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1.
川滇地区地壳上地幔三维速度结构研究 总被引：95，自引：22，他引：95
根据云南和四川地震台网174个台站记录的4625个区域地震初至Ｐ波和Ｓ波走时资料，并结合其它深部地球物理资料，确定了川滇地区地壳上地幔三维速度结构．在上地壳速度异常分布中，四川盆地为正异常，川西高原为负异常，龙门山断裂带为正、负异常的边界．龙门山断裂、鲜水河断裂以及红河断裂等，在下地壳和上地幔的速度异常中仍显示出构造分界特征，说明它们可能穿透了莫霍界面．腾冲火山区和攀西构造带在50km深度上呈现负速度异常，与上地幔温度和物质组成的差异相联系．川滇地区地壳结构的总体特征是:地壳和上地幔的低平均速度，地壳厚度变化剧烈，地壳和（或）上地幔存在高导层、高热流值．这些同印度板块与欧亚板块碰撞的构造背景有关．川滇菱形块体在地壳内总体上为正常或正异常速度，而其边界的深大走滑断裂存在负速度异常，它有助于地壳块体沿断裂的侧向挤出．在主要的地震带上，中下地壳的负速度异常与地震活动性相关．多数强烈地震发生在具有正速度异常或正常速度分布的上中地壳深度上，而其下方则通常是负速度异常带． 相似文献
2.
Based on the first arrival P and S data of 4 625 regional earthquakes recorded at 174 stations dispersed in the Yunnan and
Sichuan Provinces, the 3-D velocity structure of crust and upper mantle in the region is determined, incorporating with previous
deep geophysical data. In the upper crust, a positive anomaly velocity zone exists in the Sichuan basin, whereas a negative
anomaly velocity zone exists in the western Sichuan plateau. The boundary between the positive and negative anomaly zones
is the Longmenshan fault zone. The images of lower crust and upper mantle in the Longmenshan fault, Xianshuihe fault, Honghe
fault and others show the characteristic of tectonic boundary, indicating that the faults likely penetrate the Moho discontinuity.
The negative velocity anomalies at the depth of 50 km in the Tengchong volcanic area and the Panxi tectonic zone appear to
be associated with the temperature and composition variations in the upper mantle. The overall features of the crustal and
the upper mantle structures in the Sichuan-Yunnan region are the lower average velocity in both crust and uppermost mantle,
the large crustal thickness variations, and the existence of high conductivity layer in the crust or/and upper mantle, and
higher geothermal value. All these features are closely related to the collision between the India and the Asia plates. The
crustal velocity in the Sichuan-Yunnan rhombic block generally shows normal value or positive anomaly, while the negative
anomaly exists in the area along the large strike-slip faults as the block boundary. It is conducive to the crustal block
side-pressing out along the faults. In the major seismic zones, the seismicity is relative to the negative anomaly velocity.
Most strong earthquakes occurred in the upper-mid crust with positive anomaly or normal velocity, where the negative anomaly
zone generally exists below.
Foundation item: National Scientific and Technological Development Program (95-973-02-02), the Climb Program (95-S-05-01) of National Scientific
and Technological Ministry of China, and the State Natural Sciences Foundation of China (49874021).
Contribution No. 02FE2004, Institute of Geophysics, China Seismological Bureau. 相似文献
3.
本文以构造应力场观测结果、 岩石圈流变特性为约束, 采用摩擦接触单元反映断裂带空间分段特征, 以最接近真实地下环境的非线性黏弹性材料为模型的本构关系, 建立包括安宁河—则木河—小江断裂带的三维有限元模型, 模拟在速度边界条件和重力势能等动力因素共同作用下的断裂带应力分布特性. 研究结果表明, 模拟得到的断裂带现今构造应力场与地震活动有明显的对应关系, 应力比较集中的区域, 如石棉、 西昌、 巧家、 东川附近, 极有可能是未来的地震危险区域. 相似文献
4.
