aftsolve a program for multi kinetic modeling of apatite fission track data aftsolve is a computer program for deriving thermal history information from apatite fission track data it implements a new fission track annealing model that takes into account the known kinetic variability among different apatite species to fully utilize this model a fission track worker must obtain data that can be used to infer the kinetic characteristics of each apatite grain from which a measurement was taken such data can consist of etch figure lengths or chemical composition the benefit of this overall approach is that it allows useful information to be derived from previously unusable analyses extends the practical range of geological temperatures constrained by fission track analyses and increases overall confidence in model predictions aftsolve also incorporates the effects of fission track orientation relative to the apatite crystallographic c axis variation in initial track length and the biasing effect of 2 5 2 cf irradiation for enhancing confined horizontal track length detection aftsolve is written for windows operating systems and has a graphical interface that allows interactive input of thermal histories and real time generation of estimates for fission track length distributions and ages for up to six simultaneously modeled kinetic populations it also includes procedures for estimating the range of time temperature histories that are statistically consistent with a data set and constraints entered by the user

cooling trend over the past 4 centuries in northeastern hong kong waters as revealed by alkenone derived sst records abstract the climate history over the past few centuries is important to be used to assess how regional climate responds to global forcing here we report three high resolution alkenone based sea surface temperature sst records over the past 4 centuries from three sediment cores collected in the mirs bay northeastern hong kong all three sst records consistently show a general cooling trend toward the present with most of cooling occurring over the last century alkenone derived sst values stayed around 26 5 27 c at the three sites prior to 1900s and decreased into the range of 25 26 c the magnitude of cooling approximately from the little ice age lia to present tends to be dampened from 2 c nearshore to 1 c offshore the cooling trend as identified in all three sst records is thus opposite to the global temperature rise over the last century assisted with modern observations we interpret that the alkenone derived sst reflects increasing upwelling in the mirs bay which likely results from the strengthened east asian summer monsoon in the context of global warming over the last century

seismic stratigraphic reconstruction of plio quaternary depositional sequences on the continental shelf of korea strait abstract the korea strait is a seaway connecting the east sea with the east china sea the plio quaternary stratigraphy and sedimentation on the korea strait shelf was studied using a dense network of high resolution single channel seismic reflection profiles the shelf sequences above the acoustic basement consist of seven depositional sequences separated by erosional unconformities corresponding to falls in sea level individual sequences are characterized by well stratified and complex sigmoid oblique prograding reflection configurations reflecting a history of upbuilding and outbuilding in response to repetitive transgressive and regressive events driven by sea level changes during the regression to lowstand of sea level lowstand prograding wedges were formed seaward along the present shelf margin whereas during the highstand of sea level as in the present condition highstand deposits were deposited in the inner shelf along the coast however as the subsequent regression began the inner shelf highstand deposits were severely eroded out and or formed a condensed section volumetrically the forced regressive and lowstand systems tracts are the most important components of the korea strait consequently the plio quaternary sequence in this area consists of a succession of stacked progradational lowstand wedges mainly formed during the regression and lowstand of sea level

changes in the source of sedimentary organic matter in the marginal sea sediments of eastern hainan island in response to human activities during the past 200 years abstract marine sediments have been frequently used to reconstruct the records of environment change and human activities we collected four sediment cores from wanquan river estuary and the eastern continental shelf of hainan island in the south china sea and analyzed the down core physical and chemical properties of sub samples based on 210pb dating the longest core had a record of the most recent 200 years while the other three profiles were slightly younger the results show that both the toc tn ratios and fossil fuel corrected organic 13c of marine sediments for all four cores remained relatively constant before 1950 ad indicating relatively stable sedimentary material sources however after 1950 ad the toc tn ratios and organic 13c in all four sediment cores displayed decreasing and increasing trends respectively indicating that the proportion of marine derived material increased whereas the land derived materials that were mainly transported by the wanquan river decreased this is consistent with the obvious decrease in runoff and sediment discharges of the wanquan river due to the increase in human activities including industrial and agricultural production and domestic water use in hainan island since 1950 ad therefore we suggest that environmental changes on the land were recorded by changes in the source material of marine sediments collected from coasts and estuaries

clinoforms and clinoform systems review and dynamic classification scheme for shorelines subaqueous deltas shelf edges and continental margins abstract clinoforms are inclined and normally basinward dipping horizons developed over a range of spatial and temporal scales in both siliciclastic and carbonatic systems the study of clinoform successions underpins sequence stratigraphy and all efforts to reconstruct the relative partitioning of reservoir seal and source rocks along shoreline to basin floor profiles here we review clinoform research and propose a more systematic description and classification of clinoforms this is a crucial step to improve predictions of facies and lithology distribution within shoreline to continental shelf and abyssal plain successions together with the genesis drivers and dynamics of their constituent sedimentary units four basic clinoform types are here distinguished in delta shorelines lacustrine and marine environments on the basis of their overall spatial and temporal scale morphology outbuilding dynamic and geodynamic and depositional setting 1 2 delta scale clinoforms which in turns are sub divided into shoreline and delta scale subaqueous clinoforms 3 shelf edge clinoforms and 4 continental margin clinoforms delta scale clinoform sets are tens of metres high and typically represent 1 103 kyr with progradation rates ranging from 1 000 100 000 m kyr for shorelines and subaerial deltas to 100 20 000 m kyr for subaqueous deltas shelf edge clinoform sets are hundreds of metres high and are nucleated and accreted in 0 1 20 myr usual progradation rates of 1 100 m kyr by successive cross shelf transits of delta scale clinoforms continental margin clinoform sets are thousands of metres high hallmark key geodynamic crustal boundaries e g continent ocean transition and slowly prograde basinwards in ca 5 100 myr with typical rates of 0 1 10 m kyr as a consequence of the very different progradation rates and of the difficulty of large scale clinothems to backstep during transgressions shorelines are the most dynamic clinoforms with regards to position continental margins the least and shelf edges are intermediate shortly after a transgression therefore the four clinoform types may prograde synchronously along shoreline to abyssal plain transects forming compound clinoform systems during the subsequent regressive cycle however due to the dissimilarity in progradation rates different clinoform types will normally merge progressively with each other giving rise to hybrid clinoforms e g shelf edge deltas and fewer depositional breaks in slope are distinguished along a single shoreline to abyssal plain transect overall all clinoform systems are the result of the dynamic evolution of compound and hybrid clinoforms along a temporal and spatial continuum regulated by the cyclical backstepping of the smaller scale system within natural progradational retrogradational cycles of larger scale clinothem outbuilding all clinothem types may show either an accretionary active or draping passive style depending on the proximity to the sediment source draping clinothems are nearly always composed of condensed fine grained sediments while actively accreting clinothems can be composed of predominantly coarse grained i e reservoir forming or predominantly fine grained i e non reservoir lithotypes a novel hierarchical classification scheme for both recent and ancient clinoforms is here proposed consisting of 12 classes the four basic clinoform types delta scale shoreline delta scale subaqueous shelf edge and continental margin are sub divided into eight accretionary active and draping passive sub types 8 division each accretionary sub type is then sub divided into a sandstone prone and mudstone prone variant 12 division which can be at least tentatively predicted on the basis of the clinoform morphology even in the absence of direct stratigraphic logs

geohazards monitoring in roma from insar and in situ data outcomes of the pangeo project within the pangeo project financed by the european commission under the 7th framework program the geological survey of italy ispra and the urban planning department of the city of roma developed a geodatabase and map of the geological hazards for the territory of roma integrating remotely sensed data psinsar permanent scatterer interferometry synthetic aperture radar and in situ geological information numerous thematic layers maps and inventories of hazards e g landslides sinkholes cavities geological and hydrogeological data added to historical and recent urbanization information were compared to the permanent scatterer ps data from the european remote sensing satellites ers 1 2 1992 2000 and envisat 2002 2005 descending scenes in order to produce a ground stability layer gsl based on the ps data most of the territory appears stable almost 70 of ps velocities are within 1 mm year about 14 of the pss show positive line of sight los velocities measured along the los of the satellite between 1 and 3 mm year and more than 2 exceed 3 mm year more than 11 of pss show negative los velocities between 1 and 3 mm year while about 3 exceed 3 mm year with tens of the pss showing velocities over 20 mm year the gsl is comprised of polygons or multi polygons multipart polygons grouping individual polygons under a single identifier geohazard enclosing areas where geohazards have been pointed out by ps data and or in situ surveys observed instabilities and by polygons enclosing areas potentially affected by geohazards based on the available knowledge of the territory potential instabilities in roma s gsl 18 multi polygons covering ca 600 km2 related to observed instabilities have been outlined where ground movements could be detected through insar data or where landslides and sinkholes are known to have occurred other 13 multi polygons covering nearly 900 km2 concern areas where the potential occurrence of geohazards was inferred by combining geological and or geothematic data potential instabilities the geohazards mapped in roma have been landslides collapsible grounds compressible grounds groundwater abstraction mining man made ground tectonic movements and volcanic inflation deflation the lattermost is the likely cause of the significant uplift observed in the alban hills area however this paper focuses on two more currently impending hazards subsidence and sinkholes in general sinkhole prone areas areas of dense underground cavities are hard to discern from satellite data but can be revealed by ruling out other potential causes of observed ground movement based on in situ data subsiding zones are effectively detected by the available psinsar dataset over a total extent of about 60 km2 mostly overlapping the recent alluvial areas of the tiber and its tributaries pss show a very different behaviour inside and outside the historical centre inside loading by anthropogenic construction and man made ground since ancient times has led to an almost complete consolidation of the recent river deposits marked by modest to absent subsidence in contrast outside subsidence clearly stands out with negative los velocities that although generally within several mm year can locally exceed 25 mm year ps data have provided motion information at both a regional and local scale up to the scale of a single building closer to the sea in the tiber delta area velocities increase especially above recently reclaimed marsh areas rich in peat and organic clays velocities can change significantly over short distances as in the international airport area reflecting the local stratigraphic setting the same occurs in the two subsiding areas located within the alban hills volcanic complex which is generally affected by ground uplift as a whole psinsar ground motion velocities offer a significant contribution to susceptibility and hazard recognition studies in particular such a method provides a fast and effective tool available to local authorities to monitor ground and building behaviour possibly allowing for timely prevention activities especially when coupled with appropriate in situ knowledge

structural styles of mountain building controls of lithospheric rheologic stratification and extensional inheritance 1 the strength of the crust and the mantle lithosphere are strongly influenced by the temperature the thickness and the composition of the crust and mantle lithosphere and by inherited weaknesses it consequently strongly depends on the geodynamic setting and is then expected to be different from one orogen to another which might explain the diversity of deformation styles here we use 2d thermomechanical models at lithospheric scale to study the effect of the strength of the upper and middle crust on the geometry of contractional systems the role of extensional inheritance is included by forward modeling the formation of rift basin or passive margin and using the resulting extensional structure as initial condition for lithospheric scale inversion our results demonstrate that 1 crustal strength strongly controls the width and the elevation of orogenic wedge 2 relative weak crust facilitates efficient propagating of thick skinned crustal scale thrusts 3 contraction of a strong crust leads to the formation of long thrust sheets and an anti formal stack in the core of the orogen or the accretion of upper crust depending on the depth of the decoupling zone in the mid crust 4 erosion processes favor the localization of shortening in a narrow crustal orogen 5 rifting inheritance can explain the presence at shallower depth of lower crustal or mantle material previously upwelled and facilitates the propagation of the deformation in the external part of the chain the range of predicted behaviors is compared to first order with the zagros the alps and the pyrenees three natural examples for which the crustal structure is well constrained by geophysical data

geoarchaeology confirms location of the ancient harbour basin of ostia italy abstract to the northwest of the ancient city of ostia the analysis of cores revealed a stratigraphic sequence which we interpret as the filling of a harbour basin this basin located at the west of the so called palazzo imperiale presents seven characteristics 1 the maximum depth is 6 m below the roman sea level this depth allowed any type of ship even heavy tonnage to access the harbour 2 a chronostratigraphic gap at 6 m below roman sea level suggests digging operations in the basin or subsequent dredging that have caused the loss of sedimentary archives 3 the filling consists of dark clays typical of a quiet environment but open to marine and river influences 4 the dates at the base of this sequence give a range between the 4th and the 2nd century bc 5 in the harbour sequence a facies change at 2 5 m under the roman sea level involves a change in the processes of sedimentation and or operation 6 no later than the beginning of the 1st century ad the thickness of the water column in the basin is less than 50 cm and seems to be caused by a massive siltation following a succession of floods of the tiber 7 this basin was thus already abandoned during the start up of portus

