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1Relocation of the M8.0 Wenchuan earthquake and its aftershock sequence显示文摘We relocated M8.0 Wenchuan earthquake and 2706 aftershocks with M≥2.0 using double-difference algorithm and obtained relocations of 2553 events. To reduce the influence of lateral variation in crustal and upper mantle velocity structure, we used different velocity models for the east and west side of Longmenshan fault zone. In the relocation process, we added seismic data from portable seismic sta-tions close to the shocks to constrain focal depths. The precisions in E-W, N-S, and U-D directions after relocation are 0.6, 0.7, and 2.5 km respectively. The relocation results show that the aftershock epi-centers of Wenchuan earthquake were distributed in NE-SW direction, with a total length of about 330 km. The aftershocks were concentrated on the west side of the central fault of Longmenshan fault zone, excluding those on the north of Qingchuan, which obviously deviated from the surface fault and passed through Pingwu-Qingchuan fault in the north. The dominant focal depths of the aftershocks are between 5 and 20 km, the average depth is 13.3 km, and the depth of the relocated main shock is 16.0 km. The depth profile reveals that focal depth distribution in some of the areas is characterized by high-angle westward dipping. The rupture mode of the main shock features reverse faulting in the south, with a large strike-slip component in the north.HUANG Yuan WU JianPing ZHANG TianZhong ZHANG DongNing 2008Science China Earth Sciences2008,51,12:64
2Stress changes on major faults caused by M_w7.9 Wenchuan earthquake,May 12,2008显示文摘On May 12,2008,a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province,China,collapsing buildings and killing tens of thousands people.As predicted,aftershocks may last for at least one year,and moreover,large aftershocks are likely to occur.Therefore,it is critical to outline the areas with potential aftershocks before reconstruction and resettling people as to avoid future disasters.It is demonstrated that the redistribution of stress induced by an earthquake should trigger successive seismic activity.Based on static stress triggering theory,we calculated the coseismic stress changes on major faults induced by the Wenchuan earthquake,with elastic dislocation the-ory and the multilayered crustal model.We also discuss the stress distribution and its significance for future seismic activity under the impact of the Wenchuan earthquake.It is shown that coulomb failure stress(CFS) increases obviously on the Daofu-Kangding segment of the Xianshuihe Fault,the Maqu and Nanping segment of the Eastern Kunlun Fault,the Qingchuan Fault,southern segment of the Min-jiang Fault,Pengxian-Guanxian Fault,Jiangyou-Guangyuan Fault,and Jiangyou-Guanxian Fault.The increased stress raises the probability of earthquake occurrence on these faults.Since these areas are highly populated,earthquake monitoring and early disaster alarm system are needed.CFS increases with a magnitude of 0.03―0.06 MPa on the Qingchuan Fault,which is close to the northern end of the rapture of Wenchuan earthquake.The occurrence of some strong aftershocks,including three events with magnitude higher than 5.0,indicates that the seismic activities have been triggered by the main shock.Aftershocks seem to migrate northwards.Since the CFS change on the Lueyang-Mianxian Fault located on the NEE of the Qingchuan Fault is rather small(±0.01 MPa),the migration of aftershocks might be terminated in the area near Hanzhong City.The CFS change on the western Qinling Fault is around 10 Pa,and the impact of static triggering can be neglected.The increment of CFS on the Pengxian-Guanxian Fault and Beichuan-Yingxiu Fault southwest to the main rupture is 0.005―0.015 MPa,which would facilitate earthquake triggering in these areas.Very few aftershocks in these areas indicate that the accumulated stress has not been released sufficiently.High seismic risk is predicated in these areas due to coseismic CFS loading.The Wenchuan earthquake released the accumulated CFS on the Fubianhe Fault,the Huya Fault,the Ha'nan-Qingshanwan Fault,and the Diebu-Bailongjiang Fault.The decrement of CFS changes on the Longquanshan Fault east to Chengdu City is about 0.002 MPa.The seismic activity will be depressed by decrement of CFS on these faults.SHAN Bin XIONG Xiong ZHENG Yong DIAO FaQi 2009Science China Earth Sciences2009,52,5:47
