how paleosols influence groundwater flow and arsenic pollution a model from the bengal basin and its worldwide implication in the bengal basin the land surface exposed during the last lowstand of sea level around 20 ka and now buried by holocene sediment is capped by an effectively impermeable clay paleosol that we term the last glacial maximum paleosol lgmp the paleosol strongly affects groundwater flow and controls the location of arsenic pollution in the shallow aquifers of our study site in southern west bengal and by implication in shallow aquifers across the bengal basin and as polluted deltaic aquifers worldwide the presence of the lgmp defines paleointerfluvial areas it is absent from paleochannel areas a paleosol model of pollution proposed here predicts that groundwater in paleochannels is polluted by arsenic while that beneath paleointerfluvial areas is not paleointerfluvial aquifers are unpolluted because they are protected by the lgmp from downward migration of arsenic and from downward migration of organic matter that drives as pollution via reductive dissolution of as bearing iron oxyhydroxides horizontal groundwater flow carries arsenic from paleochannels toward paleointerfluvial aquifers in which sorption of arsenic minimizes the risk of pollution

high resolution sequence stratigraphic analysis of late quaternary deposits of the changhua coastal plain in the frontal arc continent collision belt of central taiwan abstract detailed analysis of the sequence stratigraphy in 30 cores from the late quaternary deposits of the changhua coastal plain provides a 25 ka record of the depositional history of a region situated in the frontal arc continent collision belt of taiwan twenty five lithofacies and nine facies associations are recognized an alluvial plain was the dominant feature during a pronounced sea level fall at 25 20 ka ago between 20 and 10 ka alluvial fans were deposited along the western front of the pakua tableland during movement along the changhua fault and a local sag basin was produced no other deposits in the seaward area are recognized between 20 and 16 ka or in the landward area between 20 and 10 ka between 16 and 6 ka the changhua coastal plain experienced rising sea level and retrogradational deposition from 16 to 10 ka estuarine deposits lower transgressive systems tract were deposited and the base of these deposits defines the last glacial maximum lgm unconformity sequence boundary now preserved in four regions to the east of the plain from 10 to 6 ka shelf shoreface and lagoonal deposits upper transgressive systems tract were laid either on top of the estuarine deposits or directly on the lgm unconformity surface by about 7 6 ka sea level had reached its peak maximum flooding surface and shelf and marginal marine sediments covered most of the study area after 6 ka the highstand was dominated by progradation of offshore transition shoreface lagoonal tidal channel tidal flat and alluvial plain deposits one thousand year old fluvial deposits in incised channels are preserved in the central part of the changhua coastal plain since then fluvial channels shifted southward to the present day chuoshuei river the depositional patterns in this tectonically active area during the last interglacial period reflect the complex interplay between high frequency sea level fluctuations tectonics subsidence and uplift and autocyclic processes in the seaward area however fluctuations in sea level were clearly the dominant factor in controlling the nature of depositional facies

chromium and nickel as indicators of source to sink sediment transfer in a holocene alluvial and coastal system po plain italy abstract a reliable quantitative estimate of changes in source to sink sediment transfer requires that high resolution stratigraphic studies be coupled with accurate reconstructions of spatial and temporal variability of the sediment routing system through time source to sink patterns from the contributing upland river catchments to the deltaic and coastal system are reconstructed from the holocene succession of the po plain on the basis of selected geochemical indicators sediment supplied to the delta area by the major trunk river the po exhibits naturally high cr and ni values which invariably exceed the maximum permissible concentrations for unpolluted sites this anomaly reflects remarkable sediment contribution from ultramafic ophiolitic parent rocks cropping out in the po drainage basin western alps and nw apennines in contrast alluvial and coastal plain deposits supplied by ophiolite free apenninic catchments invariably display lower cr and ni contents for constant sediment provenance domain cr and ni distribution is observed to be controlled primarily by hydraulic sorting clay silt deposits floodplain swamp and lagoon bay facies associations invariably show higher metal concentrations than their sandy counterparts fluvial channel distributary channel and beach ridge facies associations from a stratigraphic perspective in sedimentary basins characterized by strong differences in sediment composition geochemical fingerprinting of individual facies associations framed by surfaces of chronostratigraphic significance is proposed as an invaluable approach towards an accurate quantitative assessment of sediment storage in alluvial and coastal depositional systems as opposed to volumetric reconstructions based on lithologic or geometric criteria alone

bayhead deltas and shorelines insights from modern and ancient examples abstract bayhead deltas are important components of the rock record as well as modern estuaries hosting important hydrocarbon reservoirs and many coastal cities ports and large expanses of wetlands despite their significance few studies have summarized their occurrence and sedimentary characteristics in this paper we review the stratigraphic sedimentary and geomorphic characteristics of 68 modern and ancient bayhead deltas bayhead deltas are found in incised valleys structural basins fjords interdistributary bays of larger open ocean deltas and other backbarrier environments except for within fjords they generally prograde into shallower and more brackish waters than their open ocean equivalents as a result 80 of modern 68 of quaternary and 67 of ancient bayhead deltas have clinoform thicknesses of 10 m or less with 73 of modern bayhead deltas having clinoform thicknesses of 5 m or less additionally 89 of modern 81 of quaternary and 77 of ancient bayhead deltas examined are fluvial dominated we distinguish true bayhead deltas from their genetically similar bayhead shorelines which are not constructional features but sites of enhanced marsh or estuarine sedimentation near river mouths with inadequate rates of sediment delivery to form distributary channels and prograde into the estuary or lagoon we also distinguish confined bayhead deltas found in incised valleys structural basins and fjords from unconfined bayhead deltas found as incipient lobes of larger delta complexes and other back barrier lagoons the architecture of confined bayhead deltas is largely influenced by the limited accommodation brought about by the walls of the flooded valleys in which they are located as such confined bayhead delta ontogeny is controlled by many autogenic interactions within these valley walls both confined and unconfined bayhead deltas are sensitive to sea level rise climate controlled changes in sediment flux and tectonics their relatively small size connection with the terrestrial system and protected nature make them the ideal depositional system to record earth history including sea level and climate changes

