滦河三角洲海岸潮汐汊道——潮盆体系的演变   总被引：2，自引：0，他引：2  

张忍顺  李坤平 《海洋工程》1996,(4)

近二千年以来，滦河尾闾从西向东迁移，形成了由不同时期的亚三角洲互相叠复而成三角洲体系。丰富的入海泥沙和弱潮环境使该三角洲海岸发育了我国较为完整的潮汐汊道——潮盆体系群。尽管滦河三角洲与密西西比河三角洲有诸多相异之处，但动力泥沙条件的某些相似性使它们的汊道潮盆体系的演变可以进行类比。研究表明，决定潮汐汊道——潮盆体系发育阶段的是它所在的亚三角洲的废弃年龄。从狼窝口到湖林口的各亚三角洲均处于演变的第一阶段。即以受蚀陆岬及其沙咀状堡岛为特色的第一阶段。而大清河口附近则处于以堡岛弧为代表的第二阶段。目前，曹妃甸附近的亚三角洲正在向第三阶段，即堡岛演化为内陆架浅滩的阶段演化。从现代滦河口向曹妃甸，对应于废弃年龄的增加，潮汐汊道分别属于五种类型，即新生波浪型、新生过渡型、潮汐型、老年过渡型及老年波浪型  相似文献   

Three‐dimensional to two‐dimensional cross‐strata transition in the lower Pleistocene Catanzaro tidal strait transgressive succession (southern Italy)     

Sergio G. Longhitano  Domenico Chiarella  Francesco Muto 《Sedimentology》2014,61(7):2136-2171

Sandstone tidal cross‐strata are the predominant sedimentary feature of strait‐fill stratigraphic successions. However, although widely described in numerous studies, tidal strait‐fill two‐dimensional and three‐dimensional cross‐strata have rarely been reported to occur in discrete intervals which are laterally adjacent or vertically stacked, and the meaning of this stratigraphic architecture has not yet been fully investigated. Understanding of the processes responsible for changes in the internal features of modern and ancient tidal bedforms is essential in order to predict lateral and vertical heterogeneities in analogous reservoir strata. This facies‐based study aims to interpret the three‐dimensional to two‐dimensional cross‐strata transition observed in the lower Pleistocene mixed siliciclastic/bioclastic sandstone filling the Catanzaro Strait, in southern Italy, during a continuous phase of tectonically driven marine transgression. Tidal cross‐strata disappear in the uppermost interval of the studied succession, where mudstone strata prevail. This stratigraphic trend is interpreted as the evidence of an important change in the tidal strait hydrodynamics due to a phase of relative sea‐level rise. At the beginning of the transgression, three‐dimensional tidal dunes migrated throughout the ca 3 to 4 km wide and ca 30 km long, WNW–ESE‐oriented Catanzaro Strait, due to strong tidal currents amplified through the seaway and flowing in semi‐diurnal phase opposition. As the intermediate phase of transgression enlarged the seaway width, the tidal current strength decreased as tidal water exchange occurred over a larger cross‐sectional area. The progressive reduction of the bed shear stress modified three‐dimensional tidal dunes into an extensive two‐dimensional bedform field. At the end of the transgression, the further widening of the Catanzaro Strait into a ca 10 to 12 km wide marine passageway changed the tidally dominated strait into a non‐tidal open shelf. The results of this research suggest the presence of a ‘critical cross‐sectional area’ in the narrowest strait‐centre zone which controls the activation and deactivation of tidal current amplification along a marine seaway.  相似文献   

海上地震资料处理中的潮汐静校正处理研究及应用     

杨薇  朱江梅  张兴岩  黄莉娜 《物探化探计算技术》2014,(3):331-334

海水因为受月亮引力的作用会产生潮汐现象,在海上地震资料中表现为假断层现象,这种现象会影响地震资料的成像质量,导致错误层位解释及储层预测,因此在地震资料处理中,需要进行潮汐静校正处理。这里讨论了如何应用海上采集的高程值计算出地震波来回通过基准海平面与放炮时海平面之间的薄层水体所经历的时间,再将全部地震数据都校置在同一观察平面,从而实现潮汐静校正处理的方法,并应用于海上某工区中,得到较为理想的效果。  相似文献   

黄河三角洲潮滩的侵蚀和再沉积:示踪砂棒法的应用   总被引：1，自引：0，他引：1  

周良勇  高茂生  徐刚  苏大鹏 《地质通报》2014,33(10):1602-1608

利用示踪棒方法,对现代黄河三角洲潮滩的半年和整年的再沉积进行了定量测量,分析了潮滩沉积动力的影响因素。测量结果显示,尽管潮滩地形平均变化值只有1cm左右,但是平均沉积交换量(侵蚀和再沉积之和)是它的10倍。因此,潮滩地形处于基本稳定状态,但是无论是北侧还是南侧潮滩,都存在强烈的物质交换。对比结果表明,北侧潮滩沉积交换最强,且主要发生在下半年。北侧潮滩每年的沉积交换量为15~33cm。南侧潮滩沉积交换量次于北侧潮滩,上半年和下半年的沉积交换量相当。东侧潮滩沉积交换最弱。影响沉积交换和再沉积的原因包括海洋动力、河流输沙、局部地形特征、海滩植被、海滩蟹类活动、人工突堤等,此外气候(冰冻)也影响北侧潮滩沉积交换。  相似文献   

