A quality investigation of global vertical datum connection   总被引：3，自引：0，他引：3  

Peiliang Xu 《Geophysical Journal International》1992,110(2):361-370

  相似文献   

单个粘土体裂缝中水流规律的研究   总被引：2，自引：0，他引：2       下载免费PDF全文

葛中华  范炳恒 《地质学报》1993,67(2):159-167

通过模型实验,研究粘土体裂缝中的水流规律,提出了临界水位上升速度的概念。水位上升速度大于临界值时,裂缝中水流量增加,反之则减少。裂缝水流量与水位不呈正比关系。指出粘土裂缝中最大水流量要比相同条件下基岩裂缝水流量小30—40倍。随着水流运动的延续,水流量将逐渐变小。在水流作用下,粘土裂缝宽度将变窄3.0—4.0cm,裂缝深度也大幅度变浅到裂缝水深的50％以上。  相似文献   

Quaternary depositional patterns and sea-level fluctuations, northeastern North Carolina     

Peter R. Parham  Stanley R. Riggs  David J. Mallinson 《Quaternary Research》2007,67(1):83-99

A detailed record of late Quaternary sea-level oscillations is preserved within the upper 45 m of deposits along an eight km transect across Croatan Sound, a drowned tributary of the Roanoke/Albemarle drainage system, northeastern North Carolina. Drill-hole and seismic data reveal nine relatively complete sequences filling an antecedent valley comprised of discontinuous middle and early Pleistocene deposits. On interfluves, lithologically similar marine deposits of different sequences occur stacked in vertical succession and separated by ravinement surfaces. Within the paleo-drainage, marine deposits are separated by fluvial and/or estuarine sediments deposited during periods of lowered sea level. Foraminiferal and molluscan fossil assemblages indicate that marine facies were deposited in a shallow-marine embayment with open connection to shelf waters. Each sequence modifies or truncates portions of the preceding sequence or sequences. Sequence boundaries are the product of a combination of fluvial, estuarine, and marine erosional processes. Stratigraphic and age analyses constrain the ages of sequences to late Marine Isotope Stage (MIS) 6 and younger (∼ 140 ka to present), indicating multiple sea-level oscillations during this interval. Elevations of highstand deposits associated with late MIS 5 and MIS 3 imply that sea level was either similar to present during those times, or that the region may have been influenced by glacio-isostatic uplift and subsidence.  相似文献   

河北沿海海侵灾害初探   总被引：5，自引：1，他引：4  

萧嗣荣  穆仲义 《地理研究》1998,17(1):75-81

文中以包含海进、海岸侵蚀和海水入侵的广义“海侵”概念,论述河北沿海地区海侵现状及其危害,探讨海侵产生的自然原因和人为活动的影响,在此基础上,评估海侵发展趋势。  相似文献   

四川甘孜生康剪切混杂岩带物质组成、变形特征及演化历史     

江元生  葛梦春 《四川地质学报》1998,(2)

甘孜生康剪切混杂岩带,它初始发育在陆棚与大陆基之间,是“再生”小洋盆关闭、俯冲－碰撞乃至斜冲剪切、左行走滑综合作用的产物。带内由不同岩性,不同层位,不同时代的构造岩块与遭受强烈剪切变形的粉砂岩、板岩“基质”组合而成。宏观上,无层无序,块体内有序,是造山带特有的非史密斯地层体。  相似文献   

1992—2007全球海平面变化     

马金周永宏  廖德春廖新浩 《中国科学院上海天文台年刊》2007,(1):37-41

引起全球海平面变化的因素是复杂多样的，大气压、风、大洋环流以及海水密度的变化，都会引起海平面在时间、空间上的变化，而海水温度的变化是海平面变化的主要原因。该文利用法国Archiving, Validation and Interpretation of Satellite Oceanographic data（AVISO）的海表面高度异常数据，计算了1992年10月至2007年1月间，全球海平面的平均上升速度，同时详细解算海平面上升速度的全球空间分布，分析全球海平面的变化趋势并将海平面变化同美国国家海洋大气署（NOAA）的Optimum Interpolation Sea Surface Temperature （OISST）海表面温度数据进行了比对和相关分析。  相似文献   

Holocene coastal environmental changes on the periphery of an area of glacio‐isostatic uplift: an example from Scapa Bay,Orkney, UK     

