sediment provenance and paleoenvironmental change in the ulleung basin of the east japan sea during the last 21 kyr despite the well reconstructed paleoceanography of the late quaternary deposits in the east japan sea es provenances of terrigenous sediments and a comprehensive interpretation of their variations since the last glacial maximum remain unclear especially in regard to the mainland china and taiwan derived matter grain size conservative trace elements rare earth elements rees nd isotope and clay mineralogy of core sediments from the ulleung basin of the es were investigated for better understanding of detrital sediment provenance and transport process and then their forcing mechanisms over the last 21 kyr geochemical mineralogical multi indices in this study showed notable three phase changes in sediment provenance which can be closely related to sea level fluctuation development of the tsushima warm current as well as intermittent influence from the east asian summer monsoon climate evolution during unit 1 21 1 8 4 kyr bp when the tsushima warm current was absent in the es the paleo changjiang and the paleo huanghe mouth might be situated close to the study area and thus mainland china could have played major role in the southwestern ulleung basin sedimentation in particular the formation of rhythmic dark colored alternation in unit 1 is possibly attributable to the pulse of paleo huanghe discharge associated with centurial to millennial scale variability in the east asian summer monsoon in unit 2 8 4 7 2 kyr bp these river mouths gradually retreated to their present positions with global sea level rise leading to decreasing terrigenous sediment supply from mainland china to the study area since 7 2 kyr bp unit 3 sedimentation in the ulleung basin should still be mainly derived from mainland china meanwhile increasing chlorite kaolinite ratio but decreasing epsilon nd value revealed that terrigenous matter from taiwan might have been limitedly transported northward to the study area by the fully evolved tsushima warm current a prominent decline in chlorite kaolinite ratio together with contrast change on epsilon nd value centered at around 2 9 kyr bp 3 3 2 4 kyr bp may have been caused by the tsushima warm current suppression possibly related to the pulleniatina minimum event popularly found in the study area and nearby seas c 2014 elsevier ltd all rights reserved

sr nd isotopic geochemistry of holocene sediments from the south yellow sea implications for provenance and monsoon variability abstract elemental geochemical and sr nd isotopic signatures are used to decipher terrigenous sediments provenances and transport mechanisms in the south yellow sea during the holocene 87sr 86sr ratios in the chinese and korean riverine sediments overlap each other whereas end values of korean riverine sediments are generally less radiogenic in comparison to the changjiang and huanghe moreover end values of these two large rivers appear unaffected by mineral sorting and are relative stable during the holocene we propose a three endmembers i e the changjiang the huanghe and korean rivers mixing model to explain sediment provenances in the central yellow sea mud cysm mixing calculations show that the huanghe is the major sediment contributor to the cysm before 8 ka thousand years before 1950 ce whereas the changjiang has become the predominant sediment source after 8 ka holocene changes in riverine sediment supplies to the cysm are closely related to the oceanic circulation monsoon climate and drainage changes after examining several hypotheses to explain the variations in 87sr 86sr ratios of core ysc 1 during the past 8 kyr we tentatively attribute that to changes in the erosion patterns of the changjiang basin this in turn is associated with the asynchronous evolution of monsoon precipitation in the upper indian summer monsoon and middle lower changjiang east asian summer monsoon therefore our results highlight significant influences of monsoon climate on erosion patterns within the changjiang catchment at millennial timescales

a diagnostic model of summer circulation on the northwest shelf of the east china sea abstract hydrographic data and moored current meter records collected during a cruise of the china u s joint study in august 1981 were used to compute the circulation in the east china sea a steady state linear diagnostic model with a constant vertical eddy viscosity was developed lateral friction was ignored the taiwan warm current plays a dominant role in the survey area both the huanghai warm current and the cyclonic cold water gyre southwest of cheju island are closely related to the taiwan warm current

aquaplanet experiments using cam s variable resolution dynamical core abstracta variable resolution option has been added within the spectral element se dynamical core of the u s department of energy doe ncar community atmosphere model cam cam se allows for static refinement via conforming quadrilateral meshes on the cubed sphere this paper investigates the effect of mesh refinement in a climate model by running variable resolution var res simulations on an aquaplanet the variable resolution grid is a 2 222 km grid with a refined patch of 0 25 28 km resolution centered at the equator climatology statistics from these simulations are compared to globally uniform runs of 2 and 0 25 a significant resolution dependence exists when using the cam version 4 cam4 subgrid physical parameterization package across scales global cloud fraction decreases and equatorial precipitation increases with finer horizontal resolution resulting in drastically different climates between the uniform grid runs and a physics induced grid imprinting in the var res simulation

recent sediment accumulation and origin of shelf mud deposits in the yellow and east china seas abstract modern last 100 yr accumulation rates of shelf mud deposits in the yellow and east china seas were investigated using the distribution of excess 210pb 210pbex in sediment core samples compilation and merger of new and previously published data helped clarify sediment accumulation in these seas the estimated accumulation rates together with data of suspended sediment concentrations provided findings on the sediment budget origin and transport pathway of the mud deposits the overall accumulation distribution in the yellow and east china sea shelf revealed a general cross shelf decreasing trend along the sediment dispersal system away from the rivers except for the south sea ssm and southeastern yellow sea seysm mud patches found along the korean coast notably 210pbex activity profiles within the ssm and the seysm yielded a relatively high accumulation rate of 2 5 mm yr implying a sedimentation rate of 4 15 107 tons per year in this coastal zone such an annual accumulation rate is about one order of magnitude greater than the total sediment discharge 6 20 106 tons yr from korean rivers suggesting an additional offshore source the distribution pattern of the well defined suspended plume clearly showed the possible transport and exchange of fine grained sediments between the ecs shelf and the coastal area of korea especially during winter such a high accumulation in korean coastal areas is attributable to the sediments supplied from the mud deposit of the ecs i e swcim with origins in chinese rivers therefore the korean coastal area may be an important sink for some of chinese river sediments being transported from the south by the yellow sea warm current

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

sedimentary record of environmental evolution off the yangtze river estuary east china sea during the last 13 000 years with special reference to the influence of the yellow river on the yangtze river delta during the last 600 years abstract a 35 60 m long core ecs 0702 recovered from a water depth of 22 m in the muddy area off the yangtze river estuary was analyzed for sedimentary characteristics clay and detrital mineral components and element geochemistry as well as by ams 14 c dating to document sediment provenance changes and environmental evolution during the postglacial period in the study area on the basis of the lithology the benthic foraminiferal and ostracod assemblages and the ams 14 c ages we divided the core into four depositional units du1 du4 in descending order representing the postglacial sedimentary sequence during the last 13 000 years du 4 was deposited in a littoral to tidal flat environment during 13 000 11 500 cal yr bp du 3 in a nearshore subtidal environment upwards to the nearshore shelf with tidal influence in response to the postglacial sea level rise during 11 500 7400 cal yr bp du 2 in a tide affected nearshore shallow sea environment during 7400 540 cal yr bp on the delta front of the yangtze river when the delta was actively prograding and du 1 in a nearshore shallow sea environment during the last 540 years on the delta front under modern marine conditions in du 1 the depositional rate was much higher than in the underlying units and the sediment composition reflects more influence from the yellow river this unit can therefore be logically linked to the period when the yellow river last discharged into the south yellow sea from ad 1128 to 1855 according to historical records this period can be divided into an early stage ad 1128 1494 when the shoreline near the yellow river mouth was advancing slowly eastward and a late stage 1495 1855 when the shoreline was advancing rapidly the initiation of du 1 deposition corresponds to the latter part of the early stage suggesting that since that time a relatively large amount of sediment from the old yellow river mouth area has been transported to the offshore area of the yangtze river mouth our study has identified a high resolution sedimentary signature associated with the last course shift of the yellow river in the yangtze river delta front thus highlighting the intricate relationship between sediment sources and sinks in coastal areas a significant contribution of the old yellow river sediments to the yangtze subaqueous delta during the last 600 years must be considered when the evolutional history of the yangtze delta is examined and especially when the influence of the three gorge dam construction on the future changes of the yangtze estuary and ecological environments in the east china sea is estimated

