concentrations of rare earth elements in topsoil from east china fifty topsoil samples collected from 12 different regions of east china have been analyzed for rare earth elements rees the average ree concentrations of the 50 topsoil samples are much higher than world average and are characterized by lree enrichment hree depletion eu depletion and ce enrichment however the ree concentration is not strongly affected by the climate of the sampling site it is controlled mainly by parent materials the plot of ce eu against eu sm is proved to be useful to distinguish different parent materials of topsoil each element in the 50 topsoil has a good correlation with its neighboring element seven of the 13 values are above 0 987

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

geochemical investigation of soils developed in different lithologies in bhutan eastern himalayas within a project studying soil genesis on the southern slopes of the eastern himalayas a comprehensive set of major trace and rare earth element ree contents has been compiled for the first time six saprolites and their associated pedons were sampled on metamorphic migmatitic and leucogranitic parent materials at altitudes ranging from 1520 m to 3770 m metamorphic soils are largely illitic with si decreasing and al and fe increasing with decreasing degree of metamorphism the subsoil of a tourmaline bearing leucogranite is characterised by equally high si but higher contents of k and lower fe mg and ti a migmatitic profile in southern bhutan is dominated by hornblende and is quite distinct from the other lithologies with lower contents of si and k but higher fe mg ca and mn chondrite normalised ree patterns compare with post archaean materials with steep light rare earth lree and flat heavy rare earth hree patterns in comparison to generalised upper crustal composition ucc the bhutanese lithologies show a pronounced eu anomaly whereas the patterns appear rather homogenised in topsoils the influence of the parent materials causes deviations from the general trend with increasing depth the occurrence of marine tethyan sediments is confirmed by a strong positive ce anomaly in the central bhutanese phobjikha valley in the leucogranitic profile ree depletion is attributed to the presence of monazite as corroborated by trace element behaviour because of the hornblende ree patterns of the migmatitic profile are flat and without a eu anomaly chemical indices of alteration cia of between 71 and 92 indicate advanced weathering even at high altitudes correlation analyses show that ree are associated with the silt and clay fraction 63 m at elevations above approximately 3500 m physical weathering causes passive ree enrichment however no differentiation of ree concentrations or patterns within the profile is observed below 3500 m increased chemical weathering and leaching appears to be sufficient to release and translocate rees in this process hree are preferentially translocated whereas ce is more refractory than the other lanthanides this case study confirms that soil weathering and ree behaviour are closely related

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

petrology and geochemistry of syn to post collisional metaluminous a type granites a major and trace element and nd sr pb o isotope study from the proterozoic damara belt namibia abstract leucocratic a type granites of the proterozoic damara orogen namibia are a distinctive groups of rocks based on their mineralogical chemical and isotopic characteristics a type granites can be distinguished from the leucocratic s type granites on the basis of fe rich amphibole and biotite and higher abundances of zr nb y and lree but lower values of 87 sr 86 sr 500 ma and 18 o in the a type granites in comparison with a type granites described in the literature the damaran a type granites are enriched in cao al2o3 mgo feo ba sr and eu but depleted in ga and zn low k rb rb sr rb ba and sr ba ratios indicate that these melts are not fractionation products of calc alkaline source rocks and therefore these chemical criteria are interpreted as a feature of the source rocks i e undepleted metatonalites the a type granites have high calculated zircon and monazite saturation temperatures mostly in excess of 800 c and it is concluded that these granites represent high temperature partial melts the relationship between major and trace element data and isotopic composition demonstrates that the a type granites originate from several sources and have undergone different processes the lack of evidence for shallow crustal contamination e g lack of country rock xenoliths the low viscosities of the melts as inferred from their high calculated temperature and their high nd concentrations relative to the country rocks suggest that the isotopic characteristics were acquired from an enriched mantle initial sr isotopic compositions vary over a narrow range 0 70486 0 70928 but the initial nd isotopic compositions vary considerably with initial end values between 0 03 and 6 35 this wide range in the nd isotope values is probably the result of interaction of mantle derived magmas with crustal rocks a type granites at baukwab have negatively correlated initial end values and 207 pb 204 pb and 206 pb 204 pb ratios indicating interaction of mantle derived magmas low initial end low 207 pb 204 pb and 206 pb 204 pb with continental crust high initial end high 207 pb 204 pb and 206 pb 204 pb a type granites from albrechtstal and oetmoed have positively correlated pb isotope ratios and show also positive correlations between nd isotopes and pb isotopes suggesting interaction of at least two different source materials the relationship between nd isotopes and nd concentrations precludes simple assimilation instead mixing of different sources seems to be more realistic for the a type granites from oetmoed oxygen isotopes are negatively correlated with sr isotopes indicating that the crustal end member has high 18 o values and rather low initial 87 sr 86 sr ratios whereas a hypothetical mantle component has lower 18 o values but higher initial 87 sr 86 sr ratios the chemical and isotope data suggest that the damaran a type granites were generated by a variety of processes including partial melting of mantle derived tonalitic sources limited crystal fractionation and interaction of these magmas with crustal material these data indicate that the damaran a type suites mark episodes of continental growth during which mantle material although limited in extent is added to the crust

sedimentary records of large holocene floods from the middle reaches of the yellow river china slackwater deposits have been used as evidence for the magnitude and frequency of palaeofloods which occurred prior to gauged and historical data sets e g holocene extreme flood reconstruction in north america and australia the slackwater deposits from xiaolangdi reach of the yellow river have been identified and related to floods according to both eyewitness accounts and the analysis of sediments the technique successfully delineated the peak flood level and estimated a discharge of the 1994 ad flood in the yellow river the discrepancy of the estimated discharge was less than 5 compared with the instrumental records when we applied the technique to palaeoflood analysis the highest slackwater deposits and flood indicators from the tributary mouths the low river terraces and the loess platforms and loess alcoves together with radiocarbon dating provided evidence of at least six floods with peak discharges greater than 27 300 m3 s 1 at xiaolangdi section over the last 8500 yr the largest flood in ca 7362 yr b p had an estimated discharge of 42 900 m3 s 1 which is the maximum flood event known in the yellow river the results provide a basis for a determining the floods which were comparable to the most cataclysmic flood during the last 2360 yr in 1843 ad and b estimating the flood magnitude for a 10 000 yr time scale relevant for building xiaolangdi dam one of the largest dams under construction in the world the reconstruction of palaeofloods also provides evidence for a phase between ca 6000 8000 yr b p which was much wetter than today as a result of increased summer precipitation and enhanced pacific monsoon conditions in eastern china

rare earth element and mineralogic changes in holocene soil and stream sediment a case study in the wet mountains colorado u s a size fractions of soil and stream sediment developed on plutonic metamorphic or mixed plutonic metamorphic sources in the wet mountains colorado have been analyzed for ree rare earth elements and mineralogy the clay sized fractions 0 5 m and 0 5 2 m or 2 m have ree contents that are similar to more enriched than the source eu sm ratios that are similar to the source and la lu ratios that are higher than their corresponding source the 0 5 m fractions have lower ree contents than the corresponding 0 5 2 m fraction in every stream sediment for example unweathered san isabel batholith near the sampled stream sediment contains ree 511 712 ppm and eusmratio 0 17 0 19 and lalu cn 9 8 10 3 the corresponding 0 5 and 0 5 2 m fractions of sediment formed from san isabel batholith are enriched in the ree ree 1135 and 2225 ppm respec are slightly lower in eu sm ratios 0 16 and 0 14 respec and are higher in la lu ratios 12 2 and 16 3 respec than the unweathered rocks the silts have lree light ree contents and eu sm ratios very similar to the source due to similar mineralogy but silts have hree heavy ree contents higher than the source due to high zircon for example silt sized fractions in stream sediment draining the san isabel batholith contain ree 808 ppm eusmratio 0 18 and lalu cn 7 4 in contrast the sands contain lower ree contents similar to higher eu sm ratios and lower la lu ratios than the corresponding source due to depletion in heavy minerals concentrated in the ree and containing lower eu sm ratios relative to quartz and feldspar depleted in the ree and containing higher eu sm ratios for example the sand fraction from stream sediment from the san isabel batholith has ree 206 ppm eusmratio 0 17 and lalu cn 5 6 small variations of accessory minerals concentrated in the ree like allanite or sphene may cause drastic variation in ree content in the sand fraction clays and silts derived only from the plutonic rocks have higher ree and similar to lower eu sm ratios than corresponding fractions derived only from migmatites e g ree of silt fractions from migmatites 224 ppm and from plutons 375 808 ppm eu sm ratios from migmatites 0 17 and from plutons 0 11 0 18 the ree content and the eu sm ratio of clays and silts derived from migmatites are much more similar to the average of mcps mid continent platform sediment than corresponding fractions derived from the plutons mcps has ree 192 ppm eusm 0 19 lalu 8 0 the eusm ratio of sands derived from plutons and migmatite are lower to mostly higher than the mcps the ree content of sands from plutons are not necessarily higher than the mcps due to variation in heavy minerals like allanite or sphene concentrated in the ree sediments derived from mixed sources have ree contents in fine fractions that may not necessarily reflect the ree content of the nearest source for example 0 5 2 m and silt fractions developed on the san isabel batholith with a migmatite upstream have the high ree content of the batholith ree in 0 5 2 m fraction 1100 ppm silt 573 ppm while the corresponding 0 5 m fraction has the very low ree content of the migmatites ree 110 ppm these results suggest fine grained material near the source may sample a much larger area than coarser material near the source thus analysis of fine grained sediment associated with coarse grained material near the source may give a much different impression of the source than would determination of the source using classic petrographic examination of the sand or gravels

high resolution reconstruction of sedimentary organic matter variability during the holocene in the mud area of the yellow sea using multiple organic geochemical proxies abstract as a result of terrestrial input and local circulation an area containing continuously deposited mud with abundant organic matter om has formed in the yellow sea ys off the shandong peninsula china during the holocene the understanding of temporal variations in sedimentary organic matter som from this mud area helps to evaluate the influences of yellow river discharge and marine productivity on the burial of organic matter in the ys in this study multiple organic geochemical proxies were used to reconstruct holocene changes in som in a sediment core a02c recovered from the mud area of the ys higher total organic carbon toc and biomarker contents during the early holocene relative to the middle and late holocene are attributed to sea level fluctuations the 13c values of toc 13ctoc range from 21 8 to 23 5 becoming more positive from the bottom to the top of the core tmbr terrestrial and marine biomarker ratio values vary from 0 43 to 0 80 with a decreasing trend during the holocene the decrease in tom contribution was related to elevated sea level shifting of the mouth of the yellow river and weakening of the east asian winter monsoon eawm during the holocene a mixing model with three end members based on 13ctoc and tmbr reveals that the contribution of soil om average 42 is higher than that of plant om average 17 simultaneous decreases in the plant om fraction and the marine om fraction occurred around 10 3 8 2 5 9 4 2 and 2 8 kyr bp corresponding to drift ice events in the north atlantic spectral analyses also reveal that all three om fractions exhibit 1015 year periodicity and that the soil and plant om fractions display 1420 year periodicity consistent with the 1000 year cycle of solar activity and the 1500 year cycle of the kuroshio current kc respectively