IntroductionThestudyingareaislocatedwithin32(~40(N,100(~108(E,consistingofseveralgeotectonicsubdivisions.Thisarea,locatedonthenortheasternmarginoftheuprisingregionoftheQinghai-Tibetanplateau,isaveryactiveregionofnewtectonicmovement.Moreover,afewoflargedeepfaultsdistributethere,mostofwhicharenotonlyboundaryfaultsofimportantgeotectonicdivisions,butalsoactivefaultscontrollingcontemporarystrongseismicactivities.AsshowninFigure1,manystrongearthquakeshaveoccurredinthisresearchareasuchassouthernTi… 相似文献
5.
通过与更早地震资料的对比, 研究了鲜水河断裂带, 川滇地壳块体东带、 西带, 松潘、 龙门山断裂带以及整个川滇地区较长时间尺度的地震活动盛衰交替性。 结果表明, 川滇东带北段(鲜水河断裂带)、 松潘、 龙门山地震带及川滇西带中段和南段(主要是红河断裂带)的地震活动具有明显的几十到百年尺度的盛衰交替性。 而川滇东带中南段(安宁河-则木河-小江断裂带)与川滇西带北段(金沙江断裂带)在上述地震带的平静期里, 中强以上地震频次明显减少, 但有个别7级以上强震发生。 这样, 整个川滇地区地震活动的盛衰交替性呈现一种比较复杂的阶段性特征: 伴随频繁中强震的强震活跃期与突发强震活动期交替出现。 值得注意的是, 川滇地区从19世纪末开始的伴随频繁中强震的强震活跃期已超过百年, 目前出现长期平静, 应注意进入突发强震活动期的可能性。 根据川滇地区上一个突发强震活动期突发强震的空间分布, 推测未来的突发强震可能发生在南北向断裂带, 或其他方向断裂带与南北向断裂带的交汇部。 文中还对上述统计现象的机理作了简要讨论。 相似文献
6.
研究龙门山及邻区地壳密度结构对于认识该地区地震活动性具有重要意义.根据龙门山及邻区( 100°～105°E,28°～33°N)的布格重力异常资料,选取了跨越龙门山断裂带的6条重力测线,在深地震测深资料约束下,使用Geosoft软件分别反演出了龙门山地区地下的沉积层、康拉德界面和莫霍面的深度分布.研究结果表明:龙门山断裂带两侧的地壳结构明显不同,西面高原地区沉积层较薄,大部分为基岩出露;而东边盆地沉积层明显较厚,多在6km以上.莫霍面和康拉德面在两侧均相对平缓,康拉德面从东部的大约24km增加到青藏高原山区的35km左右;莫霍面深度从东部盆地的大约42km增加到西部青藏高原的67km左右.龙门山断裂带整体表现为一条近SN向的陡变重力梯度带,并在其地壳内各界面均发生错断,莫霍面和康拉德面错断距离分别达6 ～ 7km和3～ 5km.该区地壳的这种陡变和不均匀性是导致地震活动性强烈的主要原因之一. 相似文献
7.
A study on 3-D velocity structure of crust and upper mantle in Sichuan -Yunnan region, China 总被引：1，自引：0，他引：1
Many evidences indicate that the collision of two plates deformed strongly the crust of the SYR, and the deformation has been continued up to the present. In addition, the SYR is in the south segment of the South-North Seismic Zone of China, which is one of the regions in the Chinese mainland, where the seismic activity is very high, and the strong earthquakes frequently occurred. Since the 1970s, a series of large earthquakes with magnitude M>7.0 occurred in SYR, such as the 1970 Tongha… 相似文献
8.
ZHANG Zhongjie BAI Zhiming WANG Chunyong TENG Jiwen Lü Qingtian LI Jiliang LIU Yifeng & LIU Zhenkuan . Institute of Geology Geophysics Chinese Academy of Sciences Beijing China . Institute of Geophysics China Seismological Bureau Beijing China . Institute of Deposition Resource Chinese Academy of Geosciences Beijing China . School of Exploration Information China University of Geosciences Beijing China 《中国科学D辑(英文版)》2005,48(9):1329-1336
The Sanjiang area in southwest China is considered as a tectonic intersection belt between the Tethys-Alps and the western Pacific, and has endured three-phase evolution processes: Proto-Tethys,Paleo-Tethys and Meso-Tethys[1―4]. In this area, its tectonics and struc- ture are extremely complicated, and intensively extru-sive deformation and faults are widely developed[1―3]. For that, the area is considered as the ideal na- ture-laboratory to study the evolution of Paleo-Tethys and also … 相似文献
9.
本文利用川滇地区宽频地震接收函数结果和WGM2012全球布格重力场模型数据,采用正则化参数和接收函数结果交叉验证得到最优莫霍面参考深度和上下界面密度差,使用基于球坐标系下的快速非线性重力反演方法建立川滇地区莫霍面深度模型.研究结果显示,川滇地区整体莫霍面深度介于30～69km,青藏高原内部地区莫霍面深度大于50km;四川盆地莫霍面深度在36～38km;攀枝花地区莫霍面出现明显的隆起和下凹,变化范围在42～48km;川滇菱形地块莫霍面深度在40～50km;滇西和滇南地块莫霍面深度由南向北逐渐变深,变化范围在38～44km.本文反演莫霍面深度与接收函数结果平均误差为0.18km,与该区域天然地震层析成像、人工地震探测以及重力数据反演结果基本一致,但细节更加丰富,进一步确认了莫霍面在攀西裂谷地区存在隆起,小江断裂带下方存在下凹的特征.该结果可作为精细化川滇地区地壳密度界面模型,为研究该地区岩石圈结构和地质构造演化提供参考. 相似文献
10.
对川滇地区主要活动断裂地震活动性的分析表明 ,该区主要活动断裂间存在地震活动的相关性 :1)强震活跃期沿着鲜水河断裂、小江断裂、红河断裂、龙陵 -澜沧断裂及NE向的龙门山 -瑞丽断裂依次迁移 ;2 )鲜水河断裂与龙陵 -澜沧断裂不仅在强震活动上 ,而且在b值变化上存在较强的相关性 ,是平行断裂在区域应力场作用下相互作用的结果 ;3)龙门山 -瑞丽断裂与上述川滇地区其它近NW向断裂间存在地震交替活动的现象 ;4 )龙门山 -瑞丽断裂的地震具有分段活动的特征 ,是断块差异活动的体现。有限元分析显示 ,上述断层相互作用现象是块体非均匀运动过程中应力场调整的反映 ,是块体运动的结果。研究表明川滇地区主要断层地震活动间存在 3种相互作用的现象 ,即块体边界迁移型、旋向相反平行断层交替型和交叉断层交替型 相似文献
11.
Relationship between the regional tectonic activity and crustal structure in the eastern Tibetan plateau discovered by gravity anomaly 
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下载免费PDF全文 The eastern Tibetan plateau has been getting more and more attention because it combines active faults, uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus, a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative (THD) had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks, including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the Songpan-Garze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion, which is coincident with the flowing direction indicated from the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault. 相似文献
12.
结合新一轮编图工作的开展,中国东部海区重、磁平面图件在拼入新资料同时,也包含了邻区朝鲜半岛,台湾岛,日本海,菲律宾海等地区的资料.本文在此基础上综合分析研究区重、磁异常特征,利用重、磁资料反演莫霍面、居里面,进而求取了热岩石层底界面,对重、磁数据进行了突出断裂带信息的处理,确定了13条重要断裂带的展布,将研究区划分为8个块体和4个结合带,它们具有"东西成带、南北分块"的特征,是"2条锋线"作用的产物.研究表明,江—绍断裂带向东延伸进入海区,虽然受东海陆架西缘断裂带的切割,但仍继续往东延伸,可能延至朝鲜半岛南端与济州岛南缘断裂带相接;在朝鲜半岛西缘地球物理场存在NNW—NW的明显界线,可解释为断裂带,称之黄海东缘断裂带,中国大陆东部的五莲—青岛断裂带与黄海东缘断裂带和济州岛南缘断裂带共同构成中朝和扬子块体的边界. 相似文献
