北山地区小狐狸山钼多金属矿床成矿类型及找矿方向

小狐狸山钼多金属矿床是近年来在北山地区发现的一个具中—大型规模的隐伏钼矿床. 该矿床成矿特征典型,赋矿岩体可以明显的划分为三个相带,即边缘相、过渡相和中心相。岩体中心相具强硅化、钾长石化现象,过渡相和边缘相具有明显的钠长石化蚀变特征,并叠加有岩浆期后云英岩化蚀变现象。钼矿体主要产于岩体过渡相和边缘相的钠长石化带和云英岩化带中。小狐狸山钼多金属矿床成矿时代为三叠纪, 属印支期构造-岩浆活动的产物。通过对Mo→Pb-Zn→稀有金属的复合矿化特征分析,推测该矿床可能是不同期次岩浆热液活动形成的热液叠加矿床。结合岩石地球化学、构造环境及其矿化、蚀变特征分析,该矿床应为板内伸展构造环境下形成的高-中温岩浆热液叠加型矿床。     

吉林省桦甸兴隆钨钼矿床地质特征及找矿方向

兴隆钨钼矿床属高中温热液矿床,矿体呈脉状产于燕山期花岗岩的断裂之中,矿体与云英岩化和硅化关系密切,矿化类型主要为石英脉-蚀变岩型,矿体主要受北西向构造控制.本文总结了矿床地质特征和成矿规律,确定了该区矿床的找矿标志.     

福建南平巨口白石岩钼矿床地质特征及成因探讨

南平巨口白石岩钼矿床位于闽西北隆起带的东南边缘与浦城-嵩口南北向断裂带交汇部位,产于燕山早期黑云母花岗岩小岩株的相变带上,矿化蚀变分带和工业钼矿体的容矿岩百、结构构造显示为成分单一的岩浆期后热液充填交代型钼矿床。     

内蒙古小东沟斑岩型钼矿床辉钼矿铼-锇同位素年龄及地质意义

为了进一步查明小东沟斑岩型钼矿床的形成时间,对主要钼矿体6件辉钼矿样品进行了铼-锇同位素分析,所获同位素等时线年龄为135.5±1.5Ma(2σ),其MSWD值为1.4。鉴于辉钼矿呈浸染状和团块状分布于斑状花岗岩株中,并且与石英和钾长石呈共生结构关系,可以推测小东沟地区钼矿床和斑状花岗岩株的形成时间均为早白垩纪,属燕山期构造-岩浆活动的产物。     

浙东南石平川钼矿床地质特征、成矿时代及成因

石平川钼矿床位于浙东南政和—大埔断裂与长乐—南澳断裂之间的火山坳陷带相对隆起区,空间上和成因上均与燕山晚期侵入的钾长花岗岩体关系密切,矿体受断裂构造控制。矿化类型为石英脉型,围岩蚀变主要为绢云母化、黄铁矿化,次为碳酸盐化。石英流体包裹体Rb-Sr等时线年龄为(87±1)Ma[锶初始值I(Sr)=0.713 36],形成时间为晚白垩世。成矿期流体包裹体研究表明其均一温度为114.4~325.8℃,集中于170.2~227.0℃。氢氧同位素研究表明,成矿流体的δ(D)为-52.8‰~-64.9‰,δ(18O)为-3.85‰~-7.27‰,反映成矿流体来自混合的岩浆水与大气降水。黄铁矿的硫同位素研究表明δ(34S)为+3.14‰~+4.19‰,表现为岩浆硫特征。辉钼矿Re的质量分数为15.05×10-6~37.65×10-6,与其他钼矿床中辉钼矿Re质量分数的对比结果显示,成矿物质来源于下地壳。以上研究表明石平川钼矿床属中低温岩浆期后热液充填石英脉型钼矿床。     

希勒库都克钼铜矿床地球化学特征及成因

希勒库都克钼铜矿床位于新疆北部富蕴县境内,萨尔布拉克-阿克塔斯断裂南侧.初步研究和钻孔资料表明,矿体受斑岩体控制,矿石具细脉浸染状、稀疏浸染状构造,金属矿物主要为辉钼矿、黄铁矿、黄铜矿、白铁矿、磁铁矿.岩体和其接触带内常见硅化、绿帘石化,次为绢云母化、钾化、绿泥石化、矽卡岩化,外围褐铁矿化,未见明显蚀变分带.含矿岩石地球化学研究表明,花岗斑岩、花岗闪长岩(花岗闪长斑岩)、闪长玢岩属弱铝质不饱和高钾钙碱性岩石系列,微量元素分布模式总体趋势一致,表明为同源岩浆演化产物.结合年代学研究成果认为,成岩成矿可能为同一岩浆作用过程.对矿区浅部地层中含辉钼矿石英脉包裹体氢、氧同位素研究成果显示,成矿流体中具来自天水部分流体特征.     

