A comparative study on the illite crystallinity and the clay mineral reflectance spectral index for subdividing the very low-grade metamorphic belt along the Lizhou-Hekou geological section in the Youjiang sedimentary basin, Guangxi, China     

YAN Shouxun Laboratory of Remote Sensing Information Sciences  Institute of Remote Sensing Applications  Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2004,47(9)

To examine the application potential of hyperspectral remote sensing techniques in classifying very low-grade metamorphic belts, the composition of clay minerals and the cyrstallinity of illite from mudstones were measured using XRD and VIS-SWIR (400-2500 nm) reflectance spectroscopy. Based on the illite cyrstallinity, Kubler Index (KI), the Early Triassic LuoLou Group and the Middle Triassic lower Baifeng Formation were classified as the lower Epizone with KI△2θ° ranging from 0.22 to 0.25, the upper Baifeng Formation as upper anchizone with KI△2θ°ranging from 0.26 to 0.33, and the Hekou Formation as lower anchizone with KI△2θ° ranging from 0.38 to 0.40. According to a KI△2θ° value of 0.43, it is possible that there may exist a local diagenetic zone in the upper strata. The illite cyrstallinity Kubler index and the metamorphic grade increase from the bottom to the top of the stratigraphic sequence. The metamorphic grade boundaries nearly match the stratigraphic boundaries, indicating a burial metamorphism nature for the stratigraphic sequence. From the bottom to the top of the sequence, the spectral absorption band center of clay minerals from fresh rocks is around 2200 nm. The absorption band centers change towards shorter wavelengths: the Luolou Group being at 2220 nm, the Baifeng Formation at 2217-2213 nm, the lower member of the Hekou Formation at 2214-2206 nm, and the upper member of the Hekou Formation at 2205-2197 nm. The spectral absorption band center of illite shows the same change pattern. These results indicate that very low-grade metamorphic belts can be subdivided using spectral indices of clay minerals, which are measured by using field portable spectroradiometers. However, it may not work well with satellite and airborne sensors.  相似文献   

A Modeling Study of the Effects of Anomalous Snow Cover over the Tibetan Plateau upon the South Asian Summer Monsoon   总被引：1，自引：0，他引：1  

刘华强  孙照渤王举 闵锦忠 《大气科学进展》2004,21(6):964-975

The effect of anomalous snow cover over the Tibetan Plateau upon the South Asian summer monsoon is investigated by numerical simulations using the NCAR regional climate model (RegCM2) into which gravity wave drag has been introduced. The simulations adopt relatively realistic snow mass forcings based on Scanning Multi-channel Microwave Radiometer (SNINIR) pentad snow depth data. The physical mechanism and spatial structure of the sensitivity of the South Asian early summer monsoon to snow cover anomaly over the Tibetan Plateau are revealed. The main results are summarized as follows. The heavier than normal snow cover over the Plateau can obviously reduce the shortwave radiation absorbed by surface through the albedo effect, which is compensated by weaker upward sensible heat flux associated with colder surface temperature, whereas the effects of snow melting and evaporation are relatively smaller.The anomalies of surface heat fluxes can last until June and become unobvious in July. The decrease of the Plateau surface temperature caused by heavier snow cover reaches its maximum value from late April to early May. The atmospheric cooling in the mid-upper troposphere over the Plateau and its surrounding areas is most obvious in May and can keep a fairly strong intensity in June. In contrast, there is warming to the south of the Plateau in the mid-lower troposphere from April to June with a maximum value in May.The heavier snow cover over the Plateau can reduce the intensity of the South Asian summer monsoon and rainfall to some extent, but this influence is only obvious in early summer and almost disappears in later stages.  相似文献   

冲击钻进     

赵玉军  孙建平 《水文地质工程地质技术方法动态》2004,(5):36-38

冲击钻进方法能使钢绳钻进更容易些吗?的确是这样。在加利福尼亚州的尤巴城，我们使用H．T．“Ted”Herr well drilling Inc．钻机进行工作。钻井大多数分布在尤巴县，萨特县，科卢萨县和比尤特县，偶尔在普莱瑟和约洛县也进行过钻井工作。在尤巴-萨特县和其他四个县的部分岩层，适于用钢绳钻机进行冲击钻进。  相似文献   

