塔里木西缘明尧勒背斜的弯滑褶皱作用与活动弯滑断层陡坎

塔里木西缘明尧勒活动背斜两翼河流阶地面上多处发育活动弯滑断层陡坎。这些断坎主要分布在活动轴面附近较陡的等斜岩层(地层倾角分别为74°~89°、18°~20°和45°~60°)一翼,往往成排发育在距活动轴面50~1 200m范围内,宽90~1 000m,长40~950m,随着离活动轴面的距离加大弯滑断层陡坎规模渐小。同一阶地面上发育的弯滑断层陡坎几乎以等间距或间距倍数关系产出。这些断坎走向与下伏基岩地层走向一致,基岩地层大多为中-厚层块状砂岩或粉砂岩互层,岩层间力学性质差异较小。明尧勒背斜南翼克孜勒苏河北岸T3阶地面废弃以来,单条弯滑断层的地表最大缩短速率为0.31mm/a,地表最大抬升速率为0.34mm/a。这些弯滑断层的活动具有重复性和新生性。     

褶皱陡坎中相关断层在缩短量计算中的作用——以东秋里塔格背斜为例

通过对东秋里塔格背斜地区内与褶皱陡坎伴生的次级断层进行的地质调查,确定了该次级断层属于伸出向斜的逆冲断层,也给出了次级断层的发生时间晚于褶皱作用起始时间的1个变形实例。褶皱陡坎中发育的次级断层使得陡坎上盘地层沿断层面整体向上迁移,不仅次级断层使得阶地面发生掀斜并增大褶皱陡坎的坡度,而且直接影响了区域缩短增量计算的真实性。计算结果显示,当不考虑次级断层对褶皱陡坎高度的影响时,计算所得缩短增量为51.42m,考虑次级断层对褶皱陡坎高度的影响时,计算得到的地壳缩短量为45.23m。二者相差6.19m,偏差占总缩短增量的13.7%,是一个不可忽视的量值。东秋里塔格背斜北翼和南翼的褶皱陡坎发育于相同岩性的基岩中而且具有相同的形成机制。但是背斜北翼在水平距离不足300m的范围内发育了3级褶皱陡坎,这表明北翼相对于南翼,其活动枢纽带更为紧闭。这是由于北翼存在更加强烈的挤压应力及更加快速的隆升作用。因此,次级断层的研究对于正确认识区域构造演化、了解褶皱与断层相互作用关系具有重要意义。但是仍存在很多问题:1)受观察剖面范围有限、次级断层分布不连续和断距沿延伸方向不断增大等因素的制约,次级断层对缩短增量造成的影响可能被低估,计算结果应为缩短量的最小值。2)次级断层增加的陡坎高度与断层的断距、倾角具有怎样的定量关系?3)若次级断层只发育于活动枢纽带内,又会产生怎样的影响?这些问题还需更多的研究实例来进行更加深入的研究。     

西宁市活断层地震构造模型初步研究

在西宁市城市活断层探测的基础上,对城市活断层与地层褶皱变形的关系进行了研究,认为湟水河断层和NW向的湟水河北岸断层为背斜顶部张性断层,南川河断层为褶皱不均匀变形形成的横向撕裂断层,北川河东岸断层为向斜核部或翼部发育的挤压断层。并根据褶皱变形平衡剖面和重力资料反演,推测了褶皱变形滑脱面深度,初步建立了西宁市城市活断层的地震构造模型。依据地震构造模型,对城市活断层的发震能力进行了讨论     

天山全新世活动断裂及古地震研究

横亘亚洲腹地的天山山脉近代构造活动十分强烈。规模较大的全新世活动断裂有２０多条，多为近东西走向的倾滑型逆断裂，常与活动褶皱相伴生。活动褶皱为无根的断裂扩展褶皱和滑脱褶皱，它的生长是受地下活动的盲断裂所控制，往往是褶皱地震潜在的地区。天山古地震活动遗迹很多，归纳其标志有：多重断层陡坎、古断塞塘、崩积楔、填充楔、推覆楔、地震断错台地和断裂扩展褶皱等。近几年对１０条全新世活动断裂进行开挖研究，已取得大地     

帕米尔北缘木什背斜第四纪滑脱褶皱作用与北翼逆断裂的生长

发育在帕米尔弧形推覆构造带最前缘的木什活动背斜是一南缓北陡的第四纪滑脱褶皱,背斜的最小地壳缩短量为0.7km,构造隆升幅度可达1.5km.木什背斜北翼逆断层由一系列坡向北的反向断层陡坎组成,不同断坎间垂直位移分布呈现此消彼长的特征,不论是整个北翼逆断层西段还是单条断坎,其垂直位移均呈东高西低的不对称分布,位移梯度东高西...     

