multi method dating comparison for mid pleistocene rangitawa tephra new zealand abstract the rangitawa tephra a widespread mid pleistocene marker in the new zealand region is dated by fission track thermoluminescence tl infrared stimulated luminescence irsl k ar and single crystal laser fusion sclf 40 ar 39 ar methods as well as by matching to the astronomical timescale via oxygen isotope stratigraphy in deep sea cores fifty one independent numerical age estimates for rangitawa tephra range from 173 to 456 ka however only 15 of these results are considered to be reliable five zircon fission track results four isothermal plateau fission track itpft age estimates on glass shards four sclf 40 ar 39 ar results and two astronomically calibrated age estimates from deep sea cores the weighted mean of the nine reliable fission track age determinations is 345 12 ka in excellent agreement with the weighted mean of 340 7 ka for the two reliable astronomically calibrated age estimates the weighted mean of the four reliable 40 ar 39 ar results 302 8 ka is significantly younger and further ar ar dating is recommended to investigate this difference since the tl and irsl dating methods are experimental for sediments beyond 200 ka we have excluded these from the group of reliable age results tl and irsl results on dunesand appear to be systematically younger than tl results on loess and loess results depend upon analytical procedures

aminostratigraphy of quaternary shorelines in the mediterranean basin the age and correlation of shorelines around the mediterranean basin have been addressed by analyzing the extent of isoleucine epimerization aile ile ratio in protein preserved in molluscan fossils collected from raised marine deposits the taxodont genera glycymeris and arca were selected as the primary taxa for this study because of their simple shell structure reproducible aile ile ratios and ubiquitous occurrence direct comparison of aile ile ratios in associated mollusks allows correlation of disjunct marine deposits and relative dating of sequential marine units in nearby areas that have similar thermal histories the thermal gradient across the mediterranean basin is however sufficiently high that shells from isochronous shorelines have significantly higher ratios at warmer than at cooler localities absolute dating primarily u series dates on corals directly associated with molluscan samples provides an independent calibration of the amino acid data and compensates for dissimilar thermal histories aile ile ratios in shells from 46 marine units cluster into 5 discrete groups c e f g and k that are related to positive sea level events interglacials interstadials associated with odd numbered deep sea isotopic stages the most complete sequences are in southern italy where group c ratios in glycymeris that average 0 30 are associated with the neotyrrhenian a post last interglacial late stage 5 high sea level event group e ratios 0 38 are associated with classical eutyrrhenian deposits from which four u series coral dates 126 7 ka substantiate the correlation to isotope substage 5e group f ratios 0 50 are associated with u series coral and mollusk dates between 200 and 300 ka the deposits are tentatively correlated with stage 7 deposits that have group g ratios 0 58 are correlated with stage 9 shells from lower pleistocene marine deposits that have ratios between 1 0 and 1 2 group k constrain the ages of the younger groups an exponential decrease in the epimerization rate inhibits resolution of the older events aile ile ratios in last interglacial deposits are similar in the northern and central region of the study area but increase sharply in southern sicily north africa and crete similar to the modern thermal gradient a lacuna between group g and group k is similar to gaps identified in california and alaska suggesting generally lower interglacial sea levels between stage 11 and sometime before the brunhes matuyama boundary

aminostratigraphy and faunal correlations of late quaternary marine terraces pacific coast usa recent studies using the extent of racemization of amino acids to date fossil mollusc shells in the arctic1 the british isles2 and on the atlantic3 4 and pacific5 13 coasts of north america have relied mainly on theoretical kinetic models of racemization ages generated in this fashion are highly model dependent and require estimates of integrated long term diagenetic temperatures we present here an alternative empirical approach to aminostratigraphy in which we plot amino acid enantiomeric ratios versus latitude for localities along the pacific coast of the united states and generate isochronal correlations by connecting data points of geographically proximal localities that have similar d l ratios and zoogeographic aspect isochrons are calibrated at a few localities by independent radiometric dates the diagenetic temperature effect on racemization is reflected in the slope of the isochrons but the need to quantify temperature is eliminated

a comparison of shear and buoyancy driven planetary boundary layer flows abstract planetary boundary layer pbl flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces these differences are not unexpected in that shear instabilities occur locally while buoyancy force sets up vigorous thermals which result in nonlocal transport of heat and momentum at the same time these two forces can act together to modify the flow field in this study four large eddy simulations less spanning the shear and buoyancy flow regimes were generated two correspond to the extreme cases of shear and buoyancy driven pbls while the other two represent intermediate pbls where both forces are important the extreme cases are used to highlight and quantify the basic differences between shear and convective pbls in 1 flow structures 2 overall statistics and 3 turbulent kinetic energy tke budget distributions results from the two intermediate les cases are used to develop and verify a velocity scaling and a tke budget mode

sea surface roughness and drag coefficient as functions of neutral wind speed abstract near the surface it is commonly believed that the behavior of the turbulent atmospheric flow can be well described by a constant stress layer in the case of a neutrally stratified surface layer this leads to the well known logarithmic wind profile that determines the relation between near surface wind speed and magnitude of stress the profile is set by a surface roughness length which over the ocean surface is not constant rather it depends on the underlying ocean wave sea state for instance at the european centre for medium range weather forecasts this relation is parameterized in terms of surface stress itself where the scale is set by kinematic viscosity for light wind and a charnock parameter for strong wind for given wind speed at a given height the determination of the relation between surface wind and stress expressed by a drag coefficient leads to an implicit equation that is to be solved in an iterative way in this paper a fit is presented that directly expresses the

