云南金厂河铁铜铅锌多金属矿床矽卡岩矿物学特征及蚀变分带

金厂河铁铜铅锌多金属矿床是位于"三江"地区保山地块北部的隐伏多金属矿床,矿体呈层状、似层状产于上寒武统核桃坪组大理岩化灰岩与矽卡岩内,受NW向F2断裂和NE向F10断裂控制明显。本文根据野外穿切关系及矿物共生组合,将矿床划分为4个成矿阶段,即矽卡岩阶段、退化蚀变阶段、石英-硫化物阶段、碳酸盐阶段。矿区脉石矿物包括石榴子石、辉石、角闪石、绿帘石、绿泥石、黑柱石、石英、方解石、萤石等,矿石矿物主要包括磁铁矿、黄铜矿、磁黄铁矿、黄铁矿、方铅矿和闪锌矿。本文以矽卡岩矿物为研究对象,利用电子探针技术对其矿物学特征进行研究,结果表明:该矿床矽卡岩矿物主要为钙矽卡岩,石榴子石以钙铁榴石为主,辉石为透辉石-钙铁辉石过渡系列,角闪石主要为阳起石、铁阳起石和铁闪石,黑柱石含铁较高,多与磁铁矿相伴生;本矿床含少量锰质矽卡岩,包括锰铝榴石、含锰钙铁辉石、含锰阳起石、含锰黑柱石。矿床从深至浅的垂向分带以及自东向西的水平分带具有相似性:含Fe钙质矽卡岩※含Cu钙质矽卡岩※含Pb-Zn锰质矽卡岩※大理岩化灰岩,表明由矿床中部至两侧,自东向西,均有明显高温氧化环境向低温还原环境演化趋势。通过与已有矽卡岩Pb-Zn矿床矿物分带模型对比,推测存在深部岩浆热液以断裂交汇部位侵入交代围岩成矿,该矿床应为远接触带的矽卡岩型隐伏铁铜铅锌多金属矿床。     

西藏邦铺钼多金属矿床矽卡岩矿物学特征及其地质意义

西藏邦铺超大型钼多金属矿床中矽卡岩铅锌矿体赋存于下二叠统洛巴堆组矽卡岩和大理岩中,矿体呈似层状、透镜状产出,矽卡岩矿物较为发育。为进一步查明矿床矽卡岩矿物种属及矽卡岩类型,剖析矽卡岩形成环境及其与矿化类型之间的关系,基于对矽卡岩矿物系统地显微镜下观测,利用电子探针对矿床主要矽卡岩矿物化学成分进行了系统分析。结果表明,石榴子石端员组分以钙铁榴石为主,含少量锰铝榴石和钙铝榴石;单斜辉石主要为透辉石-钙铁辉石系列,含少量锰钙辉石;似辉石为铁钙蔷薇辉石;角闪石主要为钙质阳起石;绿帘石贫Fe、Mg。矽卡岩矿物组合特征表明,矿床矽卡岩兼具钙矽卡岩和锰质矽卡岩特征;早期矽卡岩形成于较强的氧化环境,成矿岩浆流体亦具有较高氧逸度。邦铺首次发现锰质矽卡岩矿物组合,表明矿区具有银矿找矿潜力,为下一步找矿工作提供了理论支撑。     

