facies architecture of a last interglacial barrier a model for quaternary barrier development from the coorong to mount gambier coastal plain southeastern australia abstract the last interglacial woakwine range a linear barrier shoreline complex of temperate bioclastic carbonate origin in the southeast of south australia occurs essentially uninterrupted over a distance of 300 km and up to 10 km inland from the present coastline mapping of the internal facies architecture of the barrier as revealed in mccourt s cutting southeast of robe reveals the presence of transgressive and regressive facies associated with the last interglacial maximum oxygen isotope substage 5e as well as an older aeolianite within the core of the barrier correlated herein with oxygen isotope stage 7 amino acid racemisation and thermoluminescence dating indicate that volumetrically the majority of the woakwine range is of last interglacial age the bulk of the barrier structure comprises aeolian facies in the form of landward migrating coastal dunes the internal facies appear to record the culmination of the post stage 6 marine transgression at the onset of substage 5e and possibly the termination of substage 5e based on the shallow seaward dip of the discontinuity between regressive littoral and sublittoral facies

paleomagnetic study of juvenile basaltic andesite clasts from andean pyroclastic density current deposits abstract additional paleomagnetic data are necessary to improve geomagnetic models of secular variation during the holocene especially from the southern hemisphere in most of the andean volcanoes from ecuador to the chilean central volcanic zone very well dated lava flows are rare in contrast andesitic to basaltic pyroclastic density current pdc deposits commonly contain charcoal facilitating their age determination with 14c in this study we present the magnetic properties and the paleomagnetic results obtained from three pdc deposits of basaltic to andesitic composition one is the 2006 pdc deposit from the ecuadorian tungurahua volcano and the two others are well dated pdc deposits from chilean volcanoes osorno and villarica although most paleomagnetic studies in pyroclastic rocks deal with the estimation of emplacement temperatures from bulk deposits or accessory and accidental non juvenile clasts we show that juvenile clasts embedded in pdc deposits provide well grouped paleomagnetic directions indicating post emplacement in situ cooling below curie points moreover the rapid cooling of the juvenile clasts yields an abundance of single domain titanomagnetite grains providing low unblocking temperatures and a reliable material for paleointensity determination

beach ridges and prograded beach deposits as palaeoenvironment records abstract beach ridges are landforms commonly developed on prograded coasts with beach shorelines a sequence of beach ridges coupled with their subsurface deposits can be regarded as a time series of coastal evolution methodological advances in field surveying and chronology applicable to beach ridges have led to detailed palaeoenvironmental reconstructions to be derived from such sequences this paper reconsiders the basic aspects of beach ridges and deposits which need to be properly understood for their comprehensive interpretation in a palaeo environmental context it also reviews case studies in which beach ridge sequences have been used to unveil past sea level history catastrophic events and climate changes proposed formative processes of beach ridges include 1 progradation of sandy beach and berm formations in relation to fairweather waves coupled with aeolian foredune accumulation 2 building of gravel ridges by storm waves 3 welding of longshore bars beach ridge formation through sea level oscillation is thought to be questionable and caution is suggested for this process when undertaking palaeoenvironmental reconstruction beach deposit stratification is known to dip either landwards or seawards but landward dips are uncommon seaward dipping stratification is formed in relation to beachface progradation and is usually dissected in places by erosion surfaces resulting from episodic beach retreat the boundary between the foreshore and the underlying shoreface is well defined only in the case that longshore bars lead to complex bedding structure relative to that of the foreshore reliable chronology of beach ridges can be determined by radiocarbon and optically stimulated luminescence osl dating radiocarbon dating of articulated shells which are considered not to be extensively reworked provides robust results but osl dating is more useful as it enables direct dating of sediment grains it is noted that there are restrictions in chronological resolution and continuity inherent to beach ridge and beach deposits the plan view geomorphic expression of beach ridges typically consists of ridge sets with multi decadal intervals whereas their internal sedimentary structures define shorter time scales records of beach sedimentation and erosion are likely to be reworked by episodic high magnitude beach retreat and the resultant record of the net progradation is likely to be sporadic and discontinuous the height of sandy beach ridges is often variable due to differing degrees of aeolian sand accumulation and they are thus not used as sea level indicators unless purely wave built gravel ridge height is a relatively reliable indicator of sea level but can vary in response to storminess fluctuations subsurface sediment facies boundaries are preferred as sea level indicators and those proposed include boundaries of aeolian beach foreshore shoreface and upper lower shorefaces catastrophic events are expressed in both erosional and depositional records erosion surfaces or scarp imprints revealed in a cross section of beach deposits indicate storm or tsunami events however erosional events are likely to rework previous records of sedimentation and even other erosional events and thus the apparent history decoded from the resultant deposits tends to be biased several attempts for estimating the frequency and intensity of prehistoric cyclones rely on assumed relationships between the level of coarse sand beach ridges and cyclone inundation the formative process of coarse sand ridges remains uncertain and needs to be clarified as it constitutes the fundamental basis of these attempts the growth rates of beach ridge systems are expected to reflect fluctuations in river sediment discharge to the coast and in aeolian sand flux due to onshore winds both of which are affected by climate change assessment of the growth rate is potentially improved by ground penetrating radar survey of subsurface structure and by detailed chronology orientation of beach ridges reflects long term trends in wave direction inferred relationships between beach ridges and cyclic fluctuations of sea level and climate rely on weak assumptions and are not substantiated by rigid chronological evidence and thus remain highly questionable correlation between the inherently decadal signal of beach ridge intervals and possible climate cycles such as sunspot activity is probably coincidental as it lacks causal explanations

secular variation of the earth s magnetic field and application to paleomagnetic dating of historical lava flows in chile abstract the recent geomagnetic secular variation is mainly characterized by the large growth of the south atlantic magnetic anomaly during the last three centuries first documented by the geomagnetic model gufm1 jackson et al 2000 we report new paleomagnetic results directions and paleointensities from several sites in two well dated lava flows in chile the 1835 ad eruption of the osorno volcano and the 1751 ad eruption of the llaima volcano in addition paleointensities were obtained on 14 samples from bricks of shelters built along the main road across the andes from santiago chile to mendoza argentina in 1770 5 ad the results confirm the high reliability of the global geomagnetic model gufm1 for the last three centuries with a large amplitude of the secular variation in inclination 20 and intensity 25 t results from three 14 c dated volcanic units in the time interval 1400 1750 ad indicate that more paleomagnetic results in well dated lava flows are necessary to improve the robustness of existing global geomagnetic models at this stage precise paleomagnetic or archeomagnetic dating in south america using global models should be restricted to the last 3 centuries to illustrate the potential of paleomagnetic dating in region and time interval with very large geomagnetic secular variation we report paleomagnetic data from several sites in historical lava flows 1700 1900 ad from the antuco llaima and villarrica volcanoes that permit to refine the ages of the major historical effusive volcanic events

palaeogeographic climatic and tectonic change in southeastern australia the late neogene evolution of the murray basin the murray basin is a low lying but extensive intracratonic depocentre in southeastern australia preserving an extraordinary record of late neogene sedimentation new stratigraphic and sedimento logic data allow the long term evolution of the basin to be re evaluated and suggest a significant role for 1 tectonism in controlling basin evolution and 2 progressive and step wise climatic change beginning in the early pleistocene tectonic change is associated with regional uplift occurring at approximately the same rate from the early pliocene until the present day and possibly associated with changing mantle circulation patterns or plate boundary processes this uplift led to the defeat and re routing of the murray river australia s major continental drainage system key to our interpretation is recognition of timing relationships between four prominent palaeogeographic features the loxton parilla sands strandplain the gambier coastal plain palaeo megalake bungunnia and the kanawinka escarpment geomorphic and stratigraphic evidence suggest that during the early pliocene the ancestral murray river was located in western victoria flowing south along the douglas depression relatively small amounts of regional uplift 200 m defeated this drainage system dramatically changing the palaeogeography of southeastern australia and forming plio pleistocene megalake bungunnia at its maximum extent lake bungunnia covered more than 50 000 km 2 making it one of the largest known palaeo or modern lakes in an intracontinental setting magnetostratigraphic constraints suggest lake formation c 2 4 ma the formation of lake bungunnia influenced the pliocene coastal dynamics depriving the coastline of a sediment source and changing the coastal system from a prograding strandline system to an erosional one erosion during this period formed the kanawinka escarpment a palaeo sea cliff and one of the most prominent and laterally extensive geomorphic features in southeastern australia marine sediments c 800 ka to c 1 16 ma represent the time of re establishment of depositional coastal dynamics and of a permanent outlet for the murray river this age range is consistent with our best estimate of the age of the youngest lake bungunnia sediments and points towards an early pleistocene age for the demise of the lake system the youngest lake bungunnia sediment present on a number of distinct terraces suggests that progressive step wise climatic change played a role in the demise of the lake however in order for the ancestral murray river system to have been able to breach the pre existing tectonic dam it is likely that tectonic change and or temporarily enhanced discharge was also significant this scenario indicates that the modern murray river has only been in existence for at most 700 ka c 2010 elsevier ltd all rights reserved less

late pleistocene landscape response to climate change eolian and alluvial fan deposition cape liptrap southeastern australia abstract sea cliffs along the western coast of cape liptrap at arch rock provide nearly continuous exposure of calcareous eolianites dated at 68 112 ka five optically stimulated luminescence osl ages calcareous eolian deposition began immediately after the last interglacial marine highstand oxygen isotope stage ois 5e and continued during sea level fall until the beginning of ois 4 west southwesterly winds transported calcareous sand across 12 km of exposed continental shelf by the beginning of ois 4 a brief period of cold arid windy continental climate with ephemeral but intense surface runoff immediately preceded the last glacial maximum lgm this resulted in fluvial reworking of the calcarenites into an alluvial fan dated at 23 25 ka four osl ages the fan overlies peat dated at 25 279 yr cal bp and is capped by a paleosol dated at 6010 yr cal bp concurrent eolian reworking by northwesterly winds of siliceous sediments on marine terraces along the eastern and central portion of cape liptrap formed siliceous longitudinal dunes with ages ranging from 19 to 24 ka five osl ages the phase of maximum landscape instability at cape liptrap coincides with solar insolation and air temperature minima and preceded the lgm by several thousand years

dynamics of outgassing and plume transport revealed by proximal unmanned aerial system uas measurements at volcan villarrica chile volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing and on geological timescales constitute an important source of volatiles to the earth s atmosphere measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles however significant gaps remain in our global inventories of volcanic emissions particularly for co2 which requires proximal sampling of a concentrated plume for those volcanoes where the near vent region is hazardous or inaccessible unmanned aerial systems uas provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments here we present gas compositional data acquired using a gas sensor payload aboard a uas flown at volcan villarrica chile we compare uas derived gas timeseries to simultaneous crater rim multi gas data and uv camera imagery to investigate early plume evolution so2 concentrations measured in the young proximal plume exhibit periodic variations that are well correlated with the concentrations of other species by combining molar gas ratios co2 so2 1 48 1 68 h2o so2 67 75 and h2o co2 45 51 with the so2 flux 142 17 t day from uv camera images we derive co2 and h2o fluxes of 150 t day and 2850 t day respectively we observe good agreement between time averaged molar gas ratios obtained from simultaneous uas and ground based multi gas acquisitions however the uas measurements made in the young less diluted plume reveal additional short term periodic structure that reflects active degassing through discrete audible gas exhalations

