dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

flux and fate of small mountainous rivers derived sediments into the taiwan strait article i nfo high resolution chirp sonar profiles across the taiwan strait reveal a large silt sand dominated deltaic clinoform up to 50 m thick overlying the postglacial transgressive sea floor across the southeastern central and northern strait delta like configuration and internal depositional sequences indicate a northwestward progradation from western taiwan primarily from the choshui zhuoshui river grain size and mineral data confirm the sediment s taiwanese derivation the chirp profiles together with existing radiocarbon and geomagnetic dates suggest that the clinoform has formed over the past 10 kyr the estimated volume of 375 km 3 of sediment mainly sand and silt suggests a mean annual accumulation of 60 10 6 t yr presumably much of fine mud delivered by taiwanese rivers has been washed away by the local currents and escaped either northeastward into the southern okinawa trough or southward into the south china sea numerous shallow borings onshore over the central western taiwan coastal plain reveal an additional 350 km 3

age limits on the late quaternary evolution of the upper loire river abstract the loire river is one of the largest rivers in europe draining a basin area of southern france which exceeds 100 000 km 2 despite its significance the loire remains poorly studied and has a very limited amount of chronological control on the deposited sedimentary record of fluvial activity these factors coupled with the availability of a set of 10 radiocarbon dates on younger c

determining the burial time of single grains of quartz using optically stimulated luminescence abstract in the optical dating of sediments it is usually assumed that the optically stimulated luminescence osl signal has been completely reset by light exposure prior to burial this assumption is often not valid one approach to testing and perhaps circumventing this assumption is to examine the apparent date of last exposure to daylight of individual sediment grains this paper reports on the application for the first time of 2 new measurement protocols to the estimation of the radiation dose received during burial for individual quartz grains from an aeolian deposit of known age 10 000 year old which is considered likely to have been completely reset by sunlight at deposition additive dose laboratory doses added to the burial dose before osl measurement and regenerative dose doses added after measurement of osl from burial dose single aliquot protocols are applied to 28 and 25 individual grains respectively each grain provides an independent estimate d e of the burial dose the average d e from the additive dose protocol 21 8 1 1 gy is in good agreement with the average from the regenerative dose protocol 23 8 1 0 gy both agree well with 1 13 multiple grain regenerative dose single aliquot measurements each on 1 mg sub samples of 23 9 0 3 gy 2 9 multiple grain additive dose single aliquot measurements also on 1 mg sub samples of 22 4 0 7 gy and 3 one previously published multiple aliquot additive dose estimate of 23 5 0 6 gy using 52 sub samples each of 5 mg the resulting optical ages are in good accord with 14 c and thermoluminescence age determinations the distribution of equivalent doses in the single grains is however unexpectedly large 23 of mean d e given the very likely complete resetting of the osl signal at deposition possible reasons are discussed and it is concluded that heterogeneity in beta dosimetry is the most likely explanation the single grain optical dating protocols reported here allow a detailed examination of the dose distribution in very small samples thus they should enable accurate dates to be obtained for sediments and soils that contain poorly bleached or mixed age components as well as deposits in which quartz grains are present in extremely low abundance

quaternary sediments in the dien bien phu fault zone nw vietnam a record of young tectonic processes in the light of osl sar dating results abstract the dien bien phu fault zone dbp orientated nne to n is one of the most seismically active zones in indochina in nw vietnam this zone is 160 km long and 6 10 km wide cutting sedimentary and metamorphic rocks of the late proterozoic palaeozoic and mesozoic age as well as palaeozoic and late triassic granitoids along the dbp relatively small narrow pull apart basins occur the three largest of which chan nua lai chau and dien bien phu have been studied in detail all of them are bounded by sinistral and sinistral normal faults responsible for offset and deflected drainage presence of numerous shutter ridges and displaced terraces and alluvial fans the normal component of motion is testified to by well preserved triangular facets on fault scarps highly elevated straths in river watergaps overhanging tributary valleys as well as high and uneven river bed gradients our observations indicate a minimum recent sinistral offset ranging from 6 8 to 150 m for holocene valleys to 1 2 9 75 km for middle late pleistocene valleys in different fault segments the thickness of quaternary sediments varies from 5 25 m in the lai chau area to some 130 m in the dien bien phu basin in the lai chau basin the middle terrace 23 m alluvia of nam na river at muong te bridge have been optically stimulated luminescence single aliquot regenerative dose technique osl sar dated at 23 40 to 13 ka these sediments were normal faulted by some 11 m after 13 ka and mantled by vari coloured slope loams 8 12 m thick containing colluvial wedges composed of angular debris these wedges were probably formed due to at least three palaeoseismic events postdating 6 ka in the dien bien phu basin in turn alluvium of the upper holocene terraces has been osl sar dated to 6 5 7 and 1 7 1 0 ka whereas the younger sub recent terrace sediments give ages of 0 5 0 2 ka displaced terraces and alluvial fans allow us to suppose that the sinistral and sinistral normal faults bounding narrow pull apart basins in the southern portion of the dbp fault reveal minimum rates of left lateral strike slip ranging from 0 6 to 2 mm year in holocene and 0 5 3 8 mm year in pleistocene times whereas rates of holocene uplift tend to attain 1 mm year north of lai chau and 0 4 0 6 mm year west of dien bien phu more precise estimations however are difficult to obtain due to poor age control of the displaced drainage rates of quaternary strike slip are comparable with those of the red river fault the sense of movement being however opposite taking into account the presence of two phases of late cenozoic strike slip of contrasting sense of motion as well as the geometry of the two fault zones we hypothesize that the red river and dien bien phu faults are conjugate faults capable of generating relatively strong earthquakes in the future

recognition of insufficient bleaching by small aliquots of quartz for reconstructing soil erosion in greece optical dating of sediments requires sufficient bleaching of the material to be dated using single aliquot techniques the statistical parameter of the coefficient of variation v in combination with the reduction of mineral grains per aliquot enables the detection of insufficiently bleached samples this was empirically tested on quartz extracts from the greek study area which were artificially bleached differently dosed and then mixed to simulate insufficiently bleached samples the single aliquot regenerative dose protocol was applied the test measurements show that for the studied quartz material the detection of insufficient bleaching is possible if small aliquots of 200 500 grains and a threshold value of v 10 are used the technique was applied to the age determination of colluvial and alluvial torrential deposits from the study area the basin of phlious in greece the optically stimulated luminescence age data allow reconstruction of the history of holocene soil erosion which essentially started in the 7th millennium bc simultaneous with the onset of agricultural activities in the early neolithic

the radiocarbon age of organic carbon in marine surface sediments abstract long term carbon cycling and climate change are strongly dependent on organic carbon oc burial in marine sediments radiocarbon 14 c has been widely used to constrain the sources sinks and processing of sedimentary oc to elucidate the dominant controls on the radiocarbon content of total organic carbon 14 c toc accumulating in surface sediments we construct a box model that predicts 14 c toc in the sediment mixed layer measured as fraction modern fm our model defines three distinct oc pools degradable semi labile and refractory and assumes that 14 c toc flux to sediments is exclusively derived from surface ocean primary productivity and hence follows a generic surface ocean dissolved inorganic carbon dic bomb curve model predictions are compared to a set of 75 surface sediment samples which span a wide geographic range and reflect diverse water column and depositional conditions and for which sedimentation rate and mixed layer depth are well characterized our model overestimates the fm value for a majority 65 of these sites especially at shallow water depths and for sites characterized by depleted 13 c toc values the model is most sensitive to sedimentation rate and mixed layer depth therefore slight changes to these parameters can lead to a match between modeled and measured fm values at many sites yet in some cases we find that measured fm values cannot be simulated without large and unrealistic changes to sedimentation rate and mixed layer depth these results point to sources of pre aged oc to surface sediments and implicate soil derived terrestrial oc reworked marine oc and or anthropogenic carbon as important components of the organic matter present in surface sediments this approach provides a valuable framework within which to explore controls on sedimentary organic matter composition and carbon burial over a range of spatial and temporal scales

thermoluminescence dating of australian palaeo earthquakes abstract thermoluminescence tl dating is a useful tool for determining the age of prehistoric earthquakes by dating deposits that are stratigraphically related to fault scarps that formed during the earthquakes tl dating of aeolian sand in the area of the 1988 tennant creek northern territory earthquakes provides evidence that similar earthquakes have not ruptured the causative faults for at least 50 ka pilot tl measurements of deposits associated with the roopena and ash ridge fault scarps near whyalla on eyre peninsula south australia suggest an age of 140 ka for the quaternary deposits associated with the formation of the scarps