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

rare earth elements and clay minerals of soils of the floodplains of three major rivers in bangladesh the rare earth elements ree particle size distribution and mineralogical composition in the 2 m clay fraction from the soils on the floodplains developed by the three major rivers of the brahmaputra meghna and ganges in bangladesh were analyzed ree as the chondrite normalized curve or the plot of ce eu against eu sm did not differentiate the soils according to the river floodplains whereas the clay mineralogy did particle size distribution varied between the soils and the soil horizons

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

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

geochronology and petrogenesis of pan african syn tectonic s type and post tectonic a type granite namibia products of melting of crustal sources fractional crystallization and wall rock entrainment abstract the oetmoed granite migmatite complex ogmc central damara orogen namibia consists mainly of 526 to 516 ma garnet and cordierite bearing granite and subordinate 488 to 494 ma hornblende and titanite bearing granite in the form of planar sheets and dykes additionally a slightly elongated granite body occurs in the center of the complex the garnet and cordierite bearing granite has major and trace element characteristics of s type granite but the hornblende and titanite bearing granite has higher hfse and ree contents similar to a type granite whereas the garnet and cordierite bearing granite contains numerous restitic xenoliths the hornblende and titanite bearing granite is xenolith free the country rocks are cordierite sillimanite k feldspar garnet bearing metasedimentary rocks and migmatite cordierite and garnet rich xenoliths in the s type granite do not represent primary restite their depleted chemical composition is best explained by varying and large degrees of partial melting of incorporated country rocks most chemical variations among the garnet and cordierite bearing granite can be explained by processes linked with fractional crystallization of plagioclase biotite and accessory phases mostly monazite and zircon major and trace element data and high 18 o values suggest that the least evolved members of the garnet and cordierite bearing granite were derived from metapelitic rocks at ca 800 c as inferred from monazite and apatite dissolution thermometry higher cao and na2o but lower sio2 contents and lower rb sr ratios as well as lower 18 o values of the hornblende and titanite bearing granite suggest that they are more likely generated by partial melting of non pelitic sources metagranitoids at temperatures in excess of 900 c decreasing tio2 na2o feotot mgo cao total ree content but increasing al2o3 and k2o indicate fractionation of mainly hornblende and titanite in the case of the hornblende and titanite bearing granite the differing compositions of the garnet and cordierite bearing granite and the hornblende and titanite bearing granite are attributed to different source rocks metapelite instead of metagranitoid and different temperatures during melting as inferred from accessory phase dissolution thermometry furthermore significant entrainment of country rock in some samples played a major role during petrogenesis of the garnet and cordierite bearing granite but was not important during the evolution of the hornblende and titanite bearing granite intrusion of such hot felsic magmas close to the inferred peak of metamorphism has probably caused in part the high temperature metamorphism and anatexis of the country rocks at relatively low pressures

partitioning of transgressive deposits in the southeastern yellow sea a sequence stratigraphic interpretation abstract the last glacio eustatic sea level fluctuation in the southeastern part of the yellow sea formed a number of unconformity bounded sedimentary sequences these sequences comprise 1 regressive to transgressive incision fills unit c 2 transgressive sand ridges and swales unit b and 3 transgressive to highstand muds lower mud unit a2 upper mud unit a1 the sequence boundary between unit c and the lower unit comprises erosional surface which can be traced for the entire study area the even and sharp boundary between the incision fills unit c and the sand ridges unit b represents a transgressive surface of erosion the depositional boundary between the lower mud unit a2 and the upper mud unit a1 suggests a change in oceanographic conditions the boundary is confined landward and correlated offshore with the top of units b and c that is exposed on the seafloor these transgressive deposits show partitioning controlled by currents tides and sediment supply as well as physiography of the seafloor

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

mobilization and redistribution of rees and thorium in a syenitic lateritic profile a mass balance study abstract ree th geochemistry and mineralogy have been studied in a lateritic profile derived from a syenite at akongo in sw cameroon ree and th mass balance calculations for the host rock minerals show that at least 70 of the lree s and 50 of the hrees are contained in allanite apatite titanite and epidote and at least 50 of the th is controlled by the same accessory minerals which represent about 2 wt of the unaltered syenite these accessory phases are destroyed during the first stages of weathering causing most of the rees and th to be rapidly released into the soil comparison of the variation in the zr ti and th content as a function of the apparent density of the different zones of the saprolite shows that th is the least mobile element the presence of secondary thorianite tho2 the etched surface on zircon grains and the presence of ti in secondary cerianite support this geochemical interpretation the concentration of thorium was therefore chosen as invariant relative to the concentration of the other elements especially the rees in mass balance calculations most of the rees are leached in the iron rich upper horizons loose nodular horizon iron crust and top of mottled clay horizon where the groundwater table moves saprolite and bottom of the mottled clay horizon the rees are fractionated and redistributed there is a juxtaposition of leached and accumulation zones with precipitation of lree aluminous hydrated phosphates this study supports the existence of two different cycles for the redistribution of elements in the soil 1 1 as dissolved ions in the saprolite horizon and 2 2 as individual particles in the upper part of the profile

rare earth element behavior in soils and salt pan sediments of a semi arid granitic terrain in the western cape south africa the rare earth element ree contents of soils and pan sediments of the darling hills granitic terrain of southwestern south africa were determined to study the behavior of ree during weathering in a semi arid mediterranean climate the p rich stype bedrock granite has a middle ree mree enrichment relative to post archean australian sedimentary rocks paas that primarily reflects the ree content of feldspar and accessory apatite initial chemical weathering of the granite results in the loss of ree particularly ce eu and the heavy ree hree the enrichment of ree in soils relative to bedrock granite corresponds to clay mineral and amorphous fe oxide content in the case of the light ree lree and precipitation of pedogenic calcite in the case of the hree quartz sand dilutes the ree content and concentration of k feldspar produces positive eu anomalies cerium is rapidly precipitated during weathering and retained in clayey upper soil horizons as insoluble ceo2 most pan sediments have a bowl shaped ree pattern that is derived from the accumulation of eroded catchment soils modified by precipitation of evaporative carbonates ree enrichment particularly lree and the large negative ce anomaly of oxidized basal pan sediment relative to the bedrock granite suggest that ree entering the pan by groundwater flow are sorbed onto amorphous fe oxides in contrast goethite rich nodules from the pan have a low ree content and show hree enrichment relative to the granite precipitation of pedogenic calcite and evaporative pan carbonates greatly increases the retention of the hree in these semi arid soils diagenetic pan dolomite has a ree pattern similar to pedogenic and evaporative calcite but with a significantly lower ree content the ree patterns indicate that although most abundant in the bedrock granite the mree are least retained by soils during weathering the lree are generally retained by clayey and amorphous fe oxide rich soils and sediments whereas hree are retained by precipitation of soil and pan carbonates d 2003 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

paleoenvironmental changes associated with the holocene marine transgression yellow sea hwanghae benthic foraminiferal and stable isotopic data from two radiocarbon dated cores from the yellow sea record paleoenvironmental changes largely associated with the holocene marine transgression the holocene marine transgression began significantly earlier 12 9 ka in the central part of the yellow sea as recorded in 278 cm long core cc 02 water depth 77 5 m compared with 7 9 ka in a tidal flat on west coast of korea as recorded in 350 cm long vibra core dh4 1 water depth 1 8 m the benthic foraminiferal assemblages in the lower part of cc 02 and the entire marine sequence of dh4 1 are dominated by assemblages characteristic of shallow 50 m waters ammonia ketienziensis ishizaki astrononion italicum cushman and edwards and hanzawaia nipponica asano after 7 5 ka in the central yellow sea much higher 18o 1 6 to 1 8 and 13c 0 1 to 0 7 values of a ketienziensis reflect a change to more open ocean higher salinity environments with deeper waters dominated by the hwanghae cold water as in the present day

effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments with implications for provenance studies the bulk chemical compositions mineralogy and mineral proportions of sands and muds of the mallacoota basin in southeastern australia reflect the composition of weathering profiles mantling source rocks rather than bedrock muds contain abundant clay minerals that are virtually absent from the source rocks but abundant in the weathering profiles sands are strongly enriched in quartz relative to source rocks even in the headwaters of the fluvial system demonstrating that feldspar destruction occurs by in situ chemical weathering within profiles and before detritus enters the fluvial system k feldspar is proportionally more abundant in fluvial sands than in source rocks because plagioclase is more rapidly destroyed than either quartz or k feldspar in weathering profiles subsequent erosion and sorting produce sands enriched in quartz with high k feldspar plagioclase ratios relative to source rocks the composition of plagioclase incorporated into the fluvial sands is also controlled by chemical weat

