论570矿床稀土元素特征及地球化学演义

本文对５７０矿床新鲜岩石、蚀变岩石的稀土元素进行了地球化学研究。稀土元素特征表明，矿区基底花岗岩的成因类似华南改造型花岗岩；火山岩可能是基底变质深熔作用形成；次花岗斑岩与火山岩同源。在弱酸性一中性热液蚀变（赤铁矿化和水云母化）过程中，稀土元素的变化不大，仅表现变稀土总量有所增减，而碱性蚀变（碱交代和碳酸盐化）则一方面表现出稀土总量的变化，另一方面轻，重稀土的分馏程度也有变化。矿石中稀土总量，特别是     

平顶山金矿床的稀土元素地球化学特征

平顶山金矿床的矿石、石英脉、蚀变花岗岩、细晶闪长岩及蚀变闪长玢岩等的稀土元素地球化学特征是：蚀变花岗岩、矿石、石英脉三者的稀土配分曲线基本相似,轻稀土富集型而重稀土则相对较贫。而蚀变闪长玢岩脉及细晶岩脉的稀土总量较前三者高出许多,具较明显的铕负异常。这些特征指示了成矿热液可能来源于花岗岩侵入后的岩浆期后热液。     

武夷山高溪和富城花岗岩体地球化学及其与铀成矿的关系

从成矿地质条件分析，武夷火山铀成矿带中的主要铀矿床的共同点是都具有花岗岩基底岩石。选择富城和高溪两花岗岩体进行地球化学研究。这两个岩体均为复式岩基，其主体岩石都形成于印支晚期（高溪：２１４．６Ｍａ；富城：２０３～２２６Ｍａ）。岩体中的长石为微斜长石；黑云母为铁云母和铁叶云母。岩石化学表现为富硅、偏碱和铝过饱和的特征。微量元素Ｃｏ、Ｎｉ、Ｃｒ、Ｓｒ、Ｂａ含量和Ｓｒ／Ｂａ比值较低，Ｒｂ、Ｎｂ、Ｐｂ、Ｚｎ的含量和Ｒｂ／Ｓｒ比值高。稀土总量较高，轻稀土富集，轻、重稀土的比值高，并有强烈的铕亏损。高溪和富城两岩体的初始锶同位素组成高（分别为０．７１２３９和０．７１９８），钕同位素组成低（－６．６２～－１２．８４），这些表明高溪岩体属改造型花岗岩。两岩体中活性铀的比例高，特别是在蚀变作用中活性铀的比例增加。铅同位素追踪研究表明，在蚀变过程中岩体中的铀发生了大量的丢失。矿石铅同位素和岩体铅同位素都位于造山带的演化线附近，且矿石铅、火山岩铅、花岗岩铅及基底变质岩铅同位素组成呈线性关系，据此认为高溪和富城花岗岩体分别是形成５７０和６７２２矿床主要铀源体之一     

银山多金属矿床成矿流体稀土元素地球化学

对江西银山矿床规模不同的矿体、蚀变围岩及其原岩的稀土元素特征进行了对比研究。结果表明，成矿流体的稀土元素以轻稀土富集型，无Ce异常，强烈的Eu正异常而显著地区别于赋矿围岩。热液蚀变作用造成围岩的稀土总量升高12．1％－52．4％，轻重稀土比值降低，但紧邻矿体的稀土含量则低于原岩。导致围岩稀土总量升高有两个因素：（1）通过热液蚀变作用带入了稀土元素；（2）体系主元素（Si)质量迁移而造成稀土元素出现表观浓缩。其中以前者为主导因素。矿体的接触带及其紧邻处的蚀变围岩的REE含量明显偏低，主要因出现大量石英或石英＋硫化物等矿物的显微脉体（脉幅3－8μm）而被稀释，是一种表观亏损现象。研究结果表明，矿体越大，其围岩REE被“稀释”越明显，涉及的范围越大，REE特征可能是一种潜在有效的找矿勘探地球化学指标。     

东昆仑祁漫塔格山西段鸭子泉志留纪火山岩特征

在新疆阿牙克库木湖幅一比二十五万区域地质调查中，于东昆仑祁漫塔格山鸭子泉构造混杂岩带中发现大量以蚀变玄武岩、蚀变玄武安山岩、蚀变安山岩及蚀变辉长岩、蚀变闪长岩为主的中基性火成岩，其呈大小不一的岩片岩块存在于构造混杂岩带内。通过岩石学、岩石地球化学的研究其属钙碱性岩系的玄武岩-安山岩；具有稀土总量较低、轻稀土弱富集、重稀土分馏不明显、稀土元素配分曲线呈右倾型、大离子亲石元素富集、Nb、Ti等元素亏损的特征，显示其形成于与俯冲作用有关的岛弧环境；依据同位素测年资料和地质构造演化确定该岛弧火山岩就位于志留纪，这对东昆仑地区的地质构造演化具有重要意义。     

