库车坳陷活动构造的基本特征

简要介绍了南天山山前库车坳陷的主要活动逆断裂-背斜带的分布特征、构造样式、最新活动证据等资料。平面上库车坳陷呈一“眼”状,由南北两大背斜带构成。北部靠近南天山为一套向南逆冲的逆断裂-背斜系统,最新活动的逆断裂-背斜带为喀桑托开逆断裂-背斜带;南部靠近塔里木盆地的是一套向北逆冲的逆断裂-背斜系统,最新活动的主要是秋里塔格逆断层-背斜带及其以南的亚肯背斜等新背斜;南北两大背斜系统夹持着拜城盆地。坳陷区北部的喀桑托开断裂与坳陷区南部的秋里塔格断裂带是区内最主要的活动断裂,前者长逾60km,后者长近200km,沿这两条断裂带均发现了清楚的断裂露头和古地震形变带。此外,在秋里塔格背斜带以南发育了更新的、规模较小的背斜,表明库车坳陷区的褶皱作用继续向盆地方向扩展。石油地震剖面资料显示,库车坳陷南北两侧的褶皱作用均受盖层与基底之间的滑脱断层控制,属于山前的薄皮构造。滑脱面的深度可达10km左右。这是库车坳陷主要的发震层     

新疆南天山库车坳陷晚第四纪以来地壳缩短速率的初步研究

库车坳陷是南天山中段新构造运动异常强烈的地区,发育4排近EW向展布的逆断裂-背斜带。通过野外实地考察及前人资料分析,认为该区晚第四纪以来的构造变形主要集中于喀桑托开逆断裂-背斜带、秋里塔格逆断裂-背斜带和最南缘的亚肯逆断裂-背斜带之上,而且不同构造带之间的变形方式存在较大差异。作者利用全站仪(total station)对上述构造带的变形地貌进行了精确测量,并结合年代学分析,得到喀桑托开逆断裂-背斜的地壳缩短速率为1·0~2·0mm/a,秋里塔格逆断裂-背斜带的地壳缩短速率为2·5~3·0mm/a,亚肯盲逆断裂-背斜的地壳缩短速率为1·5~2·0mm/a。晚第四纪以来,库车坳陷SN向总的地壳缩短速率不<5·0~7·0mm/a     

天山南北两侧山前坳陷带中新生代构造特征与地震

形成于中新生代的南天山库车山前坳陷带和北天山乌鲁木齐山前坳陷带表现出类似的几何学、运动学和动力学特征 ,即坳陷内都发育 4排近东西向展布的逆断裂 -背斜带 ;新生代 (特别是第四纪以来 )表现出强烈的由山体向盆地的逆冲活动 ;逆断裂 -背斜带的形成、演化和发展都受控于统一的近南北向构造应力场。然而 ,南北两个山前坳陷在变形强度、地球物理细结构、地球动力学环境等方面存在着明显的不同。对这些不同点进行了讨论 ,认为正是这些不同点的存在 ,使得天山南北两侧山前坳陷内的现今地震活动性显示出不对称性 ,即南天山库车山前坳陷 5级以上地震基本都分布在第 3排 (秋里塔格 )逆断裂 -背斜带上 ,而北天山乌鲁木齐山前坳陷 5级以上地震基本都分布在坳陷南部准噶尔南缘断裂附近及其以南的天山内部     

库车坳陷东部秋里塔格背斜带的活动断层及其形成机制

在详细调查盐水沟以东秋里塔格背斜带地质、地貌特征的基础上,结合地震反射剖面揭示的深部构造形态,讨论了背斜区地表断层的分布特征、活动性及形成机制。盐水沟以东的秋里塔格背斜带包括库车塔吾背斜和东秋里塔格背斜。库车塔吾背斜核部断层是发育于古近系盐膏层中的滑脱断层向地表的延伸,在晚更新世仍持续活动。库车塔吾背斜北翼断层为受局部挤压应力控制而产生的褶皱调节断层,发育于北翼山前活动枢纽内,成组近平行出现,走向上展布不连续;探槽开挖结果表明,该断层全新世有过断错地表的古地震事件。发育于东秋里塔格背斜南翼靠近核部的博斯坦断层为较大规模的低倾角逆冲断层,向下可能与控制表层背斜生长的断坡相连。东秋里塔格背斜南翼断层是发育于断展褶皱陡倾前翼的剪切逆冲断层,亦平行成组出现,断续分布,在哥库洛克一带断层错断了全新世洪积扇。活动褶皱及其褶皱相关断层均为深部断层滑动经过复杂的褶皱变形传播到近地表的表现,是深部断层活动的指示构造。褶皱调节断层仅是褶皱过程中产生的局部变形,与控制褶皱生长的深部断层仅存在间接的关系。此类断层的滑动位移、速率等不代表深部控制背斜生长断层的运动学参数,但这些次级断层部分记录了活动褶皱区的古地震事件。     