convective boundary layer structure in the presence of wind following swell the marine boundary layer is known to be influenced by fast long ocean swell waves travelling away from their generation area where they were initiated by momentum transferred to the ocean wave field during storms the atmospheric boundary layer during wind following swell and various stability states has been investigated using large eddy simulation les data the dominant energy containing motions in the near neutral atmospheric boundary layer over flat terrain are known to be dominated by near ground shear induced regions of high and low speed flow wind fields and momentum fluxes from les for swell dominated situations have been used to interpret field measurements suggesting that these motions are disrupted by effects related to the underlying wave field in the presence of swell waves statistical analysis and visualization are used to further describe the effects of stratification during swell for convective boundary layer winds and fluxes a mechanism for transport of momentum to the upper levels of the boundary layer is suggested from interpretation of les data coherent detached eddies from the directly wave induced motions near the surface are found to maintain an upward momentum transfer this mechanism is found to strengthen during stronger swell conditions and also during slightly convective conditions in this way it is argued that processes related to both the wave field and surface convection can have a significant influence on the global structure of neutral and convective boundary layers during swell this has implication for the turbulence length scales during wind following swell copyright 2012 royal meteorological society

further development of a theory of lee cyclogenesis abstract the purpose of this paper is to further develop and then apply the lee wave theory of lee cyclogenesis described by smith the two dimensional time dependent quasi geostrophic theory is shown to give closed form asymptotic solutions which clarify the cyclone growth mechanism and the catalytic influence of orography ageostrophic effects are considered and found to have little influence on the ice cyclone unless a low lying inertial wave critical layer is present when a rigid lid is added to the model thus allowing baroclinic instability a rapid two phase cyclone growth is found without a resonant orographic phase the unstable growth is small the theory is applied to three mountain ranges the alps the colorado rockies and the southern appalachians the results suggest that the iee wave model may be partially correct in the first two regions but problematic in the third

a late holocene marine terrace on the kidnappers coast north island new zealand some implications for shore platform development processes and uplift mechanism abstract a marine terrace up to 6 m above present mean sea level is preserved along 15 km of the kidnappers coast hawke s bay north island new zealand radiocarbon dates for 10 shell samples collected from intertidal marine deposits overlying an uplifted shore platform have a total age range of 590 yr from 2280 50 to 2750 70 yr b p sample age decreases landward suggesting a small relative sea level rise probably as a result of tectonic subsidence prior to uplift rates of contemporary shore platform formation preclude the preservation of a marine terrace subjected to constant aseismic uplift preservation of a subhorizontal uplifted shore platform mantled by intertidal marine deposits with in situ fauna is best explained by abrupt coseismic uplift 2300 yr b p and preceded by tectonic subsidence the presence of a single marine terrace does not permit the calculation of past earthquake magnitude or recurrence but the nne tilt of the 2300 yr old marine terrace indicates continued growth of the north trending late pleistocene kidnappers anticline

large eddy simulations and observations of atmospheric marine boundary layers above nonequilibrium surface waves abstract winds and waves in marine boundary layers are often in an unsettled state when fast running swell generated by distant storms propagates into local regions and modifies the overlying turbulent fields a large eddy simulation les model with the capability to resolve a moving sinusoidal wave at its lower boundary is developed to investigate this low wind fast wave regime it is used to simulate idealized situations with wind following and opposing fast propagating waves swell and stationary bumps les predicts momentum transfer from the ocean to the atmosphere for wind following swell and this can greatly modify the turbulence production mechanism in the marine surface layer in certain circumstances the generation of a low level jet reduces the mean shear between the surface layer and the pbl top resulting in a near collapse of turbulence in the pbl when light winds oppose the propagating swell turbulence levels increase over the depth of the boundary layer and the surface drag increases

wave driven wind jets in the marine atmospheric boundary layer abstract the interaction between ocean surface waves and the overlying wind leads to a transfer of momentum across the air sea interface atmospheric and oceanic models typically allow for momentum transfer to be directed only downward from the atmosphere to the ocean recent observations have suggested that momentum can also be transferred upward when long wavelength waves characteristic of remotely generated swell propagate faster than the wind speed the effect of upward momentum transfer on the marine atmospheric boundary layer is investigated here using idealized models that solve the momentum budget above the ocean surface a variant of the classical ekman model that accounts for the wave induced stress demonstrates that although the momentum flux due to the waves penetrates only a small fraction of the depth of the boundary layer the wind profile is profoundly changed through its whole depth when the upward momentum transfer from surface waves sufficiently exceeds the downward turbulent momen

pleistocene unconformity bounded shelf sequences wanganui basin new zealand correlated with global isotope record abstract eleven successive unconformity bound sequences in the castlecliff section wanganui basin each typically composed of a lower variably conglomeratic 0 1 2 m thick shell bed and an upper 5 20 m thick barren siltstone are identified in the stratotype of the local new zealand middle pleistocene castlecliffian stage based on magnetostratigraphy the section is correlated with the published benthonic oxygen isotope curve for dsdp core 552a from the north atlantic each of the sequences accumulated during one of the odd numbered interglacial isotope stages in the interval 31 to 11 inclusive the unconformities developed during intervening glacial ages when the shelf was exposed through glacio eustatic lowering the correlation provides a geochronologic framework for assessment of the eustatic contribution to the generation of the sequences in a situation where the paleoshorelines and related shelf sequences are preserved and for which an independent approximation of the sea level history is available in the form of an oxygen isotope curve

