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1.
The direction of convergence between the Rivera and North American plates becomes progressively more oblique (in a counter-clockwise sense as measured relative to the trench-normal direction) northwestward along the Jalisco subduction zone. By analogy to other subduction zones, the forces resulting from this distribution of convergence directions are expected to produce a NW moving, fore-arc sliver and a NW–SE stretching of the fore-arc area. Also, a series of roughly arc parallel strike-slip faults may form in the fore-arc area, both onshore and offshore, as is observed in the Aleutian arc.In the Jalisco subduction zone, the Jalisco block has been proposed to represent such a fore-arc sliver. However, this proposal has encountered one major problem. Namely, right-lateral strike-slip faulting within the fore-arc sliver, and between the fore-arc sliver and the North American plate, should be observed. However, evidence for the expected right-lateral strike-slip faulting is sparse. Some evidence for right-lateral strike-slip faulting along the Jalisco block–North American plate boundary (the Tepic–Zacoalco rift system) has been reported, although some disagreement exists. Right-lateral strike-slip faulting has also been reported within the interior of the Jalisco block and in the southern Colima rift, which forms the SE boundary of the Jalisco block.Threefold, multi-channel seismic reflection data were collected in the offshore area of the Jalisco subduction zone off Manzanillo in April 2002 during the FAMEX campaign of the N/O L'Atalante. These data provide additional evidence for recent strike-slip motion within the fore-arc region of the Jalisco subduction zone. This faulting offsets right-laterally a prominent horst block within the southern Colima rift, from which we conclude that the sense of motion along the faulting is dextral. These data also provide additional evidence for recent subsidence within the area offshore of Manzanillo, as has been proposed.  相似文献   

2.
http://www.sciencedirect.com/science/article/pii/S1674987111000417   总被引:1,自引:0,他引:1  
The characteristics of the Bolokenu-Aqikekuduk (Bo-A) fault, a right-lateral strike-slip fault that runs for more than 700 km long and obliquely cuts North Tianshan Mountains, are evaluated here based on remote sensing data, and through an analysis of the results from field investigations as well as climate-geomorphic events. The fault is composed of a western segment with a NW strike and an eastern segment with a NWW strike. The western segment is nearly 250 km long, extending northwestward into Kazakhstan with a right-lateral strike-slip rate of 5 mm/a. This domain consists of 4e5 rupture sections, with 3e4 deformation belts, caused by ancient or historical earthquakes, and suggesting the potential for the occurrence of further strong earthquakes (with M z 7.5) in future. The eastern segment of the fault shows a right-lateral strike-slip rate of 1e1.4 mm/a, with the development of 3e4 deformation belts caused by ancient or historical earthquakes, and with a potential for future strong earthquake with M z 7.0. A typical strain partitioning style in the compression area has developed between the intermontane Bo- A fault and the piedmont thrust structures of Northern Tianshan Mountains, under the effect of oblique compression, as indicated by the piedmont thrust structure and the strike-slip fault in the mountains.  相似文献   

3.
要通过在TM遥感图像解译和野外观测的基础上,描述了东昆仑断裂带东段活动形迹的组成和活动断层地貌特征,阐述了甘南高原西秦岭地区新近纪拉分盆地的沉积-构造特征,提出了该区东昆仑-秦岭断裂系晚新生代左旋走滑伸展-走滑挤压-走滑伸展的3个阶段的构造变形模式。指出,中新世晚期至上新世早期,东昆仑-秦岭断裂系以左旋走滑伸展活动为主,伴随着西秦岭地区拉分盆地的形成和超基性火山岩群的发育。这期左旋走滑伸展活动向东扩展导致了渭河盆地新近纪引张应力方向由早期的NE-SW向转变为晚期的NW—SE向。上新世晚期以来(约3.4Ma以前),东昆仑-秦岭断裂系以左旋走滑挤压活动为主,导致早期拉分盆地的轻微褶皱变形,走滑挤压活动主要集中在东昆仑东段玛沁-玛曲主断裂带上。该期构造变动持续到早更新世,它的向东扩展产生了广泛的地壳形变效应,包括青藏东缘岷山隆起带的快速崛起、华北地区汾-渭地堑系的形成和发展以及郯庐断裂带右旋走滑活动等。中、晚更新世时期,断裂系以走滑伸展变形为主,主要集中在东昆仑断裂带东段3个分支上,地块向东挤出伴随着顺时针旋转。  相似文献   

