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1.
Eocene carbonate deposits of the Barru area, Sulawesi, Indonesia, provide a rare insight into sedimentation prior to and during propagation of normal faults to the surface. Three main successions; late prerift, latest prerift/earliest synrift and synrift, are characterised by distinctive facies associations and sequence development. Shallow water foraminiferal shoals and intervening lower energy depositional environments occurred during the late prerift in areas which latter formed footwall highs and hangingwall depocentres, respectively. During the latest prerift/earliest synrift, shallow water shelves deepened laterally into slope environments in developing hangingwall depocentres. In both these sequences, sections in developing hangingwall areas are thickest, deepen up-section and thin laterally towards growing footwall highs. Active faulting resulted in rapid drowning of hangingwall depocentres and massive reworking of material derived from collapse of the platform margin and adjacent shallow water/emergent footwall highs.Differential subsidence, controlling water depths and accommodation space, types of carbonate producers and active faulting were the main factors affecting depositional environments and facies distributions. Carbonate producers are extremely sensitive indicators of depositional water depth and energy, hence rapid lateral and vertical facies variations in the Barru area provide quantifiable insight into environmental changes prior to and during active faulting. 相似文献
2.
The Early Miocene was a period of active rifting and carbonate platform development in the Midyan Peninsula, NW Saudi Arabia. However, there is no published literature available dealing with the detailed characterization of the different carbonate platforms in this study area. Therefore, this study aims to present new stratigraphic architectural models that illustrate the formation of different carbonate platforms in the region and the forcing mechanisms that likely drove their formation. This study identified the following features formed during active rifting: a) a Late Aquitanian (N4) fault-block hangingwall dipslope carbonate ramp, b) a Late Burdigalian (N7-N8) isolated normal fault-controlled carbonate platform with associated slope deposits, and c) a Late Burdigalian (N7-N8) attached fault-bounded platform with reef buildups, rimmed shelf developed on a footwall fault-tip within a basin margin structural relay zone that formed coinciding with the second stage of rifting. Variations in cyclicity have been observed within the internal stratigraphic architecture of each platform and also between platforms. High-resolution sequence stratigraphic analysis shows to be parasequences the smallest depositional packages (metre-scale cycles) within the platforms. The hangingwall dipslope carbonate ramp and the attached platform demonstrate aggradational-progradational parasequence stacking patterns. These locations appear to have been more sensitive to eustatic cyclicities, despite the active tectonic setting. The isolated, fault-controlled carbonate platform reveals disorganized stratal geometries in both platform-top and slope facies, suggesting a more complex interplay of rates of tectonic uplift and subsidence, variation in carbonate productivity, and resedimentation of carbonates, such that any sea-level cyclicity is obscure. This study explores the interplay between different forcing mechanisms in the evolution of carbonate platforms in active extensional tectonic regions. Characterization of detailed parasequence-scale internal architecture allows the spatial variation in syn-depositional relative base-level changes to be inferred and is critical for understanding the development of rift basin carbonate platforms. Such concepts may be useful for the prediction of subsurface facies relationships beyond interwell areas in hydrocarbon exploration and reservoir modeling activities. 相似文献
3.