库车坳陷深浅构造变形与地震关系浅析

通过研究库车地区的地震活动性 ,由地震分布的规律性推断可能的基底断裂 ,并分析了基底活动断裂与地表构造的对应关系、盖层变形和基底变形特征的差异及成因。结果表明 :1)地震震中分布揭示库车坳陷内对应东、西秋里塔格背斜带位置上 ,基底中发育东秋里塔格深断裂和南、北秋里塔格深断裂 ;另外 ,依奇克里克背斜和亚肯背斜位置上也存在对应的深断裂 ,这表明地表构造的形成受深部构造的控制。 2 )依奇克里克构造西端至东秋 5井连线位置上发育 1条NE向走滑断裂 ,在拜城西侧发 1条NW走向的活动断裂 ,这 2条切穿构造走向的活动断裂是库车坳陷构造分段的主因。 3)基底和盖层变形特征的差异主要源于二者之间介质特性的差异。盆地基底岩石圈强度非常高 ,决定了其变形以脆性破裂———地震活动为主 ;而盖层中沉积岩层强度较弱 ,且存在煤和膏盐等极软弱的薄层 ,在构造挤压作用下 ,可以产生黏性或塑性流动大变形及顺层无震滑脱     

THREE-DIMENSIONAL STRUCTURAL FEATURES OF THE PENGXIAN ACTIVE BLIND FAULT IN THE CENTRAL LONGMEN SHAN FRONT BELT

The Pengxian blind fault is a typical active fault in the central Longmen Shan front belt. It has important reference value for understanding the growth mode and process of the eastern Tibetan plateau. Because the fault is covered by the thick Upper Cenozoic strata in the western Sichuan Basin, its three-dimensional spatial distribution, structural style and formation mechanism remain unclear. In this paper, based on several high-resolution 3-D seismic reflection profiles, together with near-surface geological data and borehole data, we investigate the structural geometry of the Pengxian blind fault and build a 3-D model based on the results. We analyze the shape and scale of underground spatial distribution of the fault through a three-dimensional fault model. According to the theory of fault-related fold and fold-accommodation fault, this paper discusses the forming mechanism of the Pengxian buried structures. The shallow tectonic deformation in front of Longmen Shan is closely related to the detachment layer of the Middle and Lower Triassic, and this detachment layer f1 horizontally propagates into the Longquanshan anticline in the western Sichuan Basin. The Pengxian buried fault is a typical fault-bend fold and the f1 horizontally propagates into the western Sichuan Basin with a fault slip of 3.5km. The Pengxian blind fault is a high angle(50°~60°)thrust fault developed in the front wing of the kink-band zone, striking NE-SW, with a total length of~50km; But the fault is not connected with the Dayi buried fault in the south section of Longmen Shan. They are two different faults, and this defines the scale of the Pengxian blind fault. This limitation makes sense for analyzing and evaluating the magnitudes of potential earthquake. All above study provides research basis for further analysis of the potential seismic risk in this area. The Pengxian blind fault is parallel to the anticlinal axis with small amount of offset as a fold-accommodation fault. We believe that the fault formation is related to the fold deformation of the fold front limb. The study reveals the geometry, kinematics and formation mechanism of the Pengxian active fault, and provides a basis for further analysis of fault activity and hazard. Therefore, there is little possibility of strong earthquakes at the Pengxian blind fault due to its formation mechanism of the fault which is generally characterized by fold deformation and shortening deformation. In this paper, we discuss the location of Pengxian blind fault in the middle of Longmen Shan and Sichuan Basin. Because the Pengxian buried structures are in the transition area, the shortening amount in Pengxian indicates that the absorption in the basin is quite limited. It reflects the blocking effect of Sichuan Basin. In the study, we find that the relationship between folds, faults and sediments is an important part of tectonic interpretation; the theory of fault-related fold and fold-accommodation fault is well used for analysis. This would have great significance for the study of structural deformation, which can help to build a three-dimensional model of fault.     

霍尔果斯活动构造的断裂扩展褶皱作用

作者在论述霍尔果斯活动构造地表特征的基础上,进一步讨论了霍尔果斯活动逆断裂的扩展和背斜褶皱的发育过程。断裂扩展褶皱作用以后断裂构造活动演化为背斜后翼向上分叉的数条南倾的叠瓦状逆断裂,地壳总缩短量在5km以上,缩短率大于5mm/a。     