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

paleosols and associated channel belt sand bodies from a continuously subsiding late quaternary system po basin italy new insights into continental sequence stratigraphy previous sequence stratigraphic work has emphasized the key role of paleosols and associated sand dominated fluvial bodies as key features for interpreting alluvial architecture the temporal resolution of the ancient record is however insufficient to fully explain the complex relationship between soil formation and the evolution of fluvial systems under changing sea level and climate conditions in this paper we present a detailed record of paleosol channel belt relationships reconstructed from the subsurface of a rapidly subsiding region po plain italy that spans almost all of the last glacial interglacial cycle 120 k y the studied succession preserves a systematic bipartite zonation into a thick paleosol bearing segment close to the basin margin and a sand dominated interval with vertically amalgamated channel belts in an axial position individual paleosols are weakly developed and represent key stratigraphic markers that can be traced basinwide into adjacent essentially contemporaneous unconfined channel belt deposits unlike conventional models of late quaternary alluvial coastal plain systems no persistent incised valley was established in the po system during the last glacial interglacial cycle continuous accommodation was the key depositional control on alluvial stratigraphy during the prolonged 90 k y phase of late pleistocene sea level fall which led to the deposition of a thick dominantly aggradational alluvial succession the development of shallowly incised short lived valley systems took place only at the transition to glacial stages associated with substantial sea level drop marine oxygen isotope stage mis 3 2 transition and possibly mis 5 4 transition this study shows that in rapidly subsiding settings with high rates of sedimentation incised valley systems may be replaced by aggradationally stacked essentially nonincised fluvial bodies in these cases overbank packages bounded by immature paleosols represent the most likely alternative to the highly weathered interfluve paleosol predicted by classic sequence stratigraphic models fourth order sequence boundaries and lower rank erosional surfaces may be easily confused at the 100 k y scale and transgressive surfaces defining the onset of retrogradation may become the most readily identifiable sequence stratigraphic surfaces

fluvial response to late quaternary climatic and environmental change edwards plateau texas abstract radiocarbon controlled late pleistocene to modern stratigraphic frameworks for fluvial systems that drain the edwards plateau westcentral texas coupled with reconstruction of climatic and environmental changes permit development of a model for the evolution of fluvial landscapes during the past 20 000 years during this time large valleys of the edwards plateau were characterized by channel aggradation and sediment storage from 20 to 14 000 yrs b p deep excavation of bedrock valleys from ca 14 to 11 000 yr b p and deposition of extensive and complex valley fills during the last 11 000 yr valley fills contain three distinct unconformity bounded allostratigraphic units representing episodes of channel aggradation and floodplain construction during the early to middle ca 11 000 5000 yr b p and late holocene ca 5000 1000 yr b p and development of the incised channels and associated narrow floodplains of the last 1000 years early to middle holocene alluvial deposits were derived from proximal sources within the respective drainage basins whereas late holocene deposits include sediments derived from distal sources sediment supply to major valleys axes has been extremely limited during the last 1000 years alluvial sequences of the edwards plateau record fluvial responses to climatically driven changes in discharge regimes and the concentration of sediments along valley axes allostratigraphic units define time periods when the concentration of sediment exceeded stream power resulting in sediment storage whereas unconformities record widespread morphological and sedimentary adjustments unconformities between late pleistocene alluvium and holocene valley fills record bedrock valley incision in response to decreased sediment loads associated with slope stability in the uplands by contrast unconformities within the holocene valley fill record floodplain abandonment accompanied by continued channel migration and sediment storage but little additional bedrock valley cutting episodes of floodplain abandonment occurred as a result of decreased flood magnitudes following shifts to drier climatic conditions at ca 5000 and 1000 yr b p fluvial responses to climatic change were conditioned by a progressive degradation of upland soils that caused increases through time in the flashiness of flood events which in turn led to changes in processes of floodplain construction flood events on late pleistocene and early to middle holocene rivers were for the most part contained within channel perimeters and floodplains were constructed by lateral migration by contrast late holocene rivers were characterized by deep overbank flooding and floodplain construction by vertical accretion high magnitude floods were most significant from ca 2500 to 1000 yr b p when large chute channels were cut and filled on floodplain surfaces and soils developed on previously stable terrace surfaces were buried by up to 2 m of fine sands and muds

coastal dynamics under conditions of rapid sea level rise late pleistocene to early holocene evolution of barrier lagoon systems on the northern adriatic shelf italy this multidisciplinary case study of two preserved barrier systems combined the analysis of radiocarbon datings grain size distributions high resolution seismics and shelf bathymetry with reconstructions of palaeo environmental conditions tides waves sea level change and forward modelling of barrier lagoon systems to provide an integrated view of the coastal transgressive evolution of a large sector of the northern adriatic shelf between 15 and 8 ka bp palaeoenvironmental reconstructions point to increased tidal amplitude low energy wave climate and high rates of sea level rise up to 60 mm a during the formation of the oldest preserved barrier system not vert similar90 m water depth 14 3 cal ka bp a younger barrier system 42 m water depth 10 5 cal ka bp formed under conditions of lower tidal amplitude higher wave energy and a lower rate of sealevel rise 10 mm a forward modelling suggests that the probability of barrier island overstepping during transgression is inversely proportional to tidal amplitude if all other factors are assumed equal the oldest barrier lagoon system developed under conditions of large tidal amplitude which permitted rapid transgression however this system apparently failed to keep up with the anomalously high rate of sea level rise resulting from melt water pulse 1a the youngest barrier system appears to have drowned in place due to antecedent topography as the barrier system transgressed over an ancient pleistocene alluvial plain the rapid increase in backbarrier accommodation caused an abrupt disequilibrium between shoreface and backbarrier sedimentation which led to barrier overstepping although barsim modelling indicates that tidal deposition can reduce the probability of barrier overstepping there are other driving mechanisms in our case extremely rapid sea level rise and antecedent topography which are more determinative in explaining the transgressive coastal evolution of barrier lagoon systems in the northern adriatic sea grain size analysis of shoreface deposits sampled above the transgressive ravinement surface across the northern adriatic shelf indicate a distinct relation between the sediment grain size and the rate of sea level rise during deposition which implies that progressive sorting must have been highly effective

transgressive depositional systems of the mississippi delta plain a model for barrier shoreline and shelf sand development abstract depositional sequences generated in the mississippi river delta plain consist of a regressive and a transgressive component the transgressive component has been considerably less studied but accounts for the majority of the surface area on the lower mississippi river delta plain and up to 50 percent of the total sequence thickness in shallow water deltas the development and preservation of transgressive depositional systems in abandoned delta complexes follows the process of transgressive submergence in which the horizontal component of reworking occurs during shoreface retreat combined with a vertical component of submergence acting to preserve the sequence the evolution of transgressive depositional systems in each of the abandoned holocene mississippi river delta complex s can be summarized in a three stage model beginning with stage 1 an erosional headland and flanking barriers in this stage regressive sand deposits contained within abandoned deltaic headlands are reworked by the eroding shoreface and dispersed longshore into contiguous flanking barriers enclosing restricted interdistributary bays submergence of the delta plain during relative sea level rise generates an intradeltaic lagoon separating the former stage 1 sand body from the shoreline forming stage 2 a transgressive barrier island arc the landward migrating barrier island arc is unable to keep pace with relative sea level rise and the retreating mainland shoreline resulting in submergence and the formation of stage 3 an inner shelf shoal following submergence the former barrier island arc sand body continues to be reworked into a marine sand body on the inner continental shelf during stage 3 this sequence of coastal evolution provides direct evidence of barrier island formation with each stage producing a distinctive stratigraphic signature the current sea level rise models of shoreface retreat and in place drowning developed for the u s atlantic continental shelf do not adequately explain either the morphology or the stratigraphy of transgressive mississippi river delta sand bodies current models of mississippi deltaic stratigraphy emphasize the deep water artificially maintained balize delta which differs considerably from the shallow water shelf phase delta complexes that are the primary depositional constituents of he holocene mississippi river delta plain

