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1.
Maher I. El-Soughier 《Arabian Journal of Geosciences》2014,7(4):1297-1311
Palynological and palynofacies analyses were carried out on some middle–upper Cretaceous samples from the El-Noor-1X borehole, northern Western Desert, Egypt. Palynological age has lead to a refinement of the original ages suggested by the drilling company. Upper Albian–Lower Cenomanian, Upper Cenomanian, and Turonian–Coniacian were recognized. The palaeoenvironment was interpreted on the basis of the ecological preferences of the palynomorphs. It was fluctuating between marginal to inner-middle shelf environment. Distribution of araucaroid pollen and xerophytes suggests that arid or semi-arid paleclimate prevailed during the deposition of the studied sediments. A warm tropical palaeoclimate is suggested on the basis of abundance of hygrophilous plants. Based on the recovered palynological organic matter, two palynofacies were recognized: palynofacies A for the Bahariya Formation, which suggests kerogen type III, and palynofacies B for the upper Bahariya and Abu Roash Formations, which suggests kerogen type IX. Data gathered from the theoretically estimated vitrinite reflectances, which are based on spore/pollen coloration, and visual pterographic kerogen analysis are used to define the source rock potentialities of the studied sediments. 相似文献
2.
Maher I. El-Soughier Amr S. Deaf Magdy S. Mahmoud 《Arabian Journal of Geosciences》2014,7(8):3051-3068
Palynological and palynofacies analyses were carried out on some Cretaceous samples from the Qattara Rim-1X borehole, north Western Desert, Egypt. The recorded palynoflora enabled the recognition of two informal miospore biozones arranged from oldest to youngest as Elaterosporites klaszii-Afropollis jardinus Assemblage Zone (mid Albian) and Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (late Albian–mid Cenomanian). A poorly fossiliferous but however, datable interval (late Cenomanian–Turonian to ?Campanian–Maastrichtian) representing the uppermost part of the studied section was also recorded. The palynofacies and visual thermal maturation analyses indicate a mature terrestrially derived organic matter (kerogen III) dominates the sediments of the Kharita and Bahariya formations and thus these two formations comprise potential mature gas source rocks. The sediments of the Abu Roash Formation are mostly dominated by mature amorphous organic matter (kerogen II) and the formation is regarded as a potential mature oil source rock in the well. The palynomorphs and palynofacies analyses suggest deposition of the clastics of the Kharita and Bahariya formations (middle Albian and upper Albian–middle Cenomanian) in a marginal marine setting under dysoxic–anoxic conditions. By contrast, the mixed clastic-carbonate sediments of the Abu Roash Formation (upper Cenomanian–Turonian) and the carbonates of the Khoman Formation (?Campanian–Maastrichtian) were mainly deposited in an inner shallow marine setting under prevailing suboxic–anoxic conditions as a result of the late Cenomanian and the Campanian marine transgressions. This environmental change from marginal to open (inner shelf) basins reflects the vertical change in the type of the organic matter and its corresponding hydrocarbon-prone types. A regional warm and semi-arid climate but with a local humid condition developed near/at the site of the well is thought to have prevailed. 相似文献
3.
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
4.
Salah El Beialy Maher El-Soughier Sayed Abdel Mohsen Haytham El Atfy 《Journal of African Earth Sciences》2011,59(2-3):215-226
Palynological investigation of the Cretaceous Abu Roash, Bahariya, Kharita, Alamein, Alam El Bueib and Betty formations, encountered in the Gebel Rissu-1 well, north Western Desert, Egypt yielded 27 species of pteridophytic spores, 24 of gymnosperm pollen, 25 of angiosperm pollen and 11 of dinoflagellate cysts in addition to some acritarchs, foraminiferal test linings and freshwater algae. This enabled us to recognize five miospore biozones arranged from youngest to oldest as: Classopollis brasiliensis–Afropollis cf. kahramanensis–Dichastopollenites ghazalataensis Assemblage Zone (Late Cenomanian); Elaterosporites klaszii–Sofrepites legouxae–Afropollis jardinus Assemblage Zone (Middle/Late Albian–Early Cenomanian); Pennipollis peroreticulatus–Duplexisporites generalis-Tricolpates Assemblage Zone (Early Aptian–Early Albian); Tucanopollis crisopolensis–Afropollis sp. Assemblage Zone (Barremian) and Appendicisporites cf. tricornitatus–Ephedripites spp. Assemblage Zone (Late Neocomian).The Early Cretaceous Kharita, Alam El Bueib and the Betty formations encountered in the Gebel Rissu-1 well are interpreted to indicate oxic proximal and distal shelf deposits, characterized by type III/IV, V kerogen, which is gas prone but having little potential to produce hydrocarbons. The Upper Cretaceous Abu Roash and Bahariya formations are characterized by a distal suboxic–anoxic and marginal dysoxic–anoxic environment, and their kerogen type III/II indicates gas/oil prone nature. The Bahariya and Kharita Albian–Cenomanian sediments in the present study witnessed the onset of a semi-arid to arid climate, with local or seasonal humid conditions, based on the continuous high abundance of the elaterates pollen and Afropollis-producing plants that inhabited the paleotropical humid coastal plains. 相似文献
5.
