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1.
本研究通过对长江口现代潮滩6个柱状样沉积物的粒度精细分析,试图提取研究区潮滩沉积相识别的粒度敏感指标,并通过对长江三角洲南部平原一个全新世钻孔(SL67孔)潮滩沉积物的粒度研究,检验现代沉积粒度敏感指标在全新世钻孔潮滩沉积相识别中的应用。研究显示,长江口现代高潮滩和中潮滩的黏性颗粒(8μm)和粗粉砂(32~63μm)含量差异显著,可以成为区分高潮滩和中潮滩的敏感组分;在开敞型的中、低潮滩之间,砂(63μm)和细粉砂含量(8~32μm)也差异明显。长江口现代潮滩沉积物的粒度频率曲线及众数值也可以有效协助区分高潮滩、中潮滩和低潮滩沉积物。利用上述粒度敏感组分和众数指标检验SL67孔全新世早中期在海平面波动控制下的潮滩演替过程,并揭示了7.5 cal ka BP前后的一次海平面加速上升事件。 相似文献
2.
杭州湾潮滩沉积物黏土矿物空间差异与物源指示 总被引：4，自引：1，他引：3
通过对杭州湾潮滩沉积物中主要黏土矿物成分及组合类型的研究,分析了杭州湾潮滩沉积物黏土矿物的空间分布特征。借助聚类分析等手段,同时结合杭州湾水动力特征,探讨了研究区黏土矿物的来源和成因。研究结果表明,杭州湾潮滩表层沉积物主要为黏土质粉砂,其余为砂质粉砂。本区沉积物黏土矿物成分复杂,主要为伊利石,其次是高岭石和绿泥石;还有少量蒙皂石和蛭石及1.4 nm过渡矿物。根据其相对含量可分为3种组合类型:Ⅰ型为伊利石-高岭石-绿泥石-蛭石类-蒙皂石型,Ⅱ型为伊利石-绿泥石-高岭石-蒙皂石-蛭石类型,Ⅲ型为伊利石-高岭石-绿泥石-蒙皂石-蛭石类型。在空间上,北岸的蒙皂石和绿泥石平均含量高于南岸,而伊利石、高岭石和蛭石(含1.4 nm过渡矿物)平均含量则低于南岸。高潮滩和中潮滩黏土矿物对比,除了蒙皂石含量高潮滩大于中潮滩外,其他矿物含量均无明显规律。表层沉积物黏土矿物的分布特征与水动力条件和物质来源密切相关,杭州湾北岸乍浦以东潮滩受潮流和长江沿岸流影响明显,沉积物主要为长江和东海源的;南岸由于曹娥江和甬江两条河流的注入,流域物质所占比例明显比北岸高。柱状岩芯样品中各黏土矿物含量自下而上的变化则反映了物源区风化强度的波动特征。 相似文献
3.
随着海平面上升和人类活动加剧,潮滩正面临着严重威胁,掌握其形态变化规律是研究潮滩系统对外在条件响应的直接手段。以江苏斗龙港潮滩为研究对象,利用无人机倾斜摄影测量技术,结合运动恢复结构(Structure from Motion,SfM)算法,重建潮滩三维点云,生成数字高程模型和正射影像,分析潮滩滩面及潮沟系统年内变化规律。研究结果表明:潮滩高程测量精度优于9 cm,水平精度优于2 cm;高程年内变化较大,变幅高达±0.5 m;潮沟短历时变化剧烈,无明显季节性变化特征;潮沟发育过程中,宽深比范围为10~25。无人机技术不仅可以监测粉砂淤泥质潮滩滩面变化趋势,还可以观测到卫星难以捕获的中小型潮沟短历时发育过程,可为监测河口海岸短周期动力地貌过程提供有力的技术支持。 相似文献
4.
杭州湾是钱塘江河口区外海滨部分,其水动力条件、泥沙运移、沉积过程和地貌演变复杂。根据杭州湾区域遥感影像和地理地形等资料,通过综合分析研究,探讨了杭州湾南、北两岸潮滩的变迁过程。研究表明:杭州湾南、北两岸潮滩的发展程度不同,总体呈现南淤北侵的趋势。 43年来,北岸滩界变动范围基本限制在 1955年潮滩界线之内,潮滩面积呈负增长;南岸扇顶滩界外移 12550m,外移速率达 + 292m/a。潮滩的发展具有空间、时间上的差异性,南岸潮滩淤涨集中在 1955～1963年和 1977～1987年;北岸负增长则集中在 1955～1963年及 1987～1998年。进一步研究还发现:潮滩发育的差异性主要受岸线的空间地貌位置的影响。 相似文献
5.
