an improved method of sediment grain size trend analysis in the xiaoqinghe estuary southwestern laizhou bay china although deltas evolve with a regular cycle of growth and abandonment over centuries knowledge of these cycles and their effects is important given the fact that humans tend to locate near these areas this study examines sediment transport patterns in the xiaoqinghe estuary in southwestern laizhou bay china in order to identify the factors controlling the sedimentary environment in the estuary sediment samples collected from the bed of laizhou bay in 2007 were analyzed using the gao collins 2 d grain size pattern analysis method and two polymodal distribution functions the study identified three grain size subgroups 4 6 16 and 27 115 mu m and mapped the distribution of the relative percentage of the three components and the mean size distribution within each component the sediment transport trends for the three components were derived by a mathematical partitioning process generally the finest grains move from the local river mouths seaward in the north and south directions with a large anomaly suggesting input into the study area from the more distant huanghe river in the north in addition fine grained sediment is transported by marine hydrodynamic forces from the shallow sea areas toward the coast the medium sized grains move toward the river mouths settling over oyster beds and sandbars that create high turbulence zones while the fine silt grains move seaward in northerly and southerly directions the coarser grains tend to flow toward the coast brought in by seaward migration with some coarse material moving off the river mouths

accommodation and sediment supply controls on clastic parasequences a meta analysis this study combines data from many published case studies to undertake a quantitative characterization of clastic parasequences with the aim to determine how accommodation sediment supply and autogenic sediment storage dynamics are recorded in their sedimentary architecture and stacking patterns results of this study are used to critically evaluate the validity of paradigms and models that are routinely used to explain and predict trends in the anatomy and arrangement of parasequences data on 957 parasequences from 62 case studies of clastic shallow water successions were coded in a relational database which includes outcrop and subsurface datasets of ancient and quaternary examples these units cover the preserved records of both river dominated deltas and wave dominated coasts representing shoreline transits over a breadth of timescales likely of both local and regional extent the role of extant accommodation rates of creation of accommodation and rates of sediment supply in determining parasequence architecture is assessed through analysis of relationships between i proxies of these variables at different scales rates of aggradation and progradation facies belt shoreline trajectories systems tract type parasequence set stacking patterns parasequence progradation angle and stratigraphic rise size of feeder rivers and ii parameters that describe the geometry and stacking style of parasequences and associated shallow water sand bodies statistical analyses of database outputs indicate which proxies of accommodation sediment supply and accommodation sediment supply ratio are significant as predictors of parasequence architecture and allow for interpretations of the importance of allogenic and autogenic factors the principal results of this study reveal the following i parasequence thickness varies as a function of water depth accommodation generation and erosional truncation and these variations are also reflected across types of systems tracts and parasequence sets ii the dip length of parasequence sand bodies demonstrates scaling with measures of accommodation sediment supply ratio at multiple scales partly in relation to the possible effect of sediment supply on progradation rates iii in systems tracts stratigraphic trends in parasequence stacking due to autogenic mechanisms or to acceleration or deceleration in relative sea level fluctuations are not revealed quantitatively iv some association is seen between the abundance of deltaic or river dominated parasequences and progradational stacking v positive but modest correlation is observed between measures of river system size and the dip length of shallow marine parasequence sand bodies the resulting insights can be applied to guide sequence stratigraphic interpretations of the rock record and the characterization of sub seismic stratigraphic architectures of subsurface successions

holocene coastal morphologies and shoreline reconstruction for the southwestern coast of the bohai sea china abstract ground penetrating radar gpr reflection profiles were interpreted and combined with sedimentological data to highlight the morpho evolutionary history of the southwestern sector of the bohai sea the internal structures in gpr images obtained near the holocene maximum transgression boundary revealed concave upward and onlap types of transgressive paleo topography the relationship between historical courses of the yellow river and the distribution of shell ridges at three periods 6 ka 2 ka and recent times showed that the concave upward types derived from the marine sediments overlap the fluvial sediments and the onlap types from the marine sediments cover the coastal lagoon sediments based on the above paleo geographical setting previous sea level markers were corrected taking into account uncertainties of their relationship to former water levels the rates of vertical tectonic displacement evaluated through comparison of the relative sea level rsl data from the gpr images and the holocene predicted sea level elevation markedly affected rsl changes the fitted rsl curves from the corrected sea level indicators showed that the accuracy of former sea level determinations can be improved by comparing with the maximum transgressive position of gpr detection a topographic digital elevation model dem for 6 ka is reconstructed based on the corrected data

provenance and climate change inferred from sr nd pb isotopes of late quaternary sediments in the huanghe yellow river delta china we present a provenance study of core zk2 from the huanghe yellow river delta in order to assess the impacts of climate change on the sediment supplies during the last glacial interglacial cycle facies analysis and sequence stratigraphy methods are used to construct the age model sr isotopic compositions of zk2 range from 0 716389 to 0 723884 with 87sr 86sr increased with decreasing grain size nd and pb isotopic compositions display two large major excursions during marine oxygen isotope stages mis 2 and 4 with less radiogenic end and lower 208pb 204pb 207pb 204pb and 206pb 204pb values during these periods these excursions have been explained in terms of changes in the mixing proportion of sediments from the loess plateau and ordos plateau resulting from east asian monsoon intensity variations the weak summer monsoon precipitation resulted in decreased erosion of loess plateau during mis 2 4 and the middle of mis 3 meanwhile both the intensified east asian winter monsoon and the southward expansions of mu us desert significantly enhanced the eolian sand entering the huanghe therefore our results highlight the impact of monsoon variability on erosion patterns in the huanghe basin

seismic stratigraphy and morphology of the holocene progradational system beneath bohai bay bohai sea lobate evolution of a multi sourced subaqueous fluviodeltaic complex abstract since 6 kyr bp the subaerial deltas of the yellow the yanshan and the taihang river systems evolved along the bohai bay coast forming several lobate progradational systems associated with frequent avulsions of these river systems their subaqueous parts consist of a multi sourced subaqueous deltaic complex in bohai bay but little is known about the complex s subsurface structure morphology and evolutionary history here we investigate these characteristics using a dense high resolution seismic survey using stratigraphic superposition seismic geometry and the results of previous studies we identified nine seismic units sus in the post last glacial maximum stratigraphy which are interpreted from bottom to top as 1 fluvial lacustrine sediments su0 2 marine sands combined with estuarine coastal deposits su1 and 3 a subaqueous fluviodeltaic complex sus2 8 these units correspond to the lowstand system tract the transgressive and or highstand system tracts and the normal regressive system tract respectively and evolved as a function of eustatic fluctuations the subaqueous fluviodeltaic complex is characterized by a discrete and spatially confined lobate architecture which is indicative of step wise switching of subaqueous lobes two sets of progradational systems ps a northern one sus2 3 and a southern one sus4 8 were observed within the complex tapering in opposite directions and bounded by an erosional unconformity r3 these characteristics indicate that the two ps were sourced from different river systems and prograded at different times r3 forms the base of the southern ps but cross cuts the northern ps indicating that it is a diachronous surface marks the preexisting seafloor which was further reworked eroded by the progradation of the southern ps in each ps the internal subaqueous lobes correlated well with the onshore lobes superlobes of the subaerial deltas suggesting the lobate evolution of the complex is driven predominantly by alternating erosion and deposition caused by the variation in fluvial supply which appears to be linked to the frequent avulsions of the major river systems in addition to the multi sourced supply based on the dipping geometries and the locations of the depocenters we hypothesize that 1 the northern ps is the seaward extension of the ancient haihe river s northern branch 2 the bulk of southern ps in the middle and southern bohai bay is correlated with the principal body of the yellow river subaqueous delta 3 the majority of the volume of the northern ps in northern bohai bay consists of the modern haihe river subaqueous delta

decadal scale riverbed deformation and sand budget of the last 500 km of the mississippi river insights into natural and river engineering effects on a large alluvial river

