sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

coherence between solar activity and the east asian winter monsoon variability in the past 8000 years from yangtze river derived mud in the east china sea ams 14 c dating and grain size analysis for core pc 6 located in the middle of a mud area on the inner shelf of the east china sea ecs were used to rebuild the holocene history of the east asian winter monsoon eawm the 7 5 m core recorded the history of environmental changes during the postglacial transgression the core s mud section the upper 450 cm has been formed mainly by suspended sediment delivered from the yangtze river mouth by the ecs winter coastal current ecswcc since 7 6 kyr bp using a mathematical method called grain size vs standard deviatiow we can divide the core pc 6 s grain size distribution into two populations at about 28 mu m the fine population 28 mu m is considered to be transported by the ecswcc as suspended loads content of the fine population changes little and represents a stable sedimentary environment in accord with the present situation thus variation of mean grain size from the fine population would reflect the strength of ecswcc which is mainly controlled by the east asian winter monsoon abrupt increasing mean grain size in the mud section is inferred to be transported by sudden strengthened ecswcc which was caused by the strengthened eawm thus the high resolution mean grain size variation might serve as a proxy for reconstruction of the eawm a good correlation between sunspot change and the mean grain size of suspended fine population suggests that one of the primary controls on centennial to decadal scale changes of the eawm in the past 8 ka is the variations of sun irradiance i e the eawm will increase in intensity when the number of sunspots decreases spectral analyses of the mean grain size time series of core pc 6 show statistically significant periodicities centering on 2463 1368 128 106 100 88 91 7678 and 70 72 years the eawm and the east asian summer monsoon easm agree with each other well on these cycles and the east asian monsoon eam and the indian monsoon also share in concurrent cycles in holocene which are in accord with the changes of the sun irradiance c 2005 elsevier b v all rights reserved

role of orbital forcing in east asian monsoon climates during the last 350 kyr evidence from terrestrial and marine climate proxies from core rc14 99 proxy records of northeast asian precipitation marine pollen and northwest pacific sea surface temperatures marine fauna contain concentrations of variance frequency peaks coincident with those of orbital variations eccentricity obliquity and precession time series of these monitors of various components of the east asian monsoon system are coherent with changing solar insolation and climate boundary conditions ice volume snow cover albedo at 41 and 23 kyr frequencies winter sea surface temperature wsst maxima are in phase with global ice volume minima at all three milankovitch frequencies 100 41 and 23 kyr periods wsst maxima are also linearly related to summer insolation at 30 n lagging radiation maxima by 55 3 5 kyr across the precessional frequency band 23 kyr period our east asian monsoon rainfall indicator cryptomeria reaches highest values immediately following summer insolation maxima during periods of low ice volume interglacials across the eccentricity frequency band 100 kyr period cryptomeria maxima are in phase with ice volume minima at the higher frequency of orbital precession monsoon rainfall lags both summer radiation maxima 125 8 kyr and ice volume minima 60 3 8 kyr whereas much of the variation in northwest pacific wsst can be attributed to summer radiation forcing and changes in global climate mechanisms driving east asian monsoon precipitation are more complex involving other possibly internal factors

landslide development at the shores of a dam reservoir wloclawek poland based on 40 years of research this article presents results of our 40 year research on dynamics of a deep rotational landslide developed in clay deposits the landslide is located in a lowland within the shoreline of wloclawek reservoir with little water level variation in dobrzyn on the vistula northern poland it is an old landslide which was active also before the construction of the reservoir our research was initiated in 1970 i e when the river vistula was dammed there currently the landslide covers about 20 000 m2 and has a volume of about 160 000 m3 during the 40 years 3 periods of increased landslide activity were observed the first conspicuously nearly 40 increase in the rate of movements within the central landslide was initiated in the early 1970s and lasted till the early 1980s it coincided with the initial filling of the reservoir and the first years of exploitation of wloclawek reservoir the increase in landslide dynamics was a direct effect of hydrological and morphological changes associated with the damming of the river the next 2 periods of increased landslide activity occurred in 2001 2002 and 2010 2011 the latter was the most spectacular displacement within the central landslide it was recorded between december 2010 and february 2011 and reached 10 0 19 4 m after unusually long lasting heavy rainfall in the summer and autumn of 2010 followed by snowmelt and unfavourable changes in air temperature since march 2011 no movements within the landslide have been recorded

reconstructing recent landslide activity in relation to rainfall in the llobregat river basin eastern pyrenees spain abstract a chronology of recent landslides in the upper basin of the llobregat river eastern pyrenees has been reconstructed from technical reports field reconnaissance and dendrogeomorphological analysis the precipitation conditions responsible for triggering and reactivating landslides have been deduced by analysis of rainfall records from two rain gauges located in the area two different rainfall patterns relate to landslide occurrence i without antecedent rainfall high intensity and short duration rains trigger mostly debris flows and shallow slides developed in colluvium and weathered rocks a rainfall threshold of around 190 mm in 24 h initiates failures whereas more than 300 mm in 24 48 h are needed to cause widespread shallow landsliding ii with antecedent rain moderate intensity precipitation of at least 40 mm in 24 h reactivates mudslides and both rotational and translational slides affecting clayey and silty clayey formations in this case several weeks and 200 mm of precipitation are needed to cause landslide reactivation dendrochronological analysis shows that landslide activity in the eastern pyrenees was relatively low between 1926 and 1959 but has since increased significantly with reactivation now occurring about every 3 years

practical modifications to improve the sledgehammer seismic source we have examined frequency and amplitude changes in high resolution seismic reflection data associated with practical modifications to the sledgehammer method our seismic data acquired at three sites with different near surface geology demonstrate the effects of seating the plate prior to recording of centered versus noncentered impacts of subsurface plate emplacement of various plate surface covers and of aluminum versus steel impact plates impacts on well seated plates produced as much as 4 db higher seismic amplitude than data recorded using unseated plates and increased the ratio of high to low frequencies sledgehammer impacts on the edge of the plate decreased seismic amplitude by 6 to 12 db for frequencies above 100 hz compared to centered impacts placement of the impact plate 1 meter below the ground surface produced a 12 db amplitude increase for frequencies above 130 hz at one test site plates made of either steel alloy or aluminum produced equivalent seismic signals the site dependent nature of some of our results suggests that other investigators may benefit from conducting similar experiments prior to acquiring shallow seismic reflection data when using the sledgehammer source

pleistocene chemical weathering history of asian arid and semi arid regions recorded in loess deposits of china and tajikistan quaternary loess soil sequences in china and tajikistan are valuable archives of the chemical weathering history for arid and semiarid regions of asia the development of new proxies independent of grain size are vital to reconstruct the long term chemical weathering history of eolian deposits in this study we analyze major elemental and rb sr and ba concentrations of decarbonated residue from representative loess and soil units along a north south transect on the chinese loess plateau and compare these concentrations among different grain size fractions results show that most of the elemental abundances and ratios vary considerably among different grain size fractions for both loess and paleosols indicating transport driven compositional differentiation of minerals during subaerial transport however cao na2o mgo tio2 ratios show little variation among different size fractions for the loess soil transect loess soil sequences at lingtai northern china and chashmanigar southern tajikistan for the past 1 50 1 77 ma show lower cao na2o mgo tio2 ratios in soil units than in adjacent loess horizons in good agreement with greater weathering intensity in soils than in loess units the cao na2o mgo tio2 ratio of the decarbonated residue is therefore a reliable proxy for chemical weathering of loess deposits that is independent of grain size the cao na2o mgo tio2 ratios of the lingtai and chashmanigar sections display a relatively regular oscillation within a narrow range in the early pleistocene and a rapid increase in average values and in variance from 0 85 0 6 ma to the present indicating lowered chemical weathering intensity in both the dust source regions and the depositional areas this event may be causally related to the expansion of northern hemisphere ice and or the regional tectonic uplift of high mountains in asia since the mid pleistocene