The development of stratigraphic sequences has been demonstrated to be controlled by a set of factors including variations in subsidence, sediment input, eustatic sea level and physiography. Well and seismic data from the Jeanne d'Arc Basin, Grand Banks indicate that mid-Cretaceous tectonism controls at least three of these factors, namely subsidence, sediment input and physiography. North Atlantic rift tectonism was therefore the dominant factor in controlling the migration of coastal to shallow marine environments and the development of sequence stratigraphy in this basin during the mid-Cretaceous. The Avalon Formation respresents a mainly Barremian to Early Aptian regressive phase of clastic, marine to marginal marine sedimentation. This followed the deposition of a thick sequence of mainly marine limestones and shales of the Whiterose Formation above a mid-Valanginian sequence-bounding unconformity. The increased clastic input and northward progradation of coastal environments represented by the Avalon Formation occurred during uplift of a basement arch to the south with subsidence of the basin increasing to the north, accompanied by only relatively minor faulting. These features indicate that a period of epeirogenesis was initiated during the Barremian. Continuing uplift over an expanding area at the southern end of the basin is interpreted to have resulted in the development of an angular unconformity with incised valleys. This mid-Aptian unconformity defines the top of the Whiterose/Avalon sequence. Initiation of brittle fracturing of the sedimentary package and underlying basement (i.e. rifting) in mid-Aptian times resulted in rapid fault-controlled subsidence and fragmentation of the Jeanne d'Arc Basin. This great increase in subsidence rate caused retrogradation of coastal environments across the previously developed sequence-bounding unconformity, despite continuing high rates of sediment input from the uplifted basin margins. The transgressive, siliciclastic Ben Nevis Formation comprises two separate but related facies associations. A locally preserved basal association represents interfingering back-barrier environments and is herein defined as the Gambo Member. An upper, ubiquitous facies association comprises tidal-inlet channel, shoreface and lower shoreface/offshore transition sandstones. This upper facies association onlapped marine ravinement diastems above the laterally equivalent back-barrier facies. The rapid fault-controlled subsidence and high sediment input rate of this mid-Aptian to late Albian rift period resulted in the accumulation and preservation of very thick shoreface sandstones. The transgressive sandstones were buried by laterally equivalent offshore shales of the Nautilus Formation. Flooding of the basin margins induced by the onset of thermal subsidence in latest Albian or early Cenomanian times marks the top of the Ben Nevis/Nautilus syn-rift sequence. 相似文献
4.
Analysis of multi-channel seismic data from the northern East China Sea Shelf Basin (ECSSB) reveals three sub-basins (Socotra, Domi, and Jeju basins), separated by structural highs (Hupijiao Rise) and faulted basement blocks. These sub-basins show a typical rift-basin development: faulted basement and syn-rift and post-rift sedimentation separated by unconformities. Four regional unconformities, including the top of acoustic basement, have been identified and mapped from multi-channel seismic data. Faults in the acoustic basement are generally trending NE, parallel to the regional structural trend of the area. The depths of the acoustic basement range from less than 1000 m in the northwestern part of the Domi Basin to more than 4500 m in the Socotra Basin and 5500 m in the Jeju Basin. The total sediment thicknesses range from less than 500 m to about 1500 m in the northwest where the acoustic basement is shallow and reach about more than 5500 m in the south.Interpretation of seismic reflection data and reconstruction of three depth-converted seismic profiles reveal that the northern ECSSB experienced two phases of rifting, followed by regional subsidence. The initial rifting in the Late Cretaceous was driven by the NW-SE crustal stretching of the Eurasian Plate, caused by the subduction of the Pacific Plate beneath the Eurasian Plate. Extension was the greatest during the early phase of basin formation; estimated rates of extension during the initial rifting are 2%, 6.5%, and 3.5% in the Domi, Jeju, and Socotra basins, respectively. A regional uplift terminated the rifting in the Late Eocene-Early Oligocene. Rifting and extension, although mild, resumed in the Early Oligocene; while fluvio-lacustrine deposition continued to prevail. The estimated rates of extension during the second phase of rifting are 0.7%, 0.8%, and 0.5% in the Domi, Jeju, and Socotra basins, respectively. A second phase of uplift in the Early Miocene terminated the rifting, marking the transition to the post-rift phase of regional subsidence. Regional subsidence dominated the study area between the Early Miocene and the Late Miocene. An inversion in the Late Miocene interrupted the post-rift subsidence, resulting in an extensive thrust-fold belt in the eastern part of the area. Uplift and subsequent erosion were followed by regional subsidence. 相似文献
5.
