祁连山摆浪河全新世冰量变化初探   总被引：2，自引：2，他引：0  

吴家章  易朝路  许向科  乔宝晋  刘宇硕 《冰川冻土》2015,37(3):595-603

采用祁连山老虎沟12号冰川2009年RTK测量生成的数字高程模型(DEM), 建立现代冰川表面横截面拟合的二次方程, 结合差分GPS测量的冰碛垄形态, 运用于祁连山摆浪河上游14号冰川和16号冰川全新世以来冰量变化的估算. 结果表明: 新冰期以来冰储量减少0.38 km³, 小冰期以来14号冰川和16号冰川的冰储量分别减少0.016 km³和0.047 km³; 根据祁连山全新世各个时期最大冰川范围的时间, 估计了全新世以来14号和16号冰川冰储量的减少速率, 新冰期以来为12.2×10^-5~15.0×10^-5 km³·a^-1, 小冰期以来分别为4.0×10^-5~5.3×10^-5 km³·a^-1, 11.75×10^-5~15.7×10^-5 km³·a^-1.  相似文献   

ABLATION OF ICE‐CORED MORAINE IN A HUMID,MARITIME CLIMATE: FOX GLACIER,NEW ZEALAND     

MARTIN S. BROOK  SHERYL PAINE 《Geografiska Annaler: Series A, Physical Geography》2012,94(3):339-349

Depending on thickness, debris‐cover can enhance or reduce ablation, compared to bare‐ice conditions. In the geological record, hummocky moraines often represent the final product of the melt‐out of ice‐cored moraines, and the presence or absence of such moraine deposits can have paleoclimatic implications. To evaluate the effects of varying debris‐cover and climate on ice‐melt in a maritime mid‐latitude setting, an 11‐day ablation stake study was undertaken on ice‐cored moraine at Fox Glacier, on the western flank of the New Zealand Southern Alps. Ablation rates varied from 1.3 to 6.7 cm d^?1, with enhancement of melt‐rate under thin debris‐covers. Highest melt‐rates (effective thickness) occurred under debris‐cover of c. 2 cm, with ～3 cm being the debris thickness at which melt‐rates are equal to adjacent bare‐ice (critical thickness). Air temperature from nearby Franz Josef Glacier allowed for a simple degree‐day approach to ablation calculations, with regression relationships indicating air temperature is the key climatic control on melt. Digital elevation models produced from topographic surveys of the ice‐cored moraine over the following 19 months indicated that ablation rates progressively decreased over time, probably due to melt‐out of englacial debris increasing debris‐cover thickness. The morphology of the sandur appears to be strongly determined by episodic high‐magnitude fluvial flows (jökulhlaups), in conjunction with surface melt. Thus, ‘hummocky’ moraine appears to be a transient landform in this climatic setting.  相似文献   

青海德尔尼铜（钴）矿床研究新进展     

焦建刚  ;黄喜峰  ;袁海潮  ;陈博  ;孙涛  ;刘瑞平 《西安地质学院学报》2009,(1):42-47

以大比例尺地质填图和实测剖面工作为基础,通过野外详细地质观察,室内电子探针分析对比,再结合前人研究成果,论述了德尔尼铜（钴）矿床成矿晚于超基性岩,矿床主体为海底喷流沉积成因,同时经历了热液叠加成矿作用和构造变位。其成矿过程为：在拉张环境下,蛇绿岩破碎,同时发生了海底喷流—沉积作用,喷流物质沿蛇绿岩中的构造破碎带喷出与沉积,并萃取了超基性岩中大量的钴,矿体形成后又经历了构造变位。  相似文献   

Multifractal Simulation of GeochemicalMap Patterns   总被引：3，自引：0，他引：3  

Agterberg Frederik P Geological Survey of Canada  Booth Street  Ottawa  KA E  Canada 《中国地质大学学报(英文版)》2001,12(1)

INTRODUCTIONThe mathematical modeling of geochemical data continuesto present an important challenge to earth scientists. Basically,the available data are 2-dimensional realizations of 3dimensional patterns, which are the results of one or more genetic processes that usually are poorly understood. It may bedifficult to project from the observations into the rock mass. Inthis paper, multifractal modeling is advocated as a methodologyto characterize geochemical patterns. If a geochemical pa…  相似文献   

The final phase of dead-ice moraine development: processes and sediment architecture, Kötlujökull, Iceland     

Kurt H. Kjær  & Johannes Krüger 《Sedimentology》2001,48(5):935-952

Consecutive phases of de-icing of ice-cored moraines and the formation of dead-ice moraine were monitored over a 4-year period at the terminus of the Kötlujökull glacier, Iceland. Particularly, the transition from partially ice-cored moraine with isolated dead-ice blocks to the ice-free landscape receives attention in this paper in order to link the final melting processes to the architecture of the sedimentary end product. In the current humid sub-polar climate of south Iceland de-icing of partially ice-cored moraines results chiefly from melting along the bottom surface of ice-cores with an annual average rate of 25 cm. The final de-icing is associated with an interrelated group of re-sedimentation processes and surface features. Series of sinkholes evolve at the toe of dead-ice blocks, which initiate retrogressive rotational sliding or backslumping of the ice-cored slopes and the formation of distinct edges and fractures in the adjacent basins. Although backslumping is the dominant process in this phase of re-sedimentation, structures resulting from this process are rarely recognized in the ice-free landscape. As ice-cores gradually diminish the effect of the latest re-sedimentation events will overprint or destroy most existing sedimentary characteristics. Thus, in the ice-free landscape, structures mainly related to the formation of sinkholes and fractures remain imprinted on the sediment succession. Generally, no inversion of the topography occurs during the final phase of de-icing. The overall topography recognized in the late phase of the fully ice-cored terrain is merely lowered and the amplitude of the relief reduced as de-icing progresses. The sediment architecture of the ice-free landscape is characterized by heterogeneous and often slumped diamict sediments with variable thickness and lateral distribution; clast orientation is related to the direction of slopes, and boulders are found in isolated groups or in linear arrangements.  相似文献   