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

a 25 ka indian ocean monsoon variability record from the andaman sea recent paleoclimatic work on terrestrial and marine deposits from asia and the indian ocean has indicated abrupt changes in the strength of the asian monsoon during the last deglaciation comparison of marine paleoclimate records that track salinity changes from asian rivers can help evaluate the coherence of the indian ocean monsoon iom with the larger asian monsoon here we present paired mg ca and d 18 o data on the planktic foraminifer globigerinoides ruber white from andaman sea core rc12 344 that provide records of sea surface temperature sst and d 18 o of seawater d 18 osw over the past 25 000 years ka before present bp age control is based on nine accelerator mass spectrometry ams dates on mixed planktic foraminifera mg ca sst data indicate that sst was 31c cooler during the last glacial maximum lgm than the late holocene andaman sea d 18 osw exhibited higher than present values during the lateglacial interval ca 19 15 ka bp and briefly during the younger dryas ca 12 ka bp lower than present d 18 osw values during the bolling allerod ca 14 5 12 6 ka bp and during the early holocene ca 10 8 5 5 ka bp are interpreted to indicate lower salinity reflect some combination of decreased evaporation precipitation e p over the andaman sea and increased irrawaddy river outflow our results are consistent with the suggestion that iom intensity was stronger than present during the bolling allerod and early holocene and weaker during the late glaciation younger dryas and the late holocene these findings support the hypothesis that rapid climate change during the last deglaciation and holocene included substantial hydrologic changes in the iom system that were coherent with the larger asian monsoon r 2007 elsevier ltd all rights reserved

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

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

climate correlations between greenland and antarctica during the past 100 000 years the ice cores recovered from central greenland by the grip1 2 and gisp23 projects record 22 interstadial warm events during the part of the last glaciation spanning 20 105 kyr before present the ice core from vostok east antarctica records nine interstadials during this period4 5 here we explore links between greenland and antarctic climate during the last glaciation using a high resolution chronology derived by correlating oxygen isotope data for trapped o2 in the gisp2 and vostok cores we find that interstadials occurred in east antarctica whenever those in greenland lasted longer than 2 000 years our results suggest that partial deglaciation and changes in ocean circulation are partly responsible for the climate teleconnection between greenland and antarctica ice older than 115 kyr in the gisp2 core shows rapid variations in the 18o of o2 that have no counterpart in the vostok record the age depth relationship and thus the climate record in this part of the gisp2 core appears to be significantly disturbed

erosional history of the himalayan and burman ranges during the last two glacial interglacial cycles abstract the results of a clay mineralogy study combined with major element geochemistry strontium neodymium and oxygen isotopes and 14c ams stratigraphy are reported for deep sea gravity cores located in the bay of bengal md77 180 and the andaman sea md77 169 end 0 and 87sr 86sr from holocene and last glacial maximum lgm sediments of fifteen other cores have also been investigated to identify sediment sources and to estimate oceanic sedimentary transport the data show the contribution of three sources 1 ganges brahmaputra rivers 2 irrawaddy river and 3 sediment derived from the western part of the indo burman ranges the dispersion of the detrital material issuing from these sources has been constrained by the geographic distribution of nd and sr isotopic ratios the lgm sediments are characterized by a significant increase of 87sr 86sr small changes in end 0 and a general decrease of smectite illite chlorite which together imply a decrease in weathering intensity the increased 87sr 86sr are attributed to a decrease in chemical weathering which should release preferentially 87sr during weathering processes in the andaman sea sediments smectite illite chlorite and kaolinite quartz ratios combined with a chemical index of alteration cia indicate that the weathering intensity of the irrawaddy river basin is mainly controlled by the summer monsoon rainfall intensity the wet summer monsoons increase vegetation cover in the plains and favor soil development by the production of pedogenic clays smectite and kaolinite

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

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

response of western pacific marginal seas to glacial cycles paleoceanographic and sedimentological features abstract this paper reviews the recent progress in late quaternary studies in five northwestern pacific marginal seas especially the south china sea as an example a series of marginal seas separate asia from the pacific ocean and significantly modify the material and energy flux linkage between land and sea during glacial cycles the sea level induced environmental signal was amplified in the marginal seas giving rise to drastic changes in areas and configurations of these seas and to reorganization of sea water circulation in basins since most of the western pacific marginal seas are influenced by monsoon circulation and some of these are located within the western pacific warm pool the glacial geographic changes have produced a profound impact on regional and global climate for example the decrease of sea area and sea surface temperature sst in the marginal seas was one of the factors responsible for the enhanced aridity of inland china during the glaciation glacial intensification of the winter monsoon and increased seasonality of sst in marginal seas might explain at least partly the apparent discrepancy between the tropical paleotemperature estimations based on terrestrial and open ocean records in this region as the western pacific marginal seas trap terrigenous material supplied by east asia the deep water sedimentation rates there can be one to two orders of magnitude higher than in the open ocean down slope sediment transport is more active when the sea level changes particularly during the deglaciation at least four types of carbonate cycles have been recognized in the western pacific marginal seas and each of those contains environmental signals from the surface and deep sea water as well as from the drainage basin

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

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

chemical weathering of the loess deposits in the lower changjiang valley china and paleoclimatic implications abstract loess deposits xiashu loess are widely distributed in the lower changjiang valley east china and are considered to be of eolian origin with a similar provenance to the well documented loess of north central china the xiashu loess is characterized by strong dissolution of carbonate and considerable weathering of some silicate minerals especially plagioclase chemical mobility of ca sr na mg was observed in the xiashu loess sediments whilst most transition metals are relatively enriched chemical index of variation cia and element ratios of k na and k ca record several paleoclimate events in the lower changjiang valley during the mid late quaternary corresponding with isotopic records in deep sea sediments east china might be governed by stronger summer monsoons than north central china during interglacial periods of the mid late quaternary which may somewhat obscure the record of winter monsoons during glacial periods

