The Enya mounds: a lost mound-drift competition     

D. Van Rooij  V. A. I. Huvenne  D. Blamart  J.-P. Henriet  A. Wheeler  H. de Haas 《International Journal of Earth Sciences》2009,98(4):849-863

The genesis and evolution of cold-water coral banks along the Northeastern Atlantic margin is known to be influenced by several factors, among which the palaeotopography and nature of the coral settling surface, the presence of bottom currents and sediment supply. In this paper, a case study is presented of the Enya mound cluster, located in the southernmost tip of the Belgica mound province, west of Ireland. Below this mound cluster, seismic stratigraphy revealed a yet unmapped local unconformity RD1b, being part of a composite erosion event (RD1). As such, from the Late Miocene to Late Pliocene, at least two erosional events have incised the margin, ending with the final RD1a “moundbase” unconformity, acting as a base for the Enya mounds. During the Quaternary the mounds became outgrown and were covered by a mounded contourite drift. In addition, they are closely associated with a cluster of seabed pockmarks. The bottom current regime which became active since the Middle Pleistocene has certainly influenced the fate of this mound cluster. The occurrence of the pockmarks seems to be related to relatively recent fluid migration processes, however leaving an open question if any previous seepage phases were involved in the growth or initiation of the coral banks.  相似文献   

山东莱州浅滩地区沉积特征与沉积作用          下载免费PDF全文

王庆  战超  商杰  宋传广  仲少云  刘亚龙  王红艳 《海洋与湖沼》2011,42(3):337-342

通过系统采集海底表层沉积样品进行粒度测试分析,对现代莱州浅滩地区的沉积类型、粒度特征、泥沙搬运方式、运移趋势及沉积动力、沉积机制进行了研究。结果表明,莱州浅滩是形成于松散碎屑堆积海岸岬角岸外的砂砾质水下沙洲／沙脊,它的形成深刻改变了浅滩地区原有的沉积动力和机制,在浅滩两侧海域各自形成了大致对称的潮余环流,分别与两个主要...  相似文献   

基于中资商业银行全球空间扩展的世界城市网络及其影响因素   总被引：7，自引：0，他引：7  

薛德升  邹小华 《地理学报》2018,73(6):989-1001

世界城市及其网络是近20多年来国际上城市研究的重要方向。现有研究主要反映了发达国家高级生产者服务业企业主导下的世界城市网络,针对中国等新兴经济体经济动力影响下的世界城市网络的研究明显不足。以在全球快速扩展中的中资商业银行为对象,利用改进的链锁网络模型,分析了1978年以来中资商业银行境外扩展的时空变化,及其连接下的世界城市网络的空间结构变迁。结果显示：中资商业银行的全球扩展,强化了中国主要城市与西欧和北美核心金融中心城市、全球的区域性门户城市、以及亚太地区的世界城市之间的联系,对不同阶段全球的世界城市网络的发展产生了日益重要的影响。中国的对外经济、人员以及政府间的联系,是影响中资商业银行全球扩展与世界城市网络格局的主要原因。  相似文献   

Extreme wave event along the Guyana coastline in October 2005     

Mathijs van Ledden  Geoffrey Vaughn  Joost Lansen  Frank Wiersma  Mewburn Amsterdam 《Continental Shelf Research》2009

The objective of the research is to analyze in detail the causes and consequences of the unusual event at the coast of Guyana (South America) during October 16–19, 2005. Several sea defense structures were damaged and flooding of low-lying areas occurred. A data analysis of offshore wave and water level characteristics shows an abrupt change in wave direction from east to almost north on October 16, 2005 and a sudden increase in the offshore peak period up to extreme values. The offshore significant wave height was also relatively high, and these wave characteristics coincided with springtide conditions. The long-wave periods and the sharp transition in wave direction indicate that this event is associated with swell waves generated by a depression far away. An analysis of hurricanes and depressions reveals that a severe depression in the Northern Atlantic Ocean during October 11–15 was the origin of this swell event. Numerical computations with SWAN have been carried out to investigate the propagation of the offshore wave characteristics towards the shoreline. The SWAN model includes wave damping due to the presence of soft mud deposits. A calibration of the parameters has been carried out using joint offshore and onshore wave data from November 2006. The numerical simulations of the event in October 2005 clearly demonstrate that the mud banks damp the wave heights, but have almost no effect on the peak period. The resulting waves at the steep sea walls can be classified as surging waves causing severe runup and overtopping. The obtained insights are translated into practical recommendations for the Guyana Sea and River Defence Division in Guyana to build a sustainable management and maintenance of the sea defenses in the future.  相似文献   