morphometric analysis and genetic implications of pro deltaic sea floor undulations in the northern alboran sea margin western mediterranean basin abstract several fields of seafloor undulations from pro deltaic wedges in the northern margin of alboran sea western mediterranean basin are described in this paper a series of elongated subparallel bathymetric undulations are distinguished in the foreset to bottomsets regions of the holocene pro deltaic wedges related with the guadalfeo and verde seco rivers multibeam data surficial sediment samples and high resolution seismic profiles have been used in this study and integrated in a geographical information system quantitative measurement of key morphometric parameters wave length height asymmetry length and wave form index was performed on multibeam data and seismic profiles using the arcgis software wave form index and depth data were analysed statistically and a cluster analysis was carried out in each area according to these results we infer that sea floor undulations in the study areas are best explained by the influence of strong sediment flows normal to bathymetric contours probably coupled with the effect of subsequent slow sediment deformation processes such as sediment creeps the influence of bottom current activity is considered less likely as the position of river mouths and the very high slope gradients seems to be the key factors which control the development of these sea floor undulations the alboran sea sea floor undulations are compared with those of other fields in shallow water environments and the different processes of formation evaluated

the tiber river delta plain central italy coastal evolution and implications for the ancient ostia roman settlement geomorphologic stratigraphic faunistic palynological and carbon isotope analyses were carried out in the area of the tiber river mouth the results depict a complex palaeoenvironmental evolution

was there an abrupt cold climatic event in the middle eemian pollen record from a palaeolake at the hieronimowo site ne poland abstract seventy samples of lacustrine sediments from a palaeolake at the hieronimowo site ne poland were investigated by pollen analysis method the obtained results indicate that the examined sequence spans the whole eemian interglacial mis 5e the beginning of the early vistulian weichselian mis 5d and some undefined period of the plenivistulian middle weichselian mis 2 4 the specific feature of the studied profile is the great thickness of deposits representing the hornbeam phase of the eemian interglacial e5 r paz which was the younger part of the climatic optimum of this interglacial and the very well developed pollen record of this phase that is absent in other profiles in ne poland due to this our study allowed for the first time in ne poland the detailed reconstruction of changes in the vegetation and in the mean january and july temperature during the middle part of the eemian interglacial this reconstruction unequivocally rules out the existence of an abrupt short lasting cold event at that time only a gradual slight increase in temperature was apparent during the older part of the hornbeam phase to 21 c for july and to 0 c for january and gradual decrease during its younger part to 17 c for july and to 5 c and

pre alpine evolution of a segment of the north gondwanan margin geochronological and geochemical evidence from the central serbo macedonian massif abstract the serbo macedonian massif smm represents a composite crystalline belt within the eastern european alpine orogen outcropping from the pannonian basin in the north to the aegean sea in the south the central parts of the massif i e southeastern serbia southwestern bulgaria eastern macedonia consist of the medium to high grade lower complex and the low grade vlasina unit new results of u pb la icp ms analyses coupled with geochemical analyses of hf isotopes on magmatic and detrital zircons and main and trace element concentrations in whole rock samples suggest that the central smm and the basement of the adjacent units i e eastern veles series and struma unit originated in the central parts of the northern margin of gondwana these data provided a basis for a revised tectonic model of the evolution of the smm from the late ediacaran to the early triassic the earliest magmatism in the lower complex vlasina unit and the basement of struma unit is related to the activity along the late cadomian magmatic arc 562 522 ma subsequent stage of early palaeozoic igneous activity is associated with the reactivation of subduction below the lower complex and the eastern veles series during the early ordovician 490 478 ma emplacement of mafic dykes in the lower complex due to aborted rifting in the middle ordovician 472 456 ma and felsic within plate magmatism in the early silurian 439 2 ma the third magmatic stage is represented by carboniferous late to post collisional granites 328 304 ma these granites intrude the gneisses of the lower complex in which the youngest deformed igneous rocks are of early silurian age thus constraining the high strain deformation and peak metamorphism to the variscan orogeny the permian triassic 255 253 ma stage of late to post collisional and within plate felsic magmatism is related to the opening of the mesozoic tethys

stepwise post glacial transgression in the rhone delta area as revealed by high resolution core data abstract integrated sedimentological and micropalaeontological benthic foraminifers and ostracods analyses of two continuous cores 40 m and 50 m long respectively recovered in the lower delta plain of modern petit rhone delta along with data from the previously studied core sf enable detailed reconstruction of the late pleistocene holocene palaeoenvironmental evolution of the rhone delta system through identification of nine microfossil assemblages and with the aid of 28 radiocarbon dates a high resolution picture of stratigraphic architecture is offered for the first time for the entire post glacial succession above late pleistocene fluvial channel gravels a retrograding pattern of swamp and estuarine bay deposits lower transgressive systems tract tst is overlain by vertically stacked late transgressive nearshore deposits upper tst this succession reflects the progressive landward migration of the palaeoshoreline driven by the rapid post glacial sea level rise which took place in the study area between ca 12 and 7 cal ky bp the following deceleration in sea level rise highstand phase induced the onset of deltaic sedimentation as evidenced by superposition of middle late holocene prodelta delta front and delta plain deposits within the cored succession at distal location the occurrence within prodelta deposits of a distinctive microfossil assemblage dominated by opportunistic benthic foraminifer valvulineria bradyana marks the onset of the rhone delta mud belt around 4 cal ky bp identification and lateral tracking of six separate flooding surfaces within the tst enable the characterization of five short term millennial to sub millennial scale depositional cycles with distinctive transgressive regressive internal architecture t r 1 5 the lower transgressive portions of cycles 1 3 11 8 9 8 cal ky bp mark abrupt shifts from freshwater to increasingly mixed brackish marine environments under conditions of rapid sea level rise in contrast the upper regressive portions represent the filling of newly formed accommodation space via extensive crevasse to bay head delta processes cycles 4 and 5 9 8 8 2 cal ky bp and the uppermost transgressive deposit below the maximum flooding surface document three distinct landward shifts of the shoreline that took place under conditions of rapidly increasing sea level rise the vertical stacking of these millennial scale cycles is interpreted to reflect the stratigraphic response to stepwise sea level rise during the early holocene the youngest flooding surface may represent the sea level signature of the 8 2 ka climate event

the contribution of geochemistry to ancient harbor geoarcheology the example of ostia antica abstract once trapped in ancient harbor basins sediments form environmental archives that have been widely studied by geoarcheologists in recent decades especially to help reconstruct fluvio marine landscapes of the last millennia in some cases classic environmental markers cannot be used for this purpose either because of their scarcity in the sedimentary deposits or because analytical costs limit the resolution that can be achieved in order to remedy these shortcomings and to complement the more commonly used proxies elemental and isotopic geochemistry has been added to the geoarcheological toolkit here we show how to read the evolution of the paleo environmental dynamics in the water column of ostia antica rome s first maritime harbor using the geochemical and isotopic record of a 3000 year old sediment core drilled in the ancient harbor basin a comparison of the results obtained from ostia antica with those of other ancient mediterranean harbors reveals the nature of the main environmental processes operating during the formation of sedimentary deposits in harbor basins from this comparative approach it appears that the respective weight of each control factor is dependent on the coastal geomorphological context of the sites where the harbors were established since the discovery of the harbor of ostia antica in 2014 this method has provided the means for the first time to identify two distinct harbor basin regimes an initial marine dominated regime from the middle of the 4th c bc to the 3rd c bc and a later freshwater dominated regime up to the 2nd c bc more generally we observe the effects of the dynamics of the deltaic progradation of the tiber which very early on was subject to a hydro climatic component on the processes of alluviation of the harbor basin additionally and also for the first time in harbor geoarcheology pb isotope compositions measured specifically on uncontaminated sediments demonstrate their utility for both identifying the geological sources of the sediments of the tiber delta and discriminating finer from larger particles the present study further provides an opportunity to test the validity of two hypotheses recently put forward 1 that a series of three tsunamis is recorded in the harbor silts and 2 that an initial lagoon type harbor was constructed at ostia antica which later evolved into a fluvial harbor neither of these hypotheses are supported by the present data

morphological changes and sedimentary processes induced by the december 2003 flood event at the present mouth of the grand rhone river southern france the study which is based on repetitive bathymetric surveys assesses changes and effects of one of the most important floods recorded in the rhone delta area bottom morphology and sediment distribution in the rhone outlet after the december 2003 flood are discussed by comparison between digital terrain maps dtms of november 2003 and january 2004 the post flood morphology shows that the whole of the system is active mainly in the east the channel of the rhone has been hollowed out on the left bank by more than 5 m the eastern coast of the mouth has retreated 400 m the mouth bar has prograded 200 m and the slope of the delta front has increased by 0 19 the overlay of pre and post flood dtms makes it possible to estimate the total volume deposited in the 0 to 20 m zone as 7 8 10 the acquisition of bathymetric measurements immediately before and after a major flood allows more than a simple morphological description in addition an analysis of the solid load transfer processes towards the prodelta is achievable three mechanisms are highlighted most of the material eroded in the channel and supplied to the delta front corresponds to fine sediment that drape homogeneously over the pre flood morphology of the delta front the transit of the coarsest sediment primarily sand is slowed down in the channel of the rhone this sediment builds up in relatively small areas leading to the formation of gullies on the prodelta slope the gullies have fixed positions and disappear gradually towards the west following the progressive migration of the active band towards the east these old features are not reactivated by floods occurring after their formation during the flood only a small volume of coarse sediment bypasses through the gullies and the fine deposits are remobilised rapidly or compacted flood input concerns essentially the delta front which traps 90 of the fluvial solid discharge between 0 and 20 m depth the coarse prodelta supply is then due mainly to mass movements of unconsolidated material deposited beforehand on the top of the delta front consequently the main nourishment of the prodelta does not occur directly during and or immediately after a flood event but is delayed by sediment being temporarily trapped on the delta front

from river to shelf anatomy of a high frequency depositional sequence the late pleistocene to holocene tiber depositional sequence the late pleistocene holocene tiber delta succession represents the most recent and one of the best preserved high frequency low rank depositional sequences developed along the latium continental margin of the italian peninsula several previous studies have established a robust data set from which it has been possible to describe the stratigraphic architecture of the entire tiber depositional sequence from the landward to seaward sectors and over a distance of 60 km the tiber depositional sequence shows many characteristics found in other late pleistocene to holocene deltaic and coastal successions of the mediterranean area the stratigraphic architecture of the tiber depositional sequence is controlled mainly by glacioeustasy although factors such as tectonic uplift volcanism and subsidence exert an influence at a local scale the resulting depositional model allowed discussion of some important points such as 1 the genesis of the tiber mixed bedrock alluvial valley extending from the coastal plain to the innermost portion of the shelf recording i multiple episodes of incision during relative sea level fall and ii a downstream increase of depth and width of the valley during the base level fall and the subsequent base level rise 2 the different physical expression of the tiber depositional sequence boundary from landward to seaward and its diachronous and composite character 3 the maximum depth reached by the tiber early lowstand delta at the end of the sea level fall is estimated at ca 90 m below the present sea level and not at 120 m as suggested by previous works 4 the backward position of the tiber late lowstand delta relative to the deposit of early lowstand 5 the change of the channel pattern and of the stacking pattern of fluvial deposits within the lowstand systems tract transgressive systems tract and highstand systems tract all of these features indicate that the late pleistocene holocene tiber delta succession even if deposited in a short period of time from a geological point of view represents the result of the close interaction among many autogenic and allogenic factors however global eustatic variations and sediment supply under the control of climatic changes can be considered the main factors responsible for the stratigraphic architecture of this sedimentary succession which has been heavily modified by human activity only in the last 3000 years

late holocene alluvial events in the central apennines italy a stratigraphic sequence wasidentified inthegransassomassif central apennines italy consisting ofalluvial sediments andburied soils thesoils dated bytheradiocarbon method enabled various alluvial phases that haveoccurred inthelast 2500years tobechronologically framed these phases werethencorrelated withthefrequency ofthetiber floods atromeandwiththeprogradation ofits delta thephases ofsoil burial byalluvial sediments coincide withtheperiods ofintense flooding ofthetiber at rome between thesecond century bc andthesecond century ad between thesixth andtheninth centuries ad andbetween thefifteenth andthenineteenth centuries ad andwithperiods ofstrong progradation oftheriver delta onthebasis ofthechronological correlation between alluvial phases glacial variations andoscillations inthelevels oflakesfucino andtrasimeno itwasthenpossible to establish that corresponding tothealluvial phases thehydrological balance ofthelakes waspositive and intwoofthethree cases theincreased flood frequency coincided withthephases ofadvance oftheonly glacier located intheapennines

