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1.
南海晚新生代构造运动与天然气水合物资源   总被引:6,自引:0,他引:6  
南海在新生代经历过两次海底扩张产生了南海洋盆.南海北部和南部原来都是被动大陆边缘,但北部在晚新生代由于菲律宾海板块与欧亚板块在台湾地区发生了碰撞,使陆缘遭受到北西向挤压,在陆缘上产生了北西向左旋走滑活动,我们命名此次构造活动为东沙运动;南部陆缘在早中新世末由于南移的南沙地块与婆罗洲地块发生了碰撞,加上此时北移的菲律宾海板块在明都洛岛地区与欧亚板块发生碰撞,以及南部的东南苏拉威西地块与西北苏拉威西地块发生碰撞,在南海南部产生了挤压构造,我们命名此次构造运动为南沙运动.这两次新生代的构造运动改变了南北陆缘的性质,北部陆缘有人因此称之为准被动陆缘,而南部陆缘的南部则变成了挤压边缘.南海南北陆缘在晚新生代受到的挤压活动,对油气成藏和天然气水合物的形成有重要的推动作用,因为挤压活动有利于流体的流动,进而在适当的地方形成油气藏和天然气水合物.  相似文献   

2.
台西南盆地晚新生代地质演化分析   总被引:2,自引:0,他引:2  
通过对构造沉降、断裂活动、岩浆活动、构造应力场等分析,认为台西南盆地晚新生代地质演化存在两个旋回,即渐新世-中中新世受南海扩张控制、陆缘主动裂陷-沉降旋回和晚中新世-第四纪受台湾弧-陆碰撞影响、陆缘被动拉张-活化旋回。  相似文献   

3.
台西南盆地晚新生代构造演化初步分析   总被引:1,自引:0,他引:1  
钟建强 《海洋通报》1993,12(5):44-50
台西南盆地是南海北部陆缘的一个新生代沉积盆地。通过对构造沉降,断裂活动,岩浆活动,构造应力场等特征的分析和恢复盆地发育过程,认为台西南盆地主要是在南海北部陆缘与台湾晚新生代构造作用下地壳多次张裂而成的。  相似文献   

4.
南海南部海域新生代万安运动的构造意义及其油气资源效应   总被引:13,自引:2,他引:13  
南海南部海域在中中新世末发生了一次区域构造运动,被命名为万安构造运动。这次构造运动在新生代沉积中的表现是断裂、块断、挤压背斜和向斜。部分地区发育逆冲构造等。根据南海区域构造分析产生这次构造运动的起因可能与菲律宾海板块和欧亚板块于13MaBP在民都洛岛处发生碰撞.以及澳大利亚板块和欧亚板块在苏拉威西岛处发生碰撞(10MaBP)有关。这两次碰撞事件均对南海南部海域产生挤压,尤其是第一次碰撞挤压(向西方向)很强烈,是这次构造事件的主导因素。万安构造运动在南海南部海域沉积盆地中产生了许多挤压构造;而该海域沉积盆地中生烃的关键时刻是6MaBP,构造形成时间在生烃关键时间之前。因此,该海域形成了极其丰富的油气资源。  相似文献   

5.
论南海新生代的构造运动   总被引:8,自引:1,他引:7       下载免费PDF全文
白垩纪末和新生代之交的构造运动揭开了新生代南海多旋回构造运动的序幕,自此之后整个南海的地壳开始进入总体受张性背景区域构造应力场控制、以张性沉降为主要特征的地质发展时期.七次区域性的构造运动和沉积作用具有多旋回、周期性振荡式发生的特点,其中尤以白垩纪末和老第三纪初、晚始新世和中渐新世及中中新世和晚中新世之间的三次构造运动表现最为强烈,形成了南海最为重要的三个区域性构造界面.南海地壳运动是欧亚、太平洋和印度—澳大利亚三大板块相互作用效应的结果和缩影,是跨越太平洋和印度—澳大利亚两大板块更大范围的岩石圈和软流圈流动(运动)方向、速度和强度的周期性振荡式改变所导致的.  相似文献   

6.
关于中国东部中、新生代的裂陷作用,马杏垣已有系统论述,对本区中新生代构造,陈国达、王鸿祯、郭令智等亦已论及,近年来,南海海洋研究所提出南海陆缘活化、陆缘扩张的认识(刘昭蜀、刘以宣、杨树康等)。本文主要讨论本区晚白垩世以来的裂陷作用和伸展构造,并侧重于裂谷的分类和演化。  相似文献   