青海牛苦头矿区锰质黑柱石成因及其地质意义

锰质黑柱石是矽卡岩型铅锌矿床中一种常见的脉石矿物,其与铅锌矿体关系密切。本文对东昆仑祁漫塔格地区牛苦头铅锌多金属矿床中黑柱石的产状、矿物共生组合、化学成分等进行了研究。牛苦头矿区锰质黑柱石主要产于3种矿物组合:黑柱石+石榴子石+磁铁矿组合;黑柱石+锰钙(铁)辉石+方铅矿+磁铁矿组合;黑柱石+方解石+石英+硫化物(黄铁矿+磁黄铁矿+其他硫化物)组合,并形成自内向外石榴子石-磁铁矿—黑柱石—锰钙辉石的矽卡岩分带。上述3种组合分别对应矿床的3个蚀变矿化阶段:进变质阶段(阶段I),石榴子石被交代分解,形成黑柱石;退变质阶段(阶段Ⅱ),锰钙(铁)辉石分解形成黑柱石;石英硫化物阶段(阶段Ⅲ),黑柱石进一步分解,形成磁铁矿、方解石和石英。电子探针结果,牛苦头矿床黑柱石的化学分子式为Ca_(0.94-0.98)(Fe_(1.22-1.92)Mn_(0.10-0.75)Mg_(0.01-0.03))■(Fe_(0.83-0.93)Al_(0.01-0.07))■[Si_(2.00-2.07)O_7]O(OH);LA-ICP-MS原位分析显示,牛苦头矿区黑柱石的稀土配分曲线与矿区进变质阶段形成的石榴子石、锰钙(铁)辉石近乎一致。综合研究认为,矿区黑柱石为进变质阶段的石榴子石和辉石蚀变分解的产物;矿床自内向外的矽卡岩分带反映了矽卡岩被逐渐交代的过程,并伴随了成矿流体从主矽卡岩阶段的"还原(Fe~(2+)、Mn~(2+))"环境向退变质阶段偏氧化(先是Fe~(2+)-Mn~(2+)+Fe~(3+),后是Fe~(3+))环境的转变。     

青海尕林格铁矿床矽卡岩矿物学及蚀变分带

尕林格矽卡岩型铁多金属矿床位于青海省西部祁曼塔格成矿亚带的中部.矿体处于花岗闪长岩与滩间山群白云质大理岩接触带内以及外接触带沿NWW向断裂构造破碎带分布的大理岩和蚀变安山岩内.从侵入接触带往东,蚀变岩石分带性明显,主要划分出3种含矿矽卡岩带:含Fe的镁质矽卡岩带,含Fe、Cu的钙质矽卡岩带,含Fe、Pb、Zn的锰-钙质矽卡岩带.镁质矽卡岩带的矽卡岩矿物主要包括镁橄榄石及其蚀变矿物蛇纹石、粒硅镁石、透辉石、斜绿泥石,有关的金属矿物主要为磁铁矿.钙质矽卡岩带的主要矽卡岩矿物有绿钙闪石、铁阳起石、钙铁辉石、铁叶绿泥石、磷灰石、中长石,有关的金属矿物为磁铁矿、磁黄铁矿和少量黄铜矿.与锰-钙质矽卡岩有关的矽卡岩矿物有锰钙铁辉石、钙铁榴石、钙铝榴石、铁镁绿泥石、绿帘石、硅灰石、磷灰石、钙长石等,金属矿物有方铅矿、闪锌矿、磁铁矿和磁黄铁矿.通过对矿物组合的研究,确定了不同矿物组合的生成关系,划分了成矿期次,分为矽卡岩期、退化蚀变期和金属硫化物期,矽卡岩期又分为早、晚2个阶段.矽卡岩早期生成的石榴子石的化学成分端员以钙铝榴石(Gro67～ 99)为主,辉石的成分端员以透辉石(Di96～ 98)为主;矽卡岩期晚期阶段石榴子石的化学成分端员以钙铁榴石(Ad78～98)为主,辉石的成分端员以钙铁辉石(Hd68～ 84)为主.与中国东部矽卡岩型矿床进行对比后发现,锰-钙质矽卡岩带是一种向锰质矽卡岩带过渡的类型,对于寻找与锰质矽卡岩有关的矿化类型具有指示意义.     

