Late-Stage Ductile Deformation in Xiongdian-Suhe HP Metamorphic Unit, North-Western Dabie Shan, Central China     

SuoShutian ZhongZengqiu ZhouHanwen YouZhendong 《中国地质大学学报(英文版)》2004,15(3):262-274

New structural and petrological data unveil a very complicated ductile deformation history of the Xiongdian-Suhe HP metamorphic unit, north-western Dabie Shun, central China. The finegrained symplectic amphibolite-facies assemblage and coronal structure enveloping eclogite-facies garnet,omphacite and phengite etc., representing strain-free decompression and retrogressive metamorphism,are considered as the main criteria to distinguish between the early-stage deformation under HP metamorphic conditions related to the continental deep subduction and collision, and the late-stage deformation under amphibolite to greenschist-facies conditions occurred in the post-eclogite exhumation processes.Two late-stages of widely developed, sequential ductile deformations D3 and D4, are recognized on the basis of penetrative fabrics and mineral aggregates in the Xiongdian-Suhe HP metamorphic unit, which shows clear, regionally, consistent overprinting relationships. D3 fabrics are best preserved in the Suhe tract of low post-D3 deformation intensity and characterized by steeply dipping layered mylonitic amphibolites associated with doubly vergent folds. They are attributed to a phase of tectonism linked to the initial exhumation of the HP rocks and involved crustal shortening with the development of upright structures and the widespread emplacement of garnet-bearing granites and felsic dikes. D4 structures are attributed to the main episode of ductile extension (D^24) with a gently dipping foliation to the north and common intrafolial, recumbent folds in the Xiongdian tract, followed by normal sense top-to-the northductile shearing (D^24) along an important tectonic boundary, the so-called Majiawa-Hexiwan fault (MHF), the westward continuation of the Balifan-Mozitan-Xiaotian fault (BMXF) of the northern Dabie Shan. It is indicated that the two stages of ductile deformation observed in the Xiongdian-Suhe HP metamorphic unit, reflecting the post-eclogite compressional or extrusion wedge formation, the subhorizontal ductile extension and crustal thinning as well as the top-to-the north shearing along the high-angle ductile shear zones responsible for exhumation of the HP unit as a coherent slab, are consistent with those recognized in the Dabie-Sulu UHP and HP metamorphic belts, suggesting that they were closely associated in time and space. The Xiongdian-Suhe HP metamorphic unit thus forms part of the Triassic(250-230 Ma) collision orogenic belt, and can not connect with the South Altun-North Qaidam-North Qinline UHP metamorphic belt formed durin~ the Early Paleozoic (500-400Ma).  相似文献   

中国兴凯湖北岸平原晚全新世花粉记录及泥炭沼泽形成   总被引：7，自引：1，他引：7  

张淑芹  邓伟  阎敏华  李小强  王升忠 《湿地科学》2004,2(2):110-115

通过兴凯湖北岸平原泥炭剖面高分辩率花粉分析研究，对晚全新世花粉划分4个组合带。XKH-4组合时期(1857～1746aB．P．)为沼泽发育前期，这一时期花粉浓度小，陆生草本植物占优势，气候干冷。XKH-3组合时期(1746～1287aB．P．)为沼泽发育早期，这一时期花粉浓度较大，且水生植物花粉含量为剖面最高，喜温落叶阔叶植物大发展时期，气候温和湿润。XKH-2组合时期(1287～602aB．P．)为沼泽发育中期，这一时期花粉浓度最小，但以陆生草本植物为主，木本植物为辅，水生植物急剧减少，针叶植物出现两次高峰，气候向冷干方向发展。XKH-1组合时期(602aB．P．至今)为沼泽发育盛期，这一时期花粉浓度最大，陆生草本植物大发展时期，气候波动较大。  相似文献   

世界政治新形势下的中国经济安全观     

徐忠  娄昭 《世界地理研究》2004,13(3):25-29,49

当前，世界政治形势处于动荡催生调整，调整蕴含机遇，在单极与多极矛盾的碰撞与互动中，正在形成某种更有效的机制，培育更为成熟、理性竞争的意识，促使各主要大国为世界的持久和平与繁荣共同担负起应有的责任。因此，国家经济安全是世界各国都普遍关注的战略问题。本文首先总结了就当今世界政治发展的四个特点，并在分析国际形势新变化对中国经济安全影响的基础上，提出了维护我国经济安全的六点思考。  相似文献   

Palaeomagnetic evidence for southward displacement of the Chuan Dian fragment of the Yangtze Block   总被引：5，自引：0，他引：5  

Masato Tamai  Yuyan Liu  Lian Zhong Lu  Masahiko Yokoyama  Nadir Halim  Haider Zaman  Yo-ichiro Otofuji 《Geophysical Journal International》2004,158(1):297-309

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Mesozoic-Cenozoic tectonic transition in Kuqa Depression-Tianshan, Northwest China: Evidence from sandstone detrital and geochemical records   总被引：2，自引：0，他引：2  

LI Zhong  GUO Hong  WANG Daoxuan & LIN Wei . Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China . Tarim Oilfield Branch  CNPC  Korla  China  . Hefei University of Industry  Tunxilu  Hefei  China 《中国科学D辑(英文版)》2005,48(9):1387-1402

Succeeding to multiply collisions of different blocks in Late Paleozoic[1―5], complex intracontinental structural deformation occurred in the Tianshan area during Mesozoic-Cenozoic[6―16], which controlled coeval basin-range evolution and resulted in intensive modi- fication and adjustment of the Paleozoic oil-gas reser- voirs[17―19]. The Kuqa Depression is a secendary struc- tural unit of the Tarim basin, in which Mesozoic- Ce- nozoic deposits occur in thickness of 6000―7000 m. The Kuq…  相似文献   

施工降水中的环境保护及水资源合理利用     

钟士国 《岩土工程技术》2005,19(2):101-105

城市缺水是目前带有普遍性的重大问题 ,但在城市建设过程中 ,宝贵的地下水资源遭到浪费的现象又大量存在 ,解决好施工降水与环境保护问题是关系到城市发展的重要问题之一 ,结合郑州市的工程实践 ,谈谈施工降水中的环境保护及水资源合理利用问题。  相似文献   

Dynamics of thermal plumes in three-dimensional isoviscous thermal convection     

Shijie Zhong 《Geophysical Journal International》2005,162(1):289-300

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Modelling post-glacial rebound with lateral viscosity variations   总被引：2，自引：0，他引：2  

Archie Paulson  Shijie Zhong  John Wahr 《Geophysical Journal International》2005,163(1):357-371

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Analysis of rock structure stability in coal mines   总被引：1，自引：0，他引：1  

Yi‐Shan Pan  Zhong‐Hua Li 《国际地质力学数值与分析法杂志》2005,29(10):1045-1063

In this paper, the theory of limit point instability is used to analyse the stability of rock structures in coal mines. A general method of analysing stability of rock structures is put forward and a uniform instability condition of rock structures is set up. Some instability phenomena, such as rock bursts in circular roadways, pillars and long walls, and the outburst of coal and gas from circular roadways, are discussed analytically. At a later stage, the critical point of rock structure instability is determined. The influence of relative parameters (such as the mechanical properties of rock, coal, and the geometric sizes) on the stability of the rock structures is carefully analysed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

A Real-Time Analysis and Feedback System for Quality Control of Dam Foundation Grouting Engineering     

D. H. Zhong  F. G. Yan  M. C. Li  C. X. Huang  K. Fan  J. F. Tang 《Rock Mechanics and Rock Engineering》2015,48(5):1947-1968

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