Metamorphic buried hill reservoirs possess complex pore structures, making the evaluation of their effectiveness particularly challenging. This study explores the influence of lithology and stress conditions on fracture development in such reservoirs, aiming to improve predictions of effective storage spaces. Three representative metamorphic rocks from the Bohai Bay Basin: plagioclase amphibolite, gneissic granite, and monzogranite were subjected to mechanical testing under compressive and tensile stresses. Acoustic emission (AE) monitoring was used to track energy release and the spatiotemporal evolution of microfractures during deformation, complemented by thin-section analysis of post-failure samples to examine microfracture morphology and density. The results show that tensile stress more readily induces rock failure but typically produces narrow, localized damage zones, whereas compressive stress promotes the development of broader, more interconnected fracture networks. Under tensile loading, all three lithologies exhibit similar axial splitting behavior, with granitic rocks forming slightly wider fracture zones than amphibolite. Under compressive loading, distinct macroscopic failure modes are observed among the lithologies. Analysis of microfracture parameters and spatial distributions reveals that monzogranite exhibits extensive microfracture activity and wide fracture zones, indicating a higher potential for forming interconnected secondary porosity and making it the most favorable reservoir lithology among those tested. This study provides detailed insights into fracture evolution across different lithologies under varying stress conditions and offers experimental evidence to support improved predictions of effective reservoirs in deep metamorphic settings.

During the Mesozoic, NE Asia experienced intense tectonic and magmatic activity, including the closure of the Mongol–Okhotsk Ocean (MOO), the subduction and demise of the Mudanjiang Oceanic Plate (MOP), and the continuous westward subduction of the Paleo-Pacific Plate (PPP). The evolution of the MOP remains highly contentious, particularly regarding its final closure timing and subduction polarity, and warrants further investigation. The Heilongjiang Complex (HLC), primarily distributed within the Mudanjiang Suture Zone (MSZ), which separates the Jiamusi and Songnen blocks, preserves key geological records of the Mudanjiang Oceanic subduction and closure. By employing detailed structural analysis, zircon U-Pb dating, and tomographic imaging, we reconstruct the tectonic history of the HLC and propose its five stages of deformation since the Mesozoic. The first stage, which occurs from the Late Triassic to the Early Jurassic, is characterized by SE-dipping schistosity within the HLC. Integrating the identification of the east-dipping remnants of the oceanic lithosphere west of the MSZ by tomographic imaging suggests an eastward subduction of the MOP underneath the Jiamusi Block during the Early Mesozoic. The second stage, spanning the Early Jurassic to the Late Jurassic, is characterized by E–W-striking tight folds associated with the MOO’s SSE-ward subduction and PPP’s NNW-ward subduction. The third stage of deformation, occurring from the Late Jurassic to Early Cretaceous, features S–N-striking box folds, indicative of the final amalgamation of the Jiamusi, Songnen, and Nadanhada terranes. The fourth stage, taking place in the late Early Cretaceous, is marked by near E–W-striking thrust faults that are associated with the closure of the eastern segment of the MOO. Finally, the fifth stage, which follows the Early Cretaceous, involves nearly NE-striking thrust faults related to NW-ward subduction of the PPP.

This study investigates the influence of foliation on the mechanical behavior and fracture characteristics of transversely isotropic gneiss under tensile stress. Brazilian splitting tests were conducted on disc-shaped specimens with five anisotropy angles (β = 0°, 30°, 45°, 60°, and 90°). By integrating acoustic emission (AE), digital image correlation (DIC), and 3D laser scanning techniques, the evolution of microfractures and fracture surface characteristics was revealed. The results show that P-wave velocity increases from 3.42 km/s at β = 0° to 4.23 km/s at β = 90°, while the tensile strength decreases from 7.25 MPa to 2.93 MPa, indicating pronounced anisotropy. Three distinct failure patterns were identified: central failure (β = 0°), mixed failure (β = 30°, 45°, and 60°), and layer-activation failure (β = 90°). AE and DIC monitoring revealed that central fractures, governed by tensile stress, consistently initiated near the specimen center and propagated bilaterally, enabling reliable strength determination. In contrast, non-central fractures formed parallel to foliation planes exhibited a mixed tensile–shear mechanism and propagated inward from the specimen edges. Fracture surface roughness, characterized by relative height (RH) and the joint roughness coefficient (JRC), was found to gradually decrease with increasing β, a trend consistent with the variations in tensile strength and AE energy. These findings provide valuable insights into the tensile fracture mechanisms of gneiss controlled by anisotropy.