新疆阿克苏大石峡水电站附近活动断层的基本特征

通过对大石峡水电站附近的多条活动断层研究表明:库车坳陷西段的乌什坳陷区内,主要发育有两排新隆起的活动褶皱,由北向南依次为沙依拉木背斜带和苏尔滚背斜带;区内的活动断层主要以NE向为主,其中较大的断层有阔克沙勒断层、迈丹—沙依拉木断层和库齐隐伏断层。研究区中对场地影响较大的断层为迈丹—沙依拉木断层和大石峡口山前断层,它们均表现为东西分段特性,断层整体活动程度西强东弱。库齐隐伏断层是一条晚更新世末期的活动断层,最新的活动时代为距今1.4万年左右。     

A Preliminary Study on a Seismotectonic Model for the Active Faults in the Xining Urban Area

On the basis of the Xining active urban fault survey, we studied the relationship between the active urban fault and fold deformation. The result of this research shows that the Huangshuihe fault and the NW-striking fault on the northern bank of the Huangshulbe River are tensional faults on top of an anticline, the Nanchuanhe fault is a transverse tear fault resulting from differential folding on two sides of the fault, the east bank of the Beichuanhe River fault is a compressional fault developed on the core or climb of a syncline. By balance profile analysis of fold deformation and inversion of gravity anomaly data, we obtained the depth of the detachment plane and established the seismotectonic model of the ）fining urban area. Based on the seismotectonic model, we analyzed the earthquake potential of the active urban fault.     

祁连山北缘玉门—北大河断裂东段古地震特征

玉门—北大河断裂是酒西盆地南侧的一条重要的活动断裂, 断裂西起青草湾, 向东经老玉门市、 青头山、 大红泉, 止于北大河以东骨头泉一带, 长约80 km, 走向北西西, 倾向南, 倾角20°~60°。 玉门—北大河断裂为一条全新世活动的逆冲断裂, 断裂东段保留了地震破裂带遗迹, 通过野外断错地貌调查和探槽开挖, 揭示该破裂带形成于距今1.7±0.3 ka, 此前断裂在4.1±0.3~5.4±0.3 ka及8.4±1.0 ka还有过2次古地震事件, 利用经验公式和已有震例估算, 每次地震震级约为M7。     

东昆仑活动断裂带及其强震活动

本文在简述东昆仑活动断裂带的构造背景与演化历史的基础上，重点叙述了该活动断裂带的展布，几何结构，第四纪运动和强震活动等特征，指出，这是一条具有长期演化历史，深部构造背景和第四纪乃至全新强烈活动的断裂带。因而在我国大地构造演化，尤其在青藏高原隆起形成，占有重要地位，同时，它还是我国西部地区一条主要的强震活动构造带，根据现代强震活动记录和在全带新发现的多期全新世古地震及其地表破裂带，分析了大震在断裂带     

轮台迪那尔河"五一"水库附近活动断裂

对水库近场区内的多条活动断裂研究认为：区域性北轮台断裂具分段性，水库所在的西部断裂全新世以来未活动；全新世活动的东却勒塔格断裂向东延伸至二八台河以西；库区土尸洛克背斜核部有全新世断裂，但对水库影响不大；牙哈背斜北翼发现10km左右的断裂陡坎，隐伏断裂局部出露地表。     

南定河断裂带断层活动特征与古地震事件

南定河断裂带是滇西南地区一条重要的北东向断裂构造，它由东、西两分支断裂组成。本文根据沿断裂带发育的串珠状盆地展布、沉积物的分布以及第四纪地层的变动情况，分析了该断裂带的活动特征，西支断裂第四以来活动强烈且明显的差异性，东支断裂从晚第三纪末起已停止活动，对于这条缺少地震历史载和仪器记录的活动断层，古地地震研究也是一个进一步认识其活动强度的行之有效的方法。     

郯庐断裂带莒县胡家孟晏地震破裂带的发现

郯庐断裂带是中国东部最主要的一条活动断裂带。在该断裂带中部,沂沭断裂东地堑的潍坊—嘉山段中发育了1条长360km的全新世活动断裂带(F5),在该全新世断裂带的北段和中段分别发生了公元70年的安丘地震和公元1668年的郯城地震。2003年底我们考察沭河断裂带时,在莒县境内发现了1条长约7km的地震破裂带,作为活动断层应该归属于F5断裂带,但其是一条独立的地震破裂段还是归属于1668年郯城8.5级地震破裂带有待于进一步的研究。尽管如此,探槽揭示出的上覆未经破坏的地层的14C年代表明,该破裂带在(2140±190)aBP以来没有过活动,因此我们认为其作为1条独立破裂段的可能性较大     