misleading reconstruction of seawater intrusion via integral depth sampling summary saltwater intrusion in coastal aquifers is an urgent issue for the actual and future groundwater supply and a detailed characterization of groundwater quality with depth is a fundamental prerequisite to correctly distinguish salinization processes in this study interpolated cl maps of the po river delta coastal aquifer italy gained with integrated depth sampling ids and multi level sampling mls techniques are compared the data set used to build up the ids and mls interpolated cl maps come from numerous monitoring campaigns on surface and ground waters covering the time frame from 2010 to 2014 the ids interpolated cl map recalls the phenomenon of actual seawater intrusion with cl concentration never exceeding that of seawater and the absence of hypersaline groundwater all over the study area on the contrary in the mls interpolated cl maps the lower portion of the unconfined aquifer presents hypersaline groundwater making it necessary to consider salinization processes other than actual seawater intrusion like upward flux from a saline aquitard results demonstrate the obligation of using mls in reconstructing a reliable representation of the distribution of salinity especially in areas where the density contrast between fresh and saline groundwater is large implications of the reported field case are not limited to the local situation but have a wider significance since the ids technique is often employed in saltwater intrusion monitoring even in recent works with detrimental effect on the sustainable water resource management of coastal aquifers

new evidence on the evolution of the po delta coastal plain during the holocene abstract the po coastal plain dominated by the po and adige rivers deltaic systems is characterized by beach ridges which mark successive positions of the coastline during the holocene the most evident of these ridges are the most recent ones their dating is mainly based on archaeological and historical data the complex formed by some of the most prominent beach ridges was previously considered by experts to be the first post glacial shoreline this shoreline enclosed a single lagoonal system comprising the lagoon of venice and the delta of the main rivers more recent studies have instead allowed us to recognize other beach ridges older than this one these beach ridges are partially or totally buried by alluvial sediments belonging we believe to active subboreal shorelines additionally other studies we are now carrying out such as the geomorphologic map of the po plain and the venetian lagoonal system project have allowed the identification of older buried intertidal facies this work proposes a progradational model mainly developed by the building of the marine deltas including episodic or discontinuous lagoonal environments in opposition to the continuous lagoonal system model described up to now

wavelet analysis of remote sensing and discharge data for understanding vertical ground movements in sandy and clayey terrains of the po delta area northern italy abstract subsidence phenomena change the proneness of urban and coastal areas to huge flooding particularly in river delta regions many natural and or anthropic processes can induce vertical ground movements identifying the causes of the observed phenomena is a useful even if not easy task for flood forecasting in order to improve the knowledge of natural versus anthropic contributions to vertical ground movements in the present work data analysis techniques polynomial regression analysis frequency analysis and cross wavelet and wavelet coherence analysis are used to analyze both the long and short time scale dependencies between continuous global positioning system cgps and variations of meteorological hydrogeological and hydrological data collected in the po river delta area northern italy from january 2009 to december 2015 the main findings are as follows i occurrence of positive correlations and periodic oscillations of about 2 3 years for all the analyzed meteorological hydrogeological and hydrological records ii a general decrease of the ground level with a faster soil lowering in clayey terrain with respect to sandy terrain and iii negative correlations between cgps and po river discharge records at the intra annual scale 2 6 months which are attributed to an isostatic rebound induced by the change of the river discharge due to precipitation changes over northern italy

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

a simple approach to define holocene sequence stratigraphy using borehole and cone penetration test data cone penetration testing has been widely used since the 1950s for determining the subsurface geotechnical conditions of unconsolidated sediments this paper highlights the potential value of cone penetration testing as an aid to define the stratigraphic structure of holocene sedimentary deposits by calibrating cone penetration test logs with adjacent borehole logs and by utilizing all the available information produced during geotechnical surveying stratigraphic models that accurately describe the vertical and lateral boundaries as well as the stacking pattern of late quaternary systems can be constructed the widespread application and technical simplicity of cone penetration testing combined with simple data interpretation via correlation with adjacent borehole logs yield a useful and inexpensive tool for sedimentological investigations this methodology is illustrated using data from 36 cone penetration tests and 11 boreholes on the holocene deltaic plain of the aliakmon river greece sedimentological and stratigraphic information from core log correlations the spatial distribution of cone penetration test parameters sediment grain size and per cent concentration of organic matter are utilized the results suggest that in sequence stratigraphic terms the delta is divided into a lowstand systems tract composed by fluvial gravels and sands u0 of late pleistocene age as well as from red oxidized clays and a transgressive systems tract represented by fluvial channel sands u1 overlain by a thin transgressive sand sheet of coastal origin u2 characterized by fining upward trends the highstand systems tract is constituted by a variety of stratigraphic units u3 to u7 and depositional environments characterized by coarsening upward sequences representing both aggradational and progradational facies and dominated by the presence of three prograding wedges detailed definition of the thickness vertical boundaries and stacking pattern of the resolved stratigraphic units presented as a two dimensional stratigraphic model demonstrates the applicability of the proposed method

high resolution sequence stratigraphy from piezocone tests an example from the late quaternary deposits of the southeastern po plain abstract cone penetration tests are traditionally regarded as a major tool for geotechnical investigations this study based upon interpretation of 234 cone penetration tests with pore pressure measurements piezocone tests or cptu carried out in the late quaternary deposits of the southeastern po plain shows how cptu tests can also be used for sedimentological purposes including detailed facies characterization subsurface stratigraphic correlations and identification of the key surfaces for sequence stratigraphic interpretation the late quaternary depositional history of the southeastern po plain reconstructed on the basis of data from seventeen continuously cored boreholes includes 1 alluvial plain development during the late quaternary lowstand and the early stages of transgression 2 formation of a rapidly migrating barrier lagoon system during the late transgressive phases 8800 6000 y bp 3 construction and progradation of a wave dominated delta ancient po delta during the following sea level highstand 6000 800 y bp and 4 development of the present day alluvial plain following the delta lobe abandonment in the 13th century a d local execution of cptu tests in coincidence with drilling sites enables the calibration of borehole data with piezocone penetration profiles lithofacies characterization is based upon estimation of three major parameters corrected cone resistance q t sleeve friction f s and pore water pressure u plotting of q t versus the ratio of cone friction to cone bearing fr is adopted as the major tool for sediment texture classification eight major facies associations for the southeastern po plain are identified these are for decreasing q t values 1 fluvial channel sands 2 beach ridge sands 3 transgressive barrier sands 4 crevasse sands and silts 5 levee silts and sands 6 floodplain silts and clays 7 prodelta clays and 8 marsh clays and peats cptu profile interpretation also provides the basis for the identification of the three major key surfaces within the late quaternary 4th order depositional sequence 1 the transgressive surface ts marking the boundary between the locally pedogenized stiff pleistocene alluvial clays and the overlying holocene transgressive paralic deposits has a distinctive pore pressure response with very low u values and is characterized by a sharp downward increase in f s which is paralleled by a moderate increase in q t 2 the ravinement surface rs corresponding to the boundary between fine grained back barrier deposits and the overlying transgressive barrier sands is invariably marked by a sharp upward increase in q t and decrease in fr 3 the maximum flooding surface mfs which is not clearly recognizable on the sole basis of core data is identified within shallow marine prodelta clays in combination with minor peaks of q t which have been interpreted to reflect a laterally extensive fossil lag with transition in proximal areas to sand shell rich layers simplicity speed and comparatively low costs of cptu tests imply that an extensive use of this method when used in conjunction with core programs can be a very attractive alternative to economically less convenient methods for the geological mapping of alluvial coastal plain areas consisting of non gravel deposits

