渭河盆地东部地区的活断层

本文根据近年来的调查结果,讨论了渭河盆地东部地区六条主要断裂的活动情况。指出这些断裂现今活动以倾向滑落为主,同时兼有一定分量的左旋走滑运动     

东昆仑活动断裂带东段古地震活动特征

东昆仑活动断裂托索湖——玛曲以东肯定那一带， 可据阿尼玛卿玛积峰为界再分为花石峡段和玛沁段两个在几何上不连续的段落. 两段在表征断层全新世活动特征的古地震事件方面有明显差异， 花石峡段的地震活动性明显高于玛沁段的地震活动性. 古地震研究表明， 花石峡段上3次强震活动相邻两次地震发生的时间间隔分别约为500 a和640 a， 玛沁段上最近两次古地震事件间大致有1 000 a左右的时间间隔. 根据断层平均滑动速率计算的花石峡段7.5级地震的平均复发间隔为411~608 a， 相对应的同震平均水平位错约为（5.75plusmn;0.57）m. 虽然玛沁段的地震活动性较弱， 但由于该段上最近一次地震事件离现在较为久远， 已经积累的应变能应该使我们对其未来地震危险性的分析有足够重视.      

Re-discussion on the Jiaochang Arcuate Structure, Sichuan Province, and the Seismogenic Structure for Diexi Earthquake in 19331

The Jiaocbang arcuate structure is one of the numerous arcuate structural belts in Sichuan. The present paper gives a further argument about the characteristics of that arcuate structure and the new activity of the Songpinggou fault and affirms that the Songpinggou fault is an active fault in the Holocene epoch. The Diexi M7.5 earthquake took place in 1933 on the west wing of that arcuate structure, near the apex of the arc. Many authors have given quite different opinions about the genetic structure of that earthquake. The authors have made on-the-spot investigations time and again over recent years. Besides this, the authors have also further studied the shape of intensity contour lines, the distribution characteristics of ground surface seismic hazards, the left-lateral dislocation of buildings along the Songpinggou fault, the NWtrending ground fissures that developed on the ground surface after earthquake, and so on. On this basis, it is still considered that the seismogenic fault of the 1933 Diexi M7.5 earthquake was the Songpinggou fault on the west wing of the Jiaochang arcuate structure.     

发震时深浅构造相互作用导致横向断层致锁的有限元分析

本文利用三维有限元方法，研究和计算了大震发生前、发生时，发生后震源断层面与深部同面立接断层之间的相互作用以及发震后促使深部断层发生错动从而对震源区近场横向活动断层致锁的结果，得到以下结果：（１）临近大震前震源断层面端部调整单元下方的深部断层有较高的剪应力水平，造成震时对震源断层面发生底辟作用的条件，即调整单元区对应的深部断层单元首次满足破裂条件并发生破裂。（２）震源端部的调整单元和具有蠕能力的横向     

2008年10月5日新疆乌恰6.8级地震现场考察

2008年10月5日在新疆乌恰地区发生的M_S6.8地震,微观震中位于乌恰县境内,距边境18km,宏观震中位于吉尔吉斯斯坦共和国努拉村,距新疆乌恰县伊尔克什坦口岸西南约7km处,极震区烈度达到8度(境外).我国境内Ⅶ度和Ⅵ度区面积分别为7354km~2和1031km~2.这次地震的发生与南北向的卡兹特阿尔特弧形断裂带的活动有关.震区建筑物遭到一定程度的破坏,地质灾害现象较明显.     

Seismic evidence of small-scale lacustrine drifts in Lake Baikal (Russia)

High resolution, single-channel seismic sparker profiles across the Akademichesky Ridge, an intra-basin structural high in Lake Baikal (Russia), reveal the presence of small sediment mounds and intervening moats in the upper part of the sedimentary cover. Such features interrupt the generally uniform and even acoustic facies and are not consistent with the hemipelagic sedimentation, which is expected on such an isolated high and which would produce a uniform sediment drape over bottom irregularities. The influence of turbidity currents is excluded since the ridge is an isolated high elevated more than 600-1000 m above adjacent basins. The mounded seismic facies, including migrating sediment waves and non-depositional/erosional incisions, strongly suggest that sediment accumulation was controlled by bottom-current activity. We interpret the mounds as small-scale (< few tens of km² in area) lacustrine drifts. Four basic types of geometry are identified: 1) slope-plastered patch sheets; 2) patch drifts; 3) confined drifts; 4) fault-controlled drifts. The general asymmetry in the sedimentary cover of the ridge, showing thicker deposits on the NW flank, and the common location of patch drifts on the northeast side of small basement knolls indicate that deposition took preferentially place at the lee sides of obstacles in a current flowing northward or sub-parallel to the main contours. Deep-water circulation in the ridge area is not known in detail, but there are indications that relatively cold saline water masses are presently flowing out of the Central Basin and plunging into the deep parts of the North Basin across the ridge, a process that appears to be driven mainly by small differences in salinity. We infer that the process responsible for the observed bottom-current-controlled sedimentary features has to be sought in these large-scale water-mass movements and their past equivalents. The age of the onset of the bottom-current-controlled sedimentation, based on an average sedimentation rate of 4.0 cm/ky, is roughly estimated to be as least as old as 3.5 Ma, which is generally regarded as the age of the onset of the last major tectonic pulse of rift basin development in the Baikal region.     

