grain size and heavy minerals of the late quaternary eolian sediments from the imbituba jaguaruna coast southern brazil depositional controls linked to relative sea level changes abstract the stratigraphic subdivision and correlation of dune deposits is difficult especially when age datings are not available a better understanding of the controls on texture and composition of eolian sands is necessary to interpret ancient eolian sediments the imbituba jaguaruna coastal zone southern brazil 28 29 s stands out due to its four well preserved late pleistocene eolian generation 1 to holocene eolian units eolian generations 2 3 and 4 in this study we evaluate the grain size and heavy mineral characteristics of the imbituba jaguaruna eolian units through statistical analysis of hundreds of sediment samples grain size parameters and heavy mineral content allow us to distinguish the pleistocene from the holocene units the grain size displays a pattern of fining and better sorting from generation 1 older to 4 younger whereas the content of mechanically stable dense and hard heavy minerals decreases from eolian generation 1 to 4 the variation in grain size and heavy mineral content records shifts in the origin and balance input versus output of eolian sediment supply attributable mainly to relative sea level changes dunefields submitted to relative sea level lowstand conditions eolian generation 1 are characterized by lower accumulation rates and intense post depositional dissection by fluvial incision low accumulation rates favor deflation in the eolian system which promotes concentration of denser and stable heavy minerals increase of ztr index as well as coarsening of eolian sands dissection involves the selective removal of finer sediments and less dense heavy minerals to the coastal source area under a high rate of relative sea level rise and transgression eolian generation 2 coastal erosion prevents deflation through high input of sediments to the coastal eolian source this condition favors dunefield growth coastal erosion feeds sand from local sources to the eolian system including sands from previous dunefields eolian generation 1 and from drowned incised valleys therefore dunefields corresponding to transgressive phases inherit the grain size and heavy mineral characteristics of previous dunefields leading to selective enrichment of finer sands and lighter minerals eolian generations 3 and 4 developed during a regressive progradational phase holocene relative sea level highstand the high rate of sediment supply during the highstand phase prevents deflation the lack of coastal erosion favors sediment supply from distal sources fluvial sediments rich in unstable heavy minerals thus dunefields of transgressive and highstand systems tracts may be distinguished from dunefields of the lowstand systems tract through high rates of accumulation low deflation in the former the sediment source of the transgressive dunefields high input of previously deposited coastal sands differs from that of the highstand dunefields high input of fluvial distal sands based on this case study we propose a general framework for the relation between relative sea level sediment supply and the texture and mineralogy of eolian sediments deposited in siliciclastic wet coastal zones similar to the imbituba jaguaruna coast

upper ocean variability between iceland and newfoundland 1993 1998 we investigate the variability of upper ocean temperature and surface salinity between iceland and newfoundland along world ocean circulation experiment line ax2 in 1993 1998 north of 54 n as well as close to newfoundland deviations from the seasonal cycle indicate upper ocean warming from 1994 to 1998 with largest anomalous warming during late 1995 early 1996 and during the winter 1997 1998 north of 54 n surface salinity increases after mid 1996 the winter of 1995 1996 is the first winter of weak westerlies after more than 20 years of strong westerly conditions in the subarctic gyre and the ocean loses less heat during that winter than during a normal year the magnitude of upper ocean heat content change is at least twice as large as what results from the change in air sea fluxes which indicates a complementary contribution to heat content change by advection altimetric sea level data indicate also an increase of sea level of the order of 6 5 cm during that year out of which more than 4 cm is contributed by the steric change associated with the temperature increase a principal component analysis of the sea level data suggests that the increase sensed along line ax2 west of the reykjanes ridge is found in most of the subpolar gyre although to a lesser extent in most other areas

control factors in the evolution of holocene coastal barriers in southern brazil abstract the evolution and behavior of coastal barriers are controlled by several allogenic and autogenic factors some of these may be more deterministic than others in this study the geombest morphostratigraphic model is used to evaluate the degree of influence of both the substrate slope and the long term sedimentary budget on the evolution of an extensive lagoon barrier system during the mid late holocene in the middle littoral of rio grande do sul state southern brazil along this coastal stretch there is a coexistence of barriers with regressive transgressive and stationery morphological behavior over 200 km the modern configuration of the holocene system shoreline position and the lagoon barrier width was reproduced through the variability of two factors the substrate slope which defines the horizontal and vertical distance that the barrier will translate and rotate and the sedimentary budget which controls the evolution of the barrier when sea level oscillates slowly the substrate slope of the middle littoral between 0 021 and 0 149 determined the cross shore position of the shoreline and the exogenous input or removal of sediment estimated between 8 to 4 5 m3 m a allowed establishing the type of barrier behavior in the last millennia thus the substrate slope exerts both direct and indirect control on coastal evolution according to sensitivity analysis a small decrease in the slope of the substrate on the order of 0 001 can increase the resulting barrier translation by 150 m considering a 1 m rise in sea level over a 100 year interval

weakening of northeast trade winds during the heinrich stadial 1 event recorded by dune field stabilization in tropical brazil the identification characterization and mapping of large areas of stabilized eolian features along the tropical northeastern brazilian coast enabled recognition of the existence of one of the largest quaternary dune fields 16 000 km 2 in south america this paleodune system is observed inland of the lencois maranhenses transgressive dune field 2 5 s 43 w and comprises deflation plains stabilized parabolic dunes and barchanoid chains developed under the action of northeast ne trade winds optically stimulated luminescence ages coupled with geomorphological analysis were used to constrain the time of dune field stabilization ages of stabilization of parabolic dunes and barchanoid chains throughout this paleodune system range between 19 to 14 ka showing heterogeneous dune stabilization by vegetation growth during a 5 ka time interval dune field stabilization is related to a decrease in ne trade wind strength and increase in precipitation as a consequence of the southward shift of the intertropical convergence zone during the heinrich stadial 1 event 18 15 ka which resulted in a lower eolian drift potential less sand input by alongshore transport and low sediment availability to eolian transport due to an increase in moisture to support vegetation growth and rising relative sea level

