Regional tectonic framework,structure and evolution of the western marginal basins of India

The Kutch-Saurashtra, Cambay and Narmada basins are pericontinental rift basins in the western margin of the Indian craton. These basins were formed by rifting along Precambrian tectonic trends. Interplay of three major Precambrian tectonic trends of western India, Dharwar (NNW-SSE), Aravalli-Delhi (NE-SW) and Satpura (ENE-WSW), controlled the tectonic style of the basins. The geological history of the basins indicates that these basins were formed by sequential reactivation of primordial faults. The Kutch basin opened up first in the Early Jurassic (rifting was initiated in Late Triassic) along the Delhi trend followed by the Cambay basin in the Early Cretaceous along the Dharwar trend and the Narmada basin in Late Cretaceous time along the Satpura trend. The evolution of the basins took place in four stages. These stages are synchronous with the important events in the evolution of the Indian sub-continent—its breakup from Gondwanaland in the Late Triassic-Early Jurassic, its northward drifting during the Jurassic-Cretaceous and collision with the Asian continent in the Early Tertiary. The most important tectonic events occurred in Late Cretaceous time. The present style of the continental margins of India evolved during Early Tertiary time.The Saurashtra arch, the extension of the Aravalli Range across the western continental shelf, subsided along the eastern margin fault of the Cambay basin during the Early Cretaceous. It formed an extensive depositional platform continuous with the Kutch shelf, for the accumulation of thick deltaic sediments. A part of the Saurashtra arch was uplifted as a horst during the main tectonic phase in the Late Cretaceous.The present high thermal regime of the Cambay-Bombay High region is suggestive of a renewed rifting phase.     

Influence of the Neotethys rifting on the development of the Dampier Sub-basin (North West Shelf of Australia), highlighted by subsidence modelling

During the Late Palaeozoic and the Mesozoic, the development and evolution of the North West Shelf of Australia have been mostly driven by rifting phases associated with the break-up of Gondwana. These extensional episodes, which culminated in the opening of the Neotethys Ocean during the Permo-Carboniferous and a series of abyssal plains during the Jurassic-Cretaceous, are characterised by different stress regimes and modes of extension, and therefore had distinctive effects on the margin, and particularly on the Northern Carnarvon Basin.Interpretation of 3D and 2D seismic data enables a structural and stratigraphic analysis of the Late Palaeozoic sediments deposited in the proximal part of the Dampier Sub-basin (Mermaid Nose). Based on their seismic characters, stratigraphic relationship, internal patterns, lateral continuity, and architecture, these units are associated here with the Pennsylvanian?–Early Sakmarian glaciogenic Lyons Group and the Sakmarian–Artinskian Callytharra Formation. The former were deposited in a half-graben whose development is associated with the onset of the Neotethys rifting, and the latter is characterised by restricted deposition, inversion of prograding patterns, and uplift.The integration of seismo-stratigraphic characterisation of the Late Palaeozoic sequences and Mesozoic data from one exploration well (Roebuck-1) enables the construction of subsidence curves for the Mermaid Nose and the interpretation of its geohistory.The tectonic subsidence curves show a striking Permo-Carboniferous rifting phase related to the Neotethys rifting and a discrete Late Jurassic–Early Cretaceous event coeval with the opening and the spreading of the Argo Abyssal Plain.This result points out the predominance of the effects of the Permo-Carboniferous Neotethys episode, whereas the extension related to the Argo Abyssal Plain rifting that occurred later and closer to the studied area, had only limited effects on the subsidence of the proximal Dampier Sub-basin. Therefore, it supports a tectonic model with two distinct modes of extension for the Late Palaeozoic (widespread) and the Mesozoic (localised) rifting phases.     

松辽盆地裂谷期前火山岩与裂谷盆地关系及动力学过程

松辽盆地存在裂谷期前火山岩,之后上地壳脆性伸展发育半地堑裂谷盆地。裂谷期前火山岩近水平展布于基底之上,裂谷期,沉则分布于半地暂内,两者属于不同构造层。     

Style of active intraplate deformation from gravity and seismicity data: the Baikal Rift, Asia