利用在长江口崇明岛北支北四滧港（SY）、北堡港（BBG）以及新卫村（XW）潮滩获取的表层沉积物,测试总有机碳（TOC）、总氮（TN）及总硫（TS）含量,分析有机地球化学元素在潮滩微相的分布规律及影响因素,试图建立TOC/TN、TS/TOC等潮滩微相识别指标。研究结果显示,影响长江口潮滩TN、TS微相分布的重要因素为有机质含量及类型。在淤涨型潮滩,TOC/TN在高潮滩一般大于10,在中潮滩明显降至10以下;中潮滩植被带TS/TOC最高,平均值达0.063,其次为高潮滩互花米草带和中潮滩光滩（分别为0.055和0.054）,高潮滩芦苇带最低;TS-TOC一元线性回归斜率在高潮滩芦苇带呈现为显著低值,自高潮滩米草带向光滩,逐渐增大。在侵蚀型潮滩,TOC/TN从高潮滩到低潮滩均大于10,而且中、低潮滩的比值大于高潮滩,潮下带骤降至小于10;TS/TOC自陆向海逐渐增大,TS-TOC一元回归斜率高潮滩最低,中潮滩最高。另外,侵蚀型潮滩各微相的TS-TOC一元线性回归斜率均明显低于淤涨型潮滩。上述研究结果表明,长江口沉积物的TOC/TN和TS/TOC及TS-TOC一元线性回归斜率与潮滩沉积微相之间存在一定的关系,具有应用于全新世钻孔识别潮滩沉积物微相的潜力。 相似文献
6.
以长江口崇明岛北支潮滩的3个潮滩为对象,在粒度测量和磁性分析的基础上,揭示了现代潮滩表层沉积物的磁性变化,探讨了磁性矿物、尤其是自生亚铁磁性矿物—硫复铁矿（Fe3S4）在潮滩沉积微相的分布规律及机制。研究结果表明：长江口潮滩表层沉积物的磁性特征由亚铁磁性矿物及超顺磁颗粒(SP)主导。淤积型中高潮滩磁铁矿以单畴(SD)和SP为主,侵蚀型潮滩的中低潮滩则更多假单畴/多畴(PSD/MD)晶粒,反映了水动力的分选及以细颗粒矿物溶解为主的早期成岩作用。此外,最东侧的北四滧港剖面潮上带—高潮滩芦苇带普遍存在自生亚铁磁性硫复铁矿,北堡港和新卫剖面的高潮滩也局部存在硫复铁矿,反映了本区高潮滩—潮上带丰富的有机质及细颗粒沉积物、加上有限的海水淹没时间,是早期成岩作用过程中生成硫复铁矿的主要机制。 相似文献
7.
辽河口海口沉积特征及潮滩动态预测 总被引：6，自引：0，他引：6
本文以翔实的调查资料较详细的叙述了辽河口浅海区的沉积特征,分别总结了潮滩、浅海、潮道及潮沟等单元体的沉积特征,并分析了各单元体的沉积过程,文章重点叙述了潮滩的动态变化,并根据210Pb测定沉积速率资料及河流输沙量观测资料,分别建立预测方程,估算了双台河口东、西两段潮滩的极限淤涨时间及潮滩淤涨高度预测,两种计算方法所获得的结果基本上一致。 相似文献
8.
潮滩沉积物重金属累积特征研究进展 总被引：21，自引：1，他引：21
在分析总结国内外潮滩重金属研究现状和成果的基础上，指出潮滩重金属来源的定量分析尚很不完整；沉积物的物质组成、粒径、水动力作用、潮滩生物、河流输入量、人类活动等都对重金属在潮滩的分布有着重要影响。在垂岸方向，重金属从高潮滩到低潮滩含量逐渐降低，反应了水动力以及粒径对潮滩重金属的分布的控制；沿岸方向，淤涨岸段，重金属含量低，排污口严重影响着重金属的沿程分布，重金属含量随离排污口的距离增大而呈指数减少；垂向方向，在许多地方重金属分布与人类活动、经济发展状况相吻合。生物活动使潮滩重金属的累计特征变得复杂，改变了潮滩局部的微环境。与国内外河口重金属研究相比，潮滩重金属的研究远远不足。沉积物中重金属常用研究方法，如Tes sier地球化学相连续提取法、Meso cosm模型，以及数值和现场模拟的方法的应用，对潮滩重金属的研究将有很大帮助。在潮滩重金属的污染评价中，生物标准较其它标准更为适合。 相似文献
9.
