Uniform postglacial slip-rate along the central 600 km of the Kunlun Fault (Tibet), from ²⁶Al, ¹⁰Be, and ¹⁴C dating of riser offsets, and climatic origin of the regional morphology     

Jerome Van Der Woerd  Paul Tapponnier  Frederick J. Ryerson  Anne-Sophie Meriaux  Bertrand Meyer  Yves Gaudemer  Robert C. Finkel  Marc W. Caffee  Zhao Guoguang  Xu Zhiqin 《Geophysical Journal International》2002,148(3):356-388

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Sedimentary cycles of trace elements in Salawusu River Valley since 150 ka BP   总被引：6，自引：0，他引：6  

Yao Chun-xial  Li Bao-sheng  Jin He-ling  David Dian Zhang  Yan Man-cun  Zhu Yi-zhi  Li Hou-xin  Zhang Yu-hong  Luo Kai-li 《地理学报(英文版)》2002,12(1):65-71

The paper makes some analyses on 11 trace elements in the Milanggouwan stratigraphical section in the Salawusu River valley, which is regarded as a prototype geology-palaeoclimate record since 150 ka BP. The results show that the content and variation of trace elements has experienced remarkably regular changes in the pace with coarse and fine sedimentary cycles of palaeo-aeolian sands to its overlying fluvio-lacustrine facies or/and palaeosols. The trace elements with chemical properties of relatively active (V, Sr, Cu, Ni, As) and relatively stable (P, Pb, Rb, Mn, Nb, Zr) are a manifestation of the corresponding 27 changeable cycles between peak and valley values, appearing a multi-fiuctuational process line of relative gathering and migration since then. The low numerical value distribution of these two types of trace elements in the aeolian sand facies represents erosion and accumulation under wind force during the cold-dry climate. Whereas their enrichments in both fluvio-lacustrine facies and palaeosols are related to the valley’s special low-lying physiognomic position between the Ordos Plateau and the Loess Plateau under the warm and humid climate conditions. The above relatively migrated and gathered change of the trace elements is the result of 27 climatic cycles of cold-dry and warm-humid, which is probably caused by repeated alternations of winter monsoon and summer monsoon in the Mu Us Sandy Land influenced by the climate vicissitudes in northern hemisphere during glacial and interglacial periods since 150 ka BP.  相似文献   

湖泊记录中的古气候和古环境指标及其地质灾害信息   总被引：4，自引：0，他引：4       下载免费PDF全文

段丽萍  王兰生  董孝璧 《沉积与特提斯地质》2002,22(1):40-45

笔者在简略论述反映古气候、古环境的多种代用指标的基础上，讨论其在揭示地质灾害信息方面的意义，并分析从中提取地质灾害信息的方法和思路。认为在沉积物粒度判别基础上， 沉积物表现出的较低δ^18O值，较低δ13C值和较低碳酸盐含量以及较高的有机质含量特征可能指示了地质灾害方面的信息。  相似文献   

福建省中部沿海地区十二万年来的古气候   总被引：2，自引：0，他引：2  

金株生  郑芬 《福建地质》1993,12(3):218-227

根据福建中部沿海地区有关钻孔或露头第四系孢粉样的研究,将该区距今12万年以来的古气候划分为七个气候期:(1)温暖湿润的琅岐期,距今12.0—7.0万年;(2)冷干的前福州期,距今7.0—4.1万年;(3)前期凉爽,后期温湿的福州期,距今4.1—2.0万年;(4)冷干的后福州期,距今2.0—1.2万年;(5)稍温干的前长乐期,距今1.2—0.8万年;(6)暖热湿润的长乐期,距今0.8—0.3万年;(7)稍温湿的后长乐期,距今0.3万年至现在。福建省中部沿海地区晚更新世下限距今约12万年,全新世下限距今约1.2万年。  相似文献   

