稀土元素指标δCe－ΣREE对沉积相的指示研究

通过对内蒙古额济纳盆地小狐山剖面沉积物中酸溶组分稀土元素含量及其相关指标、分布模式的分析,讨论了剖面中稀土元素指标δCe－ΣREE与沉积相、沉积环境之间的关系。分析结果表明剖面沉积物酸溶组分中稀土元素丰度均值为7.24μg/g(不包括Y),其中LREE含量占稀土总量的88.67%; 且各层的稀土分布模式均为轻稀土适度富集缓右倾斜型、Eu呈负异常模式,但各相位地层的LREE富集程度与分配模式存在差异。由于小狐山剖面中沉积地层的自身岩性、沉积粒径、矿物结构组成以及气候环境变化等因素均可能会引起REE分异。因此,通过δCe－ΣREE图并结合三次回归曲线,可以很好地将不同沉积相得物质有效的区分开来。小狐山剖面除极少数的几个样品(水下沉积砂)之外,其余的均落在三次多项式回归曲线上部; 而风成砂层则几乎全部落在回归曲线之下; 此外,对于风沙－河流作用下的混合样品也有较好识别,河流过渡相的样品则分布在曲线上或与之相邻近。此研究结果得到了柴达木贝壳堤沉积物的REE数据的验证,运用此方法可以为直观的判别剖面中的不同沉积相,并为定量化划分地层提供依据。     

冀东南地区稀土元素演化特征及基准值研究

从冀东南地区系统采集了地表水(n=37)、地下水(n=31)、水系沉积物(n=81)、土壤(n=242)和岩石(n=472)的稀土样品,利用统计学和岩性岀露加权方法分别对14个稳定的稀土元素(REE)含量及各类稀土基准值和分布模式方面进行了研究。对岩石—土壤—水系沉积物—地下水和地表水系统中稀土元素迁移和分布模式的研究表明,随土壤的发育,REE出现富集,并出现分异,HREE比LREE更易在土壤中富集;Eu在岩石和土壤中由负异常到地下水和地表水的正异常演化特征。地表水和地下水中REE的含量和分布模式相近。     

南黄海中部泥质沉积区DLC70-3孔稀土元素及环境意义

通过对南黄海中部泥质区北缘DLC70-3孔沉积物全岩组分的∑REE、分布模式和分异参数及其他地球化学相关指标的分析,讨论了沉积物物源以及ω(∑REE)变化的控制因素.分析结果表明DLC70-3孔沉积物稀土元素上陆壳标准化分布模式均为轻稀土元素适度富集缓右倾斜型、Eu呈负异常模式,与现代黄河沉积物的分布模式一致;[ω( ...     

宝应钻孔沉积物的微量元素地球化学特征及沉积环境探讨

沉积物微量元素特征对指示沉积盆地演化历史、沉积环境及沉积物的物质来源具有十分重要的示踪作用.宝应沉积物的微量和稀土元素地球化学特征印证了苏北平原物质来源具有多源性,与黄河、长江具有类似的物源,并可能受基底碱性火山岩和黄土高原粉尘物质的影响.钻孔沉积物具有轻稀土适度富集、缓右倾斜型的稀土元素配分模式,呈现Ce正异常的总体特征; 海侵段的稀土含量比陆相沉积段略低.δEu在陆相沉积中为1.16,呈微小的正异常; 在海侵沉积中为0.99,基本不显示异常.稀土元素含量与沉积物粒度之间存在一定相关性:随着粒度由粗变细,稀土元素含量增加; ΣREE的高值段对应粘土含量较高,反之亦然.沉积物REE及Rb/Sr比值的纵向变化反映了海陆交互过渡带古气候环境的波动:ΣREE的高值段与δEu和δCe的低值段代表了冷湿的气候环境; ΣREE和δCe的低值与δEu的高值段反映了暖湿润的环境信息.结合地貌、岩性及微体古生物,综合分析表明苏北平原在第四纪曾遭受了多次海水淹覆, 海-陆交互堆积作用明显,从古海湾逐渐发育堆积最后由河流冲积物覆盖成陆.     

大同盆地沉积物REE分布特征及其对碘富集的指示

大同盆地是典型的干旱-半干旱内陆盆地,盆地中部地下水碘含量异常,对当地饮用水安全造成了严重威胁.对盆地高碘地下水分布区沉积物组成及稀土元素(REE) 进行了地球化学研究,结果表明,地下水系统呈弱碱性(pH值为7.18~9.64) 的偏还原环境,沉积物多为Ce正常或轻微负异常及Eu负异常;沉积物中碘含量为0~1.78×10-6;ΣREE含量较高,ΣLREE/ΣHREE比值为2.79~4.14,即富集轻稀土元素(LREE) 而亏损重稀土元素(HREE).ΣREE与碘含量呈负相关关系,虽然铁氧化物/氢氧化物矿物的还原性溶解可导致二者的释放,但由于沉积物有机质产生的低结晶矿物对碘的强吸附性,使沉积物中碘含量较高;弱碱性环境中REE的再吸附过程会导致沉积物中富集LREE;沉积物中碘含量与氧化还原敏感组分TOC、U、V及[Eu]_N的关系也表明,地下水系统的氧化还原条件及有机质含量是影响碘富集的重要因素.      

