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1.
Shear wave velocity structure of the crust and upper mantle underneath the Tianshan orogenic belt 总被引：9，自引：1，他引：9
LI Yu LIU QiYuan CHEN JiuHui LI ShunCheng GUO Biao & LAI YuanGen State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing China 《中国科学D辑(英文版)》2007,50(3):321-330
From April, 2003 to September, 2004, a passive broadband seismic array consisting of 60 stations was deployed over the Tianshan orogenic belt by State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration. Among them, 51 stations make up an about 500-km-long profile across the Tianshan Mountains from Kuytun to Kuqa. The receiver function profile and S-wave velocity structure of the crust and upper mantle down to 100 km deep are obtained by using the re-ceiver function method (Liu et al. 1996, 2000). The main results can be summarized as follows: (1) A clear mountain root does not exist beneath the Tianshan Mountains, and the crust-mantle boundaries underneath the stations mostly have transitional structures. This implies that the material differentia-tion between the crust and mantle is not yet accomplished and the orogenic process is still going on. (2) The crust beneath the Tianshan Mountains has laterally blocked structures in direction perpendicular to the mountain strike, and the crust-mantle boundary has a clear dislocation structure. Both of them correspond to each other. (3) The offsets of the Moho discontinuity are highly correlated to the tectonic borders on the surface and that corresponding to the frontal southern Tianshan fault reaches to 14 km. This manifests that large vertical divergent movement took place between different blocks. This sup-ports the discontinuous model of the Tianshan orogeny, and the Tarim block subduction is restricted only to the southern side of the South Tianshan. (4) Inside the upper and middle crust of the Tianshan Mountains exist several low-velocity bodies correlated with high seismicity located on the moun-tain-basin jointures on both sides of the mountain and between different blocks, and the low-velocity bodies on the mountain-basin jointures are inclined obviously to the mountain. This implies that the low-velocity bodies may be correlated closely to the thrust and subduction of the basins on both sides of the mountain, the splicing of adjacent blocks and the fast uplift of the Tianshan Mountains. 相似文献
2.
JOINT INVERSION OF SURFACE WAVE DISPERSION AND RECEIVER FUNCTIONS FOR CRUSTAL AND UPPERMOST MANTLE STRUCTURE BENEATH CHINESE TIENSHAN AND ITS ADJACENT AREAS 
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下载免费PDF全文 The Tienshan orogenic belt is one of the most active intracontinental orogenic belts in the world. Studying the deep crust-mantle structure in this area is of great significance for understanding the deep dynamics of the Tienshan orogen. The distribution of fixed seismic stations in the Tianshan orogenic belt is sparse. The low resolution of the existing tomographic results in the Tienshan orogenic belt has affected the in-depth understanding of the deep dynamics of the Tienshan orogenic belt. In this paper, the observation data of 52 mobile seismic stations in the Xinjiang Seismic Network and the 11 new seismic stations in the Tienshan area for one-year observations are used. The seismic ambient noise tomography method is used to obtain the Rayleigh surface wave velocity distribution image in the range of 10~50s beneath the Chinese Tienshan and its adjacent areas (41°~48° N, 79°~91° E). The joint inversion of surface wave and receiver function reveals the S-wave velocity structure of the crust and uppermost mantle and the crustal thickness below the station beneath the Chinese Tienshan area(41°~46° N, 79°~91° E). The use of observation data from mobile stations and new fixed seismic stations has improved the resolution of surface wave phase velocity imaging and S-wave velocity structure models in the study area.
