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1.
利用最新的钻井、地震资料,对东非凯瑞巴斯盆地(Kerimbas Basin)进行构造–地层解释和构造演化过程恢复。结果显示,凯瑞巴斯盆地共发育了4期构造变形:(1)二叠纪–早侏罗世晚期的冈瓦纳陆内裂谷活动,全区发生伸展构造变形;(2)早侏罗世晚期–早白垩世晚期马达加斯加向南漂移,全区发生右行走滑变形;(3)新发现晚白垩世局部伸展构造变形;(4)中新世–第四纪的东非裂谷海域分支活动,导致研究区发生第三期伸展构造变形,形成凯瑞巴斯盆地现今地堑形态。三期伸展构造变形的应力方向均为近E-W向,断层展布方向均为近S-N向。每一期构造变形的范围,强度及对沉积地层的控制作用差异显著。凯瑞巴斯盆地控坳断层活动具有继承性。基于研究结果,建立凯瑞巴斯盆地构造成因模式。冈瓦纳陆内裂谷活动有利于二叠系–下侏罗统构造圈闭的形成,并沟通了烃源岩和储层,有利深层油气的聚集;东非裂谷海域分支裂谷活动沟通了前新生界烃源岩和西部陆坡古近系储层,但同时也破坏了盆地内及东部的圈闭。断层不发育的西部陆坡为主要油气聚集区。  相似文献   

2.
Plate tectonic reconstructions assume a major inactive transform fault, the Davie Fracture Zone, in the West Somali Basin, along which Madagascar is thought to have migrated southwards following Gondwana breakup in the Mesozoic. Based on the interpretation of reflection seismic data, we show that the Walu Ridge offshore Kenya and the Kerimbas Basin offshore northern Mozambique are tectonically unrelated to the southward motion of Madagascar and correlate with Late Cretaceous volcanism and inversion in Kenya and the evolution of the East African Rift System respectively. Offshore Tanzania, geophysical data do not show basement structures indicating the presence of a major transform fault. These results challenge the commonly supported transform margin concept and imply a more southerly pre‐breakup position of Madagascar within Gondwana. Opening of the West Somali Basin by SW‐propagating oblique rifting and seafloor spreading is proposed.  相似文献   

3.
The apatite fission track (AFT) ages and thermal modeling of the Longshoushan and deformation along the northern Hexi Corridor on the northern side of the Qinghai-Tibetan Plateau show that the Longshoushan along the northern corridor had experienced important multi-stage exhumations during the Late Mesozoic and Cenozoic. The AFT ages of 7 samples range from 31.9 Ma to 111.8 Ma. Thermal modeling of the AFT ages of the samples shows that the Longshoushan experienced significant exhumation during the Late Cretaceous to the Early Cenozoic (~130–25 Ma). The Late Cretaceous exhumation of the Longshoushan may have resulted from the continuous compression between the Lhasa and Qiangtang blocks and the flat slab subduction of the Neo-Tethys oceanic plate, which affected wide regions across the Qinghai-Tibetan Plateau. During the Early Cenozoic, the Longshoushan still experienced exhumation, but this process was caused by the Indian-Eurasian collision. Since this time, the Longshoushan was in a stable stage for approximately 20 Ma and experienced erosion. Since ~5 Ma, obvious tectonic deformation occurred along the entire northern Hexi Corridor, which has also been reported from the peripheral regions of the Qinghai-Tibetan Plateau, especially in the Qilianshan and northeastern margin of the plateau. The AFT ages and the Late Cenozoic deformation of the northern Hexi Corridor all indicate that the present northern boundary of the Qinghai-Tibetan Plateau is situated along the northern Hexi Corridor.  相似文献   