3大兴安岭地区德尔布干断裂带北段构造年代学研究显示文摘德尔布干断裂带是大兴安岭隆起西侧NE向的重要断裂带,处在海拉尔-拉布达林-根河盆地西缘,是著名德尔布干成矿区东南边界断裂带。为了确定德尔布干断裂带运动性质、活动时间,深入探讨该断裂带与中生代海拉尔-拉布达林-根河盆地及大兴安岭盆山格局、认识德尔布干断裂带多金属矿床成因等问题,本文应用锆石SHRIMP和云母^(40)At/^(39)Ar定年技术,分别对断裂带内的细粒黑云母花岗岩侵入体、韧性变形的花岗闪长质片麻岩、白云母石英片岩,进行了同位素年代学研究。其中花岗闪长质片麻岩岩浆型锆石SHRIMP谐和年龄300.6±9.3Ma,为花岗闪长质片麻岩海西期的侵位年龄;而花岗闪长质片麻岩中黑云母^(40)At/^(39)Ar坪年龄是130.9±1.4Ma,白云母石英片岩的白云母^(40)Ar/^(39)Ar坪年龄是115.6±1.6Ma,代表早白垩世伸展构造变形年龄;细粒黑云母花岗岩侵入体岩浆型锆石SHRIMP谐和年龄130.1±1.4Ma,为同伸展构造变形侵位的岩浆事件。上述地质年代说明德尔布干断裂带是早白垩世(110~130Ma)该区最年轻的重大伸展构造变形产物。控制NE向大兴安岭隆起和中生代海拉尔-拉布达林-根河等火山沉积盆地的发育格局、以及中生代以来的地壳演化与成矿类型。郑常青 周建波 金巍 季建清 张兴洲 马志红 丁雪 2009岩石学报2009,25,8:42
4Discovery of the Longriba Fault Zone in Eastern Bayan Har Block, China and its tectonic implication显示文摘Re-measured GPS data have recently revealed that a broad NE trending dextral shear zone exists in the eastern Bayan Har block about 200 km northwest of the Longmenshan thrust on the eastern margin of the Qinghai-Tibet Plateau. The strain rate along this shear zone may reach up to 4-6 mm/a. Our interpretation of satellite images and field observations indicate that this dextral shear zone corresponds to a newly generated NE trending Longriba fault zone that has been ignored before. The northeast segment of the Longriba fault zone consists of two subparallel N54°±5°E trending branch faults about 30 km apart, and late Quaternary offset landforms are well developed along the strands of these two branch faults. The northern branch fault, the Longriqu fault, has relatively large reverse component, while the southern branch fault, the Maoergai fault, is a pure right-lateral strike slip fault. According to vector synthesizing principle, the average right-lateral strike slip rate along the Longriba fault zone in the late Quaternary is calculated to be 5.4±2.0 mm/a, the vertical slip rate to be 0.7 mm/a, and the rate of crustal shortening to be 0.55 mm/a. The discovery of the Longriba fault zone may provide a new insight into the tectonics and dynamics of the eastern margin of the Qinghai-Tibet Plateau. Taken the Longriba fault zone as a boundary, the Bayan Har block is divided into two sub-blocks: the Ahba sub-block in the west and the Longmenshan sub-block in the east. The shortening and uplifting of the Longmenshan sub-block as a whole reflects that both the Longmenshan thrust and Longriba fault zone are subordinated to a back propagated nappe tectonic system that was formed during the southeastward motion of the Bayan Har block owing to intense resistance of the South China block. This nappe tectonic system has become a boundary tectonic type of an active block supporting crustal deformation along the eastern margin of the Qinghai-Tibet Plateau from late Cenozoic till now. The Longriba fault zone is just an active fault zone newly-generated in late Quaternary along this tectonic system.XU XiWei WEN XueZe CHEN GuiHua YU GuiHua 2008Science China Earth Sciences2008,51,9:46
