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591.
东亚大陆磁异常的西向漂移   总被引:12,自引:6,他引:6       下载免费PDF全文
西向漂移是地磁场长期变化最重要的特点之一,而西漂最显著的部分是非偶极子场部分.本文以1900-2000年国际参考地磁场(IGRF)为依据,运用无线电科学中的"移动变形图案相关分析"方法对近百年来东亚大陆磁异常的漂移运动进行了分析,得到磁异常各分量漂移矢量随时间的变化.结果表明,最能代表地磁场西漂特征的Z分量异常近百年来平均西漂速度为0.07°/a,明显小于全球磁场西漂的平均速度0.2°/a.Z分量还显示出0.02°/a的缓慢北向漂移.详细分析还表明,东亚大陆磁异常的漂移分为3个阶段:1900-1930年为较快的西漂,平均速度为0.10°/a;1930-1980年为西北向漂移,平均西漂速度分量0.07°/a,北漂速度分量为0.04°/a;1980年后漂移几乎停止,并有转为东漂的迹象.  相似文献   
592.
在确立了大气环境质量标准物元矩阵基础上,对物元分析法在大气环境单元质量评价和排序中的应用进行了探索。实例分析表明物元分析法用于环境单元质量评价和排序是有效的  相似文献   
593.
王仁民 《地震地质》1994,16(3):216-216
胶东半岛发现元古宙蛇绿岩套王仁民(北京大学地质学系,北京100871)近年来在原胶东群内部,新发现一条NNE走向的蛇绿岩套。层序基本齐全,出露宽约15km,从北海岸到南海岸延长在100km以上,大约在东经122°附近将胶东半岛分割为东西两半。蛇绿岩套  相似文献   
594.
黄土高原小流域特性指标与产沙统计模式   总被引:27,自引:0,他引:27  
本文从黄土高原实际情况出发,在广泛的野外考察基础上,收集了面积在0.193--329km2的58个小流域(包括21个变量)的系列数据。通过分析筛选,建立了流域地表综台特性指标:  相似文献   
595.
In order to investigate connections between deep tectonic and halokinetic structures and the development of recent topography, GIS-based calculation of correlation coefficients was carried out between different stratigraphic horizons of the deep Northwest German Basin (NGB) according to the “Geotektonischer Atlas von NW-Deutschland” and surface topography of Schleswig-Holstein. The results show seven areas of high correlation that are traceable from the Base Zechstein up to the recent surface topography. Five areas with high correlation are connected to NNE–SSW trending salt structures within the Glückstadt Trough, i.e. the area of the salt domes Oldensworth, Tellingstedt, Eisendorf and, to the north of Hamburg, the area of the salt domes Elmshorn and Sievershütten. Two areas, however, with NW–SE trending high correlation are located in the northwest (restricted to the Westschleswig Block) and the northeast (south of Fehmarn) outside the Glückstadt Trough. These NW–SE trending correlation areas are not related to known salt structures and/or faults but match the general orientation of faults in the NGB.  相似文献   
596.
The Kimmeridgian Stage is represented in the cliffs of the Dorset-type area and those in Normandy by richly fossiliferous marine mudstones and limestones. Taken together, these coastal exposures provide the only complete composite outcrop through this part of the Jurassic in the Sub-boreal Faunal Province. Detailed correlations between the two successions are presented here: these enable the Normandy-coast sections to be more accurately placed than previously within in their regional chronostratigraphical context. The Normandy succession is more completely exposed than that in Dorset, and is situated midway between Dorset and the Sub-Tethyan succession of the Berry region. It therefore offers a better prospect than any English section for inter-province correlation at this stratigraphical level. To cite this article: R. Gallois, C. R. Geoscience 337 (2005).  相似文献   
597.
Using a large database of residential short-term radon measurements in New Hampshire, this study evaluated the ability of expert-assigned bedrock radon potential for predicting residential radon concentration. First, each bedrock type was assigned a radon potential level by a geologist familiar with the local geology. Then, using residential radon measurements, a continuous surface of radon concentration was generated through a kriging process. The mean residential radon concentration within the spatial extent of each bedrock type was then calculated based on that surface. The Spearman Rank Correlation Coefficient was calculated between the two ranks of the bedrock types, one based on the expert-assigned potential level and the other based on the mean residential concentration. A strong correlation between the rank correlation and the area of the bedrock type was found. When only the 15 largest bedrock types were used, the Spearman Correlation Coefficient reached 0.6. Geological knowledge is concluded to be useful in predicting and mapping residential radon concentration, but the prediction should be interpreted with caution, especially for areas in which the underlying bedrocks are highly localized.  相似文献   
598.
中国-老挝古近纪钾盐矿对比   总被引:6,自引:0,他引:6  
张建林 《云南地质》2006,25(3):309-314
云南江城勐野井钾盐矿的探明,填补了我国无固体钾盐矿的史例。时代属古近系古新统(E1),与老挝万象钾镁盐矿属同时代、同构造带。勐野井钾盐矿赋存在勐野井组上部(E1me^3),属氯化钾(KCl)类;老挝万象钾镁盐矿属光卤石类,地层为古新统塔贡组下部(E1tg^1)。  相似文献   
599.
With a thickness of 3900 m, the Tazareh section is one of the thickest developments of the Shemshak Formation in the Alborz range. It overlies with sharp and disconformable contact the limestones and dolomites of the Lower–Middle Triassic Elikah Formation and is topped, again with a disconformable contact, by the marls and limestones of the Middle Jurassic Dalichai Formation. The nearly exclusively siliciclastic succession represents a range of environments, from fluvial channels, flood plains, swamps and lake systems to storm-dominated shelf, and a comparatively deep marine and partly dysoxic basin. The segment of the section between 2300 and 3500 m is exclusively marine and contains a moderately diverse ammonite fauna, ranging from the Middle Toarcian to the Upper Aalenian. The ammonite fauna comprises 21 taxa, among them the new genus Shahrudites with two new species, Shahrudites asseretoi and S. stoecklini from the Middle Aalenian Bradfordensis Zone. The other ammonites from the Shemshak Formation at Tazareh (as elsewhere in North and Central Iran) are exclusively Tethyan in character and closely related to faunas from western and central Europe. An ammonite-based correlation of Toarcian–Aalenian successions of the eastern Alborz with time-equivalent strata of the Lut Block, part of the Central-East Iranian Microcontinent (ca. 500 km to the south), suggests a strong influence of synsedimentary tectonics during the deposition of the upper Shemshak Formation.  相似文献   
600.
The emerging advances in the field of dynamical prediction of monsoon using state-of-the-art General Circulation Models (GCMs) have led to the development of various multi model ensemble techniques (MMEs). In the present study, the concept of Canonical Correlation Analysis is used for making MME (referred as Multi Model Canonical Correlation Analysis or MMCCA) for the prediction of Indian summer monsoon rainfall (ISMR) during June-July-August-September (JJAS). This method has been employed on the rainfall outputs of six different GCMs for the period 1982 to 2008. The prediction skill of ISMR by MMCCA is compared with the simple composite method (SCM) (i.e. arithmetic mean of all GCMs), which is taken as a benchmark. After a rigorous analysis through different skill metrics such as correlation coefficient and index of agreement, the superiority of MMCCA over SCM is illustrated. Performance of both models is also evaluated during six typical monsoon years and the results indicate the potential of MMCCA over SCM in capturing the spatial pattern during extreme years.  相似文献   
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