《International Geology Review》2012,54(9):840-849
The eastern Pontide magmatic arc extends ～600 km in an E-W direction along the Black Sea coast and was disrupted by a series of fault systems trending NE-SW, NW-SE, E-W, and N-S. These fault systems are responsible for the formation of diachronous extensional basins, rift or pull-apart, in the northern, southern, and axial zones of the eastern Pontides during the Mesozoic. Successive extensional or transtensional tectonic regimes caused the abortive Liassic rift basins and the Albian and Campanian pull-apart basins with deep-spreading troughs in the southern and axial zones. Liassic, Albian, and Campanian neptunian dikes, which indicate extensional tectonic regimes, crop out within the Paleozoic granites near Kale, Gumushane, and the Malm–Lower Cretaceous platform carbonates in Amasya and Gumushane. These neptunian dikes correspond to extensional cracks that are filled and overlain by the fossiliferous red pelagic limestones. Multidirectional Liassic neptunian dikes are consistent with the general trend of the paleofaults (NE-SW, NW-SE, and E-W), and active dextral North Anatolian fault (NAF) and sinistral Northeast Anatolian fault (NEAF) systems. The Albian neptunian dikes in Amasya formed in the synthetic oblique left-lateral normal faults of the main fault zone that runs parallel to the active North Anatolian fault zone (NAFZ). Kinematic interpretation of the Liassic and Albian neptunian dikes suggests N-S extensional stress or northward movement of the Pontides along the conjugate fracture zones parallel to the NAFZ and NEAFZ. This northward movement of the Pontides in Liassic and Albian times requires left-lateral and right-lateral slips along the conjugate NAFZ and Northeast Anatolian fault zones (NEAFZ), respectively, in contrast to the recent active tectonics that have been accommodated by N-S compressional stress. On the other hand, mutual relationships between the neptunian dikes and the associated main fault zone of Campanian age extending in an E-W direction in the Kale area, Gumushane suggest the existence of a main left-lateral transtensional wrench zone. This system might be accommodated by the counterclockwise convergence of the Turkish plate with the Afro-Arabian plate relative to the Eurasian plate, and the southward oblique subduction of Paleotethys beneath the eastern Pontide magmatic arc during the Mesozoic. 相似文献
6.
维马克背斜构造带位于孔雀河斜坡的东部,该背斜构造带西段发育北西走向断裂,东段发育北东东走向断裂,是孔雀河斜坡两大断裂系统的构造转换地带,解析该背斜构造带的构造特征对于认识孔雀河斜坡成因演化和塔里木盆地东北缘早古生代以来的地球动力学背景都具有重要的意义。本文利用断层相关褶皱理论,通过对过孔雀河斜坡维马克背斜构造带地震剖面的精细解释,分析了该背斜构造的构造特征并讨论了其形成演化。维马克背斜构造带西段受北西走向的断裂组Fw1 和Fw2 控制,维马克1号背斜呈北西-南东向展布,东段受北东东走向的断裂组Fw3 和Fw4 控制,维马克2号背斜呈北东-南西向展布,维马克背斜卷入变形的地层为中-上奥陶统、志留系、侏罗系和白垩系,控制背斜形态的断裂系统具有挤压扭动的动力学特征,维马克背斜构造带及其南北两侧盆山系统构造演化大致经历了5期构造运动,维马克背斜构造带至库鲁克塔格山前带地壳缩短37.4 km,南段英吉苏凹陷南缘斜坡带缩短4.31 km,缩短率为25.32%。研究认为,维马克背斜断裂系统是北西向和北东东向两大断裂系统相互影响下的特定构造样式,来自南北不同方向的构造应力在维马克背斜构造带产生走滑效应,使得维马克背斜构造断裂系统具有挤压扭动的特征。 相似文献
7.
