Dimensions and architecture of late Pleistocene submarine lobes off the northern margin of East Corsica   总被引：2，自引：0，他引：2  

MARK E. DEPTUCK  DAVID J. W. PIPER  BRUNO SAVOYE  ANNE GERVAIS‡ 《Sedimentology》2008,55(4):869-898

Sandy lobe deposits on submarine fans are sensitive recorders of the types of sediment gravity flows supplied to a basin and are economically important as hydrocarbon reservoirs. This study investigates the causes of variability in 20 lobes in small late Pleistocene submarine fans off East Corsica. These lobes were imaged using ultra‐high resolution boomer seismic profiles (<1 m vertical resolution) and sediment type was ground truthed using piston cores published in previous studies. Repeated crossings of the same depositional bodies were used to measure spatial changes in their dimensions and architecture. Most lobes increase abruptly down‐slope to a peak thickness of 8 to 42 m, beyond which they show a progressive, typically more gradual, decrease in thickness until they thin to below seismic resolution or pass into draping facies of the basin plain. Lobe areas range from 3 to 70 km² and total lengths from 2 to 14 km, with the locus of maximum sediment accumulation from 3 to 28 km from the shelf‐break. Based on their location, dimensions, internal architecture and nature of the feeder channel, the lobes are divided into two end‐member types. The first are small depositional bodies located in proximal settings, clustered near the toe‐of‐slope and fed by slope gullies or erosive channels lacking or with poorly developed levées (referred to as ‘proximal isolated lobes’). The second are larger architecturally more complex depositional bodies deposited in more distal settings, outboard more stable and longer‐lived levéed fan valleys (referred to as ‘composite mid‐fan lobes’). Hybrid lobe types are also observed. At least three hierarchical levels of compensation stacking are recognized. Individual beds and bed‐sets stack to form lobe‐elements; lobe‐elements stack to form composite lobes; and composite lobes stack to form lobe complexes. Differences in the size, shape and architectural complexity of lobe deposits reflect several inter‐related factors including: (i) flow properties (volume, duration, grain‐size, concentration and velocity); (ii) the number and frequency of flows, and their degree of variation through time; (iii) gradient change and sea floor morphology at the mouth of the feeder conduit; (iv) lobe lifespan prior to avulsion or abandonment; and (v) feeder channel geometry and stability. In general, lobes outboard stable fan valleys that are connected to shelf‐incised canyons are wider, longer and thicker, accumulate in more basinal locations and are architecturally more complex.  相似文献   

基于Web Services的分布式GIS体系结构研究     

郭秀娟  范晓鸥 《吉林地质》2008,27(1)

分析了GIS的发展及Web Services的特点,讨论了Web Services的体系模型,提出了一个基于Web Services的分布式GIS的体系结构,并进行了模块分析。  相似文献   

Applied geomorphology and the impact of natural hazards on the built environment   总被引：2，自引：1，他引：2  

David Alexander 《Natural Hazards》1991,4(1):57-80

This paper examines the scope and limitations of geomorphological investigation of the sites of architectural and engineering works. Various degrees of vulnerability, forms of impact, and types of applied geomorphological response are summarized. Aspects of land development and construction practice that may increase the vulnerability of buildings and structures to geomorphological hazards are discussed. Strengths and weaknesses of the geomorphological input to hazard mitigation are reviewed. Examples are described that show both negative and positive influences exerted by geomorphological site analysis on urban and regional planning for unstable terrains in Italy. It is concluded that societal choice, within the overall matrix of a society's culture (sensu largo), will influence the way in which vulnerability is managed at sites, and hence the scope for utilizing geomorphological analysis of the physical risks.  相似文献   

Small turbidite systems in a complex tectonic setting (SW Mediterranean Sea): morphology and growth patterns   总被引：1，自引：0，他引：1  

Beln Alonso  Gemma Ercilla 《Marine and Petroleum Geology》2002,19(10)