As an intense deformation region, the compressional overlapping areas of strike-slip faults play a crucial and significant role in influencing fault propagation, seismic activity, and the formation and distribution of hydrocarbon reservoirs. Hence, enhancing the comprehension of detailed microscopic deformation mechanisms lays the foundation for a better understanding of the macroscopic deformation, constituting the core issue of this study. Compressional en echelon fault model experiments were conducted, combining with acoustical and optical measurements to simulate fault interactions and mechanical coupling within fault systems. The experimental results manifest that three distinct episodes of derived faults were observed during the interaction of preexisting faults. Firstly, a group of derived faults extends from the ends of the overlapping area, conjugating with the pre-existing en echelon faults. Secondly, the fault consisting of a series of secondary fractures propagates from the ends of the overlapping area towards the interior, leading to a complete destruction of the overlapping area. Thirdly, another group of faults extends from the ends of the overlapping area, forming a rhombic region in conjunction with the two pre-existing faults. Furthermore, the analysis of the strike-slip rate distribution along two en echelon faults showed significant heterogeneity. Specifically, the segments with relatively low strike-slip rate were inferred to be locked zones, which are likely to act as nucleation points for future emergent deformation events. These simulation results contributed to understanding the issues such as the mechanical coupling between Garlock and San Andreas fault systems, the linkage fault development in the branching zones of the North Anatolian Fault Zone, and the kinematic intersection geometry between the Danghenan Shan and Altyn Tagh faults.

The strike-slip associated structures are a variety of structures developed at tails, bends and stepovers of strike-slip faults, among which the bend associated structure is the most common one. Its study is not only enriching for strike-slip related researches, but also important for hydrocarbon and mineral exploration. The characteristics and relevant analogue studies of associated structures forming at bends of strike-slip faults are summarized, compared and analyzed in this paper. The results indicate that strike-slip bend associated structures can be categorized into the transpressional and transtensional ones forming at restraining and releasing bends of strike-slip-dominated faults, respectively, and they show different characteristics with the change of stress regimes. Results of analogue studies show that the morphology and internal architectures of bend associated structures vary as the influential factors change, and the bend angle is the decisive factor influencing the morphology and internal architectures of bend associated structures, while the strike-slip displacement is the most important factor controlling their development and evolution. Eventually, a smaller-angle bend will form on the through-going faults above the preset bend of basement strike-slip fault. However, some results of previous analogue studies may be questionable due to the lack of discrimination of baseplate settings between strike-slip bend and stepover and irrationality of setting bend angle in those studies. Besides, further analogue studies are still needed on exploring the differences of bend associated structures formed in inhomogeneous lithologies or structures, stress regimes and so on.

The Xinchenggou area is located in the northeast part of the eastern segment of the Xingmeng orogenic belt (EXOB), NE China and has been demonstrated to be a promising exploration target for epithermal deposits. Although previous studies have shown that syenogranite and monzogranite occurring in the Xinchenggou area are promising in forming epithermal mineralization, the petrogenesis and geodynamic settings in which these granites were emplaced are still unclear. To address these problems, in this study detailed whole-rock major and trace element analyses for these granites were conducted. Combined with previously published data, we show that both syenogranite and monzogranite in the Xinchenggou area are high-K calc-alkaline and peraluminous with high SiO 2 . Their rare earth element concentrations are low (ΣREE = 72.35 × 10 −6 –217.64 × 10 −6 ) and show obvious differentiation between LREE and HREE (La N /Yb N =2.74–11.37), with apparent Eu negative anomalies (δEu = 0.14–0.83) and indistinctive Ce anomalies (δCe = 0.96–1.11). Combined with petrographical observations, it is suggested that both syenogranite and monzogranite are (slightly fractionated) I-type granite. Nb/Ta ratios of syenogranite and monzogranite range from 6.18 to 26.33, indicating that the granitic magma was derived from the upper mantle or the lower crust. Both syenogranite and monzogranite were emplaced in a continental arc setting, which was related to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate during the Late Triassic to Early Jurassic.