7.
本文详细描述了万安盆地形成演化进程中几期主要构造运动,以及各构造层内的构造样式,并对两者关系进行动力学成因解释。研究表明,万安盆地新生代主要有三期构造运动,早期的礼乐运动造就了现今盆地构造格局的最初雏型;稍后发生的西卫运动使早期的陆级张裂断陷范围进一步扩大,转化为渐新一中中新世的断坳沉积;而最终的万安运动则导致盆内地层强烈挤压、隆升剥蚀、产生构造反转、断块及褶皱、是盆内圈闭构造最发育的时期。伴随万  相似文献   

8.
南海北部陆缘位于特提斯与古太平洋两大构造域的叠合部位,构造特征十分复杂,其构造属性一直是国内外学者争论的焦点,从主动陆缘到被动陆缘,火山型被动陆缘到非火山型被动陆缘等均有表述。南海复杂的形成机制以及东、西部构造差异性所引起的地球物理、岩浆活动等认识的异同,是造成南海北部陆缘构造属性认识差异的主要原因。通过与全球典型地区的比较研究,进一步加强对南海形成演化过程分析,开展大洋钻探与多学科综合分析,揭示南海海盆的多期扩张与多盆张裂特征,是认识南海北部陆缘构造属性的关键。探讨了南海三叉裂谷张裂模式,初步认为南海第1次扩张具有非火山型被动陆缘性质,第2次扩张具有火山型陆缘性质。  相似文献   

9.
南海北部新生代的构造运动特征   总被引:7,自引:3,他引:4  
新生代以来,南海北部陆架陆坡区及其邻区的地壳构造运动是在统一的区域构造应力场和总体区域性张裂沉降背景之下发生的,构造运动具有多旋回振荡式发生的特点,并贯穿了晚白垩世末之后的整个新生代.它的发生与太平洋板块的构造运动密切相关,这是由于太平洋板块之下的软流层流动方向和强度的振荡式改变而引发的.  相似文献   

10.
南海的天然气水合物矿藏   总被引:62,自引:1,他引:61  
讨论了南海的地形地貌特征,以及中新生代的构造运动历程,认识到中中新世之前,这里经历了一系列的构造运动,但在中国新世之中,这里无构造运动,只是发生区域沉降,由此认为南海应有丰富的天然气水合物矿藏,进而估算了南海天然气水合物的总资源达643.5亿一772.2亿t油当量。  相似文献   

11.
The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, 50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 105–106 yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.  相似文献   

12.
南海中北部中新世陆坡凹陷沉积充填与古陆坡形态演变   总被引:3,自引:0,他引:3  
对中德合作“南海地球科学联合研究”和“中国边缘海的形成演化及重大资源的关键问题”的有关航次获得的地震资料进行层序地层和沉积相解释,并结合前人的研究成果,对南海中北部陆坡凹陷的构造和沉积特征进行了研究.研究结果表明,南海中北部陆坡区凹陷的构造演化经历了裂陷期、裂陷-坳陷过渡期和坳陷期三个阶段,沉积环境经历了河流-湖泊、浅海和深海的演化过程,不同演化阶段形成不同的地形形态.南海中北部地形演变可分为三个阶段,即早第三纪、早中新世-中中新世中期和中中新世中期-现在,其中早中新世中期-中中新世中期的沉积充填使陆坡形态发生了重要的转变,这次转变基本上奠定了现代意义上的陆架-陆坡-海盆的格局.  相似文献   

13.
琼东南盆地陆坡区深水浊积水道的地震相特征   总被引:1,自引:0,他引:1  
水道-天然堤体系作为油气储集圈闭日益引起沉积学家和勘探家的重视。地震相特征是识别深水水道的有效途径,本文基于高分辨率2D、3D地震资料的地震相分析,在琼东南盆地陆坡区深水盆地中识别出早中新世、上新世和第四纪多期深水水道体系。早中新世深水水道在地震剖面上具有强、弱振幅交替反射和相互叠置的地震反射特征,局部具有杂乱反射特点;上新世水道整体表现为强振幅,横向上连续或者半连续,纵向上为强振幅的叠加;第四纪水道在地震剖面上具有典型下切反射特点,该水道整体振幅相对较弱,但其水道轴部充填具有典型的强反射特征,这与世界典型地区的水道轴部粗粒充填强振反射一致。这几期深水水道都发育于低水位时期,为上部物源搬运引起的浊流事件而形成。  相似文献   