4.
ABSTRACT

At the end of the Cenozoic, western Turkey was fragmented by intense intra-continental tectonic deformation resulting in the formation of two extensional areas: a transtensional pull-apart basin systems in the northwest, and graben systems in the central and southwest areas. The question of the connection of this Late Cenozoic extensional tectonics to plate kinematics has long been an issue of discussion. This study presents the results of the fault slip data collected in Bak?rçay Basin in the west of Turkey and addresses changes in the direction of extensional stresses over the Plio-Quaternary. Field observations and quantitative analysis show that Bak?rçay Basin is not a simple graben basin that has evolved during a single phase. It started as a graben basin with extensional regime in the Pliocene and was transformed into a pull-apart basin under the influence of transtensional forces during the Quaternary. A chronology of two successive extensional episodes has been established and provides reasoning to constrain the timing and location of subduction-related back-arc tectonics along the Aegean region and collision-related extrusion tectonics in Turkey. The first NW–SE trending extension occurred during the Pliocene extensional phase, characterized by slab rollback and progressive steepening of the northward subduction of the African plate under the Anatolian Plate. Western Turkey has been affected, during the Middle Quaternary, by regional subsidence, and the direction of extension changed to N–S, probably in relation with the propagation of the North Anatolian Fault System. Since the Late Quaternary, NE–SW extension dominates northwest Turkey and results in the formation and development of elongated transtensional basin systems. Counterclockwise rotation of Anatolian block which is bounded to the north by the right-lateral strike-slip North Anatolian Fault System, accompanies to this extensional phase.  相似文献   

5.
鄂尔多斯盆地周边地带新构造演化及其区域动力学背景   总被引：21，自引：0，他引：21  
系统研究了松辽盆地泰康地区青山口组沉积相类型及沉积特征.对其中青一段与青二、三段的沉积相平面分布与垂向演化规律做了较深入的探讨.青山口组主要发育湖泊相与三角洲相2种沉积相类型,湖泊相包括2种亚相与4种微相,三角洲相包括2种亚相和2种微相.青一段以深湖、半深湖相泥岩沉积为特征,青二、三段以浅湖相与三角洲相砂泥岩互层为特征.区内青山口组主要存在3种类型的储层砂体,分别为三角洲前缘河口坝砂体、三角洲前缘远砂坝砂体和浅湖砂体,其中浅湖砂体是最好的含油砂体,浅湖砂体发育的优势区也即浅湖沉积亚相发育区是区内最重要的油气富集区,是今后油气勘探的有利地区  相似文献   

6.
Based on the concept of tectonic delamination of the lithosphere, we revealed that the Sea of Japan and the Sea of Okhotsk were formed as a result of the tectonic flow of crustal material. The intermittent southward movement of southwestern Japan (Late Cretaceous–Cenozoic) along the eastern Japanese leftlateral strike-slip fault zone resulted in the formation of paired structures: back-arc extensional (Central Japan rift) and frontal compressional (South Japan imbricate–thrust belt) structures. The Sea of Okhotsk was formed in a similar tectonic setting: South Okhotsk rift (back-arc extensional structure) and Kamuikotan–Susunai compressional belt (frontal imbricate-thrust structure). Synchronous extension, compression, and strike-slip movements suggest that the tectonic flow of crustal material played a critical role in the formation of the Sea of Japan and the Sea of Okhotsk.  相似文献   

7.
The common elements and differences of the neighboring Austral (Magallanes), Malvinas and South Malvinas (South Falkland) sedimentary basins are described and analyzed. The tectonic history of these basins involves Triassic to Jurassic crustal stretching, an ensuing Early Cretaceous thermal subsidence in the retroarc, followed by a Late Cretaceous–Paleogene compressional phase, and a Neogene to present-day deactivation of the fold–thrust belt dominated by wrench deformation. A concomitant Late Cretaceous onset of the foreland phase in the three basins and an integrated history during the Late Cretaceous–Cenozoic are proposed. The main lower Paleocene–lower Eocene initial foredeep depocenters were bounding the basement domain and are now deformed into the thin-skinned fold–thrust belts. A few extensional depocenters developed in the Austral and Malvinas basins during late Paleocene–early Eocene times due to a temporary extensional regime resulting from an acceleration in the separation rate between South America and Antarctica preceding the initial opening of the Drake Passage. These extensional depocenters were superimposed to the previous distal foredeep depocenter, postdating the initiation of the foredeep phase and the onset of compressional deformation. Another pervasive set of normal faults of Paleocene to Recent age that can be recognized throughout the basins are interpreted to be a consequence of flexural bending of the lithosphere, in agreement with a previous study from South Malvinas basin. Contractional deformation was replaced by transpressive kinematics during the Oligocene due to a major tectonic plate reorganization. Presently, while the South Malvinas basin is dominated by the transpressive uplift of its active margin with minor sediment supply, the westward basins undergo localized development of pull-apart depocenters and transpressional uplift of previous structures. The effective elastic thickness of the lithosphere for different sections of each basin is calculated using a dynamic finite element numerical model that simulates the lithospheric response to advancing tectonic load with active sedimentation.  相似文献   

