a multivariate mixing model for identifying sediment source from magnetic measurements a sequential method for quantitative identification of sediment source components based on magnetic measurements has been developed and tested for sediments from the rhode river maryland simulated mixing tests and multiple regression were employed to establish numerical relationships between source component proportions and the magnetic measurements of mixtures on the basis of these multivariate mixing models source components of three estuarine sediment cores were estimated by linear programming the results strongly support the previous studies on this catchment which indicated a dramatic change in sediment source some 150 to 200 yr ago quantitative calculations are more useful and informative than purely qualitative descriptions

active moribund and buried tidal sand ridges in the east china sea and the southern yellow sea shallow seismic profiles and borehole data revealed active moribund and buried tidal sand ridges in the east china sea and the southern yellow sea the ridges consist of relatively clean well sorted sands with fairly uniform sequences the microfossil assemblage exhibits a high diversity including both euryhaline and stenohaline species the ridges are huge elongated sand bodies several kilometres wide 10 60 km long and up to 20 m thick and occur in groups with a spacing of several to 10 km normally they are parallel with each other extending in the direction of the tidal currents the field of tidal sand ridges on the east china sea shelf covers an area of 57 000 km2 tidal sand ridges in the east china sea and the southern yellow sea were formed in estuarine and shallow shelf environments where strong tidal currents reworked transported and redeposited large amounts of relict sands from older deltaic and fluvial sediments the development of tidal sand ridges in estuary mouth areas is accompanied by a net sand transport from the shelf into the estuary the evolution of tidal sand ridges is closely related to transgressions active tidal sand ridges are formed during sea level rises they show distinct morphology and active migrations in a lateral as well as in a landward direction they are generally in equilibrium with present day tidal processes and their distribution patterns are related to the flow field of the tidal currents as the sea level rises further these tidal sand ridges become moribund sand bodies with less distinct morphologies their upper surfaces are covered by a thin calcareous rich layer with very high contents of foraminifera tests reflecting a submarine hiatus condition on the shelf during the highstand period during the subsequent steady fall in sea level tidal sand ridges are often buried by fine grained shelf and prodelta sediments they have therefore a good chance of being preserved in stratigraphic records the sequential buildup during a sea level rise tr tract and a subsequent sea level fall hs and ls tract would consist of estuarine channel and tidal flat facies tidal sand ridge facies shelf mud facies delta facies and fluvial facies in an ascending order tidally dominated estuary conditions may also occur when a major distributary is abandoned such as at the northern branch of the modern changjiang river mouth where the accumulation of sand from an abandoned delta lobe and the development of tidal sand ridges have been observed the observed features have important implications for the subsurface recognition of fossil tidal sand ridges for the reconstruction of the regional palaeogeography and transgressional history and for the prediction of potential reservoir sandstones

influence of provenance and hydrodynamic sorting on the magnetic properties and geochemistry of sediments of the oujiang river china abstract we present the results of environmental magnetic granulometric and geochemical analyses of sediments of the oujiang river china the aim of the study was to assess the influence of hydrological sorting and sediment source on sediment composition from upstream down to the river mouth the results reveal that the sedimentary magnetic properties are dominated by ferrimagnetic minerals in the fluvial reach the proportion of imperfect antiferromagnetic minerals is relatively high due to strong soil chemical weathering in a subtropical climate from upstream down to the river mouth the proportion of ferrimagnetic minerals increases consistently and the magnetite becomes finer grained as a result of hydrological sorting in the tidal reach the sediments consist of a mixture of fluvial and marine sourced sediments derived from the yangtze river as a result of the strong tidal influence a combination of the demagnetization parameter s 100 mt and element ratios fe k and al mg enables the discrimination of the sediments of the fluvial reach from those of the tidal reach due to the rock types and subtropical weathering conditions in the catchment the sediments of the oujiang river are significantly different to those of the yangtze river our results potentially contribute to the study of the provenance of the muddy sedimentary deposits in the inner east china sea they demonstrate that sediment sorting has a significant effect on bulk magnetic properties and geochemical compositions during transport from source to sink in addition magnetic and geochemical characterization of sized fractions of sediment can provide more reliable information regarding sediment source tracing

magnetic properties of muddy sediments on the northeastern continental shelves of china implication for provenance and transportation mud deposits are widespread in estuaries and on continental shelves and contain important information regarding interactions between terrestrial and coastal processes magnetic properties of muddy sediments from the northeastern continental shelves of china including shelves close to korean coasts were analyzed using bulk and size fractionated samples to elucidate muddy sediment sources and transport types concentration and granulometry of magnetic minerals were determined and all samples were found to be dominated by magnetite muddy sediments from the zhemin coast off the zhejiang and fujian coasts have the highest magnetic susceptibility and saturation isothermal remanent magnetization sirm values while those from the central and southeastern south yellow sea and the western korea strait have lower values reflecting lower magnetic mineral concentrations single domain ferrimagnetic grains dominate the magnetic particles in the central south yellow sea while superparamagnetic sp grains contribute significantly to the magnetic grains in the bohai sea sp and coarse multi domain md grains dominate magnetic grain assemblages in the north yellow sea and along the zhemin coast rock sediment particle size is not a major factor affecting the magnetic properties of the mud deposits in the study area rather terrigenous inputs and hydrodynamic transport processes primarily control the magnetic properties and sediments from the changjiang and huanghe rivers make the most significant contribution this observation applies to the whole study area although terrigeneous magnetic mineral concentrations decrease with increasing distance from the river mouths due to both sorting and mixing with other sediments with weak magnetic signatures bacterial magnetosomes also play a role in the central south yellow sea

drainage basin weathering and major element transport of two large chinese rivers huanghe and changjiang long term records show high concentrations of dissolved major elements in the changjiang yangtze river and the huanghe yellow river the huanghe drainage basin is characterized by intense weathering and erosion of carbonates and evaporites while weathering and erosion of carbonates and silicates over the drainage basin is the main source of major elements in the changjiang the rock soil composition and tectonics of the drainage basin are more important than atmospheric precipitation in affecting major element composition of these two rivers compared with other large rivers of the world the high suspended sediment and major element loads of the changjiang and huanghe reveal intense physical and chemical erosion over the chinese continent