sedimentary evolution of the holocene subaqueous clinoform off the shandong peninsula in the yellow sea abstract a subaqueous clinoform wraps around the end of the shandong peninsula in the yellow sea the clinoform previously called the shandong mud wedge is up to 40 m thick nearshore and thins seaward its origin has been controversial since it was first noted in the 1980s for our recent investigation offshore of the northeastern shandong peninsula high resolution shallow seismic profiles covering about 1700 km were obtained and two drilling cores penetrating the clinoform were recovered we described the lithofacies characteristics identified benthic foraminifera and ostracoda measured grain size analyzed the mineral components of the cores and obtained ams 14 c dates on 28 samples to decipher the sedimentary evolution of the clinoform in response to postglacial sea level changes the shallow seismic profiles show that the clinoform comprises three units a lowermost seismic unit su 3 less than 2 3 m thick showing a retrogradational aggradational stacking pattern with subhorizontal internal reflectors a middle seismic unit su 2 up to 35 m thick showing a prograding reflection pattern with mostly seaward stepping reflectors separated by several erosive surfaces and an uppermost seismic unit su 1 maximum thickness 18 m exhibiting an aggradational reflection pattern with subparallel reflectors the three seismic units are bounded on the bottom by distinct erosion surfaces analyses of the two cores indicate that the clinoform comprises three depositional units du 1 du 2 and du 3 in descending order corresponding respectively to su 1 su 2 and su 3 the depositional units are distinguished by lithofacies characteristics and the downcore distributions of benthic foraminiferal and ostracod assemblages mineral components of the cores suggest that the clinoform s provenance is predominantly yellow river derived sediments ams 14 c dates suggest that du 3 was formed from about 11 6 to 9 6 cal kyr bp du 2 from 9 6 to 6 5 cal kyr bp and du 1 after ca 6 5 cal kyr bp some major meltwater pulse mwp events during the deglacial transgression were registered in the clinoform stratigraphy with the basal surfaces sediments of du 3 and du 2 corresponding respectively to mwp 1b ca 11 6 11 3 cal kyr bp and mwp 1c ca 9 6 9 2 cal kyr bp events and with du 2 being largely formed after the 8 4 8 2 cal kyr meltwater event rapid centennial to multidecadal scale flooding events were presumably responsible for the erosive surfaces separating the downlapping internal reflectors in su 2 the change of depositional pattern from progradational in su 2 to aggradational in su 1 is attributed to a change from strong dominantly to and fro tidal currents to the modern circulation in the bohai sea as well as to the weakening of the tidal current field during the highstand after about 6500 cal yr bp as a product of complex interactions among sediment supply sea level changes and hydrodynamic regimes the clinoform can be regarded as the distal part of the tidal depositional system in the eastern bohai sea which was largely derived from the yellow river

late quaternary paleoenvironmental changes in the southeastern yellow sea korea abstract a 34 meter long ams 14 c dated sediment core was examined in order to reconstruct the paleoenvironmental changes that have taken place in the southeastern yellow sea during the last 16 600 years to achieve this we analyzed the geochemical compositions of organic matter the benthic foraminiferal assemblages and the stable isotopes of benthic foraminiferal tests the organic geochemical results show that terrigenous organic matter was dominant in the southeastern yellow sea between 16 600 and 4300 cal yr bp probably due to the influence of river runoff marine organic matters originating from surface primary productivity began increasing drastically after 4300 cal yr bp benthic foraminiferal assemblages reveal that brackish species were dominant before 3500 cal yr bp but the saline species dominated after this time the 18 o values of the benthic foraminifer cibicides lobatulus showed that a change from high amplitude to low amplitude fluctuations took place at 3500 cal yr bp these multi results indicate that the southeastern yellow sea changed from an estuarine to a modern marine shelf environment probably due to the inflow of the yellow sea warm current between 4300 and 3500 cal yr bp the time discrepancy of 800 years indicates that a modern marine shelf environment was not fully developed in the southeastern yellow sea until 3500 cal yr bp even though the sea began to be influenced by the oceanic current at 4300 cal yr bp

sediment transport in the yellow sea and east china sea abstract eight survey cruises in different seasons have been conducted in the yellow sea ys and east china sea ecs during the period from 2000 to 2008 suspended sediment concentration ssc and hydrological data were collected during each cruise data analysis showed that total suspended sediment mass was approximately 0 18 109 tons in the surveyed area during spring and autumn seasons highly turbid waters were found in the shallow waters between the subei coast the changjiang estuary and the zhejiang coast with seasonal variations the investigation provided convincing evidence that suspended sediments were transported from the subei coast and the southern entrance of the yellow sea trough to the central ys muddy patches were found at the sea bed when tidal currents were too weak to erode the bottom sediments and water column stratification and eddies provided favorable conditions for trapping the fine grained suspended sediments the investigation indicated that the different front may have different effect on sediment transport during different seasons the front between the yellow sea cold water and the coastal water in the subei coast appeared to trap the high ssc sediments on the shallow water side of the front during summer the front along the zhejiang coast seemed to prevent suspended sediments from transport across the front due to circulation in the front zone and upwelling along the zhejiang coast during winter sediments were likely transported across the front to the central continental shelf of the ecs with the help of the downwelling and lateral ekman transport driven by monsoon winds

delta progradation and chenier formation in the huanghe yellow river delta china abstract to clarify holocene development of the huanghe yellow river delta and the relationship between delta progradation and chenier formation detailed sediment analyses and high resolution radiocarbon dating were done on borehole samples taken from two sites on the present huanghe h9601 latitude 37 40 5 n and longitude 118 28 7 e with an altitude of 5 5 m and h9602 lat 37 47 8 n and long 118 54 3 e 4 8 m downcore changes of sediment facies and accumulation rate show that delta progradation occurred at least twice during ca 2 6 1 2 c 14 yrbp and 1855 present at the two borehole sites these phases of progradation correlate with superlobes 6 and 7 and superlobe 10 respectively of ten superlobes composing the holocene huanghe delta shown by c xue historical changes in the yellow river delta china marine geology 113 321 329 1993 the boundary of these sediments at h9602 is sharp and erosional and correlates with cheniers located between borehole sites on the delta plain the diastem period between these phases of progradation almost coincides with the periods when the river mouth of the huanghe was located in the northwestern part of the bohai sea during 1048 1128 ad superlobe 8 and the jiangsu region facing the yellow sea during 1128 1855 superlobe 9 this suggests that chenier formation and delta progradation are linked and controlled by sediment supply and river course shifts of the lower reaches of the huanghe

high resolution unsaturated alkenones sea surface temperature records in the yellow sea during the period of 3500 1300 cal yr bp abstract high resolution sea surface temperature records based on long chain unsaturated alkenones u 37 k sst in the south yellow sea ys during the period of 3500 1300 cal yr bp were reconstructed in sediment core z8 from the shandong mud wedge the sst records show broad variations between 14 3 and 16 9 c 15 6 c on the average with a high sst phase at 3500 2750 cal yr bp a low and intense fluctuating sst period at 2500 2000 cal yr bp and a sharp cooling period at 1750 1300 cal yr bp superimposed on this trend five cooling periods occurred in 3360 3250 cal yr bp 3150 3050 cal yr bp 2750 2650 cal yr bp 2350 2150 cal yr bp and 1750 1300 cal yr bp variation pattern of the sst records is similar to the fluctuations of the kuroshio current kc indicating a close relationship between the yellow sea warm current yswc and the kc the general u 37 k sst curve fluctuates with the local air temperature variations the intensity of the east asia winter monsoon eawm could be a key factor affected the prevailing relationship between the cold coastal current and the warm yswc and dominated the sst variation in core site z8 during 3500 1300 cal yr bp furthermore our temperature records within age uncertainty coincides with the changes of the solar irradiance changes suggesting a possible link between solar forcing and climate variability

evolution of the coastal depositional systems of the changjiang yangtze river in response to late pleistocene holocene sea level changes abstract the paleo changjiang yangtze incised valley fills approximately 80 90 m thick provide an opportunity to document the evolution of coastal depositional systems with large sediment supply in response to late pleistocene holocene sea level fluctuations on time scales of 103 to 104 years the sedimentary facies of the incised valley fills record three main depositional systems fluvial tide dominated estuary and tide dominated delta radiocarbon ages for the incised valley fills suggest that these depositional systems developed before about 11 ka between 11 and 8 ka and after approximately 8 ka respectively by applying sequence stratigraphic concepts the evolution of the depositional systems can be divided into three systems tracts a lowstand systems tract lst a transgressive systems tract tst and a highstand systems tract hst sea level changes on a 104 year time scale controlled the basic architecture of the sequence of the incised valley fill on the other hand sea level changes on a millennial time scale affected the stacking pattern of the systems tracts in particular the continuous sea level rise with episodic rapid rises during the last deglaciation affected the stacking pattern of the tst which is characterized by a combination of aggradation and backstepping the aggradation of fluvial and estuarine systems was dominant and the shoreline migrated only gradually landward under the relatively slow rise in sea level and a very rapid sea level rise around 12 and 10 ka caused the system to migrate abruptly landward unlike the transgressive estuarine phase the stacking pattern of the regressive tide dominated delta hst which developed within the almost filled incised valley and on the surrounding interfluve zones was characterized by seaward progradation with clinoform architecture it was initiated with aggradational and progradational stacking about 8 ka during the last phase of decelerated sea level rise and was followed by a progradational phase after the highest sea level about 6 ka

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

evidence for a warmer period during the 12th and 13th centuries ad from chironomid assemblages in southampton island nunavut canada abstract this study presents the late holocene evolution of a northern southampton island nunavut canada lake using fossil chironomids supported by sedimentological evidences xrf grain size and cns all proxies revealed a relatively stable environment during the last millennium with short lived events driving changes in the entire lake ecosystem the chironomid based paleotemperatures revealed variations of significant amplitude coincident with changes in the sediment density and chemical composition of the core higher temperature intervals were generally correlated to lower sediment density with higher chironomid concentration and diversity higher temperatures were recorded from cal yr ad 1160 to ad 1360 which may correspond to the medieval warm period between cal yr ad 1360 and ad 1700 lower temperatures were probably related to a little ice age event this study presents new information on the timing of known climatic events which will refine our knowledge of the paleoclimate and climatic models of the foxe basin region it also provides a new framework for the evolution of such freshwater ecosystems under the anthropocene and underlines the importance of including sedimentological proxies when interpreting chironomid remains as this combined approach provides an extended overview of the past hydrological and geochemical changes and their impacts on lake biota

