相山、下庄铀矿田稀土元素特征及示踪研究     

张国玉  王生忠  王正其  梁良 《华东地质学院学报》2007,30(1):9-14

相山、下庄两个铀矿田主要赋矿围岩的稀土元素特征极具相似性,显示出壳源型的特点。但它们的矿石稀土元素特征有很大的不同,相山铀矿田矿石稀土元素特别是重稀土元素含量与铀含量呈正相关,负铕异常和围岩相同。而下庄铀矿田矿石亏损稀土元素尤其是轻稀土元素,负铕异常比围岩更强烈,与幔源辉绿岩、正长岩的稀土元素分布模式相近。两矿田矿石稀土元素含量上存在明显差异的同时,都具有比其围岩LREE/HREE比值大幅度降低的特点。结合区域地质演化,认为两铀矿田矿石稀土元素具有不同的特征,但成矿流体都具有幔源性质,矿床都是在白垩—第三纪地壳拉张环境下形成的。  相似文献   

河南汝阳王坪西沟铅锌矿床地球化学特征   总被引：2，自引：0，他引：2  

刘永春  瓮纪昌  班宜红  郭锐  王文娟  刁爱国  付治国 《物探与化探》2007,31(3):205-210

通过对河南汝阳王坪西沟大型铅锌矿床地球化学特征的分析研究，揭示了利用土壤化探作为有效手段，发现并查明铅锌矿床的基本思路。同时证实，土壤化探在铅锌找矿方面效果是好的。通常，主要工业铅锌矿体均限制在Pb、Zn、Ag、Cu组合异常的外边缘以内，而且其成矿母岩等主成矿元素Pb、Zn只要大于涂和费及维诺格拉多夫值有关中性岩Pb含量2．5倍、Zn丰度值2倍以上，均可列入与找矿有利的原生晕异常。  相似文献   

四川黑水徐古锰矿床成矿地质特征及找矿标志   总被引：3，自引：0，他引：3  

周兵  张成江  黄昌华  张厚亮 《四川地质学报》2007,27(4):255-258

四川黑水徐古锰矿位于日嘎希—瓦钵梁子复背斜西段北翼。铁锰矿赋存于下三叠统菠茨沟组浅海相泥质—碳酸盐类的混合沉积物中,地层、岩性控矿明显。矿体呈层状、似层状产出,沿走向、倾向延伸比较稳定。属沉积变质类型,具有7种找矿标志。  相似文献   

高地震烈度区堆积体边坡动力响应时程特征分析   总被引：10，自引：0，他引：10  

周永江  王开云  符文熹  何江达 《山地学报》2007,25(1):93-98

考虑到在地震过程中,工程边坡的动安全系数最小值出现在某一瞬间,而用这个值评价边坡在地震荷载作用下的抗滑稳定性不合适宜。在简单分析地震荷载作用下边坡稳定性评价的主要方法及差异基础上,介绍了地震动力响应时程分析法的基本原理和计算过程,明确指出了边坡动力稳定分析时应注意的边界条件、材料参数等问题,建立了评价动力稳定性的有限元应力法表达式。基于地震动力时程反应,结合金安桥水电站库岸堆积体边坡工程,用动力有限元计算获得了边坡的动力响应在空间的变化规律(包括动应力和加速度等)和整体稳定性,计算成果合理地评价了其稳定性。  相似文献   

斑岩铜矿若干问题的最新研究进展   总被引：8，自引：1，他引：8  

姚春亮  陆建军  郭维民  袁林  李伟 《矿床地质》2007,26(2):221-229

斑岩铜矿是最重要的铜矿床类型,对其成矿作用的认识对找矿实践具有重要指导意义,为此,文章通过收集和整理有关文献总结了近年来斑岩铜矿研究在构造和岩浆对成矿作用的控制、成矿金属和成矿流体来源、矿石伴生金属组分含量的影响因素等方面所取得的成果。近几年的研究工作揭示:斑岩铜矿的大规模成矿作用与洋壳高浮力块体(包括无震海岭和洋底高原)的俯冲有关,高氧逸度的岩浆活动有利于斑岩铜矿的形成,与无矿斑岩体相比,含铜斑岩体一般具有低稀土元素含量以及亏损Ho和Er等特征;斑岩铜矿中铜和金多由俯冲洋壳所释放的流体对地幔中硫化物的氧化作用释放而来;在部分斑岩铜矿中,岩浆来源流体可构成绢英岩化期流体的主体;斑岩铜矿伴生金属组分的含量受许多因素控制,其中包括岩浆源区地幔演化、火成岩岩石类型、岩浆侵位深度和成矿温度等多个方面。部分研究成果应作为找矿标志在实践中运用。  相似文献   

