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931.
932.
Employing long‐range correlation, complexity features and clustering, this study investigated the influence of dam and lake‐river systems on the Yangtze River flow. The impact of the Gezhouba Dam and the lake systems on streamflow was evaluated by analysing daily streamflow records at the Cuntan, the Yichang and the Datong station. Results indicated no evident influence of the Gezhouba Dam on streamflow changes. Distinct differences in scaling behaviour, long‐range correlation and clustering of streamflow at the Datong station when compared with those at the Cuntan and Yichang stations undoubtedly showed the influence of water storage and the buffering effect of the lake systems between the Datong station and other two hydrological stations on streamflow in the lower Yangtze River basin. Decreased regularity, enhanced long‐range correlation and increased clustering of streamflow in the lower Yangtze River basin due to the effect of water storage of the lake systems were corroborated. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
933.
Yu Changmin 《《地质学报》英文版》1990,3(1):69-79
Abstract This paper presents a comprehensive evaluation on the Devonian-Carboniferous Boundary (DCB) section in Nanbiancun, Guilin, Guangxi on the basis of Palaeontological, biostratigraphical and sedimentary petrological studies as well as microfacies analysis, REE and trace element analysis and isotopic dating. The DCB at this section conforms to the definition of this boundary and essentially measure up the criteria and conditions for selection of the boundary stratotype. Up to 14 fossil groups are contained in the section. The section presents a general biostratigraphical framework with multispecies fossils zones, assemblage zones and multiple groups of fossils and has latent preponderant conditions for magnetostratigraphic and chronostratigraphic studies. The boundary and point occur in a persistent and continuous monofacial carbonate succession, and the section is located in a tourist city with convenient communication, where various facies of DCB sections are developed, allowing the correlation within a small area. So it is an ideal candidate boundary stratotype. 相似文献
934.
Methodology is described in this paper for investigating biotite reactions in pneumatolyto-hydrothermal solutions rich in
Na, F and Li by using tow buffer systems, NNO and CFG. The results show: (1) Under the experimental conditions biotite is
unstable and different new stable phases will be formed, depending upon the fugacity of oxygen. Na-rich minerals, such as
aegirine and albite, will be produced at low oxygen fugacity, while Li-rich micas are found stable at high oxygen fugacity.
This agrees with the field observation that albitization occurs in general at a lower position than that of Li-rich micas,
suggesting that alkalimetasomatism of biotite may provide the necessary components for subsequent reactions. (2) The stability
of Li-rich micas is dependent on Mg2+ concentration in the medium, which in turn is determined by Mg2+ content in the starting biotite. Li-rich micas are favored by metasomatism of only those biotites that are poor in Mg2+. (3) Unstability of biotite would favor the incorporation of ore-forming elements contained in it as isomorphous impurities
into solutions. 相似文献
935.
936.
937.
通过对桃山、诸广复式岩体的深入研究,得出铀、钍元素在本地区花岗岩中具有以下地球化学特征及地球化学行为:1.岩体的铀、钍丰度与岩体外接触带的变质岩铀,钍丰度具同步增长特点;2.铀与硅、钾、钠关系密切,并有随钾增长,及随铀增长二种趋势,而钍则与TiO_2、FeO、MnO关系密切;3.钍在花岗岩中分布型式为正态分布,变异系数较铀小,而铀在花岗岩中分布型式为正态分布及对数正态分布,变异系数略高,显示了铀有某种富集可能;4.铀在花岗岩中地球化学行为,表现有二个富集高峰,既有在结晶早期富集在各类副矿物中的早富集特征,也有随花岗岩形成和演化富集在晚期的晚富集特征。二个富集途径,即随Si、K增高和随Si、Na增高途径。 相似文献
938.
用扫描电子显微镜研究晋东南太原组下部黄铁矿矿石和煤岩中的黄铁矿,发现许多原始莓体保留着形成时的特征。这些特征反映出原始莓体大多数为硫磺细菌化石,少数由胶体形成。本文对莓体的成因、特征、形成环境等进行了论述。 相似文献
939.
本文在邓肯-张模型进行深入探讨的基础上,提出了切线模量实质物理意义是剪切模量的观点,并分别采用应力法和应变法推导了剪切模量和体积模量(或变形模量)公式,还进行了考虑Biot固结非线性弹性油罐地基有限元实例分析。对不同的变形模量计算方法进行了比较,提出了改进的非线性弹性模型。 相似文献
940.
NumericalModellingoftheEffectsofOzoneontheSummerAtmosphericCirculationWangQianqian(王谦谦);WangYinhui(汪迎辉);SongYu(宋煜)(Naminginst... 相似文献