潮滩盐沼物理过程的研究进展综述 总被引：9，自引：2，他引：9
综述了本世纪国外潮滩盐沼堆积、侵蚀机制的研究进展，主要包括潮滩盐沼的粘性泥沙沉积动力机制的分析、对潮滩盐沼的物理过程的详细观测研究、沉积模式研究，以及潮滩盐沼物理过程的知识在海岸防护和其它方面的应用。 相似文献
10.
江苏海岸潮滩沉积环境及其可持续利用问题 总被引：2，自引：1，他引：2
凭借着独一无二的地质、地貌、海洋、气候、土壤和生态特征，江苏潮滩拥有丰富的自然资源，然而却又受着不利自然条件及不合理人类活动的限制。江苏潮滩沉积表现出4个水平相带：草滩(湿地)沉积带、盐蒿泥滩沉积带、泥一砂混和滩沉积带、粉砂滩沉积带。潮滩是极为脆弱的生态系统，它极容易受到湿地围垦、低效的生产方式、酷取滥采、环境污染等人类扰动的破坏。基于以上认识，提出顺应潮滩自然演变，人类活动与潮滩沉积环境的和谐开发利用及保护模式。 相似文献
11.
潮滩沉积的物源一直是沉积学领域重要的研究内容。近30年长江入海泥沙量持续减少,致使长江入海泥沙对浙闽潮滩沉积的物质贡献降低。在此背景下,探究浙闽沿岸潮滩沉积的物源具有重要的现实意义。对杭州湾至福州湾沿岸的泥质潮滩表层沉积开展了详细地磁学研究,结果显示,研究区沉积物的磁性主要受磁铁矿主导,但磁性矿物含量、磁畴和矫顽力等磁性特征存在一定差异,这可能意味着沉积物受到多物源影响。皮尔森相关性分析进一步表明,沉积物磁性特征受粒度效应影响有限,主要与物源差异有关。物源判别结果指示,浙闽泥质潮滩沉积的物源包括长江、海岸基岩和浙闽河流。杭州湾至福宁湾,沉积物普遍受到长江和浙江诸河混合物质的影响,且浙江诸河的物质贡献较大;隘顽湾和象山港沉积物还受到其附近海岸基岩的影响;福宁湾沉积物可能还受到闽江源物质和其附近海岸基岩的影响;罗源湾和福州湾沉积物的潜在物源是闽江和其附近海岸基岩,长江和浙江诸河的物质贡献相当有限。 相似文献
12.
A unique radial tidal sand ridge system (RTSRS) has developed under a complex tidal current field on the eastern China coast
between the Yangtze River delta to the south and the abandoned Yellow River (Huanghe) delta to the north. The present study
examines the sedimentary evolution of a ridge-channel pair in the central RTSRS. Three cores, with two on the ridges and one
in the channel, were drilled to reveal the late Pleistocene-Holocene deposits of the system. Five sedimentary facies were
distinguished, i.e. ridgeshallow subtidal facies, ridge-deep subtidal facies, nearsurface channel bottom facies, middle tidal
flat facies and low tidal flat facies. The ridge-shallow subtidal facies consists of sandy strata with ripple cross beddings,
horizontal lamina, and massive beddings. Bioturbation seldom occurs. The ridge-deep subtidal facies is primarily characterized
by sandy and muddy interlayers with common flaser and lenticular bedding structures. Bioturbation appears abundantly. Massive
and graded sediment sequences of storm origin are present as characterized by rich shell fragments. The nearsurface channel
bottom facies consists of loose, soft, clayey silt deposits with deformed sedimentary layers. This facies occurs in the deeper
part of the active channels. The middle tidal flat and lower tidal flat facies composed of silt-clay couplets prevailed primarily
in the tidal flats. Incomplete sedimentary successions show that coastal plain deposits dominate in the study area during
12–13 ka B.P. The sandy ridge and channel facies became dominant during 4–6 ka B.P. when the sea level receded temporarily.