To better understand how active deformation localizes within a continental plate in response to extensional and transtensional tectonics, a combined analysis of high-quality gravity (Bouguer anomaly) and seismicity data is presented consisting of about 35000 earthquakes recorded in the Baikal Rift Zone. This approach allows imaging of deformation patterns from the surface down to the Moho. A comparison is made with heat flow variations in order to assess the importance of lithospheric rheology in the style of extensional deformation. Three different rift sectors can be identified. The southwestern rift sector is characterized by strong gravity and topography contrasts marked by two major crustal faults and diffuse seismicity. Heat flow shows locally elevated values, correlated with recent volcanism and negative seismic P-velocity anomalies. Based on earthquake fault plane solutions and on previous stress field inversions, it is proposed that strain decoupling may occur in this area in response to wrench-compressional stress regime imposed by the India–Asia collision. The central sector is characterized by two major seismic belts; the southernmost one corresponds to a single, steeply dipping fault accommodating oblique extension; in the centre of lake Baikal, a second seismic belt is associated with several dip-slip faults and subcrustal thinning at the rift axis in response to orthogonal extension. The northern rift sector is characterized by a wide, low Bouguer anomaly which corresponds to a broad, high topographic dome and seismic belts and swarms. This topography can be explained by lithospheric buoyancy forces possibly linked to anomalous upper mantle. At a more detailed scale, no clear correlation appears between the surficial fault pattern and the gravity signal. As in other continental rifts, it appears that the lithospheric rheology influences extensional basins morphology. However, in the Baikal rift, the inherited structural fabric combined with stress field variations results in oblique rifting tectonics which seem to control the geometry of southern and northeastern rift basins.     

The Baikal rift zone: the effect of mantle plumes on older structure

The main chain of SW–NE-striking Cenozoic half-grabens of the Baikal rift zone (BRZ) follows the frontal parts of Early Paleozoic thrusts, which have northwestern and northern vergency. Most of the large rift half-grabens are bounded by normal faults at the northwestern and northern sides. We suggest that the rift basins were formed as a result of transformation of ancient thrusts into normal listric faults during Cenozoic extension.Seismic velocities in the uppermost mantle beneath the whole rift zone are less than those in the mantle beneath the platform. This suggests thinning of the lithosphere under the rift zone by asthenosphere upwarp. The geometry of this upwarp and the southeastward spread of its material control the crustal extension in the rift zone. This NW–SE extension cannot be blocked by SW–NE compression generated by pressure from the Indian lithospheric block against Central Asia.The geochemical and isotopic data from Late Cenozoic volcanics suggest that the hot material in the asthenospheric upwarp is probably provided by mantle plumes. To distinguish and locate these plumes, we use regional isostatic gravity anomalies, calculated under the assumption that topography is only partially compensated by Moho depth variations. Variations of the lithosphere–asthenosphere discontinuity depth play a significant role in isostatic compensation. We construct three-dimensional gravity models of the plume tails. The results of this analysis of the gravity field are in agreement with the seismic data: the group velocities of long-period Rayleigh waves are reduced in the areas where most of the recognized plumes are located, and azimuthal seismic anisotropy shows that these plumes influence the flow directions in the mantle above their tails.The Baikal rift formation, like the Kenya, Rio Grande, and Rhine continental rifts [Achauer, U., Granet, M., 1997. Complexity of continental rifts as revealed by seismic tomography and gravity modeling. In: Jacob, A.W.B., Delvaux, D., Khan, M.A. (Eds.), Lithosphere Structure, Evolution and Sedimentation in Continental Rifts. Proceedings of the IGCP 400 Meeting, Dublin, March 20–22, 1997. Institute of Advanced Studies, Dublin, pp. 161–171], is controlled by the three following factors: (i) mantle plumes, (ii) older (prerift) linear lithosphere structures favorably positioned relative to the plumes, and (iii) favorable orientation of the far-field forces.     

Late Mesozoic and Cenozoic rifting and its dynamic setting in Eastern China and adjacent areas

