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1.
Paleogene sediments in fault-bounded basins on Judge Daly Promontory, northeast Ellesmere Island, Canadian High Arctic, are rich in volcanogenic material. Volcanic pebbles within the Cape Back basin near Nares Strait were studied for their petrography, geochemistry, Sr and Nd isotopes, and geochronology to identify and characterize their parent rock. The pebbles are derived from lava flows and ignimbrites of a continental rift-related, strongly differentiated, highly incompatible element enriched, alkaline volcanic suite, the proposed Nares Strait volcanic suite, which is distinct from other alkaline volcanic suites on the northern coasts of Ellesmere Island and Greenland. 40Ar/39Ar amphibole and alkali feldspar ages indicate that volcanism was active around 61–58 Ma and was probably contemporaneous with sedimentation resulting in Middle to Late Paleocene age for deposition within the Cape Back basin and the other Paleogene basins on Judge Daly Promontory.  相似文献   

2.
The tectonic effects of the Thulean mantle plume on the opening of the North Atlantic Ocean is still poorly understood. An analysis of the brittle deformation affecting the Late Cretaceous Chalk and Lower Tertiary igneous formations cropping out in Ulster (Northern Ireland), part of the Thulean Province, leads to the recognition of two tectonic phases. Each of these phases is characterized by different stress regimes with similar trends of the horizontal maximum principal stress σH. The first phase, syn-magmatic and dominated by NE–SW to ENE–WSW extension, occurred during the Palaeocene. It is followed by a second post-magmatic phase, characterized initially by a probably Eocene strike-slip to compressional palaeo-stress regime with σ1 (=σH) trending NE–SW to NNE–SSW associated with the partial reactivation (as reverse faults) of normal faults formed during the first phase NE–SW extension. This episode is postdated by an Oligocene extension, with σH (=σ2) still striking NNE–SSW/NE–SW, which reactivated Eocene strike-slip faults as nearly vertical dip-slip normal faults. This Palaeogene tectonic evolution is consistent with the tectonic evolution of similar age in western Scotland and in the Faeroe Islands. In particular, the post-magmatic NE–SW compression is here related to the ‘Faeroe compressive event’, which is related to the earliest stages of drift of the Greenland plate.  相似文献   

3.
Abstract

The classical model of faulting predicts that slip planes occur in two conjugate sets. Theoretically, more sets can be contemporarily active if pre-existing structures are reactivated in a three-dimensional strain field. Four to six sets of faults have been active in the Holocene in the Zailiski Alatau mountain range, Kazakstan. Faults strike with the highest frequency ENE and ESE and show mostly left-lateral reverse and right-lateral reverse motions, respectively. These faults have a bimodal distribution of dips, forming four sets arranged in orthorhombic symmetry. Locally, NNW- to NNE- striking vertical faults have also been active in the Holocene and show right-lateral strike-slip and left-lateral strike-slip motions, respectively. All these fault sets accommodated the general three-dimensional deformation, given by N-S-directed horizontal shortening, vertical extension, and E-W-directed horizontal extension. Field evidence also shows that the reverse motions, even if with a minor strike-slip component, occurred on high-angle planes with inclination of 65°-85°. ENE- and ESE-striking faults reactivated older fracture zones, whereas the other sets are newly formed. Comparison of these field results with the structures obtained from published analogue models shows a strong similarity of fault geometry and kinematics.  相似文献   

4.
右江地区北西向断裂起源于晚古生代右江盆地内发育的同沉积断裂，这些断裂近等间距平行分布，新生代以来发生了多期次左旋走滑活动，进而导致了右江地区整体发生简单剪切变形。利用三维沙箱模型展开了物理模拟实验，对新生代右江地区的变形机制进行了分析。实验结果表明，早期在红河断裂的左旋剪切错动和印支地块的顺时针旋转联合作用下，右江地区北西向断裂复活，并发生明显的左旋走滑活动；随后川滇地块发生东南向的挤出运动，对右江地区产生侧向挤压，导致了右江地区北西向断裂新一轮的快速左旋走滑活动，同时还导致了右江地区西部的地壳压缩增厚。实验证实新生代右江地区的简单剪切变形以及北西向断裂的走滑活动是印支地块和川滇地块挤出运动共同作用的结果，同时也是印度-欧亚板块碰撞产生的连锁反应之一。   相似文献   