the ti al molar ratio as a new proxy for tracing sediment transportation processes and its application in aeolian events and sea level change in east asia abstract ti al molar ratios of sediments in various sedimentary environments are used to explain sediment transportation from source regions to sink areas samples were collected from outcrops soils fluvial lake and marine sediment environments initial ti al molar ratios of sediments are controlled by those of parent soils or rocks these ratios tend to decline gradually as a result of heavy mineral gravity fractionation during transportation sedimentary ti al molar ratios in sink areas such as lakes and pelagic environments are lower than those in source regions in this study for the changjiang river huanghe river and kaoping river ti al molar ratios decline considerably from downstream to estuary environments additionally well sorted aeolian sands have extremely low ti al molar ratios in northern china the ti al molar ratios of aerosol particles found in taiwan and the east china sea show reduced ratios as a result of asia dust storm episodes furthermore lower ti al molar ratios in deep ocean sediments were discovered by tracing the distribution of sedimentary ti al molar ratios in the south china sea when sea levels dropped during glacial periods the river estuary was closer to deep marine areas and carried more terrestrial sediments into deep marine environments the closer estuary with relatively higher ti al ratio would lead increase of ti al molar ratios in deep sea sediments in this study ti al molar ratio is promoted as a new proxy to help with understanding changes in sedimentary environments

man s influence on the erosion and transport of sediment by asian rivers the yellow river huanghe example during the holocene sediment input from the yellow river to the yellow sea and adjacent areas has amounted to about 3000 km 3 detailed records from river gauging stations over the past 70 yrs together with estimates based on earlier historic records suggest that the river has contributed 2300 km 3 of sediment during the last 2300 yrs an average discharge of 1 km 3 yr 1 x 10 9 t yr prior to extensive agricultural use of the loess plateau in northern china beginning about 200 bc therefore the river s load must have been about 0 1 km 3 yr an order of magnitude lower than that at present a broad delta 20 m below sea level suggests that early holocene rates were higher than the pre agricultural average and therefore that middle holocene loads were low

provenance discrimination of last deglacial and holocene sediments in the southwest of cheju island east china sea abstract the ultimate provenance of muddy sediment in the southwest of cheju island east china sea remains enigmatic thus far in this study rare earth elements rees were used to investigate sediment provenances of cores e03 6 e03 10 and e03 11 taken from the mud patch discrimination plots based on ree fractionation parameters and trace elements suggest that the sediments deposited during the last deglacial period 15 ka were derived predominantly from the paleo huanghe yellow river which might have delivered sediments directly into the northeastern east china sea during the lowstand of sea level the coarse grained sediments deposited at transgressive stage 15 6 ka were primarily sourced from the changjiang yangtze river and partly from the korean peninsula probably transported by tidal currents in comparison the clayey sediments deposited at highstand stage

a review on the provenance discrimination of sediments in the yellow sea the yellow sea has been extensively studied for the understanding of dispersal patterns and limits of sediments from neighboring countries including china and korea although sedimentological mineralogical and geochemical approaches have been tried to solve the problems especially including the identification of sediment sources in and around the yellow sea the published results are not enough for understanding them suggestions on sediment origins budgets sediment accumulation rates mineralogical and geochemical compositions are not coincident to each other and sometimes even controversial for example conflicts on the distribution patterns of smectite and calcium carbonate the provenance of the southeastern yellow sea mud and sedimentation rates in there the ratios of v al and mn al in korea and china river sediments the origin of ba and pb in sandy sediments of the northeastern yellow sea and so on various geochemical indicators from the literature for the provenance discrimination in the yellow sea are reviewed here in depth and corresponding discussions are described separately research topics for the future study also are suggested for the proper access to the understanding of the origin and dispersal patterns of the yellow sea sediments especially focusing on the geochemical approaches d 2003 elsevier science b v all rights reserved

stratigraphy and paleoenvironmental changes in the yangtze delta during the late quaternary the yangtze delta area may be subdivided into paleo valley and paleointerfluves of the last glaciation the postglacial transgressive sedimentary cycle ptsc on the front zones of the paleointerfluves is composed of marsh nearshore and barrier lagoon shallow marine and nearshore tidal flat units with a basement in stiff clay the ptsc in back zones of the paleointerfluves consists of lacustrine marsh deposits the ptsc in the incised valley contains river channel floodplain estuary estuarine shallow marine and deltaic units with an erosional surface at its bottom the stiff clay and the erosional surface constitute the ptsc lower boundary the stiff clay consisting of a paleosol experienced deposition alternating with pedogenesis during the falling of sea level during 18o stage 3 ongoing pedogenesis in the sea level lowstand of 18o stage 2 and early diagenesis after paleointerfluve inundation by the sea level rise of 18o stage 1 the climate during the paleosol formation was temperate with more than 500 mm a 1 rainfall and frequently fluctuating groundwater the yangtze river incised its course during falling sea level of stage 3 and a huge incised valley was formed during the sea level lowstand stage 2 the filling of the incised valley took place during the postglacial sea level rise and delta formation occurred at a late stage of ptsc development

holocene changes in detrital sediment supply to the eastern part of the central yellow sea and their forcing mechanisms in this study holocene changes in the riverine eolian and erosional supplies to the eastern part of the central yellow sea ys and their forcing mechanisms were determined on the basis of multiple mineralogical and geochemical indices of three age dated piston cores from the central yellow sea mud cysm deposition the core records of the indices including clay minerals rare earth element fractionation parameters and conservative trace elements revealed abrupt changes in the sediment sources especially similar to 9 0 and 4 8 ka the late last deglaciation and early holocene sediments units 3 and 4 similar to 14 1 to similar to 9 0 ka most likely originated from the paleo huanghe and the sea bed erosion together with some contribution from the paleo changjiang shoal sediments that extended northeastward into the ys after that period the dominant sediment source gradually changed to the changjiang during the middle holocene similar to 9 0 4 8 ka unit 2 while the supplies from huanghe and sea bed erosion to the south ys decreased in the last 4 8 ka unit 1 the cysm largely received changjiang derived sediments besides some clay sized particulates from the huanghe sea bed erosion and korea rivers might be transported to the cysm during unit 1 possible mechanisms behind such changes in the riverine and erosional sediment sources and contributions include position shifts of river mouths tidal stress evolutions shelf sea level fluctuations east asian monsoon climate changes and the development of the yswc and coastal circulation systems c 2015 elsevier ltd all rights reserved

holocene shifts in riverine fine grained sediment supply to the east china sea distal mud in response to climate change holocene changes in fine grained sediment supplies to the east china sea outer shelf were uncovered through the mineralogical and geochemical analysis of core b3 in the east china sea distal mud ecsdm based on the lithology accelerator mass spectrometry ams 14c dating and sea level change core b3 can be divided into two major units transgressive stage unit 1 12 5 6 8 kyr and highstand stage unit 2 6 8 0 kyr significant discrepancy of dolomite calcite ratio in the fine fractions 16 m of changjiang dolomite calcite 3 1 and huanghe dolomite calcite 1 22 sediments was used as a new uniqueness provenance tracer to distinguish these two riverine sources both of the dolomite calcite ratio and rare earth elements fractionation parameters in the fine grained sediment indicated distinct provenance shifts of core b3 during the holocene unit 1 of core 3 12 5 6 8 kyr mainly consists of the reworked and resuspension sediments of the east china sea shelf during the holocene transgression while unit 2 sediments 6 8 0 kyr are most likely sourced from the changjiang and huanghe moreover mixing curves of dolomite calcite ratio reveal that the ecsdm continuously received the changjiang sediment since 6 1 kyr with notable fluctuations whereas the huanghe sediment supply began in 6 8 kyr but abruptly stopped during 4 2 0 8 kyr and then appeared again since 0 8 kyr temporal changes of the changjiang and huanghe fine grained sediment contribution to the ecsdm are closely related to the formation of modern oceanic circulation system since 6 8 kyr shelf sea level change the 4 2 kyr climate event and the followed transition to cold and dry climate condition in the northeastern china global climate change as well as the artificial shift of lower huanghe course in ad 1128 in the war against invasion of the northern nomadic nation human activities