康滇地轴中段前震旦系马鞍山组的发现及特征

四川会东县“马鞍山组”的发现，是近年来康滇地轴中段前震旦系地质研究的重要进展，对提高基础地质研究，进一步寻找会理拉拉式铜矿具有重要意义。“马鞍山组”的剖面特征和岩石学研究表明，该组相于古元古界河口群，岩性组合主要为海相喷发的钠质火山岩－细碧岩组合，蚀变强烈；火山岩岩石化学特征表现为富钠、贫钾，高钙、低铁，岩性偏中酸性，火山岩属碱性玄武岩系列。微量元素以Cu-Au-U-Zn-As-Sb-Fe-Cr-Co组合为特征。岩石的稀土总量低，轻重稀土比值大，为轻稀土富集型，具有等铕亏损和微弱铈亏损；其配分模式图呈向右倾斜的“V”字型。     

四川红原地区三叠纪花岗岩的地球化学特征及地质意义

红原地区三叠纪花岗岩位于松潘-甘孜造山带的北部,侵位于三叠纪西康群砂板岩系中,岩石类型主要为中细粒花岗闪长岩和二长花岗岩。岩石地球化学分析结果表明该区岩体属于准铝质-过铝质富钾钙碱性系列,大部分为I型花岗岩(羊拱海和达盖寨岩体部分表现为A型),稀土元素总量变化较大,轻稀土元素相对富集,稀土元素球粒陨石标准化配分型式为右倾型,Eu异常不明显。轻重稀土元素分馏明显,轻稀土元素分镏大于重稀土元素。岩石地球化学特征指示该区花岗岩体可能为同源的地壳物质的部分熔融作用所形成,源岩可能为变杂砂岩和变中性火山岩,热源可能来自于地幔岩浆的底侵作用。     

北秦岭丹凤地区产铀花岗岩稀土元素地球化学特征

针对北秦岭丹凤地区产铀花岗岩的区域地层、赋矿围岩、蚀变岩和铀矿石进行稀土元素地球化学研究,结果表明:各类样品具有大体类似的LREE富集及Eu负异常的稀土配分模式,表明它们之间稀土元素特征具有继承性;赋矿黑云母二长花岗岩与区域地层(丹凤岩群变质基性火山岩)稀土元素特征指示,二者均形成于岛弧环境;蚀变花岗岩和铀矿石主要继承了赋矿花岗岩的特征。各类样品Y/Ho值变化范围狭窄,为25.09~33.46,显示它们具有共同的源区。铀矿石具有最高的w_B(∑HREE),且与铀矿石的品位存在正相关关系,暗示HREE与铀的迁移具有同步性。     

个旧卡房蚀变花岗岩地球化学特征及其与成矿的关系

文章通过分析个旧卡房不同蚀变花岗岩地球化学特征,表明花岗岩总体上呈强酸性、富碱性、铝过饱和、贫基性特点;富集轻稀土模式,显强烈的负铕异常。花岗岩富集Sn、W等成矿元素,具有很好的含矿性。不同蚀变类型对常量、微量、稀土元素的地球化学特征影响有差异,钾化使其具有强富钾特征,绿泥石化使稀土元素特征变化较大,并且这些元素的迁入迁出是影响成矿元素富集的直接因素。与成矿最为密切的是钾化、电气石化、萤石化、黄铁矿化,可作为找矿标志。卡房矿田具有与老卡岩体西凹蚀变岩型矿床类似矿体的找矿潜力。     

圈定地质构造特异部位寻找中生代大型与超大型火山岩型铀矿床

文中分析了中生代大型、超大型火山岩型铀矿床产出的特异部位──含矿火山塌（断）陷的地质环境，将其归纳为＂近带、伴盆、早洼、晚隆、切壳、酸底、泥化＂１４字特征。在讨论该类铀矿床的形成机制的基础上，提出了特异部位的９条定位标志，即：位处１，２级构造单元结合部位的构造岩浆活动带；构造岩浆活动带边部的大型火山沉积盆地；火山沉积盆地边部的港湾状小型火山塌（断）陷；火山塌（断）陷的火山岩发育充分；火山塌（断）陷在盆地发展晚期隆起；火山塌（断）陷受一条长期活动的切壳断裂控制；火山塌（断）陷的基底发育有多期花岗岩体；火山塌（断）陷的盖层遭受强烈的以泥化为主的中低温蚀变作用；蚀变带有硅化、低温钠长石化、铁绿泥石化等蚀变作用叠加，并见有铀及其相关元素异常。     

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