morphology of the itapeva to tramandai transgressive dunefield barrier system and mid to late holocene sea level change the surface morphology of the transgressive dunefield barrier extending from itapeva to tramandai along the northern littoral of rio grande do sul is examined and an attempt is presented to link morphological changes across the barrier to holocene sea level changes the 4 5 km wide holocene barrier displays two typical morphologies an inner part dominated by large scale continuous alongshore overlapping dunefield phases comprising sand sheets dunes deflation plains and precipitation ridges and an outer part dominated by discontinuous medium to small scale triangular to lobate transgressive dunefield phases cut by both active and relict palaeo creeks or washouts holocene sea level in the region rose to c 1 to 3 m above present reaching a maximum around 5100 years bp and then progressively fell to the present level we argue that the effect on barrier development was to suppress the development of a drainage system during the rising and maximum stages and encourage the development of an organized drainage system in the form of regularly spaced washouts during the falling period and that this change in sea level from rising to falling therefore produced the large scale differences in barrier morphology copyright 2006 john wiley sons ltd

late quaternary stratigraphic evolution of the inner continental shelf in response to sea level change santa catarina brazil abstract the inner continental shelf 0 50 m water depth off santa catarina southern brazil was investigated using seismic stratigraphic methods to identify and interpret the major seismic stratigraphic units and to reconstruct the late quaternary evolution of the inner shelf and coast the stratigraphy comprises a bedrock basement overlain by a thick 30 m unit that comprises in the distal portion laminated muds and sands and in the coast proximal zone offlapping deltaic deposits whose upper surface has been reworked to form alongshore prograding barrier spits deposition of this unit is tentatively attributed to sea levels 20 m msl during the late pleistocene mis 5a or 5c a normal fault in the muddy units with a vertical offset of 3 5 m indicates episodic tectonic activity cut into this unit is a profusion of incised valleys associated with sea level fall ultimately to 120 m at the last glacial maximum lgm the associated subaerial unconformity is only preserved close to shore where it has escaped subsequent wave ravinement this coupled with the well preserved incised valleys implies the underlying substrate to be weakly cohesive material mud the incised valleys display a variety of infilling sediments interpreted variously as basal fluvial sediments estuarine basin infill muds and marginal bar or barrier associated sands deposited during the postglacial marine transgression during a sea level stillstand at ca 50 m a 3 5 km wide planar surface was cut into the unconsolidated coastal plain sediments forming a terrace on which a thick sequence of sands accumulated this unit is regionally developed and the acoustic signature implies it to comprise littoral sand including a large aeolianite component the accumulation of sand on this mainland beach dune system is attributed to establishment of a mature littoral system with strong longshore drift the fact that it rests on an erosional surface that truncates incised valleys suggests the unit to be holocene in age it is interpreted to have been deposited during a still stand in the holocene and to have undergone aggradation and cementation until it was overstepped by sea level rise its surface and the coastal plain to landward were then subject to wave ravinement and a thin ca 5 6 m layer of modern marine sands was deposited on the eroded surface sea level rise continued to the regional glacio isostatic highstand of ca 5 5 m after which regressive strandplains developed in response to a renewed mature longshore drift system similar to that prevailing during the 50 m stillstand of sea level in the intervening period rapid shoreline translation over the low gradient surface inhibited the development of the longshore transport system the three shoreline systems identified show marked differences that relate to sea level change and the influence of the underlying topography shoreline 1 pleistocene highstand developed by localised wave reworking of delta deposits and involved a series of alongshore prograding barrier spits on a shoreline of alternating high relief bedrock and littoral sands in coastal re entrants shoreline 2 50 m was a major accumulation of beach and dune sand deposited as a mainland attached beach dune system on a low lying coastal plain environment shoreline 3 the modern coast comprises a series of headland embayment beaches strandplains and transgressive dunes with a strong bedrock control and a well developed longshore drift system delivering sediment northward

deglacial climate and relative sea level changes forced the shift from eolian sandsheets to dunefields in southern brazilian coast abstract quaternary sea level and climate changes can promote spatio temporal shifts in the morphology of coastal eolian depositional systems a shift of depositional features such as from sandsheets to dunefields occurs as response to a disequilibrium condition in the system promoted by changes in accumulation space and sediment supply balance on the other hand the eolian system migration with maintenance of morphological patterns points to an equilibrium conservation under minor variations in the external controlling factors of the system the santa catarina coast in southern brazil hosts widespread active and stabilized eolian depositional systems with varied morphology in this study geomorphologic and stratigraphic changes of eolian deposits of the southern coast of santa catarina were constrained by optically stimulated luminescence osl dating this allowed to assess how coastal eolian systems responded to late quaternary climate and sea level changes eolian sandsheets initiated around 22 ka ago during the last glacial maximum lgm and persisted during most of the deglacial period under conditions characterized by sea level lowstand wider exposition of shelf sediments more continental and drier climate and scarcer vegetation cover in the study setting the shift from eolian sandsheets to dunefields occurred approximately at 6 ka ago and marks the establishment of coastal conditions in the study setting the development of dunefields since the middle holocene would result from eolian system disequilibrium in response to a condition characterized by sea level highstand wetter climate and denser vegetation cover the maintenance of a dunefield morphology since 6 ka ago despite its onshore migration indicates a new equilibrium between accumulation space and sediment supply sandsheets evolved to dunefields around 6 ka ago when the coastline stabilized and the accumulation space was limited by onshore vegetation growth favoring eolian sediment aggradation the precipitation ridge in the inner margin of the dunefield has been successively stabilized abandoned and repositioned seaward accompanying the coastal progradation since 4 ka ago the decreasing migration rate of dunefields since 4 ka ago is attributed to rainfall reduction which deplete fluvial sediment supply to coastal systems and therefore slow down the coastal progradation rate

les variations du niveau de la mer durant les derniers 17 500 ans bp l exemple de la plate forme continentale du rio grande do sul bresil abstract the horizontal coastline translation on the rio grande do sul continental shelf during the post glacial wisconsinian period differed markedly between the northern region where it was about 8 6 m year and the southern region where the translation was 16 7 m year the northern region with a narrow continental shelf and a relatively strong pendant suffered a slow transgression characterized by a stronger hydrodynamic regime in the southern region the transgression was quite faster and combined with a lower energy regime caused by the presence of a wider continental shelf and a soft pendant the vertical coastline translation on the rio grande do sul continental shelf between 17 500 and 6500 yrs b p initiated from 130 m to the current sea level three intermediary stabilizations the first one at 11 000 yrs b p between 60 and 70 m the second one at 9000 yrs b p between 32 and 45 m and the third at 8000 yrs b p between 20 and 25 m on rio grande do sul continental shelf morphosedimentary marks confirm the sea level stabilizations they are characterized by an increasing of the shelf pendant associated to a biodetritical and coarse sand sedimentation at the profile trench as well as the presence of heavy mineral concentrations

