滇中郝家河砂岩型铜矿床成岩期和改造期热液蚀变作用——来自组分迁移计算的证据

通过牟定郝家河砂岩型铜矿床两类典型矿化的围岩蚀变类型、空间分布、蚀变矿物组合特征的综合分析,识别出该矿床存在成岩期与改造期两期热液蚀变。成岩期热液蚀变分布于浅紫交互带浅色砂岩一侧,呈现大范围面状硅化、碳酸盐化、黄铁矿化,并具蚀变分带:全浅色砂岩中的强硅化、黄铁矿化亚带;浅紫过渡砂岩中的强碳酸盐化、绢云母化、绿泥石化、弱硅化亚带,并具辉铜矿-斑铜矿-黄铜矿-黄铁矿的金属矿物分带。改造期热液蚀变主要分布于断裂、节理旁侧,表现为带状、网脉状的硅化、碳酸盐化。以1580 m中段实测剖面为研究对象,采集各蚀变亚带的代表样品,以紫色砂岩为原岩,进行主量元素、微量元素及稀土元素的组分迁入、迁出计算,结果显示各亚带组分的迁入、迁出特征与镜下观察的蚀变矿物组合吻合。分析表明,蚀变矿物组合与组分迁移特征还间接指示了不同亚带的形成条件:成岩期紫色砂岩(围岩)呈氧化-碱性条件,浅色砂岩呈还原-酸性条件,浅紫过渡矿化带则处于氧化还原-酸碱转化面上;改造期构造热液属还原-中偏碱性的中温构造流体。在此基础上,探讨了两期成矿流体分别形成层状矿体及脉状富矿体的机理,为深化研究该类矿床的"矿源-构造-流体耦合成矿"机制提供了重要证据。     

Surficial deposits on salt diapirs (Zagros Mountains and Persian Gulf Platform, Iran): Characterization, evolution, erosion and the influence on landscape morphology

The surfaces of salt diapirs in the Zagros Mountains are mostly covered by surficial deposits, which significantly affect erosion rates, salt karst evolution, land use and the density of the vegetation cover. Eleven salt diapirs were selected for the study of surficial deposits in order to cover variability in the geology, morphology and climate in a majority of the diapirs in the Zagros Mountains and Persian Gulf Platform. The chemical and mineralogical compositions of 80 selected samples were studied mainly by X-ray powder diffraction and X-ray fluorescence. Changes in salinity along selected vertical profiles were studied together with the halite and gypsum distribution. The subaerial residuum formed from minerals and rock detritus released from the dissolved rock salt is by far the most abundant material on the diapirs. Fluvial sediments derived from this type of residuum are the second most common deposits found, while submarine residuum and marine sediments have only local importance. The mineralogical/chemical composition of surficial deposits varies amongst the three end members: evaporite minerals (gypsum/anhydrite and minor halite), carbonates (dolomite and calcite) and silicates-oxides (mainly quartz, phyllosilicates, and hematite). Based on infiltration tests on different types of surficial deposits, most of the rainwater will infiltrate, while overland flow predominates on rock salt exposures. Recharge concentration and thick accumulations of fine sediment support relatively rich vegetation cover in some places and even enable local agricultural activity. The source material, diapir relief, climatic conditions and vegetation cover were found to be the main factors affecting the development and erosion of surficial deposits. A difference was found in residuum type and landscape morphology between the relatively humid NW part of the studied area and the arid Persian Gulf coast: In the NW, the medium and thick residuum seems to be stable under current climatic conditions. Large sinkholes and blind valleys with sinking streams are common. On other diapirs, the original thick residuum is undergoing erosion and the new morphology is currently represented by salt exposures and badland-like landscapes or by fields of small sinkholes developed in the thin residuum. Models for evolution of the subaerial residuum and the diapir landscape/morphology are described in this paper. While the thick residuum with vegetation has very low erosion rates, the salt exposures and thin residuum are eroded rapidly. During wet periods (e.g. early Holocene), the diapirs rose and salt glaciers expanded as the influx of salt mass was much faster compared to erosion. After the onset of an arid climate, c. 6 ka BP, the rising of the some diapir surfaces decreased or even reversed due to acceleration of erosion thanks to vegetation degradation and changes in the residuum type and thickness.     

界牌岭锡矿床地质、地球化学特征及成因类型

为了深入研究界牌岭锡矿床的成因类型，系统研究了该矿床成矿母岩的产出形式、成岩年龄、岩石化学成分及微量元素含量、副矿物成分、稀土元素含量等特征；同时，着重研究了该矿床锡一钨矿化与蚀变的类型、化学成分及相互间的共生一分带特征；并且研究了该矿床流体包裹体的主要特征。研究认为，界牌岭锡矿床成矿物质来自壳源型岩浆花岗岩类，其成矿母岩是浅成一超浅成侵位的，因而又具有斑岩型矿床的特征，其成因类型应属于斑岩一云英岩型锡矿床。     

