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281.
蒙古国煤炭资源丰富,但地质基础工作薄弱。位于蒙古国西部的胡硕图井田含煤地层为二叠系胡硕图组,为陆相三角洲体系沉积,含M1、M2巨厚煤层。根据煤质资料分析,区内煤类复杂,M1煤层以低灰、低挥发分、特低硫、高-特高热值、强黏结-特强黏结的焦煤(JM)为主;M2煤层以低灰、低挥发分、低硫、高-特高热值、中黏结-中强粘结的瘦煤(SM)为主;煤的变质作用类型以深成变质作用为主,同时存在动力变质作用。 相似文献
282.
郑州沿黄水源地地下水资源量评价 总被引:1,自引:0,他引:1
采用水文地质数值法和水均衡法,对郑州市九五滩和北郊水源地近年的运行状况进行模拟,对其满负荷开采的可行性进行评价.结果表明,两大水源地按设计进行开采,水资源量有保证. 相似文献
283.
康滇地轴前晋宁期构造运动讨论 总被引:2,自引:0,他引:2
康滇地轴前晋宁期是否有形成克拉通区域性强烈的构造运动,地学界未有共识。笔者从野外资料及大量同位素年龄两方面对其考查后,认为此时期构造运动证据不足。 相似文献
284.
Jun-ping Ren Jie Wang A-lei Gu Li-bo Zuo Hong-wei Sun Kang-kang Xu Fu-Qing He Chipilauka Mukofu Alphet Phaskani Dokowe Ezekiah Chikambwe 《China Geology》2022,5(1):60-70
The 1∶1000000 geochemical mapping of Zambia provides catchment sediment geochemical data for 58elements including Au from 746 sediment samples at 736 sampling sites,corresponding to a sampling density of about one site per 1000 km2.Under strict quality control using field duplicates,certified reference materials,and analytical replicate samples,the Au was determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS).The detection limit of Au was 0.20×10-9.The 95%range(2.5%–97.5%)of Au concentrations was from 0.24×10-9 to 1.36×10-9,and the median value was 0.40×10-9.The most noticeable Au distribution patterns shown on the map are mainly located between Lusaka and Ndola(Lufilian Arc Belt).In addition,several high Au value areas occurred in Mansa,Muyombe,Chipata,and Livingstone.The spatial distribution patterns of Au in tectonic units,drainage basins,and geomorphological landscapes could be related to the Lufilian Arc Belt and Bangweulu Block.The Au concentrations show metallogenic belts between Muyombe and Mbala areas,between Mansa and Ndola areas,and between Lusaka and Kasempa areas. 相似文献
285.
286.
An extended Ulysses interplanetary coronal mass ejections (ICMEs) list is used to statistically study the occurrence rate of ICMEs, the interaction
of ICMEs with solar wind, and the magnetic field properties in ICMEs. About 43% of the ICMEs are identified as magnetic clouds
(MCs). It is found that the occurrence rate of ICMEs approximately follows the solar activity level, except for the second
solar orbit; the rate is higher in the southern heliolatitude than in the northern heliolatitude; and it roughly decreases
with the increase of ICME speeds. Our results show that the speed difference between the ICME and the solar wind in front
of it shows a slight decrease with increasing heliocentric distance for ICMEs preceded by a shock, whereas no such dependence
is found for the ICMEs without shock association. It is also found that approximately 23% of the ICMEs are associated with
radial field events, in which the interplanetary magnetic field with near-radial direction lasts for many hours, in the Ulysses detected range, and these associated events are not necessarily confined to fast ICMEs or the trailing portions of ICMEs.
Nearly all these associated events occur during the period of declining solar wind speed and most of them occur at low heliolatitudes. 相似文献
287.