sediment distribution dispersal and budget in the yellow sea abstract information on the surface sediment distribution in the yellow sea is newly compiled based on all available data produced by chinese and korean workers and is used to refine the dispersal patterns and budget of sediments derived from the adjoining landmass the central yellow sea is largely covered with fine grained sediments originating from the huanghe river 2 2 10 8 t yr about 20 of the total discharge thick sediment accumulation exceeding 5 mm yr occurs in the gulf of bohai and around the shandong peninsula about two thirds of the total huanghe river discharge the old huanghe delta suffers from reworking by strong tides and waves and forms a mud patch southwest of cheju island accumulation rate 2 10 7 t yr more than half of the sediments derived from the changjiang river are deposited along the coast of the east china sea the remainder accumulate on the inner shelf off the river mouth in the southeastern yellow sea the keum river dominates sediment discharge forming a holocene mud belt along the southwestern coast of korea accumulation rate 5 10 6 t yr turbid water plumes occur nearshore throughout the year and their suspended sediments are transported along the tip of the peninsula to the western coastal embayments in the south sea the nakdong river discharge of 1 10 7 t yr is responsible for the eastern nearshore mud of the south sea relict sands occur in the northern part of the yellow sea in the northern east china sea and in the korea strait

geochemistry and provenance of bed sediments of the large rivers in the tibetan plateau and himalayan region we investigated the geochemical characteristics of major trace and rare earth elements and sr nd isotope patterns of bed sediments from the headwaters and upper reaches of the six large rivers draining the tibetan plateau the jinsha river yangtze lancang river mekong nujiang river salween huang he yellow indus and yarlung tsangpo brahmaputra by using ca al versus mg al la sc versus co th and 87sr 86sr versus end 0 binary differentiation diagrams of provenance some typical contributors to the different catchment sediments can be identified in the three river the jinsha lancang and nujiang rivers tectonomagmatic belt acidic intermediate acidic volcanic rocks are very important provenance of sediments carbonate rocks and permian emeishan basalts are dominant in the jinsha river the yellow river sediments have similar geochemical characteristics with loess in catchments the indus and yarlung tsangpo rivers sediments are mainly from ultra k volcanic rocks and cenozoic granitoids widely distributed in the indus yarlung suture the intensity of chemical weathering in these river catchments is evaluated by calculating the chemical indices of alteration cia of sediments and comparing them with bedrocks the cia values of the six river sediments are from 46 5 to 69 6 closing to those of bedrocks in the corresponding catchment which indicates relatively weak chemical weathering intensity lithology climate and topography affect the chemical weathering intensity in these river catchments

magnetic evidence for yellow river sediment in the late holocene deposit of the yangtze river delta china abstract sediment source identification is critical for understanding delta evolution processes and for managing delta sustainability particularly for deltas experiencing significant recent fluvial sediment discharge sediment sources for the yangtze river delta yrd are commonly assumed to be derived from the yangtze river despite the fact that the yrd is a tide dominated delta that can receive marine sourced sediments in addition to fluvial inputs in particular potential contributions from the neighbouring sediment laden yellow river when it discharged into the yellow sea during 1128 1855 ce remains unclear here we present provenance analysis of three cores from the northern yrd using size specific magnetic characterizations we find that magnetic properties of sediments younger than 400 years have large differences among the studied cores comparison of magnetic properties to potential sources including the major yangtze river tributaries i e jinsha river jialing river and han river and old yellow river oyr indicates that the northern core received enhanced yellow river sediment loads over the last 400 years while the southern core had a dominant yangtze influence which is most pronounced in size fractions less than 16 m this interpretation is supported by geochemical results the documented spatial sediment source heterogeneity is caused by differences in tidal fluvial interaction among delta distributary channels our results imply that the neighbouring oyr delta to the north exerts a remote influence on the yrd through longshore transport this coastal connectivity between deltas should be assessed when forecasting future tide dominated delta changes in the context of global change

particulate element inventory of the huanghe yellow river a large high turbidity river abstract suspended sediments from the river mouth to the upper portions of the huanghe yellow river were collected and analysed to determine their chemical composition comparison with other large world rivers indicates that trace element levels are relatively low in this high turbidity river natural weathering and erosion are of primary importance in controlling particulate element concentrations although the impact from anthropogenic activities is also visible finally input of particulate elements to the china sea is assessed from the river sediment load and compositions

detrital sediment fluxes from continents to oceans abstract detrital sediment is carried from land to the sea by three agents rivers glaciers and winds the shoreline is an arbitrary boundary within the detrital sediment transport system which extends from a site of origin across areas of temporary storage to a site of long term deposition the most important of the agents moving sediment across the land is river transport estimated to be in the order of 20 10 12 kg of sediment annually at present analysis of drainage basins indicates that relief and runoff are the most important factors in determining the sediment load of rivers the competence of rivers to transport sediment is governed by the volume flow gradient and the sediment load itself today most large rivers are fed by snowmelt in highland areas runoff from rainfall in the drainage basin and groundwater inflow along the river course water is lost to evaporation and groundwater infiltration river courses can often be divided into two segments a degradational section in which the gradient is relatively steep and little temporary storage of sediment takes place and an aggradational section where the gradient is sharply reduced through meandering and where large scale temporary sediment storage forms a flood plain lakes trap sediment inland and prevent its transport to the sea today many high and mid latitude rivers are interrupted by lakes of glacial origin there are also some large areas of internal drainage that deliver no sediment to the sea the load carried by rivers has been markedly altered by human activity and may have doubled over the past few thousand years only to be reduced in the past century by the widespread construction of dams the ancient use of fire in hunting and its subsequent use in clearing land has increased erosion extensive deforestation and cultivation processes have also increased the sediment supply dam construction is a relatively new factor and affects the sediment transport system by trapping sediment before it can reach the sea the resulting lower sediment supply from rivers is at least in part compensated by increased coastal erosion glacial erosion is difficult to estimate there is an ongoing controversy whether ice sheets are effective erosive agents or not estimates of the present global flux of glacial detritus range from 0 8 50 10 12 kg annually with the lower value most probable the dust flux is in the order of 0 5 to 0 9 10 12 kg annually but may vary greatly with time