The results show that there are many obvious low-velocity layers in the crust near the basin-bearing zone in the northern Tienshan Mountains and the southern Tienshan Mountains. There are significant differences in the structural characteristics and distribution range of the low-velocity zone in the northern margin and the southern margin. Combining previous research results on artificial seismic profiles, receiver function profiles, teleseismic tomography, and continental subduction simulation experiments, it is speculated that the subduction of the Tarim Basin and the Junggar Basin to the Tienshan orogenic belt mainly occurs in the middle of the Chinese Tienshan orogenic belt, and the subduction of the southern margin of the Tienshan Mountains is larger than that of the northern margin, and the subduction of the eastern crust is not obvious or in the early subduction stage. There are many low-velocity layers in the inner crust of the Tienshan orogenic belt, and most of them correspond to the strong uplifting areas that are currently occurring. The thickness of the crust below the Tienshan orogenic belt is between 55km and 63km. The thickness of the crust(about 63km)is the largest near the BLT seismic station in the Bazhou region of Xinjiang. The average crustal thickness of the Tarim Basin is about 45km, and that of the Junggar Basin is 47km. The S-wave velocity structure obtained in this study can provide a new deep basis for the study of the segmentation of the Tienshan orogenic belt and the difference of the basin-mountain coupling type. 相似文献
The results show that there are many obvious low-velocity layers in the crust near the basin-bearing zone in the northern Tienshan Mountains and the southern Tienshan Mountains. There are significant differences in the structural characteristics and distribution range of the low-velocity zone in the northern margin and the southern margin. Combining previous research results on artificial seismic profiles, receiver function profiles, teleseismic tomography, and continental subduction simulation experiments, it is speculated that the subduction of the Tarim Basin and the Junggar Basin to the Tienshan orogenic belt mainly occurs in the middle of the Chinese Tienshan orogenic belt, and the subduction of the southern margin of the Tienshan Mountains is larger than that of the northern margin, and the subduction of the eastern crust is not obvious or in the early subduction stage. There are many low-velocity layers in the inner crust of the Tienshan orogenic belt, and most of them correspond to the strong uplifting areas that are currently occurring. The thickness of the crust below the Tienshan orogenic belt is between 55km and 63km. The thickness of the crust(about 63km)is the largest near the BLT seismic station in the Bazhou region of Xinjiang. The average crustal thickness of the Tarim Basin is about 45km, and that of the Junggar Basin is 47km. The S-wave velocity structure obtained in this study can provide a new deep basis for the study of the segmentation of the Tienshan orogenic belt and the difference of the basin-mountain coupling type. 相似文献
3.
天山起源于古生代的陆-陆碰撞作用,又经历了中新生代的典型陆内造山过程,其深浅构造结构和活动性一直是众多学者关注的热点。文中通过多种地球物理探测和综合地质构造分析, 以地学断面形式对其深浅构造进行填图,揭示了天山中段复杂的深浅构造特色。结果表明:沿古生代的陆-陆碰撞缝合带两侧分别呈现出主要构造地质单元由老到新的对称性,并伴有相应深部结构的复杂性,反映了碰撞过程及后期的构造演化特点;天山中部的上地幔顶部存在厚近 10km、宽近 200km、几乎涵盖整个天山的低速高导层,可能是中新生代以来天山的陆内再造山作用引起的壳幔拆沉作用形成的残留下地壳 相似文献
4.
