sedimentary system response to the global sea level change in the east china seas since the last glacial maximum abstract the east china seas ecs is one of the world s largest continental shelf seas based on the combination of global sea level change and sequence stratigraphy we systematically investigated the evolution of sedimentary system in the ecs since the last glacial maximum lgm we have defined the transgressive boundary layer and constructed several sedimentary models of the ecs on the sequence stratigraphy and evolution of tidal sand ridges since the lgm and sediment source to sink during the high sea level the result shows that the ecs represent a typical case for large scale continental shelf response to the global sea level change three sedimentary system tracts had been formed in the ecs since the lgm first is the lowstand system tract corresponding to the late of last glaciation and lgm 23 15 4 cal kyr b p the progressive wedge occurred along the okinawa trough slope and the paleo coastal zone pcz along the continental shelf edge second is the transgressive system tract corresponding to the last deglaciation 15 4 7 cal kyr b p a large scale transgressive boundary layer and tidal sand ridges were formed in this stage third is the highstand system tract corresponding to the high sea level since 7 cal kyr b p the eddy mud coastal current mud present tidal sand ridge delta tidal flat and beach have been accumulating since then the global sea level change after lgm can be divided into seven phases of which four rapidly rising phases rrp i ii iii iv and three slowly rising phases srp i ii iii are distinguished the tidal sand ridges were formed in the srp and transgressive boundary layer in the rrp the tidal sand ridges can be divided into three types including radicalized channel and emanative the modern circulation current system of the ecs had been built in the end of the last deglaciation the effect of sediment source to sink in the ecs is closely correlative to the current system driven by the interaction of the east asian monsoon and kuroshio the major sediment source is from the river discharge of the huanghe and changjiang river and coastal resuspension the muddy sediment in the eddy and coastal current which cover the tidal sand ridges and transgressive boundary layer is a major sediment sink in the modern ecs

geochemistry origin and recharge mechanisms of groundwaters from the garoua sandstone aquifer northen cameroon this paper presents results of the geochemical and isotopic studies on groundwater samples from the garoua sandstone basin in northern cameroon chemical and environmental isotope data are presented and discussed in terms of the origin of dissolved species and of groundwater all of the investigated groundwaters are categorized into two chemical types low mineralized and acidic waters of ca na hco3 type and relatively high mineralized waters of na hco3 type with relatively high ph between 7 40 and 8 22 interpretation of chemical data based upon both thermodynamic calculations and stability diagrams suggests that the chemical evolution of groundwater is primarily controlled by water rock interactions involving 1 acidic weathering of aluminosilicates 2 dissolution of secondary carbonate minerals and 3 cation exchange of na for ca2 however the original composition of groundwater may have been modified by further secondary processes such as mixing of chemically different water masses and anthropogenic no 3 pollution tritium contents in the considered groundwaters are very heterogeneous suggesting differences in the water turnover time or in the recharge conditions or both on the basis of the geographical distribution of 3h contents a hydrogeological relation between river and the groundwater systems has been proposed for the study site interpretation of both 18o and 2h as well as 3h suggests that the recharge of the investigated groundwaters may result from three major mechanisms 1 direct infiltration of local precipitation 2 lateral inflow of river waters 3 probably upward leakage of old groundwaters

hydrogeochemistry and arsenic contamination of groundwater in the rayen area southeastern iran high as contents in groundwater were found in rayen area and chosen for a detailed hydrogeochemical study a total of 121 groundwater samples were collected from existing tube wells in the study areas in january 2012 and analyzed hydrogeochemical data of samples suggested that the groundwater is mostly na cl type also nearly 25 62 of samples have arsenic concentrations above who permissible value 10 g l for drinking waters with maximum concentration of aqueous arsenic up to 25 000 g l the reducing conditions prevailing in the area and high arsenic concentration correlated with high bicarbonate and ph results show that arsenic is released into groundwater by two major phenomena 1 through reduction of arsenic bearing iron oxides oxyhydroxides and fe may be precipitated as iron sulfide when anoxic conditions prevail in the aquifer sediments and 2 transferring of as into the water system during water acidic volcanic rock interactions

worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

shallowly buried enigmatic seismic stratigraphy on the new jersey outer shelf evidence for latest pleistocene catastrophic erosion chirp seismic profiles reveal a prominent seismic facies boundary 0 20 m below the seafloor within an 8 6 10 2 km area of the new jersey outer shelf this irregular boundary separates seismically transparent facies from underlying stratified facies the irregularities form two populations of incisions trending northeast and east northeast stratified blocks within the transparent facies occasionally within presumed incisions together with lithologic evidence indicate that some of the transparent facies was formed by disruption of the stratified facies preservation of steep 50 90 incision flanks implies that deposition of the transparent facies closely followed disruption catastrophic erosion and redeposition following the multiple breaching of glacial lake dams to the north ca 19 12 ka constitute the likeliest mechanisms both for producing facies boundary incisions and emplacing the transparent facies implying that local forcing can generate erosional unconformities on periglacial shelves in the absence of base level change this facies boundary adds complexity to the already complex shallowly buried stratigraphic record of the last glacio eustatic cycle on the new jersey continental shelf long considered typical of periglacial shelves worldwide

sediment budget of the yellow river delta china the importance of dry bulk density and implications to understanding of sediment dispersal abstract this study constructs sediment budgets for the delta of the yellow river one of the world s largest muddy rivers and based on these budgets discusses the characteristics and related mechanisms of sediment dispersal at the river mouth the sediment budgets are derived from quantifying deposits in the deltaic lobe formed at the diaokouhe mouth of the river a detailed investigation of the dry bulk density of deposits in the delta which yields models of dry bulk density of deposits in the main depositional settings of the delta guarantees the reliability of the sediment budgets results show that deposits behind the delta front of the diaokouhe lobe over the period of 1965 to 1974 account for 73 5 of the incoming sediment the constructed sediment budgets reveal that the proportions of the deposits accumulated behind the delta front vary considerably over time the main factor responsible for the variations is the change in sediment discharge of the river there is no evidence for the anticipated positive relationships between the proportion of sediment escaping from the delta and water discharge clay content of incoming sediment or mouth channel efficiency the characteristics of sediment dispersal on the delta are related to the rapid extinction of sediment charged hyperpycnal underflows which are dominant in the plumes off the yellow river mouth and sediment deposition in the overbank flow on the delta plain because both of these processes trap a higher proportion of sediment at a higher sediment discharge

geochemical and statistical evaluation of groundwater in imphal and thoubal district of manipur india abstract in order to identify the hydrogeochemical process controlling the quality of groundwater an extensive study was carried out in imphal and thoubal district of manipur india the objectives of the studies were to delineate the spatial and temporal variability in groundwater quality and understand its suitability for human uses in the study area groundwater samples from 45 location have been collected during the pre monsoon monsoon and post monsoon seasons and analyzed for the major ions such as ca2 mg2 na k hco 3 cl so 4 2 no 3 po 4 3 f fe and silica the water quality of both districts was good for domestic and agricultural uses except for few samples these saline samples were localized and were due to the inherent lithology of the study area three major hydrochemical facies ca hco3 type mixed ca na hco3 and ca mg cl types in imphal district and ca hco3 mixed ca mg cl and ca cl type in thoubal district were identified the mineral stability diagrams indicated that the groundwater is in equilibrium with kaolinite and ca montmorillonite whereas gibbs plot showed that the chemical composition of ground water in both districts is controlled by the natural weathering processes irrespective of seasons among the chemical weathering processes silicate weathering was dominant the results were supported by wilcox plot and ussl diagrams the study reflected the overall suitability of groundwater for anthropogenic use