A. C. de la Vega‐Leinert  D. E. Smith  R. L. Jones 《第四纪科学杂志》2007,22(8):755-772

The first detailed investigation of a deep, coastal, sedimentary basin in Orkney reveals a complex Holocene history of back‐barrier morphodynamics. At Scapa Bay, the sea flooded a freshwater marsh after ca. 9400 yr BP at ca. ?5.4 m OD. Before ca. 7800 BP, abundant sediment from nearby cliffs was mobilised inland into a series of gravel barriers across the valley mouth. By ca. 7500 BP, direct marine influence was restricted in the back‐barrier area, although saltmarsh persisted until ca. 5900 BP. By then, at least four gravel ridges had enclosed the backing lagoon, where freshwater inputs became dominant. As terrestrial sediments filled the basin, another freshwater marsh developed. The multiple barrier complex demonstrates progradation resulting from continuous sediment supply in a sheltered embayment. The progressively rising height of the barrier crests seawards probably resulted from a combination of factors such as barrier morphodynamics, increased storminess and long‐term rising relative sea levels. The dominant vegetation surrounding Scapa Bay changed from open grassland to scrub ca. 9400 BP, then to deciduous woodland ca. 7800 BP, and to dwarf‐shrub heath ca. 2600 BP, the latter probably a response to a combination of climate change and human activity. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Frictional heating and pore pressure rise due to a fault slip     

Tien-Chang Lee  Paul T. Delaney 《Geophysical Journal International》1987,88(3):569-591

  相似文献   

Estimating Sea-Level Allowances for Atlantic Canada using the Fifth Assessment Report of the IPCC     

Li Zhai  Blair J.W. Greenan  John Hunter  Thomas S. James  Guoqi Han  Phillip MacAulay 《大气与海洋》2015,53(5):476-490

Abstract

Sea-level allowances at 22 tide-gauge sites along the east coast of Canada are determined based on projections of regional sea-level rise for the Representative Concentration Pathway 8.5 (RCP8.5) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) and on the statistics of historical tides and storm surges (storm tides). The allowances, which may be used for coastal infrastructure planning, increase with time during the twenty-first century through a combination of mean sea-level rise and the increased uncertainty of future projections with time. The allowances show significant spatial variation, mainly a consequence of strong regionally varying relative sea-level change as a result of glacial isostatic adjustment (GIA). A methodology is described for replacement of the GIA component of the AR5 projection with global positioning system (GPS) measurements of vertical crustal motion; this significantly decreases allowances in regions where the uncertainty of the GIA models is large. For RCP8.5 with GPS data incorporated and for the 1995–2100 period, the sea-level allowances range from about 0.5?m along the north shore of the Gulf of St. Lawrence to more than 1?m along the coast of Nova Scotia and southern Newfoundland.  相似文献   

第四纪洞庭盆地安乡凹陷及西缘构造-沉积特征与环境演化     

柏道远  李长安  马铁球  王先辉  陈渡平 《西安地质学院学报》2010,(2):120-129

通过地表观察和钻孔资料,对洞庭盆地安乡凹陷及其西缘第四纪构造沉积特征和环境演化进行了研究,为江汉—洞庭盆地第四纪地质研究补充了新的资料。凹陷总体呈南北向,周边为正断裂。凹陷内第四系厚一般为100-220 m,最厚达300 m,自下而上依次为早更新世华田组、汨罗组,中更新世洞庭湖组,晚更新世坡头组和全新世湖冲积。第四系以砾石层、砂层为主,次为（含）粉砂质黏土、黏土,岩性、岩相横向变化大。安乡凹陷西缘（即太阳山隆起东缘）,呈自西向东缓倾的丘岗地貌。区内主要发育中更新世白沙井组,其中南部下部以砂、砾石层为主,上部为黏土;北部以粉砂质黏土沉积为主,下部可发育砂层。根据地貌、沉积及控凹断裂特征,重塑安乡凹陷及其西缘第四纪构造活动与环境演化过程：早更新世—中更新世早期,凹陷西边的北北东向周家店断裂伸展活动,安乡凹陷不均匀沉降,总体具河流和过流性湖泊环境并接受沅水沉积;同期凹陷西缘构造抬升,处于剥蚀的山地环境。中更新世中期断陷活动向西扩展,凹陷区为过流性湖泊环境;凹陷西缘地区转为河流（南部）和湖泊（北部）环境并接受沉积。中更新世晚期安乡凹陷及其西缘整体抬升并遭受剥蚀,凹陷西缘同时具有自西向东的掀斜。晚更新世安乡凹陷拗陷沉降,具河流和湖泊环境;同期凹陷西缘遭受剥蚀。晚更新世末受区域海平面下降影响,安乡凹陷遭受剥蚀。全新世安乡凹陷拗陷沉降,具泛滥平原之河流、湖泊环境。  相似文献