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

holocene paleoenvironment changes in the northern yellow sea evidence from alkenone derived sea surface temperature abstract a well dated high resolution sea surface temperature sst record based on long chain unsaturated alkenones from a northern yellow sea nys sediment core is present in this study variations in linear sedimentation rate alkenone content and sst clearly reveal five distinct stages consistent with changes in local sea level as well as the evolution of the yellow sea warm current yswc before 8 9 cal kyr bp the marine transgression might not reach to the northern part of the nys a shallow coastal environment was formed from 8 9 to 8 5 cal kyr bp with a subsequent fast transgression during 7 8 to 6 5 cal kyr bp after 5 8 cal kyr bp the nys was dominated by a relatively constant marine environment sst records reveal that the yswc was likely to have started since 7 0 cal kyr and strengthened progressively in period of 7 0 5 5 cal kyr bp after 5 5 cal kyr bp the sst elevated about 1 5 c which correlated well to salinity changes along the yswc indicating that the formation time of the modern yswc was at about 5 5 cal kyr bp the sst variation shows a millennial period of 1500 yr and centennial periods of 131 yr and 113 yr the 1 5 kyr cycle dominated the period of 8 9 5 5 cal kyr bp suggesting a tele connection between the yellow sea sst and global climate changes might through the kuroshio current centennial periods dominated almost all of cold periods recorded in core by14 implying the signature of solar irradiance cycles by means of the strengthened east asia winter monsoon eawm

clay sized sediment provenance change in the northern okinawa trough since 22kyrbp and its paleoenvironmental implication provenances of clay sized terrigenous sediments and a comprehensive interpretation of their high resolution variations in the northern okinawa trough since the late last glaciation remain unclear especially in regard to the huanghe and taiwan derived matter grain size clay mineralogy typical elemental ratio oxygen isotope and ams c 14 dating of core pc 1 in the northern okinawa trough were investigated to trace clay sized sediment provenance and transport process and thus to recover their forcing mechanisms over the last 22 kyr variations in linear sedimentation rate grain size delta o 18 ti ca ratio and clay minerals can be clearly divided into three distinct intervals consistent with changes in sediment provenance that can be close related to sea level fluctuation evolution of the tsushima warm current as well as influence from the east asian monsoon climate evolution during the late last glaciation period interval 1 22 16 kyr bp when the tsushima warm current was absent in the east china sea the paleo huanghe mouth was situated close to the study area and thus the paleo huanghe could have played major role in sedimentation therein in interval 2 16 7 3 kyr bp global sea level rise led to gradually retreating of the paleo huanghe mouth and thus decreasing terrigenous sediment supply from it to the study area since 73 kyr bp interval 3 some clay minerals from taiwan might have been transported northward to the study area by the fully evolved tsushima warm current characterized by higher chlorite kaolinite ratios in contrast the decreasing influence of the huanghe derived sediments during the strengthening of the tsushima warm current periods was probably caused by the blocking effect of the tsushima warm current particularly chlorite kaolinite ratio and smectite content in the okinawa trough sediment might be good proxies for indicating the tsushima warm current related sedimentary environment c 2014 elsevier b v all rights reserved

climate modulates the acidity of arctic lakes on millennial time scales high resolution diatom stratigraphies from two lakes on eastern baffin island nunavut canadian arctic are used to reconstruct lake water ph over the past 5 k y despite contrasting geomorphic histories and markedly different diatom floras the inferred ph of both lakes declined in concert with neoglacial cooling this result confirms that climate exerts a first order influence on the acidity of these poorly buffered oligotrophic lakes through links between lake ice cover primary productivity and dissolved inorganic carbon dynamics diatom based ph inferences from dilute lakes can therefore assist paleoclimatic interpretations from lake sediments

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

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

spatial and temporal distributions of clay minerals in mud deposits on the inner shelf of the east china sea implications for paleoenvironmental changes in the holocene abstract we present a paleoclimatic reconstruction for the holocene by clay mineral analyses of sediments from core mz02 retrieved from the mud area of the inner continental shelf of the east china sea ecs the clay minerals mainly consist of illite 66 79 and chlorite 12 19 with minor kaolinite 7 13 and smectite 0 6 provenance analysis suggests that the illite dominated clay minerals were derived mainly from the detrital outputs of the changjiang minjiang and small rivers from taiwan island our study indicates that the sea level rise since the last glacial the strength of the taiwan warm current twc and chinese coastal current ccc have controlled the dispersal and deposition of clay minerals on the ecs that in turn determined the clay mineral compositions in the core sediments during 13 000 9500 bp due to the lower sea level and shorter distance between these three estuaries and core mz02 fine sediments on the inner shelf of the ecs were primarily supplied by mixed provenances from the changjiang taiwanese and minjiang rivers during the early holocene 9500 6200 bp stronger sediment reworking and erosion at the shelf edge was responsible for the increased lateral transport of fine sediments in the ecs which lead to a dominance of the sediment source from the changjiang while the taiwanese and minjiang rivers only provided minor components of detrital sediment to the shelf increased strength of twc might have played an important role in the sediment dispersal and deposition on the inner shelf of the ecs during 6200 2400 bp with a dominance of more than 60 sediments transported from taiwanese rivers furthermore our study implies that the asian monsoon and the weakening of twc were linked to the abrupt increase of changjiang and minjiang derived terrigenous detritus materials since 2400 bp

holocene development of the yellow river s subaqueous delta north yellow sea high resolution seismic profiles from the north yellow sea reveal a 20 40 m thick subaqueous clinoform delta that wraps around the eastern end of the shandong peninsula extending into the south yellow sea this complex sigmoidal oblique clinoform containing an estimated 400 km 3 of sediment overlies prominent relict transgressive surfaces the nearshore topset of the clinoform 50 m contain less than 1 m of holocene sediment with low sedimentation rates 1 mm year in contrast to other clinoforms the shandong clinoform appears to be a compound subaqueous deltaic system with what we interpret to be proximal and distal phases of clinoform development the underlying proximal sequence formed proximally between f11 and 9 2 ka in response to a temporary pause in the rapid postglacial sea level rise after the meltwater pulse 1b mwp 1b and increased discharge from the yellow river to the north yellow sea due to intensification of the summer monsoon a flooding surface appears to separate the proximal and distal phases corresponding to the next rapid sea level rise 9 5 9 2 ka bp mwp 1c since 9 2 ka bp an overlying distal sedimentary sequence has accumulated reflecting the backstepping and shifting river mouth westward to the gulf of bohai some inputs from coastal erosion and nearby small streams may be locally important along shore transport cross shelf advection and upwelling in the north yellow sea have reworked post lgm sediment and have helped maintain the morphology of the clinoform in the shandong mud wedge d 2004 elsevier b v all rights reserved

post glacial climatic change on boothia peninsula nunavut canada abstract a high temporal resolution pollen diagram from a lake in the mid arctic region of the boothia peninsula nunavut canada documents the history of the regional vegetation and climate for the past 7200 yr major tundra pollen taxa in the core include cyperaceae and salix with cyperaceae comprising over 50 of the pollen in the early and late holocene tree pollen transported from far to the south comprised a large percentage of the pollen sum with pinus accounting for 30 of the pollen in some levels of the core pollen percentages and concentrations of taxa typical of the mid arctic were highest in the mid holocene corresponding to warm conditions decreasing pollen concentrations indicate cooling temperatures with more rapid decreases occurring around 4200 3800 3400 and 2500 cal yr bp pollen percentages of salix cyperaceae and artemisia increased in the past 35 yr in response to global warming reconstructions of july temperature using the modern analog technique showed that the mid holocene 5800 2800 cal yr bp was approximately 1 c higher than during the past 1000 yr

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 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

flux and fate of yangtze river sediment delivered to the east china sea numerous cores and dating show the yangtze river has accumulated about 1 16 x 10 12 t sediment in its delta plain and proximal subaqueous delta during holocene high resolution seismic profiling and coring in the southern east china sea during 2003 and 2004 cruises has revealed an elongated similar to 800 km distal subaqueous mud wedge extending from the yangtze river mouth southward off the zhejiang and fujian coasts into the taiwan strait overlying what appears to be a transgressive sand layer this distal clinoform thins offshore from similar to 40 in thickness between the 20 and 30 m water depth to 1 2 in between 60 and 90 m water depth corresponding to an across shelf distance of less than 100 km total volume of this distal mud wedge is about 4 5 x 10 11 m 3 equivalent to similar to 5 4 x 10 11 t of sediment most of the sediment in this mud wedge comes from the yangtze river with some input presumably coming from local smaller rivers thus the total yangtze derived sediments accumulated in its deltaic system and east china sea inner shelf have amounted to about 1 7 x 10 12 t preliminary analyses suggest this longshore and across shelf transported clinoform mainly formed in the past 7000 yrs after postglacial sea level reached its mid holocene highstand and after re intensification of the chinese longshore current system sedimentation accumulation apparently increased around 2000 yrs bp reflecting the evolution of the yangtze estuary and increased land erosion due to human activities such as fanning and deforestation the southward flowing china coastal current the northward flowing taiwan warm current and the kuroshio current appear to have played critical roles in transporting and trapping most of yangtze derived materials in the inner shelf and hence preventing the sediment escape into the deep ocean c 2006 elsevier b v all rights reserved