Distribution of crustal extension and regional basin architecture of the Albertine rift system, East Africa 总被引：1，自引：0，他引：1
G. D. Karner B. R. Byamungu C. J. Ebinger A. B. Kampunzu R. K. Mukasa J. Nyakaana E. N. T. Rubondo N. M. Upcott 《Marine and Petroleum Geology》2000,17(10)
By applying a kinematic and flexural model for the extensional deformation of the lithosphere, and using a recently available EROS Data Center topography DEM of Africa in conjunction with new and previous gravity data from Lakes Albert, Edward and George, we have determined the distribution, amplitude, and style of deformation responsible for the formation of the Albertine rift system, East Africa. Further, we have been able to approximate the three-dimensional architecture of the Albertine rift basin by analyzing a series of profiles across and along the rift system for which we also estimate the flexural strength of the rifted continental lithosphere and its along-strike variation. Previous modeling studies of the Lake Albert basin either overestimated the flexural strength of the extended lithosphere and/or underestimated the crustal extension. The single most important factor that compromised the success of these modeling efforts was the assumption that crustal extension was limited to the present-day distribution of the rift lakes. The style of deformation appears to have changed with time, beginning with a regionally distributed brittle deformation across the region that lead progressively to the preferential growth and development of the major border faults and antithetic/synthetic faults within the collapsed hangingwall block. Minor fault reactivation within the footwall block appears to be related to the release of bending stresses associated by the flexural uplift of the rift flank topography. By simultaneously matching the observed and modeled topography and free-air gravity across the Albertine rift system, we have determined a cumulative extension ranging from 6 to 16 km with the maximum extension occurring in the central and northern segments of the basin. Crustal extension is not constrained to the lake proper, but extends significantly to the east within the hangingwall block. Effective elastic thickness, Te, varies between 24 and 30 km and is unrelated to either the amount of extension or the maximum sediment thickness. The variation of Te relates possibly to small changes in crustal thickness, heterogeneities in crustal composition, and/or variations in radiogenic crustal heat production. Maximum sediment thickness is predicted to be 4.6 km and occurs within the central region of Lake Albert. Low bulk sediment densities, correlating with the location of major lake deltas, may be indicative of present-day sediment overpressures. Our results show that basin geometry is strongly dependent on the cumulative (and distribution) of lithospheric extension and the flexural rigidity of the lithosphere. Thus, in order to determine the total amount of extension responsible for the formation of a basin system, it is necessary to independently constrain the flexural strength of the lithosphere both during and after extension. Conversely, in order to determine the rigidity of extended lithosphere using the stratigraphy and/or geometry of rift basins and passive margins, it is necessary to independently constrain the cumulative extension of the lithosphere. 相似文献
6.
黄福林 《海洋地质与第四纪地质》1992,12(4):21-28
本文初步讨论了区内活动断裂的时空展布及一般特征,NNE—NE向继承性活动断裂是渤海海域及沿海大陆的主导构造,北黄海断裂活动与渤海相似,南黄海则以NEE向为主,苏北陆地及其近海兼有NNE—NE和NW向。资料表明,断裂的水平运动量大于垂直运动量,从各自的沉积厚度所估算的沉积速率说明早、晚第三纪和第四纪的构造强度是很近似的,因而华北和渤海区由走滑正断层反映的水平运动和差异升降运动仍处于十分活跃的发展阶段。 相似文献
7.
尖峰北盆地位于南海北部大陆边缘南部,是一个新生代沉积盆地。盆地发育了A、B、C、D、E5套地震层序;盆地内地质构造复杂,断裂发育,平面上断裂展布方向主要有NE向、近EW向和NW向三组,断裂可分为正断层及平移断层,以正断层为主。古新世—始新世为盆地形成时期即断陷阶段,盆地内部充填了大量河湖相沉积。渐新世—中中新世为盆地发展期即坳陷阶段,盆地沉积类型由陆相逐步过渡到海陆过渡相和海相。中中新世末期,盆地相对隆升,部分地区遭受剥蚀。晚中新世—全新世为区域沉降阶段,盆地及其围区以稳定的浅海-半深海相沉积为主。盆地早期河湖相、三角洲相沉积分布范围较广,最大沉积厚度超过4500m,具有一定的生烃能力;盆地储盖条件良好,油气运移条件良好;尖峰北盆地具备较好的油气潜力。 相似文献
8.