利用2002~2003年中国地震局地质研究所台阵实验室以唐山大震区为中心布设的40个流动宽频带地震台站和首都圈数字台网的33个宽频带台站的远震数据,采用接收函数非线性反演方法得到其中72个宽频带台站下方60 km深度范围内的S波速度结构.根据得到的各台站下方地壳上地幔的S波速度结构,并综合刘启元等（1997）用接收函数非线性反演方法得到的延怀盆地15个宽频带流动台站下方的地壳上地幔S波速度结构模型,给出了39°N～41°N,114°E~119.5°E区域内沿不同走向、不同深度S波速度分布.由于综合了利用首都圈数字地震台网的宽频带台站以及流动地震台阵的观测数据,本文给出了较前人同类研究空间分辨率更好的结果.结果表明: (1)研究区的速度结构,特别是怀来以东的速度结构十分复杂.在10~20 km深度范围内,研究区地壳具有高速和低速异常块体的交错结构.研究区中上地壳速度结构主要被与张渤地震带大体重合的NW向高速条带和穿越唐山大震区的NE向高速条带所控制,而其中下地壳的速度结构主要为延怀—三河—唐山地区上地幔隆起所控制.(2)研究区内存在若干壳内S波低速体,它们主要分布在唐山,三河及延怀盆地等地区.在这些地区,壳内低速体伴随着壳幔界面的隆起和上地幔顶部速度结构的横向变化.(3)地表断层分布与地壳速度结构分区有较好的相关性,表明断层对不同块体有明显的控制作用.其中,宝坻断裂,香河断裂和唐山断裂均为超壳断裂.(4)首都圈内大地震的分布与壳内低速体及上地幔顶部的速度结构有密切关系.对于唐山大地震的成因,仅考虑板块作用引起的水平应力场是不够的,有必要充分重视由于上地幔变形引起的地壳垂直变形和上地幔物质侵入造成的热效应. 相似文献
5.
Seismic tomography beneath the orogenic belts and adjacent basins of northwestern China 总被引：2，自引：0，他引：2
Three-dimensional velocity images of the crust and upper mantle beneath orogenic belts and adjacent basins of the northwestern
continent of China are reconstructed by seismic tomography, based on arrival data of P wave recorded in seismic networks in
Xinjiang, Qinghai, Gansu of China and Kyrgyzstan. The velocity images of upper crust demonstrate the tectonic framework on
the ground surface. High velocities are observed beneath orogenic belts, and low velocities are observed in the basins and
depressions that are obviously related to unconsolidated sediments. The velocity image in mid-crust maintains the above features,
and in addition low velocities appear in some earthquake regions and a low velocity boundary separates the western Tianshan
Mts. from eastern Tianshan Mts. The orogenic belts and the northern Tibetan plateau have a Moho depth over 50 km, whereas
the depths of the Moho in basins and depressions are smaller than 50 km. The velocity images of upper mantle clearly reveal
the colliding relationship and location of deep boundaries of the continental blocks in northwestern China, indicating a weakness
of the upper mantle structure of orogenic belts. The top depth of upper mantle asthenosphere varies from place to place. It
seems shallower under the northern Tibetan plateau, Altay and Qilian Mts., and deeper under the Tarim and Tianshan regions.
Hot mantle probably rose to the bottom of some orogenic belts along tectonic boundaries when continental blocks collided to
each other. Therefore their dynamic features are closely correlated to the formation and evolution of orogenic belts in northwestern
China. 相似文献
6.
LIU Qiyuan Rainer Kind CHEN Jiuhui YUAN Xiaohui LI Shuncheng GUO Biao Kurt Wylegalla & LAI Yuangen . State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing China . GeoForschungZentrum Potsdam Telegrafenburg A Potsdam D- Germany 《中国科学D辑(英文版)》2005,48(7)
The Dabie Shan is located on the eastern side of the Qinling-Dabie orogenic belt, which marks a geological boundary between the Sino-Korean and Yangtze cra- ton. Since the 1980s, the discovery of coesite and mi- crodiamond in the Dabie Shan orogen motivates an extensive interest to the ultra-high pressure (UHP)metamorphism and its exhumation[1,2]. Many results about them were published, which deal with different disciplines, including tectonics, petrology and chro- nology[3?8]. Up to now,… 相似文献
7.
