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1.
海岸现代风成砂粒度参数特征的研究--以中国温带海岸为例 总被引：6，自引：1，他引：6
现代海岸风成砂的粒度特征是海岸风沙研究的重要问题,本文以我国温带海岸为研究区域,利用 136个现代海岸风成砂样数据,通过粒度组成、平均粒径、标准偏差和偏差、峰态等粒度参数分析了其粒度特征。结果表明,我国温带海岸的现代风成砂并非过去认为的几乎全由分选很好的细砂组成,是以正偏为主,粒度参数的地域差异明显,并随沙丘类型、规模及距海岸线的远近不同等而变化。与海滩砂比较,风成砂具有普遍含有粉沙、略细、多正偏、峰态偏窄等特点,但利用粒度参数散点图和因子分析法二者均无法区分。我国温带海岸现代海岸风成砂粒度参数的上述特征与其特有的发育条件和演化过程密切相关,其中主要与季风气候特征显著、形成时间短、风力作用时间有限以及风沙活动空间狭小并受到水力与重力作用的干扰等有关。 相似文献
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胡杨回涡沙丘是别里库姆沙漠常见的一种风积地貌类型,通过测试分析来自6个样区胡杨回涡沙丘的195个表层沉积物样品,结合粒级-标准偏差法、Sahu成因判别和相关统计分析法,对其粒度特征进行研究,以分析别里库姆沙漠表层沉积物类型、沉积环境的稳定性。结果表明:(1)胡杨回涡沙丘表层沉积物粒度组成以砂和粉砂为主,从北向南、从东向西沉积物粒级均呈现变细趋势。(2)6个样区平均粒径的均值属于极细砂或细砂范围,71.79%的物质样品分选较好,97.94%的沉积物样品属于近对称分布,100%的物质样品属于中等峰态。(3)6个样区的粒级-标准偏差曲线均呈现多峰分布,沉积环境不稳定。(4)6个样区胡杨回涡沙丘表层沉积物的Sahu成因判别值介于-7.277~ -5.912,均属于风成沉积。 相似文献
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海岸沙丘表面现代风成沙地球化学元素分异的典型研究--以河北昌黎黄金海岸横向沙脊为例 总被引：2，自引：0，他引：2
在我国海岸沙丘主要分布地区河北昌黎黄金海岸选取代表性的海岸横向沙脊为研究对象,对其典型断面上沙丘表面不同部位的21种地球化学元素的含量进行了比较分析。结果表明,Co、Zr和Mg三种元素在海岸沙脊表面不同部位的含量差异明显且与海滩沙相比含量差异较大,Cr、Pb、Ti、Nb、As、Mn、Zn和Ba等8种元素的含量差异程度中等,但Y、Ca、Fe、Na、Al、Sr、P、K、Rb和Si等10种元素的差异并不明显,而11种差异程度中等以上元素在海岸横向沙脊迎风坡脚、迎风坡、脊顶、背风坡、背风坡脚等部位的含量变化特征并不一致,呈现出不同的分异模式,其主要原因是受沉积环境、化学元素性质、粒度特征及营力的影响等。 相似文献
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库布齐沙漠南缘抛物线形沙丘表面粒度特征 总被引：5，自引：0，他引：5