9.
珠江口盆地第三纪古地理及沉积演化 总被引：5，自引：0，他引：5
珠江口盆地第三纪以来经历了断陷、拗陷两个构造演化阶段,具有“南北分带”、“东西分块”的构造格局和先陆后海的沉积特征。本文根据前人资料进行综合整理,编制了珠江口盆地古近纪神狐组、文昌组、恩平组、珠海组地层和新近纪珠江组地层的岩相古地理图。神狐组发育有冲积扇和河湖相,主要分布在珠三坳陷南断裂的狭长地带。文昌组沉积半深湖—深湖相,恩平组水深变浅,河沼相广泛分布。珠海组岩相古地理发生了较大的变化,为海陆过渡相沉积。随后海平面振荡上升,珠江口盆地处于陆架—陆坡环境,发育浅海—半深海沉积。对整个珠江口盆地岩相古地理图的编制为详细研究盆地内各区块的岩相古地理演变提供了区域背景,也为区域构造演化和油气地质条件的研究提供了基础依据。 相似文献
10.
南海北部陆丰凹陷内LF14井记录了早中新世至早上新世的海相沉积地层。古水深重建结果显示研究井位在早中新世突然发生海侵, 水深迅速上升至最大值275m, 随后经数次波动, 整体处于中—外陆架环境, 共记录了5个完整的海侵—海退层序。回剥分析方法重建的LF14井沉降史揭示了研究井位在中中新世(17.5—10Ma)处于快速沉降期, 快速沉降导致的凹陷内沉积物的可容纳空间发育速率高和陆源物质供给充足是造成该阶段沉积速率高的两个重要因素; 晚中新世—早上新世(10—4.53Ma)处于弱沉降期, 推测东沙运动导致凹陷内的沉积物可容纳空间发育速率变小和陆源物质供给减少, 造成该时期内研究井位沉积速率低。最后, 依据定量重建的古水深变化在研究层段识别出一系列短暂存在的构造上升事件。 相似文献
11.
Sedimentary and structural evolution of the Eastern South Korea Plateau (ESKP), East Sea (Japan Sea)
The East Sea (Japan Sea) is a semi-enclosed back-arc basin that is thought to preserve a significant record of tectonic evolution and paleo-climatic changes of Eastern Asia during the Neogene. We use here 2-D regional multi-channel seismic reflection profiles and borehole data from Expedition 346 of the Integrated Ocean Drilling Program (IODP) to provide new constraints on the geological history of the Eastern South Korea Plateau (ESKP). The ESKP represents a structurally-complex basement high in the southwestern East Sea which formed during rifting of the back-arc basin. Our new observations show that the ESKP is composed of numerous horsts and grabens controlled by NE-trending normal faults. The acoustic basement is blanketed by Oligocene to recent sediments that have preferentially accumulated in topographic lows (up to 1.5 km thick) and have been cored during Expedition 346 at Site U1430 close to the southern margin of the ESKP. Seismic profiles in the ESKP reveal three units separated by regional unconformities. These seismic units closely correspond to IODP lithostratigraphic units defined at Site U1430, where biostratigraphic data can be used to constrain the timing of three main evolutionary stages of the ESKP. Stage 1 was related to rifting in the late Oligocene and middle Miocene, terminated by a regional uplift leading to an erosional phase in the middle Miocene. Stage 2 was associated with subsidence in the middle and late Miocene and uplift and accompanying erosion or non-deposition in the latest late Miocene. Stage 3 (Pliocene to present) recorded overall uniform hemipelagic-pelagic subsidence of the ESKP with short-lived tectonically-induced uplifts in the late middle Miocene and latest Miocene-early Pliocene. The three stages of evolution of the ESKP closely correlate to sedimentary changes since the Oligocene and suggest a direct control of regional/local tectonics on sedimentation patterns in the southwestern East Sea, with secondary influence of regional climatic and paleo-oceanographic processes. 相似文献
12.