We constructed a geological map, a 3D model and cross-sections, carried out a structural analysis, determined the stress fields and tectonic transport vectors, restored a cross section and performed a subsidence analysis to unravel the kinematic evolution of the NE emerged portion of the Asturian Basin (NW Iberian Peninsula), where Jurassic rocks crop out. The major folds run NW-SE, normal faults exhibit three dominant orientations: NW-SE, NE-SW and E-W, and thrusts display E-W strikes. After Upper Triassic-Lower Jurassic thermal subsidence, Middle Jurassic doming occurred, accompanied by normal faulting, high heat flow and basin uplift, followed by Upper Jurassic high-rate basin subsidence. Another extensional event, possibly during Late Jurassic-Early Cretaceous, caused an increment in the normal faults displacement. A contractional event, probably of Cenozoic age, led to selective and irregularly distributed buttressing and fault reactivation as reverse or strike-slip faults, and folding and/or offset of some previous faults by new generation folds and thrusts. The Middle Jurassic event could be a precursor of the Bay of Biscay and North Atlantic opening that occurred from Late Jurassic to Early Cretaceous, whereas the Cenozoic event would be responsible for the Pyrenean and Cantabrian ranges and the partial closure of the Bay of Biscay. 相似文献
8.
Maher A. El Amawy Ahmed M. Muftah Mohamed Abd El-Wahed Aymn Nassar 《Arabian Journal of Geosciences》2011,4(7-8):1067-1085
Al Jabal Al Akhdar is a NE/SW- to ENE/WSW-trending mobile part in Northern Cyrenaica province and is considered a large sedimentary belt in northeast Libya. Ras Al Hilal-Al Athrun area is situated in the northern part of this belt and is covered by Upper Cretaceous–Tertiary sedimentary successions with small outcrops of Quaternary deposits. Unmappable and very restricted thin layers of Palaeocene rocks are also encountered, but still under debate whether they are formed in situ or represent allochthonous remnants of Palaeocene age. The Upper Cretaceous rocks form low-lying to unmappable exposures and occupy the core of a major WSW-plunging anticline. To the west, south, and southeast, they are flanked by high-relief Eocene, Oligocene, and Lower Miocene rocks. Detailed structural analyses indicated structural inversion during Late Cretaceous–Miocene times in response to a right lateral compressional shear. The structural pattern is themed by the development of an E–W major shear zone that confines inside a system of wrench tectonics proceeded elsewhere by transpression. The deformation within this system revealed three phases of consistent ductile and brittle structures (D1, D2, and D3) conformable with three main tectonic stages during Late Cretaceous, Eocene, and Oligocene–Early Miocene times. Quaternary deposits, however, showed at a local scale some of brittle structures accommodated with such deformation and thus reflect the continuity of wrenching post-the Miocene. D1 deformation is manifested, in Late Cretaceous, via pure wrenching to convergent wrenching and formation of common E- to ENE-plunging folds. These folds are minor, tight, overturned, upright, and recumbent. They are accompanied with WNW–ESE to E–W dextral and N–S sinistral strike-slip faults, reverse to thrust faults and pop-up or flower structures. D2 deformation initiated at the end of Lutetian (Middle Eocene) by wrenching and elsewhere transpression then enhanced by the development of minor ENE–WSW to E–W asymmetric, close, and, rarely, recumbent folds as well as rejuvenation of the Late Cretaceous strike-slip faults and formation of minor NNW–SSE normal faults. At the end of Eocene, D2 led to localization of the movement within E–W major shear zone, formation of the early stage of the WSW-plunging Ras Al Hilal major anticline, preservation of the contemporaneity (at a major scale) between the synthetic WNW–ESE to E–W and ENE–WSW strike-slip faults and antithetic N–S strike-slip faults, and continuity of the NW–SE normal faults. D3 deformation is continued, during the Oligocene-Early Miocene, with the appearance of a spectacular feature of the major anticline and reactivation along the E–W shear zone and the preexisting faults. Estimating stress directions assumed an acted principal horizontal stress from the NNW (N33°W) direction. 相似文献
9.