BOOK REVIEWS     

《The Professional geographer》1988,40(3):347-378

Books reviewed in this article: The Mexican Colonial Copper Industry. Elinore M. Barrett . The Control Revolution: Technological and Economic Origins of the Information Society . James R. Beniger . Land Degradation and Society . Piers M. Blaikie And Harold C. Brookfield , Eds . La carte, mode d'emploi. Roger Brunet . France: les dynamiques du territoire . Roger Brunet AND Jacques Sallois , EDS. At the Crossroads—The Mineral Problems of the United States . Eugene N. Cameron . A Census of One Billion People , Papers for International Seminar on China's 1982 Population Census. Li Chengrui , ED. Les Milieux “Naturels” du Globe . Jean Demangeot . The Geophysiology of Amazonia: Vegetation and Climate Interactions : Robert E. Dickinson , ED. Tenn-Tom Country . James F. Doster And David C. Weaver . Family Farming in Europe and America . Boguslaw Galeski And Eugene Wilkening , EDS. The Geography of Urban Transportation . Susan Hanson , Ed. Combating Desertification in Developing Countries . J. K. Jain , ED. Cartography in France—1660–1848. Science, Engineering and Statecraft . Josef W. Konvitz . Distribution of Distances in Pregeographical Space . Hans Kuiper . Physical Geography Lab Manual: A New Experimental Approach . Neal G. Lineback And John M. Harlin . Physical Geography: A Landscape Appreciation , 2nd ed. Tom L. Mc Knight . The Desert Is No Lady: Southwestern Landscapes in Women's Writing and Art . Vera Norwood And Janice Monk , EDS. France: A Geographical, Social, and Economic Survey . Philippe Pinchemel , translated, by D. Elkins and T. H. Elkins. Gene Banks and the World's Food . Donald L. Plucknett , Nigel J. H. Smith , J. T. Williams , And N. Murthi Anishetty . Latin American Development: Geographical Perspectives . David Preston , Ed. Making Sense of Development: An Introduction to Classical and Contemporary Theories of Development and Their Application to Southeast Asia . P. W. Preston . The History of the Countryside. Oliver Rackham . The Third World in Perspective . H. A. Reitsma AND J. M. G. Kleinpenning . The Industrial Geography of Australia . David C. Rich . The Recruiting Game , 2nd Ed., revised. John F. Rooney , JR. A Cultural Geography of North American Indians . Thomas E. Ross AND Tyrel G. Moore , EDS. Eastern Europe . Dean S. Rugg . Human Territoriality: Its Theory and History . Cambridge Studies in Historical Geography: 7. Robert David Sack . Experimental Fluvial Geomorphology . Stanley A. Schumm , M. Paul Mosley , AND William E. Weaver . The New Urban Landscape . David Schuyler . Atlas of American Women . Barbara Gimla Shortridge . Impacts of Hazardous Technology: The Psycho-Social Effects of Restarting TMI-1 . John Sorensen , Jon Soderstrom , Emily Copenhaver , Sam Carnes AND Robert Bolin . Modern Physical Geography , 3rd Ed., (Third Edition). Arthur N. Strahler AND Alan H. Strahler . India: Economic Resource Base and Contemporary Political Patterns . B. L. Sukhwal .  相似文献   