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

watershed scale reconstruction of middle and late holocene paleoenvironmental changes on melville peninsula nunavut canada abstract arctic regions have heightened sensitivity to climatic changes however regional scale differences exist in the magnitude and timing of biotic responses melville peninsula in the east central canadian arctic is a transitional area with respect to modern climate with a continental climate to the west and more maritime influences to the east this and the presence of thule archaeological sites make the peninsula an area of high importance for paleoclimate reconstructions lake sediment cores from two adjacent ultra oligotrophic and very dilute lakes sp02 and sp04 from interior melville peninsula 68 33 n and 83 17 w 220 m a s l were analyzed for diatom assemblages microscopic algae to track paleoclimatic changes high magnetic susceptibility coarse grained sediments low organic matter and lack of diatoms in sediments older than 6000 years bp confirm earlier suggestions of a persistent ice cap on the peninsula peak diatom concentration and biogenic silica and maximum values for sediment organic matter between 4400 and 2900 years bp may indicate the holocene thermal maximum htm the timing of the htm is similar to that of the baffin region to the east decreases in these proxies as well as small shifts in diatom assemblages following 2900 years bp indicate the advancement of neoglacial cooling the changes of the pre industrial portion of the last millennium were of smaller magnitude than those of the htm but subtle changes in diatom assemblages after 750 years bp may be indicative of the little ice age the timing of which agrees well with that of boothia peninsula to the west the anthropocene is well marked in these records with increases in diatom species richness from a pre industrial maximum of 28 51 diatom species in the modern assemblage at lake sp02 planktonic diatoms appear in the 20th century signalling profound ecological changes associated with longer ice free seasons

the supply and accumulation of silica in the marine environment rivers and submarine hydrothermal emanations supply 6 1 1014g sio2 yr to the marine environment approximately two thirds of the silica supplied to the marine environment can be accounted for in continental margin and deep sea deposits siliceous deep sea sediments located beneath the antarctic polar front convergence account for over a fourth 1 6 1014g sio2 yr of the silica supplied to the oceans deep sea sediment accumulation rates beneath the polar front are highest in the south atlantic with values as large as 53cm kyr during the last 18 000 yr siliceous sediments in the bering sea sea of okhotsk and subarctic north pacific accumulate 0 6 1014g sio2 yr or 10 of the dissolved silica input to the oceans the accumulation of biogenic silica in estuarine deposits removes a maximum of 0 8 1014g sio2 yr although estuarine silica versus salinity plots indicate extensive removal of riverine silica from surface waters the removal rates must be considered as maximum values because of dissolution of siliceous material in estuarine sediments and bottom waters siliceous sediments from continental margin upwelling areas e g gulf of california walvis bay or peru chile coast have the highest biogenic silica accumulation rates in the marine environment 69 g sio2 cm2 kyr despite the rapid accumulation of biogenic silica upwelling areas account for less than 5 of the silica supplied to the marine environment because they are confined laterally to such small areas

recent warming in a 500 year palaeotemperature record from varved sediments upper soper lake baffin island canada laminated sediments from upper soper lake on southern baffin island provide a new 500 year record of temperature change in the arctic radiometric dating using 210pb and pu shows that the light and dark coloured laminae couplets are annually deposited varves dark laminae thickness is strongly correlated to average june temperature from kimmirut r 0 82 reflecting the influence of temperature on snowmelt and fluxes of runoff and suspended sediment this relationship allowed the construction of a palaeotemperature record that documents large amplitude interannual to decadal variability superimposed on distinct century scale trends including 2 c average warming and maximum temperatures during the 1900s similar patterns of change are seen in individual and regionally averaged palaeotemperature records from around the circum arctic upper soper lake records temperatures rates of change and variance during the twentieth century that are all anomal ously high within the context of the last 500 years and outside the observed range of natural variability comparisons of upper soper lake and arctic average palaeotemperature to proxy records of hypothesized forcing mechanisms suggest that the recent warming trend is mostly due to anthropogenic emissions of atmos pheric greenhouse gases the magnitude of the warming and decade scale variability throughout the records however indicate that natural forcing mechanisms such as changing solar irradiance and volcanic activity as well as positive feedbacks within the arctic environment also play an important role

depositional development of an isolated mound and adjacent area in the southern yellow sea during the last postglacial sea level rise abstract a detailed analysis of the chirp 2 7 khz profiles core sediments and 14c ages from an isolated mound and adjacent area in the southern yellow sea off the jiangsu coastal area reveals a highly complex development of transgressive and highstand deposits during the last postglacial sea level rise in water depths of 50 60 m the terrace consists of thin transgressive sediments directly above transgressive surface the isolated mound 40 7 km long and 29 6 km wide occurs above 40 50 m in water depth and is detached from the jiangsu and east china sea tidal sand ridges it comprises the sse ward prograding sandy unit pu and the overlying muddy flank unit fu at the outer margin the terrace with thin transgressive sediments was most likely formed when sea level rose rapidly from 58 to 45 m around about 11 6 ka as rate of sea level rise was attenuated from 45 to 36 m between ca 11 6 and 9 6 ka the nearly flat lower boundary of the pu was produced at water depths of 37 42 m by a ravinement process subsequent rapid sea level rise from 36 to 16 m between ca 9 6 and 9 1 ka created accommodation for deposition of the pu sea level rise stagnated from 16 to 10 m between ca 9 1 and 7 5 ka during which the huanghe river apparently shifted south of the shandong peninsula and discharged directly into the western yellow sea the combination of slow sea level rise and sediment supply from the early holocene huanghe delta by the southward flowing coastal currents most likely favoured the formation of the sse ward prograding transgressive sandy pu the highstand muddy fu overlying the pu was accumulated after ca 7 5 when sea level approached its present position and the huanghe river shifted back to the north development of transgressive and highstand deposits in the study area during the last postglacial sea level rise was highly variable in time and space in response to changes in rate of sea level rise together with variations in sediment supply caused by the shifting of the huanghe river

transport pathway and depocenter of anthropogenic heavy metals off the shandong peninsula china abstract surface sediment grain size as well as the spatial distribution sources and geochemical baseline levels of heavy metals in the south shandong peninsula clinoform were analyzed to determine the transport pathway and main depocenter of anthropogenic heavy metals off the peninsula results showed that the surface sediments were primarily silt sized components and the fine grain matter mainly originated from the yellow river and rivers around laizhou bay heavy metals cu pb zn cr and cd were predominantly from natural sources and their spatial distributions were controlled by grain size conversely anthropogenic as concentration above geochemical baseline level 10 9 mg kg was principally derived from human activities and its transportation from the yellow river and laizhou bay was controlled by the shandong coastal current off the shandong peninsula furthermore the anthropogenic as was deposited in three main areas that is the yellow river estuary laizhou bay and south shandong peninsula clinoform

diatom community responses to late holocene climatic variability baffin island canada a comparison of numerical approaches a high resolution diatom stratigraphy from the late holocene sediments of a small arctic lake on bafe n island nunavut canada has been analysed by several numerical methods and considered in relation to independent palaeoclimatic proxies to enable an objective assessment of the response of freshwater diatom communities to climatic change diatom relative frequencies and absolute abundances were subjected to several manipulations including application of a weighted averaging transfer function for summer water temperature conversion of valve concentrations to cell biovolumes biostratigraphic rate of change and taxonomic richness estimated by rarefaction analysis the major directions of variability within the derived diatom data were explored using principal components analysis diatom inferred lakewater temperatures and indices of diatom palaeoproductivity declined during late holocene cooling and they faithfully record post little ice age warm ing between 2000 cal bp and the little ice age which includes the coldest intervals of the neoglacial diatom assemblages diversie ed and destabilized ree ecting a state of intermediate disturbance together these results examine different methods of interpreting freshwater diatom stratigraphic data with the objective of gaining palaeoclimatic insights from fossil assemblages

the huanghe and changjiang contribution to seasonal variability in terrigenous particulate load to the okinawa trough abstract terrigenous particulate load transported to the okinawa trough was examined using time series sediment trap samples collected in 1993 1994 at sst 1 29 21 6 n 128 13 5 e 1100 m water depth lateral transport through the bottom layer was important in transport of terrigenous particles from shelf to the trough flux reached a maximum in spring reflecting seasonal change although a short period of transport also occurred in the late summer unrelated with the general seasonal change mineralogical and chemical analyses revealed that contributions from sediment sources changed seasonally a changjiang yangtze river influence was relatively high during winter while the huanghe yellow river and or eolian derived sediment was enhanced in spring and late summer when the total flux also intensified

