack. This paper reports on efforts to extend the use of GGBS to highway and other foundation layers by determining the beneficial effect of the suppression of swelling of lime-stabilized clay soils, particularly in the presence of gypsum. The paper describes the results of laboratory tests on lime-stabilized kaolinite containing different levels of added gypsum and on lime-stabilized gypsum (selenite) bearing Kimmeridge Clay to which, in both cases, the lime has progressively been substituted with GGBS. The tests determine the linear expansion behaviour of compacted cylinders, during moist curing in a humid environment at 30°C and during subsequent soaking in de-ionized water. The results illustrate that substitution of lime with GGBS produces significant reduction in linear expansion of lime-stabilized clay soils particularly those containing gypsum.     

川东及其周缘地区下寒武统龙王庙组沉积相

通过野外露头、钻测井、三维地震及区域地质调查等资料的综合研究发现,川东及其周缘地区下寒武统龙王庙组岩石类型以碳酸盐岩(粉晶白云岩、颗粒白云岩、泥晶灰岩和颗粒灰岩)为主,局部发育大套蒸发岩(膏岩和云质膏岩)及碳酸盐岩与碎屑岩的混合沉积;识别出局限台地相、开阔台地相、蒸发台地相和混积台地相4种沉积相类型,以局限台地相最为发育;川东及其周缘地区龙王庙组各沉积相带呈北东—南西向展布,混积台地相分布于研究区西北部,蒸发台地相集中发育在研究区西部华蓥山断裂东侧,局限台地相分布于混积台地相以东到盆地东边界以西的地区,开阔台地相分布于局限台地相以东到广海的部分地区。     

从中下三叠统膏盐特征看中下扬子早印支运动

中下扬子早-中三叠世膏盐层是对早印支运动的沉积响应,本文从膏盐的成因、中下扬子膏盐层位的差异、沉积环境的变迁、膏盐的厚度变化和产状特征、沉积中心和沉降中心的分布等方面,分析早印支运动的表现形式。中下扬子早-中三叠世依次出现陆棚台地(碳酸盐岩)、潟湖—潮坪(白云岩与膏盐)和滨海(碎屑岩),这种大规模海退,正是早印支运动表现为构造抬升的结果。抬升过程中,残留海水在炎热干燥的气候条件下蒸发形成膏盐层,而中扬子的膏盐层位比下扬子低,据此推测中扬子先于下扬子与华北板块碰撞而抬升。平面上,现今构造格局(主要由中印支—早燕山运动形成复向斜、复背斜和推覆构造)的坳陷区主要为白云岩与(硬)石膏互层或石膏夹少量白云岩或云质石膏,膏盐层厚度大,现今构造的隆坳过渡区主要为石膏假晶、含膏云岩、石膏质白云岩、白云岩夹石膏等,膏盐层厚度小,而膏盐的厚度和产状与沉积时的水深和地势直接相关;另外,地层等厚图显示膏盐层主要分布于当时的沉降中心。这些沉积特征显示膏盐沉积时的地势与现今隆坳相间的构造地貌存在一定程度的吻合,说明膏盐沉积时的地层已经发生了轻微的褶皱变形(未见角度不整合和地层缺失)。     

山西中奥陶世石膏岩的成因类型及生成环境

山西中奥陶世石膏岩的沉积受到机械沉积作用的影响。区内九种石膏岩分别是不同水深条件下的沉积及交代产物,并可归纳为浪基面下洼地、浅水、滩岛潮坪等三种沉积环境。在空间上,它们彼此依存、转换并连为一体形成一个巨大的浅水蒸发岩沉积。     

Gypsum facies transitions in basin-marginal evaporites: middle Miocene (Badenian) of west Ukraine