evolution of holocene coastal environments near robe southeastern south australia abstract coastal robe range and adjacent woakwine range situated 10 15 km inland are the most southwesterly and youngest of a series of parallel low altitude pleistocene beach dune barriers in southeastern south australia in the early holocene the post glacial marine transgression flooded the robe woakwine corridor thus forming a shallow back barrier lagoon open to the southern ocean near the present towns of robe and beachport marine to lagoonal bioclastic carbonate quartz sedimentation prevailed within the corridor from ca 7500 2000 yr bp along the seaward side of robe range transgressive sands were deposited initially as ephemeral sand flats but were mostly redistributed as coastal dunes which today remain active and blanket the pleistocene core of the range sand was also transported along the coast and deposited within the protected embayments of guichen and rivoli bays in the form of prograded beach ridge plains eventually isolating the back barrier lagoon from the open ocean sediment aggradation within the lagoon cessation of marine influence and regional uplift of 0 7 m during the holocene combined to transform the corridor to a lacustrine landscape fossil molluscs foraminifera and ostracods are diagnostic of successive palaeo environments and thus signify stages in the rapid geomorphic evolution of the coastal robe woakwine corridor

late quaternary sea level highstands in the tasman sea evidence from lord howe island abstract lord howe island situated 600 km east of australia provides a unique opportunity to evaluate late quaternary highstands of sea level in the tasman sea the mid ocean island which is the site of the southernmost coral reef is composed of basalts of late tertiary age and calcarenites derived from bioclastic reefal carbonates both erosional and depositional evidence of late quaternary highstands of sea level is preserved uranium series disequilibrium dating of coral clasts from a calcarenite beach facies at neds beach on the northeast of the island yielded a mean age of 136 000 yr b p thermoluminescence dating of the quartz sand fraction from the same deposit using fine grained and coarse grained methods yielded ages of 138 000 and 116 000 yr b p respectively these ages are interpreted to indicate that this beach unit within which fossil bones and eggs of the extinct horned turtle meiolania are found formed during the last interglacial when the sea was 2 4 m above present benches and platforms developed on tertiary basalt and on late pleistocene calcarenite on the more sheltered lagoonal shore on the west of the island indicate a sea level up to 1 5 m higher than present during the holocene cemented boulder conglomerates ca 3000 yr b p at north head and emergent mollusc rich carbonate muds ca 900 yr b p within an embayment fill at old settlement beach further support this interpretation these palaeo sea level data from the tasman sea support previous estimates of the height of the last interglacial sea surface relative to eastern australia and supplement a growing body of evidence for a higher sea level in the region during the mid to late holocene

understanding late quaternary change at the land ocean interface a synthesis of the evolution of the wilderness coastline south africa coastal barrier systems have been widely used to understand the responses of coastal margins to fluctuating pleistocene sea levels what has become apparent particularly with the development of robust chronological frameworks is that gaps in terrestrial barrier sedimentary records are not uncommon and that they most likely reflect phases of barrier construction on the now submerged continental shelf thus understanding the land ocean interface through time is critical to fully appreciate the quaternary archives contained within the barriers and their associated back barrier deposits this study uses offshore and lakefloor back barrier seismic profiling from the south african south coast at wilderness to link the sub aerially exposed barrier stratigraphy to the currently submerged geological and sedimentological record a total of eight separate submerged aeolian units are identified at water depths of up to 130 m below mean sea level their approximate ages are constrained with reference to the eustatic sea level record and the deepest units are consistent with the estimated magnitude of sea level lowering during the last glacial maximum lgm on the south african coastline as previously assumed aeolian sedimentation tracked the shoreline onto the continental shelf during the late pleistocene during sea level regressions both the incision of fluvial channels and the deposition of back barrier systems occurred across the continental shelf during late low stand early transgression periods landward shoreface migration occurred pre existing channel incisions were infilled and pre existing barriers were truncated rapid transgression however allowed the preservation of some back barrier deposits possibly aided by protection from antecedent topography as sea level neared the present day elevation erosion of the mid shelf sediments resulted in the development of a holocene sediment wedge which was augmented by holocene fluvial sediment supply the holocene sand wedge is preserved in the back barrier lakes and was deposited during the holocene highstand inundation overlying middle to late holocene terrestrial muds reflect the deposition of river borne mud onto the shelf these results clearly demonstrate that within transgressive regressive sea level cycles accommodation space for barriers is controlled by antecedent drainage systems and gradients on the adjacent inner continental shelf

atmospheric pressure response to mesoscale sea surface temperature variations in the kuroshio extension region in situ evidence several research cruises were conducted across the kuroshio extension front to examine the low level atmospheric responses to mesoscale variations in sea surface temperature sst surface meteorological observations including sea level pressure slp and sst were collected at two moored buoys that were located on either side of the kuroshio extension and from a research vessel as it moved between the two buoys during the various cruises spatial perturbations in slp along the ship transects calculated by subtracting moored buoy slp from that of the moving ship tend to be positive negative where sst is lower higher on spatial scales of about 100 km and the magnitude of these slp perturbations near the sst front can exceed 1 0 hpa radiosonde data also show that the atmospheric boundary layer thins thickens over lower higher sst although the contribution of across track component in the wind cannot be calculated the along track component of divergence suggests low level convergence over higher sst the thermally induced pressure gradient is important in the momentum budget suggesting that sea breeze like local circulations formed over the sst fronts indeed the pressure adjustment mechanism can sometimes dominate even on a scale of 100 km although it is not always observed the time scale in which the boundary layer thickness adjusted to sst is estimated to be 1 day or less

sea level pressure minimum along the kuroshio and its extension abstractatmospheric effects of sea surface temperature sst fronts along the kuroshio and kuroshio extension k ke are investigated by examining spatial characteristics of the climatological sea level pressure slp surface winds and surface heat flux q fields based on an in situ observation dataset a hydrostatic effect of the sst front is observed during the northwesterly monsoon characterized by a westward extending low slp wedge trough slightly south of the peak in q along the k ke ageostrophic surface westerlies crossing slp isobars toward a trough center are found north of the low slp wedge apparently because of the eastward acceleration by the vertical mixing effect this feature of the ageostrophic winds is less pronounced south of it a north south asymmetry arising as vertical mixing accelerates decelerates eastward ageostrophic winds north south of it while the slp trough near the sst front is found nearly year round except for summer its meridional location seasonally migrates pr

assumed holocene highstands gulf of mexico basic issues of sedimentary and landform criteria discussion record high mid and late holocene relative sea levels significantly above the current sea level have been widely documented in certain areas of the australo pacific region brazil lessa et al 2000 and parts of africa and india that were not characterized by tectonic uplift and or glacio isostatic rebound such elevated sea levels are yet to be reliably identified on our gulf and atlantic shores radically departing from traditional gulf of mexico sea level curves morton et al 2000 now suggest recurring highstands throughout the entire second half of the holocene epoch their findings echo earlier ideas in the same vein see otvos 1995 1997 1999 however a detailed analysis of several lines of evidence presented by morton et al raises serious doubts about these conclusions morton et al accept the position of beach ridge summits as indicative of higher than present elevations thus seaward declining beach ridge summits on bolivar peninsula galveston island and other coastal areas of texas in their view reflect late holocene sea levels that fell from their highest elevations although beach ridges are of wave constructed berm ridge foredune or composite origins otvos 2000 morton et al fail to distinguish adequately among these categories by sediment and landform analysis the problem is that under favorable circumstances wave built berm ridges may be accurate markers of ancient sea levels or lake levels foredunes on the other hand aggrade to varying supratidal elevations rising several meters above the associated high tide level for this reason summit elevations of relict foredunes can not provide precise data on corresponding sea level otvos 1995 foredune ridges foredune ridges often overlie mask and bury wave built berm ridges beal and shepard 1956 because sand is usually readily available for wind transport on most gulf shores the upper interval in most beach ridges tends to be of eolian origin except when wave built

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

air sea interaction effects in the lower troposphere across the north wall of the gulf stream abstract significant atmospheric and oceanographic differences have often been observed in the regions lying on either side of the north wall of the gulf stream satellite visible range sensors have revealed changes in reflectivity across the gulf stream believed to be due to changes in sea state that are related to these atmospheric and oceanic differences in addition lines of low level cloud paralleling the edge of the gulf stream have been observed to persist in satellite imagery for several days at a time anomalous radar propagation also has been noted to occur in these same regions in an attempt to document the interrelation of these phenomena the lower atmosphere over the north wall of the gulf stream was studied on two separate occasions sea state photography and measurements of sea surface temperature air temperature dew point temperature and atmospheric pressure were made by an instrumented rp 3a aircraft flying at various altitudes from the gulf stream across the north wall and onto

holocene shoreline progradation and coastal evolution at guichen and rivoli bays southern australia prograded barrier systems record shoreline behaviour and palaeoenvironmental information the guichen bay holocene embayment fill succession in south australia has been subject to several prominent

quaternary aeolianites in south east australia a conceptual linkage between marine source and terrestrial deposition calcareous aeolianites are an integral part of many carbonate platforms and ramps such limestones are particularly common in heterozoan late cenozoic carbonate systems and it has been postulated that they could contain a particularly sensitive record of their offshore source this hypothesis is tested herein by documenting and interpreting part of the most extensive and temporally longest such system in the modern world the deposits are a combination of extraclasts and biofragments extraclasts are detrital quartz relict allochems older pleistocene particles and oligo miocene limestone clasts biofragments are penecontemporaneous coralline algae echinoderms small benthic foraminifera molluscs and bryozoans the aeolianites differ in composition from distant open shelf sediments because they contain more mollusc fragments and many fewer bryozoans this difference is interpreted to be due to i most sediment was derived from near shore seagrass meadows and macroalgal reefs ii all sediments were modified by hydrodynamics in near shore and beach environments and iii fragments of infaunal beach dwelling bivalves were added to the sediment at the strandline extraclasts should be expected in older pleistocene and cenozoic heterozoan deposits because the limestones are poorly lithified largely because of the lack of meteoric cementation and so easily eroded thus cool water aeolianites ought to contain more extraclasts than their warm water tropical cousins seagrasses in temperate environments are more productive than in the tropics and thus potentially might contribute many more particles to the beach and dunes than do tropical systems although particle breakage in the surf zone cannot be proven herein the abundance of whole benthic foraminifera and delicate bryozoans implies that suspension and flotsam shoreward transport was an essential process the similarity of pleistocene aeolianites over such a long time period herein suggests that the combination of postulated sedimentological biogenic and hydrodynamic processes could be universally important this article is protected by copyright all rights reserved

quantifying rates of coastal progradation from sediment volume using gpr and osl the holocene fill of guichen bay south east south australia guichen bay on the south east coast of south australia faces west towards the prevailing westerly winds of the southern ocean the bay is backed by a 4 km wide holocene beach ridge plain with more than 100 beach ridges the morphology of the guichen bay strandplain complex shows changes in the width length height and orientation of beach ridges a combination of geomorphological interpretation shallow geophysics and existing geochronology is used to interpret the holocene fill of guichen bay six sets of beach ridges are identified from the interpretation of orthorectified aerial photographs the ridge sets are distinguished on the basis of beach ridge orientation and continuity a 2 25 km ground penetrating radar gpr profile across the beach ridges reveals the sedimentary structures and stratigraphic units the beach ridges visible in the surface topography are a succession of stabilized foredunes that overlie progradational foreshore and upper shoreface sediments the beach progrades show multiple truncation surfaces interpreted as storm events the gpr profile shows that there are many more erosion surfaces in the subsurface than beach ridges on the surface the width and dip of preserved beach progrades imaged by gpr shows that the shoreface has steepened from around 2 9 to around 7 5 the changes in beach slope are attributed to increasing wave energy associated with beach progradation into deeper water as guichen bay was infilled at the same time the thickness of the preserved beach progrades increases slightly as the beach prograded into deeper water using the surface area of the ridge sets measured from the orthophotography and the average thickness of upper shoreface foreshore and coastal dune sands interpreted from the gpr profile the volume of holocene sediments within three of the six sets of beach ridge accretion has been calculated combining optically stimulated luminescence osl ages and volume calculations rates of sediment accumulation for ridge sets 3 4 and 5 have been estimated linear rates of beach ridge progradation appear to decrease in the mid holocene however the rates of sediment accumulation calculated from beach volumes have remained remarkably consistent through the mid to late holocene this suggests that sediment supply to the beach has been constant and that the decrease in the rate of progradation is due to increasing accommodation space as the beach progrades into deeper water changes in beach ridge morphology and orientation reflect environmental factors such as changes in wave climate and wind regime