quantitative reconstruction of holocene sediment source variations in the yellow and northern east china seas and their forcings abstract sediment provenance in the yellow sea and northern east china seas yecss has long been a subject of interest but its quantification is still inconclusive here we present an improved al mg regression analysis by refining its methodological approach to strengthen quantification of sediment source to sink transports in the yecss with focus on its forcing mechanisms during the holocene our quantitative source estimates clearly depict a considerable supply of the chinese river cr sediments 50 to the southwestern korean coastal region and the korean river kr sediments 30 40 to the central yellow sea mud deposit which accounts for a good balance between the sediment supply and budget of the shelf deposit of particular note is an abrupt decline in the cr contributions around 124 e which indicates that the cr sediments do not directly reach the eastern part of the yellow sea blocked by a strong physical boundary further the observed variations in proportions between huanghe changjiang and korean river derived sediments over the last 15 kyr notably an abrupt increase of cr contribution since 7 ka followed by a sudden drop at 3 4 ka exhibit a good correspondence with other mineralogical proxy records these temporal provenance changes witnessed robust palaeoenvironmental signals which fit to major climatic and oceanographic events linked with sea level intensity of the kuroshio current inflow and the east asian monsoon this study improves understanding of what pathways and sinks exist within the yecs basin and how rates of sediment supply from adjacent rivers have changed over time

an early holocene sea level jump and delta initiation 1 early holocene sea level change controlled the evolution of clastic coastal depositional systems radiocarbon dated borehole cores obtained from three incised valley fill systems in asia changjiang song hong and kiso river record very similar depositional histories especially between about 9000 and 8500 cal bp sedimentary facies changes from estuarine sand and mud to shelf or prodelta mud suggest that the marine influence in the incised valleys increased during this period in addition large decreases in sediment accumulation rates occurred a sea level jump causes an estuarine system and its depocenter to move rapidly landward it is possible that the final collapse of the laurentide ice sheet accompanied by catastrophic drainage of glacial lakes at approximately 8500 cal bp caused such a jump the jump was followed immediately by a period of decelerated sea level rise that promoted delta initiation

initiation of the changjiang yangtze delta and its response to the mid holocene sea level change abstract the changjiang yangtze delta in eastern china is one of the largest tide dominated deltas in the world to obtain a more detailed information on its initiation we drilled three sediment cores pk01 hg01 and xj03 from the uppermost region of the delta plain on the basis of sedimentary facies and ams 14c dating we identified three depositional systems 1 a fluvial system 2 an estuarine system and 3 a deltaic system including an initial delta estuary delta transition and a typical delta the maximum flooding surface separates the estuarine and deltaic systems and occurred at ca 8 0 cal kyr bp when brackish water intruded landward and reached the nanjing area the changjiang delta was initiated at the area between nanjing and yizheng when the sea level rise decelerated after the rapid rise in sea level during 9 0 8 2 cal kyr bp the subsequent evolution of the changjiang delta has been shown as a seaward development model of river mouth bars with shoreline migration the oldest river mouth bar called hongqiao sand body which is located most landward was dated at 6 0 5 5 cal kyr bp in this study nearly one thousand years younger than the previous estimates a tide dominated funnel shaped estuary was formed at 8 0 cal kyr bp and lasted until the hongqiao sand bar became exposed this stage is regarded as an aggradation dominated initial stage of the changjiang delta followed by a progradation dominated stage that is characterized by the formation of a series of seaward migrating river mouth bars a relative sea level highstand in the mid holocene may be associated with glacio hydro isostatic tilting

sr nd isotopic constraints on terrigenous sediment provenances and kuroshio current variability in the okinawa trough during the late quaternary abstract the okinawa trough in the east china sea continuously receives terrigenous sediments from the surrounding east asian continent during the late quaternary which makes it an ideal site for the studies of land sea interaction and sediment source to sink transport geochemical and sr nd isotopic compositions of the detrital sediments in the middle okinawa trough allow the provenance discrimination and the reconstruction of paleoenvironmental changes over the last 30 ka large variations in 87 sr 86 sr ratios and e nd values occur between 14 0 and 7 1 ka suggesting a significant change in sediment provenances from the dominance of the changjiang yangtze river and or continental shelf to that of taiwan island during the last glacial maximum the continental shelf was largely exposed and the fine grained sediments from the changjiang and the shelf with higher 87 sr 86 sr ratios and lower e nd values might be transported directly into the middle okinawa trough with the sea level rise during the deglacial period the strengthening kuroshio current increasingly delivered taiwan derived fine sediments lower 87 sr 86 sr ratios and higher e nd values to the middle trough while the sediment contribution from the east asian continent became subordinate this study suggests that the changes in sea level and the kuroshio current pathway during the late quaternary predominantly determined the dispersal and deposition of the terrigenous sediments in the okinawa trough and the kuroshio current might have obviously influenced the okinawa trough since 14 ka this study illustrates that the radiogenic isotopic compositions of the fined grained sediments are sensitive proxies to trace the sediment provenance and to reconstruct oceanic circulations in the west pacific marginal seas

surface water evolution of the eastern east china sea during the last 36 000 years abstract planktic foraminifera have been studied in two high resolution cores raised from the continental slope of the eastern east china sea ecs to reconstruct the surface water history ams 14c dating on fifteen horizons revealed that the two cores kh82 4 14 and rn80 pc3 contain continuous records of the last 36 and 17 thousand cal years respectively thirty one planktic foraminiferal species which are commonly found in the present western north pacific and the ecs are recognized in down core samples three faunal phases iii ii and i distinguished by characteristic planktic foraminiferal assemblages suggest three major paleoenvironmental stages of the surface water of the eastern ecs since 36 000 yr b p 1 a stage influenced by coastal water from 36 000 to 19 500 yr b p 2 a stage also influenced by coastal water and extremely low salinity from 19 500 to 10 500 yr b p and 3 a stage controlled by the modern open sea water related to the kuroshio with both higher temperature and higher salinity since 10 5 8 5 thousand years b p oxygen isotope records of the planktic foraminiferal species g bulloides show that the three planktic foraminiferal faunal phases correspond to the last glacial deglacial and postglacial stages respectively the planktic foraminiferal assemblage during the deglacial stage which is represented by high percentages of g quinqueloba is quite different from those during the glacial and postglacial stages linked to a large amount of river discharge from the chinese continent a negative oxygen isotope excursion in g bulloides during the same period is highly correlated to the g quinqueloba anomaly also indicating a decrease in surface water salinity furthermore the sedimentation rate of core kh82 4 14 during 19 15 thousand years b p is much higher than the rates during the glacial and postglacial stages suggesting a great increase in the supply of terrigenous material related to an increased river and sediment discharge during the early deglaciation the coastal water influenced stage of the eastern ecs terminated gradually at 10 5 8 5 thousand years b p since the warm kuroshio current and its branches flowed in the eastern ecs as today the formation of the postglacial surface water circulation pattern in the eastern ecs was closely related to the flow patterns of the kuroshio current

magnetic evaluation of sediment provenance in the northern east china sea using fuzzy c means cluster analysis abstract to identify the provenance of fine grained sediments in the northern east china sea various magnetic parameters indicating concentration magnetic susceptibility susceptibility of anhysteretic remanent magnetization arm and saturation of isothermal remanent magnetization sirm mineral composition s 300 irm 300 mt sirm and hirm 50 sirm irm 300 mt sirm and grain size frequency dependent magnetic susceptibility fd arm sirm and s 20 irm 20 mt sirm were measured from surface sediments collected at 98 regularly spaced sites as an unbiased analytic tool fuzzy clustering analysis was performed on data from 97 sites except an outlier each dataset for each site comprised magnetic parameters representing ultrafine superparamagnetic fd fine single domain or pseudo single domain arm sirm and coarse multidomain s 20 fractions and the relative dominance of low and high coercivity minerals s 300 and hirm respectively the statistical analysis yielded four clusters indicating that the sediments in the study area can be differentiated magnetically of the magnetic properties of the cluster centers the most distinctive feature of cluster 1 is a predominance of coarse grained magnetic minerals highest s 20 value while the contribution of high coercivity minerals is highest in cluster 2 highest hirm value ultrafine and fine grained fractions are prominent in cluster 3 highest fd and arm sirm values while cluster 4 has the highest ratio of low to high coercivity minerals highest s 300 value related to sediment provenance the sediments of cluster 1 are interpreted to have been derived from the yangtze river in china the old yellow river deposits are the primary source of sediments in cluster 2 sediments in cluster 3 were probably transported from taiwan or the northwest pacific by the taiwan warm current or the kuroshio current respectively while korean river deposits are the most probable sources of sediments in cluster 4

ree geochemistry of fine grained sediments from major rivers around the yellow sea abstract to investigate the distribution pattern and controlling factors of rare earth elements rees in riverine sediments river mouth sediments were collected at five geographically different rivers around the yellow sea two 1 m hcl leached and residual fractions and five step sequential extraction schemes the sedex method were applied to size separated sediments