西藏浦桑果铅锌多金属矿床矽卡岩矿物学特征及其地质意义

西藏浦桑果铅锌多金属矿床位于南冈底斯成矿带火山岩浆弧内,矿区矽卡岩型铅锌矿体主要呈似层状和透镜状近东西向赋存于白垩系塔克那组第4岩性段矽卡岩化大理岩中,矽卡岩矿物较发育。为进一步查明矽卡岩矿物种属及矽卡岩类型,剖析矽卡岩的形成环境及其与成矿的关系,在对矽卡岩矿物系统的显微镜下鉴定基础上,利用电子探针对矿区内主要矽卡岩矿物化学成分进行了系统分析。结果表明,石榴子石主要为非连续的钙铁榴石钙铝榴石类质同像系列(And47.39~98.17Gro0.59~50.22Ura+Pyr+Spe0~3.53),且早期主要形成钙铁榴石,部分钙铁榴石含锰质较高;单斜辉石主要为钙铁辉石-锰钙辉石-透辉石类质同像系列(Hd37.91~74.16Jo0.91~61.66Di0.43~46.07);似辉石主要为硅灰石,端员组分为Wo99.09~99.26En0.50~0.56Fs0.13~0.24;角闪石主要为镁角闪石,具钙质角闪石属性;绿帘石贫铁、镁而富铝、钙;绿泥石属于密绿泥石类。矿床矽卡岩矿物组合特征表明,浦桑果矿床矽卡岩兼具钙质矽卡岩和锰质矽卡岩的特征。早期矽卡岩形成于高温、偏碱性、强氧化的开放体系中,成矿流体具有较高氧逸度。锰质矽卡岩矿物特征及独立银矿物的存在综合表明矿区具有银矿找矿潜力,为下步找矿工作提供了思路和方向。     

青海西部祁漫塔格地区矽卡岩铁铜多金属矿床的矽卡岩类型和矿物学特征

青海西部祁漫塔格地区矽卡岩型铁铜多金属矿床分布广泛,主要发育两类矽卡岩,即钙矽卡岩和锰质矽卡岩,少数矿区还有镁矽卡岩.钙矽卡岩的组成矿物主要有透辉石、钙铁辉石、钙铝-钙铁系列石榴石、绿帘石、阳起石和方柱石,常伴随Fe、Cu、Mo矿化,构成钙矽卡岩型铁多金属矿床或铜(钼)矿床,而锰质矽卡岩主要由锰钙铁辉石组成,含少量锰三...     

湖南金船塘锡铋矿床矿物化学特征及其地质意义

金船塘锡铋矿床是东坡矿田内一以锡铋为主的大型矽卡岩型多金属矿床,迄今为止对其矽卡岩矿物学特征的系统研究较少。本文以金船塘锡铋矿床主要矽卡岩矿物为研究对象,利用电子探针技术对该矿矽卡岩矿物学特征进行了研究。电子探针分析结果表明:金船塘锡铋矿床的矽卡岩中的石榴子石主要为钙铝榴石-钙铁榴石系列,含少量的锰铝榴石,辉石为透辉石-钙铁辉石系列,角闪石主要为铁镁钙闪石,其次为钙镁闪石、阳起石和透闪石,表明该区的矽卡岩为钙质矽卡岩,含少量的锰质矽卡岩。同时,根据矽卡岩矿物学特征的研究,笔者进一步探讨了该矿床锡石的沉淀机制:早期矽卡岩阶段的氧逸度较高,Sn主要以Sn4+的形式替代Fe3+存在于石榴子石中,而在晚期矽卡岩阶段由于氧逸度的降低,Sn主要以Sn2+的形式呈氯的络合物在流体中迁移,由于流体的温度、盐度、pH和氧逸度的变化,Sn2+被氧化成Sn4+,导致锡石沉淀。     

云南都龙锡锌多金属矿床矽卡岩矿物学特征与地质意义

都龙锡锌矿床位于云南省马关县境内,是我国第3大锡多金属矿床。前人对该矿床进行了大量的研究工作,但关于该矿床的成因仍存争议,有岩浆热液、喷流沉积和沉积-变质-热液改造3种成因观点。矽卡岩作为矿区最重要的含矿岩石,对其开展相关的研究工作对于解决上述争议具有重要的意义。本文在详细的镜下鉴定工作之上,对矽卡岩中的石榴子石、辉石和角闪石进行了电子探针成分分析。分析结果表明,矽卡岩中石榴子石为钙铁榴石-钙铝榴石系列,辉石主要为透辉石-钙铁辉石系列,角闪石主要为阳起石和铁阳起石,另含有少量的铁角闪石。结合前人年代学、流体包裹体、硫、铅和碳同位素等方面研究资料,认为该矿床成因类型为岩浆热液成因的矽卡岩型多金属矿床。     