During the Late Mesozoic and Cenozoic, extension was widespread in Eastern China and adjacent areas. The first rifting stage spanned in the Late Jurassic–Early Cretaceous times and covered an area of more than 2 million km² of NE Asia from the Lake Baikal to the Sikhot-Alin in EW direction and from the Mongol–Okhotsk fold belt to North China in NS direction. This rifting was characterized by intracontinental rifts, volcanic eruptions and transform extension along large-scale strike–slip faults. Based on the magmatic activity, filling sequence of basins, tectonic framework and subsidence analysis of basins, the evolution of this area can be divided into three main developmental phases. The first phase, calc-alkaline volcanics erupted intensely along NNE-trending faults, forming Daxing'anling volcanic belt, NE China. The second phase, Basin and Range type fault basin system bearing coal and oil developed in NE Asia. During the third phase, which was marked by the change from synrifting to thermal subsidence, very thick postrift deposits developed in the Songliao basin (the largest oil basin in NE China).Following uplift and denudation, caused by compressional tectonism in the near end of Cretaceous, a Paleogene rifting stage produced widespread continental rift systems and continental margin basins in Eastern China. These rifted basins were usually filled with several kilometers of alluvial and lacustrine deposits and contain a large amount of fossil fuel resources. Integrated research in most of these rifting basins has shown that the basins are characterized by rapid subsidence, relative high paleo-geothermal history and thinned crust. It is now accepted that the formation of most of these basins was related to a lithospheric extensional regime or dextral transtensional regime. During Neogene time, early Tertiary basins in Eastern China entered a postrifting phase, forming regional downwarping. Basin fills formed in a thermal subsidence period onlapped the fault basin margins and were deposited in a broad downwarped lacustrine depression. At the same time, within plate rifting of the Lake Baikal and Shanxi graben climaxed and spreading of the Japan Sea and South China Sea occurred. Quaternary rifting was marked by basalt eruption and accelerated subsidence in the area of Tertiary rifting. The Okinawa Trough is an active rift involving back-arc extension.Continental rifting and marginal sea opening were clearly developed in various kind of tectonic settings. Three rifting styles, intracontinental rifting within fold belt, intracontinental rifting within craton and continental marginal rifting and spreading, are distinguished on the basis of nature of the basin basement, tectonic location of rifting and relations to large strike–slip faults.Changes of convergence rates of India–Eurasia and Pacific–Eurasia may have caused NW–SE-trending extensional stress field dominating the rifting. Asthenospheric upwelling may have well assisted the rifting process. In this paper, a combination model of interactions between plates and deep process of lithosphere has been proposed to explain the rifting process in East China and adjacent areas.The research on the Late Mesozoic and Cenozoic extensional tectonics of East China and adjacent areas is important because of its utility as an indicator of the dynamic setting and deformational mechanisms involved in stretching Lithosphere. The research also benefits the exploration and development of mineral and energy resources in this area.     

Structural characteristics of the Suez rift margins

Field study of the Hadahid Block (the eastern margin of the central half-graben of the Suez rift) indicates two listric normal faults at its eastern and western boundaries, the rift-bounding fault and the Hadahid Fault, respectively. These faults were affected by two episodes of movement. The earlier movement (at the initial, Neogene rift opening) led to equal displacements on the two faults whereas the later movement (at the mid-Clysmic event, l7 Ma ago) caused the Hadahid Fault to bound the deep part of the central half-graben. A similar conclusion is also reached for the western margin of the southern half-graben of the rift (Esh El Mellaha and Zeit Blocks). The two listric faults bounding the margin blocks in these two oppositely tilted half-grabens (Hadahid and Esh El Mellaha Blocks) join at depth into a ramp-flat detachment. This geometry of the rift-bounding faults represents an intermediate stage in the evolution of rift basins. It is preceded by the early rifting stage where extension is less and oppositely tilted half-grabens are formed (e.g. the ancestral Red Sea-Gulf of Suez rift). Increased extension at later stages leads to the prevailance of one system of detachment instead of oppositely dipping detachments of adjacent half-grabens. The central and southern Red Sea have perhaps had this geometry before the onset of seafloor spreading.     

松辽盆地形成、发展与岩石圈动力学

根据区域构造环境、深部构造机制、火山活动的时间序列以及盆地几何学、运动学特征,分析了松辽盆地形成与发展的岩石圈动力学问题。提出古太平洋板块向欧亚大陆下俯冲引起热流上升,由此导致裂谷期前火山作用和岩石圈热与机械减薄,裂谷期上地壳伸展发育成裂谷盆地,火山活动减弱。随着陆缘陆块拼贴,俯冲带长距离后退,处于热异常的岩石圈开始向热平衡转化,盆地由伸展转化为坳陷。     

酒东盆地营尔凹陷早白垩世断陷形成机制探讨

位于青藏高原和华北板块两大构造带交汇处的河西走廊带中西段酒东盆地,早白垩世为典型断陷盆地,但对其断陷形成机制存在明显争议.因早白垩世两大构造带的主体构造作用明显差异:北—南向挤压和北西—南东向伸展,为深入了解哪一种作用是控制早白垩世酒东盆地形成的主要因素,本研究特选取远离新生代强烈活动的阿尔金断裂带,在河西走廊带中西段...     

