川滇地块的震源力学机制、运动速率和活动方式   总被引：39，自引：3，他引：39       下载免费PDF全文

程万正  刁桂苓  吕弋培  张永久  李桂芳  陈天长 《地震地质》2003,25(1):71-87

用 4 4 2次中强地震的震源机制解分析了川滇次级地块应力场的优势方向。使用 771次 3级左右地震的滑动角λ参数统计确定震源断层的错动方式 ,并用中强地震P波初动解的N轴仰角的统计分布结果得到的震源断层错动或滑动型式去佐证。拟合中强地震的矩张量速率式 ,计算了川滇次级地块各地震构造区的年均滑动速率 ,并进行比较。根据 1980— 2 0 0 1年川青地块、雅江地块和滇中地块边界断裂带跨断层短水准、短基线定期复测结果 ,分析了水平和垂向年均形变速率。川滇地块间的运动是不均匀的。川青地块的运动方向为SEE。雅江地块压应力场优势方向为SSE ,相对川青地块的运动速率更大。滇中地块承袭雅江地块的运动方向 ,略偏东。密支那滇西地块压应力场有 2组优势方向 ,存在向NE方向的推挤和SSE方向的逃逸 ,活动速率大  相似文献   

苏皖地块构造演化、苏鲁造山带形成及其耦合的盆地发育   总被引：34，自引：2，他引：34  

吴根耀  马力  陈焕疆  徐克定 《大地构造与成矿学》2003,27(4):337-353

郯庐断裂带一度是古特提斯洋域中的转换断层,其东的苏皖地块和胶辽克拉通分别是曾经独立于扬子克拉通和华北克拉通之外的构造单元。苏皖地块原属中朝构造域,因中元古代时苏鲁洋的张开而向南漂移,震旦纪起归入华南构造域。受北东东-近东西向的江南断裂和江绍断裂右行走滑活动控制,苏皖地块及怀玉地块在石炭纪末-三叠纪时脱离华南构造域,成为古特提斯洋域中的中间地块。中国东部地区东亚燕山期山系的形成受两个地球动力学系统制约:一是苏鲁洋的消减及闭合后苏皖地块与胶辽克拉通的碰撞,二是江南断裂和江绍断裂的先剪后压,苏皖地块与拼合了的扬子-华北克拉通间发生斜向会聚和剪切造山,怀玉地块仰冲超叠在苏皖地块上。分5个阶段(印支期消减,早-中侏罗世斜向会聚,晚侏罗-早白垩世消减,早白垩世碰撞和燕山造山带坍塌)叙述了中生代造山作用的表现和特点,探讨了与各阶段造山作用耦合的盆地类型和时空分布。因燕山造山带的坍塌而燕山运动构建的“盆”“山”关系解脱,中国东部第三纪的伸展盆地直接叠加在燕山造山带的坍塌裂谷上。  相似文献   

Origin and tectonic significance of a Mesozoic multi-layer over-thrust system within the Yangtze Block (South China)   总被引：21，自引：0，他引：21  

Dan-Ping Yan  Mei-Fu Zhou  Hong-Lin Song  Xin-Wen Wang  John Malpas 《Tectonophysics》2003,361(3-4):239-254

In the Yangtze Block (South China), a well-developed Mesozoic thrust system extends through the Xuefeng and Wuling mountains in the southeast to the Sichuan basin in the northwest. The system comprises both thin- and thick-skinned thrust units separated by a boundary detachment fault, the Dayin fault. To the northwest, the thin-skinned belt is characterized by either chevron anticlines and box synclines to the northwest or chevron synclines to the southeast. The former structural style displays narrow exposures for the cores of anticlines and wider exposures for the cores of synclines. Thrust detachments occur along Silurian (Fs) and Lower Cambrian (Fc) strata and are dominantly associated with the anticlines. To the southeast, this style of deformation passes gradually into one characterized by chevron synclines with associated principal detachment faults along Silurian (Fs), Cambrian (Fc) and Lower Sinian (Fz) strata. There are, however, numerous secondary back thrusts. Therefore, the thin-skinned belt is like the Valley and Ridge Province of the North American Applachian Mountains. The thick-skinned belt structurally overlies the thin-skinned belt and is characterized by a number of klippen including the Xuefeng and Wuling nappes. It is thus comparable to the Blue Ridge Province of Appalachia.The structural pattern of this thrust system in South China can be explained by a model involving detachment faulting along various stratigraphic layers at different stages of its evolution. The system was developed through a northwest stepwise progression of deformation with the earliest delamination along Lower Sinian strata (Fz). Analyses of balanced geological cross-sections yield about 18.1–21% (total 88 km) shortening for the thin-skinned unit and at least this amount of shortening for the thick-skinned unit. The compressional deformation from southeast to northwest during Late Jurassic to Cretaceous time occurred after the westward progressive collision of the Yangtze Block with the North China Block and suggests that the orogenic event was intracontinental in nature.  相似文献   

Identification of ore extraction and metal working in ancient times: a case study of Sagalassos (SW Turkey)     

P. Degryse  Muchez  S. Six  M. Waelkens 《Journal of Geochemical Exploration》2003,77(1):65-80

The extensive territory of the ancient (Hellenistic to Byzantine) city of Sagalassos (SW Turkey) offered a rich variety in natural mineral resources. The frequent occurrence of iron slag in the excavations at the site proved the local working of metal. A geochemical prospection campaign was done in the territory of the ancient city in order to identify or discard the city and its territory as a self-sustaining metallurgical centre. Secondly, the geochemical impact of ancient metallurgy was investigated. Geochemical anomalies identified in stream sediments are explained by the presence of mineralised deposits and ancient metal working. Mg, Cr, Co and Ni anomalies point to chromite and chrysotile-magnetite deposits related to the basic rocks of the Lycian nappes in the area. Fe, V and Ti anomalies indicate the presence of iron mineralisations, which have been worked for iron production in ancient times. Finally, the association of P, Cu, Pb, Mn, As and Ag anomalies are an indicator of human activity at archaeological sites. Within the framework of this geochemical prospection, a metal working site apart from the city of Sagalassos was identified. Here, ore was both extracted and processed to workable iron.  相似文献   