Chahreddine Naji Amara Masrouhi Zayneb Amri Mohamed Gharbi Olivier Bellier 《Arabian Journal of Geosciences》2018,11(19):583
New stratigraphic data, lithostratigraphic correlations, and fault kinematic analysis are used to discuss the basin geometry and sedimentation patterns of the northeastern Tunisia during Cretaceous times. Significant facies and thickness variations are deduced along the northeastern Atlas of Tunisia. The NW-SE 80-km-long regional correlation suggests a high sedimentation rate associated with irregular sea floor. The fault kinematic analysis highlights N-S to NE-SW tectonic extension during Early Cretaceous. During Aptian–Albian times, an extensional regime is recognized with NE-SW tectonic extension. The Cenomanian–Turonian fault populations highlight a WNW-ESE to NW-SE extension, and Campanian–Maastrichtian faults illustrate an NW-SE extension. The normal faulting is associated to repetitive local depocenters with a high rate of sedimentation as well as abundant syntectonic conglomeratic horizons, slump folds, and halokinetic structures. The sequence correlation shows repetitive local depocenters characterizing the basin during Early Cretaceous times. All the above arguments are in favor of basin configuration with tilted blocks geometry. This geometry is shaped by major synsedimentary intra-basin listric normal faults, themselves related to the extensional setting of the southern Tethyan paleomargin, which persisted into the Campanian–Maastrichtian times. The results support a predominant relationship between tilted blocks geometry and sedimentation rather than E-W “Tunisian trough” as it was previously accepted. 相似文献
10.
G. Musumeci 《Geodinamica Acta》2013,26(1-2):119-133
AbstractThe Monte Grighini Complex (Central-Western Sardinia) is a NW-SE trending metamorphic complex of Hereynian age made up of a medium grade Lower tectonic unit with mylonitie granitoids and a low grade Upper tectonic unit exposed in the westernmost and southernmost portions of this complex. The Lower Unit shows a prograde metamor phism from garnet to sillimanite zone and the transition from MP/MT to LP/HT metamorphism. The metamorphic climax was reached at the end of the main deformative phase 1)2 (600° C. 6 kbar). After the main tectonic and metamorphic phase. the Lower Unit was affected by a wide NW-SE trending ductile dextral wrench shear zone. Intrusive rocks emplaced within the shear zone yielded radiometric ages of 305-300 Ma. Shear deformation leads to low temperature C-S mylonites and retrograde phyllonitic rocks with subhorizontal NW-SE trending stretching lineations. Kinematic analysis of the shear zone points to a dextral sense of shear with an amount of ductile displacement of about 7 km. Later low angle N-S and E-W trending normal faults are associated with cataclastic zones separating the Lower Unit from the Upper one. These faults originated during a later evolutionary stage of the shear zone. This shows a progressive change of deformation regime from duetile wrenching to brittle normal faulting. The Monte Grighini Complex is a good example of ductile wrench tectonics. followed by uplift and extension in the Paleozoic basement of Sardinia. 相似文献
11.
12.
Mohamed I. A. Ibrahim 《Cretaceous Research》2002,23(6):775
Quantitative analyses of palynomorph assemblages, particulate organic matter (kerogen), and total organic carbon (TOC) have been made on samples of the Albian–Cenomanian Kharita and Bahariya formations encountered in the Abu Gharadig-5 well, Western Desert, Egypt. Two assemblage palynozones are defined: Assemblage Zone A (Kharita Formation) of late Albian–early Cenomanian age and Assemblage Zone B (Bahariya Formation) of early–middle Cenomanian age. Palynofacies of the Kharita Formation suggest that sedimentation of these strata took place in a warm, shallow, nearshore-marine environment. The deposition of the lower Bahariya Formation took place initially in similar conditions but subsequently further offshore in somewhat deeper water of the inner shelf. The relatively high percentage of Ephedripites, Afropollis and elaterate pollen in both formations indicates an arid climate. The Kharita Formation yields kerogen types III and IV whereas the assemblages recovered from the Bahariya Formation contain types II and III. The TOC is generally between 0.42 and 0.65% in the Kharita Formation, while it ranges between 0.42 and 0.80% in samples of the Bahariya Formation. The spores and pollen grains are pale in colour; hence little source potential for hydrocarbons is indicated. 相似文献
13.