the geochemistry of thai paddy soils abstract this study has determined the elemental composition of uncontaminated thai paddy soils and identified whether variations in chemical composition within and between profiles are sedimentological in origin or due to pedogenic processes the chemical composition of the paddy soils is highly diverse in comparison to typical values for soils worldwide the median concentrations of zn rb sr pb as and cd in thai paddy soils are lower concentrations of si al fe k ca mg na mn ti s v p li ni cu ga co ag be and u are comparable and concentrations of cr are higher using factor analysis two affinity groups of elements and properties are recognized the first group consists of sand si and cr and relates to the sand content of the soils which includes chromium magnetite grains the second group is diffuse and consists of clay silt cec ph h 2 o ph kcl al fe k ca mg na mn ti s v p zn rb li ni sr cu ga pb co as be u ag and cd factor analysis indicates that the compositions of individual horizons in each soil are highly diverse resulting in substantial overlaps in composition between different horizons and soil profiles the large variations of chemical composition within and between thai paddy soils are due to the presence of discrete depositional layers within soil profiles with differences in texture of the soil controlling the variations in chemical composition pedogenic processes have modified original depositional properties to only a moderate extent but may have included the genesis of smectite microprobe analysis of thin sections has shown that the chemical composition of clay coatings is similar to that of the clay matrix and is consistent with the smectitic kaolinitic or mixed clay mineralogies of particular soils the composition of clay minerals in iron oxide rich mottles is similar to that of the clay matrix for kaolinitic soils iron oxide rich nodules in smectitic soils are also kaolinitic rather than smectitic indicating that the smectite formed in the matrix but not in the nodules which are original sedimentary features

geochemical composition and provenance of muddy shelf deposits in the east china sea abstract textural and geochemical compositions of shelf sediments in the east china sea were measured and compared with those of riverine sediments the sediments were primarily composed of mud and sandy mud with an average mean grain size of 6 1 contents of caco3 varied from 3 9 to 11 5 averaging 7 6 elemental ratios of sc al zr ti cr th and nb co can be treated as powerful geochemical indices for sediment sources because these elements behave conservatively under marine environments and the ratios show large variations between different end members of potential sediment sources comparative analysis between elemental sc al zr ti cr th nb co ratios and sr isotopic 87sr 86sr ratios strongly suggest that sediments in the northern part of the east china sea primarily originate from the huanghe river whereas the muddy deposits in the western part of the east china sea originate from the changjiang river the difference in 87sr 86sr ratios between the two regions appears to indicate varied sources

evidence for flexural shear folding associated with extensional faults the maintainance of bed length and bed thickness within the hanging wall of extensional fault systems requires the development of bed parallel shear four field examples of bed parallel shear related structures are described from a number of positions within the hanging wall and footwall to extensional faults flexural shear folding is a characteristic of both fault bend and fault propagation folding the dominant direction of the over riding shear is directed toward the fault surface in the case of fault bend folds the fault surface may be considered to represent the finite neutral surface of the fold in extensional fault propagation folds the direction of the overriding shear is toward the synclinalfold axial surface the observations suggest that the direction of flexural shear for extensional and contractional folds is opposite for folds of geometrically similar form

using nd sr isotopes and rare earth elements to study sediment provenance of the modern radial sand ridges in the southwestern yellow sea abstract the radial sand ridges rsrs in the southwestern yellow sea off the jiangsu coast east china have been intensively studied at least since 1975 despite decades of studies the provenance of the rsr sediments remains uncertain in this study the nd sr isotopic and ree geochemical compositions of residual sediments i e the acid insoluble fractions were investigated to determine the provenance of the rsr sediments the nd isotopic composition paas normalized ree patterns and characteristic parameters e g sm nd la sm n gd yb n were merely associated with source rocks but not with particle sorting while the sr isotopic composition and ree contents of residual sediments were affected by particle sorting in addition to source rocks the onshore rsr sediments originated mainly from mixing of the fine grained sediments from various parts of the offshore rsr in terms of ree geochemical and isotopic analyses isotopic and ree geochemical comparison further reveals that the rsrs off the jiangsu coast were fed chiefly by the dispersal of surface sediments from the yangtze river mouth surface sediments from the yangtze river mouth were directly dispersed to the rsrs along the jiangsu coast and significantly affected the seaward part of the offshore rsr and the old yellow river delta area by a northward branch of the changjiang diluted freshwater plume only minor quantities of surface sediments from the modern yellow river mouth were introduced into the rsrs by the jiangsu coastal current and mainly contaminated the landward part of the offshore rsr area our findings highlighted the potential of the nd isotopes with ree geochemistry to trace the provenance of coastal sediments

holocene regression and the tidal radial sand ridge system formation in the jiangsu coastal zone east china abstract a radial tidal sand ridge system rtsrs spans more than 20 000 km 2 in the southwest yellow sea is fan shaped and stretches from qianggang toward the sea the marine rtsrs is located in a convergent divergent tidal current field cdtcf numerous drilling holes reveal an area of 3000 km 2 containing tidal sand strata in the jiangsu coastal plain on land adjacent to the marine rtsrs which stretches eastward from chengdong and is also a fan shaped with a central angle of 130 the tidal sand unit lies on a transgressive coastal barrier lagoon unit with an erosional surface between them and the latter unit is in turn lying on late pleistocene stiff mud the tidal sand unit is overlain by the littoral tidal flat unit and together they constitute the holocene regressive succession paleo current study reveals that a paleo current pattern similar to the modern marine cdtcf was present in the holocene sub aerial tidal sand strata therefore the sub aerial tidal sand bodies are deduced to be an ancient rtsrs that was formed during the holocene regression and gradually exposed and changed into land as the changjiang and huanghe deltas prograded both sub aerial and marine rtsrs should be formed in the same tidal depositional environment but in different development stages thus the radial tidal sand ridges in southwestern yellow sea should have formed not during the holocene transgression as most previous studies have inferred but in the process of holocene regression mineralogical analyses demonstrate that the sediment source of the sub aerial rtsrs initially came from the changjiang and later predominantly from the huanghe sea floor erosion by tidal currents may also provide sandy material to form the rtsrs drilling cores and ground penetrating profiles show that the paleo valleys in the study area are much smaller than the present distributaries of the changjiang river thus the presumption of direct sand supply by a large river to form the rtsrs through its apical area is cannot be supported after the sea level reached the present high stand the jiangsu coastline has been prograding seaward as the changjiang delta expanded and this progradation was accelerated when the huanghe debouched in the study area the nearshore part of rtsrs has been gradually changing into land while the entire rtsrs extends seawards in the process of the development the rtsrs apex changed from chengdong to qianggang at present the coastline is still moving seaward while the outer part of the rtsrs suffers from some erosion owing to reduction of sediment supply from both the changjiang delta and the abandoned huanghe delta