辽河小洼油田东营组沉积环境条件的研究     

周琦 《沉积与特提斯地质》1997,17(5):50-56

陆相盆地沉积作用主要受构造作用及古气候的控制，所以从区域构造背景出发，结合地层、古生物、沉积、地球化学等方面资料，对小洼油田东营组的沉积环境条件进行综合分析。确定了沉积物源来自北东方向的中央凸起，古气候属于半干旱—半潮湿的温带气候条件，水介质是弱还原性的淡水滨浅湖泊沉积环境。此时中央凸起上丰富的风化剥蚀产物经过河流的搬运和分异作用，进入湖盆中形成三角洲沉积体  相似文献   

西藏南部吉隆盆地晚中新世-早更新世介形类群落研究     

陈奋宁  陈锐明  郭岐明  张克信  周修高  徐亚东  江尚松 《地质学报》2013,87(6):872-886

本文在西藏南部吉隆盆地新生代沉积中获得丰富的介形类化石,根据介形类动物群在地层剖面上的分布规律,建立了8个介形类群落,自下而上为:Leucocytherella trinoda-Ilyocypris群落;Ilyocypris pentanada-Leucocytherella hyalina群落;Candoniella zadaensis-Leucocytherella群落;Eucypris subgyrongensis-Candoniella zadaensis群落;Leucocytherella-Cadoniella zadaensis群落;Leucocythere mirabilis-Leucocytherella hyalina群落;Leucocythere mirabilis-Leucocytherella glabra群落和Leucocythere mirabilis-Leucocytherella trinoda群落。通过对介形类群落进行详细的特征分析,并结合磁性地层年代学数据,将吉隆盆地7.2～1.67Ma的古气候划分为5个期次:①7.2～6.7Ma为暖湿期;②6.7～5.8Ma为凉湿期;③5.8～3.6Ma为暖湿期;④3.6～2.6Ma为凉湿期;⑤2.6～1.67Ma为冷干期。将研究区的7.2Ma以来的气候演化特征与全球气候演变对比认为:吉隆盆地7.2～5.8Ma间的气候以暖湿为主,可能与来自印度的东南季风加强有关;5.8～3.6Ma间吉隆盆地古气候分析显示为相对暖湿期,可能与来自印度洋的东南季风再次加强有关;3.6Ma后,由于是受全球气候变冷、冬季风加强及青藏高原强烈隆升的影响,吉隆盆地气候向更寒冷干旱的环境转变。  相似文献   

Phanerozoic general circulation model results and quantitative climate data for Australia     

L. A. Frakes  E. J. Barron 《Australian Journal of Earth Sciences》2013,60(5):643-655

Quantitative data bearing on Phanerozoic climates of Australia are summarised and comparisons are made with the predictions of atmospheric general circulation models over 12 time slices from the Silurian to the Miocene. Summaries of the model derived mean temperature and precipitation conditions are given individually for each of four regions (southeast, northeast, southwest and northwest). Model results provide the means of estimating climate conditions in many cases, but there is fair agreement between the two approaches in most cases in which data are available. On model results, the southeast experienced winter freezing conditions from the Permian through until the middle Cretaceous and was consistently the coolest of the four regions, in part because of its proximity to the pole, but also because it was the site of elevated terrain throughout most of the Phanerozoic. It also tended to be among the wettest parts of Australia over this time and was subject to frequent winter storms. The northeast, in contrast, was often the warmest part of the continent, although strong seasonality and freezing winter temperatures were common during the Mesozoic and Palaeozoic. Strong seasonality (>30°C contrast between winter and summer) also apparently characterised most of the record for the southwest region, except for the Tertiary, part of the Jurassic, and the Early Palaeozoic. Together with the southeast, this region experienced the most intense effects of winter, especially in the Triassic. Strong seasonality also affected the northwest region through much of the Palaeozoic and Mesozoic and, interestingly, the highest summer temperatures on the continent are predicted for the southwest for most of the time slices studied. The models used today are imperfect but, nonetheless, offer a means of prediction and will perhaps stimulate the gathering of quantitative data in a continent where information is hard to come by and for which not much has yet been presented.  相似文献   