eolian depositional episodes controlled by late quaternary relative sea level changes on the imbituba laguna coast southern brazil the late quaternary coastal eolian deposits of the imbituba laguna region santa catarina state southern brazil comprise two eolian depositional sequences separated by an unconformity the older eolian sequence a is correlated to the relative sea level rise of the last interglacial period the eolian sequence b was initiated during the relative sea level rise in the post glacial period and extends up to active dunefields the correspondence between the two eolian depositional episodes represented by these sequences and the relative sea level highstand phases is confirmed by thermoluminescence and optically stimulated luminescence dating this correspondence is explained by a conceptual model that links the availability of coastal sediments for eolian transport with relative sea level changes the link between relative sea level changes and coastal eolian sedimentation can be used to integrate coastal eolian systems to the sequence stratigraphy model

sea level sediment supply and coastal changes examples from the coast of ireland abstract sediment supply and pre existing shoreline morphology are crucial factors in controlling coastal changes due to sea level rise using examples from both southeast and northeast ireland it can be shown that sea level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium cliff erosion and longshore sediment movement in east co wexford has led to injection of sediment onto the shelf and the growth under both wave and tide regimes of linear offshore shoals these shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea level rise in contrast the nearby coast of south co wexford comprises a series of coarse clastic barriers moving monotonously onshore via overwash processes here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms finally the rock platform coast of co antrim presents a far more resistant shoreline to incident marine processes yet even here there is strong evidence of present process control over so called raised platforms and embayments it is concluded that coastal sediment supply and dynamics together with coastal morphology and its interaction with waves present a far more complex variety of sea level indicators than is normally acknowledged

shoreface translation and the holocene stratigraphic record examples from nova scotia the mississippi delta and eastern australia abstract classic descriptive models of barrier sedimentation have been developed with data from the atlantic and gulf coasts of the united states these models are dominated by low to moderate rates of relative sea level rsl rise and wave energy barriers respond by landward recycling of sediment through the mechanism of shoreface retreat sedimentation processes on the central coast of new south wales n s w australia consist of rapid rsl rise in early holocene times followed by a stillstand since 6500 b p wave energy is relatively high year round and sand sources for barrier formation are only found on the inner shelf barrier sedimentation on the central coast of n s w exhibits a thick composite sequence composed of a basal marine transgressive sand overlain by regressive beach and dune facies the louisiana coast surrounding the mississippi delta is underlain by compacting deltaic muds which generate very rapid rates of rsl rise the louisiana coast experiences low wave energy punctuated by high energy tropical and extra tropical storm events barrier sediments accumulate from the erosion of deltaic headlands and undergo a transformation from subaerial barrier island systems to subaqueous shoals located on the inner shelf drumlins experience coastal erosion on the eastern shore of nova scotia and provide a sediment source for compartmented estuary mouth barriers an ongoing moderate rise of rsl results from the passage of a glacial forebulge wave energy is intermediate between louisiana and n s w and displays a seasonal pattern dominated by frequent winter storms coastal barrier sedimentation is episodic consisting of a period of beach ridge progradation followed by barrier destruction and re establishment further landward the three contrasting sedimentary sequences found in examples from louisiana n s w and nova scotia indicate that presently available sedimentation models from locations such as the middle atlantic or texas coasts of the united states may only represent well documented regional case studies a true generalised coastal sedimentation model is required which can identify the parameters controlling vertical and horizontal translation of the depositional surface and provide relationships between these parameters which quantitatively predict the genesis distribution and geometry of coastal sedimentary facies

mineral and elemental indicators of post glacial changes in sediment delivery and deposition under a western boundary upwelling system cabo frio southeastern brazil abstract minerals and elements are important proxies that can provide information about variations in the delivery and deposition of coastal ocean sediments associated with past climate changes in this study postglacial changes in the accumulation of sediments on the upper shelf of southeastern brazil are linked to the evolution of regional paleoceanographic and continental paleoclimatic conditions during the last 14 4 kyr cal bp mineralogical and major and trace element analyses of a 14 c dated sediment core identify three main lithostratigraphic units of this core that reveal a succession of changes in sediment delivery and accumulation as postglacial sea level rose and holocene climate on land evolved the depositional setting has transitioned in response to the large sea level rise prior to 9 9 kyr cal bp from being a shallow water high energy environment to a deeper water one this location has since then been a lower energy environment that has persisted into modern times due to the high marine productivity associated with the cabo frio upwelling system in an oxygenated water column the sediments have shown a complex and dynamic redox condition making variations in redox sensitive trace elements indicative of changes in primary production and organic matter diagenesis at this location after sea level stabilized 9 kyr cal bp variations in fluxes of al fe ca and minerals were small indicating that climate driven changes had only secondary controls on delivery of detrital sediment components to the cabo frio shelf modern coastal upwelling conditions and the onset of mid shelf organic rich sediment deposition were established after 9 9 cal kyr bp

late holocene development of a mangrove ecosystem in southeastern brazil itanhaem state of sao paulo abstract most palynological studies of mangroves have been carried out in the indo pacific region but few have investigated these ecosystems along the southern atlantic coast this paper provides information on the palynology of a mangrove at itanhaem state of sao paulo on the southeastern brazilian coast this mangrove occurs on microtidal flats adjacent to a fluvial tidal channel mouth itanhaem river part of an estuarine lagoon system established in the mid holocene pollen samples were collected from the surface and from bromeliad water in order to define the composition of modern pollen rain in the study area the results show a strong presence of rain forest taxa in the mangrove pollen spectra which differ from those obtained from northern brazilian mangroves which are characterized by higher percentages of the mangrove taxa rhizophora and avicennia based on palynological and 14 c chronological analysis of a shallow core measuring 135 cm in depth the itanhaem mangrove already existed by 1300 years bp and began expanding about 1000 years bp reaching its present extent sometime after 300 years bp its evolution is related to the sedimentary filling of the estuarine lagoonal depositional system two factors may have controlled the development of this mangrove the relative increase of intertidal areas due to this sedimentary filling and the decrease in wave action and increase in pelitic deposition in the intertidal zone related to the partial closing of the estuarine lagoonal inlets these processes were favored by the advance of bayhead deltas and by the development of sand spits as a part of the regression of the holocene strandplain

