排序方式: 共有91条查询结果,搜索用时 15 毫秒
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雪峰山加里东造山运动及其体制转换 总被引:17,自引:0,他引:17
本文论述了雪峰山地区加里东造山运动的变形序列,加里东运动期间,至少存在3个连续的构造热事件。并且阐述了挤压体制向伸展体制的转换,形成低角度滑脱带,高角度正断层及变质核杂岩。 相似文献
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西南岩溶山区生态危机与反贫困的可持续发展文化反思 总被引:11,自引:3,他引:8
西南岩溶山区生态环境退化严重、贫困人口集中。文章探讨民族传统文化观念在岩溶山区经济活动中的作用,力图寻找岩溶山区生态恶化和贫困的深层次原因,指出岩溶山区存在的山地文化封闭性和典型的贫困文化特性及不合理的现代性转换导致区域生态恶化和可持续发展的滞后。岩溶山区应通过生态恢复模式示范建设、开展参与式社区资源管理、改善居民聚居点环境来实现文化创新和文化整合,实现传统性与现代性的深层次互动与接纳,拓宽现代性生长的内在精神空间,变外源性的“输血”机制为内源性的“造血”机制,从而使岩溶山区实现可持续发展。 相似文献
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黔北桐梓红花园地区的五峰组是华南地区奥陶系的重要剖面之一,在其以泥质灰岩为特征的五峰组观音桥段下部黑色含炭质钙质页岩和褐色粉砂岩中分别产有较为丰富的双壳类Modiolopsis和腹足类Holopea。产双壳和腹足类的地层中岩性和生物具有差异性,表明观音桥段沉积早期的沉积环境具有多变的特征。横长卵形、较膨凸的Modiolopsis和其两瓣壳相连保存的标本表明为近原地埋藏,为弱水动力、有氧的、较浅水环境的软质基底。丰度较大的低圆锥形Holopea的不规则的壳顶指向指示了具一定水动力的、沙性基底的浅水环境。 相似文献
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With the definition and adoption of the Global Stratotype Section and Point (GSSP) for base of the Visean in China, the newly synthesized zonations and correlation of some significant fossil groups: foraminifera, conodont, coral and brachiopoda near the Tournaisian-Visean boundary beds are reviewed, which help in the recognition of the boundary in various sedimentary facies. The occurrence of two physical events, one pre- and one post- the Tournaisian-Visean boundary is emphasized, which allows for recognition of the position close to the Tournaisian-Visean boundary in the field. The regional correlation in southern China and international correlation throughout Eurasia around the Tournaisian-Visean boundary beds with the GSSP is proposed. 相似文献
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依托某层状围岩深埋铁路隧道工程,以主线单线隧道与横通道正交结构为研究对象,通过ABAQUS建立有限元分析模型.选取12条地震波数据,模拟基岩SV波地震作用,调整地震动峰值加速度和地震动入射方向,对研究结构随地震动输入方向的敏感性进行分析.研究分析得到:二次衬砌在地震入射角度为30°~45°时对地震动方向变化敏感性较低,... 相似文献
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Heterogeneity of Parent Rocks and Its Constraints on Geochemical Criteria in Weathering Crusts of Carbonate Rocks 总被引:1,自引:0,他引:1
WANG Shijie FENG Zhigang Institute of Geochemistry Chinese Academy of Sciences Guiyang Guizhou Graduate School Chinese Academy of Sciences Beijing 《《地质学报》英文版》2004,78(5):1143-1153
Owing to the low contents of their acid-insoluble components, carbonate rocks tend to decrease sharply in volume in association with the formation of weathering crust. The formation of a 1 m-thick weathering crust would usually consume more than ten meters to several tens of meters of thickness of parent rocks. The knowledge of how to identify the homogeneity of parent rocks is essential to understand the formation mechanism of weathering crust in karst regions, especially that of thick-layered red weathering crust. In this work the grain-size analyses have demonstrated that the three profiles studied are the residual weathering crust of carbonate rocks and further showed that there objectively exists the heterogeneity of parent rocks in the three studied weathering crusts. The heterogeneity of parent rocks can also be reflected m geochemical parameters of major elements, just as the characteristics of frequency plot of grain-size distribution. Conservative trace element ratios Zr/Hf and Nb/Ta are proven 相似文献