stratigraphic evolution of the nakdong river valley in response to late quaternary sea level changes abstract sequence analysis using borehole samples and high resolution seismic data in the nakdong river valley yielded a good example of a river valley sequence influenced by the complex interplay between the bottom morphology of the steep paleo valley varying sediment supply and holocene sea level change associated with coastal currents the late quaternary stratigraphic sequence in the nakdong river estuary approximately 60 70 m thick forms a high frequency sequence consisting of a set of lowstand transgressive and highstand systems tracts that corresponds to a fifth order 20 ka sea level cycle four main depositional systems including ten sedimentary facies constitute these systems tracts fluvial estuarine coastal shoreface and deltaic the lowstand systems tract lst consisting of gravelly sand forms a fluvial depositional system unit i which fills the thalweg of river valley mainly developed before 12 ka the transgressive systems tract tst showing a succession of retrograding or backstepping depositional arrangements can be divided into two depositional systems unit ii and iii the riverine sediments were trapped within the paleo estuary forming an estuarine depositional system unit ii developed between 12 and 7 ka as the transgression continued the coarse sediments were deposited and redistributed by coastal processes resulting in coastal shoreface depositional system unit iii it is characterized by an isolated sand body and thin sand veneer the hst is composed of deltaic depositional system including delta plain delta front and prodelta unit iv during the delta progradation most coarse grained sands derived from the river were deposited in the lower delta plain and delta front forming sand bars and shoals less than 15 m deep the remaining fine grained sediments were transported further offshore in a suspension mode and deposited in the inner shelf off the present river mouth forming a subaqueous prodelta radiocarbon and optically stimulated luminescence osl dating suggest that the holocene deltaic system was initiated by aggradational and progradational stacking patterns at approximately 8 ka during the last stage of decelerated sea level rise and was then followed by a prograding clinoform after the highest sea level at approximately 7 ka

holocene delta evolution and sediment flux of the pearl river southern china delta progradation and sediment flux of the pearl river delta prd southern china during the holocene are presented based on analyses of borehole data on the delta plain results indicate that the delta prograded into the drowned valley because of early holocene inundation from 9 to 6 cal ka bp as sea level rise decelerated the sea level reached its present level at about 6 cal ka bp and as a consequence a large portion of the drowned valley was covered by the estuary with more than 160 rock islands and platforms the scattered landmasses promoted active deposition and acted as deposition nuclei during deltaic evolution consequently apart from exhibiting a general tendency towards progression prd development occurred less regularly over time and space because of deposition around island boundaries during the last 2 ka mainly because of significantly increased human activities which have trapped sediments in the encircled tidal flats along the front of delta plains the shoreline has advanced rapidly estimated sediment fluxes for the three periods 9 6 6 2 and 2 0 cal ka bp based on the sediment volume analysis were 17 25 22 30 and 44 58 million t a 1 respectively copyright c 2016 john wiley sons ltd

unraveling magmatic and orogenic provenance in modern sand the back arc side of the apennine thrust belt italy modern river and beach sands carried to and deposited along the coasts of the tyrrhenian sea are derived from multiple mag matic arc and orogenic sources including ophiolitic sequences and tur bidites issued from the ligurian ocean carbonate platform to pelagic sedimentary and metasedimentary successions originally deposited onto the adria continental margin and overlying foredeep clastic wedges undissected arc feldspatholithic signatures characterize limited areas capraia island tarquinia and napoli gulfs contrasting fea tures with respect to circum pacific suites low to very low p f ratio include sanidine as the most abundant detrital feldspar and common leucite and leucite bearing lithic fragments reflecting the potassic to ultrapotassic character of neogene quaternary magmatism green au gite associated with oxyhornblende and either abundant hypersthene tuscan magmatic province or minor olivine and spinel roman mag matic province is the dominant dense mineral dissected arc ar kosic signatures reflect unroofing of miocene monzogranitic stocks in the tuscan archipelago sands from ophiolitic sequences and remnant ocean sediments subduction complex provenance are characterized by common cel lular serpentinite with few chert grains basaltic to diabase and gab broic grains and by abundant shale to slate lithic grains respectively dense mineral suites are dominated by either diallage or chrome spinel sedimentaclastic sands ranging in composition from lithic to quartz ofelspathic are widespread thrust belt provenance richest in lith ic grains is detritus from mesozoic platform dominant carbonates with abundant dolostone to pelagic dominant limestone with abundant chert sedimentary successions metamorphiclastic sands with poly crystalline quartz phyllite and quartz mica or marble lithic grains from denuded core complexes are found locally apuane alps rela tively quartzose sands with abundant feldspars and garnet rich dense mineral assemblages are recycled from foredeep turbidites derived di rectly or indirectly chiefly from the alps this signature is foreign to the apennine accretionary wedge where continental basement is not structurally involved we calculate that one third of the sand grains deposited along tyrrhenian shores today are ultimately derived through long distance multistage transport and repeated recycling from the alps

tiber delta co2 ch4 degassing a possible hybrid tectonically active sediment hosted geothermal system near rome fiumicino town in the tiber river delta near rome international airport italy is historically affected by large amounts of carbon dioxide co2 in the ground and gas eruptions triggered by shallow drilling while it is known that co2 originates from carbonate thermometamorphism and or mantle degassing the origin of methane ch4 associated with co2 is uncertain and the outgassing spatial distribution is unknown combining isotope gas geochemistry soil gas and structural stratigraphic analyses we provide evidence for a hybrid fluid source system classifiable as sediment hosted geothermal system shgs where biotic ch4 from sedimentary rocks is carried by deep geothermic co2 through active segments of a half graben molecular and isotopic composition of ch4 and concentration of heavier alkanes ethane and propane obtained from gas vents and soil gas throughout the delta area reveal that thermogenic ch4 up to 3 7 vol in soil gas 13cch4 37 to 40 vpdb vienna peedee belemnite and 2hch4 162 to 203 vsmow vienna standard mean ocean water in gas vents prevails over possible microbial and abiotic components the hydrocarbons likely result from known meso cenozoic petroleum systems of the latium tyrrhenian coast overmaturation of source rocks or molecular fractionation induced by gas migration are likely responsible for increased c1 c2 ratios co2 and ch4 soil gas anomalies are scattered along nw se and w e alignments which based on borehole geomorphologic and structural stratigraphic analyses coincide with active faults of a half graben that seems to have controlled the recent evolution of the tiber delta this shgs can be a source of considerable greenhouse gas emissions to the atmosphere and hazards for humans and buildings

geometry and structure associated to gas charged sediments and recent growth faults in the ebro delta spain abstract in the ebro delta ne spain small to large scale synsedimentary deformation has been observed by means of high and low resolution seismics correlated with a network of wells lithoseismic units involved are middle upper pleistocene clays and gravels and holocene deltaic sequence gassy sediments and large river floor pockmarks are identified from seismic profiles along the ebro delta gas charged sediments are identified by zones of acoustic turbidity and other acoustic anomalies on seismic profiles most of the gas is believed to be biogenic in origin resulting from the decay of organic matter contained within rapidly developing shelf margin deltas a group of large symmetric river floor pockmarks also occurs along the inner delta plain both on the river floor surface and buried in the sediment column listric fault geometry is a typical scope shaped plane with a steep upper surface 40 60 that passes downward into a horizontal shear plane the shear plane appears seismically as chaotic and convoluted high amplitude reflectors and is correlated with well data showing layers that include gravel sand and clays associated structural features include reverse drag of reflectors antithetic faults and fluid escapes methane water the growth faulting along the ebro delta includes a break away and thin near surface layer created by overstepping of a sandy holocene delta slope the over steeping lies down dip from growth faults along the shelf break the overall growth faults province appears to represent a deeper seated general movement of the delta mass involving differential loading overpressure of fluids diapiric movements and extensional tectonics that cause listric faults and associated structures at different scales the recent growth faults are regularly spaced with the distance between successive faults controlled by the depth to the detachment layer three main fault systems have been identified a first or primary system spaced 5 2 10 5 km above a detachment layer at 55 95 m deep a second system spaced 3 5 6 km and a third system spaced 1 5 2 5 km above a detachment layer at 25 30 m the slope angle calculated by empirical equations ranges between 0 5 and 1 0 for the three systems

stratal architecture of western mediterranean margins as the result of the stacking of quaternary lowstand deposits below glacio eustatic fluctuation base level abstract through a comparison of high resolution seismic stratigraphy of seven western mediterranean margins similarities and differences in stratigraphic architecture were highlighted and a hierarchy of controlling factors was established the areas are northwestern alboran ebro and northern catalonia in the spanish margin rho ne in the french margin and tuscany latium and calabria in the italian tyrrhenian margin despite their different tectonic physiographic and depositional setting the seismic facies and growth pattern of the middle late pleistocene deposits are comparable the margins are in fact the result of the stacking of lowstand systems tracts of 4th order depositional sequences bounded by polygenetic unconforniities on the shelf and condensed sections on the upper slope this lowstand nature results from the high frequency 100 ka high amplitude 100 m asymmetry falling 65 of the time and stationariness between 10 and 120 m with respect to the present of the glacio eustatic sea level curve if eustasy directly controls the types of deposits making up the margins tectonism conditions their growth pattern as it is the only factor accounting for similarities and differences in the external geometry stratal pattern and distribution of the middle late pleistocene depositional sequences an evolutionary model for the quaternary growth of young passive continental margins is proposed in this model tectonics determines the degree of preservation of lowstand deposits because it conditions the accommodation space left below the erosional profile produced by each glacio eustatic cycle thus some of the sequence stratigraphy principles widely used to set up the model have been modified and adjusted to take into consideration the peculiar nature of quaternary glacio eustasy

environmental evolution and mid late holocene climate events in the valencia lagoon mediterranean coast of spain integration of geomorphological stratigraphic malacological sedimentological and micropalaeontological techniques and 14c dating allows us to characterise the processes and evolution of the coastal barrier lagoon system of valencia spain from the middle holocene to the historical epoch as well as the responses to global climate events four stages are recognised phase 1 around 8240 80 cal yr bp a brackish lagoon of moderate energy and in restricted environment was formed with an energy peak that could correspond to the maximum holocene marine transgression dating 8240 80 cal yr bp carried out in peat corresponds to a cold cycle and low water levels in inland lakes of the western mediterranean phase 2 from 6450 cal yr bp to 3710 130 cal yr bp a lagoon remained in restricted environment and connected with the sea but with a notable energy decrease and recurrent saturation processes similar to those described in other mediterranean continental lakes this phase is contemporaneous

submarine deltaic geometries linked to steep mountainous drainage basins in the northern shelf of the alboran sea filling the gaps in the spectrum of deltaic deposition abstract a comprehensive analysis of small deltaic environments linked to short mountainous and seasonal fluvial systems in the northern shelf of the alboran sea was undertaken in order to define the controlling parameters of the geomorphological variability the database includes multibeam and backscatter imagery surficial sediment samples and high resolution seismic profiles additionally geomorphological and hydrodynamic modeling and statistical analysis principal component and cluster analysis of hydrological and physiographic variables were performed most of the studied deltaic systems have high gradient coarse grained deposits with preferential development of the submarine portions to the detriment of the deltaic plains the geomorphological analysis identified three basic types of plan view distributions according to the length to width ratios elongate linguoid and lobate cross slope profiles evidence dominant concave upward geometries fewer occurrences of planar geometries and no sigmoid profiles sediment depocenters are extremely thick in proximal locations but thin out rapidly seawards the geometric distribution patterns of the deltaic systems are characterized by a predictable pattern in plan view according to the type of fluvial system ranging from a relatively large river to ephemeral creeks prevailing concave and secondary planar profiles support strong sediment progradation in the submarine realm and low sediment retention in the emerged deltaic environment two different types of systems are distinguished 1 larger rivers where deltaic deposition is largely controlled by basin dimensions ultimately dictating the magnitude of water and sediment discharges and 2 smaller rivers and creeks where deltaic geometries are related to the basin slopes the influence of hydrodynamic variables on defining the submarine deltaic geometry has been observed in the case of concave upward geometries where geomorphological boundaries are defined by medium and high energy wave conditions