Caractérisation hydrogéochimique de la nappe du Continental Intercalaire (sud tunisien) / Hydrogeochemical characterization of the Continental Intercalaire aquifer (southern Tunisia)     

《水文科学杂志》2013,58(3):526-537

Abstract

The study of the Continental Intercalaire aquifer system of southern Tunisia, based on the interpretation of geochemical (major elements) and isotopic (¹⁸O, ²H, ¹³C and ¹⁴C) data, has aided the understanding of the hydrodynamics of this multi-layer aquifer system, which is greatly influenced by tectonics. The determination of the origin of groundwater salinization and the understanding of the hydrogeological and geochemical behaviour of this aquifer were achieved by studying the correlation between the major elements and total mineralization (TDS). By using isotopic tools, it was shown that the water of this aquifer has been recharged under cooler, palaeoclimatic conditions. The technique also made it possible to better understand the hydrodynamic functioning of the aquifer system: it showed that the relatively recent recharge of the aquifer has been by direct infiltration from carbonate and sandy outcrops of the Cretaceous and Miocene, respectively, located in the eastern and northeastern parts of the aquifer. The ¹⁸O content was used to calculate the altitude of recharge basins. The isotopic gradient defined in this study is ?0.5 δ¹⁸O ‰/100 m.  相似文献   

Middle and late Cenomanian oceanic anoxic events in shallow and deeper shelf environments of western Morocco     

BRIAN GERTSCH  THIERRY ADATTE  GERTA KELLER  ABDEL AZIZ A.M. TANTAWY  ZSOLT BERNER  HAYDON P. MORT  DOMINIK FLEITMANN 《Sedimentology》2010,57(6):1430-1462

The response of shallow‐water sequences to oceanic anoxic event 2 and mid‐Cenomanian events 1a and 1b was investigated along the west African margin of Morocco north of Agadir (Azazoul) and correlated with the deep‐water sequence of the Tarfaya Basin (Mohammed Beach) based on biostratigraphy, mineralogy, phosphorus and stable isotopes. In the deeper Mohammed Beach section results show double peaks in δ¹³C_org for mid‐Cenomanian events 1a and 1b (Rotalipora reicheli biozone, lower CC10a biozone), the characteristic oceanic anoxic event 2 δ¹³C excursion (Rotalipora cushmani extinction, top of CC10a biozone) and laminated (anoxic) black shale. In the shallow environment north of Agadir, a fluctuating sea‐level associated with dysoxic, brackish and mesotrophic conditions prevailed during the middle to late Cenomanian, as indicated by oyster biostromes, nannofossils, planktonic and benthonic foraminiferal assemblages. Anoxic conditions characteristic of oceanic anoxic event 2 (for example, laminated black shales) did not reach into shallow‐water environments until the maximum transgression of the early Turonian. Climate conditions decoupled along the western margin of Morocco between mid‐Cenomanian event 1b and the Cenomanian–Turonian boundary, as also observed in eastern Tethys. North of Agadir alternating humid and dry seasonal conditions prevailed, whereas in the Tarfaya Basin the climate was dry and seasonal. This climatic decoupling can be attributed to variations in the Intertropical Convergence Zone and in the intensity of the north‐east trade winds in tropical areas.  相似文献   

甘肃兰州盆地渐新世古气候参数重建          下载免费PDF全文

姚妮妮  马福军  闫德飞 《甘肃地质》2010,(4):20-25

本文对甘肃兰州盆地渐新统韩家井组的9科11属20种植物化石进行了共存分析,重建了该地区渐新世古气候各参数:年均温(MAT)为-1.4℃～10.9℃,最热月均温(MWT)为9.6℃～27.3℃,最冷月均温(CMT)为-4.4℃～-12.5℃,年较差(DT)为28.0℃～29.8℃,年均降水量(MAP)为315.7～492.2mm,平均最大月降水量(MMaP)为70.5～93.5mm,平均最小月降水量(MMiP)为0.4～11.1mm。分析表明相对于当前气候来说,兰州盆地在渐新世时接近现今甘肃武山地区气候特征,降水量多,气候更加湿润。  相似文献