内蒙古小东沟斑岩型钼矿床的成矿时代及成矿物质来源

小东沟斑岩型钼矿床位于大兴安岭南段,距北部的西拉木伦河大断裂仅25 km。对小东沟岩体进行了Sr-Nd同位素和铅同位素分析,87Sr/86Sr(t)为0.705 0~0.705 5,εNd(t)为-2.4~-2.8;对主要钼矿体的6件辉钼矿样品进行了铼-锇同位素分析,所获同位素等时线年龄为(138.1±2.8)M a,表明小东沟钼矿床形成于早白垩世。铅同位素分析结果表明小东沟斑岩型钼矿床的成岩成矿物质具有不同来源,成岩物质来自俯冲洋壳衍生的新生地壳物质,而成矿物质来自地幔分异的产物(流体),属于壳源岩浆+幔源流体的组合。结合区域构造演化历史,对小东沟斑岩型钼矿的成因做出如下解释:在早白垩世,大兴安岭开始隆升,岩石圈拆沉,软流圈(层)物质上涌、基性岩浆的底侵以及地幔流体的加入,引起下地壳岩石的熔融,随后更多的地幔含矿流体进入到岩浆房。岩浆携带来自地幔的含矿流体,沿着区域性的EW、NE向深大断裂上侵定位,并在此过程中演化形成富硅、富钾质的花岗岩,最后沿近NS向的断裂侵位到二叠纪地层中,沉淀形成矿床。     

陕西金堆城斑岩钼矿床地质特征及成因探讨

金堆城花岗斑岩在燕山期侵位于元古代熊耳群变细碧岩中,按其岩石化学特征应属高硅富钾的钙碱性系列岩石。钼矿化发育于斑岩体及其外接触带内,矿体由含钼石英细网脉组成,最大矿化深度约达1000m。围岩蚀变自斑岩体向外为:钾化、绢(云)英岩化→硅化→青磐岩化,其中以硅化最为强烈且与钼矿化关系最密切。气液包裹体与含子矿物多相包裹体常常共存,主要成矿温度为300—400℃。硫、氧和碳同位素特征表明,主要成矿阶段的成矿流体是以岩浆水为主的混合液,硫、钼主要来源于花岗岩浆。低f_(o2)、高f_(s2)的弱酸性还原条件以及成矿流体沸腾是辉钼矿沉淀的主要因素。矿床成因类型属斑岩型中高温热液钼矿床。     

河南商城县汤家坪钼矿床地球化学特征与成矿模式

在研究商城县汤家坪大型钼矿床的赋矿岩体特征、成矿物质来源、成矿流体性质和成矿地球动力学背景的基础上,建立了矿床成岩成矿模式。研究发现汤家坪钼矿主成矿期石英包裹体,以CO₂包裹体和含子矿物的多相包裹体为主,少量二相气液包裹体,主成矿期的成矿温度在260～419℃之间;包裹体盐度具有典型的双配分模式特征,其中含盐度介于32.6%～48.54%(NaCl)之间的含子矿物的多相包裹体基本代表含水的“岩浆”。成矿物质来源于元古宙大别片麻杂岩部分熔融而形成的富钼花岗岩浆。成矿流体为高温高盐度的初始岩浆水,中后期有大气降水加入。由此建立汤家坪钼矿床的成岩成矿模式为：大别片麻杂岩重熔形成岩浆源—伸展体制下岩浆侵入冷凝阶段—钾化及初始岩浆热液成矿阶段—大气降水加入的中后期成矿阶段。     

海南屯昌地区高通岭钼矿床的地质、地球化学 特征及成矿时代

高通岭钼矿床位于华南板块南部的华南褶皱系五指山褶皱带内,共查明平行脉状矿体9个、矿化体5个.矿石分石英脉型和钾长花岗岩型2种,矿石中含辉钼矿、黄铁矿、黄铜矿、方铅矿、闪锌矿及石英、钾长石、黑云母、绢云母、绿泥石等.高通岭花岗岩体的Mo含量比其克拉克值高4倍,沿岩体构造裂隙发育钾长石化、黄铁矿化、硅化、绢云母化、绿泥石化等蚀变和钼矿化.成矿流体成分为K -Na -Cl--F--SO42-型;S、C、H、O同住素组成反映成矿物质以岩浆源为主,流体为岩浆水与大气降水混合来源.辉钼矿Re-Os等时线年龄为98.4Ma 2.5Ma.与高通岭花岗岩体侵位的时代一致.该矿床为与燕山晚期岩浆活动有关的热液石英-硫化物脉型钼矿床.     

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.     

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.)     

GEOCHEMISTRY

正20142002 Wei Hualing(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang065000,China);Zhou Guohua Element Content and Mineral Compositions in Different Sizes of Soil in Tongling Area,Anhui Province(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(11),2013,p.1861