Late- and postglacial history of the Great Belt, Denmark   总被引：3，自引：0，他引：3  

OLE BENNIKE  JØRN BO JENSEN  WOLFRAM LEMKE  ANTOON KUIJPERS  STEEN LOMHOLT 《Boreas: An International Journal of Quaternary Research》2004,33(1):18-33

On the basis of shallow seismic records, vibrocoring, macrofossil analyses and AMS radiocarbon-dating, five stratigraphical units have been distinguished from the deepest parts of the central Great Belt (Storebælt) in southern Scandinavia. Widespread glacial deposits are followed by two lateglacial units confined to deeply incised channels and separated by an erosional boundary. Lateglacial Unit I dates from the time interval from the last deglaciation to the Allerød; lateglacial Unit II is of Younger Dryas age. Early Holocene deposits show a development from river deposits and lake-shore deposits to large lake deposits, corresponding to a rising shore level. Lake deposits are found up to 20 m below the sea floor, and the lake extended over some 200–300 km2. The early Holocene freshwater deposits are dated to the time interval c. 10900 to c. 8800 cal. yr BP and the oldest shells of marine molluscs from the Great Belt are dated to c. 8100 cal. yr BP.  相似文献   

信号传输的屏蔽措施与研究     

薄永进 《云南地理环境研究》2004,(Z1)

为了保证信息的正常传输,当布线环境有电磁干扰时,要相应地采用屏蔽系统。为了保证电子设备的正常工作,采用适当的屏蔽措施来阻挡或衰减电磁干扰。本文阐述了在现阶段雷灾中屏蔽的重要性以及屏蔽的具体施工,并对屏蔽的检验提出了一定的见解。  相似文献   

Satellite evidence for no change in terrestrial latent heat flux in the Three-River Headwaters region of China over the past three decades     

YUNJUN YAO  SHAOHUA ZHAO  HUAWEI WAN  YUHU ZHANG  BO JIANG  KUN JIA  MENG LIU  JINHUI WU 《Journal of Earth System Science》2016,125(6):1245-1253

Terrestrial latent heat flux (LE) in the Three-River Headwaters region (TRHR) of China plays an essential role in quantifying the amount of water evaporation and carbon sink over the high altitude Tibetan Plateau (TP). Global warming is expected to accelerate terrestrial hydrological cycle and to increase evaporation. However, direct field observations are lacking in this region and the long-term variability in LE remains uncertain. In this study, we have revised a semi-empirical Penman LE algorithm based on ground eddy covariance (EC) observations from an alpine grass site and provided new satellite-based evidence to assess LE change in the TRHR during 1982–2010. Our results show that the average annual terrestrial LE in the TRHR is about 38.8 W/m ² and there is no statistically significant change in annual LE from 1982 to 2010. We also found that during the same time period, terrestrial LE over the east region of the TRHR significantly decreased, on average, by 0.7 W/m ² per decade, which was driven primarily by the surface incident solar radiation (R_s) limitation, offsetting the increased LE over the west region of the TRHR caused by the increased precipitation (P) and soil moisture (SM).  相似文献   

Status of Stratigraphy Research in China     

YAO Jianxin  BO Jingfang  HOU Hongfei  WANG Zejiu  MA Xiulan  LIU Fengshan  HU Guangxiao  JI Zhansheng  WU Guichun  WU Zhenjie  LI Suping  GUO Caiqing  LI Ya 《《地质学报》英文版》2016,90(4):1069-1081

Scientific research and productive practice for earth history are inseparable from the accurate stratigraphic framework and time framework. Establishing the globally unified, precise and reliable chronostratigraphic series and geological time series is the major goal of the International Commission on Stratigraphy(ICS). Under the leadership of the ICS, the countries around the world have carried out research on the Global Standard Stratotype-section and Points(GSSPs) for the boundaries of chronostratigraphic systems. In the current International Chronostratigraphic Chart(ICC), 65 GSSPs have been erected in the Phanerozoic Eonothem, and one has yet been erected in the Precambrian Eonothem. Based on the progress of research on stratigraphy especially that from its subcommissions, the ICS is constantly revising the ICC, and will publish a new International Stratigraphic Guide in 2020. After continual efforts and broad international cooperation of Chinese stratigraphers, 10 GSSPs within the Phanerozoic Eonothem have been approved and ratified to erect in China by the ICS and IUGS. To establish the standards for stratigraphic division and correlation of China, with the support from the Ministry of Science and Technology, the National Natural Science Foundation of China and the China Geological Survey, Chinese stratigraphers have carried out research on the establishment of Stages in China. A total of 102 stages have been defined in the "Regional Chronostratigraphic Chart of China(geologic time)", in which 59 stages were studied in depth. In 2014, the "Stratigraphic Chart of China" was compiled, with the essential contents as follows: the correlation between international chronostratigraphy and regional chronostratigraphy of China(geologic time), the distributive status of lithostratigraphy, the characteristics of geological ages, the biostratigraphic sequence, the magnetostratigraphy, the geological events and eustatic sea-level change during every geological stage. The "Stratigraphical Guide of China and its Explanation(2014)" was also published. Chinese stratigraphers have paid much attention to stratigraphic research in south China, northeast China, north China and northwest China and they have made great achievements in special research on stratigraphy, based on the 1:1000000, 1:250000, 1:200000 and 1:50000 regional geological survey projects. Manifold new stratigraphic units were discovered and established by the regional geological surveys, which are helpful to improve the regional chronostratigraphic series of China. On the strength of the investigation in coastal and offshore areas, the status of marine strata in China has been expounded. According to the developing situation of international stratigraphy and the characteristics of Chinese stratigraphic work, the contrast relation between regional stratigraphic units of China and GSSPs will be established in the future, which will improve the application value of GSSPs and the standard of regional stratigraphic division and correlation. In addition, the study of stratigraphy of the Precambrian, terrestrial basins and orogenic belts will be strengthened, the Stratigraphic Chart of China will be improved, the typical stratigraphic sections in China will be protected and the applied study of stratigraphy in the fields of oil and gas, solid minerals, etc. will be promoted. On the ground of these actions, stratigraphic research will continue to play a great role in the social and economic development of China.  相似文献   