对库布齐沙漠南缘抛物线形沙丘特征断面上下层（0~5cm、5~10cm）沉积物采样分析结果表明,沙丘粒径与分选参数及其分布随沙丘形态、发育程度和植被生长状况发生变化。抛物线形沙丘丘体迎风坡下凹背风坡上凸,丘顶始终处于侵蚀亚环境。在顺风向断面,平均粒径从迎风坡脚到丘顶变粗,从丘顶到背风坡脚又变细,且这种变化在高大沙丘上更为明显;分选性在迎风坡为中等和较好,丘顶较差,顺风向到背风坡脚逐渐由中等变为较好;粒径频率曲线在丘顶双峰正偏,除迎风坡脚单峰正偏外,其余部位均单峰近对称。在垂直于风向的两翼断面,平均粒径在成熟沙丘由翼顶向两侧坡脚趋于变细,而在欠成熟沙丘无明显的变化趋势。翼间平地沉积物受植被等影响,平均粒径偏细但分选性差,偏度为正偏和极正偏,峰度为尖锐和非常尖锐。受不同时期风况的影响,成熟抛物线形沙丘上下层粒度参数在沙丘断面的分布较欠成熟沙丘一致。 相似文献
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南极长城站区松散沉积物的粒度特征及环境意义 总被引：6，自引：0，他引：6
南极长城站区地表松散沉积物按成因分为冰碛、冰缘沉积、冲积、湖积和海岸沉积。对其部分沉积的３．５２ｍｍ以下粒度分析表明，其粒度特征有明显的差别，能很好地反映其形成过程和环境特征。按冰缘沉积、冰碛、冲积和海岸沉积的次序，其粒度组成中砂粒级的含量增加，粉砂和粘土的含量减少；分选性由分选差变为分选较差和分选好；平均粒径分别落在极细砂、细砂、中砂和粗砂粒级；偏度由极正偏变为近对称。粒度参数散点图中各种沉积物的分布有明显的区别。粒度频率曲线的差别能很好地反映沉积物各自的形成过程特点。而冲积和海岸沉积服从正态概率分布，其累积图表现为直线形；冰缘沉积和冰碛服从罗辛概率分布，在累积图中表现为直线形 相似文献
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福建长乐东部海岸沙丘发育成因及特征 总被引：2，自引：0，他引：2
通过对长乐东部沿海海岸沙丘的形成及其发育成因进行分析,认为风况、沙源和地形空间是形成该地区海岸沙丘的基本条件。另外,根据沙丘的空间组合、形态特征、地貌特点等,对该地区的海岸沙丘分布形态进行了进一步的分类阐述。 相似文献
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以2000年及2007年黄河三角洲滨海区采集的123和155个表层沉积物样品为数据基础,经实验室分析取得各样品的粒度参数,结合地貌条件、动力条件和水深资料,探讨黄河三角洲滨海区沉积物的分布类型、粒度特征以及其动力分区等方面的规律。黄河三角洲滨海区表层沉积物类型主要为砂质粉砂;中值粒径由岸向海逐渐变细;分选系数整体偏高反映了的复杂性;偏态值均为正,其极高值大都分布于水深10m左右的区域;峰态的极大值分布于现行河口的南侧,极小值分布于湾湾沟口和飞雁滩以东的近岸。Flemming三角图反映出冲蚀区的动力条件整体较强;淤积区内清水沟老河口附近的动力条件比现行河口强;浅海平原区水动力较弱且单一。 相似文献
8.
冲绳海槽南部沉积层序的粒度特征 总被引：2，自引：1，他引：2
对取自冲绳海槽南部的A2 3孔经前处理后的沉积物样品进行了粒度测试,探讨了陆源沉积层序的粒度特征。沉积物平均粒径、分选系数、偏态、峰态等粒度参数的变化显示出A2 3孔的沉积层序以 4 0 0cm为界可分为上、下两段,下段各参数稳定,代表了比较稳定的水动力条件的沉积环境;上段则波动较大,小规模浊流沉积频繁发育,暗示了不稳定的沉积环境。浊流层内粗粒与细粒组分含量及粒度分布的变化具有明显的规律性。通过分析A2 3孔陆源沉积层序的各沉积参数特征,认为冲绳海槽南部的沉积环境和动力在时间尺度上有较大的变化,东海陆架物质向南部海槽的输运可能是以峡谷为通道的重力作用引起的床底沉积作用为主。另外,对陆源碎屑和全样粒度结果的对比,显示了前处理方法对于海洋沉积物粒度分析的重要性. 相似文献
9.