5.
Disjunctive, spaced solution cleavage in carbonate rocks is genetically associated with the propagation of the left-lateral, strike-slip Mattinata Fault in the Gargano Promontory, Italy. Typical cleavage development is restricted within the 200–300-m wide fault zone, which is bounded by virtually unfractured wall rocks. The cleavage consists of sub-parallel solution surfaces, which are often reactivated as sheared solution planes. Geometrical and kinematic relationships exist between the fault and the associated cleavage planes, thus: (1) cleavage–fault intersection lines lie parallel to the fault and the sheared cleavage rotational axes and (2) the cleavage–fault angle is almost constantly equal to 40°. A model for the development of the Mattinata Fault is proposed in which the cleavage surfaces are interpreted as fault-propagation deformations. Cleavage nucleates as solution planes at the front of the advancing fault as the result of stress concentration in this region. Two distinct, time-sequential processes are shown to operate during the fault propagation: (1) typical millimetre- to centimetre-spaced solution surfaces form in the distal tip zone of the advancing fault plane; (2) as the tip advances, the fault plane breaks through the cleavage as minor shear displacements reactivate some of these nascent surfaces. These observations may prove useful in understanding mechanisms for fault-controlled enhanced/reduced permeability and fluid pathways.  相似文献   

6.
《International Geology Review》2012,54(11):1363-1381
ABSTRACT

The mechanism of deformation associated with the Cenozoic collision of India with Asia along the eastern boundary remains a poorly understood aspect of the tectonic evolution of the southwestern South China Block (SCB). Consequently, we carried out a palaeomagnetic investigation of Palaeogene red beds of the Dayao area of Yunnan Province in order to contribute to understanding the Palaeogene evolution of the SCB. A characteristic higher temperature magnetic component (HTC), with an unblocking temperature from 660°C to 680°C, was determined by principal component analysis (PCA), and positive fold tests indicated that the remanence was a primary magnetization. The mean direction of the HTC from the Dayao area is Ds = 27.8° Is = 33.1° κ = 64.8, α95 = 4.3° after tilt correction. Compared with other palaeomagnetic results from the SCB, our data suggest that the central part of the Chuan–Dian Fragment (CDF) experienced approximately 16.3 ± 4.7° clockwise rotation with respect to East Asia. Rotation of the CDF occurred along the left-lateral Xianshuihe–Xiaojiang Fault Systems (XSF-XJF), which exhibit an arc-shaped curve centred on the Eastern Himalayan Syntaxis. The XSF-XJF was approximated by a circle centred on a Euler pole at Lat. = 26.5° N, Lon. = 97.2° E (α95 = 0.2°), based on 11 reference points selected from the fault system. The clockwise rotation of the CDF resulted in left-lateral shearing along the XSF-XJF system, with a left-lateral displacement of ~200 km. The nature of diverse intense local deformation along the Xianshuihe-Xiaojiang left-lateral strike-slip fault systems is also discussed.  相似文献   

7.
郯庐断裂带北段构造特征及构造演化序列   总被引：10，自引：3，他引：7  
根据大量野外地质调查和盆地地震资料分析,认为郯庐断裂北段在中-新生代发生多期不同性质的活动,形成各具特色的构造变形现象。密山县知一镇敦密断裂韧性剪切带具有左旋走滑特征,其中黑云母~(40)Ar/~(36)Ar-~(39)Ar/~(36)Ar等时线年龄为161±3Ma,是郯庐断裂带被利用发生第二期左旋走滑运动并向北扩展到中国东北-俄罗斯远东地区的产物。四平市叶赫乡佳伊断裂带中负花状断裂形成于早白垩世早中期,是郯庐断裂北段在早白垩世遭受左旋走滑-拉张作用的典型代表。四平市石岭镇佳伊断裂大型走滑-逆冲断褶带、桦甸县敦密断裂"逆地堑"、沈阳-哈尔滨逆冲断裂形成于晚白垩世嫩江运动-晚白垩世末期,这一时期脆性右旋走滑-逆冲事件规模大,影响范围广,导致整个郯庐断裂北段遭受到强烈改造。佳伊断裂带和敦密断裂带中古近纪盆地在横剖面上呈不对称地堑,并且不对称地堑沿断裂带走向发生断、超方向左右变位,是郯庐断裂带北段在古近纪时受右旋走滑、伸展双重机制控制的产物。根据郯庐断裂带北段中-新生代不同地质时期变形特征,建立了郯庐断裂北段构造演化序列。即郯庐断裂北段构造演化分为左旋韧性剪切(J_2末期)、左旋张扭(K_1早中期)、右旋压扭(K_2晚期-末期)、右旋走滑断陷(E)和构造反转(E_3末期)五个阶段。其演化历史主要受控于环太平洋构造域的构造作用。  相似文献   