库车坳陷西部喀拉玉尔滚断裂的活动时间、形成机制及其构造意义

喀拉玉尔滚断裂是塔里木盆地北缘、库车坳陷西边界的一条NW向右行走滑断裂,同时也是库车坳陷和温宿凸起的分界断裂,对其开展研究对于认识库车坳陷的构造变形具有重要意义,但目前对该断裂的展布特征、活动时间及形成机制仍存在较大争议。文中根据深部地球物理资料、高分辨率遥感卫星影像解译,并结合前人研究成果,对该断裂进行了系统的研究工作。结果表明,喀拉玉尔滚右行走滑断裂向N延伸穿过了阿瓦特背斜,但其S向并未延伸至北喀背斜南部,总体延伸约40km,走滑断距约达4.1～4.3km。喀拉玉尔滚右行走滑断裂形成于上新世初期,其活动可能一直持续至今,但强度已明显减弱。喀拉玉尔滚断裂的形成除了受断裂两侧基底性质差异的控制外,还与膏盐层的厚度差异密切相关。前者影响了断裂两侧地壳水平缩短量的差异,从而导致新生代沉积盖层被撕裂;后者在挤压应力的作用下影响盐上构造层的产生与演化,进而影响断裂的形成。此外,先期盐构造(盐底辟)的存在可能也对断裂的形成起到了重要作用。喀拉玉尔滚右行走滑断裂作为库车坳陷西部的边界断裂,对其两侧甚至整个库车坳陷东、西部地壳缩短量有一定的调节作用。同时,断裂对南天山前陆盆地的地质地貌、油气资源的运...     

塔里木库车坳陷新生代盐构造解析及其变形模拟

塔里木盆地北缘库车坳陷新生代盐构造为油气聚集提供了丰富的圈闭和良好的盖层,是我国重要的油气勘探目标.通过详细的野外地质观测和二维、三维地震反射剖面解析,结合物理模拟实验和离散元数值模拟,发现库车坳陷发育三层结构的挤压冲断型盐构造:盐上层逆冲断层和褶皱、盐岩塑性流变形成的盐丘和盐背斜和盐下层构造.盐岩聚集于拜城凹陷南北两侧,盐下构造发育于拜城凹陷北侧,盐上构造向南传播的更远,盐上层与盐下层的构造形态和高点存在较大的差异,它们没有一一对应的关系.库车坳陷盐构造分为两个阶段:渐新世-中新世库车坳陷构造变形微弱,天山山前的重力(沉积)差异负载导致盐岩发生塑性流变,由山前向盆地流动,形成刺穿型盐丘、盐株;上新世库车坳陷受到强烈挤压,发生大规模逆冲推覆,早期的盐底辟构造演变为盐席断层推覆体,形成大型盐撤凹陷、外来盐席和整合型盐背斜.盐岩边界、区域构造应力变化、差异负载(沉积负载和局部构造负载)是影响库车坳陷盐构造的三个主要因素.     

华南上地壳速度分布与基底、盖层构造研究

对华南地区有代表性的几条宽角地震剖面进行了研究,利用初动到时资料拟合剖面地带地壳上部详细的速度分布,结合其他地球物理资料与地质资料对地壳基底和沉积盖层的构造进行了综合解释. 结果表明,浙-闽-粤东部地区在地壳基底上分布一系列中生代火山岩断陷盆地,火山岩盖层厚度变化为1000-4000m. 浙西-皖南以及湘-赣地区地壳基底起伏较大,盖层主要为古生界,并发育许多受基底形态与边界断裂控制的小型中生代白垩纪盆地. 华南西部的楚雄盆地为一构造复杂的深坳陷,其中侏罗-白垩系的厚度超过10km,并被分割为东部斜坡和西部坳陷两个单元,而西部坳陷又被一中央隆起分割为东、西两个更次级的凹陷. 区内一些主要的断裂构造在速度等值线图上均有明显的反映,如东部的江绍断裂、莲花山断裂和吴川-四会断裂以及西部的程海断裂和绿汁江断裂都是重要的构造分界,此外众多的基底断裂多是盆地与隆起的边界.     