The Bohai Bay Basin (BBB) is a Meso-Cenozoic intracontinental petroliferous basin, where four pre-existing continental-scale fault zones intersect, in East China. The BBB has experienced complex deformational and evolutionary history that records significant information about how the lithosphere there has responded to the coeval plate interactions around the Eurasian Plate and/or their resulting deep crust-mantle processes in the Cenozoic. Now both deep and shallow deformational and evolutionary processes of the BBB have been wellstudied, but many geodynamic mechanisms previously proposed for those processes are too general to explain them well. Based on various data and principles, we first summarized both deep and shallow responses and processes of the BBB in the Cenozoic and then matched reasonable geodynamic mechanisms for each of them. The results show as follows: the Cenozoic differential reactivation of pre-existing continental-scale weak zones controlled the coeval deep-shallow differential coupling evolution of the BBB. The Paleogene extension in the BBB was mainly caused by crust-mantle processes triggered by the stagnant Izanagi slab. The Cenozoic strike-slip faulting was influenced by various plate interactions, in which the oblique subduction and anticlockwise rotation of young Pacific Plate resulted in the complex pre-Oligocene strike-slip history of the Tan-Lu Fault Zone to the south of the Zhang-Peng Fault Zone, while the India-Eurasia collision has caused the intense and synchronous strike-slip faulting of various faults there since ~35 Ma, which was then weakened by the oblique subduction and clockwise rotation of young Philippine Sea Plate in the Neogene. The compression resulting from both the India-Eurasia collision and the Philippine Sea Plate's subduction contributed to the latest Paleogene tectonic inversion in the BBB. The arrival of mantle flow triggered by both the India-Eurasia collision and the stagnant slab of the Pacific Plate resulted in the tectonic reactivation there in the late Neogene. (c) 2020 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The Mesozoic East Asian Continental Margin (EACM) is generally considered as a continental magmatic arc triggered by Paleo-Pacific Plate subduction. However, the magmatic arc was not evident for a long time. This paper tries to use the gravity and magnetic responses along the magmatic arc to deeply explore its spatio-temporal distribution. Based on the gravity and magnetic anomalies of the Mesozoic magmatic arc on the EACM and combined with the integration of previous geological and geochronological studies, it is found that the tectonic features of the magmatic arc are more obvious in the fourth-order approximation/detail gravity anomaly fields by using wavelet multi-scale analysis. Furthermore, the residual crustal gravity anomalies containing the medium-wavelength components of the complete Bouguer gravity anomalies are analyzed for the identification of the Jurassic magmatic arcs. Finally, line-drawing analysis is performed on the fourth-order detail gravity anomaly field to explore the response of the Mesozoic magmatic arcs to Paleo-Pacific subduction on the EACM. Our results support that the magmatic arcs on the EACM mainly developed in the Late Triassic-Early Cretaceous Andean Active Continental Margin and in the late Early Cretaceous-Eocene transtensional continental margin. Our study contributes to the formation and refinement of the Paleo-Pacific Plate subduction mechanism and the Mesozoic tectonic evolutionary model of the EACM, and also provides geophysical evidence for the reconstruction of dynamic processes of the EACM.