14.
前处理步骤与方法对风成红粘土粒度测量的影响   总被引:38,自引:1,他引:37  
中国北方晚第三纪红粘土堆积为研究古气候与古环境提供了很好的地质记录,其粒度测量作为一个重要的代用指标被广泛应用。粒度测量结果受到前处理方法的影响,但是,现在各个实验室的前处理方法还不一致,这就为粒度数据分析和古气候古环境解释带来了困难。在黄土高原从北到南选择了3个具有代表性的红粘土剖面,对每个剖面从下向上取10块样品总计得到30块样品,对每个样品用不同的前处理方法与步骤(包括化学分离石英的方法)处理后用激光粒度仪进行颗粒测量。结果表明,前处理方法与步骤可以使同一个样品粒度参数发生几倍甚至于二十几倍的变化。综合理论和经验分析,推荐了一种较好的进行风尘堆积粒度测量的前处理方法(正文中方法C)。化学分离的纯石英的粒度分布比本文推荐的方法处理同一个样品的粒度结果偏粗,表明在提纯石英的过程中较细的不稳定矿物已经被剔除。  相似文献   

15.
16.
This study focuses on the interpretation of stratigraphic sequences through the integration of biostratigraphic, well log and 3D seismic data. Sequence analysis is used to identify significant surfaces, systems tracts, and sequences for the Miocene succession.The depositional systems in this area are dominantly represented by submarine fans deposited on the slope and the basin floor. The main depositional elements that characterize these depositional settings are channel systems (channel-fills, channel-levee systems), frontal splays, frontal splay complexes, lobes of debrites and mass-transport complexes.Five genetic sequences were identified and eleven stratigraphic surfaces interpreted and correlated through the study area. The Oligocene-lower Miocene, lower Miocene and middle Miocene sequences were deposited in bathyal water depths, whereas the upper Miocene sequences (Tortonian and Messinian) were deposited in bathyal and outer neritic water depths. The bulk of the Miocene succession, from the older to younger deposits consists of mass-transport deposits (Oligocene-lower Miocene); mass transport deposits and turbidite deposits (lower Miocene); debrite deposits and turbidite deposits (middle Miocene); and debrite deposits, turbidite deposits and pelagic and hemipelagic sediments (upper Miocene). Cycles of sedimentation are delineated by regionally extensive maximum flooding surfaces within condensed sections of hemipelagic mudstone which represent starved basin floors. These condensed sections are markers for regional correlation, and the maximum flooding surfaces, which they include, are the key surfaces for the construction of the Miocene stratigraphic framework. The falling-stage system tract forms the bulk of the Miocene sequences. Individual sequence geometry and thickness were controlled largely by salt evacuation and large-scale sedimentation patterns. For the upper Miocene, the older sequence (Tortonian) includes sandy deposits, whereas the overlying younger sequence (Messinian) includes sandy facies at the base and muddy facies at the top; this trend reflects the change from slope to shelf settings.  相似文献   

17.
INTRODUCTIONTheOkinawaTrough (OT) ,locatednorthwestoftheRyukyuTrenchandtheRyukyugunto ,eastoftheEastChinaSeashelf,isaback arcbasinbulgedtotheRyukyuTrench .TheOTextendsfromKyushuinthesouthwestofJapantotheIlanPlaininthenortheasternTaiwan ,Chinainthesouthwest…  相似文献   

18.
Using recently gathered onland structural and 2D/3D offshore seismic data in south and central Palawan (Philippines), this paper presents a new perspective in unraveling the Cenozoic tectonic history of the southeastern margin of the South China Sea. South and central Palawan are dominated by Mesozoic ophiolites (Palawan Ophiolite), distinct from the primarily continental composition of the north. These ophiolites are emplaced over syn-rift Eocene turbidites (Panas Formation) along thrust structures best preserved in the ophiolite–turbidite contact as well as within the ophiolites. Thrusting is sealed by Early Miocene (∼20 Ma) sediments of the Pagasa Formation (Isugod Formation onland), constraining the younger limit of ophiolite emplacement at end Late Oligocene (∼23 Ma). The onset of ophiolite emplacement at end Eocene is constrained by thrust-related metamorphism of the Eocene turbidites, and post-emplacement underthrusting of Late Oligocene – Early Miocene Nido Limestone. This carbonate underthrusting at end Early Miocene (∼16 Ma) is marked by the deformation of a seismic unit corresponding to the earliest members of the Early – Middle Miocene Pagasa Formation. Within this formation, a tectonic wedge was built within Middle Miocene (from ∼16 Ma to ∼12 Ma), forming a thrust-fold belt called the Pagasa Wedge. Wedge deformation is truncated by the regionally-observed Middle Miocene Unconformity (MMU ∼12 Ma). A localized, post-kinematic extension affects thrust-fold structures, the MMU, and Late Miocene to Early Pliocene carbonates (e.g. Tabon Limestone). This structural set-up suggests a continuous convergent regime affecting the southeastern margin of the South China Sea between end Eocene to end Middle Miocene. The ensuing structures including juxtaposed carbonates, turbidites and shallow marine clastics within thrust-fold belts have become ideal environments for hydrocarbon generation and accumulation. Best developed in the Northwest Borneo Trough area, the intensity of thrust-fold deformation decreases towards the northeast into offshore southwest Palawan.  相似文献   