8.
While the offshore post‐Caledonian extensional history of the north Norwegian passive margin is well constrained, the tectonic relationship between onshore and offshore regions is less clear because of limited age constraints on the timing of rifting onshore. 40Ar/39Ar dating of K‐feldspar from hydrothermally altered fault rocks in a Precambrian gneiss complex in northern Norway was used to study the timing of extensional faulting onshore. In addition, 40Ar/39Ar dating of K‐feldspar from the host rock provided insight into the regional rock cooling history prior to brittle deformation. Results indicated a dominant Late Permian–Early Triassic (~265–244 Ma) faulting event and found no evidence for later reactivation, which has been documented offshore. The region cooled to below the closure temperature for 40Ar/39Ar K‐feldspar in the Carboniferous to Early Permian, prior to the main brittle faulting event. 40Ar/39Ar dating of fault zone K‐feldspar products provided a means to date brittle faulting events.  相似文献   

9.
INTRODUCTION Whatmechanismresultedinthespreadingof SouthChinaSeabasin(SCSB)?Wasitreallypro ducedbytheinteractionofperipheralplatesofthe SCSBorAilaoshan RedRiversinistralfault(Fig.1)? Figure1.AnoutlinetectonicmapofSouthChinablockandIndochinablock(modified…  相似文献   

10.
In order to unravel the tectonic evolution of the north-central sector of the Sicily Channel (Central Mediterranean), a seismo-stratigraphic analysis of single- and multi-channel seismic reflection profiles has been carried out. This allowed to identify, between 20 and 50 km offshore the central-southern coast of Sicily, a ~80-km-long deformation belt, characterized by a set of WNW–ESE to NW–SE fault segments showing a poly-phasic activity. Within this belt, we observed: i) Miocene normal faults reactivated during Zanclean–Piacenzian time by dextral strike-slip motion, as a consequence of the Africa–Europe convergence; ii) releasing and restraining bend geometries forming well-developed pull-apart basins and compressive structures. In the central and western sectors of the belt, we identified local transpressional reactivations of Piacenzian time, attested by well-defined compressive features like push-up structures and fault-bend anticlines. The reconstruction of timing and style of tectonic deformation suggest a strike-slip reactivation of inherited normal faults and the local subsequent positive tectonic inversion, often documented along oblique thrust ramps. This pattern represents a key for an improved knowledge of the structural style of foreland fold-and-thrust belts propagating in a preexisting extensional domain. With regard to active tectonics and seismic hazards, recent GPS data and local seismicity events suggest that this deformation process could be still active and accomplished through deep-buried structures; moreover, several normal faults showing moderate displacements have been identified on top of the Madrepore Bank and Malta High, offsetting the Late Quaternary deposits. Finally, inside the northern part of the Gela Basin, multiple slope failures, originated during Pleistocene by the further advancing of the Gela Nappe, reveal tectonically induced potential instability processes.  相似文献   