The NE China region involves a complex accretionary belt formed by multiple stages of assembly of micro-blocks from the Paleozoic to Mesozoic, the tectonics of which provides important clues on the evolution of the East Asian continental margin. With a view to evaluating the micro-block evolution in NE China, we used gravity and magnetic methods to analyze the geophysical characteristics of the micro-blocks and their boundaries. Combining with regional geology, paleomagnetism and paleontology, we reconstructed the micro-block assembly history in the eastern Central Asian Orogenic Belt. Five Paleozoic to Mesozoic micro-blocks are recognized in NE China: the Erguna, Xing'an, Songnen, Jiamusi and Nadanhada, and their boundaries show significant differences in gravity and magnetic fields. The boundary between the Erguna Block (EB) and the Xing'an Block (XB) shows as a continuous tectonic line in the gravity field, whereas the one between the XB and the Songnen Block (SB) exhibits a rather discrete but strong magnetic anomaly belt. The boundary between the SB and the Jiamusi Block (JB) is characterized by both distinct gravity and magnetic anomalies. The Nadanhada Micro-block (NMB) appears as an independent micro-block in the fourth-order detail field of the Bouguer gravity anomaly, where it shows as a short axis or circinate structure in this anomaly field. The Paleozoic to Mesozoic tectonic evolution of these micro-blocks in NE China is closely related to five sutures in the eastern Central Asian Orogenic Belt. The Xinlin-Xiguitu Suture was first formed at-500 Ma, leading to the assembly of the EB and the XB, the Heihe-Hegenshan Suture was formed at 320-290 Ma, marking the amalgamation of the XB and the SB, the Mudanjiang-Yilan Suture was formed at-200 Ma, marking the collision of the JB and the SB. The Paleo-Asian Ocean closed during 250-230 Ma in a scissor style. The subduction of the Paleo-Pacific Ocean was initiated at-200 Ma. Based on the deep structural architecture imaged from gravity and magnetic anomalies, we propose an evolutionary model of the micro-blocks in the NE China, which provides important insights into the tectonic evolution of the NE China region during the Paleozoic to Mesozoic.(c) 2020 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

The transition from complex crater to peak-ring basin is a hot topic in lunar research. There are many controversies about the formation process of the ring basin, and its formation is closely related to the central features. The data obtained from DEM can determine the volume and morphology of the central features in the complex craters more accurately. We complied a data set of 52 fresh complex craters from the Global Lunar Orbiter Laser Altimeter (LOLA) DEM, and established the Vi-D (internal volume–crater diameter) and Vcf-D (central feature volume-crater diameter) relationships for complex craters in the highlands, mare, mare-highland border, and South Pole Aitken-Basin (SPA) terrain. In general, the Vcf increases as the Vi increases, and the Vcf of the complex craters with similar Vi changes significantly. According to the morphological characteristics, the central features of complex craters can be categorized into 5 main types: the tiny-peak, the multi-peak, the single-peak, the mountain-peak, and the incomplete or complete peak-ring types. The ratio of Vcf/Vi shows the increasing trend from tiny-peak to peak-ring types. The central features of complex craters have significant differences in volume and morphology due to the different terrain conditions. The transition from complex craters to peak-ring basins is closely related to the central features and collapsed blocks. The tectonic uplift collides or thrusts with the collapsed blocks driven by the inward gravity of the instantaneous crater rim, resulting in an upward movement of materials within the transient cavity to form a peak-ring with prominent internal topography. And a larger peak-ring in the morphology and thickness may occur on the highlands due to the stronger collision and compression. We support those peak-ring formation theories that involve the collision and interaction of inwardly collapsing crater rims.

As part of the assessment and need to clarify the Mesozoic subduction-related accretion history of the East Asian Ocean-Continent Connection Zone (EAOCCZ), 27 micro-blocks were identified on the continental margin of Northeast Asia, of which 22 are related to the Paleo-Pacific Plate (PPP) subduction. Two new methodologies are proposed to fulfil this purpose, comprising the residual crustal anomaly extraction technique and the gravity line-drawing method. The residual crustal gravity anomaly fields were extracted by multi-scale moderate-wavelength gravity field separation to reveal basement structures of the EAOCCZ. Meanwhile, the linear tectonic framework of Northeast Asia is determined through a gravity line-drawing method based on the fourth-order detailed field of the complete Bouguer gravity anomaly, to identify the micro-block boundaries. As a result, the recognized micro-blocks are mainly distributed along the Mongol-Okhotsk Suture Zone, Northeast China, Russian Far East and Japan Island Arc. In addition, the Mesozoic strike-slip faults and the pull-apart basins in the Trans-Baikal are evidenced by the left-stepping horsetail-shaped structure on the magnetic lineations and the continuous gravity high on the residual crustal gravity field. The latter reveals regional crustal extension, which indicates a strong intracontinental sinistral strike-slip motion in the Early Cretaceous on the northern flank of the Mongol-Okhotsk Suture Zone. Affected by the change of motion of the Paleo-Pacific Plate in Mesozoic, the EAOCCZ experienced frontal accretion in the Jurassic and oblique accretion in the Cretaceous. The Cretaceous braided structures on the northeastern continental margins indicate at least two stages of strike-slip movements. The earlier stage is controlled by dextral strike-slip transpression of the arc slivers, from north to south, to form the oroclinal-bending structures; whereas the later stage is controlled by the sinistral strike-slip faulting, moving the Taukha Terrane from south to north. The crustal residual gravity anomaly field reveals the crustal structure of the Okhotsk Micro-plate, which shows the characteristics of a subduction-related accretionary continental margin. This accretionary margin has been located at the northern slope of the Kurile Basin, similar to the Sikhote-Alin and Kamchatka volcanic arcs, and has not yet completely collapsed. Crustal thinning has obviously occurred in the back-arc area, and some main depocenters developed in the northwest, controlled by the NNW-trending boundary faults.