geochemical constraints on the provenance of surface sediments of radial sand ridges off the jiangsu coastal zone east china abstract the jiang harbor centered radial sand ranges rsrs off the jiangsu coast are the largest in the yellow sea however the provenance of the rsrs remains controversial in this study we compare major and trace element geochemistry together with grain size and main mineral composition in carbonate free sediments from rsrs and potential sources onshore and offshore rsr sediments have different grain size characteristics onshore rsr sediments have mean grain sizes of 2 tio 2 li and partly in cs zn and some high field strength elements y zr nb pb and th while depleted in other elements offshore rsr sediments are complicated in geochemical compositions some of them have very high contents of high field strength elements and others are similar to onshore rsr sediments onshore and offshore rsr sediments have different controlling factors of geochemical compositions onshore rsr sediments are influenced by clay size minerals whereas offshore sediments are controlled by heavy minerals the identification of zr nb and ti zr vs k rb shows that onshore and offshore rsrs seem to have similar sources their differences in grain size are a result of hydrodynamic sorting the identification of elemental ratios reveals that sources of rsr sediments are variable in space and time and the inputs of the chinese rivers especially the old yellow river and the yangtze river are still dominant but the effect of the korean field cannot be neglected our findings also demonstrate the potential of elemental ratios such as zr nb and k rb as tracer pairs for provenance of sediments in the yellow sea

geochemical factors controlling accumulation of major and trace elements in greenland coastal and fjord sediments the major al ti ca mg fe mn si and trace element cd cr cu hg li ni pb v zn concentrations in surficial 63 m and 63 m and have accumulated at the same rate as other detrital clastic material provenance and glaciomarine deposition are the main factors controlling the abundance and distribution of the major and trace elements the chemical composition reflects the mineralogical differences in the provenance of glacial marine material deposited by water and ice adjacent to greenland the main source of the sediments enriched in ti fe mg cr cu ni and v appears to be material derived from the volcanic rocks of the mesozoic tertiary provinces of greenland by glacial erosion

major sinks of the changjiang yangtze river derived sediments in the east china sea during the late quaternary the east china sea ecs is a typical marginal sea located between the eurasian con tinentandwestpacificocean inthisstudy wereviewstate of the artresearchprogressonthepos sible sinks of the changjiang derived sediments in the ecs during the late quaternary the major sinks of these sediments in the ecs are on the outer shelf and the okinawa trough during the last glacial maximum corresponding to a lowstand of sea level during the deglacial marine transgres sion the gently dipping shelf was rapidly inundated and strong tides prevented fine sediment from deposition on the open shelf resulting in the development of a unique tidal sand ridge sys tem with sea level reaching the present situation and the modern marine environment being com pleted in the early holocene the changjiang sediments mostly accumulated in the river s estuary to build a large delta with only a fraction reaching the inner shelf and coastal embayments the late quaternary changes in monsoon climate induced river flux sea level and oceanic circulation primarily controlled the source to sink transport of the changjiang sediments in the ecs and fur ther determined the stratigraphic framework and sedimentary facies on the shelf

exploratory morphodynamic modeling of the evolution of the jiangsu coast china since 1855 contributions of old yellow river derived sediment abstract in this study we aim to investigate the overall morphological evolution of the jiangsu coast after 1855 when the yellow river shifted northward we focus on fine sediment transport between two large scale geomorphological units i e the abandoned yellow river delta ayd and the radial sand ridges rsrs an existing morphodynamic model which was established for reproducing the development of the ayd before 1855 is modified and extended in addition to the tidal forcing waves and human interventions i e revetments are considered in the model the model results are compared with the existing data both the evolution trend of the jiangsu coast and the spatial distribution of the offshore shoals show good agreement the simulated fine sediment depositions in different periods are consistent with the geological measurements the results reveal that the old yellow river derived sediment not only contributes to the sedimentation in the rsrs but can also be transported to the adjacent zones especially farther south southeast moreover the spatial distribution of fine sediment deposits varies in the rsrs the different sedimentary environments in the dongsha and tiaozini ridges result in significant grain size differences in these two neighboring ridges a sensitivity analysis indicates that tides play a key role in dominating the long term morphological evolution of the jiangsu coast and the total erosion from the ayd on smaller scales the effect of revetments built since the 1930s on the evolution of the nearshore zone and the effect of wind waves on the erosion of offshore shoals are relatively important the effect of a gradual coarsening process of bottom sediment along the jiangsu coast which may be due to continuous fine sediment removal is identified fine sediment depositions in the tiaozini ridge and in the northern offshore zone of the rsrs are relatively more sensitive to the coarsening trend of bottom sediment than other areas

distribution and fractionation of heavy metals in the surface sediments of the ganges brahmaputra meghna river system in the bengal basin the lower ganges brahmaputra meghna g b m drainage basin occupies the total bengal basin which is one of the unique basins of the world because of its location and size density of population and catastrophic deposition of sediments the increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the g b m system in the basin which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes the differences in heavy metal concentation in the lower g b m system with that of its upper and middle counterpart is mainly related to the contrast between himalayan rivers and the other major south asian rivers and may be due to the geological differences of their denudation regime heavy metals in the lower g b m system have an affinity towards the clay fraction of the sediments the correlation matix of heavy metals in the lower brahmaputra and meghna suggests the importance of fe mn oxyhydroxides in their accumulations iron ti and mn are higher in the meghna main channel zn is higher in the meghna tributaries and cr is higher in both the brahmaputra and meghna compared to the value for standard shale the enrichment factor is 1 for most of the metals except mn which is relatively higher in the meghna and lower ganges main channels the geoaccumulation index igeo for most of the heavy metals lies below grade zero suggesting unpolluted sediment quality the lower ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals probably due to the presence of petroleum refinery industrial and mining effluents and agricultural runoff in the drainage basin the relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals the bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution

multipath variability due to the gulf stream a phase coded signal with 64 ms resolution was transmitted at 10 min intervals for a 19 day period over two 300 km ranges the acoustic source was moored at 2000 m depth northwest of bermuda one receiver was moored at 2000 m depth to the northeast of the source and the other receiver was bottom mounted at 1000 m depth near bermuda the large 0 6 s travel time change at the bermuda receiver is probably due in large part to motion of the source mooring in the presence of currents the multipath arrival pattern at the moored receiver undergoes significant modification due to the presence of a southern meander of the gulf stream which intersects this transmission path