observed cross shelf suspended sediment flux in the southern yellow sea in winter abstract the cross shelf circulation and its transport in the yellow and east china seas yecss are very important to global ocean material exchanges and regional environment a field survey including a long term mooring 89 sample stations 25 drifters etc was conducted in the yecss in the winter of 2015 to investigate the cross shelf transport of the sediment plume over the changjiang bank the observation shows that the northern east china sea ecs current carries low temperature low salinity and high turbidity coastal waters southeastward from the radial tidal sand ridge off the jiangsu coast to the outer shelf south of cheju island the northern ecs current with an average speed of 4 7 cm s and in the average direction of 100 from due north is not only measured directly by the 21 day mooring but also recorded in trajectories of 6 satellite tracked surface drifters the mean current of the northern ecs current flows roughly along the 30 50 m isobaths with a small cross isobath component the mooring data indicate that the sediment flux is dominated by the mean advection of mean sediment concentration resulting in an average suspended sediment flux of 52 23 g s 1 m 1 in the direction of 105 according to the suspended sediment flux decomposition the flux due to tidal currents is calculated to be one order of magnitude smaller than the advection by subtidal currents implying that the sediment plume is unlikely generated by the tidal pumping but is likely maintained by the advection the amount of the suspended sediments carried by the northern ecs current is estimated to reach 40 62 million tons assuming an average width of 100 km of the turbid plume during december through february the transport by the northern ecs current is suggested to provide sufficient amount of sediments for the southwestern cheju island mud to grow in time

transgressive wave and tide dominated barrier lagoon system and sea level rise since 8 2 ka recorded in sediments in northern bohai bay china abstract two sediment boreholes dq3 and dq4 were drilled in northern bohai bay to investigate the genetic type and sedimentary evolution process of the caofeidian barrier lagoon system and the impact of relative sea level rsl rise the core sediment was tested for grain size microfossils foraminifera and ostracods and 14c dating the holocene formation of the delta coast morphology and sedimentary types was closely associated with different phases of rsl rise fluvial facies palaeosols and limnetic facies formed successively during the latest deglaciation but did not exhibit a direct relationship with rsl rise these sediment facies were immediately followed by the littoral limnetic facies that formed during 9 5 8 2 cal ka bp when the holocene sea level reached the study area then offshore sand bars formed on the southern side and tidal sand ridges formed on the eastern and western sides forming a barrier island which suggest that the caofeidian barrier lagoon system began to form under wave and tide dominated ocean dynamics at 8 2 7 8 cal ka bp as the sea level rose at a rate of ca 11 5 mm a 1 the caofeidian barrier lagoon system reached the maximum extent and was mainly influenced by wave dominated ocean dynamics at 7 8 7 5 cal ka bp during which the sea level rose at a rate of ca 9 0 mm a 1 the caofeidian barrier lagoon system began to erode and deteriorate at 7 5 6 7 cal ka bp with a sea level rise rate of ca 2 6 mm a 1 tidal sand ridges as barrier islands formed on the shore side under the influence of tide dominated ocean dynamics rsl rise was estimated at 2 3 m over the past 6 7 ka over this period the sandy barrier islands were eroded by tides and the lagoon areas transitioned into an intertidal zone our reconstruction of rsl changes showed that the rsl rose abruptly in four stages increasing by 1 7 m 11 0 m 1 7 m and 2 3 m at 9 5 8 7 8 7 7 5 7 5 6 7 and 6 7 0 cal ka bp respectively

temporal changes of a delta example from the holocene yahagi delta central japan abstract the depositional history of a delta was investigated by using radiocarbon dated borehole cores from the yahagi delta nishimikawa plain central japan in particular historical changes in the gradient thickness and grain size distribution of the delta front and sediment discharge of the yahagi river are discussed the latest pleistocene to holocene sequence in the yahagi delta is interpreted as an incised valley fill system formed after the last glacial and subdivided into five sedimentary facies facies a fluvial facies b estuary facies c prodelta facies d delta front and facies e gravelly tidal flat in the main axis of the incised valley facies a facies b facies c facies d and facies a are deposited in ascending order in the western area of the valley facies e adjoins facies d the delta front was formed by river floods without reworking by wave or tide the succession was interpreted as a transgressive systems tract and highstand systems tract formed under sea level rise until ca 7 cal kyr bp and the subsequent highstand after the formation of the delta in ca 7 cal kyr bp characteristic features of the delta front changed twice as the delta prograded first during 4 5 cal kyr bp the delta front became thicker and steeper this change was induced by differences in water depth between the middle incised valley and the outer incised valley which resulted from a buried clinoform second in ca 3 cal kyr bp the grain size distribution of the delta front became coarser and the sorting became poorer the sediment discharge of the yahagi river also increased abruptly this change was induced by the increase of erosional capacity in the hinterland increasing human activities such as deforestation and poor soil conservation might have induced this change

scolosaurus cutleri ornithischia ankylosauria from the upper cretaceous dinosaur park formation of alberta canada the synonymy of the ankylosaurid dinosaur scolosaurus with euoplocephalus has been widely accepted since the 1970s however scolosaurus cutleri exhibits differences which separate it from euoplocephalus tutus and dyoplosaurus acutosquameus although the holotype of euoplocephalus is fragmentary several other specimens can be reliably referred to this taxon and thus used for comparison scolosaurus differs from euoplocephalus in cervical half ring osteoderm and forelimb morphology scolosaurus differs from dyoplosaurus primarily in pelvic morphology and osteoderm shape recognition of scolosaurus as a valid taxon adds to the growing concept that the upper cretaceous ankylosaurid fauna of north america was more diverse than previously thought

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

anthropocene archaeology of the yellow river china 5000 2000 bp in this paper we use geoarchaeological and paleoenvironmental data from three localities in the yellow river valley china taosi sanyangzhuang and the yiluo valley to argue that human activi

effects of river regulation on aeolian landscapes colorado river southwestern usa 1 connectivity between fluvial and aeolian sedimentary systems plays an important role in the physical and biological environment of dryland regions this study examines the coupling between fluvial sand deposits and aeolian dune fields in bedrock canyons of the arid to semiarid colorado river corridor southwestern usa by quantifying significant differences between aeolian landscapes with and without modern fluvial sediment sources this work demonstrates for the first time that the flow and sediment limiting effects of dam operations affect sedimentary processes and ecosystems in aeolian landscapes above the fluvial high water line dune fields decoupled from fluvial sand supply have more ground cover biologic crust and vegetation and less aeolian sand transport than do dune fields that remain coupled to modern fluvial sand supply the proportion of active aeolian sand area also is substantially lower in a heavily regulated river reach marble grand canyon arizona than in a much less regulated reach with otherwise similar environmental conditions cataract canyon utah the interconnections shown here among river flow and sediment aeolian sand transport and biologic communities in aeolian dunes demonstrate a newly recognized means by which anthropogenic influence alters dryland environments because fluvial aeolian coupling is common globally it is likely that similar sediment transport connectivity and interaction with upland ecosystems are important in other dryland regions to a greater degree than has been recognized previously

redescription of ankylosaurus magniventris brown 1908 ankylosauridae from the upper cretaceous of the western interior of north america the armor plated dinosaur ankylosaurus magniventris is redescribed based on specimens from the hell creek formation of northeastern montana usa lance formation of wyoming usa and from the scollard formation of south central alberta canada except for brief descriptions most of these specimens have not been described in detail ankylosaurus is one of the largest known ankylosaurids having an estimated length of up to 6 25 m 20 5 ft it is characterized by a long low skull having very prominent cranial horns that project laterally or dorsolaterally the body armor includes a large half ring that sat across the base of the neck and shoulders and a large low tail club

a bloat and float taphonomic model best explains the upside down preservation of ankylosaurs abstract it is widely held that within the cretaceous fluvial and marine deposits of north america ankylosaur remains are typically preserved upside down however this anecdotal observation has yet to be substantiated likewise none of the various hypotheses that purport to explain the frequent occurrence of overturned ankylosaurs has been tested either this study is the first to apply quantitative and modeling approaches to address these shortcomings we find strong statistical support for the dominance of upside down occurrences and favour a bloat and float model to account for them according to this model ankylosaur carcasses become reworked into fluvial or marine settings where they bloat and overturn prior to their final deposition differential floating behaviour between ankylosaurids and nodosaurids may have implications regarding the occurrence of the latter in marine depositional environments this consideration of ankylosaur taphonomy might similarly help to explain the purported frequency of overturned glyptodonts which share a similar bauplan with ankylosaurs