mineralogical and isotopic evidence for the sediment provenance of the western south yellow sea since mis 3 and implications for paleoenvironmental evolution abstract changing sediment provenance and related paleoenvironmental evolution since marine isotope stages mis 3 have been investigated based on accelerator mass spectrometry ams 14c and optically stimulated luminescence osl dating of core csdp 01 recovered from the western south yellow sea sys based on our results sea level fluctuations and monsoonal climate variations are identified as the principal factors driving these changes sea level fluctuations determined the accommodation space in the shelf area while the monsoonal climate controlled the sediment supply capacity from river to sea mineral and sr nd isotopic records reveal the major contribution of the paleo changjiang river yangtze river to the study core area during the early mid mis 3 which likely defined the northern limit of the paleo changjiang delta at that time high sediment supply and limited accommodation space led to the development of sediment fed systems on the sys shelf resulting in a high preservation potential for thick stacking and overlapping deltaic sediments along with deltaic progradation core sediment provenance gradually transformed from the paleo changjiang river to the paleo huanghe river yellow river near the late mis 3 implying that the paleo huanghe river likely emptied into the sys and built a large delta during the mis 3 interval a strong summer monsoon during the early mis 1 interval was favorable for the changjiang to deliver abundant sediments to the study core area a weak summer monsoon during the mid late mis 1 when the coastline had retreated to nearly its present day position decreased the changjiang and huanghe supply to the study area low sediment supply and sufficient accommodation space gave rise to the development of sediment starved systems during this period nd values fluctuated between the changjiang and huanghe sources at that time suggesting that sea bed erosion materials are the main sediment contribution to the study area in general sedimentary evolution in the western sys since mis 3 is a good example of river sea interaction in the marginal seas of southeast asia in which sea level and monsoonal climate changes should play an important role

a diatom based holocene palaeoenvironmental record from a mid arctic lake on boothia peninsula nunavut canada a 485 cm sediment core from a lake unoffcially called jr01 boothia peninsula nunavut canada yielded a high resolution diatom record documenting environmental change in the mid arctic five radi

an exploratory model study of sediment transport sources and deposits in the bohai sea yellow sea and east china sea a regional ocean circulation model roms is used to simulate the chinese land derived sediment transport in the bohai sea yellow sea and east china sea byecs the model includes the effect of currents tides and waves on the sediment transport and is used to study the pathway and dynamic mechanisms of the fine grain sediment transport from the huanghe river yellow river the old huanghe delta and the changjiang river yangtze river in the byecs the seasonal variability of the sediment transport in the byecs and the sources of the yellow sea trough mud patch the mud patch southwest of cheju island the mud patch offshore from the zhejiang and fujian provinces and the okinawa trough mud patch are discussed the results show that the huanghe river sediment can be transported to the yellow sea trough but little makes it to the outer shelf while the old huanghe delta sediment is mainly transported to the yellow sea trough most of the sediment from the changjiang river mouth is carried to the mud patch off the coast of the zhejiang and fujian provinces but with part of this sediment also transported to the yellow sea trough the model shows that it is difficult to transport land derived sediment to the okinawa trough mud patch under normal conditions the model also has difficulty accounting for the deposition of sediment in the region to the southwest of cheju island and offshore from the zhejiang and fujian provinces an issue requiring further study

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

delta development and channel incision during marine isotope stages 3 and 2 in the western south yellow sea abstract approximately 4100 km of high resolution seismic profiles recently obtained from the western south yellow sea were subdivided into seven seismic units by six major seismic surfaces three sediment cores between 60 and 71 m in length obtained from localities on the seismic profile lines were analyzed for sedimentary characteristics clay mineral components and benthic foraminiferal and ostracod assemblages and were also dated by ams 14 c and optically stimulated luminescence to document the environmental history of the region stratigraphic units in the cores were confidently correlated with seismic units in the profiles stratigraphic correlation among these three cores and the previous well studied core qc 2 was facilitated by the cold water deposits in marine isotope stage mis 5 the three cores document the sedimentary sequence during the period from mis 6 up to mis 1 strata formation and sedimentary environment changes since mis 5 are strongly controlled by sea level fluctuations most of the successions were formed in mis 5 mis 3 and mis 1 with major erosions in mis 4 and mis 2 particularly our data revealed the presence of a large delta active during mis 3 likely from the early stage of mis 3 to about 40 cal kyr bp that was subsequently affected by channel incision the delta succession and incised channel fills have a high concentration of smectite in their clay mineral components suggesting that the paleo yellow river was the main contributor to the delta development and channel incision the delta sequence has a coarsening upward trend and consists of two seismic facies the upper facies shows lateral alternations of chaotic and oblique or very low angle reflectors which correspond to sandy proximal delta front and delta plain facies and the lower facies is characterized by seaward dipping clinoforms which correspond to muddy distal delta front and prodelta facies the top surface of the delta inclines very gently seaward consistent with a deltaic development associated with the sea level fall in mis 3 the incised channel system consists of two main channels with multiple tributaries in a dendritic pattern the incised channel fills begin with fluvial and then estuarine sediments which are truncated by a transgressive ravinement surface and capped by transgressive deposits the main incision channels have a terraced cross sectional morphology which is interpreted to reflect multiple episodes of sea level fall during incision presumably from the late mis 3 to the last glacial maximum

sediment provenance and paleoenvironmental change in the middle okinawa trough during the last 18 5 ky clay mineral and geochemical evidence abstract we investigated grain size clay mineralogy elemental geochemistry organic composition and ams 14 c dating ages in core kx12 3 from the middle okinawa trough in order to better understand the sediment provenances and transport processes and also the forcing mechanisms behind their variations over the last 18 5 ky the geochemical mineralogical indices reveal three notable phases of change in the sediment provenance of the core which are related to the development of the kuroshio current coupled with sea level fluctuations the position shift of the mouths of large rivers the magnitude of tidal bottom stress and the east asian monsoon intensity the sea level lowstand deposits of interval 1 18 5 9 3 ka formed from mixed sediments originating mostly from chinese rivers the paleo huanghe and the paleo changjiang as well as from materials eroded from seafloor by the strong tidal stress thereafter during interval 2 9 3 8 7 ka a significant sea level rise the moderate tidal bottom stress and a gradual landward retreat of river mouths led to obviously decreased sediment supplies from both seafloor erosion and mainland china rivers especially the paleo huanghe into to the study area after this transitional period the dominant sediment provenance during the mid to late holocene interval 3 changed to the changjiang and seafloor erosion resulting in lower detrital linear sedimentation rate and finer grain size at the same time some fine grained materials from taiwan may have been transported northward to the study area by the kuroshio current as evidenced by higher values of chlorite kaolinite ratio and chemical index of illite and lower toc tn values in addition a prominent decline in chlorite kaolinite values that occurred at 5 0 3 5 ka may have been linked to a suppression of the kuroshio current probably related to the pulleniatina minimum event and or the late holocene neoglacial cold event commonly found in the northwestern pacific

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

asian provenance of glacial dust stage 2 in the greenland ice sheet project 2 ice core summit greenland samples of dust from the greenland ice sheet project 2 gisp2 ice core summit greenland dated within marine isotope stage 2 between 23 340 and 26 180 calendar years b p around the time of the coldest local last glacial temperatures have been analyzed to determine their provenance to accomplish this we have compared them with approximately coeval aeolian sediments mostly loesses sampled in possible source areas psas from around the northern hemisphere the 5 m grain size fraction of these samples was analyzed on the basis that it corresponds to the atmospheric dust component of that time and locale which was sufficiently fine grained to be transported over long distances on the basis of comparison of the clay mineralogy and sr nd and pb isotope composition with ice dust and psas and assuming that we have sampled the most important psas we have determined that the probable source area of these gisp2 dusts was in eastern asia the dust was not derived from either the midcontinental united states or the sahara two more proximal areas that have been suggested as potential sources based on atmospheric circulation modeling except for a brief period during an interstadial when dust transport was exceptionally low for glacial times and had a mineralogical composition indicative of a slightly more southern provenance the source area of the dust did not change significantly during times of variably higher fluxes of dust with larger mean grain size or lower fluxes of dust with smaller mean grain size this includes the high dust period that correlates with the heinrich 2 period of major iceberg discharge into the north atlantic variable wind strengths must therefore be invoked to account for these abrupt and significant changes in dust flux and grain size

development of depositional systems in the southeastern yellow sea during the postglacial transgression this study focuses on the development of depositional systems in the southeastern yellow sea during the postglacial transgression based on the analysis of closely spaced high resolution seismic profiles chirp and piston cores transgressive deposits comprise the paralic component of estuarine channel fills seaward prograding wedge and along shore prograding mound and the marine component of sand veneer mud blanket and offshore ridge these transgressive deposits were developed through three distinctive stages in terms of possible sea level position during the early stage tidal sand ridges and sand veneer formed south of jeju island resulting from shoreface erosion associated with a relatively slow transgression the following transgression in the middle stage inundated subaerially formed interfluves along the central part of the sea and affected development of estuarine environments with increasing tidal regime in the eastern part of the sea combined with the strong tidal reworking insufficient sand supply enhanced the formation of erosional ridges short period increase in fluvial discharge affected the deposition of coastal wedge in the western part fine grained sediments from either fluvial discharge or tidal reworking were dispersed seaward to form mud blanket the late stage was characterized by the deposition of veneered sands off the jiangsu coast which was due to relatively slow rise in sea level further offshore along shore prograding mound was constructed by huanghe derived sediment influx and subsequently eroded and redeposited by wave and tide activities thus detached from the proximal source the depositional processes and variability of the transgressive deposits in the southeastern yellow sea were largely controlled by changes in rate of sea level rise during the transgression most likely related to the global flooding events triggered by melt water pulses the changes in shoreline configuration and oceanographic regime have also influenced the distribution and morphology of the transgressive deposits a short period increase in riverine discharge caused the temporal sediment progradation off the jiangsu coast

a unique yellow river derived distal subaqueous delta in the yellow sea abstract newly acquired high resolution chirp sonar profiles reveal a unique yellow river derived alongshore distributed bidirectional landward and seaward across shelf transported omega shaped distal subaqueous deltaic lobe deposited around the eastern tip of the shandong peninsula in the yellow sea this clinoform deposit directly overlies the postglacial transgressive surface featured by convex up seafloor morphology up to 40 m thick locally radiocarbon 14 dates from the underlain pre holocene and transgressive sediments indicate this distal lobe has formed since the middle holocene highstand under a relatively stable sea level this along shelf distributed distal clinoform has been deposited mainly by the resuspended yellow river sediments carried down by the coastal current interacting with the local waves tides and upwelling collectively over the past 7000 years nearly 30 of the yellow river derived sediment has been re suspended and transported out of the bohai sea into the yellow sea overall the yellow river derived sediment could reach the 80 m water depth in the central south yellow sea about 700 km from the river mouth in contrast a very small fraction of the modern riverine sediment could escape the outer shelf or reach the okinawa trough

ree partitioning in riverine sediments around the yellow sea and its importance in shelf sediment provenance abstract we sought to identify the characteristics and their controlling factors of rare earth element ree fractionation patterns in two chemically partitioned labile and residual fractions of korean kr and chinese riverine cr sediments we also investigated their sediment origins in the yellow sea based on ree signatures the results showed that the upper continental crust ucc normalized ree fractionation patterns were remarkably different for labile and residual fractions even between kr and cr sediments notably kr sediments in both residual and labile fractions exhibited a striking enrichment of light rees lrees unlike cr sediments with no obvious fractionation such lree enrichment is relatively much stronger in the coarse grained sandy sediments the peculiar lree enrichment in both fractions of kr sediments was preferentially linked to grater felsic granitic compositions compared with cr sediments that were close to those of the ucc granodiorite with relatively more mafic minerals consisting of a mixture of various rock types application of these ree signatures to the provenance of yellow sea sediments provides an important clue to the cause underlying the lack of correlation between the mud budget and the river discharge in korean coastal regions as well as the ultimate fate of cr sediments the ree fractionation signals especially in residual fractions may shed light on the major existing phases affecting ree fractionation as well as the origin of sediments in the yellow sea

benthic foraminifer record of environmental changes in the yellow sea hwanghae during the last 15 000 years latest quaternary benthic foraminifer census counts in four cores from the yellow sea hwanghae were analyzed to decipher paleoenvironmental changes in this area since the last glacial maximum principal component analyses of samples from two cores in the central yellow sea indicate that the faunal variation in these cores re ects a sequence of distinct assemblages divided by sharp boundaries the shifts between individual biofacies correspond to changes in geochemical and lithological composition of the sediments and stable isotope ratios of foraminiferal shells and most can be correlated between cores the major faunal transition at a clear increase in bottom water salinity occurred between 8 47 and 6 63 ka and may indicate the establishment of modern type circulation in the yellow sea the inferred threshold size of the yellow sea basin for the establishment of such circulation seems to be rather close to its present day extent faunal shifts at 10 6 and 4 67 ka probably re ect changes in the intensity of river runo associated sediment and organic carbon delivery and bottom water oxygenation changes in benthic foraminifer faunas between 12 9 and 11 75 ka may signal the younger dryas climatic oscillation in the yellow sea the lateglacial marine transgression reached the central part of the yellow sea around 15 09 ka possibly an uplift of the central and eastern yellow sea area during the late holocene can explain the discrepancy between the timing of the transgression in the yellow sea and the global sea level curve 2000 published by elsevier science ltd all rights reserved

late quaternary evolution of the yellow east china sea tidal regime and its impacts on sediments dispersal and seafloor morphology the evolution of a tidal current field in the yellow sea and east china sea yecs in response to the sea level rise since the last glacial maximum lgm was investigated using a two dimensional tidal model with special attention to changes in the sedimentary environment of the continental shelf region it was found that tidal currents on the yecs shelf have generally been semi diurnal throughout the post glacial stages with f ratio index of diurnal inequality and s2 m2 ratio index of spring neap cycle remaining similar to present on the other hand the spatial distribution of the tidal bottom stress associated with m2 and m4 tidal currents changed greatly during the transgression as the sea level rose two core regions showing high bottom stress values migrated shoreward from cheju island toward the west coast of korea and along the retreat path of the paleo changjiang estuary distribution of extremely intense tidal bottom stress suggested that intense tidal reworking may have occurred at sea levels from 90 to 45 m in the southeast yellow sea and at 75 to 60 m off the paleo changjiang estuary the latter of which agreed with the timing of a large terrigenous organic c flux observed on the shelf slope distribution of slightly weaker bottom stress indicated that the sand ridges off the changjiang estuary and in the southeast yellow sea also might have formed at during those periods on the other hand when the sea level was between 45 and 15 m the tidal bottom stress was generally not strong enough to invoke significant reworking even though the stress intensity may be stronger than present correlation with modern and relict sedimentary features suggested that the tidal process have played a significant role on the reworking and deposition of sediments on the yecs shelf

clay mineral evolution in the central okinawa trough since 28 ka implications for sediment provenance and paleoenvironmental change abstract the okinawa trough is a natural laboratory for the study of later quaternary land ocean interaction and paleoenvironmental changes in this study we reconstruct the evolution of clay mineral assemblages in core dgks9604 retrieved from the central okinawa trough illite dominates the clay mineral compositions with average contents above 60 clay mineral evolution since 28 ka is closely related to changes in sediment provenance and paleoenvironment sea level rise and the strength of the kuroshio current control the dispersal and deposition of clays on the east china sea shelf and in the okinawa trough and thus determine the clay mineral compositions in the core sediments during the late last glacial period 28 0 14 0 ka the paleo changjiang river mouth was situated at the shelf edge close to the central okinawa trough and thus together with the outer shelf supplied large volumes of terrigenous sediments directly into the trough from 14 0 to 8 4 ka influence from the changjiang decreased while the mid outer shelf of the east china sea became the dominant sediment source to the central okinawa trough as sea level rose and the changjiang river mouth migrated west strong sediment reworking and erosion at the shelf edge at 15 13 ka significantly increased the lateral transport of fine grained shelf sediments to the central okinawa trough since ca 8 4 ka clays from taiwan have dominated the sediment flux to the site coinciding with the re entry of the kuroshio current into the trough the increasing influence of the changjiang sourced sediments since 1 5 ka was probably related to the weakening of the kuroshio current and or a higher river flux

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

provenance discrimination of siliciclastic sediments in the middle okinawa trough since 30 ka constraints from rare earth element compositions the late quaternary paleoceanography and paleoenvironment in the okinawa trough east china sea have been well reconstructed over the last decade while in contrast the provenance of terrigenous sediments that have accumulated there remains enigmatic in this study rare earth elements ree were used to investigate provenance changes in sediments from core dgks9604 taken from the middle okinawa trough discrimination plots based on ree fractionation parameters suggest that the cored sediments have variable provenances over the last 30 ka with the lower part ca 31 8 2 ka ultimately originating mostly from the changjiang yangtze river and the upper part 7 1 0 ka primarily from taiwan during the last glacial maximum and early deglacial period sea level was low and the main stream of the kuroshio current was deflected to the east of the ryukyu islands as a result the changjiang derived sediments might have dominated sedimentation of the middle okinawa trough however since about 7 ka the main stream of the kuroshio current strengthened in the area of the trough as sea level approximated the modern position this caused near bottom transport of fine grained sediments from the continental margin to the trough to become weak and instead taiwan derived terrigenous sediments dominated in the middle trough the changing provenances of terrigenous sediments into the middle okinawa trough are closely related to the evolution of oceanic circulation and sea level in the east china sea two tephra layers in the core have distinct ree compositions and correlate well with two volcanic eruptions at 7 6 and 25 8 ka in southern japan