reconstruction of sediment supply from mass accumulation rates in the northern adriatic basin italy over the past 19 000 years reconstruction of sediment supply is hampered by the incompleteness of the stratigraphic record this problem may be partly circumvented by studying mass accumulation rates in closed systems i e basins in which no sediment has bypassed the site of deposition over the time interval of interest we present time averaged basin wide mass accumulation rates and their associated uncertainties from a well documented closed basin the northern adriatic basin italy spanning the time interval from 19 ka b p to the present the sediment masses of five basin wide lithosomes and their associated uncertainties are derived by means of stochastic simulation using highresolution seismic data porosity profiles and radiocarbon datings this study demonstrates that inferring rates of sediment supply from conformity bounded stratigraphic units is feasible as indicated by the excellent agreement of our results of mass accumulation over the past 400 years with two independently derived estimates formation of the stratigraphic record is not an instantaneous process by comparing spatial patterns of mass accumulation rates on three different timescales decadal centennial and millennial we demonstrate a low preservation potential of sediments presently accumulating near the coast and a continuous cross shore and alongshore sediment transport regime the change from transient to persistent accumulation patterns in the highstand systems tract of the northern adriatic basin occurs at the centennial to millennial timescale intrabasinal erosion and recycling of sediments obscure the relation between rates of sediment supply and net basin wide mass accumulation which limits the amount of information that can be extracted from the stratigraphic record hence a mismatch between rates of sediment supply and accumulation rates is expected for unconformity bounded sequence stratigraphic units given the uncertainties associated with our estimates we are unable to reject the hypothesis that net basin wide mass accumulation rates have been constant over the time interval of 19 000 years at a 10 significance level

environmental and climatic conditions at a potential glacial refugial site of tree species near the southern alpine glaciers new insights from multiproxy sedimentary studies at lago della costa euganean hills northeastern italy abstract it has been hypothesized that refugia of thermophilous tree species were located in northern italy very close to the alps though this hypothesis has yet to be tested thoroughly in contrast to central and southern italy with its relative wealth of data only a few fragmentary records are currently available from northern italy for the last glacial wurm weichselian our new study site lago della costa lies adjacent to the catchment of the megafans of the alpine forelands and the braided rivers of the northeastern po plain that have so far inhibited the recovery of continuous glacial and late glacial records we analyze pollen plant macrofossils charcoal and ostracods to reconstruct the vegetation fire and lake history for the period 33 000 16 000 cal bp we compare our data with glacial records from southern europe to discuss similarities and dissimilarities between these potential refugial areas a comparison with independent paleoclimatic proxies allows to assess potential linkages between environmental and climatic variability new macrofossil and pollen data at lago della costa unambiguously document the local persistence of boreal tree taxa such as larix decidua and betula tree species around the study site during the last glacial the regular occurrence of pollen of temperate trees in the organic lake sediments fine detritus calcareous gyttja suggests that temperate taxa such as corylus avellana quercus deciduous tilia ulmus fraxinus excelsior carpinus abies alba and fagus sylvatica most likely survived the last glacial maximum lgm at favorable sites in the euganean hills the percentage values of temperate trees are comparable with those from southern europe e g monticchio in southern italy we conclude that the euganean hills were one of the northernmost refugial areas of temperate taxa in europe however the relative and absolute abundances of pollen of temperate trees are highly variable pollen inferred declines of temperate tree communities e g quercetum mixtum and low ostracod inferred water levels at lago della costa correspond to the cold heinrich events h 2 lgm 23 000 19 000 cal bp and h 3 around 28 000 cal bp as recorded in the marine sediments of the north atlantic similar patterns of significant temperate tree population collapses during cold heinrich events are recorded at southern mediterranean sites e g monticchio and the alboran sea these findings suggest close linkages between northern atlantic and south central european climates during the past glacial

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

freshwater seawater mixing experiments in sand columns summary a study was performed on vertical mixing between freshwater and seawater in controlled column experiments the aim was to quantify the variation in the thickness of the mixing zone caused by water table fluctuations in aeolian dune sandy sediments a series of column experiments were setup first a study on in well mixing was completed to understand the suitability of down hole logging in existing piezometers versus multi level sampling then an unsaturated saturated column experiment with sandy aeolian dune sediments of the target aquifer was performed to characterize the mixing zone thickness finally the third column experiment was conducted by imposing a groundwater fluctuation of 0 1 m to quantify the increase of the freshwater saltwater mixing zone due to vertical water table oscillations the freshwater saltwater mixing zone increase was very limited and did not exceed 0 1 m all experiments were modeled by means of the seawat numerical code and calibrated against saltwater concentrations the model fit was good for all experiments providing insights into the vertical dispersivity of sandy aeolian dune sediments and also into the reliability and precision of the freshwater saltwater interface monitoring methods the down hole logging technique in fact was demonstrated to be inefficient when horizontal flow velocity is negligible in this case only multi level sampling techniques provided reliable results

genetically related alluvial deposits across active fault zones an example of alluvial fan terrace correlation from the upper quaternary of the southern po basin italy integrated studies of alluvial fan systems and related intramontane valley deposits provide potentially useful tools for understanding the character of alluvial sedimentation and its control in fault controlled piedmont zones an example is reported from the uppermost quaternary alluvial deposits of the northern apennines and the southern margin of the po basin a distinctive cyclicity characterizes both the outcropping and the buried units in the study area in intramontane valleys individual cycles consist of regular alternations of sections displaying high and low terrace preservation in the subsurface a rhythmic alternation of coarse grained bodies and laterally extensive pelitic horizons occurs at various scales and represents the basic cyclic motif of the depositional system the correlation between the terrace sequences and the depositional cycles in the subsurface allows the differentiation of distinct sequences with a characteristic internal architecture in the lower part of sequences poorly preserved terrace deposits are laterally correlatable with alluvial fan gravel bodies whereas highly preserved terrace deposits are correlated laterally with predominantly floodplain sediments in the upper part of sequences reliable correlation lines have been constructed using 14c dating thrust tectonics and climate exerted a major control on sequence development deep valley excavation with subsequent low terrace preservation occurred in response to relief rejuvenation during successive thrusting events on the other hand decreasing erosion related to periods of minor tectonic activity led to terrace preservation in the intramontane valleys the coeval episodes of alluvial fan growth and abandonment recorded at the basin margin are interpreted to reflect changes in the efficiency of the drainage system due to variations of tectonic uplift in the adjacent areas alternating phases of deglaciation and renewed glaciation however are inferred to have played a major role in controlling the amount and type of sediment delivered to the alluvial fan complexes