the record of mid holocene maximum landward marine transgression in the west coast of bohai bay china abstract this study used benthic foraminifera diatom total organic carbon organic carbon isotope ratios c n ratios and grain size data from three ams 14 c dated cores collected from the western coastal lowland of bohai bay china to elucidate the coastal response to relative sea level change during the holocene a layer of peaty clay overlaying early holocene terrestrial sediment was dated to 8400 8000 cal bp and the peaty material in the sediment suggests possible vegetation cover before the mid holocene marine inundation in the study area sedimentary facies and changes in diatom and foraminifera assemblages suggest a five stage marine transgression regression history during the first stage from 8000 to 7855 cal bp the study area was inundated primarily by freshwater swamp during the second stage from 7855 to 6000 cal bp the study area was under brackish water influence in the third stage from c 6000 to 5750 cal bp the study area experienced marine influences and by this time the holocene transgression reached its maximum landward location and height this was followed by a period of regression since c 5750 cal bp during the last 4000 years the study area was influenced by freshwater and became a floodplain environment thus this study reveals that the most landward position of the holocene marine transgression was situated somewhere between the coring locations of dc01 and qx01 which is about 80 km inland from the present shoreline this means the west coast of the bay has advanced at an average speed of c 13 m a since the mid holocene the relative sea level around 6000 cal bp was at 2 64 0 1 m

new evidence on the spatial temporal distribution of superlobes in the yellow river delta complex abstract unraveling the spatial temporal distribution of delta superlobes precisely is particularly important and challenging in the yellow river delta complex yrdc previous research on this issue can be dated back to the early 1990s when the paleoenvironmental reconstructions mainly hinged on the historical documents and geomorphologic analysis of well developed cheniers from the west coast of bohai bay and only few drilled cores with scant radiocarbon dates were available to build a refined model of the holocene stratigraphic architecture and reconstruct the sedimentary evolution of the yrdc detailed sedimentological investigation of 12 boreholes including 59 new ams 14c radiocarbon dates was combined with other published 25 cores and 174 ams 14c dates therein age depth curves were grouped by stratigraphic positions and facies characteristics of these 233 radiocarbon dated samples across different sectors of the yrdc exhibiting consistent patterns that can be used to identify distinct phases of delta superlobe activities eight new superlobes with relatively accurate dating spans were therefore proposed in the yrdc our results demonstrate that very high aggradation rates almost invariably correlate with the onset of deltaic deposition age depth patterns thus may be very useful to elucidate the complex sedimentary evolution of delta systems with multiple lobes

stratigraphic sequence and episodes of the ancient huanghe delta along the southwestern bohai bay since the lgm abstract the sedimentary evolution of the ancient huanghe yellow river delta in china is not well documented due to frequent river avulsions and limited deep cores in this paper 22 cores with lengths of 20 m at the coastal plain along the southwestern bohai bay were used the sedimentary facies were determined by grain size and microfossil analysis and carbon 14 dating the strata in the study area since the last glacial maximum lgm are divided into lowstand system tract lst transgressive system tract tst highstand system tract hst and retrograding system tract rst the lst which formed during the lgm to 10 8 ka bp consists of hard mud layer and overlying interfluvial lowland and flood plain deposits the tst that formed during 10 8 8 5 ka bp mainly include coastal marsh onshore sand bars and filled incised valleys the hst that formed during 8 5 2 6 ka bp mainly includes flood plain river channel delta front mouth bar and prodelta the rst that formed after 2 6 ka bp mainly includes crevasse splay interfluvial lowlands and distributary channel about eight episodes of the ancient huanghe delta are observed during the holocene and the names of the deltas are given by corresponding location names of cheniers 1 during 10 8 8 5 ka bp around ys3 and np1 cores without formation of cheniers during the transgression 2 during 8 5 7 4 ka bp around ys1 ys4 and np3 cores the dongsun shuiyicheng delta 3 during 7 4 6 1 ka bp around ck1 core the mashanzi delta 4 during 6 9 5 7 ka bp around gz3 core the miaozhuang zhaizhuang delta 5 during 4 6 3 5 ka bp around ys4 core the wuditai delta 6 during 3 0 2 6 ka bp around hh4 and hh1 cores the qikou delta 7 during 2 6 1 9 ka bp around ys7 and np1 cores the nanpaihe delta and 8 during 1034 bc 1099 bc around wangzidao and dakouhe the wangzidao delta

river mouth bar formation riverbed aggradation and channel migration in the modern huanghe yellow river delta china this paper addresses the recent 1970s 1990s processes of river mouth bar formation riverbed aggradation and distributary migration in the huanghe river mouth area in the light of station based monitoring field measurements and remote sensing interpretation the results show that the morphological changes of the river mouth bar have been closely associated with the largely reduced fluvial discharge and sediment load landforrn development such as bar progradation occurred in two phases i e before and after 1989 which correspond to faster and lower bar growth rates respectively fast riverbed aggradation in the mouth channel was strongly related to river mouth bar progradation during 1976 1996 about 2 8 of the total sediment loads were deposited in the river channel on the upper to middle delta therefore the river water level rose by a few meters from 1984 to 1996 the frequent distributary channel migration which switched the radial channel pattern into the se directed pattern in the mid 1980s was linked with mouth bar formation marine conditions also constrain seaward bar progradation furthermore the history of river mouth bar formation reflects human impacts such as dredging and dyking in order to stabilize the coastal area c 2005 elsevier b v all rights reserved

the shallow marine architecture knowledge store a database for the characterization of shallow marine and paralic depositional systems abstract the shallow marine architecture knowledge store smaks is a relational database devised for the storage of hard and soft data on the sedimentary architecture of ancient shallow marine and paralic siliciclastic successions and on the geomorphological organization of corresponding modern environments the database allows incorporation of data from the published literature which are uploaded to a common standard to ensure consistency in data definition the database incorporates data on geological entities of varied nature and scale i e surfaces depositional tracts architectural elements sequence stratigraphic units facies units geomorphic elements including attributes that characterize their type geometry spatial relations hierarchical relations and temporal significance furthermore geological entities are assigned to depositional systems or to parts thereof that can be classified on multiple parameters e g shelf width delta catchment area tied to metadata e g data types data sources the smaks permits the quantitative characterization of modern and ancient shallow marine and paralic clastic depositional systems it aims to serve as a repository of analogue information for hydrocarbon bearing successions and as a research tool that can be applied to aid the development of facies models or to assess the sensitivity of depositional systems to particular controlling factors for example to demonstrate the wide applicability of the database in fields of both fundamental and applied research example database output is presented that i includes data from wave tide and fluvial dominated shallow seas and sedimentary successions and ii covers a wide depositional spectrum from backshore to shelf edge settings the examples include information on the facies organization of different types of paralic sub environments on the hierarchical arrangement of architectural elements that form deltaic constructional units in quaternary deltas on the morphometry of modern and quaternary tidal sand ridges and on the geometry of parasequence scale nearshore sandstone belts from the upper cretaceous of the western interior seaway in utah usa

seismic and core investigation on the modern yellow river delta reveals the development of the uppermost fluvial deposits and the subsequent transgression system since the postglacial period abstract postglacial stratigraphy and environmental evolution onshore and offshore the modern yellow river delta were investigated and analyzed through 1200 km high resolution seismic profiles and four boreholes together with previous publications four seismic units su 1 4 top to bottom that are bounded by seismic surfaces t1 t4 were identified in seismic profiles while four depositional units du 1 4 top to bottom were recognized in representative boreholes these seismic units and depositional units exhibit good correlation we interpreted su 1 du 1 as the modern yellow river deltaic deposits su 2 du 2 as the holocene neritic sediments su 3 du 3 as a pleistocene holocene transitional layer and su 4 du 4 as the lowstand fluvial sediments apart from t1 seafloor t2 deltaic base t3 shoreface ravinement and t4 transgressive surface all dip seaward but their dipping gradients reduced from t4 to t2 therefore the thicknesses of su 2 3 were observed seaward thicker trends presumably in relationship with different spatial sedimentation rates additionally down core distributions of environmental proxies e g grain size microfossils and geochemical characteristics reveal the transgression system du 2 and 3 can be further subdivided into 5 intervals associated with sharp environmental changes based on above evidences we raised an evolutionary model of the postglacial depositional environment at the modern yellow river delta and adjacent marine areas suggesting the study area evolved from riverine estuarine coastal shoreface neritic to final prodeltaic deltaic environment since the post last glacial maximum lgm in relationship with eustatic and climatic events as well as sediment input in the model we redefined the two phase channel systems that exhibited in our previous study liu et al 2014 as the tributaries of the lgm paleo yellow river and the tidal estuarine tidal channels that formed at the early holocene besides we speculated that two hiatuses erosions occurred at younger dryas and 4 3 cal kyr bp and further divided the study area into three depositional zones based on their different sedimentation rates of the transgression system