库尔勒—吉木萨尔剖面横跨塔里木盆地北缘、天山造山带和准噶尔盆地南缘.沿剖面完成了重磁联合反演,获得了岩石圈二维密度结构与二维磁性结构.结果发现,塔里木盆地与准噶尔盆地向天山造山带对冲.在地壳范围内,塔里木盆地北缘与准噶尔盆地南缘的平均密度较高,天山造山带的地壳平均密度较低.天山造山带具有较高的磁化强度,尤其表现在准噶尔盆地南缘至天山造山带中部的整个地壳范围内,预示着天山南北可能具有不同的构造演化历史、构造运动方式以及构造运动强度.在塔里木盆地与天山造山带以及准噶尔盆地与天山造山带的接触部位的上地幔顶部分别发现了低密度体,推测在塔里木盆地由南而北向天山造山带“层间插入与俯冲消减”,以及准噶尔盆地由北而南向天山造山带俯冲的过程中塔里木盆地北缘和准噶尔盆地南缘下地壳物质被带进天山造山带上地幔顶部.库尔勒—吉木萨尔剖面岩石圈二维密度结构与磁性结构为天山造山带的构造分段提供了岩石圈尺度的依据. 相似文献
8.
中国境内天山地壳上地幔结构的地震层析成像 总被引：23，自引：5，他引：18
根据横跨中国境内天山的库车—奎屯宽频带流动地震台阵和区域地震台网记录的近震和远震P波走时数据,利用地震层析成像方法重建了沿该地震台阵剖面下方400 km深度范围内地壳上地幔的P波速度结构.结果表明：沿新疆库车—奎屯剖面,天山地壳具有明显的横向分块结构,且南、北天山地壳显示了较为强烈的横向变形特征,表明塔里木地块对天山地壳具有强烈的侧向挤压作用;在塔里木和准噶尔地块上地幔顶部有厚度约60～90 km的高速异常体,塔里木—南天山下方的高速异常体产生了较为明显的弯曲变形,而准噶尔—北天山下方的高速异常体向南一直俯冲到中天山南侧边界下方300 km的深度,两者形成了不对称对冲构造;在塔里木和准噶尔地块下方150～400 km深度存在上地幔低速体,其中塔里木地块一侧的上地幔低速物质上涌到南天山地块的下方;在塔里木—南天山200～300 km深度范围的上地幔存在高速异常体,它可能是地幔热物质向上迁移过程融断的塔里木岩石圈的拆离体. 上述结果表明,塔里木地块的俯冲可能涉及整个岩石圈深度,但其前缘仅限于南天山的北缘;青藏高原隆升的远程效应可能不但驱动塔里木岩石圈向北俯冲,同时还造成天山造山带南侧上地幔物质的涌入;天山造山带上地幔广泛存在的低速异常有助于其上地幔的变形,而上地幔物质的强烈非均匀性应有助于推动天山造山带上地幔小尺度地幔对流的形成;根据研究区地壳上地幔速度结构特征推断,新近纪以来天山快速隆升的主要力源来自青藏高原快速隆升的远程效应,相对软弱的上地幔为加速天山造山带的变形和隆升创造了必要条件. 相似文献
9.
天山地区地质构造复杂,地震活动频繁,其壳幔变形和深部结构一直受到学者们的高度关注.然而,由于天山地区地震台站资料较少,致使壳幔变形研究结果与解释存在诸多争议.本研究利用在天山地区（40°N-46°N,78°E-92°E）新布设的11个流动宽频带地震台站和该地区39个固定台站的观测资料,采用接收函数与面波联合反演方法,获得了研究区地壳厚度及壳幔S波速度结构.反演结果显示天山地区（41.5°N-44°N,78°E-88°E）平均地壳厚度为56 km,塔里木盆地（40°N-41.5°N,79°E-90°E）、准噶尔盆地（44°N-46°N,82°E-90°E）和吐鲁番盆地（42°N-43°N,88°E-90°E）具有较厚的沉积层,地壳平均厚度为43 km、53 km和46 km,整体表现为天山厚、盆地相对较薄的特征;在研究区南天山的最高峰（42°N,80.5°E）及北天山的最高峰（43.5°N,86°E）附近,中下地壳存在较厚的低速层,我们认为在强烈挤压作用下低速、低强度的中下地壳强烈变形可能是导致该区域快速隆升的主要原因.在研究区中部,位于塔里木盆地与准噶尔盆地之间的天山地区,中下地壳及上地幔均存在低速层,且盆地莫霍面向天山倾斜明显.结合前人的研究成果推测,在南北向构造挤压应力作用下,塔里木盆地与准噶尔盆地发生了向天山造山带方向的双向壳幔层间插入俯冲.在研究区东部,塔里木盆地东北缘与天山东部接触带的地壳内没有明显的低速层,推测应处在早期挤压变形状态,该区域的壳幔边界为缓变的速度梯度带,可能与上地幔热物质侵入或渗透有关. 相似文献
10.
利用中美德INDEPTH IV合作项目2007—2009年间布置于青藏高原中、北部140个宽频地震台站记录到的天然地震数据,经过接收函数成像处理,获得了3条穿过昆仑—阿尼玛卿缝合带清晰的壳幔结构图像.结果显示柴达木南缘莫霍面位于约50 km深度,羌塘地块、可可西里地块、东昆仑造山带莫霍面位于约65 km深度,昆仑—阿尼玛卿缝合带以北约50 km存在莫霍面深度突变.在可可西里和柴达木岩石圈地幔之间观测到北倾界面,这可能是可可西里岩石圈向北俯冲到柴达木地幔之下的证据.可可西里地块地壳内宽缓的负转换震相带是低速带的反映,其向北挤入到东昆仑山下发生挤压增厚,可能是东昆仑山隆升的原因;由于刚性柴达木岩石圈的阻挡,物质向东改向,则可能是该地区向东旋转的构造应力场产生的原因.本文研究结果不支持亚洲岩石圈地幔在东昆仑—柴达木交界处向南俯冲,据此,我们提出了新的东昆仑造山模式. 相似文献
11.
The Central Asian Orogenic Belt (CAOB) represents the world's largest Phanerozoic accretionary orogen, the major phase of which was built during the closure of the Paleo-Asian Ocean. The Tianshan orogenic belt forms the southwestern segment of the CAOB and has been the focus of investigations related to the evolution of the CAOB. Here we present results from an analysis of the crustal structure and upper mantle discontinuity beneath the Chinese Tianshan by employing H-k stacking technique as well as depth domain and synthetic receiver functions. Our results identify a double peak of Moho Ps in the Tianshan orogenic belt, suggesting the possibility of insertion of the lower crust of the Tarim Basin into this belt, with the latter retaining its initial crustal architecture. Our results provide insights into the dynamics of northward extrusion and the N–S trending crustal shortening of the Tianshan orogen during the convergence of the India and Eurasia blocks. 相似文献
12.
为了研究天山造山带的地球动力学,自1970年代以来,国内外在天山造山带开展了大量的深部探测工作,并取得了丰富的成果,本文对这些工作和成果进行了梳理和综述.已有研究结果表明:天山造山带的地壳厚度较大,但并无明显山根;地壳结构具有垂向分层和横向分块特征;壳幔界面不清晰,莫霍面在盆山接合部下方发生错断;壳内普遍发育低速异常体,地壳泊松比较高,暗示了地壳力学上的弱化作用;上地幔也存在波速异常体,低速异常可能与地幔热物质上涌有关,高速体可能是古老板块的岩石圈拆离碎片;莫霍面错断、Q值结构和波速异常特征可以用天山南北侧稳定地质块体往天山造山带之下俯冲来解释,这也得到高分辨率层析成像结果的支持;剪切波分裂结果暗示有相当厚的上地幔卷入了造山过程.上述资料表明天山造山带的变形和隆升是其南北侧稳定地质块体的构造挤压与壳—幔复杂耦合作用的共同结果. 相似文献
13.
收集华北克拉通地区188个宽频带流动台站观测资料进行处理.通过背景噪声面波数据和接收函数双重资料约束联合反演,得到了研究区沉积层厚度、地壳厚度及地壳S波速度结构.结果显示:(1)沉积盖层厚度与地质构造相对应,盆地区与隆起区分界明显.(2)研究区地壳厚度变化范围约29~46 km,自西向东逐渐变薄.(3)中、上地壳华北盆地S波速度偏高,可能与新生代以来多次沉降所造成的相对高的岩石强度有关;(4)下地壳S波速度显示研究区主要存在三个低速区,分别是唐山—天津周边、张北及太行山造山带地区;华北盆地存在显著高速异常,推测可能是由于华北盆地经历下地壳拆沉后,大规模的伸展作用相伴随的幔源基性铁镁质岩浆底侵至下地壳结晶所造成的.(5)多个发生过强震的区域表现出沉积层下方存在较大范围的(约10 km)高速体,并且高速体又被其下低S波速度包裹,壳内岩石强度的差异为应力积累及地震发生提供条件. 相似文献
14.
The Pamir plateau, located north of the western syntaxis of the India-Eurasia collision system, is regarded as one of the most possible places of the ongoing continental deep subduction. Based on a N-S trending linear seismic array across the Pamir plateau, we use the methods of the harmonic analysis of receiver functions and the cubic spline interpolation of surface wave dispersions to coordinate their resolutions, and perform a joint inversion of these datasets to construct a 2-D S-wave velocity model of the crust and uppermost mantle there. A spatial configuration among the intermediate-depth seismicity, Moho topography, and low-velocity anomalies within the crust and upper mantle is revealed, which provides new seismological constraints on the geodynamic processes of the continental subduction. These results not only further confirm the deep subduction of the Asian continental lower crust beneath the Pamir plateau, but also indicate the importance of the metamorphic dehydration of the subducting continental crustal material in the genesis of the intermediate-depth seismicity and the crustal deformation. 相似文献
15.
利用秦岭─大别造山带及其毗邻地区３１０个地震台站记录到的区域地震２３６００条Ｐ波到时数据，重建了该区地壳和上地幔三维速度图像。结果表明：１．秦岭─大别造山带及其毗邻地区地壳和上地幔存在显著的横向不均匀性，直至１１０ｋｍ深度处依然明显。２．地壳上部的速度图像与地表地质构造密切相关：造山带隆起区显著高速；盆地及坳陷区明显低速。由速度鲜明对比勾勒出的秦岭─大别造山带南界基本上位于扬子北缘主边断裂带上。３．中地壳的速度图像表明，造山带内部的一些低速区对应于一些大型推覆构造。４．４０＋０ｋｍ深度处的速度图像反映了该区莫霍界面深度的起伏。大致以１０７°Ｅ为界，以东地区地壳厚度小于４０ｋｍ，以西地区大于４０ｋｍ，且呈现出往西地壳逐渐加厚的趋势。５．位于滦川、商县、丹凤的北秦岭构造带，上地幔顶部出现低速异常，异常速度值约为７．３９—７．５５ｋｍ／ｓ。结合地球物理测深的结果，可能是由下地壳、上地幔顶部的热过程所致。 相似文献
16.
利用秦岭─大别造山带及其毗邻地区３１０个地震台站记录到的区域地震２３６００条Ｐ波到时数据，重建了该区地壳和上地幔三维速度图像。结果表明：１．秦岭─大别造山带及其毗邻地区地壳和上地幔存在显著的横向不均匀性，直至１１０ｋｍ深度处依然明显。２．地壳上部的速度图像与地表地质构造密切相关：造山带隆起区显著高速；盆地及坳陷区明显低速。由速度鲜明对比勾勒出的秦岭─大别造山带南界基本上位于扬子北缘主边断裂带上。３．中地壳的速度图像表明，造山带内部的一些低速区对应于一些大型推覆构造。４．４０＋０ｋｍ深度处的速度图像反映了该区莫霍界面深度的起伏。大致以１０７°Ｅ为界，以东地区地壳厚度小于４０ｋｍ，以西地区大于４０ｋｍ，且呈现出往西地壳逐渐加厚的趋势。５．位于滦川、商县、丹凤的北秦岭构造带，上地幔顶部出现低速异常，异常速度值约为７．３９-７．５５ｋｍ／ｓ。结合地球物理测深的结果，可能是由下地壳、上地幔顶部的热过程所致。 相似文献
17.
A broadband seismic array of 7 stations was set up in the western Dabie Mountains (31°20′-31°50′N, 114°30′-115°E). Teleseismic events from May 2001 to November 2001 were collected and analyzed by radial receiver function to determine the S-wave velocity structure of the crust and uppermost mantle. The crustal thickness is 32-38 km beneath the array. The crust-mantle boundary appears as a gently north-dipping velocity discontinuity, but turns to be a velocity gradient beneath a station near the Qiliping shea... 相似文献
18.
天山造山带是新生代以来复活隆升的陆内造山带,强烈的地震活动性使得理解和认识天山造山带深部结构及盆山耦合关系尤为重要。文章中使用天山造山带及邻区(40°～49°N,79°～93°E)85个台站2017—2019年的背景噪声资料,结合背景噪声互相关方法获得了6～52 s瑞利波相速度频散曲线,利用基于射线追踪的面波直接反演法对天山中段地壳三维S波速度结构及盆山耦合关系进行研究。结果显示：地壳浅层S波速度分布与构造单元中沉积层厚度相关,塔里木盆地北缘、准噶尔盆地南缘表现为低速,天山造山带表现为高速;到了中下地壳,天山造山带下方存在被高速异常包裹的低速体;莫霍面附近,天山造山带表现出相对低速;准噶尔盆地南缘和天山造山带的地壳厚度分别在45～50 km、50～62 km之间,沿南北向,天山造山带莫霍面呈现较为宽缓的形态;在82°～86.5°E之间,塔里木盆地和准噶尔盆地向天山下方双向俯冲,86.5°～88°E之间,准噶尔盆地向天山南向俯冲,由西向东,不同盆山耦合关系揭示了新生代以来天山中段不同区域构造运动差异,为进一步探讨造山动力过程提供参考。 相似文献
19.
通过处理ChinArray计划二期和三期台阵中823个台站的远震波形数据,共获得174 562个高质量的P波接收函数,采用接收函数共转换点（CCP）叠加方法开展华北克拉通中西部及其邻区的地幔转换带结构研究,获得了研究区地幔转换带的厚度分布。结果表明:研究区内地幔转换带厚度变化幅值在235—280 km范围内,具有分区特征;阿尔金断裂带东部和汉诺坝火山以北厚的转换带异常可能与冷的岩石圈拆沉有关;河套盆地和阴山造山带附近分布着相对薄的地幔转换带,这可能暗示了该地区存在热的地幔物质上涌或岩浆活动;渤海湾盆地下方厚的地幔转换带异常可能是冷的太平洋板片西向俯冲并滞留于地幔转换带所致。 相似文献
20.
To determine the crustal structure in central Tibet, we used teleseismic waveform data recorded by 18 stations in the INDEPTH-Ⅲ seismic array across the central Tibet from the central Lhasa terrane to the central Qiangtang terrane. The S-wave velocity structures beneath stations are determined by inverting the stacked radial receiver function using the GA method. The first order features in the receiver function are modeled. Our results show that the Moho in Qiangtang is about 8 km shallower than that in Lhasa terrane along the INDEPTH-Ⅲ profile. It maybe suggests the northward subduction of the Lhasa mantle lid beneath the Qiangtang terrane is affected by the India-Asia collision. We conclude that there exist low velocity zone in the middle crust across the northern Lhasa and Qiangtang terrane, which can be related to the high temperature upper mantle beneath that. 相似文献