internal structure and evolution of the late quaternary sequence in a shallow embayment the amvrakikos gulf nw greece abstract the late quaternary stratigraphic pattern of the amvrakikos gulf in the eastern mediterranean has been studied on the basis of the analysis of high resolution seismic profiles and short sediment cores lowstand transgressive and highstand systems tracts have been identified that are configured in a major depositional sequence of a fifth order sea level cycle during the last glaciation when the sea level was lowered by 55 m relative to its present position ca 50 ka bp the amvrakikos gulf was probably emerged giving rise to a subaerial erosion and fluvial incision in the western shallow part of the gulf and b development of a paleo lake in the eastern deepest domain until the early phase of the post glacial transgression ca 11 50 ka bp a paleo river characterized by a dense network of v shaped valleys was draining the western part of the gulf and flowing into the ionian sea in the isolated eastern part lowstand lacustrine deposits deltaic and prodeltaic units accumulated within the paleo lake at the latter stage of the last post glacial transgression ca 11 ka bp seawater entered the gulf and the transgressive systems tract was deposited consisting of incised channel fills beach shoreface deposits and delta prodelta wedges buried terraces have been identified also within this transgressive tract that reveal a step like sea level rise since ca 6 ka bp when the sea level reached its present day position a distal prodeltaic unit has been deposited and overlain by prograding deltaic wedges the spatial distribution of these wedges provides evidence of a continuous shifting of the river mouths during holocene the recent sedimentation patterns are related to the terrigenous inputs primarily from the arachthos river located in the northeastern part of the gulf and secondarily from the louros river located in the northwestern part

the development of late holocene coastal cooling in the northern south china sea abstract paired high resolution sea surface temperature sst records based on the long chain alkenone unsaturation index u 37 k were reconstructed to decipher the sst evolution over the past 8000 years and its possible driving mechanisms at the hong kong coastal region the two sst records derived from a sediment core in the pearl river estuary and an offshore core in the northern south china sea scs show different patterns of sst changes the coastal record shows relatively stable warm temperatures during the mid holocene 7 4 2 6 ka and substantial cooling 2 c thereafter the cooling was most pronounced in the past 0 6 ka likely associated with the little ice age lia the offshore record generally reveals a warming trend from 8 ka to 3 5 ka and relatively warm temperatures since then as a result the sst difference sst between the two sites increased over time suggesting that the sst gradient gradually developed in the northern scs the declining coastal sst with the increasing sst likely indicates and results from the intensified east asian winter monsoon since 7 ka especially during the late holocene consistent with previous terrestrial records revealing winter monsoon variability and modern observations sst between coastal and offshore sites could thus be used as an indicator of winter monsoon variability

the sediments of the stagno di maccarese marsh tiber river delta central italy a late holocene record of natural and human induced environmental changes the environmental evolution inferred from the sedimentary sequence that has occurred during the last three millennia in a drained coastal marsh in the tiber delta is presented the stratigraphy o

characteristics of collisional orogens with low topographic build up an example from the carpathians sequence stratigraphy in the hinterland kinematic analysis of thin skinned thrusting in the foreland and thermochronological tracking of exhumation in the orogenic core are combined to quantify the mechanics of an orogen with low topographic build up the carpathian system demonstrates that collisional deformation can couple and thicken the lower orogenic plate along reverse faults that dip more steeply than the subduction zone defining a foreland coupling type of collision near the surface this is expressed by wide antiforms in the upper plate and the thin skinned orogenic wedge a sequence stratigraphic analysis of the back arc transylvanian basin demonstrates that the sedimentary architecture records orogenic uplift pulses with both short and long wavelengths these correspond to the activation of individual thrust sheets in the thin skinned wedge and to lower plate coupling events respectively

holocene environmental changes of the godavari delta east coast of india inferred from sediment core analyses and ams 14c dating abstract the godavari delta in india is a major wave dominated delta of a tropical monsoon fed river with one of the largest sediment deliveries in the world while several earlier studies revealed the nature of landforms and progradation style of the delta plain during the holocene the present study attempts to reconstruct the depositional environment of the godavari delta through the analysis of core sediment and accelerator mass spectrometry ams 14c dating from three locations the sediment core obtained from a 27 06 m deep borehole at vilasavilli vv supported by 13 14c dates revealed the complete succession of the holocene deposits unconformably overlying pleistocene sediments textural analysis indicates the lower upward fining and upper upward coarsening units in the holocene succession total organic carbon toc total nitrogen tn ratios of 20 high content of toc around 1 5 2 5 and black to very dark colored sediment throughout the muddy part of the holocene succession indicated a predominance of terrigenous material the vv core and two other cores drp and sdg with 14 14c dates indicated the thickness of the holocene sediments in the godavari delta plain is in the order of 20 50 m unconformably resting on a seaward sloping pleistocene basement sediment facies and sediment accumulation of the three cores show the evolution of the godavari delta a transgressive phase is recognized as an upward fining succession in the vv core 8 4 8 0 cal ky bp followed by a low accumulation period 8 0 6 3 cal ky bp including the holocene maximum transgression in the godavari delta after 6 3 cal ky bp areas of high accumulation rates have changed laterally between the central part vv site and southwestern part drp and sdg sites may be controlled by the location of river mouths further analysis coupled with 11 more 14c dates compiled from earlier works indicated that the strandplain of the godavari delta prograded seaward in three stages and that the rate of progradation accelerated during the past 3 ky particularly in the last millennium however pronounced shoreline erosion led to a net negative growth of the delta during the recent decades due to sediment retention by upstream dams although this study provided insights into the sedimentation patterns and rate of seaward progradation of the godavari delta further studies on three dimensional volume analysis of the deltaic sediments are necessary to estimate the overall rates of past sediment discharge and the holocene growth of the godavari delta

depositional and erosional bedforms in late pleistocene holocene pro delta deposits of the gulf of patti southern tyrrhenian margin italy abstract multibeam bathymetry high resolution seismic profiles and seafloor samples have been analyzed to characterize depositional and erosional dynamics recorded pro deltaic deposits and outer shelf sediments along of a sector of the ne sicilian margin southern tyrrhenian sea the deltaic deposits cover an area of ca 15 km 2 in front of the mazzarra river and are morphologically characterized by waveforms trending overall along strike and incised cross strike gullies of variable length the gullies are shallow and characterized by small coaxial erosive scours in the inner middle shelf whereas they become larger and deeper in the outer shelf upper slope in relation to the marked increase of slope gradients at the shelf break here the wider gullies are characterized by a frame of crescent shaped bedforms interpreted as cyclic steps indicating the occurrence of sedimentary gravity flows in supercritical regime prodelta waveforms are widespread between 50 and 120 m with wave lengths of 34 110 m and wave heights of 0 5 3 m morphometric characterization and spatial distribution of the waveforms suggests a main role in their genesis played by hyperpycnal flows although we cannot discard the possible effect of internal waves or slow deformation processes i e creep depositional and erosional features similar to those observed on the seafloor are evident in the subsurface stratigraphy revealing the onset and growth of the mazzarra delta since the last glacial maximum the post glacial sea level rise caused lateral shifts of the mazzarra river mouth controlling migration of depositional lobes and intensity of seafloor incision and sediment reworking ultimately resulting in the observed wavy bedforms extending from the inner shelf to the upper slope

palaeoenvironmental reconstruction of the ancient harbors of rome claudius and trajan s marine harbors on the tiber delta during the first and second centuries ad emperor claudius and then emperor trajan successively ordered the construction of two large harbors on the tyrrhenian coast research resulted in advances in understanding the palaeoenvironments of the portus from a bathymetric point of view the drillings indicate a 7 8 m depth for the main basins different sedimentary behaviors were observed claudius basin shows sand accretion whereas the access channel to trajan s basin shows mud accumulation trajan built the second hexagonal basin because claudius harbor did not protect the ships from the wind and swell and not because it was prone to rapid silting in terms of chronology the channel between both basins worked between the end of the 2nd century and the beginning of the 5th century when it became completely clogged this means that after the beginning of the 5th century only the junction channel canale traverso remained to provide an access to the tiber and to the sea

geochronological and structural constraints on the cretaceous thermotectonic evolution of the kraishte zone western bulgaria 1 in the kraishte region near the junction of the balkanides and dinarides late early cretaceous compression led to the thrusting of the morava unit over the struma unit structural investigations combined with zircon fission track and 40ar 39ar analyses have been used to reconstruct the geological history of the area and to clarify the original tectonic position of the main units before cenozoic extension the results show that early cretaceous lower amphibolite facies metamorphism and deformation in the osogovo lisets metamorphic complex were related to top to the ne directed nappe stacking whereas the deeper parts of the allochthonous morava unit experienced low grade metamorphic overprint at temperatures 260 c the structurally intermediate struma diorites and their mesozoic cover experienced temperatures between 170 c and 300 c thrusting of the morava onto the struma unit started probably in valanginian times 140 136 ma soon after the cessation of preorogenic to synorogenic turbidite sedimentation on struma the metamorphic peak was reached before 112 ma subsequent extension related cooling of both units was probably accompanied by the formation of low angle normal faults

uk 37 temperature estimates from eemian marine sediments in the southern coast of hainan island tropical china abstract this study concerns high resolution sea surface temperature sst changes for the eemian interglacial period reconstructed from the southern coast of hainan island china the lower marine unit in the sediment core is composed of monotonous mud 31 m thick dated to be from the eemian interglacial period or lower part of marine isotope stage 5 mis 5 determined by optically stimulated luminescence osl the high sedimentation rate and the richness of organic matter and marine fossils provide good opportunity for the study of palaeo environments in the northern margin of the south china sea scs sediment grain size foraminifer sediment color index and long chain alkenone were used to reveal the near shore sedimentary environments and temperature at millennial scale specifically a high resolution uk 37 sst record was reconstructed for the eemian interglacial period the new evidence in northwestern margin of scs shows that the maximum value of sst during the eemian interglacial is approximately 29 c and the lowest is 26 5 c the trend of decreasing sst from 29 c throughout the marine sequence is consistent with the variations in sediment grain size reflecting the cooling trend of sst and sea level lowering tendency during the last interglacial period this new eemian sst result agrees with other records in the region of scs showing a coherent descending trend but spatial heterogeneity exists in timing and amplitude the insolation changes might be the main force for initiating the sst evolution during the penultimate interglacial period

coastal upwelling in summer 2000 in the northeastern south china sea using a combination of hydrographic tide gauge near bottom mooring and satellite observations and a numerical circulation model we investigate the coastal upwelling in the northeastern south china sea nscs off the coast of fujian and guangdong provinces china in the summer of 2000 subsurface upwelling phenomenon exists mainly near the bottom boundary in the whole region investigated it is closely related to the coastal sea level fluctuations which are evidently modulated by both the local wind forcing and the large scale circulation the northeastward interior flow following the bathymetry is accelerated by the drop of coastal sea level and leads to onshore transport and subsequent cooling in the bottom boundary layer bbl over the shelf west of shantou to the east of shantou the near bottom flow veers more eastward parallel to the coastline and transports the nearshore cold water mass farther to the southern fujian coast the cross shelf advected cold water does not always penetrate through the stratification and reach the surface the local wind exhibits considerable synoptic variability the decrease in sea surface temperature sst is mostly significant near dongshan shantou intermittent in time and intensifies preferably during weather events that bring southwesterly alongshore wind to the west a freshwater tongue originating from the pearl river forms a barrier layer which results in high surface temperature in the freshwater plume the observational evidences and modeled results shown in this study provide important information for further understanding the ecological effects associated with the upwelling processes in the nscs

evidence for differential degradation of alkenones under contrasting bottom water oxygen conditions implication for paleotemperature reconstruction abstract the successful reconstruction of sea surface temperatures using alkenone paleothermometry u37k has relied on the premise that there is no significant differential degradation of alkenones with different states of unsaturation during diagenetic processes to test this assumption we conducted a comparative study of contemporary sediments in oxic and anoxic bottom waters from the santa monica basin offshore california long chain alkenones were quantified and sea surface temperature were calculated using the calibrated u37k t relationship of prahl et al 1988 our results show that temperature record from the oxic sediments is higher by as much as 4 c compared to those from time equivalent anoxic sediments as a result of differential degradation of long chain unsaturated alkenones and bioturbation mixing in the oxic sediments the differential degradation of c37 3 vs c37 2 alone could account for up to 2 5 c difference between these two records this finding has significant implication in the interpretation of paleo sea surface temperature data using alkenone paleothermometry

