the energy source for the coastal trapped waves in the australian coastal experiment region abstract the sea level on the southern australian coast is examined for the source of the coastal trapped wave energy observed during the australian coastal experiment sea level adjusted for atmospheric pressure and atmospheric pressure are observed to propagate eastward at about 10 m s 1 at the lowest frequency examined 24 day period some energy travels south along the west coast of tasmania but does not reach the east coast of mainland australia while some energy travels through bass strait to reach the east coast of mainland australia at the most energetic frequency 8 day period adjusted sea levels are coherent over the 3700 km of coastline from southern australia to the east coast and much of the wind forced coastal trapped wave energy appears to travel through bass strait to the mainland east coast we have not identified a mechanism for energy transfer through bass strait and we do not know what fraction of the coastal trapped wave energy incident on western bass strait actually reach

flow and fabric development during the diapiric rise of magma scaled isothermal experiments of the internal circulation induced by viscous drag at a diapir country rock interface are compared with published theoretical studies of flow induced finite deformation inside a rising sphere and new numerical results are presented for the incremental strain pattern developed in spherical diapirs the results predict a time dependent deformation history within rising diapirs that produces finite strains characterized by strong oblate flattening strains at the margin and strong vertical prolate strains in the center with an intervening zone of low plane strain finite strains are discussed in terms of the different sub fabrics expected to form in granitoids after considering the history of rheology and temperature distribution in rising magma strong rheological and temperature gradients are predicted for the margins of internally circulating diapirs that can lead to the formation of strong penetrative foliations at the margin and magmatic or even isotropic fabrics in the i

australasian asphaltite strandings their origin reviewed in light of the effects of weathering and biodegradation on their biomarker and isotopic profiles abstract asphaltites long known to strand along the coastline of southern australia and as distantly as new zealand and macquarie island are widely regarded as artefacts of submarine oil seepage their remarkably uniform composition suggests a common source marine shale containing sulphur rich type ii kerogen probably deposited during an early cretaceous oceanic anoxic event oae suitable hydrocarbon kitchens may exist in the offshore bight and otway basins the physical character of the asphaltites including laminations and flow structures and their degree of alteration which is not the result of biodegradation or extensive water washing suggest an origin from subsurface tar mats subsequently exposed by the incision of submarine canyons with the possible formation of asphaltic volcanoes api gravities of 4 18 impart quasi neutral buoyancy implying many asphaltites were submerged drifters prior to stranding their degree of weathering reflecting at least in part the residence time in the marine environment for any individual asphaltite specimen this will depend on the proximity of the seafloor seep to the stranding site an important consideration when attempting to locate their point of origin this study investigates the hydrocarbon biomarker signatures and n alkane 13 c profiles of asphaltite specimens from stranding sites on the eyre peninsula n 2 kangaroo island n 4 and the limestone coast n 3 south australia and the south island of new zealand n 2 sub samples of the interior and weathered surface of each specimen were analysed no distinction could be made between strandings based on their source dependent molecular and isotopic signatures confirming their common origin comparison of the interior and exterior sub samples revealed subtle although consistent differences given their degree of degradation and isotopic variance these australasian asphaltites seem to be products of low intensity seeps in the ceduna sub basin of the bight basin and or morum sub basin of the otway basin

regional tilt of the mount stuart batholith washington determined using aluminum in hornblende barometry implications for northward translation of baja british columbia we have developed a new quantitative method to estimate paleohorizontal in granitic plutons using the aluminum in hornblende ah barometer the method is used to correct previously published paleomagnetic data from the 93 96 ma mount stuart batholith of the cascades mountains washington state for the effects of postemplacement tilting ah barometry was done on 46 samples from the batholith using the compositions of hornblende rims coexisting with the full mineral assemblage required for pressureestimation high contrastback scatteredelectronimagingwas usedtoensurethattheanalyzedhornblendeswerenotsignificantly affected by subsolidus alteration the success of the ah barometry is indicated by two observations first increases in the al content of the hornblendes are governed almost entirely by a pressure sensitive tschermak type substitution second amphibole plagioclase thermometry indicates that assemblage equilibration occurred at or very near magmatic conditions 650 c and that temperature has a negligible effect on our pressure estimates ah barometry results indicate that the depth of crystallization across the batholith decreases systematically from 0 3 gpa in the northwest to 0 15 gpa in the southeast consistentwithindependentbarometryforthecontactaureole ofthebatholithandregionalstructuralandstratigraphicrelations using a best fit planar tilt model and bootstrap analysis of uncertainties we estimate that the paleohorizontal plane has a strike of 43 630 4 and dip of 7 62 0 southeast 695 confidence our estimated paleohorizontal allows us to restore the paleomagnetic data of beck et al 1981 and to estimate the original paleolatitude of the mount stuart batholith beck et al found that the southern part of the batholith yielded a number of sites with a well defined high coercivity remanence the carrier of this remanence was not resolved but the following four lines of evidence stronglysuggestthatthepublisheddirectionswereacquiredshortly after emplacement of the batholith 1 the stable sites all came from the shallowest and most rapidly cooled portions of the batholith as indicated by our ah results and concordant k ar ages for hornblende biotite pairs 2 the high coercivity component was always normal in polarity which is consistent with emplacement of the mount stuart batholith at the end of the cretaceous long normal 3 sites from the batholith and the contact aureole gave similar directions 4 the directions show no indication of tilt related smearing after restoration the paleomagnetic data indicate 42 6 11 clockwise rotation and 3100 6 600 km of northward offset

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

the mean summertime circulation along australia s southern shelves a numerical study abstract for the first time a high resolution regional model is developed for the slope and shelf circulation within the great australian bight and for the gulfs region of south australia the results indicate the extent nature and dynamical interaction of a variety of circulation features that are most likely to be important for the region in particular the positive wind stress curl south of australia leads to an equatorward sverdrup transport in the deep ocean westward flinders current along the slope and upwelling of the 600 m deep permanent thermocline the wind stress curl also leads to a seaward topographic sverdrup transport within the wide sloping shelf of the bight and results in an anticyclonic gyre that is intensified off the eyre peninsula and reduced in magnitude by the joint effect of baroclinicity and topographic relief in the western half of the bight the seaward surface ekman and topographic transports are shown to converge with the onshore component of the flinders current lea

late quaternary productivity changes from offshore southeastern australia a biomarker approach reconstructions of primary productivity at low latitudes have been the focus of several studies to better understand how the export of nutrient rich intermediate southern ocean so waters influences productivity at these latitudes this was triggered by the general observation of minima in the planktonic foraminiferal delta c 13 values during deglaciations which was interpreted as an isotopic signal of intermediate so waters together with a concomitant increase in diatom productivity at some equatorial sites however the impact of these so waters on productivity at higher latitudes is not well constrained here we compare a high resolution planktonic foraminiferal delta c 13 record with total organic carbon and biomarker records for proboscia diatoms and haptophytes in marine sediments from offshore southeastern australia the planktonic foraminiferal delta c 13 record shows distinct minima during deglaciations and the marine isotope stage 4 3 transition tentatively suggesting that c 13 depleted so waters reached the coast of southeastern australia however it did not result in increased productivity during these periods instead the highest primary productivity period as indicated by total organic carbon and alkenone accumulation rates occurred during the last glacial maximum while proboscia diatoms mainly proliferated during interglacials and marine isotope stage 3 matching periods of increased diatom productivity in some sites of the eastern equatorial pacific our study suggests that increased primary productivity offshore southeastern australia was mainly due to stronger westerly winds during glacial periods while proboscia diatom productivity was probably controlled by the transport of silicic acid to this area

the circulation south of australia derived from an inverse model an inverse model is used to determine circulation and volume transports in the australian sector of the southern indian ocean from observations during woce water movement in the upper 1000 m is westward along the continental slope and eastward in the subantarctic front saf the subtropical front is not associated with continuous eastward flow however such flow appears to build up between 120 e and 132 e where it dominates the region between 37 s and 42 s antarctic intermediate water is found to move from the pacific into the indian ocean except in the region of the saf where it moves from the indian to the pacific ocean circumpolar deep water exhibits weak flow which can only be reliably resolved in the upper part where it is predominantly westward antarctic bottom water enters the australian basin through two depressions in the australian antarctic discordance at 125 37 e and at 126 30 e

inland shell midden site formation investigation into a late pleistocene to early holocene midden from trang an northern vietnam over the course of the past two decades there has been growing research interest in the site formation processes of shell middens this stands along side and is being used to inform cultural dietary and palaeo environmental reconstructions just as midden site formation processes have turned out to be many and varied however the kinds of shell bearing sites that past human communities created are likely to have been no less diverse subsuming such sites under a single category shell middens normalises that variation and may lead to the misinterpretation of site function the greater part of research in this field also continues to focus on coastal shell middens comparatively little attention has been paid to middens containing freshwater and especially terrestrial molluscs from hinterland locations as a result much of the current understanding about shell midden sites carries a spatial as well as a functional bias this paper hopes to contribute towards discussion on both fronts it presents a detailed examination of the formation processes that went into the creation of a land snail dominated late to post glacial midden from northern vietnam and considers the role that it may have played in the early settlement of this area the data presented comes from ongoing archaeological excavations at hang boi a cave located in the sub coastal karstic uplands of trang an park in the vietnamese province of ninh binh

