1996年2月3日云南丽江7.0级地震发生的构造环境   总被引：7，自引：1，他引：7       下载免费PDF全文

韩竹军  虢顺民  向宏发  张家声  冉勇康 《地震学报》2004,26(4):410-418

作为1996年丽江7.0级地震的发震断层，丽江——大具断裂可以分为丽江——玉湖和玉湖——大具等南北两段. 它们在构造表现、运动方式等方面都存在明显差异，但都表现出比较一致的运动学性质，即既具有垂直正断运动，又有水平左旋走滑运动. 这种运动特征开始于第四纪初期（距今2.4～2.5 Ma）. 在构造形式上，早更新世时期发育低倾角拆离断层；中更新世（0.8 Ma）以来，以高角度正断层活动为主. 根据源于玉龙——哈巴雪山东麓的一系列冲沟, 在穿越山前断裂时同步左旋位错特点和剥夷面垂直落差，初步估算了丽江——大具断裂第四纪以来的平均水平和垂直位错速率分别为0.84和0.70 mm/a；中更新世以来的平均水平和垂直位错速率分别为1.56和1.69 mm/a. 近南北向丽江——大具断裂的运动性质一方面受到区域性北北西 南南东水平主压应力场的影响；另一方面，也受到玉龙——哈巴雪山与丽江盆地之间强烈的差异性运动的制约. 这两种动力学过程的共同作用, 形成了1996年丽江地震构造环境的特色.   相似文献   

Dielectric anisotropy and deformation of crustal rocks: physical interaction theory and dielectric mylonites     

Jun Muto  Hiroyuki Nagahama 《Physics of the Earth and Planetary Interiors》2004,141(1):27-35

The theory of physical interaction field by a differential geometrical approach combines the deformation field with the physical field (e.g., electromagnetic field), and derives a new tensorial relation between the deformation and the dielectric anisotropy of the crustal rocks. This relation can be applied to dielectric anisotropies of deformed natural rocks such as mylonites or gneisses. The dielectric anisotropies of mylonites are observed to increase as plastic strains of mylonites increase. Moreover, the derived tensorial relation can be linked to the electromagnetic potential field (deformational anomalies) in a deformed crust. A physico-geometrical consideration on this theory of physical interaction field is mathematically similar to ones on the theory of field in the Finsler space or on the concept of a unified gauge field.  相似文献   

Analysis of landslide frequencies and characteristics in a natural system,coastal British Columbia   总被引：1，自引：0，他引：1  

R. H. Guthrie  S. G. Evans 《地球表面变化过程与地形》2004,29(11):1321-1339

Two hundred and one debris slides and debris ?ows were analyzed in a 286 km² study area on the west coast of Vancouver Island, British Columbia, Canada. The study area remains essentially untouched by humans and therefore affords a natural setting in which to examine slope processes. Landslides were identi?ed and characterized on aerial photographs from 1:15 000 to 1:31 680, and were then mapped and transferred to a GIS for analysis. Based on detailed landslide surveys, we propose a new method to accurately determine volume of landslides of this type by measured total area. Results indicate average denudation rates of 56 m³ y^?1 km^?2, and higher natural rates of failure than analogous regions in coastal British Columbia. In contrast, the landslide rates are substantially less than those from forested watersheds. Landslide distribution is spatially clustered in air photograph epochs, and we propose intense storm cells within regional events as the causal mechanism. Further, failures occurred preferentially over the West Coast Crystalline Complex (by 1·4 times), a metamorphic assemblage of gabbros, schists and amphibolites, but 1·5 times less often over the Island Plutonic Suite, a granitic intrusive formation. The former result represents a new ?nding, while the latter corroborates ?ndings of previous authors. We examined magnitude–frequency relationships of the data set and present for the ?rst time a strong argument that the rollover effect is not merely an artefact, but is instead a consequence of the physical characteristics of the landslides themselves. We subsequently analyzed magnitude–frequency relationships from two other complete data sets from coastal British Columbia and produced a family of curves corroborating this result. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

