花岗岩中原生与次生白云母的鉴别特征及其地质意义——以赣南富城强过铝质花岗岩体为例

通过显微镜下观察和电子探针成分分析,发现赣南富城强过铝质花岗岩中存在3种类型白云母,即原生白云母、交代型白云母和次生白云母,其平均晶体化学式分别为:K1.62Na0.06Fe0.32Mg0.39Ti0.02Al4.89Si6.54O10(OH)4(原生白云母)、K1.55Na0.07Fe0.43Mg0.24Ti0.03Al4.96Si6.50O10(OH)4(交代型白云母)、K1.51Na0.07Fe0.27Mg0.21Ti0.00Al4.98Si6.65O10(OH)4(次生白云母)。根据富城花岗岩主要造岩矿物的结晶顺序(斜长石→钾长石→黑云母→白云母→石英),结合白云母、黑云母稳定曲线及合成花岗岩初融曲线对比分析,富城强过铝质花岗岩中交代型白云母是在花岗岩结晶过程中交代较早晶出的黑云母形成的,其形成温度高于花岗岩熔体的固相线温度(～650℃),故应归属于原生白云母。本文提出根据岩石学宏观特征、岩石化学特征及岩相学微观特征区分花岗岩中原生白云母与次生白云母的综合鉴别方法。     

Fe-Al云母及铝铁叶云母

黑云母花岗岩→二云母花岗岩→白云母花岗岩是华南花岗岩类中一种常见的岩石演化序列。岩石中存在贫Li富Fe、Al云母的矿物组合。例如:五里亭-101杂岩体云母组合为黑云母-铁白云母-白云母,湘千岩体为黑云母-锂铁叶云母-铁白云母-白云母,黄山岩体的云母组合包括锂黑云母-锂铁叶云母等。这些云母(表1)的分子式(按氧的原子数等于22计算)中,Li从小于0.4(白云母)到小于0.6(黑云母),低于八面体阳离子总数的10%。对这些富     

应用X射线衍射-扫描电镜-光学显微镜鉴定黑龙江石墨尾矿中的绢云母

石墨尾矿作为一类二次资源,当云母类矿物的含量在10%以上时,具有回收利用价值。黑龙江某地石墨尾矿中含有10%以上的云母类矿物,但其细度(500~800目)低于常规的云母矿,本文采用X射线衍射(XRD)分析矿物组成,再结合化学分析、扫描电镜-能谱、光学显微镜与纯矿物进行对比,由此鉴定云母类矿物种属。XRD研究初步表明石墨尾矿含有的云母族矿物属于白云母亚类或黑云母亚类。扫描电镜分析表明尾矿中的云母矿物与纯绢云母矿物均以片状和鳞片状为主要存在形态,而纯黑云母主要以片状形式存在。尾矿的Si O2含量为5%~13%,Al2O3含量为4%~8%,与纯绢云母接近。光学显微镜鉴定显示在正交偏光下石墨尾矿中的云母颜色和纯绢云母类似,而与纯黑云母截然不同。综合以上结果最终可确定该地石墨尾矿中的云母族矿物为白云母亚类中的绢云母。本研究为后续石墨尾矿的选矿工艺奠定了基础,也可应用于类似细度绢云母的鉴定。     

一株产铁载体细菌的筛选及其与云母的相互作用

        产铁载体细菌与云母类矿物相互作用的研究有助于了解矿物生物风化和土壤形成的演化规律和机理。采用纯培养法 自南京龙山废钾矿区酸模根际土壤分离筛选到一株高产荧光铁载体的细菌Z6,通过16S rDNA 序列分析和生理生化反应将其 鉴定为假单胞菌属（Pseudomonas sp.）;通过室温静置培养试验研究Z6 菌株与云母的相互作用结果表明,细菌生长代谢前期 （8~15 d）快速产生大量铁载体,菌株与矿物共培养75 d 后,产铁载体细菌对云母类矿物确实产生了风化作用,黑云母组发 酵液中Fe 含量增加了211 倍,Si 含量增加了约27.8 倍,SEM 显示云母表面出现溶蚀坑,细菌可以在矿物表面形成生物膜或 矿物- 细菌复合物。不同矿物对共培养体系中细菌数量、荧光铁载体含量、溶液pH 的影响不同。     