geochemistry of trace metals from chinese river estuary systems an overview abstract based on the data from extensive estuarine studies over 10 years 1983 93 the present work provides an overview of the geochemical features of large chinese river estuary systems elevated concentrations of major elements are observed in chinese rivers from north to south which is attributed to intense weathering and erosion over the drainage basins trace metal levels in chinese rivers are relatively low and similar to those from large and less disturbed world aquatic systems e g amazon and orinoco in the estuaries particulate elements show stable distributions in the mixing zone especially when absolute concentrations are normalized to aluminium and or scandium dissolved trace metals may have either conservative and or active non conservative distributions or both in chinese estuaries wherever non conservative distributions are observed trace elements may be remobilized and or scavenged from solution depending upon river discharge sedimentary dynamics and element biological uptake and regeneration of trace metals becomes more important in high salinity areas further offshore the riverine effluent plumes than inside correlation of heavy metals with grain size and operational chemical forms reveals a high proportion of elements associated with the fine size fraction compared to total sediments and elevated labile fractions in bottom sediments in anthropogenically disturbed systems finally an estimate is made towards the chemical flux of trace metals to the ocean through chinese estuaries

magnetic and geochemical evidence of yellow and yangtze river influence on tidal flat deposits in northern jiangsu plain china abstract the formation of a broad tidal flat along the coast of the northern jiangsu province of china depends largely on the sediment supply from the yellow and yangtze rivers although the relative contributions from each of these two large rivers remain uncertain knowledge of sediment sources to the tidal flat is critical for understanding the evolution of this muddy coast impacted by the large rivers the present study focuses on tracking the sediment source of the tidal flat deposits based on sediment magnetic properties and geochemical analyses as well as statistical analysis the study shows that sediments to the north of yangkougang site 9 have lower values of saturation isothermal remanence magnetization sirm magnetic susceptibility demagnetization parameter s 100 ratios lower fe al values and higher ca concentrations while the opposite is true for samples south to haozhigang site 18 in addition sirm values of the 63 m fractions generally display increasing trend from north to south these results suggest that sediment sources rather than particle size variation are the dominant factors influencing the bulk magnetic properties in light of the sediment composition comparison between the yellow river and yangtze river factor analysis is used to identify sediment source of the tidal flat sediments it is indicated that the yellow river in its former course is the dominant supplier for sites to the north of yangkougang site 9 while the yangtze river is the dominant supplier for sites to the south of haozhigang site 18 the coast between yangkougang site 9 and haozhigang site 18 is a transition zone influenced by both rivers the inferred provenance contrasts are consistent with the pattern of coastal geomorphological evolution our data also suggest that sediments eroded from the former yellow river delta have contributed to the evolution of the yangtze estuary in historical time this study demonstrates that a combined magnetic and geochemical fingerprinting techniques in couple with statistical analysis is valuable for identifying sediment sources of tidal flats and deltas influenced by large rivers in the world

geochemistry of alkaline earth elements mg ca sr ba in the surface sediments of the yellow sea abstract the concentrations of alkaline earth elements were measured in the surface sediments of the yellow sea in an attempt to establish their sources from horizontal distributions the maximum concentrations of mg are found in the central yellow sea and its horizontal distribution is mainly controlled by quartz dilution the concentrations of ca and sr increase toward the southeastern yellow sea region the relatively higher enrichment of ca and sr in the southeastern yellow sea with sr ca ratios of 0 0053 suggests the presence of carbonates which are comprised of foraminifera and or coccoliths like deep sea carbonates on the other hand the concentrations of ba increase toward the northeastern yellow sea the higher ba enrichment in the sandy region of the northeastern yellow sea is associated with the presence of feldspar as evidenced by excellent correlations among ba mg al mg and sr ca ratios our results suggest that the transgressive and relict sand occurring in the eastern parts of the yellow sea contains al sr and ba enriched feldspars which originated from arprock river korea and thus can be distinguished from sand occurring in the western parts of the yellow sea which originated from yellow and yangtze rivers

sediment accumulation in a modern epicontinental shelf setting the yellow sea sediment accumulation in the yellow sea epicontinental shelf environment is investigated on 100 yr and 1000 yr time scales using 210pb and 14c geochronologies the distribution of modern 210pb accumulation rates in the yellow sea reveals that the loci of modern huanghe sediment accumulation are the topset 1 2 mm yr foreset 4 9 mm yr and proximal bottomset deposits 2 4 mm yr of the shandong subaqueous delta which extends south from the shandong peninsula 210pb rates in the distal bottomset deposits of the subaqueous delta in the central and southern yellow sea are generally low 0 3 0 9 mm yr a sediment budget demonstrates that between 9 15 of the annual huanghe discharge is accumulating in the yellow sea about two thirds of this sediment is accumulating in the topset foreset and proximal bottomset deposits of the shandong subaqueous delta with the remaining third accumulating as widespread distal bottomset deposits 14c age dates of subaqueous delta sediments indicate that the thick 40m clinoform structure formed predominantly between 6200 and 4060 yrs b p at rates approaching 20 mm yr observations in the yellow sea as well as on the amazon and ganges brahmaputra shelves demonstrate that subaqueous deltaic stratigraphy is the general rule where major rivers enter energetic shelves whether epicontinental or pericontinental the development of extensive bottomset deposits may be restricted to epicontinental shelf environments and may be diagnostic of sedimentation in this type of setting

geochemical discrimination of clastic sedimentary rock sources abstract factors controlling the geochemistry of a clastic sedimentary rock can include 1 composition of source terrain 2 chemical weathering 3 hydraulic sorting 4 diagenesis 5 metamorphism and 6 hydrothermal alteration a linear solution inferring source terrain composition from geochemistry of the sediment is impossible in this multivariate system as several unknowns will commonly be present the use of graphical analysis of element pairs circumvents the problem chemically immobile elements will maintain invariant ratios during rock mass change caused by either addition or depletion of mobile elements this results in chemically immobile element scattergrams exhibiting linear trends along radians extending from the origin if the major mineral phases of the immobile elements have behaved in a hydrodynamically similar manner as chemically mobile element plots will produce a scatter of points this relationship can be used to test chemical immobility and similarity in hydrodynamic sorting history the constraint on analysis is that the source area must be compositionally uniform or the sediment well mixed prior to delivery to the basin a second technique using sio2 plots has also been developed to investigate element mobility and hydrodynamic behaviour of the mineral phases containing the elements sio2 immobile element plots result in a linear arrangement of points extending towards either 0 or 100 sio2 the 0 intercept position occurs for elements with major mineral phases concentrated in sand the 100 intercept for those concentrated in clays plotting chemically mobile elements produces different patterns and this can be used to gain information on alteration and sorting history elemental ratios for chemically immobile elements with similar hydrodynamic behaviour will be the same as those for the weighted average composition of the source material this provides a powerful tool for deducing source terrain from sediment geochemistry techniques outlined above were tested on archaean metasandstones from superior province canada immobile element ratio diagrams for nb al ti and zr al ti indicate that a calc alkaline extrusive intrusive suite lying to the north of the study area was the source and not five other volcanic suites in the region this conclusion agrees with previous clast lithology studies and accentuates the applicability of the geochemical techniques