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通过建立较精细的川滇地区三维有限元模型,数值模拟了川滇地区主要活动断裂的强震活动对于其他活动断裂潜在强震孕育进程的库仑破裂应力加卸载效应.模拟结果显示在川滇地区主要活动断裂带的几何学展布形态和运动学性质的构造背景之上,川滇地区强震活动相互影响的主要特征是活动断裂面库仑破裂应力变化大多处于增大状态.其中,金沙江断裂带、小江断裂带、楚雄—建水断裂带、鲜水河断裂带和安宁河断裂带上的强震所产生的加载作用比较强,而丽江—小金河断裂带和腾冲—澜沧断裂带则较弱.1981~2000年川滇地区M≥6.5地震序列的模拟结果显示,后续地震全部位于已发生地震所引起的库仑破裂应力增大区之内.数值模拟结果显示,在川滇地区,一个强震发生之后,发震断层本身强烈卸载的同时,库仑破裂应力的加载效应在其他主要活动断裂带潜在强震孕育进程中占据了主导地位,强震活动之间相互作用的主要效应是应力加载,已发生的强震加速了下一个强震的孕育进程,进而导致一系列地震的发生,直至整个区域所积累的应变能处于较低水平之后,区域地震活动进入一个新的平静期. 相似文献
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通过对鲁西隆起区重磁资料的分析和反演计算，研究了沂沭断裂带、齐河—广饶断裂带、聊城—兰考断裂带、丰沛断裂带以及地块内部断裂的重磁异常、莫霍面和居里面深度特征，并讨论了鲁西隆起的地质构造特征和构造活动性.结果显示:鲁西隆起基底广泛出露，沉积层主要分布在由断裂下降盘控制的凹陷内，区内断裂深度达20 km以上，其中蒙山断裂深入至上地幔，控制了蒙山金伯利岩型金刚石矿的产出；鲁西隆起区莫霍面深度为30—35 km，整体呈向西开口的箕形，地块中部地壳厚度较厚，除西侧地壳呈阶梯状增厚外隆起地块四周地壳逐渐减薄；居里面深度介于20—33 km之间，中部地区较深，为整体稳定的地块，断裂带分布位置对应于居里面梯度带；地震活动主要集中于断裂带与莫霍面梯度带交会区以及断裂带上的居里面突变区. 相似文献
15.
Introduction ZHANG and ZHONG (1977), ZHANG, et al (1978) and ZHANG (1984) pointed out that Chinese mainland is divided into two parts by the NS-trending tectonic belt, i.e., the eastern area and the western area, and each area is divided into tectonic blocks by faults. In the eastern area, the faults are trending NNE and NNW, mainly NNE, and the long axis strike of blocks is nearly trending NS. In the western area, faults are trending NEE and NWW, mainly NWW, long axis strike … 相似文献
16.
川滇地区是我国地震危险性较高的地区之一.本文基于对特大强震的风险性考虑,使用全球地震模型OpenQuake软件,建立了川滇地区地震危险性预测新模型.首先根据构造特征划分多个震源分区,并整理出这些震源分区内断层活动特征与滑动速率;基于震源分区和断层模型,使用GPS应变率转换成的锥形古登堡-里克特关系作为整个区域的地震积累率,并允许超过历史最大震级的特大地震的出现,结合活动断层滑动速率所积累的地震发生率,给出震源分区内断层地震源和背景地震源的地震发生率的比率分配关系;在活动断层分段上,保留了大型断裂或其主要部分,没有根据小的阶区来对断层进行详细分段,以便分配特大地震发生率;并使用地震率平滑方法分配背景地震发生率.最后在OpenQuake中加入地震动预测方程,计算出了川滇地区的PGA分布图,为区域地震危险性提供科学依据. 相似文献
17.
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
18.
根据福建及台湾海峡南部海陆联测试验记录到的Pg和Pm震相走时数据，利用速度与界面联合成像方法构建地壳三维P波速度结构，揭示了该区地壳深部构造特征.结果表明：福建和台湾海峡海陆过渡带以及海峡南部地壳速度结构存在明显的不均匀性，滨海断裂两侧速度结构复杂，随深度呈现明显的分段特征，其上地壳海陆过渡带呈高速特性，台湾海峡呈低速特性；下地壳海陆过渡带呈低速特性，台湾海峡呈高速特性；研究区莫霍面的深度约为28~33 km，存在较明显差异，闽粤交接部位存在明显的地壳厚度减薄，莫霍面深度接近28 km，这与正常型华南活动地块与减薄型南海活动地块交汇致使地壳厚度减薄有关，体现了活动块体边界构造特征.历史大震主要发生在高低速异常过渡带且有深大断裂穿过的区域，现今中小震主要分布于闽粤海陆过渡带，这一特征可能与此地广泛发育的断层和华南与南海活动地块相互作用有关. 相似文献
19.