Michael B.W. Fyhn Lars H. Nielsen Lars O. Boldreel Le D. Thang Jørgen Bojesen-Koefoed Henrik I. Petersen Nguyen T. Huyen Nguyen A. Duc Nguyen T. Dau Anders Mathiesen Ian Reid Dang T. Huong Hoang A. Tuan Le V. Hien Hans P. Nytoft Ioannis Abatzis 《Marine and Petroleum Geology》2009
Seismic stratigraphic and structural analyses of the northwest Phu Khanh Basin, offshore Central Vietnam, based on 2-D seismic data, indicate that the initial rifting began during the latest Cretaceous? or Palaeogene controlled by left-lateral transtension along the East Vietnam Boundary Fault Zone (EVBFZ) and northwest–southeast directed extension east of the EVBFZ. Rifting stopped due to transpression during middle Oligocene times but resumed by left-lateral transtension during the Late Oligocene. Thick sequences of lacustrine and alluvial sediments were deposited during the Palaeogene rift periods. The Late Oligocene rifting ended due to inversion, triggered by right-lateral wrenching near the Palaeogene–Neogene boundary. Following the onset of this inversion regional uplift and volcanism took place in the southern half of the study area and contemporaneous subsidence and transgression took place farther north, leading to widespread carbonate deposition. As the right-lateral wrenching decreased during the early Neogene, thermal subsidence and siliciclastic sedimentation became dominant, resulting in the buildup and southward propagation of the shelf slope. Sediment accumulation and subsidence rates increased after the Middle Miocene times due to eastward tilting of Central Vietnam and the adjacent offshore area. 相似文献
13.
The tectonic mechanisms controlling how volcanic arcs migrate through space and geologic time within dynamic subduction environments is a fundamental tectonic process that remains poorly understood. This paper presents an integrated stratigraphic and tectonic evolution of Late Cretaceous to Recent volcanic arcs and associated basins in the southeastern Caribbean Sea using seismic reflection data, wide-angle seismic refraction data, well data, and onland geologic data. We propose a new tectonic model for the opening of the Grenada and Tobago basins and the 50-250-km eastward jump of arc volcanism from the Late Cretaceous Aves Ridge to the Miocene to Recent Lesser Antilles arc in the southeast Caribbean based on the mapping of three seismic megasequences. The striking similarity of the half-graben structure of the Grenada and Tobago basins that flank the Lesser Antilles arc, their similar smooth basement character, their similar deep-marine seismic facies, and their similar Paleogene sediment thickness mapped on a regional grid of seismic data suggest that the two basins formed as a single, saucer-shaped, oceanic crust Paleogene forearc basin adjacent to the now dormant Aves Ridge. This single forearc basin continued to extend and widen through flexural subsidence during the early to middle Eocene probably because of slow rollback of the subducting Atlantic oceanic slab. Rollback may have been accelerated by oblique collision of the southern Aves Ridge and southern Lesser Antilles arc with the South American continent. Uplift and growth of the southern Lesser Antilles arc divided the Grenada and Tobago basins by early to middle Miocene time. Inversion of normal faults and uplift effects along both edges of the Lesser Antilles arc are most pronounced in its southern zone of arc collision with the South American continent. The late Miocene to Recent depositional histories of the Grenada and Tobago basins are distinct because of isolation of the Grenada basin by growth and uplift of the Neogene Lesser Antilles volcanic ridge. 相似文献
14.
台西南盆地地质构造特征及油气远景 总被引：7，自引：3，他引：7
杜德莉 《海洋地质与第四纪地质》1991,11(3):21-33
本文从盆地的基本地质特征入手,分析了台西南盆地的地层、沉积、构造特征及油气条件,在进行盆地的定性分析的基础上,对盆地内的次级构造单元进行了类比,对盆地的含油气远景进行了评价,提出了该盆地的油气勘探方向。 相似文献
15.