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

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

refined chronostratigraphy of a late quaternary sedimentary sequence from the yangtze river delta based on k feldspar luminescence dating abstract dating of sediments in the tidal dominated yangtze river delta remains a challenge because of extremely complicated processes during sediment transport and deposition in such a fluvial marine transition zone to better understand the late quaternary sedimentary history of the yangtze river delta we explore the applicability of k feldspar luminescence dating techniques to deposits through a case study on a 60 m long borehole core yz07 in the delta and then establish a spanning 50 000 year long chronological sequence a series of luminescence pre tests including dose recovery tests and determination of residual dose and fading rates were implemented using the modified single aliquot regenerative dose sar protocol for post infrared ir ir stimulated luminescence irsl measured at 150 c after prior irsl at 50 c pirir150 luminescence characteristics of the prior irsl ir50 and pirir150 were then analyzed to check their validity two fading correction models were utilized to correct apparent ages obtained from ir50 and pirir150 signals the newly obtained k feldspar luminescence ages were compared with quartz osl ages and 14c ages our results indicate that most of ages derived from pirir150 signals were overestimated due to incomplete bleaching in contrast the fading corrected ages from ir50 measured in pirir150 protocol are robust as they are consistent with quartz osl ages and 14c ages as well as the stratigraphy especially ir50 ages are characterized by negligible residual dose and thus reliably used for defining chronology of the chronological sequence over the past 50 ka our positive results of k feldspar dating shed light on further exploration of older unit in the yangtze river delta in combination with sedimentological and paleontological analyses of core yz07 we find fluvial to tide influenced fluvial deposits were emplaced during the period 30 50 ka which were then overlain by post glacial tidal river 13 11 5 ka and holocene estuarine shelf delta system and tidal flat deposits in the yangtze river delta together records of yz07 with other chronostratigraphy from the collected cores we confirm the existence of marine isotope stage mis 3 depositional units along the marginal coast of the yangtze river delta in relation to the interstadial sea level highstand our stratigraphic correlation based on the refined chronology reveals offshore transition of the mis 3 unit into facies deposited in deeper and offshore marine environments

using geochemical data and modelling to enhance the understanding of groundwater flow in a regional deep aquifer aquitaine basin south west of france abstract in deep aquifers the complex flow pattern originating from the geological structure often leads to difficult predictions of water origin determination of the main flow paths potential mixing of waters all these uncertainties prevent an efficient management of the resource in the context of the aquitaine basin an original modelling approach suggests that geochemical data can be used to identify flow directions where geological and hydrogeological data are too scarce to provide sufficient information in the eocene sands aquifer the major patterns of groundwater geochemistry suggest the presence of two distinct areas within the aquifer in the north and the east waters exhibit sodium bicarbonate or sodium sulphate facies and moderate total dissolved solids related to high sulphate concentrations in the south waters are characterised by calcium bicarbonate facies and low total dissolved solids sulphur isotopic ratios provided key information on the origin of sulphur in solution meteoric gypsum dissolution pyrite oxidation and also on the intensity of the geochemical processes involved in the dissolution of minerals and the concentration evolution a geochemical model was developed to analyse the processes generating the chemical composition of each sampled water at the aquifer scale four main geochemical processes dissolution redox acid base reaction exchange of varying intensity could explain most of the observed spatial variability in groundwater composition among several potential reaction schemes at each point only one allowed to reproduce the independent variables ph and 13c the developed model was used to select the most probable water pathways at the aquifer scale in this context geochemistry clearly demonstrates the role played by subsurface structures on water flow velocities and residence time in their vicinity in addition the concentrations of several ions could only be justified by the aquitard aquifer interactions

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

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

early to mid holocene rapid sea level rise and coastal response on the southern yangtze delta plain china we used accelerator mass spectrometry ams 14 c dated sediments of the holocene basal supratidal flat to upper tidal flat facies in 11 cores on the southern yangtze delta plain to reconstruct relative sea levels of 8 5 8 0 cal ka bp three cores were further ams 14 c dated and used to examine the evolution of sedimentary geomorphological environments in response to the rapid sea level rise during the early to mid holocene results demonstrate relative sea level rise of around 30mm a 1 from 8 5 to 8 3 cal ka bp and around 10mm a 1 from 8 3 to 8 0 cal ka bp retrogradation from supratidal to lower tidal flat environments occurred in response to the rapid sea level rise at 8 5 8 3 cal ka bp and aggradation from middle to upper tidal flat occurred at 8 3 7 9 cal ka bp further retreat of the tidal flat at 7 9 7 2 cal ka bp implies a mean sea level rise rate exceeding 5mm a 1 at this time we suggest that the rapid relative sea level rise during 8 3 8 5 cal ka bp and subsequent slower rise caused drastic changes in the coastal zone and that these changes are key phenomena for understanding the coastal response to future sea level rise copyright 2013 john wiley sons ltd

arsenic toxicity of groundwater in parts of the bengal basin in india and bangladesh the role of quaternary stratigraphy and holocene sea level fluctuation arsenic toxicity in groundwater in the ganges delta and some low lying areas in the bengal basin is confined to middle holocene sediments dissected terraces and highlands of pleistocene and early holocene deposits are free of such problems arsenic rich pyrite or other arsenic minerals are rare or absent in the affected sediments arsenic appears to occur adsorbed on iron hydroxide coated sand grains and clay minerals and is transported in soluble form and co precipitated with or is scavenged by fe iii and mn iv in the sediments it became preferentially entrapped in fine grained and organic rich sediments during mid holocene sea level rises in deltaic and some low lying areas of the bengal basin it was liberated subsequently under reducing conditions and mediated further by microbial action intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater this practice has induced groundwater flow mobilizing phosphate derived from fertilizer as well as from decayed organic matter which has promoted the growth of sediment biota and aided the further release of arsenic however the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the ganges floodplains upstream of rajmahal thus arsenic toxicity in the groundwater of the bengal basin is caused by its natural setting but also appears to be triggered by recent anthropogenic activities

hydrogeochemical characteristics of groundwater from the two main aquifers in the red river delta vietnam abstract in the red river delta situated in the northern part of vietnam nearly its entire population depends solely on groundwater for daily water consumptions for this reason groundwater quality assessments must be carefully carried out using hydrogeochemical properties to ensure effective groundwater resource planning for the delta s present and future groundwater use in this study the spatial and seasonal changes in the hydrogeochemical characteristics of groundwater in the two main aquifers of the rrd were investigated by analyzing the physicochemical data obtained in 2011 from 31 conjunctive wells in the delta s holocene unconfined aquifer hua and pleistocene confined aquifer pca using the piper diagram and the gibbs diagram results of the data analysis show that the groundwater in both aquifers in the upstream area of the delta is dominated by the ca 2 hco 3 water type while the na cl dominates along the middle stream and downstream areas seasonal changes in the hydrogeochemical facies in both aquifers comparing the results for the dry and the rainy seasons were detected in about one third of the sampling wells which were mainly located at the upstream portion of the delta the hydrogeochemical facies of hua were different from that of pca by about 45 of the sampling wells in both the dry and the rainy seasons which were found mostly in the upstream and middle stream areas