tracking lead origin in the yellow river estuary and nearby bohai sea based on its isotopic composition the pb concentration and pb isotopes pb 204 pb 206 pb 207 and pb 208 in surface sediments from the yellow river estuary and nearby bohai sea have been determined to investigate the pb sources in this area results showed that pb in the yellow river estuary and northern laizhou bay yre nl sediments was mainly from the yellow river catchment as a consequence of lithogenic sediments from rock weathering accumulation however pb in the coastal area of southern laizhou bay cslb sediments was from both natural and anthropogenic sources sewage discharged near the mihe mouth of the cslb did not extend further to the middle and outer shelves because of the current in laizhou bay the total pb concentration varied from 14 5 to 30 4 mu g g with an average concentration of 20 1 4 2 mu g g thus significant pb pollution was not observed in the yellow river estuary and nearby bohai sea however pb contamination in some sites was indicated by pb isotope ratios c 2015 elsevier ltd all rights reserved

magnetic characterization of distinct soil layers and its implications for environmental changes in the coastal soils from the yellow river delta abstract the soils in the yellow river delta yrd were formed through the deposition of the yellow river sediments under complicated hydrodynamic conditions resulting in large variability in soil properties in this study environmental magnetic analyses were conducted on four typical soil profiles and one high resolution soil profile with distinct soil layers to examine the soil formation process and to track the environmental changes the results showed that the red clay layer rcl in the yrd soil profiles had unique magnetic properties which could be clearly separated from the yellow silt layer ysl at frequency dependent susceptibility fd 6 susceptibility of anhysteretic remanent magnetization arm 250 10 8 m3 kg 1 arm magnetic susceptibility lf 5 arm saturated isothermal remanent magnetization sirm 45 10 5 m a 1 and sirm lf

modeling the infilling process of an abandoned fluvial deltaic distributary channel an example from the yellow river delta china abstract as an inevitable result of fluvial deltaic avulsions abandoned distributary channels and associated lobes form an important component of coastal marine systems serving as a sediment source and sink for the adjacent delta region the distinct differences between normal tidal flats and abandoned channel systems restrict the application of classic intertidal mud flat morphological theory to the study of the evolution of abandoned channels herein a quantitative model based on the concept of mass conservation was proposed to describe the infilling processes for an abandoned channel sediment cores and elevation profiles from an abandoned channel of the yellow river delta china along with hydrodynamic observational data are used to constrain a numerical approach and test model performance the modeled accumulation thicknesses are satisfyingly consistent with those derived from sediment cores the model results indicate that the tide delivered sediment flux and channel water depth are the dominant variables governing the variation in accumulation thickness in the abandoned channel whereas the channel shortening rate largely impacts the depositional area rather than depositional thickness by contributing to steady deposition on the mud flat tide associated landward sediment deposition formed a steep profile near the estuary while the final four years of deposition represent only a quarter of the total deposition compared to that from the first five years owing to a decreasing depositional rate the model derived sediment volume indicates that shore parallel flow is significant in shaping mudflat morphology especially in the late stages while the shortening of tidal channels leads to shrinking of the mud flat and sediment volumes despite its limitation to residual channels our model presents a new approach for quantitative interpretation of the geomorphic evolution of an abandoned river channel with finite boundary conditions providing a good reference to apply to other large deltaic systems

evolution of a tide dominated abandoned channel a case of the abandoned qingshuigou course yellow river abstract deltaic river systems including both active channels and abandoned channels are of significant importance to understand the deltaic morphology as well as to the coastal management and ecosystem maintenance however the healing process of the abandoned channel has not yet been well understood based on the sedimentary record and hydrographic surveys the deposit architecture and sediment dynamics of a tide dominated abandoned channel the abandoned qingshuigou channel of the yellow river are investigated the abandoned qingshuigou channel has been fully disconnected from the main river channel since an artificial diversion completed in 1996 twenty years after the abandonment sedimentation with an average thickness of 20 cm was identified in the abandoned channel illustrating a prominent seaward thickening trend from middle to lower channel at the present river mouth of the abandoned channel sedimentation layer with a thickness of 38 cm well matched the sedimentation rates derived from both chronological framework 1 85 cm yr derived from 210pb and sedimentary facies 1 90 cm yr these deposits are composed by fine grained sediment and enriched with organic matters differing largely from the river dominated deposits before abandonment tidal delivery of the sediment resuspended in the shallow water nearby qingshuigou river mouth dominated the refilling process of the abandoned channel meanwhile severe erosion near the abandoned river mouth shortened the channel 23 5 km in 1996 versus 14 5 km in 2018 and induced a lateral migration of the tidal inlet due to seasonally varying hydrodynamics the tide dominated abandoned qingshuigou channel converts from a sediment sink in summer seasons to both a source and a sink in winter seasons

sedimentary records off the modern huanghe yellow river delta and their response to deltaic river channel shifts over the last 200 years abstract the modern huanghe yellow river delta sedimentary complex has developed since 1855 when the lower river channel migrated northward from the yellow sea to the bohai sea as a result the river laden sediment accumulated rapidly on the lowlying plain and formed the mega delta here we present high resolution sedimentary sequences based on 137 cs and 210 pb dating and grain size parameters of two sediment gravity cores collected near the present river mouth core a11 and in adjacent laizhou bay core a26 based on these sedimentary sequences the different responses of the sediment records to natural and artificial channel shifts are presented the average sedimentation rates of the two cores a11 1951 2006 and a26 1808 2006 were estimated to be 2 25 cm year and 0 80 cm year respectively the results indicated that the geometry of the delta e g the location of river mouth and changing coastline and sediment supply from the river played an important role in the sedimentation of the subaqueous delta the channel shifts in 1976 and 1996 shortened the distances from the river mouth to the location of core a11 resulting in the local accumulations of relatively coarse particles from the river mouth the sedimentation of core a26 indicated four major channel shifts in 1855 1904 1947 and 1976 when the river mouth approached the core location the accumulated sediment became finer otherwise the active resuspension due to strong hydrodynamics resulted in the accumulation of coarser sediment the sediment records preserved in the two gravity cores illustrated different sedimentary responses to the lower channel shifts of the huanghe and sediment supply from the river at centennial scales which is critical to understanding the evolution of the modern huanghe delta in the past and to predicting the future trend

post glacial sequence and sedimentation in the western bohai sea china and its linkage to global sea level changes abstract post glacial sedimentary sequences provide a unique window for observing depositional and environmental responses to rapid changes in global climate and sea level here we integrate seismic records and the lithological variations of sediment cores from western bohai bay china in order to reveal the history of sedimentation and its linkages to global sea level changes since marine isotope stage 2 mis 2 the post glacial succession consists of six seismic units su1 su6 in descending order which are bounded by six key reflection surfaces t 0 r 1 r 2 r 3 t 1 and t 2 respectively corresponding to six depositional units du1 du6 identified in sediment cores together they comprise the latest sequence of infilling of western bohai bay where su6 is associated with the lowstand systems tract lst su5 is associated with the transgressive systems tract tst and the last four units of su4 su1 comprise the complex highstand systems tract hst during the interval of the mis 2 22 11 6 kyr bp sea level lowstand the lst was formed in a long term environment of sub aerial exposure or fluvial floodplain the tst is composed of transgressive deposits formed during the interval of global sea level rise and is characterized by a retrogradational feature from a swamp to a tidal flat environment and then to an estuarine subtidal environment a series of sedimentary facies transitions represent abrupt sea level rises in the early holocene which may correspond to the events mwp 1c 8 2 ka event and mwp 2 erosional trenches were well developed within su5 in the central eastern region and were probably part of a transgressive waterway system rooted from bohai strait they demonstrate that bohai bay experienced strong tidal erosion in the early holocene as a result of its morphology which consisted of a long narrow embayment the complex hst was initially formed at ca 7 cal kyr bp when sea level essentially stabilized in a highstand and developed rapidly after ca 6 cal kyr bp when the yellow river supplied large amounts of sediment to the western or southwestern margin of bohai bay its complex internal structure is related to the configuration of three flooding surfaces caused by changes in sediment supply and which in historical times separated four stages of river discharge mainly from the yellow river during ca 7 0 3 4 cal kyr bp the yellow river at one time emptied into the southwestern margin of bohai bay forcing its subaqueous delta to extend over the southern area of western bohai bay while open shelf sedimentation in the central and northern area of bohai bay consisted of the accumulation of a shelly layer subject to intensive storm reworking during ca 3 4 1 cal kyr bp the yellow river once discharged into the central and northern parts of western bohai bay forming two detached subaqueous deltas during ca 1 0 8 cal kyr bp the yellow river discharged into the central region stacking a subaqueous delta confined by the two older underlying subaqueous deltas during the last 800 years the discharge of the yellow river out of bohai bay has dominated coastal marine sedimentation which has a complex provenance

