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1.
The method and results of the study of granulometric composition of sediments of the Anapa bay bar are presented in this work. Along the extension, the Anapa bay bar hosts several areas with distinct granulomentric composition of sediments. The coastal variability of the bottom sediments is less expressive relative to land sediments and the pattern of the coastal distribution of granulometric composition reflects the local differences of hydrolithodynamic conditions of individual areas of the bay bar. These data are important for understanding the present-day lithodynamic processes and evolution of the geosystem of the Anapa bay bar. 相似文献
2.
《Marine Geology》2007,236(1-2):45-59
Titanomagnetite forms rich placer deposits along the northwest coast of New Zealand. These deposits were sampled along 3 shore-normal transects spaced over the southern 2 km of a dissipative high-energy beach on the west coast in 5 field campaigns covering one year. The percentage of opaque minerals (mainly titanomagnetite) was extremely high in the upper 30 m of the beach face, extending seaward where these opaque minerals were gradually replaced with variable amounts of lighter augite, hornblende and plagioclase. The pattern appeared to be divided into two regions, a lower seaward and an upper landward region, separated by a point where either marine dominated over aeolian processes or where swash dominated over breaking processes. In the seaward region, the percentage of opaques increased and particle size fined landward as undertow removed the lighter larger particles seaward. In the landward region, the percentage of opaques and particle size were more constant, or even showed the reverse pattern as wind transported the lighter material shoreward, or swash asymmetry transported the heavier material seaward. The similarity of settling velocities over the whole beach face suggests that sorting by size rather than weight plays a dominant role in separating the mineral assemblages. Considerable variations existed between transects. This could be explained by the spatial changes in surfzone waves and currents that were associated with proximity to the southern headland and various rip current channels that characterised this dissipative site. Surprisingly, the percentage of opaques decreased when the wave conditions of the day of sampling were more energetic. In contrast to many other placer deposits, these deposits are abundant on the beach face, forming an armouring layer during lower wave energy conditions. During higher wave conditions, the surface layer erodes allowing lighter augite, plagioclase and hornblende to be released from the sediments below. 相似文献
3.
Oceanology - Abstract—The paper describes the composition of bottom and beach sediments of the large accumulation form (the Anapa bay-bar). It has been shown that the sand particles size... 相似文献
4.
The results of field studies of the beach dynamics and the continental slope (over the depth range from 0 to 5 m) of the Anapa
spit barrier that were carried out in 2002–2005 using ten lateral profiles are presented. The analysis of the location of
the submarine ridges based on the data of 1992 up to a depth of 11 m has shown that the configuration thereof facilitates
the transport of sediments to the southeast, thus bypassing Cape Anapa. No resultant accumulation of beach-forming sediments
on the southeastern flank of the spit barrier occurs within the submarine slope bordering the high coast, thus provoking the
active erosion of the town beach over the last 25–30 years. The main reasons for this are the tectonic deformation of the
coastal region and the submarine slope between the harbor and the central part of the town beach, as well as the change in
the azimuth orientation of the resultant waves from 135° in the 1960s–1970s to 210° over the past decade. The relatively stable
coast and the regions of intense erosion of the accumulative body of the Anapa spit barrier were revealed on the basis of
the measurements and the analysis of the topographic data. 相似文献
5.
1 IntroductionKnowledge of suspended particle size and distri-bution is the key elements for better understandingthe sediment transport processes ( Wang et al.,2004), primary production (Ning et al., 2004),water quality controlling and pollution predictio… 相似文献
6.
通过对诏安湾海域6个站位的水文泥沙观测和181个表层沉积物样品的粒度分析,结合海湾水深地形,应用Gao?Collins粒径输运模型和系统聚类分析方法,分析研究了福建诏安湾海域的粒度参数分布特征、表层沉积物的运移趋势和沉积环境划分及其动力机制.结果表明,诏安湾表层沉积物共6种类型,以黏土质粉砂和砂为主,平均粒径介于0.5... 相似文献
7.
8.