开合构造概述   总被引：5，自引：0，他引：5  

姜春发 《地质通报》2004,23(3):200-207

随着板块构造学说的盛行，原生洋观点成为当时的主流。但根据中国的地质实际发现，中国古生代及其以来代表洋壳的蛇绿岩似乎都是元古宙陆壳裂开的产物，随之提出表明再生洋观点的手风琴式运动及岩石圈开合的理念，并逐步发展成为开合构造。本文简述了开合构造的由来和发展、研究的主要内容和现状，读者从中可了解开合构造的概貌。  相似文献   

藏南康马奥陶系及其底砾岩的发现并初论喜马拉雅沉积盖层与统一变质基底的关系   总被引：12，自引：9，他引：12  

周志广刘文灿  梁定益 《地质通报》2004,23(7):655-663

藏南北喜马拉雅拉轨岗日带康马岩体西南侧，奥陶系及其底砾岩覆盖于前奥陶系拉轨岗日群(POL)之上，后者被515～485Ma拉轨岗日构造穹隆带花岗岩侵入，沿不整合面又被泛非运动最晚期的基性脉岩侵入。奥陶系与前奥陶系的接触关系为伸展不整合，与喜马拉雅甚至冈底斯带有关剖面完全可以对比。这一不整合面即是冈瓦纳大陆北缘统一变质基底和沉积盖层的分界；冈瓦纳大陆统一变质基底的形成始于震旦纪末的“泛非运动”，其终止时间在喜屿拉雅及以北地区可以延续至寒武纪—奥陶纪之交。表现为区域上不断的伸展—拉张—裂解的构造环境。由此可以认为伸展构造亦是控制统一变质基底与沉积盖层的形成机制之一。  相似文献   

大陆科学钻探与深井地球物理长期观测研究最新进展     

徐纪人  赵志新  许志琴  石井紘 《地质通报》2004,23(8):721-727

随着地球系统科学研究的深入开展以及解决人类所面临的环境、资源、防灾等科学问题的需要，20世纪90年代以来，世界大陆、大洋科学钻探工程研究以及在钻孔深井内进行的地震、地球物理长期观测得到飞速发展，并取得了初步的观测研究成果。本文介绍了日本、德国、美国在深井长期观测方面的最新进展和科研成果，结合中国现实情况，展示了中国大陆科学钻探工程江苏东海现场开展深井地球物理综合观测的初步方案及其观测研究前景。该深井观测站将成为中国第一个无地面干扰的综合性深井地球物理和流体长期实验观测站，预期可以获取客观真实的深井综合地球物理资料，开创中国零干扰条件下地球科学观测研究的崭新局面。  相似文献   

松江河鸳鸯湖第四纪沉积特征与构造演化     

李军敏  王锡魁  刘玉英  范昌福  张洪岩 《世界地质》2004,23(1):14-19

从第四纪沉积特征出发，利用岩石矿物成分和结构间的差别及玄武岩和砂砾石年龄之间的差异，结合长白山地区的大地构造环境，得出该区玄武岩后的冷凝环境和第四纪的沉积环境；并结合该区火山、地震的活动规律，对该区复杂的新构造运动进行了复原。即该区地壳在近20万年以来，不仅经历上升和稳定状态的多次交替，且地壳每次上升的幅度和速度各异，稳定时期持续的时间也有差异，这表明地壳活动度的脉动性。由此构造活动形成的地貌和河流阶地的类型极其复杂。  相似文献   

The movement age of hidden fault and analysis on width of its effect zone from shallow seismic sounding and drilling data     

Yang Xiao-ping  Li De-qing  Zhao Cheng-bin  Liu Bao-jin  Sun Zhen-guo  Zhao Jing-yao 《地震学报(英文版)》2004,17(1):94-102