对下扬子与华南边界结合带东延问题的地球物理探讨   总被引：2，自引：1，他引：2  

郝天珧  刘建华  王谦身  Suh Mancheol  戴明刚  阎晓蔚 《地球物理学进展》2003,18(2):269-275

以江山-绍兴、铅山-宜春等断裂带作为华南与扬子块体之间的边界结合带，这种认识目前已基本为大家所接受．但是，这条边界结合带向东延伸入海之后的位置与去向一直是多年来研究的热点．本文基于黄、东海研究区的地球物理数据(空间重力数据、布格重力数据和地震层析成像结果)，利用方向导数等处理方法，对研究区的地球物理数据进行处理，并对研究区的地球物理场进行了分析，划分出不同的区块．结合研究区的磁力与地质资料，利用各种成图、成像技术，形成一系列分析图件．在此基础上对华南与扬子块体之间的边界结合带进行了追踪．研究结果认为：该结合带的位置有可能比传统认识中自长江口至大黑山群岛的位置更向南一些，在杭州湾-长崎、对马海峡一线，并呈现向北略微凸出的弓形．边界结合带在深度上属于深大断裂带，一直可以追索到上地幔的顶部．与中朝与扬子块体之间的边界结合带相比较，本条结合带的踪迹不是十分清晰．表明加里东运动之后，该结合带的运动明显减弱．  相似文献   

Timing and exhumation of eclogite facies shear zones, Musgrave Block, central Australia   总被引：2，自引：0，他引：2  

A. CAMACHO  W. COMPSTON  M. McCULLOCH  & I. McDOUGALL 《Journal of Metamorphic Geology》1997,15(6):735-751

Timing constraints on shear zones can provide an insight into the kinematic and exhumation evolution of metamorphic belts. In the Musgrave Block, central Australia, granulite facies gneisses have been affected, to varying degrees, by mylonitic deformation, some of which attained eclogite facies. The Davenport Shear Zone is a dominant strike-slip system that formed at eclogite facies conditions ( T  ≈650  °C and P ≈12.0  kbar). Sm–Nd mineral isochrons obtained from equilibrated high-pressure assemblages, as well as ⁴⁰Ar–³⁹Ar data, show that the eclogite and greenschist facies high-strain overprints were coeval, at c .  550  Ma. Mylonitic processes do not appear to have reset the U–Pb system in zircon, but may have partially disturbed it. The thermal gradient in the Musgrave Block crust at c .  550  Ma was c .  16  °C  km⁻¹ and at c .  535  Ma was c .  18  °C  km⁻¹, based on P – T  estimates of eclogite and greenschist facies shear zones, respectively. These estimates are similar to present-day geothermal gradients in many stable continental shield areas, suggesting that the region did not undergo a significant transient perturbation of the geotherm. Therefore, in the Musgrave Block, cooling subsequent to eclogite facies metamorphism appears to have been controlled by exhumation, rather than by the removal of a heat source. Estimated exhumation rates in the range 0.2 to ≥1.5  mm year⁻¹ are comparable with other orogenic belts, rather than cratonic areas elsewhere.  相似文献   

南宁、百色盆地红土风化壳的地球化学特征及其环境意义^*   总被引：4，自引：0，他引：4  

高柳青  袁宝印 《地理研究》1996,15(1):82-90

本文以广西南宁盆地那桐风化壳,及百色盆地江泽风地壳的大量土体化学分析数据为依据,进行了第四纪红土的确认、形成、分布和土壤肥力状况。以及通过地球化学强度、硅铁系数、硅铝系数等指标进行了两风化壳的对比研究。同时,还探讨了风化壳的发育过程及其与环境的关系。  相似文献   

岩质边坡设计坡角和锚固方案的确定   总被引：3，自引：0，他引：3  

郭映忠 《工程地质学报》1996,4(2):1-6

本文运用赤平极射投影、块体理论和岩体力学的基本原理, 试探求一种可供边坡工程设计采用的确定人工岩质边坡最大安全设计坡角和锚固方案的简易方法。  相似文献   

沉积盆地流体—岩石相互作用研究的现状   总被引：17，自引：0，他引：17  

蔡春芳 《地球科学进展》1996,11(6):575-579

沉积盆地流体－岩石相互作用研究主要是通过实验地球化学和岩石学，地球化学模拟方法开展的，综述了这一领域的研究现状，主要包括有机酸来源和分布及期 对矿物稳定性的影响，地层水成因与演化、烃类与岩石间的氧化还原反应、以及储层润湿性的变化等，并展望了其 发展趋势。  相似文献   

黑龙江省东部跃进山群中绿片岩的地球化学特征及地质意义   总被引：2，自引：4，他引：2  

张魁武  邵济安 《岩石学报》1997,13(2):168-172

跃进山群出露位于佳木斯地块和那丹哈达地体之间，是完达山造山带的组成部分。它由大陆斜坡相沉积物、大洋中脊型玄武岩和洋岛型玄武岩组成，其中有镁铁－超镁铁质岩块体。它不是一个地层单位，而是与活动大陆边缘板块俯冲作用有关的蛇绿混杂岩  相似文献