Three small turbidite systems (Almeria, Sacratif, and Guadiaro), each tens of kilometres long, are developed in the complex morpho-structural setting of the northern Alboran Sea and have similar primary architectural elements (canyons, channel-levee systems, lobes). However, comparison reveals differences in the axial gradients of their canyons, depth/physiographic location, morphological framework, and lateral and longitudinal sedimentary shifts of turbidite deposition. The depositional architecture and sedimentary evolution from late Pliocene to Quaternary seems to be conditioned by number of submarine feeding sources (canyons), sea-level fluctuations and local tectonic (e.g. margin/canyon-channel gradients, faults). We group the Alboran turbidite systems into two models: mud/sand-rich submarine point-source and mud/sand-rich multiple submarine source ramp.  相似文献   

Building a 3-D model of a flood basalt: an example from the Etendeka, NW Namibia   总被引：1，自引：0，他引：1  

Dougal A. Jerram  Olivier Robbe 《Visual Geosciences》2001,6(1):1-8

Flood basalts represent large outpourings of lavas which often cover, and interact with, sedimentary basins. For this reason areas with significant flood basalt cover are often targets for hydrocarbon exploration. Problems exist, however, when trying to image sediments and structures in offshore regions covered by basalts. Here we present preliminary 3-D models of the Etendeka flood basalt province from NW Namibia, which can act as an aid in understanding the internal and external architecture of the flood basalt cover. Satellite images, digital elevation models, measured geological logs, sections and maps, are used to create the geological model. Models are presented in 2 parts; 1) models created using topography with images such as Land Sat and geological maps draped over them, and 2) a 3-D model of key lava and sediment surfaces in the basin as defined by measured geological sections. Initial results show a palaeo-volcanic feature early in the flood basalt history which is onlapped by later Iavas. The modelling also allows a simple correction for post emplacement subsidence by assuming an original sub horizontal position for the first basin wide silicic flow unit.  相似文献   

均匀介质中散射过程的奇性分析     

栾文贵 《地球物理学报》1993,36(4):489-509

本文比较详细地讨论和分析了均匀介质中零偏移距散射曲面拓扑奇性和相应回波解析奇性之间的关系和分类.其基础是衍射理论的Kirchhoff积分,原理是通过曲面几何函数的解析奇性和距离函数的拓扑奇性之间的联系.基本的数学工具是Morse理论和突变理论.  相似文献   

基于点集拓扑学的三维拓扑空间关系形式化描述   总被引：24，自引：3，他引：24  

郭薇  陈军 《测绘学报》1997,26(2):122-127

本文阐明了研究空间关系理论的必要性，分析了拓扑空间关系描述方法的研究进展及存在问题，以点集拓扑理论为基础，运用维数扩展的方法，提出三维拓扑空间关系完善和形式化的描述框架，在此基础上，对三维空间目标中存在着的拓扑空间关系进行了分类，定义了五种基本的拓扑空间关系，并且给出了三维拓扑空间关系最小集的互斥性与完备性证明。  相似文献   

从栅格数据直接建立拓扑关系的算法研究     

朱振兴 《遥感学报》1993,(3)

本文提出了从栅格数据直接建立拓扑关系的思想,用跟踪过程中容易获得的拓扑信息来优化拓扑生成的算法模型,借以提高拓扑生成的效率。本文还提出用连通性区域填充的方法处理各种任意复杂岛的思想。  相似文献   

可视化平差软件的设计与开发     

赵东保  张书毕  盛业华  朱建华 《四川测绘》2003,26(2):68-71

笔者依据科学计算可视化的思想，设计并开发了一套可视化平差软件。实践表明：该软件具有数据输入方便、容错及纠错能力强、可编辑控制网的拓扑关系、图形属性一体化管理、成果报告美观大方、内容丰富且查阅方便等优点。  相似文献   

中国民族建筑研究与保护   总被引：1，自引：0，他引：1  

王景慧 《中国勘察设计》2008,(3):11-15

本文说明了民族建筑研究的三个阶段,总结了民族建筑的一些特点,同时提出了保护民族建筑的一些建议。  相似文献