Field experimental seismic sounding permitted us to obtain optimal shallow seismic reflection sounding parameters. In process of data processing, we obtained a high-qualitative shallow seismic reflection sounding profile by using the techniques such as filtering, edition surgical blanking, prediction deconvolution, fitting static correlation of first arrival time, and velocity analysis. Comprehensive analysis on the information of reflection wave groups along the seismic sounding profile and the stratigraphic and neogeochronological data obtained from many drills near the sounding line reveals that the upper termination of the detected fault zone is located at depth of 75–80 m, in the Middle Pleistocene deposits dated to be about 220 ka BP. The continuity, discontinuity, increasing and decreasing amount of reflection wave groups and change of their configurations, in combination with geological columns of drills, permitted us to know that the width of upper termination of the fault zone is 100 m. It can be inferred from the variation of number of reflection wave groups along the profile that the scarp of hidden fault is 200 m wide and the fault is a synsedimentary active fault in the Early Pleistocene and the early stage of Middle Pleistocene. No tectonic movement, which offset the covering deposits, had occurred since the late stage of Middle Pleistocene. Foundation item: A High-new Technique Project by State Development and Planning Commission of China (2001977).  相似文献   

Pb and Nd isotopic composition of the Jigongshan granite: constraints on crustal structure of Tongbaishan in the middle part of the Qinling–Tongbai–Dabie orogenic belt, Central China     

Hongfei Zhang  Zengqiu Zhong  Shan Gao  Benren Zhang  Li Zhang  Shenghong Hu  Qingye Hou 《Lithos》2004,73(3-4):215-227

The Qinling–Dabie–Sulu belt is the world's largest ultrahigh pressure (UHP) metamorphic belt. The UHP metamorphism is well dated at 220–245 Ma in the Dabie–Sulu belt but at 507 Ma in the Qinling belt. The Tongbaishan is located between the Qinling orogenic belt to the west and the Dabie–Sulu UHP metamorphic belt to the east. It is the key area for studying the tectonic relation between the Qinling and Dabie–Sulu belts and the diachronous UHP metamorphism. The Jigongshan granitic pluton (t=128 Ma) with a total area of 1200 km², composed of monzogranite, was mostly emplaced into the Tongbai complex, an exposed basement in the Tongbaishan. The Jigongshan granites have SiO₂=69.85–72.35%, K₂O/Na₂O=0.87–1.13, A/CNK=0.91–1.03, Rb/Sr=0.14–0.25 and Th/U=3.3–12. Their REE compositions show strongly fractionated patterns with (La/Yb)_N=14–58 and Eu*/Eu=0.79–1.05. The granites are characterized by low radiogenic Pb isotopic composition. The present-day whole-rock Pb isotopic ratios are ²⁰⁶Pb/²⁰⁴Pb=16.707–17.055, ²⁰⁷Pb/²⁰⁴Pb=15.239–15.326 and ²⁰⁸Pb/²⁰⁴Pb=37.587–37.853, which are similar to that of the continental lower crust. Their _Nd(t) values range from −16 to −20, and depleted-mantle Nd model ages (T_DM) from 1.8 to 2.2 Ga. The above evidence indicates that the magma of the Jigongshan granites was derived from the partial melting of the continental crust. The Pb and Nd isotopic compositions of the Jigongshan granites resemble those of the Dabie core complex in the Dabieshan but are distinct from those of the Tongbai complex in the Tongbaishan. Thus, the Dabie core complex would be the magma source of the Jigongshan granites. The result implies that the Dabie core complex is extended to the west and constitutes the unexposed basement underlaying the Tongbai complex in the Tongbaishan.  相似文献   

新疆民丰县皮什盖-塔勒克勒格断裂带的第四纪活动特征     

柏美祥 《内陆地震》2003,17(2):97-100

皮什盖-塔勒克勒格断裂将蓟县系逆掩于第四系之上，中更新世之前的西域变动显著，现今地震活动不强烈。其分支断裂帕西木断裂在中更新世之后，由正断层变为压性断层。  相似文献