wind forced setup of upwelling geographical origins and numerical models the role of bottom drag 1 an analysis is made to determine the properties and scales for the setup of upwelling driven by an impulsively started steady uniform wind of semi infinite fetch the backward edge of the wind field acts as a geographical origin for the generation of coastal trapped waves ctws a perturbation analysis is used to show that prior to the arrival of the nth mode ctw the alongshore velocity is shown to asymptote to a constant value set by bottom drag and over a timescale tn as this viscous limit is achieved the upwelling becomes increasingly confined to the bottom boundary layer and bottom stress balances wind stress interior upwelling is shut down the viscous limit may not be achieved since after the arrival of the nth ctw mode a gradient in the alongshore velocity is set up and its divergence acts to feed the offshore ekman transport and shut the upwelling down numerical results are used to show that the frictional length and timescales predicted by the perturbation analysis are unrealistically small due to an underestimation of thermal wind shear moreover the theory underpredicts the importance of the first ctw mode which is shown to largely determine the setup and shutdown of upwelling a simple first mode model for upwelling is developed and used to evaluate the validity of a numerical open boundary condition in determining the correct degree of upwelling a case study for the chilean shelf is presented

speculated cause of interhemispheric oceanic oscillation the study of large scale correlations of atmospheric and oceanic variables on a supra annual scale is essential for an understanding of climatic variability we present here new data on the mean sea level anomalies in the eastern indian ocean which are consistent with supra annual anomalies in the intensity of the main oceanic gyre and are negatively correlated with mean sea level anomalies in the eastern pacific ocean larger anomalies are induced in the indian ocean probably due to its smaller size and zonal mean stratospheric 50 mbar geopotential heights at 10 n 20 n and 30 n are better correlated with the indian ocean than with the pacific ocean mean sea levels it is speculated that the reported responses are due to a random variation of the monsoonally generated heat transport between the oceans this variability would give rise to equatorial heat anomalies in each ocean which induce the observed changes in mean sea level and the coupled changes in the sub tropical atmospheric circulations

from source to sink a new perspective on the past dynamics of the murray canyon group from benthic foraminiferal communities abstract we present fossil benthic foraminiferal assemblage data from marine sediment core ss02 06 gc2 located in the abyssal plain of the murray canyon group offshore south australia the sedimentological characteristics indicate the presence of turbidite deposits showing classical bouma like sequences dated between 40 and 12 cal ka bp these results confirm the previous interpretation of the observed large deep water holes in the abyssal area where the core was sampled as being gouged by surges of high energy turbidity currents the presence of good indicator taxa and unique assemblages occupying specific bathymetric depths allows the determination of the source origin of the sediments making the turbidites three distinct faunal groups are found 1 mostly shelf species 2 mostly bathyal species and 3 mostly abyssal species in the sediment core these groups present a quasi systematic succession with nearly all bouma like sequences starting with the dominance of bathyal species in the coarse grained base followed by the dominance of shallow species in the silty part and finally with abyssal species in the clays to explain such phenomena turbidites triggered by mixed hyperpycnal hypopycnal flow processes and turbidity currents during periods of river floods are considered for the first time within the murray canyon group they are mostly related to periods of increased fluvial discharges during wet phases in the murray darling basin

simulation of shelf averaged water properties with application to the south coast of australia abstract a method for simulating shelf averaged properties for vertically well mixed water on a strip of continental shelf is presented the conservation equations for temperature and salt are solved making use of air temperatures evaporation and rainfall rates and temperature and salinity data from the adjacent ocean and the ends of the strip together with coastal current transports the transports have been estimated from the longshore variation of wind stress and depth integrated longshore density gradient using a theoretical expression the resulting shelf distributions are interpreted as a summation of signals deriving from processes occurring in specified segments of the strip of continental shelf shelf anomalies the ends of the strip boundary anomalies and from the longshore property variation in the adjacent ocean oceanic anomalies negative oceanic temperature anomalies indicate cool advection which supports upwelling and positive oceanic temperature anomalies warm advection shelf anomalies quantify the modification of water properties on the shelf by meteorological forcing solutions are discussed for the annual cycle along the continental shelf of southern australia in which the importance of advective processes is evident in the salinity distribution but is masked in the temperature distribution by opposing oceanic and shelf anomalies

archaeological formation theory and geoarchaeology state of the art in 2016 since the influential work of michael b schiffer on formation processes has been published in 1987 much has advanced on the part of environmental formation processes also known as n transforms most new knowledge is the result of research conducted by geoarchaeologists on the theoretical level a huge leap forward was made with the realization that occupation deposits are artifacts of human activity the focus of formation theory thus shifted from the artifact to the deposit methodological innovations and a geoarchaeological tool kit notably including the contextual technique of micromorphology followed empirical studies of archaeological occupation deposits contributed new spatial and stratigraphic knowledge and understanding a holistic middle range methodology termed geo ethnoarchaeology was developed whereby macroscopic and microscopic artifacts are studied together with their associated sediments in ethnographic contexts providing contextual social information about the relationship between artifacts and the surrounding sediments as archaeological assemblages form this method is especially powerful when sequentially dated abandoned settlements or features are studied to provide mechanistic understanding of assemblage and or site formation through degradation because geo ethnoarchaeology is based on general chemical biological and physical laws the resultant mechanistic models are applicable globally for any time period culture and environment the new tools and mechanistic understanding by which n transforms are currently studied provide means to more reliably interpret the archaeological record which is crucial for the credibility of archaeology therefore when studying archaeological assemblages one should utilize the tool kit developed by geoarchaeologists to first assess the states of preservation of the various material assemblages macroscopic and microscopic as it should be borne in mind that assemblages identified to be well preserved will produce the most reliable archaeological interpretation the theory and method of geoarchaeology have matured enough to allow responsible archaeological research into the meaning of spatial and temporal stratigraphic patterns at any given site

long term coastal upwelling over a continental shelf slope abstract long term coastal upwelling over a continental shelf slope with emphasis on the planetary dispersion of rossby waves is studied with numerical models the ocean is forced by a wind stress with a limited longshore extent the thermocline intersects the shelf slope and the internal radius of deformation is smaller than the width of the shelf slope two case studies with and without the effect are studied lie early stage response within a week or so is similar between the two for an f plane case the whole stage response is accounted for by coastal trapped wave dynamics and only equatorward flow exists over the shelf slope at an advanced stage however inclusion of the effect leads to a significant change in the alongshore flow pattern at the advanced stage due to the westward rossby dispersion of the equatorward flow associated with the first and second coastal trapped mode responses the poleward undercurrent develops in the thermocline layer over the shelf the time for the undercurrent

groundwater response to the tide in wetlands observations from the gillman marshes south australia we present results from a series of piezometers installed in the foreshore flat and mangrove environments of the gillman marshes south australia in an interdisciplinary study of the propagation of the ocean tide into the coastal aquifers a unique feature of the analysis is that all water level records were harmonically analysed so that the behaviour of the four major tidal constituents could be independently examined the main findings were that 1 the decay of the groundwater tide in the coastal aquifers was greater than that predicted by the ferris solution a theoretical model has been developed and applied to the study site the model suggests that this behaviour is due to the occurrence of a time delay in the darcian response in the shelly and muddy sand substrate 2 when the tide is incident over a gently sloping bank the time delay in response gives rise to a spiked signal in which high water is confined to a small fraction of the tidal cycle and 3 at the coastal interface tidal propagation across a sloping bank causes a rise in the water table relative to mean sea level which is proportional to the variance of tidal elevation and inversely proportional to the decay constant of the groundwater tide the model developed in this study is also applicable to other coastal groundwater systems with tidal influence

a northern boundary current along australia s southern shelves the flinders current 1 south of australia the monthly mean wind stress curl is positive during both summer and winter and leads to ekman pumping and downwelling throughout the region sverdrup dynamics indicates that this downwelling should lead to a northward transport of around 5 10 sv 1 sv 10 m3 s 1 classical arguments for western boundary currents are adapted to show that this transport should be deflected into an upwelling favorable boundary current that flows from east to west along australia s southern shelves the flinders current support for this proposition is obtained from results of the ocean circulation and climate advanced modelling project occam sverdrup transports and limited observations for the region in addition the occam results show that the northward transport leads to upwelling at depths below 400 m and that the flinders current 1 intensifies from victoria to western australia transport 8 sv with speeds up to 15 cm s 1 2 can extend from the surface to depths of 800 m and 3 is found during both summer and winter during winter the winds are downwelling favorable and lead to a coastal current that flows from west to east and opposes the flinders current further support for the origin and nature of the flinders current is obtained from simple numerical experiments made using a rectangular domain and idealized representations of the summer and winter wind stress