evidence for sst forced anomalous winds revealed from simultaneous radiosonde launches from three ships across the kuroshio extension front abstractsimultaneous launches of radiosondes were conducted from three research vessels aligned meridionally across a sea surface temperature sst front on the flank of the kuroshio extension the soundings carried out every 2 h over 5 days in early july 2012 provided a unique opportunity in capturing unambiguous data on anomalous easterly winds derived from a pronounced meridional sst gradient the data indicate that a meridional contrast in surface heat fluxes from the underlying ocean enhanced the air temperature anomaly across the sst front which was observed from the surface up to 300 m altitude correspondingly high and low pressure anomalies that reached 800 m altitude formed on the north and south sides of the sst front respectively these temperature and pressure anomalies were maintained even during the passage of synoptic scale disturbances although the free tropospheric winds are overall westerly winds below the 1000 m level were easterly due to geostrophic anomalies driven by the northw

multiyear measurements of the oceanic and atmospheric boundary layers at the brazil malvinas confluence region 1 this study analyzes and discusses data taken from oceanic and atmospheric measurements performed simultaneously at the brazil malvinas confluence bmc region in the southwestern atlantic ocean this area is one of the most dynamical frontal regions of the world ocean data were collected during four research cruises in the region once a year in consecutive years between 2004 and 2007 very few studies have addressed the importance of studying the air sea coupling at the bmc region lateral temperature gradients at the study region were as high as 0 3 c km 1 at the surface and subsurface in the oceanic boundary layer the vertical temperature gradient reached 0 08 c m 1 at 500 m depth our results show that the marine atmospheric boundary layer mabl at the bmc region is modulated by the strong sea surface temperature sst gradients present at the sea surface the mean mabl structure is thicker over the warmside of the bmc where brazil current bc waters predominate the opposite occurs over the coldside of the confluence where waters from the malvinas falkland current mc are found the warmside of the confluence presented systematically higher mabl top height compared to the coldside this type of modulation at the synoptic scale is consistent to what happens in other frontal regions of the world ocean where the mabl adjusts itself to modifications along the sst gradients over warm waters at the bmc region the mabl static instability and turbulence were increased while winds at the lower portion of the mabl were strong over the coldside of the bc mc front an opposite behavior is found the mabl is thinner and more stable our results suggest that the sea level pressure slp was also modulated locally together with static stability vertical mixing mechanism by the surface condition during all cruises sst gradients at the bmc region modulate the synoptic atmospheric pressure gradient postfrontal and prefrontal conditions produce opposite thermal advections in the mabl that lead to different pressure intensification patterns across the confluence

the last interglacial shoreline in australia a review abstract marginal marine strata of last interglacial age occur in a range of morphostratigraphic settings around the australian coastline the lithofacies are similar to their holocene equivalents but are partly lithified elevated and laterally displaced inland uranium series ages for corals and molluscs from widely separated localities around the australian coastline are generally in accord with the accepted age for oxygen isotope substage 5e 125 000 10 000 bp the value generally accepted for the last interglacial maximum amino acid racemisation has principally been applied to correlation of sequences with benchmark sites dated by the uranium series method elevations of preserved last interglacial shorelines do not support the notion that australia is a stable continent significant neotectonic anomalies include cape cuvier 10 5 m fleurieu peninsula 6 m the coorong coastal plain 10 m and tasmania 32 m each indicating contrasting degrees of local uplift the tasmanian sequences are the highest occurrence on the australian continent and have been attributed to uplift as a result of mantle hotspot processes with the exception of these tectonically uplifted sites the height of the last interglacial sea surface around the australian coastline is consistently below the 6 m level globally attributed to this high sea level stand in australia the most consistent datum is from western eyre peninsula where a level 2 m above present mean sea level is ubiquitous the more southerly limit of coral growth and wider distribution of subtropical molluscan fauna are in accordance with warmer ocean waters during substage 5e approximately 2 c the extent of racemisation in molluscan fossils from southern australia also excludes the possibility of a more equable latitudinal distribution of mat during substage 5e

the last interglacial sea level change new evidence from the abrolhos islands west australia u series ages measured by thermal ionisation mass spectrometry tims are reported for a last interglacial li fossil coral core from the turtle bay houtman abrolhos islands western australia the core is 33 4 m long the top of which is approximately 5 m a p s l above present sea level from the232th concentrations and the reliability of the u series ages two sections in the core can be distinguished calculated u th ages in core section i 3 3 m a p s l to 11 m b p s l vary between 124 1 7 ka bp 3 3 m a p s l and 132 5 1 8 ka 4 m b p s l i e below present sea level and those of section ii 11 23 m b p s l between 140 3 and 214 5 ka bp respectively the ages of core section i are in almost perfect chronological order whereas for section ii no clear age depth relationship of the samples can be recognised further assessments based on the 234u t criteria reveal that none of the samples of core section ii give reliable ages whereas for core section i several samples can be considered to be moderately reliable within 2 ka the data of the turtle bay core complement and extend our previous work from the houtman abrolhos showing that the sea level reached a height of approximately 4 m b p s l at approximately 134 ka bp and a sea level highstand of at least 3 3 m a p s l at approximately 124 ka bp sea level dropped below its present position at approximately 116 ka bp although the new data are in general accord with the milankovitch theory of climate change a detailed comparison reveals considerable differences between the holocene and li sea level rise as monitored relative to the houtman abrolhos islands these observation apparently add further evidence to the growing set of data that the li sea level rise started earlier than recognised by specmap chronology a reconciliation of these contradictionary observations following the line of arguments presented by crowley 1994 are discussed with respect to the milankovitch theory

high precision u series dating of corals from western australia and implications for the timing and duration of the last interglacial abstract u series ages using methods of thermal ionisation mass spectrometry tims are reported for last interglacial fossil reefs along the stable coastal margin of western australia thorium isotope ratios were measured with superior precision using methods of charge collection high levels of precision in the measurement of both uranium and thorium isotopes has reduced the age uncertainty due to analytical errors excluding the uncertainty in the decay constants by a factor of four over the precisions reported by many earlier tims workers uncertainties in 234u t determined from both 230th 238u and 234u 238u are also significantly smaller than previously reported allowing samples which have undergone diagenetic exchange of uranium and thorium to be more easily identified strict criteria were adopted to screen the new western australian data reliable ages range from 127 to 122 ka published tims observations from other localities have been assessed using the same strict criteria when these are combined with glacio hydro isostatic sea level models they indicate that the last interglacial period occurred from at least 130 to 117 ka however these age constraints are largely determined from single data points and need to be verified with additional ages before considering them to be robust estimates for the timing of onset and termination of the last interglacial globally the main episode of reef growth appears to be confined to a narrow interval occurring from 127 to 122 ka in direct agreement with the narrow range in ages obtained from the western australian sites this may indicate that the last interglacial was of short duration extending from 127 to 122 ka only alternatively this interval may reflect a major reef building event in the middle of a longer duration 130 117 ka interglacial interval

midlatitude wind stress sea surface temperature coupling in the vicinity of oceanic fronts the influences of strong gradients in sea surface temperature on near surface cross front winds are explored in a series of idealized numerical modeling experiments the atmospheric model is the naval research laboratory coupled ocean atmosphere mesoscale prediction system coamps model which is fully coupled to the regional ocean modeling system roms ocean model a series of idealized two dimensional model calculations is carried out in which the wind blows from the warm to cold side or the cold to warm side of an initially prescribed ocean front the evolution of the near surface winds boundary layer and thermal structure is described and the balances in the momentum equation are diagnosed the changes in surface winds across the front are consistent with previous models and observations showing a strong positive correlation with the sea surface temperature and boundary layer thickness the coupling arises mainly as a result of changes in the flux richardson number across the front and the strength of the coupling coefficient grows quadratically with the strength of the cross front geostrophic wind the acceleration of the winds over warm water results primarily from the rapid change in turbulent mixing and the resulting unbalanced coriolis force in the vicinity of the front much of the loss gain of momentum perpendicular to the front in the upper and lower boundary layer results from acceleration deceleration of the flow parallel to the front via the coriolis term this mechanism is different from the previously suggested processes of downward mixing of momentum and adjustment to the horizontal pressure gradient and is active for flows off the equator with sufficiently strong winds although the main focus of this work is on the midlatitude strong wind regime calculations at low latitudes and with weak winds show that the pressure gradient and turbulent mixing terms dominate the cross front momentum budget consistent with previous work

mesoscale wind stress sst coupled perturbations in the kuroshio extension abstract mesoscale perturbations of wind stress ms and sea surface temperature sstms in the kuroshio extension ke are analyzed using long term high resolution satellite observations mesoscale wind stress and sst perturbations are first extracted using a locally weighted regression loess method and then analyzed using statistical methods including linear regression singular value decomposition svd and the inverse method the coupling coefficient between mesoscale wind stress magnitude ms and sstms and those between mesoscale wind stress divergence curl and downwind crosswind sst gradients exhibit distinct seasonal variability with large values in winter and small values in summer consistent with previous studies the three leading svd modes for ms and sstms show highly consistent variability in both spatial patterns and temporal expansion coefficients and the temporal expansion coefficients exhibit distinct seasonal and interannual variability these modes are associated with inherent seasonal variability of ms and sstms and interannual variability of the ke jet dynamic state based on the observed coupling relationships between wind stress divergence curl and downwind crosswind sst gradients an empirical model for mesoscale wind stress vector perturbations x y ms f sst is established this model solves x y ms from their divergence and curl estimated from sst gradient data using an inverse method this newly established x y ms f sst model produces reasonably consistent solutions compared to the one established based on the empirical relationship between ms and sstms furthermore this model could separate divergence only and curl only wind stress perturbations to study their respective effects and thus is promising and will contribute to ocean dynamic analyses

first recorded evidence of subaqueously deposited late pleistocene interstadial mis 5c coastal strata above present sea level in australia abstract significant differences in the elevation of late pleistocene interstadial coastal strata have been noted at the global scale resulting from the combined effects of tectonism proximity of field sites to pleistocene ice sheets and the variable effects of glacio hydro isostatic adjustment processes here we report the first recorded example of subaqueously deposited late pleistocene interstadial coastal sediments above present sea level in australia in a far field location to pleistocene ice sheets and characterised by minimal to modest rates of vertical crustal movements located at port macdonnell in southern australia the sedimentary succession is represented by a flint conglomerate beach facies with interstratified shells an optically stimulated luminescence osl age of 53 4 ka for an aeolianite unit that unconformably overlies the shelly deposit indicates that the beach facies is older than early mis 3 osl analysis also confirms that the macdonnell range located 7 km inland from the present coastline is of last interglacial age 124 10 ka mis 5e radiocarbon dating on the operculum of turbo undulatus from the shelly conglomerate yielded a minimum age of 47 905 2106 yr bp wk 34733 the extent of amino acid racemization aar for turbo sp from the shelly unit beneath the aeolianite suggests an interstadial age 102 16 ka uplift corrected palaeo sea level at the time of deposition of the shelly flint conglomerate was at least 14 m during mis 5c these results are consistent with palaeo sea level estimates from other far field settings as well as oxygen isotope inferred sea levels for this interval and further highlight the regional tectonic stability of australian coastal landscapes in a global context

holocene tephra succession of puyehue cordon caulle and antillanca casablanca volcanic complexes southern andes 40 41 s abstract puyehue cordon caulle and antillanca volcanic complexes are two of at least 50 active frontal arc volcanoes that define the 1400 km long southern volcanic zone of chile holocene tephra deposits in chile and argentina 40 41 s up to 100 km east of these volcanoes comprise at least five voluminous 1 to 8 km 3 pyroclastic fall layers that preceded several recently deposited cordon caulle pumice fallouts field observations of proximal medium and distal facies of the deposits in conjunction with geochronology and geochemistry of the volcanic complexes indicate that three fall layers are derived from puyehue volcano puyehue 1 and 2 and mil hojas whereas two are sourced from the antillanca complex playas blanca negra and nahuel huapi tephra 20 km to the south the oldest tephra calibrated 14 c age 10 49 0 12 ka 2 found only at medium distal facies is deposited directly on granitic moraine boulders and consists of deeply weathered orange dacitic pumice lapilli the next prominent tephra at 7 ka comprises dacitic pumice and its age is equivalent to a rhyodacitic dome exposed in the puyehue summit crater above these deposits there are phases of a complex eruption consisting of a conspicuous compositionally zoned tephra it also comprises a pyroclastic density current together with lithic rich and scoriaceous fallout deposits mineralogical geochemical and sr isotope evidence plus the isopach maps confirm that this sequence of eruptive events is sourced from antillanca at 1932 68 yrbp the total volume of this eruptive sequence exceeds 8 km 3 making it the largest holocene eruption from either volcanic complex this eruption was likely responsible for the destruction of an ancestral antillanca volcano and the formation of a 4 5 km diameter caldera a distinctive younger unit in the region is a voluminous rhyodacitic pumice fall calibrated 14 c age 1 11 0 07 ka above which a series of several alternating dark lithic and pumice lapilli beds accumulated correlation with proximal deposits indicates that the 1 11 ka eruption was derived from puyehue and destroyed 3 km 3 of rhyodacitic domes at this volcano summit historic explosive activity at the nascent casablanca volcano and along cordon caulle including the 2011 2012 eruption 1 km 3 of uncompacted pumice the largest from this fissural zone emphasizes an increased risk for volcanic hazards in central chile and argentina

bypassing and diachronous deposition from density currents evidence from a giant regressive bed form in the poris ignimbrite tenerife canary islands exceptional longitudinal exposure through an ignimbrite sheet on the southern flanks of las canadas volcano tenerife canary islands reveals a giant regressive bed form 520 m long it comprises sourceward dipping diffuse lenses 50 m long of massive and diffuse bedded lapilli tuff its architectural relationships indicate that at any one moment in time deposition was restricted to an 50 m long longitudinal depositional zone bounded both upslope and downslope by extensive bypassing zones the regressive architecture shows that the zone of deposition gradually migrated sourceward as the current passed nonpersistent scours indicate that the current was locally and momentarily erosive although at many locations there is little evidence for substantial erosion or deposition and most of the pyroclastic load seems to have entirely bypassed subaerial slopes to enter the atlantic ocean 20 km from the source the ignimbrite is diachronous and any single vertical section through it represents only a short phase of the current9s protracted depositional history similarly protracted and complex flow histories elsewhere may be easily overlooked at typical field exposures of ignimbrites turbidites and lahar deposits leading to significantly underestimated flow durations and volumes

rapid coastal geomorphic change in the river murray estuary of australia abstract the river murray estuary a ramsar wetland site has experienced considerable rapid coastal change during the quaternary the interplay of aeolian processes river flows tidal oscillations wave action and variations in relative sea level due to global sea level changes and land subsidence provides the energy for the ongoing dynamism often accelerated by human impacts the estuary is the terminus of the murray darling catchment which covers 1 073 million km 2 of the australian continent terminal lakes alexandrina albert and the coorong lagoon are holocene features occupying tectonically subsiding quaternary interdune areas they formed in response to eustatic sea level rise following the last glacial maximum ca 20 ka the last interglacial shoreline 125 000 yr bp parallels the modern shoreline several kilometres inland dislocation of the last interglacial shoreline demonstrates ongoing tectonic subsidence as does historical seismic activity the northern half of hindmarsh island formed during last interglacial times when it was the sink for dominant longshore transport from the southeast which pushed the river murray westward partly explaining the large bend in the river murray at goolwa the modern coastal barriers of sir richard peninsula and younghusband peninsula formed from 7000 yr ago following glacier melt and sea level rise subsequently the barriers have migrated landward sporadically exposing lagoonal sediments on the ocean beaches differential loading of the soft lagoonal sediments by advancing dunes possibly in conjunction with seismic events has deformed and elevated them to up to 10 m above present sea level apsl during the mid holocene an extensive sand flat with associated dunes formed immediately inland of the coastal barrier at least six generations of late pleistocene dune systems occur in the region for example during last glacial times the climate was drier colder and windier than at present and a system of parallel west east trending yellow red desert dunes developed around the lakes aeolian processes remain important with occasionally up to 5000 tonnes of sand being in motion along 10 km of the modern shoreline during mouth migration dunes up to 2 m high have been formed and vegetated in 12 months directly inland from the mouth and replicating the formation of older dunes on hindmarsh island elsewhere sand blown directly from the barrier system infills channels barrage construction on the beach facies of the last interglacial shoreline transformed the estuary into freshwater lakes with permanently raised water levels and reduced the tidal prism by 90 increased deposition upstream and downstream accompanied barrage construction as have accelerated lakeshore erosion and the growth and consolidation of the flood tidal delta bird island these human accelerated changes provide rapidly formed analogues of older quaternary features and aid their interpretation the shape and location of the murray mouth is constantly changing migrating over 1 6 km since the 1830s migrations of up to 6 km over the past 3000 yr have influenced sedimentation on the landward shore of the back barrier lagoonal system

gas and aerosol emissions from villarrica volcano chile here we report results from a multidisciplinary field campaign at villarrica volcano chile in march 2009 a range of direct sampling and remote sensing techniques was employed to assess gas and aerosol emissions from the volcano and extend the time series of measurements that have been made during recent years airborne traverses beneath the plume with an ultraviolet spectrometer yielded an average so2 flux of 3 7 kg s 1 this value is similar to previous measurements made at villarrica during periods of quiescent activity the composition of the plume was measured at the crater rim using electrochemical sensors and for the first time open path fourier transform infrared spectroscopy yielding a composition of 90 5 mol h2o 5 7 co2 2 6 so2 0 9 hcl 0 3 hf and 0 01 h2s comparison with previous gas measurements made between 2000 and 2004 shows a correlation between increased so2 hcl ratios and periods of increased activity base treated filter packs were also employed during our campaign yielding molar ratios of hbr so2 1 1 10 4 hi so2 1 4 10 5 and hno3 so2 1 1 10 3 in the gas phase our data represent the most comprehensive gas inventory at villarrica to date and the first evaluation of hbr and hi emissions from a south american volcano sun photometry of the plume showed the near source aerosol size distributions were bimodal with maxima at 0 1 and 1 m these findings are consistent with results from analyses in 2003 electron microscope analysis of particulate matter collected on filters showed an abundance of spherical micron sized particles that are rich in si mg and al non spherical s rich particles were also observed

atmospheric boundary layer adjustment to the synoptic cycle at the brazil malvinas confluence south atlantic ocean 1 this study analyzes and discusses atmospheric boundary layer vertical profiles of potential temperature specific humidity and wind speed at each of the sides of the brazil malvinas confluence in the southwestern atlantic ocean such confluence is characterized by the meeting of water masses with very different characteristics the southern waters of the malvinas current can be several degrees colder and appreciably less salty than the northern brazil current waters at the same time a synoptic cycle can be identified at the region marked by the successive passages of frontal systems and extratropical cyclones the different phases of the synoptic cycle lead to different thermal advections at the confluence causing respective different patterns of atmospheric boundary layer adjustment to the surface heterogeneity induced by the confluence in the present study this adjustment along the synoptic cycle is analyzed using data from five experiments performed across the confluence from 2003 to 2008 in each of the campaigns a number of soundings were launched from a ship at both sides of the confluence a climatological analysis with respect to the closest frontal passage is presented and it suggests that the observations collected at each of the years analyzed are referent to a different day of the synoptic cycle the average profiles at each side of the confluence are in agreement with previous modeling studies of warm and cold thermal advection patterns over an oceanic front furthermore our study shows that peculiar transitional characteristics are also observed between the conditions of well established warm and cold advection at many phases of the synoptic cycle a strongly stratified boundary layer occurs at one or both sides of the confluence some of the observed characteristics such as a large moisture accumulation near the surface suggest that existing sensible and latent heat fluxes parameterizations fail under very strong stratifications and the consequences of this deficiency are analyzed

the distribution of carbonate eolianite abstract carbonate eolianite forms distinctive coastal landforms on many mid latitude continents and islands numerous studies of extensive continental and smaller island deposits in both hemispheres have shown the eolianites are predominantly pleistocene in age the coorong coastal plain of south australia contains the world s longest record of eolianite deposition revealing that major phases of carbonate accumulation occurred during interglacial and some interstadial sea level highstands throughout the quaternary similarly the well studied eolianite islands of bermuda and the bahamas record a close match between dune accretion and sea level highstands since the middle pleistocene several other eolianite deposits appear to have formed at least partially during glacial periods the glacial age deposits are eolian reworked relict shelf or coastal sediments or remnants of former highly mobile coastal dunes sourced from low sea level shorelines the distribution and bioclastic composition of large scale eolianite deposits suggests carbonate production on shallow shelves and banks is the ultimate control on the formation of eolianite the bulk of the carbonate comprising those eolianites is heterozoan being produced where there is low terrigenous sediment input in dominantly temperate cool water and subtropical carbonate provinces quaternary cyclical movements of sea level have also controlled the form and rate of coastal carbonate deposition with repeated pulses of sedimentation during highstands forming laterally coalesced vertically stacked or composite dune successions major unconformities within the deposits are marked by paleosols which record hiatuses in coastal sedimentation in several regions major eolianite units overlie coastal deposits of terrigenous sediment those successions suggest that the trend towards aridity and reduction in the supply of terrigenous sediment to shelves during the quaternary has enhanced the production of carbonate and the deposition of eolianite

role of the gulf stream and kuroshio oyashio systems in large scale atmosphere ocean interaction a review abstract ocean atmosphere interaction over the northern hemisphere western boundary current wbc regions i e the gulf stream kuroshio oyashio and their extensions is reviewed with an emphasis on their role in basin scale climate variability sst anomalies exhibit considerable variance on interannual to decadal time scales in these regions low frequency sst variability is primarily driven by basin scale wind stress curl variability via the oceanic rossby wave adjustment of the gyre scale circulation that modulates the latitude and strength of the wbc related oceanic fronts rectification of the variability by mesoscale eddies reemergence of the anomalies from the preceding winter and tropical remote forcing also play important roles in driving and maintaining the low frequency variability in these regions in the gulf stream region interaction with the deep western boundary current also likely influences the low frequency variability surface heat fluxes damp the low frequency sst anomalies ove

pleistocene coastal stratigraphy sea level highstands and neotectonism of the southern australian passive continental margin a review located in a tectonically stable intraplate setting and in the far field of former ice sheets the southern australian passive continental margin represents a globally important region for quantifying sea level during pleistocene highstands the stratigraphical record of the southern australian margin is dominated by geographically extensive coastal barrier estuarine and peritidal landforms of bioclastic temperate carbonate affinity a function of regional aridity siliciclastic successions dominate the eastern australian coastline despite the generally high level of tectonic stability regional contrasts are evident in the elevation of pleistocene shoreline deposits that largely relate to pre quaternary geotectonic setting the most complete record of pleistocene highstand deposits occurs in the murray basin coorong coastal plain region and indicates that interglacial sea level highstands for at least the past 11 interglacials did not deviate by more than 6 m from present sea level the pleistocene marginal marine record of southern australia is dominantly represented by coastal successions deposited during marine oxygen isotope stages 5e and 7 equating with relative sea level maxima of 2 6 m and greater than 1 m above present sea level apsl respectively intertidal facies of late pleistocene interstadial successions rarely occur above present sea level the most reliable record of glacio eustatic ice equivalent sea level is registered on coastlines developed on stable precambrian cratons such as the gawler craton eyre peninsula where a consistent elevation of 2 m apsl is registered for over 500 km for the last interglacial shoreline 125 ka copyright 2002 john wiley sons ltd