itrax description and evaluation of a new multi function x ray core scanner a new automated multi function core scanning instrument named itrax has been developed that records optical radiographic and elemental variations from sediment half cores up to 1 8 m long at a resolution as fine as 200 m an intense micro x ray beam focused through a flat capillary waveguide is used to irradiate samples to enable both x radiography and x ray fluorescence xrf analysis data are acquired incrementally by advancing a split core via a programmable stepped motor drive through the flat rectangular section x ray beam traditional xrf determination of element composition in sediments provides high quality data but it takes a considerable time and normally consumes gram quantities of material that is often only available in limited quantities the itrax core scanner non destructively collects optical and x radiographic images and provides high resolution elemental profiles that are invaluable for guiding sample selection for further destructive detailed sampling this paper presents a description of the construction characteristics and capabilities of the itrax system high resolution itrax data obtained from sediment cores are also presented and compared with results from traditional wavelength dispersive xrf analysis at lower resolution finally some recent technical developments linked to the second generation itrax are presented

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

identification of spatio seasonal hydrogeochemical characteristics of the unconfined groundwater in the red river delta vietnam abstract groundwater has been the primary source of daily water supplies for people living in the red river delta the second largest delta in vietnam for this reason identification of hydrogeochemical properties of the groundwater is indispensable for sustainable utilization of groundwater sources in this study the spatio seasonal hydrogeochemical characteristics of groundwater in the unconfined aquifer of the red river delta have been investigated by systematically applying self organizing maps som and gibbs diagrams the groundwater chemistry dataset used in the analysis is composed of eight major dissolved ions i e ca2 mg2 na k hco 3 cl so 4 2 and co 3 2 and total dissolved solids that are collected from 47 groundwater monitoring wells within the study area during the dry and rainy seasons the som application classified the hydrogeochemical data into five clusters which revealed three basic representative water types high salinity one cluster low salinity two clusters and freshwater two clusters the spatial distribution of clusters and water types were identified in particular the low salinity type was found not only in the downstream area but also in the northeastern parts of the upstream and middle stream areas where the groundwater was mainly classified into one specific cluster in which agricultural activities were considered to influence groundwater chemistry cluster changes from the dry to rainy seasons were detected in approximately one fifth of the observations wells dilution by surface water may significantly affect the chemical characteristics of the unconfined aquifer during the rainy season based on gibbs diagrams rock weathering was found to be the main process in the evolution of chemical composition of freshwater type whereas the chemical structure of the low and high salinity types was primarily controlled by saltwater intrusion or anthropogenic activities

stratigraphy and sedimentary environments during the late quaternary in the eastern bohai sea north china platform abstract the bohai sea is a shallow sea at the east coast of china it communicates with the yellow sea through a narrow strait during and since the late pleistocene the bohai sea has been a filled subsiding basin submitted to successive regressive transgressive cycles in the east bohai sea a number of finger shaped ridges are present near the strait where tidal currents are dominant very high resolution seismic reflection data have been interpreted relative to sedimentological data provided by a formerly drilled borehole seven seismic units are identified and correlated with the following events units u7 u6 with the bohai relative sea level rise 65 000 53 000 yr b p and a relative sea level fall 53 000 39 000 yr b p unit u5 with the xianxian relative sea level rise 39 000 22 000 yr b p unit u4 with the period of the late wurm glaciation 22 000 15 000 yr b p units u3 u2 with the transitional period from the end of the pleistocene to the beginning of the holocene 15 000 9000 yr b p and unit u1 with the holocene huanghua marine intrusion in the bohai sea since 9000 yr b p in the bohai sea formation of the tidal ridges is probably due to a substantial increase in tidal current velocities during the late holocene rise of sea level constriction due to the strait amplifies the tidal process so that the sediments of the late holocene transgressive sequence have been remodeled as tidal ridge

late quaternary linkage of sedimentary records to three astronomical rhythms and the asian monsoon inferred from a coastal borehole in the south bohai sea china abstract the bohai sea was formed by subsidence during the cenozoic some 2000 3000 m of fluvial lacustrine and marine sediments has been deposited in this basin previous studies focused mainly on the transgression history with little examination of orbital variation in relation to other areas within the asian monsoon domain here we present the late quaternary results of a new borehole in the south bohai sea optically stimulated luminescence and radiocarbon dating which provide concordant age estimates were employed to generate an initial chronology for the borehole after refining the chronology through astronomical tuning the results showed that 1 the grain size variation represents asian monsoon intensity which was dominated by both solar insolation major and global ice volume minor forcing 2 the magnetic susceptibility indicates river incision processes which were sensitive to orbital tilt with influence from solar insolation 3 the vegetation coverage responded to global ice volume coupled obliquity changes and that 4 neither external nor internal factors could dominate the paleoenvironmental evolution on orbital timescales in an independent way and they are both integrated in a complex pattern we conclude that three different astronomical rhythms have affected coastal evolution and that the sedimentary records in the south bohai sea china result from the nonlinear interaction and the complex response to driving processes

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

palaeochannels on the north china plain palaeoriver geomorphology abstract variations in the geomorphology of the north china plain are related to differences between river deposits the river deposits from different periods form the various geomorphological features different combinations of palaeochannels form different geomorphological regions different kinds of palaeochannels form different kinds of micro geomorphology during the early glaciation of the late pleistocene the river deposits formed piedmont plains and floodplains by the early holocene the rivers had cut the piedmonts into dissected valleys and deposited alluvial fans at the front edge of the piedmonts to form alluvial plains below by the middle holocene lake sediments covered the alluvial plains and filled in the dissected valleys of the piedmont plains by the late holocene rivers dissected the piedmonts again to form dissected valleys and deposited alluvial fans in the lower reaches to form alluvial plains and deltas at the river mouths