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

a field investigation of source parameters for the sledgehammer we examined amplitude and frequency changes in shallow seismic reflection data associated with simple source parameter modifications for the sledgehammer seismic data acquired at three sites with different near surface geology show the potential effects of varying the hammer mass the hammer velocity the plate mass and the plate area at these study sites seismic amplitudes depend on plate surface area and on hammer mass but not heavily on hammer velocity or plate mass furthermore although the total bandwidth of the recorded data was independent of source parameter changes the peak frequency at one site was increased approximately 40 hz by increasing the area of the plate the results indicate that the effects of modifying the source parameters for the sledgehammer are site dependent the experiments described are quick cheap and simple and can be duplicated by others at prospective sites to answer site specific questions

shallow seismic reflection mapping of the overburden bedrock interface with the engineering seismograph some simple techniques where unconsolidated overburden exceeds 20 m in thickness the reflection method may be efficiently used with a 12 channel engineering seismograph to map topography on the overburden bedrock interface as well as possible structure within the overburden the two techniques we suggest are the simplest forms of reflection profiling which can be applied with a minimum amount of equipment which we suggest is a 12 channel enhancement seismograph a 12 geophone array and a hammer source these techniques require good transmission characteristics of the overburden as well as a sharp velocity discontinuity at the overburden bedrock interface for data processing and display a microcomputer is essential

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

mineralogic and climatic interpretations of the luochuan loess section china based on diffuse reflectance spectrophotometry we examined the top 135 m that is the entire pleistocene of the classic luochuan section on the chinese loess plateau with a diffuse reflectance spectrophotometer from the near ultraviolet through the visible and into the near infrared from the reflectance data we calculated sample brightness which with some caveats is a reasonable proxy for magnetic susceptibility mineralogic changes were identified by factor analyzing the first derivative of the percent reflectance data and examining samples with high factor scores two factors which explain about 96 of the cumulative variance are distinguished by the relative proportion of hematite and goethite the minerals that are responsible for the color changes in the loess sequence both hematite and goethite are present in both loess and paleosol but goethite dominates in loess whereas hematite dominates in paleosol the goethite factor exhibits an inverse correlation with magnetic susceptibility the hematite factor exhibits a weak positive correlation with susceptibility paleoclimatic interpretations are drawn from comparison of susceptibility to the concentration of spectrally identified hematite based on this comparison paleosols in the early pleistocene wucheng formation are characterized by conditions that are drier than today a dry summer monsoon whereas later pleistocene paleosols are characterized by a wet summer monsoon

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

a holocene environmental record from the southern yangtze river delta eastern china abstract the holocene sedimentary record of core zx 1 recovered west of mid holocene chenier ridges on the monsoon controlled southern yangtze delta eastern china consists of lagoon salt marsh upper tidal flat and limnic facies reflecting low energy depositional environments holocene deposits mainly originated from the surrounding tai lake drainage basin the temporal variation of most geochemical element percentages corresponds with the climatic phases inferred from the pollen record i e the relatively low values of sio2 na2o cao and high values of al2o3 k2o mgo fe2o3 feo feo fe2o3 and tio2 generally concur with the warm and humid climate and vice versa three geochemical indices al2o3 na2o k2o na2o and cao k2o are found to be sensitive to past precipitation in the monsoon controlled southern yangtze river delta based on fine sediment analysis of core zx 1 the samples deposited under a dry climate with a mean annual precipitation map holocene climatic variation history is reconstructed for the southern yangtze delta from 8000 to 7000 yr bp regional climate demonstrated frequent fluctuations with warm and wet periods 8000 7700 7500 7200 yr bp alternating with cool and less humid periods 7700 7500 7200 7000 yr bp from 7000 to 6000 yr bp the climate was relatively warm and humid since then it had turned cool and dry climaxing in an intense cold event around 4000 yr bp after the cold event it became warm and humid until around 2500 yr bp

modelling of the landslide induced impulse waves in the artvin dam reservoir by empirical approach and 3d numerical simulation abstract due to the burgeoning energy demand in turkey there has been a significant increase in the number of dams and hydroelectric power plants constructed 250 dams have been built in the past 10 years consequently various engineering problems were encountered due to landslides near reservoirs both during and after the construction generally two dimensional 2d and three dimensional 3d empirical equations have been used to calculate the physical properties and propagation of the landslide induced impulse waves however 3d numerical simulation based methodologies are rarely used although they can model the complex geometry of dam reservoirs better using detailed topographic data in this study therefore 3d numerical analysis is carried out for a potential generation of impulse waves using the data of paleo landslide at the artvin dam reservoir ne turkey and the results are compared with the calculated results by empirical equations a finite element method based shear strength reduction analysis fem ssr was performed to analyse the slope stability after the establishment of the correct propagation model the equations were utilised with different input parameters and 3d numerical analysis based simulations to evaluate the characteristics of the impulse waves in the numerical model created using the flow 3d software the drift flux model was used to simulate the probable landslides the reynolds averaged navier stokes equations were used in a free surface modelling technique together with the volume of fluid vof model for simulating the wave generation the renormalised group model rng for viscous flow and k e turbulence model for fluid fluid coupled condition were used as the boundary conditions the results indicated that the values obtained from the proposed empirical equations and 3d numerical analysis were not similar thus if the reservoir geometry is very complex and the wave propagation distance is more than a few kilometers as in this study highly detailed engineering geological studies should be performed to accurately define the boundary conditions and three dimensional numerical analyses should be performed to construct the impulse wave model

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

field comparison of shallow seismic sources near chino california data from a shallow seismic source comparison test conducted in an area with a water table depth in excess of 30 m and near surface velocities less than 330 m s were acquired from 13 different sources at a single site near chino california the sources included sledgehammer explosives weight drop projectile impacts and various buffalo guns a possible reflecting event can be interpreted at about 70 ms at this particular test site the lowly sledgehammer is among the best sources to provide data to see the possible reflection our previous work and that of our colleagues suggests that any source could dominate the comparison categories addressed here given the appropriate set of site characteristics

sea level induced variations in clay mineral composition in the southwestern south china sea over the past 17 000 yr variations in clay mineral composition of sediment cores from the margin and continental slope of the sunda shelf southern south china sea se asia covering the past 17 000 yr reflect changing influences of sediment sources together with clay mineral partitioning processes in shallow waters we identify the deglacial sea level rise as the principal factor driving these changes during the late glacial high values of kaolinite are interpreted to reflect a higher contribution of clays from soils that have formed on the exposed sunda shelf and in the southern archipelagos of indonesia at this time core sites were located in close proximity to the mouths of the sunda shelf palaeo drainage systems on the emerged shelf sundaland the progressive landward displacement of the coastline and breakdown of these vast drainage systems during deglaciation led to a decrease in influence of the kaolinite rich southern sources when the coastline had retreated closely to its present day position in mid holocene times the former dominance of southern sources was replaced by a stronger influence of illite rich sources e g borneo the overriding control of sea level changes on the clay mineral distribution patterns precludes a definite climatic interpretation of clay mineral data in terms of climatic monsoonal changes in such highly dynamic sedimentary environment