strontium lead and zinc isotopes in marine cores as tracers of sedimentary provenance a case study around taiwan orogen abstract the active collision zone around taiwan orogen receives a variety of sedimentary inputs including terrigenous flux from taiwan and chinese rivers oceanic currents and atmospheric dust in order to determine the present day respective contributions of these different sources we analysed the pb and sr isotopic compositions of late quaternary sediments accumulated offshore east taiwan samples from the taiwan coastal range andesites sandstones conglomerate and peinan river terraces and suspended loads have also been analysed to constrain the mean taiwan isotopic signature mixing lines between the different sources of material indicate that the core located in the okinawa trough represents a mixture of about 60 of taiwan 30 of chinese loess and 10 of yangtze river contributions the southernmost core located close to luzon arc is influenced by taiwan 60 and volcanic material 40 the sr and pb isotopic compositions of samples cored in the manila trench and in the huatung basin are strongly influenced by the taiwan signature while the ryukyu trench core samples point to significant but variable contributions of chinese loess and yangtze river this work also reports zn isotopic variations in the silicate fraction of these marine core samples the overall variation in zn isotopic compositions expressed as 66zn is greater than 0 3 per mil for an analytical precision of 0 05 the zn isotopic signal for most of the marine core samples is similar to the literature data measured on sedimentary material except for the manila trench core samples and the older sample from the huatung basin they present values heavier by 0 2 0 3 close to those obtained on all taiwan rocks and peinan river particulates these results show 1 the particular characteristics of taiwan zn isotopic compositions on a large scale and 2 the possible use of zn isotopes as a tracer of material sources

geochemistry of surface sediments off the southern and western coasts of korea abstract the continental shelf off the southern and western side of the korean peninsula is part of a modern epicontinental sea and is an effective sediment trap for clastic material derived from china and korea we have analyzed 179 surface sediment samples from this shelf for al fe na k mg ca ti p mn sr ba v cr co ni cu zn organic carbon and calcium carbonate in order to determine the geochemical characteristics of these sediments results showed a wide range of element contents which are mainly related to the textural variability of sediments exceptions to this were found in the contents of ca k sr and ba the ca and sr contents were largely determined by the amounts of carbonate present the k content on the other hand appeared to be influenced by both the contents of illite and feldspar and ba of potassium feldspar for muds i e sediments deposited under present day conditions it is possible to distinguish those in the central yellow sea from those in the keum estuary the former are characterized by high contents of fe na k mg ca and v and the latter by high contents of mn ba and co these differences become more apparent when these elements are normalized relative to al in order to minimize grain size effects the distribution of v al ratios is different from that of other elements the highest v al values occur in muds from the central yellow sea derived from the huanghe the yellow river in china whereas the highest values of mn al are found in the nearshore area adjacent to the korean peninsula based on these results it is suggested that the sources of fine sediments in the yellow and south seas can be distinguished from the geochemical characteristics of the surface sediments in the yellow sea two different sources of fine grained sediments can be seen the huanghe and the keum river the former is characterized by higher v contents and the latter by higher mn contents using the v al ratio as an end member component of the two source materials the dispersal patterns of the fine sediments 6o were also derived

exploratory morphodynamic hindcast of the evolution of the abandoned yellow river delta 1578 1855 ce abstract the abandoned yellow river delta ayd which formed when the yellow river flowed into the southern yellow sea between 1128 and 1855 ce is a representative example of the sensitivity of deltas to modifications in their environments in this study we established a process based morphodynamic model to explore the morphological evolution of one such large scale fine grained delta the ayd before 1855 ce the uncertainties in the model settings which are inevitable when historical data are insufficient were assessed together with the corresponding influences on the evolution of the deltaic system by considering a series of scenarios the results indicate that the strength of local tidal forcing is the key factor that determines the shape and evolutionary trend of the delta sediment input discharge and the slope of the initial coastal profile have a considerable effect on the overall size of the delta and the relative ratio between subaerial and subaqueous parts of the delta respectively based on the evaluation of the uncertainties and a comparison with historical maps the simulated ayd was evaluated to be reliable through an analysis of the temporal delta evolution and residual sediment transport the morphological evolution of the ayd before 1855 ce was investigated the southern delta grew as the shoals merged with the mainland which is in agreement with an existing hypothesis zhang 1984 whereas the accretion of the northern delta was independent from the shoals in the northern part additionally suggestions are made regarding the distribution of the ayd at the end of its progradation stage which provides fundamental information for analyzing subsequent erosion processes since 1855 ce this study differs from existing studies on the ayd which are all based on geological approaches it provides insight into the evolution of the ayd through an alternative means viz a process based morphodynamic modeling approach

geochemical compositions and provenance discrimination of the central south yellow sea sediments geochemical compositions and sedimentation rates of surface and core sediments in the central south yellow sea were analyzed for the identification of sediment origins the sediment accumulation rates measured by 210 pb geochronology decrease significantly from the western part to the central area calcium carbonate total organic carbon and most elements are more enriched in the western muddy sediments than in the sandy eastern part overall geochemical compositions of the central south yellow sea sediments vary between those of chinese and korean river sediments supplied into the sea although caco3 content exhibits regional variations in the central south yellow sea the discrimination diagram of sc al vs cr th distinctly suggests that the muddy holocene sediments in the central western part are derived ultimately from chinese rivers especially the huanghe river whereas the eastern sandy sediments primarily came from the korean rivers during the postglacial transgression 2007 elsevier b v all rights reserved

discrimination of geochemical compositions between the changjiang and the huanghe sediments and its application for the identification of sediment source in the jiangsu coastal plain china concentrations of 25 elements in the fine grained fraction 6 63 wm of bottom sediments of the changjiang and the huanghe were determined to characterize the geochemical compositions of each riverine origin most of the elements except for alkali and alkaline earth elements na ca sr and ba are highly enriched in the changjiang sediments compared to those in the huanghe sediments differences in source rocks and weathering mechanisms between the two drainage basins are the major factors controlling those compositional characteristics the provenance index of core sediments from the northern jiangsu coastal plain calculated with nine elements with distinct compositional differences between both river sediments indicates that the changjiang had prevailed in the coastal plain sedimentation during the early stage of holocene while the huanghe dominated over the area during the late holocene however neither of the signatures of the modern changjiang and huanghe derived sediments is remarkable in the present day coastal plain 5 2002 elsevier science b v all rights reserved