南黄海北部坳陷及周缘地区白垩纪以来构造研究进展

南黄海北部坳陷是在印支期前陆盆地基底上发育的白垩纪—新生代大型伸展盆地。笔者系统总结了国内外学者南黄海北部坳陷周缘大地构造学研究、盆地内构造变形—陆相层序充填研究近年来的研究成果,对比了中韩两国学者对于北部坳陷的陆相层序划分方案的异同点,列举了目前研究的薄弱点,提出了一些亟待解决的问题。此研究对于东亚陆缘断陷盆地群地球动力学机制分析、扬子—华北碰撞造山带垮塌研究以及南黄海油气勘探突破均有重要的科学和经济意义。     

中国南部海域主要断裂类型、分布及地质特征

中国南部海区及邻域1∶1 000 000地质地球物理系列图已编制完成并即将出版,区域构造图是其中的主要图件之一,据此成果,讨论了中国南部海域主要断裂类型、分布及地质特征。主要断裂类型有俯冲带、碰撞缝合带、转换断层、扩张脊型断裂、大型走滑断裂及深大断裂等。根据断裂规模及控制的地质构造单元性质划分出了一级断裂和二级断裂。一级断裂主要是指俯冲带、碰撞缝合带或者控制构造域、地块之间界线的深大断裂;二级断裂主要是控制隆褶带、海盆区以及大型沉积盆地的深大断裂。这些断裂大多具有形成时期早、规模大、断层延伸远、断距大甚至多次活动的特征。     

长平井田三维勘探精细构造解释

山西沁水盆地是一个构造残留型的富煤盆地,是我国最大的煤层气田。长平井田位于沁水盆地南部,是煤层气成藏的有利区域,且该区域煤层气的形成及分布以构造成因为主要因素。在三维地震勘探偏移数据体的基础上,对研究区域的速度进行标定,对层位、断层、陷落柱以及褶曲进行精细解释,获得该区域精细构造特征描述。与原二维构造特征对比发现：三维地震构造特征中的煤系地层走向和埋深与原二维构造特征基本一致;三维地震构造特征反映出沿走向上发育的多个短轴状展布小幅褶曲,新增断层19条和新增陷落柱24个;查明原二维构造特征与三维构造特征中不一致的一条断层和陷落柱的位置,获得对地下煤层精确的成像解释。通过该区测井资料验证,三维地震构造特征符合地下实际情况,验证了三维精细构造解释的准确性。     

安达曼海东部凹陷渐新世以来断裂–构造演化特征及其成因探讨

本文研究内容为印度洋东北部边缘海安达曼海的构造演化。利用安达曼海域东部大范围二维地震数据资料及钻井数据,结合区域地质概况以及前人研究成果,选取8条具有代表性的断层并将其划分为一级和二级断裂,运用生长指数法和古落差法对断层进行定量分析,再通过计算安达曼海东部凹陷4条主测线的构造沉降量,探讨构造演化过程。结果表明：选取的生长断层中3条属于一级断裂,跨度大,几乎切穿整个地层,属于控制安达曼海域地区沉降的大断裂;另外5条属于二级断裂,控制构造带的展布情况,属于构造带的分界线。渐新世时期,印度–澳大利亚板块与欧亚板块之间处于软碰撞阶段,断层发育缓慢,上下盘落差较小,生长指数与构造沉降量也处于低值;中新世时期,板块之间的耦合效应不断增强,断层发育速度加快,此时上下盘厚度最大,是形成多处断裂带以及多种断裂样式的关键时期,各地层生长指数和构造沉降量也达到峰值。上新世至今,安达曼海沟–弧–盆体系逐渐稳定,断层活动减弱,断裂上下盘厚度差基本一致,生长指数差异较小,构造沉降量基本稳定在 1 km 左右。