global sea level control on local parasequence architecture from the holocene record of the po plain italy abstract holocene deposits exhibit distinct predictable and chronologically constrained facies patterns that are quite useful as appropriate modern analogs for interpreting the ancient record in this study we examined the sedimentary response of the po plain coastal system to short term millennial scale relative fluctuations of sea level through high resolution sequence stratigraphic analysis of the holocene succession meters thick parasequences form the building blocks of stratigraphic architecture above the younger dryas paleosol a prominent stratigraphic marker that demarcates the transgressive surface early holocene parasequences s 1 3 record alternating periods of rapid flooding and gradual shoaling and are stacked in a retrogradational pattern that mostly reflects stepped post glacial eustatic rise conversely middle to late holocene parasequences s 4 8 record a complex pattern of coastal progradation and delta upbuilding that took place following sea level stabilization at highstand starting at about 7 cal ky bp the prominent transgressive surface at the base of parasequence 1 correlates with the period of rapid global sea level rise at the onset of the holocene mwp 1b whereas flooding surfaces associated with parasequences 2 and 3 apparently reflect minor early holocene eustatic jumps reported in the literature changes in shoreline trajectory parasequence architecture and lithofacies distribution during the following eustatic highstand had instead an overwhelming autogenic component mostly driven by river avulsions delta lobe switching local subsidence and sediment compaction we document a 1000 year delayed response of the coastal depositional system to marine incursion farther inland from the maximum landward position of the shoreline a dramatic reduction in sediment flux due to fluvial avulsion resulted in marine inundation in back barrier position whereas coastal progradation was simultaneously taking place basinwards we demonstrate that the landward equivalents of marine flooding surfaces parasequence boundaries may be defined by brackish and freshwater fossil assemblages and traced for tens of kilometers into the non marine realm this makes millennial scale parasequences whether auto or allogenic in origin much more powerful than systems tracts for mapping detailed extents and volumes of sediment bodies the holocene parasequences of the po coastal plain with strong age control and a detailed understanding of sea level variation may provide insight into the driving mechanisms and predictability of successions characterized by similar depositional styles but with poor age constraint resulting in more robust interpretations of the ancient record

fluvial evolution of the rhine during the last interglacial glacial cycle in the southern north sea basin a review and look forward this paper presents the current state of knowledge on the evolution and depositional history of the river rhine in the southern part of the north sea basin during the upper middle and late pleistocene and its response to climate change sea level oscillation and glacio isostasy the study focuses on the development of the eemian interglacial lower delta in the central netherlands and its relation to records of climate and sea level rise and uses the saalian and weichselian pre and postdating periods to place its development in context the rhine fluvial system fills the gradually subsiding north sea basin but its development has strongly been affected by the saalian glaciation and its remaining topography ice pushed ridges originating off the limit of maximum glaciation basically divided the central netherlands into two sedimentary depocentres a central depocentre within the former ice limit and a southern depocentre south of it the sedimentary record of the central depocentre including an incised valley fill shows a 20 40m thick stacked sequence consisting of three units the incised valley fill consists of a late saalian to early eemian age lower fluvial unit and a weichselian age upper fluvial unit both composed of coarse grained channel deposits sandwiched in between is a 5 15m thick record composed of fine grained fluvial and estuarine tidal floodbasin and shallow marine deposits it is of eemian interglacial and early weichselian age and comprises transgressive and highstand deposits that show the drowning of a fluvial system inland parts transformed from fluvial to deltaic and estuarine environments and the most downstream parts transformed to a shallow marine embayment preservation of these units occurred despite considerable sea level fall and climate controlled erosion taking place in the last glacial preservation potential was increased by the fact that the rhine system avulsed away to the southern depocentre halfway the weichselian pleniglacial consequently the infill of the southern depocentre is of an entire different nature and last interglacial transgressive or highstand units are hardly preserved because of glaciation and resulting depocentre configuration the netherlands in nw europe thus offers a very good opportunity to study the transgressive interglacial lower deltaic records and falling stage preservation thereof both key elements for understanding sedimentary development over full 100 ky glacial interglacial cycles of climate and base level change 2014 elsevier ltd and inqua

late quaternary stratigraphy and paleogeography of the eastern nile delta egypt abstract a petrological study of numerous sediment borings identifies the late pleistocene and holocene lithofacies in the northeastern nile delta of egypt a coarsening upward sequence characterizes the major holocene depocenters located along the northern margin of the present delta stratigraphic correlation of radiocarbon dated sections and mapping of key facies such as delta front mud reveal the locations of four major holocene delta lobes related to former distributary branches of the nile river mendesian pelusiac tanitic and pre modern damietta these lobes formed primarily of marine prodelta and delta front deposits interfinger geographically but radiocarbon dating indicates that their bases are not synchronous lobes developed for the most part since 8000 years b p i e as the rate of eustatic sea level rise began to decrease climatic and sediment discharge fluctuations lateral migrations of distributaries and isostatic subsidence of land are additional factors that affected the temporal and spatial distributions of the lobes paleogeographic maps reveal the changes with time in the distributions of different lobes and deltaic plain environments marsh lagoons and concomitant displacement of the coastline holocene sediment accumulation rates to 500 cm per 1000 years are calculated this is 10 times greater than that on the nile cone and 50 times greater than on the egyptian continental shelf the delta coastal margin in the study area migrated northward by as much as 50 km during the past 5000 years an average progradational rate of up to 10 m per year the general configuration of the present delta developed during the past millennium the major changes recently induced by man in this region coupled with a series of continuing natural phenomena slow rise in sea level coastal erosion subsidence have markedly affected the evolution of the delta petrological study of the nile delta sediments provides baseline reference information to help recognize changes in the recent geological past to help identify those taking place at present and possibly to help predict those likely to occur in this region in the future