4.
The Northwestern (Maghreb) boundary of the Nubia (Africa) Plate   总被引:1,自引:0,他引:1  
Alain Mauffret   《Tectonophysics》2007,429(1-2):21-44
A study of the present compressional deformation of the Northwestern (Maghreb) Nubia (Africa) margin is derived from the analysis of more than 20,000 km of seismic profiles. In the western part the compression is distributed in a large zone with on-land compression in Algeria, mainly strike-slip deformation on the Algerian margin and folds and strike-slip faulting in Eastern Spain. In the middle of the Algerian margin, around Algiers, the evidences of compression become more obvious. In this area a ridge trending N–S that is interpreted as a middle to late Miocene spreading center interacted with the transpressional margin that trends E–W. North of the location of the Boumerdes–Zemmouri earthquake the oceanic crust is deformed by blind thrusts up to 60 km from the coast. These thrusts are south dipping and with the northward dipping thrusts located onshore form a wedge that maybe a positive flower structure at a crustal scale related to the right-lateral transpression of the margin. In the eastern part of the Northwestern (Maghreb) Nubia (Africa) Deformed Belt, off eastern Algeria and Tunisia, the deformation is more intense but limited to the north by the continental slope. Large late Miocene Tortonian folds are cut by the Messinian erosional surface but the present deformation is also evident. It is suggested that the deformation with a double vergence may be followed up to the north of Sicily. After the docking (18 Ma) of the Kabylies to the Africa Plate, the crust has been thinned and the Algerian Basin opened during the middle-late Miocene with an E–W direction. From the late Miocene to the Present the margin has been rethickened by transpression and uplifted.  相似文献   

5.
The significance of late-stage fracturing in the European Alps in a large geodynamic context is reappraised by studying brittle deformations over the entire belt. In the internal Western Alps, paleostress datasets display a major occurrence of orogen-parallel extension resulting in normal faulting and associated strike-slip mode. There the direction of subhorizontal extension rotates with the bending of the Alpine belt. In the Central Alps, paleostress tensors also indicate orogen-parallel extensional regimes, both in the Bergell area and the Lepontine Dome, where the brittle structures are associated with ductile structures related to the formation of large-scale upright folds that accommodate most of the collisional shortening due to the north-directed component of the movement of the South-Alpine indenter. This brittle deformation phase is of Miocene age and is coeval with the propagation of the Alpine front toward the external Alpine domains. In the Eastern Alps, brittle deformation of the Tauern Window displays an overwhelming occurrence of orogen-parallel normal faulting and associated strike-slip regimes again, which is inferred to be driven by lateral extrusion of the orogenic wedge toward the Pannonian basin, partly due to indentation on the Dolomites indenter. The major orogen-parallel extensional signal of the brittle Cenozoic deformations appears remarkably stable all over the internal Alps. Extensional brittle structures are part of a late phase of collisional deformation, during which the propagation of the Alpine front of the Western Alps and the northward movement of the Southern Alpine and the Dolomites indenters in the Central and Eastern Alps were accommodated by orogen-parallel extension in the inner zones, at the scale of the entire chain.  相似文献   