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

a view on some hydrological triggering systems in landslides abstract in this paper different types of hydrological triggering systems for debris flows shallow and deeper landslides are described the generation of surface run off and high peak discharges in first order alpine catchments is an important triggering mechanism for debris flows failure conditions in shallow landslides can occur when at a critical depth which is determined by the cohesion of the soil and the slope angle the moisture content in the soil becomes close to saturation resulting in a considerable reduction of soil strength deeper landslides 5 20 m depth are in most cases triggered by positive pore pressures on the slip plane induced by a rising ground water level the assessment of meteorological threshold conditions for shallow landslides 1 2 m needs more detailed meteorological information than for deeper landslides in the analyses of the hydrological triggering systems of deeper landslides the presence of a permeable top layer and fissures has to be taken into consideration

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

the 8k event cause and consequences of a major holocene abrupt climate change abstract a prominent abrupt climate event about 8200 years ago brought generally cold and dry conditions to broad northern hemisphere regions especially in wintertime in response to a very large outburst flood that freshened the north atlantic changes were much larger than typical climate variability before and after the event with anomalies up to many degrees contributing to major displacement of vegetative patterns this 8k event provides a clear case of cause and effect in the paleoclimatic realm and so offers an excellent opportunity for model testing the response to north atlantic freshening has the same general anomaly pattern as observed for older events associated with abrupt climate changes following north atlantic freshening and so greatly strengthens the case that those older events also reflect north atlantic changes the north atlantic involvement in the 8k event helps in estimating limits on climate anomalies that might result in the future if warming caused ice melt and hydrologic cycle intensification at high latitudes lead to major changes in north atlantic circulation few model experiments have directly addressed the 8k event and most studies of proxy records across this event lack the time resolution to fully characterize the anomalies so much work remains to be done

mid holocene sea level highstand along the southeast coast of china various sea level curves have been proposed for the coast of china in the past two decades these sea level curves indicate a complex history of holocene sea level and so the debate on whether or not a higher mid holocene sea level highstand exists in the coast of china has continued this paper aims to re examine the holocene sea level history for the low latitude part of the china coast between 18 n and 32 n by re assessing all the sea level data available from the east to south coasts and separating them according to geological settings in order to examine the influences of global and local factors the reconstructed sea level histories from different coastal sectors of the china coast reveal a certain degree of variability in the timing and height of mid holocene sea level highstand within large river deltas the mid holocene sea level highstand occurred earlier by almost 1000 years than that from other coastal sites the highstand from large river deltas appears also lower in altitude a few metres below the present day sea level due probably to the local factors of subsidence and sediment consolidation in geologically stable coastal sites the highstand is recorded at the same altitude as the present day sea level a 1 2 m higher highstand is found from sites where tectonic uplift is observed

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

an in hole shotgun source for engineering seismic surveys we have conducted several source comparisons involving 12 gauge and 8 gauge buffalo guns a 7 3 kg sledgehammer and a 75 kg weight drop the results are strongly site dependent we found that when the near surface consisted of fine grained water saturated sediments the 12 gauge buffalo gun produced up to two orders of magnitude more energy than the conventional hammer across a broad frequency range under such conditions the gun produced the greatest improvement in energy between 200 and 400 hz where it yielded up to ten times more energy than the 75 kg weight drop this indicates that the buffalo gun may be particularly useful as a shallow reflection seismic source however at sites where the near surface materials were coarse grained and the water table was well below the ground surface the advantages of using an in hole shotgun source as opposed to a hammer or weight drop were minimal nevertheless in many areas we believe that the buffalo gun is an excellent source for engineering seismic surv

seasonal cycles of manganese and cadmium in coral from the galapagos islands manganese to calcium ratios in corals from the eastern and western galapagos demonstrate regional differences in seasonal trace metal cycling the variability of trace metal to calcium ratios within the galapagos islands points to their unique geographic setting as a major factor this region is influenced by several major oceanic currents e g the south equatorial current the equatorial undercurrent and the panama or el nino current and by extremely intense upwelling manganese to calcium ratios in a banded coral pavona clavus from isabela island the westernmost island in the galapagos have distinct seasonal cycles for the non el nino southern oscillation enso years 1946 1950 with lower ratios following intensified seasonal upwelling cadmium calcium ratios show less distinct seasonal cycles the near moderate enso event in 1951 is marked by the disruption of seasonal cycles in mnca and cdca ratios in contrast corals from islands further east in the galapagos hood island 1964 1973 linn et al 1990 san cristobal 1965 1979 shen and sanford 1990 have stronger seasonal cdca signals with higher ratios following seasonal upwelling and less distinct seasonal cycles in mnca ratios one half year out of phase with cdca variations average mnca ratios are lower for these corals from locations further east indicating that urvina bay appears to have an additional localized source of mn shen and sanford 1990 in general these regional variations in seasonal trace metal cycling are consistent with coral stable isotope signals and with their geographic locations these variations are important to consider in using coral records to reconstruct and interpret oceanographic events occurring prior to historical records

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

implications of late eocene to early miocene clay mineral assemblages in mcmurdo sound ross sea antarctica on paleoclimate and ice dynamics abstract the clay mineral assemblages of upper eocene to lower miocene sediments recovered at the ciros 1 and mssts 1 drill sites on the mcmurdo sound shelf antarctica were analyzed in order to reconstruct the cenozoic antarctic paleoclimate and ice dynamics the assemblages are dominated by smectite and illite with minor amounts of chlorite and kaolinite the highest smectite amounts and best smectite crystallinities occur in the upper eocene part of ciros 1 below 425 445 mbsf they indicate that during their deposition chemical weathering conditions prevailed on the nearby continent large parts of east antarctica were probably ice free at that time but some glaciers reached the sea and contributed to the glaciomarine sedimentation in contrast only minor total amounts of smectite are present in oligocene and younger sediments due to the shift to mainly physical weathering on an ice covered antarctic continent however relative smectite percentages rise to more than 60 during two late oligocene intervals ca 27 5 26 2 and 25 0 24 5 ma and during one early miocene interval starting at ca 23 3 ma these intervals are characterized by ice masses coming probably from the south where volcanic rocks acted as a source as also indicated by the composition of the sand and gravel fractions during the other intervals the ice came from the west where the physical erosion of basement rocks and sedimentary rocks of the beacon supergroup in the transantarctic mountains provided high illite concentrations because the two drill sites are only 4 km apart their clay mineral records can be correlated this led to a new interpretation of the oligocene paleomagnetic data of the mssts 1 site and to a more detailed lithostratigraphic correlation of the miocene parts of the cores

