Discovery and significance of deep-water gravity-flow deposits of the late Barremian of Early Cretaceous in Lower Congo Basin

Taking the middle Pointe Indienne Formation of the Lower Cretaceous Barremian in the Lower Congo Basin as an example,based on the theory of deep-water sedimentology,combined with the latest research progress of gravity-flow,and with the help of the latest drilling core data and its analyzing test results in the study area,the lithology,sedimentary structure types and petrological characteristics were investigated. It is found that gravity-flow deposits were widely developed in the middle Pointe Indienne Formation of the study area. The deposition process and the conceptual model of sand-body development for the deep-water gravity-flow have also been summarized. The gravity-flow deposits are mainly composed of midium-fine grained sandstone where the flute cast,load cast,flame structure,ball and pillow structure are occurred at the bottom and the normal graded bedding,parallel bedding,climbing ripple bedding,convolute bedding,water escape structure and floating mud gravel are occurred in the internal part. The gravity flow sandstones whose transportation mechanism are dominated by suspension transport are mainly feldspathic detrital quartz sandstones which are poorly sorted,sub angular and sub rounded. Grainsize accumulation probability curve are characterized by both “one-segment” which suggests total suspension population and “two-segment” which suggests high suspension population. Five fluid types of gravity-flows including,slump,sandy debris flow,muddy debris flow and turbidity can be identified,and six styles of facies combination in vertical direction have been recognized. The gravity-flow sand-body in the study area can form large-scale oil and gas reservoir due to the better lateral continuity and the thicker vertical stack thickness.     

塔中地区中晚奥陶世内波、内潮汐沉积

现代海底普遍发育由内波、内潮汐引起的深水牵引流,内波、内潮汐不仅可形成各种厘米级的深水牵引流沉积构造,还可建造千米级的大型沉积物波。这种大型沉积物波既可沿斜坡向下迁移,也可沿斜坡向上迁移。在古代地层记录中已发现各种厘米级的内波、内潮汐沉积单元,但尚未发现内波成因的大型沉积物波。塔中地区中上奥陶统碎屑岩段内发育内波及内潮汐形成的各种牵引流沉积构造单元。通过详细的岩心观察,识别出 4种内波、内潮汐沉积微相类型及 5种基本垂向沉积层序。此外,通过地震剖面分析,在研究区中上奥陶统陆坡相中识别出顺坡向上迁移的大型沉积物波,该沉积物波的特征与现代海底发育的沉积物波的特征类似,运用内波理论可对其成因进行合理的解释。     

西沙海区碳酸盐台地地震反射特征及沉积模式

随着南海海盆的持续扩张,西沙海区整体沉降,从早中新世起西沙碳酸盐台地开始发育,而且在台地之上生长了不同类型的生物礁。通过地震识别认为,西沙海区生物礁在地震剖面上表现为顶底强振幅的丘形连续反射、内部弱振幅杂乱反射;碳酸盐台地表现为顶部强振幅连续平行反射、底部界面局部模糊、内部强弱相间亚平行连续反射。通过对西沙海区地层层序的分析以及大量地震资料的解释认为,在西沙碳酸盐台地的发育早期它受基底构造的控制,而在后期主要受多期海平面变化的影响,其发育演化经历了初始生长—加积—出露—二次生长—淹没等一系列阶段,复杂的演化过程也使西沙碳酸盐岩具有较好的储集条件和油气远景。     

Deep-water stands of Cystoseira zosteroides C. Agardh (Fucales,Ochrophyta) in the Northwestern Mediterranean: Insights into assemblage structure and population dynamics

Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m⁻². Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m⁻², and densities ranging from 4 to 7 plants m⁻². The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m⁻² and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.     

深水港与江苏海洋经济探讨——以洋口港为例

从江苏海洋经济发展现状入手,分析了江苏海洋经济的特点、存在问题和发展瓶颈。基于江苏海洋经济和深水港口的现状,重点阐述了洋口港在江苏海洋经济中的地位和作用,提出洋口港是苏北海岸发展重要的支点,江苏海洋经济的希望在于深水大港以及由此带动发展起来的港区工业和海港中心城市,提出了“一核三载体”的海洋发展战略。     

琼东南盆地深水区BSR带裂隙系统空间分布特征

为解决甲烷渗漏系统末端裂隙系统空间分布规律问题,基于南海北部深水区高分辨率三维地震数据,采用可视化与相干体技术描述似海底反射层分布区裂隙空间结构与分布特征,阐述了裂隙产生的地质成因类型,讨论了裂隙与其他类型输导体系对甲烷气成藏的关系。似海底反射层界面上部空间裂隙远少于下部空间的地质结构体,使水合物成藏过程中甲烷气供大于散,对研究水合物成藏和检测甲烷气的渗漏有普遍指示作用。根据裂隙的发育规模,研究区大致可以识别出短裂隙、长裂隙、裂隙束、裂隙群(组) 4种类型,它们对流体的渗漏能力依次增强,这些裂隙在地层中往往以多类型共存的方式,或与其他地质构造共同构成渗漏系统。这些结果和认识对完善深水盆地甲烷气渗漏系统水合物成藏模式及成藏机理有广泛意义。     

南海珠江深水扇系统的层序地层学研究

位于古珠江大河及其浅海陆架富砂珠江三角洲下方的陆坡深水区白云凹陷是沉积大型深水扇的有利地域,宏观认识的进展指导了白云深水陆坡区系统的层序地层学研究,并因此发现了多层序叠置的南海珠江深水扇系统,使其成为具有油气勘探潜力的新领域。南海珠江深水扇系统的层序地层学研究包含了以下关键内涵层序地层学解释中在承认各种资料的分辨率、多解性和局限性的同时,强调多学科资料的综合应用、相互印证,强调周期性海平面变化对沉积的控制作用研究,强调地震反射相位等时界面确认的有效性,强调层序界面的反复确认,强调生物地层时代、相对海平面、全球海平面与层序界面的响应研究,强调层序格架内各沉积体的相互响应关系研究等。层序地层格架的建立导致了珠江深水扇系统的发现,揭示了珠江大河流域、陆架区大型珠江三角洲系统与陆坡区珠江深水扇系统的耦合关系,揭示了珠江深水扇与海平面变化的响应关系,揭示了珠江深水扇与古地理的响应关系。珠江深水扇系统的发现有力地推动了南海陆坡深水区的油气勘探。     

南海深水盆地油气地质特征及勘探方向

在深入调研南海深水盆地油气地质条件的基础上,系统分析了油气分布规律和成藏主控因素,明确了油气资源潜力和有利勘探方向,旨在为南海深水油气勘探决策提供科学依据.研究结果表明:南海深水盆地发育在非典型边缘海大陆边缘,其石油地质条件具有特殊性,油气分布特征存在显著的南北差异.其中,南海北部深水的珠江口盆地和琼东南盆地,以构造圈...     

大水深斜坡堤护面块体稳定重量的确定

近年来,军队和地方港口建设中,在一些水深达20 m的水域,选择了造价相对较高、但安全性和耐久性较好的斜坡式结构防波堤。但在确定护面块体稳定重量时却发现,按照相关规范计算的重量值偏小,不能满足安全性的要求。结合某船厂防波堤的断面物模试验,对大水深的斜坡堤护面块体的稳定性进行了初步分析,发现在该试验中块体的临界重量为8.15 t。并提出在计算块体稳定重量时应考虑水深的影响,适当降低块体稳定系数的取值。