architectural stacking patterns of the ebro delta controlled by holocene high frequency eustatic fluctuations delta lobe switching and subsidence processes abstract during the late pleistocene and holocene 125 ka b p to present a type 1 4th order depositional sequence comprising regressive lowstand transgressive and highstand system tracts formed worldwide the holocene 10 ka b p to present part of this contains the latest and present highstand systems tract hst within this and the underlying transgressive systems tract tst of the ebro delta in northeastern spain higher frequency 5th to 6th order sea level fluctuations are recognised these form retrogradational and progradational high frequency depositional sequence sets within the tst and hst respectively each high frequency sequence comprises 1 a basal highly reflective shell lag associated with an erosional transgressive surface 2 aggradational deposits which seawards consist of a wedge of marine clays with transparent seismic facies but inland are represented by thick peats 3 progradational deposits composed of sandy delta front facies displaying slope clinoforms these pass seawards into prodeltaic grey silts and landwards into red silts and pebbly sands of delta plain facies the progradational deposits downlap towards their bases the aggradational deposits formed in response to a period of rising sea level and a rapid increase in accommodation space progradation began when sediment supply to the delta exceeded accommodation space as a result of relative sea level fall the relative sea level curve for the delta has a stepped character caused by the punctuation of the 4th order sea level trend by higher frequency eustatic fluctuations as well as by high subsidence rates of about 1 75 mm per year the tst comprises retrogradational parasequences that onlap the underlying pleistocene gravels the maximum flooding surface separating the tst from the hst was formed about 6900 yrs b p on the basis of14c dating of peats the hst comprises progradational deltaic and aggradational units stacked as progradational high frequency parasequence sets the hst of the ebro delta is compared with other deltaic sequences around the world in particular with that of the mississippi delta a tentative chronology of the high frequency climatic and eustatic oscillations influencing deltaic sedimentation globally over the last 7000 years is presented

holocene hydrological and sea surface temperature changes in the northern coast of the south china sea abstract in order to reconstruct the holocene environmental history of a coastal site in the northern south china sea this study analysed the organic carbon isotope ratios 13corg and alkenone unsaturation ratios uk 37 from a 36 5 m long sediment core drilled at seabed in the mouth region of the pearl river estuary and generated a coupled hydrological and temperature record this record reveals changes of monsoon induced sediment discharge and sea surface temperature of the holocene in four stages in stage i the site was under fluvial conditions prior to postglacial marine transgression stage ii saw an increase of sea surface temperature from c 23 0 c to 27 0 c associated with a strengthened summer monsoon from c 10 350 to 8900 cal years bp this was also a period of rapid sea level rise and marine transgression during which the sea inundated the palaeo incised channel i e the lower part of the t shape accommodation space created by the rising sea in these 1500 years fluvial discharge was strong and concentrated within the channel and the high sedimentation rate 11 8 mm year was very close to the rate of sea level rise in the subsequent 2000 years stage iii sea level continued to rise and the sea flooded the broad seabed above the palaeo incised channel resulted in fluvial discharge spreading thinly across the wide accommodation space and a much reduced sedimentation rate 1 8 mm year sea surface temperature in this stage reached 27 3 c initially but dropped sharply to 26 1 c towards c 8200 cal years bp the final stage covers the last 7000 years and the site was under a stable sea level sedimentation in this stage varied a little but averaged at 1 8 mm year whilst fluvial discharge and sea surface temperature didn t change much two short periods of hydrological and temperature change were observed which are related to the climatic cooling events of c 4200 cal years ago and the little ice age

morpho sedimentary characteristics and holocene evolution of the emergent part of the ombrone river delta southern tuscany abstract the holocene evolution of the ombrone river delta has been investigated using morphological and sedimentological evidence the delta had a lagoon like prehistoric evolution while seawards the growth occurred mainly in historical times the data obtained together with the available historical and archeological documentation enable a quantitative evaluation of the volume of the emerged part of the delta to be made moreover for the apical area it has been possible to calculate the annual average increase in the volume of deposition during etruscan and roman times as well as during the middle ages and since the renaissance up to now it has been possible to estimate the periods during which wind exerted a more important role in shaping the delta morphology the volume of sediments deposited during the last 6000 years has been estimated at 1766 10 6 m 3 a combination of climatic conditions littoral dynamics and human action appears to have driven the dynamics of the delta growth which however was not continuous but active especially during the last 3000 years during this period about the 80 of the whole delta volume seems to have deposited high rates of sedimentation occurred between the 16th and the 19th centuries a cold and moist period coinciding with the little ice age when the delta took the typical shape of microtidal wave dominated deltas

sand bodies and incised valleys within the late quaternary sanaga nyong delta complex on the middle continental shelf of cameroon abstract seismic data and sediment cores collected offshore from the sanaga river and nyong river mouths were used to analyse a loose mantle of yellow to reddish sandy gravel with a range of fluvial and deltaic characteristics cropping out in the middle part 25 65 m water depth of the continental shelf of cameroon contrary to most of the atlantic shelves where the lowstand systems tract was destroyed by erosion we found 80 120 ms 60 90 m of sediment mainly in the middle part of the shelf which correspond credibly to mis 2 4 fluvial paleodrainage systems are preserved beneath the shelf and individual filled channels with planar infillings were mapped that cross the shelf along two surfaces of erosion these incisions suggested westerly and northwesterly drainage shifts during presumed lowered base level the presence of closely spaced channel fills suggests repeated avulsion of a single stream during a long lasting sub aerial erosion period the seismic facies of these pleistocene deposits distinguish themselves clearly from well stratified older strata showing deformation pliocene or intense folding miocene the orientation of the paleovalleys appears strongly controlled by the n60 e trending cross faults within mesozoic cenozoic strata on the basis of approximately 80 000 years of accumulation an estimate of the yearly mass of sediment transported was calculated for the sanaga and nyong rivers and compared to the present sediment load of the two rivers it is estimated that as much as 50 of the sediment discharge must have bypassed the upper slope we show that deposition took place near the terrestrial break in slope even though the coastline had already regressed across the shelf in contrast the gradient of the lower course of the nearby niger river remains below 0 05 through several hundreds of kilometres and no lowstand deposits have been preserved we conclude that the break in slope even terrestrial is the determining factor regarding preservation of shelf deposits during relative sea level rise

late holocene variation in vertical thermal gradient from the coastal east china sea links to monsoon climate and coastal upwelling the evolution history of coastal upwelling systems in the east china sea over the late holocene are important yet difficult to be characterized here we present 3000 year temperature records based on both alkenones uk 37 and glycerol dialkyl glycerol tetraethers texh86 from a sedimentary core in the coastal upwelling site of the southern east china sea by examining the similarity and difference between the down core texh86 derived temperature and records of sea surface temperature summer monsoon and winter monsoon we suggest that the texh86 mainly reflects temperature in the subsurface water in the studied site in this sense paired temperature records from both surface uk 37 and subsurface texh86 water would yield an estimation on the vertical thermal gradient which provides insight into the upwelling strength in the summer season weak upwelling periods occurred at 2600 2800 yr bp 2000 2400 yr bp 1200 1550 yr bp 350 750 yr bp and the recent 100 years positive correlations among the

surface and subsurface of the metaponto coastal plain gulf of taranto southern italy present day vs lgm landscape abstract the metaponto coastal plain mcp in southern italy stretches 60 km long and 5 km wide along the gulf of taranto in the ionian sea and is presently subject to strong anthropogenic pressure a multidisciplinary study reviewed the geomorphology lithostratigraphy and sedimentology of the mcp and its subsurface incorporating both borehole and radiocarbon dating information in the review this paper focuses on comparisons and differences between present day and buried late pleistocene landscapes lgm and mis 3 the modern coastal plain is the top of a late holocene coastal wedge prograding on a very narrow shelf that is connected to a deep basin the ionian sea by a steep slope this scenery likely resembles those produced during earlier late quaternary relative highstands and is in marked contrast with that produced during the last sea level fall and lowstand and buried in the mcp subsurface the last scenery corresponds to the lgm landscape where river valleys deeply dissected a previous highstand coastal wedge mis 3 whose remnants represented interfluve areas thanks to resonance properties of the subsurface this buried landscape was obtained in a 3d visualization highlighting location and shape of incised valleys and interfluve areas during the lgm

historical morphogenesis of the turia river coastal flood plain in the mediterranean littoral of spain abstract the cross referencing of sedimentological stratigraphic geoarchaeological and radiocarbon data enables us to establish the geomorphologic evolution of the late holocene coastal flood plain of the turia river the holocene marine transgression formed a coastal barrier lagoon environment in the coastal plain during the late holocene increased sediments supplied to the low reach of the river promoted a the progradation of deltaic coastal sandy ridges on the coastline and b the aggradation of the floodplain on top of the sedimentary sequence four phases are clearly recognised in the geoarchaeological record of the flood plain 1 high magnitude flooding events 2800 bp to 3rd century bc 2 slow riverbed aggradation and progressive levee formation low energy flood regime in roman times 2nd century bc to 5th century ad 3 swampy environmental processes 6th to 9th centuries 4 second high magnitude flooding phase 11th century the navigable channel of the roman and early islamic periods became a wide and shallow braided channel in medieval times these phases are correlated with others detected by researchers in many areas of the mediterranean region and with global holocene climate events

alkenone and tetraether lipids reflect different seasonal seawater temperatures in the coastal northern south china sea abstract we examined the lipid based temperature proxies u 37 k and tex 86 h in five short sediment cores from the inner shelf of the northern south china sea and related them to local sea water temperature from the world ocean atlas woa database the u 37 k based temperature values are consistent with euphotic zone temperature in spring and summer when the southeast monsoon prevails and vertical stratification occurs in the water column whereas tex 86 h based temperature values reflect sea surface temperature in winter when the northeast monsoon prevails and vertical mixing occurs the different temperature signals between the tex 86 h and u 37 k proxies could be a result of differences in the growing season between the source organisms with alkenone producing haptophyte algae blooming in the warmer and nutrient rich season with higher fluvial influx and tetraether producing thaumarchaeota blooming in the cooler and oligotrophic season

high resolution seismic study as a tool for sequence stratigraphic evidence of high frequency sea level changes latest pleistocene holocene example from the korea strait abstract sequence stratigraphic analysis of high resolution seismic reflection profiles and sediment data reveals that the latest pleistocene holocene deposits in the korea strait shelf off the southeastern korean peninsula form a high frequency sequence consisting of a set of lowstand transgressive and highstand systems tracts that corresponds to a fifth order 20 kyr sea level cycle eight depositional systems each with different seismic facies constitute the systems tracts the lowstand systems tract consisting of sandy mud forms a deltaic wedge that pinches out updip near or at the relict shelf edge the transgressive systems tract consisting mainly of sands includes six depositional systems 1 inner shelf transgressive layer 2 transgressive estuarine deltaic complex 3 transgressive sand ridge 4 mid shelf transgressive layer 5 incised channel fill and 6 beach shoreface complex although the transgressive systems tract is widely distributed it is much thinner than the lowstand and highstand systems tracts the highstand systems tract is composed of a prodelta shelf complex consisting almost exclusively of holocene muds the distribution and geometry of the systems tracts in the latest pleistocene holocene sequence in the korea strait shelf is different from that of vail s model in that 1 the lowstand systems tract consists only of the lowstand deltaic wedge which forms an elongated sediment body along the paleoshelf edge and 2 the highstand systems tract is completely confined to the inner shelf and forms a nearshore belt parallel to the coastline high frequency 20 kyr high amplitude magnitude of about 130 m sea level change together with strong currents flowing northeastward along the southeastern coast of the korean peninsula and varying sediment supply have resulted in this rather unusual stratigraphic architecture

lowstand terraces on tyrrhenian sea steep continental slopes abstract wave built terraces formed during sea level stillstands at depths lower than present are found along margins with fairly steep morphology and no to ill developed continental shelf for instance the margin of volcanic islands terraces deposits are up to 20 30 m thick and are flat topped with well defined edges they extend up to 1 km in dip section the deposits are composed of intrabasinal sediments mainly bioclastic sand and silt and are probably due to deposition below the storm wave base during large scale energy episodes two areas of the tyrrhenian sea have been analysed one in a volcanic context the pontine archipelago and the other in a highly active structural context the calabrian arch similar wave built terraces were found in both areas with a main terrace placed at a depth of 100 150 m which is thought to be wurmian older terraces are also present emplaced during the preceding lowstands in the late pleistocene a possible present day terrace is found at about 20 m depth in the pontine archipelago a mechanism of subsequent formation below wave base level and removal because of sea level lowering has been hypothesised during long lasting periods of late pleistocene sea level falls terraces are thus thought to preserve only at the minimum lowstand position and to remain relict on the slope during sea level rise and highstand the analysis of the distribution and depths of these terraces allows some neotectonic interpretation for example in the volcanic archipelago whose western sector has probably risen at an average rate of 2 5 mm yr over the last 20 000 years