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

sedimentary facies and holocene progradation rates of the changjiang yangtze delta china abstract the changjiang yangtze river one of the largest rivers in the world has formed a broad tide dominated delta at its mouth during the holocene sea level highstand three boreholes cm97 js98 and hq98 were obtained from the changjiang delta plain in 1997 1998 to clarify the characteristics of tide dominated delta sediments and architecture based on sediment composition and texture and faunal content core sediments were divided into six depositional units in ascending order they were interpreted as tidal sand ridge prodelta delta front subtidal to lower intertidal flat upper intertidal flat and surface soil deposits the deltaic sequence from the prodelta deposits to the delta front deposits showed an upward coarsening succession overlain by an upward fining succession from the uppermost part of the delta front deposits to the surface soil thinly interlaminated to thinly interbedded sand and mud sand mud couplets and bidirectional cross laminations in these deposits show that tide is the key factor affecting the formation of changjiang deltaic facies sediment facies and their succession combined with ams 14c dating revealed that isochron lines cross unit boundaries clearly and delta progradation has occurred since about 6000 to 7000 years bp when the rising sea level neared or reached its present position the average progradation rate of the delta front was approximately 50 km kyear over the last 5000 years the progradation rate however increased abruptly ca 2000 years bp going from 38 to 80 km kyear the possible causes for this active progradation could have been an increase in sediment production in the drainage basin due to widespread human interference and or decrease in deposition in the middle reaches related to the channel stability caused by human activity and climatic cooling after the mid holocene

marine sediment records and relative sea level change during late pleistocene in the changjiang delta area and adjacent continental shelf abstract optically stimulated luminescence osl dating and microfossil analysis were conducted on late quaternary samples from two boreholes in the changjiang delta area successions from 12 collected boreholes revealed lithology stratigraphy and sedimentary facies of the changjiang delta area and continental shelf of the east china sea ecs these data were used to determine the chronology of two transgressions during marine isotope stage mis 5 and mis3 interpret the sedimentary facies and mechanisms of the distinctive transgression pattern and reconstruct relative sea level of the study area during late mis3 fluvial gravelly sediment deposition prevailed with limited marine influence during mis5 while muddy and sandy deposition occurs along with widespread coastal facies during mid and late mis3 in the changjiang delta area this suggests that the study area was dominated by high relief and local rivers developed with large freshwater and sediment discharge during mis5 therefore marine micro faunas may not have survived due to dominant freshwater process or strong erosion has scoured away the marine records of mis5 tectonic subsidence is indicated to occur at a rate of 1 m ka since mis5 and lower the changjiang coastal area to be invaded by seawater during mis3 the altitude of late mis3 transgressive sediments decreases from the inner delta plain seaward gradually reflecting differential tectonic subsidence of the study area abrupt sea level rise occurred and relative sea level is proposed as 5 m during late mis3

geochemical characteristics and the provenance of sediments in the bransfield strait west antarctica abstract the bransfield basin is a quaternary marginal basin separating the south shetland islands from the antarctic peninsula we analyzed major trace and rare earth element chemistries and the nd sr and pb isotopic compositions for six piston core sediments from the western and eastern bransfield basins to determine the sediment provenance and factors controlling the composition of the sediments the bransfield sediments have chemical characteristics similar to sediments deposited in a tectonically active setting where the source rocks are predominated by igneous rocks of intermediate to mafic composition low k and high cn in the a cn k diagram low la sc low th sc and lower lree hree than average shale the low chemical alteration index of the sediments about 45 on average suggests the effect of weathering on the sediment composition was minimal the source rocks of the bransfield sediments are mostly composed of mesozoic to tertiary arc volcanic and plutonic rocks in the antarctic peninsula and the south shetland islands meanwhile contributions from other rock types in the northern antarctic peninsula region such as the trinity peninsula group or scotia metamorphic complex seem to be negligible the bransfield sediments can be divided into three distinct compositional groups group i sediments have a lower la yb and a less prominent negative eu anomaly than group ii sediments they are also characterized by negative ce anomalies group i sediments have been derived mainly from the south shetland islands whereas group ii sediments which are more widespread than group i sediments in the bransfield strait have been derived mainly from the antarctic peninsula group iii sediments which are very low in la yb with the lowest 87 sr 86 sr and the highest 143 nd 144 nd values have been derived from deception island the composition of the bransfield sediments is largely controlled by the composition of nearby source rocks the distribution of sediments is further modified by the current and topography of the basin

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

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

high altitude varve records of abrupt environmental changes and mining activity over the last 4000 years in the western french alps lake bramant grandes rousses massif abstract two twin short gravity cores and a long piston core recovered from the deepest part of proglacial lake bramant grandes rousses massif french alps under and overlying a large slump identified by high resolution seismic profile allow the investigation of holocene natural hazards and interactions between human activity and climatic changes at high altitude annual sedimentation throughout the cores glacial varves is identified on photographs itrax high resolution continuous microfluorescence x and cat scan computerized axial tomography analyses and is supported by 1 the number of dark and light laminations between dates obtained by radionuclide measurements 137cs 241am 2 the correlation of a slump triggered by the nearby ad 1881 allemond earthquake msk intensity vii and of a turbidite triggered by the ad 1822 chautagne regional earthquake msk intensity viii 3 the number of laminations between two accelerator mass spectrometry ams 14c dates and 4 archaeological data in lake bramant dark layers are coarser contain less detrital elements but more neoformed elements and organic matter content these darker laminations result from calm background sedimentation whereas the lighter layers are finer and rich in detrital elements and reflect the summer snowmelt traces of mining activity during the roman civilization apogee ad 115 330 and during the early bronze age 3770 3870 cal bp are recorded by lead and copper content in the sediments and probably result from regional and local mining activity in the nw alps warmer climate during the bronze age in this part of the alps is suggested by 1 two organic deposits 4160 3600 cal bp and 3300 2850 cal bp likely reflecting a lower lake level and smaller glaciers and 2 evidence of a different vegetation cover around 2500 m a s l the onset of clastic proglacial sedimentation between 3600 3300 cal bp and since 2850 cal bp is synchronous with periods of glacier advances documented in the alps and high lake levels in west central europe this major change in proglacial sedimentation highlights the development of a larger st sorlin glacier in the catchment area of lake bramant

geochemistry characterization of groundwater in an agricultural area of razan hamadan iran this study was conducted to evaluate factors regulating groundwater quality in an area with agriculture as main use thirty groundwater samples have been collected from razan area hamadan iran for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater the chemical compositions of the groundwater are dominated by na ca2 hco3 cl and so42 which have been derived largely from natural chemical weathering of carbonate gypsum and anthropogenic activities of fertilizer s source the production of so42 has multiple origins mainly from dissolution of sulphate minerals oxidation of sulphide minerals and anthropogenic sources the major anthropogenic components in the groundwater include na cl so42 and no3 with cl and no3 being the main contributors to groundwater pollution in razan area

identification and evolution of hydrogeochemical processes in the groundwater environment in an area of the palar and cheyyar river basins southern india the palar and cheyyar river basins in tamil nadu state of southern india are characterised by different geological formations and groundwater is the major source for domestic agricultural and other water related activities hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes and their relation to groundwater quality groundwater samples were collected once a month from 43 groundwater wells in this area from january 1998 to july 1999 sampling procedures and chemical analysis were carried out as per the standard methods chemical data are used for mathematical calculations and graphical plots to understand the chemical process and its relation to the groundwater quality the chemical composition of groundwater in the central part of the study area mainly depends on the recharge from lakes and the river which is explained by a mixing mechanism in addition weathering of silicate minerals controls the concentration of major ions such as sodium calcium magnesium and potassium in the groundwater of this area further the activity ratios indicate that the groundwater is in equilibrium with kaolinite smectite and montmorrillonite the reverse ion exchange process controls the concentration of calcium magnesium and sodium in hard rock formations and dissolution of carbonate minerals and accessory minerals is the source of ca and mg in addition to cation exchange in the sedimentary formations in general the chemical composition of the groundwater in this area is influenced by rock water interaction dissolution and deposition of carbonate and silicate minerals ion exchange and surface water interactions