库车坳陷东秋里塔格断裂晚第四纪活动和滑动速率

东秋里塔格断裂是库车坳陷内活动最为强烈的断裂之一,断错了波斯坦托克拉克河两岸的各级阶地。利用全站仪对河西岸的阶地变形进行了精确测量,得到Ⅰ、Ⅱ、Ⅲ级阶地形成以来东秋里塔格断裂的垂直断错量分别为12.5 m、20 m和24.5 m,并根据前人资料和区域类比的方法对各级阶地年龄进行了估计,计算得到晚第四纪以来该断裂的平均垂直滑动速率为1 mm/a左右,所引起的地壳缩短速率为(1.97~2.13)mm/a。     

位移转换的两种概念模型与实例

运用断层转折褶皱理论建立位移转换的两种概念模型, 即反向对称模型和无穷等分模型. 构造几何学和运动学分析表明, 这两类位移转换都造成上覆褶皱向断层位移方向偏移, 偏移角度的正切值等于位移转换梯度. 利用位移转换机制可以合理地解释多层次滑脱构造地区地表(浅层次)褶皱的扭曲及分叉现象, 例如在秋里塔格褶皱带中段, 深部断层之间的位移转换造成库车塔吾深层背斜和南秋里塔格深层背斜在走向上呈左列叠置, 二者在交汇处叠加形成长约18 km的双重构造带, 地表(浅层次)背斜在这个区域向南迁移形成显著的“S”型扭曲.     

江汉-洞庭盆地构造特征和地震活动的初步分析

本文根据地质、地球物理和地震等资料,初步分析了江汉-洞庭盆地构造及其演化和地震活动的基本特征。此盆地由江汉坳陷、华容隆起和洞庭湖坳陷组成,整个盆地呈现二坳一隆、多凹多凸的构造特征。盆地之下是低缓的北东向莫霍面隆起带,埋深30—31km。自早白垩世至第四纪盆地经历了裂陷、强烈裂陷和区域性沉降等复杂过程,第四纪仍存在一定程度的断裂活动和断块差异活动。盆地区有中强地震和小震活动,地震带基本位于第四纪差异活动较明显的地区和莫霍面隆起的斜坡带     

帕米尔东北缘及塔里木盆地西北部弧形构造的扩展特征

归纳了帕米尔东北缘弧形构造的基本特征 ,分析了塔里木盆地西北部EW向逆断裂背斜带与NNW向隐伏走滑断裂之间的关系。通过塔里木盆地与西南天山和帕米尔东北缘变形特征的对比 ,认为塔里木盆地西北部的变形样式与帕米尔东北缘的弧形构造类似 ,弧形构造具有由帕米尔东北缘向塔里木盆地扩展的特征 ,这种构造是帕米尔向北挤入运动所特有的变形样式     

