北部湾东部沉积物结构和碳酸盐含量变化对末次海侵和环流作用的响应

为了揭示末次冰消期以来北部湾东部沉积环境的整体变化,深入认识环流对北部湾沉积的控制作用,对位于北部湾东部的15只柱样进行了粒度、碳酸盐含量和C/N分析,并测定了其中11只柱样的AMS14 C年代.结果表明,在末次冰消期随海平面上升,北部湾沉积环境由陆向海转变,沉积物碳酸盐含量总体递增,而C/N值则递减,其间伴随发生于全新世早期的碳酸盐低值事件,在北部湾深水区的柱样中也有记录.全新世中期海平面基本稳定以后,稳定的C/N数值表示有机质来源趋于稳定,而碳酸盐含量受钙质生物生产力不同(南高北低)和陆源输入的区域性差异影响出现不同变化.与C/N分析结合,碳酸盐含量曲线可用于地层划分与对比.北部湾环流可能形成于7ka BP左右,影响了沉积物的输运与沉积.全新世中晚期沉积厚度存在区域差异,海南岛西侧大于2.0m,湾顶多介于0.8~2.0m,而涠洲岛西南海域厚度相对最小,可能与湾北物质难以向南输运,而湾南物质主要在琼州海峡西口外卸载有关.     

广西涠洲岛全新世上升海滩沉积及其成岩作用

涠洲岛是广西北部湾中的一个火山岛,该岛由第四纪喜山期的喷出岩,主要是玄武岩和火山碎屑岩、凝灰质砂岩等所构成。岛的北部、西部和东部沿岸多处发育有珊瑚岸礁,它们是向海岸地带供应大量各种生物骨壳碎屑的物源区。在海滩地带相应地发育了以生物砂、砾屑为主的海滩沉积。所观察的岛北部和西部的全新世海滩沉积(与海南岛类似的沉积岩层比较,推断可能属全新世)由于海平面下降而处于     

南海北部湾全新世以来沉积物地球化学特征及物源分析

为探讨全新世以来南海北部湾沉积物的沉积环境变化,对北部湾海域的SO-31沉积物柱状样进行了元素地球化学分析。根据元素地球化学的垂向分布特征,将SO-31沉积柱划分为3个单元,反映了全新世不同时期的区域海平面波动以及沉积物物源的变化。SO-31沉积柱的稀土元素配分曲线和La/Co与La/Sc散点图分析表明:111 400~12 800 a BP(全新世前期),研究区海平面较低,红河、其他周边河流及海岸侵蚀物均为本区的主要物源;28 500~1 1400 a BP(全新世早期),随着海平面的逐渐上升,河口和岸线逐渐后退,各物源供给区对本区沉积物的贡献量也发生了相应变化,相对而言红河贡献率有所下降;30~8 500 a BP(中全新世至今),区域海平面持续上升导致了琼州海峡打开,北部湾水动力环境和物源供给发生了剧变,红河对本区的物源贡献逐渐变小,而来自北部湾东部的物质成为本区沉积物的主要物源。     

泛巽他盆山体系北部湾古泥沼旋回与古生态效应

南海西北部北部湾在地质环境方面与狭义巽他陆架相似而成为一体构成泛巽他,同属青藏高原及其挤出阶梯地貌盆山体系。然而,关于其指示环境变化和碳循环的古泥沼分布及其气候-构造驱动机制、作用与联系等缺乏关注,其研究滞后于上述热点巽他陆架相关进展。为加强对这些内容的认识,本文的研究在北部湾北部华南陆缘沉降带进行了80.05 m进尺第四系全岩心钻取,立足于沉积物微体古生物、粒度、碎屑矿物组分、微量元素含量等基础沉积环境指标的实验测试、鉴定以及测年数据,并结合前人相关资料和结果进行综合分析。结果表明,岩心底部年龄为中更新世后期171.0 ka,孢粉化石呈热带和亚热带植被面貌,主要有栲属、栎属等以及鳞盖蕨属、水龙骨科等,其含量变化显示出3个主要气候变化阶段,与倒数第二冰盛期、末次间冰期、末次冰期以及冰消期等相联系,从56.0 ka始见有半咸水种硅藻化石条纹小环藻、柱状小环藻等,有孔虫化石出现于中全新世6.0 ka接受海进。总体上以砂为主,但局部粉砂和黏土(泥)含量较高,最高依次可达65.78%、59.71%,元素含量为2.6×10^-6～347×10^-6,碎屑矿...     