sources and radiocarbon ages of organic carbon in different grain size fractions of yellow river transported particles and coastal sediments abstract the elemental toc tn and c n and carbon isotope 14c and 13c compositions of organic matter were measured in different grain size fractions of particles transported by the yellow river and surface sediments in the bohai sea and the yellow sea in the riverine particle and sediment samples high oc contents were associated with small grain size fractions consisting mainly of clay minerals the 13c and 14c values of the bulk riverine particulate organic carbon poc collected from the lijin and xiaolangdi sites were relatively constant but varied significantly 21 9 to 26 0 and 325 to 620 respectively among the different size fractions in comparison large spatial variations in 13c 20 6 to 24 5 and 14c 188 to 646 values which increased seaward due to the difference in source carbon were found for bulk toc 14c preserved in the surface sediments but no significant differences were observed among the values in the different size fractions in most sediments the different carbon isotopic values of the riverine poc and sedimentary toc reflect differences in the sources degradation and cycling time scales of the oc the yellow river exports very old 5220 295 yrs poc that is much older than the toc 2457 676 yrs preserved in the surface sediments in the bohai and yellow seas calculations using a dual isotope three end member model indicate that pre aged soil oc and ancient fossil oc represent major proportions 57 16 and 30 8 respectively of the riverine poc and that terrestrial biomass oc represents a minor proportion 13 11 the drainage environment of the river plays important roles in controlling the sources and ages of the riverine poc in contrast the toc in the grain size fractions of the surface sediments in the bohai and yellow seas is dominated by marine derived modern oc 47 13 followed by pre aged soil oc 29 9 and ancient fossil oc 25 14 the ages of the toc are determined mainly by the source input rapid sedimentation sediment minerology and decomposition of oc during early diagenesis in these large river influenced marginal seas

bulk particulate organic carbon in the east china sea tidal influence and bottom transport abstract five oceanographic surveys were carried out in the east china sea ecs and yellow sea from 1999 to 2003 in all seven different sections were surveyed but one section the pn section was observed on every cruise two time series stations were also surveyed one located at the changjiang river mouth the other over the continental shelf in the pn section we identified biogeochemical characteristics for waters close to the changjiang estuary and in the kuroshio waters kw respectively resuspension is a strong feature near bottom over the ecs continental shelf with suspended matter values 13 times higher than that for the surface a model of particulate organic carbon poc dynamics based on a rectangle equation reveals that poc concentration close to the changjiang estuary varies with a semidiurnal period of 13 h coinciding with the tidal period the upper limit for poc residence times in the seasons we covered over the shelf are estimated to be on the order of weeks and generally increase seaward from near the changjiang estuary to the kw short poc residence times suggest that poc in the ecs is rapidly exported from euphotic waters a nepheloid layer observed as elevated suspended matter in near the bottom of the water column is important in particle transfer over the shelf especially in winter when the residual current flows mainly eastward cross shelf transport of poc via the nepheloid layer is estimated to be 0 22 1012 g yr 1 comparison with other work indicates that poc transport is 2 of the changjiang poc input

size sorting in marine muds processes pitfalls and prospects for paleoflow speed proxies the basis for and use of fine grain size parameters for inference of paleoflow speeds is reviewed here the basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field experimental data on suspended sediment transport and deposition and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed in the deep sea sorting events occur under resuspension deposition events in benthic storms at flow speeds below 10 15 cm s 1 size in the noncohesive sortable silt 10 63 m range is controlled by selective deposition whereas above that range removal of finer material by winnowing also plays a role the best particle size instruments to measure a flow speed related grain size employ the settling velocity method while laser diffraction sizers can yield misleading results because of particle shape effects potential problems including source effects downslope supply on continental margins spatial variability of flow over bedforms and influence of ice rafted detritus are examined a number of studies using the sortable silt flow speed proxy are reviewed and inverse modeling of grain size distributions is examined outstanding problems are that corroboration is sparse because almost no studies have yet used the full range of proxies for flow rate and water mass identification and that the sortable silt mean size is not yet properly calibrated in terms of flow speed

hydrodynamic condition and suspended sediment diffusion in the yellow sea and east china sea based on monthly averaged current temperature and salinity we analyzed the changes of suspended sediment concentration ssc and the relationship with the warm current coastal current and cold water mass cwm in the east china seas ecss the result shows that the coastal current and surface diluted water are the route for transporting suspended sediment the kuroshio and its derived warm current branches play the important role of the continental shelf circulation system and control the diffusion of suspended sediment high ssc has been mainly concentrated in coastal current and cwm two sedimentary dynamic patterns have been identified the winter half year pattern lasts almost 7 months the coastal currents off the shandong peninsula northern jiangsu zhejiang fujian coast are the main routes for diffusion and deposition of the suspended sediment from the yellow river and changjiang river the summer half year pattern is characterized by the well developed cwm all cwms have a unique function to trap suspended sediment under the thermocline due to weakening tidal current and residual current there these cwms in the yellow sea ys and north ecs are connected together the layer above the thermocline is characterized by diluted water with low salinity high temperature suspended sediment can be transported into the okinawa trough and the south korea coast during this period a strong eddy always occur nearby the kuroshio bend at northeast taiwan which has promoted the exchange between the ecs shelf and okinawa trough and the development of the shelf edge current and taiwan warm current twc

optical dating of colluvial deposits from xiyangfang china and the relation to palaeo earthquake events abstract ten samples of slope wash and colluvial deposits from a trench wall at xiyangfang yanqing county located in the northern margin fault zone of the yanqing basin about 90 km northwest of beijing have been dated by both green light stimulated emission glsl and infra red stimulated emission irsl four of the samples were measured in both adelaide riso equipment and beijing daybreak equipment with essentially consistent results the paper gives a comparison of equivalent dose values obtained by both glsl and irsl the xiyangfang trench wall presents four fault scarp collapsed wedges showing a clear normal faulting pattern which can be interpreted as a record of palaeo earthquake events covering a time period from about 100 ka to the modern a return time of about 7000 yr is suggested for events at this site an attempt is made to correlate the dating records with the local earthquake history of destructive earthquakes in the last 2000 yr

episodic late quaternary palaeogully erosion in northern kwazulu natal south africa abstract hillslope deposits in northern kwazulu natal south africa are incised by gullies dongas which expose sequences of buried palaeosols developed within a succession of discontinuity bounded colluvial sedimentary units infilled and buried palaeogully topography attests to at least four geomorphic cycles comprising gully cut and fill and palaeosol formation on hillslopes in the region during the past 135 ka past attempts at dating colluvial stratigraphic units were limited to radiocarbon dating of associated palaeosol organic matter and authigenic soil carbonates this study presents a preliminary set of infra red stimulated luminescence irsl age determinations pertaining to deposition of the succession of colluvial units infilling and burying palaeogullies at several sites of stratigraphic geochronological and palaeoenvironmental importance in the region interpretation of the irsl and 14 c dates in the context of cyclical hillslope processes suggests that past episodes of palaeogully erosion and infill were not synchronous and individual palaeosol landsurfaces were diachronous during the late pleistocene

changes in sediment flux and storage within a fluvial system some examples from the rhine catchment the rhine river system can look back on a long history of human impact whereas significant anthropogenic changes to the river channel started only 200 years ago the impacts of land use have been felt for more than 7500 years here we review results from several case studies and show how land use change and climate impacts have transformed the fluvial system we focus on changes in sediment delivery pathways and slope channel coupling and show that these vary in time and depend on the magnitude of a rainfall event these changes must be accounted for when trying to use sediments as archives of land use change and climatic impacts on fluvial systems for example human impact is recorded in slope deposits only as long as rainfall intensity and runoff generation do not exceed the threshold for gullying similarly climatic impacts are only recorded in alluvium when both the landscape is rendered sensitive by human activities e g deforestation and rainfall thresholds for gullying are exceeded copyright 2003 john wiley sons ltd

reevaluation of holocene faulting at the kaysville site weber segment of the wasatch fault zone utah the 1978 kaysville utah trench excavated by swan and others 1980 across a large graben of the weber segment of the wasatch fault zone was reexcavated in 1988 to reevaluate the timing and nature of holocene faulting relogging of the trench reveals evidence for five or six faulting events younger than the provo phase of lake bonneville circa 13 000 14c years b p geometric reconstruction of net vertical offset in the last three events suggests a variation in coseismic vertical displacement at this site ranging from a net of 1 4 3 4 m per event the three latest faulting events occurred at shortly before 0 6 0 8 ka 2 8 0 7 ka and circa 3 8 7 9 ka earlier events cannot be directly dated because older graben fill sediments yielded thermoluminescence ages older than the time of deposition and some scarp derived colluvial wedges beneath the trench floor were not exposed the two younger faulting events we recognize at kaysville correlate reasonably well with faulting events on the same segment 25 km north near east ogden utah at circa 0 8 1 2 ka and 2 5 3 0 ka forman and others 1991 whereas the earlier kaysville event is significantly older than the earliest 3 5 4 0 ka event dated at east ogden the 3 5 4 0 ka ground rupture recognized at east ogden may have died out at a subsegment boundary between the two trench sites within the 61 km long weber segment

soil erosion history in central tanzania based on osl dating of colluvial and alluvial hillslope deposits abstract the irangi hills in kondoa district central tanzania are severely degraded by sheet rill and gully erosion using recently developed optically stimulated luminescence osl dating techniques and a detailed study of the hillslope stratigraphy and soils we have determined the sequence of events that gave rise to this highly degraded landscape two major colluvial deposits have been identified on the slopes the oldest colluvium gave osl deposition dates of 14 700 1600 14 200 1500 and 11 400 1300 years ago these dates coincide with the climatic change from dry to wet conditions which took place during the late pleistocene it is possible that the erosion and deposition of the old colluvium occurred as a response to this change this phase of erosion and deposition was followed by a long phase of stability and pedogenetic alteration of the old colluvium a phase of accelerated soil erosion began not later than 900 years ago as indicated by a dated alluvial fan the presence of which indicates that some deeper gullies already existed on upper pediment slopes at that time the second more recent colluvial deposit gave osl dates of 460 40 590 70 and 660 50 years a major period of gully formation and incision with subsequent fan development occurred sometime between 600 and 300 years ago the recent phase of erosion

the distribution of apparent dose as determined by optically stimulated luminescence in small aliquots of fluvial quartz implications for dating young sediments abstract we noted recently murray et al 1995 that quartz samples taken from in channel fluvial deposits have apparent doses ranging over several orders of magnitude we suggested that these dose distributions are best explained by a mixture of a small number of poorly bleached grains and a larger number of well bleached grains in this paper we examine the distribution of apparent dose in small aliquots each composed of 2000 grains of different particle size fractions 63 90 m 90 125 m 125 180 m 180 212 m 212 250 m diameter from two samples collected from the murrumbidgee river new south wales australia the samples are of known burial age the first being 70 years old and the second being its modern equivalent 0 2 gy the difference in the lowest apparent dose in the two samples is considered to be the result of their different burial times we suggest a method for dating recently deposited

thermoluminescence dating of quaternary red sand beds a case study of coastal dunes in sri lanka red sand beds that occupy extensive tracts of coastal humid tropics have conventionally been considered undatable results of a first successful attempt to provide an absolute chronology to these sediments based on thermoluminescence dosimetry are presented along with a discussion on the importance of an understanding of ambient geochemistry in the application of the thermoluminescence technique the results on the sri lankan coastal region indicate that the sea level in the region may have been affected by regional tectonics during the past 70 000 years based on in situ finds of geometric microliths in the red sands a date of ca 25 000 years is ascribed to them suggesting them to be substantially older than believed so far

classic and new dating methods for assessing the temporal occurrence of mass movements abstract establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research and for the assessment of landslide hazards as part of applied geomorphology we discuss the applicability of different methods for determining landslide chronologies frequencies and dynamics in relation to the type of material being dated sampling location and type of mass movement the emphasis is on the possibilities and limitations of the different dating methods established methods such as radiocarbon dating lichenometry and dendrochronology are briefly discussed the paper focuses however on 1 new analytical techniques like accelerator mass spectrometry ams thermally ionising mass spectrometry tims and laser fusion which have led to significant improvements of established dating methods and on 2 new dating methods like optically stimulated luminescence osl dating and alpha recoil track art dating

infrared stimulated luminescence dating of holocene colluvial sediments using the 410 nm emission abstract infrared stimulated luminescence irsl ages are reported for loessic colluvial sediments from wiesenbach south germany the samples were collected by boring and the polymineral fine grain fraction t4 1 i m was used for irsl investigations irsl spectra were measured prior to dating they show two major emissions at approx 560 and 410 nm the advantages of the subtraction dating technique aitken and xie 1992 using the 410 run emission are demonstrated the ages obtained are used for the reconstruction of the landscape development at the studied site subsequent to an erosion phase the deposition of a colluvium started prior to the roman period and increased to a maximum accumulation rate during the middle ages

luminescence dating of poorly bleached sediments from scotland abstract two types of poorly bleached sediment are differentiated and the applicability of various luminescence dating methods is assessed the methods are applied to three fluvioglacial sediments from scotland it is shown that it is possible to detect sediments that contain a mixture of well bleached and unbleached grains using the single aliquot additive dose method or the analysis of the scatter in aultiple aliquot additive dose growth curve

longshore suspended sediment transport and its implications for submarine erosion off the yangtze river estuary abstract coastal currents that originate from large rivers play a key role in delivering sediment to shelf regions quantifying their transport capability is therefore essential to understanding the sediment budgets and the consequent deposition or erosion of coastal areas in february 2012 we observed the sediment transport carried by the min zhe coastal current that originates from the yangtze river mouth and calculated a flux of 18 7 tons per second on a cross shore section in this period the coastal current was at a typical status which allowed us to estimate a total annual sediment transport of 0 27billion tons southward this result was more than three times the present annual yangtze river sediment discharge suggesting that considerable net sediment removal occurs in the coastal regions the sediment transport 0 27 billion tons year is probably the deposition erosion threshold for the east china sea coast north of our study site analysis of historical yangtze river sediment influx records showed that the onset and acceleration of coastal erosion was closely linked with the operation of the three gorges dam tgd upstream of the yangtze river

tidal hydrodynamics and fine grained sediment transport on the radial sand ridge system in the southern yellow sea abstract the large radial sand ridge rsr system located in the southern yellow sea off the jiangsu coast is characterized by a radial current field and high suspended sediment concentrations sscs significant rectilinear currents are present over the northern sand ridge area whereas rotary currents prevail over the southern area the transition between the two being dominated by a locally generated trapped wave observations undertaken in 2006 and 2007 indicate a seasonal pattern in the ssc and associated dynamic characteristics the results of a calibrated hydrodynamic model show that the m2 tide dominates the rsr area the maximum tidal amplitude in the core region close to land being approximately 2 m an amphidromic point is located some distance north of the rsr off the abandoned yellow river mouth 121 686 e 34 6 n specifically the eulerian and lagrangian residual currents flow southward in both summer and winter whereas the stokes drift is directed southward in the north and northward in the south moreover in deep water the lagrangian residual current is mainly determined by the eulerian residual current whereas it is strongly influenced by the stokes drift in shallow water the seasonal variation in the residual current in the southern yellow sea is a good indicator for the location of the yellow sea warm current yswc in both summer and winter measurements show that a ssc peak appears off the abandoned yellow river delta in response to the strong currents and plentiful supply of fine grained sediment from coastal erosion another ssc peak lying close to the north branch of the changjiang river mouth is related to the abundant suspended sediment supplied by the river seasonal variations in ssc are observed in the study area maximum average values and widest diffusion from land occurring in winter this being contrasted by minimum mean values in summer sensitivity experiments demonstrate that the main factor influencing the distribution of ssc is the tide while river discharge wind and wave effects are small and very localized to explain the seasonal variation in ssc the role of hydrodynamics initial conditions and temperature are tested in the model the results show that the hydrodynamics play a significant role whereas the initial conditions only have a minor regional influence temperature on the other hand is also shown to greatly influence the seasonal variation in ssc because of substantial changes in the viscosity of the water and the erosion shear stress the modeled results are used to calculate sediment fluxes which are shown to be consistent with the lagrangian residual current pattern while wind waves can significantly change the fluxes in winter bed elevations change substantially on a monthly time scale in general the deep channels are undergoing erosion while the shallow ridges and coastal tidal flats are accreting the net sediment transport being directed towards the coastal tidal flat and the changjiang yangtze river subaqueous delta

evaluation of luminescence dating procedures applied to late holocene colluvium near st paul s mission natal south africa colluvial deposits provide an interesting challenge for luminescence dating techniques because of the short and varied light exposure histories of the grains prior to deposition results of thermoluminescence tl and infrared stimulated luminescence irsl measurements are presented for two stacked colluvial deposits from natal a radiocarbon date for bulk organic matter in the a horizon of the soil formed within the surface of the lower unit provides a means of assessing the suitability of various luminescence procedures for such material the overlying colluvium contains grains bleached to varying extents as shown by the range of eds for the coarse grain feldspar separate obtained using the single aliquot irsl method for this sample all age estimates either by irsl or tl are too large compared with the radiocarbon age indicating that even the irsl signal was not zeroed in all grains before they were buried the underlying colluvium contains grains bleached more uniformly resulting in a smaller ra

relationships between grain size and organic carbon 14c heterogeneity in continental margin sediments abstract the deposition and long term burial of sedimentary organic matter om on continental margins comprises a fundamental component of the global carbon cycle a key unknown in interpretation of carbon isotope records of sedimentary om is the extent to which om accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes here we present results from an extensive survey of organic carbon oc characteristics of grain size fractions ranging from 14 c values defined here as h 14 to argue that the hydrodynamic processes amplify overall 14c heterogeneity within corresponding bulk sediment samples the magnitude and footprint of this heterogeneity carries implications for our understanding of carbon cycling in shallow marginal seas

dating of quaternary lake sediments from the schirmacher oasis east antarctica by infra red stimulated luminescence irsl detected at the wavelength of 560 nm abstract twelve samples from three antarctic lake cores in the schirmacher oasis east antarctica were selected for dating by a method using infra red stimulated luminescence irsl a spectral study of the luminescence signal from coarse grain plagioclase feldspars by a high sensitivity tl osl spectrometer using a ccd camera showed four wavelength maxima and the comparison of the equivalent doses d e measured at these wavelength namely 280 330 410 and 560 nm yielded different values the ages were calculated using d e obtained at 560 nm

prehistoric ruptures of the gurvan bulag fault gobi altay mongolia 1 the 1957 gobi altay m8 3 earthquake in southern mongolia was associated with the simultaneous rupture of several faults including the gurvan bulag reverse fault which is located about 25 km south of the main strike slip bogd fault our study of paleoseismic excavations across the gurvan bulag fault suggests that the penultimate surface rupture occurred after 6 0 ka most likely between 2 6 and 4 4 ka and a possible earlier rupture occurred after 7 3 ka our interpretation of the stratigraphic relations in one of the exposures suggests that at least five earthquakes have generated surface rupture of the gurvan bulag fault since the abandonment of an ancient alluvial fan surface luminescence dating of sediment associated with this surface indicates that it formed either 26 6 2 1 ka or 16 1 2 0 ka these data imply that the recurrence intervals for surface faulting on the gurvan bulag and bogd faults are similar on the order of several thousands of years but that the penultimate surface ruptures of the two faults did not occur during the same earthquake

optical and radiocarbon dating at jinmium rock shelter in northern australia the jinmium rock shelter is located in the kimberley region of northern australia claims for ancient rock art and an early human presence at this site1 were based on thermoluminescence ages of 50 75 thousand years kyr for quartz sands associated with buried circular engravings pecked cupules and on thermoluminescence ages of 116 176 kyr for the underlying artefact bearing deposits here we report substantially younger optical ages for quartz sand and ages based on measurements of radioactive carbon in charcoal fragments from the occupation deposit using conventional multiple grain optical dating methods we estimate that the base of the deposit is 22 kyr however dating of individual grains shows that some have been buried more recently the single grain optical ages indicate that the jinmium deposit is younger than 10 kyr this result is in agreement with the late holocene ages obtained for the upper two thirds of the deposit from radiocarbon measurements we suggest that some grains have older optical ages because they receivedinsufficient exposure to sunlight before burial the presence of such grains in a sample will cause age overestimates using multiple grain methods whether using thermoluminescence or optical dating

late quaternary earthquake chronology from luminescence dating of colluvial and alluvial deposits of the arava valley israel abstract luminescence ages help provide a time scale for recurrent surface ruptures on a normal fault in the southern arava israel the dated samples come from alluvium and colluvium along a fault scarp north of elat the ages obtained mainly by infrared stimulation of sand size potassium feldspar grains accord with geomorphic age estimates from soils and degraded scarps four large earthquakes occurred between 37 000 and 14 000 yr ago five smaller earthquakes occurred thereafter continuing until recent times the mean recurrence interval for earthquakes of magnitudes greater than 6 is about 4000 yr

thermoluminescence dating of fault scarp derived colluvium deciphering the timing of paleoearthquakes on the weber segment of the wasatch fault zone north central utah the timing of middle to late holocene faulting on the weber segment of the wasatch fault zone utah is constrained by thermoluminescence tl and radiocarbon age estimates on fine grained fault related colluvial sediments the stratigraphy in two trenches excavated across fault scarps is characterized by a stack of three colluvial wedges deposited in response to three separate faulting events the oldest of which buried a soil developed on a middle holocene debris flow thermoluminescence age estimates by the partial and total bleach methods and the regeneration method on fine grained colluvium from the trenches agree within 1 sigma and are concordant with the radiocarbon chronology a synthesis of the tl and 14c age estimates indicate that these three faulting events occurred sometime between 4500 and 3500 between 3200 and 2500 and between 1400 and 1000 years ago detailed investigation of a sequence of fine grained scarp derived distal colluvium shows that much of the sediment was deposited during 600 year intervals immediately after faulting the sedimentation rate of colluvium is inferred to increase shortly after faulting and tl dating of these sediments provides additional information to constrain the timing of faulting events

210pb 137cs and 239 240pu in east china sea sediments sources pathways and budgets of sediments and radionuclides profiles of 210 pb 137 cs and 239 240 pu measured in 83 sediment cores collected from various sedimentary regimes in the east china sea were analyzed to elucidate the sources routes and budgets ofsediments as well as these radionuclides distributions ofsedimentation rates and nuclide inventories reveal alongshore transport ofsediments 137 cs and 239 240 pu from the mouth of the yangtze river toward the south largely confined to the inner shelf area water depth 6 70 m mass balance calculations suggest that the east china sea is a sink for the particle reactive 210 pb and 239 240 pu with about one sixth oftheir sedimentary budgets supplied via boundary scavenging in contrast due to lower affinity of 137 cs for particles and rapid turnover of the shelf water the east china sea serves as a source for 137 cs about two thirds ofthe cumulative input of 137 cs have been transported out ofthe east china sea leaving the remaining one third stored in the bottom sediments and the overlying water column as for the sediment budget mass balance cannot be established due to a shortfall in sediment supply of more than 30 based on a comparison between input terms documented thus far and the sedimentation flux derived from this study it is very likely that we have overestimated the sediment burial flux or that long distance transport from the yellow river s dispersal system to the east china sea is underestimated alternatively the imbalance could be explained by the discrepancy between sediment input and output on decadal to centennial timescales 7 2002 elsevier science b v all rights reserved

holocene slip rate on the sabzevar thrust fault ne iran determined using optically stimulated luminescence osl abstract fault slip rates and the recurrence interval between earthquakes can be determined from reliable dating of deformed sediments we report optically stimulated luminescence osl ages of alluvial gravels fine grained sediments and colluvial deposits associated with the sabzevar thrust fault in northeastern iran six samples of the late quaternary deposits were dated by osl using the single aliquot regenerative dose sar protocol the osl ages indicate deposition of alluvial gravels in the study region between 30 and 9 13 ka followed by a period of fluvial incision which is ongoing at the present day the alluvial deposits have been uplifted by 9 5 m relative to the river level indicating a holocene slip rate of 1 mm yr and a rate of convergence across the fault of 0 4 0 6 mm yr assuming a maximum fault dip of 60 the average interval between large earthquakes on the sabzevar fault will be 3000 years if the fault dips 60 and less if the fault dip is less the last earthquake to destroy sabzevar was in 1052 a d

osl dating of coarse grain fluvial quartz using single aliquot protocols on sediments from ne peloponnese greece abstract optical ages of quartz extracts in holocene sediments from the north eastern peloponnese greece are reported the single aliquot regenerative dose protocol proposed by murray and wintle 2000 radiation measurements 32 57 73 was used to estimate the equivalent dose in these samples a large inter aliquot scatter in d e values was observed for all samples this is ascribed to heterogeneous bleaching of the samples at deposition to estimate a d e for age calculation a technique is suggested based on the analysis of the d e scatter obtained from nine different quartz samples which were artificially bleached and irradiated this procedure is especially useful when the sample quantity is limited the optical age estimates increase with sampling depth an average aggradation rate of 1 5 mm yr is derived using the osl ages this value is consistent with the known uplift rate of 1 2 mm yr

vertical distribution of isoprenoid gdgts in suspended particles from the east china sea shelf and implications for sedimentary tex86h records abstract the t e x 86 h or tex86 paleothermometer has been widely applied for reconstructing water temperature in marine settings particularly in marginal seas which often archive paleoclimate records with high temporal resolution yet debate remains regarding the water depth at which the t e x 86 h signal is imparted in these settings in this study east china sea ecs surface sediments and suspended particulate matter spm from different water depths 0 60 m were analyzed for lipid biomarkers to better constrain the depth to which the sedimentary t e x 86 h signal corresponds our data showed divergent vertical distributions between archaeal lipids and phytoplankton lipids the maximum concentration of core lipid isoprenoid glycerol dialkyl glycerol tetraethers core igdgts appeared in bottom waters 2 5 m above the sea floor at all sites whereas phytoplankton lipids showed highest abundance in surface waters 0 m consistent with the maximum core igdgts concentration in bottom waters the best correlation was observed between spm t e x 86 h values and 2 4 weeks averaged water temperatures from the bottom waters moreover the spm core igdgts content was higher in bottom waters than in surface sediments implying that in situ production rather than sediment resuspension leads to the maximum concentration of core igdgts in bottom waters by compiling published surface sediment data from water depths t e x 86 h with bottom water temperature bwt exceeds that with sea surface temperature sst therefore it is proposed that sedimentary t e x 86 h is a bwt proxy in the shallow ecs

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

infra red stimulated luminescence dating of holocene reworked silty sediments abstract infra red stimulated luminescence irsl ages are reported for holocene colluvial lacustrine and alluvial sediments and late glacial loess for colluvial sediments irsl ages concur with independent ages age overestimation occur in the case of very poorly bleached sediments such as young less than 2000 years floodloams for which a high suspended sediment load was deduced from sedimentation rates and actually observed floods age underestimates are observed for late glacial loess probably due to inadequate preheat procedures

the origin of n alkanes in santa monica basin surface sediment a model based on compound specific δ14c and δ13c data 14c and 13c values were measured for individual long chain n alkanes c24 33 from santa monica basin sediments the data were then simulated using a three component mixing model designed to represent the contributions of different sources the three selected end members were petroleum modern plant wax and shale derived alkanes the model was optimized to fit the data and to determine the fractional contribution of each component the results indicated that petroleum accounted for 12 of the alkanes in 0 2 5 cm sediment and 5 in 2 5 7 5 cm sediment modern plant waxes contributed 80 0 2 5 cm and 87 2 5 7 5 cm and the remaining 8 of each sample was attributed to the shale source the 14c concentration of the modern terrestrial end member was also determined from the model 14c values of 235 for the 0 2 5 cm post bomb horizon and 0 for the 2 5 7 5 cm pre bomb horizon indicate that plant leaf waxes have a continental residence time of decades in the southern california region

an assessment of human versus climatic impacts on holocene soil erosion in ne peloponnese greece soil erosion is a natural geomorphological process which can be triggered by both natural climate tectonics or both and anthropogenic e g agriculture perturbation of the ecosystem evidence has accrued that the holocene climate experienced large fluctuations in amplitude and suggestions of human impact on the ecosystem provided by the neolithic revolution dating back to the early holocene have been made the question of whether man or climate was the dominant factor responsible for holocene soil erosion remains unresolved to resolve the reasons for holocene sediment redistribution high resolution chronometric data on sediments derived from colluvial and alluvial archives from southern greece were obtained and combined with available archaeological and paleoclimatic data from the eastern mediterranean these data show a significant correlation between sedimentation rates and settlement history climatic fluctuations are only weakly correlated with sedimentation history the results show high sedimentation rates during the early neolithic 7th millennium bc in southern greece suggesting that holocene soil erosion was triggered by human activity and then amplified by enhanced precipitation this would explain the high sedimentation rates during the early neolithic in connection with enhanced precipitation in the eastern mediterranean which continued until the mid holocene

an evaluation of thermoluminescence dating of paleoearthquakes on the american fork segment wasatch fault zone utah the accuracy of the thermoluminescence tl method for dating holocene paleoearthquakes was tested on fine grained sediments from three trenches excavated across the american fork segment of the wasatch fault zone utah sediments exposed in the trenches targeted for tl dating include a horizons of buried soils loessial silts and sag pond muds this study indicates that these sediments were fully light bleached prior to deposition and are suitable for tl dating equivalent dose estimates by the regeneration total and partial bleach methods are in general agreement and mean tl age estimates are concordant with radiocarbon ages combined radiocarbon and tl age estimates indicate three major episodes of faulting at 5 3 0 3 2 6 0 3 and 0 5 0 2 kyr ago

optical dating studies of quartz and feldspar sediment extracts abstract continuing developmental work into optical dating has led to some clarification of the optical behaviour of quartz and feldspar sediment extracts we have verified the key assumption intrinsic to the method that the optical signal is zeroed completely upon exposure to daylight we also show that the rate of zeroing in optical dating is much more rapid than it is in tl dating studies concerned with the extraction of the thermally stable signal from laboratory irradiated samples showed that problems may arise from medium to high temperature preheating of young samples optical alternatives to thermal stabilization were tested using dye and krypton lasers using a krypton laser we have succeeded in obtaining an equivalent dose of 0 0 0 7 gy for the quartz from a modern intertidal sand and an average dose of 120 22 gy for the feldspar extract of a 70 ka sand unit both were obtained using six wavelengths from the infrared to the violet and no dependence on wavelength was found we found that the photon energies of infrared and deep red light can stimulate luminescence in unirradiated quartz and feldspar extracts of sediments this was not expected and suggests that the process of trap emptying is more complex than we had envisioned but implies a far greater than expected degree of technical flexibility for the optical dating method

continental record of the southwest monsoon during the last 130 ka evidence from the southern margin of the thar desert india abstract field stratigraphy sedimentology and luminescence dating of the exposed fluvial and aeolian sequences from the southern desert margin were used to discern the pattern of southwest monsoon variability during the last 130 ka the sedimentary architecture and textural attributes of the sediments belonging to the period 130 120 ka suggests the existence of a meandering river system consequent to enhanced southwest monsoon conditions a shift from a meandering to a braided pattern during 120 100 ka indicates a phase of reduced precipitation presence of flood plain fines and bedded calcretes during 100 70 ka suggest a period of enhanced monsoon with seasonality following this a phase of weak monsoon activity was observed during 70 60 ka regional flood plain aggradation and pedogenesis during the period termination of a regional fluvial phase around 30 ka and incision of dunes dated to 20 11 ka suggest that the present rivers occupied their course between 11 ka drowned valleys in the estuarine zones suggest that the incision began during the low sea stand around 20 ka when the rivers were graded to the exposed shelf the incision intensified with the re establishment of monsoon during the early holocene

widespread dispersal and aging of organic carbon in shallow marginal seas the occurrence of pre aged organic carbon oc in continental margin surface sediments is a commonly observed phenomenon yet the nature sources and causes of this aged oc remain largely undetermined for many continental shelf settings here we present the results of an extensive survey of the abundance and radiocarbon content of oc in surface sediments from the northern chinese marginal seas pre aged oc is associated with both coarser 63 m and finer 63 m sedimentary components measurements on specific grain size fractions reveal that it is especially prevalent within the 20 63 m fraction of inner shelf sediments we suggest that organic matter associated with this sortable silt fraction is subject to protracted entrainment in resuspension deposition loops during which it ages is modified and is laterally dispersed most likely via entrainment within benthic nepheloid layers this finding highlights the complex dynamics and predepositional history of organic matter accumulating in continental shelf sediments with implications for our understanding of carbon cycling on continental shelves development of regional carbon budgets and interpretation of sedimentary records

soils as a tool for estimating ages of quaternary fault scarps in a hyperarid environment the southern arava valley the dead sea rift israel abstract on the alluvial fan of nahal shehoret in the extremely arid region of the negev desert israel reg soils developed on stable alluvial surfaces in colluvium along terrace risers and in colluvial units on a complex fault scarp were compared the degree of soil profile development provided an age estimate of the surface that was faulted a maximum age estimate of the scarp or terrace riser and an estimate of the maximum recurrence intervals of faulting events irsl dates of the tectonically displaced alluvial surfaces and colluvial units at the same site enabled us to re evaluate the use of reg soils for relative dating the major faulting event started at 34 8 4 3 ka it displaced a late pleistocene surface of the nahal shehoret alluvial fan dated at 56 10 8 ka renewed fluvial activity and deposition of alluvium on the downfaulted block had almost terminated by 13 6 2 3 ka the scarp was formed during the latest pleistocene and was followed by smaller faulting events which had only minor effects on the fault scarp morphology the similarity of age estimates from irsl dating and the degree of soil development in this environment indicates that soils can be used to date surfaces and colluvial units

across shelf sediment transport interactions between suspended sediment and bed sediment 1 we use a two dimensional time dependent sediment transport model to quantify across shelf transport deposition and sorting during wave driven resuspension events characteristic of those that dominate sediment transport on many continental shelves decreases in wave orbital velocities as water depth increases and the resulting cross shelf gradient in bed shear stress favor a net offshore transport of sediment on wide flat shelves slopes 0 1 percnt these gradients are low and the depth to which the seabed is reworked depends mainly on bottom shear stress and local sediment availability on narrow steep shelves slopes 0 5 percnt however the gradient in bottom stress generates significant cross shelf suspended sediment flux gradients that create regions of net erosion and deposition while the magnitude of waves generally determines the water depth to which sediment can be resuspended erosional and depositional patterns on narrow shelves are sensitive to cross shelf gradients in wave energy nonlocal sediment availability and the direction and magnitude of the cross shelf current during energetic waves cross shelf divergence of suspended sediment flux can create a coarsened erosional area on the inner shelf that abuts a region of fine grained sediment deposition on the mid to outer shelf if currents are strongly shoreward however flux divergence leads to erosion over the entire shelf

changes in holocene paleoseismic activity in the hula pull apart basin dead sea rift northern israel abstract paleoseismic analysis of the azaz fault segment of the dead sea fault northern israel indicates that this region was subjected to intermittent periods of strong seismicity and quiescence during the latest pleistocene and the holocene the azaz fault forms the eastern margin of the hula valley a pull apart basin between two left stepping segments of the dead sea fault the fault is currently inactive but it displaces a 25 30 ka travertine in the northeastern corner of the hula valley and near surface marsh sediments inside the valley two trenches excavated across a 15 20 m high fault scarp near kefar szold expose fluvial and colluvial sequences showing clear evidence of recent tectonics one trench exposes well sorted bedded alluvial sediments comprising two upward fining units each capped by a weakly developed paleosol the sediments were deposited on the down faulted block and are bounded in the east by the fault scarp the second trench uncovers fine colluvial sediments cross cut by a wide fault parallel fissure filled by collapsed sediments in both trenches the lower sedimentary unit is capped by a coarse colluvium containing boulders up to 1 5 m in size the colluvium shows no clear bedding and has a weakly developed paleosol on top optically stimulated luminescence dating of the lower fluvial sequence shows that its age ranges between 12 ka at the base to 6 ka at the top while the middle part of the overlying colluvium is ca 4 8 ka the relation between the lower fluvial units and the fault indicates that at least two large scale earthquakes occurred in the early holocene each one resulting in a 1 1 5 m high fault scarp during this seismically active period no coarse colluvial sediments were deposited along the fault trace and thus the region must have had low tectonic relief the clear contact with the overlying coarse colluvium reflects a middle holocene rapid change to the present high steep relief this change was achieved by frequent strong seismic events which triggered colluvial processes and prevented stratification and soil formation on the slope the soil on the present slope reflects a quiescent period that has lasted at least several hundred years during which stress has accumulated and seismic risk increased

episodic late quaternary slopewash deposition as recorded in colluvial aprons southeastern wyoming abstract colluvial aprons found along fluvial terraces of the laramie river and sybille creek in southeastern wyoming are interpreted as late quaternary slopewash deposits each apron studied contained multiple buried soils interpreted to indicate that slopewash activity was episodic and short lived and was followed by relatively long periods of landscape stability and soil development apron deposits were described and subsequently correlated based on their internal stratigraphy and their relative degree of soil development optical dating was used to chronologically constrain periods of slopewash deposition and based on 17 optical ages taken from five aprons aggradation occurred at 65 56 16 0 12 9 11 8 8 1 7 3 5 0 and 1 7 ka several of these events correspond with climatic transitions such as the termination of heinrich event 1 the onset and termination of the younger dryas and the 8 2 ka event suggesting that apron aggradation was driven by changes in climatic regime although either increased aridity or a change in precipitation regime could result in increased erosion of terrace scarps apron aggradation events do not correlate with regional records of aridity instead periods of increased precipitation intensity and or frequency that occur during climatic transitions most likely drive apron aggradation events

test of thermoluminescence dating of buried soils from mt kenya kenya we have applied the partial bleach r gamma thermoluminescence tl dating method to four organic rich ab horizons of buried soils from mount kenya our objective was to test the feasibility of directly measuring the time of last exposure to sunlight of the fine grained silicate minerals within these horizons the resulting apparent ages for three samples of 1 2 0 3 6 2 and 10 2 ka 1 std dev are in general agreement with associated 14c age estimates from buried whole soil paleosol samples the fourth sample of an age though unknown presumed to lie beyond the 14c dating limit yielded a tl age estimate of 60 20 ka notwithstanding some limitations these results are encouraging and imply that with simple refinements this tl method is capable of directly dating accurately such buried soils probably to well beyond the 40 ka 14c dating limit

geomorphological investigations and luminescence dating in the southern part of the khangay and the valley of the gobi lakes central mongolia geomorphological investigations in the catchment area of the baydragiyn river along the southern slope of the khangay and in the valley of the gobi lakes in western mongolia provide evidence for late quaternary glaciations and lake level changes thermoluminescence tl and infrared optically stimulated luminescence irsl dating of aeolian and colluvial sediments from the central khangay place the sediments that overlie fluvial and glaciofluvial terraces in the holocene an age of 21 ka is determined for a sand deposit overlying the terrace that is related to the last glacial ice margin lacustrine sediments from higher beach lines in the valley of the gobi lakes provide evidence for a slightly more humid period around 1 5 ka and a larger extent of the lakes in the early holocene at about 8 5 ka as also reported from other parts of central asia remnants of lacustrine sediments buried by alluvial gravel and indicating a huge palaeolake in the basin of the orog nuur however date to the early stage of the last glaciation around 70 ka copyright 2001 john wiley sons ltd

the isotopic composition of particulate organic carbon in mountain rivers of taiwan small rivers draining mountain islands are important in the transfer of terrestrial particulate organic carbon poc to the oceans this input has implications for the geochemical stratigraphic record we have investigated the stable isotopic composition of poc 13corg in rivers draining the mountains of taiwan in 15 rivers the suspended load has a mean 13corg that ranges from 28 1 0 8 to 22 0 0 2 on average 37 samples per river over the interval of our study to investigate this variability we have supplemented suspended load data with measurements of poc in bedrock and river bed materials and constraints on the composition of the terrestrial biomass fossil poc in bedrock has a range in 13corg from 25 4 1 5 to 19 7 2 3 between the major geological formations using coupled 13corg and n c we have found evidence in the suspended load for mixing of fossil poc with non fossil poc from the biosphere in two rivers outside the taiwan central range anthropogenic land use appears to influence 13corg resulting in more variable and lower values than elsewhere in all other catchments we have found that 5 variability in 13corg is not controlled by the variable composition of the biomass but instead by heterogeneous fossil poc in order to quantify the fraction of suspended load poc derived from non fossil sources fnf as well as the isotopic composition of fossil poc 13cfossil carried by rivers we adapt an end member mixing model river suspended sediments and bed sediments indicate that mixing of fossil poc results in a negative trend between n c and 13corg that is distinct from the addition of non fossil poc collapsing multiple fossil poc end members onto a single mixing trend as an independent test of the model fnf reproduces the fraction modern fmod in our samples determined from 14c measurements to within 0 09 at the 95 confidence level over the sampling period the mean fnf of suspended load poc was low 0 29 0 02 n 459 in agreement with observations from other mountain rivers where physical erosion rates are high and fossil poc enters river channels the mean 13cfossil in suspended poc varied between 25 2 0 5 and 20 2 0 6 from catchment to catchment this variability is primarily controlled by the distribution of the major geological formations it also covers entirely the range of 13corg found in marine sediments which is commonly thought to derive from mixing between marine and terrigenous poc if land sourced poc is preserved in marine sediments then changes in the bulk 13corg observed offshore taiwan could instead be explained by changes in the onshore provenance of sediment the range in 13corg of fossil organic matter in sedimentary rocks exposed at the surface is large and given the importance of these rocks as a source of clastic sediment to the oceans care should be taken in accounting for fossil poc in marine deposits supplied by active mountain belts

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

sediment transport off the huanghe yellow river delta and in the adjacent bohai sea in winter and seasonal comparison abstract based on the data on the current velocity water temperature salinity turbidity and concentration of suspended sediment collected in november 2006 along three survey transects at three time series ship based stations off the huanghe yellow river delta and at twenty four grid survey stations in the adjacent bohai sea sediment transport off the huanghe delta and in the adjacent bohai sea under winter regime were studied and compared with those from the summer season the homogeneous distribution of salinity temperature and sediment in the water column indicated a well mixed body of water a zone of high suspended sediment concentrations ssc 100 mg l 1 with a width of 35 km was identified along the delta coast two highest ssc centers were found in the surface and middle water layers around the abandoned diaokou huanghe river mouth and the present huanghe river mouth and the third one in the bottom layer around the abandoned qingshuigou huanghe river mouth these three highest ssc centers become major sediment source areas in winter based on the location of the high bottom shear stress zone the prevailing wave directions and the protuberant topography of the river mouths we identified the resuspension origin of the three highest ssc centers caused mostly by the winter storm waves partially by tidal currents suspended sediment flux ssf along the three coastal transects indicated that the sediment in the northwest part of the delta was transported northeastward and southeastward along the coast of the recent delta lobe the ssc and ssf were higher in winter than summer by 1 7 27 1 and 2 122 5 times respectively except around the present river mouth this indicates that the intensity of sediment transport in winter is much stronger than in summer due to the powerful effect of winter storms although the river water and sediment discharges to the sea were much greater in summer the massive huanghe sediment to the sea was accumulated in a narrow coastal area due to weak hydrodynamics in summer and then strongly resuspended mostly by storm waves in winter and transported to the offshore area the coastal area off the huanghe delta acts as a sediment sink in summer and converted to be a sediment source in winter in response to the seasonal variation of the east asian monsoon in this region the erosion accumulation pattern of the huanghe subaqueous delta from 1976 to 2003 illustrates that river laden sediment is deposited mainly in the southern part off the coastal area and it is also the result of intensive southward sediment transport in winter

preliminary study of the dynamic origin of the distribution pattern of bottom sediments on the continental shelves of the bohai sea yellow sea and east china sea the bottom sediment types in the bohai sea yellow sea and east china sea byecs are diversified and their distribution pattern is very complicated however the bottom sediment types can be simplified to be sandy sediment clayey sediment and mixed sediment which comprise the complicated distribution pattern of bottom sediment in the byecs the continental shelves of the byecs are broad with shallow water depths and tidal currents which are permanent and dominate the marine dynamics in the byecs based on numerical simulation of tidal elevations and currents in the byecs the rates of suspended load transport and bed load transport during a single tidal cycle for sediments of eight different grain size ranges are calculated the results show that any sediment whose threshold velocity is less than that of tidal current has the same transport trend suspended load transport rare bed load transport rate and the ratio of the former to the latter decrease with grain size becoming coarser and coarser the erosion accretion patterns of sediments with different grain sizes are determined by the sediment transport rate divergences and the results show that the patterns are the same for sediments with different grain sizes three main bottom sediment types i e sandy sediment mainly composed of fine sand clayey sediment mainly composed of silty clay and mixed sediment mainly composed of fine sand silt and clay are obtained by computation the three bottom sediment types and their distribution pattern are consistent not only with sediment transport field and the sea bed erosion accretion pattern obtained by simulation but also with field data of bottom sediment types and divisions in the byecs sand ridges form mainly in the areas with strong rectilinear tidal currents sand sheets form mainly in the areas dominated by strong rotatory tidal currents and clayey sediments i e mud patches form mainly in the areas with weak tidal currents hence not only the sandy sediments but also the clayey sediments in the byecs are formed under the control of the whole tidal current field of the byecs the three main bottom sediment types are not isolated respectively in fact they constitute a whole tidal depositional system under the condition with no cyclonic cold eddy the clayey sediments in the byecs can form in weak tidal current environments therefore a cold eddy is not necessary for the deposition of clayey sediments in the byecs c 2000 academic press

tidal deposition systems of china s continental shelf with special reference to the eastern bohai sea abstract the continental shelf of china has undergone a large scale marine transgression tidal currents have become the main active agent and have had a profound influence on the deposition and geomorphology of the shelf the continental shelf of china has five modern tidal deposition systems 1 the eastern part of the yellow sea 2 the eastern part of the bohai sea 3 off the mouth of yangtze river 4 to the west of taiwan and 5 the strait of qiongzhou when the tidal current speed is above 150 cm s erosion dominates and reciprocating currents form deep scour furrows when the tidal current speed is 50 to 150 cm s deposition is dominant and tidal currents form tidal shoals i e tidal sand ridges and tidal sand sheets whose margins are near an absolute ellipticity value for the m2 tidal component of 0 4 when the absolute m2 value is less than 0 4 a reciprocating current is strong enough to form tidal sand ridges when the absolute value is above 0 4 a rotating current increases so as to form a tidal sand sheet tidal deposition material came mainly from tidal erosion and locally redeposition of late pleistocene sediments and from the neighbouring sea bottom the tidal deposition system in the eastern bohai sea is a typical example it consists of the laotieshan channel scour furrow the liaodong shoal sand ridges and the bozhong shoal sand sheet the maximum tidal current speed in the laotieshan channel where strong erosion occurs is up to 250 cm s in the liaodong shoal the maximum tidal current speed is 64 115 cm s and the absolute ellipticity value of the m2 tidal component is less than 0 4 in the bozhong shoal the maximum tidal speed is 58 79 cm s and the absolute ellipticity value of the m2 tidal component is above 0 4 the small scale bedforms surveyed in detail in the area show that the sand ridges and sand sheet are still under the action of tidal current processes at the present time based on the interpretation of tidal currents bedforms and sediment thickness it is inferred that the general direction of sediment transport within the study area is nnw from the laotieshan channel to the liaodong and bozhong shoals the small scale bedforms in the detailed survey area indicate a local net sediment transport from south to north

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

pre aged soil organic carbon as a major component of the yellow river suspended load regional significance and global relevance abstract large rivers connect the continents and the oceans and corresponding material fluxes have a global impact on marine biogeochemistry the yellow river transports vast quantities of suspended sediments to the ocean yet the nature of the particulate organic carbon poc carried by this system is not well known the focus of this study is to characterize the sources composition and age of suspended poc collected near the terminus of this river system focusing on the abundance and carbon isotopic composition 13c and 14c of specific biomarkers the concentrations of vascular plant wax lipids long chain c24 n alkanes n fatty acids and poc co varied with total suspended solid tss concentrations indicating that both were controlled by the overall terrestrial sediment flux poc exhibited relatively uniform 13c values 23 8 to 24 2 and old radiocarbon ages 4000 4640 yr however different biomarkers exhibited a wide range of 14c ages short chain c16 c18 fatty acid 14c ages were variable but generally the youngest organic components from 502 yr to modern suggesting they reflect recently biosynthesized material lignin phenol 14c ages were also variable and relatively young 1070 yr to modern suggesting rapid export of carbon from terrestrial primary production in contrast long chain plant wax lipids display relatively uniform and significantly older 14c ages 1500 1800 yr likely reflecting inputs of pre aged mineral associated soil oc from the yellow river drainage basin even carbon numbered n alkanes yielded the oldest 14c ages up to 26 000 yr revealing the presence of fossil petrogenic oc two isotopic mass balance approaches were explored to quantitively apportion different oc sources in yellow river suspended sediments results indicate that the dominant component of poc 53 57 is substantially pre aged 1510 1770 yr and likely sourced from the extensive loess paleosol deposits outcropping within the drainage basin of the remaining poc between 10 and 31 is fossil in origin 26 000 yr resulting from the physical erosion of ancient sedimentary rock and input of fossil fuel residues from anthropogenic activity and 16 33 is modern carbon derived from terrestrial and aquatic productivity these findings have implications both regarding the provenance and vintage of organic matter signatures emanating from the yellow river basin and similar catchments containing extensive paleosol sequences as well as for the reactivity and fate of this poc upon supply to adjacent marginal seas

spatial temporal evolution of slow slip movements triggered by the 2016 mw 7 8 kaikoura earthquake new zealand abstract the 2016 mw 7 8 kaikoura earthquake involved complex rupture across multiple faults and triggered large scale slow slip movements on the hikurangi subduction zone the complex seismically triggered slow slip events sses contribute to the understanding of triggering mechanisms of sses in new zealand here we invert the continuous global positioning system cgps observations to investigate the temporal evolution of the seismically triggered slow slip behaviour on the hikurangi subduction interface similar to previous studies our optimal geodetic inversion model reproduces deep 30 50 km marlborough afterslip of over 60 cm deep kapiti slow slip of up to 31 cm and shallow 10 cm east coast slow slip on the hikurangi subduction interface the slow accumulated seismic moment over the past eight months from the large scale slow slip motion is 3 12 1020 nm which is equivalent to a magnitude 7 6 earthquake both the marlborough afterslip and kapiti slow slip were considerably active during the first week after the mainshock and gradually slowed down in the following months these deep ongoing fault motions may continue for at least several months and are expected to decay logarithmically with time in agreement with previous studies the east coast slow slip motion occurred rapidly within 2 3 weeks which stretched from the central to northern hikurangi subduction margin the coseismic coulomb failure stress change investigation suggests that large scale stress increase over 1 2 mpa appears on the southern hikurangi subduction interface which encourages afterslip underlying the marlborough fault system and slow slip beneath the kapiti coast consistent with previous studies the long distance slow slip motion offshore the east coast was likely dynamically triggered by the kaikoura earthquake where the static coulomb stress increase is insignificant

loessic silt deposits in the western himalayas their sedimentology genesis and age abstract loess is abundant in the foreland basins of the himalayas however it is poorly developed within the intermontane basins of the western himalayas and karaloram selected sections were studied from the swat himalaya and the karakoram mountains fieldwork and sedimentological analysis including grain size mineralogy and microfabric showed that the loessic sediments have been reworked and some have undergone weak pedogeneses these silts are not true loess rather a loessic colluvium thermoluminescence tl dates from the loessic sediments in sections from the swat valley provided younger ages than earlier workers had suggested this is consistent with reworking of the loess in these areas it is concluded that care must be taken when using loessic silts for tl in similar mountainous terranes

reconstruction of late holocene slope and dry valley sediment dynamics in a belgian loess environment to unravel the evolution of a dry valley in the belgian loess area soils and sediments along a slope catena were studied in detail a 67 m long trench was opened from the upper slope to the centre of the valley bottom the exposed soils and sediments showed evidence of severe soil erosion and other human disturbances that significantly changed the valley topography the early holocene slope gradient was up to 25 whereas now it is less than 10 in the thalweg a remnant of the early holocene soil was found underneath colluvial deposits which were more than 3 m thick a chronology for the valley evolution was established based on ams 14c dating of charcoal fragments and optical dating of colluvial sediments the first sediment deposition occurred in the early iron age with an average sedimentation rate of approximately 3 4 1 3 t ha per yr this increased to c 5 4 2 2 t ha per yr during the roman period and further to 18 0 2 2 t ha per yr in the middle ages although sediment accumulation in the

the potential of using thermoluminescence to date buried soils developed on colluvial and fluvial sediments from utah and colorado u s a preliminary results the natural tl intensity for surface and buried holocene and pleistocene a horizons developed on flood plain silts near denver colorado exponentially decreases with time this signal is approaching saturation by ca 130 ka the a horizon of the modern flood plain soil is not fully light bleached the tl properties and age estimates are presented for radiocarbon dated eolian enriched buried a horizons developed on fault derived colluvium from the american fork segment of the wasatch fault zone utah dating of these buried soils provide a close age estimate on paleoearthquake events mean tl age estimates by regeneration and total bleach techniques for buried a horizons are 0 5 0 1 ka and 2 7 0 4 ka which are in agreement with corresponding radiocarbon dates of 980 70 years bp and 2620 70 years bp a surface sag pond mud formed within an antithetic grabben is well light bleached and yielded a tl age estimate by the total bleach method of 240 60 years bp in agreement with its known age of 300 years bp this study indicates that relatively brief periods of pedogenesis are not sufficient to light bleach sediment and that eolian additions enhance the reduction of tl in soils

mobile mud dynamics in the east china sea elucidated using 210pb 137cs 7be and 234th as tracers mobile mud mm which has fine grain size distribution 90 clay silt and 2 5 in south inshore indicates that the sediment focusing resulted in the increased mass flux the residence time of mm is estimated as 3 6 years both by mass balance of mm and 210pbex in mm

luminescence dating of hillslope deposits a review abstract luminescence dating determines the last exposure to light of quartz and feldspar mineral grains and thus the time a sediment was laid down prerequisite is that the sediment grains were sufficiently exposed to light prior to deposition for eolian deposits this seems a fair assumption although exceptions may well exist for other depositional environments light exposure prior to burial is often restricted in duration intensity and spectral composition and may result in an age overestimation recent developments now allow dating of sediments that were exposed to only little light prior to deposition the main developments are single aliquot techniques and statistical tests that allow extraction of valid age estimates even from deposits in which bleached and unbleached grains are mixed these developments in combination with the fact that the great majority of sediments near the earth s surface are not of eolian origin have resulted in the large interest in the luminescence dating of non eolian deposits here we review possibilities and challenges of luminescence dating of colluvial deposits we summarize techniques for the detection and handling of insufficiently bleached sediments a common condition in colluvial deposits we give an overview how luminescence dating has been applied on hillslope sediments for reconstructing landscape response to climate change to analyze past fault activity and unravel human induced soil erosion we discuss sampling strategies and give guidelines as to which techniques are best suited to establish luminescence chronologies for colluvium

sediment accumulation and budget in the bohai sea yellow sea and east china sea abstract sediment accumulation and budget in the continental margins provides abundant information of source sink processes from the land to the sea including weathering human activities and sedimentary environment here we show the distribution of mud areas modern sedimentation rates and sediment budget in the bohai sea yellow sea and east china sea using grain size data of 18 000 surface sediment samples and 210 pb data from 413 sites we identify five areas with sediments mainly composed of fine grained fractions mean grain size 6 and find a relatively high sedimentation rates of 1 5 mm yr in the mud areas near the yellow and yangtze river deltas sedimentation reaches 95 0 mm yr approximately 1185 4 10 6 tons of fine grained sediment accumulate annually in the mud areas of the east china seas atmospheric deposition contributes 6 tons yr while the riverine sediment inputs account for 75 917 10 6 tons yr the remainder comes from all other sources including coastal erosion and resuspension of bottom sediments in addition 45 of the fluvial sediment supply deposits on the subaerial delta 40 50 is trapped on the subaqueous delta and shelf and the remainder

diagenetic and sedimentological controls on the composition of organic matter preserved in california borderland basin sediments compound specific radiocarbon 14c contents stable carbon isotopes and abundances of phytoplankton and vascular plant derived lipid biomarkers alkenones and fatty acids were obtained from santa barbara basin and santa monica basin sediments along with radiocarbon contents of planktic foraminifera and total organic carbon we investigated core top and prebomb sediment intervals at sites from the flanks and depocenters of the basins deposited under contrasting bottom water oxygen concentrations bulk organic matter generally has the lowest radiocarbon levels of all sediment constituents measured whereas planktic foraminifera tend to be the most radiocarbon enriched alkenones are systematically depleted in radiocarbon with respect to foraminifera short chain c14 c 16 c 18 fatty acids decrease rapidly in absolute abundance and relative to longer chain c24 homologues from core top to prebomb samples the loss of short chain fatty acids with depth is associated with 13c depletion of short chain fatty acids indicating preferential preservation of terrestrially derived fatty acids short chain fatty acids tend to be more 14c enriched relative to alkenones in core top sediments whereas longerchain homologues are generally the most radiocarbon depleted of the lipids studied here less refractory compounds e g short chain fatty acids are thus enriched in radiocarbon with respect to more recalcitrant biomarkers alkenones long chain fatty acids the lower 14c content of more refractory compounds reflects a larger proportion of laterally supplied preaged material greater preservation of labile organic compounds observed at the depocenters than in flank sediments results in the presence of younger biomarkers underlining the important influence of selective degradation of labile compounds on their radiocarbon ages

luminescence dating of quaternary sediments recent advances duller geoffrey 2004 luminescence dating of quaternary sediments recent advances journal of quaternary science 19 2 pp 183 192 rae2008

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples

radiocarbon and 230th data reveal rapid redistribution and temporal changes in sediment focussing at a north atlantic drift abstract in locations of rapid sediment accumulation receiving substantial amounts of laterally transported material the timescales of transport and accurate quantification of the transported material are at the focus of intense research here we present radiocarbon data obtained on co occurring planktic foraminifera marine haptophyte biomarkers alkenones and total organic carbon toc coupled with excess thorium 230 230thxs measurements on four sediment cores retrieved in 1649 2879 m water depth from two such high accumulation drift deposits in the northeast atlantic bjorn and gardar drifts while 230thxs inventories imply strong sediment focussing no age offsets are observed between planktic foraminifera and alkenones suggesting that redistribution of sediments is rapid and occurs soon after formation of marine organic matter or that transported material contains negligible amounts of alkenones an isotopic mass balance calculation based on radiocarbon concentrations of co occurring sediment components leads us to estimate that transported sediment components contain up to 12 of fossil organic matter that is free of or very poor in alkenones but nevertheless appears to consist of a mixture of fresh and eroded fossil material considering all available constraints to characterize transported material our results show that although focussing factors calculated from bulk sediment 230thxs inventories may allow useful approximations of bulk redeposition they do not provide a unique estimate of the amount of each laterally transported sediment component furthermore our findings provide evidence that the occurrence of lateral sediment redistribution alone does not always hinder the use of multiple proxies but that individual sediment fractions are affected to variable extents by sediment focussing

the history of holocene soil erosion in the phlious basin ne peloponnese greece based on optical dating anthropogenic induced soil erosion has occurred in the mediterranean during historic and pre historic times but precise timeframes for periods of past soil erosion are largely missing due to the lack of datable material and suitable dating methods in this study optical dating of colluvial sediments from the phlious basin ne peloponnese greece was applied the results show that soil erosion derived colluvium formed under a mediterranean type climate can be successfully dated by optical stimulated luminescence osl and a high resolution chronology of holocene soil erosion could be established colluvial formation occurred in the early holocene but increased distinctly in the seventh millennium parallel with the onset of the neolithic the start of farming activities other periods of strong colluviation are the middle and late bronze age second millennium the roman period first century to sixth century and the period since the sixteenth century rates of reduced colluviation occurred during