circulation near submarine canyons a modeling study circulation near a submarine canyon is analyzed with a numerical model previous theoretical work indicated that stratification controlled the interaction of coastal flow with canyons specifically the ratio of canyon width to the internal radius of deformation a wide canyon was thought to merely steer the flow while a narrow canyon would create substantial cross shelf exchange four cases are analyzed considering two directions of alongshore flow and two choices of initial stratification the weakly stratified case has an internal radius about equal to the canyon width while the strongly stratified case has one about 3 times the canyon width the direction of the alongshore flow is shown in this study to be the more important of the two factors in particular right bounded flow flow with the coast on the right looking downstream in the northern hemisphere leads to shallow downwelling in the canyon and weak exchange across the shelf break while left bounded flow creates upwelling at the head of the canyon and strong exchange between the ocean and shelf in left bounded flow upwelling dense water is pumped onto the shelf even for strong stratification however the stratification limits the vertical extent of the topographic influence so that the alongshore flow above the canyon is only weakly affected in the strongly stratified case with any level of stratification the surface temperature density is not modified at all by the flow interaction with the submarine canyon the important dynamics involve pressure gradients and coriolis acceleration and how they interact with the bathymetric gradients but not advection of momentum advection of density is clearly important in the upwelling cases finally continued upwelling onto the shelf acts as a drag mechanism and retards the alongshore coastal flow

composition and genesis of temperate shallow marine carbonate muds spencer gulf south australia abstract the origin of carbonate muds grain sizes 63 m in shallow nontropical marine environments is poorly documented coarse grained carbonates often characterize coastal temperate seafloors but many such deposits also have abundant carbonate muds spencer gulf a large shallow embayment along the southern australian margin 60 m water depth contains mixtures of carbonate gravels sands and muds with muds constituting up to 84 volumetrically benthic environments include dense seagrass meadows sand barrens and rhodolith pavements where bivalves benthic foraminifera coralline algae and bryozoans dominate heterozoan carbonate assemblages mud grain morphologies were investigated using scanning electron microscopy leading to the conclusion that muds are predominantly composed of skeletal fragments bivalves benthic foraminifera ascidians echinoderms and coralline algae interpreted to have formed due to breakdown of rigid material via maceration x ray diffraction analysis confirms that these muds contain combinations of intermediate mg calcite low mg calcite and aragonite with concentrations varying among locations according to skeletal grain types spencer gulf muds differ in mineralogy and composition from those of classic models of tropical and deep water carbonate mud deposition unlike shallow water tropical carbonate muds these temperate muds are not dominated by aragonite and there is no evidence of carbonate precipitation from seawater pelagic organisms contribute only trivial amounts to these deposits in contrast to deep water muds

earth wind and fire ethnoarchaeological signals of hadza fires we present the preliminary results of an interdisciplinary ethno geoarchaeological project aimed at characterizing sedimentary aspects of recent combustion structures through soil micromorphology to obtain empirical parameters with which to interpret archaeological features micromorphological analyses of five different types of fires made and abandoned by the hadza of tanzania were performed and compared with ethnographic descriptions their anthropogenic nature burning intensity and type of fuel used were identified based on the composition and optical features of the microscopic components of the combustion structure the data provided elements to assess the preservation potential of open air fires and our ability to interpret their function the life history of two of the fires was reconstructed a sleeping fire showed evidence of a pre existing trampled surface and a communal cooking fire showed evidence of the scooping out of ashes for maintenance these findings substantiate the important contribution of ethnoarchaeological research conducted jointly with soil micromorphology in discovering cues of human behavior preserved in the sedimentary record

buried in ashes site formation processes at lapa do santo rockshelter east central brazil few archaeological sites in the americas contain high concentrations of human burials dating back to the early holocene the tropical karstic region of lagoa santa in central brazil state of minas gerais is one of the richest bioanthropological records available to study the behaviors and funerary practices of early holocene south americans with more than 200 skeletons found so far one of the key locations to examine the history of human settlement in lagoa santa is the site of lapa do santo a rockshelter known to contain the oldest rock art and the earliest evidence of funerary complexity in the continent in this geoarchaeological investigation we focus on the early holocene settlement at lapa do santo 7 9 12 7 cal kybp applying high resolution geoarchaeological techniques such as micromorphology organic petrology and ftir on both archaeological modern reference and experimental samples this is the first time that a micro contextual approach integrated with experimental geoarchaeology has been applied to study the formation of rockshelter deposits in a tropical setting our results show that the stratigraphic sequence formed under the dual influence of anthropogenic sedimentation through continuous combustion activities and geogenic sedimentation in the form of oxisol aggregates which fell from above the limestone cliff into the rockshelter intact hearths and remobilized combustion debris possibly hearth rake out are close to the graves suggesting repeated burning activities as part of the ritual behavior of early holocene south americans large amounts of ash are intermixed with heated and unheated oxisol aggregates heated termite mound fragments were also found mixed within the sediments post depositional alteration of the site includes limited bioturbation and localized low energy surface water and sub surface concentrations of moisture leading to precipitation of dense secondary carbonates the age inversions can be attributed to the human action of reworking the ashy sediments and not to post abandonment processes despite this the overall preservation of the sediments is good and most human burials can be considered to be in primary context

the transition from magmatic to high temperature solid state deformation implications from the mount stuart batholith washington criteria for syntectonic emplacement of plutons are commonly ambiguous the strongest single criterion is probably the preservation of a continuous transition from submagmatic to high temperature solidstate deformation this transition is not commonly documented an exception is the mount stuart batholith which displays a variety of syntectonic structures within its sheared northeastern margin including the following 1 s c fabrics that range from submagmatic to high temperature solid state 2 solid state foliation and lineation defined by amphibolite facies assemblages that overprint and are parallel to magmatic foliation and lineation 3 folds of magmatic and solid state foliation that have hinge lines parallel to magmatic and solid state lineation and to equivalent structures in wall rocks 4 dikes that were folded and boudinaged over a wide range of rheological states with boudin necks locally filled by tonalite 5 pegmatite dikes and mineralized joints that are sub perpendicular to magmatic and solid state lineation and 6 submagmatic and high temperature solidstate ductile shear zones we suggest that many plutons emplaced during regional deformation do not preserve evidence for syntectonic deformation because of the transitory nature of the submagmatic state and the obscuring effects of postemplacement deformation syntectonic features are most likely preserved in plutons cooled at slow to moderate rates or in plutons deformed at high strain rates during emplacement the optimum conditions for preservation may occur in plutons emplaced along fault zones in the mid crust such as the mount stuart batholith and in intrusions at deeper levels that were rapidly exhumed and or intruded during the waning stages of regional deformation

δ18o and δ13c variability in brachiopods from modern shelf sediments and its utility for understanding complex oceanography southern australian shelf abstract the 18o and 13c values of brachiopod shell calcite are commonly used as proxies for ancient environmental marine conditions and secular changes in ancient ocean chemistry the variability of 18o and 13c across modern shelf settings is however not well documented this study presents 18o and 13c data from 407 holocene 5000 yr bp and living brachiopods collected from 220 sites across 3000 km along australia s southern shelf the largest cool water carbonate shelf in the modern world significant isotopic variability is present in separate specimens at individual sites and across the entire region individual specimens analyzed at multiple shell positions have an isotopic range of values up to 1 3 and 1 9 for 18o and 13c respectively multiple brachiopods at a single site have values that vary as much as 2 1 for 18o and 1 8 for 13c regional variability ranges on the order of 3 6 and 3 4 for 18o and 13c respectively the distribution of intrasite variability can be divided into areas of high and low variability areas characterized by low variability occur in zones of relatively consistent shelf water conditions high variability zones usually correspond to areas of seasonal upwelling onto the shelf and this aspect is interpreted to be the main cause of isotopic variability upwelling waters are cold leading to higher 18o values and are commonly rich in respired dissolved inorganic carbon dic and nutrients promoting active phytoplankton growth and leading to variable 13c values the extensive spatial coverage across this vast latitude parallel region provides a valuable baseline illustrating the isotopic range that could occur in a single layer in the rock record furthermore changes in isotopic signatures measured across stratigraphy might not necessarily reflect secular changes in ocean chemistry but instead could be recording local changes in shelf circulation and upwelling intensity

continental shelf wave propagation in the mid atlantic bight a general dispersion relation abstractthe authors address the propagation of continental shelf waves in the mid atlantic bight an analytical model of the bathymetry in the region is constructed by representing the continental shelf as a gently sloping bottom which deepens linearly with offshore distance to the place where it meets the continental slope seaward of that point the bathymetry is modeled with an exponentially decaying function of distance the linearized barotropic equations of hydrostatic motion subject to the long wave approximation yield separate shelf and slope solutions which are matched at the shelf break to specify the eigenfunctions the associated eigenvalues define the dispersion relations for each of the modes wavenumber frequency pairs derived from noaa sea surface height stations along the coast are plotted on the first mode dispersion curve and the agreement is good the theory also shows good agreement with the wave data of d p wang