5Expansion of the Cathaysian Oldland through the Ordovician-Silurian transition:Emerging evidence and possible dynamics显示文摘Located northwest of the Jiangshan-Shaoxing Fault Zone,western and northwestern Zhejiang and northeastern Jiangxi provinces experienced major changes in bio-and litho-facies and paleogeography through the Ordovician-Silurian transition (late Katian,Hirnantian,and early Rhuddanian),as manifested by stratigraphic,paleontologic and synecologic records.Three geographic units under consideration are South,Central,and North areas.The western margin of the South area was occupied by the Huaiyu Mountains,whereas the other two parts were covered by the Zhe-Gan Sea during late Katian (Late Ordovician) time.In the early stage of the Changwu Formation deposition (late Katian),the sea was deepening northeastward,but with shallower conditions in the southwest and deeper conditions in the northeast.During mid to late stages of Changwu Formation deposition (latest Katian),the sea became much shallower and the sea bottom was uplifted substantially,which occurred somewhat prior to the global trend.During the Hirnantian (latest Ordovician) and early Rhuddanian (earliest Silurian),the study region became a shallow bay under expansion of the Cathaysian Oldland.There occurred a major drop of sea level and great changes in benthic biota with the occurrence of many new immigrants through the Ordovician-Silurian transition,which are closely related to a unique regional orogeny.The Yangtze and Cathaysian blocks may have amalgamated within the South China Paleoplate during this interval to cause the continuous uplifting and northwestward expansion of the Cathaysian Oldland.RONG JiaYu ZHAN RenBin XU HongGen HUANG Bing YU GuoHua 2010Science China Earth Sciences2010,53,1:37
6基于加权中值的分布式传感器网络故障检测(英文)显示文摘无线传感器网络中的错误测量数据会导致网络服务质量下降和能量浪费.提出了一种通过融合邻居节点的测量数据来实现故障检测的策略.主要做了以下3项工作:(1)提出了一种新颖的对邻居节点测量数据进行加权的方法;(2)提出了一种衡量测量数据之间差距的方法;(3)提出了基于加权中值的故障诊断策略WMFDS(weighted median fault detection scheme),它同时适用于二进制决策和实数测量值.理论分析及仿真结果表明,即使节点发生故障的概率很高,提出的诊断策略也能得到很高的检测精度和较小的误判率,这表明在无线传感器网络故障检测中应用该方法具有很好的性能.高建良 徐勇军 李晓维 2007软件学报2007,18,5:38
7The control of syndepositional faulting on the Eogene sedimentary basin fills of the Dongying and Zhanhua sags, Bohai Bay Basin显示文摘The Dongying and Zhanhua sags are the major hydrocarbon exploration and produc- tion subbasins in the Bohai Bay Basin. Integrated analysis of the sedimentary basin fills has shown that the syndepositional faults and their arrangement styles exerted an important influ- ence on the development and distribution of the Eogene depositional systems. The sedimentary filling evolution of the subbasins reflects the general control of the episodic rifting process. The major long-term active normal faults formed a series of paleogeomorphic accident or slopebreak zones that commonly delineated the subsidiary palaeostructural units and the depositional facies tracts and constrained the general distribution of sedimentary facies zones. The central sag boundary fault slopebreak zones usually determined the distribution of the depocenters of ter- restrial clastic depositional systems, particularly the lowstand fans or deltaic depositional sys- tems, and have proven to be the economically important targets for the exploration of subtle sandstone reservoirs. A variety of syndepositional fault arrangement patterns, including the par- allel, en echelon, combo-like, broom-like fault systems and the fault overlap or transfer zones, have been recognized in the subbasins. They generated distinctive geomorphic features and exerted a direct influence on sediment dispersal and sandbody distribution during the Eogene synrift stage. It is the key for the prediction of depositional systems tracts and reservoir sand- stones to investigate the activity and distribution of the fault slopebreak zones and reconstruct the structural paleogeomorphy in different basin filling stages of the basin evolution.LIN Changsong1, ZHENG Herong2, REN Jianye1, LIU Jingyan1 & Qiu Yigang1 1. Department of Energy Geology, China University of Geosciences, Beijing 100083, China 2. Petroleum Exploration and Production Institute, Sino-Petroleum and Chemistry Cooperation, Beijing 100083, China 2004Science China Earth Sciences2004,47,9:33
8Structural characteristics of the Tan-Lu fault zone in Cenozoic basins offshore the Bohai Sea显示文摘The Tan-Lu fault zone across the eastern margin of the Cenozoic basins offshore the Bohai Sea is a NNE-trending right-lateral strike-slip fault system developed in the Cenozoic basin cover. It cuts through NE-to NNE-striking major extensional faults that controlled the formation of Paleogene basins. Recent petroleum exploration indicates that Cenozoic structural activities of the Tan-Lu fault system have directly or indirectly affected oil and gas distribution offshore the Bohai Sea. As part of a deep fault zone the Tan-Lu fault zone has been activated since the Oligocene,and obviously affected the tectonic evolution of offshore Bohai basins since then. The formation of Paleogene rift basins offshore the Bohai Sea has utilized the pre-existing structural elements of the Tan-Lu fault zone that developed in the late Mesozoic.QI JiaFu1,2,ZHOU XinHuai3,DENG RongJing4 & ZHANG KeXin2 1 State Key Laboratory of Petroleum Resource and Prospecting,China Petroleum University,Beijing 102249,China 2 Department of Earth Sciences,China Petroleum University,Beijing 102200,China 3 Tianjin Branch of CNOOC China Limited,Tianjin 300451,China 4 Beijing Research Center of CNOOC China Limited,Beijing100027,China 2008Science China Earth Sciences2008,51,S2:33
9Basic characteristics of active tectonics of China显示文摘During the last 20 years, studies on active tectonics in China have entered a new quan-titative research stage and made a great progress. Summing up the quantitative results, a Map of Active Tectonics of China on the scale of 1︰4 million has been compiled. In the map all types of active tectonics and their kinematic parameters are reflected in possible detail, such as active faults, active folds, active basins, active blocks, volcanoes, and earthquakes. This paper summa-rizes the basic characteristics of active tectonics of China. The Himalaya Mountains and Taiwan Island are major plate boundaries where the slip rates are larger than 15 mm/a. Tectonic activity in the continental intraplate region is characterized by block motion. The crust and lithosphere in the region were dissected into blocks with different orders. Of them the Qinghai-Xizang (Tibet), Xin- jiang, and North China block regions exhibit the most recent tectonic activity. The kinematic char-acteristics of more than 200 active tectonic zones indicate that the intraplate tectonic activity represents a block motion at a limited low rate. Horizontal slip rate along the tectonic boundary belts between the blocks is generally less than 10 mm/a, and 10—15 mm/a in maximum, and hence it does not support the continental escape theory of high rate of slip.邓起东 张培震 冉勇康 杨晓平 闵伟 楚全芝 2003Science China Earth Sciences2003,46,4:29
10^(40)Ar/^(39)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance显示文摘Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (12-10 Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 350℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.ZHANG Yueqiao1, CHEN Wen2, 3 & YANG Nong1 1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China 2. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2004Science China Earth Sciences2004,47,9:27
11^(40)Ar/^(39)Ar age evidence for Altyn fault tectonic activities in western China显示文摘Four 40Ar/39Ar age groups of mica, hornblende and K-feldspar were obtained from Proterozoic and early Paleozoic metamorphic rocks in the Aksay-Dangjin Pass area, western China. The samples away from the middle shear zone of the Altyn fault belt yield two plateau age groups in the range of 461—445.2 Ma and 414.9—342.8 Ma, respec-tively. They represent the tectono-thermal events that had been recorded in the rocks that were displaced by the Altyn strike-slip fault in late Ordovician-early Silurian and Devo-nian, respectively. These two age groups should be related to the closures of Northern and Southern Qilian Oceans. The deformed granitic gneiss from the northern belt gives a pla-teau age group of 178.4—137.5 Ma, which is interpreted as the active age of the Altyn fault in the middle-late Jurassic- early Cretaceous and should be related to the accretion of Lhasa block to the north. The sample from the middle shear zone of the Altyn fault