似新华夏式伸展盆海系的基本特征及其形成演化的力学机制

晚中生代(白垩纪)以来,中国东部及西太平洋大陆边缘发育一系列NNE、NE乃至NEE向(与纬向构造联合)的巨型右行张扭性断陷(地堑、半地堑)在平面上组成平行雁列的多字型构造,其深部发育同走向的上地幔隆起和基底拆离,地表常出现变质核杂岩和大型低缓倾角的伸展剥离断层,它主要是东亚及西太平洋大陆边缘陆缘扩张的产物,其地球动力学过程为晚燕山期以来的后造山期的大陆隆升和水平侧向伸展以及晚白垩世末一早第三纪、45Ma以来的印度板块与欧亚板块碰撞所产生的碰撞效应。      

东海盆地中、新生代盆架结构与构造演化

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。     

珠江口盆地珠一坳陷新生代盆地结构与成因演化

运用丰富的三维地震资料,在断裂体系的静态描述基础上,通过断层活动速率计算和平衡剖面分析,并结合残留地 层展布特征,恢复了新生代盆地垂向演化与叠合过程,探讨盆地发育与转型的动力学机制。珠一坳陷新生代经历了裂陷早 期、裂陷晚期、裂后拗陷和构造活动期四大演化阶段。裂陷期（E2w-E2e）,印支地块旋转挤出和古南海俯冲,区域拉张应 力场由NW 向顺时针转变为近SN 向,导致了裂陷早期NE、NEE 向断裂控盆向裂陷晚期近EW 向、NWW 向断裂控盆转变, 岩石圈伸展作用由宽裂谷方式向窄裂谷方式转变,导致盆地格局由彼此孤立的半地堑或窄地堑系趋于相互扩展连通;裂后 拗陷期（E3z-N1z-N1h）,岩石圈伸展中心迁移至南海扩张中心,南海北部地区整体处于裂后热沉降阶段,构造活动微弱;构 造活化期（N1y-N2w-Q）,菲律宾海板块NWW 向仰冲-碰撞联合作用下产生NNE 向拉张,同时派生近EW 向和NW 向的共 轭剪切作用,导致了先存NWW 向和近EW 断裂的活化,以及隆起区NWW 向张性断裂和近EW 向、NW 向走滑断裂带的形 成。该研究所揭示的盆地发育演化过程不仅对该区油气勘探提供指导,也对被动大陆边缘演化的研究有着一定的借鉴意义。     

Mechanism of rifting and some features of the deep-seated structure of the Baikal rift zone

The mechanism of rifting in the Baikal rift zone is a complex process, with stages of crustal fracturing alternating with stages of plastic extension. Data on the form and size of the anomalous mantle region lying below the rift zone is given in the present work. Divergent flow in the upper part of the anomalous mantle is considered the cause of extension of the crust in this region.     

Tectonics,stress state,and geodynamics of the Mesozoic and Cenozoic Rift basins in the Baikal region

The results of geological, structural, tectonic, and geoelectric studies of the dry basins in the Baikal Rift Zone and western Transbaikalia, combined under the term Baikal region, are integrated. Deformations of the Cenozoic sediments related to pulsing and creeping tectonic processes are classified. The efficiency of mapping of the fault-block structure of the territories overlapped by loose and poorly cemented sediments is shown. The faults mapped at the ground surface within the basins are correlated with the deep structure of the sedimentary fill and the surface of the crystalline basement, where they are expressed in warping and zones of low electric resistance. It is established that the kinematics of the faults actively developing in the Late Cenozoic testifies to the relatively stable regional stress field during the Late Pliocene and Quaternary over the entire Baikal region, where the NW-SE-trending extension was predominant. At the local level, the stress field of the uppermost Earth’s crust is mosaic and controlled by variable orientation of the principal stress axes with the prevalence of extension. The integrated tectonophysical model of the Mesozoic and Cenozoic rift basin is primarily characterized by the occurrence of mountain thresholds, asymmetric morphostructure, and block-fault structure of the sedimentary beds and upper part of the crystalline basement. The geological evolution of the Baikal region from the Jurassic to Recent is determined by alternation of long (20–115 Ma) epochs of extension and relatively short (5.3–3.0 Ma) stages of compression. The basins of the Baikal Rift System and western Transbaikalia are derivatives of the same geodynamic processes.     