6.
The NW-SE oriented Sorgenfrei–Tornquist Zone (STZ) has been thoroughly studied during the last 25 years, especially by means of well data and seismic profiles. We present the results of a first brittle tectonic analysis based on about 850 dykes, veins and minor fault-slip data measured in the field in Scania, including paleostress reconstruction. We discuss the relationships between normal and strike-slip faulting in Scania since the Permian extension to the Late Cretaceous–Tertiary structural inversions. Our paleostress determinations reveal six successive or coeval main stress states in the evolution of Scania since the Permian. Two stress states correspond to normal faulting with NE-SW and NW-SE extensions, one stress state is mainly of reverse type with NE-SW compression, and three stress states are strike-slip in type with NNW-SSE, WNW-ESE and NNE-SSW directions of compression.The NE-SW extension partly corresponds to the Late Carboniferous–Permian important extensional period, dated by dykes and fault mineralisations. However extension existed along a similar direction during the Mesozoic. It has been locally observed until within the Danian. A perpendicular NW-SE extension reveals the occurrence of stress permutations. The NNW-SSE strike-slip episode is also expected to belong to the Late Carboniferous–Permian episode and is interpreted in terms of right-lateral wrench faulting along STZ-oriented faults. The inversion process has been characterised by reverse and strike-slip faulting related to the NE-SW compressional stress state.This study highlights the importance of extensional tectonics in northwest Europe since the end of the Palaeozoic until the end of the Cretaceous. The importance and role of wrench faulting in the tectonic evolution of the Sorgenfrei–Tornquist Zone are discussed.  相似文献   

7.
About 400 km of new seismic reflection data has been acquired in the study region offshore of Alaçatı, Doğanbey, and Kuşadası, which enables investigation of the active crustal deformation in this region. The deformation onshore in western Turkey is dominated by crustal extension, and clear evidence of this process is also now available from this offshore area. However, in the onshore area adjacent to this study region evidence of active right-lateral strike-slip faulting has also previously been observed. This strike-slip faulting has previously been thought only to accommodate variations in extension between adjacent normal faults. However, in the offshore area there is considerable evidence of zones of deformation, some of which may link to the strike-slip faulting onshore, suggesting that strike-slip faulting may be of greater importance in this region than previously thought.  相似文献   

8.
Based on our detailed structural characterization, we examine possible relationships between thrust faults and strike-slip faults and thrust-cored folds and depositional units in the Silla Syncline, a 4 km wide fold composed of fine-grained mudstone, coarse sandstone and conglomerate deposits of the Cerro Toro Formation in the Magallanes foreland basin, Chilean Patagonia. The syncline is bounded on its western flank by an asymmetric anticline and on its eastern flank by a broad zone of thrust faults and associated folds, which are oriented sub-parallel to the syncline axis. Deposition of the coarse-grained units of the Silla Syncline appears to have taken place in this structurally defined trough controlled primarily by thrust fault related growth structures flanking the syncline.The syncline and surrounding area have also been deformed by two sets of strike-slip faults, one right-lateral and one left-lateral. The strike-slip and thrust faulting operated contemporaneously for much of their active periods, although it appears that thrust faulting, confined within the fine-grained units, initiated slightly earlier than strike-slip faulting. In addition, younger igneous intrusions at high angle to bedding generally localize along the strike-slip faults. The cross-cutting relationships among the intrusions, strike-slip faults, and flexural slip faults show that all these structures were active during the same period, which extends beyond mid-Miocene.These conclusions support the premise that structures in deep-water sediments are important for understanding not only the deformation of a foreland basin, but also its depositional architecture.  相似文献   

9.
郯庐断裂带中段第四纪活动及其分段特征   总被引:30,自引:4,他引:30       下载免费PDF全文
郯庐断裂带是中国东部一条岩石圈尺度的构造不连续带。位于江苏和山东培内的郯庐断裂带中段,在新构造运动时期强烈右旋走滑复活,形成地貌形迹显著的走滑活动断裂带。笔者在断层活动形迹的野外调查和观测的基础上,结合TM遥感影像特征解译和地震震源机制解资料,分析了郯庐断裂中段第四纪活动的分段行为特征。位于嘉山-潍坊之间的郯庐断裂带中段可以进一步划分为3段,北段安丘-茅埠亚段,中段汪湖-宿迁亚段,南段宿迁-嘉山亚段,这三段可能分别是独立的地震破裂段。观测表明,新构造变形主要集中在宿迁以北的中、北段,是历史强震的发生段,而南段变形相对较弱,嘉山以南安徽境内郯庐断裂新构造变形更弱。郯庐断裂带新构造走滑变形的走向分段行为是华北地区不同块体新构造运动位移调节的结果。  相似文献   