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

paleoenvironmental changes during the last 8400 years in the southern yellow sea benthic foraminiferal and stable isotopic evidence we used benthic foraminiferal stable isotopic and grain size data from an ams c 14 dated core from the southern yellow sea to decipher holocene paleoenvironmental changes large amplitude changes in 6180 613 c and benthic foraminiferal assemblage composition indicate that major environmental changes occurred during the last 8400 years in the southern yellow sea we recognize 3 stages of environmental development 1 a low salinity estuarine environment stage at 8 4 6 9 cal kyr bp 2 a low salinity shallow sea environment stage at 6 9 to about 6 5 cal kyr bp and 3 a modem marine shelf environment stage after about 6 5 cal kyr bp the delta o 18 and delta c 13 values of ammonia aomoriensis asano combined with benthic foraminiferal assemblage data indicate a low bottom water salinity 15 parts per thousand during stage 1 suggesting a large amount of river runoff abrupt increases in delta o 18 and delta c 13 around 6 9 cal kyr bp were accompanied by a decrease in mean grain size and in abundance of benthic foraminifera possibly caused by a north ward shift of the yellow river s outlet during subsequent stage 2 the southern yellow sea was still characterized by a low salinity 28 parts per thousand even though sea level was high possibly due to the continued strong influence of river input and or limited exchange between the southern yellow sea and the open ocean at about 6 5 cal kyr bp an a aomoriensis dominated benthic foraminiferal assemblage was replaced by an ammonia ketienziensis ishizaki dominated assemblage indicating an increase in bottom water salinity grain size and stable isotope data suggest that the modem circulation was probably established at that time we speculate that the combined impacts of reduced river runoff enhanced east asia winter monsoon and increased influence of southern warm ocean currents caused this transition c 2007 elsevier b v all rights reserved

rare earth elements in fine grained sediments of major rivers from the high standing island of taiwan thirty eight sediment samples from 15 primary rivers on taiwan were retrieved to characterize the rare earth element ree signature of fluvial fine sediment sources compared to the three large rivers on the chinese mainland distinct differences were observed in the ree contents upper continental crust normalized patterns and fractionation factors of the sediment samples the average ree concentrations of the taiwanese river sediments are higher than those of the changjiang and huanghe but lower than the zhujiang light rare earth elements lrees are enriched relative to heavy rare earth elements hrees with ratios from 7 48 to 13 03 we found that the variations in la lu ucc gd lu ucc and la yb ucc gd yb ucc are good proxies for tracing the source sediments of taiwanese and chinese rivers due to their distinguishable values our analyses indicate that the ree compositions of taiwanese river sediments were primarily determined by the properties of the bedrock and the intensity of chemical weathering in the drainage areas the relatively high relief and heavy rainfall also have caused the rees in the fluvial sediments from taiwan to be transported to the estuaries down rivers from the mountains and in turn delivered nearly coincidently to the adjacent seas by currents and waves our studies suggest that the ree patterns of the river sediments from taiwan are distinguishable from those from the other sources of sediments transported into the adjacent seas and therefore are useful proxies for tracing the provenances and dispersal patterns of sediments as well as paleoenvironmental changes in the marginal seas

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

holocene paleoenvironmental changes in mud area southwest off cheju island east china sea evidence from benthic foraminiferal assemblages and stable isotope records abstract a sediment core retrieved from the mud area southwest off cheju island masci was analysed for benthic foraminifera grain size and stable isotopes and constrained by ams14c dating holocene paleoenvironmental changes in this broad shallow shelf were investigated with special focus on the evolution of the masci and its related ocean eddy system the results indicate that the east china sea shelf has undergone four major environmental evolution stages during the holocene prior to 9 8 cal kyr bp the benthic foraminiferal assemblages were dominated by low salinity shallow water species ammonia beccarii linnaeus elphidium advenum cushman and cribrononion subincertum asano reflecting a near coast deposit environment a noticeable transition of the benthic foraminifera from an a beccarii dominated to ammonia compressiuscula brady dominated assemblage taking place at approximately 9 8 cal kyr bp together with a contemporaneous increase in 18o and 13c provides evidence that a rapid rise in sea level occurred at this time in the east china shelf a gradual increase in 18o between 9 8 and 6 cal kyr bp indicates a steady strengthening influence of open ocean water on the area under study a sudden increase in the abundance of benthic foraminifera along with a decrease in the coarse fraction imply that an early eddy circulation system was established since almost 6 cal kyr bp in the masci this eddy circulation system was quite weak but gradually strengthened between 6 and 3 cal kyr bp possibly due to the intrusion of the yellow sea warm current yswc a more stable mud deposition period characterised by a high sedimentation rate of fine grained sediment and lighter value of 13c starting at approximately 3 cal kyr bp indicates that the masci was formed mainly during the late holocene we believe that the strengthened yswc since 3 cal kyr bp might increase the trap efficiency of the eddy system thereby accounting for the high sedimentation rate of mud deposits during this period

the rare earth element compositions of the changjiang yangtze and huanghe yellow river sediments thirty four samples from the changjiang and huanghe were analyzed to characterize their rare earth element ree compositions although ree concentrations in the changjiang sediments are higher than those of the huanghe sediments the former are less variable bulk samples and acid leachable fractions have convex ree patterns and middle ree enrichments relative to upper continental crust whereas flat patterns are present in the residual fractions source rock composition is the primary control on ree composition and weathering processes play a minor role grain size exerts some influence on ree composition as demonstrated by the higher ree contents of clay minerals in sediments from both rivers heavy minerals contribute about 10 20 of the total ree in the sediments apatite is rare in the river sediments and contributes less than 2 of the ree content but other heavy minerals such as sphene allanite and zircon are important reservoirs of residual ree fractions the fe mn oxides phase accounts for about 14 of bulk ree content in the changjiang sediments which could be one of the more important factors controlling ree fractionation in the leachable fraction 6 2002 elsevier science b v all rights reserved

hydrodynamic processes and their impacts on the mud deposit in the southern yellow sea abstract the sedimentation processes of mud deposits on the continental shelves of the yellow sea ys are investigated using a combined data analysis and hydrodynamic modeling approach in order to identify the dominant factors that contribute significantly to the formation of these deposits the data analysis makes extensive use of existing data especially recently collected deep core data while the hydrodynamic and sediment transport processes are studied using a 3d hydrodynamics model that incorporates the effects of tides waves and wind the average deposit rate of the central yellow sea mud cs is estimated to be 3 6 107 t a 1 based on high resolution chirp sonar profiles combined with core data available sedimentological mineralogical geochemical and fluid flow data all indicate that the fine sediments discharged from huanghe river and changjiang river as well as the resuspended sediments from the old huanghe delta are the main sources for the mud deposits in the southern yellow sea sys this study confirms that tidal current flow is indeed the main agent for transporting the fine sediment to the mud patch in the central sys but wave effect is also significant as it is responsible for maintaining suspension concentration and causing sediment resuspension the wave influence is particularly notable around the old huanghe delta in winter storms as during these storm periods current circulation mainly caused by the asian monsoon can transport a large quantity of fine sediments from the old huanghe delta to the central sys under the present hydrodynamic conditions the modeling results showed that approximately 16 1 33 108 t a 1 of the huanghe river derived sediment is transported out of bohai strait of which around 44 5 72 107 t a 1 will finally be transported to the south yellow sea the corresponding values without accounting for the wave effects are 9 8 and 2 6 respectively it is noted that the deposition rate in the cs mud area over the past 12 kyr is virtually constant despite the significant rise in sea level and associated changes in the tidal current fields and wave distributions in the yellow sea the reason for this is believed to be that the weaker currents and waves during a lower water period is compensated by the shorter distance the suspended sediments have to travel from the paleo huanghe river to the cs mud area thus maintaining a nearly constant deposition rate in the cs mud area

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

discrimination of sediment provenance in the yellow sea secondary grain size effect and ree proxy this study analyzed grain size and elemental concentrations al mg fe and rare earth elements rees in 91 surface sediments to elucidate sediment provenance in the yellow sea elemental concentrations were normalized by al concentration c element c al to minimize the sediment grain size effect gse however noticeable linear relationships between ai concentration or mean grain size and the ratio e g mg al or fe al appeared unexpectedly in pair diagrams the spatial distribution patterns of fe al and mg al ratios were also similar to the pattern of mean grain size this implies that the gse was not removed completely even after the normalization process thus great care must be taken when applying the ratios of c element c al as a proxy of sediment provenance to improve provenance discrimination of the sediments in the yellow sea the difference between the ree distribution patterns of chinese and korean river sediments expressed as delta delta ree la ree lu was calculated and the spatial distribution patterns of the delta values were mapped the delta values gradually increased from the western to the eastern part of the yellow sea except for low delta values in the southeastern part of the yellow sea this result indicates that the majority of chinese and korean river sediments are accumulating near to their respective coasts except for a deposit along the southwestern coast of korea in which a considerable amount of sediment from chinese rivers has been accumulating c 2016 elsevier ltd all rights reserved

discrimination of sediment provenance using rare earth elements in the ulleung basin east japan sea abstract in order to discriminate the origins of ulleung basin east japan sea sediments using rare earth elements rees sediments from 15 box cores and one piston core collected in the shelf slope and basin were analyzed for major elements al fe ca and mn and rees the major sedimentary components in this basin were presumed to be detrital materials from land even in the basin sediments based on al and organic contents carbon and opal post depositional recycling processes involving fe and mn were identified in the basin sediments thus the ce anomaly and the fractionation factors of light rees lrees and middle rees mrees relative to heavy rees hrees could not be used as provenance indicators in the deep basin sediments 2000 m of water depth based on a feasibility check using their covariation with fe and mn for the shelf slope and basin b sites near islands water depths of 1200 1800 m regions the eu anomaly lreen hreen and mreen hreen could be successfully used to discriminate possible provenances including nakdong river sediments nrs chinese river sediments crs ulleungdo volcanic rocks uvr and dokdo volcanic rocks dvr from the provenance indicators slope as well as the shelf sediments called the korea strait shelf mud kssm in the ulleung basin can be regarded as mixtures of nrs and crs with decreasing portions of nrs in the kssm with distance from the nakdong river basin b sediments were mixtures of uvr or dvr and crs these findings can be explained if sediments discharged from the nakdong river were transported and deposited kssm northward within the strong coastal front in normal periods and if sediment flumes from summer floods flowed out across the coastal front were carried with the tsushima warm current and then deposited in the slope area this study indicated that crs were very important detrital sediments and that ree compositions can be successfully used as a provenance indicator in even hemipelagic sediments close to land