中晚全新世科尔沁沙地沉积物化学特征及其气候变化

科尔沁沙地位于我国沙漠-黄土边界带和北方农牧交错带,深受东亚季风的影响,对全球气候变化反应非常敏感,是研究全球气候变化的理想区域。TL剖面磁化率、粒度和地球化学元素氧化物及其比值变化分析表明:中晚全新世研究区气候极不稳定,可以大致划分为:① 6.0～4.2 ka BP,气候暖湿,夏季风逐渐增强,并占据主导,冬季风较弱,与全新世大暖期对应,但存在百年尺度的气候波动,其中:6.0～5.6 ka BP,5.5～5.4 ka BP,4.9～4.7 ka BP,4.5～4.2 ka BP气候暖湿;5.6～5.5 ka BP,5.4～4.9 ka BP,4.7～4.5 ka BP气候相对冷干。② 4.2～1.3 ka BP,气候相对暖湿,与上一阶段相比夏季风有所减弱,其间也存在次一级波动,4.2～3.63 ka BP,3.57～3.4 ka BP气候相对干冷;3.63～3.57 ka BP,3.4～1.3 ka BP,气候相对暖湿。③ 1.3～0.65 ka BP以来,气候波动频繁,后期有向暖湿发展的趋势。这些气候变化与区域和全球变化具有良好的对应关系,反映该区气候变化与全球气候变化具有高度一致性。     

鄱阳湖地区晚更新世古环境变迁

晚更新世期间鄱阳湖北部地区,九江、湖口、彭泽一带发育风沙-黄土-湖沼相交互地层序列。本文通过对该序列5个露头剖面多环境代用指标分析,研究了该地区晚更新世环境变迁和季风变化过程。研究表明:约147-129.6kaBP,以较强的冬季风控制的气候为主,季风降水很少,气候偏冷干;129.6-76kaBP,早期,夏季风逐渐增强,至120kaBP后,夏季风进入强盛阶段,103kaBP后,夏季风较弱,97kaBP后,夏季风又一次增强,这一时段内古气候阶段性非常清楚,早中期暖湿程度较高,后期较弱,在暖湿的背景上存在110-106、103-92kaBP等冷事件;76-55kaBP,为强盛的冬季风时期,气候冷干;55-25kaBP,夏季风又一次增强,气候温暖湿润,中间有冷波动;25-16kaBP,气候变冷干,后期冬季风有所减弱;16kaBP后,夏季风明显增强,气候变温湿,13.0kaBP后,气候有变干的趋势.      

三门峡地区末次盛冰期至全新世早期的古季风事件

通过三门峡地区小刘寺剖面黄土- 古土壤序列磁化率曲线和粗颗粒组分含量曲线的研究,发现它们分别指示的夏季风和冬季风变迁在末次冰消期向全新世转变时的新仙女木事件中显示不同的变化特征。夏季风的加强过程对应于冬季风的大幅度波动,气候为凉湿背景上的冷湿与暖湿振荡。冰后期的早期为全新世第一暧期。夏季风强盛对应于冬季风衰弱的湿暖气候,它由夏季风锋面降水的穿时性所决定,在华北地区为全新世适宜期。8 kaBP 前后为夏季风偏弱对应于冬季风偏强的干冷气候,是具有普遍意义的全新世第一冷期。这3 次古季风事件可与格陵兰冰芯记录进     

青藏高原东北缘共和-贵德盆地全新世气候变化

青藏高原东北缘地处现代亚洲季风影响的北界和中国干旱与半干旱气候的过渡地带,沉积物对气候变化敏感,是研究全新世高原冬夏季风系统对全球变化响应的理想地点。笔者根据粉尘搬运的动力学原理,利用温湿度组合、风力强度变化和粉尘源区收扩演变特点,分析了共和-贵德盆地全新世气候波动、区域环境变化以及冬夏季风关系等,主要取得了以下认识:(1)建立了大气粉尘的风力强度指数、粉尘搬运距离指数、大气湍流强度指数、春季近地面气温指数和有效湿度指数等估算方法。(2)全新世时期西南季风是影响共和-贵德盆地的主要夏季风系统,高原冬季风则是影响这个地区的主要冬季风,共和-贵德盆地近地面具有不同的风场演化模式。(3)共和-贵德盆地的全新世气候变化可划分为4个阶段:1大约6.5~4.2kaBP的全新世适宜期以湿度大幅增加、温度小幅升高的暖湿为特点。2在2.6~4.2kaBP期间出现了一次以冷干为特点、粉尘源区扩张、冬夏季风均减弱的环境恶化事件,这次恶化事件在高原季风系统的西北粉尘源区和亚洲季风系统的北方粉尘源区都同样存在。3大约1.2~2.6kaBP时期,粉尘源区收缩、环境好转,推测是夏季风小幅加强的时期。41.2kaBP以后,湿度增加、成壤强度先强后弱,总体环境趋于冷湿。     

西安何家营全新世黄土磁化率的古气候环境

探讨西安地区全新世以来古气候环境的变化规律,通过西安何家营村全新世黄土剖面的地层岩性描述,运用磁化率年龄模型确定地层年代序列,根据所采样品的磁化率值绘制磁化率曲线来分析全新世气候变化。同时选取其他学者所建立的气候曲线进行对比,将西安地区全新世气候分为5分阶段：10～8．5kaBP,冷暖转换阶段;8．5～7kaBP,大暖期冷暖波动阶段;7～5kaBP,大暖期鼎盛阶段;5～3．4kaBP,大暖期温度波动暖和阶段;3．4kaBP至今,气温先下降后稳定阶段。     