滇西保山地块金厂河Fe- Cu- Pb- Zn矽卡岩型多金属矿床黑柱石成因及地质意义

黑柱石是一种矽卡岩型铅锌及铁矿床中少见的矿物,与铅锌矿体、磁铁矿体关系密切。为查明黑柱石成矿过程中与铅锌铁铜多金属成矿作用的关系,本文对金厂河Fe- Cu- Pb- Zn多金属矿床中的黑柱石产状、矿物共生组合、化学成分、分带性等开展了研究。根据电子探针数据计算可得,金厂河矿区黑柱石的化学式为:Ca0. 95- 1. 08(Fe0. 87- 1. 97Mn0. 08- 0. 36Mg0. 01- 0. 06)2+(1. 89- 2. 03)(Fe0. 82- 1. 04Al0. 01- 0. 03)3+(0. 88- 1. 15)\[Si1. 94- 2. 08O7\]O(OH)。结合矿物组合类型、产状、分带特征等,推测矿床内矽卡岩由内带逐渐向外带交代的趋势。金厂河矿区主要有3种矿物共生组合：黑柱石+磁铁矿组合,黑柱石+磁铁矿+黄铁矿+黄铜矿组合,黑柱石+方铅矿+闪锌矿+黄铜矿组合,分别对应三个不同的蚀变阶段：晚期矽卡岩阶段（代表组合I）,以石榴子石的分解为主,形成大量的黑柱石;退蚀变阶段（代表组合II）,以阳起石、黄铜矿、黄铁矿发育为主;石英- 硫化物阶段（代表组合III）,以发育大量的方铅矿、闪锌矿为主,同时这一阶段内黑柱石分解,形成阳起石、方解石、磁铁矿等。此外,黑柱石的稀土元素配分模式与石榴子石的类似,一定程度上保留了石榴子石的稀土元素特征。研究认为：黑柱石是早期石榴子石退化分解的产物,矿床自内向外逐渐交代,形成了铅锌铜矿体中以锰质黑柱石为主,而磁铁矿体、铜矿体中以含锰黑柱石为主的分带特性。锰质黑柱石有利于铅锌矿的形成,而对于磁铁矿有贫化的影响,同时也可为矿区揭露中酸性岩体和深部找矿提供重要科学意义。     

西藏龙玛拉铅锌矿床矽卡岩矿物特征及其地质意义

龙玛拉铅锌矿床是位于冈底斯成矿带之念青唐古拉铅锌成矿亚带东段的一个典型矽卡岩型矿床。前人对矿床成矿物质来源及演化、成岩-成矿时代、矿床形成动力学背景等方面进行过一定的研究, 但对矽卡岩矿物学及分带模式还缺乏系统的研究。为此, 本文通过详细的野外地质编录、系统的镜下鉴定和电子探针分析, 开展矽卡岩矿物组合、矿物成分及其分带特征研究。矿床矽卡岩矿物主要包括石榴子石、辉石、硅灰石、绿泥石和绿帘石等。矽卡岩矿物组合和化学成分在空间上具有明显的分带性。矽卡岩主要发育在角岩与大理岩接触带, 或沿裂隙充填在围岩中, 横向上显示了从褪色角岩→石榴子石矽卡岩→深色角岩→透辉石矽卡岩(矿体)→大理岩→角岩的分带特征。垂向上由顶板至底板表现出从角岩→石榴子石矽卡岩→透辉石矽卡岩→大理岩→石榴子石矽卡岩→透辉石矽卡岩→角岩的岩性分带特征。矿床石榴子石为钙铁-钙铝榴石类质同象系列(And7.92~88.63Gro5.92~86.46Pyr+Spe1.04~5.11), 端员组分变化范围较大, 表明矽卡岩的形成环境并不是完全封闭的体系。通过对铅锌主矿体的赋矿矽卡岩中石榴子石进行研究, 表明成矿流体是从矿区南西方向向北东方向运移就位形成主矿体, 为矿区寻找成矿岩体及深部找矿提供指导。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)