渤海湾盆地是在中生代华北克拉通破坏基础上,经由新生代深埋形成的叠合盆地,遭受了多期不同性质构造叠加改造.渤海海域油气资源的勘探逐步走向深层,深部潜山油气藏成为重要的勘探目标.本文以石臼坨东428潜山构造(以下简称428构造)为例,探索渤海湾盆地潜山的形成和构造演化.基于前人对渤海湾盆地内构造和储层特征的研究成果,通过对地震剖面的精确解析,结合相干切片和其他地质资料,系统研究428构造各个阶段的变形特征,特别是对428构造的断裂特征进行了平面和剖面上的解析与断裂组合分析.结果发现:428构造东、西侧现今差异主要是由一条斜跨该构造的NEE向断裂导致的,对比邻区野外应变测量分析,识别出五期构造应力场,分别对应于印支期、燕山期和喜山期的各阶段应力场变化,并结合428构造及其周缘残留地层等方面的证据,进而认为428构造经历了中生代印支期?燕山早期逆冲、燕山中?晚期伸展、燕山末期挤压及新生代右行右阶的走滑?拉分构造叠加的多期复合构造模式.

南海北缘发育了一系列新生代陆缘盆地,从西向东可划分为北部湾盆地、琼东南盆地、珠江口盆地及台西南盆地,这些盆地记录了新生代南海北缘构造演化过程.为加深对南海北部陆缘新生代盆地断裂活动及构造演化的认识,本文以珠三坳陷阳江东凹为例,基于覆盖阳江东凹研究区的高分辨率三维地震资料,对该地区的断裂体系进行了系统解剖,阐述了古近纪断裂的展布特征,并对主干断裂的活动速率进行定量计算,探讨了断裂体系演化规律及沉积中心迁移过程,并利用2Dmove软件对典型地震剖面进行了构造演化恢复.结果表明,文昌组沉积期阳江东凹主要以NE-NEE向断裂活动为主,且活动强度大;恩平组沉积期,NWW向断裂大量发育,少数NE-NEE向断裂继续活动.阳江东凹的断裂活动表现出从早到晚,同沉积主干断裂走向由NE-NEE向转变为近E-W向和NWW向,同时沉积中心相应的整体向西、向南迁移.而单一主干断裂在不同位置不同时期,其活动强度也存在差异.基于断裂体系展布特征和平衡剖面分析,本文认为阳江东凹的基底作为中生代华南陆缘的一部分,经历了多次变形作用,形成了NE向和NWW向基底卷入型共轭断裂;早?中始新世,NE向先存断裂在NW-SE向应力作用下优先复活,其断裂活动强度达到最大;进入中?晚始新世,NE向断裂活动继承性发展,NEE向断裂大量发育,在右旋应力作用下,早期NE向断裂呈右行右阶走滑,控制着地层沉积与断裂构造样式;至渐新世,NE向断裂少数继承性活动,近E-W向及NWW向断裂大量发育,以左行走滑方式存在.因此,阳江东凹裂陷期主要经历了文三段沉积期NW-SE向伸展、文二段沉积期NE向右行右阶走滑拉分和文一段?恩平组沉积期NWW向左行左阶走滑拉分的三阶段演化过程.结合前人对南海北部陆缘研究成果可知,南海北缘盆地群宏观格局主要为受NE向断裂控制的拉分成盆,其产生的NEE向次级断裂分别控制着各坳陷内部各个凹陷的次级构造和沉积充填,晚期经历了NWW向断裂走滑叠加改造.