longitudinal profile evolution of the rhine meuse system during the last deglaciation interplay of climate change and glacio eustasy fluvial longitudinal profiles reconstructed from abandoned floodplains contain significant evidence about the role of relative sea level vs climatic and tectonic controls on depositional systems two weichselian floodplain surfaces that occur as terraces updip of the hinge zone of the rhine meuse system have recently been mapped beneath the holocene rhine meuse delta the netherlands their vertical offset is several metres in the upstream area and decreases to only 0 4 m in the central part of the delta the older and higher of the two floodplain surfaces is generally assumed to have been formed around the last glacial maximum whereas the younger dates to the younger dryas following a phase of climatically induced fluvial incision during the bolling allerod the downstream convergence of these two floodplain surfaces may be related to the relative rise of sea level forcing the rhine meuse system to become graded to a higher base level during the younger dryas the upper weichselian rhine meuse system then provides an example of a basin marginal fluvial system that responds in terms of its longitudinal profile to the combined effects of upstream control primarily climate change affecting water and sediment flux from the hinterland and downstream control glacio eustatically driven relative sea level change this new evidence may therefore revitalize the presently unfashionable concept of relative sea level control penetrating many hundreds of kilometres inland

sand composition and sedimentary evolution of a late quaternary depositional sequence northwestern adriatic coast italy abstract in order to detect temporal and spatial variations in detrital supply in the upper part of the last depositional sequence of late pleistocene holocene age we conducted a combined petrographic and stratigraphic study in the romagna coastal plain south of the po delta northern italy we analyzed heavy minerals and the bulk composition of sands from cores and surface samples by using petrographic and stratigraphic data on composition of modern beach and major river deposits new aspects of detrital dispersal mechanisms and the depositional history of the study area are documented the heavy mineral distribution coupled with the dolostone and volcanic rock fragment contents of bulk sands allow identification of three different petrofacies petrofacies a petrofacies b and petrofacies c which have been interpreted as of apenninic mixed eastern alps po river basin and po river catchment basin provenance respectively distribution of the three petrofacies changed through time in response to landward and seaward shifting of the coastline during the late pleistocene lowstand a pure apenninic provenance characterized the romagna coastal plain petrofacies a during the holocene transgression when the shoreline migrated tens of kilometers west of its present position eastern alpine sediment sources fed littoral facies petrofacies b probably as a result of southward transport by littoral drift this sediment supply continued during the early regressive phases and was cut off by a change in coastal morphology related to the development of the early po delta this led to the establishment of a sediment supply entirely related to the po river catchment basin petrofacies c changes in the compositional signature of sand in the youngest beach ridges mark the abandonment of the early po delta due to an avulsion event and testify to the establishment of a coastal system fed by rivers draining the apennines petrofacies a we emphasize sand petrography as an important tool in studying the internal architecture of sandy clastic depositional units on detailed spatial scales and its use in deciphering the depositional history of complex sedimentary successions fig 1 location of the study area end page 829

surface electrical resistivity tomography and hydrogeological characterization to constrain groundwater flow modeling in an agricultural field site near ferrara italy a portion of an unconfined alluvial aquifer located in the padana plain italy was characterized following an integrated hydro geophysical approach initially an electrical resistivity tomography ert survey was employed to localize the boundaries of a modest paleo channel body and to design the installation of a groundwater monitoring network multilevel slug tests were performed to estimate the aquifer s saturated hydraulic conductivities determined permeability values together with electrical resistivity data were correlated the correlation resulted in a site specific bi logarithmic linear relationship based on this relationship punctually determined hydraulic conductivities were spatially extended over the studied flow domain finally continuously measured piezometric heads were used to calibrate a 3d flow model sensitivity analysis was performed to confirm the reliability of the reconstructed permeability field as well as to assess the minimum number of direct measurements needed to safely characterize the selected aquifer portion the integration of the ert survey results with the classical hydrogeological tests can be conveniently applied to constrain the permeability field during flow model calibration although the applicability of the determined relationship is site specific the followed procedure is useful especially when there is a need to optimize the available resources and in case of small scale pilot studies

inverse modeling of post last glacial maximum transgressive sedimentation using 2d sedflux application to the northern adriatic sea abstract a coupled simulation of the hydrologic model hydrotrend and the stratigraphic model 2d sedflux is applied to transgressive deposits in the north adriatic sea area over the last 21 000 years synthetic sediment discharge from the po river which increases more than 70 during late pleistocene compared to those during holocene due to glacier melt and enlarged drainage area is employed in the simulation of sediment deposition by the process based forward model 2d sedflux paleo morphology is reconstructed in a pseudo inverse manner by comparing the predicted deposit distribution and the modern morphology accommodation for thick prograding deposits in the modern po delta and the po lowstand delta are created by drawing back the modern bathymetric profile the bathymetric profile is then adjusted for aggradational deposits these sequential simulations produced a likely profile of the paleo morphology which had accommodation matching with the sediment supply evaluation of effects of waves however suggested that the predicted rate of sediment input was too low to produce a prograding delta a good match with the observation of the modern po delta was achieved when further adjustments in basin width was properly made

late quaternary palaeoenvironmental evolution of the adriatic coastal plain and the onset of po river delta abstract despite abundant geologic literature about the po coastal plain stratigraphic architecture beneath modern po river delta is virtually unknown in this paper combined sedimentological micropalaeontological and geochemical investigations of three continuous cores cores 1 to 3 about 40 m thick enable for the first time the detailed reconstruction of subsurface stratigraphy in the po river delta area along with its late quaternary palaeoenvironmental evolution lowstand deposits formed during the last glacial maximum are expressed as a fining upward succession of fluvial channel and related overbank deposits capped by a stiff overconsolidated horizon above this unconformable surface the lower post glacial succession transgressive systems tract or tst is less than 7 m thick and includes a deepening upward succession of back barrier shoreface and inner shelf deposits on the other hand the overlying highstand systems tract is considerably thicker up to 27 m and comprises the bulk of recent delta progradation i e vertically stacked prodelta delta front and delta plain deposits stratigraphic correlations within early transgressive back barrier deposits show vertically stacked thin shallowing upward successions reflecting an internal subdivision of tst into small scale parasequences the homogeneous shallow marine clay that accumulated at the turnaround from transgressive to highstand conditions can be palaeontologically differentiated into two packages miliolidae dominated and ammonia cribroelphidium dominated reflecting open marine and river influenced conditions respectively timing of maximum marine ingression maximum flooding surface mfs is recorded within the open marine clays at about 5500 calibrated yr bp by minor changes in microfauna geochemical characterization of core 1 testifies that distinct changes in sediment provenance accompanied the palaeoenvironmental evolution of the study area under changing relative sea level conditions at lowstand times the study area was an alluvial plain under the influence of adige river as suggested by comparatively high ba al values within pre holocene fluvial deposits increasing upward values of cr al 2 o 3 and ni mg within tst suggest an increasing sediment provenance from the po river during early stages of transgression via the longshore drift the onset of modern age po delta in the study area is precisely identified in core 1 at 25 10 m depth and has a distinctive double signature in terms of microfaunal assemblages po river sediments are clearly marked by the development of a characteristic foraminiferal association dominated by the opportunistic species nonionella turgida a taxon typically abundant in the marginal zone of present northern adriatic sea mud belt po river deposits are also fingerprinted by a peculiar geochemical composition corresponding to maximum cr and ni concentrations

