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1.
THE CRUSTAL STRUCTURE OF NORTHEASTERN TIBET: A RESULT OF RECEIVER FUNCTION ANALYSIS FOR TELESEISMIC P WAVEFORM 相似文献
2.
Wang Xiaofeng Yin An Peter Rumelhart Eric Cowgill Chen Xuanhua Chen Zhengle T.Mark Harrison Zhang Yueqiao Zhang Qing Zhou Xianqiang WT ”BX 《地学前缘》2000,(Z1)
THE FORMATION AND EVOLUTION OF ALTYN TAGH FAULT SYSTEM AND ITS RELATIONSHIP TO THE GROWTH OF TIBETAN PLATEAUtheNational(G19980 4 0 80 0 )andthefundofOpeningLaboratoriesofGeomechanics 相似文献
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MODELING v_P AND Q ON EXPLOSION SEISMOLOGY DATA IN NE TIBET 相似文献
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D. M. Finlayson R. J. Korsch R. A. Glen J. H. Leven D. W. Johnstone 《Australian Journal of Earth Sciences》2013,60(2):311-321
A 2‐D crustal velocity model has been derived from a 1997 364 km north‐south wide‐angle seismic profile that passed from Ordovician volcanic and volcaniclastic rocks (Molong Volcanic Belt of the Macquarie Arc) in the north, across the Lachlan Transverse Zone into Ordovician turbidites and Early Devonian intrusive granitoids in the south. The Lachlan Transverse Zone is a proposed west‐northwest to east‐southeast structural feature in the Eastern Lachlan Orogen and is considered to be a possible early lithospheric feature controlling structural evolution in eastern Australia; its true nature, however, is still contentious. The velocity model highlights significant north to south lateral variations in subsurface crustal architecture in the upper and middle crust. In particular, a higher P‐wave velocity (6.24–6.32 km/s) layer identified as metamorphosed arc rocks (sensu lato) in the upper crust under the arc at 5–15 km depth is juxtaposed against Ordovician craton‐derived turbidites by an inferred south‐dipping fault that marks the southern boundary of the Lachlan Transverse Zone. Near‐surface P‐wave velocities in the Lachlan Transverse Zone are markedly less than those along other parts of the profile and some of these may be attributed to mid‐Miocene volcanic centres. In the middle and lower crust there are poorly defined velocity features that we infer to be related to the Lachlan Transverse Zone. The Moho depth increases from 37 km in the north to 47 km in the south, above an underlying upper mantle with a P‐wave velocity of 8.19 km/s. Comparison with velocity layers in the Proterozoic Broken Hill Block supports the inferred presence of Cambrian oceanic mafic volcanics (or an accreted mafic volcanic terrane) as substrate to this part of the Eastern Lachlan Orogen. Overall, the seismic data indicate significant differences in crustal architecture between the northern and southern parts of the profile. The crustal‐scale P‐wave velocity differences are attributed to the different early crustal evolution processes north and south of the Lachlan Transverse Zone. 相似文献
5.
青藏高原是当今世界上最高、最大和最年轻的高原。青藏高原的地球动力学研究是一个复杂而饶有兴趣的问题。本文试图从高原的范围、地球物理特征、地震活动、构造演化和新构造运动等方面探讨其地球动力学过程。 从新构造分析,笔者着重指出,青藏高原是欧亚大陆板块中最活动的一个块体,它在造就中国乃至东亚新构造运动的格局方面,是一个十分重要的因素。 相似文献
6.
青藏高原隆升对新疆天山山脉地壳-上地幔构造的影响 总被引：1，自引：0，他引：1
依据地震层析和接收函数的结果获得了天山山脉东段和西段的深部构造的速度图像,探讨了印度板块向北推进和青藏高原隆升对天山山脉造山作用的影响以及天山山脉不同地段的地壳上地幔构造的差异。克拉玛依—库车剖面上清楚地展示出,天山是由高速和低速的地体拼合而成。来自塔里木的高速体向北俯冲到天山达200km以下的深度,而来自准噶尔盆地的高速体则没有明显地向南推进,说明由南向北的推进是很强的,它是造成天山山脉继续隆升的主要动力,从而造就了天山山脉。天山山脉在Moho面以上的部分是中天山北缘断裂和中天山南缘断裂之间的低速体与两侧的高速体拼合成的,其南北宽度约350km,向深度延伸越过200km。塔里木盆地和准噶尔盆地均为高速体的范围,天山山脉东段Moho面以上的地壳部分,南部高速体有向北推进和俯冲的特征,但不明显。夹在两盆地之间的天山主要为低速体,仅在乌鲁木齐和北天山山前断裂以南有残留的高速体,深度不超过30km,这表明天山是由速度不同的地质体挤压而拼合成的。天山延伸到乌鲁木齐以东,向深部的延伸仅仅100km上下。在富蕴—库尔勒剖面上,塔里木板块向北的推进相对于克拉玛依—库车剖面有所减弱。天山西段表现出强烈的造山作用,向东逐步减缓,到达天山的东段,虽然天山深部的构造活动仍然在继续进行,地震活动频繁,可是,活动区域集中在天山底部不过100km上下。说明山根的范围比西部减少了近一半。 相似文献
7.
TECTONIC EVOLUTION OF THE WESTERN KUNLUN AND KARAKORAM MOUNTAINS—SOME NEW OBSERVATIONS FROM A MULTI-DISCIPLINARY GEOSCIENTIFIC TRANSECT (MGT) IN NW TIBET 相似文献
8.
红河断裂带两侧地震震源机制及构造意义 总被引：8，自引：1，他引：7
红河断裂带是一条大型的走滑断裂带。根据印支半岛前新生代的古地块与华南地块的接触关系 ,将红河断裂带海陆部分分为两段。断裂带自第三纪以来 ,经历了左旋运动、右旋运动 ,南北两段的活动性有一定的差异。根据断裂带两侧地震和震源机制解分析 ,震源深度 0～ 33km的地震在整个区域密集分布 ,较深的地震分布在断裂的北东侧。断裂带西北部断裂活动方式为逆冲型 ,北部为正断型 ,南部为走滑型 ,其它地方为奇异型 ,也即是逆冲型、正断型、走滑型 3种方式的过渡类型 ,反映了红河断裂带及其周围地区受到来自北北西向的推挤力和北东东向的正压力的联合作用 ,使受力区的断裂发生挤压逆冲、水平走滑和拉张正断运动。 相似文献
9.
THE NORTHWARD PROPAGATION OF THE ARC TECTONICS OF THE NORTHEAST PAMIR AND NORTHWEST TARIM BASINThisworkispartoftheresearchproject“themechanismofJiashistrongearthquakeswarmandprediction
ofearthquakeriskinthenortheastPamir 相似文献
10.
利用天然地震环境噪声成像研究柴达木盆地及邻区的岩石圈结构,利用工业地震剖面研究新生代构造变形的几何学与运动学特征,在此基础上讨论柴达木盆地新生代的成盆动力学过程与演化。柴达木盆地及邻区的岩石圈表现出向南和向北挠曲的特征。其中,东昆仑-可可西里地区地壳深度30～40 km 的低速层向北抬升,可与柴达木盆地内部深度15 km 左右的低速区相连接,反映了东昆仑-祁漫塔格山向柴达木盆地的逆冲推覆作用,因此在岩石圈尺度上,柴达木新生代成盆动力学过程与前陆盆地是相似的,表现为构造负荷引起的挠曲沉降。柴达木盆地新生代构造变形受控于柴西南和柴北缘两期冲断系统,柴北缘冲断系统形成于古新世-始新世路乐河-下干柴沟期,主要记录于祁连山山前、阿尔金山山前北段及冷湖和鄂博梁深层;柴西南冲断系统形成于早中新世下油砂山期以来,现今盆地南部的北西向构造带和盆地北部的冷湖和鄂博梁浅层构造都属于这期冲断系统。由于柴西南冲断系统的前锋构造已扩展至柴达木盆地北缘,并受到阿尔金山和祁连山的阻挡,缺少稳定的台盆区,因而使得柴达木盆地新生界不发育前陆盆地特有的楔状沉积结构。柴西南和柴北缘两期冲断系统的叠加,不仅使得柴达木新生代构造变形在时间和空间上呈现有次序的分布,也使得新生代盆地呈现出开启到封闭的演化格局,从而对新生界油气生成和聚集产生了重要影响。 相似文献
11.
We investigated the seismic shear-wave velocity structure of the crust beneath nine broadband seismological stations of the Shillong–Mikir plateau and its adjoining region using teleseismic P-wave receiver function analysis. The inverted shear wave velocity models show ∼34–38 km thick crust beneath the Shillong Plateau which increases to ∼37–38 km beneath the Brahmaputra valley and ∼46–48 km beneath the Himalayan foredeep region. The gradual increase of crustal thickness from the Shillong Plateau to Himalayan foredeep region is consistent with the underthrusting of Indian Plate beyond the surface collision boundary. A strong azimuthal variation is observed beneath SHL station. The modeling of receiver functions of teleseismic earthquakes arriving the SHL station from NE backazimuth (BAZ) shows a high velocity zone within depth range 2–8 km along with a low velocity zone within ∼8–13 km. In contrast, inversion of receiver functions from SE BAZ shows high velocity zone in the upper crust within depth range ∼10–18 km and low velocity zone within ∼18–36 km. The critical examination of ray piercing points at the depth of Moho shows that the rays from SE BAZ pierce mostly the southeast part of the plateau near Dauki fault zone. This observation suggests the effect of underthrusting Bengal sediments and the underlying oceanic crust in the south of the plateau facilitated by the EW-NE striking Dauki fault dipping 300 toward northwest. 相似文献
12.
JIANG Mei XUE Guangqi SU Heping QIAN Hui WEI Suhua DONG Yingjun Institute of Mineral Resources CAGS Beijing China E. KISSLING ETH-Hongebeg Institute for Geophysical CH- ZURICH Switzeland G. POUPINET LGIT-IRIGM Univercite Joseph F 《Continental Dynamics》2000,(1)
1. IntoductionSponsored by the National 305 Program, China, a teleseismic experiment was performed jointly by the Chinese Academy of Geological Sciences and the French Scientific Research Center in Tian Shan area from June 1997 to February 1998. The array was mostly deployed along the main road, starting from Karamay in the north to Kuqa in the south. Geologically, the 700 km-long profile covers the Junggar basin, the Tian Shan Mts., the Bo-A Fault and the Korla Fault, ending in nort… 相似文献
13.
EARTHQUAKE FOCAL MECHANISM AND ITS TECTONIC SIGNIFICANCE ALONG THE TWO SIDES OF THE RED RIVER FAULT ZONE 总被引：1，自引：0，他引：1
The Red River Fault Zone is a gigantic slide-slip fault zone extending up to 1000km from Tibet to South China Sea. It has been divided into the north, central and south segments according to the difference of the geometry, kinetics, and seismicity on the land, but according to the contacted relationship between the old pre-Cenozoic block in Indochina Peninsula and the South China block, the Red River Fault Zone was divided into two parts extending from land to ocean, the north and south segments. Since the Tertiary, the Red River Fault Zone suffered first the sinistral movement and then the dextral movement. The activities of the north and the south segments were different. Based on the analysis of earthquakes and focal mechanism solutions, earthquakes with the focus depths of 0-33km are distributed over the whole region and more deep earthquakes are distributed on the northeastern sides of the Red River fault. Types of faulting activities are the thrust in the northwest, the normal in the north and the 相似文献
14.
Crustal structure of the northeastern margin of the Tibetan plateau from the Songpan-Ganzi terrane to the Ordos basin 总被引：20，自引：0，他引：20
Mingjun Liu Walter D. Mooney Songlin Li Nihal Okaya Shane Detweiler 《Tectonophysics》2006,420(1-2):253
The 1000-km-long Darlag–Lanzhou–Jingbian seismic refraction profile is located in the NE margin of the Tibetan plateau. This profile crosses the northern Songpan-Ganzi terrane, the Qinling-Qilian fold system, the Haiyuan arcuate tectonic region, and the stable Ordos basin. The P-wave and S-wave velocity structure and Poisson's ratios reveal many significant characteristics in the profile. The crustal thickness increases from northeast to southwest. The average crustal thickness observed increases from 42 km in the Ordos basin to 63 km in the Songpan-Ganzi terrane. The crust becomes obviously thicker south of the Haiyuan fault and beneath the West-Qinlin Shan. The crustal velocities have significant variations along the profile. The average P-wave velocities for the crystalline crust vary between 6.3 and 6.4 km/s. Beneath the Songpan-Ganzi terrane, West-Qinling Shan, and Haiyuan arcuate tectonic region P-wave velocities of 6.3 km/s are 0.15 km/s lower than the worldwide average of 6.45 km/s. North of the Kunlun fault, with exclusion of the Haiyuan arcuate tectonic region, the average P-wave velocity is 6.4 km/s and only 0.5 km/s lower than the worldwide average. A combination of the P-wave velocity and Poisson's ratio suggests that the crust is dominantly felsic in composition with an intermediate composition at the base. A mafic lower crust is absent in the NE margin of the Tibetan plateau from the Songpan-Ganzi terrane to the Ordos basin. There are low velocity zones in the West-Qinling Shan and the Haiyuan arcuate tectonic region. The low velocity zones have low S-wave velocities and high Poisson's ratios, so it is possible these zones are due to partial melting. The crust is divided into two layers, the upper and the lower crust, with crustal thickening mainly in the lower crust as the NE Tibetan plateau is approached. The results in the study show that the thickness of the lower crust increases from 22 to 38 km as the crustal thickness increases from 42 km in the Ordos basin to 63 km in the Songpan-Ganzi terrane south of the Kunlun fault. Both the Conrad discontinuity and Moho in the West-Qinling Shan and in the Haiyuan arcuate tectonic region are laminated interfaces, implying intense tectonic activity. The arcuate faults and large earthquakes in the Haiyuan arcuate tectonic region are the result of interaction between the Tibetan plateau and the Sino–Korean and Gobi Ala Shan platforms. 相似文献
15.
中国东北地区地震空间分布与主要断裂带、深部构造及应力场关系 总被引：5，自引：1，他引：4
中国东北地区在北东东向应力场控制下, 地震有其特殊性。地震空间分布和深度统计结果表明, 东北地区地震主要受岩石圈断裂(开原-赤峰断裂带) 控制, 以44°N为界, 南北具有明显差异。北部地震发生的数量少于南部, 震源深度主要集中在4～6 km和8～12 km两个深度范围内; 而南部主要集中在8～12 km和28～30 km两个深度范围内。发震深度分析显示, 开原-赤峰、郯庐断裂带、大兴安岭断裂带下可能存在地温较低的区域, 使地震可以在深部孕育。地震分布的Vp和Vs剖面资料的研究暗示, 断裂与速度变化带、断裂与断裂的相交区域是地震易发生区域。 相似文献
16.
Lower-crust S-wave velocity beneath western Yunnan Province from waveform inversion of dense seismic observations 总被引：5，自引：0，他引：5
We use teleseismic body waveforms to explore S-wave layered velocity structures beneath 30 portable digital seismic stations deployed around western Yunnan Province. Results show that the Moho depth in this region is ∼40 km and decreases in general from north to south, consistent with previous geophysical studies. Associated with this lateral variation of the Moho depth, the lower crust above the Moho discontinuity has a 15–25 km thick zone with an S-wave velocity lower than that of the upper crust. This lower velocity zone might be interpreted as a lower crust weak channel, which may mechanically partially decouple the upper-crust deformation from the underlying mantle. Thus, the inverted S-wave velocity structure could provide new evidence for the lateral flow of lower crust in the build-up of the south-eastern Tibetan plateau. 相似文献
17.
基于四川防震减灾信息网以及中国地震台网中心、中国地震信息网、国家地震科学数据共享中心提供的汶川8．0级地震目录资料,对2008年S月12日至2010年3月1日共1613次3．0级及以上余震的地震序列进行了时空分布分析。结果表明：汶川8．0级地震的余震大致可分为7个阶段,主震后18天应列为大地震强余震发生的警戒时间;地震序列的b值为0．751,印证了在类型相同的情况下主震震级越大b值越高的观点;地震序列的P值为1．117,与全球地震衰减速率相当;汶川地震的余震分布主要沿龙门山断裂走向北东向扩展,且具有明显分区性,自南向北分为南、中、北3区段,南区为地震起始破裂段,地震后期余震则主要分布在北区;震源深度分布在10～40km,集中在10～20km,表明龙门山断裂主要发生在中上地壳,且震源深度由南向北呈现逐渐变浅的趋势;震源深度扩展,南区呈明显脉冲状,中区主要是依次由15、30、25km深度向深、浅层同时扩展,北区余震深度分布呈“乙”字型,最后稳定在15km左右。 相似文献
18.
DEEP SEISMIC SOUNDING EVIDENCE FOR TECTONIC INTERACTION BETWEEN TARIM AND WEST KUNLUN MT1 MatteP ,TapponnierP ,ArnaudN ,etal.TectonicofWesternTibet,betweentheTarimandtheIndus[J] .EarthPlanetSciLett,1996 ,14 2 :311～ 330
2 GaoRui,LiDexing,LuDeyuan ,etal.DeepseismicreflectionprofileacrosscontactzoneofwestKunlunandTarimalongtheXinjianggeotransectinNWChina[C] .14 thHKTworkshop ,1999.4 9～ 50 .… 相似文献
19.
东昆仑大地震的深部构造背景 总被引：4，自引：1，他引：3
本文以深地震测深剖面资料揭示的地壳结构形态为切入点 ,探讨东昆仑 8.1级大地震的深部构造背景。沱沱河—小柴旦长 5 0 0km的剖面范围内发现两处大的莫霍面错断 ,分别位于东昆仑 柴达木结合带之下和金沙江断裂之下。青藏高原北部的地壳厚度 6 1～ 75km :莫霍面具有一致南倾 ,逐步加深的产状及弱反射性特征 ;下地壳明显增厚 ,但速度未见明显降低 ;上地壳发育逆冲、走滑断裂 ;地壳中部存在低速层。北邻的柴达木盆地地壳相对刚性 ,厚 5 2± 2km。东昆仑及邻区的壳幔结构有利于强地震孕育。在印度板块向北推挤和柴达木地块的向南插入的区域挤压应力场中 ,青藏高原北部较弱的下地壳缩短增厚 ,变形过程中的蠕滑引起地壳浅部的应力放大。但NE向主压应力的作用不是大地震形成的唯一要素 ,与青藏高原北部各地体侧向运动有关。侧向运动速率和幅度的差异使应力在各地体的边界断裂积累并使其复活。而低速层对形成孕育大地震需要的“立交桥式”的局部应力环境是必不可少的条件。 相似文献
20.
Thirty magnetotelluric soundings were made along two NW–SE profiles to the north and south of Oaxaca City in southern Mexico. The profiles crossed the N–S Oaxaca Fault and the Oaxaca-Juarez terrane boundary defined by the Juarez mylonitic complex. Dimensionality analysis of the MT data showed that the subsurface resistivity structure is 2D or 3D. The Oaxaca and correlative Guichicovi terranes consist of ca. 1–1.4 Ga granulitic continental crust overlain by Phanerozoic sedimentary rocks, characterized by high and low resistivities, respectively. The Juarez terrane consists of oceanic Mesozoic metavolcanic and metasedimentary rocks, characterized by a low to medium resistivity layer, that is approximately 10 km thick. The Oaxaca Fault is a Cenozoic aged, normal fault that reactivated the dextral and thrust Juarez mylonitic complex north of Oaxaca City: its location south of Oaxaca City is uncertain. In the southern profile, the MT data show a ca. 20–50 km wide, west-dipping, relatively low resistivity zone material that extends through the entire crust. This is inferred to be the Juarez terrane bounded on either side by the ca. 1–1.4 Ga granulites. The Oaxaca Fault is imaged only by a major electrical resistivity discontinuity (low to the west, high to the east) along both the western border of the Juarez mylonitic complex (northern profile) and the San Miguel de la Cal mountains (southern profile) suggesting continuity. 相似文献