environmental processes of the ice age land oceans glaciers epilog knowledge of the state of the earth at the last glacial maximum lgm an interval around 21 000 years ago is an important benchmark for understanding the sensitivity of global environmental systems to change much progress in understanding climates of the lgm has occurred in the 20 years since the end of the climap project of the 1970s climate long range investigation mapping and prediction here we review this progress based on presentations and discussion at a rst open science meeting of the epilog project environmental processes of the ice age land oceans glaciers held in delmenhorst germany may 1999 we outline key controversies and document protocols for epilog contributions so that a new synthesis of the lgm earth can emerge as an open project of the world s community of scientists 2001 elsevier science ltd all rights reserved

north kona slump submarine flank failure during the early tholeiitic shield stage of hualalai volcano abstract the north kona slump is an elliptical region about 20 by 60 km 1000 km 2 area of multiple geometrically intricate benches and scarps mostly at water depths of 2000 4500 m on the west flank of hualalai volcano two dives up steep scarps in the slump area were made in september 2001 using the rov kaiko of the japan marine science and technology center jamstec as part of a collaborative japan usa project to improve understanding of the submarine flanks of hawaiian volcanoes both dives at water depths of 2700 4000 m encountered pillow lavas draping the scarp and bench slopes intact to only slightly broken pillow lobes and cylinders that are downward elongate dominate on the steepest mid sections of scarps while more equant and spherical pillow shapes are common near the tops and bases of scarps and locally protrude through cover of muddy sediment on bench flats notably absent are subaerially erupted hualalai lava flows interbedded hyaloclastite pillow breccia and or coastal sandy sediment that might have accumulated downslope from an active coastline the general structure of the north kona flank is interpreted as an intricate assemblage of downdropped lenticular blocks bounded by steeply dipping normal faults the undisturbed pillow lava drape indicates that slumping occurred during shield stage tholeiitic volcanism all analyzed samples of the pillow lava drape are tholeiite similar to published analyses from the submarine northwest rift zone of hual lai relatively low sulfur 330 600 ppm and water 0 18 0 47 wt contents of glass rinds suggest that the eruptive sources were in shallow water perhaps 500 1000 m depth in contrast saturation pressures calculated from carbon dioxide concentrations 100 190 ppm indicate deeper equilibration at or near sample sites at water depths of 3900 to 2800 m either vents close to the sample sites erupted mixtures of undegassed and degassed magmas or volatiles were resorbed from vesicles during flowage downslope after eruption in shallow water the glass volatile compositions suggest that the tholeiitic lavas that drape the slump blocks were erupted either 1 early during shield stage tholeiitic volcanism prior to emergence of a large subaerial edifice or alternatively 2 from submarine radial vents during subaerial shield building because no radial vents have been documented on land or underwater for the unbuttressed flanks of any hawaii volcano alternative 1 is favored in comparison to other well documented hawaiian slumps and landslides north kona structures suggest a more incipient slump event with smaller down slope motions and lateral displacements

transgressive and highstand systems tracts and post glacial transgression the east china sea abstract the late pleistocene holocene depositional sequence on the shelf in the east china sea ecs is interpreted on the basis of the analyses of four sediment cores and high resolution seismic reflection sub bottom profiler records along a ne sw across shelf transect sedimentary strata deposited above a lowermost planar erosional surface that was formed during sea level fall of the last glacial are divided into two units along a ne sw across shelf transect changjiang okinawa the lower unit is characterized by seaward dipping tangential clinoforms with a thickness of 30 40 m at mid shelf depths and less than 30 m beneath the outer shelf prograding clinoforms are more obvious in mid shelf environments the upper unit is characterized by an upper transparent layer that is formed into ridge and swale topography the boundary between the upper and lower units is sharp and erosional surficial sediments taken by cores from the central ecs shelf are also divided into two facies a sandy facies consisting of sand or sandy gravel with moderately abundant molluscan shell fragments and a muddy facies comprising mud intercalated with thin sand layers the sandy facies is widely distributed on the middle to outer shelf seafloor and has a measured thickness of 30 cm up to several metres radiocarbon ages of molluscan shells in this sediment are less than approximately 10 ka bp except for ages from basal shell lag deposits which are 10 40 ka bp the muddy facies underlies the sandy facies and has radiocarbon ages of 2 7 2 9 ka bp previous work and 20 38 ka bp this study and tl ages of 27 50 ka bp previous work the boundary between these lithologic units is an erosional sharp contact the sandy and muddy facies are correlated with the upper and lower seismic units respectively the lower unit is characterized by prograding clinoforms and is interpreted to represent deltaic or nearshore tidal ridge sediments of the paleo changjiang river that were deposited during the last glacial lowstand of sea level as a lowstand systems tract the underlying erosional surface is interpreted to be a sequence boundary formed as a regressive marine erosional surface during the fall of sea level the erosional boundary between the lower and upper units is interpreted as a transgressive surface of erosion formed during the subsequent rise of sea level the upper unit has a modern sand ridge topography and is interpreted to represent offshore shelf sand ridges of the transgressive to highstand systems tract

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

marine to non marine sedimentation in the upper miocene evaporites of the eastern betics se spain sedimentological and geochemical evidence abstract several neogene basins in the eastern betics contain a record of thick upper miocene evaporites the inner basins those located distal to the mediterranean coast include evaporite units ranging from the late tortonian to the early messinian whereas the marginal basins those located in the vicinity of the mediterranean coast include evaporite units corresponding to the late messinian that are linked to the salinity crisis the sedimentological and geochemical comparison of the evaporites in the inner and marginal basins enable us to show their differences in the modes of deposition under local structural controls and differentiated palaeogeography in the inner basins of the murcia alicante region a number of evaporite units have been differentiated whose gypsum lithofacies have 1 variable strontium contents with mean values primary gypsum between 1121 and 2380 ppm 2 isotopic compositions of sulphur 34 s ranging from those characteristic of the tertiary marine water 20 3 to 25 5 to those characteristic of the triassic sulphates 8 0 to 16 0 the latter suggesting recycling of the sulphate anion in meteoric waters intermediate values 17 4 to 19 6 are attributed to mixed mother brines and 3 strontium ratios 87 sr 86 sr comprised between 0 70804 and 0 70888 these values range from those of the tertiary marine water to those exceeding the triassic sulphates suggesting additional continental contributions from country rocks and hydrothermal solutions the comparison between the sulphur and strontium isotopic compositions of the sulphates together with the study of the biota present in the marls associated with the gypsum allows us to distinguish between marine continental and mixed units in the marginal basins of the eastern betics where single evaporite units characterized by selenitic gypsum prevail 1 the strontium contents are more homogeneous with mean values primary gypsum between 493 and 625 ppm 2 the isotopic compositions of oxygen 18 o and sulphur 34 s are comprised between 12 2 and 14 8 and between 22 0 and 23 5 respectively and 3 the strontium ratios 87 sr 86 sr vary from 0 70890 to 0 70895 all these isotopic values reveal a marine origin and the lack of contribution of significant continental water during the late messinian evaporite deposition in the betic strait these characteristics are similar to those of the lower evaporite