裂陷盆地初始阶段构造—沉积协同机制

裂陷盆地蕴含丰富的油气资源,盆地不同演化阶段发育独特的地层结构样式及其砂体成因类型,形成各具特色的油气藏系统。近年来湖盆初始裂陷层系不断获得油气勘探突破,使之成为石油工业界重要关注对象,其多级次断裂演化、组合关系、地貌特征及其与水系和沉积响应关系已成为当前地质学领域关注的热点科学问题。蒙古塔南凹陷下白垩统铜钵庙组良好记录了一套初始裂陷沉积序列,丰富的钻井及地震资料使之可作为理想的研究对象。综合利用地震、岩心及测录井资料,在构造—沉积学理论指导下重建了塔南凹陷初始裂陷构造—沉积演化及源—汇响应模式。研究表明,塔南凹陷初始裂陷第一阶段以新生的分割型小洼陷群为特征,与前裂陷阶段“高山深谷”地貌背景联控下形成短距离输送且数量众多的小型扇群;初始裂陷第二阶段伴随控洼断层长度的迅速增加发生软联结,形成连通且宽浅的盆地结构,发育多套低坡降构造转换带（面积大于50 km2）和西北侧缓坡带（延伸约28 km）供给型大套扇三角洲体系,长轴及陡坡方向水系运输距离较短。实例解析结合调研结果表明,先存水系和盆地地貌结构联合控制初始裂陷盆地源—汇系统,进而形成初始裂陷第一阶段盆地满盆富砂（沟通先存水系）或欠补偿（不沟通先存水系）,年轻短程水系主导的孤立小湖盆群则主要发育小规模近源碎屑沉积物;初始裂陷第二阶段源—汇系统则与该时期断裂体系联结方式有关:断裂晚期联结型湖盆主要发育以短程断崖或小型转换带水系为特征,而断裂早期联结型湖盆形成大型构造转换带水系及三角洲体系,其缓坡带长度亦快速增大,盆地整体具有“富砂”特征。本研究为其他裂陷盆地寻找大型优质砂体提供了科学理论依据。     

非洲地区盆地演化与油气分布

非洲地区盆地整体勘探程度较低,待发现资源量大,是当前油气勘探开发的热点地区之一。非洲板块在显生宙主要经历了冈瓦纳大陆形成、整体运动和裂解3个构造演化阶段,形成多种不同类型的盆地。通过板块构造演化和原型盆地研究及石油地质综合分析,明确了不同类型盆地的构造特征与油气富集规律。北非克拉通边缘盆地形成于古生代早期,受海西运动影响,油气主要富集在挤压背景下形成的大型穹隆构造之中,以古生界含油气系统为主;北非边缘裂谷盆地海西运动之后普遍经历了裂谷和沉降,裂谷期各盆地沉降幅度和沉降中心的差异导致了油气成藏模式和资源潜力的差异;东、西非被动陆缘盆地形成于中生代潘吉亚大陆的解体、大西洋和印度洋张裂的过程中,西非被动陆缘盆地普遍发育含盐地层,形成盐上和盐下两套含油气系统,东非被动陆缘盆地结构差异较大,油气分布主要受盆地结构控制;中西非裂谷系是经历早白垩世、晚白垩世和古近纪3期裂谷作用而形成的陆内裂谷盆地,受晚白垩世非洲板块与欧亚板块碰撞的影响,近东西向展布盆地抬升剧烈,油气主要富集在下白垩统,北西南东向盆地受影响较弱,油气主要富集在上白垩统和古近系之中;新生代东非裂谷系盆地和红海盆地形成时间相对较晚,以新生界含油气系统为主,新生代三角洲盆地中油气分布主要受三角洲砂(扇)体展布和盆地结构所控制。     

http://www.sciencedirect.com/science/article/pii/S1674987111000491

Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin, South China Sea, stratigraphic sequences, deformation characteristics and an extension model for this sub-basin have been worked out. Three tectonic-stratigraphic units are determined. Detailed analyses of extension show that the event occurred mainly during the Paleogene and resulted in the formation of half-grabens or grabens distributed symmetrically around the spreading center. Sediments are characterized by chaotic and discontinuous reflectors, indicating clastic sediments. Farther to the southwest, the sub-basin features mainly continental rifting instead of sea-floor spreading. The rifting would have been controlled by the shape of the massif and developed just along the northern edge of the Zhongsha-Xisha Block, rather than joined the Xisha Trough. After 25 Ma, a southward ridge jump triggered the opening of the Southwest Sub-basin. The NW-directed stress caused by the sea-floor spreading of the Northwest Sub-basin may have prevented the continuous opening of the sub-basin. After that the Northwest Sub-basin experienced thermal cooling and exhibited broad subsidence. The deep crustal structure shown by the velocity model from a wide-angle seismic profile is also symmetrical around the spreading center, which indicates that the Northwest Sub-basin might have opened in a pure shear model.     