deformation around a rising diapir modeled by creeping flow past a sphere a new experimental method for determining the pattern of flow and three dimensional progressive finite deformation of fluid elements in low reynolds number re viscous flow has been applied to creeping flow past a rigid sphere falling in a cylinder this is intended as a model analogue of natural rock deformation associated with magmatic and solid state diapirs rising through ductile crust the kinematics of finite strain in such analogue experiments may give useful information on the development of natural structures the experiment and a new method for quantifying the progressive finite deformation of fluid volumes in the transparent newtonian test fluid used sgm36 are discussed in detail the progressive finite deformation of fluid flowing along specific streamlines passing the sphere appears to be complex and largely a function of the initial distance of fluid volumes and the particular streamlines which they follow from the flow axis the progressive deformation history in the material surrounding a rising spherical diapir is characterized by progressive flattening and rotation of material above and progressive stretching below the sphere the results compare favorably with the external strain pattern associated with post tectonic mesozonal diapiric intrusions

climatic evolution in the australian region over the last 94 ka spanning human occupancy and unveiling the last glacial maximum abstract the quaternary is well known for being a period of the geological record that saw significant and alternating climatic fluctuations here we concentrate on the last 94 millennia that saw australia and its surrounding seas undergo significant environmental changes importantly also it is during that this period of time includes the arrival and settlement of humans in australia following on from marine isotopic stage 4 mis4 that saw over the period of 71 59 ka bp a significant eustatic sea level drop 100 m low sea surface temperatures as well as glacial conditions on land australia experienced wet conditions again but eventually progressively entered into a glacial phase by then humans had arrived on this large continent and later the megafauna progressively became extinct this paper describes in detail the climate over this period based principally on the high resolution record of two marine sediment cores located offshore of the southern australian margin and that are then compared with known events on land as well as other deep sea cores particular emphasis is placed on the period that spans the last glacial maximum lgm the extent of which thus far had been poorly defined in the australian region emphasis is placed on the period from 34 to 14 ka to demonstrate that 1 the lgm defined here as the period 24 to 18 ka was not always extremely dry and cold and 2 that people were able to live in inland australia as water existed in places despite generally cold conditions we also show using a series of ten maps at 2 ka intervals over the 34 14 ka period the waxing and waning of oceanic fronts such as the subtropical and subantarctic fronts link sea surface temperatures sst with periods of glacial expansion in the australian alps and tasmania as well as the south island of new zealand and the extent of the leeuwin current down to south of australia aeolian dust was transported at sea over the main core site from 26 to 18 ka period pointing to arid conditions in australia but this period was punctuated by two significant reductions in dust transport to both core sites coinciding with a retreat of the subantarctic front away from the australian southern coastline and slight sst shifts for a few centuries at 24 and 22 21 ka bp at the peak of the cold phase from 23 to 18 4 ka summer sst were of the order of 9 c below that experienced during the middle of the holocene at about 6 ka bp a similar temperature drop was also experienced offshore the northwestern corner of western australia periglacial activity dates for the australian mainland and tasmania pool around 22 ka on either side of the 24 ka event the chain of lakes in the willandra lakes retained water and human activity was registered in the area elsewhere in australia water was present to sustain human populations during the cold and dry times it is postulated here that northern australia was at times quite wet especially during mis4 the cessation of the lgm is set on 18 4 ka from offshore southern australia as confirmed for the deep sea cores by several proxies and more likely at 18 ka inland finally we document that it took two millennia for glacial conditions to end in the australian region as registered in our deep sea core records well after the lowest global sea level 20 6 and 20 ka respectively started to rise there is also evidence of another very cold period determined on the australian mainland tasmania and the south island of new zealand centred around 27 ka after which time warmer conditions occurred before the start of the lgm this is matched with our deep sea records with very cold conditions and changes in oceanographic conditions

the 5500 km long boundary flow off western and southern australia 1 the path of the shelf edge flow off southwestern australia is documented using results from satellite altimetry and sea surface temperature sst and a climatogical in situ analysis during austral winter a continuous current is shown to extend from its origin at north west cape to the southern tip of tasmania a distance of 5500 km satellite sst observations and surface buoy tracks confirm the location and continuity of the current trajectory while the leeuwin current is forced by the strong alongshore pressure gradient associated with the meridional portion of the western australian coastal boundary our results suggest that the essentially zonal shelf edge flow along the southern australian coast arises from the setup of coastal sea level by onshore ekman flow driven by the winter westerly wind and possibly a further alongshore pressure gradient the timing of these two different forcing mechanisms means that the west coast pressure gradient delivers the leeuwin current to the south coast just as the winds reverse and are thus able to maintain the eastward passage of the current the shelf edge flow consists of two main water masses a low salinity warm water type of tropical origin associated with the leeuwin current and a high salinity warm water inflow formed on the western end of the great australian bight continental shelf a naming convention is proposed the leeuwin current representing flow from north west cape to the great australian bight gab the south australian current between the eastern gab and western bass strait and the zeehan current off western tasmania

aureole deformation by flattening around a diapir during in situ ballooning the cannibal creek granite the cannibal creek granite a foliated pluton within a strongly deformed aureole shows several diagnostic features of a diapir the intensity of the aureole deformation diminished away from the contact the aureole foliation is continuous with that of the granite and forms closed elliptical trend lines and the contact metamorphic minerals are synkinematic with regard to the aureole foliation the pluton deformed its aureole in three stages involving initially brittle then ductile and finally brittle deformation styles initial intrusion of a low strength magma stoped kinked and flexed aside its overburden crystallization of the magma prevented further rise and it ballooned and deformed its aureole evidently entirely by ductile bulk shortening perpendicular to the contact this the major stage of aureole deformation records no evidence of vertical movement of the pluton or of progressive simple shear along its margin during this stage the magma may have been theologically a high strength bing

the formation of fire residues associated with hunter gatherers in humid tropical environments a geo ethnoarchaeological perspective this work was supported by the people programme marie curie actions of the european union s seventh framework programme fp7 2007 2013 under rea agreement n 623293 granted to d e f at the mcdonald institute for archaeological research university of cambridge radiocarbon dating was also funded by the exilarch s foundation for the dangoor research accelerator mass spectrometry laboratory d reams

ocean circulation in the great australian bight in an eddy resolving ocean reanalysis the eddy field seasonal and interannual variability abstract the ocean circulation in the great australian bight gab is dominated by the surface intensified leeuwin current lc over the outer continental shelf and the flinders current farther offshore in the gab the lc flows eastwards and varies seasonally with strongest currents of up to 0 8 m s at 130 5 e bringing warm and salty waters as far east as western tasmania the flinders current flows westwards as an undercurrent at depths of around 500 m over the continental slope and at the surface offshore of the lc off the shelf the gab is rich in mesoscale eddies with surface intensified currents of up to 0 4 m s that are coherent over the full water depth getting weaker with depth within deep water eddies isotherms are displaced vertically by up to 200 m eddies in the eastern gab are most energetic in austral winter and spring coincident with the seasonal weakening of the lc the eastern most penetration of gab eddies occurs in austral winter when the lc starts to weaken we hypothesise that the horizontal shear associated with the lc generates eddies in the eastern gab the volume transport of the lc at the head of the gab is typically between 1 and 7 sv with a clear seasonal cycle and the interannual variability of lc transport is up to 2 sv

a review of the shelf slope circulation along australia s southern shelves cape leeuwin to portland abstract a review is presented of the ocean circulation along australia s southern shelves and slope uniquely the long zonal shelf is subject to an equatorward sverdrup transport that gives rise to the flinders current a small sister to the world s major western boundary currents the flinders current is strongest near the 600 m isobath where the current speeds can reach 20 cm s and the bottom boundary layer is upwelling favourable it is larger in the west but likely intermittent in both space and time due to possibly opposing winds thermohaline circulation and mesoscale eddies the flinders current may be important to deep upwelling within the ubiquitous canyons of the region during winter the leeuwin current and local winds act to drive eastward currents that average up to 20 30 cm s the currents associated with the intense coastal trapped wave field 6 12 day band are of order 25 30 cm s and can peak at 80 90 cm s wintertime winds and cooling also lead to downwelling to depths of 200 m or more and the formation of dense coastal water within the great australian bight and the south australian sea within the great australian bight the thermohaline circulation associated with this dense water is unknown but may enhance the eastward shelf edge south australian current the dense salty water formed within spencer gulf is known to cascade as a gravity current to depths of 200 m off kangaroo island this dense water outflow and meanders in the shelf circulation also fix the locations of a sequence of quasi permanent mesoscale eddies between the eyre peninsula and portland during summer the average coastal winds reverse and surface heating leads to the formation of warm water in the western great australian bight and the south australian sea no significant exchange of shelf water and gulf water appears to occur due to the presence of a dense nutrient rich sub surface pool that is upwelled off kangaroo island the winds lead to weak average coastal currents increasing evidence suggests that el nino events 4 7 year period can have a major impact on the winter and summer circulation these events propagate from the pacific ocean and around the shelf slope wave guide of west australia and into the great australian bight during winter el nino events the average shelf currents may be largely shut down during summer the thermocline may be raised by up to 150 m the nature and role of tides and surface waves is also discussed along with uncertainties in the general circulation and future research