10.
青藏高原东南部第四纪右旋剪切运动   总被引:4,自引:0,他引:4  
通过对藏东南嘉黎断裂和滇西北断裂实地考察研究,表明青藏高原南部不存在统一的边界走滑断裂。嘉黎断裂的西段位于青藏高原南部,是一个南北挤压作用下的东西向伸展构造区,发育近南北向的地堑系,嘉黎断裂西段是这些地堑之间的转换断层,具有较高的右旋走滑速率。滇西北断裂与红河断裂构成川滇菱形块体的西南边界,该块体具有向东南逃逸和顺时针旋转运动。  相似文献   

11.
华北地区上新世至第四纪断裂作用型式与左旋扩展   总被引:10,自引:2,他引:8  
华北地区包含两个新生代引张构造域,即太行山以西的鄂尔多斯周缘地堑系和以东的华北-渤海平原盆地。鄂尔多斯周缘地堑系上新世~第四纪的断裂作用表征为正向倾滑活动为主,同时具有右旋或左旋走滑分量的运动型式,指示了NW-SE向地壳引作用,华北-渤海盆地内上新世~第四纪的断裂作用发生在NNE至NE走向的断鲜明带上,具有右旋和正向倾滑的斜向运动特征,EW走向的秦岭断裂系华北引张构造域的东界,表现为右旋走滑,与E  相似文献   

12.
The Tulva Upland is a meridional neotectonic swell that complicates the eastern Russian Plate in its recent manifestation. The intense recent uplift is expressed in the rise and splitting of terraces of the Kama River and anomalously increasing lateral ruggedness of topography. Having a steep western and a gentle eastern limb, the swell is sharply asymmetric in cross section and additionally is complicated by a chain of local NE-trending uplifts. Several morphostructural indications testify to the substantial role of NW-trending strike-slip faulting in the structure of the swell, which was formed under conditions of latitudinal compression and conjugated meridional extension. Such a stress-strain field is confirmed by the study of mesotectonic structural elements in the western steep limb of the swell regarded as a flexure above a suggested reverse fault. Like many other zones of within-plate dislocations in the Russian Plate, the recent Tulva Swell was formed as a result of folding of sedimentary fill and inversion of long-lived platform trough. In our case, this trough inherited the Riphean Kaltasy Aulacogen. Together with the unilateral, probably, reverse-fault-line (?) Ufa Horst, the Tulva Swell is situated opposite to the area of maximum near-latitudinal compression of the recent Urals (the socalled Ufa amphitheater, or Central Ural pinch) and along with other within-plate arches similar in structure—Bugul’ma-Belebei and Obschii Syrt—marks a zone of neotectonic reactivation of the Russian Plate near the Urals.  相似文献   

13.
鸭绿江断裂带的主要特征及其研究意义   总被引:2,自引:0,他引:2  
鸭绿江断裂带是郯庐断裂带东侧的一个次级断裂,也是辽宁东部规模较大的断裂带,具有多期活动特点,先后经历了晚印支-早燕山期(T3-J1)左行平移韧性剪切活动、中燕山期(J2-3)早期低角度伸展滑脱和晚期挤压逆冲活动、晚燕山期(K1)至末燕山期(K2)左行正走滑活动、末燕山晚期-喜马拉雅早期(N)右行走滑活动等4个阶段.它控制着侏罗纪、白垩纪岩浆岩、沉积盆地和矿产的分布,也控制着白垩纪中酸性、中基性火山岩喷发.该断裂带为切割地壳硅镁层的深断裂.最大左行平移20 km,最大垂直断距4 km.该断裂带两侧地质构造特征可以对比,对其研究具有重要的指导意义.  相似文献   