Cenozoic lithogenesis in the Baikal rift zone

New data on the geological history and Cenozoic lithogenesis in depressions of the Baikal rift zone are considered with areas adjacent to Lake Baikal as example. In this region, rifting developed during the plain (Late Oligocene?Early Pliocene) and orogenic (Late Pliocene?Holocene) stages and was accompanied by the accumulation of plain coaliferous fan and orogenic molasses formations, respectively. The examination of Quaternary sequences in the Baikal region reveals that deposition and postsedimentary transformations of riftogenic sediments were intensely influenced by deep-seated water sources of the so far undivided stratal?infiltration, elision, and exfiltration types, according to the classification in (Kislyakov and Shchetochkin, 2000). Deep processes in this region determined the elevated heat flow, volcanism, and extensive discharge of hydrothermal solutions and gas fluids. In our opinion, gaseous?hydrothermal activity stimulated the formation of hydrothermal?sedimentary rocks (dolomitic and calcitic travertines, geyserites, aluminosulfates), the accumulation of diatomaceous and carbonaceous oozes in Baikal, and the formation of a large methane gas hydrate deposit.     

东地中海原型盆地演化

东地中海经历了伸展-聚敛的构造演化旋回,聚集了丰富的油气资源。基于2D地震、ODP Leg160、IHS及Tellus商业数据库和公开发表的文献资料,本文在建立东地中海及周缘构造-地层格架的基础上,恢复了东地中海12个关键地质历史时期的原型盆地,并以板块构造为切入点探讨了盆地演化机制。东地中海及周缘上三叠统以来地层可划分为新特提斯被动大陆边缘陆地及浅水区、新特提斯被动大陆边缘深水区和塞浦路斯弧前褶皱区3个地层分区,前两个地层分区均发育一套裂谷-被动大陆边缘层系,但是二者的岩相特征和不整合发育有明显的差异,而塞浦路斯弧前褶皱区发育一套大洋盆地-弧前盆地层系。研究认为东地中海经历了二叠纪—早侏罗世裂解期、中侏罗世巴柔期—晚白垩世土伦期漂移期和晚白垩世森诺期以来的汇聚改造期3个原型阶段,其中汇聚改造期又可细分为晚白垩世森诺期“双俯冲带”消减期、古近纪北部俯冲-碰撞期、中新世塞浦路斯岛弧带南侧俯冲-碰撞与黎凡特边缘活化期和中新世梅西期以来“弧-山碰撞”与“走滑逃逸”期4个阶段。东地中海盆地演化受控于图哈罗德-安纳托利亚板块以及凯里尼亚、特罗多斯和埃拉托色尼等微板块与冈瓦纳大陆北缘的分离、向北的漂移和与欧亚大陆汇聚拼贴的板块构造活动。     

渤海湾盆地大歧口凹陷新生代构造演化与盆地原型

大歧口凹陷位于渤海湾盆地黄骅坳陷中北部,是中新生代叠合盆地中新生界沉积最厚的凹陷。本文基于大量二维、三维地震剖面和钻井资料,从凹陷主控断裂活动性、沉积沉降中心分布和构造格架等方面,侧重对大歧口凹陷新生代构造演化过程和原型盆地类型进行研究。认为:1)大歧口凹陷构造单元有4级,凹陷具有"东西分带、南北分块"的平面构造格局和北断南超箕状断陷的剖面结构。2)凹陷内断裂有4级,主要断裂的规模、活动期次和断裂活动具有演化的阶段性和空间的迁移性,典型构造带活动性具有由北往南迁移的特点。3)新生代期间整个大歧口凹陷的沉积沉降中心均在东部海域的歧口主凹内,但整体具有往南迁移的趋势。4)凹陷经历了拓展裂谷、拉分断陷、箕状断陷和碟状坳陷4个构造演化阶段,断陷阶段在整个构造演化时期意义重大,且具有走滑拉分特点。故认为大歧口凹陷原型盆地是一种"板内拉分盆地"。