introducing surface waves in a coupled wave atmosphere regional climate model impact on atmospheric mixing length 1 the marine atmospheric boundary layer is strongly influenced by the moving surface in the presence of surface waves the impact depends on the wave conditions and the interaction with the atmosphere previous studies using measurements as well as numerical simulations with large eddy simulations have shown that surface waves propagating faster than the wind swell alter the surface exchange as well as turbulence properties in the atmosphere this impact is here introduced in a coupled wave atmosphere regional climate model with a so called e l turbulence scheme where e is the turbulent kinetic energy and l is a mixing length a wave age dependent coefficient here called wmix is added to the mixing length in the turbulence parameterization this acts similarly to inducing additional convection with larger mixing length and increased eddy diffusivity when we have near neutral stratification and strong swell for shallow boundary layers the regional coupled climate model shows a larger response to the introduced wave coupling with increased near surface wind speed and smaller wind gradient between the surface and middle part of the boundary layer the impact for the studied areas is relatively minor for parameters averaged over 1 year but for limited periods and specific situations the impact is larger one could expect a larger impact in areas with stronger swell dominance we thus conclude that the impact of swell waves on the mixing in the boundary layer is not insignificant and should be taken into account when developing wave atmosphere coupled regional climate models or global climate models

upper quaternary marine terrace chronology and deformation south taranaki new zealand an extensive flight of late quaternary marine terraces in the south taranaki region of the north island of new zealand is dated using fission track radiocarbon and amino acid racemization methods a simple model of terrace deformation based on a doming type uplift pattern allows terrace strandline ages to be estimated twelve strandlines are recognized and are estimated to have formed during high sea level stands at 60 000 80 000 100 000 120 000 135 000 210 000 310 000 340 000 400 000 450 000 520 000 600 000 and 680 000 yr b p

amino acid geochronology of raised beaches in south west britain abstract based on 1 the epimerization of l isoleucine to d alloisoleucine d l ratios in patella vulgata littorina littorea l littoralis l saxatilis littorina species and nucella lapillus from raised beaches in south west britain 2 statistical analysis of the d l ratios and 3 lithostratigraphic and geomorphic evaluation three d l stages are proposed the d l ratios for all the species measured are converted to a patella vulgata standard the three d l stages are 1 1 the minchin hole d l stage d l ratios 0 175 0 014 defined at a stratotype in minchin hole cave gower wales 2 2 a provisionally defined but as yet unamed d l stage because of the current unavailability of a suitable stratotype with d l ratios of 0 135 0 014 3 3 the pennard d l stage d l ratios 0 105 0 016 defined at a stratotype in minchin hole cave gower wales two geochronological models of the three high sea level events representing the d l stages are constrained by uranium series age determinations on stalagmite interbedded with marine beds in minchin hole and bacon hole caves gower wales a potential fixed point in model evaluation is an age determination which is equivalent to oxygen isotope sub stage 5e 122 ka the two models are oxygen isotope stage and age ka bp d l stage d l ratio model 1a model 1b model 2 pennard 0 105 0 016 5a ca 80 5e 122 5e 122 5c ca 100 unnamed 0 135 0 014 5e 122 7 194 minchin hole 0 175 0 014 7 186 245 7 186 245 7 216 the ages of the raised beaches are used to constrain the timing and extent of glaciation in the area the extent of the late devensian glaciation is fixed by reference to localities where raised beaches of the pennard d l stage outcrop as well as by using unpublished data on molluscs incorporated into glacial deposits two pre devensian glaciations antedate the minchin hole d l stage the irish sea glaciation of the bristol channel irish sea older drift of south wales fremington till of north devon is ascribed to oxygen isotope 10 or earlier while the paviland welsh glaciation is ascribed to oxygen isotope stage 8 or earlier an earlier glaciation berwyn glaciation is inferred from erratics of known welsh provenance in essex

correlations between interannual sst oscillations and modeled swell impacts on turbulent mixing abstractthe possibility of teleconnections between southern ocean swells and sea surface temperature sst anomalies on interannual time scales in the eastern pacific nino 3 region and southeastern indian ocean is investigated using numerical wave models two alternative parameterizations for swell dissipation are used it is found that swell dissipation in the models is not directly correlated with large interannual variations such as el nino southern oscillation enso or the indian ocean dipole iod however using one of the two swell dissipation parameterizations a correlation is found between observed sst anomalies and the modification of turbulent kinetic energy flux tkef by southern ocean swells due to the damping of short wind waves modeled reduction of tkef is opposite in phase to the sst anomalies in the nino 3 region indicating a potential positive feedback the modeled bimonthly averaged tkef reduction in the southeastern indian ocean is also well correlated with the iod mode

zircon fission track age for middle pleistocene rangitawa tephra new zealand stratigraphic and paleoclimatic significance rangitawa tephra is an important stratigraphic marker in mid pleistocene marine and terrestrial sequences in new zealand and adjacent ocean basins zircon fission track ages zfta on rangitawa tephra from five sites in the southern north island yield mean site ages in the range 0 34 to 0 40 ma with a weighted mean of 0 35 0 04 ma 1 on the basis of glass shard major element chemistry ferromagnesian mineralogy zfta and similarity of paleomagnetic dates of proposed tephra correlatives in deep sea cores it is concluded that rangitawa tephra represents a major eruptive event in the taupo volcanic zone most probably associated with eruption of the whakamaru group ignimbrites 0 35 0 39 ma or less likely the paeroa range group ignimbrites 0 36 0 38 ma pollen analyses from two onshore sites together with regional loess stratigraphy show that rangitawa tephra was erupted during a glacial period the zfta and previously reported oxygen isotope data from dsdp site 594 indicate that rangitawa tephra was erupted near the end of oxygen isotope stage 10