14.
The Qinling Orogenic belt has been well documented that it was formed by multiple steps of convergence and subsequent collision between the North China and South China Blocks during Paleozoic and Late Triassic times. Following the collision in Late Triassic times, the whole range evolved into an intracontinental tectonic process. The geological, geophysical and geochronological data suggest that the intracontinental tectonic evolutionary history of the Qinling Orogenic Belt allow deduce three stages including strike-slip faulting during Early Jurrassic, N-S compressional deformation during Late Jurassic to Early Cretaceous and orogenic collapse during Late Cretaceous to Paleogene. The strike-slip faulting and the infills in Early Jurassic along some major boundary faults show flower structures and pull-apart basins, related to the continued compression after Late Triassic collision between the South Qinling Belt and the South China Block along the Mianlue suture. Late Jurassic to Early Cretaceous large scale of N-S compression and overthrusting progressed outwards from inner of Qinling Orogen to the North China Block and South China Block, due to the renewed southward intracontinental subduction of the North China Block beneath the Qinling Orogenic Belt and continuously northward subduction of the South China Block, respectively. After the Late Jurassic-Early Cretaceous compression and denudation, the Qinling Orogenic Belt evolved into Late Cretaceous to Paleogene orogen collapse and depression, and formed many large fault basins along the major faults.  相似文献   

15.
Intraplate earthquakes in North China are characterized by shallow depth, large magnitude and high frequency. Obviously, the zonal distribution of earthquakes is closely related to recent active faults and Cenozoic graben and rift systems.The active faults are mainly oriented NNE with right-lateral movements, and partially oriented NW with left-lateral movements.The Hetao-Yinchuan graben, Fenhe-Weihe graben and North China Plain rift systems often reflect crustal thinning and mantle uplift.According to the data concerning crustal deformation, particularly the movement patterns of faulting, crustal taphrogenesis and earthquake surface rupture, it is suggested that a shearing-extension mechanism could be considered as a cause of the formation of seismotectonic structures in North China since the Early Cenozoic Era.Graben and rift systems also developed in Northeast and South China. They formed earlier than the graben and rift systems in North China, however, and their activity has decreased during the Quaternary period. It is reasonable that the seismicity in Northeast and South China is not as strong as that in North China.  相似文献   

16.
The Lang Shan, North-Central China, has experienced a complex Mesozoic to recent history of intraplate deformation and sedimentation. Well-exposed cross-cutting relationships document Jurassic right-lateral strike-slip faulting (transtension) followed by several tens of kilometers of Late Jurassic to Early Cretaceous north-northwest–south-southeast crustal shortening and development of an associated foreland basin. Since the Early Cretaceous, the south-central Lang Shan has undergone two phases of extension. The first, which occurred along north–south oriented structures, may represent collapse of an overthickened crust. The youngest deformation is represented by the active Cenozoic mountain-front normal fault system. This compound history may be the result of the complicated far-field effects of plate interactions combined with structural inheritance in a region adjacent to a rigid and undeformed crustal block, the Ordos block.  相似文献   

17.
鄂拉山断裂带是分隔青海乌兰盆地 (柴达木盆地的一部分 )与茶卡—共和盆地的一条重要边界断裂 ,长约 2 0 7km ,由 6条规模较大的主要以右阶或左阶次级断裂段羽列而成 ,阶距约 1~ 3.5km。该断裂右旋走滑的起始时代为第四纪初期 ,约在 1.8~ 3.8MaB .P .期间 ,大的地质体累积断错约 9~12km。断裂新活动形成了一系列山脊、冲沟和阶地等的右旋断错及断层崖、断层陡坎等。晚更新世晚期以来 ,鄂拉山断裂带的平均水平滑动速率为 (4 .1± 0 .9)mm/a ,垂直滑动速率为 (0 .15± 0 .1)mm/a。鄂拉山地区的构造变形受区域NE向构造应力作用下的剪切压扁与鄂拉山断裂的右旋剪切和挤压的共同影响 ,共和—茶卡盆地和乌兰盆地均属于走滑挤压型盆地。青藏高原东北缘地区在区域性北东向挤压的作用之下 ,应变被分解为沿北西西向断裂的左旋走滑和沿北北西向断裂的右旋走滑运动 ,形成一对共轭的剪切断裂。鄂拉山断裂及其他北北西走向断裂的发展演化和变形机制表明青藏高原东北缘向东的挤出和逃逸是非常有限的。  相似文献   