11.
The apatite fission track dating of samples from the Dabashan(i.e., the Langshan in the northeastern Alxa Block) by the laser ablation method and their thermal history modeling of AFT ages are conducted in this study. The obtained results and lines of geological evidence in the study region indicate that the Langshan has experienced complicated tectonic-thermal events during the the Late Cretaceous-Cenozoic. Firstly, it experienced a tectonic-thermal event in the Late Cretaceous(~90–70 Ma). The event had little relation with the oblique subduction of the Izanagi Plate along the eastern Eurasian Plate, but was related to the Neo-Tethys subduction and compression between the Lhasa Block and Qiangtang Block. Secondly, it underwent the dextral slip faulting in the Eocene(~50–45 Ma). The strike slip fault may develop in the same tectonic setting as sinistral slip faults in southern Mongolia and thrusts in West Qinling to the southwest Ordos Block in the same period, which is the remote far-field response to the India-Eurasia collision. Thirdly, the tectonic thermal event existed in the late Cenozoic(since ~10 Ma), thermal modeling shows that several samples began their denudation from upper region of partial annealing zone(PAZ), and the denudation may have a great relationship with the growth of Qinghai-Tibetan Plateau to the northeast. In addition, the AFT ages of Langshan indicate that the main body of the Langshan may be an upper part of fossil PAZ of the Late Cretaceous(~70 Ma). The fossil PAZ were destroyed and deformed by tectonic events repeatedly in the Cenozoic along with the denudation.  相似文献   

12.
晚中生代—新生代构造体制转换与鄂尔多斯盆地改造   总被引：13，自引：15，他引：13       下载免费PDF全文
鄂尔多斯盆地是叠加在华北古生代克拉通台地之上的中生代大型陆内盆地。晚中生代—新生代是鄂尔多斯盆地重要的改造阶段,区域构造体制经历了重大转换,在盆地周缘形成不同方向和不同样式的构造带。其中发生在中、晚侏罗世时期的燕山运动主幕,对鄂尔多斯盆地的定型和发展具有划时代意义,这期构造变动导致鄂尔多斯盆地周缘挤压逆冲构造带的形成。早白垩世时期,对区域构造应力体制转换的响应,鄂尔多斯盆地处于弱引张构造环境,引张构造变形主要集中在盆地西南缘地带,六盘山古地堑发育。新生代时期,构造变形主要发生在鄂尔多斯盆地周缘,形成一系列地堑盆地。晚中新世或上新世以来的新构造运动时期,受到青藏高原快速隆升和向东构造挤出作用的影响,鄂尔多斯盆地西南缘六盘山褶皱带快速崛起,而在盆地的其他周边地带则发生引张变形和地块差异性升降。最后,笔者论述了不同构造应力体制下盆地的改造作用,讨论了鄂尔多斯盆地研究中的一些基础地质构造问题。  相似文献   

13.
试论南中国海盆地新生代板块构造及盆地动力学   总被引：2，自引：0，他引：2       下载免费PDF全文
南海地处欧亚、印度—澳大利亚和菲律宾海板块的交互带,是西太平洋地区面积最大的边缘海之一,其成因机制和演化过程对探讨特提斯构造域和太平洋构造域相互作用及油气勘探等问题具有重要意义,虽备受关注但仍存争议.综合目前该区及外围已有的大地构造等方面的资料,本文从探讨南海外围的构造格架及中-新生代演化过程入手,分析了南海及外围板块...  相似文献   

14.
青藏高原东北缘构造变形研究是认识整个青藏高原隆升过程、机制以及印欧板块碰撞远程效应的重要途径。受控于昆仑山断裂、阿尔金断裂、祁连山断裂的柴达木盆地,新生代地层发育,较完整地记录了高原东北缘的构造变形信息。尤其柴达木盆地西部地区,构造变形强烈,晚新生代地层出露完整,是研究其晚新生代构造变形历史及驱动机制的理想地区。文中应用平衡剖面和古地磁构造旋转方法,结合最新的磁性地层年代,定量恢复该地区的构造变形历史。结果表明,在挤压应力的控制下该地区自22 Ma以来,构造变形主要表现为地层缩短与构造旋转,且其强度呈阶段性增长,具体又可划分为3个阶段：22~9.1 Ma构造活动平静期、9.1~2.65 Ma构造变形相对加强期、2.65 Ma以来构造变形顶峰期。研究表明,造成柴西地区地层持续缩短和顺时针旋转的关键推动力是印欧板块晚新生代的持续向北推挤、昆仑山-祁曼塔格山向柴达木盆地强烈挤压推覆以及阿尔金左旋走滑断裂大规模的复活。  相似文献   

15.
A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates (the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west) towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton.  相似文献   

16.
南海盆地的扩张经历了早期(中生代晚期至新生代早期)和晚期(32~17Ma)2个快速阶段,但2阶段在时间上相继,在形成机制上也可能是一致的.然而由于南海盆地与周围板块侧向作用的关系复杂,对扩张机制的认识一直极具争议,新的构造分析和测年资料表明“弧后扩张”及“走滑扩张”模式均与事实有出入.对位于华南地块西南缘的都龙SongChay变质穹隆体的研究表明,在中生代至新生代时期,至少经历了2期重要的伸展构造: D1期(237~228Ma)穹隆的隆升与表露阶段,代表了印支期造山作用前的伸展构造; D2期(86~78Ma)叠加和改造阶段,并有可能始于176~146Ma,致使穹隆进一步隆升和表露.D2期构造在发育时间、伸展方向及变形方式等上既与华南地块同时期区域伸展构造特征相一致,也与南海盆地北缘早期扩张特征相一致.因此,作为华南地块的组成部分,南海盆地北缘的早期扩张也是华南中生代晚期至新生代早期伸展构造的构成部分.由此推测,南海盆地扩张的动力学机制可能主要来自于华南地块的板内变形作用,而哀牢山-红河断裂带的左行走滑作用对南海盆地新生代的扩张起到推动和加强作用.   相似文献   

17.

In order to unravel the tectonic evolution of the north-central sector of the Sicily Channel (Central Mediterranean), a seismo-stratigraphic analysis of single- and multi-channel seismic reflection profiles has been carried out. This allowed to identify, between 20 and 50 km offshore the central-southern coast of Sicily, a ~80-km-long deformation belt, characterized by a set of WNW–ESE to NW–SE fault segments showing a poly-phasic activity. Within this belt, we observed: i) Miocene normal faults reactivated during Zanclean–Piacenzian time by dextral strike-slip motion, as a consequence of the Africa–Europe convergence; ii) releasing and restraining bend geometries forming well-developed pull-apart basins and compressive structures. In the central and western sectors of the belt, we identified local transpressional reactivations of Piacenzian time, attested by well-defined compressive features like push-up structures and fault-bend anticlines. The reconstruction of timing and style of tectonic deformation suggest a strike-slip reactivation of inherited normal faults and the local subsequent positive tectonic inversion, often documented along oblique thrust ramps. This pattern represents a key for an improved knowledge of the structural style of foreland fold-and-thrust belts propagating in a preexisting extensional domain. With regard to active tectonics and seismic hazards, recent GPS data and local seismicity events suggest that this deformation process could be still active and accomplished through deep-buried structures; moreover, several normal faults showing moderate displacements have been identified on top of the Madrepore Bank and Malta High, offsetting the Late Quaternary deposits. Finally, inside the northern part of the Gela Basin, multiple slope failures, originated during Pleistocene by the further advancing of the Gela Nappe, reveal tectonically induced potential instability processes.