impact of swell on the marine atmospheric boundary layer a model that describes the impact of swell on the marine atmospheric boundary layer is proposed the model is based on the two layer approximation of the boundary layer the near surface inner region and the outer region above the swell induced momentum and energy fluxes are confined within the inner region swell loses energy to the atmosphere and enhances the turbulent kinetic energy in the inner region the transfer of momentum results in acceleration or deceleration of the airflow near the surface following wind swell accelerates the flow which for a very low wind results in a swell driven wind opposite wind swell decelerates the airflow which for a steep swell could cause the reverse airflow the sea drag in the case of opposite wind swell is considerably enhanced as compared with the following wind swell case cross wind swell causes the rotation of the wind velocity vector with height which leads to the deviation of the turbulent stress vector from the wind velocity vector the impact of swell becomes more pronounced when the wind speed decreases or when the swell phase velocity increases in fact it is the wave age of the swell that characterizes the swell impact because the dimensionless wave induced fluxes of energy and momentum are proportional to the wave age parameter both fluxes are also proportional to the swell slope so that the swell impact is stronger for a steeper swell the model reproduces qualitatively and quantitatively the main experimental findings for the ocean swell the impact of swell on the sea drag is very pronounced for opposite wind swell is less pronounced for cross wind swell and is only at low wind speeds

evidence of energy and momentum flux from swell to wind abstractmeasurements of pressure near the surface in conditions of wind sea and swell are reported swell or waves that overrun the wind produces an upward flux of energy and momentum from waves to the wind and corresponding attenuation of the swell waves the estimates of growth of wind sea are consistent with existing parameterizations the attenuation of swell in the field is considerably smaller than existing measurements in the laboratory

controls on active forearc basin stratigraphy and sediment fluxes the pleistocene of hawke bay new zealand detailed high resolution documentation of forearc basin fi ll is scarce in the literature in this geological and geophysical study we investigated the pleistocene sedimentary record of the tectonically active hawke bay forearc domain of the hikurangi subduction margin of new zealand interpretation of an extensive seismic refl ection data set that is correlated with marine cores and onshore geological maps identifi es the detailed stratigraphic architecture of the last 1 1 m y this analysis reveals the infl uences and interactions of tectonic deformation climate eustasy and isostasy on forearc basin sedimentation eleven 100 k y depositional sequences are recognized in the basin fi ll thus highlighting the dominance of pleistocene climate eustasy on sequence development the stacking pattern and isopach maps of sequences exhibit an overall retrogradational trend and an arcward migration of depocenters these trends progressively develop a basinwide diachronous and composite erosion unconformity formed by the lateral succession and landward encroachment of the 12 sequence bounding unconformities s12 to s1 among these the s5 surface ca 430 ka is an angular unconformity that separates major megasequences of the sedimentary record the forearc domain evolved from a series of ridge parallel basins to a succession of connected basins that have progressively developed around major growing thrust faulted ridges since ca 430 ka this change in basin confi guration and associated signifi cant increase of the preserved sediment fluxes occurred synchronous with the reactivation of major out of sequence thrusts and the completion of the mid pleistocene transition

the influence of swell on the atmospheric boundary layer under nonneutral conditions the anomalous phenomena induced by the prevailing swell at low wind speeds prevent a complete understanding of air sea interaction processes many studies have considered this complex problem but most have focused on near neutral conditions in this study the influence of the swell on the atmospheric boundary under nonneutral conditions was addressed by extending the turbulent closure models of makin and kudryavtsev and the monin obukhov similarity theory most monin and yaglom to the existence of swell and nonneutral conditions it was shown that wind profiles derived from these models were consistent with each other and both departed from the traditional most at low wind speeds a supergeostrophic jet appeared on the upper edge of the wave boundary layer which was also reported in earlier studies under nonneutral conditions the influence of buoyancy was significant the slope of the wind profile increased under stable conditions and became smoother under unstable conditions considering the effects of buoyancy and swell the wind stress derived from the model agreed quantitatively with the observations

vertical profiles of the wave induced airflow above ocean surface waves abstractan analysis of coherent measurements of winds and waves from data collected during the onr southern california 2013 socal2013 program from r p flip off the coast of southern california in

a case study of air sea interaction during swell conditions air sea interaction data from a situation with pronounced unidirectional swell have been analyzed measurements of turbulence at three levels 10 18 and 26 m above mean sea level together with directional wave buoy data from the site ostergarnsholm in the baltic sea were used the situation which lasted for 48 hours appeared in the aftermath of a gale the wind direction during the swell situation turned slowly within a 90 sector both during the gale phase and the swell phase the over water fetch was 150 km the wind speed during the swell phase was typically 4 m s 1 during the swell phase a wind maximum near or below the lowest wind speed measuring level 10 m was observed the net momentum flux was very small resulting in cd values 0 7 10 3 throughout the lowest 26 m covered by the tower measurements turbulence intensities in all three components remained high despite the low value of the kinematic momentum flux u w resulting in a reduction of the correlation coefficient for the longitudinal and vertical velocity from its typical value around 0 35 to between 0 2 and 0 and with some positive values at the higher measuring levels appearing abruptly at wave age c0 u10 equal to 1 2 turbulence spectra of the horizontal components were shown not to scale with height above the water surface in contrast to vertical velocity spectra for which such a variation was observed in the low frequency range in addition spectral peaks in the horizontal wind spectra were found at a frequency as low as 10 3 hz from a comparison with results from a previous study it was concluded that this turbulence is of the inactive kind being brought down from the upper parts of the boundary layer by pressure transport