el nino sea level and currents along the south american coast comparison of observations with theory abstract interannual sea level fluctuations along the south american coast and 7 3 year long current records at 30 s off central chile were examined with a low frequency linear numerical model the model includes stratification and shelf and slope bottom topography which varies alongshore the coastal flow is driven by interannual alongshore wind stress and an interannual alongshore pressure gradient resulting from el nino la nina pressure fluctuations at the equator calculations suggest that along the south american coast the coastal interannual variability is primarily due to the remote equatorial forcing rather than interannual coastal alongshore wind stress past work using this model has shown that due to the scattering of lower vertical modes to higher ones by bottom friction the model predicts a low frequency jet trapped near the bottom along the continental slope until now adequate interannual current time series were unavailable to check this prediction analysis of the observations shows th

archaeological site formation in rain forests insights from the ituri rock shelters congo abstract this contribution complements the existing literature on rock shelter geoarchaeology and site formation processes by presenting data from 10 granite rock shelters in a tropical rain forest environment geological taphonomic pedological and archaeological data are used to assess the geomorphological evolution of rock shelters in the ituri rain forest northeast democratic republic of congo mechanisms of sediment production and deposition soil formation and related site formation processes were investigated the implications for the preservation of archaeological materials and stratigraphic resolution are discussed rock shelters in the tropical environment of the congo basin are formed by mechanical and chemical denudation of large granite boulders the current geomorphological cycle of rock shelter formation and collapse dates to the late pleistocene and may have been accelerated by anthropogenic forces the sedimentary record includes in situ breakdown products from the rock shelter walls while off site sources are represented by a minor influx of colluvium soil forming forces have acted on these matrices humans introduced charcoal phytoliths endocarps shell animal and human bone as well as inorganic materials such as stone ceramics and metal lags of archaeological materials are common under driplines where fine sediments have been washed away and include artefacts of different ages there is no evidence of extensive bioturbation but limited disturbance by roots burrowing animals and termites has been documented although there is some horizontal and vertical movement of prehistoric artefacts the post depositional translocation of materials is not significant we conclude that the stratigraphic integrity of these granite rock shelter sites with multiple archaeological horizons and the potential for the long term preservation of organic materials in a tropical environment are better than previously thought

post depositional alteration of humid tropical cave sediments micromorphological research in the great cave of niah sarawak borneo the post depositional alteration of cave sediments is of critical importance for the recognition identification and investigation of geoarchaeological and palaeoenvironmental evidence there have been relatively few studies of tropical cave sediments using micromorphology and this work represents one of the most detailed with 26 samples taken from deposits in the west mouth of the great cave of niah that cover the last 55 000 bp and contain the earliest known evidence for the remains of modern humans in southeast asia cave sediments situated in the humid tropics are subject to relatively high temperatures and moisture conditions that promote high rates of chemical alteration and geomorphic change this paper outlines those post depositional features that occurred in situ in the west mouth and include translocation and concentration bioturbation excrement bone alteration plant alteration clast alteration and guano decomposition it examines their implications for recognising past human activities e g fire altered materials the preservation of archaeological remains the nature of palaeoenvironments and of localised physical and bio geochemical processes

the nature of stone lines in the african quaternary record archaeological resolution at the rainforest site of mosumu equatorial guinea abstract stone lines are widespread quaternary features that appear in tropical and subtropical regions they have a diverse nature and genesis and are frequently associated with archaeological assemblages however archaeological deposition and stone line configuration may be unrelated geological events separated by thousands of years the energetics involved in stone line formation coarse and fine material translocation across space and in depth and overall assemblage integrity vary from one site to another this paper presents quantitative and spatial geoarchaeological data from the site of mosumu in the tropical rain forest of continental equatorial guinea mosumu yielded middle and later stone age assemblages dated to at least the last 30 000 years in a stone line context special attention to the study of vertical and horizontal variations of artifacts sedimentary features and taphonomic indicators allows analysis of the nature meaning and archeological resolution at this site the results are placed in the wider debate over the meaning of stone lines in the african quaternary record

geoarchaeological research in the humid tropics a global perspective abstract geoarchaeological research is now commonly undertaken as an integral component of archaeological investigations across much of the world however in humid tropical regions there is a relative shortfall of this earth science approach to understanding archaeological records in these regions where hot and humid conditions prevail for significant parts of the year sedimentological records are prone to high levels of diagenesis bioturbation and weathering this means that understanding and quantifying archaeological site formation processes can be very challenging because we may not have sufficient existing data with which to decipher the stratigraphic and microstratigraphic features recorded in these sequences in this paper we introduce a special issue of journal of archaeological science in which we showcase a selection of geoarchaeological research from across the equatorial regions of five continents highlighting the types of stratigraphic sequences and sedimentological features that are likely to be encountered and evaluating the tools that can be employed to maximise the geoarchaeological potential of these unique records additionally we use this opportunity to review geoarchaeology in the humid tropics from a global perspective outlining the main problems that geoarchaeologists face working in these environments and the techniques available with which to mitigate them

identification of activity areas by multi element characterization of sediments from modern and archaeological house floors using inductively coupled plasma atomic emission spectroscopy abstract a pilot study on the chemical analysis of earthen house floors using both modern and archaeological localities was undertaken to determine the degree to which activities leave detectable chemical residues and whether these residues are preserved in archaeological contexts the goals were to develop techniques for the identification and interpretation of activity areas in archaeological structures and to determine which elements serve to distinguish activities one modern structure from oaxaca mexico and two archaeological house floors from british columbia canada and oaxaca mexico were studied soil samples were collected from floors at all three sites and analysed by inductively coupled plasma atomic emission spectroscopy icp aes for al ba ca fe k mg mn na p sr ti and zn preliminary results show that activity areas in the modern house compound can readily be distinguished on the basis of chemical residues in soils that archaeological features are chemically distinct from natural soils and that features such as floors and hearths can be distinguished from each other and from the natural prehistoric ground surface multi element characterization by icp aes offers an advantage over traditional single element analysis by yielding more useful data for less effort expense and time

stoped blocks in plutons paleo plumb bobs viscometers or chronometers abstract stoped blocks potentially provide information about paleohorizontal during emplacement of plutons and about the timing of and viscosities and kinematics during magmatic fabric formation in the mount stuart batholith washington we have examined magmatic fabrics patterns around stoped blocks in tonalite located near the pluton roof and completed 1 1 scale three dimensional mapping of fabric patterns around stoped blocks in diorite located 1000 m below the roof in both settings no structural record of magma ascent early emplacement or settling of the blocks is preserved instead fabric formation largely post dates the settling and trapping of stoped blocks two dimensional finite difference thermal modeling and calculations of sinking rates support short

tropical limestone forest resilience and late pleistocene foraging during mis 2 in the trang an massif vietnam abstract in this paper we present a multi proxy study of tropical limestone forest and its utilization by human groups during the significant climatic and environmental upheavals of mis 2 29 11 7 kbp our data are drawn from new field research within the trang an world heritage property on the edge of the red river delta northern vietnam key findings from this study include 1 that limestone forest formations were resilient to the large scale landscape transformation of the sunda continent at the end of the last glaciation 2 that prehistoric human groups were probably present in this habitat through out mis 2 and 3 that the forested insular karst of trang an provided foragers with a stable resource base in a wider changing landscape during the late pleistocene and into the holocene these results have implications for our understanding of the prehistoric utilization of karst environments and resonance for their conservation in the face of climate and environmental change today

lapa das boleiras rockshelter stratigraphy and formation processes at a paleoamerican site in central brazil abstract lapa das boleiras rockshelter a paleoamerican archaeological site in central brazil was intensely occupied by humans from 10 000 14c bp 11 8 cal kyr bp until approximately 7500 14c bp 8 4 cal kyr bp in this paper we present some interpretations about the formation processes operating on the site one of our main conclusions is that the bulk of accumulated sediments at the site is of anthropogenic origin they are constituted by volumetrically significant quantities of plant ash remains what is somewhat unexpectedly in view of prevailing models about the lifestyle of paleoamerican hunter gatherers in south america the evidence we discuss below is also consistent with paleoenvironmental data that suggest a dry period during the mid holocene in the region probably leading to a decrease in human occupation araujo a g m neves w pilo l b atui j p 2005 holocene dryness and human occupation in brazil during the archaic gap quaternary research 64 298 307 we surmise that both factors underpin a surprising reduction in sediment accumulation at the site during the mid holocene

water mass analysis and alongshore variation in upwelling intensity in the eastern great australian bight 1 a study of climatological and conductivity temperature depth ctd data for 2004 is made to provide a conceptual model of upwelling for the eastern region of the great australian bight in particular the data and other studies provide strong evidence that shelf break upwelling is confined to the southwest kangaroo island region and does not occur farther to the west off the eyre peninsula rather the upwelled water is likely to remain in a kangaroo island pool until subsequent upwelling events draw the water to the shallower and surface coastal regions of the eastern bight in this manner the surface upwelling apparent off the bonney coast kangaroo island and the eastern great australian bight gab can appear to be simultaneous moreover it appears likely that the water within the kangaroo island pool remains nutrient rich support for this model comes from ctd sections collected in 2004 that show that the upwelled signal cool 26 kg m 3 diminishes in width and intensity with increasing distance from kangaroo island the pattern of fluorescence is similar to that for temperature in the upwelled plume and indicates that the kangaroo island pool remains nutrient rich relatively low oxygen concentrations may indicate a previous bloom the warmest water is found near the shelf break along with very low values of fluorescence and relatively higher levels of oxygen suggesting nutrient limited growth of phytoplankton these data also support the notion that the upwelled nutrient rich water is supplied from the kangaroo island pool and not by shelf break upwelling in the eastern gab anomalously salty and fresh water is identified as resulting from evaporation in coastal bays and groundwater aquifer discharge