ankylosaurian tail clubs of middle campanian to early maastrichtian age from western north america with description of a tiny club from alberta and discussion of tail orientation and tail club function there are numerous undescribed tail clubs of diverse morphologies that may be assigned to euoplocephalus ornithischia thyreophora ankylosauridae of middle campanian to early maastrichtian age among these is an exceptionally small club the smallest so far described from north america most but not all clubs can be placed into one of three shape categories round bluntly pointed or elongate much of this diversity is ontogenetic or individual but some of it may be taxonomic caudal structure restricts lateral and especially vertical tail flexibility analysis of hindlimb length tail length and downward angle of the tail from the hips suggests that the tail was normally carried and swung just above the ground and was used primarily defensively for striking at the metatarsals of an attacking theropod intraspecific agonistic functions are possible but improbable

missing evidence for stepwise postglacial sea level rise and an approach to more precise determination of former sea levels on east china sea shelf abstract the vertical range of past sea level indicated by tidal flat deposits is equal to the sum of the sediment thickness and tidal range defining position of the dated sample in tidal flat deposits can increase the accuracy of former sea level determinations the salt water peaty layer often contains mixtures of autochthonous and allochthonous organic carbon and the tidal flat deposits may contain biological remains transported from shallow marine sources these allochthonous remains have older ages than those of the layers containing the dated materials most published 14 c data on the east china sea shelf are inadequate to define a precise postglacial sea level rise curve good results in determining both precise former sea levels and reliable 14 c ages can be provided by selecting large plant roots and wood fragments from peaty layers and selecting less worn foraminifera tests and mollusk shells of dominant species in modern equivalent environments such as foraminifera ammonia beccarii vars or mollusk corbicula fluminea from the peaty layer its close overlying deposits and the base of tidal flat deposits without a basal peaty layer the stepwise model for postglacial sea level rise on the east china sea shelf liu 2001 liu et al 2004 was mostly determined by freshwater peat shallow marine and subtidal samples which cannot provide precise water levels the reliability of many 14 c ages used is also questionable due to unknown proportions of allochthonous material thus the stepwise model is unsupported by available data a rough sea level curve in last 13 000 yr on the east china sea shelf is herein proposed it seems simple but is effective based on valid data

overbank and channelfill deposits of the modern yellow river delta abstract the huanghe is noted for its high transport rate of silt and clay which may reach depth averaged values of 200 kg m 3 during peak discharge the sediment load transported through the river on entering the delta plain amounts to 1012 kg per year in contrast to most other large deltas only one distributary channel is active at any one time the high sediment load causes the rivermouth to prograde at a yearly rate of 1 4 km into the shallow less than 20 m deep bohai gulf the vertical aggradation of the channel belt and mouth bar complex is also rapid decimetres per year on average so that after a normal average of twelve years increasing channel instability and avulsion create the start of a new delta lobe a series of satellite images covering the last fifteen years has provided insight in the evolution of the river pattern as well as the progradation of the delta front a newly developed distributary passes from a multichannel to a single straight channel system and ends with the formation of meanders the protruding mature delta lobe shows a radiating pattern of crevasse channels overbank crevasse deposits are made of vertically stacked dm scale waning flow sequences structurally characterized by from bottom to top small scour and fills even parallel lamination and climbing ripple crosslamination accumulation rates on crevasse splays can be predicted on the basis of estimated river sediment discharge it can be concluded that each sequence has been deposited within a few hours and that tidal waterlevel fluctuations may have played a role in the generation of a single sequence

morphological adjustment of the qingshuigou channel on the yellow river delta and factors controlling its avulsion abstract the avulsion time scale of channels on the yellow river delta yrd is about a decade due to the large sediment load and rapid channel aggradation and progradation nevertheless the qingshuigou channel has been maintained for about four decades since 1976 this channel provides an ideal opportunity to study channel evolution following avulsion and to examine different avulsion criteria in this study we analyzed the geomorphic adjustment of the lower qingshuigou channel during 1976 2015 and calculated normalized gradient advantage and superelevation at the channel to estimate how close the channel was to avulsion results showed that channel evolution processes may be divided into four phases i 1976 1980 rapid aggradation ii 1980 1985 channel widening and enlargement iii 1985 1996 main channel aggradation and shrinkage and iv 1996 2015 main channel incision and deepening evolution phases i ii and iii are similar to the avulsion cycle observed in natural and experimental fluvial systems the calculated values of normalized gradient advantage and superelevation in early 1990s exceeded the critical values suggested by previous studies implying that the channel was prone to avulsion nevertheless avulsion was prevented mainly due to limited overbank flows constriction from artificial dikes and slowed channel extension as a result of reduced sediment load the evolution of the qingshuigou channel confirms previous arguments that superelevation and gradient advantage are not sufficient for avulsion and multiple factors should be considered including flood frequency lateral mobility sediment diameter and human interruptions

sedimentary evolution during the last 1 9 ma near the western margin of the modern bohai sea abstract because the bohai sea is a semi enclosed sea connected to the north yellow sea only via the bohai strait its sedimentary evolution during the quaternary has been complex in particular the timing of quaternary transgressions especially pleistocene transgressions in the region has long been a matter of controversy thus the sedimentary history of the bohai sea in the quaternary is still poorly understood borehole core yrd 1101 200 30 m long drilled in 2011 on the northern coast of the modern yellow river delta covers the last 1 90 ma as indicated by paleomagnetic measurements here we report the results of integrated analyses of the core including its sedimentary characteristics downcore changes in environmental proxies benthic foraminifers and ostracods and accelerator mass spectrometry ams 14 c and optically stimulated luminescence osl dates from 1 9 to 0 83 ma the environment was fluvial the first quaternary transgression occurred at 0 83 ma the latest early pleistocene presumably caused by minor subsidence of the miaodao islands uplift several relatively weak transgressions occurred from 0 83 ma to the end of the middle pleistocene and three major marine sedimentary beds here called t 3 t 2 and t 1 in ascending order recorded in the early to middle mis 5 the early mis 3 and the middle to late holocene respectively were presumably caused by major subsidence of the miaodao islands uplift in transgression strength t 3 was weaker than t 2 which was basically the same as t 1 we interpret the change in transgression strength to reflect the interplay of sea level changes neotectonic subsidence and sediment supply changes comparisons with other cores from around the bohai sea showed that the thickness of the quaternary sedimentary sequence differs significantly among them and both the t 2 and t 3 clearly display differences in thickness facies sequence and completeness among the cores highlighting the important role of tectonic activity in the evolution of the quaternary stratigraphy in the bohai bay basin