In the middle Miocene Badenian gypsum basin of the Carpathian Foredeep, west Ukraine, three main zones of gypsum development occur in the peripheral parts of the basin. Zone I consists entirely of stromatolitic gypsum formed in a nearshore zone. Zone II is located more basinward and is characterized by stromatolitic gypsum in the lower part of the section, overlain by a sabre gypsum unit. Zone III occurs in still more basinward areas and is characterized by giant gypsum intergrowths (or secondary nodular gypsum pseudomorphs of these) in the lowermost part, overlain by stromatolitic gypsum, sabre gypsum and then by clastic gypsum units. Correlation between these facies and zones has been achieved using lithological marker beds and surfaces. Of particular importance for correlation is a characteristic marker bed (usually 20–40 cm thick) of cryptocrystalline massive gypsum occurring in zones II and III. The marker was not distinguished in zone I, possibly because this bed is older than the entire gypsum section of that zone. These new results strongly suggest that the deposition of giant gypsum intergrowth facies and stromatolitic gypsum facies was coeval. In some sections of zones I and II, limestone intercalations have been recorded within the upper part of the gypsum sections. Considerable scatter of the δ¹⁸O and δ¹³C values of these limestones indicates variable diagenetic overprints of marine carbonates, but a marine provenance of the limestones is confirmed by microfacies analysis. Some of the limestones are coeval with an intercalation of gypsarenitic, mostly laminated gypsum occurring in the sabre gypsum unit of zones II and III. Badenian gypsum formed in extremely shallow‐water to subaerial environments on broad, very low relief areas of negligible brine depth, which could be affected by rapid transgressions. Stable isotope (δ³⁴S, δ¹⁸O) studies of the gypsum demonstrate that the sulphate was of sea‐water origin or was derived from dissolution of Miocene marine evaporites. Investigations of individual inclusions in the gypsum indicate decreased water salinity when compared with modern marine‐derived, calcium sulphate‐saturated water. Groundwater influences are indicated by high calcium sulphate contents of the brines in the evaporite basin. The chemical composition of Badenian waters was thus a mixture of relic sea water (depleted in NaCl), groundwater (enriched in calcium sulphate) and surface run‐off.     

The hydrological setting, occurrence and significance of gypsum in late Quaternary salt lakes in South Australia

Well exposed, often laminated gypsum sequences occur in many Quarternary salt lakes in southern South Australia. The gypsum in the salt lakes is classified by increasing grain size into gypsite, gypsarenite and selenite. The salt lakes are classified by age and hydrological setting into coastal salinas which are Holocene sea-water fed groundwater lakes, and continental playas which are late Pleistocene endorheic basins. A study of the relationships between coastal salina hydrology and the associated gypsum deposition has shown the different types of gypsum form under distinct hydrological regimes. As the hydrology above a coastal salina depositional surface changes through time so does the type of gypsum deposited. Application of a gypsum depositional model derived from a study of the coastal salina gypsum to those portions of a continental playa gypsum unit where deposition is no longer occurring confirms the applicability of the model to non-salina gypsum deposits.     

四川盆地下寒武统膏盐岩发育特征与封盖有效性分析

四川盆地下寒武统广泛发育一套膏盐岩,主要沉积于早寒武世龙王庙期。基于四川盆地深井及实测剖面中膏盐岩的识别和统计,发现下寒武统有川南和鄂西两大聚盐区,最厚达690.40m;川南聚盐区西部以含泥含云质石膏岩类和含膏砂泥岩类为主,东部及颚西聚盐区主要为含膏白云岩类。结合前人研究,认为膏盐岩发育于浅水缓坡沉积环境,有潮上萨布哈和缓坡蒸发两类成因。通过对川南聚盐区储盖匹配关系及后期构造与膏盐岩封盖性分析,表明下寒武统膏盐岩与盐下震旦系优质的白云岩储层在空间上具有良好的匹配关系;四川盆地边界大断裂及边界外寒武系的抬升暴露让膏盐岩在盆地外封盖性失效,而在盆地内膏盐岩的封盖性较好。威远气田解剖表明有膏盐岩分布的威远地区成藏,而无膏盐岩分布的资阳地区气藏被破坏,显示了下寒武统膏盐岩在四川盆地油气成藏中具有重要的作用。     

Sedimentology of Badenian (middle Miocene) gypsum in eastern Galicia, Podolia and Bukovina (West Ukraine)