measurements of the evolution of ocean wave spectra due to bottom friction data from a field experiment in which seven wave measurement instruments were placed in a linear transect across the great australian bight are analyzed to determine the spectral decay which can be attributed to bottom friction since other processes such as atmospheric input nonlinear interactions whitecap dissipation refraction and shoaling will also be active the spectral wave model wam is used as an analysis tool explicitly taking these additional processes into account in the analysis the data show marked spectral decay across the shelf analysis reveals that the bottom friction coefficient c is not constant as often assumed in operational wave models the bottom friction coefficient varies approximately inversely with the wave induced bed velocity consistent with the predictions of previous laboratory data and eddy viscosity models it is possible that percolation may also be important in the region but the available data do not allow the relative contributions of bottom friction and percolation to be determined

arterial ocean circulation of the southeast indian ocean 1 the time mean ocean circulation for the southeast indian ocean seio is analyzed using a colorwheel to reveal an arterial like structure although quasi zonal the mean circulation in this region is distinctly more complex than previously presented in recent literature the mean flow is derived from an eddy resolving ocean reanalysis of the past 14 years the ocean state is constrained through data assimilation with observed sea level anomaly sea surface temperature and in situ profiles geostrophic currents derived from the reanalyzed mean dynamic topography mdt are validated against two other mdt analyses to show a comparable arterial structure and distribution of scales in particular the broad scale eastward flow is regularly interspersed by narrow bands of the near westward flow meridional sections from the ocean reanalysis reveal a net eastward transport in the surface layer and a net westward flow at mid depth the seasonality of the surface layer flow in the seio appears to have increased decreased eastward mean transport that coincide with seasons of stronger weaker leeuwin current lc whether the narrow bands of mean current and mass flux are simply the average of the eddies or represent an underlying weak jet remains a topic of current debate

exploding xenoliths and the absence of elephants graveyards in granite batholiths abstract biotite monzogranite near the eastern margin of the late devonian south mountain batholith at portuguese cove nova scotia surrounds a large 20 m 25 m anisotropic decimetre scale interbedded psammite and semipelite xenolith of the metamorphic regional greenschist thermal cordierite hornfels country rocks of the cambro ordovician meguma group the xenolith has two distinct types of surfaces against the monzogranite i one rounded diffuse and apparently old surface that had prolonged contact with the granite magma and ii two straight sharp and apparently new surfaces that had more recently come into contact with the granite magma more than 375 thin sheets width n 224 0 1 0 5 cm n 66 0 5 1 0 cm n 51 1 0 5 0 cm n 30 5 0 10 0 cm n 3 10 cm n 2 ranging in composition from monzogranite to pegmatite to coarse quartz sericite cut the xenolith parallel to bedding producing a cumulative volume expansion of 14 in the xenolith aspect ratios in some of the thin sheets exceed 1000 1 several sheets cut the xenolith perpendicular to bedding producing a volume expansion of

rheology and deformation mechanisms of an isotropic mica schist we have investigated the transitional semibrittle deformation of a mica schist 75 biotite by shortening cylinders cored at 0 45 and 90 to foliation to varying strains at confining pressures pc to 500 mpa constant strain rates e from 1 5 10 7 to 1 6 10 4 s 1 and temperatures t from 25 to 400 c deformation is concentrated within one or more throughgoing millimeter wide shear zones at all conditions these localize at low strains e 2 through the nucleation and coalescence of dense sets of intragranular microkink bands mkbs despite distinct differences in the relative number of mica grains oriented favorably for slip and kinking in different loading directions the differential stresses required for shear zone development vary little with fabric orientation biotite schist undergoes a transition from strain softening to steady strength mechanical response at confining pressures in the range 75 to 150 mpa the pressure sensitivity of strength characterized by the slope of the mohr envelope decreases from 0 5 at pc 100 mpa to 0 1 at pressures greater than 200 mpa reflecting the increasing contribution of glide and kinking in biotite at higher pressures however dilatancy associated with microcracking and void formation along mkb boundaries persists to at least 500 mpa within the pressure insensitive regime 200 pc 500 mpa temperature and strain rate dependencies of strength determined in stepping tests reveal a strong history dependence to flow that cannot strictly be described by a steady state constitutive law samples deformed in steps from low to high temperatures or fast to slow strain rates consistently exhibit stronger temperature and strain rate sensitivities than those deformed along t decreasing or e increasing paths path dependent effects may reflect differences in the degree to which inherited dislocation substructures are utilized or overprinted during later deformation increments by assuming an exponential relationship between differential stress d and strain rate e of the form e c exp d exp q rt we fit the data with two end member flow laws with a single activation energy q 89 kj mol and exponential constants ss 0 15 0 01 mpa 1 and ws 0 55 0 04 mpa 1 that account for the different responses observed along stepping paths that are strongly sensitive or weakly sensitive to t and e respectively application of the results to crustal deformation suggests that mica rich aggregates are weaker than other common rock types throughout a broad midcrustal depth range supporting the inference that retrograde reaction to phyllosilicates may be important in localizing crustal deformations within large faults and shear zones

analysis of hydrographic and stable isotope data to determine water masses circulation and mixing in the eastern great australian bight 1 hydrographic and stable isotope data from waters in the eastern great australian bight gab sampled during march april 1998 indicate that both mixing and evaporative processes are important on the shelf five water masses are defined on the basis of their temperature salinity 2h and 18o values two of these are end members the flinders current fc and the great australian bight plume gabp whereas the other three are a result of mixing between these two end members water mass distribution reflects an anticyclonic gyre in the eastern gab cool and fresh water present at depth along the eyre peninsula is sourced from upwelling of flinders current water directly from the shelf break this water is progressively heated evaporated and mixed with warmer and more saline shelf waters as it flows around the gyre high temperatures salinities and 2h values in surface waters in the central gab suggest that the great australian bight plume has a greater spatial extent than previously recorded also occurring along the shelf edge between 130 e and 133 e a high temperature high salinity low 2h water mass that is isotopically similar to the flinders current occurs in the west of the study area indicating intrusion of flinders current water into the central gab differences in isotopic compositions of off shelf water suggest that the great australian bight plume is flowing off the shelf and mixing with flinders current water at 132 e however this outflow does not generate an eastward flowing current during the period when samples were collected

waxy bitumen stranding in southern australia a geochemical study of multiple oil families and their likely origins abstract reports of bitumen stranding on the ocean beaches of southern australia date back to the early days of european settlement previous investigations have shown that this coastal bitumen comprises three categories of stranded petroleum waxy bitumen asphaltite and oil slicks all three varieties are physically and chemically distinct from each other and bear no geochemical resemblance to any indigenous australian crude oil this study focuses on the most common variety waxy bitumen which accounted for 90 of the strandings on six south australian beaches repeatedly surveyed during 1991 1992 geochemical analysis of 96 individual specimens collected from these survey sites and other beaches in south australia and western victoria has shown them to be variously weathered high wax crude oils of paraffinic to aromatic intermediate bulk composition elemental isotopic and biomarker differences allow their assignment to at least five oil families with inferred source facies that range from deep freshwater lacustrine through paludal and deltaic to euxinic marine possibly deposited within different sedimentary basins family 1 2 and 3 waxy bitumens all contain biomarkers derived from the freshwater alga botryococcus sp and tropical angiosperms notably dipterocarps similar biomarker assemblages are unknown in australian sedimentary basins but are common in cenozoic crude oils and source rocks throughout western indonesia family 4 waxy bitumens lack these biomarkers but do contain dinosterane and 24 n propylcholestane indicative of a marine source affinity while the carbon isotopic signatures and high pristane phytane pr ph ratios of family 5 waxy bitumens are consistent with their origin from coal rich source rocks deposited in fluvial to deltaic sedimentary successions the majority of these waxy bitumens represent an oceanic influx of non indigenous southeast asian crude oils carried into the waters of southern australia by the leeuwin current although they are likely to originate from natural seepage within the indonesian archipelago it is unknown whether the parent oils emanate from submarine seeps or from inland seepages which are then carried to the sea by rivers the common practice of tanker cleaning operations in the java and banda seas may augment the supply of natural bitumen to the beaches of australia

