Delgada Fan: Preliminary interpretation of channel development

Geo-Marine Letters - The Delgada Fan, an irregularly shaped turbidite deposit extending more than 350 km offshore from northern California, consists of two large leveed-valley units each fed by a...     

Side echoes from a sinuous fan channel obscure the structure of submarine fan channel/levee systems,Amazon Fan

A high-resolution bathymetric and seismic study of sinuous midfan channels on the Amazon Fan shows that some common elements of seismic profiles across the channel/levee system may be side echoes (sideswipe) from reflective, coarse channel-floor sediments Which lie to the side of the ship track. This includes portions of a dipping zone of high-amplitude reflectors beneath the channel. If these strong echoes are side echoes rather than buried coarse sediments, there may be less coarse material present within the midfan channel/levee systems than predicted, and channel evolution is still poorly resolved. Side echoes may be common in other areas of complex deep-sea morphology.     

运用神经网络方法对WRF数值模拟结果的初步释用

针对WRF模式的数值模拟结果中的各种输出变量,运用BP神经网络方法,对大连站点的气温、风速等变量进行了初步的释用,与实况进行比较后发现,释用后的结果较模式直接输出结果有了很大的改进;同时,运用中低层云水混合比、气压、海平面高度层上的温度露点差等变量,对能见度进行了诊断释用,获得令人满意的结果.     

老铁山水道潮流能初步估算

采用ECOMSED海洋数值模型较好地模拟了渤海的潮流运动状况,估算了老铁山水道的潮流能的理论蕴藏量,并采用FLUX方法对该水道的技术可开发量进行了评估.结果表明,老铁山水道北侧近岸海域最大可能流速约2.5 m/s,平均功率密度超过500W/m2,大潮平均最大功率密度为3 700w/m2,小潮平均最大功率密度为1400w...     

运用支持向量机方法对数值模拟结果的初步释用

基于获得的海水浴场逐日两次观测资料及同期NCEP数值模拟结果(提取各种相关变量),通过求取两者之间的相互关系,并采用最优子集方法确定了对各预报要素具有重要意义的影响因子。针对海水浴场的气温、降水及能见度等要素的预报,应用支持向量机方法建立了相应的预测模型,最终获得不同海水浴场在不同预报时效、不同预报要素的数值产品释用结果。经过对比分析,各预报要素释用后的结果较释用前在预报准确率方面有较大的提高。     

厦门湾大型深水航道初步研究

大型深水航道作为大型码头的配套工程，其建设方案和工程投资对大型码头工程决策起到至关重要的作用，本文以厦门湾后石港区大型码头规划为例，对配套的3个大型深水航道建设方案进行了初步的比选研究，以供规划和建设部门参考。     

Controls on turbidite sedimentation: Insights from a quantitative approach of submarine channel and lobe architecture (Late Quaternary Congo Fan)

The role of internal and external forcing of sedimentation in turbidite systems remains a subject of debate. Here we propose new insights from the quantitative analysis of architectural parameters of the Congo Axial Fan.Fifty-two channel-levee-lobe systems, spanning the last ca. 200 ka, are visible on the seafloor, most of them having slightly elongated lobe complexes at their termination. Volumes of lobe complexes (usually 3–196 km³) are highly variable in time and space. The cumulative volume of the lobe complexes represents approximately 30% of the volume of the Axial Fan.The Axial Fan is sequentially divided into periods of increasing/decreasing channel lengths and basinward/landward migrations of avulsion points, representing successive prograding/retrograding architectural patterns called architectural cycles. These cycles are either symmetrical saw toothed and bell-shaped with progressive progradation and retrogradation phases, or asymmetrical, with long-lasting progradation phases and abrupt retrogradation phases that correspond to channel avulsions occurring high up on the fan.Our study points to the interplay between internal and external factors controlling the architecture of the Congo Axial Fan. The local topographic constraint is a major factor in the fan's stacking pattern. However, cyclic evolution of the architecture reveals major shifts in the deposition site that are linked to very upfan avulsion events. These events are interpreted to be driven by external factors (e.g. climate and/or eustatic sea-level change) that were able to drastically increase and/or coarsen the sediment supply to the fan.     