  相似文献   

18.
张岳桥  施炜  董树文 《地质学报》2019,93(5):971-1001
作为大陆内部典型的伸展断陷区和强震活动区,华北地区处于东部太平洋板块俯冲构造和西部印欧大陆碰撞构造的双重大地构造背景之下,其新构造运动相当复杂:西部沿鄂尔多斯地块周缘两个地堑盆地系引张伸展断陷作用、中部太行山块体的局部断陷和整体隆升、东部华北平原区和渤海湾海域区的区域沉降,南缘沿秦岭构造带的左旋走滑拉张活动,东缘沿郯庐断裂带的右旋挤压走滑活动。这些不同类型的断裂构造在晚新生代的阶段性活动,产生了复杂的构造地貌组合特征。综合研究发现,华北晚新生代经历了3期伸展断陷-挤压隆升演化阶段:新近纪晚期(10～2.5 Ma)、早中更新世和晚更新世以来。地壳引张应力方向或NW-SE、或NE-SW向;地块隆升导致湖盆的消亡,挤压应力方向为NE-SW至W-E向。研究认为,华北地区新构造受两个岩石圈构造过程的相互影响:印欧碰撞产生的远程效应和东部岩石圈地幔的上涌。一方面,青藏高原东北缘地块的持续推挤及其构造应力向东的传递导致鄂尔多斯地块反时针旋转和秦岭山地的向东挤出逃逸,这个挤出构造动力学统治了华北地区晚新生代的引张伸展、斜张走滑和挤压变形。尤其是,新近纪晚期强烈的NW-SE向地壳伸展变形与青藏东缘挤出造山作用同步(10～9 Ma至4.2 Ma);上新世末期(约2.5 Ma)、晚更新世早期(约200～70 ka)和晚更新世晚期—全新世(约20 ka以来)3次构造挤压事件与青藏高原东缘构造事件基本对应。另一方面,岩石圈地幔上涌主导了华北东部平原区的区域地壳沉降,同时伴随着早、中更新世的5期幔源火山活动。这两个岩石圈构造作用力此消彼长,深刻统治着华北地区新构造与现今活动构造以及地震构造。  相似文献   

19.
Southwestern Turkey experienced a transition from crustal shortening to extension during Late Cenozoic, and evidence of this was recorded in four distinct basin types in the Mu?la–Gökova Gulf region. During the Oligocene–Early Miocene, the upper slices of the southerly moving Lycian Nappes turned into north-dipping normal faults due to the acceleration of gravity. The Kale–Tavas Basin developed as a piggyback basin along the fault plane on hanging wall blocks of these normal faults. During Middle Miocene, a shift had occurred from local extension to N–S compression/transpression, during which sediments in the Eskihisar–T?naz Basins were deposited in pull-apart regions of the Menderes Massif cover units, where nappe slices were already eroded. During the Late Miocene–Pliocene, a hiatus occurred from previous compressional/transpressional tectonism along intermountain basins and Yata?an Basin fills were deposited on Menderes Massif, Lycian Nappes, and on top of Oligo–Miocene sediments. Plio-Quaternary marked the activation of N–S extension and the development of the E–W-trending Mu?la–Gökova Grabens, co-genetic equivalents of which are common throughout western Anatolia. Thus, the tectonic evolution of the western Anotolia during late Cenozoic was shifting from compressional to extensional with a relaxation period, suggesting a non-uniform evolution.  相似文献   

20.
New kinematic and structural data from the tectonic windows of eastern Crete and the Dodecanese Islands combined with strain and quartz fabric analysis have enabled us to determine a detailed structural evolution of the region and to present a plate tectonic scenario for the southeast Hellenides. During the Early Mesozoic, the southeastern part of Apulia was separated from North Africa and the adjacent microplates by WNW‐trending rift zones and NE‐trending transfer faults. Displacement along the transfer faults has locally reoriented these rift zones into an ENE–WSW direction. Finite strain and quartz fabric asymmetry data indicate that in Late Cenozoic time, NNW‐directed nappe movements caused a nearly coaxial deformation along the ENE–WSW trending rift segments and non coaxial top‐to‐the‐southeast shearing along the WNW‐trending rift segments, as well as along the pre‐existing NE‐trending transfer faults. Tectonic style along the margin varies in response to the obliquity of the principal shortening direction with respect to the margin. These variations could be due to the pre‐convergence geometry of the southern margin of Eurasia and to local strain partitioning effects. Furthermore, a tectonic model is presented in which syncompressional uplift and vertical buoyancy of the subducted crustal slice caused the rapid exhumation of metamorphic units in the south Hellenides. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

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