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

millennial scale depositional cycles from the holocene of the po plain italy the holocene depositional history of southeastern po plain on time scales of 103 yr is reconstructed based upon integrated sedimentological and micropalaeontological analyses of nine continuously cored boreholes about 40 m deep major palaeoenvironmental changes include the rapid landward migration of a barrier estuary lagoon system during the early middle holocene transgressive systems tract tst followed by extensive delta progradation in the last 6000 yr highstand systems tract hst detailed facies analysis of cores combined with the identification of 12 microfossils benthic foraminifer and ostracod associations allow an ultra high resolution sequence stratigraphic framework to be reconstructed particularly eight small scale high frequency cycles about 3 5 m thick and spanning intervals of time of about 1000 yr can be physically traced throughout the study area interpretation of these cycles which are invariably bounded by sharp flooding surfaces and generally show internal shallowing upward trends parasequences indicates that relative sea level changes during the holocene were episodic and punctuated by rapid phases of sea level rise followed by periods of stillstand or decreasing sea level rise from seaward to landward locations parasequence boundaries document beach barrier migration bay head delta abandonment and increasing accommodation in the coastal plain the ensuing phases of sea level stillstands resulted in the progressive filling of the newly formed accommodation space through beach progradation extensive mud deposition in behind barrier lagoonal estuarine and marsh deposits and aggradation in bay head delta systems at the head of estuaries eustacy appears to be the major controlling factor of the retrogradational stacking pattern of parasequences within the tst by contrast a complex interplay of eustacy sediment supply and subsidence with an increasing influence of autocyclic mechanisms such as channel avulsion and delta lobe abandonment controlled facies architecture within the hst the maximum flooding surface cannot be assumed to be synchronous its timing being strongly dependent upon local variations in sediment influx and subsidence this study shows that the micropalaeontologic characterization of mud prone coastal plain and estuarine successions in terms of water depth and salinity can lead to very accurate sequence stratigraphic interpretations allowing identification of parasequence boundaries that may not be detected by conventional stratigraphic approach

continental depositional systems of the quaternary of the po plain northern italy abstract the po plain is a molasse foredeep bounded by two mountain chains apennines and alps apenninic thrusting is still active whereas the alpine one ended by early pliocene times the continental deposits form a veneer at the surface and form the topset of a prograding complex the po river divides the plain into two sectors with different sedimentary facies and body geometries to the south the alluvial fan and plain deposits are small embedded in clays and show elongate shapes to the north sedimentary bodies are laterally extensive tabular and with minor amounts of fine grained sediments this difference could be due to a different climatic conditions during quaternary ice ages on the two sides of the basin b different structural settings in the two sectors of the basin that produce a higher subsidence rate to the south c different lithologies in the source areas i e alps and apennines

onshore to offshore anatomy of a late quaternary source to sink system po plain adriatic sea italy abstract in understanding the evolution of siliciclastic systems late quaternary analogs may enable reliable predictive models of facies tract architecture the po plain adriatic sea system where a wealth of research has been conducted during the last 20 years represents one of the most intensively investigated late quaternary successions with the aid of a chronologically well constrained stratigraphy paleoenvironmental evolution is tracked for the first time from fluvial to deep marine realms over 1000 km in length vertical stacking trends onshore and stratal terminations offshore are the key observations that allow identification of surfaces with sequence stratigraphic significance systems tract boundaries in the distinct segments of the system recurring motifs in stratigraphic architecture showing tight coupling of sedimentary responses among source area catchment basin and coastal and marine depocenters reveal a cyclicity driven by glacio eustatic fluctuations in the milankovitch band due to high rates of subsidence middle pleistocene forced regressive systems tracts are exceptionally expanded and the mis5e mis2 interval late pleistocene preserves a nearly continuous record of fourth order 100 kyr stepwise sea level fall the stratigraphic architecture of last glacial maximum deposits highlights the genetic relations between channel belt development pedogenesis and sediment delivery to the lowstand delta through narrow incised valley conduits the late glacial holocene succession records the last episode of sea level rise and stabilization through well developed patterns of shoreline transgression regression tst hst that can be readily traced updip from offshore to onshore locations architectural styles across the whole system reflect a dominance of allogenic forcing in the tst as opposed to a predominantly autogenic control on stratigraphic development in the hst external drivers of facies architecture were also effective on millennial timescales the younger dryas cold reversal which marks the transgressive surface on land records a short lived episode of subaqueous progradation that is correlative onshore with widespread immature paleosol development and small sized channel belt formation quantitative assessment of sediment budgets over different time intervals requires precise positioning of the key bounding surfaces based on this approach we outline for the first time over the entire po adriatic basin an estimate of the sediment volumes stored in each systems tract

processes governing natural land subsidence in the shallow coastal aquifer of the ravenna coast italy abstract we identified the processes governing natural land subsidence in a shallow coastal aquifer near ravenna north eastern italy by analysing the relationships among different data set time series water table level rainfall drainage sea level etc and establishing the correlations with vertical ground motion observed at a high resolution settlement gauge for the first time we establish the relationships between water table fluctuations and vertical displacement in a real field dataset as well as demonstrate the important contribution of primary consolidation and aquifer stratigraphy to natural land subsidence our study highlights the presence of three deformation components related to different processes controlling land subsidence elastic delayed elastic and irreversible plastic components the elastic and delayed elastic components are closely related to water table fluctuations that change the effective stress in two portions of the coastal aquifer at a daily in the sandy unconfined portion and seasonal time scales in the finely layered clay rich semiconfined prodelta portion respectively the irreversible component represents the trend in the land subsidence time series and is due to primary consolidation pore water pressure dissipation of the fine grained prodelta levels above where the settlement gauge is located the amplitudes of the elastic component can be up to 0 2 0 3 mm whereas the amplitude of the delayed elastic component reaches 0 89 mm the primary consolidation rate of deformation is 0 9 mm year and constrains the likely age of prodelta sediments deposition to 1300 2800 years before present the average degree of consolidation for the prodelta sediments varies from 0 8 to 0 99 according to consolidation coefficients varying from 1 58 to 3 15 m2 year which are accepted values in the literature our analysis point out that primary consolidation in the shallow fine grained sediments of the shallow coastal aquifer is still ongoing the delayed elastic land subsidence rate has similar magnitude to that due to primary consolidation and is likely connected to poroelastic effects in the prodelta sequence following seasonal variations in water table our findings are important for planning land subsidence management and monitoring strategies especially where the surface aquifer structure is heterogeneous due to different depositional settings