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

the pleistocene cape kidnappers section in new zealand orbitally forced controls on active margin sedimentation high sedimentation rates in pleistocene active margin basins can provide a very detailed record of tectonic and climatic controls on sediment preservation a 500 m thick pleistocene rock section exposed in northeastern north island of new zealand kidnappers group provides the opportunity to discuss these controls the section is composed of conglomerate sandstones siltstones and minor shales interbedded with tephra layers the sediments were deposited in alluvial to shallow marine environments and preserved in stacks of depositional units decimetres to hundreds of metres thick as a result of base level changes through time the correlation of base level changes in the section with the deep sea oxygen isotope stratigraphy shows that the sequences at 10 m and 80 m scales can correlate respectively to the 20 and 100 kyr changes in eustatic sea level but that the 80 m thick sequences correlate also to changes in tectonic uplift rates a major change in the stratigraphical architecture occurs at the mid pleistocene transition mpt when the 40 kyr ice volume variations shifted to a dominant 100 kyr variation this change includes an increase in the amplitude of the shifts in depositional environments and an overall simplification of the stacking pattern of the depositional units through the mpt this study illustrates that active margin basins can record orbitally forced sedimentary cycles and points to a possible leading influence of eustasy on the pattern of sediment preservation in tectonically active areas copyright 2004 john wiley sons ltd

quaternary marine terrace chronology north canterbury new zealand using amino acid racemization and infrared stimulated luminescence extensive marine terraces along the north canterbury coast of the south island of new zealand record uplift in this tectonically active area although the terraces have been studied previously applications of quaternary geochronological techniques to the region have been limited we use infrared stimulated luminescence irsl amino acid racemization aar and radiocarbon to determine ages of terraces at three locations glenafric motunau beach and haumuri bluff we develop an aar calibration curve for the mollusk species tawera spissa from sites of known age including the sedimentary sequence of the whanganui basin bayesian model averaging of the results is used to estimate ages of marine shells from the north canterbury terraces by using both irsl and aar we are able to confirm ages using two independent dating methods and to identify one irsl result that is likely in error we develop new age estimates for the marine terraces of north canterbury and propose correlations between sites this terrace chronology differs significantly from most previous studies highlighting the importance of numerical dating the most extensive terraces are from marine isotope stages miss 5a and 5c with partial reoccupation of one terrace during mis 3 whereas mis 5e terraces are notably lacking among those dated

observational study of marine atmospheric boundary layer characteristics during swell abstract by combining simultaneous data from an instrumented air sea interaction spar asis buoy and a 30 m tower profiles of wind and turbulence characteristics have been obtained at several heights from about 1 to 30 m above the water surface during swell conditions five cases formed as averages over time periods ranging from 2 5 to 9 5 h representing quasi steady conditions have been selected they represent a range of typical wave age and include wind following swell cases and cross swell cases for relatively large wave age the wind profile exhibits a well defined maximum in the height range 5 10 m for more modest wave age this maximum turns into a sharp knee in the wind profile below the maximum or knee the wind increases rapidly with height above that point the wind is very nearly constant up to the highest measuring level on the tower 30 m analysis of balloon data from one day with swell indicates that the layer with constant wind in fact extends to the top of the boundary layer

wave induced wind in the marine boundary layer recent field observations and large eddy simulations have shown that the impact of fast swell on the marine atmospheric boundary layer mabl might be stronger than previously assumed for low to moderate winds blowing in the same direction as the waves swell propagates faster than the mean wind the momentum flux above the sea surface will then have two major components the turbulent shear stress directed downward and the swell induced stress directed upward for sufficiently high wave age values the wave induced component becomes increasingly dominant and the total momentum flux will be directed into the atmosphere recent field measurements have shown that this upward momentum transfer from the ocean into the atmosphere has a considerable impact on the surface layer flow dynamics and on the turbulence structure of the overall mabl the vertical wind profile will no longer exhibit a logarithmic shape because an acceleration of the airflow near the surface will take place generating a low level wave driven wind maximum a wind jet as waves propagate away from their generation area as swell some of the wave momentum will be returned to the atmosphere in the form of wave driven winds a model that qualitatively reproduces the wave following atmospheric flow and the wave generated wind maximum as seen from measurements is proposed the model assumes a stationary momentum and turbulent kinetic energy balance and uses the dampening of the waves at the surface to describe the momentum flux from the waves to the atmosphere in this study simultaneous observations of wind profiles turbulent fluxes and wave spectra during swell events are presented and compared with the model in the absence of an established model for the linear damping ratio during swell conditions the model is combined with observations to estimate the wave damping for the cases in which the observations showed a pronounced swell signal and almost no wind waves the agreement between observed and modeled wind profiles is remarkably good the resulting attenuation length is found to be relatively short which suggests that the estimated damping ratios are too large the authors attribute this at least partly to processes not accounted for by the model such as the existence of an atmospheric background wind in the model this extra momentum must be supplied by the waves in terms of a larger damping ratio

a global perspective on langmuir turbulence in the ocean surface boundary layer the turbulent mixing in thin ocean surface boundary layers osbl which occupy the upper 100 m or so of the ocean control the exchange of heat and trace gases between the atmosphere and ocean here we show that current parameterizations of this turbulent mixing lead to systematic and substantial errors in the depth of the osbl in global climate models which then leads to biases in sea surface temperature one reason we argue is that current parameterizations are missing key surface wave processes that force langmuir turbulence that deepens the osbl more rapidly than steady wind forcing scaling arguments are presented to identify two dimensionless parameters that measure the importance of wave forcing against wind forcing and against buoyancy forcing a global perspective on the occurrence of wave forced turbulence is developed using re analysis data to compute these parameters globally the diagnostic study developed here suggests that turbulent energy available for mixing the osbl is under estimated without forcing by surface waves wave forcing and hence langmuir turbulence could be important over wide areas of the ocean and in all seasons in the southern ocean we conclude that surface wave forced langmuir turbulence is an important process in the osbl that requires parameterization citation belcher s e et al 2012 a global perspective on langmuir turbulence in the ocean surface boundary layer geophys res lett 39 l18605 doi 10 1029 2012gl052932