oceanographic controls on shallow water temperate carbonate sedimentation spencer gulf south australia spencer gulf is a large ca 22 000 km2 shallow 60 m water depth embayment with active heterozoan carbonate sedimentation gulf waters are metahaline salinities 39 to 47 and warm temperate ca 12 to 28 c with inverse estuarine circulation the integrated approach of facies analysis paired with high resolution monthly oceanographic data sets is used to pinpoint controls on sedimentation patterns with more confidence than heretofore possible for temperate systems biofragments mainly bivalves benthic foraminifera bryozoans coralline algae and echinoids accumulate in five benthic environments luxuriant seagrass meadows patchy seagrass sand flats rhodolith pavements open gravel sand plains and muddy seafloors the biotic diversity of spencer gulf is remarkably high considering the elevated seawater salinities echinoids and coralline algae traditionally considered stenohaline organisms are ubiquitous euphotic zone depth is interpreted as the primary control on environmental distribution whereas seawater salinity temperature hydrodynamics and nutrient availability are viewed as secondary controls luxuriant seagrass meadows with carbonate muddy sands dominate brightly lit seafloors where waters have relatively low nutrient concentrations ca 0 to 1 mg chl a m 3 low diversity bivalve dominated deposits occur in meadows with highest seawater salinities and temperatures 43 to 47 up to 28 c patchy seagrass sand flats cover less illuminated seafloors open gravel sand plains contain coarse bivalve bryozoan sediments interpreted as subphotic deposits in waters with near normal marine salinities and moderate trophic resources 0 5 to 1 6 mg chl a m 3 to support diverse suspension feeders rhodolith pavements coralline algal gravels form where seagrass growth is arrested either because of decreased water clarity due to elevated nutrients and associated phytoplankton growth 0 6 to 2 mg chl a m 3 or bottom waters that are too energetic for seagrasses currents up to 2 m sec 1 muddy seafloors occur in low energy areas below the euphotic zone the relationships between oceanographic influences and depositional patterns outlined in spencer gulf are valuable for environmental interpretations of other recent and ancient particularly neogene high salinity and temperate carbonate systems worldwide

temperate shelf water dispersal by australian boundary currents implications for population connectivity boundary currents have been recognized as potential drivers of spatial heterogeneity in the ocean because of their role in physical transport and influence on large scale coastal processes in this study we used particle tracking methods in a data assimilating eddy resolving ocean circulation model to determine the effect of multiple boundary currents on connectivity around temperate australia during the austral winter results demonstrated that oceanographic connectivity was asymmetric around australia having greater eastward trajectories due to more favorable ocean boundary currents during this season we validated connectivity patterns with genetic data from an ecologically important species the kelp ecklonia radiata which has greater genetic similarity between the west and south coasts of australia compared with the east coast likely due to predominantly eastward propagule dispersal boundary current circulation was a coarse predictor of kelp genetic connectivity on multigeneration time scales and the nature of these relationships varied among the three boundary current systems according to mean current strength

deep sections through the south australian basin and across the australian antarctic discordance fronts and water masses in the australian basin are described based on three sections made by r v franklin during 1994 as part of the woce one time hydrographic survey the subtropical front is found closer to the australian continent than previously thought convection of subantarctic mode water is seen to reach 700 m depth a locally formed variety of antarctic intermediate water with a temperature near 6 c is found near 120 e antarctic bottom water enters the indian ocean through the discordance at 125 37 e and 127 e but not at 120 e where the deep passage seen in the topography may be closed for bottom water inflow

revisiting upper gulf st vincent in south australia the salt balance and its implications abstract due to the excess of evaporation over rainfall some regions of the coastal waters fringing the semi arid zones of australia are highly saline at the head waters of gulf st vincent in south australia where there is virtually no river discharge the salinity can increase to over 42 in summer when the rainfall is minimal based on the data available from a salinity monitoring programme over the northern regions of the gulf the seasonal variation of the salt balance has been reviewed the component of the salt efflux due to the oscillatory vertical shear of the tidal current has been estimated by using an existing simple model based on this estimation the seasonal variation of the salt efflux associated with the lateral general circulation has been calculated therefrom the intensity of the general circulation is estimated at 1 2 cm s 1 which agrees well with available current meter observations due to the large width to depth ratio of the region the general circulation dominates over dispersion in the salt flushing process except in mid winter when the two mechanisms contribute almost equally the general circulation which is maintained to a large extent by the horizontal density gradient and the wind stress reverses itself at times depending on the relative strength of these two factors

detection of burning of plant materials in the archaeological record by changes in the refractive indices of siliceous phytoliths abstract the most resilient remains of plants in most archaeological sites are the siliceous phytoliths special cells that are partially or completely silicified during the plant s life these cells have characteristic morphologies and thus the phytoliths can often be used to identify the taxonomic affinities of plants brought to an archaeological site in order to determine what they were used for other means of analysis are needed we present here a method to distinguish burnt from unburnt phytolith assemblages the method is based on measuring the refractive index ri of individual phytoliths the phytoliths even from a single plant have a range of ri values burning a phytolith sample causes a shift to higher ri comparing burnt and unburnt samples we demonstrate that it is possible to differentiate between them based on the fraction of phytoliths with ri higher than 1 440 this serves as a basis for a simplified mode of measurement that requires only the use of a petrographic light microscope and a mineral oil of ri 1 440 we apply the simplified method to two natufian samples from hayonim cave western galilee israel

initial micromorphological results from liang bua flores indonesia site formation processes and hominin activities at the type locality of homo floresiensis liang bua a karstic cave located on the island of flores in eastern indonesia is best known for yielding the holotype of the diminutive hominin homo floresiensis from late pleistocene sediments modern human remains have also been recovered from the holocene deposits and abundant archaeological and faunal remains occur throughout the sequence the cave the catchment in which it is located and the gross aggradational phases of the sediment sequence have all been subject to a great deal of scientific scrutiny since the discovery of the holotype of h floresiensis in 2003 a recent program of geoarchaeological research has extended analyses of the site s deposits to the microstratigraphic micromorphological level the stratigraphic sequence in the cave is well defined but complex comprising interstratified sediments of diverse lithologies and polygenetic origins including volcanic tephras fine grained colluvium coarse autogenic limestone gravels speleothems and anthropogenic sediments such as combustion features the sedimentological and chemical heterogeneity suggest that processes of site formation and diagenesis varied markedly through time both laterally and vertically we present initial results from samples collected in 2014 from an excavation area near the rear of the cave which yielded radiocarbon ages from charcoal that fill an important temporal gap in the chrono stratigraphic sequence of previously excavated areas of the site the results indicate marked changes in site environment and hominin activity during the late pleistocene relating primarily to the degree to which the cave was connected to the hydrogeological system and to the varying intensities of use of the cave by hominins importantly we identify anthropogenic signs of fire use at the site between 41 and 24 thousand years ago most likely related to the presence of modern humans

formation processes and combustion features at the lower layers of the middle palaeolithic open air site of nesher ramla israel the lower stratigraphic sequence units iii vi of the middle palaeolithic site of nesher ramla was studied using geoarchaeological methods field observations indicate that the site formed within a karst depression that was infilled by colluvium and in which intermittent human activity occurred including two layers highly rich in anthropogenic remains units iii and v infrared analysis of bones determined that black bones are carbonized and that certain white bones are calcined quantitative analysis of wood ash pseudomorphs indicates specific areas of high concentrations of ash micromorphological analysis enabled identification of two distinct features associated with ash and burnt bones one is a thinly bedded complex of blacked soil overlain by ash and charcoal and the second is a 20 cm thick massive fine grained layer of mixed ash the first feature is interpreted as an in situ hearth macroscopically similar features have not yet been analyzed the second feature is interpreted as ash in secondary position i e an ash pile midden that formed following hearth rake out activities these findings are unique considering that most middle palaeolithic open air sites in the levant are single layered and that in most evidence for hominin use of fire is scarce or absent we discuss the factors that may affect the preservation of ash in open air sites and conclude that the setting of nesher ramla in a topographic low provided relative protection from wind which prevented ash deflation and at the same time hominin activity remains were buried relatively fast which detached the ashes and combustion features from direct rainfall and from decalcifying root activity

have the southern westerlies changed in a zonally symmetric manner over the last 14 000 years a hemisphere wide take on a controversial problem the prevailing view in the palaeoclimate literature of the last 20 years is that the southern westerly winds sww were intensified over southern australia and tasmania during the warmer than present early holocene 11e8 ka at similar latitudes on the opposite side of the southern mid latitudes palaeoclimate studies have suggested a poleward shift of the northern edge of the westerlies and focusing at 49 s in southern south america this zonal asymmetry contrasts with the modern day zonal symmetry displayed by the sww and poses a formidable challenge to an understanding of the modes of climatic variability of the southern extra tropics this paper presents an updated synthesis of continuous radiocarbon dated palaeoenvironmental data from the westerlies zone of influence in all southern hemisphere continents synchronous multi millennial trends in moisture vegetation fire and hydrologic balance are remarkably consistent with the way the sww changes impact upon the climate in southern hemisphere landmasses in the modern climate considering the modern relationships between local precipitation and zonal wind speeds it is suggested that the sww changed in a zonally symmetric manner at multi millennial scale between 14 and 5 ka regional asymmetry develops after 5 ka across the southern hemisphere with a pattern of precipitation anomalies akin to the modern functioning of el nino e southern oscillation which started w6200 years ago