hydrogeochemical characterization and isotope investigations of a carbonate aquifer of the northern part of the united arab emirates abstract this paper assesses a carbonate aquifer of the wadi al bih area in the northeastern part of uae using hydrogeochemical and isotope approaches analyses of groundwater samples showed that the tds and high concentrations of major cations and anions were encountered in the lower segment of the wadi al bih area most of the groundwater salinity was noticed downstream of the wadi and this may be attributed to the brines that underlie the groundwater and also to the over pumping of groundwater with mostly very low recharge nitrate concentrations observed in the groundwater of the study area may be ascribed to the nature of the karastic aquifer which could lead to the dominance of dissolved oxygen that makes no 3 the dominant form of nitrogen the presence of sulfate in collected groundwater samples is due to the gypsum bearing mudstone in the lower segment of the wadi al bih carbonate aquifer majority of the groundwater samples showed the presence of nacl which indicates the possible influence of the underlying brine the mixing process of brine water and freshwater was noted in the shift from cahco 3 facies to ca cl facies the piper plot showed a ca rich to na rich water type shift which could be explained by a cation exchange process the oxygen and hydrogen isotope compositions in the groundwater samples suggest that the main source of precipitation is the mediterranean sea with some possible effects of the arabian sea a trend of increasing chloride concentration with enrichment of hydrogen isotope compositions suggests that groundwater originated from evaporated raindrops or evaporated surface water the similarity of oxygen and hydrogen isotope compositions between the eastern gravel plain ophiolite and the northern carbonate aquifers indicates the presence of a common source of recharge

coastal sedimentation associated with the december 26 2004 tsunami in lhok nga west banda aceh sumatra indonesia abstract with wave heights of 30 m and runups reaching 50 m a s l and 6 km inland the december 26 2004 tsunami in sumatra was one of the largest tsunamis in recorded human history in this paper we present a description of the event in the lhok nga bay west coast of banda aceh and an interpretation of the tsunami sand deposits mostly based upon grain size analysis the 3 5 km long transect of lampuuk displays two landward fining thinning and sorting sequences the thickest cross sections of the first sequence of deposits 0 1 5 km inland suggest a deposition by three consecutive runups inflows and a final backwash return flow or outflow from 1 5 to 3 5 km inland the record is dominated by the second and highest wave 15 30 m normally graded couplets or triplets of layers were used to identify the runup of each wave the topmost layers interpreted as the backwash deposition describe a seaward sequence of increasing mean grain size and decreasing degree of sorting the local effects of the topography could be identified thickest deposits in the topographic lows 50 80 cm great spatial variations in thickness and upper laminated texture when the sedimentation was limited by steep slopes landward coarsening and very poor sorting at the wave breaking point bimodal grain size distributions reflecting different sources of sediments finally by coupling the longitudinal and vertical trends of the 26 cross sections we propose a model of sediment transport and deposition in a large tsunami wave

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

evolution of 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

seasonal variation of groundwater quality in a part of guntur district andhra pradesh india the area in guntur district andhra pradesh india is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking granite gneisses associated with schists and charnockites of the precambrian eastern ghats underlie the area groundwater samples collected seasonally pre and post monsoons during three years from forty wells in the area were analyzed for ph ec tds ta th ca2 mg2 na k co 3 2 hco 3 cl so 4 2 no 3 and f the chemical relationships in piper s diagram chebotarev s genetic classification and gibbs s diagram suggest that the groundwaters mainly belong to non carbonate alkali type and cl group and are controlled by evaporation dominance respectively due to the influence of semi arid climate gentle slope sluggish drainage conditions greater water rock interaction and anthropogenic activities a comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking especially in post monsoon period us salinity laboratory s and wilcox s diagrams and na used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in post monsoon compared to that in pre monsoon these conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters a management plan is suggested for sustainable development of the area

holocene variability of the kuroshio current in the okinawa trough northwestern pacific ocean abstract cores 255 and b 3gc from the southern and northern okinawa trough respectively were studied for determining the variability of the kuroshio current on centennial scales during the holocene based on detailed ams 14 c dates stable isotope and planktonic foraminiferal distribution the main flow of the kuroshio current was inferred to re enter the okinawa trough at 7 3 calendar cal kyr bp leading to abrupt changes in sedimentation rate remarkably increased abundance of the kuroshio current indicator pulleniatina obliquiloculata increased sea surface temperature sst and depth of thermocline dot during 4 6 2 7 cal kyr bp the abundance of p obliquiloculata sharply decreased corresponding to a decreases in sst and dot implying that the influence of the kuroshio current weakened at that time possibly as a result of the intensified winter monsoon significantly the kuroshio current proxies e g the difference in sst between the southern and northern okinawa trough display periodicities of 1500 yr and 700 800 yr ascribed to the second harmonic of the 1500 yr cycle in oceanic thermohaline circulation during the holocene the holocene events at 0 6 1 7 3 3 4 6 5 9 8 1 9 4 cal kyr bp in the okinawa trough appear to be the most recent manifestation of the millennial scale climate cycle recorded in the north atlantic arabian sea marine sediment cores and greenland ice cores suggesting global climatic tele connections

subaqueous deltaic formation of the old yellow river ad 1128 1855 on the western south yellow sea abstract the yellow river presently flows into the bohai sea but during the period ad 1128 1855 the river called the old yellow river oyr flowed into the western south yellow sea sys where the dispersal of its sediment load was controlled by the interactions among alongshore currents waves and tides and shelf morphology in this study high resolution shallow seismic profiles vibrocores boreholes and water depth data which were obtained during geological surveys in the western sys in recent years are used to examine the depositional pattern and stratigraphic record related to the oyr entering the sea our data reveal compound clinoform morphologies double clinoforms a subaerial subaqueous delta couplet sourced by the oyr in the western sys the subaerial delta comprises the currently onshore delta plain and deltafront extending to 17 m in water depth while the subaqueous delta is composed of a wide gently inclined topset and a relatively narrow steeply sloping foreset stretching seaward about 160 km away from the shoreline and showing a morphological asymmetry with a generally southward deflection relative to the oyr mouth the topset is 25 100 km wide in a shore normal direction at water depths of 10 25 m but is generally less than 4 m thick the foreset is much narrower and thicker than the topset is generally 5 30 km wide at 10 45 m water depth and is mostly 4 16 m thick with a maximum thickness of 20 m it shows seaward dipping internal reflectors generally 0 3 0 5 the rollover points topset foreset transition of the subaqueous clinoform range mostly between 10 and 25 m water depth results of 210pb and 137cs geochronology indicate that maximum sediment accumulation rates 1 06 to 2 16 cm yr correspond to the foreset region with much lower rates in the topset and surrounding shallow sea regions 97 in ad 1128 1855 has accumulated on the subaerial delta and that about 10 16 of the total load on the subaqueous delta our data also reveal that the subaqueous delta related to the oyr is underlain by a large scale clinoform broadly confined to 2 5 9 8 cal kyr bp in age as thick as 4 13 m with seaward dipping lower angled

hydrogeochemical investigation using multivariate analytical methods in esfadan basin eastern iran the chemical analyses of 71 water supply wells in the esfadan area of eastern iran were evaluated using statistical methods to determine the hydrogeochemical processes that control groundwater quality groundwater in the study area is mainly saline na cl type water and statistical analyses show that there are three subgroups of groundwater quality whose differences reflect the influences of geology