sequence stratigraphy and depositional setting of the tiber delta integration of high resolution seismics well logs and archeological data abstract using archeological evidence radiocarbon data well logs and high resolution seismic profiles we applied sequence stratigraphic analysis to sediments deposited during the last glacio eustatic cycle on the tyrrhenian continental margin embracing the tiber river months these sediments form a high frequency sequence of fifth order that has developed over the last 20 000 yr since the last lowstand hereafter referred to as the tiber depositional sequence tds the tds is still evolving and lies on a type 1 sequence boundary that has been identified both on the shelf and below the present delta plain this sequence consists of lowstand transgressive and highstand systems tracts the lowstand deposits are not present on the shelf but are found on the continental slope where they constitute the last progradation set of the continental margin a network of gullies active when the river mouth was at the shelf break is present within the lowstand deposits the transgressive systems tract tst deposits lie directly on the basal unconformity landwards the tst is represented by a retrogradational parasequence set of fluvial coastal barrier lagoon and lagoonal delta facies seaward on the shelf these parasequences merge into a seismically transparent deposit that forms a condensed section the flooding surfaces that bound the parasequences are marked by peat layers that were dated by 14c the radiometric ages were used to draw a carve of sea level rise for the last 11 000 yr the top of the transgressive systems tract maximum flooding surface is represented by the last peat layer which was formed about 4700 5000 yr bp and buried 4 5 m below the present upper delta plain the highstand systems tract is made up of deposits of the present tiber wave dominated delta i e upper and lower delta plain delta front and prodelta slope the aligned beach ridges mark the position of the prograding coastline which for the last 2500 yr can be dated by archeological and historical data the recent very fast progradation of the tiber delta during the last 500 years is consistent with historical data on floods of the city of rome and the suspended load of the tiber river

reconstruction of the tiber deltaic stratigraphic successions near ostia using the padm chart and tracking of the bedload derived facies rome italy abstract located between the deltaic plain and the subaqueous delta base level is one of the most important factors that affect depositional elements and the sedimentary architecture of river deltas in this respect its changes are essential to reconstruct delta evolution during the holocene in this paper we study three cores drilled in the tiber delta italy palaeoenvironmental analyses were performed and included new sedimentological data laser grain size loss on ignition magnetic susceptibility new data from bioindicators ostracods and macrofauna and 11 new radiocarbon dates the three cores were analysed and replaced in a cross section between the inner and outer tiber delta i e in the palaeolagoon and in the progradational delta plain first we have mapped the holocene transgression and progradation of the ostia area using palaeoenvironmental age depth modelling techniques padms padm charts help to interpret a stratigraphic succession in a river delta they contribute to the understanding of the links between depositional environments sedimentation rate and sea level rise and to reconstruct coastline trajectories more precisely they contribute to the interpretation of the consequences of the sea level jumps dated to the 9000 8000 cal bp period on coastal environments and help to identify progradational phases around 4 k and from 2 8 to 2 6 k cal bp second we identify indirect freshwater bioindicators and direct bedload derived facies evidence of fluvial activity in the studied cross section the studied deep cores indicate that at least one palaeochannel of the tiber river was already flowing in the middle southern part of the delta from 4 k cal bp finally a first map of the lateral mobility of the palaeochannels of the tiber river is proposed for the last 6 k cal bp using the new data and a synthesis of all the data available at the scale of the delta

a source to sink compositional model of a present highstand an example in the low rank tiber depositional sequence latium tyrrhenian margin italy abstract our source to sink compositional model of sediment distribution in the present highstand of the tiber depositional sequence has important implications for sediment source lithology generation transport and deposition in the tiber river system sand compositional trends reflect provenance mixing anthropic intervention and the effects of local autogenic factors in continental to marine depositional environments fluvial feldspatho quartzo lithic sand results from the contribution of the major tributaries of the tiber drainage basin which can be divided into two sub basins separated by the corbara dam built in the 1950s upstream drainage basin sand has a siliciclastic sedimentary lithic signature whereas carbonate and volcanic lithic fragments dominate downstream drainage basin sand downstream sand is further modified in the coastal environment by hydraulic sorting and mixed with detritus derived from the recycling of coastal dune sand and altered volcaniclastic paleosols the latter are associated with lower course floodplain and channel deposits which produce a quartzo feldspatho lithic sand sediment grain size zonation in the marine environment is influenced by coastal hydrodynamics which in turn produce two detrital populations with distinct compositional signatures and hydraulic behavior coarser minerals essentially pyroxene phenocrysts and finer feldspar grains are progressively concentrated in higher energy and lower energy environments respectively biogenic continental shelf and slope deposits off the tiber river mouth show very little riverine influence this study of the last highstand system tract in the tiber depositional sequence clarifies the effects of hydraulic sorting grain size dependence and sediment reworking in controlling the final composition of modern sand this knowledge can be used to better understand detrital modes of ancient sedimentary successions

coalescent valley fills from the late quaternary record of tuscany italy abstract three prominent incised valley fills of post last glacial maximum age are described from the northern tuscan coast of italy stratigraphic correlation of core data along a cross section transversal to the present fluvial channel axes enables identification of a suite of genetically related valley bodies that fill the incisions made up by arno serchio and camaiore stiava rivers during the last glacial interglacial cycle the valley fills display different shapes and size but remarkably similar facies architecture valley bodies range between 5 and 10 km in width and between 30 and 45 m in thickness with width thickness ratios of about 100 300 above a lowstand and early transgressive gravel fluvial deposit the three incised valley fills display a distinctive succession of coastal plain to estuarine facies dated to about 13 8 cal ka bp radiocarbon dates document that the three valleys were active simultaneously accommodation space was rapidly created during transgression and then filled under conditions of very high sediment accumulation about 1 cm y in contrast to the more common deepening upward trend recorded by the latest pleistocene early holocene valley fill successions worldwide sedimentation in the tuscan valleys equalled or even exceeded the rate at which accommodation was created thus leading to an aggradational rather than backstepping stacking pattern of high frequency millennial scale parasequences above the valley fills and on the interfluves a thin deepening upward succession of nearshore deposits marks the rapid change from aggradational to retrogradational depositional style this is invariably overlain by a characteristic shallowing upward motif of prograding deltaic and coastal facies the maximum flooding surface which can be tracked across the whole study area on the basis of subtle palaeontologic indicators is shown to represent an almost isochronous surface dated to about 7 8 cal ka bp through examination of large scale geometry and facies attributes of the valley fills including the relationships between valley bodies and interfluves this study represents an example of how adjacent river systems with significantly different characteristics may respond simultaneously in a consistent manner to rapid changes in sea level and climate conditions

physical stratigraphy and sedimentology of the late pleistocene holocene tiber delta depositional sequence the tiber delta lies on the passive continental margin of central western italy the tiber delta is a late pleistocene holocene sedimentary succession and constitutes an incomplete high frequency depositional sequence 4th or 5th order which developed from the last post glacial rise in sea level to the present stillstand it is bound by a type 1 basal unconformity which cuts pleistocene deposits five depositional systems have been identified 1 coastal barrier lagoon 2 shelf transition 3 fluvial braided 4 tiber lagoonal deltas t1 t2 t3 and 5 tiber wave dominated delta the first four systems constitute the transgressive system tract tst which is characterized by a retrogradational parasequences set while the fifth system represents the highstand system tract hst characterized by only one parasequence progradational the evolution of these depositional systems has been mostly controlled by sea level rise which was not continuous but punctuated by eight minor stillstands and rapid rises this mechanism of sea level change led to the formation of parasequences that developed within the depositional systems from a palaeogeographical point of view the present tiber delta area was mainly characterized by a coastal barrier lagoon and tiber lagoonal deltas t1 t2 t3 which migrated landwards during the sea level rise throughout the time of the present stillstand the t3 lagoonal delta prograded rapidly into the lagoon reaching the coastal barrier and the lagoon was replaced first by marshes and then by the alluvial plain finally the tiber river overcame the littoral barrier supplying the coast giving rise to the present wave dominated delta

the role of foraminifera as indicators of the late pleistocene holocene palaeoclimatic fluctuations on the deltaic environment the example of tiber delta succession tyrrhenian margin italy abstract the palaeoclimatic and palaeoenvironmental reconstruction of the last 39 0 kyr of the central tyrrhenian shelf are presented in this paper micropalaeontological sedimentological and stable isotopic data integrated by radiocarbon dates were determined from three cores drilled in the tiber delta sequence tds which constitutes one of the most complete late quaternary high frequency depositional sequences in the mediterranean area short period climate variations that induced short period events caused changes in the tiber run off and increased the sediment supply and grain size in the delta system the three cores with different thicknesses record all the system tracts forming the tds three intervals corresponding to the early and late lowstand transgressive and highstand system tracts tst and hst were recognised the first is characterised by shoreface inner shelf deposits and corresponds to a general cooling period characterised by short warmer periods approximately 1 0 kyr confirming the climatic variability of mis 3 mis 2 a very condensed deposition affected the second interval which is characterised by a very low sedimentation rate corresponding to the tst of tds the third interval corresponding to holocene shelf deposits shows small climatic oscillations that mark an enhanced seasonality typical of the modern tyrrhenian regime at the millennial scale two warm intervals copper age and late bronze age ii century ac alternating with two cold humid intervals bond cycle b3 rcc 4 2 3 8 kyr bp of mayewski events and the little ice age have been recognised

mantle derived co2 migration along active faults within an extensional basin margin fiumicino rome italy abstract fluid migration along faults can be highly complex and spatially variable with the potential for channeled flow accumulation in capped porous units fault cross flow lateral migration along strike or complete sealing extensional basin margins can be important for such migration given the associated crustal thinning and decompression that takes place combined with potential geothermal or mantle gas sources one such example is near the urban area of rome situated along the active extensional continental margin of the tyrrhenian back arc basin and surrounded by middle upper pleistocene k rich and arc related volcanoes recent research activities in the area around fiumicino a town 25 km to the west of rome has highlighted the close spatial link between degassing co 2 and the faults that provide the necessary vertical migration pathways in particular detailed soil gas and gas flux surveys have highlighted the release at surface of large volumes of asthenospheric mantle co 2 in correspondence with normal faults observed in a new seismic reflection profile acquired along the tiber river detailed reconstruction of the pleistocene holocene stratigraphy of the area dates fault activity from 20 000 to 9000 years bp it is proposed that the gas migrates preferentially along the cataclastic tectonic breccias of the faults until it encounters recent unconsolidated sediments porous units within this shallow stratigraphy act as temporary secondary traps for the leaking gas with local gas release at the ground surface occurring where the sealing of the overlying aquitards has been compromised degassing and active faults confirm the extensional tectonics affecting the area and the geodynamic scenario of a mantle wedge beneath the western apennines associated with ongoing w directed subduction moreover degassing highlights the potential geochemical and seismic risks for the highly populated urban areas near rome

the transition from wave dominated estuary to wave dominated delta the late quaternary stratigraphic architecture of tiber river deltaic succession italy abstract this paper presents a detailed description of the stratigraphic architecture of the late pleistocene holocene tiber delta succession in order to document the passage from wave dominated estuary to wave dominated delta in the broader context of late quaternary sea level fluctuations this succession constitutes a sequence stratigraphic unit known as tiber depositional sequence tds which was deposited during the last glacial interglacial cycle last 120 ka our study is based on the examination of an enormous amount of data derived from the stratigraphy of about 300 wells petrographical and paleontological data foraminifera ostracoda pollen and plant macrofossils 14 c dating and from the integration of geomorphological and geoarcheological data recently a 100 m deep core pesce luna well was studied through a multidisciplinary approach and a detailed description of sedimentary facies foraminifer and ostracod assemblages pollen and 14 c dating is presented in this paper the new data allowed to produce three new correlation panels and to describe in more detail with respect to previous interpretations the stratigraphic depositional architecture of the tds which internally shows the preservation of sediment deposited during the early and late lowstand the transgressive and the highstand systems tracts alluvial and coastal depositional systems characterize the early lowstand phase of the tds which developed during the eustatic sea level fall between about 120 and 30 26 yr bp during the late lowstand phase which is characterized by stillstand and slow eustatic sea level rise a prograding delta and an aggrading incised valley fluvial fill developed the tiber incised valley was transformed into a wave dominated estuary during the transgressive phase tst whereas a coastal shelf sedimentation took place during the subsequent highstand phase hst this study confirms the lithofacies distribution resulting from transgression and infilling of the wave dominated estuaries but also shows how the transition to a wave dominated delta prograding at the time of sea level highstand occurred changes in sediment input climatic variations and more recently human activities played a major role in the development of the tiber delta during the last 20 000 yr bp in the last 3000 years a relationship between progradational phases of the delta and flood events of the tiber river has been highlighted suggesting also the formation and merging of barrier spits to the mainland

summer monsoon induced upwelling dominated coastal sea surface temperature variations in the northern south china sea over the last two millennia the south china sea scs situated to the north of the indo pacific warm pool ipwp is under the strong influence of the asian monsoon system however coastal sea surface temperature sst reco