Three-dimensional seismic data and wireline logs from the western Niger Delta were analyzed to reveal the sedimentary and tectonic history of a major deltaic growth-fault depocenter comprising a kilometer-scale rollover anticline. The seismic units of the rollover show a non-uniform thickness distribution with their respective maximum near the main bounding growth-fault on the landward side of the system. This wedge-shaped sediment-storage architecture ultimately reflects the non-uniform creation of accommodation space in the study area that was controlled by 1) the differential compaction of the hanging-wall and footwall strata, 2) the lateral variation of fault-induced tectonic subsidence above the listric master fault, and possibly 3) local subsidence related to the subsurface movement of mobile shale reacting to loading and buoyancy. A sequential three-dimensional decompaction of the interpreted deltaic rollover units allowed to reconstruct and measure the compaction development of the rollover succession through time, documenting that sediment compaction contributed per depositional interval to between 25 and 35% of the generation of depositional space subsequently filled by deltaic sediments. The incremental decompaction of sedimentary units was further used to quantify the cumulative amount of accommodation space at and around the studied rollover that was created by fault movement, shale withdrawal, regional tectonic subsidence, isostasy and changes in sea level. If data on the regional subsidence and eustasy are available, the contribution of these basinwide controls to the generation of depositional space can be subtracted from the cumulative accommodation balance, which ultimately quantifies the amount of space for sediments to accumulate created by fault movement or shale withdrawal. This observation is important in that it implies that background knowledge on subsidence, stratigraphic age and sea-level changes allows to reconstruct and quantify fault movement in syn-tectonic deltaic growth successions, and this solely based on hanging-wall isopach trends independent of footwall information. 相似文献
16.
《Marine and Petroleum Geology》2001,18(5):525-534
Cliff exposures of synsedimentary growth faults at the base of the Cretaceous Ferron sandstone in central Utah represent outcrop analogs to subsurface growth faults. Delta front sands prograded over and deformed less dense prodelta muds of the underlying Tununk Shale. Detailed fault patterns and associated facies changes demonstrate a complex fault history and style for growth fault development rather than a simple progressive development of faults in a basinward position. The most proximal and most distal fault sets were the earliest active faults. Growth faulting was initiated by deposition of cross-bedded distributary channel and mouth bar sandstones that reach 9 m thick in the hangingwalls of the faults. Curvature of the beds in the hangingwall of the faults nucleates smaller conjugate fault sets. Cross-bed sets in the hangingwalls of faults decrease from meter to decimeter scale away from the faults suggesting decreasing flow velocity or decreased preservation of cross sets as a result of decreasing accommodation in distal hangingwalls. Shifts in depositional loci, including upstream and downstream accretion of mouth bar sands contribute to the complex faults history and internal heterogeneity and development of potentially isolated sandy reservoir compartments. 相似文献
17.
南昆嵩地区是万安盆地西部负向构造单元,其中部N–S向断裂贯穿南北,独特的构造特征使其成为研究万安盆地西部构造演化与区域断裂走滑活动的窗口。将研究区沉积地层划分为3套构造层,通过回剥法绘制南昆嵩地区构造–沉积充填剖面,并计算南昆嵩地区构造沉降量以及构造沉降速率,论述南昆嵩地区构造演化史与沉降过程以及控制因素。研究结果表明:下部构造层和中部构造层中断裂组合样式主要为卷心型断层、“Y”型断层、阶梯状断层和高角度花状构造等,断裂延伸方向大致可分为:N–S向、W–E向和NE–SW向3种;上部构造层断裂不发育,为稳定沉积;在区域走滑断裂以及南海扩张运动的控制下,南昆嵩地区始新世以来构造演化经历4个阶段:初始裂谷期、伸展断拗期、走滑改造期和热沉降期,新生代地层构造性质也表现为以伸展与走滑作用为主–走滑断裂控制–热沉降的三段式转变。 相似文献
18.