west coast dune plumes climate driven contrasts in dunefield morphogenesis along the western and southern south african coasts abstract this study examines two major late quaternary coastal dune systems situated in the southwestern most extremity of africa the false bay and duinefontyn dune plumes formed in close proximity but under contrasting oceanographic regimes warm agulhas and cold benguela oceanic current systems respectively the false bay and duinefontyn dune plumes have hitherto lacked the objective numerical chronology required to realize their full potential in unraveling the complex palaeo oceanographic and palaeoclimatic history of the region here we present a dual amino acid racemizationn aar and optically stimulated luminescence osl chronological framework from the extensive three dimensional exposures in sea cliffs at false bay three generations of dune deposition corresponding with orbitally forced climatic sea level cycles mis 7 mis 5 and holocene were resolved whereas the duinefontyn plume is dominated by mis 5 and holocene sedimentation at false bay and duinefontyn glacial periods are marked by the development of mature palaeosols confirming the link between glacio eustacy and dune deposition determined previously on the west and southern coasts of south africa along the west coast dune plumes typify dunefield morphology whereas shoreline parallel dune cordons are commonly developed on the southern coast these regional variations in dune system morphogenesis are largely controlled by contrasting wind and rainfall patterns the attenuated dimensions of the mis 5 plumes at false bay and duinefontyn may indicate a weakening of the south atlantic anticyclone during the last interglacial at false bay stone artifacts illustrate a human presence in the region during mis 7

syn depositional substrate deformation produced by the shear force of a pyroclastic density current an example from the pleistocene ignimbrite at monte cimino northern lazio italy substrate deformation by pyroclastic density currents is very sparsely described in the literature the rare occurrence of syn depositional substrate deformation suggests that special circumstances are required to transmit shear from the base of a pyroclastic density current into the deposited ignimbrite and the substrate one example of a substrate deformed by a pyroclastic density current is found at the base of the pleistocene ignimbrite at monte cimino central italy a series of reverse faults that offsets the basal contact were produced by the shear force of the pyroclastic current during deposition of the ignimbrite the faults formed on the vent facing side of a palaeo slope that strikes sub parallel to the flow direction of the pyroclastic current fault offsets suggest motion was parallel to the flow direction of the pyroclastic current rather than down slope we propose that these faults resulted from fluctuations in the shear force of the pyroclastic density current as it was channelled down a palaeovalley the lower flow boundary which separated the deposited ignimbrite and the substrate from the moving pyroclastic density current momentarily stepped down into the substrate so that the upper 0 5 m of the substrate and about 1 5 m of the deposited ignimbrite became incorporated into the current this momentary coupling of the current and the substrate induced reverse faulting in the substrate and the deposited portion of the ignimbrite deposition appears to have been ongoing during the formation of these faults as well as afterward following the formation of the faults the lower flow boundary seems to have been quickly re established above the faults approximately 1 5 m above the base of the ignimbrite allowing deposition to continue without further deformation of the substrate

how long and how stable was the last interglacial abstract surface ocean indicators in the north atlantic during marine isotope stage mis 5 correlate closely with the vegetational succession in northeastern france the melisey i silty layer which marks the end of the last interglacial biozone in la grande pile pollen record appears coeval with the polar front advance c24 registered in the core v29 191 by a sharply increased presence of ice rafted detritus and the cold water foraminifer neogloboquadrina pachyderma sinistral since this event is younger than the peak of mis 5d the last interglacial as recognized in northern france correlates not only with the mis 5e but also with a substantial part of mis 5d the last interglacial in la grande pile was twice as long as the holocene and the climate in its first half was apparently not less stable than during the current interglacial if the future natural climates were to develop as analogs of the past then the onset of the next glacial environments on land would be still many millennia ahead

the stranded beach dune sequence of south east south australia a test of thermoluminescence dating 0 800 ka the remarkable sequence of stranded beach dunes in south east south australia deposited during the past 800 ka has provided us with a rare set of samples for testing thermoluminescence sediment dating methods here we report thermoluminescence ages obtained from quartz separated from the dunes and compare them with accepted ages for the high sea levels responsible for the dunes the independent ages of the dunes were obtained from earlier work by schwebel which has been extended and refined by modelling the dune formation using sea level variations derived from the oceanic 18o record the work is unusual in extending thermoluminescence dating to an 800 ka sequence with modest geological control of the age the agreement between thermoluminescence and geological ages is satisfactory for eight dunes with ages in the range 120 800 ka quartz is not usually thought to be useful for thermoluminescence dating in this time span two factors contribute to our success the first is that the dose rates are low about 0 5 gy ka 1 or one quarter of that typical of sediments the second is that the thermoluminescence vs dose response continues to rise monotonically above the saturation region at doses above 300 gy

barometric pressure variations associated with eastern pacific tropical instability waves abstract barometric pressure surface temperature and wind time series in the eastern equatorial pacific are analyzed to determine if oceanic tropical instability wave tiw sea surface temperature variations cause barometric pressure gradients large enough to influence the atmospheric boundary layer during the study period from april 2001 to september 2002 11 tiws propagated westward past 110 w causing a spectral peak at 20 30 days in the sea surface temperature sst meridional difference between 2 n 110 w and 0 110 w likewise the meridional pressure difference also had a spectral peak in the 20 30 day tiw band cross spectral analysis shows that within the tiw band sst induced pressure variations were roughly 0 1 hpa c 1 in magnitude the resulting pressure gradient force is comparable in magnitude to other terms in the meridional momentum balance implications about the role of the boundary layer capping in the adjustment to sst forcing are discussed

the holocene pucon eruption of volcan villarrica chile deposit architecture and eruption chronology the pucon eruption was the largest holocene explosive outburst of volcan villarrica chile it discharged 1 0 km3 of basaltic andesite magma and 0 8 km3 of pre existing rock forming a thin scoria fall deposit overlain by voluminous ignimbrite intercalated with pyroclastic surge beds the deposits are up to 70 m thick and are preserved up to 21 km from the present day summit post eruptive lahar deposits extending farther two ignimbrite units are distinguished a lower one p1 in which all accidental lithic clasts are of volcanic origin and an upper unit p2 in which basement granitoids also occur both as free clasts and as xenoliths in scoria p2 accounts for 80 of the erupted products following the initial scoria fallout phase p1 pyroclastic flows swept down the northern and western flanks of the volcano magma fragmentation during this phase being confined to within the volcanic edifice following a pause of at least a couple of days sufficient for wood devolatilization eruption recommenced the fragmentation level dropped to within the granitoid basement and the pyroclastic flows of p2 were erupted the first p2 flow had a highly turbulent front laid down ignimbrite with large scale cross stratification and regressive bedforms and sheared the ground flow then waned and became confined to the southeastern flank following emplacement of pyroclastic surge deposits all across the volcano the eruption terminated with pyroclastic flows down the northern flank multiple lahars were generated prior to the onset of a new eruptive cycle charcoal samples yield a probable eruption age of 3 510 60 14c years bp

oxygen isotopes sea level changes and the temperature history of a coral reef environment in new guinea over the last 105 years abstract coral reef terraces consisting of an upward succession of fringing and barrier reef types are preserved on land along the raising coast of huon peninsula new guinea seven coral reef units i vii from the coast landwards spaced at about 20 kyr interval provide a rather complete record of sea levels oxygen isotopes and temperature of teh surface tropical ocean over the duration of the high sea level events of the last glacial cycle the systematic sampling of the coral reefs was restricted to the massive tridacna gigas species the giant clam which are about 0 7 0 enriched in 18o relative to calcite equilibrium value and the presence of symbionts seems to have no effect on the 18o of their aragonitic skeleton sea levels rose rapidly to 5 6 5 m above present during the last interglacial which on stratigraphic grounds and 18o compositions can be separated into an early phase whose 18o is similar to modern reef viia dated at 138 kyr and a late phase that is 0 6 0 heavier reef viib dated at 118 kyr fringing reefs vi v iv iii and ii record short lived high sea levels stands at 107 85 60 45 to 40 and 31 kyr respectively that stopped short of the present sea level 12 19 28 32 to 42 m the general decline of the high sea level stands corresponds to an average 18o enrichment of 1 7 0 measured between the early interstadials of isotope stage 5 vi and v and the late interstadials of isotope stage 3 iv iiia iiib and ii the maximum 18o enrichment of 1 7 0 relative to present was registered during a regressive phase of reef iiia stratigraphic evidence indicates that sea level lows in the range of 37 to 55 m below present have occurred in between the high sea level stands but those are unlikely to represent the lowest sea levels of the last glacial cycle sea levels and 18o ddta pair offer important clues regarding the partitioning of ice volume and temperature in 18o records the results suggest that the ice volume effect accounts for the observed 18o changes during the early interstadial culminations but only for 29 46 during the late interstadial culminations sea water cooling beyond the threshold limit of coral reef growth 18 c did not occur during the last glacial cycle the temperature of the surface tropical ocean was similar to present during the early interstadials of isotope stage 5 and cooler by 3 c below present during the later interstadials of isotope stage 3

air sea heat exchanges characteristic of a prominent midlatitude oceanic front in the south indian ocean as simulated in a high resolution coupled gcm abstract an integration of a high resolution coupled general circulation model whose ocean component is eddy permitting and thus able to reproduce a sharp gradient in sea surface temperature sst is analyzed to investigate air sea heat exchanges characteristic of the midlatitude oceanic frontal zone the focus of this paper is placed on a prominent sst front in the south indian ocean which is collocated with the core of the southern hemisphere storm track time mean distribution of sensible heat flux is characterized by a distinct cross frontal contrast it is upward and downward on the warmer and cooler flanks respectively of the sst front acting to maintain the sharp gradient of surface air temperature sat that is important for preconditioning the environment for the recurrent development of storms and thereby anchoring the storm track induced by cross frontal advection of cold warm air associated with migratory atmospheric disturbances the surface flux is highly variable with intermittent en

ocean frontal effects on the vertical development of clouds over the western north pacific in situ and satellite observations abstract a suite of shipboard and satellite observations are analyzed and synthesized to investigate the three dimensional structure of clouds and influences from sea surface temperature fronts over the western north pacific sharp transitions are observed across the kuroshio extension ke front in the marine atmospheric boundary layer mabl and its clouds the ocean s influence appears to extend beyond the mabl with higher cloud tops in altitude along the ke front than the surroundings in winter intense turbulent heat release from the ocean takes place on the southern flank of the ke front where the cloud top penetrates above the mabl and reaches the midtroposphere in this band of high cloud tops frequent lightning activity is observed the results of this study suggest a sea level pressure mechanism for which the temperature gradient in the mabl induces strong surface wind convergence on the southern flank of the ke front deepening the clouds there in early summer sea fog frequently occurs on

the evolution of chabahar beach ridge system in se iran in response to holocene relative sea level changes abstract the chabahar strandplain chs stretches along the chabahar bay at a width of more than 5 km along the northern coast of the gulf of oman and se iran an area that has been subjected to tectonic uplift as a part of the makran accretionary prism the chs comprises of beach ridges inter ridge swales sand dunes tidal channels and fluvial deposits we present the first documentation of the spatial distribution and the internal architecture of the chs based on topographic surveys sediment percussive coring trenching and ground penetrating radar gpr transects radiocarbon dating on marine shells from foreshore deposits of 8 representative beach ridges yielded ages between 4800 and 270 cal years bp at respective distances of 4800 to 670 m from the present shoreline we interpret the boundary between the foreshore beach and the foredune deposits as indicator of past sea levels by analogy to present shore processes this boundary is readily recognizable in sediment profiles from cores and trenches as well as gpr reflectors based on the age model and depositional features we estimate relative sea level fall of up to 15 m over the past 4800 years considering that the eustatic sea level changes for this period are negligible for the makran coast this relative sea level fall is related to tectonic uplift across the coastal makran the elevation of palaeo shorelines with similar ages decrease from east to west of the chs which suggest that alongshore variations in uplift rates are likely related to different movements of coastal fault blocks

high precision u series dating of last interglacial events by mass spectrometry houtman abrolhos islands western australia the houtman abrolhos islands situated at the western passive margin of the australian continent consist of a series of shelf edge coral reefs the central platforms of the reefs are late pleistocene in age and are generally some 3 5 m above present sea level the uppermost part of the last interglacial reefs normally has an upward shallowing sequence consisting of coral framestone coralline algal bindstone and skeletal grainstone to rudstone this sequence represents deposition in water depths of less than 2 m and provides a good indicator of sea level high precision mass spectrometric dates of corals from the abrolhos reefs including dates obtained from drill cores arological isotopic and stratigraphic criteria are established for the selection of suitable samples for dating and for assessing the reliability of dates using the screened dates and the stratigraphic evidence the timing and character of the sea level variations of the last interglacial in the abrolhos region are examined the data show that sea level of the last interglacial in the abrolhos was 4 m below its present height by ca 134 ka bp and probably reached about 2 m above present height at ca 133 ka bp the exact time at which sea level reached its peak 6 m above present sea level cannot be determined from our data but it is clear that the sea level high stand of the last interglacial lasted until ca 116 ka bp and that for much of the last interglacial sea level at the abrolhos was at a height of about 4 m above its present level

duration and structure of the past four interglaciations reanalysis and additional dating of the devils hole 18o paleotemperature record confirm that the last interglaciation in the great basin the continental analog of marine isotopic substage 5e lasted 22 000 yr consistent with the vostok paleotemperature record which suggests a duration of 19 000 yr for this event in antarctica the three preceding interglaciations in the devils hole record analogs of marine isotopic substages 7e 9c and 11c range from 20 000 to 26 000 yr in duration a 20 000 yr duration for the last interglaciation is consistent with tims uranium series dated sea level high stands thus the widely held view that interglaciations were of 11 000 to 13 000 yr duration and constituted only about 10 of mid to late pleistocene climatic cycles needs reexamination the warmest portion of each interglaciation in the devils hole time series is marked by a 18o plateau signifying apparent climatic stability for periods of 10 000 to 15 000 yr duration

interglacial glacial climatic signatures preserved in a regressive coastal barrier southeastern australia abstract regressive barriers persisting in the landscape over interglacial glacial cycles are important repositories of paleoclimatic signatures such as past sea level and regional aridity the gippsland region of victoria contains a multi barrier system formed during past interglacial glacial cycles and the late holocene an extensive series of parallel foredune ridges forming the elongate inner barrier was sampled for luminescence dating with ages indicating deposition ca 125 000 108 000 years ago coinciding with the later phase of the last interglacial lig marine isotope stage mis 5e and the transition to mis 5d ground penetrating radar gpr imaged beach face reflectors within the lig barrier indicate that sea level was within 2 to 3 m of present level during mis 5e in this far field location significant reworking of the barrier system through blowout and parabolic dune activity occurred between 23 000 18 000 years ago corresponding to the last glacial maximum lgm with an estimated 160 000 000 m3 of coastal sediments eroded and redistributed the morphological changes to this coastal barrier over the most recent interglacial glacial cycle mis 5e to present also imply significant landscape instability during the lgm in southeastern australia and are further evidence for extension of the geographical range and intensity of aridity at this time

on the role of sea surface temperature gradients in forcing low level winds and convergence in the tropics abstract we examine the importance of pressure gradients due to surface temperature gradients to low level p 700 mb flow and convergence in the tropics over time scales 1 month the latter plays a crucial role in determining the distribution of cumulonimbus convection and rainfall our approach is to consider a simple one layer model of the trade cumulus boundary layer wherein surface temperature gradients are mixed vertically consistent with ecmwf analyzed data the top of the layer is taken at 700 mb the influence from higher levels is intentionally suppressed by setting horizontal pressure gradients and frictional stresses to zero at the top of the layer horizontal convergence within the layer is taken up by cumulonimbus mass flux however the development of the cumulonimbus mass flux is associated with a short relaxation time o hr roughly the development time for such convection during this short time horizontal convergence acts to redistribute mass so as to reduce horizontal pressur

the evolution of coastal barrier systems a case study of the middle late pleistocene wilderness barriers south africa abstract barrier systems contain lengthy but complex records of long term environmental fluctuations the wilderness embayment south africa contains a system of shore parallel barriers reaching up to 200 m above modern sea level this study reports the results of chronological topographical both on and off shore sedimentological and micromorphological analyses within the wilderness embayment sixty one new luminescence ages from sixteen sites in unconsolidated dunes and three separate barriers are presented which when combined with previously published luminescence ages from the area provide a high resolution chronological framework for the emplacement and evolution of the barrier system the preserved barriers have been constructed within at least the last two glacial interglacial cycles with notable phases between 241 221 ka 159 143 ka 130 120 ka 92 87 ka and post 6 ka multiple phases of barrier construction occurred during sea level highstands with sediment deposition on each individual barrier occurring over at least two interglacials holocene evolution of the system sheds light on earlier events with dune preservation occurring only during early regression from the mid holocene highstand tectonic stability at wilderness allowed glacio eustatically formed shorelines to occupy similar positions on multiple occasions this in conjunction with a relatively humid climate and a well vegetated landscape enabled deflated sediment from beaches to form dunes which stacked upon each other to form an extensive and complex vertical accretionary sequence repeated erosion and recycling of pre existing barriers as well as barrier construction on what is currently the off shore platform during still stands in sea level regressional cycles when sea levels dropped below ca 50 m from the present day has added to the complexity of the preserved terrestrial barrier record the wilderness barrier system contrasts with barriers developed elsewhere in the world where higher rates of crustal uplift have allowed preservation of a more complete and more widely spaced palaeorecord this research also shows the utility of integrating off shore topography as revealed by bathymetry with terrestrial topographic data for the better understanding of the evolution of palaeo coastlines and the preserved dune record found on present day coastal plains local variation in the topography of the continental shelf at wilderness has generated spatial and temporal complexity within the sedimentary records of individual barriers as well as having a significant influence on preservation

quaternary sea level history and the origin of the northernmost coastal aeolianites in the americas channel islands national park california usa abstract along most of the pacific coast of north america sand dunes are dominantly silicate rich on the california channel islands however dunes are carbonate rich due to high productivity offshore and a lack of dilution by silicate minerals older sands on the channel islands contain enough carbonate to be cemented into aeolianite several generations of carbonate aeolianites are present on the california channel islands and represent the northernmost quaternary coastal aeolianites on the pacific coast of north america the oldest aeolianites on the islands may date to the early pleistocene and thus far have only been found on santa cruz island aeolianites with well developed soils are found on both san miguel island and santa rosa island and likely date to the middle pleistocene the youngest and best dated aeolianites are located on san miguel island and santa rosa island these sediments were deposited during the late pleistocene following the emergence of marine terraces that date to the last interglacial complex 120 000 yr to 80 000 yr based on radiocarbon and luminescence dating the ages of these units correspond in time with marine isotope stages mis 4 3 and 2 sea level was significantly lower than present during all three time periods reconstruction of insular paleogeography indicates that large areas to the north and northwest of the islands would have been exposed at these times providing a ready source of carbonate rich skeletal sands these findings differ from a previously held concept that carbonate aeolianites are dominantly an interglacial phenomenon forming during high stands of sea in contrast our results are consistent with the findings of other investigators of the past decade who have reported evidence of glacial age and interstadial age aeolianites on coastlines of australia and south africa they are also consistent with observations made by darwin regarding the origin of aeolianites on the island of st helena in the south atlantic ocean more than a century and a half ago

the influence of sea surface temperature on surface wind in the eastern equatorial pacific seasonal and interannual variability abstract the climate of the eastern pacific exhibits a pronounced equatorial asymmetry boundary layer air originating in the southern hemisphere trades crosses the equator and flows into the intertropical convergence zone itcz whose southern limit is nearly always located at least 4 to the north of the equator the sea surface temperature sst distribution is characterized by a prominent cold tongue centered 1 s a strong frontal zone centered 2 n and a warm eastward current centered near 5 n the surface wind field exhibits a pronounced horizontal divergence as the air flows northward across the oceanic frontal zone these features vary in strength in response to the annual cycle and the el nino southern oscillation phenomenon the northward cross equatorial surface winds the cold tongue and the frontal zone all tend to be strongest during the cold season july through november during the cold season of the coldest years when the cold tongue is most prominent the cross equatorial flow t

sea breeze like winds across the north wall of the gulf stream an analytical model sea breeze like winds have been observed on the warmer side of the gulf stream when synopticscale winds blow from cool shelf water toward a warm water surface sweet et al 1981 it is shown that a simple thermally driven analytical model can explain satisfactorily the increase in wind speed from the cold to the warmer water side as resulting from horizontal temperature gradient across the gulf stream

coastal aminostratigraphy of the last interglaciation in southern australia abstract amino acid racemization data for marine molluscs of the last interglaciation from southern australia provide the basis for a predictive model for relative dating of late quaternary sequences genera analyzed include anadara sp katelysia sp glycymeris sp and fulvia sp that exhibit moderate racemization rates a genus effect on racemization is not evident in these taxa coefficients of variation for intershell d l ratio variation for each deposit are generally less than 12 the extent of racemization in molluscan fossils of the last interglaciation from temperate coastal settings in southern australia represents an exponential function of temperature and is in general accord with data from northern hemisphere sites with similar contemporary mean annual temperature values these data highlight the potential of amino acid racemization for global correlation programs the amino acid data from southern australia suggest however that a larger margin of variation may have to be accounted for in stratigraphic correlation as indicated by the greater scatter of data around the oxygen isotope substage 5e isochron these data have implications regarding the age resolving power of amino acid racemization

further thermoluminescence dates from the dune sequence in the southeast of south australia abstract our thermoluminescence dating technique has been applied to several new samples from the remarkable sequence of stranded beach dunes in southeast south australia that were formed during the past 800 ka we show that robe iii is probably 100 ka as suggested by schwebel and not 80 ka as we suggested earlier a sample from the west dairy dune is shown to belong to 18 o stage 7 in accordance with schwebel s original suggestion and not stage 5 as he suggested later a new west naracoorte sample yielded acceptable data and an age consistent with formation just after the brunhes matuyama magnetic reversal at 780 ka as required by palaeomagnetic measurements two more samples from the woakwine dune show that our reproducibility is consistent with our derived errors

dynamical analyses of marine atmospheric boundary layer structure near the gulf stream oceanic front the effects of the sea surface temperature s s t front at the edge of the gulf stream on the marine atmospheric boundary layer mabl are investigated using a numerical model to study the modification effects of an oceanic front on the mabl structure the situation simulated is flow from over cold shelf water to over the warm water of the gulf stream the initial temperature and humidity profiles of the air are specified to be near neutral over the cold water and are therefore typical of undisturbed conditions the differential in s s t across the oceanic front creates a horizontal variation in the surface perturbation pressure and the stability the surface perturbation pressure and turbulent fluxes modulate the flow and produce horizontal variations in horizontal wind components with associated vertical motions a thermally direct cell is produced as a result of the s s t difference across the front the isotherms slope upward towards the warm water entrainment of inversion layer air and upward vertical motion over the warm water cause the mabl to be deeper there a layer of cloud forms over warm water and is associated with mixed layer deepening rather than lowering of the condensation level turbulent fluxes in the mabl show considerable spatial variation surface stress is much larger over the front and over the warm water than over the cold water this is mostly caused by wind speed changes associated with the front changes in the drag coefficient due to changes in surface roughness and stability are much less important mean budgets for temperature and total water indicate that there is a balance between horizontal advection and turbulent flux divergence the u momentum budget shows that once the geostrophic balance terms are subtracted the balance is mainly between the pressure gradient force associated with the induced temperature field and turbulent friction with horizontal advection and the coriolis force acting on the geostrophic departure playing minor roles the v momentum budget shows a balance between horizontal advection coriolis force and friction although there are few data for comparison the results are in qualitative agreement with observations in the area this study shows that the s s t front at the gulf stream edge produces marked local changes in the nearby atmospheric surface layer

observations of marine atmospheric boundary layer transitions across the summer kuroshio extension abstract the baiu and kuroshio extension ke fronts both zonally oriented and nearly collocated east of japan are the dominant summertime features of the atmosphere and ocean respectively over the midlatitude northwest pacific an atmospheric sounding campaign was conducted on board the r v roger revelle during the 2005 summer transects of soundings across the ke front are analyzed to study its effects on the atmosphere along with continuous surface meteorological and ceilometer cloud base observations while the ke front remained nearly stationary during the cruise the baiu front displayed large meridional displacements that changed wind direction across the ke front the presence of sharp sea surface temperature sst gradients anchored by the ke enhanced the thermal and moisture advection causing substantial changes in the marine atmospheric boundary layer mabl structure when the baiu front was displaced north of the ke front southwesterly winds advected warm humid air from the subtropics

pleistocene aeolianites at cape spencer south australia record of a vanished inner neritic cool water carbonate factory aeolianites are integral components of many modern and ancient carbonate depositional systems southern australia contains some of the most impressive and extensive late cenozoic aeolianites in the modern world pleistocene aeolianites on yorke peninsula are sculpted into imposing seacliffs up to 60 m high and comprise two distinct imposing complexes of the late pleistocene bridgewater formation the lower aeolianite complex which forms the bulk of the cliffs is a series of stacked palaeodunes and intervening palaeosols the diagenetic low mg calcite sediment particles are mostly bivalves echinoids bryozoans and small benthic foraminifera this association is similar to sediments forming offshore today on the adjacent shelf in a warm temperate ocean by contrast the upper aeolianite complex is a series of mineralogically metastable biofragmental carbonates in a succession of stacked lenticular palaeodunes with impressive interbedded calcretes and palaeosols bivalves geniculate coralline algae and benthic foraminifera together with sparse peloids and ooids dominate sediment grains fragments of large benthic foraminifera including marginopora vertebralis a photosymbiont bearing protist are particularly conspicuous palaeocean temperatures are interpreted as having been sub tropical somewhat warmer than offshore carbonate factories in the region today the older aeolianite complex is tentatively correlated with marine isotope stage 11 whereas the upper complex is equivalent to marine isotope stage 5e marine isotope stage 5e deposits exposed elsewhere in southern australia glanville formation are distinctive with a subtropical biota including marginopora vertebralis thus in this example palaeodune sediment faithfully records the nature of the adjacent inner neritic carbonate factory by inference aeolianites are potential repositories of information about the nature of long vanished marine systems that have been removed due to erosion tectonic obliteration or are inaccessible in the subsurface such information includes not only the nature of marine environments themselves but also palaeoceanography

charcoal reflectance as a proxy for the emplacement temperature of pyroclastic flow deposits hot pyroclastic flow deposits often entomb and preserve vegetation as charcoal when studied in polished section this charcoal is highly reflective novel data from experimentally charred woods demonstrate that reflectance increases with both temperature and time at temperatures above 250 c reflectance rises rapidly for the first hour effectively stabilizing after 4 h for temperatures below 400 c however for higher temperatures reflectance only stabilizes after 24 h charcoalified woods from block and ash flow deposits generated by the soufriere hills volcano in montserrat have yielded interpreted deposit temperatures based on reflectance data of 325 525 c these temperatures compare favorably with directly measured data 365 640 c from the same deposits indicating that charcoal reflectance is useful as a temperature proxy for ancient pyroclastic flow deposits particularly where magnetic or mineral data are absent for this purpose however caution should be exercised as only a minimum temperature can be inferred where the heating duration of the deposit is unknown unlike magnetic or mineral data temperature data from charcoalified woods can be obtained from reworked deposits providing a valuable means of validating observations made about the style of eruption of volcanoes in ancient settings

a late holocene explosive mafic eruption of villarrica volcano southern andes the chaimilla deposit abstract villarrica chile is one of the most active volcanoes in south america having erupted about 60 times in the last 460 years although its historical eruptive activity has been mainly effusive and weakly explosive it had strong explosive behaviour in postglacial times chaimilla

diagenesis and compositional partitioning of quaternary cool water carbonate aeolianites southeastern australia abstract middle to late pleistocene stranded carbonate sea beaches adjacent aeolian dunes and pleistocene aeolianites together with holocene marginal marine calcareous sediments across southeastern australia contain the longest record of such deposition in the modern world stretching back to at least 900 ky mis 23 the grains are were derived from a suite of cool water heterozoan carbonate sediments produced on the adjacent offshore shelf most modern shelf carbonate sediments in the region today are aragonite rich but the aragonite is presently slowly being dissolved on or just below the seafloor before the deposits enter the rock record beach dune sediments are derived mainly from the shallow 30 meters deep adjacent seafloor they are mollusk rich but with most bryozoan particles having been destroyed in the surf zone the mollusks are dominantly aragonite these nearshore sediments are swept onshore before any significant seafloor diagenesis can take place and so are compositionally different from the eventual aragonite poor open shelf sediments aragonite skeletal fragments in the dunes progressively dissolve with time under a semi arid climate and produce diagenetic low magnesium calcite meteoric cements a well known process common in tropical aragonitic pleistocene aeolianites the loss of metastable minerals with time is matched by a progressive and well understood change in stable isotopes such alteration in this environment however seems to take longer than in tropical carbonates with lithification herein not beginning until 200 ka and complete cementation being achieved in 450 ky thus neither aeolianites nor offshore marine carbonates record the composition of the original sediment aeolianites lack the important bryozoan constituents whereas neritic deposits lack the prolific mollusks this partitioning revealed for the first time answers the conundrum as to why some cool water neritic shelf and coastal sediments in the rock record are compositionally different

cloud response to the meandering kuroshio extension front abstracta unique set of observations on board research vessel r v mirai in april 2010 captured a striking cloud hole over a cold meander of the kuroshio extension ke east of japan as corroborated by atmospheric soundings ceilometer shipboard radiation data and satellite cloud images distinct differences were also observed between the warm meander farther to the north and warm water south of the ke the atmosphere is highly unstable over the warm meander promoting a well mixed marine atmospheric boundary layer mabl and a layer of solid stratocumulus clouds capped by a strong inversion over the warm water south of the ke mabl deepens and is decoupled from the ocean surface scattered cumulus clouds develop as captured by rapid variations in ceilometer derived cloud base the results show that the meandering ke front affects the entire mabl and the clouds such atmospheric response can potentially intensify the baroclinicity in the lower atmosphere

lacustrine turbidites as a tool for quantitative earthquake reconstruction new evidence for a variable rupture mode in south central chile understanding the long term earthquake recurrence pattern at subduction zones requires continuous paleoseismic records with excellent temporal and spatial resolution and stable threshold conditions south central chilean lakes are typically characterized by laminated sediments providing a quasi annual resolution our sedimentary data show that lacustrine turbidite sequences accurately reflect the historical record of large interplate earthquakes among others the 2010 and 1960 events furthermore we found that a turbidite s spatial extent and thickness are a function of the local seismic intensity and can be used for reconstructing paleo intensities consequently our multilake turbidite record aids in pinpointing magnitudes rupture locations and extent of past subduction earthquakes in south central chile comparison of the lacustrine turbidite records with historical reports a paleotsunami subsidence record and a marine megaturbidite record demonstrates that the valdivia segment is characterized by a variable rupture mode over the last 900 years including i full ruptures mw 9 5 1960 1575 1319 9 1127 44 ii ruptures covering half of the valdivia segment mw 9 1837 and iii partial ruptures of much smaller coseismic slip and extent mw 7 5 8 1737 1466 4 also distant or smaller local earthquakes can leave a specific sedimentary imprint which may resolve subtle differences in seismic intensity values for instance the 2010 event at the maule segment produced higher seismic intensities toward southeastern localities compared to previous megathrust ruptures of similar size and extent near concepci n

synchronisation of sedimentary records using tephra a postglacial tephrochronological model for the chilean lake district abstract well characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives the use of tephra as a chronological tool is however still widely underutilised in southern chile and argentina in this study we develop a postglacial tephrochronological model for the chilean lake district ca 38 to 42 s by integrating terrestrial and lacustrine records tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout by combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date we present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental palaeoclimatological and palaeoseismological purposes most volcanoes in the studied segment of the southern volcanic zone between llaima and calbuco have produced at least one regional marker deposit resulting from a large explosive eruption magnitude 4 some of which now have a significantly improved age estimate e g the 10 5 ka llaima pumice eruption from llaima volcano others including several units from puyehue cordon caulle are newly described here we also find tephra related to the cha1 eruption from chaiten volcano in lake sediments up to 400 km north from source several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives our chronological model suggests three distinct phases of eruptive activity impacting the area with an early to mid holocene period of relative quiescence extending our tephrochronological framework further south into patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial

pyroclastic density currents at etna volcano italy the 11 february 2014 case study abstract on 11 february 2014 a considerable volume 0 82 to 1 29 106 m3 of unstable and hot rocks detached from the lower eastern flank of the new southeast crater nsec at mt etna producing a pyroclastic density current pdc this event was by far the most extensive ever recorded at mt etna since 1999 and has attracted the attention of the scientific community and civil protection to this type of volcanic phenomena usually occurring without any clear volcanological precursor and especially toward the mechanisms which led to the crater collapse the pdc flow dynamics and the related volcanic hazard we present here the results of the investigation carried out on the 11 february 2014 collapse and pdc events data were obtained through a multidisciplinary approach which includes the analysis of photograph images from visible and thermal surveillance cameras and the detailed stratigraphic textural and petrographic investigations of the pdc deposits results suggest that the collapse and consequent pdc was the result of a progressive thermal and mechanical weakening of the cone by repeated surges of magma passing through it during the eruptive activity prior to the 11 february 2014 events as well as pervasive heating and corrosion by volcanic gas the collapse of the lower portion of the nsec was followed by the formation of a relatively hot up to 750 c dense flow which travelled about 2 3 km from the source stopping shortly after the break of the slope and emplacing the main body of the deposit which ranges between 0 39 and 0 92 106 m3 this flow was accompanied a relatively hot cloud of fine ash that dispersed over a wider area the results presented may contribute to the understanding of this very complex type of volcanic phenomena at mt etna and in similar volcanic settings of the world in addition results will lay the basis for the modeling of crater collapse and relative pdc events and consequently for the planning of hazard assessment strategies aimed at reducing the potential risks to scientists and tens of thousands of tourists visiting etna s summit areas every year

the last interglacial mis 5e sea level highstand from a tectonically stable far field setting yorke peninsula southern australia abstract yorke peninsula in southern australia is an important region for reconstructing relative sea level histories due to its location on the eastern margin of the tectonically stable gawler craton and in one of the world s geographically most remote far field locations from the pleistocene ice sheets richly fossiliferous skeletal carbonate sands of the last interglacial 125 ka glanville formation crop out in the coastal cliffs along large sectors of southern yorke peninsula sedimentary facies include deepening upward intertidal to shallow subtidal facies relict storm beach facies and cobble and boulder beach deposits in more exposed higher energy locations during deposition of the glanville formation southern yorke peninsula had a different coastal geography with two prominent marine corridors extending across the southern most portion of the entire peninsula in a 3 km long coastal cliff section in southern hardwicke bay the glanville formation crops out as an upward deepening intertidal subtidal succession capped by supratidal and subaerially exposed sediments with pervasive calcrete development the sedimentary succession passes upwards from a basal unit of intertidal sand flat facies with abundant gastropods batillaria diemenensis near the upper bounding disconformity surface upwards into richly fossiliferous shelly sands coquina representing a shallow subtidal facies formed by sediment aggradation in response to a relative sea level rise the subtidal facies is dominated by the bivalve molluscs katelysia sp and amesodesma angusta signifying a water deepening event the subtidal facies is in turn overlain by pedogenically modified skeletal carbonate sands with pervasive calcrete development signifying a relative sea level fall at the end of the last interglacial maximum the upper bounding surface of the shallow water subtidal facies ranges from 2 4 to 3 0 m australian height datum ahd and by analogy with modern sedimentary environments suggests a maximum palaeo sea level of 4 8 1 0 m during the last interglacial maximum uranium series ages of 127 3 2 1 to 115 0 5 4 ka on specimens of the solitary coral plesiastrea versipora from the subtidal facies confirm that the succession was deposited during the last interglacial maximum and are consistent with the independent stratigraphical evidence that the highstand event was represented by a single phase of relative sea level rise correlation with other occurrences of the glanville formation in southern australia has also been confirmed by aminostratigraphy

modulation mechanisms of marine atmospheric boundary layer at the brazil malvinas confluence region 1 the influence of the brazil malvinas confluence bmc region on the marine atmospheric boundary layer mabl is investigated through in situ data analysis of five different cruises 2004 to 2008 and numerical experiments with a regional atmospheric model two different groups of numerical experiments were performed in order to evaluate the relevance of static stability and hydrostatic balance physical mechanisms for the mabl instability the first group used monthly climatological sea surface temperature sst as bottom boundary condition while the second used daily updated advanced microwave scanning radiometer eos sst data together with radiosondes and surface data assimilation a reasonable agreement between numerical results and quikscat wind data was observed through correlation coefficients and mean square error values in terms of the horizontal structure of the mabl stronger winds were found over the warm side of the bmc region as well as over the thermal front itself which supports the coexistence of both modulation mechanisms the analyzed patterns of surface atmospheric thermal advection showed a clear interaction between the synoptic and regional scales the signature of the oceanic thermal front almost meridionally oriented on the air temperature at 2 m makes the temperature advection strongly determined by the zonal component of the wind the analysis of momentum budget terms did not show a clear and reasonable explanation of the existence or predominance of the modulation mechanisms and it also suggested the relevance of other effects such as the idea based on unbalanced coriolis force and turbulence friction effects

optically stimulated luminescence dating of holocene relict foredunes guichen bay south australia abstract optically stimulated luminescence osl dating of quartz sand 106 150 or 150 200 m in bioclastic carbonate quartz sediments sampled from coastal relict foredunes beach ridges was undertaken to evaluate the utility of the osl method for studies of dune dynamics and to quantify rates of coastal progradation twelve sediment samples from a 4 km transect across a holocene embayment fill at guichen bay south australia were measured for their luminescence characteristics apart from one age inversion attributed to recent disturbance associated with mining the osl ages are in sequential order when considered in the context of their associated error terms the osl ages indicate an extremely rapid initial phase of sedimentation i e 1600 m within a few hundred years approximately 5 ka ago followed by a constant rate of progradation for the past 4 ka of 0 39 m a with a high level of association between distance across the embayment fill and luminescence age for this time interval an average rate of dune development of one dune every 80 yr from 3900 yr ago to the present day is apparent the osl ages for the late holocene indicate that the present beach state is largely in equilibrium with sediment supply

global analysis of the pressure adjustment mechanism over sea surface temperature fronts using airs aqua data 1 we investigate the signatures of atmospheric pressure adjustment mechanism for surface wind convergence divergence over major sea surface temperature sst frontal regions using global observations of satellite sounding and scatterometer lower tropospheric air thickness which includes a sea level pressure component modified by air temperature in the marine atmospheric boundary layer is analyzed and the relation between the laplacian of the thickness and wind convergence are examined among four sst frontal regions in mid latitudes correlation between the thickness laplacian and wind convergence is the largest over the gulf stream followed by those for the agulhas return current and for the brazil malvinas current and relatively small but still significant over the kuroshio oyashio extension these correlations strongly suggest that the pressure adjustment mechanism ubiquitously plays an important role in air sea interaction over the global sst frontal regions furthermore air temperatures in the first two regions exhibit sst relating signatures even in the mid troposphere

transport and deposition of a pyroclastic surge across an area of high relief the 18 may 1980 eruption of mount st helens washington the 08 32 pdt 18 may 1980 mount st helens eruption began as an explosion blast that produced a laterally flowing pyro clastic current blast surge it moved outward in a 180 arc at supersonic speeds and then slowed to subsonic speeds supersonic flow severely eroded the ground and produced a ground layer formerly layer a0 above the ground layer lies the deposit derived from the blast surge the blast surge deposits formed in three continuous and concurrent stages the first stage was movement of the transport system that is the blast surge carrying fragments most of the distance from the vent the next two stages involved the depositional system this system developed from rapidly accumulating sediment by gravity segregation at the base of the blast surge two stages of sediment gravity flows with independent flow regimes formed sequentially in rapid succession from the moving blast surge each moved downhill due to gravity independently of the generating blast surge that was driven by explosive expansion units repeated in some sections are deposits derived from divergent and crossing surge lobes caused by irregular topography locally ponded massive deposits in valleys and depressions formed from gas rich pyroclastic flows and originated in two ways 1 topographic blocking by steep volcano facing slopes blocking includes diversion or damming of the lower elevation high density part of the blast surge that could not surmount high ridges 2 also occurring to form valley ponds was drainage of just deposited or almost deposited material from steep slopes 30 35 moving downhill in all slope directions into separate valleys or depressions distances traveled by the blast surge and rates at which coarsest fragments decrease laterally are related to the topographic grain surge runout was farther where flow directions paralleled topographic trends and least where trends were at right angles to the flow obstacle interference depositional patterns thinning thickening rapid fine to coarse facies changes caused a spread in median diameter values that are as great in local areas near the volcano as they are over the width of the devastated region

experimental studies of particle laden plumes experiments are described in which buoyant plumes of fresh water and solid particles are generated in a tank of salt water dependence of the behavior of the plumes on particle concentration and grain size was studied at low concentrations behavior was similar to single component plumes and the principal effect of the particles was to reduce the buoyancy flux measurements of particle concentration across the plumes demonstrated that there were substantial amounts of particle reentrainment from an outer sedimenting veil reentrainment caused the plume margins to become denser than the ambient fluid total particle flux in the plumes increased with height and can be several times greater than the flux at the plume source plumes with high particle concentration exhibit several kinds of convective instability which generated gravity currents and rapid sedimentation gravity currents were generated at the margins of concentrated plumes these flows are attributed to reentrainment causing the flow margins to have excess density when the plume density was close to but less than the density of the ambient fluid a fountain forms high in the plumes which collapsed asymmetrically to generate a gravity current on one side of the plume when the density of the particle laden flow was greater than the ambient fluid a symmetrical fountain formed and gravity currents moved across the tank floor depositing sediment at a well defined distance from the source buoyant fluid ascended from the flow fronts to form a ring of plumes around the central fountain these plumes coalesced to form a broad buoyant cloud the plumes are generated by the sedimentation from the gravity currents which resulted in the fresh water and some entrained particles being released all the experimental plumes ascended to the top of the tank and spread out as gravity currents beneath the upper surface particles often fall from this layer in discrete parcels of particle rich fluid with shapes similar to thermals the fall velocities were much greater than the terminal velocities of individual particles and the sedimenting region is inhomogeneous these observations indicate that sedimentation is enhanced by convective instabilities when particle rich fluid is emplaced above particle free fluid the experiments indicate that there may be several different mechanisms of generating pyroclastic flows and surges from the collapse of volcanic eruptions columns the experiments also demonstrate that the sedimentation of particles from a plume has an important influence on dynamical behavior

on the importance of midlatitude oceanic frontal zones for the mean state and dominant variability in the tropospheric circulation 1 observations indicate that midlatitude weather systems are organized into storm tracks near oceanic frontal zones with pronounced sea surface temperature sst gradients a pair of atmospheric general circulation model experiments with zonally uniform sst profiles prescribed show that their observed collocation is not fortuitous in one experiment a storm track is anchored around a midlatitude sst front that maintains near surface thermal gradients and energizes eddies westerly momentum transport by eddies produces a well defined polar front jet along the front even in winter when a subtropical jet stream intensifies in the other experiment removal of the sst front leads to a substantial weakening in eddy activity and the pfj especially in winter it also leads to a weakening of the annular mode the dominant mode of westerly jet variability and its notable structural distortion in winter though idealized our experiments suggest the importance of midlatitude oceanic fronts for the tropospheric circulation and its variability

whole rock aminostratigraphy of the coorong coastal plain south australia towards a 1 million year record of sea level highstands the coorong coastal plain in southeastern south australia preserves a long quaternary record of cool water temperate carbonate sedimentation in the form of high wave energy barrier shoreline deposits and associated back barrier lagoon facies that formed during successive sea level highstands whole rock samples of bioclastic skeletal carbonate sand with subordinate quartz were collected from aeolian facies modern and relict foredunes of a holocene embayment fill and from ten pleistocene barriers across the coastal plain in a transect from robe to naracoorte the extent of leucine racemization total acid hydrolysate and free amino acids in the pleistocene skeletal carbonate sand 63 500 m increases monotonically with age and is consistently higher than for entire fossil molluscs from the same allostratigraphic units reflecting the lengthy residence time for bioclasts in this high wave energy environment and sediment recycling from the erosion of older barriers the extent of racemization in the whole rock samples conforms with a model of apparent parabolic racemization kinetics and the calculated ages largely agree with previously determined luminescence ages apart from a possible reinterpretation of the significance of the west naracoorte range the coastal plain succession indicates that interglacial sea levels did not deviate by more than 6 m of present sea level for the mid and late pleistocene thus providing an important framework for quantifying ice volume during sea level highstands and calibrating the oxygen isotope record

reconciliation of late quaternary sea levels derived from coral terraces at huon peninsula with deep sea oxygen isotope records a major discrepancy between the late quaternary sea level changes derived from raised coral reef terraces at the huon peninsula in papua new guinea and from oxygen isotopes in deep sea cores is resolved the two methods agree closely from 120 ka to 80 ka and from 20 ka to 0 ka ka 1000 yr before present but between 70 and 30 ka the isotopic sea levels are 20 40 m lower than the huon peninsula sea levels derived in earlier studies new high precision u series age measurements and revised stratigraphic data for huon peninsula terraces aged between 30 and 70 ka now give similar sea levels to those based on deep sea oxygen isotope data planktonic and benthic 18o data using the sea level and deep sea isotopic data oxygen isotope ratios are calculated for the northern continental ice sheets through the last glacial cycle and are consistent with results from greenland ice cores the record of ice volume changes through the last glacial cycle now appears to be reasonably complete