8.
A combined analysis of the recently collected aeromagnetic data from the Eurasian Basin with the magnetic data from the Labrador Sea, the Norwegian-Greenland Sea and the North Atlantic yields a plate kinematic solution for the Eurasian Basin which is consistent with the solution for the North Atlantic as a whole. It shows that the Eurasian Basin and Norwegian-Greenland Sea started to evolve at about anomaly 25 time, though active seafloor spreading did not start in either of these regions until anomaly 24 time. It further shows that the spreading in the Eurasian Basin has been a result of motion only between the North American and Eurasian plates since the beginning, with the Lomonosov Ridge remaining attached to the North American plate. The relative motion among the North American, Greenland and Eurasian plates as obtained from the plate kinematics of the North Atlantic shows that from Late Cretaceous to Late Paleocene (anomaly 34 to 25) Greenland moved obliquely to Ellesmere Island. It is suggested that most of this motion was taken up within the Canadian Arctic Islands resulting in little or no motion along Nares Strait between Greenland and Ellesmere Island. From Late Paleocene to mid-Eocene (anomaly 25-21) Greenland continued to move obliquely, resulting in a displacement of 125 km along and of 90 km normal to the Nares Strait. From mid-Eocene to early Oligocene another 100 km of motion took place normal to the Strait, which correlates well with the Eurekan Orogeny in the Canadian Arctic Island. During these times the relative motion between Greenland and Svalbard (Eurasian plate) was mainly strike-slip with a small component of compression. The implication of the resulting motion between the North American and the Eurasian plates onto the Siberian platform are discussed.  相似文献   

9.
走滑断裂带对中国西部压扭性叠合盆地大中型油气田形成与分布具有重要的控制作用,也是研究难点之一.基于高密度三维地震资料,本文采用多种地震构造解析技术,瞄准噶尔盆地腹部侏罗系开展了精细走滑断裂带解释和变形样式分析.在燕山Ⅱ幕构造活动期,侏罗系发育了NWW向左行压扭性和NE向左行张扭性两类走滑断裂带.它们都是由4组剪切断层复合而成,共同遵从左行简单剪切模式,但几何学特征和构造属性差异很大.NWW和NE向走滑断裂带不存在共轭剪切关系,而是在钝夹角区（135°左右）普遍具有弧形联合与归并趋势.在构造变形中,两类同期左行走滑断裂带弧形联合控制了变形区域旋扭形变和剪切破裂,构成了一个大尺度“面”状旋扭构造体系.旋扭构造变形样式对中亚陆内造山带研究具有一定借鉴意义,也为压扭盆地的油气勘探实践提供了新思路.   相似文献   