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

the seismic signature of rain abstractrain has long been a problem for land seismic surveys in terms of its effect on the condition of the surface and near surface and also due to the seismic noise it creates when raindrops hit the ground i measured the seismic signature of rainfall using water dripped from height using a pipette and natural rain in winchester england over a three month period my results indicated that rain noise is concentrated at frequencies of greater than 80 hz with a detectable range of less than 1 m drops of water landing directly on a geophone result in events with amplitudes nearly 30 times larger than those landing next to the geophone items placed on the surface of the ground such as cables absorb the energy of the impact and reduce the level of the resulting seismic noise burying geophones results in attenuation of rain noise by between 7 7 and 8 6 db 0 1 m but given the effort required to bury geophones it is likely that data processing algorithms or the placement of vibration absorbent ma

holocene paleoclimatic reconstruction based on mud deposits on the inner shelf of the east china sea abstract we present a paleoclimatic reconstruction of the mid holocene by geochemical analysis of a sediment core mz01 retrieved from the mud area of the inner continental shelf of the east china sea ecs our results show that the downcore geochemical variations in the sediments of the core provide a link to historical climate changes relatively higher ratios of cia ba sr and a lower ratio of cao mgo coincide with major regional warm and humid climate episodes and vice versa therefore these geochemical indicators are useful in reconstructing the paleoclimate in eastern china using the geochemical records of core mz01 which are well constrained by ams 14c dating we found that from 8300 yr bp to 4200 yr bp the regional climate was moderately warm and humid and from 4200 yr bp to 2300 yr bp the climate was cool and dry with large fluctuations between cool dry 3700 yr bp 2850 yr bp and 2400 yr bp and warm wet 3250 yr bp and 2650 yr bp since 2300 yr bp our records indicate that the climate has gradually become warmer although a cold event centered at around 250 yr bp the little ice age lia interrupted this warming trend we also found significant 238 yr cycles in our cia records that imply a possible solar influence on the regional climate changes since the mid holocene

variations in temperature and salinity of the surface water above the middle okinawa trough during the past 37 kyr abstract east china sea ecs is an important climate modulator of east asia in the last glacial period the global sea level the path and strength of the kuroshio current experienced great changes combined with the variable volume of fresh run off input they made the hydrographic situation in the ecs quite different from nowadays based on high resolution alkenone sea surface temperature sst and oxygen isotope composition of planktonic foraminifera globigerinoides sacculifer we reconstructed paleo sea surface salinity sss of a long piston core dgks9604 retrieved from the middle okinawa trough of the eastern ecs the 18o and sst records display significant variations with global ice volume synchrony of the millennial scale climate events like yd and heinrich events of core dgks9604 to the ice core from the northern high latitudes and the synchroneity of deglacial warming with the bolling allerod warming suggests a strong coupling of the sst variations in the marginal pacific ocean to the climate of the north atlantic most likely through the asian monsoon atmospheric circulation the ecs documents lowest sst 22 c at 26 cal kyr bp and 3 c sst difference between the full glaciation 26 to 19 cal kyr bp and mid to late holocene 6 cal kyr bp present the overall long term hydrographic variations in the middle okinawa trough are controlled by temporal and spatial variations in i the intensity and position of the kuroshio current ii intensity of the asian summer monsoon and iii sea level fluctuations coupled with ecs topography saline surface water dominated over the middle okinawa trough during early pre glaciation 37 to 31 cal kyr bp last deglaciation 19 to 11 6 cal kyr bp and mid to late holocene 6 cal kyr bp present whilst freshened surface water prevailed during the late pre glaciation 31 to 26 cal kyr bp full glaciation 26 to 19 cal kyr bp and early holocene 11 6 to 6 cal kyr bp

clay mineral distribution in surface sediments of the south atlantic sources transport and relation to oceanography abstract surface samples mostly from abyssal sediments of the south atlantic from parts of the equatorial atlantic and of the antarctic ocean were investigated for clay content and clay mineral composition maps of relative clay mineral content were compiled which improve previous maps by showing more details especially at high latitudes large scale relations regarding the origin and transport paths of detrital clay are revealed high smectite concentrations are observed in abyssal regions primarily derived from southernmost south america and from minor sources in southwest africa near submarine volcanoes of the antarctic ocean south sandwich bouvet island smectite contents exhibit distinct maxima which is ascribed to the weathering of altered basalts and volcanic glasses the illite distribution can be subdivided into five major zones including two maxima revealing both south african and antarctic sources a particularly high amount of mg and fe rich illites are observed close to east antarctica they are derived from biotite bearing crystalline rocks and transported to the west by the east antarctic coastal current chiorite and well crystallized dioctaedral illite are typical minerals enriched within the subantarctic and polarfrontal zone but of minor importance off east antarctica kaolinite dominates the clay mineral assemblage at low latitudes where the continental source rocks west africa brazil are mainly affected by intensive chemical weathering surprisingly a slight increase of kaolinite is observed in the enderby basin and near the filchner ronne ice shelf the investigated area can be subdivided into ten large scale clay facies zones with characteristic possible source regions and transport paths clay mineral assemblages of the largest part of the south atlantic especially of the western basins are dominated by chlorite and illite derived from the antarctic peninsula and southernmost south america and supported by advection within the circumantarctic deep water flow in contrast the east antarctic provinces are relatively small assemblages of the eastern basins north of 30 s are strongly influenced by african sources controlled by weathering regimes on land and by a complex interaction of wind river and deep ocean transport the strong gradient in clay mineral composition at the brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins

deglacial meltwater pulse 1b and younger dryas sea levels revisited with boreholes at tahiti reconstructing sea level changes during the last deglaciation provides a way of understanding the ice dynamics that can perturb large continental ice sheets the resolution of the few sea level records covering the critical time interval between 14 000 and 9 000 calendar years before the present is still insufficient to draw conclusions about sea level changes associated with the younger dryas cold event and the meltwater pulse 1b mwp 1b we used the uranium thorium method to date shallow living corals from three new cores drilled onshore in the tahiti barrier reef no significant discontinuity can be detected in the sea level rise during the mwp 1b period the new tahiti sea level record shows that the sea level rise slowed down during the younger dryas before accelerating again during the holocene