late quaternary depositional architecture of po and tevere river deltas italy and worldwide comparison with coeval deltaic successions abstract po and tevere rivers form two of the most important deltas of the whole mediterranean area detailed investigations have been carried out in the last decade beneath the present delta plains of these two river systems using borehole data correlation with the aid of radiocarbon dates and other dating methods pollens archaeology a detailed sequence stratigraphic framework has been constructed in both areas especially for the last glacial interglacial cycle regional subsidence combined with short term sea level fluctuations of relatively high amplitude played a fundamental role in creating subtracting accommodation during the long phase of falling sea level which followed the tyrrhenian substage 5e transgressive event a discontinuous record of this phase is present in the subsurface of the po plain whereas poor or no preservation has been detected in the tevere area progradational lowstand wedges accumulated during the last glacial maximum mostly in the central part of the basins far from the present deltas and are lacking in the study areas where a hiatal surface is invariably recorded below the transgressive deposits glacioeustasy exerted a major control on sedimentation in both areas during the latest pleistocene holocene sea level rise infilling of fluvial valleys and rapid landward migration of barrier lagoon systems in the context of wave dominated estuaries characterized the transgressive phase in both po and tevere systems in place drowning and transgressive submergence mechanisms of barrier migration were effective predominantly between 13 5 and 9 ka bp in contrast shoreface retreat was dominant in the late transgressive phase the maximum flooding surface mfs can be traced physically from continental to marine deposits and has similar characteristics in the po and tevere river systems being marked by peat layers or lagoonal deposits at landward locations and by distinctive lithological characteristics and micro and macrofossils assemblages basinwards above the mfs the early highstand systems tract records initially the filling of the lagoons followed by the rapid progradation of wave dominate delta systems and flanking strandplains autocyclic processes such as distributary channel avulsion delta lobe abandonment and local subsidence due to sediment compaction were the fundamental controlling factors on sedimentation during deposition of the hst the stratigraphic architecture of the post glacial po and tevere delta complexes closely resembles the basic facies successions documented from coeval deposits of wave dominated and wave influenced clastic coasts both locally within the mediterranean area and in other parts of the world our study emphasizes however some additional features and major differences with previously published depositional models including i the development of backstepping wave dominated estuaries during transgression ii consistent changes through time in the mechanism of barrier migration iii a later construction of the delta systems with respect to what traditionally considered

mid to late holocene climate change an overview the last 6000 years are of particular interest to the understanding of the earth system because the boundary conditions of the climate system did not change dramatically in comparison to larger glacial interglacial changes and because abundant detailed regional palaeoclimatic proxy records cover this period we use selected proxy based reconstructions of different climate variables together with state of the art time series of natural forcings orbital variations solar activity variations large tropical volcanic eruptions land cover and greenhouse gases underpinned by results from general circulation models gcms and earth system models of intermediate complexity emics to establish a comprehensive explanatory framework for climate changes from the mid holocene mh to pre industrial time the redistribution of solar energy due to orbital forcing on a millennial timescale was the cause of a progressive southward shift of the northern hemisphere nh summer position of the intertropical convergence zone itcz this was accompanied by a pronounced weakening of the monsoon systems in africa and asia and increasing dryness and desertification on both continents the associated summertime cooling of the nh combined with changing temperature gradients in the world oceans likely led to an increasing amplitude of the el nin o southern oscillation enso and possibly increasingly negative north atlantic oscillation nao indices up to the beginning of the last millennium on decadal to multi century timescales a worldwide coincidence between solar irradiance minima tropical volcanic eruptions and decadal to multi century scale cooling events was not found however reconstructions show that widespread decadal to multi century scale cooling events accompanied by advances of mountain glaciers occurred in the nh e g in scandinavia and the european alps this occurred namely during the little ice age lia between ad w1350 and 1850 when the lower summer insolation in the nh due to orbital forcing coincided with solar activity minima and several strong tropical volcanic eruptions the role of orbital forcing in the nh cooling the southward itcz shift and the desertifi cation of the sahara are supported by numerous model simulations other simulations have suggested that the fingerprint of solar activity variations should be strongest in the tropics but there is also evidence that changes in the ocean heat transport took place during the lia at high northern latitudes with possible additional implications for climates of the southern hemisphere sh

a review of the stratigraphy of rome italy according to geochronologically and paleomagnetically constrained aggradational successions glacio eustatic forcing and volcano tectonic processes abstract in this paper we provide a critical review of the studies conducted on the geology of rome since the first half of the 20th century aimed at presenting an updated state of the art on the stratigraphy of this area following this introductory summary we present a complete reconstruction of the geological evolution and the resulting chrono litho stratigraphic setting of the greater area of rome according to a series of works that in the last 20 years have adopted an innovative methodological approach based on the conceptual model of aggradational successions deposited in response to sea level rise during the glacial terminations and on the strict geochronologic constraints to the sedimentary record achieved by paleomagnetic investigation of clay sections and 40ar 39ar dating of interbedded volcanic materials we also present a complete overview on the chronostratigraphy of the two volcanic districts of colli albani and monti sabatini located se and nw of rome respectively that has been achieved integrating the field work with the large number of radiometric ages provided in these years on their eruptive products moreover we propose a revised stratigraphic column to compare the most recent official 1 50 000 and 1 10 000 geologic mapping of rome which is intended as a tool of correlation for an international audience of quaternary scientists to approach the study of this area a detailed discussion of the proposed revisions is also provided as supplementary information to this paper

rapid 20th century increase in coastal upwelling off northwest africa near shore waters along the northwest african margin are characterized by coastal upwelling and represent one of the world9s major upwelling regions sea surface temperature sst records from moroccan sediment cores extending back 2500 years reveal anomalous and unprecedented cooling during the 20th century which is consistent with increased upwelling upwelling driven ssts also vary out of phase with millennial scale changes in northern hemisphere temperature anomalies nhtas and show relatively warm conditions during the little ice age and relatively cool conditions during the medieval warm period together these results suggest that coastal upwelling varies with nhtas and that upwelling off northwest africa may continue to intensify as global warming and atmospheric co 2 levels increase

weakened yellow sea warm current over the last 2 3 centuries abstract variations of oceanic currents beyond the instrumental period are often difficult to characterize although sea surface temperature sst changes along current pathways could provide some indirect information here we reconstruct four u 37 k based annual sst records over the past 2 3 centuries from muddy areas in the yellow sea ys and the northern east china sea ecs to characterize the regional sst variation patterns and to assess whether such patterns could be used to infer current changes three offshore sites are located along the pathway of the yellow sea warm current yswc and an additional coastal site near the yangtze river mouth with the minimal yswc influence the records show ssts dropped 3 6 c over the last 2 3 centuries at the three offshore sites and a warming trend toward the present at the coastal site the cooling sst trend observed at the three offshore sites is at odds with the average northern hemisphere temperature and solar irradiance changes strongly suggesting that regional processes or drivers in the ys and northern ecs regions overturned the global temperature signal accordingly we propose that the yswc weakened over the last 2 3 centuries which might be linked to the east asian winter monsoon variability

structure and provenance of late cretaceous miocene sediments located near the ne dinarides margin inferences from kinematics of orogenic building and subsequent extensional collapse the ne part of the dinarides mountain chain located near their junction with the carpatho balkanides is an area where sedimentary basins associated with the neotethys subduction and collision are still exposed we performed a provenance study based on detrital fission track thermochronology combined with zircon upb magmatic geochronology and existing studies of kinematics and exhumation our study shows rapid sedimentation in the trench and forearc basin overlying the upper european tectonic plate a number of latest cretaceous early paleocene igneous provenance ages show a dominant magmatic source area derived from a late cretaceous subduction related arc this arc shed short time lag sediments in the forearc and the trench system possibly associated with focused exhumation in the serbo macedonian margin this was followed by burial of the trench sediments and a novel stage of middle late eocene exhumation driven by continued continental collision that had larger effects than previously thought the collision was followed by late oligocene miocene exhumation of the former lower adriatic plate along extensional detachments that reactivated the inherited collisional contact along the entire dinarides margin this event re distributed sediments at short distances in the neighboring miocene basins our study demonstrates that the dinarides orogenic system is characterized by short lag times between exhumation and re deposition whereas the upper tectonic plate is significantly exhumed only during the final stages of collision such an exhumation pattern is not directly obvious from observing the overall geometry of the orogen

late quaternary inner shelf deposits in response to late pleistocene holocene sea level changes nakdong river se korea abstract the high resolution seismic profiles from the inner shelf off the nakdong river in se korea can be directly correlated with the lithologic characteristics in the borehole data these correlations offer an opportunity to document the evolution of the inner shelf deposits with sediment supplies in response to the late quaternary sea level changes the inner shelf sequence in this area consists of four sedimentary units which comprise a set of lowstand transgressive and highstand systems tracts deposited since the last glacial maximum incised channel fill su1 estuary su2 sand veneer su3 and subaqueous delta su4 the lowermost unit su1 which overlies the sequence boundary is interpreted as fluvial deposits formed during the last glacial period and the early stage of transgression and belongs to the lowstand to transgressive systems tract the lower middle unit su2 lying below the ravinement surface represents a paralic component that consists of estuarine sandy mud or muddy sand developed between approximately 13 and 8 cal ka bp whereas the upper middle unit su3 above the ravinement surface corresponds to a marine component that consists of sand veneer produced by the shelf erosion during the ensuing sea level rise these two units su2 and su3 belong to the transgressive deposits the uppermost unit su4 regarded as the highstand systems tract formed the nakdong subaqueous delta including the proximal and distal systems developed after the highstand sea level at approximately 6 cal ka bp the lateral transition from the proximal to distal facies suggests a prograding delta system in the nakdong river

marine connections of amazonia evidence from foraminifera and dinoflagellate cysts early to middle miocene colombia peru abstract species composition in the present day amazonian heartland has an imprint of past marine influence the exact nature timing and extent of this marine influence however are largely unresolved here we use calcareous tests of foraminifera and marine palynomorphs from miocene sediments in northwestern amazonia to extend on current estimates for salinity ranges paleoenvironments and paleogeography our samples mostly contain tests and or organic linings of euryhaline tolerant to a wide range of salinity foraminifera of the genera ammonia trochammina and elphidium with ammonia being by far the dominant genus at all locations organic walled dinoflagellate cysts dinocysts such as spiniferites brigantedinium and tuberculodinium vancampoae are also common at a number of sites this association of foraminifera and dinocyst taxa points at varying salinities with aberrant forms of ammonia indicating lower limits of 0 10 psu practical salinity units whereas dinocyst associations suggest more marine conditions such regional heterogeneity is common at the interface of shallow marine to freshwater environments like estuaries we conclude that during the early and middle miocene marginal marine conditions reached at least 2000 km inland from the caribbean portal global high sea level and fast subsidence in the sub andean zone are thought to be the controlling mechanisms of the marine incursions lowering of global sea level and a change in tectonic regime terminated the incursions in the course of the plio pleistocene

asymmetry in holocene river deltas patterns controls and stratigraphic effects abstract understanding controls on sediment distribution in river deltas is paramount to predicting facies relationships and stratal architecture most classifications of deltas have focused on subaerial plan morphology as a simplistic function of river tide and wave energy new work however is revealing the importance of subaqueous deposits and in particular shore parallel sediment redistribution in the shaping of delta planform delta asymmetry has emerged as an important characteristic reflective of patterns of alongshore sediment dispersal asymmetry has been described from onshore and offshore environments from several different types of modern deltas but aspects of asymmetry have not been fully documented and the degree to which these patterns are recorded in deltaic strata is not yet known this study is a comprehensive literature review of sediment distributions in modern deltas focusing on studies with high resolution geomorphic geophysical and geochronological datasets we reviewed 27 deltas using over 100 papers primarily from the past 15 20 years morphological facies and stratigraphic aspects were analyzed across the entire spectrum of deposits from the delta apex to the most distal muds of the prodelta we define quantifiable indices of asymmetry describing upcurrent vs downcurrent distribution of sediment volume sediment area sediment caliber and distributary channels most deltas are asymmetrical to some degree with respect to one or more of these parameters many deltas are increasingly skewed toward the downcurrent side from proximal to distal sub environments i e delta plain delta front prodelta some deltas are skewed toward the upcurrent side in one sub environment and toward the downcurrent side in another sub environment sand is preferentially deposited on the downcurrent side of most deltas but distributary channels tend to develop toward the upcurrent side the highest sand mud ratios are often on the upcurrent side in the lower delta plain but in the delta front these ratios are highest on the downcurrent side these complex patterns of asymmetry reflect different combinations of controls including discharge partitioning lobe abandonment and localized transgression plume deflection by coastal currents dominance of longshore current direction variable subsidence and other factors these processes may result in upcurrent downcurrent variations in clinoform geometry rates of progradation and stratal lapping relationships asymmetry has multiple aspects manifestations and controls even within a single delta but the long term preservation potential of these patterns likely varies depending on depositional setting and shoreline trajectory studies of ancient deltas will be better informed by recognizing the wide variety of controls on sediment distribution and avoiding the tendency toward a single model of delta asymmetry