胶莱盆地白垩纪构造应力场与转换机制 总被引：14，自引：3，他引：14
通过对胶莱盆地断层滑动矢量的收集与测量,利用计算机程序反演了盆地白垩纪的古构造应力场演化历史,并据此将盆地的发育划分为三个伸展阶段和三个挤压反转阶段,分别为早白垩世早-中期莱阳期伸展,与造山期后应力松弛重力坍塌有关;早白垩世中-晚期青山期伸展,受早白垩纪早期以后广泛的岩石圈减薄、大陆裂陷制约;晚白垩世王氏期伸展,与郯庐断裂及牟平-即墨断裂右旋走滑有关。三期伸展之间存在构造挤压反转,最后阐明各期盆地发育的地球动力学背景。 相似文献
14.
15.
Geological mapping, interpreted cross sections, structural analyses and residual thickness maps were used to characterize the evolution of stress setting, structure and stratigraphic distribution of the Chepaizi Uplift, which is a NW-SE trending structure located in the Western Junggar Basin. The NS-trending faults show an important transpressional phase during the Late Permian, as demonstrated by tectonic stress field and stratigraphic thickness variations. A major compressional thrusting and strike-slip phase during the Late Jurassic created a series of NW-SE faults that originated by the large-scale uplift event in the Northern Tianshan. Faults were reactivated as thrust and dextral strike-slip faults. In addition, the angular unconformity observed between Jurassic and Cretaceous provide evidence of this tectonic event. Lots of normal faults indicate that the area records southward tilting and regional derived extensional stress that took place during the Neogene. Before that, thick Early Cenozoic strata are widely deposited. The balanced cross-section highlights the evolution of stress setting and stratigraphic distribution of the Chepaizi Uplift. 相似文献
16.
Mineralization Characteristics and Structural Controls of Hydrothermal Deposits in the Gyeongsang Basin, South Korea 总被引：1，自引：0，他引：1
Abstract. Hydrothermal deposits in the Gyeongsang Basin show the genetic relationship with igneous activity from Late Cretaceous to Early Tertiary in the spatial and temporal viewpoints. Many hydrothermal Au-Ag-Cu-Pb-Zn and clay deposits are dominantly distributed within the Gyeongsang Basin. The Gyeongsang Basin is divided into seven metallogenic provinces by spatial distribution. The age ranges of igneous activity and mineralization are 140∼40 Ma and 100∼40 Ma, respectively, and the most dominant age ranges of the both activities are from 90 Ma (Coniacian) to 50 Ma (Eocene). The age consistency between igneous activity and mineralization suggests that this age range is the climactic period of the hydrothermal activity of the Gyeongsang Basin. The metallogenic epochs in the Gyeongsang Basin are divided into three epochs of 100∼80 Ma (western part of the Gyeongsang Basin), 80∼60 Ma (central part of the Gyeongsang Basin), and 60∼40 Ma (eastern part of the Gyeongsang Basin). The mineralization and igneous activity tend to become young eastward in the Gyeongsang Basin.
NNW-SSE mineralized veins from 100 to 80 Ma in the western part of the Gyeongsang Basin are interpreted as the control of the parallel tensional fissures caused by NNW-SSE compressional stress. NW-SE mineralized veins from 80 to 60 Ma in the central part of the Gyeongsang Basin seem to have been formed under the same stress as that of the Gaeum and Yangsan Fault Systems. Namely, NW-SE tensional stress is associated with a conjugate set of fracturing of the WNW-ESE Gaeum Fault System and NNE-SSW Yangsan Fault System. Also NE-SW mineralized veins from 60 to 40 Ma in the eastern part of the Gyeongsang Basin seem to be controlled by the NE-SW fractures. The fractures are related with NE-SW compressional stress and are developed as secondary fractures within the dextral strike slip Yangsan Fault System. 相似文献
NNW-SSE mineralized veins from 100 to 80 Ma in the western part of the Gyeongsang Basin are interpreted as the control of the parallel tensional fissures caused by NNW-SSE compressional stress. NW-SE mineralized veins from 80 to 60 Ma in the central part of the Gyeongsang Basin seem to have been formed under the same stress as that of the Gaeum and Yangsan Fault Systems. Namely, NW-SE tensional stress is associated with a conjugate set of fracturing of the WNW-ESE Gaeum Fault System and NNE-SSW Yangsan Fault System. Also NE-SW mineralized veins from 60 to 40 Ma in the eastern part of the Gyeongsang Basin seem to be controlled by the NE-SW fractures. The fractures are related with NE-SW compressional stress and are developed as secondary fractures within the dextral strike slip Yangsan Fault System. 相似文献
17.