This paper attempts to highlight issues that are relevant in the application of the Parabolic Bay Shape Equation (PBSE) to a non-equilibrium bay. For this case, the bay of Imbituba in southern Brazil was chosen. The construction of a breakwater to shelter the port of Imbituba in the south of the bay was accompanied by an increase in sedimentation to the port area from an eroding downdrift beach. Superimposed plots of the coastline of the Bay of Imbituba from different years confirm a general trend of accretion of the southern part of the bay accompanied with a retreat of the coastline in the northern part. After the application of the PBSE it became clear that the breakwater caused a change in the equilibrium state of the bay. Between 1947 and 2001 the Bay of Imbituba has changed from a dynamic equilibrium to a natural beach reshaping or self-reshaping. The tendency of the sedimentation of the southern part of the bay can be explained by the SEP associated with the new updrift diffraction point (tip of the breakwater): The seaward position of the SEP predicts a need for additional sediment in order to achieve a stable plan form. 相似文献
9.
During deposition in the Palaeogene, the Pearl River Mouth Basin (Enping Sag) was filled by sediments derived from northern and southern source regions. The northern sources are the fold belt Caledonian and Hercynian metamorphic rocks that are widely exposed along the South China block and stacked with Mesozoic igneous rocks, and the southern sources are Mesozoic igneous rocks from the southern Panyu lower uplift. We analysed the characteristics of the provenance and sediment-dispersal patterns of the beach and bar systems in the Palaeogene third-order sequence framework on the basis of detritus, thin section, zircon and the geophysical response test data. The source and deposition areas were distinguished based on their palaeogeomorphology. The sedimentary material composition of the deposition area was determined based on the characteristics of the detrital assemblage and cathode luminescence, and the characteristics of the age distribution were determined in detail using detrital zircon U–Pb dating. This study suggests that the provenance system in the Palaeogene mainly consisted of Palaeozoic metamorphic rocks and Mesozoic igneous rocks, with a supplement of Proterozoic metamorphic rocks. The transport capacity of three large fault troughs that delivered the northern provenances gradually increased from the Wenchang Formation (E2w) to the Enping Formation (E3e), whereas the southern provenances were transported by four or five incised valleys in E2w and then submerged in E3e. In the 3D seismic area, the features of the beach and bar sedimentary systems were described and interpreted based an analysis of the well-based sedimentary facies, seismic reflection characteristics and multiple attribute clustering. The results show that the beach and bar systems by the short-axis braided deltas mainly developed in the upper member of E2w and that the beach and bar systems on the subaqueous high in E3e developed during the Palaeogene. In addition, the bedrock-beach bar sedimentary system in the lower member (E3eL) was transferred to the braided delta–beach bar sedimentary system in the upper member (E3eU). 相似文献
10.
通过对石老人海滩不同季节表层沉积物体积磁化率的原地实测和所取表层样品粒度分级,结合海滩沉积动力环境因素综合分析得知,石老人海滩不同季节表层沉积物磁化率值总体上都表现出东高西低,滩肩高滩面低的趋势。海滩沉积物颗粒夏季比冬季细,分选好。海滩磁化率和沉积物粒度在海滩上的空间分布特征及其季节性变化存在一定联系。海滩的侵蚀沉积过程主要受冬夏季不同的波浪、沿岸流和风的作用影响。通常磁化率值高的区域为颗粒较细的侵蚀区,磁化率值低的区域为颗粒较粗的沉积区。磁学方法作为一种简便快捷低成本易操作的新方法,可以代替耗时的粒度和矿物分析,来分析海滩的沉积动力作用过程,识别海滩的侵蚀和沉积区域。 相似文献
11.
B_2孔揭示海河口地区全新世海侵层厚达19.2m,自下往上依次出现潮间滩、近岸浅海、前三角洲、三角洲湾、河口砂坝及河口边滩六个亚相,下部两个亚相呈海进层序,上部四个亚相呈海退层序。除河口边滩亚相底界外,其他所有亚相间的界面均为不连续面,显示海侵层为不连续沉积。研究表明该不连续沉积与海面波动有关.在全新世海侵高峰后,海面一直处于幅度不大(约1m 左右)的振荡运动状态,一次振荡波就在海岸线上留下一道贝壳堤,近5000余年来发生了5次振荡波,在海退平原中就有5道贝克堤与之对应。B_2孔海退层序中曲不连续面与贝壳堤基底侵蚀面相对应,也与振荡波的上升坡段相对应。海退层序所表现出来的海岸向海推进现象不是海面大幅度下降的反映,而主要是河口区沉积物迅速加积的结果。 相似文献
12.