on the geological significance of clastic parasequences abstract parasequences recognized in clastic sedimentary successions of shallow marine origin are considered by some geologists to be the fundamental building blocks of depositional sequences even though problems in their definition and application have been identified by others who instead advocate their abandonment as formal sequence stratigraphic units to elucidate the geological significance of clastic parasequences and inform the debate on their use in stratigraphy a quantitative characterization of the geometry facies characteristics and timescale of deposition of 1163 parasequences has been undertaken based on a synthesis of data from outcrop and subsurface studies that are available in the scientific literature through a database compilation the attributes of the studied parasequences are analysed with respect to the interpreted geological origin of the units and with consideration of sources of bias and uncertainty particular emphasis is placed on assessing the following i the importance of heuristics and of data types and coverage in the recognition of parasequences ii differences in parasequence characteristics observed across deltaic and shoreface depositional systems and between the quaternary and the ancient rock record iii possible explanations for the range in timescales of deposition of parasequences and iv the role of autogenic dynamics on the development of deltaic parasequences partly based on a comparison with the recent evolution of modern deltas the results demonstrate that parasequence definition and physical correlation suffer from subjectivity and that significant variability exists in the spatio temporal and architectural attributes of clastic parasequences this gives rise to uncertainty that affects the use of parasequences as a framework for comparison of the architecture of packages of strata originating via shoreline regression this uncertainty must be considered when using analogue data for subsurface predictions or when attempting comparative studies of clastic successions

transgressive successions of the mahakam delta province indonesia traditional views of deltaic systems assert that progradational deposits comprise nearly the entire stratigraphic succession with transgressive strata forming only a minor component similarly progradational units generally are regarded as having the best reservoir potential especially in topset beds and transgressive units are viewed as shale prone and therefore downgraded however integration of regional seismic mapping with well log and core data plus concepts derived from modern sedimentary processes indicates that transgressive successions are an important component of the mid miocene and younger stratigraphy of the mahakam delta province and that they have considerable reservoir potential seismic mapping identified eight horizons of regional extent that correspond to the boundaries of stratigraphic sequences seven sequences were deposited by successive deltas since the 10 2 my midmiocene unconformity with the axis of sedimentation shifting as each delta developed each sequence comprises progradational clastic successions at the axis of sedimentation aggradational clastic successions deposited primarily during transgressive events and aggradational carbonate successions that developed along the shelf edge in areas with minimal clastic input

mineralogy of the core yrd 1101 of the yellow river delta implications for sediment origin and environmental evolution during the last 1 9myr abstract in this study we report the high resolution heavy mineral records from a 200 30 m long borehole yrd 1101 on the northern coast of modern yellow river delta yrd covering the last 1 90myr the results show that the heavy mineral assemblages are dominated by epidote followed by hornblende garnet and hematite limonite in the yellow river yr sediments the content of hornblende is higher than the epidote and the epidote to hornblende ratios e h are lower than the core yrd 1101 the e h show two distinct lower values at depositional unit du 4 2 117 9 125 6 m and du 4 1 to du 2 13 5 99 3 m indicating the obvious influence of yr sediments the heavy mineral composition of du 5 is distinct from yr sediments and interpreted as the result from heterogeneous provenance of the adjacent ancient rivers while du 4 to du 1 resemble the upper middle reaches of the yr sediments the different sediment types mud sandy silt and silt of core yrd 1101 do not contain markedly different transparent heavy mineral assemblages in terms of concentration and mineral ratios no matter how sedimentary environment changes the ratios of epidote and hornblende show very stable values in du 4 1 and du 3 due to the influence of yr sediments the transparent heavy minerals such as hornblende epidote and other stable minerals which were relatively stable are controlled primarily by provenance while the sedimentary environment mostly influences the flaky minerals and the authigenic minerals this study provides evidence regarding the history of the lower reaches of the yr and yrd since the early pleistocene highlighting river s important role for the evolution of the western coast of the bohai sea bs

evolution of the buried channel systems under the modern yellow river delta since the last glacial maximum abstract a combined seismic survey and borehole analysis revealed a series of buried channels under the modern yellow river delta these data also provide evidence for the evolutionary study of the paleo channel system seismic units were correlated with the sedimentary facies along the borehole two sets of paleo channels phase i and phase ii are identified within different seismic units spanning the last deglaciation 13 8 5 ka b p the phase i channels formed between the last glacial maximum and the last deglaciation estimates of paleo discharge and analysis of local depositary environment link the phase i channels with the main stream of the paleo yellow river these channels were fed by melting ice caps and were abandoned with the rechanneling of the yellow river the phase ii channels were formed during the early holocene and exhibited a dendritic pattern further investigation is needed to fully understand the origin and evolution of the phase ii channels

the progradation and retrogradation of two newborn huanghe yellow river delta lobes and its influencing factors abstract in this paper 342 landsat satellite images were used to study the evolution of the qingshuigou and qing8 lobes during 1976 2016 sea level correction and statistical analysis were used to eliminate the effect of sea level fluctuations on the shoreline positions the results revealed that the evolution of the two newborn huanghe delta lobes was mainly influenced by the river sediment discharges river channel changes course shifts floods droughts and marine hydrodynamic forces during 1976 2016 the total land gain of the two lobes was 377 km2 according to mean tide line and the average epeirogenetic efficiency of river sediment discharge was 0 020 m2 ton which was greatly less than that when the channels were natural the artificial stabilization of the deltaic channels had negative impact on the land gain assuming no artificial adjustment to the deltaic channels the total land gain would increase 435 km2 the land gain of the two lobes was a function of the cumulative sediment discharges shoreline lengths and course shift bonuses under the circumstance of historical river channel changes the critical sediment discharge maintaining the area balance of the two lobes was a function of historical shoreline lengths which increased linearly from 61 m ton in 1976 to an average of 163 m ton during 1996 2016 in the future there are two ways to increase the land gain under the less huanghe sediment discharge reducing artificial disturbance of deltaic channels and letting the river enter the sea through the southwest coast of qingshuigou lobe

causes for continuous siltation of the lower yellow river previous studies indicate that aggradation of a river channel is caused by upriver and or downriver controls but the evaluation of their relative importance is often difficult a method is proposed to isolate the effect of the downriver control based on the slopes of the existing river profile those of the graded profile estimated from the discharge sediment relationship and slope reduction due to local base level rise the method was applied to the rapidly aggrading lower yellow river the downriver control in this case refers to the local base level rise associated with deltaic extension during the period under discussion the result shows that the main portion of siltation along the river is not caused by downriver control but by the slope difference between the existing and the graded profiles over a period within the last 700 years assuming conditions of discharge and sediment load during the period from 1962 to 1985 are reflective of the long term the marked slope difference between the existing and the graded profiles of the river is a result of changes in the river environment in the past several thousand years including the increase of sediment load local base level rise associated with river lengthening by deltaic growth and relative sea level rise due to tectonic subsidence of the coastal alluvial plain

changing pattern of accretion erosion of the modern yellow river huanghe subaerial delta china based on remote sensing images abstract the yellow river shifted from the diaokou course to the qingshuigou course in 1976 and shifted again at the north bank of the qingshuigou course in 1996 as a result the entire modern yellow river delta has experienced complicated patterns of erosion and accretion multitemporal remote sensing data of landsat mss and tm from 1976 to 2000 totaling twenty scenes were used to examine the changing pattern of accretion and erosion of the modern yellow river subaerial delta with gis tools during the period 1976 to 2000 the maximum erosion occurred at the head of the last two abandoned promontories diaokou and shenxiangou promontories where the coastline retreated landward over 7 and 4 5 km respectively with mean net erosion rates of 0 29 and 0 19 km a respectively in contrast the maximum accretion occurred at the head of the qingshuigou promontory where the coastline advanced seaward over 20 km with a mean net accretion rate of 0 83 km a the coastline at the head of the q 8 promontory also advanced seaward 7 km with a mean net accretion rate of 0 29 km a during the period 1996 to 2000 total area of the diaokou and shenxiangou promontories was reduced by 141 3 km 2 with a mean net erosion rate of 6 03 km 2 a total area of the qingshuigou and q 8 promontories increased by 384 16 and 11 88 km 2 respectively with mean net accretion rates of 16 4 and 3 03 km 2 a respectively relative to the diaokou shenxiangou and qingshuigou promontories the west area of the diaokou promontory and south area of the qingshuigou promontory were relatively stable although minor erosion occurred the general pattern of accretion and erosion of the modern yellow river subaerial delta was divided into three stages rapid accretion stage 1976 1984 accretion erosion adjustment stage 1985 1995 and slow erosion stage 1996 present the factors affecting the pattern of erosion and accretion over the yellow river delta such as structural geology the yellow river sediment discharge coastal processes meteorological conditions human activity sea level rise and land subsidence were summarized the cumulative area of increase over the entire subaerial delta is closely correlated with the cumulative yellow river sediment discharge wave induced longshore current is the major driving force to transport sediment from eroded areas along the last two abandoned promontories diaokou and shenxiangou promontories mostly westerly and partially easterly together with these coastal processes is the geographical shift of the yellow river course associated with its discharge regime after 1976 leading to the accretion along the present qingshuigou promontory and then the q 8 promontory

dinosaur eggshells from the lower maastrichtian st mary river formation of southern alberta canada north america is known for its rich uppermost cretaceous record of dinosaur egg remains although a notable fossil gap exists during the lower maastrichtian here we describe a diverse dinosaur eggshell assemblage from the st mary river formation of southern alberta that in conjunction with recently described eggs from the same formation in montana helps fill this gap and sheds light on the dinosaur diversity in this poorly fossiliferous formation three theropod eggshell types continuoolithus cf c canadensis montanoolithus cf m strongorum and prismatoolithus cf p levis and one ornithopod spheroolithus cf s albertensis are reported from albertan exposures of the st mary river formation increasing the ootaxonomic diversity of the formation from two to five ootaxa the taxonomic composition of the eggshell assemblage is consistent with the dinosaurian fauna known from the st mary river formation based on skeletal remains spheroolithus eggshells constitute the majority of identifiable e

skeletal and dermal armor reconstruction of euoplocephalus tutus ornithischia ankylosauridae from the late cretaceous oldman formation of alberta previously life reconstructions of ankylosaurid dinosaurs are incorrect in that they show uniformly shaped keeled plates arranged in neat longitudinal and transverse rows and large spines projecting laterally from the flanks of the body articulated armor of euoplocephalus tutus previously described as the types scolosaurus cutleri nopsca and dyoplosaurus acutosquameus parks from the late cretaceous oldman formation shows that armor shape and size varied considerably along neck back and tail an attempt is made to reconstruct the skeleton and arrangement of the dermal armor of euoplocephalus

sedimentation in the yellow river delta part ii suspended sediment dispersal and deposition on the subaqueous delta abstract rapid deposition and suspended sediment dispersal off the modern yellow river mouth has been examined from the data of topographic maps 1 25 000 suspension and bed sediments current and salinity which were measured in the field the results show that the sedimentation rate of the mouth bar is the highest of all the environments of deposition in the modern yellow river delta about 30 40 of the sediment that the river transports into the sea has been deposited within the mouth bar area rapid deposition of the mouth bar results mainly from kinetic energy dissipation of the river under the influence of three ambient mechanisms these three mechanisms occur simultaneously as shear front movement which obstructs the river s jet like flow small scale circulations where large velocity gradients occur and the bulldozer effect of the tide sensitive zone in the estuary at ebb based on the analysis of morphologic changes the mouth bar can be divided into two morphologic types one is the double lobe and single channel type and the other double channel and single lobe type weak hyperpycnal plumes with small density differences between the river flow and ambient water dissipate rapidly and deposit about 20 of the river sediments on the delta front slope while hyperpycnal underflows from the river mouth can go through the steep delta front slope to form a rise apron along the upper part of the prodelta grain size analysis of suspended sediment shows that the flow can be divided into three layers a tide layer in the upper part and a hyperpycnal layer in the lower part these two layers are normally graded and a transition layer with inverse grading in the mid part the fine suspended sediments have been transported in the hypopycnal plume layer into the prodelta and deep sea such as the north huanghai sea north yellow sea this study indicates that the tidal current field has dominated the distribution of deposition of sediment on the subaqueous delta and the movements of the river effluent and hyperpycnal underflows

sedimentation in the yellow river delta part i flow and suspended sediment structure in the upper distributary and the estuary abstract a 44 year data record measured by lijin hydraulic station on the yellow river shows that sediment concentration has been increasing while river discharge has been decreasing into the delta since the 1970s these changes are important because flood waters of the yellow river which are heavily laden with sediment must be used to supply dongying city and shengli oil company which are located on the delta based on the analyses of data of velocity sediment concentration salinity and sediment grain size from four cross section measurements at lijin station and one 8 vessel simultaneous measurement cruise in the estuary structural characteristics of the river flow and suspended sediments throughout the upper distributary and the estuary have been studied and discussed results show that when sediment concentrations of the yellow river exceed 100 kg m 3 in the lower layer of the river flow during the flood period the river flow structure does not coincide with the logarithmic law of wall and becomes vertically layered and the vertical distributions of suspended sediment do not coincide with the diffusion law the channel length influenced by the tide wave is less than 15 km and there is no tidal intrusion flow only weak osmosis of salinity occurs inside the river mouth during the flood period of the yellow river simultaneous 8 vessel measurements and simulation using the method of preissman show that there is a tidal sensitive zone inside the river mouth bar with a length of 6 7 km when the discharge is as large as 1100 m 3 s and an area of very active sedimentation the tidal sensitive region near the river mouth becomes a low velocity zone that traps a large amount of river sediment which rapidly forms a plastic bed at flood tide and a high velocity zone with a strong hydrodynamic action to erode the new bed and transport the sediments into the sea at ebb tide

historical changes in the yellow river delta china abstract the lower yellow river delta has experienced numerous avulsions during the last 2000 years and the floodplain can be divided into four provinces alluvial fan western plain middle plain and eastern plain coastal deltas the yellow river delta complex is composed of several delta superlobes resulting from shifts in the lower river channel and each delta superlobe consists of several smaller lobes formed by shifts in the distributary channels these two kinds of channel shifts have resulted in a complicated imbrication pattern in the delta complex two imbricated delta superlobes are divided by a reworked bed and buried shelf deposits shelly ridges form the surface boundaries between the various delta superlobes the delta superlobes passed through an active stage a reworking stage and were then finally overlain by later superlobes

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

anthropogenic origins of a late holocene basin wide unconformity in the middle reaches of the yellow river the luoyang basin henan province china we evaluate the relative importance of climate change fluvial dynamics and anthropogenic environmental modification in forming the holocene sedimentary record of the luoyang basin a tributary drainage basin of the yellow river located in western henan province china our 2011 fieldwork south of the erlitou site in the luoyang basin indicates that an unconformity dating to ca ad 1100 is roughly coincident with a major southward shift in the lower course of the yellow river in ad 1128 the governor of kaifeng breached the dikes of the yellow river to impede an advancing army causing the yellow river to flow south out to the yellow sea we argue that the dike breach not only changed the fluvial dynamics of the yellow river but also switched the rivers in the luoyang basin from an aggrading to an incising system the resumption of sedimentation in the luoyang basin is roughly coincident with the next major shift of the yellow river s main course northward to the bohai sea in ad 1855 the unconformity found in the luoyang basin may be a legacy of historically contingent human agency rather than climatic shifts or gradual environmental modification

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

a reconstruction of late pleistocene relative sea level in the south bohai sea china based on sediment grain size analysis future anthropogenic sea level rise and its impact on coastal regions is an important issue facing human civilizations due to the short nature of the instrumental record of sea level change development of proxies for sea level change prior to the advent of instrumental records is essential to reconstruct long term background sea level changes on local regional and global scales here we employ numerical methods to partition sediment grain size using a combined database of marine surface and core samples and to quantitatively reconstruct sea level variation since the late pleistocene in the south bohai sea china our sea level reconstruction indicates that relative sea level changes in the southern bohai sea track global sea level variation for the duration of the record the results also indicate substantial regression from 70 to 30 cal kyr bp and potentially subarial exposure from 38 to 20 cal kyr bp our results document the feasibility of reconstructing relative sea level change by numerical partitioning of sediment grain size data demonstrating the potential for future applications c 2012 elsevier b v all rights reserved