北部湾全新世海侵演进及其与气候、冰川关系分析

北部湾是我国热带和亚热带大型海湾且资源丰富,了解其演进变化过程是环境保护、利用和预测的基础;在接近湾口的南部海盆进行了岩芯钻取,并对样品进行较高分辨率地球化学元素Sr、Ba和微体古生物化石测试、鉴定和14C测年.分析对比结果表明,微体古生物化石丰富,有孔虫共有42属67种,主要为表层暖水种和近岸浅海种,硅藻有19属29...     

北部湾东南部末次冰期以来环境演化与驱动机制

应用单道浅层地震、等离子体质谱仪（ICP-MS）和X射线衍射（XRD）等测试技术对地层结构及主微量元素地球化学、黏土矿物组成和结晶学特征等气候代用指标进行分析，高精度刻画了北部湾东南部末次间冰期以来的气候演化及驱动机制。指标变化显示南海西北部75千年（75 ka）以来物源供给受气候及海平面变化的协同控制。晚更新世受海因里希（Heinrich）全球气候变冷事件及青藏高原巨大高度和纬度效应的调控导致56 ka、41 ka和28 ka东亚季风的冬季风较夏季风阶段性增强，步入全新世以来，北部湾东南部历经多次干湿交替性升温过程，逐步演化到现今气候阶段。     

近3000cal.aB.P.以来东海东北部环境异常及其与全新世ElNio活动的可能联系

利用取自东海东北部、冲绳海槽西侧陆坡的重力柱状岩芯DOC082(29°13.93′N,128°08.53′E;水深1128m),通过对碳酸钙、有机碳和蛋白石等生源组分含量的分析,结合浮游有孔虫、底栖有孔虫、放射虫和硅鞭藻等微体古生物化石丰度的变化以及底栖有孔虫属种组成特征,揭示了全新世东海东北部生物生产力的演变。研究结果显示,近10500cal.aB.P.以来生源组分含量和微体古生物化石丰度的演变趋势十分相似,明显分为3个阶段:约4000cal.aB.P.之前的早、中全新世明显偏低,大约在4000cal.aB.P.左右开始突然大幅度上升,而约3000cal.aB.P.以来的晚全新世以持续的高值为显著特征。生源组分含量、微体古生物化石丰度以及底栖有孔虫内生属种Uvigerina和Bulimina百分含量等指标的变化一致指示,东海东北部近10500cal.aB.P.以来古生产力演变的显著特征是早、中全新世明显偏低,约4000cal.aB.P.左右突然且大幅度上升,大约3000cal.aB.P.之后的晚全新世为生物生产力异常的高值期;同时有研究表明该区域的表层海水年平均温度(SST)也呈现了明显的三段式演变:早全新世10500~8400cal.aB.P.期间为持续的高值期、中全新世SST相对稳定、3100~500cal.aB.P.期间的晚全新世为显著的低SST时期[1]。近3000cal.aB.P.以来古生产力的异常高值和表层海水古温度的大幅度下降说明晚全新世区域海洋环境发生了明显的改变。据东海东北部现代生物生产力和表层海水温度的分布特征和控制机制、结合现代ElNio发生期间中国大陆气候和降水异常以及黑潮暖流变异的分析表明,近3000cal.aB.P.来东海东北部的环境异常可能是对晚全新世ElNio活动显著增强的反应。     

殷墟文化发生的环境背景及人类活动的影响

不同农业单元122个表土样品花粉分析结果表明,安阳地区表土花粉组合中草本植物花粉含量最高,以禾本科、蒿属、藜科和十字花科为主,乔木植物花粉百分含量较低,以松属、桦属、胡桃属、黄栌属、栎属为主,应为西部太行山区传播而来。汪家店和茶店陂两个全新世地层自然剖面孢粉分析表明,约 10000cal.aB.P.以前,安阳地区分布着以松属、栎属、桦属等为主的落叶阔叶林;  约 10000～8200cal.aB.P.,气候变暖,降水量增加,森林植被中夹杂着常绿栎等亚热带树种;  约 8200～3400cal.aB.P.,安阳地区进入全新世大暖期,森林植被演变为亚热带落叶阔叶和常绿阔叶混交林;  商王朝在安阳地区建都后（3400cal.aB.P.后）,乔木植物花粉急剧减少,草本植物花粉和中华卷柏百分含量升高,表明森林被大量砍伐,砍伐后的林地开垦为农田,主要种植禾本科等农作物;  两条剖面上部的冲积层中出现大量中华卷柏孢子,表明森林植被破坏后水土流失加剧。古地貌面孢粉分析也证明殷商时期安阳地区生长有亚热带落叶阔叶和常绿阔叶混交林,气候和植被条件适于野象生存;  殷墟附近为禾本科农作物花粉高含量区,表明殷商时期农业已具一定规模。     

长江下游巢湖9870cal.aB.P.以来孢粉记录的环境演变

根据对巢湖490cm湖泊沉积物柱样7个AMS¹⁴C年龄的测定以及98个孢粉样品的分析,植物种类分属于86个（科）属,可以划分为6个孢粉组合带:孢粉带Ⅰ（9870～6040cal.aB.P.）代表了末次冰期之后全新世温暖气候到来之前气候转暖的早全新世过渡时期,气候呈现温和略干的特点,其中亚带Ⅰ-1（9870～7700cal.aB.P.）,Ⅰ-2（7700～6250cal.aB.P.）和Ⅰ-3（6250～6040cal.aB.P.）分别对应温暖湿润→温暖较湿→温和干燥的气候波动;孢粉带Ⅱ（6040～4860cal.aB.P.）代表中全新世温暖湿润期,水热配置条件最佳;孢粉带Ⅲ（4860～2170cal.aB.P.）体现中全新世后期温和干燥的气候,约2170cal.aB.P.干旱程度达到最高;孢粉带Ⅳ（2170～1040cal.aB.P.）反映巢湖流域由干燥向湿润气候的转型,气候总体上温和湿润;孢粉带Ⅴ（1040～200cal.aB.P.）反映了晚全新世巢湖流域温凉稍湿的气候;孢粉带Ⅵ（200cal.aB.P.至今）则体现巢湖流域处在相对温暖湿润的时期。植被类型演替大体为:以壳斗科的落叶、常绿属种为主的落叶阔叶、常绿阔叶混交林→以落叶栎类、栗属、青冈属和栲/石栎属为主的落叶阔叶、常绿阔叶混交林→以落叶栎类占绝对优势的落叶阔叶、常绿阔叶混交林→以禾本科为主的草地→以禾本科、蒿属和蓼属等为主的草丛。     

近3000cal.aB.P.以来东海东北部环境异常及其与全新世ElNiño活动的可能联系

利用取自东海东北部、冲绳海槽西侧陆坡的重力柱状岩芯DOC082（29°13.93′N,128°08.53′E;水深1128m）,通过对碳酸钙、有机碳和蛋白石等生源组分含量的分析,结合浮游有孔虫、底栖有孔虫、放射虫和硅鞭藻等微体古生物化石丰度的变化以及底栖有孔虫属种组成特征,揭示了全新世东海东北部生物生产力的演变。研究结果显示,近10500cal.aB.P.以来生源组分含量和微体古生物化石丰度的演变趋势十分相似,明显分为3个阶段:约4000cal.aB.P.之前的早、中全新世明显偏低,大约在4000cal.aB.P.左右开始突然大幅度上升,而约3000cal.aB.P.以来的晚全新世以持续的高值为显著特征。生源组分含量、微体古生物化石丰度以及底栖有孔虫内生属种Uvigerina和Bulimina百分含量等指标的变化一致指示,东海东北部近10500cal.aB.P.以来古生产力演变的显著特征是早、中全新世明显偏低,约4000cal.aB.P.左右突然且大幅度上升,大约3000cal.aB.P.之后的晚全新世为生物生产力异常的高值期;同时有研究表明该区域的表层海水年平均温度（SST）也呈现了明显的三段式演变:早全新世10500～8400cal.aB.P.期间为持续的高值期、中全新世SST相对稳定、3100～500cal.aB.P.期间的晚全新世为显著的低SST时期[1]。近3000cal.aB.P.以来古生产力的异常高值和表层海水古温度的大幅度下降说明晚全新世区域海洋环境发生了明显的改变。据东海东北部现代生物生产力和表层海水温度的分布特征和控制机制、结合现代ElNio发生期间中国大陆气候和降水异常以及黑潮暖流变异的分析表明,近3000cal.aB.P.来东海东北部的环境异常可能是对晚全新世ElNio活动显著增强的反应。     

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.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

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.)