龙门山南段前缘地区活褶皱-逆断层运动学机制——以芦山地震为例

2013年4月20日发生在龙门山南段的芦山MS7.0地震是继发生在龙门山中北段的汶川MS8.0地震之后的又一次强震。本文通过震后地表变形特征、余震分布、震源机制解、石油地震勘探剖面、历史地震数据等资料,结合前人对龙门山南段主干断裂、褶皱构造特征的研究以及野外实地考察,应用活动褶皱及"褶皱地震"的相关理论,初步分析芦山地震的发震构造模式。认为芦山地震为典型的褶皱地震,发震断裂为前山或山前带一隐伏断裂。构造挤压产生的地壳缩短大部分被褶皱构造吸收。认为龙门山南段前缘地区具有活褶皱-逆断层的运动学特征,表明龙门山逆冲作用正向四川盆地内部扩展。     

内蒙大青山山前活动断裂带的地震破裂分段特征

沿内蒙大青山山前活动断裂进行野外调查及探槽开挖的研究结果表明 ,该断裂西部地段及东部地段的最新活动时期在全新世中期以后及全新世晚期以前 ;中部地段在全新世晚期强烈活动 ,公元 84 9年包头地震的地表破裂沿该段展布。大青山山前台地与断层陡坎分布、洪积扇类型及河流阶地断错等地貌特征、全新世晚期断裂活动范围、沿断裂带探槽开挖获得的古地震事件对比 ,以及现今中小地震震中分布表明 ,全新世晚期大青山山前断裂的活动以土左旗为界 ,该界以西全新世晚期断裂强烈活动 ,该界以东全新世晚期断裂活动不明显。全新世时期大青山山前断裂的活动显示了由东向西的迁移     

Study of Paleoearthquakes by Excavation of Grouped Trenches on the Zemuhe Fault in Daqingliangzi,Xichang,Sichuan

Uncertainties are common in the dating of paleoearthquakes.To improve the credibility of the dating of paleoearthquakes,analysis was done on fault activity,sedimentary environment and seismo-geomorphology to investigate paleoearthquakes along the Zemuhe active fault zone.Grouped trenches were excavated near Daqingliangzi,which revealed three palaeoearthquake events aged 160a,3100a and 5500a～8900a,respectively,including recurrence intervals of about 3000a.Sedimentary processes related to strike-slip fault type earthquakes were discussed,and a sedimentary model was put forward for strike-slip faults at hillsides where drumlin and reverse scarp developed.     

郯庐断裂带江苏段安丘-莒县断裂全新世活动及其构造意义

郯庐断裂带是中国东部重要的活动断裂带和边界构造带,其鲁苏段全新世活动断层的空间展布和古地震序列是地学关注的焦点问题,也是准确评价区域地震危险性的重要参数.以往研究工作多集中在郯庐断裂带地表地貌现象明显且有强震记录的山东段,而江苏段则研究程度相对较低,有关郯庐断裂带江苏段全新世活动断层范围和古地震序列问题存在争议.本文利用野外地质地貌调查、浅层地震勘探、钻孔联合剖面以及古地震探槽等多层次综合方法,重点开展郯庐断裂带江苏段全新世活动断层的分布和古地震序列研究.结果显示全新世时期,安丘-莒县断裂是郯庐断裂带江苏段的主要活动断层,且江苏全段该断层都是全新世活动断层.通过对比宿迁闸-皂河镇断裂南北安丘-莒县断裂的断层地貌和断层最新活动时间,并结合宿迁闸-皂河镇断裂在第四纪没有活动过等证据,推测该断层在全新世时期并不是区域阻碍破裂的断层.探槽揭示郯庐断裂带江苏段全新世两次古地震事件,事件Ⅰ限定在（6.2±0.3）-（13.4±0.7）ka B.P.之间,而事件Ⅱ限定在（2.5±0.1）ka B.P.到现今,全新世两次古地震间隔较长.基于构造类比法,安丘-莒县断裂具有深部孕震的构造特点,是区域未来强震的潜在发震构造.     

Paleoseismologic record of earthquakes along the Wuzunxiaoer section of the Altyn Tagh fault and its implication for cascade rupture behavior

The Altyn Tagh fault is one of the few great active strike-slip faults in the world. The recurrence characteristics of paleoearthquakes on this fault are still poorly understood due to the lack of paleoseismic records recorded in high-resolution strata. We document a paleoseismic record in a pull-apart basin along the Wuzunxiaoer section of the central Altyn Tagh fault.The high-resolution strata recorded abundant seismic deformations and their sedimentary responses. Four earthquakes are identified based on event evidence in the form of open fissures, thickened strata, angular unconformities, and folds. The occurrence times of the four events were constrained using radiocarbon dating. Event W1 occurred at AD1220–1773, events W2 and W3 occurred between 407 and 215 BC, and event W4 occurred slightly earlier at 1608–1462 BC, indicating clustered recurrence characteristics. A comparison of the earthquake records along the Wuzunxiaoer section with other records along the Xorkoli section suggests that both sections ruptured during the most recent event.