Primary gypsum is the main evaporite mineral in the middle Miocene (Badenian) of the West Ukraine. The lower part of the gypsum sequence is built of autochthonous gypsum while the upper part is composed of allochthonous gypsum that formed following a major, tectonically induced, change in basin morphology. This change resulted in the destruction of the gypsum deposited on the margins of the basin and formation of redeposition features. Autochthonous gypsum facies were deposited in two main environments: (1) giant gypsum intergrowths precipitated from highly concentrated brines; (2) very shallow subaqueous gypsum deposited in a vast brine pan. The brine pan was characterized by a facies mosaic that reflects an interplay of concentrated brines from the central part of the evaporite basin and diluted brines due to the influx of continental meteoric waters. The facies continuum, microbial gypsum - bedded selenite - massive selenite - sabre gypsum, indicates increasing salinity of the brine with time. This type of facies pattern has been established in recent salinas that are analogous to Badenian gypsum in their lateral facies changes. However, the pattern of facies distribution with respect to the open sea in the Badenian basin is opposite to that found in recent salinas. The pattern of the Badenian gypsum facies in the Ukraine indicates that facies repetition may have been related to climatically controlled salinity changes and not to depth changes, as is commonly used to explain the repetition of sulphate facies in a vertical succession.     

Speleothems in gypsum caves and their paleoclimatological significance

This article highlights the relationship between speleothems growing inside gypsum caves and the particular climate that existed during their development. Speleothems in gypsum caves normally consist of calcium carbonate (calcite) or calcium sulphate (gypsum) and the abundance of such deposits greatly differs from zone to zone. Observations carried out over the last 20 years in gypsum caves subjected to very different climates (Italy, Spain, New Mexico, northern Russia, Cuba, Argentina) highlight wide variation in their cave deposits. In arid or semi-arid climates, the speleothems are mainly composed of gypsum, whilst in temperate, humid or tropical regions, carbonate formations are largely predominant. In polar zones no speleothems develop. These mineralogical details could be useful paleoclimatic indicators of climate change. The interpretation proposed is based on the fact that in gypsum karst the kind of speleothems deposited is determined by competition between the two principal mechanisms that cause precipitation of calcite and gypsum. These mechanisms are completely different: calcite speleothem evolution is mainly controlled by CO₂ diffusion, while gypsum deposits develop mostly due to evaporation. Therefore, the prevalence of one kind of speleothem over the other, and the relationship between the solution–precipitation processes of calcite and gypsum, may provide evidence of a specific paleoclimate. Additionally, other non-common deposits in gypsum caves like moonmilk, cave rafts and dolomite speleothems can be used as markers for the prevalence of long, dry periods in humid areas, seasonal changes in climate, or rainfall trends in some gypsum areas. Moreover, the dating of gypsum speleothems could contribute paleoclimatic data relating to dry periods when calcite speleothems are not deposited. In contrast, the dating of calcite speleothems in gypsum caves could identify former wet periods in arid zones.     

Gypsum–anhydrites in 1.9 Ga Vempalle Formation,Cuddapah basin,India: A note on the Palaeoproterozoic environment and diagenetic condition

The Cuddapah basin consists of generally well-preserved Palaeoproterozoic–Neoproterozoic sedimentary and associated volcanic rocks. The detailed lithological studies of sedimentary rocks of Vempalle Formation from the narrow linear belt of 15 km, in the southern margin, show the occurrence of layered gypsum in the cherty dolostone–shale intercalated facies, red shale and phosphatic dolostone facies of the Vempalle Formation. The petromineralogical studies reveal that gypsum is in close association with anhydrites. Microscopically, three different types of gypsum and anhydrite are identified, viz., lath-shaped, equant-shaped and anhedral-shaped grains. The equant variety corresponds to a granular gypsum, whereas the anhedral grains of gypsum exist as the granular and fibrous variety as seen in the hand specimen. The presence of gypsum/anhydrite has been confirmed by the petromineralogical, X-ray diffraction and chemical analytical data. The phosphatic dolostone is the host rock for stratabound type of uranium deposit at Tummalapalle, Cuddapah district, Andhra Pradesh, which is one of the most unique types of uranium mineralisation in the world. Abundant pseudomorphs of gypsum and anhydrite relicts and discontinuous gypsum layers within these dolostones, nodules of chert and gypsum indicate the interrelationship between the diagenesis and genesis of uranium mineralisation which indicates the carbonate precipitation in the sulphate-rich hypersaline environments.