ammonium occurrence in a salinized lowland coastal aquifer ferrara italy to understand the spatial distribution and the possible sources of high ammonium concentration in the unconfined coastal aquifer of the po river delta lowland italy a detailed characterization of inorganic nitrogen species was completed a total of 59 boreholes were drilled to collect core samples and groundwater samples of the aquifer among them four piezometers located along a representative flow line were chosen to monitor the inorganic nitrogen concentrations with depth ammonium is the prevalent nitrogen inorganic species in groundwater and its concentration increases with depth and salinity very high ammonium concentrations are found in coincidence with peaty sediments in the salinized anoxic aquifer and in the low lying aquitard in particular the elevated ammonium concentration derives from mineralization of organic matter present in fine sediments deposited in paleo marsh environments copyright 2012 john wiley sons ltd

facies architecture and latest pleistocene holocene depositional history of the po delta comacchio area italy abstract integrated sedimentological and micropaleontological study of 16 cores and 137 piezocone penetration tests approximately 40 m deep in the comacchio area enables the documentation of the depositional history of southeastern po plain in the last 30 ka in response to fluctuating sea level sedimentation within an alluvial plain was the dominant feature across the entire study area during the pronounced sea level fall that culminated in the last glacial maximum thin lowstand fluvial sediments form the lower part of a shallow incised valley above the last glacial maximum unconformity whereas a characteristic paleosol separates the last glacial alluvial plain deposits from the overlying postglacial deposits in the interfluves transgressive and highstand deposits show a well developed stacking pattern of retrogradational coastal plain and estuarine and progradational deltaic facies detailed reconstruction of transgressive paleogeography shows evolutionary features that can be useful for refin

volcanomagnetic signals associated with the quasi continuous activity of the andesitic merapi volcano indonesia 1990 1995 abstract merapi volcano in java island indonesia is an andesitic stratovolcano which presents long periods of effusive activity during which an endogeneous dome is continuously growing the viscous lava dome gives rise to unstable blocks which collapse or turn into pyroclastic flows when the volcano does not exhibit any surface activity the overpressure within the volcano slowly increases depending on the quietness duration the unrest of the volcano can start with an explosive phase during which the former dome is partly destroyed magnetic variations of different time constant are observed during the 1990 1995 period which includes one gas plume emission on august 26 1990 and two eruptions on january 20 1992 and on november 22 1994 compared with other types of active volcanoes the observed volcanomagnetic variations are very small at the most a few nanoteslas nt to discriminate the variations associated with the global activity from the signals correlated with each unrest phase one has to dissociate the different time constant variations over the six year time span when long term trends are removed from the magnetic field in each station of the network an outstanding correlation between all the magnetic differences is emphasised the midterm variations point out 2 cycles of activity which fit the stress field evolution within the edifice leading to the 1992 and 1994 eruptions a new cycle has started in may 1995 in every identified cycle rapid volcanomagnetic signals are well associated with stress field changes may 1991 september 1991 february 1993 december 1993 some of the volcanomagnetic variations are short term precursory signals as the three months decrease up to 1 3 nt preceding the 1992 eruption the comparison between magnetic data seismicity and surface phenomena implies that the midterm volcanomagnetic variations associated with the cycles of merapi activity are of piezomagnetic origin

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

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

low temperature magnetic transition of chromite in ordinary chondrites 1 we present low temperature magnetic data thermal demagnetization hysteresis obtained on thirty three ordinary chondrite meteorites a magnetic transition is observed in the 40 80 k range average 66 k and is interpreted as a ferrimagnetic to paramagnetic phase transition we present quantitative analyses of changes in magnetization across the magnetic phase transition and chemical elemental analyses to argue that chromite a common accessory mineral in meteorites is the mineral undergoing the phase transition and not troilite or tetrataenite as proposed in previous studies moreover we observe a correlation between the measured curie temperature and chemical composition of chromites in ordinary chondrites low temperature magnetic measurement are thus a sensitive indicator of chromite composition in these meteorites and as such a possible proxy to the understanding of their thermal metamorphism

sand composition changes across key boundaries of siliciclastic and hybrid depositional sequences abstract sand composition of arenite successions is sensitive to a suite of factors operating between initial grain production and final diagenesis on a variety of spatial and temporal scales seven allogenic factors the relative importance of which relies upon the complex interaction between tectonics eustasy and climate play a decisive role in dictating petrofacies distribution within siliciclastic to hybrid depositional sequences these factors include i tectonic exhumation ii physical and chemical rock breakdown iii change in sediment flux iv change in source basin physiography v shelf colonization by organisms vi generation of chemical grains and vii volcanism autogenic processes may locally have a considerable influence on the type and amount of sediment supplied to the basin thus interfering with the external control based upon literature data a conceptual framework of expected compositional changes across the key surfaces for sequence stratigraphic interpretation is outlined two case histories from the miocene shelf to turbidite deposits of the northern apennines and the quaternary alluvial to nearshore succession of the adriatic coast respectively are used as references to illustrate how arenite petrofacies changes can be framed into a sequence stratigraphic scheme on multiple timescales

influence of sediment provenance on background values of potentially toxic metals from near surface sediments of po coastal plain italy systematic variability in metal concentrations is recorded in near surface 1 m deep late quaternary sediments of po coastal plain across the boundary between alluvial deposits of apenninic provenance and a formerly active now abandoned delta lobe of the po river in the latter area high cr and ni concentrations exceeding the national standard limits are attributed to sediment provenance from ultramafic source rocks of po catchment basin and not to anthropogenic impact spatial distribution of carbonate related elements such as ca and sr displays consistent differences between the two areas confirming a primary control of provenance domains on sediment composition accurate facies characterization of near surface sediments coupled with detailed information on sediment dispersal patterns enable a reliable interpretation of the spatial variability of major elements and trace metals in the study area particularly detailed reconstructions of source area composition and changes in flow directions through historical times allow precise correlation of apparently anomalous geochemical patterns with distinctive depositional events such as shifts in channel course crevasse splay formation and beach ridge evolution the findings of unusually high natural provenance controlled heavy metal concentrations in pre industrial near surface levels highlight the contribution of a sedimentological approach to a reliable interpretation of geochemical data this should be taken into account when determining background values versus anthropogenic impact

reclamation influence and background geochemistry of neutral saline soils in the po river delta plain northern italy reclaimed neutral saline sulphate soils constitute a large part of the eastern part of po plain lowlands where intensive agricultural activities take place the knowledge of their geochemical features is essential to develop the best management practices capable to preserve this threatened environment with this aim three boreholes were drilled in an agricultural field and a typical reclaimed soil profile has been characterized for major and trace element ph electrical conductivity redox conditions and water soluble anions and ammonium statistical analysis cluster analysis and principal component analysis has been used to understand the relationship between elements and grain size the soil profile is characterized by high salinity and high organic matter contents responsible for high chloride sulphate and ammonium concentrations heavy metal content is naturally high since po plain sediments are the result of ultramafic rocks erosion in addition organic matter tends to concentrate heavy metals by adsorption mainly in peaty horizons as a consequence of chemical and zootechnical fertilization high no3 contents have been found in the top soil thus enhancing the risk of nitrate discharge in the water system especially in relation to extreme climatic events

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr