广西岑溪糯垌稀土矿床地质特征及成矿规律

文章阐述了岑溪糯垌稀土矿床地质特征及其矿石特征、矿石有用组分含量及变化规律、矿石化学成分、矿石浸取率及稀土元素配分类型等,认为岑溪糯垌稀土矿床属黑云钾长(二长)花岗岩风化壳离子吸附型稀土矿床,稀土元素配分类型为低铕富镧钕轻稀土型,矿层主要赋存于花岗岩全风化层中。     

滇西盈江地区新泡山离子吸附型稀土矿床成矿条件及找矿前景

滇西盈江地区是近年来离子吸附型稀土矿床找矿突破较大的地区,典型代表为腾冲岩浆弧内新发现的新泡山稀土矿床,为一中型离子吸附型稀土矿床,是滇西高海拔地区新发现的典型矿床。新泡山稀土矿床的发现对今后高海拔地区的找矿工作具有重要的示范意义。通过对新泡山稀土矿床的地质特征、风化壳结构特征、矿体垂向变化特征进行研究,认为新泡山稀土矿床类型为富钕轻稀土离子吸附型稀土矿床,并伴生有重稀土钇。滇西盈江地区与花岗岩有关的离子吸附型稀土矿主要受控于母岩稀土元素丰度、气候以及地形地貌。"沟-谷-盆"地貌两侧及周缘低缓山丘和平缓山坡、山脊是有利的成矿部位。结合区域找矿成果,认为研究区稀土矿找矿潜力较大,可达超大型远景规模,在后续的找矿工作中应加强对重稀土元素钇的评价。     

滇西陇川营盘山离子吸附型稀土矿稀土元素分布特征

滇西陇川地区广泛分布着白垩纪至古近纪中酸性花岗岩,以邦棍尖山为代表的岩体花岗岩稀土含量较高,经复杂的风化淋滤作用,岩体中的稀土元素在风化壳中迁移、富集成矿,陇川营盘山稀土矿即为近年新发现的该类型矿产地之一。为研究新发现的营盘山稀土矿稀土元素分布特征、富集规律及稀土配分特征,利用电感耦合等离子体质谱仪(ICP-MS)分析成矿母岩及其风化壳不同风化程度样品稀土分量,结果表明:风化壳各层位稀土元素分布特征相比母岩具有明显的继承性,随风化程度升高,轻重稀土分馏程度升高,轻稀土在全风化层上部相对富集,且随风化程度升高轻稀土富集程度升高,而重稀土的富集程度则逐渐减弱,Gd是风化壳富集能力最强的元素,Dy富集能力最弱,Ce富集在近地表,重稀土具有更强的向下迁移能力。同时,研究发现该稀土矿床的稀土配分特征为低钇、铕,富镧、铈、钕。     

龙南上黄湾稀土矿地质特征及成矿条件分析

龙南县是首次发现花岗岩风化壳离子吸附型稀土矿的地区,具有丰富的稀土资源。通过对龙南上黄湾稀土矿成矿内生与外生地质条件进行系统的分析研究,结果显示该稀土矿床的形成与燕山期的高稀土含量(达406.65×10~(-6))的中细粒黑云母花岗岩有关,母岩的稀土配分模式为低钇低铕轻稀土配分型,在特定的构造位置和温暖潮湿气候条件下,含矿母岩经风化淋滤作用后,在花岗岩全风化层中富集形成轻稀土矿床。     

滇西临沧花岗岩中段离子吸附型稀土矿成矿特征研究

滇西临沧花岗岩中段岩性主体为黑云母二长花岗岩,是离子吸附型稀土矿的天然成矿母岩。研究区湿热的气候使得在地势相对平缓的中山地区形成巨厚的花岗岩风化带,依据风化程度由地表至基岩依次分为腐殖土层、亚黏土层、全风化层、半风化层、弱风化层和新鲜基岩。全风化层是本区离子吸附型稀土矿的主要赋矿层位,该层位元素地球化学特征显示,经过风化后稀土元素发生了富集和分馏,稀土矿化是以轻稀土为主。轻稀土又以La和Ce这两种元素为主。依据本区不同地貌类型建立了倾缓的山脊、平缓的山顶和低缓的山丘3种离子吸附型稀土矿成矿模式。     