11.5kaBP以来尕海沉积物氧化物地球化学特征及其环境意义

通过对柴达木盆地尕海DG03孔沉积序列的年代学测定和沉积物分析,选取对气候环境较为敏感的SiO2,Al2O3,TiO2,Fe2O3,MgO,ＣaO,K2O,Na2O等作为环境代用指标,分析了尕海地区11.5 kaBP以来的气候环境变化。研究表明尕海地区在11.5 kaBP以来存在4个明显的气候变化期:晚冰期晚期（11.5～10.16 kaBP）的气候波动较大,其中11.5～11.16 kaBP是暖干气候;11.16～10.16 kaBP,气候冷干,可能是新仙女木事件的反映;全新世早期（10.16～7.83 kaBP）气候转暖,有短期极干冷事件的发生;中全新世适宜期（7.83～4.73 kaBP）,气候温暖湿润;4.73 kaBP以来的全新世晚期,气候环境明显恶化,期间出现气候暖湿与干冷的多次波动变化。     

青藏高原东北部风成沉积微量元素揭示的全新世千年尺度气候变化*

通过对青藏高原东北部共和盆地典型古土壤—风成砂剖面的释光（OSL）年代测定和沉积物中微量元素的分析,重建了区域全新世千年尺度的气候变化过程。研究表明,除Co、Rb、Sr和Ba以外的12种微量元素所反映的气候变化规律较显著,其含量变化曲线上的峰值段对应于古土壤层而谷值段对应于风成砂层,这一现象可作为气候暖湿、冷干波动的标志;区域全新世气候变化可分为以下阶段：11.8～10.0 ka气候寒冷干燥,10.0～9.2 ka气候逐渐趋于暖湿,9.2～4.6 ka气候相对冷干,4.6～0.7 ka气候相对暖湿,0.7 ka以来气候明显寒冷干燥;区域全新世气候变化中存在8次寒冷事件,与青藏高原和北大西洋揭示的寒冷期具有明显的对应关系,表明共和盆地千年尺度的气候变化与全球气候变化具有一致性。     

台湾头社盆地湖沼相沉积孢粉记录的6.2~1.3 cal ka BP以来气候研究

头社盆地位于中国台湾省中部,东亚季风区的最前沿,对东亚季风的响应十分敏感,研究其中晚全新世以来古植被、重建古气候序列,探讨其气候与东亚夏季风的关系具有重要的科学意义。文章对头社盆地泥炭—湖泊沉积的AMS14C测年、体积磁化率测试的基础上,基于孢粉记录,重建晚全新世来植被变化,恢复古气候。结果表明全新世中晚期以来分六个阶段：6.2~6.0 cal ka BP,气候凉干,植被类型是亚热带常绿阔叶林;6.0~4.0 cal ka BP,气候转暖湿,植被类型为含较多热带成分的亚热带常绿阔叶林;4.0~2.2 cal ka BP,气候相对凉干,植被类型转为亚热带常绿阔叶林;2.2~1.9 cal ka BP,气候又变暖湿;1.9~1.7 cal ka BP,气候快速冷干事件,森林退化;1.7~1.3 cal ka BP,气候重转温暖湿润,植被类型为接近现代的沼泽草原。整体上6.2~2.2 cal ka BP的气候变化是由温暖湿润向温凉干燥转变的趋势,这是全新世中晚期以来的太阳辐射量减少所导致的,太阳辐射量的减少导致热带辐合南移,进而导致东亚夏季风减弱,而2.2 cal ka BP之后气候波动较大,可能是在东亚夏季风减弱的背景下,ENSO活动加强与人类活动的干扰下耦合的结果。     

青藏高原昆仑山垭口盆地晚上新世以来沉积物磁化率与气候变化

通过对青藏高原昆仑山垭口盆地磁化率、频率磁化率环境重要参考指标的分析,并与黄土—古土壤和深海δ18O记录的气候变化进行对比,结合剖面的岩性特征和年代序列以及前人所获得的粒度和孢粉资料,揭示了3.6Ma～0.5Ma期间昆仑山垭口盆地气候变化经历了6个不同的阶段:3.6Ma～2.48Ma气候相对冷干,2.48Ma～2.14Ma气候偏凉湿,2.14Ma～2.07Ma气候相对冷干,2.07Ma～1.16Ma气候总体相对较湿润(其间有数次冷干波动),1.16Ma～0.78Ma气候偏冷干以及0.78Ma～0.5Ma气候向冷湿发展。     

西藏纳木错及邻区全新世气候与环境变化的地质记录

综合分析了全新世期间内的多种与气候和环境变化密切相关的地质记录,结果表明该区全新世期间的气候变化可划分为3个阶段:1)约11.8～8.4kaBP期间,处于微温期和升温期,气候相对温和稍湿.2)8.4～4.0kaBP期间,为全新世气候最适宜时期或大暖期.该期间的平均气温可能比现今高约5℃,降水量比今多100～200mm.3)4.0kaBP以来,气候整体较为干冷.纳木错湖面发生持续下降,其最大下降幅度可达11.4m.冰川进退和湖面波动表明,该期间内的气候波动过程分别与新冰期和小冰期相对应,其中又各包含了3次明显的冷期,其中新冰期期间的最低年平均气温可达-6℃左右.约1970年以来,区域气候向暖湿方向转化,造成念青唐古拉山西布冰川后退约120～200m,纳木错湖面上涨了约2m.     

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.)