Environmental changes in the northern Altai during the last millennium documented in Lake Teletskoye pollen record   总被引：1，自引：0，他引：1  

Andrei A. Andreev  Roberto Pierau  Ivan A. Kalugin  Andrei V. Daryin  Lyubov G. Smolyaninova  Bernhard Diekmann 《Quaternary Research》2007,67(3):394-399

A high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.  相似文献   

REE geochemical characteristics of the No. 302 uranium deposit in northern Guangdong, South China   总被引：1，自引：0，他引：1  

ZHANG Guoquan HU Ruizhong BI Xianwu FENG Haisheng SHANG Pengqiang TIAN Jianji 《中国地球化学学报》2007,26(4):425-433

The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The result showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites. It is indicated that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation.  相似文献   

张衡地动仪的失传   总被引：4，自引：1，他引：4  

武玉霞  朱涛 《中国地震》2007,23(1):93-103

0引言随着国际交流的日益扩大,世界上更多的人注意到了中国的张衡和他创制的地动仪。这不仅是因为它的出现比西方的验震器(1703年Feuille、1747年Cirillo、1751年Bina、1784年Cavalli等仪器)早约1600年(Dewey等,1969),是人类第一台地震仪器,还因为它成功地测到了公元134年的陇西地震,首开人类测震记录之先河(“京师学者咸怪其无征,后数日驿至,果地震陇西”《后汉书.张衡传》)。目前,张衡地动仪的研究已经国际化,国内外取得的一些新成果,修正、更新和弥补了早期研究中的一些内容和缺憾。主要体现在以下几个方面:(1)长期宣传的地动仪曾经检…  相似文献   

Simplified seismic design approach for steel portal frame piers with hysteretic dampers     

Zhiyi Chen  Hanbin Ge  Akira Kasai  Tsutomu Usami 《地震工程与结构动力学》2007,36(4):541-562

A simplified seismic design procedure for steel portal frame piers installed with hysteretic dampers is proposed, which falls into the scope of performance‐based design philosophy. The fundamental goal of this approach is to design a suite of hysteretic damping devices for existing and new bridge piers, which will assure a pre‐defined target performance against future severe earthquakes. The proposed procedure is applicable to multi‐degree‐of‐freedom systems, utilizing an equivalent single‐degree‐of‐freedom methodology with nonlinear response spectra (referred to as strength‐demanded spectra) and a set of formulae of close‐form expressions for the distribution of strength and stiffness produced in the structure by the designed hysteretic damping devices. As an illustrative example, the proposed procedure is applied to a design of a simple steel bridge pier of portal frame type with buckling‐restrained braces (one of several types of hysteretic dampers). For the steel portal frame piers, an attempt is made to utilize not only the displacement‐based index but also the strain‐based index as pre‐determined target performance at the beginning of design. To validate this procedure, dynamic inelastic time‐history analyses are performed using the general‐purpose finite element program ABAQUS. The results confirm that the proposed simplified design procedure attains the expected performance level as specified by both displacement‐based and strain‐based indices with sufficient accuracy. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

诗经日食及其天文环境     

刘次沅  周晓陆 《时间频率学报》2002,25(1):74-80

《诗经 .小雅》明确记载了发生于十月辛卯的日食 ,其时代和地域背景也比较清楚。但是精确的现代天文计算却找不到对应的事件。对公元前 8- 6世纪的全部辛卯日食、厉王至幽王时代的全部十月日食以及相关的天文因素进行了全面的计算和讨论 ,以期对史学界关于文献背景的讨论提供帮助。  相似文献