广西钟山县花山矿区南矿段稀土矿矿石品质特征分析

花山矿区南矿段稀土矿矿石为中低品位为主的花岗岩风化壳离子吸附型稀土矿石,属于轻稀土富集型,且Eu具有明显的负异常,其稀土配分特征表现出了与原岩的明显继承性。花岗岩原岩风化程度越高,风化壳厚度越大,矿层的品质就越好,浸取率也相应增高。全风化层是稀土矿的主要赋矿层位,全风化层的顶部稀土氧化物含量不高,稀土元素主要富集在全风化层的中下部。矿体轻重稀土的比值由地表向下,比值降低,即表现出明显的矿层上部富集轻稀土,下部富集重稀土。     

盈江县旧城地区离子吸附型稀土矿特征及控矿条件

云南盈江旧城地区地处滇西亚热带温热环境,出露了大面积的稀土元素背景值较高的古近纪二长花岗岩体,岩体经过长期的表生成矿作用,形成了多处风化壳离子吸附型稀土矿.通过实施的取样钻、槽探等工程控制,可以看出盈江地区的稀土矿体,主要赋存于古近纪花岗岩体风化壳底部之半风化层上部,矿化分布较广泛,其潜在资源远景规模达大型或超大型.     

广西新联稀土矿区莲塘花岗岩的地质地球化学特征及成矿意义

新联稀土矿区莲塘花岗岩体形成于中侏罗纪,属于燕山期岩浆岩。该花岗岩体富Si、Na、K、Hf,贫Fe、Mg、Ca、P、Ni、Co、Cu、Zr、Sr、Ba、Ta,为过铝质高钾钙碱性系列S-I过渡型花岗岩;稀土总量的平均值为185.39×10-6,高于中国花岗岩均值147.80×10-6。轻重稀土的平均比值为6.75,表现为富集轻稀土。该花岗岩体的风化壳发育,由于风化程度不同,造成稀土元素的富集程度存在较大的差异。稀土矿层主要以离子吸附形式赋存于花岗岩全风化层中部及半风化层上部。该区稀土矿化与高丰度稀土含量的岩体、低山丘陵地貌条件及气候、风化壳保存程度等影响因素密切相关。     

广东惠东地区离子吸附型稀土矿床地球化学特征

摘要：运用岩石地球化学方法,对广东惠东地区离子吸附型稀土矿床的地球化学特征进行研究。结果显示,风化壳中元素含量及配分特点总体上取决于母岩,但稀土元素在继承母岩稀土元素的基础上含量进一步富集,且各风化层中元素含量变化与风化作用之间具有一定相关性。WIG指数相较于CIA指数能更有效地描述风化壳风化强度,风化壳中稀土元素迁出富集与WIG指数及元素迁移系数具有一定规律性,轻稀土元素多在全风化层上部富集,而重稀土元素在全风化层下部及半风化层明显迁入富集,Ce、Eu均具明显负异常。     

云南建水普雄铌稀土矿床微量和稀土元素地球化学特征

云南建水普雄铌稀土矿床是近年来发现的一处大型铌稀土多金属矿床,产于霞石正长岩和碱性正长岩组成的长岭岗碱性岩体的风化壳中,累计探明铌资源量超过5.7×10~7 kg,总稀土资源量超过47×10~7kg。目前,对该矿床的研究主要集中在矿物学特征和找矿勘查技术上,在矿床地球化学研究方面,仅限于部分成矿元素(如铌和稀土等)的基本分析上。本次工作在深入的野外观测基础上,对具有代表性的12号勘探线64号钻孔进行了系统取样(24件)和高精度微量、稀土元素含量分析。结果显示,微量元素与上地壳元素平均含量相比,全部样品Li、Ga、Nb、Sb、Cs、Pb、Th和U等有不同程度富集;稀土元素相对球粒陨石也均有不同程度富集,但稀土总量变化范围较大,总体上表现为全风化层样品(∑REE介于1046×10~(-6)～9154×10~(-6))高于粘土层(630×10~(-6))和半风化层样品(163×10~(-6)～1369×10~(-6)),表明成岩作用和风化过程导致了这些元素的不同程度富集。此外,全部样品的轻稀土总量和重稀土总量比值较大,轻稀土元素和重稀土元素间分异明显,∑LREE/∑HREE=20～58,(La/Yb)N=25～143,轻稀土元素内部分异((La/Sm)N=11～26)较重稀土元素内部分异明显((Gd/Yb)N=1～6),表明稀土元素发生了不同程度分异和富集。全部样品Eu负异常明显(δEu=0.5～0.7),Ce异常显著,正、负异常均有(δCe=0.1～3.8),表明成岩作用和风化过程没有导致Eu异常改变,但对Ce异常产生了显著影响。综上,普雄铌稀土矿床富集多种三稀(稀有、稀土和稀散)元素,成岩作用和风化过程共同导致了三稀元素不同程度分异和富集。     

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