解钾细菌对西北干旱地区不同硅酸盐矿物的解钾效应研究

为了开发西北干旱地区土壤潜在肥力并提高土壤水分利用效率,笔者以解钾细菌为供试菌种,西北干旱地区代表性土壤矿物钾长石和伊利石为供试基质,采用实验室培养的方式,研究不同水分和接菌浓度条件下解钾细菌对土壤矿物的解钾效应,并通过傅里叶变换红外光谱、透射电镜和能谱分析技术探究解钾细菌对矿物形貌和结构成分的影响。结果表明,解钾细菌对钾长石和伊利石均有显著的解钾效应,该作用受水分、接菌浓度因素影响显著。钾长石最佳接菌量15%、最佳含水量70%;伊利石最佳接菌量20%、最佳含水量70%。钾长石受解钾细菌作用发生溶蚀,K含量降低,Si/Al降低,说明解钾细菌不但可以释放钾长石中的钾元素,还可溶出Si元素并用以自身的生长需求。伊利石受解钾细菌作用层间电荷降低,铝氧八面体中2价阳离子释放,层间电荷降低,造成层间K+离子和吸附水的释放。伊利石傅里叶变换红外光谱曲线显示K元素的释放与层间水分子的释放有关。因此,进一步研究解钾细菌作用下的土壤粘土矿物Si、Fe等元素的迁移,以及层间K元素与层间水分子的相互作用具有重要的生态意义。     

西藏过铝花岗岩矿物化学特征及其岩石学意义

本文系统地讨论了西藏过铝花岗岩中斜长石、钾长石、黑云母、白云母和电气石的矿物化学特征。结果表明：岩石中的斜长石均以Ab为主，占78．73％。100％，An分子为0．13％～18．93％，而Or分子仅为0．19％-3．74％；在长石的成分分类图解中多分布于更长石区内，少量分布于钠长石区。钾长石的端元组分中Or含量最高，为81％-98．48％，Ab为1.52％～19．00％，基本不含An分子，在成分分类图解中集中分布在Ab-Or线的正长石区内。斜长石中Ab〉An〉Or，主要属更长石，极少量为中长石；钾长石具有高Or含量，显示Or〉〉Ab〉〉An，属钾透长石。白云母在以22爪氧原子计算的分子式中，Si与Al的阳离子数均较高，其中Si为6．0575-6.6412，属多硅白云母；黑云母中Si阳离子数绝大多数小于6，值介于5．3227-6．1265之间，平均为5．5718；Al离子数为1．8735-2．6464，四面体配位为Si、Al^Ⅳ所占据，八面体配位的阳离子中Al^Ⅵ为0．2101-1．7388，大离子位中以K为主。过铝花岗岩中黑云母的Mg／（Mg＋Fe）比全岩的Mg／（Mg＋Fe）比值略高，但二者具有正相关关系，说明了其成因仍以岩浆成因为主。在云母类矿物的成因图解显示，研究区内大多数黑云母均位于C区，属壳源。     

韧性剪切带型金矿床矿物中熔融包裹体与矿床成因研究

在新疆乔尕山及广东河台韧性剪切带金矿床的含金石英脉及糜棱岩中首次发现熔融包裹体及流体一熔融包裹体，其均一化温度分别为780～960℃与600℃。用电子探针及扫描电镜能谱对熔融包裹体子矿物成分进行分析，通过56个熔融包裹体231个测点分析，鉴定出石英、白云母、黑云母、磁铁矿等十种子矿物，组成不同的矿物组合。子矿物常含Si、Al、Na、K、Au、Ag、Cu等元素。剪切带金矿床中熔融包裹体的发现为其成因研究提供了新依据，表明成矿与多阶段硅酸盐熔体及流体作用有关。     