“大洋一号”远洋科学考察船          下载免费PDF全文

《探矿工程》2004,31(12):41-41

“大洋一号”远洋科学考察船于1994年从俄罗斯引进，为国际无限航区大洋综合科学调查船，2002年在上海沪东船厂进行了增改装，安装了动力定位系统、全回转艏侧推系统、光缆绞车、铠装电缆绞车、地质绞车、  相似文献   

南极冰貌卫星影像条带噪声的剔除          下载免费PDF全文

鄂栋臣  沈强 《极地研究》2004,15(1):1-10

本文在简要叙述条带噪声形成原因的基础上 ,针对南极地区的ASTER 1A的可见光影像中出现的条带噪声的现象 ,通过设计了基于切比雪夫窗、凯瑟窗的FIR滤波器和约束最小二乘FIR滤波器对其条带噪声进行剔除 ,这两种滤波器能够尽可能地剔除条带 ,同时使影像的灰度分布发生最小畸变。并通过与其他方法 (例如 :低通滤波 ,直方图匹配等 )比较 ,说明这两种滤波的方法优于其他的方法  相似文献   

地形可视化的进展与评述   总被引：4，自引：0，他引：4  

詹发新 《四川测绘》2004,27(2):58-61

地形可视化由于具有越来越广泛的用途，因此越来越多地引起了大家的关注。本文在简要论述科学可视化、地形可视化定义及其研究内容的基础上，着重讨论了当前地形可视化的表达手段、可视化建模与技术、可视化生成工具、实时地形生成等方面的研究现状及存在的问题，最后对可视化的应用前景和发展趋势进行了展望。  相似文献   

淮安五河口特大桥大口径灌注桩施工实践     

刘效良  李宏伟  董军 《安徽地质》2005,15(1):56-60

介绍了使用大口径钻机，采用泥浆护壁气举反循环回转钻进工艺、进行淮安市五河口特大桥大口径灌注桩施工的工程实践。通过不断提高施工技术措施，摸索与总结出一套成孔施工经验，顺利地完成了施工任务。  相似文献   

Biomineralization of Uranium: A Simulated Experiment and Its Significance   总被引：5，自引：0，他引：5  

L. L. BARTON  H. WIATROWSKI 《《地质学报》英文版》2005,79(1):134-138

A simulated experimental reduction of U^v1 and the synthesis of uraninite by a sulfate-reducing bacteria,Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were:35℃, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week‘s incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments,might have participated in the biomineralization of this uranium deposit. There is an important difference in the orderdisorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated.  相似文献   

CGD-1型大口径全套管冲击抓斗的设计和应用          下载免费PDF全文

冯起赠  宋志彬  王年友 《探矿工程》2005,32(6):38-40

CGD－1型大口径全套管冲击抓斗主要是配套全套管钻机施工而研制的。该抓斗主要适用于复杂地层的施工。介绍了该抓斗的技术参数、性能特点、主要结构及试验情况。  相似文献   

北冰洋海冰和海水变异对海洋生态系统的潜在影响   总被引：2，自引：0，他引：2       下载免费PDF全文

王桂忠  何剑锋  蔡明红  李少菁  戴聪杰 《极地研究》2005,17(3):165-172

最近30年来,北冰洋海冰和海水发生了急剧变化:海冰覆盖面积减少、冰层变薄、水温升高、淡水输入增加、污染加剧,正威胁着现有与海冰关系密切的生态系统。预期随着变化的持续,与海冰相关的食物链将在部分海域消失并被较低纬度的海洋物种所取代、总初级生产力有望增加并为人类带来更多的渔获量、而北极熊和海象等以海冰作为栖息和捕食场所的大型哺乳动物的生存前景堪忧。今后人类将更为重视对北冰洋生态环境变化规律的认识并加以运用、关注北冰洋特有物种的命运并加以力所能及的保护、评估北冰洋生态系统的变化对人类社会经济的影响以期及早采取应对措施。数据积累是目前制约北极研究的最大障碍,但随着 SEARCH 等大型国际研究计划的实施,对北冰洋生态系统的监测和研究将更为系统和全面。  相似文献