ACTIVE FAULTS AND THEIR FORMATION MECHANISM IN THE EAST SEGMENT OF QIULITAGE ANTICLINE BELT,KUQA DEPRESSION

Based on geological and geomorphologic characteristics of the surface faults acquired by field investigations and subsurface structure from petroleum seismic profiles, this paper analyzes the distribution, activity and formation mechanism of the surface faults in the east segment of Qiulitage anticline belt which lies east of the Yanshuigou River and consists of two sub-anticlines:Kuchetawu anticline and east Qiulitage anticline. The fault lying in the core of Kuchetawu anticline is an extension branch of the detachment fault developed in Paleogene salt layer, and evidence shows it is a late Pleistocene fault. The faults developed in the fold hinge in front of the Kuchetawu anticline in a parallel group and having a discontinuous distribution are fold-accommodation faults controlled by local compressive stress. However, trenching confirms that these fold-accommodation faults have been active since the late Holocene and have recorded part of paleoearthquakes in the active folding zone. The fault developed in the south limb near the core of eastern Qiulitage anticline is a low-angle thrust fault, likely a branch of the upper ramp which controls the development of the eastern Qiulitage anticline. The faults lying in the south limb of eastern Qiulitage anticline are shear-thrust faults, which are developed in the steeply dipping frontal limb of the fault-propagation folds, and also characterized by group occurrence and discontinuous distribution. Several fault outcrops are discovered near Gekuluke, in which the Holocene diluvial fans are dislocated by these faults, and trench shows they have recorded several paleoearthquakes. The surface anticlines of rapid growth and associated accommodation faults are the manifestations of the deep faults that experienced complex folding deformation and propagated upward to the near surface, serving as an indicator of faulting at depth. The fold-accommodation faults are merely local deformation during the folding process, which are indirectly related with the deep faults that control the growth of folds. The displacement and slip rate of these surface faults cannot match the kinematics parameters of the deeper fault, which controls the development of the active folding. However, these active fold-accommodation faults can partly record paleoearthquakes taking place in the active folding zone.     

南天山及塔里木北缘构造带西段地震构造研究

南天山及塔里木北缘构造带位于帕米尔地区东北侧,地震活动强烈。文中通过地质构造剖面、深部探测资料和地震震源机制解资料,综合研究了该区的地震构造模型。结果认为,该区的构造活动主要表现为天山地块逆冲于塔里木地块之上。天山构造系统包括迈丹断裂及其前缘推覆构造;塔里木构造系统包括深部的塔里木北缘断裂、基底共轭断层和浅部的推覆构造。塔里木北缘断裂是发育于塔里木地壳内部的高角度断裂,其形成原因在于塔里木和天山构造变形方向的差异。塔里木北缘断裂为研究区大地震的主要发震构造,天山推覆构造和塔里木基底断裂系统均具有不同性质的中强地震发震能力     

1949年新疆库车7.4/级地震的地震构造条件

前人研究认为 ,库车 194 9年 7 级地震主要与天山南麓活动构造带的NEE向秋立塔格断裂有关。最近笔者根据深地震地壳测深、石油地质及活断裂等研究的新成果 ,对这次地震的构造条件进行了较深入的分析。塔里木陆块向天山俯冲 ,天山上地壳被挤压块断隆升并侧向推覆扩展 ,于天山南缘形成库车盆地及由秋立塔格等一系列逆断裂组成的逆断 -褶皱系 ,这是发育于沉积盖层的薄皮构造。NE向库车 -依西 1井断裂是库车盆地构造中重要的传递断裂 ,位于NE向的乌鲁木齐 -库车 -柯坪构造带中。有关 7 级地震的地震学研究结果与秋立塔格断裂完全不符 ,而与库车 -依西 1井断裂基本一致     

西南天山-塔里木盆地结合带浅深构造关系 ——深地震反射剖面的初步揭露

盆山结合部的浅-深结构样式是进行陆内造山动力学研究与讨论的重要依据.2007年,在喀什东的天山与塔里木盆地之间的过渡带上,完成了一条近南北向的长度为121 km的主动源深地震反射剖面,显示出盆山结合部现今地壳尺度的构造格架.剖面南部呈现出10~12 km巨厚的沉积盖层,沉积盖层内发育滑脱断层;盆山结合部多排隆起构造以及天山山前上地壳显现出向北倾斜的断裂与地表地质观察吻合;盆山结合带展现出滑脱与逆冲推覆构造相关的断层褶皱;与塔里木盆地稳定沉积层相比,在南天山浅、中层地层受到强烈的变形改造,导致地层比较破碎,反射变弱、连续性较差;时间剖面上可以追踪到比较连续的Moho反射,从南向北有加深的趋势.深地震反射剖面揭露出的西南天山与塔里木盆地的这些浅-深构造,展现出塔里木盆地盖层向南天山滑脱与南天山向塔里木盆地逆冲推覆的特征,反映出陆内汇聚下的盆山耦合关系.     