10.
The late Eocene to Neogene tectonic evolution of the Dinarides is characterised by shortening and orogen-parallel wrenching superposed on the late Cretaceous and Eocene double-vergent orogenic system. The Central Dinarides exposes NW-trending tectonic units, which were transported towards the Adria/Apulian microcontinent during late Cretaceous–Palaeogene times. These units were also affected by subsequent processes of late Palaeogene to Neogene shortening, Neogene extension and subsidence of intramontane sedimentary basins and Pliocene–Quaternary surface uplift and denudation. The intramontane basins likely relate to formation of the Pannonian basin. Major dextral SE-trending strike-slip faults are mostly parallel to boundaries of major tectonic units and suggest dextral orogen-parallel wrenching of the whole Central Dinarides during the Neogene indentation of the Apulian microplate into the Alps and back-arc type extension in the Pannonian basin. These fault systems have been evaluated with the standard palaeostress techniques. We report four palaeostress tensor groups, which are tentatively ordered in a succession from oldest to youngest: (1) Palaeostress tensor group 1 (D1) of likely late Eocene age indicates E–W shortening accommodated by reverse and strike-slip faults. (2) Palaeostress tensor group 2 (D2) comprises N/NW-trending dextral and W/WSW-trending sinistral strike-slip faults, as well as WNW-striking reverse faults. These indicate NE–SW contraction and subordinate NW–SE extension related to Oligocene to early Miocene shortening of the Dinaric orogenic wedge. (3) Palaeostress tensor group 3a (D3a) comprises mainly NW-trending normal faults, which indicate early/middle Miocene NE–SW extension related to syn-rift extension in the Pannonian basin. The subsequent palaeostress tensor group 3b (D3b) includes NE-trending, SE-dipping normal faults indicating NW–SE extension, which is likely related to further extension in the Pannonian basin. (4) Palaeostress tensor group 4 (D4) is characterised by mainly NW-trending dextral and NE-trending sinistral strike-slip faults. Together, with some E-trending reverse faults, they indicate roughly N–S shortening and dextral wrenching during late Miocene to Quaternary. This is partly consistent with the present-day kinematics, with motion of the Adriatic microplate constrained by GPS data and earthquake focal mechanisms. The north–north-westward motion and counterclockwise rotation of the Adriatic microplate significantly contribute the shortening and present-day wrenching in the Central Dinarides.  相似文献   

11.
Tehran lies on the southern flank of the Central Alborz, an active mountain belt characterized by many historical earthquakes, some of which have affected Tehran itself. The border between the Alborz Mountain and the Tehran’s piedmont (northern part of Tehran City) is marked by the North Tehran Fault (NTF), dividing the Eocene rock formation from the alluvial units of different ages (Early Pleistocene to the recent alluvium). A detail mapping of the piedmont, combined with structural study reveal that two active thrust faults (situated south of the NTF) are of importance for hazard assessment of the City. The geomorphological evidences along the NTF are not in agreement with an active fault, indicating that the fault activity may have been shifted southward. Furthermore differentiation of newly recognized alluvial units and their inferred ages, together with the mapped fault pattern permit us to characterize the Quaternary deformation. The Late Pleistocene alluvial deposits consist of three alluvial fans among them the youngest one together with the modern alluvial fan defines the Holocene deposit. The present deformation in the piedmont is accommodated along vertically left-lateral strike-slip faults and low-angle thrust faults trending in range from N070 to N110E.  相似文献   

12.
柴达木盆地西南缘与之毗邻的阿达滩盆地对周边造山带构造应力场的变化响应敏感,并有较多的地质记录。中新生代以后,其与阿尔金断裂带同处于统一左行走滑剪切应力场作用之下,构造形迹保存较好。通过对盆地内沉积建造、断裂系性质及区域构造特征的识别分析,推断柴达木盆地西南缘在始新世时构造活动处于南北向挤压环境,而渐新世后则转换为左行平移构造应力之下。推测柴达木西南缘在三维空间上应当存在着来自塔里木地块斜向上的推挤力。通过盆地沉积及构造序列分析,初步建立了该区晚古近纪构造运动阶段性演化模式。  相似文献   

13.
对郯庐断裂系研究的最新进展作了介绍。郯庐断裂是多期活动，性质多次转换的巨型断裂，最初的启动时间在晚三叠世末，与南北大陆的碰撞有着直接的关系，早期以走滑（左行）运动为主，伴随挤压和拉伸，范围限于华北地块内部，断裂纵向伸展的高峰期为白垩纪到早始新世，这一时期也是裂陷作用最强的时期，始新世以来以挤压作用为主，东亚走滑断裂系各组成断裂性质复杂，不能以中生代左行平移运动简单概括，走滑断裂系的发展和演化与同时  相似文献   

