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81.
山东迄今发现的蓝宝石砂矿和原生矿位于昌乐地区。根据成因蓝宝石砂矿层分为冲积砂矿层、洪积砂矿层和残坡积砂矿层;洪积砂矿层中蓝宝石最富。蓝宝石原生矿赋存于新生代新近纪临朐群牛山组和尧山组的玄武岩中,与高钾碱性玄武岩关系密切。  相似文献   
82.
Outlines of New Global Geochemical Mapping Program   总被引:2,自引:1,他引:2  
<正>Since 1988,great efforts and enthusiasm had been paid by applied geochemists in the implementation of global geochemical mapping through the International Geological Correlation Program's Projects 259 and 360,and the Task Group on‘Global Geochemical Baselines' established by the International Union of Geological Sciences(IUGS),in collaboration with the International Association of Geochemistry(IAGC).But how to use extremely low-density sampling to obtain a global picture of the distribution of most elements in the periodic table in a reasonably short time is still a great challenge faced by the applied geochemistry community.It will depend on the continuous development of new mapping concept,and the advisable and courageous innovation of methodology for searching other suitable sample media and sampling layout.Based on the encouragement results obtained from the representativeness study of delta sediments conducted at the mouth of Yangtze River,and at the mouths of its four major tributary,it is expected to broadly apply the geochemical fractal self-similarity nature to main rivers and their estuaries with catchments up to hundreds of thousands or over a million square kilometers in the world.With this new mapping concept,a new outlines of a Global Geochemical Mapping Program was advanced and the establishment of an International Research Center of Global Geochemical Mapping was also suggested to facilitate the programs implementations.  相似文献   
83.
南亚高压的季节变化与趋暖性   总被引:27,自引:3,他引:27  
利用NCEP/NCAR再分析资料,分析了南亚高压的季节变化,讨论了对流层中高层温度、整层大气视热源和非绝热加热率的时空变化对南亚高压季节变化的影响。结果表明,南亚高压存在两个季节平衡态,即夏半年的大陆高压和冬半年的海洋高压,大陆高压又可分为青藏高压和伊郎高压。加热场对南亚高压的季节变化有重要作用,南亚高压是一个暖性高压,其中心有“趋热性”,通常位于或趋于加热率的相对大值区。南亚高压的年循环过程,主要受南亚地区潜热和感热季节变化的支配。夏季北方地区和高压地区的强烈短波辐射加热对高压中心北移和维持也有作用,长波辐射的冷却作用则是高压减弱的重要原因。  相似文献   
84.
85.
According to the different pattern of sea surface temperature anomaly(SSTA) in the previous year of La Nia events,we categorized La Nia events into two types to investigate the different characteristics of tropical cyclone(TC) activity over the western North Pacific(WNP) in TC peak season of two types La Nia events.One type is following the previous El Nio event(La Nia I);the other is following the previous neutral phase or developing La Nia event(La Nia II).Results show that TC genesis frequency in the WNP during TC peak season of La Nia I is less than normal year,whereas it has no differences from normal year during La Nia II.The main reason is attributed to the different amplitude SSTA in the East Indian Ocean(EIO) and the western Pacific Ocean(WPO).Similar to the capacitor effect,strongly positive SSTA in the EIO-WPO during La Nia I triggers an equatorial baroclinic Kelvin wave,which intensifies the easterly in the lower troposphere and weakens the East Asian summer monsoon,and thus the TC frequency decreased during La Nia I.However,the easterly anomaly shows a weak response to the SSTA in the EIO-WPO during La Nia II,and there is no significant change in the environmental pattern over the WNP;so is TC frequency.The modulation of strong EIO-WPO SSTA on large-scale circulation over the WNP reduces the environmental barotropic energy conversion into synoptic-scale disturbances during La Nia I,and also suppresses TC disturbances.The understanding of two different types of La Nia events could help improve the seasonal prediction of TC activity in the WNP during La Nia.  相似文献   
86.
The protection and development problems in ethnic minority villages have received great attention from the Chinese government. This study aims to systematically identify the spatial differentiation characteristics of ethnic minority villages and their influencing factors in Guizhou Province. Applying ArcGIS and GeoDa, a total of 1,014 ethnic minority villages in the four batches announced by the Ethnic and Religious Affairs Commission of Guizhou Province(272in the first batch, 240 in the second ...  相似文献   
87.