天津潮间带高程现状与滨海新区城市安全   总被引：2，自引：2，他引：0  

王福  裴艳东  李建芬 《地质通报》2010,29(5):682-687

通过6条潮间带水准测量剖面,对天津滨海新区潮间带的高程及坡度进行了测量和计算。结果显示:人工岸线(海堤、海防公路等)与滩面交汇处的高程为+0.22m~+0.73m(1956黄海高程);天津潮间带的平均坡度为1.25‰,海河南侧滩面的平均坡度为1.09‰,较北侧1.33‰小,海河北侧从蛏头沽剖面(1.21‰)到大神堂剖面(1.58‰)滩面坡度呈现变大的趋势;结合潮位观测数据,获得了潮间带的出落宽度,永定新河潮间带最宽,为1730~1810m,大神堂潮间带最窄,为1090~1160m。与20世纪80年代对比,滩面已变陡、变窄。进一步的滩面高度与潮位对比发现,滩面与人工岸线交汇处的高程均低于平均高潮位,揭示了海防设施受到海水直接影响的现状。海防设施真正地成了保护城市的唯一屏障,因此应该进一步加高、加固海防设施,提高防灾等级。  相似文献   

Comparison between Different Models of Galactic Tidal Effects on Cometary Orbits     

Marc Fouchard  Christiane Froeschlé  John J. Matese  Giovanni Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):229-262

Different models of the action of the galactic tide are compared. Each model is a substitute for direct numerical integrations allowing a drastic decrease of the computation time. The models are built using two different techniques, (i) averaging of the fast variable (the mean anomaly) over one cometary period and (ii) fixing the comet in its aphelion direction. Moreover, we consider two different formalisms (Lagrangian and Hamiltonian) and also two different sets of variables. As expected, we find that the model results are independent of the formalism and the set of variables considered, and are highly accurate, whereas mathematical technique leads to poor results. In order to further reduce the computation time, mappings are built from the development of the solution of the models. We show that for these mappings, the set of variables giving the most accurate results is strongly dependent on the cometary eccentricity, e, and semimajor axis, a.  相似文献   

曹妃甸老龙沟潮汐通道拦门沙演变机制   总被引：2，自引：0，他引：2  

季荣耀  陆永军  左利钦 《水科学进展》2011,22(5):645-652

渤海湾曹妃甸老龙沟海区属于泻湖型潮汐通道体系,口门附近发育有大规模拦门沙浅滩。由于沿岸泥沙供给不足,近几十年来东坑坨等沙坝外侧海区整体呈侵蚀冲刷态势,等深线向陆蚀退。老龙沟西支深槽也以侵蚀作用为主,而拦门沙地区滩槽冲淤变化则与东坑坨演变密切相关。其中东槽冲刷发展主要是东坑坨西南尾端淤长压迫老龙沟口门,引起岬角效应增大、潮流动力增强所致,而西槽的摆动现象则主要与东槽发展所产生的挤压作用有关。由于泥沙供给不足,近年来东槽发展和西槽摆动的速度都有明显减缓。  相似文献   

内蒙古阿尔山地区下寒武统苏中组混合沉积特征及形成环境研究   总被引：2，自引：0，他引：2  

曹桐生  田景春  朱迎堂  赵荣华  解惠  田江飞  杨辰雨 《沉积学报》2011,29(1):55-63

以内蒙古阿尔山地区下寒武统苏中组为研究对象,综合区域地层、岩石结构、剖面特征、粒度分布特征,对苏中组碳酸盐岩夹碎屑岩的沉积环境进行了深入分析.从粒度分布特征来看,苏中组砂岩粒度分布表现出双峰和多峰不对称,偏度以正偏为主,峰度数值多且比较低,分选性差,以粗粒物质为主等特征;运用萨胡图解投点、判别函数计算确定内蒙古阿尔山地...  相似文献   

对华北中元古代海侵初期"河流相"沉积的重新认识:以天津蓟县剖面为例   总被引：1，自引：0，他引：1       下载免费PDF全文

钟焱  赵亮东  陈留勤  梅冥相 《古地理学报》2011,13(1):21-29

作为中元古代海侵初期一套厚达400余米的非成熟含砾砂岩地层,常州沟组第一段曾被解释为一套河流相沉积序列.然而,来自于蓟县剖面的实际资料表明需要重新审视前人的解释.在蓟县剖面常州沟组最底部的含细砾粗砂岩中,双向交错层理及冲刷面的频繁发育表明了其具有潮汐作用的沉积特点,这种认识否定了海侵初期大面积发育河流而衍生出的"河侵"...  相似文献   

曹妃甸老龙沟动力地貌体系及演化   总被引：3，自引：0，他引：3  

黎刚  孙祝友 《海洋地质与第四纪地质》2011,(1):11-19

老龙沟为典型沙坝-泻湖型潮汐汊道,潮汐汊道地貌结构完整.老龙沟口门处潮流动力最强,发育-20m的深槽.口门内涨潮流三角洲上发育完整的多级水道体系.口门外落潮三角洲止于-11 m水深处.以突起的末端坝为地形标志,落潮主水道偏于落潮三角洲东侧发育,落潮三角洲西侧发育宽缓冲流平台.落潮主水道以落潮流为优势,冲流平台上潮流动力...  相似文献