云南西北部丽江—剑川地区古近纪宝相寺组
石英砂颗粒表面特征 总被引：1，自引：0，他引：1
石英砂具有丰富的颗粒表面特征,是判别沉积环境的重要标志。利用扫描电镜对云南丽江—剑川地区宝相寺组(E2b)的石英砂颗粒表面特征进行了系统分析:下部样品具水成特征,中部样品具风成特征,上部样品则具经水流改造后的风成特征。结合野外观察结果,从宝相寺组石英砂颗粒表面特征的变化规律可以看出,下部为近源洪积环境、中部为风成沙丘环境、上部为湖泊环境。其中中部样品的石英砂磨圆、分选极好,普遍具有标准的碟形、新月形撞击坑和毛玻璃化表面,是典型的沙漠砂沉积。 相似文献
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FIKRY KHALAF 《Sedimentology》1989,36(2):253-271
Several types of aeolian deposits have been recognized in Kuwait: (a) smooth sand sheets that resemble desert floor sand, (b) immobile sands that include rugged vegetated sand sheets and wadi fill deposits, and (c) mobile sands that form active sand sheets and sand dunes. Simple size frequency curves illustrate the genetic relationship between the various aeolian sediment types. The four size parameters, namely, mean size, sorting, skewness and kurtosis, were calculated. Scatter plot diagrams of sorting versus mean size and sorting versus kurtosis are effective in differentiating smooth sand sheet deposits from dune sands. Active sand sheet deposits can also be recognized because they are usually located between the two end members–smooth sand sheets and dune sands. Size parameters change with location regardless of their types. Coarsening and positive skewness usually increase downwind. Mineralogical and textural characteristics of the aeolian deposits in Kuwait revealed that they are mostly derived from the lower Mesopotamian muddy flood plain deposits, the sand fraction of the Al-Dibdibba gravelly deposits and the disintegrated material from calcretic and gypcretic duricrusts. Distribution of depositional and deflational areas indicates that the northern desert of Kuwait is characterized by a positive sand budget, whereas the southern desert has a negative sand budget. 相似文献
12.
华南海岸沙丘岩的特征及其形成发育模式 总被引：10，自引：0，他引：10
海岸沙丘岩是一种热带、亚热带干旱及季节性湿润地区特有的碳酸盐胶结的风成碎屑岩。本文对华南沿海沙丘岩的沉积结构、沉积构造特征,地球化学与古生物特征,及其胶结类型、成岩机制和发育模式进行了较系统研究,并讨论了与海滩岩的区别。 相似文献
13.
The origin of the Tertiary ‘red clay’ underlying the Pleistocene loess in the Chinese Loess Plateau remains controversial, although several lines of evidence have suggested a wind‐blown origin. This study examines the particle‐size parameters of the late Miocene and Pliocene ‘red clay’ by comparing it with those of the late Pleistocene loess. The particle‐size distribution of a total of 15 339 loess and 6394 ‘red clay’ samples taken from 12 loess sections along a north–south transect and two ‘red clay’ sequences at Lingtai and Jingchuan was systematically analysed. The median grain size, skewness and kurtosis of the late Pleistocene loess all show a systematic southward change and are principally influenced by distance from source region. The spatial and temporal differentiation of dust deposits is expressed in a skewness–kurtosis–median grain size ternary diagram, from which the distance to the source region can be inferred. The particle‐size characteristics of the Tertiary ‘red clay’ sediments are very similar to those of the palaeosols within the late Pleistocene loess deposits, suggesting an aeolian origin for the ‘red clay’. Based on the comparison of ‘red clay’ and loess in the ternary diagrams, it is inferred that the source–sink distance was greater in the Neogene than in the last and penultimate interglacials, and that the dust source region in north‐western China underwent a progressive expansion during the period from at least 7·0 Ma to the present. 相似文献
14.
东北平原东部天恒山钻孔的粒度特征及其对地层划分的指示 总被引：2，自引：2，他引：0
东北平原东部荒山剖面是我国东北地区的第四纪典型剖面,但针对该剖面的地层划分和成因的研究尚存在不同看法,对其开展详细的粒度特征研究有望对该剖面的地层划分和地层成因提供进一步的认识。通过天恒山（THS）钻孔对该区地层进行高分辨率的粒度特征研究,并与黄土高原典型黄土进行对比。研究结果显示哈尔滨组地层平均粒径、中值粒径以及粒级百分含量等大幅度波动,呈现黄土-古土壤地层旋回变化特征,黄土层粒度粗,古土壤层粒度细,与黄土高原典型第四纪黄土的粒度特征一致。荒山组地层则呈现小幅度波动,沉积动力较稳定。哈尔滨组和荒山组的粒度频率分布、C-M图及粒度参数（平均粒径、标准偏差、偏度、峰度）等特征均存在显著差别,指示二者的沉积动力过程明显不同。基于以上粒度特征,结合沉积相特征和已有划分方法,THS钻孔中-晚更新世地层自上而下可划分为哈尔滨组和荒山组,并将哈尔滨组地层判定为风成堆积,将荒山组地层判定为河湖相沉积。 相似文献
15.