In this article, results obtained from an experimental investigation conducted to determine the wave-induced geometric characteristics of offshore ripples and bars are presented. The experiments were performed using irregular waves. Natural beach sand was used in the study, where the mean diameter was 0.35 mm and the specific gravity was 2.63. The initial slope of the beach was 1:5. Different wave groups were generated over the initially flat beach, and a number of characteristics were determined. These include the ripple number, individual and average ripple heights, individual and average ripple lengths and the length of the offshore bar. The results of the experimental study were evaluated and empirical expressions based on the results were formulated. 相似文献
13.
The sandy beaches of Anapa Bay Bar are a unique natural resource, but they are gradually being degrade under both natural
and anthropogenic factors. The emissions of sand and shelly ground from the adjacent sea bottom partly compensate for this
process. The concentration of carbonates may reach up to 50% in the beach sands, and most of these carbonates are of mollusk
origin. The major deposit formation role belongs to the key bivalve species: Chamelea gallina (Linnaeus, 1758). The average biomass of this mollusk species reaches up to 450 g/m2 at the depths of 5–10 m. The other two subdominating mollusk species, the bivalve Donax trunculus (Linnaeus, 1758) and the gastropod Rapana venosa (Valenciennes, 1846), may impact as 16 g/m2 and 6 g/m2, respectively. Annually, 350 kg of shelly ground per running meter are newly deposited on Anapa beach. 相似文献
14.
浙江三门湾猫头深潭风暴快速沉积研究 总被引：2，自引：2，他引：2
三门湾频受热带风暴的影响,风暴期出现剧烈的滩冲、槽淤的泥沙交换,而在风暴后的正常天气条件下,则产生滩淤、槽冲的泥沙交换过程.通过猫头深潭(槽)9417号台风前后剖面水深重复测量、沉积特征及沉积物放射性同位素(210Pb,137Cs)测年等资料,揭示猫头深潭风暴快速沉积(骤淤).正常天气条件下风暴沉积产生再悬浮随潮运移,深潭水深得以恢复.在连续强热带风暴的影响下,又遇强的风暴增水,风暴沉积难以完全被冲刷,部分残留在深潭内,在猫头深潭沉积层中储存着风暴沉积的信息 相似文献
15.
根据１９９０年现场调查及前期观察资料，论述了海南岛新海弧形海湾不同岸段由主要动力驱动过程和海滩地貌结构组成的４种海滩地貌状态，为Ⅰ．隐蔽段消散类型，Ⅱ．脊－沟体系与低潮台地类型，Ⅲ．韵律海滩与砂坝类型，Ⅳ．开敞段消散类型。应用泥沙粒级参数概率模型分析近岸泥沙纵向运动趋势，结果表明，常波况下，沿岸泥沙存在双向运动，湾顶海滩为汇集地带，泥沙纵向运动主趋势为西南向；高能条件下，海岸北段可出现北向泥沙运动 相似文献
16.
2007年和2010年在厦门湾及邻近海域进行底质表层沉积物和柱状岩心样品采集,并进行粒度分析及粒度参数计算,获得了研究区底质表层和柱状沉积物样品的粒度分布特征.结果表明,厦门湾海域沉积物类型多样,以粉砂质砂和砂质粉砂为主.平均粒径介于?1.5Φ~7.5Φ之间.采用 Gao-Collins粒径趋势分析方法,发现九龙江口的沉积物主要呈东南方向净输运,而大金门南侧海域沉积物则有向九龙江口输运的趋势,同安湾内沉积物由海岸向湾中央输运;厦门东部海域沉积物向北输运,翔安南部海域沉积物向同安湾口以及澳头近岸输移.对柱状岩心进行放射性同位素210Pb 测年分析,计算得到九龙江口沉积速率为2.62 cm/a,进而探讨了九龙江口的沉积环境演化特征,研究成果可为区域资源开发和环境保护提供科学依据 相似文献
17.