application of multivariate statistical techniques in alongshore differentiation of coastal barriers abstract this paper investigates the existence of statistical correlations and relationships between geological and oceanographic parameters along a coastal barrier system in southern brazil the existence of few statistical studies on coastal barriers motivated the use of multivariate statistical techniques that take environmental parameters such as coastal morphological sedimentary features and their morphometric measurements into account the hierarchical cluster analysis hca and principal component analysis pca were used to assess the spatial variations of fourteen parameters driving the current and past behavior of this coastal barrier system at fourteen locations through the application of hca these locations were divided into four groups groups 1 2 3 and 4 the hca results were analyzed using pca the first pc1 and the second pc2 principal components together explained at least 76 4 of the variability of all four groups the most important geological and oceanographic parameters that were correlated to pc1 and pc2 were different in each group in general the shoreface slope and shoreface dimensions were common to all groups as pc1 correlated parameters being the most important ones regarding data variability in addition for the progradational groups 1 and 4 retrogradational group 2 and aggradational barriers group 3 pca indicated that shoreline orientation wave exposure and beach type are secondary but relevant factors controlling the past and current behavior of coastal barriers in southern brazil

holocene oscillations of southwest atlantic shelf circulation based on planktonic foraminifera from an upwelling system off cabo frio southeastern brazil the brazil current bc is a relevant feature in the atlantic meridional overturning circulation amoc its behavior during slowdown or intense amoc remains poorly known because of the lack of pal

paleoenvironmental insights into the quaternary evolution of the southern brazilian coast based on fossil and modern diatom assemblages abstract diatom assemblages provide a strong basis for detailed interpretations of paleoceanography and diatom paleoecology of the southern brazilian coast nine cores obtained in the coastal plain shelf and continental slope and thirteen surface sediment samples of the patos lagoon provide an excellent opportunity to use a paleoecological approach to study detailed quaternary environmental changes in the southern coasts in the interval studied the basin sedimentation occurred in a marine dominated environment related to humid periods prior to 43 500 year bp abundant diatom taxa are highlighted as excellent indicators of environmental changes including salinity sediment composition and transport by incised valleys providing additional insights into coastal evolution paralia sulcata is dominant in all analyzed cores occurring continuously from late pleistocene to holocene but is rare in the modern sediments non marine diatom assemblages occurred continuously but in very low densities in periods before and after the last glacial maximum abrupt changes in sedimentation have been recorded related to shifts from marine dominated to shallow estuarine deposition during the holocene sea level rose rapidly which is responsible for the progressive coastal flooding prior to 8420 7930 year bp the holocene barrier system became more continuous and patos lagoon developed consequently the secondary former inlets from the jacui and camaqua rivers are closed and only one single inlet rio grande channel remains active the spatial distribution of modern assemblages is controlled by salinity gradient wind action and climate forcing the bottom sediments of patos lagoon are dominated by freshwater diatom aulacoseira veraluciae aulacoseira sp 2 and marine estuarine species of cyclotella litoralis

nd and pb isotope signatures on the southeastern south american upper margin implications for sediment transport and source rocks abstract neodymium and lead isotope values in sediment samples were used to interpret sediment transport and source rocks on the southeastern south american upper margin the sediments of the argentinian margin exhibit an average nd value of 1 9 indicating the influence of the andean rocks as sediment sources sediments from the rio de la plata estuary show an average nd value of 9 6 which is similar to that of the southern brazilian upper margin finally sediments of southeastern brazil which are associated with the transport of the brazil current exhibit an average nd of 13 0 the pb isotope signatures also confirm the differentiation of source rocks in the sedimentation of the study area in addition pb isotopes helped to establish the extent of the influence of the rio de la plata on the sedimentation of the southern brazilian margin in terms of pb isotopes the sediments from the rio de la plata estuary and southern brazil are more radiogenic than those of southeastern brazil and the argentinian margin

origin of step like and lobate seafloor features along the continental shelf off rio de janeiro state santos basin brazil a combined analysis of seismic and morphological features identified in a set of high resolution seismic reflection and bathymetric data shows a systematic relationship between major modern seafloor morphological traces and the basinward migration of late pleistocene coastlines along the continental shelf of the santos basin rio de janeiro state se brazil observed fairly continuous and sinuous mid outer shelf escarpments are related to the sea level variations and shelf exposure during the last glacial cycle a bathymetric step at 110 m is an erosional remnant of offlapping detached forced regressive wedges that spread over 50 km in the shelf dip direction probably developed during periods of falling sea level between mis 3 and 2 a second major escarpment at 130 m was interpreted as the shoreline during the lgm at the time of most extensive subaerial exposure of the continental shelf however a distal escarpment at 150 m is expressed as a straight contour feature along the two main shelf edge embayments that characterize the shelf break this escarpment is coupled with a basal seaward inclined and highly eroded ramp and was interpreted as the erosional action of bottom currents during the last transgression due to the displacement of the southward flowing brazil current towards the present day outer shelf previously published articles have regarded the morphological features observed on the modern shelf as indicators of stillstands during the post lgm transgression we conclude that on the contrary most of these features are actually from earlier parts of the late pleistocene and were formed in a regressive scenario under oscillating and relative slow sea level fall

near surface circulation of the nordic seas as measured by lagrangian drifters in the period june 1991 to august 1993 107 argos tracked drifters drogued to 15 m depth were released in the nordic seas or greenland iceland and norwegian seas the drifter movements revealed the strong and spatially confined current systems along the surface salinity fronts of the iceland faroe frontal zone and of the norwegian coast and along the continental margins and their extensions to the barents sea and spitsbergen the norwegian atlantic current is composed of three distinct streams two continental margin and one coastal branches which join into one single swift mean current west of the lofoten and vesteralen islands where the strongest measured currents are in excess of 110 cm s 1 in addition to the general cyclonic gyre circulation in the nordic seas the drifters indicate smaller cyclonic circulation patterns in all the major subbasins i e the iceland plateau the norwegian the lofoten and the greenland basins no surface signature of the east icelandic current is disclosed by the drifters interpolated and low pass filtered position data were used to construct maps of 15 m depth ensemble mean velocity velocity variability and residence time vigorous eddy fields are dominant in the strong currents and in the lofoten basin eulerian correlations indicate that they tend to propagate to the west in contrast the iceland plateau appears quiescent both in the mean and eddy velocities single particle diffusivities are computed and are found to be in the range 1 7 107 cm2 s 1 the corresponding lagrangian timescale and space scale are 1 3 days and 10 40 km respectively these lagrangian drifter measurements compose the first basin scale accurate near surface velocity data set of the nordic seas

tidal strait to embayment seismic stratigraphy and evolution of a rock bounded embayment in the context of holocene sea level change abstract elongate rock framed santa catarina island partly encloses a low energy marine embayment that communicates with the ocean via narrow rock bounded inlets with ebb and flood tide deltas the bay shoreline consists of low energy sandy beaches strandplains mangroves and bayhead deltas while the exposed atlantic shoreline comprises a series of headland embayment littoral cells in a linked north directed longshore drift system new and previously published seismic stratigraphic investigations enable assessment of the palaeogeographic geomorphic evolution of the area since the early holocene at a sea level of ca 50 m a sandy mainland attached shoreline complex dune and beach developed on a coastal plain setting some 6 7 km offshore of the present shoreline north of the island a barrier island and tombolo were formed in a coastal re entrant adjacent to the northern entrance to florianopolis bay the open coast beach dune system was overstepped by rapid sea level rise during mwp 1b whereas the barrier island and tombolo continued to accrete until mwp 1c when they too were overstepped the back island embayment contains up to 40 m of sediment overlying an irregular bedrock surface it was initially flooded during mwp 1c and the early muddy sedimentation suggests a distal sheltered marine embayment the subsequent development of many large bioherms on bedrock and mud suggests a change to more fully marine conditions as sea level continued to rise in the north bay these were subsequently enveloped by tidal dunes migrating north from the mid bay the vertical stacking of 3 d and 2 d sandy bedforms suggests that a tidal strait had developed with strong tidal currents radiating from a constriction in the vicinity of modern florianopolis city the strong tidal currents may be linked to the holocene sea level high that is well documented for this region a fall in sea level from this highstand coupled with accumulation of tidal strait sediments reduced the tidal prism and strength of tidal currents in the bay at the same time regressive beachridge plains developed in open coast and bay environments this coincided with development of the contemporary tidal inlet complexes at the north and south outlets of the bay as a consequence the upper surface of the tidal strait sand deposits experienced tidal ravinement and the bay switched to a sheltered back barrier environment dominated by deposition of mud and silt which blanket the contemporary bay floor the tidal inlets sequestered sand from the littoral drift system in ebb and flood tide deltas which created breaks in the longshore drift system causing littoral sediment to accumulate at the north of the island in a series of spits and promoting strandplain development south of the island

barrier evolution and placer formation at bujuru southern brazil abstract this paper demonstrates the link between the evolution of a coastal barrier in southern brazil during the late holocene and the formation of a large volume of eolian disseminated heavy mineral deposits our data set is based on an earlier heavy mineral prospecting campaign 1991 and on 10 new shallow vibrocores 2 5 m long the model presented has three main steps of barrier evolution the first step is the recycling of coastal plain deposits during the postglacial marine transgression which ended at 5 6 ka when heavy minerals were incorporated into beach and washover facies of a transgressive barrier the second step is the shoreward retreat of the barrier under a slow and small sea level fall during the last 5 6 ka this second step eroded and recycled sediments from the pleistocene substrate which acted as an extra source of heavy minerals heavy minerals were concentrated in backshore deposits by wave action during barrier recession the third step is the erosion and transport of backshore sands by onshore winds into an inter barrier depression in the form of transgressive dune deposits these deposits contain an average of 4 66 1 02 disseminated heavy minerals 1494 samples this eolian placer deposit has started to form 1 ka ago and is still under formation

high resolution stratigraphy of holocene lagoon terraces of southern brazil abstract the northern portion of the coastal plain of the rio grande do sul state southernmost brazil comprises an outer sandy barrier that protects a complex lagoon system formed during the holocene the terraces of three different lagoons gentil malvas and pinguela formed along their margins record the depositional processes and the relative base level changes over the past 5000 yr therefore our main objective was to characterize and quantify base level fluctuations from the study of these terraces to correlate them to sea level changes and to describe the depositional architecture related to the distinct sea level stages high resolution sequence stratigraphy satellite images topographic and gpr profiles auger holes and radiometric dating were used the main results indicate a close relationship between relative base level and relative sea level changes a stillstand period just after the last transgressive maximum 4840 4650 cal yr bp and a subsequent overall relative sea level fall of about 3 m both a normal highstand systems tract and a forced regression falling stage systems tract controlled the geological record preserved in the terraces the highstand older terrace is characterized by agradational bedding whereas the falling stage comprises three progradational sets terraces bounded by erosive surfaces related to smaller scale sea level drops

north atlantic ocean surface currents 1 close to 1800 surface drifters are used to investigate the 15 m circulation of the north atlantic ocean the data are used to describe structures of the average eulerian circulation and of the associated eddy variability the data resolve scales on the order of 50 km which have hitherto not been systematically described in particular near shelf breaks and near the most intense currents the gulf stream the north atlantic current nac and the frontal currents of the subpolar gyre this reveals a complex series of quasi permanent eddies meanders and recirculation patterns gulf stream intensity is portrayed as changing abruptly near 54 w east of which it is identified as two current branches centered near 39 and 41 5 n the northern one connecting more directly with the nac and the southern one with the recirculation gyre and the azores current ac many features of the currents are controlled by topography in particular currents are often intensified near shelf breaks or parallel to ridges in the subpolar gyre however the largest northward branch of the nac in the icelandic basin is located near the deepest bathymetry not near steep bathymetry other currents in particular in the subtropical gyre are less clearly related to topography for instance the ac is featured as a zonal eastward current extending far west of the mid atlantic ridge mar to at least 55 w and possibly 63 w in the interior and away from topographic features the eddy kinetic energy eke is the largest where the mean currents are the largest in the subpolar gyre there are striking differences in eke between southward flowing currents the labrador and east greenland current and the northward flowing currents west greenland current and branches of the nac which have higher eke the areas of weakest variability are located in the southwest part of the subpolar gyre northeast of iceland and in the eastern atlantic south of 45 n the ac eddies and the mesoscales south of the canary islands transect this eastern eddy desert drifter trajectories are used as realizations of lagrangian particles in the vicinity of current cores these illustrate the variety of paths or connections between different current systems and demonstrate cross stream dispersions