major and trace elements of river borne material the congo basin the congo river basin is the second largest drainage basin in the world after the amazon the materials carried by its main rivers provide the opportunity to study the products of denudation of a large fraction of the upper continental crust of the african continent this paper presents the chemical composition of the different phases carried in the congo rivers and is followed by a companion paper devoted to the modelling of major and trace elements the congo river between bangui and brazzaville as well as its main tributaries including a few organic rich rivers also called black rivers were sampled during the 1989 high water stage the three main phases suspended load dissolved load and bedload were analysed for twenty five major and trace elements concentrations normalized to the upper continental crust show that in each river suspended sediments and dissolved load are chemical complements for the most soluble elements ca na sr k ba rb and u while these elements are enriched in the dissolved loads they are considerably depleted in the corresponding suspended sediments this is consistent with their high mobility during weathering another type of complementarity is observed for zr and hf between suspended sediments and bedload related to the differential velocity of suspended sediments and zircons which are concentrated in bedloads compared to other rivers absolute dissolved concentrations of ca na sr k ba rb and u are remarkably low surprisingly high dissolved concentrations are found in the congo waters for other trace elements e g rees especially in the black rivers on a world scale these concentrations are among the highest measured in rivers and are shown to be ph dependent for a number of dissolved trace elements the dissolved loads are systematically normalized to the suspended loads for each river in order to remove the variations of the element abundances owing to source rock variations normalized diagrams for rees are presented and extended to the other elements they strongly support the argument that the apparent higher solubility of trace elements in the congo waters is due to the presence in the dissolved load of a colloidal phase as a result of 0 2 m filtration an important result is that these colloids are strongly depleted in fe and al with respect to the other elements finally the comparison of the dissolved suspended and sandy transport fluxes of each element in the congo basin rivers shows that although the proportions of for example the rees in the dissolved loads of the majority of the congo basin rivers is close to 10 of the total transport flux up to 80 of the rees are transported by the so called dissolved load in the black rivers

ree geochemistry of recent clastic sediments from the kaveri floodplains southern india implication to source area weathering and sedimentary processes abstract the kaveri river drains through archean gneissic and charnockitic terranes in south india the rare earth element ree chemistry of the floodplain sediments along with their major and trace element composition in different size fractions are discussed we observe a strong coherence between ree and tio2 contents in the sediments which is suggestive of strong control by titanite or its weathered products on the ree chemistry ree concentrations also show a general increase with decreasing size of bulk sediments different size fractions and of light and heavy mineral fractions this suggests the presence of ree in the fe oxy hydroxide surface coatings on clastic grains formed by the weathering of hornblende and titanite in the granodioritic to dioritic protoliths we also interpret the data as showing that ree patterns of clastic sediments notably eu anomaly are affected by the degree of source rock weathering as well as by the fluvial processes of sorting and mineral differentiation therefore for provenance study sediments having all granulometric grades such as the floodplain sediments are preferable because they most closely represent the source particularly when the source region suffered little chemical weathering in the present case the sediments were derived from the high standing hills of archean charnockites because of their recent uplift and physical denudation

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

dune activity as a record of late quaternary aridity in the northern kalahari new evidence from northern namibia interpreted in the context of regional arid and humid chronologies abstract sediments from presently vegetated linear dune ridges in the caprivi strip of northern namibia are optically dated to assess the timing of dune building phases and aridity in the late quaternary the dunes have been constructed from sediments likely to have been initially transported into the area by fluvial processes dune sediments do not preserve obvious evidence of hiatuses in deposition in the dated period 48 121 ka but continuous deposition and therefore continuous aridity is considered unlikely given differences in dated phases compared with chronologies from western zimbabwe to the southeast and western zambia to the north that include ages derived from the same equivalent sampling depths laboratory experiments provide evidence that dune sediments have not been bioturbated since deposition such that sample palaeodoses determined from different sampling depths are a true reflection of the duration of sediment burial independent chronologies from cave sediments provide evidence that humid episodes have occurred in the region within the dated range of dune construction it is concluded that dune construction in the late quaternary has been punctuated that the preserved record reflects the attributes of the aeolian processes that affect linear dune development and that the late quaternary record of dune building in the middle and northern kalahari was spatially complex

cerium anomalies in lateritic profiles the ree geochemistry and mineralogy have been studied in four lateritic profiles one derived from a syenite akongo sw cameroon the others being developed on a gneissic basement and located along a soil toposequence goyoum e cameroon there is a fractionation between lree and hree in the lateritic samples during weathering the weathered residual products being enriched in lree from la to eu and depleted in hree from gd to lu sampled waters are enriched in hree in relation to the syenite host rock a positive ce anomaly has been found systematically at the top of the saprolite beneath a zone of iron oxide accumulation in the laterite up to 2000 ppm ce may be present in the akongo profile cerianite ceo2 is present as very fine coatings in non ferruginous clayey domains primary ree bearing accessory minerals are weathered at the bottom of the profile specifically allanite and apatite are transformed into florencite and rhabdophane but these phases have no ce anomaly all the data are interpreted as the result of the following processes 1 1 ree leaching in a reducing environment 2 2 oxidation of ce3 to ce4 in an oxidizing environment 3 3 deposition of cerium as cerianite whereas the other ree remain in solution

major and trace elements of stream sediments from the lowermost amazon river geochemical results from river bottom sediments taken from the lowermost amazon river are presented bedload sediments were analyzed for 10 major and 38 minor elements mud bulk sediments exhibit a tendency to a slight enrichment in cr mn rb sr zr cs ba and hf pointing to the importance of these elements in the silt fraction generally cu zn rb cs ba and sn are clearly associated with clay minerals while y zr hf th and u are associated with heavy minerals the location of this area in an intensive chemical weathering environment results in the strong modification of sediment composition chemical weathering processes strongly modify original sediment composition and can be recognized apart from provenance processes on the basis of their geochemical signature discriminant analysis makes the detection of less marked differences in sediment characteristics possible thus improving the accuracy of distinctions between groups the amazon mouth and xingu mouth xm are discriminated principally by the textural maturity of their sediments the jari mouth jm shows highest co and fe2o3 contents despite similarities between the amazon north branch anb and amazon south branch asb the anb can be differentiated on the basis of its higher sr p2o5 and na2o contents the asb on the basis of its higher zn mno and cao contents and the estreitos de breves est based on its higher abundance of ni and cu higher contents in p2o5 fe and mn are related to laterite covers

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

pleistocene forced regressions and tidal sand ridges in the east china sea abstract tidal sand ridges are common features on modern shelves but only few examples of such preserved sand bodies are described in pleistocene deposits in the stratigraphic record some sand bodies encased in shales previously interpreted as sand ridges have been reinterpreted as shoreface deposits more than 5000 km of high resolution seismic data from the east china sea correlated to geotechnical boreholes and shallow cores demonstrate the potential of sand ridge preservation and allow reconstruction of the depositional history of pleistocene fourth order 100 kyr depositional sequences a high subsidence rate of about 300 m myr allows the preservation of three elementary sedimentary facies constitutive of a motif which was repeated during glacio eustatic cycles they consist of 1 regressive marine prodeltaic prograding wedges 2 estuarine and continental deltaic facies and 3 transgressive sand ridges similar in shape and orientation to modern sand ridges major discontinuities traceable over the entire outer continental shelf along distances of hundreds of kilometers are transgressive and regressive surfaces of marine erosion whereas sequence boundaries formed by fluvial erosion are difficult to identify on this low gradient shelf because of the asymmetry of the pleistocene glacio eustatic cycles most of the preserved sedimentary record with the exception of sand ridges corresponds to forced regressive deposits deposits that formed during a seaward shift of the shoreline due to relative sea level lowering

holocene environmental change in the otjiwarongo thornbush savanna northern namibia evidence from soils and sediments in the otjiwarongo region northern namibia vertisol kastanozem calcisol soil associations occur as patches of several hundred hectares in extent they have formed in fine grained mid holocene sediments which accumulated on both sides of the subcontinental watershed between the ugab river draining into the south atlantic and the omatako omuramba draining into the kalahari basin kastanozem formation cannot be explained by the environments that exist at present the humification suggests open savanna environments in the past and does not accord with the shrublands and thornbush savanna at present using ams 14c and osl data it is possible to distinguish two periods of soil degradation during the recent past initially most of the kastanozems and vertisols were buried by slope wash sediments to a depth of several decimetres this process started in the mid 19th century at the latest in a second phase the soils were affected by rill and gully erosion indicating increased runoff this occurred during the last decades of the 19th and the first decades of the 20th century probably as a result of intensified cattle farming in contrast to other parts of namibia the prominent river channels of the otjiwarongo region most of them up to 20 m wide and 3 4 m deep are a result of recent erosion degradation of vegetation and soils and river channel formation seem to be the main causes of farmland aridification

trace element and nd isotopes in shales as indexes of provenance and crustal growth the early paleozoic from the brabant massif belgium abstract the cambrian ordovician shales from the brabant massif show an increase in th 6 7 17 7 ppm and la 16 6 71 2 ppm contents in lree hree ratio la n yb n 3 8 13 9 and in tnd values 3 3 to 8 9 with younger age of the sedimentary rocks this evolution is related to a change in the dominant source rock from basic metavolcanics in the early cambrian to granite gneiss schist rocks in the early ordovician the ta content appears to be controlled by the provenance area as well the modification in the origin of detritus is not reflected in the abundance of sc cr and v but it is slightly recorded in the co and ni concentrations tnd responds more sensitively to source changes than sm nd ratios and crustal residence ages and it is confirmed to be a more powerful parameter to detect new addition of mantle material to the crust the evolution of tnd with stratigraphic age tnd vs t for the brabant shales parallels the trends for coeval clastic rocks from brittany france and southern britain michard et al 1985 davies et al 1985 and is considered to be a characteristic of the armorica plate the tnd vs t path of sediments deriving from crystalline rocks first cycle sediments turns out to be a convenient function to delineate the boundaries of fossil lithospheric plates on the contrary such first cycle sediments are not very useful to investigate the long term continental growth because their tnd vs t path represents a second order pattern episodic evolution that disturbs the first order trend of the sedimentary nd isotope record secular evolution

short lived u and th isotope distribution in a tropical laterite derived from granite pitinga river basin amazonia brazil application to assessment of weathering rate we have analyzed samples of a 15 m thick profile weathered from the madeira granite located in the pitinga basin river north of manaus in the state of amazonia brazil this profile consists essentially of a yellow red saprolite covered by a soil u and th concentrations are particularly high in the granite 20 and 80 g g respectively normalized element to th concentrations indicate that th is most resistant to chemical weathering except to some extent in the top soil higher concentrations in the saprolite compared to the granite comprise a relative enrichment resulting from a loss of mass the saprolites are initially generated by a descending weathering front which alters the granite to a yellow red saprolite a second front close to the top turns the saprolite into a soil weathering has led to leaching of u the 234u 238u and 230th 238u isotopic ratios are in radioactive disequilibrium numerous nodules are present and apparently started to form at the base of the saprolite these nodules achieve more developed form during their relative ascent until they are reached by the descending top front where they undergo dissolution the th and pb are concentrated in the nodules close to the top front the u being more mobile is strongly leached by the first front and most of the remainder freed by the second engages in a descending flux which supplies the underlying saprolite using the data an attempt is made to model the isotopic distribution in the profile we conclude that the first front has descended at a rate of 5 cm 1000 yt and that the time needed to create the saprolite must have been around 300 000 yr

sources of stream sediments in the granulite terrain of the walawe ganga basin sri lanka indicated by rare earth element geochemistry abstract thirty eight samples of stream sediments draining high grade metamorphic rocks in the walawe ganga river basin sri lanka were analysed for their ree contents together with samples of metamorphic suites from the source region the metamorphic rocks are enriched in light ree lree compared to heavy ree hree and are characterised by high la lu ratios and negative eu anomalies the chondrite normalised patterns for these granulite grade rocks are similar to that of the average post archaean upper crust but they are slightly enriched with la and ce the ree contents of the n sm n and lower la n lu n ratios relative to other fractions the lower la n lu n ratio is related to the depletion of heavy minerals in the

rare earth element and nd isotopic variations in regionally extensive dolomites from the burlington keokuk formation mississippian implications for ree mobility during carbonate diagenesis abstract marine carbonates of the burlington keokuk fm miss of the midcontinent region have been subject to two major episodes of regionally extensive 100 000 km2 dolomitization previous studies of the cathodoluminescent petrography sr c and o isotopic compositions and sr fe mn and ca concentrations of burlington keokuk dolostones outline a diagenetic history in which lime mud was pervasively dolomitized by a seawater dominated fluid at many localities this early dolomite generation dolomite i was recrystallized by nonmarine diagenetic fluids at shallow burial depths to produce dolomite ii dolomites i and ii have similar rare earth element ree patterns and abundances and a narrow range of initial 143nd 144nd isotope ratios of 0 511906 0 000025 1 this consistency in the nd isotope ratios and ree patterns along with the presence of anomalously low abundances of cerium in the dolomites cherts glauconite pellets fish apatite and crinoids suggests that 1 seawater derived ree dominated the system and 2 the extensive water rock interaction that produced profound textural and compositional changes during the formation of dolomite ii did not significantly alter the ree patterns or nd isotopic signatures of the dolomites the results of quantitative modeling of isotopic and trace lement exchange during water rock interaction in carbonate systems indicate that extremely large water rock ratios are required to alter the ree signatures of diagenetic carbonates such large water rock ratios can reflect either 1 large extents of fluid flow during carbonate recrystallization or 2 minimal interaction between diagenetic fluids and host rocks during carbonate cement crystallization late vug filling calcite and dolomite have low sm nd and high ce nd n ratios relative to the dolostones such distinct ree signatures probably reflect limited interaction between late diagenetic fluids and burlington keokuk host rocks penecontemporaneous clastic sediments have similar initial 143nd 144nd isotope ratios 0 511857 0 511877 and lower sm nd ratios compared to the dolomites suggesting 1 a common crustal source of ree for the clastics and carbonates and 2 ree fractionation during the formation of carbonate apatite glauconite and other authigenic phases in the marine environment

dust and loessic alluvial deposits in northwestern namibia damaraland kaokoveld sedimentology and palaeoclimatic evidence based on luminescence data abstract in northwestern namibia silty deposits are widespread the silts consist of two major components locally produced weathering detritus and allochthonous dust blown in from the western kalahari to the eastern margin of the namib desert sedimentological analysis and luminescence age estimations allow identification of distinct sedimentological and geomorphological processes associated with two different climatic periods between about 30 and 8 ka loessic alluvial deposits several metres in thickness accumulated in valleys and basins the deposition was generated by weak slope wash and or endoreic drainage of the ephemeral rivers the dust input and the accumulation of silt in the valleys indicate semi arid climatic conditions with weak summer rains and long dry seasons since about 9 8 ka silt terraces caused by fluvial incision and erosion have been formed these indicate more humid conditions than had occurred before the change from a dry to a moister semi arid climate at about 9 8 ka is confirmed by proxy data from drill cores off the namibian coast and by dune studies in the south western kalahari

another look at rare earth elements in shales linear correlation and mass balance considerations indicate that clays are more important than zircon or other heavy minerals in hosting both light and heavy ree in cratonic shales considering the uniformity of the eu anomaly and ree distributions in cratonic shales it seems likely that detritus is thoroughly mixed during weathering and sediment transport and that the ree patterns in shales reflect the average ree pattern of the sources regardless of the ratio of clays to heavy minerals in the shales shales suspended river loads and near shore marine sediments all have broadly similar ree patterns and reported hree depletions in the latter two groups may reflect incomplete dissolution of heavy minerals during sample preparation ree distributions in shales and suspended river loads determined by inna are similar to those in average upper continent crust and ree distributions in shale averages nasc and paas seem to be reasonably representative of the average composition of post archean upper continental crust

rare earth and trace element geochemistry of termite mounds in central and northeastern namibia mechanisms for micro nutrient accumulation abstract rare earth element ree and trace element concentrations of ten termite mounds and adjacent topsoil from central and northeastern namibia were used to investigate the processes underlying the alteration of soil chemical and physical properties by termites macrotermes spp accumulation of micro nutrients in the mounds was of particular interest because of the ecological implications of the enhanced availability of these scarce elements the absolute concentrations of ree and trace elements including nine micro nutrients b fe mn ni cu zn se mo and cd were greater in termite mounds compared to topsoil suggesting a possible external supply of enriched materials or accumulation of in situ weathering products of the underlying bedrock similarities between the chondrite normalized ree patterns of the samples and those of the average upper continental crust ucc and post archaean average australian shale compositions indicated that the mounds and topsoil at each site originated from the same host bedrock coherent behavior between two incompatible elements th and la in both topsoil and mound samples suggested that the two sets of samples were exposed to two different weathering processes the relatively low zr sc ratios fine particle sizes and the persistence of positive eu anomalies of the mounds relative to ucc were interpreted as reflecting 1 a lack of grain sorting effects and 2 active transport of materials rich in primary clay minerals and trace elements from the deeper regolith to the surface by termites lower permeability of mound materials may also prevent leaching of primary minerals and trace elements titanium and zr enrichment in most mound samples 8 samples was attributed to the decomposition of biotite by macrotermes with the concomitant release of ti and zr into the mounds suggesting the termites ability to transform soil minerals and enhance chemical weathering this was further corroborated by a substantial increase in th u ratios in most mounds relative to topsoil because of the oxidizing conditions of the mounds ti and zr are likely to be adsorbed onto fe oxides positive ce anomalies relative to ucc and the high ph values in the mounds indicate calcrete aggradation or mound aeration as a result of burrowing activities of the termites and evaporation from mounds the impacts of the changes in environmental conditions and the termite activities on the mound geochemistry are highlighted by heavy ree hree as well as fe and mn retentions in the mounds heavy ree and light ree lree are likely to coprecipitate with carbonate complexes and fe and mn oxyhydroxides and in the process scavenge a series of micro nutrients such as zn cu cd and co a substantial enrichment of se in mounds despite the oxidizing conditions of the mounds could be attributed to active transport of se enriched materials from deep soil horizons the study demonstrated the suitability of ree and trace element geochemistry for assessing the influence of macrotermes on the physico chemical properties of semi arid soils

solid liquid ree fractionation in the lateritic system of goyoum east cameroon the implication for the present dynamics of the soil covers of the humid tropical regions the ree th weathering geochemistry and mineralogy has been investigated in a lateritic soil cover in relation to the close hydrographical system at goyoum east cameroon the stutied area composed of gneissic hills covered by humid tropical forest belongs to the sanaga river basin and corresponds to a transition vegetation zone between rainforest and savannah a representative soil catena was taken as a reference zone close to the sanaga river the gneissic parent rock soil and groundwater samples have been cut off in pits in the lower part of the catena waters were also sampled both in brooks rich in organic matter and in the sanaga river all the waters were sampled seasonally during the rainy and dry periods the water rock interactions and the exportation of ree and th have been discussed as a function of the evolution of specific ratios considering th as the less mobile element during laterization variation of parent rock pr normalized ratios ln th pr vs depth show that the upper ferruginous horizons are depleted in ree while the basal saprolite presents accumulation zones which are differently located for ce and the other lrees the hrees are also depleted the la accumulations are located near the saprolite gneiss weathering front associated with negative ce anomalies ce ce 0 4 the ce accumulations inducing strong positive ce anomalies ce ce 4 are located in the upper saprolite beneath the ferruginous horizons all along the soil catena the secondary lree bearing minerals which reflect lree fractionation during incipient weathering of the gneiss are hydrous phosphates rhabdophane lreepo4 nh2o and cerianite ceo2 whose precipitation depends on the eh ph changes in the soil profiles on the other hand hree depletion is controlled by the dissolution of xenotime the major hree bearer in the parent gneiss in the 0 45 m filtered acidic groundwater ph 5 5 which have flooded the saprolite for a long residence time th contents are extremely low 0 th 10 ppt while lree contents are high 90 la 450 ppt in these filtered waters th seems to be strongly controlled by minerals i e thorianite which lead to its immobilization in the soil while lree remain in the soluble and or colloidal pools moreover the groundwaters show significant negative ce anomalies throughout the year 0 1 ce ce 0 4 the mobilization of lree except redox active ce results from the dissolution and or the mobilization in colloidal form of the secondary phosphates which may present major negative ce anomalies as indicated by the bulk soil analyses at the saprolite gneiss weathering front therefore the groundwaters have the signature of saprolitic materials we propose that the strong positive ce anomalies of the upper saprolite result from ancient weathering processes these processes would have led to much stronger ce iii ce iv dissolution reprecipitation conditions than those occurring at the present time in the saprolite in the 0 45 m filtered brook acidic blackwaters lree and th contents are high 100 th 400 ppt 400 la 1700 ppt in this organic matter rich environment lree and th are highly mobilized the colloial pool controls half of the whole lree th load the geochemical signature of these waters is independent of the gneissic parent rock and soil lree contents there is no ce anomaly this signature is similar to those of other organic rich rivers draining humid tropical ecosystems in the world in the 0 45 m filtered sanaga waters lree and th contents are lower than in the brooks 15 th 40 ppt 40 la 300 ppt these concentrations are dependent on the time and on the colloidal composition however 90 of these elements are mainly controlled by the suspended pool

ree fractionation and ce anomalies in weathered karoo dolerite abstract analyses of samples from a weathering profile on karoo dolerite allow elements to be divided into three groups depending on their behaviour si k na mg ca sr ba and v are mobilized and removed from weathered products fe al ti zr hf zn cu sc co and ni are immobile ree y and to a lesser extent cr are mobile and redistributed within the profile without a net loss of these elements from the profile large positive ce anomalies are developed in oxidized weathered products by preferential leaching of the other ree s negative ce anomalies and ree enrichment is a feature of less altered dolerite

ree fractionation during granite weathering and removal by waters and suspended loads sr and nd isotopic evidence very few studies deal with ree rare earth element mobility within the system soil soil solution streamwater in this article we try to characterize the fractionation and the migration of the ree in a granite derived soil system located in a small catchment of the vosges mountains icp ms and tims measurements were performed on both solid samples fresh granite soil and suspended load of the stream and waters soil solutions springwater and streamwater to determine their respective ree concentrations and sr and nd isotopic compositions the paas normalized ree pattern of the bedrock is characterized by a strong depletion in hree heavy ree and a negative eu anomaly 0 46 similarly the granite normalized ree distribution patterns of the soil samples show hree depletions that become more important with decreasing depth the correlative behavior between p2o5 th and ree with depth indicates that besides apatite other phosphate minerals such as monazite are the most important phases controlling the th and ree budget in the soil profile on the other hand at greater depth zircon seems to be another important mineral phase controlling especially the hree enrichment as shown by the positive relationship between zr content and the yb ho ratio different grain size fractions show similar ree distribution patterns and are only weakly fractionated compared with bulk soil sample however the finest fraction 0 20 m is more enriched in sr and ree suggesting a stronger concentration of ree carrying minerals in this fraction the suspended and dissolved load of the stream show as a whole an enrichment in hree if compared with the granite or with the different soil samples however compared with the uppermost soil samples the suspended load is significantly more enriched in hree its ree distribution pattern is more similar to that of the finest fraction of the deeper soil sample and to the fresh granite thus most probably the ree of the suspended load originated from a source with ree characteristics found in the deep soil horizons this source might have been situated in the uppermost soil profile which is actually ree depleted the weathering process can be compared with a leaching experiment where the waters correspond to the leachate and the soil to the residual phase of the granite the sr isotope data indicate that the suspended load originates from the finest soil fraction the sr and nd isotopic data of the suspended load suggest that it contains up to 3 sr and nd from apatite and up to 97 from feldspar most of the sr and nd in the waters originate from apatite leaching or dissolution

pedogenic processes and domain boundaries in a vertisol climosequence evidence from titanium and zirconium distribution and morphology abstract the occurrences of titanium ti and zirconium zr within eight vertisols formed in a climosequence on the upper beaumont formation of the texas gulf coastal plain were investigated in order to determine processes responsible for ti and zr redistribution during pedogenesis discontinuities defined by significant shifts in particle size distribution and the content in volume percent of zr are present at 160 to 260 cm depth in each pedon the discontinuities are interpreted to be functional boundaries i e physico chemical expressions of pedogenic domains between an upper soil domain dominated by open system pedogenesis and a lower more closed system domain dominated by chemical weathering the depth at which the functional boundary occurs is dependent on physical and hydrogeochemical influences which are largely a function of available water soil materials above the discontinuities are slightly coarser textured and enriched in zr whereas below the sediments are finer textured and have lower and more constant zr contents the zr is associated almost exclusively with zircon and zr contents correlate positively to the weight percent sand coarse silt with negligible zr present in the profile volume loss gain i e soil strain e a mass balance calculation that assumes zr or ti immobility during pedogenesis indicate ezr values nearly four times greater than eti large values of ezr within the upper soil domains are due primarily to sand and coarse silt additions to the vertisols and preclude use of zr as a basis of mass balance calculations in these soils despite its relative chemical stability by comparison ti is generally conserved within the clay rich soil profiles and is therefore better suited for mass balance calculations of volume change and mobile element translocation during pedogenesis

parent material and chemical weathering in alpine soils on mt mansfield vermont usa we compared the elemental composition of soil and bedrock samples to determine the extent of chemical weathering and the nature of the soil parent material in alpine soils on vermont s highest summit previously it was unclear whether these soils formed through weathering of bedrock glacial till or eolian sediment or solely through the accumulation of organic matter in eighteen profiles no evidence was found to indicate that soils have developed in glacial till despite evidence that the mountain was completely inundated by the laurentide ice sheet in contrast results strongly support the theory that pedogenesis in this environment involves in situ bedrock weathering under a thickening blanket of acidic organic litter weathering indices reveal an increase in weathering intensity upwards from the bedrock and trends of normalized rare earth elements demonstrate a strong similarity between bedrock and soil samples leaching has concentrated less mobile elements such as al cr la p pb and ti in soil horizons and removed mobile elements such as co fe k mg mn si and zn x ray diffraction reveals that chlorite which is present in all bedrock samples and some saprolites has weathered completely from upper soil horizons and that hydrobiotite vermiculite kaolinite gibbsite and goethite have formed in the soil ratios of immobile elements ce cr nb ta ti y and zr in soil and bedrock samples are however notably different furthermore the moderately mobile trace elements cu mo and sr are actually more abundant in soil than in bedrock and soil concentrations of zr are up to an order of magnitude greater than in bedrock samples together these data argue for at least a modest eolian influx which may have arrived during the regression of lake vermont during the latest pleistocene or from an outwash source in the immediate post glacial period similarly increased ca and na concentrations in soil samples may signify modern deposition of dust bearing ca from agricultural fields and na from roads

tidal current ridges in the southwestern yellow sea abstract large tidal current ridges tidal sand banks in the southwestern yellow sea are located offshore of northern jiangsu province china these ridges radiate to a depth of 20 30 m the dimensions of the ridge system are about 200 km long and 90 km wide their morphology indicates the strong influence of tidal currents the ridges are composed of well sorted fine sands size range is 2 4 the grain size distributions of the sands show that the sands are transported and deposited by tidal currents the ridge system formed on the abandoned yellow river and ancient yangtze river deltas has an abundant sand supply from the former deltas of particular importance is the existence of two tidal wave systems in the yellow sea the rotary ti al wave system in the southern yellow sea and the pacific progressive tidal wave system propagated into the southern ridge area of the southwestern yellow sea under the interaction of the two tidal wave systems the huge tidal current system in the southwestern yellow sea has formed

high resolution acoustic characteristics of epicontinental sea deposits central eastern yellow sea abstract large amounts 45390 line km of closely spaced 2 2 4 4 km high resolution subbottom profiles chirp 2 7 khz made it possible to identify detailed echo types and their distribution in an epicontinental shelf environment on the basis of seafloor morphology surface bedforms and subbottom acoustic characters 10 echo types were identified in the uppermost sedimentary sequence of the central eastern yellow sea flat seafloor with sharp bottom echoes echo types 1 1 1 2 and 1 3a transgressive sediment sheets or relict sands is widespread in the offshore area and underlain to the west by an acoustically transparent wedge echo type 1 3b highstand muds mounded seafloor with either smooth surface or superposed bedforms echo types 2 1 2 2 and 2 3 tidal ridges and flat seafloor with regularly spaced wavy bedforms echo type 1 4 large scale dunes are dominant in the eastern nearshore area large scale mounds with continuous inclined internal reflectors echo type 2 4 giant mud bank occur in the southeastern nearshore area various scale eroded seafloor echo types 3 1 and 3 2 channels and flat seafloor with regularly spaced wavy bedforms echo type 1 4 large scale dunes are present in the northern part of the sea the distribution pattern of echo types in the central eastern yellow sea reflects depositional processes and sediment dispersal systems during the holocene transgression and highstand period 1 development of tidal ridges and large scale dunes in response to strong tidal currents and waves in the eastern nearshore area 2 construction of transgressive to highstand mud bank huksan mud belt by deposition of muds derived from the keum river in the southeastern nearshore area 3 active erosion due to intensified currents in the northern part and 4 highstand mud deposition derived from the huanghe river on the transgressive sediment sheets in the offshore area

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

infilling and flooding of the mekong river incised valley during deglacial sea level rise the abrupt transition from fluvial to marine deposition of incised valley fill sediments retrieved from the southeast vietnamese shelf accurately records the postglacial transgression after 14 ka before present bp valley filling sediments consist of fluvial mud whereas sedimentation after the transgression is characterized by shallow marine carbonate sands this change in sediment composition is accurately marked in high resolution x ray fluorescence xrf core scanning records rapid aggradation of fluvial sediments at the river mouth nearly completely filled the mekong incised valley prior to flooding however accumulation rates strongly reduced in the valley after the river mouth system flooded and stepped back this also affected the sediment supply to deeper parts of the southeast vietnamese shelf comparison of the mekong valley filling with the east asian sea level history of sub and inter tidal sediment records shows that the transgressive surface preserved in the incised valley fill records is a robust sea level indicator the valley was nearly completely filled with fluvial sediments between 13 0 and 9 5 ka bp when sea level rose rather constantly with approximately 10 mm yr as indicated by the east asian sea level record at shallower parts of the shelf significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface nevertheless incised valley fill records and land based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern vietnamese coastline to the cambodian lowlands between 9 5 ka and 8 5 ka bp fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the east asian sea level rise from 34 to 9 meter below modern sea level mbsl corresponding to the sea level jump of melt water pulse mwp 1c c 2010 elsevier ltd all rights reserved

experimental evidence for mobility of zr and other trace elements in soils a soxhlet extraction was carried out over a period of 27 d on a column comprising 3 cm of quartz overlain by 4 cm of soil from the b horizon and then 1 cm of soil from the a horizon of a granitic podzol major and trace elements were leached from the column and accumulated in a reservoir at the base of the column total loss of elements from the soil over the course of the experiment ranged from 0 002 to 1 wt with major elements and the light and heavy rare earth elements ree showing the largest percentage losses zirconium 0 002 and then al 0 008 showed the lowest percentage loss the light ree were leached out of the soil preferentially to the mid ree all elements showed accumulation by a factor of 2 to 11 in the quartz layers at the base of the column particularly in the upper first 1 cm of the quartz major elements were leached from the column at a rate of 0 02 to 0 59 mol h 1 whereas zr nd sm gd dy rb and sr were leached at the rate of 0 5 to 30 10 6 mol h 1 concentrations of other ree in the reservoir increased over the duration of the experiment but they were poorly correlated with time so leaching rates were not calculated normalization of the major element leaching rates to take into account the constant flushing of water through the column the average annual rainfall in the allt a mharcaidh catchment in scotland from where the soil was sampled and the cross sectional area of the soil in the column together with the temperature of the soil in the column 70 c compared with the average annual temperature of the allt a mharcaidh catchment 5 7 c gave major element release rates from the soil of 0 002 to 0 97 meq m 2 yr 1 depending on the choice of ea the dissolution activation energy which are generally less than those measured in the field of 0 1 to 40 9 meq m 2 yr 1 calculations showed that despite the redistribution and loss of zr from the column assumptions of zr mobility would have had a negligible effect on calculated element release rates of na ca fe and mg however significant underestimates of the release of k 5 ti 57 al 5 and si 10 as well as some trace elements e g nd 23 rb 54 sr 24 would have occurred concentrations of ca and sr leached from the column correlated well rsq 0 93 p 0 01 supporting the idea of the use of sr release as a proxy for ca release in weathering rate calculations the release rates and percentage loss of ree from the soil varied between elements indicating that ree distribution patterns of rocks and soils may not be preserved in drainage waters

wavelet spectral analysis of the earth s orbital variations and paleoclimatic cycles the wavelet time frequency spectral analysis is applied to geological records that are proxies of paleoclimatic variations d18o in sedimentary cores atmospheric co2 concentration and a loess magnetic susceptibility stratigraphy within the past million years these spectra are compared with those for the astronomically predicted variations of the earth s orbital eccentricity obliquity precession and their resultant variations of the incoming insolation the latter has been known to be unable to explain the characteristics of the observed 100 kyr paleoclimatic cycles based on similarities between the wavelet spectra of the orbital variations and paleoclimatic cycles the authors introduce a signal noise resonance theory to understand the dynamics of climate response to the orbital forcing it is shown that the observed 100 kyr cycles are mainly caused by the period variation in the obliquity which amplifies the small orbital forcing but the observed flickers within these cycles are induced by the amplitude variation of obliquity and precession which are two major components of the milankovitch insolation deviations

aeolian origin of the red earth in southeast china a clay like deposit known as red earth is widely distributed over the terraces and high lands of the yangtze river valley in southeast china its typical pedo stratigraphical features have attracted the interest of pedologists and geologists for many years although its origin is still debated here we report an analyses of the grain size distributions rare earth element bee patterns and upper continental crust ucc normalised major elemental composition of the red earth and compare them with those of the loess and other aeolian deposits in northern china the results show that the red earth in southeast china has two or three end member grain size distributions similar to the sedimentary characteristics and geochemical composition of aeolian deposits found in northern china together with other evidence from field observations these results suggest that the red earth is probably of acolian origin on the basis of these data we suggest that thick aeolian dusts were also deposited in the wet subtropics and that the effect of the winter monsoonal winds upon the dust transport in eastern china was more important than previously believed copyright c 2002 john wiley sons ltd

evolution of sedimentary mode since pleistocene in the central south yellow sea china based on seismic stratigraphy analysis abstract in order to investigate the distribution development and evolution of the strata in the south yellow sea basin sysb seismic and core data were analyzed fourteen 14 reflecting interfaces and 13 seismic units are identified and a stratigraphic framework since 1 81 ma b p is established the deposition rate has changed since 126 ka b p the stratigraphic model shows that the sysb responded to sea level changes during the same period 126 ka b p which suggests a model change of the development of regional strata between 1 81 ma b p and 126 ka b p the zhejiang minnan uplift zmu obstructed the intrusion of seawater into the sysb which is the main factor responsible for the development of regional strata while the sea level fluctuation and fluvial material input have dominated the formation of the strata since 126 ka b p

rare earth element geochemistry of the antalo supersequence in the mekele outlier tigray region northern ethiopia abstract the antalo supersequence ass a mesozoic carbonate marl shale succession in the mekele outlier was sampled for chemical analysis the samples were analysed by icp ms and icp oes for rare earth element ree and major elements both in the total sample and the acid soluble fraction more than 80 of the ree are held in the acid soluble fraction however the very good correlation between ree insoluble residue ir mn and fe coupled with the three fold enrichment of ree in the impure compared to the pure limestone suggests that the content of ree in the ass is related to the non carbonate constituents steep lree relatively flat hree patterns and a negative eu anomaly characterize the chondrite normalized pattern of ree fractionation of ree in the sedimentary environment is displayed by a vertical increase and a west east decrease in the lree hree ratio and by a negative ce anomaly towards the base of the ass the latter suggests that the mesozoic sea of the region was relatively more oxidizing during its earlier history of transgression the ce depletion displayed by the whole ass is however very small and this is ascribed to the influence of continental clastic materials shallowness of the basin and dominant reducing conditions in the seawater based on the similarity in the ratios and patterns of ree it is concluded that the ass and the nearby clastic unit have the same continental source of ree

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

evolution of late quaternary mud deposits and recent sediment budget in the southeastern yellow sea abstract analysis of high resolution seismic reflection profiles and sediment samples has revealed the evolution and sediment budget of the southeastern yellow sea mud belt seysm along the southwestern korean peninsula the seysm up to 50 m thick over 250 km long and 20 55 km wide can be divided into three stratigraphic units a1 a2 and b from oldest to youngest unit a1 overlying the acoustic basement comprises the northern part of the seysm unit a2 comprises the southern part of the seysm much of unit a2 is exposed at the seafloor unit b completely covers unit a1 and pinches out southward 14c data suggest that evolution of each unit is closely related to the postglacial sea level changes unit a1 consists of estuarine deltaic or shallow water muds deposited during the early to middle stage of postglacial sea level rise ca 14 000 7000 yr b p unit a2 corresponds to relict muds deposited during the last deceleration stage of sea level rise ca 7000 3 500 yr b p unit b consists of shelf muds deposited during the recent sea level highstand ca very low background activities of 210pb of the surface sediment of unit a2 suggest that the present day sediment accumulation is negligible in the southern seysm on the other hand 210pb excess activity profiles in unit b yield an average sediment accumulation rate of 3 9 mm yr indicating active sediment accumulation in the northern seysm the annual sink 3 0 10 7 tons yr of fine grained sediment in unit b is about an order of magnitude greater than can be explained by the sediment input from the korean rivers alone we propose that reworking of unit a2 has provided large volumes of muds to unit b resulting in excessive sediment accumulation in the northern seysm much of unit a2 in turn is likely to have originated from erosion of unit a1 in the north this rather unique erosional depositional regime of the seysm is probably owing to the tidal and regional currents characteristic in the southeastern yellow sea