Huai River Basin, as the sixth largest river basin in China, has a high‐regulated river system and has been facing severe water problems. In this article, the changing patterns of runoff and precipitation at 10 hydrological stations from 1956 to 2000 on the highly regulated river (Shaying River) and less‐regulated river (Huai River) in the basin are evaluated at the monthly, seasonal and annual scales using the Mann–Kendall test and simple linear regression model. The results showed that: (1) No statistically significant trends of precipitation in the upper and middle Huai River Basins were detected at the annual scale, but the trend of annual runoff at Baiguishan, Zhoukou and Fuyang stations in Shaying River decreased significantly, whereas the others were not. Moreover, the decreasing trends of runoff for most months were significant in Shaying River, although the trend of monthly precipitation decreased significantly only in April in the whole research area and the number of months in the dry season having significantly decreasing trends in runoff was more than that in the wet season. (2) The rainfall–runoff relationship was significant in both highly regulated river and less‐regulated river. In regulated river, the reservoirs have larger regulation capacity than the floodgates and thus have the smaller correlation coefficient and t‐value. In Huai River, the correlation coefficients decreased from upper stream to downstream. (3) The regulation of dams and floodgates for flood control and water supply was the principal reason for the decreasing runoff in Huai River Basin, although the decreasing precipitation in April in this basin was statistically significant. The findings are useful for recognizing hydrology variation and will provide scientific foundation to integrated water resources management in Huai River Basin. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
288.
Chun-Lai Li Ling-Li Mu Xiao-Duan Zou Jian-Jun Liu Xin Ren Xing-Guo Zeng Yi-Man Yang Zhou-Bin Zhang Yu-Xuan Liu Wei Zuo Han Li 《中国天文和天体物理学报》2014,(12)
Chang'e-3(CE-3) landed on the Mare Imbrium basin in the east part of Sinus Iridum(19.51°W, 44.12°N), which was China's first soft landing on the Moon and it started collecting data on the lunar surface environment. To better understand the environment of this region, this paper utilizes the available high-resolution topography data, image data and geological data to carry out a detailed analysis and research on the area surrounding the landing site(Sinus Iridum and 45 km×70 km of the landing area)as well as on the topography, landform, geology and lunar dust of the area surrounding the landing site. A general topographic analysis of the surrounding area is based on a digital elevation model and digital elevation model data acquired by Chang'e-2 that have high resolution; the geology analysis is based on lunar geological data published by USGS; the study on topographic factors and distribution of craters and rocks in the surrounding area covering 4 km×4 km or even smaller is based on images from the CE-3 landing camera and images from the topographic camera; an analysis is done of the effect of the CE-3 engine plume on the lunar surface by comparing images before and after the landing using data from the landing camera. A comprehensive analysis of the results shows that the landing site and its surrounding area are identified as typical lunar mare with flat topography. They are suitable for maneuvers by the rover,and are rich in geological phenomena and scientific targets, making it an ideal site for exploration. 相似文献
289.
Farmers’ climate change beliefs and adaptation strategies for a water scarce future in Australia 总被引:1,自引:0,他引:1
Climate change is likely to require irrigators in Australia's Murray-Darling Basin to cope with less water, which will require ongoing farm adjustment. Possible incremental adjustment strategies include expansive and accommodating responses, such as irrigators buying land and water, increasing their irrigated area, changing crop mix and adopting efficient infrastructure. Contractive strategies include selling land and water, and decreasing their irrigated area. Using historical surveys we provide a comparison of irrigators’ planned and actual strategies over the past fifteen years, thereby offering a strong foundation to support analysing future adaptation strategies. We explore influences associated with farm adjustment strategies, and in particular the role that climate change beliefs play. Farmers convinced that climate change is occurring are more likely to plan accommodating, but not expansive, strategies. The relationship between climate change belief and adopting various adaptive strategies was found to be often endogenous, especially for accommodating strategies. Such results suggest the need for irrigation farming policies to be targeted at improving irrigators’ adaptability to manage water variability, and its link with farm future viability. 相似文献
290.
基于国际耦合模式比较计划第五阶段(CMIP5)历史试验(historical)的输出结果,评估了26个耦合模式对北极涛动(AO)的模拟能力。对各模式逐月AO指数序列的功率谱分析表明,有23个模式能够模拟出AO模态无显著变化周期的特征。这些模式也能够较好地再现冬季AO在海平面气压场上的主要分布特征,但均高估了AO模态的强度。对于伴随着冬季AO位相变化而出现的中高纬度偶极型的纬向平均纬向风异常,CMIP5中只有一些模式有较好的模拟表现,大多数模式对其中心位置和强度的模拟存在明显不足。对比之下,MPI-ESM-P对AO时空特征的模拟更接近观测结果。 相似文献