Rhone Deep-Sea Fan: A review

The Rhone Fan is a large Plio-Pleistocene turbidite deposit in the western Mediterranean Sea. The fan is fed from the broad Rhone River delta, but only one canyon, the Petit-Rhone, has fed most of the major turbidite depositional sequences that have been mapped. Slumping of sediment from intercanyon areas on the delta slope also has provided much sediment for the fan. The lack of Recent turbidite deposition on the fan suggests that turbidite sedimentation dominates during glacial low stands of sea level, building major leveed valley sequences, while surficial slumping of the valley levee deposits and pelagic sedimentation seem to mark high stands of sea level during interglacial periods.     

Rhone Deep-Sea Fan: A review

The Rhone Fan is a large Plio-Pleistocene turbidite deposit in the western Mediterranean Sea. The fan is fed from the broad Rhone River delta, but only one canyon, the Petit-Rhone, has fed most of the major turbidite depositional sequences that have been mapped. Slumping of sediment from intercanyon areas on the delta slope also has provided much sediment for the fan. The lack of Recent turbidite deposition on the fan suggests that turbidite sedimentation dominates during glacial low stands of sea level, building major leveed valley sequences, while surficial slumping of the valley levee deposits and pelagic sedimentation seem to mark high stands of sea level during interglacial periods. Margin setting represents fan and/or source area     

The Laurentian Fan: Sohm abyssal plain

The 0.5- to 2-km thick Quaternary Laurentian Fan is built over Tertiary and Mesozoic sediments that rest on oceanic crust. Two 400-km long fan valleys, with asymmetric levees up to 700-m high, lead to an equally long, sandy, lobate basin plain (northern Sohm Abyssal Plain). The muddy distal Sohm Abyssal Plain is a further 400-km long. The sediment supplied to the fan is glacial in origin, and in part results from seismically triggered slumping on the upper continental slope. Sandy turbidity currents, such as the 1929 Grand Banks earthquake event, probably erode the fan-valley floors; but thick muddy turbidity currents build up the high levees.     

The Laurentian Fan: Sohm Abyssal Plain

The 0.5- to 2-km thick Quaternary Laurentian Fan is built over Tertiary and Mesozoic sediments that rest on oceanic crust. Two 400-km long fan valleys, with asymmetric levees up to 700-m high, lead to an equally long, sandy, lobate basin plain (northern Sohm Abyssal Plain). The muddy distal Sohm Abyssal Plain is a further 400-km long. The sediment supplied to the fan is glacial in origin, and in part results from seismically triggered slumping on the upper continental slope. Sandy turbidity currents, such as the 1929 Grand Banks earthquake event, probably erode the fan-valley floors; but thick muddy turbidity currents build up the high levees. Margin setting represents fan and/or source area     

厦门湾深水航道资源开发的探讨

本文从分析厦门湾航道资源现状入手 ,论述了厦门湾开发深水航道的迫切性 ,提出了厦门湾深水航道资源开发原则和布局。这些原则和布局可为今后厦门湾港口、航道资源开发提供科学依据。     

福建海洋经济发展浅析

福建省是一个具有战略区位优势的海洋资源大省，合理开发海洋优势资料、发展海洋经济、建设海洋经济强省，对推进福建省经济持续发展具有重要的战略意义。既要加大海洋资源开发的力度，又要加强海洋资源的保护，合理调整，优化海洋产业结构，发挥科技优势，实施科技兴海战略。     

