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吕梁山前寒武纪变质杂岩位于华北克拉通中部带中段西侧。其中野鸡山群位于该杂岩的中西部,呈NNE-SSW向狭长带状展布。野鸡山群的底部保存了变质的滨海-浅海相的砾岩和粗砂岩,中部主体岩性为变质玄武岩和玄武质安山岩,保存了良好的枕状构造,发育同期辉长岩浅成侵入体,并有少量的变质安山岩、英安岩和流纹岩。变质火山岩之上发育了良好的薄层状复理石沉积,记录了深水海相火山喷发和沉积特征。复理石之上以角度不整合沉积了河流相砾岩和含砾砂岩。岩石化学分析表明,野鸡山群火山岩有右斜式稀土配分模式,稀土总量在101×10-6~240×10-6范围内, (La/Yb)N比值在6~13之间变化。随着SiO2的增加(La/Yb)N和负Eu异常明显增加。在原始地幔标准化的蛛网图上,所有的岩石都表现了明显的Nb、Ta、Sr、P、Ti负异常。岩石成因研究揭示这套变质火山岩组合的原始岩浆导源于成分相当于尖晶石二辉橄榄岩与石榴石二辉橄榄岩大约以等量混合地幔源区的低度部分熔融。岩浆演化过程中经历了单斜辉石和少量斜长石的分离结晶,并在上升过程中受到了地壳物质的混染。综合地质学、岩石学和地球化学研究,结合前人的Sm-Nd同位素研究成果,野鸡山群变质火山岩组合最有可能形成于大陆边缘岛弧的弧后靠近岛弧一侧的构造背景,其形成可能与古元古代晚期洋壳俯冲作用有关。  相似文献   

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Stamps convey important visible messages about a state’s heritage and worldview. They are images or official visible products seen by those living within the state’s borders and those beyond. They also can be considered as “imagined communities,” as like festivals, holidays, or WWW pages, they represent attachments to and images of place. We investigate stamps as elements of visual culture by examining salient music themes and topics from several countries and then focus on the music stamps of Brazil, Hungary, and Senegal. In each case, we examine the number and variety of issues, the importance they place on musical instruments, composers and performers, and musical events.  相似文献   

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The author deals with the vegetation of the Himalayas taking his 1957 map as basis of the presentation. This map by way of vegetation first opened insigh into the hitherto unknown landscape structure of the mountain system, thereby revealing, for instance, the phenomeon of the inner valleys and the climatically dry valleys, in particular as well as the areas vegetationwise still unknown. Progress in our knowledge of the vegetation in the Himalayas since publication of the 1957 map is carefully recorded showing, above all, the advancement of our knowledge in Nepal since. In contrast to expectations, research was unable to concentrate on all the gaps in our knowledge as demonstrated on the 1957 map owing to political conditions prevailing.  相似文献   

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Over a continental area, the sediments are mostly found, either asoriginally spread by water along the slopes (gravels or loams: fan-deposits), or as accumulated by streams in the bottom of the basins(lake-deposits, or fluvial plains), either as disseminated by wind (sand-dunes and loess deposits).  相似文献   

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史洪岳 《地质论评》2000,46(4):393-399
地质作用、地质环境、医药矿产与人类生存、健康的关系极为密切,建立和发展医药地质学有利于科学、系统、深入地探究其内在关系,促进地质学在生命科学中发挥就有的作用。医药地质学建立的思想基础是人地同一理论,实践基础是药用矿产在人类防病,治病和保健中的广泛应用及科学研究,技术支撑是无机、有机成分的微区、微量等现代测试、分析技术的进步。本文论述了医药地质及其建立的基础,展示了医药地质学在地质学和生命科学发展中  相似文献   

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In January 1986 the spaceprobe Voyager-2 revealed details of the surfaces of the icy satellites of Uranus for the first time, including grabens, other faulted features, impact craters and possible ice flows. Despite their apparent similarity to some of the moons of Jupiter and Saturn, they highlight many new questions as to the evolution of, and interactions between, such bodies.  相似文献   

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城市地质学理论研究   总被引:2,自引:0,他引:2  
本文在系统研究国内外城市地质学理论研究与工作实践基础上,系统分析并拓展了城市地质学的内涵与外延;根据城市可持续发展的需求,提出了保证城市不同发展阶段地质安全是城市地质学理论研究的根本任务和永恒主题;明确提出了城市地质学研究的三个科学问题,即城市选址安全底限问题、城市发展规模上限问题、城市发展可持续性问题;由此构建了区域地质条件适宜性评价、地质资源环境承载力评价、城市地质作用研究,三方面的城市地质学理论体系。  相似文献   

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刘家仁 《贵州地质》2004,21(2):137-139,F002
最近,地球的近邻——火星成了一颗耀眼的新闻明星,各种媒体争相报道有关火星上发现水的新闻。在火星上发现水,是天体地质学研究的最新进展。天体地质学,又称为宇宙地质学、行星地质学、行星地球科学,是运用地质学原理和技术来研究行星及其卫星、彗星和小行星等凝聚态天体的性质、  相似文献   

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Brian D. Bornhold 《Earth》1996,40(3-4):306-307
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