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

clay mineral assemblages in the northern south china sea implications for east asian monsoon evolution over the past 2 million years abstract clay mineral assemblages at odp site 1146 in the northern south china sea are used to investigate sediment source and transport processes and to evaluate the evolution of the east asian monsoon over the past 2 myr clay minerals consist mainly of illite 22 43 and smectite 12 48 with associated chlorite 10 30 kaolinite 2 18 and random mixed layer clays 5 22 hydrodynamic and mineralogical studies indicate that illite and chlorite sources include taiwan and the yangtze river that smectite and mixed layer clays originate predominantly from luzon and indonesia and that kaolinite is primarily derived from the pearl river mineral assemblages indicate strong glacial interglacial cyclicity with high illite chlorite and kaolinite content during glacials and high smectite and mixed layer clay content during interglacials during interglacials summer enhanced monsoon southwesterly currents transport more smectite and mixed layer clays to site 1146 whereas during glacials enhanced winter monsoon northerly currents transport more illite and chlorite from taiwan and the yangtze river the ratio smectite mixed layers illite chlorite was adopted as a proxy for east asian monsoon variability higher ratios indicate strengthened summer monsoon winds and weakened winter monsoon winds during interglacials in contrast lower ratios indicate a strongly intensified winter monsoon and weakened summer monsoon during glacials spectral analysis indicates the mineral ratio was dominantly forced by monsoon variability prior to the development of large scale glaciation at 1 2 myr and by both monsoon variability and the effects of changing sea level in the interval 1 2 myr to present

rainfall ground water flow and seasonal movement at minor creek landslide northwestern california physical interpretation of empirical relations simple ground water flow analyses can clarify complex empirical relations between rainfall and landslide motion here we present detailed data on rainfall ground water flow and repetitive seasonal motion that occurred from 1982 to 1985 at minor creek landslide in northwestern california and we interpret these data in the context of physically based theories we find that landslide motion is closely regulated by the direction and magnitude of near surface hydraulic gradients and by waves of pore pressure caused by intermittent rainfall diffusive propagation of pore pressure waves accompanies downward ground water flow along nearly vertical hydraulic gradients that exist in most of the landslide field data combined with a pore pressure diffusion analysis show that single rainstorms typically produce short period waves that attenuate before reaching the landslide base in contrast seasonal rainfall cycles produce long period waves that modify basal pore pressures but only after time lags that range from weeks to months such tune lags can depend on antecedent moisture storage and can explain variable delays between the onset of the wet season and seasonal landslide motion limit equilibrium analysis shows that when seasonal pressure waves reach the landslide base they establish a critical distribution of effective stress that delicately triggers landslide motion the critical effective stress balance is extremely sensitive to the direction and magnitude of hydraulic gradients although pervasively downward gradients instigate seasonal motion we infer from theory and limited data that ground water also may circulate locally in near surface cells the circulation can further reduce the landslide s frictional strength particularly in areas of nearly horizontal ground water flow that occur beneath steep faces of hummocks hummocky topography that results from slope instability may therefore cause ground water flow that perpetuates instability

deep sea mud in the pacific ocean as a potential resource for rare earth elements world demand for rare earth elements and the metal yttrium is rapidly increasing an analysis of more than 2 000 seafloor sediment samples suggests that deep sea mud constitutes a highly promising giant resource for these elements

consistent dating for antarctic and greenland ice cores we are hereby presenting a new dating method based on inverse techniques which aims at calculating consistent gas and ice chronologies for several ice cores the proposed method yields new dating scenarios simultaneously for several cores by making a compromise between the chronological information brought by glaciological modeling i e ice flow model firn densification model accumulation rate model and by gas and ice stratigraphic constraints this method enables us to gather widespread chronological information and to use regional or global markers i e methane volcanic sulfate beryllium 10 tephra layers etc to link the core chronologies stratigraphically confidence intervals of the new dating scenarios can be calculated thanks to the probabilistic formulation of the new method which takes into account both modeling and data uncertainties we apply this method simultaneously to one greenland ngrip and three antarctic epica dome c epica dronning maud land and vostok ices cores and refine existent chronologies our results show that consistent ice and gas chronologies can be derived for depth intervals that are well constrained by relevant glaciological data in particular we propose new and consistent dating of the last deglaciation for greenland and antarctic ice and gas records

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

numerical simulation of groundwater flow for a coastal plain in japan data collection and model calibration using a three dimensional finite element model this study characterizes groundwater flow in a costal plain of the seto inland sea japan the model characterization involved taking field data describing the aquifer system and translating this information into input variables that the model code uses to solve governing equations of flow geological geometry and the number of aquifers have been analyzed based on a large amount of geological hydrogeological and topographical data results of study demonstrate a high correlation between the ground surface elevation and the groundwater level in the shallow coastal aquifer for calibrating the numerical groundwater model the groundwater flow was simulated in steady state in addition the groundwater level and trend in the transient state has also been elucidated the numerical result provides excellent visual representations of groundwater flow presenting resource managers and decision makers with a clear understanding of the nature of the types of groundwater flow pathways results build a base for further analysis under different future scenarios

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

sedimentation dynamics in the east china sea elucidated from and sedimentation dynamics in the east china sea was investigated based on profiles and inventories of 210 pb 137 cs and ex 239 240 pu in sediment cores collected from various settings in this marginal sea the derived sedimentation rates vary by two orders of magnitude from 2 to 0 02 cm yr y1 and generally decrease southward along the inner shelf and eastward offshore this pattern is consistent with the dispersal of yangtze river derived sediments by the current and tidal systems y2 y1 the weighted mean sedimentation rate over the shelf ca 0 3 g cm yr appears to be higher than fluvial inputs from the y2 y1 yangtze river and taiwan 0 14 g cm yr the discrepancy can be reduced by considering the effect of sediment mixing which renders sedimentation rates overestimated and the possibility of additional sediment input from the yellow river s dispersal system spatial variations of the observed nuclide inventories in sediments suggest extensive sediment redistribution boundary scavenging of 210 pb and large inputs of 137 cs and 239 240 pu from yangtze river s drainage basin

pulleniatina minimum events in the andaman sea ne indian ocean implications for winter monsoon and thermocline changes abstract the late quaternary record of pulleniatina obliquiloculata was investigated from two well dated sediment cores from the andaman sea ne indian ocean to examine its paleoceanographic significance and the presence of the pulleniatina minimum events pme in the western north pacific as in the pacific our study shows that pmes exist in the indian ocean albeit with a lower intensity the holocene pme occurs between 4 5 and 3 0 cal ka bp with a considerable reduction in p obliquiloculata abundance and which matches well with the pacific records influenced by the kuroshio current additionally two significant minimum events of p obliquiloculata are also seen during the younger dryas yd and late last glacial maximum lgm 20 18 cal ka bp overall the pmes of the andaman sea are not current driven events like in the western pacific margin either by the weakening of the kuroshio current or reduced winter ssts the pmes of the andaman sea are characterised by lower abundances of thermocline species indicating the increased depth of the thermocline dot and reduced winter ssts mainly during the minimum events of the yd and late lgm the high ssts during the holocene pme make this event a mystery however the presence of pmes in the andaman sea suggests that these events are not confined to areas influenced by the kuroshio current but may be responding to a broad scale oceanographic climatic process or mechanism which needs to be explored with a detailed study

field comparison of shallow seismic sources choosing a seismic source for a shallow reflection survey can be the most pivotal decision for the engineering geophysicist the intent of this paper is to present data that will assist in selection of a shallow seismic source best meeting the goals within the constraints of specific projects particularly in areas where the water table is near the surface the data were collected and displayed as seismograms and amplitude spectra for 15 different shallow seismic sources in october 1985 at a single site in new jersey they show the different characteristics of each source considering the almost three orders of magnitude difference in total source energy between the largest and smallest source we chose a display format that presented the data as objectively as possible while still allowing direct source to source comparisons two strong reflections at about 100 and 130 ms probably mark the top and bottom of a clay unit 80 m below the surface at this site our previous work and that of our colleagues

