青藏高原东北缘盆山结合部位深反射资料处理方法与初步地质认识   总被引：3，自引：0，他引：3  

王海燕高 锐马永生朱 铉李秋生李鹏武匡朝阳  卢占武 《中国地质》2007,34(1):142-148

盆山结合带地质条件复杂、地形起伏大,深地震反射资料具有信噪比低、各种干扰波严重以及速度横向变化大等特点。针对盆山结合部位深反射资料的特点,主要利用ProMAX处理系统对横跨若尔盖盆地和西秦岭造山带结合部位的二维深地震反射资料(简称SP04-2剖面)进行折射静校正、叠前去噪、地表一致性处理、人机交互速度分析、剩余静校正循环迭代处理、地表基准动校正叠加和叠后去噪处理等方法试验研究,形成一套适应盆山结合部位深地震反射资料的处理方法和流程,最终得到SP04-2叠加剖面。该剖面首次揭示出若尔盖盆地—西秦岭造山带盆山结合部位的岩石圈结构,为研究盆山深部接触关系提供了可靠的地震学依据。  相似文献   

宁杭高速公路宜广路立交桥场区岩溶发育特征     

陈希祥  黄永忠 《江苏地质》2007,31(3):218-222

研究场区为"覆盖型"岩溶区。为提供公路选线、桥梁设计施工战略决策依据,为今后类似勘察区积累经验,在补勘资料基础上,对场区岩溶分布、形态、制约因素及其发展趋势作了初步分析,重点提出岩性、构造、地貌及彼此间最佳组合状态是岩溶发育的关键。结论是场区岩溶的发展已处于衰亡期。  相似文献   

The 1980, 1997 and 1998 Azores earthquakes and some seismo-tectonic implications   总被引：2，自引：0，他引：2  

J.F. Borges  M. Bezzeghoud  E. Buforn  C. Pro  A. Fitas 《Tectonophysics》2007,435(1-4):37-54

We have studied the focal mechanisms of the 1980, 1997 and 1998 earthquakes in the Azores region from body-wave inversion of digital GDSN (Global Digital Seismograph Network) and broadband data. For the 1980 and 1998 shocks, we have obtained strike–slip faulting, with the rupture process made up of two sub-events in both shocks, with total scalar seismic moments of 1.9 × 10¹⁹ Nm (M_w = 6.8) and 1.4 × 10¹⁸ Nm (M_w = 6.0), respectively. For the 1997 shock, we have obtained a normal faulting mechanism, with the rupture process made up of three sub-events, with a total scalar seismic moment of 7.7 × 10¹⁷ Nm (M_w = 5.9). A common characteristic of these three earthquakes was the shallow focal depth, less than 10 km, in agreement with the oceanic-type crust. From the directivity function of Rayleigh (LR) waves, we have identified the NW–SE plane as the rupture plane for the 1980 and 1998 earthquakes with the rupture propagating to the SE. Slow rupture velocity, about of 1.5 km/s, has been estimated from directivity function for the 1980 and 1998 earthquakes. From spectral analysis and body-wave inversion, fault dimensions, stress drop and average slip have been estimated. Focal mechanisms of the three earthquakes we have studied, together with focal mechanisms obtained by other authors, have been used in order to obtain a seismotectonic model for the Azores region. We have found different types of behaviour present along the region. It can be divided into two zones: Zone I, from 30°W to 27°W; Zone II, from 27°W to 23°W, with a change in the seismicity and stress direction from Zone I. In Zone I, the total seismic moment tensor obtained corresponded to left-lateral strike–slip faulting with horizontal pressure and tension axes in the E–W and N–S directions, respectively. In Zone II, the total seismic moment tensor corresponded to normal faulting, with a horizontal tension axis trending NE–SW, normal to the Terceira Ridge. The stress pattern for the whole region corresponds to horizontal extension with an average seismic slip rate of 4.4 mm/yr.  相似文献   

斜向走滑构造分形和变形分解——以滇西北金沙江结合带为例     

江元生 《四川地质学报》2002,22(3):129-132

从分形和变形分解的角度讨论了滇西北金沙江结合带斜向走滑构造分形和变形分解的某些特征。  相似文献   

控制网连接点坐标值粗差的可定位性研究     

王金岭  陈永奇 《武汉大学学报(信息科学版)》1993,(4)

在原有测量控制网(称旧网)的基础上建立同级扩大网或低级加密网(称新网)时,新旧网之间的重合点(称连接点)坐标值粗差的检验是平差前的一个重要环节。本文将连接点坐标视为带协方差阵的观测值,采用数据探测法定位其粗差。借助于 Gauss-Markov模型下两个备选假设检验的理论,推导了连接点相关坐标观测值粗差可定位性基本公式,讨论了各类平面网中连接点坐标观测值粗差的可发现性和可区分性。  相似文献   