受南海海盆演化以及邻区构造事件的联合控制,南海北部珠江口盆地内部构造表现出明显的多期走滑特征.走滑拉分作用控制了珠江口盆地现今的构造格局,在区域地质构造研究的基础上,本文通过重磁资料,在区域内共识别出NW和NE两组走滑断层,并根据阳江东凹最新三维地震资料的精细解析,识别出花状构造、雁列式和羽状等多种具显著走滑特征的构造样式,进而研究了各期走滑构造对成盆的控制作用,分析走滑拉分盆地的沉积充填特征及对油气成藏的作用.研究结果表明:盆地走滑构造对油气成藏分布有明显的控制作用,对烃源岩热演化、构造圈闭发育以及油气运移聚集都有重要的控制作用,进而讨论了珠江口盆地走滑构造对油气的富集规律与分布的影响作用,对该盆地的勘探实践具有重要指导意义.

渤中凹陷作为渤海深层油气勘探最现实的有利区,其资源潜力和勘探前景有待得到进一步验证.由于深部潜山储层地质情况复杂,岩性繁多且差异明显,对深部有效储层类型及分布的研究是渤中地区深层勘探的关键.本文通过对渤中地区太古宇二长花岗岩、片麻状花岗岩、花岗质片麻岩、斜长角闪岩、古生界灰岩以及中生界安山岩6种潜山代表性岩石,开展张应力和压应力作用下的裂隙发育程度实验,观测在相同加载条件下不同岩性的微裂隙发育数、事件率等特征以及微裂隙时空分布,分析不同岩性样品裂缝发育能力及空间展布.实验结果表明:6种岩石储层在张应力和压应力条件下,均有一定规模的微裂隙产生,但在同一应力条件下其微裂隙发育累计及时空分布差异明显.其中,太古宇变质岩的内部裂隙发育程度高于古生界灰岩以及中生界安山岩储层.因此,岩性是控制储层裂缝发育的基础,相同的构造应力下太古界变质岩储层裂缝发育程度最高、储集能力最强.

珠江口盆地的成盆机制和构造演化过程探讨是该地区烃源岩研究中不可缺少的环节,也是大家广泛关注的焦点问题.本文以阳江东凹为例,通过整体与局部相结合的分析方法,从整体上确定了研究区走滑断裂的发育特征和展布框架,明确了区域构造运动与走滑断裂的成因联系;并将整体划分成局部,聚焦于阳江东凹古近纪盆地构造演化阶段逐步分解与精细检验,对珠江口盆地的成盆机制、发育过程和演化模式进行分阶段解剖和分析.结果表明,研究区的构造演化过程分为三个阶段:文三段沉积期NW-SE向伸展,文二段沉积期南北向区域拉张作用下NE走向断裂右行右阶走滑拉分和文一段?恩平组沉积期NWW向走滑断裂左行左阶拉分.由于三个阶段受到不同的区域构造运动影响,各阶段盆地的打开方式和断裂的分布特征具有一定差异.同时,不同时期的构造演化过程与同时期区域构造应力场的转变一一对应,控制了沉积?沉降中心的分布,据此本文提出珠江口盆地的裂解模式是多期走滑构造控制的"叠合型"拉分盆地的新认识,研究区整体表现为三期构造叠合型盆地,盆地的构造叠合机制与洼陷的生烃排烃具有一定的相关性.

The East Asian continental margin straddles the boundary between the Pacific Subduction Domain to the east and the Tethyan Collision Domain to the west. The spatial and temporal interaction between these two dynamic domains induced a dextral trans-tensional stress field, generating nearly 75% of the globe?s marginal seas and continental margin rifts during the Cenozoic. Among these, the South China Sea (SCS) and its northern margin are located in the core of the Pacific Subduction Domain and the Tethyan Collision Domain. The evolution of the SCS and its northern margin are of prime interest because of their spectacular magnetic lineations and strong rifting. In spite of the several investigations carried out on the Cenozoic marginal seas and rift basins, their formation mechanisms remain equivocal. Here we perform a comprehensive analysis of seismic profiles and fault architecture data with a view to understand the Cenozoic tectonic evolution of the northern margin of the SCS. Based on detailed structural analysis of the geometry and kinematics, we demonstrate that the NE-and ENE striking faults assembled to horsetail-or feather-shaped structures in plan view, which display flower-like structures in seismic profiles. Two stages of faulting along NE-trending faults are identified along the northern margin of the SCS. The earlier oblique extension occurred during the Paleocene to the early Middle Eocene (-44?42 Ma), accompanied by strong rifting and formation of some left-step en echelon-like faults. The later trans-tensional faulting developed during the late Middle Eocene to the Early Miocene (-21 Ma), resulting in the formation of the dextral right-step trans-tensional fault system. Two stages of faulting were linked to the joint effect among the Indo-Eurasian collision to the west, the subduction of the Pacific Plate to the east and the slab pull of the proto-SCS to the south. Our study provides important insights into the dynamics and tectonics controlling the opening of the South China Sea. During the Late Eocene to the Oligocene, the dextral trans -extensional faulting along the right-step strike-slip fault system caused the opening of the Northwest Sub-basin, the East Sub-basin and the Northeast Sub-basin. However, during the Early Miocene, the sinistral strike slipping of the Ailao Shan-Red River (ASRR) shear zone and the slab-pull force of the proto-SCS resulted in the opening of the Southwest Sub-basin and the change of the spreading direction of the East Sub-basin.

珠江口盆地阳江东凹形成于古近纪裂陷期,广泛发育烃源岩的富存层段——文昌组、恩平组,具有陆相断陷盆地沉积以及构造控制下多幕演化的特征.沉积环境演变以及构造?沉积的耦合作用是陆相断陷盆地的重要研究方向,认识其动态过程可为烃源岩识别和油气评价建立基础.本文从三维地震资料、钻井资料入手,通过地震反射特征和井震联合分析,划分了研究区的层序地层格架,识别出文昌组、恩平组的地震相类型.根据地震相类型和岩性资料,认为裂陷期文昌组、恩平组发育7种沉积相,洼陷中心发育半深湖相、滨浅湖相、湖底扇相,洼陷边缘在不同时期因构造、物源的影响,不同程度地发育扇三角洲相、辫状河三角洲相、近岸水下扇相、滩坝相,构成完整的沉积体系.沉积期间,构造活动尤其是控洼断裂的活动对沉积产生重要的影响,总体分为初始裂陷阶段、强烈裂陷阶段、裂陷萎缩阶段三个阶段的演化,由此,阳江东凹为该三个阶段演化的产物.

Crustal instability to induce the geohazards often results from both the internal tectonic dynamics and external sediment processes. Thus, the detailed geodynamics and kinematics of geohazards are important for understanding the tectonic evolutionary process and evaluating potential geohazards. This paper focuses on the active faults, submarine landslides , earthquakes as well as submarine canyons geomorphology description and kinetics explanation in the northern South China Sea (SCS) continental margin . Firstly, we have estimated the spatial extent, fault-plane geometry and faulting behaviors of the submarine active faults, such as the Littoral Fault Zone, based on cumulative deformation recorded by geophysical seismic reflections and geomorphic markers. We also analyzed the reactivation of preexisting structures, as well as the spatial and temporal distribution and migration of the submarine landslides and canyons. Then, several conceptual models and a comprehensive study of some of the different factors that contributed to the geohazard chain are conducted based on pre-existing theory and available literature. This review study indicates: (i) geohazards of different phases and geohazard chain are generally triggered by both early-phase tectonics-dominated and later-phase sedimentation-dominated processes; (ii) the fault geometric and stress segmentation may have played an important role in controlling on the uneven and asymmetric distribution of earthquakes and submarine canyons of the northern SCS, Especially, the ENE-striking preexisting Littoral Fault Zone is the major seismogenic structure along the Southchina coastline; (iii) the tectono-sedimentary coupling induced landslide and slope failure that has help to shape the modern coastal and slope geomorphology.