新疆南天山亚肯背斜晚更新世以来的隆起和缩短

野外考察见到亚肯背斜区发育 3级主要地貌面 ,在第 2级和第 1级地貌面 (冲洪积扇 )之下采集了堆积物的热释光样品 ,测年结果分别为距今 3 96～ 4 36万年和 0 78万年 ,区域地貌对比研究认为 ,第 2级地貌面被废弃的时代为距今 4万年至 1 2～ 1 3万年 ,第 1级地貌面被废弃的时代为距今 0 78万年之后。横跨背斜不同部位地貌面的地形剖面表明 ,第 2级地貌面形成以来褶皱隆起高度达 6 0m ,第 1级地貌面褶皱隆起高度为 2 0m。地震反射剖面显示 ,亚肯背斜区滑脱面深度约7km ,由平衡地质剖面法得到第 2和第 1级地貌面形成以来褶皱的缩短量分别为 4 7m和 17 9m。第 2级地貌面形成以来褶皱的隆起和缩短速率分别为 1 5～ 5mm/a和 1 2～ 3 9mm/a,第 1级地貌面形成以来褶皱隆起和缩短速率分别为 2 5 6mm/a和 2 2 9mm/a     

1966年邢台地震群的发震构造模型——新生断层形成?先存活断层摩擦粘滑?

通过对邢台地震极震区浅层探测、新生代深浅构造运动的分期、地壳上地幔结构特征剖析及其与震源参数的对比等研究,指出邢台地震区控制早第三纪盆岭构造发育的铲形断裂及其下部向东缓倾的滑脱面与邢台地震的发生无关;邢台地震群是在最新构造应力场作用下,受北西向断层或横向障碍体阻隔的不连续“深断裂”依次向上撕裂状破裂扩展、引起相邻斜列状深断裂间应力迁移和加载等三维破裂过程的产物;邢台地震断层是先存地壳“深断裂”向上撕裂状扩展的“新生断层”。     

TRANSVERSE STRUCTURES FEATURES OF DIFFERENT DEPTHS DERIVED FROM BOUGUER GRAVITY ANOMALIES IN THE SOUTHERN SEGMENT OF TAN-LU FAULT ZONE

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.     

THE RESEARCH OF THE SEISMOGENIC STRUCTURE OF THE LUSHAN EARTHQUAKE BASED ON THE SYNTHESIS OF THE DEEP SEISMIC DATA AND THE SURFACE TECTONIC DEFORMATION

The seismogenic structure of the Lushan earthquake has remained in suspensed until now. Several faults or tectonics, including basal slipping zone, unknown blind thrust fault and piedmont buried fault, etc, are all considered as the possible seismogenic structure. This paper tries to make some new insights into this unsolved problem. Firstly, based on the data collected from the dynamic seismic stations located on the southern segment of the Longmenshan fault deployed by the Institute of Earthquake Science from 2008 to 2009 and the result of the aftershock relocation and the location of the known faults on the surface, we analyze and interpret the deep structures. Secondly, based on the terrace deformation across the main earthquake zone obtained from the dirrerential GPS meaturement of topography along the Qingyijiang River, combining with the geological interpretation of the high resolution remote sensing image and the regional geological data, we analyze the surface tectonic deformation. Furthermore, we combined the data of the deep structure and the surface deformation above to construct tectonic deformation model and research the seismogenic structure of the Lushan earthquake. Preliminarily, we think that the deformation model of the Lushan earthquake is different from that of the northern thrust segment ruptured in the Wenchuan earthquake due to the dip angle of the fault plane. On the southern segment, the main deformation is the compression of the footwall due to the nearly vertical fault plane of the frontal fault, and the new active thrust faults formed in the footwall. While on the northern segment, the main deformation is the thrusting of the hanging wall due to the less steep fault plane of the central fault. An active anticline formed on the hanging wall of the new active thrust fault, and the terrace surface on this anticline have deformed evidently since the Quaterary, and the latest activity of this anticline caused the Lushan earthquake, so the newly formed active thrust fault is probably the seismogenic structure of the Lushan earthquake. Huge displacement or tectonic deformation has been accumulated on the fault segment curved towards southeast from the Daxi country to the Taiping town during a long time, and the release of the strain and the tectonic movement all concentrate on this fault segment. The Lushan earthquake is just one event during the whole process of tectonic evolution, and the newly formed active thrust faults in the footwall may still cause similar earthquake in the future.