belt yields two plateau ages of 36.4 and 26.3 Ma, respectively, suggesting the strike-slip move-ment with strong metamorphism at greenschist facies along the Altyn fault in the late Eocene. This event occurred in the most areas of the northern Tibet Plateau and should be in response in the north to the collision between Indian and Eurasian continents. The present study demonstrates that the Altyn fault is characterized by multiple pulse-style activi-ties under the tectonic setting of convergence between the Indian and Eurasian continents.LIU Yongjiang1, J. Genser2, GE Xiaohong1, F. Neubauer2, G. Friedl2, CHANG Lihua1, REN Shoumai3 & R. Handler2 1. College of Earth Sciences, Jilin University, Changchun 130061, China 2. Institute of Geology and Paleontology, Salzburg University, Salzburg A-5020, Austrilia 3. Statigraphic Research Center for Oil and Natural Gas, Ministry of Land and Resources, Beijing 100034, China Correspondence should be addressed to Liu Yongjiang (e-mail: liuyj@ email.jlu.edu.cn) 2003Chinese Science Bulletin2003,48,18:28
12Implementation of Envelope Analysis on a Wireless Condition Monitoring System for Bearing Fault Diagnosis显示文摘Envelope analysis is an effective method for characterizing impulsive vibrations in wired condition monitoring(CM)systems. This paper depicts the implementation of envelope analysis on a wireless sensor node for obtaining a more convenient and reliable CM system. To maintain CM performances under the constraints of resources available in the cost effective Zigbee based wireless sensor network(WSN), a low cost cortex-M4 F microcontroller is employed as the core processor to implement the envelope analysis algorithm on the sensor node. The on-chip 12 bit analog-to-digital converter(ADC) working at 10 k Hz sampling rate is adopted to acquire vibration signals measured by a wide frequency band piezoelectric accelerometer. The data processing flow inside the processor is optimized to satisfy the large memory usage in implementing fast Fourier transform(FFT) and Hilbert transform(HT). Thus, the envelope spectrum can be computed from a data frame of 2048 points to achieve a frequency resolution acceptable for identifying the characteristic frequencies of different bearing faults. Experimental evaluation results show that the embedded envelope analysis algorithm can successfully diagnose the simulated bearing faults and the data transmission throughput can be reduced by at least 95% per frame compared with that of the raw data, allowing a large number of sensor nodes to be deployed in the network for real time monitoring.Guo-Jin Feng James Gu Dong Zhen Mustafa Aliwan Feng-Shou Gu Andrew D.Ball 2015International Journal of Automation and computing2015,12,1:28
13Late Quaternary surface deformation and rupture behavior of strong earthquake on the segment north of Mianning of the Anninghe fault显示文摘The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region. Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811, 1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a. The strong earthquake activity shows a clustering character. The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.RAN YongKang CHEN LiChun CHENG JianWu GONG HuiLing 2008Science China Earth Sciences2008,51,9:25
14An ophiolitic tectonic melange first discovered in Huashan area, south margin of Qinling Orogenic Belt, and its tectonic implications显示文摘On the basis of the synthetic studies of geology and geochemistry, an ophiolitic tectonic melange was discovered in Sanligang-Sanyang area, the western part of Xiangfan-Guangji fault, the south margin of the Qinling Orogenic Belt. It is composed of different tectonic blocks with different lithological features and ages, mainly including the Huashan ophiolite blocks, Xiaofu Island-arc volcanic blocks, pelagic sediments, fore-arc volcanic-sedimentary system, and the massif of the basement and the covering strata of the Yangtze Block. These massifs were emplaced in the western part of Xiangfan-Guangji fault, the boundary between the Qinling Orogenic Belt and Yangtze Block, contacting each other by a shear zone or chaotic matrix. The characteristics of geochemistry indicate that the basalts of the Huashan ophiolite are similar to mid-oceanic ridge basalts (MORB) formed in an initial oceanic basin, and the Xiaofu volcanic rocks are formed in a tectonic setting of island arc. The ophiolitic tectonic melange董云鹏 张国伟 赖绍聪 周鼎武 朱炳泉 1999Science China Earth Sciences1999,42,3:24