Yahya Mohammed Sheikh Abolkhair Ph.D. 《GeoJournal》1986,13(2):103-109
The paper analyses the statistical parameters of the sand grain size distribution of Al-Ubaylah barchan dunes applying the sieving technique and Folk and Ward, and Trask's equation. The results of the sieving analysis divulged that nearly over 90% of the sand particles fall in the size ranging between 1.50ø and 3.ø. Insignificant amount of sand grains also fall in the size ranging from 0.0ø to 1.50ø and from 3.0ø to 4.0ø respectively. The statistical analysis reveals that the sand is characteristically fine grained, moderately to moderately well sorted with an average diameter of 2.4ø and a standard deviation of 0.64ø. The sand distribution is positively fine skewed and mesokurtic to leptokurtic in nature. No significant variation in the statistical parameters (median, mean, sorting, skewness and kurtosis) of the sand grains samples used in this research is detected. The sand grain size distribution of all the samples can also be considered symmetrical and unimodal in nature. Those abovementioned characteristics are found to be nearly similar to that of other Saudi dune deserts. The miscroscopic investigation undertaken by this researcher displays that quartz represents often more than 99% of the samples. Felsic, mafic and calcium carbonates minerals represent less than 1% of the mineralogical constituents. The sand grains are subrounded to subangular and iron and calcium carbonates coated. 相似文献
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福建省漳州市第四纪沉积物粒度特征及其沉积环境 总被引：5，自引：0，他引：5
对福建省漳州市不同沉积相带(河道沉积相带和海湾沉积相带)的两个钻孔进行详细的第四纪沉积物激光粒度分析,综合研究区内代表性钻孔的岩性和岩相等资料,得出了研究区第四系沉积环境及其演化的认识。采用MS-2000型激光粒度分析仪进行测试,对测试数据进行整理和分析,绘制出频率曲线图、概率累积曲线图和粒度众数分布曲线图等,并进行沉积环境的解释。在粒度分析曲线解释意义上,提出激光粒度分析方法做出的粒度众数曲线能够较灵敏地反映沉积环境及其水动力条件的变化,可以作为环境分析的辅助手段。在环境解释方面,漳州盆地第四纪环境演化经历了:①晚更新世中期龙海组冲洪积;②晚更新世晚期东山组冲积;③全新世早、中期长乐组下部海积;④全新世晚期长乐组上部洪冲积的演变过程。 相似文献
18.
Sedimentology, stratigraphy and landscape evolution of a Holocene coastal dune system, Lodbjerg, NW Jutland, Denmark 总被引：1，自引：0，他引：1
The stratigraphy and landscape evolution of the Lodbjerg coastal dune system record the interplay of environmental and cultural changes since the Late Neolithic. The modern dunefield forms part of a 40 km long belt of dunes and aeolian sand‐plains that stretches along the west coast of Thy, NW Jutland. The dunefield, which is now stabilized, forms the upper part of a 15–30 m thick aeolian succession. The aeolian deposits drape a glacial landscape or Middle Holocene lake sediments. The aeolian deposits were studied in coastal cliff exposures and their large‐scale stratigraphy was examined by ground‐penetrating radar mapping. The contact between the aeolian and underlying sediments is a well‐developed peaty palaeosol, the top of which yields dates between 2300 BC and 600 BC . Four main aeolian units are distinguished, but there is some lateral stratigraphic variation in relation to underlying topography. The three lower aeolian units are separated by peaty palaeosols and primarily developed as 1–4 m thick sand‐plain deposits; these are interpreted as trailing edge deposits of parabolic dunes that moved inland episodically. Local occurrence of large‐scale cross‐stratification may record the head section of a migrating parabolic dune. The upper unit is dominated by large‐scale cross‐stratification of various types and records cliff‐top dune deposition. The nature of the aeolian succession indicates that the aeolian landscape was characterized by alternating phases of activity and stabilization. Most sand transported inland was apparently preserved. Combined evidence from luminescence dating of aeolian sand and radiocarbon dating of palaeosols indicates that phases of aeolian sand movement were initiated at about 2200 BC , 700 BC and AD 1100. Episodes of inland sand movement were apparently initiated during marked climate shifts towards cooler, wetter and more stormy conditions; these episodes are thought to record increased coastal erosion and strong‐wind reworking of beach and foredune sediments. The intensity, duration and areal importance of these sand‐drift events increased with time, probably reflecting the increasing anthropogenic pressure on the landscape. The formation of the cliff‐top dunes after AD 1800 records the modern retreat of the coastal cliffs. 相似文献