19.
Reconnaissance seismic shot in 1971/72 showed a number of well defined seismic anomalies within the East Sengkang Basin which were interpreted as buried reefs. Subsequent fieldwork revealed that Upper Miocene reefs outcropped along the southern margin of the basin. A drilling programme in 1975 and 1976 proved the presence of shallow, gas-bearing, Upper Miocene reefs in the northern part of the basin. Seismic acquisition and drilling during 1981 confirmed the economic significance of these discoveries, with four separate accumulations containing about 750 × 109 cubic feet of dry gas in place at an average depth of 700 m. Kampung Baru is the largest field and contains over half the total, both reservoir quality and gas deliverability are excellent. Deposition in the East Sengkang Basin probably started during the Early Miocene. A sequence of Lower Miocene mudstones and limestones unconformably overlies acoustic basement which consists of Eocene volcanics. During the tectonically active Middle Miocene, deposition was interrupted by two periods of deformation and erosion. Carbonate deposition became established in the Late Miocene with widespread development of platform limestones throughout the East Sengkang Basin. Thick pinnacle reef complexes developed in the areas where reef growth could keep pace with the relative rise in sea level. Most reef growth ceased at the end of the Miocene and subsequent renewed clastic sedimentation covered the irregular limestone surface. Late Pliocene regression culminated in the Holocene with erosion. The Walanae fault zone, part of a major regional sinistral strike-slip system, separates the East and West Sengkang Basins. Both normal and reverse faulting are inferred from seismic data and post Late Pliocene reverse faulting is seen in outcrop.  相似文献   

20.
In recent years, exploration of the Lower Congo Basin in Angola has focused on the Neogene turbidite sand play of the Malembo Formation. Gravity tectonics has played an important role during deposition of the Malembo Formation and has imparted a well-documented structural style to the post-rift sediments. An oceanward transition from thin-skinned extension through mobile salt and eventually to thin-skinned compressional structures characterises the post-rift sediments. There has been little discussion, however, regarding the influence of these structures on the deposition of the Malembo Formation turbidite sands. Block 4 lies at the southern margin of the Lower Congo Basin and is dominated by the thin-skinned extensional structural style. Using a multidisciplinary approach we trace the post-rift structural and stratigraphic evolution of this block to study the structural controls on Neogene turbidite sand deposition.In the Lower Congo Basin the transition from terrestrial rift basin to fully marine passive margin is recorded by late Aptian evaporites of the Loeme Formation. Extension of the overlying post-rift sequences has occurred where the Loeme Formation has been utilised as a detachment surface for extensional faults. Since the late Cretaceous, the passive margin sediments have moved down-slope on the Loeme detachment. This history of gravity-driven extension is recorded in the post-rift sediments of Block 4. Extension commenced in the Albian in the east of the block and migrated westwards with time. In the west, the extension occurred mainly in the Miocene and generated allochthonous fault blocks or “rafts”, separated by deep grabens. The Miocene extension occurred in two main phases with contrasting slip vectors; in the early Miocene the extension vector was to the west, switching to southwest-directed extension in the late Miocene. Early Miocene faults and half-grabens trend north–south whereas late Miocene structures trend northwest–southeast. The contrast in slip vectors between these two phases emphasises the differences in driving mechanisms: the early Miocene faulting was driven by basinward tilting of the passive margin, but gravity loading due to sedimentary progradation is considered the main driver for the late Miocene extension. The geological evolution of the late Miocene grabens is consistent with southwest-directed extension due to southwest progradation of the Congo fan.High-resolution biostratigraphic data identifies the turbidite sands in Block 4 as early Miocene (17.5–15.5 Ma) and late Miocene (10.5–5.5 Ma) in age. Deposition of these sands occurred during the two main phases of gravity-driven extension. Conditions of low sedimentation rates relative to high fault displacement rates were prevalent in the early Miocene. Seafloor depressions were generated in the hangingwalls of the main extensional faults, ultimately leading to capture of the turbidity currents. Lower Miocene turbidite sand bodies therefore trend north–south, parallel to the active faults. Cross-faults and relay ramps created local topographic highs capable of deflecting turbidite flows within the half grabens. Flow-stripping of turbidity currents across these features caused preferential deposition of sands across, and adjacent to, the highs. Turbidite sands deposited in the early part of the late Miocene were influenced by both the old north–south fault trends and by the new northwest–southeast fault trends. By latest Miocene times turbidite channels crosscut the active northwest–southeast-trending faults. These latest Miocene faults had limited potential to capture turbidity currents because the associated hangingwall grabens were rapidly filled as pro-delta sediments of the Congo fan prograded across the area from the northeast.  相似文献   

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