河流稀土元素地球化学研究进展

河流系统中,稀土元素(REE)受区域地质背景、风化作用、溶液化学以及水与颗粒物相互作用等因素的影响发生分异。河流悬浮物显示轻稀土(LREE)适度富集;河水显示重稀土(HREE)富集,或在HREE富集的基础上又有适度的中稀土(MREE)富集;与其它微量元素相比,REE在河水与颗粒物之间有较小的分配系数(K≈10-6);河流沉积物多显示平坦的REE配分模式。     

北部湾东部海域表层沉积物稀土元素组成及物源指示意义

对北部湾东部海域70个表层沉积物样品的稀土元素(REE)分析结果表明,研究区沉积物 REE 呈现轻稀土元素(LREE)富集、重稀土元素(HREE)平坦以及中等程度的 Eu 异常等特征.REE 组成受沉积物粒度和生物碳酸盐含量的制约,具有典型风化上陆壳 REE 特征,其源岩以上陆壳的长英质岩石为主.根据研究区沉积物 REE 分布规律,研究区可划分为4个地球化学分区,各区域上陆壳标准化曲线明显的不同.物源判别显示研究区的西部、海南岛西南侧(Ⅰ区)呈多源沉积特征,来自以下几个物源区:(1)海南岛西南侧河流沉积物和沿岸侵蚀物;(2)由南向北输入的外海沉积物(冬季);(3)夏季或冬季由北部湾西北部和西部搬运来的沉积物.研究区中部粗粒沉积区(Ⅱ区)与北部湾西部沉积物来源是相同的,主要来源于红河输砂.东北部砂质区(Ⅲ区)沉积物可能来源于雷州半岛西北部近岸基岩侵蚀.研究区东北部(Ⅳ区)沉积物主要来自北部湾北部沿岸侵蚀、琼州海峡和雷州半岛西部的沿岸侵蚀.此外,部分沉积物还可能来自珠江流域以及南海北部陆架区和北部湾西北部     

太平洋中部锰结核的稀土元素

太平洋中部CP区和CC区锰结核中含有丰富的稀土元素。CP区结核较CC区结核富含REE,海山区结核较平原丘陵区结核富含REE。结核内部REE呈带状分布。结核和沉积物的稀土分布模式相同,与海水的模式曲线为镜像关系。三价稀土元素自海水进入结核时没有产生明显分异。造成结核和沉积物中REE丰度差别的主要原因是氧化还原条件。太平洋地区洋底的氧化还原强度主要受南极底流控制。结核中含铁相是REE的主要富集场所。     

西太平洋暖池近3万年来的沉积序列及其环境特征-WP92-3柱样的REE记录

WP92-3柱样采自西太平洋暖池核心区。利用稀土元素(REE)特征参数研究了该柱样的沉积物来源和地层序列划分,并对其所揭示的环境变化特征进行了探讨。研究认为:样品的REE分布模式揭示了该海域的沉积物源主要为海相自生沉积;基于REE指标的垂向深度变化特征可将该柱样划分为3个地层序列;∑REE,LREE/HREE和δCe几个指标对环境的温度变化以及地磁场的极性变换均有良好的响应,∑REE高值段基本对应于δ18O和SST所揭示的暖池低温期,而地磁场极性转变的时间正好对应着稀土指标(∑REE,LREE/HREE和δCe)快速大幅波动的层位。REE特征参数较好地记录了暖池区近3万年来的沉积和环境变化信息,是一组对气候环境演化具有潜在良好指示作用的地球化学指标。     

淮北花沟西井田煤中微量元素及其环境意义分析

通过对30件煤样微量元素含量的测定,分煤层、分类型(稀土元素、环境意义微量元素)讨论了煤中微量元素的分布特征。研究发现各样品的稀土元素主要赋存于矿物质中,稀土元素含量均呈正常质量分数水平分布,各煤层的稀土元素分布表现为轻稀土富集、重稀土亏损。受陆源影响的煤,ΣREE含量高,稀土元素主要由陆源物质继承而来。受海水影响的煤,ΣREE含量低,分布模式具有海水性质。形成后受河流冲刷的煤,灰分增加,煤中稀土元素含量增加。该研究成果为煤炭资源的合理开发和利用提供基础资料。     

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