通过借助层序地层学理论、构造古地貌分析、古生物资料、沉积速率与可容纳空间关系对比,以及典型地震相识别、地震相与沉积相剖面及平面分析等,结合区域地质资料及前人的研究成果,对白云南洼恩平组烃源岩的叠置关系、影响因素、空间展布规律及发育模式进行了研究,得到如下认识:白云南洼恩平组对应一个完整的二级层序,可细分为3个三级层序,自下至上为SQ1、SQ2、SQ3,海平面总体为上升特征,SQ3的最大海泛面对应了整个恩平组二级层序的最大海泛面;白云南洼恩平组为局限浅海环境,具备发育较好海相烃源岩的条件,稳定半封闭的古构造背景,有利于烃源岩有机质的富集保存;沉积速率小,且小于可容空间增长速率,沉积物向陆退积,沉积水体深度变大,利于海相烃源岩的发育;恩平组烃源岩为大陆边缘半闭塞—欠补偿—湿润海湾模式,优质烃源岩主要发育在受隆起及断层遮挡形成的海湾区。 相似文献
19.
南海北部陆缘记录了南海形成演化的历史,但是其新生代构造沉积演化特征在东段和西段的差异及其原因目前还不太清楚。本文分别在珠江口盆地和琼东南盆地的深水区选择了数口构造地理位置相似的井通过精细地层回剥分析,重建了两沉积盆地的沉积速率和沉降速率并结合前人研究成果进行了对比分析。研究结果发现,两沉积盆地在裂陷期的沉积和沉降特征基本相似,但是两者在裂后期的构造沉积演化特征差异明显。珠江口盆地深水区沉积和沉降速率都表现为幕式变化特征,其中沉积速率表现为“两快三慢”的特征而沉降速率表现为“两快一慢”的特征。琼东南盆地深水区的沉积速率表现为“地堑式”变化特征,但是沉降速率表现为“台阶式”上升的变化特征。琼东南盆地“台阶式”上升的沉降速率推测主要是受到海南地幔柱伴随红河断裂的右旋走滑而向西北漂移的影响,这也与南海西北部的岩浆活动以及周围盆地的沉降特征吻合。红河断裂在2.1 Ma BP的右旋走滑控制了琼东南盆地1.8 Ma BP以来的快速沉积和加速沉降分布。 相似文献
20.
High-quality seismic data document a Maastrichtian-Paleocene rift episode on the Vøring margin lasting for 20 m.y. prior to continental breakup. The rift structures are well imaged in the Fenris Graben and Gjallar Ridge region in the western Vøring Basin, and are characterized by low-angle detachment faults with variable fault geometries from south to north. The structural restoration has facilitated the division of pre- and syn-rift sediments across the extensional terrain, which is subsequently used to evaluate mode and mechanism for the lithospheric deformation. Extension estimates based on the structural restoration, subsidence analysis and crustal thickness evaluations yield stretching factors ranging between 1.5 to 2.3 across the main fault zone just landward of the early Tertiary flood basalts. The structural restoration also shows that a middle crustal dome structure, observed beneath the low-angle faults, can be explained by extensional unroofing. Thus, the dome structure may represent a possible metamorphic core complex. Calculations of the effects on vertical motion, assuming uniform and two-layer differential stretching models combined with the arrival of the Iceland mantle plume during rifting, indicate that the uniform extension model may account for both observed early rift subsidence and subsequent late rift uplift and erosion. Although the differential model can not be excluded, it implies early rift uplift which is not compatible with our seismic interpretation. The direct and indirect effects of the Iceland mantle plume may have caused as much as 1.2 km of late rift uplift. Comparison of the volcanic Vøring margin and the non-volcanic West Iberian margin shows similarities in terms of structural style as well as in mode and distribution of extension. 相似文献