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151.
152.
Based on 1961-2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a "vapor transition belt", vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient -0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5o-32.5oN) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas. 相似文献
153.
孟津县2004~2005年冬季持续低温和春季寒流,使小麦遭受冬、春季双重冻害.通过调查小麦冻害苗情,结合气象要素资料分析,找出了小麦冻害的主要影响因素,并制定出消除或减缓冻害的技术措施. 相似文献
154.
山西临汾盆地近期地震活动性分析 总被引:1,自引:0,他引:1
通过对临汾盆地内近期地震活动频度和地震活动图像的分析,认为未来中强地震最有可能发生在近期地震活动较稀少的地段,能量积累的优势层位为5km~15km。 相似文献
155.
Thermodynamic conditions of framework grain dissolution of clastic rocks and its application in Kela 2 gas field 总被引:2,自引:2,他引:2
LAI Xingyun YU Bingsong CHEN Junyuan CHEN Xiaolin LIU Jianqing MEI Mingxiang JING Weiguang & CHENG Suhua School of Earth Sciences Mineral Resources China University of Geosciences Beijing China Key Laboratory of Lithospheric Tectonics Deep-level Process Exploration of Ministry of Education Beijing China 《中国科学D辑(英文版)》2005,48(1):21-31
Feldspar and clastic debris are the most important constituent framework grains of sedimentary clastic rocks and their chemical dissolution plays an essential role in the formation and evolution of the secondary pore in the reservoir rocks. On the basis of thermodynamic phase equilibrium, this study investigates the chemical equilibrium relationships between fluid and various plagioclase and K-feldspar in diagenesis of the sediments, particularly, the impact of temperature and fluid compositions (pH, activity of K+, Na+, Ca2+ and so on) on precipitation and dissolution equilibria of feldspars. Feldspar is extremely easily dissolved in the acid pore water with a low salinity when temperature decreases. The dissolution of anorthite end-member of plagioclase is related to the Ca content of the mineral and the fluid, higher Ca either in the mineral or in the fluid, easier dissolution of the feldspar. Moreover, the dissolution of albite end-member of plagioclase is related to Na of both the mineral and fluid, 相似文献
156.
天津蓟县中元古界高于庄组中臼齿状构造的层序地层位置及其成因的初步研究 总被引:18,自引:11,他引:18
天津蓟县剖面的中元古界高于庄组为一套厚度约为1 600m的碳酸盐岩地层,包括四个段:第一段以潮坪相叠层石白云岩为主;第二段主要为含锰白云岩;第三段发育较多的纹理化石灰岩和泥晶灰岩;第四段则以叠层石岩礁(叠层石生物丘和生物层)的发育为特点。根据岩相到岩相序列可在该套碳酸盐岩地层中识别出L-M型、潮下型、环潮坪型米级旋回层序。根据米级旋回层序的有序垂直叠加形式所反映出的沉积相序列可以把高于庄组划分为13个三级层序(SQ1至SQ13),并进一步归为4个二级层序。在以灰岩为主的高于庄组第三段中,其中的第三个三级层序(SQ11)中部的灰岩层中发育臼齿状构造。这种臼齿状构造以特别的形态、富含有机质、易硅化等特点可能表明了前寒武纪碳酸盐岩沉积作用的一些基本特征:第一、在浅水环境中发育叠层石而在较深水环境(中缓坡)中发育臼齿状构造,臼齿状构造就象叠层石一样是一种极为特别的与生物沉积作用相关的沉积构造;第二、在发育叠层石的潮坪环境中有利于发生白云石化作用,发育臼齿状构造的地层则以灰岩为主,这从一个侧面反映了前寒武纪白云岩似乎又不是原生白云岩。实际上,这些特征本身即代表了一些前寒武纪沉积学问题,随着研究的深入对这些问题将会得出更加接近自然事实的答案。 相似文献
157.
HU Baoqun LU Guxian WANG Fangzhang SUN Zhanxue LIU Chengdong BAI Lihong 《大地构造与成矿学(英文版)》2005,29(2):128-138
1 Introduction The pressure, a scalar quantity, is defined as P = F/S (F is force, S is the area for F) which can be widely used for both solid and fluid. The formula P = g ρh (g-gravitation acceleration,ρ-density, h-depth) is only used for even density static solid and fluid. The delivery of pressure in the fluid follows the law of Pascal, and the average pressure of uneven density fluid can be calculated with the formula of P = g ρh. The temperature influence on pressure is notHU Ba… 相似文献
158.
Mineralogy and geochemistry of a Late Permian coal in the Dafang Coalfield, Guizhou, China: influence from siliceous and iron-rich calcic hydrothermal fluids 总被引:16,自引:2,他引:16
Shifeng Dai Chen-Lin Chou Mei Yue Kunli Luo Deyi Ren 《International Journal of Coal Geology》2005,61(3-4):241-258
This paper describes the influence of siliceous and iron-rich calcic low-temperature hydrothermal fluids (LTHF) on the mineralogy and geochemistry of the Late Permian No. 11 Coal (anthracitic, Rr=2.85%) in the Dafang Coalfield in northwestern Guizhou Province, China. The No. 11 Coal has high contents of vein ankerite (10.2 vol.%) and vein quartz (11.4 vol.%), with formation temperatures of 85 and 180 °C, respectively, indicating that vein ankerite and vein quartz were derived from low-temperature calcic and siliceous hydrothermal fluids in two epigenetic episodes. The vein quartz appears to have formed earlier than vein ankerite did, and at least three distinct stages of ankerite formation with different Ca/Sr and Fe/Mn ratios were observed.The two types of mineral veins are sources of different suites of major and trace metals. Scanning electron microscope and sequential extraction studies show that, in addition to Fe, Mg, and Ca, vein ankerite is the dominant source of Mn, Cu, Ni, Pb, and Zn in the coal, and the contents of these five elements are as high as 0.09% and 74.0, 33.6, 185, and 289 μg/g, respectively. In contrast, vein quartz is the main carrier mineral for platinum-group elements (PGEs) Pd, Pt, and Ir in the coal, and the contents of Pd, Pt, and Ir are 1.57, 0.15, and 0.007 μg/g, respectively. Sequential extraction showed a high PGE content in the silicate fraction, up to 10.4 μg/g Pd, 1.23 μg/g Pt, and 0.05 μg/g Ir, respectively. It is concluded that the formation of ankerite and quartz and the anomalous enrichment of trace elements in the No. 11 Coal in the Dafang Coalfield, Guizhou, result from the influx of calcic and siliceous low-temperature hydrothermal fluids. 相似文献
159.
太原盆地地下水资源模拟研究 总被引:1,自引:0,他引:1
山西省太原盆地由于地下水长期超采,引发了地下水降落漏斗、地面沉降等环境地质问题。通过GMS建立地下水水流三维数值模型,基于模型预测了现状开采条件下地下水水位的变化趋势,并提出合理利用地下水资源的措施,为地下水资源的优化管理提供科学依据。 相似文献
160.