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

stratigraphic and three dimensional morphological evolution of the late quaternary sequences in the western bohai sea china controls related to eustasy high sediment supplies and neotectonics abstract the bohai sea is a shallow semi closed gulf basin at the proximal position of the very wide one to several thousand kilometers eastern chinese margin and was persistently impacted by tectonic frameworks its late quaternary stratigraphy provides an excellent natural laboratory for research on the sedimentary processes and evolutionary patterns on flat proximal continental margins with high sediment inputs and how these processes respond to synsedimentary tectonic activity however due to the scarcity of comprehensive sequence stratigraphic studies our understanding of the above processes is limited here we conducted a high resolution sequence stratigraphic study using boomer seismic data with pseudo 3d coverage the seismic data revealed seven seismic units sus a g within the late quaternary stratigraphy including 1 three marine prodeltaic units sus a c g characterized by dipping oblique internal reflections and or lobate structures 2 two terrestrial fluvial lacustrine units sus b and e dominated by heterogeneous reflections 3 an erosional remnant unit sus d with semitransparent reflectors and a lenticular geometry and 4 a ravinement attributed aggradational unit su f based on the extrapolation between the seismic stratigraphy and the onshore sedimentary architecture and well established sequence stratigraphic models our preferential interpretation for the four sets of sus is that they correspond to the highstand lowstand falling stage and transgressive system tracts respectively the seismic geomorphology suggests that the bulk of the accommodation is dominated by the former two which is consistent with the alternative terrestrial and marine succession revealed by previous borehole studies at such a proximal gulf although the accumulation of thick highstand units is not surprising the two thick lowstand units that are bounded above and below by two different subaerial unconformities are exceptional our interpretation indicates that abnormally thick accumulation occurred under subaerial environments during the lowstand period which most likely corresponds to alluvial floodplain progradation aggradation given the western bohai sea is connected to the alluvial north china plain the lower subaerial unconformities of the lowstand units are associated with intensive subaerial most likely fluvial excavation erosion under su e leads to the formation of incised and eroded areas that can be tens of kilometers wide and tens of meters deep cutting into su a or even into su b which are several times greater than the last glacial maximum incised valley at the top of su e such intensive erosion appears to be a crucial contributor to the thick lowstand units as it created more accommodation the great scale of the subaerial incisions is presumably attributed to the fact that the bulk of them evolved from tectonically triggered depressions because their locations are consistent with the ne sw and nw se striking fault populations the tectonic forces also controlled the accumulation by resulting in high relief basement blocks for the pre holocene sedimentation however despite such strong tectonic controls the subsequent deposition filled and leveled the areas between the high relief steep sided basement blocks and eventually resulted in a relatively flat substratum for post lgm deposition suggesting that the geomorphic threshold for geological control at such a proximal gulf was passed because of the high supply environment

recent and modern marine erosion on the new jersey outer shelf abstract recent chirp seismic reflection data combined with multibeam bathymetry backscatter and analysis of grab samples and short cores provide evidence of significant recent erosion on the outer new jersey shelf the timing of erosion is constrained by two factors 1 truncation at the seafloor of what is interpreted to be the transgressive ravinement surface at the base of the surficial sand sheet and 2 truncation of apparently moribund sand ridges along erosional swales oriented parallel to the primary direction of modern bottom flow and oblique to the strike of the sand ridges these observations place the erosion in a marine setting post dating the passage of the shoreface ravinement and the evolution of sand ridges that form initially in the near shore environment also truncated by marine erosion are shallowly buried fluvial channel systems formed during the last glacial maximum and filled during the transgression and a regional reflector r that is 40 kyr depths of erosion range from a few meters to 10 m the seafloor within eroded areas is often marked by ribbon morphology seen primarily in the backscatter data as areas of alternating high and low backscatter elongated in the direction of primary bottom flow ribbons are more occasionally observed in the bathymetry where observed crests exhibit low backscatter and troughs exhibit high backscatter sampling reveals that the high backscatter areas of the ribbons consist of a trimodal admixture of mud sand and shell hash with a bimodal distribution of abraded and unabraded sand grains and microfauna the shell hash is interpreted to be an erosional lag while the muds and unabraded grains are in this non depositional environment evidence of recent erosion at the seafloor of previously undisturbed strata the lower backscatter areas of the ribbon morphology were found to be a well sorted medium sand unit only a few 10 s of cm thick overlying the shelly muddy sandy material concentrations of well rounded gravels and cobbles were also found in eroded areas with very high backscatter and at least one of these appears to be derived from the base of an eroded fluvial channel seafloor reworking over the transgressive evolution of the shelf appears to have switched from sand ridge evolution which is documented to 40 m water depth to more strictly erosional modification at greater water depths we suggest that this change may be related to the reduction with water depth in the effectiveness of sediment resuspension by waves resuspension is a critical factor in the grain size sorting during transport by bottom currents over large bedforms like sand ridges otherwise we speculate displacement of sand by unidirectional currents will erode the seafloor

a multiple approach radiometric age estimate for the rotoiti and earthquake flat eruptions new zealand with implications for the mis 4 3 boundary abstract pyroclastic fall deposits of the paired rotoiti and earthquake flat eruptions from the taupo volcanic zone new zealand combine to form a widespread isochronous horizon over much of northern new zealand and the southwest pacific this horizon is important for correlating climatic and environmental changes during the last glacial period but has been the subject of numerous disparate age estimates between 35 1 2 8 and 71 6 ka all errors are 1 s d obtained by a variety of techniques a potassium argon k ar age of 64 4 ka was previously determined on bracketing lavas at mayor island volcano offshore from the taupo volcanic zone we present a new more precise 40ar 39ar age determination on a lava flow on mayor island that shortly post dates the rotoiti earthquake flat fall deposits of 58 5 1 1 ka this value coupled with existing ages from underlying lavas yield a new estimate for the age of the combined eruptions of 61 0 1 4 ka which is consistent with u th disequilibrium model age data for zircons from the rotoiti deposits direct 40ar 39ar age determinations of plagioclase and biotite from the rotoiti and earthquake flat eruption products yield variable values between 49 6 2 8 and 125 3 10 0 ka with the scatter attributed to low radiogenic ar yields and or alteration and or inheritance of xenocrystic material with inherited ar rotoiti earthquake flat fall deposits occur in new zealand in association with palynological indicators of mild climate attributed to marine isotope stage mis 3 and thus used to suggest an age that is post 59 ka the natures of the criteria used to define the mis 4 3 boundary in the northern and southern hemispheres however imply that the new 61 ka age for the rotoiti earthquake flat eruption deposits will provide the inverse namely a more accurate isochronous marker for correlating diverse changes across the mis 4 3 boundary in the southwest pacific

