sea level fall and coastal water cooling during the late holocene in southeastern brazil based on vermetid bioconstructions abstract the relative sea level variation curve obtained by dating and leveling vermetid shells from northern santa catarina state 26 3 s presents fall trend during all the last 4 0 cal ka bp which matches previous results based on the same kind of indicator for the brazilian coast between 3 s and 28 s chemical and isotopic analyses of 50 vermetid bioconstructions from distinct localities of south southeastern brazilian coast indicate possible changes in the coastal water temperature these changes may have been caused by oscillations in the strength of brazilian coastal current which carries la plata plume northward being therefore responsible for the penetration of cold and less saline water masses in the study area this is a reasonable explanation for the scarcity of vermetid biolithites around 3 4 2 6 cal ka bp and 0 5 0 cal ka bp

enhanced southward flow over the oregon shelf in 2002 a conduit for subarctic water 1 moored current measurements from the oregon shelf during 1998 2003 are used to estimate time series of anomalous alongshore currents and pseudo displacements after accounting for the mean and seasonal cycle from early january through mid june 2002 currents at 10 m were anomalously strong toward the south by an average 12 cm s producing an anomalous displacement of more than 1500 km over about 5 months this may be compared with the finding by freeland et al 2003 that waters at the same latitude off oregon and off vancouver island were anomalously cool and fresh at depths between 30 and 150 m suggesting displacement from a more northern source anomalous displacements of several hundred kilometers were also found during at least three other periods in the record moored temperature measurements at the same location confirm that local waters were persistently cooler during march to october of 2002 than during the previous two years with the strongest anomaly near 20 m coastal sea levels were lower than usual along the northwest coast during spring and early summer 2003 consistent with a southward current anomaly of large scale local winds near newport did not show strong mean anomalies during this period

palynofacies and stable c and n isotopes of holocene sediments from lake macuco linhares espirito santo southeastern brazil depositional settings and palaeoenvironmental evolution particulate organic matter in sediments constitutes a valuable proxy for paleoenvironmental reconstructions a 192 cm lacustrine sediment core 7521 cal yr b p from the northern coast of the state of espirito santo southeastern brazil was radiocarbon dated and then analyzed for palynofacies stable isotopes c and n and grain size the values for total organic carbon toc 1 91 to 20 89 total nitrogen tn 0 08 to 1 1 13c 27 10 to 29 01 15n 1 92 to 5 09 and c n 12 87 to 50 11 suggest predominance of c3 plants and changing mixtures of terrestrial and aquatic organic matter in the sediments palynofacies and cluster analyses were used to identify four palynofacies associations that reflect different phases in the lake macuco evolution palynofacies 1 192 to 106 cm 7521 cal yr b p to 7054 cal yr b p interpolated age is characterized mainly by amorphous organic matter aom non opaque phytoclasts nops mangrove pollen grains rhizophora sp l 1753 and avicennia sp l 1753 and foraminiferal test linings palynofacies 2 106 to 65 cm 7054 cal yr b p interpolated age to 4847 cal yr b p is dominated by nops and aom with an increase in the values of mangrove pollen grains relative to palynofacies 1 both palynofacies reflect marine and fluvial influences in a depositional environment related to the development of an estuarine system during the mid holocene transgressive stage palynofacies 3 65 to 27 cm 4847 cal yr b p to 3800 cal yr b p interpolated age comprises high abundances of fluvial elements nop and opaque phytoclasts op and low values of aom the depositional environment is interpreted as being an estuary during the marine regression with the displacement of the estuarine basin and mangroves towards the sea palynofacies 4 27 to 0 cm 3800 cal yr b p is characterized by the predominance of aom and nop increase in the values of freshwater algae and no evidence of marine influence this last phase reflects the beginning of the establishment of lake macuco and floodplain of the barra seca river under conditions similar to the present day

the coastal ridge sequence at rio grande do sul a new geoarchive for past climate events of the atlantic coast of southern brazil since the mid holocene abstract we present here the first geochronometric analysis of a large succession of coastal ridges that developed south of rio grande do sul inlet aided by osl dating of samples taken in this succession that amounts c 306 coastal ridges this succession allows defining epochs of enhanced coastal drift or fluvial transport to the river mouth additionally changes in the preservation of ridges also suggest the additional effect of transverse winds that create blow outs while changes in the ridge packages planview onlap suggest possible changes in the dominant longshore drift four osl samples located strategically allow defining the age of five main stages of this succession the first stage comprises 2 substages the first substage shows ridges 1 to 36 onlapping the boundary coastal scarp northwardly while the second ridges 37 to 84 shows an inversion of ridge shape wedging out southwards until coast returns to be quasi parallel to the initial coastal scarp estimated to be c 6 ka we estimate this first stage to comprise enhanced coastal drift due to higher and sandier ridges ending at c 4 1 ka the second stage ridges 85 to 124 ridges is marked by a slight unconformity and indicates a period of enhanced fluvial progradation and less coastal drift suggesting milder winds up to 3 6 ka the third stage ridges 125 to 204 initiates with erosion of ridges near the delta front being higher and sandier ridges suggesting enhanced coastal drift due to windier conditions being the windiest time bracketed between 3 3 and 2 35 ka the fourth stage ridges 205 to c 270 shows again as second stage a tendency of wedging out southwards suggesting enhanced fluvial progradation estimated between 2 34 and 1 7 ka the fifth stage is defined by a complete change of coastal plain progradation due to the rapid recycling of beach ridges into a complex of blow outs and arcuate sand dunes ridges are sparsely recognized in cases they developed during short lived events of enhanced longshore drift with an outstanding group ridges 288 to 290 that we correlate to a 1 1 0 9 ka cooling event future studies improving the chronostratigraphy of the beach ridges succession at rio grande and comparing it with the parana river delta ridges will help understanding the complex environmental history of south america that include a reversal of the longshore drift given the fact they are among the most complete upper holocene geoarchives available

evidence for a transgressive barrier within a regressive strandplain system implications for complex coastal response to environmental change clastic depositional strandplain systems have the potential to record changes in the primary drivers of coastal evolution climate sea level and the frequency of major meteorological and oceanographic events this study seeks to use one such record from a southern brazilian strandplain to highlight the potentially complex nature of coastal sedimentological response to small changes in these drivers following a 2 to 4 m highstand at ca 5 8 ka in southern brazil falling sea level reworked shelf sediment onshore forcing coastal progradation smoothing the irregular coastline and forming the 5 km wide pinheira strandplain composed of ca 500 successive beach and dune ridges sediment cores grab samples and 11 km of ground penetrating radar profiles reveal that the strandplain sequence is composed of well sorted fine to very fine quartz sand since the mid holocene highstand the shoreline prograded at a rate of ca 1 to 2 m yr 1 through the deposition of a 4 to 6 m thick shoreface unit a 1 to 3 m thick foreshore unit containing ubiquitous ridge and runnel facies and an uppermost beach and foredune unit however the discovery of a linear 100 m wide barrier ridge with associated washover units a 3 to 4 m deep lagoon and 250 m wide tidal inlet within the strandplain sequence reveals a period of shoreline transgression at 3 3 to 2 8 ka during the otherwise regressive developmental history of the plain the protected nature of pinheira largely buffered it from changes in precipitation patterns wave energy and fluvial sediment supply during the time of its formation however multiple lines of evidence indicate that a change in the rate of relative sea level fall probably due to either steric or ice volume effects may have affected this coastline thus whereas these other potential drivers cannot be fully discounted this study provides insights into the complexity of decadal scale to millennial scale coastal response to likely variability in sea level change rates

radarfacies and sedimentological analysis study of sedimentary substrate from an archaeological site shell mound southern brazil integrated results of gpr ground penetrating radar and sedimentological analysis are presented for the jabuticabeira ii archaeological site shell mound santa catarina brazil by means of rada

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

geochemical evidence of the 8 2 ka event and other holocene environmental changes recorded in paleolagoon sediments southeastern brazil abstract the paleoclimatic record of jureia paleolagoon coastal southeastern brazil includes cyclic and gradual changes with different intensities and frequencies through geological time and it is controlled by astronomical geophysical and geological phenomena these variations are not due to one single cause but they result from the interaction of several factors which act at different temporal and spatial scales here we describe paleoenvironmental evidence regarding climatic and sea level changes from the last 9400 cal yr bp at the jureia paleolagoon one of the main groups of protected south atlantic ecosystems geochemical evidences were used to identify anomalies from multi proxy analyses of a paleolagoon sediment core the anomalies of centennial scale were correlated to climate and transgression regression cycles from the holocene period decadal scale anomalous oscillations in the quaternary paleolagoon sediments occur between 9400 and 7500 cal yr bp correlated with long and short term natural events which generated high sedimentation rates mainly between 8385 and 8375 cal yr bp 10 cm yr our results suggest that a modern day short duration north atlantic climatic event such as the 8 2 ka event could affect the environmental equilibrium in south america and intensify the south american summer monsoon

large scale atmosphere ocean anomalies in the northeast pacific during 2002 1 in summer fall 2002 the coastal northeast pacific nep was characterized by anomalously cool fresh waters extending from vancouver island to southern california increased equatorward transport in the california current system ccs and higher surface productivity in the northern ccs the evolution of large scale atmosphere ocean anomalies in the nep from winter 2001 02 through fall 2002 contributed to these coastal anomalies by setting up wind stress anomalies that led to 1 anomalous transport of subarctic waters into the north pacific current npc 2 enhanced eastward flow in the npc 3 anomalously strong upwelling in the ccs and 4 enhanced equatorward transport in the ccs

anomalous southward advection during 2002 in the northern california current evidence from lagrangian surface drifters 1 equatorward velocities in the upwelling jet of the northern california current were 0 05 0 06 m s 1 faster in spring and summer 2002 than on average over 1998 2002 this result is based on a five year data set of surface drifters released across the continental margin off central oregon 44 65 n during april and july of each year at this speed anomalous water displacements of over a degree of latitude can occur in 20 25 days given a source of cold subarctic water to the north this anomalous southward displacement is a plausible explanation for the cold nutrient rich halocline water observed off oregon during the summer of 2002 this interannual variability in the northern california current and its implications for the ecosystem response i e increased primary productivity may be contrasted with interannual variability of the opposite sign increased poleward velocity warmer temperatures and decreased productivity observed in this same region during el nino years

a critical review of mid to late holocene sea level fluctuations on the eastern brazilian coastline abstract the eastern coast of brazil is 7000 km long and has been the subject of systematic paleo sea level investigations for more than 35 years more than 1000 samples have been radiocarbon dated and paleo sea level trends have been determined for 14 coastal sectors these trends have in common a mid holocene sea level maximum pmt above present sea level and a subsequent fall to the present time the time and elevation of the pmt the time when relative sea level rose above present mean sea level and the nature of late holocene sea level fall can however differ significantly discrepancies are observed not only between neighboring coastal sectors but also between different studies in a same coastal sector this paper discusses all the key radiocarbon dated samples used to establish regional trends in relative sea level on the eastern coast of brazil it is concluded that although many of the key sea level indicators are imprecise in time and space there is widespread evidence 30 of the data set for a progressive decline possibly with uneven rates of relative sea level since the end of the pmt

a nested grid model of the oregon coastal transition zone simulations and comparisons with observations during the 2001 upwelling season 1 the oregon coastal transition zone octz extends several hundred kilometers offshore where shelf flows interact with the northern california current a primitive equation numerical ocean model is used to study the upwelling circulation in this region from 1 may to 1 november 2001 this octz model obtains initial and boundary conditions from a larger scale model of the california current system and forcing from a regional atmospheric model product the model results are compared with extensive in situ and remotely sensed data and the model is found to provide a realistic representation of flows both over the shelf and in the broader octz simulation of coastal sea level and shelf currents over the complex topography of the central oregon coast is improved quantitatively relative to previous regional models a particularly significant qualitative improvement is realistic representation of coastal jet separation and eddy formation offshore of cape blanco three dimensional lagrangian analysis of water parcel displacement shows that the surface waters inshore of the separated jet are upwelled from near the bottom along the shelf as far north as 45 5 n a large eddy which incorporates some of this upwelled water and carries it farther westward forms offshore in the late summer ensemble simulations show a distinction between the strongly deterministic response to wind forcing over the shelf and the more unstable less predictable jet separation and offshore eddy formation processes in the region near cape blanco

cold halocline in the northern california current an invasion of subarctic water 1 subsurface upper ocean waters off oregon and vancouver island were about 1 c cooler in july 2002 than in july 2001 the anomalously cool layer coincides with the permanent halocline which has salinities of 32 2 to 33 8 suggesting an invasion of nutrient rich subarctic waters the anomalously cool layer lies at 30 150 m the cool anomaly is likely caused by stronger southward flow in the california current and weaker northward flow in the alaska and davidson currents during spring 2002 other factors may include reduced coastal downwelling in late winter and early spring 2002 enhanced eastward flow in the subarctic current and enhanced winter mixing offshore

environmental and sea level variations on the southeastern brazilian coast during the late holocene with comments on prehistoric human occupation abstract analysis of organic sediments including their diatom and pollen contents was carried out in a swamp forest on the coastal plain of sao paulo state southeastern brazil a palaeoenvironmental reconstruction was made regarding this region where communities of fisher gatherers lived in prehistory producing numerous shell mounds from at least 4900 until 3470 cal yr bp the site was a lagoon surrounded by a relatively open forest the occurrence of shell mounds 50 km from the coast and the peak of human occupation between 5700 and 3300 cal yr bp can be linked to the presence of this great lagoon which formed an important food source the lagoon desiccated ca 3470 cal yr bp i e during the late holocene sea level fall and was replaced by a swamp forest that still exists today this forest was altered during a short period between 1300 and 675 cal yr bp when a freshwater lake or marsh was formed as a result of a rise in groundwater level the climate in the area throughout the middle late holocene ca 5000 cal yr bp to the present has not changed significantly except for three slightly more humid episodes at 3470 2750 ca 1940 and 1300 675 cal yr bp no indications of human impact on the vegetation during this period could be identified our results show that from 4900 to 3470 cal yr bp sea level was higher than at present contradicting a widely accepted relative sea level trend that suggests that at least two negative sea level oscillations occurred during the holocene i e at 4560 4150 and 3200 2800 cal yr bp our data confirm recent studies instead proposing a continuously declining relative sea level during the late holocene

a separating coastal upwelling jet at cape blanco oregon and its connection to the california current system the coastal upwelling region near cape blanco oregon 433n o the west coast of the united states was studied using a towed ctd on seasoar a shipboard acoustic doppler current pro ler adcp satellite sea surface temperature maps and surface drifters during august 1995 the equatorward upwelling jet was inshore of the shelfbreak north of cape blanco meandered gently o shore around the cape and then veered sharply o shore just to the south of the cape analysis of vertical sections of density velocity and spicinessa con rmed the separation of an upwelling jet and front the jet was followed from over the shelfbreak north of the cape to 100 km o shore downstream of the cape the separating jet originates from the coastal upwelling jet leaving the shelf but is augmented by an o shore branching of the poleward undercurrent by combining information from adcp streamfunction maps with analysis of hydrographic data including distributions of the tracer like quantity spicinessa a conceptual model of the three dimensional circulation near the cape emerges a mid shelf upwelling jet encounters a coastal promontory then turns o shore stretching and deepening as it crosses the continental margin the jet then turns back shoreward cyclonically where the deepened equatorward ow encounters the top of the poleward undercurrent owing along the continental slope this causes a portion of the undercurrent to turn o shore to join and strengthen the equatorward transport in the separated jet throughout the separation process the coastal upwelling front and jet are continuous robust features separation of a coastal upwelling jet is an important mechanism for cross shelf transport from the coast to the deep ocean cape blanco appears to be the northernmost point where an equatorward jet regularly separates from the coast to become an oceanic jet and thus serves as the northern boundary of the region where an intense meandering current characteristic of the california current system

looking at the sea mt site river plate coast canelones uruguay abstract from the source of the river plate up to the border whit brazil in the atlantic coast the uruguayan littoral presents evidence of occupation by prehistoric groups based on the research project prehistoric occupations of the present uruguayan territory by the river plate department of canelones and eastern montevideo we have recorded diagnosed and studied several archaeological sites which provide evidence of these occupations and thus broaden our knowledge on the socio cultural aspects of the groups that generated them in this article we focus on the mt site with respect to its ergologic environmental and chronological aspects to approach the characterization of prehistoric sites in an area that has been scarcely studied before and of which little is known from an archaeological viewpoint this area is being affected by coastal dynamics spoliation and explosive urbanization the analysis of archaeological material observed during fieldwork complemented by the approach of created collections during the 20th century has allowed for the first time a global vision of the ergology and the site was thus characterized as a residential site in addition to the singularities of mt location the first absolute dating was obtained for the study area both allowing for an interpretation of the human environment relationship in times of sea level retreat during the late holocene

warmer or cooler late holocene marine palaeoenvironments interpreting southeast australian and brazilian sea level changes using fixed biological indicators and their δ18o composition abstract relic inter tidal assemblages of sessile organisms which are referred to as fixed biological indicators fbis are shown to be useful proxies for late holocene climatic and environmental changes as well as direct indicators of short term fluctuations in sea level a detailed comparison of change in the inter tidal assemblages of two southern hemisphere sites at comparable latitudes port hacking new south wales south east australia and the laguna imbituba region of southern brazil indicates periods of marked similarities in the timing and nature of changes at 5200 3800 cal years bp and differences after 2400 cal years bp there is sufficient concurrence of cooling phases and falling sea levels to strongly suggest that in some cases global rather than regional forcing factors are at work the value of inter tidal organisms as indicators of changed environments is developed by identifying the past and present distributions of the common marker species tubeworms barnacles and mussels the 18 o content of these extant specimens at port hacking confirmed changes in ocean water temperature and associated sea level behaviour corresponding to invasion or extinction of temperature sensitive species a similar pattern is repeated although in a less marked fashion in the laguna imbituba region of southern brazil

southward migration of the austral limit of mangroves in south america abstract temperature influences the global distribution of mangroves and global warming may be causing a poleward mangrove expansion sedimentary features pollen and isotopes data from six sediment cores as well as 14c datings indicated a marine transgression during the holocene and it contributed to the expansion of tidal flats occupied by saltmarshes environmental conditions suitable for mangroves development occurred on the study site during the holocene but according to 210pb and 14c dating the establishment of mangroves mainly represented by laguncularia trees only began between 1957 and 1986 ad on the studied tidal flats spatial temporal analysis based on satellite and drone images revealed a mangrove expansion of 10 ha in the study area between 2003 96 1 ha and 2019 106 1 ha nowadays in the study area saltmarshes mainly characterized by spartina and acrostichum are sharing tidal flats with mangroves represented by laguncularia 5 m tall and avicennia 11 m tall probably the absence of mangroves during the holocene followed by their establishment and expansion during the anthropocene in the subtropical zone is associated with a migration of the austral mangrove limit into the temperate zone caused by the gradual increase in winter temperatures this process may be related to a poleward mangrove migration since the late holocene caused by a natural holocene global warming however the industrial era warming must have intensified the mangrove expansion into temperate zones

shell sclerochronology and stable isotopes of the bivalve anomalocardia flexuosa linnaeus 1767 from southern brazil implications for environmental and archaeological studies abstract this study presents the first stable isotopic and sclerochronological calibration of the bivalve anomalocardia flexuosa linnaeus 1767 in relation to environmental variables in a subtropical coastal area of southern brazil we investigate incremental shell growth patterns and 18o and 13c values of modern specimens collected alive from the laguna lagoonal system lls shells of anomalocardia flexuosa are also one of the main biological components of pre columbian archaeological shell mounds and middens distributed along the brazilian coastline we therefore selected archaeological specimens from a local late holocene shell mound cabecuda to compare their stable carbon and oxygen isotope values with those of modern specimens shell growth increments 18o and 13c values respond to a complex of environmental conditions involving for example the effects of temperature and salinity the isotopic information extracted from archaeological specimens from cabecuda shell midden in the lls indirectly indicates that environmental conditions during the late holocene were different from present day in particular intra shell 18o and 13c values of archaeological shells reveal a stronger marine influence at 3 ka cal bp which is in contrast to the seasonal freshwater seawater balance that currently prevails at the lls

mid holocene evolution and paleoenvironments of the shoreface offshore transition north eastern argentina new evidence based on benthic microfauna abstract a sedimentary record spanning 5792 5511 cal yr bp and 3188 2854 cal yr bp was recovered at 36 45 43 s 56 37 13 w south west south atlantic the sedimentological features and micropaleontological benthic foraminifera and ostracoda content were analyzed in order to reconstruct paleoenvironmental conditions considerable environmental fluctuations are indicated by all these proxies five different stages were distinguished stage 1 ca 5800 5000 cal yr bp consists of muddy sand with abundant microfossils in this interval species typical for inner marine shelf environments maintained a high abundance stage 2 consists of plastic light greenish grey clays barren of microfossils and probably represents fluvial input from the de la plata river to the shelf contemporaneous of a lowering of sea level stage 3 is composed of brownish yellow sandy silts and represents increasing marine conditions in the area as reflected by higher faunal diversity and typical foraminifera of inner shelf environments stage 4 is made of homogeneous mud barren of microfossil which represents a new pulse of fluvial input to the shelf in consequence of a new fall in sea level the final part of the core stage 5 is a coarsening upward sequence grading from greeny brown clayey sandy silts to coarse shelly sands and represents the modern sedimentation in the area this interpretation strengthens the stepped model of late holocene sea level fall between 5511 5792 cal yr bp and 2854 3188 cal yr bp in buenos aires coast and agrees with the relative sea level history previously proposed by some authors from western south atlantic coasts

drifter behavior on the oregon washington shelf during downwelling favorable winds abstract drifters released offshore of oregon during predominantly downwelling favorable alongshore winds during three different deployments october 1994 january 1998 and september 1998 display similar behavior after being advected around in the offshore eddy field they move onshore to a particular isobath and are advected poleward alongshore without coming ashore numerical modeling results suggest that this may be due to downwelling circulation creating a marginally stable density gradient on the shelf inshore of the downwelling front thereby increasing the vertical eddy diffusivity which reduces the effective cross shelf ekman transport to nearly zero the downwelling front itself is accompanied by a poleward jet which carries drifters rapidly to the north this behavior is consistent with previous modeling results

upper ocean water mass characteristics of the california current summer 1993 abstract two large high resolution upper ocean surveys of the california current region were conducted in the summer of 1993 temperature and salinity were measured from a seasoar vehicle and velocity was measured by a ship borne acoustic doppler current profiler both surveys extended from the continental margin to 128 w and consisted of zonal sections 28 km apart the first survey 7 28 june extended from 39 5 n to 36 25 n and the second 16 august to 1 september extended from 39 0 n to 37 0 n the current field was fairly simple in june showing an equatorward surface jet with only one gentle meander a nearly continuous poleward california undercurrent near the continental margin and two anticyclonic subsurface eddies offshore of the jet by august meanders in the surface jet had strengthened and eddies dominated the flow field large scale trends in the water mass characteristics spiciness along three isopycnal surfaces 26 4 26 0 and 25 6 kg m 3 show that temperature and salinity tend to increase towards the equator and towards shore consistent with poleward advection along the continental margin local minima in spiciness tend to coincide with the equatorward surface jet local maxima in spiciness are associated with subsurface anticyclonic eddies which have a core depth of about 150 m and seem to originate in the california undercurrent over the continental slope at local latitudes we identified several different anticyclonic eddies each with different water mass characteristics all of the eddies we observed had diameters larger than the baroclinic radius of deformation water mass characteristics and migration rates are consistent with formation over the continental margin within the preceding 6 8 months

a poleward jet and an equatorward undercurrent observed off oregon and northern california during the 1997 98 el nino abstract the timing and intensity of the effects of the 1997 98 el nino on sea surface temperature sst and coastal sea level along the us west coast are examined using in situ time series measurements and the effects on upper ocean currents on the continental shelf and slope off oregon and northern california are examined using repeated shipborne adcp transects a mid shelf mooring off newport oregon and an hf surface current radar an initial transient positive anomaly was observed in both adjusted sea level and sst during may june 1997 followed by anomalously high coastal sea levels generally strongest during september 1997 through february 1998 and abruptly returned to normal in late february 1998 and by positive temperatures anomalies over the mid shelf that persisted longer into april 1998 low frequency coastal sea level anomalies propagated poleward at 2 1 m s poleward flow over the shelf and slope was enhanced at most depths during the el nino compared with following years northward currents in the upper 12 m over the continental shelf off newport oregon averaged 13 7 cm s stronger during august 1997 through february 1998 than during the same period the following year enhanced poleward flow was present at all latitudes sampled during november 1997 and february 1998 particularly over the continental slope these transects also provided clear views of a fall winter equatorward undercurrent which was both strongest and had the most alongshore similarity of form during the enso finally subsurface intensified anticyclonic eddies originating in the poleward undercurrent appear to be a recurrent feature of the circulation off newport late in the upwelling season

preface to special section on enhanced subarctic influence in the california current 2002 1 this special section discusses a rare phenomenon strong enhancement of subarctic influence in the california current system in the summer of 2002 this cold fresh anomaly in the upper halocline was more extreme than any prior observation though historical records extend back for several decades the subarctic anomaly extended more than 1500 km along the u s west coast from 49 n to 33 n it brought high nutrient waters into the coastal upwelling zone off oregon and northern california and produced exceptionally high chlorophyll concentrations inner shelf oxygen concentrations were very high near the surface and very low near the bottom the presence of this subarctic water mass was associated with anomalous southward currents detected by three different methods by satellite tracked drifters a mid shelf mooring and by satellite altimetry large scale wind forcing over the northeastern pacific during the previous winter and spring seems to be responsible for these anomalies

post lgm sedimentation on the outer shelf upper slope of the northernmost part of the sao paulo bight southeastern brazil abstract sedimentary and isotope data as well as 14 c ams dating on 15 box cores were used to identify the main post last glacial maximum lgm processes in the outer shelf and upper slope of the northernmost part of the sao paulo bight southeastern brazil results show slight but significant variations in calcium carbonate total sulphur and nitrogen contents as well as carbon and oxygen isotope ratios sedimentation rates varying from 5 to 184 mm kyr 1 are controlled by the shelf and upper slope morphology the brazil current meander dynamics and the coastal water offshore motion

mangrove vegetation changes on holocene terraces of the doce river southeastern brazil article i nfo high resolution sedimentological geochemical and pollen analysis on sediment core from the coastal plain of the doce river southeastern brazil revealed changes in the depositional system and vegetation caused by combined action of oscillations in relative sea level rsl and sedimentary supply during the holocene two main phases were discerned using sedimentary features 13 c 15 n total organic carbon toc total ni trogen n c n and cluster analysis of pollen data temporally synchronized with radiocarbon age dating the data indicates the presence of a lagoon system surrounded by a tidal plain colonized by mangroves and its sedimentary organic matter sourced from c4 plants between 8050 and 7115 cal yr bp however during the mid and late holocene the mangroves shrank and freshwater vegetation expanded c3 plants proba bly due to a marine regression during this phase the development of a lacustrine environment was followed by the colonization of herbs trees and shrubs the continuous sediment infilling into the lake allowed the ex pansion of a herbaceous plain as seen today this geomorphologic and vegetation evolution is in agreement with the mid holocene rsl maximum above present rsl and subsequent fall to the present time

taphonomic signatures in molluscan fossil assemblages from the holocene lagoon system in the northern part of the coastal plain rio grande do sul state brazil abstract molluscan shell accumulations shell beds are very common in shallow marine and estuarine environments in south america and also on the continental shelf between argentina and southern brazil the development of these shell beds is restricted to the quaternary and can provide a great opportunity for taphonomic studies which are rare in this geographic location this study investigates the influence of environmental processes on the destruction of biological remains in a subtropical lagoonal setting by describing the taphonomic signatures occurring in the mollusk shells from the tramandai lagoon northeastern rio grande do sul state brazil this lagoon system originated during the regressive phase that followed a transgressive maximum at 6 0 6 5 ka bp the taphonomic variables fragmentation margin modification surface alteration hinge fine scale alteration and corrosion degree and their damage states were recorded for 1000 shells of erodona mactroides the shells were recovered from two outcrops 8 km apart 14c ams dating were performed on the shells of e mactroides from those outcrops which yielded similar ages from 1060 to 1490 cal yrs bp the ages would indicate that the tramandai lagoon occupied a larger area and must have been subjected to very rapid progradation towards its present position several taphonomic variables such as fragmentation surface alteration and corrasion extent and oxidation presented significant differences p

mid to late holocene evolution of transgressive dunefields from rio grande do sul coast southern brazil abstract the aim of this paper is to examine the dunefield evolution of the rio grande do sul rs coastal stretch from torres to mostardas which presents progradational aggradational and retrogradational barriers the stratigraphy and sedimentary facies of 26 cores along 9 profiles were analyzed the stratigraphy of the cores along the profiles agreed with the suggested barrier types the northern area comprises prograded barriers in jardim do eden and magisterio retrograded barriers in dunas altas an aggradational barrier and the southernmost profiles solidao sao simao and mostardas retrograded barriers three major periods of soil formation and dunefield stabilization were found from 4820 to 3970 cal yr bp in 2760 2460 cal yr bp and from 1570 to 710 cal yr bp these periods coincide with periods where the literature cites an increase in moisture during the mid to late holocene this coincidence of soil formation and wet climate indicates that the climate might be controlling dunefield evolution on the rs coast since 5000 yr bp the stratigraphic data of the three most representative cores were correlated and along with the available ages from palaeosols and the facies descriptions 10 phases of aeolian activity and stabilization were recognized for the mid littoral of rs

detachment faulting and the evolution of passive continental margins major detachment faults play a key role in the lithospheric extension process in the basin and range province and may also be important in other continental extension terranes such detachment faulting leads to an inherent asymmetry of extensional structure and of uplift subsidence patterns detachment models developed for the formation of metamorphic core complexes can also be applied to the formation of passive continental margins we therefore suggest the existence of upper plate and lower plate passive margins these give rise to a complementary asymmetry of opposing margins after continental breakup transfer faults offset marginal features and allow margins to switch from upper plate to lower plate characteristics along strike

holocene sea level history evidence from coastal sediments of the northern rio grande do norte coast ne brazil the holocene sea level history of the mesotidal northern rio grande do norte coast ne brazil was reconstructed from sedimentology and ams radiocarbon dating of beachrock and tidal lagoonal sediments at 7000 cal year bp at 3 m sea level stood and passed the modem sea level 6700 cal year ago the holocene highstand reached 1 3 m above modem sea level at 5900 cal year bp as determined by beachrock samples from the uppermost part of an intertidal foreshore deposit a 5700 cal year old shell midden overlies this beachrock that represents the spring tide sea level after the highstand sea level dropped to its present position beachrock samples from intertidal upper foreshore deposits were used for elevation and age control beachrock positions with their error bars are all within the tidal range envelope therefore no secondary oscillations during the sea level fall can be confirmed a linear sea level fall of this magnitude can be explained by the mechanism of equatorial ocean syphoning c 2005 elsevier b v all rights reserved

a taphonomic study of δ13c and δ15n values in rhizophora mangle leaves for a multi proxy approach to mangrove palaeoecology abstract the response of mangrove ecosystems to environmental change can be examined with stable isotopic tracers of c and n the 13c and 15n of a taphonomic series of rhizophora mangle l red mangrove leaves were analyzed from twin cays belize to facilitate reconstruction of past mangrove ecosystems on twin cays fresh leaves of dwarf r mangle trees 0 5 m high were found to have more negative 15n values mean 10 and more positive 13c values mean 25 3 compared to tall r mangle trees mean 15n 0 13c 28 3 these isotopic differences can be related to nitrogen and phosphorus availability ecology 83 2002 1065 we investigated three taphonomic stages in the fossilization of r mangle leaves into peat with the following 1 senescent leaves 2 fallen leaves on the surface of the peat and 3 sub fossil leaves found within mangrove peat in addition by examining natural leaf assemblages we established that 13c and 15n of r mangle leaves were not altered during senescence despite a significant 50 decrease in the n modern dwarf and tall trees could still be identified from 13c and 15n analyses of the leaf assemblages found directly below a tree dwarf and tall trees could also be identified from 13c analyses of leaves that had decomposed for four months although dwarf and tall trees could not be statistically separated after four months according to 15n analyses leaves with very negative 15n 7 were only collected below dwarf trees leaf fragments were present in 50 cm long cores of peat from four sites on the island and their isotopic compositions were determined the ranges of 13c 29 to 22 and 15n 11 to 2 values from sub fossil leaves were similar to the ranges from modern leaves 13c 29 to 23 15n 11 to 1 the sub fossil leaf isotopic compositions were independent values in comparison to the uniform values of the surrounding peat because of the stability and persistence of the stable isotopic signals they could contribute significantly to a multi proxy approach to mangrove palaeoenvironmental reconstruction

a continuous multi millennial record of surficial bivalve mollusk shells from the sao paulo bight brazilian shelf abstract to evaluate the potential of using surficial shell accumulations for paleoenvironmental studies an extensive time series of individually dated specimens of the marine infaunal bivalve mollusk semele casali was assembled using amino acid racemization aar ratios n 270 calibrated against radiocarbon ages n 32 the shells were collected from surface sediments at multiple sites across a sediment starved shelf in the shallow sub tropical sao paulo bight sao paulo state brazil the resulting 14 c calibrated aar time series one of the largest aar datasets compiled to date ranges from modern to 10 307 cal yr bp is right skewed and represents a remarkably complete time series the completeness of the holocene record is 66 at 250 yr binning resolution and 81 at 500 yr binning resolution extensive time averaging is observed for all sites across the sampled bathymetric range indicating long water depth invariant survival of carbonate shells at the sediment surface with low net sedimentation rates benthic organisms collected from active depositional surfaces can provide multi millennial time series of biomineral records and serve as a source of geochemical proxy data for reconstructing environmental and climatic trends throughout the holocene at centennial resolution surface sediments can contain time rich shell accumulations that record the entire holocene not just the present

smooth or oscillating late holocene sea level curve evidence from cross regional statistical regressions of fixed biological indicators abstract what if any is the pattern of change of the late holocene sea level curve if a common pattern exists can it be better discerned in the non glaciated tectonically stable regions of the southern hemisphere and is sea level data more reliable from one type of marine sample than another to begin an investigation of these questions we present a review of regressing time elevation plots from the low to mid latitudes of the southern hemisphere based upon the differential between modern and past levels of various fixed biological indicators mainly calcareous tubeworms and corals stranded up to 2 m above present relative sea levels the sample sets come from our work in southeast australia and comparable work from north east australia the pacific islands and brazil we show that using evidence obtained from fixed intertidal tubeworm species there is no statistical exclusivity between the smooth and oscillating polynomials but corals are more problematic in situ tubeworm species with their reduced error bars in comparison to corals fulfil the condition of providing more robust results for statistical analysis regression curves based on these species point to cross regional similarities in the pattern of sea level movement of the last 6000 years across the lower latitudes of the southern hemisphere these statistical exercises while not able to yield definitive conclusions can highlight statistically equally likely alternative patterns of sea level movement which can then be tested by field evidence they can also give useful indications of the quality of sea level data obtained from different biological sources as in the difficulties in the use of corals compared to common intertidal tubeworm species

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

relative sea level changes in the last 5500 years in southern brazil laguna imbituba region santa catarina state based on vermetid ages abstract twenty six new radiocarbon dates from vermetid shells collected in the southernmost sector of the brazilian rocky coast presented dates ranging from 5410 80 to 190 65 years b p with associated paleosea levels varying from 2 10 m to 0 20 m above present sea level the overall suggested trend of the relative sea level rsl declining until at least 190 years b p is somewhat contradictory to a proposed rsl rise in the last 1000 years in southern brazil the data also seem to undermine a more widely accepted rsl trend that suggests that at least two negative rsl oscillations occurred between 4100 and 3800 years b p and between 3000 and 2700 years b p the maximum elevation of the rsl in the holocene in southern brazil was possibly lower than that observed in most of the brazilian eastern coast discrepancies between ancient sea levels of similar ages are attributed to coincidental methodological problems to imprecisions in determining past relative sea levels and to possible changes in the geomorphology and wave climate close to shore during the last 5000 years a general trend of increasing 18 o with a reduction in age in the studied samples may suggest a gradual reduction of water temperature in the region during the same period

the coastal ocean off oregon and northern california during the 1997 8 el nino abstract the evolution and decay of el nino 1997 8 was observed in coastal waters off oregon in a sequence of cruises along 44 6 n from the coast to more than 150 km offshore hydrographic observations were made during eleven cruises between july 1997 and april 1999 at stations on the newport hydrographic line which had been occupied regularly from 1961 to 1971 the data from the earlier decade provide a basis for defining normal conditions and allow comparisons with the recent el nino in terms of t s spiciness and geostrophic velocity independent of el nino the ocean in july 1997 was already anomalously warm offshore of 50 km and above 100 m by september 1997 there were unambiguous indications of el nino isotherms and isohalines sloped down toward the coast indicating poleward flow over shelf and slope and anomalously spicy water was present at the shelf break in november 1997 and february 1998 shelf break waters were even warmer and there was strong poleward flow inshore of 100 km extending to depths greater than 200 m the april 1998 section closely resembled that of april 1983 another el nino year but by june 1998 the anomalies were mostly gone november 1998 was near normal and the sections from subsequent cruises resemble the mean sections from 1961 1971 four cruises between november 1997 and november 1998 included sampling at several latitudes between 38 and 45 n as expected these sections show significant alongshore gradients but also a surprising degree of homogeneity in the anomalous features associated with el nino in the temperature salinity spiciness and geostrophic velocity fields the anomalous signature of el nino was stronger at its winter peak in 1998 than in 1983 but the signature in the temperature and spiciness fields and in coastal sea level did not persist as long as in 1983 by april 1999 the coastal ocean from 38 n to 45 n was significantly colder than it had been in april 1984

smooth or oscillating late holocene sea level curve evidence from the palaeo zoology of fixed biological indicators in east australia and beyond abstract the nature of late holocene sea level change has important palaeo environmental implications for the understanding of past and present coastal oceanic and climatic systems this study develops a fixed biological indicator fbi method based on tubeworm barnacle assemblages in order to construct a late holocene sea level curve for south east australia it also compares changes within and between mid latitude regions of the southern hemisphere using the palaeo biology of inter tidal sub fossils that have provided time elevation data covering the past 5000 years five sites from around the mouth of the port hacking estuary 29 km south of sydney are described in detail the results suggest that rather than relative sea level describing a stable or smoothly falling pattern from a maximum of 1 0 m above present over the last 5000 years on the southeast australian coast there have been complex movements from a maximum of over 1 5 m with at least one marked fall between 3500 and 3400 yr bp and the possibility of a small positive oscillation around 1900 yr bp furthermore changes in the inter tidal species at our sites suggest that there was a period between 4300 and 2800 years where ocean temperatures were warmer than present our port hacking findings are compared with other studies from the east coast of australia as well as the pacific islands and brazil evidence from each location suggests a broad similarity in the timing of environmental events and marine fluctuations across an expanse of the southern hemisphere are such similarities coincidental or part of mechanisms common to mid latitude southern hemisphere regions

the brazilian sea level curves a critical review with emphasis on the curves from the paranaguaand cananeia regions abstract relative sea level curves for the mid to late holocene have been proposed for eight different sectors along the brazilian coast this paper aims to review the data used to construct the curves proposed for two sectors the paranaguaand cananeia regions in southeast brazil more specifically we analyze the palaeo sea level indicators vermetid tubes shells wood fragments and shell midden deposits related to 1 the sea level maximum of the mid holocene and 2 the two secondary oscillations that would have occurred between 4100 3800 years b p and 3000 2700 years b p the sedimentary deposits of the coastal plain as well as vermetid datings suggest a mid holocene sea level maximum between 3 5 and 4 m the great majority of the indicators used to infer the secondary oscillations in previous studies were derived from shell middens besides being unreliable palaeo sea level indicators these data also showed inconsistencies that undermine the existence of such oscillations the plot of all the data derived from vermetid samples found along the brazilian coast also indicate a rather smoother sea level fall in the last 5100 years

a high precision record of mid late holocene sea level events from emergent coral pavements in the houtman abrolhos islands southwest australia early work on sea levels in southwest australia claimed to recognise a holocene sea level highstand which was not seen in better known sea level records elsewhere at the time more recent work has confirmed that a mid holocene highstand occurred about 6 kyr ago as new data on oscillating sea levels from the region have recently been published a high continuity precisely dated and accurately surveyed record was obtained from emergent coral pavements in the leeward houtman abrolhos islands serventy island a tectonically stable region from where good quality holocene sea level data have been previously obtained from corals from the mid holocene highstand ca 7 u th kyr ago sea level declined linearly during the remainder of the holocene as the carbonate platform prograded leewards hydro isostatic controls are probably significant in the record c 2005 elsevier ltd and inqua all rights reserved

a numerical modeling study of the upwelling source waters along the oregon coast during 2005 abstract regional ocean circulation along the oregon coast is studied numerically for forcing fields derived from year 2005 and climatological mean conditions the primary object is to study directly the lagrangian pathways by which fluid arrives in the oregon upwelling zone roughly half of the upwelling fluid is found to arrive in the regional domain from alongshelf source points primarily north but also south of the oregon upwelling zone while the other half ultimately arrives from points offshore and west of the zone for both the year 2005 and the climatological simulations different regimes of dominant alongshelf source waters are found with cape blanco being a dividing point for northern versus southern sources and with the water parcels coming primarily from depths below 100 m for the offshore sources most upwelling fluid originates from depths between 150 and 250 m during 2005 but from within the upper 150 m for the climatological simulations in both cases there are specific regions alon

multiplatform observations of boundary layer structure in the outer rainbands of landfalling typhoons this paper analyzes data collected from a new set of observational platforms in the coastal area of china which consist of a mobile observation system meteorological tower automatic weather station and doppler radars to investigate the mean and turbulent boundary layer structure and evolution during the landfall of typhoons an example of these data is provided from typhoon morakot 2009 vertical profiles of wind velocities and thermodynamic parameters from the observed data allow us to identify different boundary layer structures during and after landfall these structures sampled in regions of the outer core are stratified into periods where convection is occurring termed convective and periods where convection has recently 2 h occurred termed postconvective data analyses show that the thermodynamic mixed layer depth and inflow layer depth are higher during the convective period than the postconvective period the mixed layer depth is found to be within the strong inflow layer but the height of the maximum tangential wind speed is above the inflow layer during both periods contrary to recent observational studies of the boundary layer structure of tropical cyclones over water high frequency wind data show that momentum flux turbulent kinetic energy tke and integral length scales of wind velocities are all much larger during the convective period than the postconvective period the results suggest that convective downdrafts may play an important role in modulating turbulent flux tke vertical mixing and boundary layer recovery processes

altimeter estimates of anomalous transports into the northern california current during 2000 2002 1 surface transports into the california current are calculated from topex poseidon altimeter surface height slopes during the 9 5 year period from october 1992 may 2002 these quantify the anomalous onshore and southward displacements of the water column during the 2000 2002 period which had been hypothesized by others based on anomalous water properties observed in mid 2002 off oregon anomalous eastward transport into the boundary between 52 54 n occurred first mid 2000 to mid 2001 followed by eastward transport into the boundary between 50 52 n in 2001 equatorward transports during 2001 and 2002 resulted in approximately 800 km of anomalous southward displacements during the 1 5 years prior to the anomalous observations off oregon this sequence suggests that both onshore and southward displacement anomalies off british columbia and the pacific northwest contributed to the subarctic characteristics of the water observed off oregon