15Average slip rate, earthquake rupturing segmentation and recurrence behavior on the Litang fault zone, western Sichuan Province, China显示文摘The Litang fault zone (LFZ) is an active fault zone within the northwestern Sichuan sub-block. Field investigation reveals new evidence for its late Quaternary offset, neoteric earthquake ruptures and surface-rupturing segmentation, from which long-term slip-rates, char-acteristic earthquake magnitudes and recurrence intervals on the fault zone are estimated. This study shows that the LFZ consists of three subordinate faults, and they are the northern Maoyaba fault, Litang fault and Kangga-Dewu fault, respectively. All of them are dominated by left-lateral strike-slip with reverse dip-slip component on different segments. Based on offset landforms and ages of relevant deposits collected from seven sites, it is estimated that the average left-lateral slip-rate on the LFZ reaches 4.0±1.0 mm/a in the past 14 ka BP, and vertical (reverse) dip-slip rate in the range of 0.1―1.8 mm/a. Three subordinate faults are independent earthquake rup-turing segments, on which the maximum moment magnitude of the characteristic earthquakes is estimated to be 7.0―7.3, and their average recurrence interval to be 500―1000 a. The latest earthquake ruptures occurred 119±2 years ago on the northern Maoyaba fault, about 1890 AD on the Litang fault, and in 1948 AD on the Kangga-Dewu fault, and this may indicate a unidirectional migration for surface rupturing earthquakes along the Litang fault zone, related to stress trigger-ing between the segments.XU Xiwei1, WEN Xueze2, YU Guihua1, ZHENG Rongzhang1, LUO Haiyuan2 & ZHENG Bin2 1. Institute of Geology, China Earthquake Administration, Beijing 100029, China 2. Earthquake Administration of Sichuan Province, Chengdu 610041, China 2005Science China Earth Sciences2005,48,8:23
16Multistage Extension and Age Dating of the Xiaoqinling Metamorphic Core Complex,Central China显示文摘There are two extensional systems in the Xiaoqinling metamorphic core complex (XMCC). One is the detachment fault system developed along the peripheries of the XMCC, which extended in an ESE-WNW direction and whose upper plate moved towards the WNW. The other extensional system includes the retrograde shear zones and normal faults developed within the XMCC, which represent the collapse of the XMCC. Ar-Ar and K-Ar dating shows that the extension of the detachment fault system continued from 135 to 123 Ma, i.e. in the late stage of its evolution at about 127 Ma. The collapse represented by the extensional system within the XMCC was operative during 120-106 Ma, and its main activity occurred about 116 Ma ago. These suggest that the XMCC experienced two extensional stages in its evolution, i.e., the syn-orogenic regional extension and post-orogenic collapse extension.ZHANG Jinjiang ZHENG Yadong 1999Acta Geologica Sinica(English Edition)1999,73,2:22
17The Yaean Metamorphic Core Complex and Extensional Detachment Fault in Inner Mangolia, China显示文摘The article describes the characteristics of the Yagan metamorphic core complex, especially the associated detachment fault and various extensional structures in its footwall. The age of the complex is discussed in some detail as well. The basic features of the Yagan metamorphic complex (Jurassic in age) are similar to those of the metamorphic core complex (Tertiary in age) in the Cordilleran area; they are as follows: (a) mylonitic gneisses in the footwall, (b) chloritized sheared mylonitic rocks, (c) pseudotachylites and flinty cataclasites or microbreccias, (d) unmetamorphosed or epimetamorphic rocks in the hanging wall with a layer of fault gouges or incohesive fault breccia next to the detachment fault. In contrast to its Cordilleran counterpart, however, there are many extensional faults with different styles (from dactile low-angle normal faults through brittle-ductile to brittle high-angle normal faults)in the footwall.Zheng Yadong and Zhang QingDepartment of Geology, Peking University 1994Acta Geologica Sinica(English Edition)1994,68,2:23