徐沛煤田石炭—二叠纪成煤以来,经过多期次构造运动,对煤系的赋存产生较大影响。利用徐沛地区近年来最新的地震、钻探等勘查成果,运用板块构造学和地质力学的观点,对区内控煤构造特征及其演化进行了探讨。分析认为,本区的控煤构造在空间上呈现出一定的规律性:丰沛区以伸展型和平移走滑型控煤构造样式为主,九里山区和贾汪区以压缩型控煤构造样式为主;近东西向掀斜断块的形成是印支期挤压运动和喜马拉雅期拉张运动的结果,走向近南北的右旋平移走滑断裂形成于新近纪以来右旋压剪性活动,构造面向NW倾的褶皱-逆断层构造型式形成于印支期NW-SE挤压力的作用,构造面向SE倾的褶皱-逆断层构造型式则形成于燕山期SE-NW挤压力的作用。 相似文献
18.
This paper deals with the regional and structural framework of the Cretaceous rocks in the Afikpo Basin located in the southeastern
part of the Lower Benue Trough. Results from regional tectonics are presented together with those of the microtectonic analysis
of microfaults in the Owutu-Afikpo-Adadama area in the basin.
The Owutu-Afikpo-Adadama ridge at the north-central part of the basin marks the boundary between the Late Cenomanian-Turonian-Conianian
sediments and the Campanian-Maastrichtian sandstones. This ridge trends N45°E on average and is faulted in three main directions,
namely: (1) N-S normal faults; (2) NE-SW strike-slip faults; and (3) NW-SE strike-slip faults. The faulted rocks along these
brittle discontinuities are mainly cataclastics with internal fracture cleavage and sigmoidal quartz mosaics that are reminiscent
of extensional deformation. The cataclasites often bear slickenside striations. 相似文献
19.
Shuguang Chen Xiaofeng Liu Yongqian Cui Xianzheng Zhao Jianli Zhang 《International Geology Review》2017,59(3):259-273
Based on the new all-covering 3D seismic data and the drilling-logging data, we established the sequence stratigraphic framework for Dongying Depression and identified two kinds of structural systems in Palaeogene, i.e. the extensional structural system and the transtensional structural system. The extensional structural system consists of different normal faults that predominantly trend NE, EW, and NW. The attitudes of the normal faults vary in different tectonic settings. However, the transtensional structural system consists of some strike–slip faults and some normal faults. According to the analysis of the relationships between the faults and the sedimentary sequences of Dongying Depression, we considered that the extensional structural system was developed mainly from the Palaeocene to the middle Eocene, whereas the transtensional structural system was mostly developed from the middle Eocene to the Oligocene. In addition, we found that the structural systems had transformed since 43.5 Ma, when the subduction direction and activity rates of the Pacific Plate changed and the dextral strike–slip movement of the large-scale Tanlu fault zone started from eastern China. The extensional structural deformation was probably derived from the back-arc extension triggered by subduction rollback of the Pacific Plate under the Eurasian Plate, whereas the transtensional structural deformation was probably related to the regional dextral strike–slip movement induced by the subduction of the Pacific Plate and the continents’ collision between the Indian Plate and the Eurasian Plate. 相似文献
20.
上扬子北部褶皱带的构造应力场演化规律 总被引：3，自引：1，他引：2
在对大量逆冲与平移断层运动学详细分析与观测的基础上,本文利用实测断层擦痕矢量数据组进行了区域应力场反演,根据对断层叠加关系的分析及叠加褶皱的验证,划分出上扬子北部经历过3期挤压构造应力场演化,从早到晚分别为:第1期北西—南东向挤压应力场,第2期近东西向挤压应力场和第3期北东—南西向挤压应力场。结合相关的地质现象,认为在这3期挤压应力场作用下分别形成了晚侏罗世末—早白垩世初的湘鄂西隔槽式褶皱带、早白垩世末—晚白垩世初的川东隔档式褶皱带和南大巴山弧形褶皱带。由此表明,上扬子北部褶皱带的形成顺序为湘鄂西隔槽式褶皱带→川东隔档式褶皱带→南大巴山弧形褶皱带。 相似文献