Tidal ridge and channel in the study area became active during the last four decades. Sediment reworking due to typhoon and
sandy ridge migration plays a key role in shaping the present radial ridge system. 相似文献
13.
In central Wisconsin, Cambrian strata of the Elk Mound Group record deposition on open‐coast, wave‐dominated tidal flats. Mature, medium‐grained quartz arenite is dominated by parallel‐bedding with upper‐flow regime parallel‐lamination, deposited during high‐energy storms that also produced three‐dimensional bedforms on the flats. Abundant wave ripples were produced as storms waned or during fair weather, in water depths ≤2 m. Indicators of variably shallow water (washout structures and stranded cnidarian medusae) and subaerial exposure (adhesion marks, rain‐drop impressions and desiccation cracks, including cracked medusae) are abundant. Parallel‐bedded facies preserve a Cruziana ichnofacies, similar to other Cambrian tidal‐flat deposits. Flats were dissected by small, mainly straight channels, the floors of which were grazed intensely by molluscs. Most channels were ephemeral but some developed low levées, point bars and cut‐banks, probably reflecting stabilization by abundant microbial mats and biofilms. Channels were filled with trough cross‐bedding that is interpreted to have been produced mainly during storm runoff. The strata resemble deposits of open‐coast, wave‐dominated tidal flats on the east coast of India and west coast of Korea. Ancient wave‐dominated and open‐coast tidal flats documented to date appear to have been limited to mud‐rich strata with ‘classic’ tidal indicators such as flaser bedding and tidal bundles. The Cambrian (Miaolingian to early Furongian) Elk Mound Group demonstrates that sandy, wave‐dominated tidal flats also can be recognized in the stratigraphic record. 相似文献
14.
Analysis of 75 vibracores from the backbarrier region of Kiawah Island, South Carolina reveals a complex association of three distinct stratigraphic sequences. Beach ridge progradation and orientation-controlled backbarrier development during the evolution of Kiawah Island, and resulted in deposition of: (1) a mud-rich central backbarrier sequence consisting of low marsh overlying fine-grained, tidal flat/lagoonal mud; (2) a sandy beach-ridge swale sequence consisting of high and low marsh overlying tidal creek channel and point bar sand, and foreshore/shoreface; and (3) a regressive sequence of sandy, mixed, and muddy tidal flats capped by salt marsh that occurs on the updrift end of the island. Central backbarrier deposits formed as a result of the development of the initial beach ridge on Kiawah Island. Formation of this beach ridge created a backbarrier lagoon in which fine-grained estuarine and tidal flat mud accumulated. Washovers, oyster mounds, and tidal creek deposits form isolated sand and/or shell-rich lenses in the lagoon. Spartina alterniflora low marsh prograded into the lagoon as the tidal flats aggraded. Barrier progradation and sediment bar-bypassing at Stono Inlet created digitate beach ridges on the northeast end of Kiawah Island. Within the beach-ridge swales, tidal flats were disconformably deposited on shoreface and foreshore sand of the older beach ridges. Tidal creek drainage systems evolved to drain the swales. These rapidly migrating creeks reworked the tidal flat, foreshore, and shoreface sediments while redepositing a fining-upward sequence of channel lag and point bar deposits, which served as a substrate for salt marsh colonization. This resultant regressive sedimentary package marks the culmination of barrier island development and estuary infilling. Given enough time and sedimentation, the backbarrier sequence will ultimately prograde over the barrier island, reworking dune, beach, and foreshore sediments to form the upper sand-rich bounding surface of the barrier lithosome. Preservation of the regressive sequence is dependent upon sediment supply and the relative rate of sea-level rise, but the reworking of barrier islands by tidal inlets and migrating tidal creeks greatly alter and complicate the stratigraphic sequence. 相似文献
15.