climate and sea level during oxygen isotope stage 7b on land evidence from new zealand abstract strata at landguard bluff near wanganui new zealand preserve a clear record of relative sea level changes during oxygen isotope stage 7 two relative high sea level stands during stages 7a about 210 000 yr ago and 7c about 240 000 yr ago are separated by a relative low sea level stage 7b that was at least 32 m lower than present pollen analysis of sediment deposited during stage 7b indicates climate at the time was up to 3 c cooler than present the climate and sea level evidence from landguard bluff are consistent with oxygen isotopic evidence from deep sea cores indicating a marked cooling during stage 7 which is closely associated with a summer radiation minimum centered at about 230 000 yr ago in the northern hemisphere

the transition from downward to upward air sea momentum flux in swell dominated light wind conditions fifteen hours of consecutive swell data from the experiment flux etat de la mer et teledetection en condition de fetch variable fetch in the mediterranean show a distinct upward momentum flux

amino acid geochronology resolution and precision in carbonate fossils changes in indigenous proteins preserved in carbonate skeletons can be used to estimate the time elapsed since death of the organism racemization the most widely used reaction in amino acid geochronology refers to the inversion of l amino acids to their d configuration for the protein amino acid l isoleucine racemization occurs about only one of the two chiral carbon atoms this reaction epimerization proceeds from an initial dl ratio near zero to an equilibrium ratio of about 1 30 the reaction rate is controlled primarily by temperature and to a lesser degree by the nature of the proteins themselves a variable related to taxonomy and the extent of protein degradation analyzing monospecific samples minimizes the taxonomic variable the resolving power of dl ratios as relative age indices is a function of the reaction rate degree of natural variability and analytical uncertainty natural variability is defined as the spread in ratios in five well preserved shells of the same age from a single stratum and is primarily related to taxonomy it can range from 20 or more in taxa of low reliability to 1 in taxa of greatest integrity 5 to 10 is to be expected analytical uncertainty within a single laboratory is relatively insignificant amounting to no more than 2 but interlaboratory comparisons suggest caution in comparing ratios determined at different laboratories or by different techniques sampling appropriate portions of a shell is essential to minimize variability in dl ratios site temperature exerts the greatest control on reaction rate hence resolving power for tropical sites 25 c age differences 1 ka can be resolved within the holocene and ca 5 to 10 ka for older samples as the rate decreases equilibrium is attained after 150 to 300 ka the reaction rate is substantially lower at mid latitude sites ca 10 c where equilibrium requires about 2 ma and resolution within the last glacial cycle is no better than 10 to 20 ka arctic sites 10 c show almost no measurable racemization within the holocene and in extreme cases even within the last 100 ka equilibrium is not attained in 10 ma the extent of amino acid racemization epimerization in carbonate fossils provides chronological information for the critical time period beyond radiocarbon dating dl ratios can be used directly as relative age indices and with suitable calibration can provide reasonable estimates of absolute age and or effective diagenetic temperature improving the accuracy of racemization based age estimates requires a better understanding of racemization kinetics in carbonate systems

boundary layer development and gravity waves in conventionally neutral wind farms while neutral atmospheric boundary layers are rare over land they occur frequently over sea in these cases they are almost always of the conventionally neutral type in which the neutral boundary layer is capped by a strong inversion layer and a stably stratified atmosphere aloft in the current study we use large eddy simulations les to investigate the interaction between a large wind farm that has a fetch of 15 km and a conventionally neutral boundary layer cnbl in typical offshore conditions at the domain inlet we consider three different equilibrium cnbls with heights of approximately 300 m 500 m and 1000 m that are generated in a separate precursor les we find that the height of the inflow boundary layer has a significant impact on the wind farm flow development first of all above the farm an internal boundary layer develops that interacts downwind with the capping inversion for the two lowest cnbl cases secondly the upward displacement of the boundary layer by flow deceleration in the wind farm excites gravity waves in the inversion layer and the free atmosphere above for the lower cnbl cases these waves induce significant pressure gradients in the farm both favourable and unfavourable depending on location and case a detailed energy budget analysis in the turbine region shows that energy extracted by the wind turbines comes both from flow deceleration and from vertical turbulent entrainment though turbulent transport dominates near the end of the farm flow deceleration remains significant i e up to 35 of the turbulent flux for the lowest cnbl case in fact while the turbulent fluxes are fully developed after eight turbine rows the mean flow does not reach a stationary regime a further energy budget analysis over the rest of the cnbl reveals that all energy available at turbine level comes from upwind kinetic energy in the boundary layer in the lower cnbl cases the pressure field induced by gravity waves plays an important role in redistributing this energy throughout the farm overall in all cases entrainment at the capping inversion is negligible and also the work done by the mean background pressure gradient arising from the geostrophic balance in the free atmosphere is small

magnetostratigraphic lithostratigraphic and tephrostratigraphic constraints on lower and middle pleistocene sea level changes wanganui basin new zealand wanganui basin north island new zealand contains a complex sedimentary record of lower and middle pleistocene sea level changes palaeomagnetic results allow identification of the matuyama brunhes transition the jaramillo subchron and the cobb mountain subchron correlations of rhyolitic tuff horizons across the basin are consistent with magnetostratigraphic correlations between sections isothermal plateau fission track itpft ages of 1 05 0 05 ma and 1 63 0 15 ma on two tuffs potaka pumice and pakihikura pumice respectively are consistent with the interpreted magnetostratigraphy and also with the astronomically tuned timescale of odp site 677 magnetostratigraphy and itpft ages allow correlation of sedimentary cycles at wanganui with odd numbered oxygen isotope stages 17 31 in deep sea cores the stratotype section for the new zealand castlecliffian stage is shown to be incomplete relative to other studied sections in the basin below stage 31 the character of the cyclothems changes at wanganui from marine dominated to a greater representation of non marine and estuarine strata this change may be partly related to a change in amplitude and frequency of climatic cycles identified in oxygen isotope records but the primary cause is likely to be increased basinal uplift

