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21.
This paper describes studies on the integrated risk assessment and zoning of meteorological disaster in Heilongjiang Province,in northeastern China,by using information-diffusion theory and cluster method with 35 years of summer temperature and precipitation data from 74 meteorological stations from 1971 through 2005.The information-diffusion theory has been used extensively in risk assessment,yet almost no one has done research about risk assessment by information-diffusion theory based on meteorological disaster standards.Some research results are as follows:the risk probability of low temperature and cold damage in the northern region is higher than that in the southern region;the risk probability of general low temperature and cold damage in the southwestern region is the highest;the risk probability of serious low temperature and cold damage in the northern region is the highest,followed by the central and southeast region;the high-risk region of arid disaster in Heilongjiang Province was primarily located in the southwestern,central,and southern parts of the province;the high-intensity arid disaster was located in the south-eastern region;the high-risk region of flood in Heilongjiang Province was primarily located from the southwest and then across the central part to the western part of Heilongjiang Province;the high-intensity flood disasters were located in almost every part of Heilongjiang Province.We can conclude from the integrated meteorological disaster risk zoning that the high-risk region of mete-orological disaster is primarily located in the southern and northern part of the province,the moderate-risk region is distributed in the central southern region and western region,the low-risk region is located in the eastern part,and the light-risk region is located in the central western part of Heilongjiang Province. 相似文献
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Lakes regulate the water and heat exchange between the ground and the atmosphere on different temporal and spatial scales. However, studies of the lake effect in the high-altitude Tibetan Plateau(TP) rarely have been performed until recently, and little attention has been paid to modelling of frozen lakes. In this study, the Weather Research and Forecasting Model(WRF v. 3.6.1) is employed to conduct three numerical experiments in the Ngoring Lake Basin(the original experiment, an experiment with a tuned model, and a no-lake experiment) to investigate the influences of parameter optimization on the lake simulation and of the high-altitude lake on the regional climate. After the lake depth, the roughness lengths, and initial surface temperature are corrected in the model, the simulation of the air temperature is distinctly improved. In the experiment using a tuned model, the simulated sensible-heat flux(H) is clearly improved, especially during periods of ice melting(from late spring to early summer) and freezing(late fall). The improvement of latent-heat flux(LE) is mainly manifested by the sharp increase in the correlation coefficient between simulation and observation, whereas the improvement in the average value is small. The optimization of initial surface temperature shows the most prominent effect in the first year and distinctly weakens after a freezing period. After the lakes become grassland in the model, the daytime temperature clearly increases during the freezing and melting periods; but the nocturnal cooling appears in other stages, especially from September to October. The annual mean H increases by 6.4 times in the regions of the Ngoring Lake and the Gyaring Lake, and the LE declines by 56.2%. The sum of H and LE increases from 71.2 W/m2(with lake) to 84.6 W/m2(no lake). For the entire simulation region, the sum of H and LE also increases slightly. After the lakes are removed, the air temperature increases significantly from June to September over the area corresponding to the two lakes, and an abnormal convergence field appears; at the same time, the precipitation clearly increases over the two lakes and surrounding areas. 相似文献
23.
江西宁冈岩体的形成时代、地球化学特征及其构造意义 总被引：14，自引：1，他引：13
宁岗岩体是湘赣交界部位呈南北向展布的加里东花岗岩带的重要组成部分,它主要由二长花岗岩组成。锆石LA-ICPMS U-Pb年龄为433.8±2.2Ma,属于加里东期岩浆活动产物。虽然宁冈岩体的SiO2含量变化明显(67.46%~74.85%),但它们的ACNK值都大于1.1,钾大于钠(K2O/Na2O=1.36~2.37),CaO/Na2O比值大于0.3,富集Rb、Th、Cs,亏损Nb、Ta、Ba、Sr,LREE富集 (LREE/HREE=5.8~12.2)和Eu亏损相对明显(δEu=0.28~0.61)。同时,它们还具有较低的εNd(t)值(-9.3~-8.6)、较高的(87Sr/86Sr)i值(0.71172~0.71937)和古老的Nd模式年龄(1838~1909Ma)。这些特征表明,宁冈岩体属于典型的壳源型花岗岩,很可能是在华夏古陆残块与扬子地块之间发生陆-陆碰撞拼贴而引发的地壳伸展-减薄的构造背景下, 通过砂质岩石部分熔融的方式形成。 相似文献
24.
Global climate change has been evident in many places worldwide. This study provides a better understanding of the variability and changes in frequency, intensity, and duration of temperature, precipitation, and climate extremes in the Extensive Hexi Region, based on meteorological data from 26 stations. The analysis of average, maximum, and minimum temperatures revealed that statistically significant warming occurred from 1960 to 2011. All temperature extremes displayed trends consistent with warming, with the exception of coldest-night temperature(TNn) and coldest-day temperature(TXn), which were particularly evident in high-altitude areas and at night. Amount of precipitation and number of rainy days slowly increased with no significant regional trends, mainly occurring in the Qilian Mountains and Hexi Corridor. The significance of changes in precipitation extremes during 1960–2011 was high, but the regional trends of maximum 5-day precipitation(RX5day), the average precipitation on wet days(SDII), and consecutive wet days(CWD) were not significant. The variations in the studied parameters indicate an increase in both the extremity and strength of precipitation events, particularly in higher-altitude regions. Furthermore, the contribution from very wet precipitation(R95) and extremely wet precipitation(R99) to total precipitation also increased between 1960 and 2011. The assessment of these changes in temperature and precipitation may help in developing better management practices for water resources. Future studies in the region should focus on the impact of these changes on runoffs and glaciers. 相似文献
25.