云南勐野井钾矿区及周边泉水水化学特征及地表钾异常成因分析     

伯英  曹养同  吕凤琳 《地质学报》2021,95(7):2193-2204

勐野井钾盐矿位于云南省兰坪-思茅盆地的南部,是我国目前发现的唯一一个具有工业开采价值的固体钾盐矿床.本文对该矿区及周边泉水等的水化学特征和地表钾异常成因进行了探讨.研究区含盐地层分布广泛,盐泉出露较多,通过对地表泉水、泉水沉积物、水中逸出气体及垂直断裂的测线剖面样品等取样分析,可以捕捉地表钾异常信息,对于成钾机理研究和钾盐找矿都有着积极的作用.结合以往研究证实了勐野井矿区附近盐泉水具有I级异常显示.沿垂直于断裂方向的剖面采集的土壤样品中,钾及相关组分的峰值和谷值的出现有一定的规律性,认为各元素含量异常是由深部流体(水、气)沿断裂上升补给造成的.泉水稀有气体He主要为深部壳源,个别为幔源,推断研究区的大断裂可能切至深部地壳,个别深切到软流圈上部.泉水氢氧同位素和锶同位素组成研究表明,该区泉水具有深部补给特征,存在一定程度的水-岩反应,受火山岩的影响较大,氢氧同位素和矿物学研究表明,深部热液在勐野井钾盐矿床形成过程中起重要作用.本研究认为深部补给是勐野井矿区及周边地表钾异常形成的重要补给源,火山岩可能是重要的物质来源之一,而断裂带是其重要的控制因素.  相似文献   

层状各向同性多孔介质中井间地震的数值计算   总被引：1，自引：0，他引：1       下载免费PDF全文

张钋  李幼铭 《地球物理学报》1995,38(4):507-518

依据Ｂｉｏｔ理论，提出计算理论地震图的相应传播矩阵算法，并针对井间地震震源和检波器的不同配置进行数值计算，结果表明，本文算法高频可达１０００Ｈ２以上．文中算例说明利用震源和检波器相对于储油层的不同位置，可从反射震相记录波形上的差异，判定储油层存在与否．  相似文献   

石灰稳定膨胀土的效用及其施工质量控制   总被引：13，自引：5，他引：13  

钱玉林  卜龙章  胡顺洋  殷宗泽 《岩土力学》2002,23(3):325-328

膨胀土的胀缩可引起地基的变形，甚至危及构筑物的安全。对于膨胀土路段，路基的稳定是工程建设成功的关键。在论述石灰稳定土加固机理的基础上，结合工程实例，论述了膨胀土路段石灰稳定的施工要点及石灰稳定膨胀土路段的施工质量控制。  相似文献   

基于被动微波遥感的青藏高原雪深反演及其结果评价   总被引：21，自引：0，他引：21  

柏延臣  冯学智  李新  陈贤章 《遥感学报》2001,5(3):161-165

采用修正的张氏雪深反演算法，用ＳＳＭ／Ｉ３７ＧＨz和19GHz水平极化亮温值计算了青藏高原及其毗邻地区的积雪深度，对其精度进行了评价，并对误差来源进行了分析，结果显示，此算法能够较好地反映研究区的雪深分布，但局部地区误差较大，总体上雪深被高估，其误差主要来源于冻土，深霜层，植被以及雪层中液态水含量，雪粒的形状和粒径的变化带来的影响，SSM／I数据较低的分辨率和研究区复杂的地形使反演的雪深与观测的雪深缺少可比性，给精度的评价带来影响。  相似文献   

大别造山带白马尖花岗岩体的钕，锶同位素地球化学研究   总被引：2，自引：1，他引：2       下载免费PDF全文

葛宁洁  柏林等 《地质论评》2001,47(2):184-187

大别造山带白马尖花岗岩体属燕山期侵入岩，为中生代大别山区岩浆活动的产物，为碰撞后花岗岩，锶，钕，同位素数据及稀土元素数据表明，白马尖花岗岩体为壳幔混合型，1．2－1．7Ga的钕模式年龄为其源岩的平均地壳存留年龄，北大别花岗岩类岩石的物质来源并不一致。  相似文献   

流体（水）在孕震过程中的作用   总被引：1，自引：0，他引：1       下载免费PDF全文

林命週  马波  仇志荣  梅安新 《地球物理学报》1981,24(2):171-181

本文在DD模式和IPE模式的基础上,提出了流体（水）扩散造成失稳的想法。对孕震过程的四个阶段给出了初步的定量讨论,突出了流体（水）的作用。以波速比前兆为例,求出了孕震时间的计算公式,发现孕震时间和余震区特征长度的平方并不严格成正比,可能含有一个三次因子。在作了适当近似和简化后,本文以实际数字对所求得的公式作了检验,计算结果和经验值吻合较好。  相似文献