vegetation dynamics during the last 7500 years on the extreme southern brazilian coastal plain abstract for the first time in the extreme southern brazilian coastal plain we analyzed palynomorphs in a continuous sequence using an outcrop profile of relict muds in hermenegildo beach 33 42 12 s 53 18 57 w santa vitoria do palmar rio grande do sul state five radiocarbon dates were obtained the results revealed the plant succession in an ancient water reservoir near the coastal line 7500 4000 bp marine organisms and freshwater taxa with herbaceous marsh at the margins marine taxa were markedly present from 6000 to 5000 bp the time of the maximum transgression regionally the vegetation was dominated by grasslands and forest groupings 4000 2000 bp regressive marine phase with an increased record of freshwater organisms due to increased rainfall a large increase in herbaceous marsh components resulted in a gradual filling in of the water reservoir and the development of regional vegetation 2000 1760 bp with the end of the marine regression progressive desalinization promoted the local herbaceous marsh development regionally grassland and forest also developed indicative of climate amelioration local plant succession ceased during this phase of herbaceous marsh ca 1760 bp when beach sands covered the sedimentary sequence this study reveals the phases of a hydrosere in a coastal water reservoir influenced by marine oscillations with gradual desalinization and filling in that culminated in an herbaceous marsh deposit these results provide a basis for understanding many other similar relict muds spread throughout the coastal plain in the extreme south of brazil

evidence for late quaternary episodic uplift of the sao pedro and sao paulo archipelago equatorial atlantic abstract the sao paulo and sao pedro archipelago spa forms an emergent part of the sao paulo transform fault zone in the equatorial atlantic in the present study the uplift rate of this part of the transform in the late quaternary was investigated in order to determine its origin uplift rates were determined by dating sedimentary and biological paleo sea level indicators the findings are a paleo sea level indicators yielded ages corresponding to the late pleistocene and mid to late holocene b ages between 43 6 and 18 9 ka correspond to paleo sea levels between 8 2 and 12 1 m above present sea level suggesting a maximum uplift rate of 3 3 2 9 and a minimum uplift rate of 0 8 1 2 mm y c the observation of a pleistocene megabalanus in the spa provides a new piece of information for understanding the evolution and biogeography of the genus d the ages of the holocene sea level indicators range between 6 2 ka and near present 13 3 m which are higher values than for mid to late holocene eustatic sea level suggesting strong uplift for that period and e different rates of lowering of sea level for the last 6 2 ka f ages and paleo sea level also suggest that almost instantaneous uplifts of 3 and 2 m could have occurred at approximately 2 5 and 0 2 ka g the rates of change in sea level indicate a clear pattern of episodic uplift which is typical of related coseismic movements in a stick slip mode h this scenario implies that the area could be affected by medium to large earthquakes mb 5 4 where a vertical displacement of 2 3 m could occur

reviewing sedimentological and hydrodynamic data of large shallow coastal lagoons for defining mud depocenters as environmental monitoring sites abstract we reviewed historical data on surface sediment composition distribution and hydrodynamics of the patos mirim lagoonal system the largest coastal shallow limnological system of the world located in eastern south america which is ca 15 000 km2 the maximum length is almost 500 km and maximum depth is around 7 m we inferred the geographical position of six mud depocenters in relation to the hydrodynamic conditions evolved from predominant winds and morphometry littoral zones of sediment resuspension dominated by sand were identified where current velocity was higher than 0 2 m s 1 and depth was 5 m such conditions observed for the central zones represent appropriate morphodynamic controls for mud depocenter formation the six permanent holocene depocenters for the whole patos mirim system were all dominated mostly by silty clayey facies and exhibited an mz value equal to or higher than 7 5 because of the dominance of the fine fraction we propose them as future potential key spots for monitoring the environmental quality of the system to assist regional sustainable management

barrier island evolution middle atlantic shelf u s a part ii evidence from the shelf floor where the atlantic coastal gradient is low and the substrate is unconsolidated shoreface processes lead to an equilibrium shoreface surface characterized by a straightened plan view and a concave up profile maintenance of this surface during the post glacial sea level rise may lead to barrier formation by mainland beach detachment where the outer oceanic shoreface is maintained by wave and current processes downwelling storm currents sweep sand from the shoreface of the middle atlantic bight transport it downcoast and seaward and deposit it on the adjacent inner shelf some of this sand is returned by the action of asymmetrical wave orbital currents during fair weather however there is a net loss in most areas the loss is not made good by river sand input since on the atlantic coast all river sand is trapped by estuaries as a result the shoreface in these areas is undergoing erosional retreat mean horizontal retreat rates are on the order of 1 3 m yr 1 but most movement occurs in brief episodes with recurrence rates on the order of several events per century erosional shoreface retreat coupled with aeolian overshoot storm washover and the movement of sand through inlets into the lagoons has lead to landward migration of the atlantic barriers through the holocene period of sea level rise the landward retreat of the barrier as a whole is as dependent on inlet formation as it is on erosional shoreface retreat repeated inlet breaching and the downdrift migration of inlets yields coalescing flood tidal deltas within the lagoon the resulting surface forms a platform on which the subaerial barrier deposits can advance under the impetus of storm washover and aeolian action the backbarrier deposits eventually re emerge at the shoreface where their upper beds are eroded and recycled the barrier thus migrates over a pavement of its own flood tidal deltas and washover fans sand is added to the system partly through the erosion of updrift headlands but mainly by means of scour in inlets which reaches down to the underlying pleistocene the modern shelf sand sheet is the debris blanket resulting from the retreat process the leading edge occurs as a thin veneer of rip current fallout on the shoreface this is periodically stripped off by winter storms to expose the underlying backbarrier strata further seaward shelf sands eroded from the shoreface rest disconformably on backbarrier deposits shoreface beach and dune strata are always missing every grain of sand in this shelf sand sheet has occupied a position on the beach or upper shoreface within the recent past however the sheet as a whole has been reconstituted its primary structures are those of the inner shelf floor backbarrier sand and mud deposits characterized by channeling and landward dipping reflectors can be traced for over 100 km seaward across the middle atlantic shelf beneath the modern sand sheet the backbarrier stratum together with the overlying shelf sand layer constitutes the record of barrier retreat across the atlantic shelf surface during holocene time the sheet like nature of this record indicates that viewed at the appropriate time scale barrier migration is a continuous process

astrochronology for the early cretaceous jehol biota in northeastern china article i nfo the early cretaceous jehol biota in northeastern china provides an evolutionary window for feathered dinosaurs primitive birds insects and early flowering plants it also provides critical information for the bio diversity changes of the early cretaceous terrestrial ecosystem here we report a time series analysis for the 11 2 m thick fossil bearing lacustrine deposits at the sihetun section in western liaoning northeastern china on the basis of high resolution magnetic susceptibility ms and anhysteretic remanent magnetization arm measurements a hierarchy of sedimentary cycle bands of 120 260 cm 50 67 cm and 18 42 cm was recorded in the ms and arm series with available radioisotope age constraints from the same section sedimentary cycles of 120 260 cm 50 67 cm and 18 42 cm were interpreted as milankovitch cycles of short eccentricity 130 and 95 kyr obliquity 36 6 and 46 kyr and precession 22 1 20 9 and 18 kyr respectively the 100 kyr tuned floating astronomical time scale indicates that the duration of the 11 2 m thick section is 0 67 myr and the average depositional rate is 1 70 cm kyr the duration of the 1 8 m thick main fossil bearing interval that contains 8 beds of feathered dinosaur primitive bird fossils can be estimated as short as 150 kyr the results suggest that climate fluctuations manifested in paleobotanical sedimentological and geo chemical records of the yixian formation may have been controlled by orbital forcing during early cretaceous 2013 elsevier b v all rights reserved

late holocene palaeotemperatures and palaeoenvironments in the southeastern brazilian coast inferred from otolith geochemistry abstract holocene palaeoceanography and climatic reconstructions were evaluated based on proxy analyses of fish otoliths from shellmounds located along the coast of rio de janeiro state brazil modern coastal seasonal upwelling is associated with the ascension of a deep and cold water mass as a consequence of persistent ne winds that affect the climate in southeastern brazil however this seasonal influence and the effect of the holocene palaeoenvironment on shallow water are poorly known in this work coastal palaeotemperatures were estimated based on the geochemical analyses of otolith the results of the 18o and 13c analyses from holocene otoliths obtained from coastal shellmounds separated by a distance of almost 200 km show two distinctive otolith derived palaeotemperature signals in a coastal region under upwelling influence additionally this analysis suggests that the fish lived in marine waters showing similar microchemistry values composition when compared with modern marine otoliths

links between surface sediment composition morphometry and hydrodynamics in a large shallow coastal lagoon abstract this study addresses the surface sediment composition and distribution in mirim lagoon a large coastal shallow transboundary system located on the border of south brazil and uruguay which is 3749 km2 and maximum depth is around 6 m in relation to the hydrodynamic conditions evolved from predominant winds surface water currents in the marginal area displayed maximum speed values of 0 25 to 0 3 m s 1 flowing parallel to the coastline either under ne of sw wind predominance the marginal zone above the 6 m bathymetric contour comprise sandy sediments indicating that under such a combination of bathymetric and hydrodynamic conditions the resuspension of fine sediments is dominant lower surface current velocity observed in the central zone of the lagoon located below the 6 m isobath i e 0 05 m s 1 together with an increase in the maximum width of the lagoon promoted conditions for deposition of the clay sediment fraction therefore the combined use of sedimentological and hydrodynamic data represents a useful tool to infer patterns of deposition and resuspension in coastal systems given the large size of the mirim lagoon and associated difficulties in sampling and monitoring the system the information presented here is important for environmental management and particularly for planning future paleolimnological research and set the coring stations on appropriate coordinates within the central region where relatively calm conditions and dominance of clay sediments are observed

the development of blowouts and foredunes in the ilha comprida barrier southeastern brazil the influence of late holocene climate changes on coastal sedimentation abstract middle to late holocene barriers are conspicuous landforms in southeastern and southern brazilian regions the barriers in the coastal zones of northern santa catarina parana and sao paulo states 27 19 24 00 s are formed mainly by beach ridge alignments and many barriers present foredune and blowout alignments in their seaward portion the development of these eolian landforms appears to record a regional shift in coastal dynamics and barrier building in this context the ilha comprida barrier stands out for its well developed and well preserved foredunes and blowouts based on the presence or not and type of eolian landforms the ilha comprida barrier can be divided seaward into inner middle and outer units the inner unit is formed entirely by beach ridges the middle unit comprises a narrow belt of blowouts up to 15 m high aligned alongshore blowout lobes pointing nnw are indicative of their generation by southern winds the outer unit is represented by low 1 m high active or stabilized foredunes and a small transgressive dunefield 1 km 2 twenty seven luminescence ages sar protocol obtained for the beach ridges foredunes and blowouts of these three units allow definition of a precise chronology of these landforms and calculation of rates of coastal progradation the inner unit presents ages greater than 1004 88 years the blowouts of the middle unit show ages from 575 47 to 172 18 years the ages of the outer unit are less than 108 10 years rates of coastal progradation for the inner and outer units are 0 71 0 82 m year and 0 86 2 23 m year respectively the main phase of blowout development correlates well with the little ice age lia climatic event these results indicate that southern winds in subtropical brazil became increasingly more intense and or frequent during the lia these conditions persist to the present and are responsible for the development of the eolian landforms in the outer unit thus barrier geomorphology can record global climatic events the sensitivity of barrier systems in subtropical brazil to late holocene climate changes was favored by the relative sea level stillstand during this time luminescence dating makes it possible to analyze barrier geomorphology during late holocene climate changes operating on timescales of a hundred to thousand years these results improve our knowledge of barrier building and will help in the evaluation of the impact of future climate changes on coastal settings

paleoenvironmental reconstruction of a late quaternary lagoon system in southern brazil jaguaruna region santa catarina state based on multi proxy analysis this paper provides a paleoenvironmental reconstruction of a late quaternary lagoon system in the jaguaruna region of santa catarina state southern brazil integrated results of bulk sedimentary organic matter characterization d 13 c d 15 n and c n microfossil pollen and diatom and grain size analysis from three shallow cores 2 5 m depth allowed us to propose an evolving paleogeographic scenario in this coastal region for the last ca 5500 cal a bp the lagoonal system in this area was more extensive during the mid holocene than today with a gradual and continuous lagoon sea disconnection until the present we add to the debate regarding relative sea level rsl variations for the brazilian coast during the holocene and discuss the importance of sedimentary dynamics for interpreting changes in coastal ecosystems the multi proxy analysis suggests that changes in coastal ecosystems could be directly related to local sedimentary processes which are not necessarily linked to rsl fluctuations and or to climatic variations copyright 2011 john wiley sons ltd

planktonic foraminifera in the sediment of a western boundary upwelling system off cabo frio brazil abstract the distribution of planktonic foraminifera in box core tops under the influence of a western boundary upwelling system along the southeastern brazilian continental margin was examined to evaluate the similarity percentage simper and to create a biofacies model for paleoenvironmental applications species associated with warm and oligotrophic water were distributed in the rio de janeiro sector of the campos basin while productive water species were most abundant in the rio de janeiro sector of the santos basin and cold water species were most abundant in the cabo frio upwelling system cfus four major biofacies are associated with the oceanographic setting of the cfus one from the campos basin a brazil current front one from the santos basin b mixture of coastal and oceanic waters and two associated with the cabo frio high in the northern biofacies c and southern biofacies d the distribution of biofacies c and d was associated with temperature differences biofacies c represents a mixture of upwelling and tropical waters while biofacies d represents a mixture of cold nutrient rich and santos basin waters these biofacies were also defined in core cf10 01b in which six main paleoceanographic phases were characterized during the last 9 cal kyr predominantly showing alternating dominance between biofacies c and d from 9 0 to 5 0 cal kyr before the present bp the system was dominated by biofacies c between 4 0 and 3 5 cal kyr bp biofacies d was dominant between 3 5 and 2 5 cal kyr bp a strong influence of coastal waters and weakened upwelling activity were indicated by the dominance of biofacies b c d the last 2 5 cal kyr was dominated by biofacies d the sst in this core was reconstructed using the modern analog technique mat which revealed 0 35 c of variability indicating no sst changes during the holocene the weak sensitivity of the mat was due to the interplay among different oceanographic features

late pleistocene to holocene palaeoclimates and palaeoenvironments inferred from palynofacies and dinoflagellates cysts in santos basin offshore brazil abstract we analyse late pleistocene to holocene palynofacies and dinoflagellates in a sedimentary core pc prima 4 collected on the northern offshore shelf of the santos basin of brazil which covers the last 29 429 cal yrs bp the aim of this study is to better understand changes in climate and oceanographic circulation that affected this region since the last glacial maximum lgm and the 120 m rise in sea level that followed the organic matter in the core shows characteristics consistent with an oxygenized proximal shelf with incursions of continental elements which evolved into a more distal dysaerobic anoxic environment over the studied time interval an increase in phytoclast opaque and non opaque abundance during the last glacial maximum interval suggests enhanced river supply driven by the increase in the hydrological cycle resulting from cold and humid climatic conditions the increase of amorphous organic matter from 16 437 cal yrs bp suggests the onset of anoxic bottomwater conditions that resulted of an increase in water depth together with the percentage increase of operculodinium centrocarpum and the fall in tuberculodinium vancampoae abundance this implies the postglacial development of warmer currents in summary our results better document the climatic and oceanographic changes that occurred in this area during and following the lgm

paleoproductivity changes during the holocene in the inner shelf of cabo frio southeastern brazilian continental margin benthic foraminifera and sedimentological proxies abstract sedimentological and benthic foraminifera analyses carried out on a core length 4 15 m collected at 22 56 31 s and 41 58 48 w at a water depth of 43 m sampled from the inner shelf of cabo frio southeastern brazilian continental margin allowed identification of different hydrodynamic and productivity regimes related to sea level fluctuations and or climatic changes during the last 9 4 ka cal bp prior to 7 0 ka cal bp a less intense hydrodynamic and lower productivity regime occurred at lower sea levels and under drier climatic conditions between 7 0 and 5 0 ka cal bp relatively stronger local oceanic circulation and relatively high productivity were observed in a scenario of rising sea levels and more humid conditions from 5 0 to 3 0 ka cal bp bottom currents weakened and input of nutrients increased with productivity levels similar to the previous phase at lower sea level and in a drier climate from 3 0 ka cal bp up to the present stronger hydrodynamic conditions and a higher productivity regime are linked to the establishment of the upwelling process in cabo frio from 2 5 ka cal bp to the present upwelling enhancement has been recognized resulting from the combined action of ne winds and the intensification of the meandering pattern of the brazil current bc

late quaternary vegetation and coastal environmental changes at ilha do cardoso mangrove southeastern brazil abstract a 190 cm mangrove sediment core from the ilha do cardoso state park state of sao paulo southeastern brazil was analyzed for pollen diatoms as well as carbon and nitrogen isotopes the goal was to determine the dynamics of the coastal terrestrial aquatic ecosystems vegetation history and climate change in this region of the brazilian atlantic rainforest during the late pleistocene and holocene the values for total organic carbon toc from 3 up to 40 c n ratios from 10 up to 130 and 15n 0 to 8 are associated with well preserved aquatic and terrestrial organic matter and possibly influenced by nitrogen cycling e g denitrification that caused 15n enrichment between 40 000 cal yr b p and 23 000 cal yr b p depleted 13c values 28 0 are also observed and indicate the predominance of c3 plants during this time interval the pollen analysis reveals the presence of the genera ilex alchornea weinmannia myrsine symplocos drimys and podocarpus on a site currently occupied by mangrove vegetation these data suggest that in the past prevailed a colder and more humid climate than today with a low relative sea level from 23 000 cal yr b p to 2200 cal yr b p a sedimentary hiatus likely occurred related to an erosive event associated to the post glacial sea level rise since at least 2200 cal yr b p sediments are marked by relatively low c n ratios from 2 to 27 exhibit more enriched 13c from 26 0 to 24 0 and 15n up to 7 values and are characterized by the presence of marine diatoms this indicates the return of the marine coastal line to its current position and consequently the development of mangrove

underwater mapping of late quaternary submerged shorelines in the western mediterranean sea and the caribbean sea abstract underwater mapping of sea floor profiles using the self contained underwater breathing apparatus was carried out along the rocky coasts of provence in southern france west corsica and the isle of elba in italy an analysis of 150 underwater profiles in these regions has provided a sequence of sub aerial erosion notches at common depths of 11 17 25 35 45 55 and 100 m because notches at similar depths have also been found in the french west indies these notches are suggested to have been formed by the same lower eustatic sea levels during the late quaternary the occurrence of submerged sub aerial erosion notches may indicate uplift and or subsidence in tectonically active coasts