Nutrient control of the global occurrence of isolated carbonate banks     

A. Vecsei 《International Journal of Earth Sciences》2003,92(4):476-481

The growth and origin of the world's isolated carbonate banks are as yet not completely understood. This paper presents a comparison of the areas, depths, and latitudinal distribution of the world's carbonate banks. These are then compared with chemical parameters of seawater in the upper mixed zone of the oceans and at depth. The results allow large-scale inferences to be made on the interacting controls on bank growth and distribution. The data support the hypothesis that nutrient-rich waters commonly control bank depth and size.  相似文献   

湖南省舂陵水两岸风化型锰矿地质特征及找矿方向     

夏泽群  姜必广 《矿产与地质》2008,22(2):101-106

近年来锰矿石价格飞速提升．舂陵水两岸地区锰矿找矿吸引了更多投资者的目光,在对湖南省未阳市东山下锰矿普查工作的取得较理想的成果后,对该地区前期的工作成果加以整理、总结,提出今后的找矿方向及工作建议。该地区风化型锰矿开采条件优越,潜在经济价值巨大,开发利用前景广阔。  相似文献   

Mark5B格式器及10G网络传输系统在VLBI中的应用     

于威  ;张秀忠  ;朱人杰  ;陈岚  ;吴亚军  ;郭绍光 《天文研究与技术》2014,(3):287-298

由于遥远的天体发出的无线电信号极其微弱,信噪比极低,VLBI系统要想得到较高的测量精度,必须尽量加大测量带宽和提高采样位数,但是这样会导致VLBI终端(比如数字基带转换器)产生的观测数据激增。传统的VLBI终端数据传输系统采用VSI接口,数据最高传输速率限制在2 Gbps,且数据记录设备必须采用定制的Mark5B设备,极其不灵活,因此已经不能适应现在VLBI系统的观测需求。为了提高数据传输速率,增加数据记录设备的灵活性,上海天文台新研制的基于多相滤波器组和快速傅里叶变换方式的数字基带转换器的数据传输系统采用了高速灵活的10 G网络接口。10 G网络系统中数据传输采用报文交换方式,因此数据到达接收端的时间不是精确可靠的,这要求数据在进入10 G网络接口之前必须已经具有标准的VLBI数据格式,所以在10 G网络前端设计了Mark5B格式器。详细介绍了基于现场可编程门阵列的Mark5B格式器及10 G网络传输系统的设计原理,并在文章的最后通过三组实验验证了其功能的正确性和性能的稳定性。  相似文献   

三维生物礁滩建模及地震数值模拟     

黄继伟  熊晓军  贺振华 《物探化探计算技术》2014,(3):326-330

基于塔礁、点礁、生物滩等地质体的几何特征及地质特征,采用高精度的三维块状建模方法,建立了适合于复杂地区的三维礁滩复合体模型。该模型不但立体地反映了生物礁、生物滩及地层间的空间展布特征,还可以直观地体现了生物礁滩储层内部的物性差异。此外采用FK域三维波动方程数值模拟方法对其进行了地震波场数值模拟,得到了一系列具有代表性时间剖面上的地震波场响应特征,为正确认识实际生物礁滩的复杂结构和特性提供了依据。  相似文献   

基于TM图像的潮滩表层沉积物含水量推算模型研究——以江苏辐射沙洲区为例     

沈永明  杨劲松  张忍顺  刘咏梅 《地理科学》2009,29(3)

潮滩表层沉积物含水量是反映潮滩与潮水周期性作用并指示潮滩高程的重要指标,了解潮滩表层沉积物含水量是开发利用潮滩资源的重要工作之一。以江苏辐射沙洲为例,在对应于2000年4月的TM遥感图像成像时潮位特征的潮汐周期时,测量了两条断面的表层沉积物含水量,然后通过对辐射沙洲TM遥感图像的多种处理及其比较,找出了TM图像与潮滩表层沉积物含水量的相关系数绝对值最高的数字图像处理方法,然后再进行傅立叶变换等处理,并推算出可决系数较高的表层沉积物含水量推算模型。  相似文献