ce anomalies in the textural components of upper cretaceous karst bauxites from the apulian carbonate platform southern italy the chemical and mineralogical composition of upper cretaceous apulian karst bauxites southern italy and their textural components i e ooids and matrix has been studied the bulk samples are composed of boehmite hematite anatase and kaolinite the samples collected along a vertical profile show a downward enrichment for the elements rb sr ba ni and cr a similar distribution is observed in deposits bauxitized in situ at the expense of matrix like material collected in the karst zone the ooids consist mainly of hematite with minor boehmite and anatase whereas in the matrix boehmite prevails on hematite kaolinite and anatase in the void fillings in the matrix there is a ca fluorocarbonate having a ce ce of 5 8 the ooids with the exception of ce are enriched in ree and show a higher la yb ch ratio relative to the matrix the matrix exhibits a large positive ce anomaly whereas the ooids have negative ce anomaly the ce fractionation between the textural components can be explained assuming 1 ce oxidation and cerianite precipitation in the uppermost part of the deposits 2 scavenging of ree from ce depleted percolating solutions by the iron oxide inducing both ree enrichment and ce negative anomalies in ooids 3 remobilization of cerium as fluoride complex as a consequence of more acidic conditions in the uppermost part of the deposit and precipitation of ce3 as fluorocarbonate mineral toward the carbonate bedrock barrier at alkaline ph alternatively the cerium remobilization possibly as a carbonate fluoride complex could be due to an eh decrease favoured by a rise of the groundwater level

early holocene mud ridge formation in the yangtze offshore china a tidal controlled estuarine pattern and sea level implications abstract the purpose of the present study is to examine the topographic evolution and sedimentary characteristics of a mud ridge system in the yangtze offshore region as revealed by seismic profiling 2 3 km wide 5 8 km long up to 15 m thick mud ridges situated 5 10 km apart extend here in a southeasterly direction approximately parallel to the direction of the ebb and flood flow of the modern tide directly resting upon the latest pleistocene terrestrial sediments some mud ridges are exposed on the present seafloor while others are buried by landward thickening holocene deltaic sediments an 11 m long vibrocore recovered from one mud ridge reveals homogenous and mottled silty clay and clayey silt rich in foraminifera suggesting an estuarine environment of deposition chronostratigraphic correlation in association with acoustic facies indicate that the mud ridge was formed primarily during 10 7 ka corresponding to a period of global decelerating rise in sea level this mud ridge is underlain by thick late pleistocene fluvial to coastal fine to medium sands with an unconformity surface on top and it is overlain by modern deltaic sediments with an erosional surface in between we propose that the mud ridges were deposited under tidal controlled estuarine conditions during the early holocene deceleration of the rise in sea level the holocene transgression in the study area was nearly coeval with the mud ridge deposition and the deltaic sedimentation occurred after the mud ridges formed the ridges were subsequently reworked largely by strong tidal currents

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

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

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

current and tide observations in the southern yellow sea determination of mean currents and tides are particularly difficult in coastal regions flows are often nongeostrophic and short lived bathymetry is frequently not adequately known and can greatly influence coastal dynamics to better quantify tides and currents in the southern yellow sea three pressure gauges and three acoustic doppler current profilers adcps were bottom moored for 4 6 month intervals at depths ranging from 77 to 89 m tidal range is over 2 m and maximum current velocities are between 50 and 80 cm s at the mooring locations the present data are analyzed for 13 significant tidal constituents which are found to account for 85 of the sea surface height variability m2 is the dominant constituent followed by s2 and k1 flow is dominated by the tides mean currents are relatively small ranging from 1 5 cm s at the northern mooring to 4 cm s at the southern mooring delineations of barotropic and depth dependent currents are made from the adcp measurements in terms of mean and eddy kinetic energy currents are found to be most depth dependent in the near surface layers approximately 85 90 of the eddy kinetic energy is depth independent

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

present weathering rates in a humid tropical watershed nsimi south cameroon the study of biogeochemical and hydrological cycles in small experimental watersheds on silicate rocks common for the temperate zone has not yet been widely applied to the tropics especially humid areas this paper presents an updated database for a six year period for the small experimental watershed of the mengong brook in the humid tropics nsimi south cameroon this watershed is developed on precambrian granitoids north congo shield and consists of two convexo concave lateritic hills surrounding a large flat swamp covered by hydromorphic soils rich in upward organic matter mineralogical and geochemical investigations were carried out in the protolith the saprolite the hillside lateritic soils and the swamp hydromorphic soils biomass chemical analyses were done for the representative species of the swamp vegetation the groundwater was analysed from the parent rock saprolite weathering front to the upper fringe in the hillside and swamp system the chemistry of the wet atmospheric and throughfall deposits and the mengong waters was monitored in the nsimi watershed the carbon transfer occurs primarily in an organic form and essentially as colloids produced by the slow biodegradation of the swamp organic matter these organic colloids contribute significantly to the mobilization and transfer of fe al zr ti and th in the uppermost first meter of the swamp regolith when the organic colloid content is low i e in the hillside groundwater th and zr concentrations are extremely low 3 pmol l icp ms detection limits strongly insoluble secondary thorianite tho 2 and primary zircon zrsio 4 crystals control their mobilization respectively this finding thus justifies the potential use of both these elements as inert elements for isoelement mass balance calculations pertaining to the hillside regolith chloride can not be used as a conservative tracer of hydrological processes and chemical weathering in this watershed biogenic recycling significantly influences the low cl input fluxes sodium is a good tracer of chemical weathering in the watershed the sodium solute flux corrected from cyclic salt input was used to assess the chemical weathering rate even though low 2 8 mm kyr the chemical weathering rate predominates over the mechanical weathering rate 1 9 mm kyr compared to the rio icacos watershed the most studied tropical site the chemical weathering fluxes of silica and sodium in the mengong are 16 and 40 times lower respectively this is not only related to the protective role of the regolith thick in both cases but also to differences in the hydrological functioning this is to be taken into account in the calculations of the carbon cycle balance for large surfaces like that of the tropical forest ecosystems on a stable shield at the global level

pedogenesis of late quaternary deposits northern kyonggi bay korea implications for relative sea level change and regional stratigraphic correlation abstract late pleistocene and early holocene paleosols are described from construction pits and boreholes in the northern kyonggi bay west coast of korea thin section petrography chemistry clay mineralogy and geotechnical properties of the paleosols were examined to infer relative sea level fluctuations during the late quaternary relict laminae and gradational contacts with underlying tidal rhythmites confirm that the late pleistocene paleosol is a pedogenically altered tidal deposit illuvial clay coatings rootlets and enrichment of kaolinite and chemically stable oxides indicate that pedogenesis occurred on a well drained stable surface during the last glacial period redoximorphic features such as drab colored root traces and sphaerosiderite however suggest that waterlogged conditions developed temporarily due to a rise of the water table at the end of the last glacial period as sea level rose an early holocene paleosol formed in freshwater bog deposits burying the late pleistocene paleosol the early holocene paleosol has abundant sphaerosiderites and organic material the presence of weakly developed illuvial clay coatings oxidized siderites and pellets however indicates oxidizing condition associated with water table fall occurred during the early holocene despite the similarity in the degree of chemical and clay mineralogical weathering the late pleistocene paleosol is distinguished from its early holocene counterpart by thicker and more abundant illuvial clay coatings more fe 2 o 3 and a greater degree of consolidation duration of pedogenesis might be a primary cause for the difference of the pedofeatures with climate playing a secondary role the widespread presence of similar late pleistocene paleosols highlights its significance as a key stratigraphic marker for regional correlations along the west coast of korea

geochemistry of mansar lake sediments jammu india implication for source area weathering provenance and tectonic setting abstract the sediment geochemistry including ree of surface and core samples from mansar lake along with mineralogical investigations have been carried out in order to understand the provenance source area weathering hydrolic sorting and tectonic setting of the basin the geochemical signatures preserved in these sediments have been exploited as proxies in order to delineate these different parameters the major element log values fe 2 o 3 k 2 o vs sio 2 al 2 o 3 and na 2 o k 2 o vs sio 2 al 2 o 3 demarcate a lithology remarkably similar to that exposed in the catchment area the chondrite normalized ree patterns of lake samples are similar to post archaean australian shale paas with lree enrichment a negative eu anomaly and almost flat hree pattern similar to a felsic and or cratonic sedimentary source however the la th sc plot of samples fall in a mixed sedimentary domain close to upper continental crust ucc and paas suggesting sedimentary source rocks for the mansar detritus it also indicates that these elements remained immobile during weathering and transportation the mineralogical characteristic rees and high field strength elements hfse together with the high percentage of metamorphic rock fragments in the siwalik sandstone support a metamorphic source for lower siwalik sediments a very weak positive correlation between zr and sio 2 poor negative correlation with al 2 o 3 negative correlation of la yb n and gd yb n ratios with sio 2 and positive correlation with al 2 o 3 suggest that zr does not dominantly control the ree distribution in mansar sediments the petrographic character and textural immaturity indicate a short distance transport for the detritus the distribution of elements in core samples reflect fractionation the higher zr th and zr yb ratios in coarse sediments and paas compared to finer grained detritus indicate sedimentary sorting plots of the geochemical data on tectonic discrimination diagrams suggest that the sediments derived from the lower siwalik were originated within a cratonic interior and later deposited along a passive margin basinal setting it therefore reveals lower siwalik depositional history