西藏波密米堆冰湖溃决浅议   总被引：4，自引：0，他引：4  

李德基  游勇 《山地学报》1992,(4)

1988年7月15日西藏波密米堆终碛湖发生溃决,最大洪峰流量1270立方米/秒,溃决水量540万立方米,形成了大规模的泥石流-洪水灾害。冰湖溃决的原因是;终碛堤存在渗漏薄弱环节,堤内有埋藏冰;持续高温和冰川融水的潜热使埋藏冰融化,由潜蚀而迅速发展成管涌导致溃决。  相似文献   

白头山区冰川地貌航空卫星照片解译   总被引：2，自引：0，他引：2  

李邦良 《地质论评》1992,38(5)

通过解译,首次在吉林省白头山下发现了巨大的冰碛扇裙、冰水扇裙和叠加其上的冰碛垄、蛇形丘、中碛、侧碛等;在火山锥体上发现了若干冰斗、冰窖、冰蚀环谷、基岩鼓丘、葫芦谷等冰蚀冰碛地貌,同时对火口内前人已报导过的冰斗、冰窖,根据其相互叠加关系进行了划分和成生探讨。根据火山锥体表面及其外围若干冰蚀冰碛地貌的空间组合及其相互关系,并充分考虑到区内新构造运动的影响、流水侵蚀和重力崩塌等的协从作用,在此基础上分析探讨了区内冰川作用的若干规律性问题。  相似文献   

深厚覆盖层渗透系数三种测定方法的对比分析--以新疆下坂地水库坝址覆盖层为例   总被引：3，自引：0，他引：3  

邢丁家 《水文地质工程地质》2004,31(2):88-89,104

深厚覆盖层结构复杂,其渗透系数的求取是目前勘察工作中一个难以解决的问题。本文通过3种方法的对比分析,并结合地层结构特征进行综合评价,取得了较为合理的渗透参数,为工程设计和施工提供了科学依据。  相似文献   

应用小波收缩方法剔除MODIS热红外波段数据条带噪声   总被引：10，自引：2，他引：10  

杨忠东  张文建  李俊  W. Paul Menzel  Richard A. Frey 《遥感学报》2004,8(1):23-30

采用多元并扫方式 (1km分辨率 1 0元并扫 ,5 0 0m分辨率 2 0元并扫 ,2 5 0m分辨率 4 0元并扫 )的MODIS传感器由于各探测单元在轨响应差异而引起的条带噪声对MODIS定量产品的反演计算精度造成一定影响。这种影响在MODIS的热红外波段尤其明显。为了尽可能减少这种影响 ,提高MODIS定量产品反演精度 ,提出应用小波收缩方法剔除MODIS数据条带噪声。研究首先使用连续小波变换方法分析MODIS条带数据 ,确定MODIS数据条带噪声在小波系数域中的尺度。其次 ,在分析条带噪声模式的基础上 ,使用小波收缩方法对MODIS 1B数据进行噪声剔除计算。最后比较了分别使用噪声剔除前后的两组MODIS 1B数据反演得到的部分云和大气定量遥感产品 ,结果表明 ,使用剔除噪声后的MODIS 1B数据反演的定量遥感产品精度具有明显的提高  相似文献   

Impact of a rock avalanche on a moraine‐dammed proglacial lake: Laguna Safuna Alta,Cordillera Blanca,Peru     

Bryn Hubbard  Andrew Heald  John M. Reynolds  Duncan Quincey  Shaun D. Richardson  Marco Zapata Luyo  Nelson Santillan Portilla  Michael J. Hambrey 《地球表面变化过程与地形》2005,30(10):1251-1264

Moraines that dam proglacial lakes pose an increasing hazard to communities in the Andes and other mountain ranges. The moraines are prone to failure through collapse, overtopping by lake waters or the effect of displacement waves resulting from ice and rock avalanches. Resulting floods have led to the loss of thousands of lives in the Cordillera Blanca mountains of Peru alone in the last 100 years. On 22 April 2002 a rock avalanche occurred immediately to the south‐west of Laguna Safuna Alta, in the Cordillera Blanca. The geomorphic evidence for the nature, magnitude and consequences of this event was investigated in August 2002. Field mapping indicated that the avalanche deposited 8–20 × 10⁶ m³ of rock into the lake and onto the surface of the frontal region of Glaciar Pucajirca, which flows into the lake. Repeated bathymetric surveying indicated that ～5 × 10⁶ m³ of this material was deposited directly into the lake. The immediate effect of this event was to create a displacement wave that gained in height as it travelled along the lake basin, overtopping the impounding moraine at the lake's northern end. To achieve overtopping, the maximum wave height must have been greater than 100 m. This, and subsequent seiche waves, caused extensive erosion of both the proximal and distal faces of the impounding terminal moraine. Further deep gullying of the distal face of this moraine resulted from the supply of pressurized water to the face via a relief overflow tunnel constructed in 1978. Two‐dimensional, steady‐state analysis of the stability of the post‐avalanche moraine rampart indicates that its proximal face remains susceptible to major large‐scale rotational failure. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献