Based on the test data in dynamic water and static water, the main factors, which influence the fine sediment flocculation, are analyzed with a gray model method of correlation theory. It is shown that the main influencing factors are water temperature, settling time, salinity, grain size, sediment concentration and current velocity according to the correlation coefficients. Among them, the salinity and the sediment grain size are critical type influencing factors (CrTIF); the settling time, the sediment concentration and the velocity are continuous type influencing factors (CoTIF); and the water temperature has the characteristics of both. When the critical values of CrTIF are reached or exceeded, the fine sediments will be flocculated, but values of CrTIF will not influence the settlement strength of floes. The influence of CoTIF is continuous. The values of the CoTIF will not only influence the occurrence of flocculation but also the settlement strength of the floes.  相似文献   
88.
The Early Cambrian Balang Formation is comprised of mudrock and shale, which was deposited in a shelf environment in the eastern part of Guizhou, south China. The Balang Fauna, which consists of seven phyla, occurs in the middle and upper parts of the Balang Formation. Arthropods are important constituents of the Balang Fauna and include a great number of trilobites, large bivalved arthropods, and newly-discovered well-preserved bradoriid fossils. The bradoriids present include three genera and four species : Comptaluta inflata (Cheng, 1974) emend Hou et al., 2002; Comptaluta kailiensis sp. nov., and Alutella elongeta sp. nov., Aluta sp. This faunal assemblage in the Balang Formation is distinguished from the Tsunyiella Chang, 1964, Songlinella Yin, 1978 and Kunmingella Hou, 1956 assemblage which occurs in the Niutitang and Mingxinsi formations of the Yangtze Platform in middle region of Guizhou and which is earlier than the Balang Formation in age. However, this assemblage resembles the Comptaluta pik, 1968 assemblage from the Early Cambrian Heilinpu Formation in Wuding County, Yuanan Province and from the Ordian Stage of the Cambrian of Australia. The great abundance of Comptaluta pik, 1968 and overall taxonomic diversity of the Comptaluta pik, 1968 assemblage set it distinctly apart from the Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 assemblages of the Balang Formation. Alutella Kobayashi et Kato, 1951 and Aluta Hou, 1956 also occur in the Early Cambrian Niutitang Formation of the Yangtze Platform of Guizhou. Individual Bradoriids from the Balang Formation are characterized by large size (3 mm). The discovery of new Bradoriid assemblages not only expands the group’s geographical range and assemblage affinities, but also indicates that Bradoriids migrated eastward from shallow-water to deeper-water environments during the Early Cambrian, indicating that they were capable of life in deeper-water, and adaptation to a new ecological setting.  相似文献   
89.
Construction of large dams is attractive because of their great benefits in flood control,hydropower generation,water resources utilization,navigation improvement,etc.However,dam construction may bring some negative impacts on sediment transport and channel dynamics adjustments.Due to the effects of recent water and soil conservation projects,sediment retention in the newly constructed large upstream reservoirs,and other factors,the sedimentation in the Three Gorges Reservoir(TGR)is quite different from the amount previously predicted in the demonstration stage.Consequently,based on the measured data,characteristics of sedimentation and the related channel deformation in the TGR were analyzed.The results imply that sediment transport tended to be reduced after the Three Gorges Project(TGP).Sedimentation slowed dramatically after 2013 and indicated obvious seasonal characteristics.Due to the rising water level in the TGR in the flood season,the yearly sediment export ratio(Eratio)was prone to decrease.The water level near the dam site should be reasonably regulated according to the flow discharge to improve the sediment delivery capacity and reduce sedimentation in the TGR,and to try to avoid situations where the flood retention time is close to 444 h.The depositional belt was discontinuous in the TGR and was mainly distributed in the broad reaches,and only slight erosion or deposition occurred in the gorge reaches.Sedimentation in the broad and gorge reaches accounted for 93.8% and 6.2% of the total sedimentation,respectively.The estuarine reach located in the fluctuating backwater area experienced alternate erosion-deposition,with a slight accumulative deposition in the curved reach.Sedimentation mainly occurred in the perennial backwater area.The insight gained in this study can be conducive to directly understanding of large reservoir sedimentation and mechanism of channel adjustment in the reservoir region in the main channel of large river.  相似文献   
90.
Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories,Chinese Academy of Sciences,we collected data from22 dark clear nights and 90 moon nights.We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity.Then with a modified sky brightness model of moon nights and data from these nights,we derived the typical value for several important parameters in the model.With these results,we calculated the sky brightness distribution under a given moon condition for the Xinglong station.Furthermore,we simulated the sky brightness distribution of a moon night for a telescope with a 5 field of view(such as LAMOST).These simulations will be helpful for determining the limiting magnitude and exposure time,as well as planning the survey for LAMOST during moon nights.  相似文献   
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