14.
The Vidigueira–Moura fault (VMF) is a 65 km long, E–W trending, N dipping reverse left-lateral late Variscan structure located in SE Portugal (W Iberia), which has been reactivated during the Cenozoic with reverse right-lateral slip. It is intersected by, and interferes with the NE–SW trending Alentejo–Plasencia fault. East of this intersection, for a length of 40 km the VMF borders an intracratonic tectonic basin on its northern side, thrusting Paleozoic schists, meta-volcanics and granites, on the north, over Cenozoic continental sediments preserved in the basin, on the south. West of the faults intersection, evidence of Cenozoic reactivation is scarce. In the eastern sector, Plio-Quaternary VMF reactivation is indicated by geomorphologic, stratigraphic, and structural data, showing reverse movement with a right-lateral strike-slip component, in response to a NW–SE trending compressive stress. An average vertical displacement rate of 0.06 to 0.08 mm/yr since late Pliocene (roughly the last 2.5 Ma) is estimated. The Alqueva fault (AF) is a subparallel, northward dipping, 7.5 km long anastomosing fault zone that affects Palaeozoic basement rocks, and is located 2.5 km north and on the hanging block of the VMF. The AF is also a reverse left-lateral late Variscan structure, which has been reactivated during the Tertiary with reverse right-lateral slip; however, Plio-Quaternary reactivation was normal left-lateral, as shown by abundant kinematical criteria (slickensides) and geomorphic evidence. It shows an average displacement rate of 0.02 mm/yr for the vertical component of movement in the approximately last 2.5 Ma. It is proposed that the normal displacements on the AF result from tangential longitudinal strain on the upthrown block of the VMF above a convex ramp of this main reverse structure. According to this model of faults interaction, the AF is interpreted to work as a bending-moment fault sited above the VMF thrust ramp. Consequently, it is expected that the displacements on the AF increase towards the topographic surface with the increase in the imposed extension, declining downwards until they vanish above or at the VMF ramp. In order to constrain the proposed scheme, numerical modeling was performed, aiming at the reproduction of the present topography across the faults using different geodynamic models and fault geometries and displacements.  相似文献   

15.
The late-Palaeozoic to Cenozoic stratigraphic and structural record of the southwestern margin of the Bohemian massif and its extension beneath the southward adjacent Molasse basin shows that it is controlled by a system of basement-involving faults which came into evidence during Stephanian– Autunian times and which were subsequently repeatedly reactivated. Thick Permo-Carboniferous clastics accumulated in fault-bounded transtensional basins aligned with the southwestern Bohemian border zone (SWBBZ). Following late-Autunian deformation of these basins, the SWBBZ was overstepped by late-Permian to Late Jurassic platform sediments, reflecting tectonic stability. During the Early Cretaceous the SWBBZ was strongly reactivated, causing disruption and erosion of its Mesozoic sedimentary cover. Sedimentation resumed in the area of the SWBBZ during late Early and Late Cretaceous with clastic influx from the Bohemian massif reflecting gradually increasing tectonic activity along the SWBBZ. During the Late Senonian and Paleocene transpressional deformations resulted in upthrusting of major basement blocks. In the Molasse basin such structures are sealed by transgressive Late Eocene marine strata. Mio-Pliocene uplift of the Bohemian massif, involving mild reactivation of the SWBBZ, is related to the development of the volcano-tectonic Eger zone. The structural configuration of the SWBBZ is largely the result of Late Senonian–Paleocene compressional intraplate tectonics which play a major role in the structural framework of the northern Alpine and Carpathian foreland.  相似文献   