palaeomagnetic location of the jaramillo subchron and the matuyama brunhes transition in the castlecliffian stratotype section wanganui basin new zealand abstract magnetostratigraphy is described for the lower part of the castlecliff section in wanganui basin new zealand based on analysis of multiple samples from 37 horizons the castlecliff section is the stratotype of the middle pleistocene castlecliffian stage and comprises eleven unconformity bound sequences which accumulated at inner shelf depths during interglacials a range of rock magnetic experiments undertaken on representative lithologies within the section show that the bulk of the remanence in all specimens is carried by ferrimagnetic mineral close to magnetite in composition in the stable single domain or pseudo single domain size range however at some sites post depositional chemical changes appear to have produced small amounts of another ferrimagnetic mineral chiefly within the superparamagnetic single domain size range resulting in hard secondary components of magnetization nevertheless at most sites the primary component of remanence was clearly identified by stepwise demagnetization four magnetozones are identified and these can be correlated to the magnetic polarity time scale using existing biostratigraphic constraints the section sampled spans the interval from below the jaramillo subchron to above the matuyama brunhes boundary the matuyama brunhes transition extends over 10 5 m of section within the upper westmere siltstone virtual geomagnetic pole positions describe an equatorial excursion in an otherwise far sided transition path these represent the first published data on the occurrence of the matuyama brunhes boundary on land in new zealand

subdividing the pleistocene using the matuyama brunhes boundary mbb an australasian perspective abstract the last major reversal of the earth s magnetic field the matuyama brunhes boundary mbb dated at 0 78 ma is widely identified in australian and new zealand pleistocene deposits in new zealand the mbb is precisely located in shallow marine sediments of wanganui basin where it corresponds with the base of the new zealand putikian substage a combination of marine biostratigraphy sequence stratigraphy and tephrostratigraphy permit correlation from wanganui basin to other on land sections and deep sea cores in australia the mbb is identified in many continental sequences particularly saline lake basins however chemical weathering has resulted in variable brunhes age normal overprints that are sometimes difficult to remove australasian tektites are a potential lithostratigraphic marker just prior to the mbb but have yet to be identified in the same on land section as the mbb in australia identification of reverse polarity magnetisation in weathered deposits including soils provides a minimum age of 0 78 ma for these materials a widespread arid shift in paleoclimate succeeded the mbb in australia placement of the lower middle pleistocene boundary at the mbb would constitute the most recognisable chronostratigraphic marker in weathered continental deposits

amino acid geochronology of pleistocene marine sediments in the wanganui basin a new zealand framework for correlation and dating amino acid analysis of indigenous protein preserved in fossil marine bivalves from plio pleistocene sediments in the wanganui basin north island new zealand has provided an aminostratigraphy d alloisoleucine l isoleucine d aile l ile ratios were measured in the venerid marine bivalves tawera spissa and austrovenus stutchburyi that show progressively increasing d aile l ile ratios with increasing stratigraphical age when calibrated by magnetostratigraphy fission track dating radiocarbon dating and coccolith biostratigraphy these relative d aile l ile ages range up to c 1 ma the aminostratigraphy provides a framework of correlation and dating for other sites in the new zealand area where other methods of dating are unavailable as well as facilitating correlation with oxygen isotope stratigraphy this is the first calibrated aminostratigraphical sequence from a long sequence of sediments that cover a significant proportion of the pleistocene

use of conventional stability parameters during swell the situation with swell is of climatological importance over the baltic sea since swell is present during as much as 40 of the time in this study two periods with unstable and two periods with stable stratification and wind following swell are investigated data are taken at a small flat island in the baltic sea during unstable stratification the turbulent structure shows great resemblance to the free convective boundary layer and scales with the boundary layer height since surface heat flux is too small to support the high levels of turbulence present inactive turbulence is probably the dominating source for the stably stratified layer there are smaller differences between data with and without swell the turbulence is mainly transported upward into the atmosphere with the aid of pressure fluctuations induced by the waves for most of the data with swell the gradients are smaller than for growing sea during unstable conditions the wind gradients are negative indicating the presence of a wave driven wind the gradients increase with increasing height above the surface the drag coefficient is smaller than is usually found for both stable and unstable stratification and varies very little with wind and stratification there are only small variations in the heat transfer coefficients with changing stratification but they are significantly different for stable and unstable stratification

swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere wave model over the ocean the atmospheric turbulence can be significantly affected by swell waves change in the atmospheric turbulence affects the wind stress and atmospheric mixing over swell waves in thi

isothermal plateau fission track ages of tephra beds in an early middle pleistocene marine and terrestrial sequence cape kidnappers new zealand abstract at least nine rhyolitic eruptive events or sequences are interbedded with alternating marine and terrestrial sediments of early middle pleistocene age at cape kidnappers new zealand the sediments represent one of the few high resolution glacio eustatic sea level records in new zealand we have obtained ages of 0 99 0 09 1 00 0 10 0 86 0 05 and 0 79 0 06 ma in ascending stratigraphic order for four prominent tephra beds from isothermal plateau fission track dating of their glass shards these ages are older than previous fission track determinations but are in agreement with tephra correlations to other sections ar ar data and magnetostratigraphy however the upper part of the sequence previously interpreted as the brunhes chron may have been affected by normal overprinting and is instead older the tephra record suggests a higher frequency of eruptions than is indicated by the proximal ignimbrite record in the taupo volcanic zone the new tephra ages indicate that the section was deposited in the interval 1 0 0 65 ma at a rapid average sedimentation rate of ca 1 m ka