黔西南泥堡金矿床容矿火山岩系中“粉砂岩”夹层的岩石类型归属研究

原先认为泥堡金矿床容矿火山岩系中间的"粉砂岩夹层",研究发现其具有与火山碎屑岩的成分与结构构造特征,包括熔蚀石英晶屑和长石板状晶假象,局部还出现大量生物化石碎片,应归属为蚀变凝灰岩。火山岩系的原"粉砂岩夹层"并不存在,只是短暂的火山喷发间隙,整个容矿火山岩系形成从偏基性火山碎屑岩到中基性火山角砾岩的晚二叠世火山喷发旋回。火山岩旋回的早期到晚期,金矿成矿作用强度逐渐增强,印证金成矿作用与火山岩的密切成因联系。     

河北省崇礼县水晶屯金矿床成因矿物学标志在找矿评价中的应用

本文首次应用自然金、黄铁矿、石英、钾长石等矿物的成因矿物学标志，对水晶屯金矿床的含金性、矿体的剥蚀程度和延伸范围进行了初步的定量评价，为今后在矿床深部及外围的找矿工作提供了一种简便有效的成矿预测方法。     

西昆仑-喀喇昆仑造山带锂矿成矿特征与成矿规律初探

西昆仑- 喀喇昆仑造山带中生代花岗伟晶岩相当发育,主要分布于麻扎- 康西瓦缝合带以南的喀喇昆仑造山带,构成了西自木吉—塔什库尔干,东到大红柳滩长达600 km的喀喇昆仑稀有金属成矿带。通过多年的研究,本文对西昆仑- 喀喇昆仑造山带37处稀有金属矿床(点)进行了全面系统的梳理,认为喀喇昆仑- 喀喇昆仑造山带表现为“西铍东锂”的格局,稀有金属成矿年龄集中213~206 Ma。将喀喇昆仑造山带稀有金属成矿带划分为木吉- 塔什库尔干稀有金属成矿亚带、赛图拉- 大红柳滩稀有金属成矿亚带,从西向东可划定4个矿化集中区：木吉- 布伦口稀有金属集中区、塔什库尔干- 塔吐鲁沟稀有金属矿化集中区、康西瓦稀有金属矿化集中区、大红柳滩- 白龙山稀有金属矿化集中区。同时,认为西昆仑- 喀喇昆仑造山带西段下一阶段的找矿可放在西合休南锂铍找矿远景区、阿然保泰铍找矿远景区、木吉西锂铍找矿远景区。     

利用铀油关系寻找可地浸砂岩型铀矿

可地浸砂岩型铀矿多数赋存于产油气盆地,并与油气关系十分密切。本文通过对可地浸砂岩型铀矿的成因分类、与油气藏的关系及与气藏异同点的分析对比,总结了几种典型油气藏上方的放射性异常模式。以二连盆地可地浸砂岩型铀矿与油气藏的客观相伴关系为例,在鄂尔多斯盆地进行了应用试验,取得了一定效果。因此,利用铀油相伴关系,在油气勘探中注意寻找铀矿(化)床,在铀矿(化)床周围的有利构造部位加强油气勘探是十分重要的。     

福建李家坊金矿床磁铁矿成因及其对金矿化过程的指示

福建泰宁李家坊金矿床位于武夷山成矿带中段,为闽西北何宝山矿田内新发现的一个中型金矿床,成因类型尚未明确。磁铁矿是该矿床中常见的氧化物,文章应用磁铁矿微量元素特征对李家坊金矿床成矿过程与成因类型进行约束。基于野外地质踏勘和钻孔岩芯编录,结合室内详细的岩相学观察,依据磁铁矿的结构和矿物共生组合,文章将其分为4种类型（Mt1a、Mt1b、Mt2和Mt3）。其中,Mt1a位于铜金矿脉边缘,呈板柱状,与绿泥石共生; Mt1b位于铜金矿脉边缘,呈自形-半自形粒状,与绿泥石-赤铁矿共生; Mt2位于铜金矿脉中,呈脉状产出,穿插早阶段的石英-黄铁矿脉,与绿泥石-绿帘石共生; Mt3位于铜金矿脉中,呈半自形-他形粒状,与绿帘石-赤铁矿共生,被后阶段黄铜矿包裹、交代。金主要以自然金和银金矿的形式赋存于Mt3中。原位微区分析结果表明,李家坊金矿不同类型磁铁矿均属于热液型磁铁矿。此外,从Mt1a型到Mt3型磁铁矿,w（Ti）呈逐渐降低的趋势,指示热液流体逐渐向低温条件演化; w（V）表现出先降低后升高再降低的变化规律,暗示热液流体的氧逸度有明显波动,但总体呈升高趋势。磁铁矿的显微结构和化学组成具矽卡岩型矿化特征,是判断矿床成因类型的证据。其中,Mt3型磁铁矿与Au矿化密切相关,其矿物组合与微量元素特征可指示金在低温高氧逸度的环境下沉淀。     

河北丰宁招兵沟铁磷矿床地质及综合利用前景

河北丰宁招兵沟铁磷矿床为赋存于太古宇绿岩带内低品位特大型矿床。含磷岩系具近似绿岩带下部火山岩群的特点。铁磷矿体呈层状,大的透镜状产出,还伴生Ti、V 等有益元素。矿石选矿回收性能良好。通过对该区当前内生低品位铁磷矿开采情况的调查,认为我国北方低品位铁磷矿综合利用前景乐观。