18.
休宁桃溪断裂破碎带构造解析及其区域控矿作用启示   总被引:1,自引:0,他引:1  
位于休宁县-歙县整装勘查区北西缘的休宁桃溪构造破碎带,岩石破碎,矿化蚀变强烈。详细的构造研究从中解析出逆冲推覆、左行平移作用、正断层作用和右行平移作用等多起变形。带中花岗斑岩侵入及金多金属矿矿化与构造的关系研究表明,逆冲推覆构造为成矿前构造,北东向平移断层控制了区内岩浆岩的分布,以北东向为主的正断层是成矿期构造,而右行平移断层是成矿后构造。本构造破碎带的多期变形及其与成矿关系可以为休宁县-歙县整装勘查区的构造控矿作用提供勘查。  相似文献   

19.
A Mw 6.3 magnitude earthquake occurred on October 6, 2008 in southern Damxung County within the N–S trending Yangyi graben, which forms the northern section of the Yadong-Gulu rift of south-central Tibet. The earthquake had a maximum intensity of IX at the village of Yangyi (also Yangying) (29°43.3′N; 90°23.6′E) and resulted in 10 deaths and 60 injured in this sparsely populated region. Field observations and focal mechanism solutions show normal fault movement occurred along the NNE-trending western boundary fault of the Yangyi graben, in agreement with the felt epicenter, pattern of the isoseismal contours, and distribution of aftershocks. The earthquake and its tectonic relations were studied in detail to provide data on the seismic hazard to the nearby city of Lhasa.The Damxung earthquake is one of the prominent events along normal and strike-slip faults that occurred widely about Tibet before and after the 2008 Mw 7.9 magnitude Wenchuan earthquake. Analysis of these recent M ? 5.0 earthquake sequences demonstrate a kinematic relation between the normal, strike-slip, and reverse causative fault movements across the region. These earthquakes are found to be linked and the result of eastward extrusion of two large structural blocks of central Tibet. The reverse and oblique-slip surface faulting along the Longmenshan thrust belt at the eastern margin of the Tibetan Plateau causing the Wenchuan earthquake, was the result of eastward directed compression and crustal shortening due to the extrusion. Prior to it, east–west extensional deformation indicated by normal and strike-slip faulting events across central Tibet, had led to a build up of the compression to the east. The subsequent renewal of extensional deformational events in central Tibet appears related to some drag effect due to the crustal shortening of the Wenchuan event. Unraveling the kinematical relation between these earthquake swarms is a very helpful approach for understanding the migration of strong earthquakes across Tibet.  相似文献   

20.
An integrated interpretation of seismicity, fault plane solutions and deep seismic reflection data suggests that the NE–SW to NW–SE trending Rhone–Simplon fault zone and the gently S-dipping basal Penninic thrust separate fundamentally different stress regimes in the western Swiss Alps. North of the Rhone-Simplon fault zone, strike-slip earthquakes on steep-dipping faults within the Helvetic nappes are a consequence of regional NW–SE compression and NE–SW extension. To the south, vertical maximum stress and N–S extension are responsible for normal mechanism earthquakes that occur entirely within the Penninic nappes above the basal Penninic thrust. Such normal faulting likely results from extension associated with southward movements (collapse) of the Penninic nappes and/or continued uplift and relative northward displacements of the underlying Alpine massifs. Geological mapping and fission-track dating suggest that the two distinct stress regimes have controlled tectonism in the western Swiss Alps since at least the Neogene.  相似文献   

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