sand compositional changes as a support for sequence stratigraphic interpretation the middle upper pleistocene to holocene deposits of the roman basin rome italy abstract sand composition is one of the factors of a stratigraphic succession that best records the interaction between allogenic and autogenic processes this is particularly true for the quaternary successions where the effects of this processes are better recognized and differentiated the quaternary succession of the roman basin and in particular the one developed during the late early pleistocene to holocene records a close interaction among tectonic uplift volcanism climate and glacio eustasy such interaction is reflected in a complex stratal pattern and stratigraphic architecture where high rank and low rank depositional sequences are developed and where qualitative and quantitative changes in sand composition are recorded in the same systems tracts the analyzed succession corresponding to the high rank ponte galeria sequence pgs was supplied by the tiber river and its tributaries which developed along the latium tyrrhenian margin such deposits include sediment derived from carbonate to siliciclastic meso cenozoic rocks and from pleistocene volcanic complexes of the roman magmatic province we defined three main sand petrofacies a b c that have a good correspondence with lowstand lst transgressive tst and highstand hst systems tracts of pgs which reflect changes in sand composition and sand provenance under the effects of tectonism volcaniclastic input sedimentary processes and relative sea level variations petrofacies a is feldspatho litho quartzose to feldspatho quartzo lithic in composition it records the erosion and influx of siliciclastic and carbonate rock detritus without volcanic input into the lst fluvial and coastal sands of the pgs petrofacies b is characterized by a modal composition varying from feldspathic to litho feldspathic and feldspatho quartzo lithic it characterizes the tst of the pgs and reflects the abrupt and rapid introduction of volcaniclastic sediment into the system petrofacies c is feldspatho quartzo lithic in composition this petrofacies characterizes the hst of pgs and with respect to the other two petrofacies better records the effects of downstream transport and river mouth sedimentary processes sand samples collected from ancient deposits are similar in composition to the modern tiber river suggesting provenance from a similar river system results show that tectonism during middle upper pleistocene volcanic activity in the sabatini cimini and vulsini volcanic complexes played a major role controlling stream network reorganization in the tiber drainage basin and resulted in enhanced volcaniclastic input from ash fall and recycling of pyroclastic flows volcanic input volcanic lithics and associated phenocrysts and postdepositional alteration during paleosol development define pre syn and post volcanic compositions in the high rank ponte galeria depositional sequence in low rank depositional sequences several processes produced variable quartz feldspar and quartz lithic ratios as well as textural changes these include hydraulic sorting during fluvial and coastal transport and postdepositional in situ weathering processes weathering and pedogenic processes in the source area catchment potentially remove provenance information reducing correlation potential of petrographic signatures of proximal successions in the tiber river sedimentary basin this work tests the effectiveness of using variation in sand composition as a tool in sequence stratigraphy

a numerical study of coupled estuary shelf circulation around the pearl river estuary during summer responses to variable winds tides and river discharge abstract the mean sub tidal circulations in the pearl river estuary pre and over the adjacent shelf are interactive they are driven by multi forcing of winds tides and the buoyancy of river discharge utilizing a validated three dimensional high resolution numerical model we find that the circulation in the pre during summer is dominated by an advective gravitational two layer circulation in the upper estuary and the landward part of the lower pre where the surface flow pattern also varies with the upwelling winds the circulation in the seaward part of the lower pre is governed by both gravitational circulation and geostrophic intrusive current from the shelf the pattern and intensity of these circulations are largely modulated by variable wind forcing the cross shore upwelling shelf circulation off the pre enhances the water exchange rate between the shelf and the pre but the net intrusive transport into the pre is negatively correlated with the intensity of upwelling favorable wind stress relatively strong water exchange rate between the shelf and estuary occurs during upwelling which reduces the flushing time of the estuary although the ebbing flooding tide strengthens weakens the eastward alongshore upwelling current tidal effect on the upwelling circulation and on the net transport between the shelf and estuary is not significant over the sub tidal period the shelf influences the estuary mainly through the intrusions of the shelf waters at the western bank and along the two navigation channels of the pre and they are governed by geostrophic cross shelf upwelling circulation and by gravitational intrusive currents due to pressure gradients yielded by the alongshore variation of the upwelling shelf circulation and by the buoyancy forcing of the river plume respectively

palaeotsunami deposits at the tiber river mouth ostia antica italy do they really exist abstract in this paper we test the recent hypothesis of the occurrence of five to seven tsunami generations that would have struck the ancient harbour basin of ostia italy and the lower channel of the tiber river during the last three millennia because these steady disaster events would have deep implications on our knowledge of the history of rome we reviewed the pluridisciplinary data available at the tiber river mouth considering sedimentological geomorphological micropalaeontological geochemical chronological and historical evidence there is currently no conclusive palaeoenvironmental evidence to suggest past tsunami inundations near ostia river mouths are not the best context in which to identify tsunami deposits high fluvial and coastal mobility generated by regular floods and storms hardly record single high energy events hee from floods storms or tsunamis sediments are regularly reworked at the river mouth both in the river channel and on the close shoreface mixed fluvial and marine influences and the seasonal formation of a salt wedge at the mouth of the tiber create specific estuarine assemblages for micro and macrofauna the layer called high energy event 1 hee 1 on the palaeo shoreface close to the river mouth and hee 4 5 in the point bars of the tiber channel are most probably layers reworked several times by fluvio coastal events storms and or floods hee 3 sealing the republican harbour of ostia is clearly related to flood deposits complementary analyses would be necessary to definitively identify the origins of the hee 2 and hee 7 in the harbour and hee 6 in the palaeochannel or floodplain based on the data available we show how other processes than tsunami inundations could be just as accountable for these coarse grained sediment layers storm deposit flood deposit or riverbank deposit this review puts into question the use of pluridisciplinary proxies to identify palaeotsunami deposits in addition we demonstrate how high pb concentrations constitute a robust proxy to definitively refute the presence of palaeotsunami deposits as such this study will be beneficial to a large community of specialists in coastal research

the modern po delta system lobe switching and asymmetric prodelta growth the modern po delta system comprising five main delta lobes has been investigated by integrating vhr seismic surveys recorded offshore from water depths as shallow as 5 m to the toe of the prodelta in about 30 m with accurate historical cartography extending back several centuries previous studies give sedimentological and geochronological information from precisely positioned sediment cores this combined historical and stratigraphic reconstruction of the modern po prodelta allows volumetric reconstructions indicating an average sediment load of 9 4 10 6 ty r 1 for po di pila and po di goro gnocca lobes this estimate is remarkably consistent with the total sediment load of 11 5 10 6 ty r 1 available for parts of the last century from a gauge station at the apex of the delta plain in pontelagoscuro these integrated stratigraphic studies allow to explain the key characters of the po delta system a the marked asymmetry of the whole delta prodelta system reflecting prevailing sediment dispersal to the south of each individual delta outlet b the shoreparallel overlapping of successive prodelta lobes fed by distinct river outlets of ever changing relative importance c the delta outlets being artificially forced in a fixed position so that natural avulsion is prevented and delta lobes undergo headland retreat leaving a marked erosion on the prodelta d the presence of prodelta lobes showing widespread bcut and fillq features ranging from 100 to 300 m and depths up to 4 5 m filled with massive silt to very fine sand offshore of short lived very active distributary channels e g po di tolle lobe and suggesting that in some particular interval short lived episodes of submarine erosion are induced by catastrophic increases in river discharge of natural origin or induced by human maintenance the seismic stratigraphy of the modern po delta documents that markedly distinct prodelta architectures form when a newly activated lobe is located updrift north in this case or downdrift south of the one that is retreating in the first case the abandoned lobe becomes sheltered by the new rapidly advancing one in the opposite case the retreating lobe is updrift and a substantial portion of the sediment is cannibalized and transported to the new lobe downdrift d 2005 elsevier b v all rights reserved

northern south china sea sst changes over the last two millennia and possible linkage with solar irradiance abstract high resolution surface temperature records over the last two millennia are crucial to understanding the forcing and response mechanism of earth s climate here we report a bidecadal resolution sea surface temperature sst record based on long chain alkenones in a gravity sediment core retrieved from the northern south china sea sst values varied between 26 7 and 27 5 c with a total variability 1 c over the last 2000 years the general sst variation pattern matches well with total solar irradiance tsi changes relatively warm period between 800 and 1400 ad and cool period 1400 1850 ad could be identified in agreement with the commonly defined periods of medieval warm period and little ice age within chronological uncertainty notable short cooling events at 640 670 ad 1030 1080 ad 1260 1280 ad and 1420 1450 ad coincide with large volcanic eruption events the general coincidence of sst changes with tsi and volcanic eruption events suggests strong impact of external forcing on sea surface conditions in the studied area in addition to the direct tsi changes volcanic eruptions might have induced oceanic and atmospheric circulation adjustments which might be responsible for the short cooling events as revealed in the alkenone sst record

significant sst differences between peak mis5 and mis1 along the low latitude western north pacific margin abstract the peak period of marine isotope stage 5 mis5e is the most recent warm period largely comparable to the present interglacial marine isotope stage 1 mis1 the spatial variations in sea surface temperature sst between mis5e and mis1 can reveal the important differences in the effects of insolation and oceanographic conditions between the two warm periods which in turns help refine global climate models in order to quantify the differences this study calculated the sst for the peak periods of mis5e c 128 113 ka bp and mis1 c 8 3 ka bp along the low latitude western north pacific margin 18 on to 26 on together with the previously published data from the south china sea 9 on to 19 on the results indicate a generally northwards decreasing trend in the two interglacial periods this latitudinal sst trend in both peak mis 1 and mis 5e can be attributed to the strong influence of ocean currents in the studied region secondly the average sst of peak mis5e is 1 3 0 2 c higher than that of peak mis1 suggesting a higher level of insolation during the previous interglacial however the above general pattern is complicated by the near shore and offshore difference in the effects of winter monsoon on oceanic conditions around 20 22 on the coastal upwelling near 26 on during peak mis5e reduced the sst whilst the sst was raised as the upwelling ceased during peak mis1 finally the ssts of the two warm periods are significantly higher than the present sst from 20 on northwards implying the influence of winter monsoon cold current in the taiwan strait

holocene evolution of the song hong red river delta system northern vietnam abstract the song hong red river delta located on the western coast of the gulf of bac bo tonkin in the south china sea formed as a result of the song hong sediment discharge throughout the holocene the river s sedimentary basin upstream from the delta plain is not large the delta plain comprises emerged tidal mangrove flats formed during the sea level highstand at 2 3 m 6 4 cal kyr bp and a beach ridge strandplain with straight to lobate beach ridges on the landward and seaward sides of the delta plain respectively the delta affords us the opportunity to examine river mouth morphodynamics comprehensively in relation to sediment discharge and sea level changes in this paper we describe the holocene evolution of the song hong delta system and the river mouth morphodynamics on the basis of seven sediment cores each 30 70 m long taken from the delta plain during 1999 2001 and 101 radiocarbon dates obtained from the core sediments sediments from the seven cores consisting of incised valley fills since the last glacial maximum can be divided in ascending order into fluvial sediments composed of gravelly sand and mottled clay tide influenced estuarine sediments containing shell and wood fragments and deltaic sediments composed of tide influenced sand and mud deposits in which the contents of sand and wood fragments increase upward by applying sequence stratigraphic concepts a transgressive surface can be identified at the gravelly sand mottled clay boundary and the maximum flooding surface can be identified at the estuarine deltaic sediments boundary the lowstand systems tract transgressive systems tract and highstand systems tract record 15 15 9 and 9 0 cal kyr bp respectively during the past 9 kyr the majority of the sediment discharged by the song hong accumulated in the incised valley and enhanced progradation at the river mouth the river mouth prograded from the bay head toward the gulf and its morphology changed from funnel shaped 9 6 cal kyr bp to straight 6 2 cal kyr bp and finally to lobate 2 0 cal kyr bp the morphological change from a funnel shaped to straight coast is interpreted to have been closely related to a hydrologic regime shift from a tide dominated bay head setting to a wave influenced open coast setting the cessation of the sea level rise at 6 cal kyr bp may have played only a small role in the change of river mouth morphology because the progradation rate decelerated from 22 to 4 m yr instead of accelerating at that time the river mouth morphodynamic change from straight to lobate was largely caused by an increase in the song hong sediment discharge from 17 27 9 2 cal kyr bp to 49 million t yr 2 0 cal kyr bp as a result of anthropogenic deforestation along the upper reaches of the song hong