新疆可可托海矿区小虎斯特91号脉中云母类矿物学特征与地质意义

以小虎斯特91号伟晶岩脉中的不同结构带及蚀变围岩、交代岩、锂云母细脉中云母矿物为研究对象,通过电子探针(EMPA)和激光剥蚀等离子体质谱(LA-ICP-MS)对各结构带不同产状的云母进行主微量成分分析.研究表明,91号脉从围岩蚀变带、伟晶岩边缘带、外侧带、中间带到核部带,依次发育黑云母、白云母、富锂白云母和锂云母,伟晶岩中云母类矿物显示由白云母向锂云母演化趋势.Li在白云母和富锂云母(锂白云母和锂云母)中的置换机制不同,分别可能为2SiⅣ+ LiⅥ(←→)3A1Tot和Si+Li(←→)AlTot+Fe (Zn,Mn,Mg)(白云母)和3LiⅥ(←→)AlⅥ+ 2□Ⅵ(富锂云母,□代表空位).小虎斯特91号伟晶岩脉经历了岩浆-热液的演化过程,随着演化进行,云母中K/Rb、Mg/Li比值显著降低,Li、Rb、Cs、F含量显著增大,指示分离结晶作用是晚期熔体相Li、Rb、Cs、F富集的主要机制.但云母类矿物的主、微量元素特征显示小虎斯特91号脉岩浆-热液过渡阶段特征不明显,伟晶岩演化很快由正岩浆阶段转化为热液阶段.     

湘南香花岭锡铅锌多金属矿田的云母类型及对成矿的指示

湘南癞子岭花岗质复式岩体是香花岭锡铅锌多金属矿田的主要成矿岩体,其中云母广泛出现在各期次岩（矿）体之中。笔者等在对癞子岭岩体岩相学研究的基础上,开展全岩主微量元素地球化学分析,同时对岩浆成因云母（花岗岩中的云母）、热液成因云母（矿化云英岩、晶洞矿物集合体以及条纹岩中的云母）进行了电子探针分析。结果表明,癞子岭岩体为一套高钾钙碱性—钾玄质、准铝质—过铝质花岗岩,癞子岭岩体中的云母主要为铁锂云母,从早期到晚期,呈现出FeO和Al2O3含量降低,K2O、F、MnO和Rb2O含量升高,且Pb、Zn、Fe等成矿元素含量逐渐增加的特征。热液成因云母分为以下两种： ① 产于矿化云英岩和晶洞矿物集合体中的云母主要形成于流体出溶的早期,无围岩组分参与,云母类型由铁锂云母演化为锂云母,主要沉淀Fe、Zn、Pb、Mo等成矿元素;② 产于条纹岩中的云母晚于矿化云英岩和晶洞矿物集合体中的云母,有围岩组分参与,云母类型由黑鳞云母变为富镁黑云母和富铁黑云母再变为金云母,主要沉淀Fe、Sn和W等成矿元素。随着流体演化,云母呈现SiO2、F、K2O含量逐渐降低,MgO含量逐渐升高,相应的成矿元素从富Fe 、Zn、Pb、Mo逐渐过渡到富Fe 、Sn和W。     

湘南香花岭锡铅锌多金属矿田的云母类型及对成矿的指示

湘南癞子岭花岗质复式岩体是香花岭锡铅锌多金属矿田的主要成矿岩体,其中云母广泛出现在各期次岩（矿）体之中。笔者等在对癞子岭岩体岩相学研究的基础上,开展全岩主微量元素地球化学分析,同时对岩浆成因云母（花岗岩中的云母）、热液成因云母（矿化云英岩、晶洞矿物集合体以及条纹岩中的云母）进行了电子探针分析。结果表明,癞子岭岩体为一套高钾钙碱性—钾玄质、准铝质—过铝质花岗岩,癞子岭岩体中的云母主要为铁锂云母,从早期到晚期,呈现出FeO和Al2O3含量降低,K2O、F、MnO和Rb2O含量升高,且Pb、Zn、Fe等成矿元素含量逐渐增加的特征。热液成因云母分为以下两种： ① 产于矿化云英岩和晶洞矿物集合体中的云母主要形成于流体出溶的早期,无围岩组分参与,云母类型由铁锂云母演化为锂云母,主要沉淀Fe、Zn、Pb、Mo等成矿元素;② 产于条纹岩中的云母晚于矿化云英岩和晶洞矿物集合体中的云母,有围岩组分参与,云母类型由黑鳞云母变为富镁黑云母和富铁黑云母再变为金云母,主要沉淀Fe、Sn和W等成矿元素。随着流体演化,云母呈现SiO2、F、K2O含量逐渐降低,MgO含量逐渐升高,相应的成矿元素从富Fe 、Zn、Pb、Mo逐渐过渡到富Fe 、Sn和W。     

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