episodes of tidally forced swale erosion on the inner shelf interspersed with millennial fluviodeltaic progradational interludes insights from northern bohai bay china abstract erosional swales are common features on the seafloor with vigorous bottom flow s on continental shelves with energetical tidal currents and limited river discharge the initiation and evolution of tidally induced erosional depressions and bedforms have been extensively discussed but little is known about the evolution of such features when interspersed with active deltaic progradation over millennial timescales a recent boomer seismic investigation revealed a swale erosional complex within and proximal to the subaqueous delta in northern bohai bay nbhb china providing us with an opportunity to investigate such features here using the same seismic dataset we analyze the morphology reflective characteristics and evolution of the erosional and depositional structures the erosional swale complex consists of two episodes of tidally induced incised channels within a northern progradational system nps located in the northernmost bohai bay and prograde to the southeast followed by an episode of extensive trough and bump formation negative and positive relief within the middle and northern nbhb which are also erosional features these features are all highly lineated oriented wnw ese we attribute their formation to the similarly oriented tidal flows in this region the multi episode evolution of the swale erosional complex is predominately associated with progradation of the nps whose lobes cap the pre existing erosional features and provide substrate for new erosion the trough and bump complex was subject to long term erosion and may represent an evolution from the previous linear tidally forced marine incisions the complex was subsequently buried in part by the step wise progradation of a southern progradational system sps developed within the southern 2 3 bohai bay and prograde to the north northeast in addition we also observed clusters of longitudinal bedforms with convex internal reflectors superimposed on the erosional remnant bumps coeval with the erosion dominated environment they are observable on both sandy and muddy substrates

the huanghe yellow river and changjiang yangtze river deltas a review on their characteristics evolution and sediment discharge during the holocene abstract today asian rivers play an important role in delivering sediment from the land to the oceans however past sediment discharge before human activities modified the landscape is not well known and is estimated to have been roughly one third to one half of the present level chinese rivers have been strongly influenced by human activities and their sediment discharge has changed over the last 6000 years for the study of the long term human impact on rivers and catchment basins chinese rivers provide excellent examples because continuous historical records are available here the characteristics evolution and sediment discharge during the holocene of the deltas of two large chinese rivers huanghe yellow river and changjiang yangtze river are summarized the huanghe and changjiang deltas are different with respect to coastal environments water and sediment discharge the pattern of development of the delta lobe thickness of holocene sediments and basal topography of the incised valleys formed during the last glacial period the huanghe delta is characterized by a high concentration of sediment huge sediment discharge thin holocene deltaic sediments a lateral delta lobe shift and a steep longitudinal profile in its lower reaches the changjiang delta is characterized by a large water discharge a large interseasonal water level change a tide dominated coastal environment continuous seaward progradation with isolated river mouth sand bodies thick holocene sediments and a deep incised valley formed during the last glacial period based on the sediment volume of prograding deltaic sediments over the last 6000 years the sediment discharge of huanghe 1000 years ago is estimated to have been 1 10 8 tons year 1 10 of the present level an abrupt increase occurred at ca 1000 years ago as a consequence of human activities on the loess plateau especially involving cultivation and deforestation moreover the estimated sediment load of huanghe at sanmenxia station prior to 1000 years was 2 7 4 0 10 8 tons year or about 20 15 25 of the present level our recent study estimated that the sediment discharge of changjiang before 2000 years bp was ca 2 4 10 8 tons year total sediment discharge of both rivers before 2000 years bp is estimated to have been 3 4 10 8 tons year or only about 20 of the present level moreover the total sediment load to the lower reaches is estimated to have been 5 6 10 8 tons year or one fourth the present level

stratigraphic development during the late pleistocene and holocene offshore of the yellow river delta bohai sea abstract a 61 m long sediment core hb 1 and 690 km of high resolution seismic profiles from offshore of the yellow river delta bohai sea were analyzed to document the stratigraphy and sea level changes during the late pleistocene and holocene accelerator mass spectrometry 14c dating and analyses of benthic foraminifera ostracods the mineral composition and sedimentary characteristics were performed for core hb 1 and seven depositional units du 1 du 7 in descending order were identified the seismic reflection data were interpreted in light of the sedimentological data of the core and correlated with other well studied cores obtained previously in the bohai sea area seven seismic units su 1 to su 7 in descending order were distinguished and interpreted as follows su 7 corresponds to marine facies in marine isotopic stage mis 5 su 6 to terrestrial facies in mis 4 su 5 and su 4 to alternating terrestrial and marine facies du 7 du 5 in mis 3 su 3 to terrestrial facies du 4 in mis 2 su 2 to holocene marine facies du 3 and du 2 and su 1 to modern yellow river delta sediments deposited since 1855 du 1 the sedimentary facies from du 7 to du 5 reflect sea level fluctuations during mis 3 and the boundary between du 5 and du 6 which coincides with that between su 4 and su 5 is a distinctive laterally continuous undulating erosion surface with up to 20 m of relief this surface reflects subaerial exposure between transgressions during mis 3 estimated sea levels during mis 3 ranged from 35 5 to 60 5 m or lower with short term fluctuations of 20 m sedimentary environments in the bohai sea area were governed mainly by eustatic sea level changes and the bohai strait topography which controls the entry of sea water into the bohai sea area the mineral composition of the sediment core suggests that the yellow river did not discharge into the bohai sea or at least did not influence the study area significantly during parts of mis 3 and mis 2 to the early holocene 11 8 5 cal kyr bp

1500 year cycle dominated holocene dynamics of the yellow river delta china the world s mega deltas are extremely important from a human perspective and attract considerable effort to reveal their evolution growth related driving forces and human impacts here we report a case study on the holocene deltaic evolution of the yellow river through development of a conceptual model which is compared with paleo proxy to analyze the forcing acting on the delta the main conclusion is that superlobe switching was modulated by the 1500 year cycle cooling in mongolia in response to strong bond ird events which is coincident with warming in eastern china due to a strong kuroshio current enhances the meridional temperature gradient which then increases cyclone frequency and activates dust storms and terrestrial erosion throughout the catchment enhanced erosion supplies great amounts of material to the yellow river and causes channel evulsion and superlobe development expressed as dominant 1500 year cycle at the same time summer monsoon and solar forcing are uncorrected with deltaic evolution on these timescales therefore we conclude that holocene dynamics of the delta on a millennial timescale was dominated by winter cyclone activity across northern china and mongolia

spatial and temporal shoreline changes of the southern yellow river huanghe delta in 1976 2016 abstract in this study 364 landsat satellite images were utilized to study the spatial and temporal shoreline changes of the southern yellow river delta in 1976 2016 and a new method revised and improved after zhang et al 2016 was proposed by employing that method the calculated sea levels calculated from simulated tidal heights and instantaneous shoreline positions rather than simulated tidal heights were used to correct fluctuations in instantaneous shoreline positions caused by tidal height and seasonal sea level changes and other random sea level fluctuations when calculating the shoreline erosion rates and beach slopes a statistical analysis of a large number of corrected shoreline positions was used to reduce the influence of random errors that were mainly caused by waves and other casual factors the shoreline erosion rates and beach slopes presented in this paper are therefore more precise and reliable than those derived in previous studies which only used two satellite images the results of this study show that the shoreline of the southern yellow river delta primarily experienced gradual erosion during 1976 2016 with an average erosion rate of 26 9 m year the average shoreline erosion rate increased from 24 9 m year in 1976 1996 to 34 9 m year in 1996 2016 an increase of 40 probably due to the reduction in sediment discharge and shifting northward course of the yellow river after 1996 the shoreline erosion rate of the central coast decreased from 50 2 m year in 1976 1996 to 27 1 m year in 1996 2016 a decrease of 46 probably due to the protection offered by coastal hard structures the average shoreline erosion rate caused by relative sea level rise was 8 5 m year or 32 of the total average shoreline erosion rate relative sea level rise plays an important role in the erosion of the southern yellow river delta due to its flat beach the beach slope of the southern yellow river delta was flat and stable in 1976 2016 and the average slope over most of the beach was 0 043

permian of myanmar abstract permo triassic carbonates with minor basal clastics cover extensive tracts of the shan plateau in the eastern part of myanmar these carbonates are grouped into the permian thitsipin limestone formation and the late permian early triassic nwabangyi dolomite formation the thitsipin formation occurs as isolated masses in many places faulted against older rocks it is now known that there is a regional unconformity between the thitsipin limestone formation and the underlying silici carbonates of devonian age in shan state and between the thitsipin limestone formation and carboniferous meta siliciclastics in kayah state mon state kayin state and tanintharyi division some of the thitsipin limestone is dolomitized and passes transitionally upward into the nwabangyi dolomite formation permian shelf carbonates occur within two different sequences the silici carbonate sequence of the shan thai block and the meta siliciclastic sequence of the mergui terrane suggesting that the permian limestones were deposited after the emplacement of the mergui terrane onto the southern margin of the shan thai block this event occurred when the shan thai block was in the southern hemisphere