16.
The Tan-Lu fault zone (TLFZ) traverses the Liaohe western depression (LHWD), affords an exceptional opportunity to reveal the structural deformation and evolution of a major strike-slip fault of the LHWD using three dimensional seismic data and well data. In this paper, based on structural interpretations of the 3-D seismic data of the LHWD, combined with depth slice and seismic coherency, a variety of structural features in relation to right-lateral strike-slip fault (the western branch of the Tan-Lu fault) have been revealed presence in the depression, such as thrust faults (Xinlongtai, Taian-Dawa, and Chenjia faults), structural wedges, positive flower structures, and en echelon normal faults. Fault cutoffs, growth strata and the Neogene unconformity developed in the LHWD verify that the activity of right-lateral strike-slip from the late Eocene to Neogene (ca. 43–23 Ma). The study indicates that the right-lateral strike-slip played an important role in controlling the structural deformation and evolution of the LHWD in the early Cenozoic. Moreover, the front structural wedge generated the gross morphology of the Xinlongtai anticline and developed the Lengdong faulted anticline during the late Eocene, and the back structural wedge refolded the Lengdong faulted anticline zone in the late Eocene to the early Oligocene. Wrench-related structures (the Chenjia thrust fault and the en echelon normal faults) were developed during the late Oligocene. Uniform subsidence in the Neogene to Quaternary. Furthermore, the driving force of the right-lateral strike-slip deformation was originated from N–S extension stress related to the opening of the Japan Sea and NE–SW compression, as the far-field effect of India–Eurasia convergence.  相似文献   

17.
In this study, we address the late Miocene to Recent tectonic evolution of the North Caribbean (Oriente) Transform Wrench Corridor in the southern Sierra Maestra mountain range, SE Cuba. The region has been affected by historical earthquakes and shows many features of brittle deformation in late Miocene to Pleistocene reef and other shallow water deposits as well as in pre-Neogene, late Cretaceous to Eocene basement rocks. These late Miocene to Quaternary rocks are faulted, fractured, and contain calcite- and karst-filled extension gashes. Type and orientation of the principal normal palaeostress vary along strike in accordance with observations of large-scale submarine structures at the south-eastern Cuban margin. Initial N–S extension is correlated with a transtensional regime associated with the fault, later reactivated by sinistral and/or dextral shear, mainly along E–W-oriented strike-slip faults. Sinistral shear predominated and recorded similar kinematics as historical earthquakes in the Santiago region. We correlate palaeostress changes with the kinematic evolution along the boundary between the North American and Caribbean plates. Three different tectonic regimes were distinguished for the Oriente transform wrench corridor (OTWC): compression from late Eocene–Oligocene, transtension from late Oligocene to Miocene (?) (D1), and transpression from Pliocene to Present (D2–D4), when this fault became a transform system. Furthermore, present-day structures vary along strike of the Oriente transform wrench corridor (OTWC) on the south-eastern Cuban coast, with dominantly transpressional/compressional and strike-slip structures in the east and transtension in the west. The focal mechanisms of historical earthquakes are in agreement with the dominant ENE–WSW transpressional structures found on land.  相似文献   

18.
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19.
对郯庐断裂系研究的最新进展作了介绍。郯庐断裂是多期活动、性质多次转换的巨型断裂。最初的启动时间在晚三叠世末，与南北大陆的碰撞有着直接的关系。早期以走滑（左行）运动为主，伴随挤压和拉伸，范围限于华北地块内部。断裂纵向伸展的高峰期为白垩纪到早始新世，这一时期也是裂陷作用最强的时期。始新世以来以挤压作用为主。东亚走滑断裂系各组成断裂性质复杂，不能以中生代左行平移运动简单概括。走滑断裂系的发展和演化与同时期大陆边缘所处的地球动力学环境，也就是与南北大陆的碰撞和古大洋板块的持续俯冲关系密切。新生代以来的构造事件使中生代的构造发生强烈变形变位改造。  相似文献   

20.
The southern termination of the left-lateral ‘Moyenne Durance’ Fault (FMD) consists in several segments, some being connected to WSW-trending south-verging reverse faults. To the south, the Aix fault is reactivated in a post-Oligocene strike-slip movement showing that these two faults might belong to the same system. This system seems to transfer, in turn, slip to the east-trending, south-verging Trévaresse reverse fault, allowing southward propagation of the Alpine deformation front in western Provence. Fault kinematics analysis shows lateral stress field change between the two faults. Strike-slip stress state is characterized by an average N150°E trending σ1 near the FMD termination, whilst strike-slip and reverse faulting stress states show north-trending σ1 to the south. To cite this article: P. Guignard et al., C. R. Geoscience 337 (2005).  相似文献   

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