TRANSVERSE STRUCTURES FEATURES OF DIFFERENT DEPTHS DERIVED FROM BOUGUER GRAVITY ANOMALIES IN THE SOUTHERN SEGMENT OF TAN-LU FAULT ZONE 下载免费PDF全文
下载免费PDF全文 WANG Xin ZHANG Jing-fa JIANG Wen-liang JIANG Hong-bo TIAN Tian GAO Min FU Ping-jie 《地震地质》2016,38(2):370-385
To research the faults distribution and deep structures in the southern segment of Tan-Lu fault zone(TLFZ) and its adjacent area, this paper collects the Bouguer gravity data and makes separation by the multi-scale wavelet analysis method to analyze the crustal transverse structure of different depths. Meanwhile Moho interface is inversed by Parker variable density model. Research indicates that the southern segment of TLFZ behaves as a NNE-directed large-scale regional field gravity gradient zone, which separates the west North China-Dabie orogen block and the east Yangtze block, cutting the whole crust and lithosphere mantle. There are quite differences of density structures and tectonic features between both sides of this gradient belt. The sedimentary and upper crustal density structure is complex. The two east branches of TLFZ behave as linear gravity anomalous belt throughout the region, whereas the two west branches of TLFZ continue to extend after truncating the EW-trending gravity anomaly body. The lower crustal density structure is relatively simple. TLFZ behaves as a broad and gentle low abnormal belt, which reflects the Cretaceous-Paleogene extension environment caused graben structure. The two west branches of TLFZ, running through Hefei city, extend southward along the west margin of Feidong depression and pinch out in Shucheng area due to the high density trap occlusions in the south of Shucheng. The Feizhong Fault, Liu'an-Hefei Fault, and Feixi-Hanbaidu Fault intersect the two west branch faults of TLFZ without extending to the east. Recent epicenters are mainly located in conversion zones between the high-density and the low-density anomaly, especially in TLFZ and the junction of the faults, where earthquakes frequently occurred in the upper and middle crust. As strong earthquakes rarely occur in the southern segment of TLFZ, considering its deep feature of abrupt change of the Moho and intersections with many EW-trending faults, the hazard of strong earthquake cannot be ignored. 相似文献
20.
Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau 总被引：2，自引：0，他引：2
The receiver functions of body waves of distant earthquakes obtained for the regions beneath 41 digital stations (Lhasa and
GANZ in Tibet, Mandalay and Rangoon in Myanmar, SHIO in India, CHTO in Thailand, and station network in Sichuan and Yunnan)
were used to invert for S-wave structure in the crust and upper mantle in Sichuan, Yunnan, and their surrounding areas. Meanwhile
the distribution characteristics of the Poisson’s ration and the crustal thickness in Sichuan and Yunnan areas were also obtained.
Results indicate that the depth of Moho beneath the eastern side of Qinghai-Tibetan plateau varies strikingly. It is obvious
that the greatest changes in crustal thickness occur in a north-south direction. The crustal thickness decreases from north
to south, being as thick as 70 km in eastern Tibet, the northern portion of our area of interest, and less than 30 km in Chaing
Mai and Rangoon, the southern portion of our area. There are, however, exceptions regarding the trend. The thickness exhibits
an east-west variation trend in the area from Ma’erkong-Kongding in Sichuan to Lijiang in Yunnan. In general the Jinpingshan-Longmenshan
fault and Anninghe fault can be taken as the boundaries of this exception area. The thickness in Kongding in the west is 68 km,
while it is only 39 km in Yongchuan in the east. Moreover the Poisson’s ratio values in the blocks of central Sichuan and
Sichuan-Yunnan Diamond are high, and a low velocity layer in the crust of this area can be obviously detected. The distribution
characteristics of the high Poisson’s ratio and the low velocity of the crust in this block correspond to the tectonic structure,
being in contrast with the surrounding areas. Combining with the distribution features of the modern tectonic stress field,
it is deduced that the Sichuan-Yunnan area is probably the channel through which the materials of the lithosphere flow eastward. 相似文献