18Newly-generated Daliangshan Fault Zone—Shortcutting on the central section of Xianshuihe-Xiaojiang fault system显示文摘The Daliangshan fault zone is the eastern branch in the central section of Xianshuihe-Xiaojiang fault system. It has been neglected for a long time, partly because of no destructive earthquake records along this fault zone. On the other hand, it is located on the remote and inaccessible plateau. So far it was excluded as part of the Xianshuihe-Xiaojiang fault system. Based on the interpretation of aerophotographs and field investigations, we document this fault zone in detail, and give an estimation of strike-slip rate about 3 mm/a in Late Quaternary together with age dating data. The results suggest that the Daliangshan fault zone is a newly-generated fault zone resulted from shortcutting in the central section of Xianshuihe-Xiaojiang fault system because of the clockwise rotation of the Southeastern Tibetan Crustal Block, which is bounded by the Xianshuihe-Xiaojiang fault system. Moreover, the shortcutting may make the Daliangshan fault zone replace the Anninghe and Zemuhe fault zones gradually, and finally, the later two fault zones will probably die out with the continuous clockwise rotation.IKEDA Yasutaka TOGO Masayoshi TAJIKARA Masayoshi ECHIGO Tomoo OKADA Shinsuke 2008Science China Earth Sciences2008,51,9:23
19Deep crustal structures of eastern China and adjacent seas revealed by magnetic data显示文摘Through reduction to the North Pole and upward continuation of the total field magnetic anomalies, we analyze magnetic patterns and spatial distributions of different tectonic blocks and crustal faults in eastern China and adjacent seas. Depths to the Curie isotherms are further estimated from radially averaged amplitude spectra of magnetic data reduced to the pole. Data reductions effectively enhance boundaries of regional tectonic belts, such as the Dabie ultra-high metamorphic belt, the Tanlu Fault, and the Diaoyudao Uplift. Curie depths are estimated at between 19.6 and 48.9 km, with a mean of 31.7 km. The Subei Basin and the south Yellow Sea Basin in the lower Yangtze block show relatively deep Curie isotherms, up to about 35 km in depth, whereas in the surrounding areas Curie depths are averaged at about 25 km. This implies that the lower Yangtze Block has experienced a unique tectonic evolution and/or has unique basement lithology and structures. From a regional perspective, sedimentary basins, such as the Subei Basin, the south Yellow Sea Basin, and the East China Sea Basin, normally show deeper Curie isotherms than surrounding uplifts such as the Diaoyudao Uplift and the Zhemin Uplifts. Curie isotherms also upwell significantly in volcanically active areas such as the Ryukyu Arc and the Cheju Island, confirming strong magmatic and geothermal activities at depth.LI ChunFeng CHEN Bing ZHOU ZuYi 2009Science China Earth Sciences2009,52,7:21
20郯庐断裂带张八岭隆起南段肥东群石榴角闪岩变质P-T演化史对其构造属性的制约显示文摘通过对张八岭隆起南端肥东群中磁铁石榴铁闪石岩的岩相学、矿物成分分析和热力学评价,并结合野外地质填图和共生围岩分析表明,该岩石经历了5期变质作用,展现了顺时针的P-T演化特征,早期阶段表现为近等压升温,晚期阶段为降温降压的过程,其峰期变质平均P-T条件为:524℃和0.49GPa。结合地质背景和郯庐断裂带的演化特征分析,早期过程可能反映的扬子基底所经历的区域变质过程,晚期过程可能是由于郯庐断裂的后期抬升分量所致,不具有造山带的P-T演化特征。对比前人对宿松群的变质演化历史的研究,肥东群和宿松群峰期变质压力差可达0.8GPa,表明两者属于不同变质级别的块体。因而,肥东群和宿松群不能作为被郯庐断裂左行错开的标志层。由此表明,张八岭隆起南段所出露的肥东群变质杂岩,属于扬子板块上的变质基底,郯庐断裂带活动中将其剥露地表,并没有经历过大别造山带的变质作用。石永红 朱光 王道轩 2009岩石学报2009,25,12:21
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