cross shelf seawater exchange controls the distribution of temperature salinity and neritic carbonate sediments in the great australian bight the seasonally averaged wind stress of the great australian bight gab during the austral winter is directed to the east along the shelf and results in downwelling that extends to depths of 250 m this downwelling is enhanced in the eastern gab through the outflow of cold saline water formed in the broad shallow regions of the gab and gulfs during the austral summer the averaged wind stress field of the gab is anticyclonic with upwelling favorable winds along much of the coastline in general however significant slope upwelling is only observed in the eastern and western gab where the shelf is narrow upwelling there provides nutrients to support the planktic and pelagic communities and the observed distribution of benthic invertebrate communities that lead to the formation of neritic carbonate sediments at the shelf break of the central gab where the shelf is very wide the observed cross shelf distributions of temperature salinity and sediments indicate that downwelling occurs year round the implied lack of nutrients is argued to explain the smaller communities of invertebrates found at the shelf edge 100 250 m in these areas a previous numerical study is cited to show that summer downwelling very likely results from a convergence of the deep ocean and poleward sverdrup transports the unique aspect of this integrated oceanographic sedimentological investigation is to tie outcomes of that numerical study with extant observations and benthic habitat to provide a consistent picture of how cross shelf exchange regulates water properties and benthos in the gab

the influence of mixing on primary productivity a unique application of classical critical depth theory mixing and primary productivity was examined in upwelling influenced nearshore waters off south western eyre peninsula swep in the eastern great australian bight egab the economically and ecologically important shelf region off southern australia that forms part of the southern and indian oceans mixing stratification in the region was highly temporally variable with a unique upwelling circulation in summer autumn november april and downwelling through winter spring may september highest productivity was associated with upwelled stratified water up to 2958 mg c m

evidence of a large seasonal coastal upwelling system along the southern shelf of australia 1 we report observational existence of a large seasonal coastal upwelling system that establishes in austral summer december april along australian southern shelves wind driven upwelling events occur simultaneously in three upwelling centres spanning a distance of 800 km during each summer period there are 2 3 major upwelling events each lasting 1 week the simultaneous rapid response of sst to wind forcing in the upwelling centres which display vastly different shelf widths points to the existence of a larger scale process that carries cold water onto the shelf prior to the upwelling season exploration of a major upwelling event in march 1998 shows the evolution of peak surface chlorophyll a concentrations of 4 g l lagging the onset of upwelling by 1 week the associated exponential growth rate can be estimated at 0 4 d 1 another week later we found a distinct sub surface chlorophyll a maximum at a depth of 50 m centred along the upwelling front reasons for the formation of this maximum are not fully understood

paleomagnetism and tectonics of the cretaceous mt stuart batholith of washington translation or tilt abstract the mt stuart batholith is a composite pluton of late cretaceous age that intrudes the crystalline north cascades terrane of northwestern washington its paleomagnetic direction d 10 0 i 45 5 95 4 9 is markedly different from the direction expected for cretaceous rocks from northwestern washington d 330 5 i 73 0 which means that the mt stuart batholith either has moved relative to the north american interior or has been tilted through a substantial angle or both since it acquired its magnetism either tilt or translation are possible geometrically but translation is more likely because 1 local geology apparently does not support tilt in the required direction 2 it probably is not possible for a panel of rock the size of the mt stuart batholith to tilt through the necessary angle ca 35 after its deeper parts have cooled sufficiently to retain remanent magnetization 3 the sense of paleomagnetic discordance found in the mt stuart batholith clockwise rotation of declination flattened inclination is identical to that found in nearly every other allochthonous terrane in the western north american cordillera including every other cretaceous batholith studied except the sierra nevada

aspects of the mean wintertime circulation along australia s southern shelves numerical studies abstract a high resolution numerical model is used to study the mean wintertime shelf slope circulation between the gulfs of south australia and the west coast of tasmania the mean downwelling favorable winds for the region result in a continuous eastward coastal current cc extending from cape leeuwin to the eastern coast of tasmania the magnitude of the cc is generally largest over the shelf break has speeds of more than 40 cm s 1 transport 2 4 sv sv 106 m3 s 1 and is generally in good agreement with observations the relative importance of the leeuwin current zonal winds and density gradients to the shelf circulation is established within bass strait the eastward circulation is in good agreement with observations and simple models show that about 30 of the transport arises from local winds and the remainder from the cc the total transport through the strait 0 95 sv is shown to be controlled by sea level on the east coast of tasmania a current of up to 10 cm s 1 is also found to flow

on enso coastal currents and sea levels abstract sea level measurements along the western coast of the americas have shown that there is a strong signal at enso frequencies approximately 2 2 yr 1 to 2 5 yr 1 that propagates poleward at about 40 to 90 cm s 1 this enso sea level signal must be associated with enso coastal currents but because adequate interannual current time series are unavailable the structure and strength of these currents are not known coastal enso currents must be fundamentally affected by bottom topography and bottom friction but previous theory has not taken these effects into account a near boundary numerical model with realistic bottom friction stratification and shelf and slope topography was therefore constructed to study enso coastal flow i at enso frequencies previous results for models with no bottom topography and no bottom friction suggest that sea level should not propagate poleward with realistic bottom friction and bottom topography coastal sea level propagates poleward at speeds similar to tho

classification of submarine canyons of the australian continental margin abstract submarine canyons influence oceanographic processes sediment transport productivity and benthic biodiversity from the continental shelf to the slope and beyond however not all canyons perform the same function the relative influence of an individual canyon on these processes will in part be determined by its form shape and position on the continental margin here we present an analysis of canyon geomorphic metrics using an updated national dataset of 713 submarine canyons surrounding mainland australia these metrics attributes for each canyon are used to classify them into canyon types across a hierarchy of physical characteristics separately for shelf incising n 95 and slope confined blind n 618 canyons we find that the canyon metrics describe a wide variety of canyon form and complexity that is consistent with a population of canyons that has evolved at different rates around the australian margin since the break up of gondwana the large number of slope confined canyons is interpreted to reflect dominance of slope mass wasting processes over erosive turbidity flows from fluvial and shelf sources on an arid continent the distribution of submarine canyons around the australian margin is not regular with clusters occurring in the east southeast west and southwest where the margin is steepest the classification result provides a quantitative framework for describing canyon heterogeneity for application in studies of geological controls on individual canyons canyon oceanography and canyon biodiversity

sediment waves with a biogenic twist in pleistocene cool water carbonates great australian bight abstract sediment waves composed of fine grained carbonate ooze with in place bryozoans are a characteristic element of the pleistocene of the great australian bight gab the low amplitude and strongly elongate sediment waves are up to 10 km long 1 km wide 40 m high and oriented sub parallel to contours immediately off the shelf slope break they are asymmetrical showing up slope migration and mainly occur in trains the sediment waves were drilled during odp leg 182 in 1998 and were interpreted as biogenic reef mounds new high quality seismic and multibeam bathymetry data were acquired on the galathea 3 expedition in 2006 allowing description of the morphology and internal architecture of the sediment waves in unprecedented detail leading to an alternative interpretation of their formation most sediment waves were initiated by preferential deposition on the landward side of irregular erosion surfaces sediment wave accretion took place under the influence of density driven currents which decelerated up the landward dipping flanks and accelerated down the seaward dipping flanks of the sediment waves the currents are interpreted as dense water cascades formed by summer evaporation and strong winter cooling by analogy with oceanographic processes in the present day gab the lithological composition varied with climate and sea level but sediment wave formation did not sediment waves formed and accreted during both glacials and interglacials in contrast to the previous interpretations which involved growth in glacial periods only bryozoans influenced the depositional environment by adding sediment trapping fine grained particles and stabilizing the muddy sea floor this caused the sediment waves to gain a more prominent sea floor relief than most muddy siliciclastic sediment waves formed by similar depositional processes the interpretation of the sediment waves as purely biogenic build ups is rejected and the sediment waves are most appropriately described as biogenically influenced sediment waves

tidal progression in a near resonant system a case study from south australia abstract detailed observations of the tide in a shallow southern hemisphere gulf are described the gulf is close to quarter wave resonance with the semi diurnal tide but the nature of the tide changes with distance from the head of the gulf near the head the tide behaves as a standing wave the phase is almost constant in this region and the tidal currents lead elevations by 90 near the entrance to the gulf the semi diurnal tide behaves more as a progressive wave there is a regular change in phase of elevation with distance and the phase difference between current and elevation is reduced it is shown here that this behaviour can be understood in terms of a simple conceptual model proposed by redfield 1950 papers in physical oceanography and meteorology 11 1 36 in this model friction causes the amplitude of the tidal wave to diminish exponentially with distance travelled near the gulf head the incident and reflected waves are of similar amplitude and a standing wave is produced further from the head the incident wave is considerably larger than the reflected wave and the resulting wave is predominantly progressive the observations presented here are in good agreement with this model if the tidal wave amplitude is allowed to fall by 1 e for every wavelength travelled this decay in wave amplitude implies a rate of energy loss in the region for the m2 tide of 135 mw a figure which is consistent with an independent estimate of energy dissipation