chemical physical and micromorphological properties of termite mounds and adjacent soils along a toposequence in zona da mata minas gerais state brazil article i nfo little is known about the effects of neotropical mound building termites in soil chemical and physical properties the influence of soil termite activity on soil characteristics was studied by assessing chemical physical and micromorphological properties of a toposequence of latosols oxisols soil samples were collected from the walls and inner parts of termite mounds and also from adjacent soil a high diversity of termite genera was found in the mounds along the toposequence together with the inquiline termites and other soil dwelling arthropods chemical analyses showed that ph and the contents of organic c and n p ca and mg were significantly higher in termite mounds compared with adjacent areas with an inverse trend for al content significant differences in ph and exchangeable al were observed between soil and mound across the slopes the mound density across the landscape was higher at the upper slope segment followed by the hill top middle slope and lower slope segments considering a lifespan of 30 years and dimensions of termite mounds found in the toposequence we conclude that the textural and chemical uniformity of latosols may be increased following the pedobiological turnover during mound building with local rates varying from 2 1 to 7 5 m 3 ha 1

origin of inner shelf mud deposit in the southeastern yellow sea huksan mud belt abstract a variety of previous sedimentological results together with newly obtained hydrodynamic data are summarized and reinterpreted with respect to the most likely origin of the huksan mud belt hmb in the southeastern yellow sea the hmb consists of two mud units that have similar grain texture and clay mineralogy but can be differentiated on seismic profiles because the lower unit is generally harder than the watery upper unit the hydrographic measurements together with satellite imagery clearly indicate that the suspended plume covering the hmb originates from the west coast of korea the suspended plume becomes enhanced by winter monsoon winds beginning in late fall most of the studies of clay mineralogy geochemistry and isotherm distribution also suggest that the hmb has been derived from the west coast of korea particularly from the keum river an approximate evaluation of the depositional time for the hmb based on its dimensions and the discharge rate of the keum river suggests a time duration of the order of 14 000 years hydrodynamic measurements across two transects over the northernmost hmb reveal that suspended matter travels southwest toward the main body of the hmb in a well constrained corridor ultimately connected with the keum river time series 12 5 h hydrodynamic measurements at a site over the hmb suggest that the winter season suspended plume carries concentrations of suspended matter one to two orders of magnitude higher than those of the summer silt grains of 5 6 well sorted through numerous resuspension events settle out onto the hmb forming distinctive silt laminae alternating with clay rich laminae

headland associated banner banks generated during the last deglaciation near the strait of gibraltar gulf of cadiz sw spain the inception and evolution of large scale bedforms on the barbate platform gulf of cadiz sw iberian peninsula are investigated based on a detailed study of multibeam bathymetric data high resolution seismic profiles and tidal current simulations elongated rocky outcrops and several large scale bedforms classified as sand banks were identified on the platform barbate zahara el palmar el varadero and canos de meca banks the barbate and zahara banks exhibit the most complex internal stratigraphic architecture which comprises five seismic units the basal unit u1 is interpreted as incised valley infill and is overlain by nearshore bars u2 two high energy growth phases u3 and u4 that combine progradation and accretion form the present day external bank shape superimposed bedforms covered these banks under the modern hydrodynamic regime u5 the multiphase accretion and progradation of u3 and u4 in the zahara and barbate banks were closely linked to the presence of a palaeo headland termed here as palaeo cape trafalgar and strong tidal current eddies that resulted from the progressive flooding of the barbate platform during the last deglaciation this configuration was relatively stable while the rocky outcrops were exposed to sub aerial conditions forming a palaeo coast with coastal bluffs we suggest that during this period of coastal stabilization u3 and u4 grew as banner banks on either side of the palaeo cape trafalgar the present study proposes that the configuration of palaeo headland associated with palaeo banner banks zahara and barbate banks along each side of the palaeo cape trafalgar represents a transgressive analogue model of headland associated tidal bank systems developed in funnel shaped coastal systems terminating in narrow straits

the growth of the continent through geological time studied by nd isotope analysis of shales abstract we determined the nd isotopic composition and the sm nd ratios in a series of australian shales ranging from 0 2 gy to 3 3 gy the first result of this study is the constancy of the sm nd ratio in these shales as in granitoids secondly the initial 143nd 144nd ratio gives a regular curve decreasing through geological time both results confirm that shales are representative samples of the continental crust when insoluble elements like ree are studied we calculated their nd model ages of crustal differentiation the model ages regularly decrease with the stratigraphic ages and after 2 gy the curve flattens and tends to an asymptotic value at around 1 8 gy the significance of the shales is that they represent a mixture of continental materials and we consider the model age of such a mixture directly linked with the mean age of the continental portion feeding the sedimentary basin from these results we deduce a quantitative model of the growth curve of the continental source of the shales taking into account the effects of erosion which selectively sample recent mountains relative to shield areas we propose that the results obtained here are representative of the whole gondwana continent having studied the case of the australian shales we try to extend our study first we applied our quantitative approach to the recent results obtained by o nions et al on north atlantic provinces the continental growth curves obtained by our inversion procedure are quite distinct from the australian shales showing the regional character of shales with these two cases studied we try to compare our results with the already developed model for continental growth the consideration of the surface conservative versus surface non conservative models clearly show the non uniqueness of the geological interpretation of the growth curve on the other hand we have calculated for each case the recycling rate versus geological time by comparing the growth curve with the hurley rand province age curve such recycling increases with time in agreement with the data obtained on nd and sr initial ratios on granitoids

the sedimentary succession of the last 3 50 myr in the western south yellow sea paleoenvironmental and tectonic implications abstract the south yellow sea sys basin which is part of the west pacific continental margin began to form in the late mesozoic to early cenozoic as a result of regional tectonic activity in asia the pre middle pleistocene sedimentary history of the area remains poorly understood or controversial mainly due to a lack of long borehole cores penetrating pre quaternary strata borehole core csdp 1 300 10 m long the longest sediment core recovered thus far from the sys was drilled in 2013 in the western sys recently a reliable timescale for the core for the last 3 50 myr was obtained by magnetostratigraphy liu et al 2016a here we report the results of integrated analyses of the core including sedimentary characteristics downcore changes in environmental proxies benthic foraminifera and ostracods and accelerator mass spectrometry 14c and optically stimulated luminescence dates in addition we analyze 546 km of single channel seismic profiles and 50 km of a boomer seismic profile around the core site and correlate the regional stratigraphy the core sedimentary succession contains 17 depositional units lithofacies associations corresponding to three major seismic units reflecting a variety of depositional environments during the last 3 50 myr our results show that fluvial environments prevailed in the western sys from 3 50 to 1 66 ma followed by alternations of tidal flat to shallow subtidal environments with fluvial environments from 1 66 to 0 83 ma and alternations of modern like marine environments and fluvial environments from 0 83 ma to the present day in response to glacio eustatic sea level cycles the depositional succession during the last 3 50 myr was dominantly controlled by tectonism and glacio eustatic sea level cycles the presumed first marine transgression since the neogene in the western sys at 1 66 ma is interpreted to suggest that sea water could partially flood the zhe min uplift zmu into the sys due to tectonic subsidence and further subsidence of the zmu and the sys shelf is inferred to have resulted in establishment of normal marine environments in the sys during the highstands of glacio eustatic sea level cycles since 0 83 ma the average subsidence rates in the western sys were 120 165 m myr during the last 1 66 myr the sedimentary succession comprises fifth and fourth order sequences which are interpreted to have been driven by the 20 kyr or 41 kyr and by the 100 kyr glacio eustatic sea level cycles respectively since the late pliocene the sequences deposited since the late pleistocene are relatively complete recording deposits from mis 5 to mis 1 however the pre upper pleistocene sequences show significant stratigraphic hiatuses presumably caused by fluvial erosion during the glacial sea level lowstands and subsequent transgressive erosion this type of significant discontinuity in the sedimentary record can be considered to be diagnostic of shelf sequences controlled by glacio eustatic sea level cycles

composition and trace element geochemistry of detrital clay and heavy mineral suites of the lowermost amazon river a provenance study abstract compositions of clays and heavy minerals as well as trace element geochemistry of the lowermost amazon sediments reflect source regions and the intense chemical weathering conditions illite and montmorillonite indicate mountainous sources under physical weathering conditions whereas kaolinite is related to the soil composition under humid tropical conditions where chemical weathering predominates the suite of unstable heavy minerals on the other hand reflects some sediment transport from the andes more supply from tributaries draining the basic and metamorphic rocks from the southeastern guiana shield and strongest influence of the upstream amazon and solimoes areas these source signals are damped by transitional storage and intense lateral sediment exchange between channel and floodplain the brazilian shield contribution via the xingu river seems to be of minor importance although the alter do chao and the barreiras formations which are products of erosion of the shields supply suites of stable heavy minerals that reflect recycling rare earth and trace element data from the clay and heavy mineral fractions provide additional clues to the source areas in the downstream direction superimposed upon provenance of sediments from an undifferentiated arc the andes is provenance from strongly weathered continental crust the precambrian shields as well as sedimentary recycling small scale provenance can be delineated by the most immobile elements heavy rare earth elements in the heavy mineral fraction increase downstream toward estreitos to the para river

development of stratigraphy and sediment distribution in the northeastern yellow sea during holocene sea level rise abstract a succession of holocene deposits in the northeastern yellow sea were interpreted in a sequence stratigraphic context and sedimentology of each deposit was characterized based on analyses of high resolution seismic profiles and sediment cores taken along a transect thin 3 m transgressive sediments that accumulated through shoreface erosion during the rapid sea level rise in the early holocene overlie a subaerially eroded low gradient late pleistocene platform on the present day inner shelf region cores reveal marine sands over tidal estuarine sandy muds with an intervening rather indistinct ravinement surface in the deepest shelf area these early holocene tidal estuarine deposits remain exposed at the seabottom in the mid o late holocene two contrasting deposits of the highstand type deltaic clayey mud and tidal sand ridges began to accumulate in response to slower rates of sea level rise a series of tidal sand ridges in the nearshore area migrated offshore over the transgressive sand sheet and a deltaic watery mud prograded discordantly over consolidated tidal estuarine deposits in the central shelf the transgressive facies relationships present a model for macrotidal epicontinental sea settings subject to low wave energy and reduced sediment supply