The Somalia plate and the East African Rift System: present-day kinematics   总被引：2，自引：0，他引：2  

F. Jestin  P. Huchon  J. M. Gaulier 《Geophysical Journal International》1994,116(3):637-654

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Seismotectonics at the Trench-Trench-Trench triple junction off central Honshu     

Tetsuzo Seno  Takashi Takano 《Pure and Applied Geophysics》1989,129(1-2):27-40

We study earthquakes in and near the TTT type triple junction off Boso peninsula, central Honshu, to elucidate the plate interaction in this area. The Pacific, North America (northeast Japan) and Philippine Sea plates meet at the junction of the Japan and Izu-Bonin Trenches, and the Sagami Trough. We determine focal mechanisms using WWSSN data. We also determine accurate focal depths by modeling body-waves. There is no serious trade-off between focal depth and source time function for the events treated in this study.The earthquake mechanisms and their focal depths show two major modes of deformation of the Pacific slab at the junction. One mode is represented by nearly vertical normal faults with strikes perpendicular to the Bonin Trench. This mode of faulting is dominant in regions south of the junction and characteristically the southwest block is downthrown. The other mode is represented by nearly vertical normal faults that strike parallel to the Japan Trench and indicate the northwest block is downthrown. This latter mode is dominant in regions north of the junction. The former mode may represent the accommodation of the slab geometry to the change in dip angle between the northeast Japan and Izu-Bonin arcs; the Izu-Bonin slab has a larger dip than that of the northeast Japan slab. The latter mode shows that normal faults parallel to the trench strike, usually seen in trench axis-outer rise regions, continue to occur further landward of the trench axis in the area just north of the junction. This might be caused by the loading of the Philippine Sea slab which penetrates between northeast Japan and the Pacific slab north of the Sagami Trough.Further north of these normal faults north of the junction, we find earthquakes which represent the relative motion between the Pacific and North American plates. This means that the Philippine Sea slab does not exist there. With the aid of earthquakes which represent the Philippine Sea-Pacific and Philippine Sea-North America motions located northwest of the normal faults, we can depict a possible area where the Philippine Sea slab exists north of the Sagami Trough.  相似文献   

甘孜－理塘结合带甘孜地区混杂岩类型及成因分析   总被引：1，自引：0，他引：1  

江元生 《四川地质学报》1996,(3)

对甘孜－理塘结合带甘孜地区的沉积混杂、火山混杂、构造混杂岩作了系统分析研究。重点论述了甘孜地区三条构造混杂岩带的物质组成、变形特征和形成机制。结合带是由大小不等，形态各异的岩块（片）拼贴、堆叠而成的构造混杂岩带。较合理地解释了结合带内，大洋拉斑玄武岩、洋岛玄武岩、大陆碱性玄武岩共存的地质特征。提出了一种新的构造岩石单位——构造混杂岩。并对甘孜地区蛇绿岩的成因作了探讨。  相似文献   

The cessation of igneous activity and uplift when an actively spreading ridge is subducted beneath an island arc     

Soichi  Osozawa 《Island Arc》1997,6(4):361-371

Abstract Ridge subduction and the resulting formation of a slab window interrupts volcanic arc-type igneous activity and causes uplift of the arc system. These implied diachronous relationships are examined by comparison of the temporal and spatial positions of ancient migrated trench-trench-ridge triple junctions and the distribution of subduction-related igneous and metamorphic rocks in Japan.  相似文献   

塔里木盆地西南缘盆山结合带东段逆冲体系的形成及演化过程   总被引：1，自引：0，他引：1  

徐晓尹  蔡志慧  何碧竹  杨有星  程木伟  何翠 《岩石学报》2016,32(12):3743-3752

塔西南盆山结合带位于青藏高原与塔里木盆地的结合部位,以发育逆冲推覆构造为主要变形特征,是研究青藏高原与塔里木关系的理想对象,也是塔里木油气成藏的重要潜力区。本研究主要通过野外考察、卫星图片解译以及重点地震剖面解释,对塔西南盆山结合带东段和田地区逆冲体系的结构及变形特征进行了分析。并且在前人研究基础上,阐述了塔西南盆山结合带东段逆冲体系的形成时限。我们认为塔西南盆山结合带东段逆冲体系由几个逆冲岩席组成,这些逆冲岩席皆形成在中新世之后,并且形成时间由南到北逐渐变新。我们采用了平衡剖面恢复手段对塔西南盆山结合带东段的变形程度及演化过程进行推理。指出塔西南盆山结合带东段新生代上地壳缩短率为36%~38%,且主要发生在中新世以来。塔西南盆山结合带东段逆冲体系的形成是新生代印度亚洲两大板块碰撞事件远程效应产生的结果。  相似文献