origin and dispersal of recent clay minerals in the yellow sea abstract the clay minerals in the by considering the clay minerals supplied by rivers in china the old and present day huanghe river and korea the keum and yeongsan to the yellow sea continental shelf and the spatial variation in the distribution of clay minerals in the yellow sea this study indicates that the provenance of the cysm may be closely related to the old and present day huanghe river system whereas the clay minerals in the seysm seem to be largely associated with the keum and yeongsan rivers in addition smectite may be suggested as an important clay mineral in differentiating between cysm and seysm and understanding the sources of these two mud categories

discrimination in magnetic properties of different sized sediments from the changjiang and huanghe estuaries of china and its implication for provenance of sediment on the shelf abstract provenance discrimination of marine sediments is an important topic in marine geology although the catchments of the changjiang and huanghe rivers are regarded as the main sources of sediments on the shelves of the china sea identification of detailed sediment provenance is necessary for understanding sediment transport patterns and the paleoenvironment magnetic properties of both bulk sediment samples and different sized particles from the changjiang and huanghe estuaries are studied to discuss the origin of the sediments the results show that the sediments are dominated by ferrimagnetic magnetite with a minor content of anti ferromagnetic minerals such as hematite and a higher concentration of ferrimagnetic minerals is observed for the changjiang estuary sediments the crystal grains of ferrimagnetic minerals in the changjiang estuary are coarser than those in the huanghe estuary whereas superparamagnetic grains significantly contribute to the huanghe sediments magnetic parameters of sirm soft and arm from different sized particles present more obvious differences than these parameters from bulk particles and s 100 and s 300 for both bulk samples and different sized particles show distinct differences between the sediments from the two estuaries therefore the latter parameters are more useful to distinguish sediment origins a comparison of the magnetic properties of sediments in these two estuaries with those on the shelves of the adjacent china sea also suggests that the analysis of sediment magnetic properties is effective to identify sediment provenances

sedimentary environment and formation mechanism of the mud deposit in the central south yellow sea during the past 40kyr abstract sedimentary environment and formation mechanism of the mud deposit in the central south yellow sea of china during the last 40 kyr are studied based on the analysis of particle size sediment density chemical features magnetic properties and ams 14 c ages of a new core ys01a together with other available core data the results show that there exist four sedimentary sections during this 40 kyr period including two marine sections a and c and two terrestrial intertidal sections b and d sedimentary indexes of section d which were formed before 40 kyr show that strong weathering and erosion occurred in this section in contrast sedimentary environment of section b was wetter and warmer and weathering and erosion were not as strong as in section d marine deposits in both sections a and c indicated the effects of sea level rise and section c was deposited when the climate was much wetter than in section a variations of climate and local hydrodynamics created different sediment features of two marine sections from the estimated river discharges of the huanghe changjiang and relevant korean rivers and calculation of mud deposit volumes of section a during the past 9 7 kyr it is found that the sediment inputs from these river sources can only account for about 48 of sediments in the two mud deposits of the central and southeastern south yellow sea the other main source of sediments is identified to be the seabed erosion resuspension and redeposition from the yellow sea and to a lesser extent from the biogenesis and diagenesis it provides a unique opportunity of understanding the formation and source of mud deposits by comparing the sedimentary properties of sections a and c in core ys01a it is found that formation of mud deposits is not related directly to the yellow sea warm current which only changed the sediment properties of mud deposits in section a since it formed from holocene by bringing a large amount of organic mass and finer particles however cold water mass developed in this area is important as it helped to trap more and finer particles in the two marine sections upwelling usually occurs around 50 m bathymetry which is at the juncture of two opposite water currents and has induced the thickest sediment layer this study also confirmed that formation of the mud deposit in the central south yellow sea is caused mainly by the tidal currents on the continental shelves

geochemical composition and provenance discrimination of coastal sediments around cheju island in the southeastern yellow sea sediments from the northern coastal area of cheju island south sea of korea southeastern yellow sea were analyzed for grain size composition elemental compositions and clay mineralogy in order to investigate their provenance rare earth element ree compositions and geochemical discrimination diagrams were revealed to be useful indices for identifying the origin of sediments in the study area these indices together with clay mineral compositions suggest that both the sandy and muddy sediments originated from weathering of the volcanic rocks of cheju island whereas sediments originating from the changjiang and huanghe rivers cannot be traced in the study area similarly river borne matter from the korea peninsula has little influence on the sediment deposited therefore the suggestion that fine grained changjiang sediments can reach the nearshore area of cheju island the cheju strait suggested by oceanic circulation patterns in the yellow and east china seas cannot be supported by this study based on geochemical and mineralogical analyses

origin of rare earth element anomalies in mangrove sediments sepetiba bay se brazil used as geochemical tracers of sediment sources elemental contents were determined in two mangrove habitats along sepetiba bay se brazil an area impacted by local industrial activities as well as hinterland water diversion networks this study demonstrates how specific rees la ce nd sm eu tb yb and lu may be used as a sediment source tracer to mangrove dominated coastlines from the two stations studied a pair of cores was collected one in the mangrove forest and the other in the tidal flat station 1 results show a general enrichment in most of the fractioned patterns of the rees normalised by post archean australian shale the relatively light rare earth elements are similarly enriched in the generally more polluted station 1 despite the probable difference in background sediment characteristics a common sharp increase in mud contents patterns in the upper part of the mangrove sediment core was related to a lower ree content as well as eu anomalies with existing knowledge of clockwise water circulation in the bay these patterns can be explained by man made water diversion from the sao francisco and guandu rivers initiated more than 30 years ago whereby suspended matter with relatively large contents of rees and material originating from industrial sources accumulate in the eastern sector of the bay this is the first comprehensive assessment of rees as sedimentary tracers in a mangrove ecosystem in brazil

metals in suspended sediments from the changjiang yangtze river and huanghe yellow river to the sea and their comparison thirty five samples of suspended sediments were collected at datong station and lijin station the basin wide control stations of the changjiang yangtze river and the huanghe yellow river during flood and dry seasons in 2000 and 2001 concentrations of 15 elements fe mg ca al na k ti mn ba sr pb cu zn v and ni in these samples were measured by icp aes the results indicated that fe al ti mn ba cu zn v and ni concentrations in the changjiang sediments in may flood season were quite close to those in november dry season whereas mg ca na k sr concentrations were slightly higher and pb was relatively lower in the dry season ti ba sr and zn concentrations in huanghe sediments varied little in august flood season and december dry season while mg ca al na and k concentrations were higher by approximately 30 and fe mn pb cu zn v and ni concentrations were lower in flood season concentrations of most metals except ca na and sr were much higher in changjiang sediments than those in the huanghe such differences of metal concentrations in sediments from these two rivers could be ascribed to their different sediment sources and weathering processes within their corresponding river basin particularly since the 1980s pb and zn concentrations in changjiang sediments have increased significantly due to the releases of waste contaminants from human activities while the variations for these two elements in the huanghe samples were very little due to the elevated river bed in the lower reaches