A. V. Egorov L. I. Lobkovskii S. A. Kovachev E. A. Esina M. M. Marina Yu. M. Berlin O. V. Levchenko L. R. Merklin 《Oceanology》2008,48(1):68-76
The results of gas geochemical and seismoacoustic measurements obtained in the course of the expedition for the studies of gas seepages at the Anapa shelf of the Black Sea are presented. According to the data of the gas survey in the surface waters of the Anapa shelf, a large methane anomaly was discovered and mapped. The correlation of the anomaly with the bottom sources located over the Pionerskaya structure is proved. The geological structure of the area studied is analyzed. The data set allowed us to positively characterize the prospects of the oil-and-gas content of the Anapa shelf interiors and of the Pionerskaya structure proper. 相似文献
18.
《Coastal Engineering》2002,46(3):233-247
A field experiment, conducted on a sandy, barred beach situated on the southern part of the French Atlantic coastline, allowed us to investigate the formation of secondary waves when a moderate (significant wave height of about 0.8 m in 3.7-m water depth), long (11–14 s) narrowband swell propagated over an intertidal ridge and runnel system, in both breaking and nonbreaking conditions. Field evidence using higher spectral analysis is given for the sum interactions between pairs of waves at the primary spectral peak and the consequent energy transfer to nearly harmonic wave components. Although wave breaking appears to weaken the strength of nonlinear couplings, the generation of high-frequency energy is hardly affected by wave breaking. The phenomenon of harmonic decoupling, which takes place behind the bar, cannot be completely ascribed to the increase in water depth and the so-called deshoaling effect. Indeed, the variation in the values of the maximum bicoherence was very moderate when no breaking occurred. Finally, the doubling in the number of wave crests and the consequent decrease in the significant wave period delay the energy dissipation on the beach face. 相似文献
19.
Seasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the 50-m depth contour. A mean coefficient of variation of 0.35 provided a measure of the relative variability of near-bottom DO concentrations along this contour. Consistently lower DO concentrations in the southern region of the bay in summer and autumn are attributed to enhanced retention. Across-shelf transects captured the seasonal development of hypoxia in relation to the distribution of phytoplankton biomass. Exceptional dinoflagellate blooms form extensive subsurface thin layers preceding the autumn DO minima in the south of the bay, prior to winter ventilation of the bottom waters. The seasonal decline in DO concentrations in the bottom waters was marked by sub-seasonal events of hypoxia, and ultimately anoxia linked to episodic deposition of organic matter, as indicated by increases in bottom chlorophyll-a concentrations. Seasonal changes in bottom water macronutrient concentrations followed trends in apparent oxygen utilisation (AOU), both of which mirrored DO concentrations. In the south of the bay, nitrogen loss through denitrification/anammox in suboxic waters was indicated by a dissolved inorganic N deficit in the bottom waters, which was most pronounced in autumn. 相似文献
20.
Hurricane- or storm-generated swell waves may cause erosion and deposition along coasts which are situated thousands of kilometers outside the generating wind field. Marked beach erosion, caused by such swell waves, was observed along the micro-tidal west coast of Aruba. During the process of erosion a swash bar was formed, which moved up-beach during the waxing part of the swell event. The swash bar welded to the beach during the waning part of the event. Rapid sedimentation occurred on the upper beach. Finally, recovery of the beach was observed. The formation of a swash bar was attributed to an erosive, dissipative interval of a normally accretionary reflective beach. The sedimentary structures, although generally in line with observations on other beaches, show several peculiar characteristics: (1) the great thickness of the laminae in these calcareous sands; (2) the succession of low-angle sigmoidal and tangential sets in the swash bar; (3) the relatively steep erosional lower set boundaries and the wedge-shaped lamination in the successive stages of beach recovery; and (4) the several types of deformation structures. 相似文献