land sea correlations in the pleistocene based on isoleucine epimerization in non marine molluscs the correlation between the oxygen isotope stratigraphy of the oceans and continental stratigraphic records is one of the main challenges for quaternary research most continental classifications however are based on techniques and hypotheses that predate recent advances nevertheless the deep sea oxygen isotope global stratigraphic framework has been extended to the continents by means of some long sequences1 but these are exceptional and regional geology is unsatisfactorily classified for correlation with the oxygen isotope signal because successive geological events produced similar evidence homotaxis geochronometric dating is essential for correlation but available methods are highly site regional or sample specific fortunately non marine molluscs are ubiquitous in time and space and here we use the time dependent epimerization of l isoleucine in these fossils to subdivide the pleistocene of the british isles and to identify more events than recognized by the existing classification2 by calibrating the relative aminostratigraphic scale with independent dating methods we have set up a geochronology which is the basis for land sea correlations back to oxygen isotope stage 15

early to middle pleistocene tephrochronology of north island new zealand implications for volcanism tectonism and paleoenvironments thick volcaniclastic sequences of early to middle pleistocene age in southern north island new zealand contain rhyolitic tephra beds that record the early history of the taupo volcanic zone tvz at least 54 different tephra beds are recorded and their chronology is defined by glass fission track ages and paleomagnetism the tephra beds span the interval ca 2 0 0 6 ma and provide an event frequency of 1 19 k y significantly higher than the frequency of sheet forming ignimbrites preserved in the tvz at this time 1 100 k y the distal tephra beds thus provide a record of volcanism not revealed in the proximal volcanic region and suggest a major period of explosive activity at ca 1 79 1 60 ma several important marker horizons are identified pakihikura tephra 1 63 ma mangatewaiiti tephra 1 24 ma potaka tephra 1 00 ma kidnappers b tephra 1 00 ma and kaukatea tephra 0 88 ma these tephra beds allow direct correlation between 1 marine and nonmarine facies and 2 the fore arc and back arc regions of new zealand the tephra beds provide a framework for a paleoenvironmental reconstruction of the southern north island volcaniclastic transport routes from the tvz to basins in the south and southeast and through the site of present mountain ranges supplied material to a terrestrial lowland fore arc area in the interval 1 64 0 7 ma uplift and deformation since 0 7 ma have disrupted paleodrainage routes diverting them to the north and southwest

revision of the marine chronology in the wanganui basin new zealand based on the isothermal plateau fission track dating of tephra horizons abstract the occurrence of tephra horizons in basins adjacent to volcanic arcs provide an excellent opportunity for establishing a reliable chronostratigraphic framework for detailed sedimentological studies in this study three widespread and stratigraphically important rhyolitic tephra horizons interbedded in plio pleistocene strata of the wanganui basin new zealand are dated by application of the isothermal plateau fission track itpft technique to hydrated glass shards all glass samples were corrected for annealing and consequently yield reliable ages rangitawa tephra yielded statistically indistinguishable ages from three localities that are in excellent agreement with recently determined zircon fission track age estimates of ca 0 35 ma itpft ages of 1 05 0 05 and 1 63 0 15 ma for potaka pumice and pakihikura pumice respectively are considerably older than previous ft estimates but consistent with new magnetostratigraphic data that places the potaka within the jaramillo subchron and pakihikura within the matuyama chron between the cobb mountain and olduvai subchrons combining our fission track ages with the magnetostratigraphy the true age of sediments within the wanganui basin is found to be significantly underestimated sedimentation rates of between ca 680 630 m ma from 1 63 ma to 0 35 ma are calculated in the eastern part of the basin and are much lower than those calculated using the previous ft chronology this new itpft age data demonstrates that the existing plio pleistocene marine chronology in new zealand will require age revision and has important implications when considering the evolution of several other sedimentary basins in southern north island that contain the same itpft dated tephra horizons

surface wave dynamics in delaware bay and its adjacent coastal shelf this study presents a broad overview of surface gravity wave dynamics in delaware bay and the adjacent continental shelf by employing the wave model simulating waves nearshore one way coupled to the ocean model regional ocean modeling system for a period from 2006 2012 the distributions of simulated wave statistics agree well with observations obtained from three wave buoys located on the shelf in the bay near the open ocean and about 35 km up the bay a partitioning analysis to separate the two dimensional wave height spectrum into wind forced and swell parts reveals that waves on the shelf are predominantly remotely generated swell bathymetric refraction shelters the bay from energetic open ocean waves which is supported by an idealized ray tracing analysis waves near the bay entrance are also refracted by oblique tidal currents whose refraction characteristics critically depend on the detailed spatial distributions of the currents opposing tidal currents flowing against the wave propagation direction focus wave energy outside the bay entrance and in the deeper bay channels where currents are relatively strong a spectral partitioning analysis for waves in the bay indicates that less energetic wave fields are likely not directly forced by the wind more energetic waves on the other hand are dominantly driven by winds and the wave response in the bay depends on the fetch setting wind direction our results for wind driven waves in the bay are consistent with previous fetch limited observations but we find a systematic bias between wind and wave directions due to bathymetric refraction

the near neutral marine atmospheric boundary layer with no surface shearing stress a case study abstract data from a marine coastal experiment over the baltic sea comprising airborne measurements and mast measurements have been used to highlight the turbulence dynamics of a case with most unusual flow characteristics the boundary layer had a depth of about 1200 m the thermal stratification was near neutral with small positive heat flux below 300 m and equally small negative heat flux above the entire situation lasted about 6 hours turbulence levels were unexpectedly high in view of the fact that momentum flux was negligible in fact positive in the layers near the surface and buoyancy flux was also small the turbulence was found to scale with the height of the boundary layer giving rise to velocity spectra having the shape of those characteristic of convectively mixed boundary layers analysis of the turbulence budget for the entire planetary boundary layer pbl revealed that energy was produced from shear instability in the uppermost parts of the pbl and was distributed to the lower par