Key controls on submarine channel development in structurally active settings

Submarine channel-levee systems commonly develop in structurally active deepwater settings. Despite their widespread development in such settings, only recently have researchers begun to address the response of channel-levee system evolution to deformation. Key factors which govern channel evolution and morphological development are relative rates of deformation and channel deposition and erosion, and also the number and scale of deformational structures, relative to the scale of the submarine channel. Submarine channel-structure interactions can be split into four end-members: deflection, blocking, diversion and confinement. Where deformation is coeval with channel development, an increase in the relative rate of uplift versus deposition and erosion causes a transition from channel deflection to blocking. Diversion and confinement are linked by the number, scale and orientation of structures relative to the channel flow path. Increasing the number of structures and their scale typically results in channel confinement. Underlying all of these individual controls is the distribution of local accommodation, which is determined by specific structural style. This distribution of accommodation over relatively small (<10 km) length scales strongly affects local channel development in order to attain the equilibrium profile. Knowledge of these controls on submarine channel development can increase our understanding of how these deepwater sedimentary systems evolve and distribute sediment across deforming submarine slopes. Understanding the factors governing spatial variations in channel morphology may also be applied when exploring for hydrocarbon reservoirs in structurally active deepwater settings.     

Mississippi Fan: Internal structure and depositional processes

The Mississippi Fan is a Quarternary accumulation composed of more than seven elongated fan lobes. Isopach and structure maps show frequent shifting of these lobes. The Mississippi Canyon, formed by retrogressive slumping, connects to the youngest fan lobe. The upper fan-lobe is characterized by a large, incised, partially infilled, leveed channel. The middle fan-lobe is aggradational, convex in cross section, with a channel-levee complex on its apex. The lower fan-lobe contains a recently active small channel and several abandoned ones. Depositional patterns can be explained by several processes: “fluvial,” debris flows, and turbidity currents. Margin setting represents fan and/or source area     

Mississippi Fan: Internal structure and depositional processes

The Mississippi Fan is a Quarternary accumulation composed of more than seven elongated fan lobes. Isopach and structure maps show frequent shifting of these lobes. The Mississippi Canyon, formed by retrogressive slumping, connects to the youngest fan lobe. The upper fan-lobe is characterized by a large, incised, partially infilled, leveed channel. The middle fan-lobe is aggradational, convex in cross section, with a channel-levee complex on its apex. The lower fan-lobe contains a recently active small channel and several abandoned ones. Depositional patterns can be explained by several processes: “fluvial,” debris flows, and turbidity currents.     

The Astoria Fan: An elongate type fan

The Astoria Fan, a modern system, is located on a subducting oceanic crust and fills a north-south-trending trench along the Oregon continental margin. Well-developed channels cross the entire fan length; they display classic inner-fan leveed profiles but evolve into distributaries in the midfan area where the gradient decreases sharply. During periods of low sea level, inner- and middle-fan channels funnel sand to distal depositional sites in the outer-fan area where the sand/shale ratios are highest. This pattern of sand displacement and efficiency of transport appears to be characteristic of elongate fans fed by a major river and submarine canyon. Margin setting represents fan and/or source area     

The Astoria Fan: An elongate type fan

The Astoria Fan, a modern system, is located on a subducting oceanic crust and fills a north-south-trending trench along the Oregon continental margin. Well-developed channels cross the entire fan length; they display classic inner-fan leveed profiles but evolve into distributaries in the midfan area where the gradient decreases sharply. During periods of low sea level, inner- and middle-fan channels funnel sand to distal depositional sites in the outer-fan area where the sand/shale ratios are highest. This pattern of sand displacement and efficiency of transport appears to be characteristic of elongate fans fed by a major river and submarine canyon.     

舟山本岛北部灌门水道及邻近海域潮波特性初步研究

依据2004年在舟山灌门水道及邻近海域获取的同步潮位和潮流资料,对该海域的潮波特性进行了统计和分析,并对分析过程中发现的主要半日分潮经过灌门水道时振幅有较大幅度减小的现象进行了初步研究,认为截面积急剧变化的水道,潮波势能向动能的转换是产生主要半日分潮振幅减小的一个重要因素。这一结论或许有助于解释M2分潮波通过舟山群岛海域振幅明显减小的现象。     

舟山海岛旅游环境可持续发展初步研究

对舟山海岛旅游资源和旅游环境现状进行了调查研究 ,指出该区具有丰富的旅游资源 ,且旅游环境仍处在良好的水平上 ,但随着旅游业的发展 ,环境问题也日益显露 ,提出了旅游业可持续发展的对策和建议。