红山含黄玉花岗岩的形成时代及其成矿能力分析 总被引：10，自引：1，他引：10
对闽西南红山含黄玉花岗岩进行了LAM-ICPMS锆石U-Pb定年以及地球化学对比研究。地球化学分析显示红山花岗岩具有富F和高演化的地球化学特征,富含稀有和有色金属成矿元素,如Sn含量为(15·3~54·0)×10-6,W含量(3·04~14·9)×10-6,Nb含量为(22·5~36·7)×10-6,Ta含量为(3·37~7·31)×10-6,U、Th含量分别(6~30)×10-6和(12·1~36·4)×10-6。与含矿花岗岩的对比研究表明红山花岗岩很可能存在与之有成因联系的Sn、U矿床。地球化学填图显示了元素在空间上的分带变化,指出与红山花岗岩有关的成矿作用最可能发生在岩体的东南端,即116°8′E~116°10′E和25°29′N~25°32′N的区域。锆石U-Pb定年结果表明红山花岗岩形成于印支期(~226Ma),因此,其在形成时代、地质产状和成矿作用上不同于华南大多数形成于燕山晚期的含黄玉花岗质岩石。南岭基底变质岩富含W、Sn、Nb、Ta等成矿元素,它们是华南(特别是南岭地区)含矿花岗岩中成矿元素富集的最主要物质来源。 相似文献
26.
新疆希勒库都克铜钼矿床硫同位素特征及成矿物质来源探讨 总被引：3，自引：2，他引：1
位于东准噶尔北缘的希勒库都克铜钼矿床是一个以钼为主的斑岩型矿床,形成于早石炭世。希勒库都克铜钼矿床硫化物δ34S值介于+0.4‰~+7.6‰之间,平均为+4.1‰,其中黄铁矿δ34S值为+0.4‰~+7.6‰(平均+4.2‰)、辉钼矿δ34S值为+3.2‰~+4.7‰(平均+4.2‰)、黄铜矿δ34S值为+1.6‰~+2.5‰(平均+2.1‰),均显示出岩浆硫的组成特征。硫化物稀土元素特征与含矿斑岩类似,暗示成矿物质可能来源于含矿斑岩;流体包裹体地球化学及H-O同位素特征也表明成矿流体主要来自岩浆热液。而含矿斑岩高的正εNd(t)值、低的87Sr/86Sr初始比值表明含矿岩浆可能主要来自于地幔源区。综合研究区硫化物硫同位素、稀土元素及流体包裹体地球化学特征等分析,本文认为希勒库都克铜钼矿床成矿物质主要来自地幔源区,且含矿岩浆可能经历了地壳深部壳幔物质混合均一化的过程。 相似文献
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28.
西藏甲玛矿区角岩特征及其对深部找矿的意义 总被引：11，自引：2，他引：9
角岩是西藏甲玛铜多金属矿床近年来钻探工作大量揭露的赋矿围岩之一,其中蕴藏的钼铜资源量已达大型以上规模,不但为甲玛增加资源量提供了新的保障,而且在矽卡岩型和斑岩型之外增加了一种新的矿石类型。但角岩的研究相对薄弱,对其在深部找矿方面的研究更是空白。本文通过对甲玛角岩基本特征的研究,归纳了角岩的空间分布,分析了角岩的物质组成,结合角岩中裂隙的统计结果,推测了深部岩体的中心位置,为深部找矿提出了建议。认为甲玛矿区角岩分布广但厚度不均匀,以ZK3218钻孔最厚(达1027m),向周围逐渐减薄,到矿区西南角和西端多个钻孔中尖灭。角岩型矿体以辉钼矿和黄铜矿为主,ZK3217钻孔中矿体厚达900m,紧邻ZK3218钻孔,矿化普遍,但品位较矽卡岩低。角岩中裂隙统计表明,在ZK1616至ZK3216一带,裂隙密度达40条/米以上,向周围减少。综合角岩的岩石学、矿物学和地球化学等特征, 认为甲玛矿区为角岩提供热源的深部岩浆分布在ZK3216-ZK3217-ZK3218一带,建议布置深钻,深部可能存在矽卡岩型矿体和斑岩型矿体。 相似文献
29.
峨眉山大火成岩省虎跳峡和金安二叠纪玄武岩的地球化学特征及其对源区的约束 总被引：1，自引：1，他引：0
本文对虎跳峡苦橄岩和玄武岩及金安玄武岩的地球化学特征进行了研究。结果表明其微量元素原始地幔标准化曲线、Sr-Nd-Pb同位素比值与OIB、丽江苦橄岩相似,表现为其大离子亲石元素相对高场强元素富集,并且不存在Nb、Ta和Ti的负异常,表明岩浆在上升过程中很少受到岩石圈地幔或地壳物质的混染。利用Klein and Langmuir（1987）的方法得出虎跳峡熔岩和金安玄武岩原始岩浆MgO含量分别为15.81%~20.89%和8.06%~13.84%,其相应的地幔温度分别为1493~1611℃和1055~1474℃。所得温度略高于正常软流圈地幔温度,低于丽江仕满苦橄岩的熔融温度（1630~1680℃）,推测丽江地区可能是峨眉山地幔柱的中心部位。 相似文献
30.
Recent advances in precipitation-bias correction and application 总被引：1，自引：0，他引：1
Significant progresses have been made in recent years in precipitation data analyses at regional to global scales. This paper re-views and synthesizes recent advances in precipitation-bias corrections and applications in many countries and over the cold re-gions. The main objective of this review is to identify and examine gaps in regional and national precipitation-error analyses. This paper also discusses and recommends future research needs and directions. More effort and coordination are necessary in the determinations of precipitation biases on large regions across national borders. It is important to emphasize that bias cor-rections of precipitation measurements affect both water budget and energy balance calculations, particularly over the cold regions. 相似文献