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101.
随着9210工程系统建设的完成,T106中期数值预报产品分发采用了地面通信系统和卫星通信系统两种传输路径。地面通信系统由于受传输能力限制,国家气象中心根据区域、省,地市级的不同接收能力,采取了3种不同的传输方式以满足各级气象台站的需求; 相似文献
102.
103.
Partial melting during tectonic exhumation of a granulite terrane: an example from the Larsemann Hills, East Antarctica 总被引:23,自引:0,他引:23
C. J. CARSON R. POWELL C. J. L. WILSON & P. H. G. M. DIRKS 《Journal of Metamorphic Geology》1997,15(1):105-126
Anatectic migmatites in medium- to low-pressure granulite facies metasediments exposed in the Larsemann Hills, East Antarctica, contain leucosomes with abundant quartz and plagioclase and minor interstitial K-feldspar, and assemblages of garnet–cordierite–spinel–ilmenite–sillimanite. Qualitative modelling in the system K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2, in conjunction with various P–T calculations indicate that the high-grade retrograde evolution of the terrane was dominated by decompression from peak conditions of c. 7 kbar at c. 800 °C to 4–5 kbar at c. 750 °C. Extensive partial melting during decompression involved the replacement of biotite by the assemblage cordierite–garnet–spinel within the leucosomes. These leucosomes represent the site of partial melt generation, the cordierite–garnet–spinel–ilmenite assemblage representing the solid products and excess reactants from the melting reaction. The extraction and accumulation of this decompression-generated melt led to the formation of syntectonic pegmatites and extensive granitic plutons. Leucosome development and terrane decompression proceeded during crustal transpression, synchronous with upper crustal extension, during a progressive Early Palaeozoic collisional event. Subsequent retrograde evolution was characterized by cooling, as indicated by the growth of biotite replacing spinel and garnet, thin mantles of cordierite replacing spinel and quartz within metapelites, and garnet replacing orthopyroxene and hornblende within metabasites. P–T calculations on late mylonites indicate lower grade conditions of formation of c. 3.5 kbar at c. 650 °C, consistent with the development of late cooling textures. 相似文献
104.
叙述了浅层地下水资源评价中几个常用参数(给水度、降雨入渗补给系数和潜水蒸发系数)的测定和估计方法,并结合实例进行剖析.通过分析,得到几点新的认识:(1)给水度值同注水的方式有关,在实际情况中,由于农田表层土壤疏松,且有作物影响,因而其最大值会出现在地表附近;(2)用抽水试验法测定给水度,其值因孔而异;(3)降雨入渗补给系数与土壤结构和给水度的关系密切,一般随着埋深的增加,该系数随之减小;(4)不同季节和不同作物,潜水蒸发系数不同,表现在计算公式上的参数也不相同. 相似文献
105.
106.
在研究沂蒙矿、蒙山矿等地幔矿物时,新发现了两种Zr-Ti、REE-Ti氧化物矿物。Zr-Ti氧化物新相6个样品点的探针成分分析(wt%):TIO227.756~46.811,ZrO231.724~58.092,TFeo2.75~5.82,CrO31.728~4.765,Nb2O51.353~4.357,Ta2O50.155~2.814,SiO20.894~13.749,主次元素的成分变化幅度均较大,但以氧为4计算的阳离子总数均为2,因此分子式可简写为(Ti,Zr,Si,Fe)2O4或(Ti,Zr)2O4,与人工化合物ZrTiO4相似。REE-Ti氧化物矿物新相的成分也较复杂,主要元素为REE(Ce,Nd,La,Sm,Pr…)及Ti,次要元素有Nb,根据五个样点的探针分析结果,简化的分子式(Ce…)2(Ti…)3O9,与人工化合物Ce2Ti3O8.7类似,属等轴晶系。两个新矿物相均产于蒙山矿中的微裂隙和熔融交代海绵边中,呈斑点状、蠕虫状、微脉状,组成元素复杂,不同颗粒分析点成分有差异,且在同一微脉中成分也有变化,反映了这两种新矿物相是非平衡的交代一结晶产物。从矿物的产出关系和成分的特征来看,它们的形成与地幔流体交代作用有关。 相似文献
107.
本文以等物质的量的反应规则建立了岩盐、芒硝中各种化合物的质量分数的计算公式。这些公式既符合法定计量单位的要求,又方便计算。 相似文献
108.
鹅公山火山盆地受郯庐断裂系影响,NW断裂构造尤为特色:张扭性,倾向NE,右行下滑,对盆地中3个铀矿床及绝大多数铀矿(化)点具明显控制作用,是铀矿成矿的关键要素。研究NW断裂对在鹅公山火山盆地及其它地区找矿都具有实际意义。 相似文献
109.
Donald A. Wilhite 《Natural Hazards》1996,13(3):229-252
Drought is a normal, recurrent feature of climate that affects virtually all countries to some degree. The number of drought-induced natural disasters has grown significantly since the 1960s, largely as a result of increasing vulnerability to extended periods of precipitation deficiency rather than because of an increase in the frequency of meteorological droughts. This increase in drought-induced natural disasters has resulted in a considerable growth of interest in drought mitigation and preparedness worldwide. The purpose of a national preparedness plan is to reduce societal vulnerability to drought through the adoption of preventive, anticipatory policies and programs. This paper describes a ten-step planning process that nations can follow to develop a drought preparedness plan. This process, originally developed in 1987, has been the basis of discussions at training seminars on drought preparedness for developing nations in Africa, Asia, and Latin America. It has also been adopted, with appropriate modifications, by state or provincial governments and by municipalities. The process is intended to be flexible so that governments can add, delete, or modify the suggested steps, as necessary.Published as Paper No. 10946, Journal Series, Nebraska Agricultural Research Division. The work reported here was conducted under Nebraska Agricultural Research Division Project 27-007. This material is based in part upon work supported by the National Science Foundation under Grant ATM-8704050. 相似文献
110.
The Turpan-Harmi (abbreviated to Tuha below) Basin is a typical basin of coal-generated oil accumulation in China. The Middle-Lower
Jurassic coal measures are considered the main source beds. Hence, both desmocollinite and suberinite are considered the contributors
for coal-generated oil. Principal geochemical features of the crude oil in the Tuha Basin are rich in alkanes (70%—80%), high
pristane/phytane ratio (6—8), abundant heavy carbon isotope (δ13C PDB= -26%–-23%) and absolute GP sterane predominance. The hydrocarbon generation process from the coal series is characterized
by multistages, early generation and early expulsion. 相似文献