a preliminary study of a sediment core drilled from the mud area on the inner shelf of the east china sea implications for paleoclimatic changes during the fast transgression period 13 ka b p 8 ka b p abstract a 35 30 m long core mz02 that was recovered from a water depth of 32 4 m from the inner shelf mud deposit of the east china sea is analyzed to determine its sedimentary characteristics color reflectance clay mineral content element geochemistry components and ams 14 c dating to investigate the sedimentation rate sediment provenance and paleoclimate evolution during the fast transgression period rare earth element and clay mineral proxies indicate that mixed provenance sediment accumulated in the foreshore nearshore region at the beginning of the fast transgression period with a higher sedimentation rate of 5 58 m ka from the early holocene 9 8 9 5 ka b p the sedimentation rate declined by approximately 1 73 m ka and the sediment provenance obviously changed the silt fraction resembled that of taiwan s mountainous rivers and the clay fraction was primarily transported from the yangtze river a multiple proxy system including sediment redness a chemical index of alteration cia clay mineral ratio smectite kaolinite and major and trace element ratios cao mgo ba sr also provides a good paleoclimate record during the fast transgression period which can be divided into three units all the proxies barely changed during unit i 12 88 10 85 ka b p revealing that the climate remained relatively stable obvious fluctuations occurred during unit ii 10 85 10 05 ka b p and the temperature kept decreasing for more than 1 ka until the younger dryas event showing a notable regional response to global climate changes a continuous warming trend resumed again during unit iii 10 05 8 15 ka b p which may mark the threshold of the holocene warm period in addition we find significant 80 yr 89 yr and 100 yr cycles in the cia cao mgo and ba sr records which imply the possible influence of solar activity on regional climate change during the fast transgression period in the asian margin region

analysis of baishuihe landslide influenced by the effects of reservoir water and rainfall since the impoundment of the three gorges reservoir in june 2003 a number of new landslides have occurred and existing landslides have been made worse the 1 260 104 m3 baishuihe landslide located at 56 km west of the three gorges dam began to deform more noticeably after the first impoundment in early july 2003 the sliding of the two blocks comprising the landslide one an active block and the other a relatively stable block became apparent after approximately 5 years of monitoring field recordings show that the landslide displacement is affected by the combined effects of the rainfall and water level in the reservoir these effects have been investigated in the present paper including the deformation characteristics movement pattern direction displacement and velocity earmarking the temporal evolution of the active block based on a practical creep model of a large rock slide alert velocity thresholds for pre alert alert and emergency phases have been computed corresponding to the imminence of failure the alert velocity thresholds are being proposed to be included as a part of an early warning system of an emergency plan drawn up to minimize the adverse impact in the event of landslide failure the emergency plan is intended to be implemented as a risk management tool by the relevant authorities of the three gorges reservoir in the near future

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

glacier retreat in new zealand during the younger dryas stadial the younger dryas a period of sudden cooling in the northern hemisphere about 12 900 years ago is perhaps the best known example of abrupt climate change but the global extent of the younger dryas is a topic of intense debate particularly in the record of glacial behaviour in new zealand a new reconstruction of the growth and retreat patterns of glaciers in the southern alps in new zealand at the time of the younger dryas supports the suggestion that temperature reductions in the north caused warming and glacial retreat in the southern hemisphere through a series of climate feedbacks the younger dryas during which northern hemisphere temperatures cooled drastically in just a few years is perhaps the best known example of abrupt climate change but its global extent is under debate particularly in the record of glacial behaviour in new zealand these authors present evidence for glacial retreat in new zealand during the younger dryas supporting the hypothesis that northern hemisphere climate changes caused southern hemisphere warming through a series of climate feedbacks millennial scale cold reversals in the high latitudes of both hemispheres interrupted the last transition from full glacial to interglacial climate conditions the presence of the younger dryas stadial 12 9 to 11 7 kyr ago is established throughout much of the northern hemisphere but the global timing nature and extent of the event are not well established evidence in mid to low latitudes of the southern hemisphere in particular has remained perplexing1 2 3 4 5 6 the debate has in part focused on the behaviour of mountain glaciers in new zealand where previous research has found equivocal evidence for the precise timing of increased or reduced ice extent1 2 3 the interhemispheric behaviour of the climate system during the younger dryas thus remains an open question fundamentally limiting our ability to formulate realistic models of global climate dynamics for this time period here we show that new zealand s glaciers retreated after 13 kyr bp at the onset of the younger dryas and in general over the subsequent 1 5 kyr period our evidence is based on detailed landform mapping a high precision 10be chronology7 and reconstruction of former ice extents and snow lines from well preserved cirque moraines our late glacial glacier chronology matches climatic trends in antarctica southern ocean behaviour and variations in atmospheric co2 the evidence points to a distinct warming of the southern mid latitude atmosphere during the younger dryas and a close coupling between new zealand s cryosphere and southern high latitude climate these findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the north atlantic led to a strong interhemispheric thermal gradient8 during late glacial times in turn leading to increased upwelling and co2 release from the southern ocean9 thereby triggering southern hemisphere warming during the northern younger dryas

paleocurrent analysis for the late pleistocene holocene incised valley fill of the yangtze delta china by using anisotropy of magnetic susceptibility data abstract anisotropy of magnetic susceptibility ams analysis has been conducted on samples from borehole core cm 97 from the yangtze river changjiang incised valley fill china to determine the paleocurrent directions to help in reconstructing sedimentary paleoenvironments borehole cm 97 consists of fluvial unit 1 estuarine units 2 6 and deltaic units 7 9 sediments after the last glacial maximum in ascending order the ams results show that the paleocurrent directions for the tide dominated estuarine and deltaic sediments were westerly or northwesterly directed flood tide dominated but give no definite trend for the fluvial sediments comparison between the paleocurrent directions inferred from primary sedimentary structures and in situ ams data shows that they are in good agreement confirming the applicability of ams as a good paleocurrent indicator for sediments deposited in coastal tide dominated environments considering that these sediments were strongly tide influenced and the tidal pattern since 12 kyr bp has not changed significantly we think that the westerly or northwesterly current direction most probably resulted from flood tidal currents and the sedimentary paleoenvironment was a flood tide dominated estuary or delta additionally it has been found that downhole changes of some ams parameters including the mean magnetic susceptibility k the corrected anisotropy degree p j and the magnetic foliation f clearly mark the defined stratigraphic boundaries in the borehole this further extends the validity of ams as a good stratigraphic marker in addition to its long known credibility as a sensible paleocurrent recorder