sedimentation in the yellow river delta part iii seabed erosion and diapirism in the abandoned subaqueous delta lobe abstract historical bathymetry satellite remote sensing and river discharge data have been used to examine the evolution of an abandoned delta lobe in the northern area of the modern yellow river delta results show three stages of evolution in the subaqueous delta slope after lobe abandonment 1 rapid erosion stage 2 slow erosion stage and 3 erosion accumulation adjustment stage according to 1 10 000 bathymetry data and high resolution seismic profiles diapirism in the subaqueous abandoned delta lobe is closely related to seabed erosion which mainly occurs in the middle part of subaqueous delta slope diapirism results from the deformation of soft fine grained prodeltaic sedimentary stratum when the accumulation body on the soft stratum is removed in rapid erosion stage the maximum accumulation centre in the delta lobe during growth coincides with the maximum erosion centre in the delta lobe abandonment phase the diapir body occurs there distinguishing from diapirism in the mississippi delta three stages of the soft stratum deformation and diapirism are established in the yellow river delta the mobile strata and its diapirism are destructive to the offshore engineering facilities

vegetation climate and sea level in the past 55 000 years hanjiang delta southeastern china abstract pollen in quaternary deposits from the subtropical hanjiang delta records three major phases in the local vegetation and climate history during the last 55 000 yr 1 a prevalent cool to temperate and humid climate at ca 24 000 14c yr b p is indicated by abundant pollen of temperate trees including conifers 2 between 20 000 and 15 000 14c yr b p a cold dry environment was associated with low sea level during the last glaciation leading to subaerial exposure weathering and interruption of sedimentation as well as departure from the region of dacrydium and sonneratia 3 a short term expansion of grassland at ca 10 300 14c yr b p reduced the predominant lauraceae fagaceae evergreen forest possibly corresponding to the younger dryas cooling the combined data indicate a maximum sea level rise in the mid holocene 7500 4000 14c yr b p and a marine influence in the late pleistocene at 45 000 20 000 14c yr b p the holocene warming however did not bring back moisture sensitive taxa indicating high seasonal aridity probably caused by renewed monsoon conditions

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

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

groundwater arsenic contamination in manipur one of the seven north eastern hill states of india a future danger manipur state with a population of 2 29 million is one of the seven north eastern hill states in india and is severely affected by groundwater arsenic contamination manipur has nine districts out of which four are in manipur valley where 59 of the people live on 10 of the land these four districts are all arsenic contaminated we analysed water samples from 628 tubewells for arsenic out of an expected total 2 014 tubewells in the manipur valley analyzed samples 63 3 contained 10 g l of arsenic 23 2 between 10 and 50 g l and 40 50 g l the percentages of contaminated wells above 10 and 50 g l are higher than in other arsenic affected states and countries of the ganga meghna brahmaputra gmb plain unlike on the gmb plains in manipur there is no systematic relation between arsenic concentration and the depth of tubewells the source of arsenic in gmb plain is sediments derived from the himalaya and surrounding mountains north eastern hill states were formed at late phase of himalaya orogeny and so it will be found in the future that groundwater arsenic contamination in the valleys of other north eastern hill states arsenic contaminated aquifers in manipur valley are mainly located within the newer alluvium in manipur the high rainfall and abundant surface water resources can be exploited to avoid repeating the mass arsenic poisoning that has occurred on the gmb plains

a geochemical application of the itrax scanner to a sediment core containing eastern mediterranean sapropel units the itrax micro x ray fluoresence xrf core scanner has been applied in a sediment geochemistry investigation the core sections selected contain examples of the organic rich sedimentary units sapropels that form periodically in the eastern mediterranean basin sapropels are visually obvious from their dark coloration but the itrax x radiograph also reveals physical property changes that result mainly from the high pore water content of sapropels a consideration of wavelength dispersive xrf data from discrete samples of the most recent sapropel s1 was made along with the set of elements reported by the itrax instrument s energy dispersive xrf system over core sections containing s1 this allowed selection of a suite of eight inter element ratios or element integrals through which characteristic features of sapropel development and geochemistry were revealed while recognizing that the measured xrf element integrals from the itrax do not have an exact constant relationship with element concentration over changing sediment types this combination of ratios provides significant information for geochemical interpretation these include evidence for i the presence of high corg contents in the visual sapropel from ba ti and br cl ratios ii a thinning of the original sapropel thickness by post depositional oxidation from mn ti and cu ti ratios iii pyrite authigenesis in the residual visual sapropel from fe ti and s cl ratios and the as integral and iv aragonite formation in and around the sapropel from the sr ca ratio these same ratios were then used to interpret itrax data from a deeper section of the same core containing the older sapropel s3 where the same characteristics including the relict post depositional oxidative thinning of the original unit could be identified with only minor differences of detail directions of supply of fe as and cu into the sapropels could be inferred from profile shapes

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

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 sedimentary record of the post glacial transgression on the gulf of cadiz continental shelf southwest spain abstract four seismic units ta to td have been identified from the analysis and interpretation of high resolution seismic profiles in a sector of the gulf of cadiz shelf they constitute a composite seismic unit attributed to the transgressive systems tract tst of the last depositional sequence the earliest transgressive unit was deposited on the outer shelf and represents the distal facies of a coastal deposit a process of shelf partitioning seems to have occurred during the formation of the three later transgressive parasequences the shelf sector offshore from the guadiana river mouth was a high energy environment dominated by storm events by contrast the shelf sector offshore from the donana national park was a low gradient shelf where large barrier island and lagoon systems were formed the sparse occurrence of marine deposits within the tst is a consequence of the episodic nature of the sea level rise the generation and preservation of these transgressive deposits results from the interaction of the following controlling processes 1 relative sea level rise the formation of coastal transgressive deposits is related to intervals of reduced sea level rise or stillstands within a period of continuous sea level rise those sea level changes were probably driven by short term periods of colder climate during the late pleistocene holocene deglaciation the younger dryas interval is the most widely recognised climatic event of this type but probably other events of similar characteristics had the same effect on the glacio eustatic sea level rise 2 sediment supply changes short lived climatic events probably also involved changes in the sediment supply to the continental shelf due to changes in erosion rates and river regimes of the river basin hinterlands 3 effect of the paleophysiography paleogeography the sedimentary environments differentiation processes are associated to the formation of an exposed coastal promontory offshore from the guadiana river mouth and a semi protected embayment offshore from donana national park this coastal configuration was controlled by previous tectonic evolution and influenced the non uniform landward migration of the coastline

hydrogeochemical processes in the groundwater environment of muktsar punjab conventional graphical and multivariate statistical approach understanding the hydrogeochemical processes that govern groundwater quality is important for sustainable management of the water resource a study with the objective of identifying the hydro geochemical processes and their relation with existing quality of groundwater was carried out in an intensively cultivated district of punjab india the study approach includes conventional graphical plots and multivariate analysis of the hydrochemical data to define the geochemical evaluation of aquifer system based on the ionic constituents water types hydrochemical facies and factors controlling groundwater quality the results suggest that different natural hydrogeochemical processes like simple dissolution mixing weathering of carbonate minerals locally known as kankar silicate weathering and ion exchange are the key factors in the pre monsoon which was superseded by leaching processes loaded with anthropogenic inputs in the post monsoon limited reverse ion exchange has been noticed at few locations of the study area especially in pre monsoon periods there was a significant effect of monsoon observed in terms of hardness and the significant amount of area with temporary hardness ca2 mg2 hco 3 type in the pre monsoon switched to permanent hardness domain i e ca2 mg2 cl type by the post monsoon at most factor analyses substantiate the findings of conventional graphical plots and provide greater confidence in data interpretation thus the study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater evaluation