Spatial and depth-wise distribution of sediment components, organic carbon and selected metals (Fe, Mn, Al, Ni, Cr, Co, Zn and Pb) is studied across upper and middle tidal flats from lower and middle estuarine regions of Kundalika Estuary, central west coast of India. Silt and clay form the major components in lower and middle estuary, respectively. Sand, silt, clay and organic carbon showed band-type distribution along the estuary. The sediment deposition over the years took place in varying hydrodynamic conditions in lower and middle estuarine regions. Upper flats of the lower estuary represent mud while middle flats of the lower estuary facilitated the deposition of sandy mud. Correlation results indicated the importance of clay and organic carbon in removal and trapping of metals at lower and middle estuary, respectively. Factor analysis indicated that the distribution of metals is largely controlled by Fe–Mn oxyhydroxides and organic carbon. The middle flats of the lower estuary showed an anthropogenic source for Ni, Cr and Co while middle flats of the middle estuary showed a mainly lithogenic source. 相似文献
16.
基于海洋区域地质调查获取的1 438个粒度数据,利用Folk分类方法将中国东部海域表层沉积物划分为砂质粉砂、粉砂质砂、粉砂、砂、砂质泥、泥质砂、泥7种沉积物类型,阐述了不同沉积物类型的粒度组成和参数特征.其中,砂质粉砂、粉砂质砂和粉砂是3种最主要的沉积物类型,分别占样品总数的34.70%、24.20%和15.51%.粉砂质砂呈条带状分布在研究区的南部且向北延伸.粉砂主要分布在长江口-浙闽沿岸、渤海西部和南黄海中北部.砂主要分布在东海外陆架、扬子浅滩和苏北浅滩、朝鲜湾等海区,其中在东海外陆架海区分布最广.影响沉积物分布的主要因素有物源、水动力环境以及水深、地形、地貌等.晚第四纪冰期旋回中海平面变化和海洋环流控制陆源沉积物的入海通量和陆架沉积体系的发育过程.综合沉积物物源供给、海洋环流、冰后期海平面变化过程,基于Folk分类的动力学属性和表层沉积物类型分布,将中国东部海域表层沉积物分布划分为河口沉积、陆架泥质沉积、潮流沉积以及残留沉积等分区.不同沉积分区的形成机制和影响因素差异显著,反映出在中国东部陆架的特殊地形影响下,不同海平面时期陆源碎屑物质的运移过程. 相似文献
17.
渤海湾西部表层沉积物粒度特征与沉积混合 总被引：2，自引：0，他引：2
根据渤海湾西部135个表层沉积物样品的粒度分析结果,分析了表层沉积物的粒度特征与规律。整体上由研究区东北部沿海岸向南沉积物粒度变细,由砂和粉砂质砂变为砂质粉砂,再变为粘土质粉砂。沉积物粒度频率曲线显示,由研究区东北部至北部,沉积物粗组分含量减少,由单峰逐渐过渡为主峰或弱峰,到中部粗组分减少为粗尾形态,到南部粗组分几乎缺失;而沉积物细组分的变化趋势则与之相反。沉积物粗组分在粒度频率曲线上的表现由单峰逐渐过渡至主峰或次峰,粗峰含量减少,到中部粗组分减少为粗尾形态,到南部粗组分几乎消失;而沉积物细组分的变化趋势则与之相反。沉积物粒度参数的平面分布规律和粒度参数之间的相关性变化形态显示出粗细2种母质组分以不同比例的沉积混合的特征,即来自东北部的粗组分与来自南部的细组分发生混合,这可能主要与区内双向的沿岸环流输运有关。 相似文献
18.
江苏王港潮间带表层沉积物特征及输运趋势 总被引：20，自引：1，他引：19
潮滩沉积物粒度参数可以用来反映沉积物沉积的水动力条件和沉积环境。根据对江苏王港潮间带采集的15 4个表层样品的粒度资料进行分析,结果表明,沉积物类型以粉砂为主;随着水动力环境由海向陆的减弱,沉积物粒度参数表现出有规律的变化趋势,即由岸向海粒径具有粗化趋势,分选变好,逐渐正偏并达到近对称。研究区与世界其他地区的潮滩在沉积特征上有较大差异,主要是由于沉积物来源、水动力环境及受生物作用的强弱程度不同所致。沉积物输运趋势分析显示,该地区沉积物输运主要受当地潮波特征、大型人工建筑物、地貌形态及生物作用的影响;在低潮线附近主要向西北方向输运,随着向陆地方向的延伸,沉积物由向西输运逐渐转变为向南输运。 相似文献