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

pyrite sulfur isotopes constrained by sedimentation rates evidence from sediments on the east china sea inner shelf since the late pleistocene abstract isotopic compositions of coeval sulfide and sulfate have been widely employed to reconstruct the seawater chemistry evolution over geologic time however these signals can be modulated by other factors such as the sedimentation rate here we present a data set of pyrite sulfur isotopes 34spy derived from 60 m drilled core sediments deposited on the inner shelf of the east china sea since 16 5 ka the resulting 34spy values range from 38 2 to 15 0 vienna canyon diablo troilite v cdt representing a range of 53 2 freshwater deposition before 12 3 ka produced a limited pyrite abundance and 34spy values that fall within the typical range of freshwater environments after the marine incursion in the study area at 12 3 ka variations in the 34spy values become significantly correlated with sedimentation rates srs r 0 78 p 0 suggesting that srs exert controls on 34spy values we propose that these sedimentary controls are expressed by modulating the connectivity between porewaters and the overlying seawater low srs tend to form an open diagenetic system in which the pyrites are able to preserve the large biological fractionations associated with microbial sulfate reduction and disproportionation in contrast high srs favour a restricted diagenetic system in which the distillation of porewater sulfate produces pyrites enriched in 34s masking the magnitude of biological fractionation during microbial sulfur cycling these findings highlight the critical effect of the local sedimentation regime on pyrite sulfur isotopic compositions especially within shallow depositional environments over geologic time

timing of the late glacial climate reversal in the southern hemisphere using high resolution radiocarbon chronology for kaipo bog new zealand abstract the pattern of climate change in the southern hemisphere during the younger dryas yd chronozone provides essential constraint on mechanisms of abrupt climate change only if accurate high precision chronologies are obtained a climate reversal reported previously at kaipo bog new zealand had been dated between 13 600 and 12 600 cal yr b p and appeared to asynchronously overlap the yd chron but the chronology based on conventionally radiocarbon dated bulk sediment samples left the precise timing questionable we report a new high resolution ams 14 c chronology for the kaipo record that confirms the original chronology and provides further evidence for a mid latitude southern ocean cooling event dated between 13 800 and 12 400 cal yr b p 2 range roughly equivalent to the antarctic cold reversal

sedimentation on the inner shelf of the east china sea magnetic properties diagenesis and paleoclimate implications abstract high resolution magnetic analysis was performed on the 19 22 m core md06 3040 27 43 3663 n 121 46 8822 e 46 m water depth from the east china sea ecs inner continental shelf which was recovered during the images xiv md155 marco polo 2 cruise of the r v marion dufresne ipev magnetic grains are mainly transported to the inner shelf from erosion on mainland china delivered by the yangtze river nine 14 c ams dates indicate that the core spans about the last 10 4 ka with an average sedimentation rate of nearly 2 mm yr the primary magnetic mineral assemblage of the uppermost sediments contains magnetite with some contributions from hematite and greigite two main stepwise changes are observed in the magnetic mineral content due to post depositional reductive diagenesis the first occurs from the top of the core to 3 5 m and is characterized by reduction of both the magnetite and hematite contents the second occurs at 8 45 9 m and is characterized by a loss of fine grained ferrimagnetic material variations in the magnetic mineral content of this core are related to geochemical and redox environment changes in the ecs through the oxic suboxic sulfidic methanic zones from top to bottom despite significant reduction of a large amount of the ferrimagnetic mineral content due to diagenesis intervals characterized by lower magnetic mineral concentrations and higher coercivities are still identified at 0 45 0 6 1 5 1 7 2 9 3 1 4 4 4 7 5 3 5 7 5 9 6 1 and 8 2 8 4 ka these intervals are in phase within dating errors these intervals are in phase with weak summer monsoon events which indicate that a relationship between magnetic results and paleoclimatic events is partially preserved

landslide monitoring for risk mitigation by using corner reflector and satellite sar interferometry the large landslide of carlantino italy abstract the use of satellite synthetic aperture radar interferometry insar for monitoring ground instability due to landslide events although advantageous over large spatial scales still poses challenges related to the recurrently complex kinematics of the phenomena or to the unfavorable settings of the examined areas with respect to steep topography and vegetated land cover this paper presents results obtained by using multi temporal insar techniques with high resolution terrasarx tsx data for monitoring the carlantino landslide located in the daunian subapennine apulia region southern italy on a slope overlooking a water reservoir and subjected to several investigations and consolidation works the targets detected by using persistent scatterer interferometry psi correspond to urban structures or peri urban walls and guard rails while the landslide body is almost completely devoid of stable targets due to the widespread vegetation and variable land cover to allow stability monitoring a network of six corner reflectors cr was designed and deployed over the landslide test site the tsx images were analyzed by using both the psi processing and a procedure based on the double difference analysis of insar phase values on the cr pixels despite residual noise and the loss of 2 crs due to vandalism the processing allowed verifying the stability of the upper and central part of the landslide body and relating indirectly the movements at the toe of the landslide to the water level fluctuations of the reservoir finally this experiment suggests some recommendations and guidelines in planning cr deployment in complex landslide sites

monitoring of landslides in the brda river valley in koronowo polish lowlands the paper discusses landslides investigated in a brda river valley in the region of the town koronowo near bydgoszcz kujawsko pomorskie voivodeship in the polish lowlands due to morphologic and geologic setting the area is prone to slope instability out of 32 identified landslides 9 were selected for detailed examination to register a nature and rate of failures a complex monitoring system was installed on slopes where the selected landslides resulted in damages to municipal infrastructure the system was facilitated with inclinometers and piezometers supported by a network of gps rtk geodetic benchmarks as well as with a recording station the performed examination revealed that the most unfavourable arrangement of the layers is when under a non cohesive soil lies a cohesive impermeable layer the landslides are rather shallow ones except for two incidents with slow rate of displacement the landslide triggering factor is water originating from precipitation and snow melting influence of water was especially significant in early spring 2011 due to the combined effect of snow melting and infiltration of thawing water originating from the former as well as exceptionally high rainfalls the influence of hydrologic conditions on slope deformations is complex there is a significant time lag between a movement initiation and unfavourable hydrometeorological conditions that is exemplified with the landslide that was initiated in february march 2011 in consequence of atmospheric conditions of november december 2010 the results formed the background for inventing engineering treatment measures aiming at current remedial stabilisation of slopes and mitigation of possible landsliding in the future

effects of the near field on shallow seismic studies seismic studies in the near surface typically involve path lengths that are on the order of a wavelength however most investigators extrapolate seismic imaging and parameter extraction techniques to the near surface without incorporating the near field in their processing approach for such short path lengths we find that the near field is strongly present in the recorded waveforms which consequently biases seismic parameter estimation such as q measurement to suppress the near field effects we examined the challenges of near field removal and the issues involving the accurate modeling of the near field using the mathematical expression for a source monopole which describes an elastic impact source typically used in shallow seismic studies we modeled the near and far field terms of the waveform with distance in a homogeneous elastic medium for thiscase we found that the near field can be suppressed through frequen cy domain or polarization filtering however in heterogeneous media the near