sub basin scale dust source geomorphology detected using modis 1 the spatial and temporal variability of dust emissions from different surfaces in the lake eyre basin australia is determined using modis data for 2003 6 the sources of 529 dust plumes were classified overall 37 of plumes originated in areas of aeolian deposits 30 from alluvial deposits and floodplains and 29 from ephemeral lakes or playas at this sub basin scale the relative importance of different dust source geomorphologies varied primarily in response to sediment supply and availability and was not related to aeolian transport capacity suggesting the lake eyre basin is a supply limited system

lead isotopic evidence for an australian source of aeolian dust to antarctica at times over the last 170 000 years abstract systematic analysis of pb sr and nd isotopes of 32 fluvial clay samples 6 km 2 murray darling basin mdb located in semiarid southeastern australia displays similar isotopic values between some mdb clays and dust from several ice core samples from the epica dome c in antarctica close scrutiny of several ratios of the four pb isotopes and in particular 208 pb 207 pb versus 206 pb 207 pb shows that several samples from the darling sub basin of the mdb display similar values for the same isotopes for dome c samples from different ages and more particularly during wet phases in australia marine isotopic stages 5e 3 and 1 the combination of nd and sr isotopic ratios from the same mdb fluvial clays clearly eliminates the murray sub basin and supports the darling sub basin as a potential source of aeolian material to antarctica overall the australian dust supply to antarctica predominantly occurred during interglacial periods the work presented here shows that aerosols generated in southeastern australia can travel to parts of west antarctica and this is supported by atmospheric observations and models in addition evidence of australian dust in antarctic ice cores further implies dust deposition in the southern ocean would have occurred in the past current meteorological observations also imply that the western pacific and indian ocean sector of the southern ocean would frequently receive aeolian dust components originating from southeastern australia

global cooling initiated stony deserts in central australia 2 4 ma dated by cosmogenic 21ne 10be stony deserts are durable indicators of aridity but until now have not been directly dated using 21ne and 10be produced in surface rocks by cosmic rays we show that australian stony deserts formed 2 4 ma at the time when global cooling initiated the quaternary ice ages and intensified aridity induced major landscape changes in central australia this is the first direct determination of stony desert ages using a new method for determining cosmogenic 21ne in the presence of various neon components from other sources

la nina de australia contemporary and palaeo hydrology of lake eyre abstract the available records of inflows to lake eyre cover only forty five years their quality is questionable as longer time series of precipitation records are available the observed series of inflows to lake eyre can be extended with the help of a rainfall runoff model further reconstruction of the inflow series can be achieved by examining local evidence or with the help of proxy data however the limitations of these extensions and reconstructions of inflows are severe the inflows to lake eyre could be considered one of the most convincing manifestations of hydrological uncertainty however it is apparent that major flooding episodes in the lake eyre basin are most often associated with la nina phases of the el nino southern oscillation enso phenomenon the paper presents a hydrological description of the lake eyre basin and large scale contemporary and palaeo climatic patterns which affect the water balance of the catchment a simple water balance model has been constructed to determine storages of the lake when annual evaporation reaches equilibrium with annual runoff

identifying regional dust transport pathways application of kinematic trajectory modelling to a trans tasman case pi kinematic trajectory model is used to investigate potential pathways of dust transport from australia to new zealand historically these have been assumed to follow rather direct west east trajectories spanning 2 to 3 days often resulting in red snow events in the southern alps of new zealand however results from the present study which examined the route taken by air parcels originating in southern australia during dust storms on 24 and 25 may 1994 indicate that trans tasman dust transport trajectories are more diverse than previously thought and display considerable variation during single events these mon divergent pathways tie in more closely with aeolian dust sedimentation patterns identified by ocean coring in the tasman sea and may account for the deposition of australian dust on sub antarctic islands located well south of the australian continent copyright 2000 john wiley sons ltd

australian desert dune fields initiated with pliocene pleistocene global climatic shift development of continental aridity has been linked to late cenozoic global cooling but the evidence is indirect based on terrestrial loess deposits and eolian silt in marine sediments whereas direct dating of the inception of arid landforms has been frustrated by a lack of suitable methods here we report the first age determination of a major arid zone dune field based on cosmogenic 10 be and 26 al measurements of drill cores from dunes in the simpson desert central australia results show that the dune field began to form ca 1 ma whereas dating using quartz optically stimulated luminescence indicates episodic dune building during late quaternary ice ages less intense desertification began earlier the previous cosmogenic exposure dating showed that neighboring stony deserts began to form at the onset of quaternary ice ages 2 4 ma aridity deepened and the dune field formed when ice age cycles increased their amplitude and switched their periods from 40 k y to 100 k y ca 1 ma

the timing of linear dune activity in the strzelecki and tirari deserts australia abstract linear dunes occupy more than one third of the australian continent but the timing of their formation is poorly understood in this study we collected 82 samples from 26 sites across the strzelecki and tirari deserts in the driest part of central australia to provide an optically stimulated luminescence chronology for these dunefields the dunes preserve up to four stratigraphic horizons bounded by palaeosols which represent evidence for multiple periods of reactivation punctuated by episodes of increased environmental stability dune activity took place in episodes around 73 66 35 32 22 18 and 14 10 ka intermittent partial mobilisation persisted at other times throughout the last 75 ka and dune activity appears to have intensified during the late holocene dune construction occurred when sediment was available for aeolian transport in the strzelecki and tirari deserts this coincided with cold arid conditions during marine isotope stage mis 4 late mis 3 and mis 2 and the warm dry climates of the late pleistocene holocene transition period and late holocene localised influxes of sediment on active floodplains and lake floors during the relatively more humid periods of mis 5 also resulted in dune formation the timing of widespread dune reactivation coincided with glaciation in southeastern australia along with cooler temperatures in the adjacent oceans and antarctica

glacial interglacial changes of southern hemisphere wind circulation from the geochemistry of south american dust abstract the latitudinal displacement of the southern westerlies and associated climate systems is a key parameter for understanding the variations of southern hemisphere atmospheric circulation during the late quaternary period to increase understanding of past atmospheric circulation and of the paleo environmental conditions associated with continental dust sources we dig deeper into dust provenance in paleo archives of the southern hemisphere we present here a sr nd isotopic and rare earth element study of surface sediments collected along a 4000 km latitudinal band from arid and semi arid terrains in southern south america findings from terrains that served as paleo dust suppliers are compared with modern dust collected from monitoring stations along the same latitudinal band which affords a test on how actual present day aeolian compositions compare to those of the past potential source areas moreover the comparison between past and present day datasets is useful for understanding present day atmospheric circulation armed with a new comprehensive dataset we revise previous interpretations of the provenance of dust trapped in the antarctic ice and sediments deposited in the south atlantic sector of the southern ocean these comparisons support multiple source regions in southern south america that changed with climates the findings reveal that although patagonia plays an important role in contributing dust to the higher latitudes central western argentina and to a lesser extent the southern puna region also emerge as potentially important dust sources during glacial times the southern altiplano appears to be a major contributor during interglacial periods as well we rely in part on an understanding of modern wind dust activities to conclude that the possible presence of southern south america source regions other than patagonia in east antarctic ice is consistent with an overall equatorward displacement during glacial times of both the mid latitude westerlies and the subtropical jet stream

how flat is tibet high resolution digital topography three arc second grid for most of tibet provides new information to characterize the relief of the highest and largest plateau on earth the arid to semiarid central and northern part of the plateau interior has low relief average slopes of over 250 m windows and a mean elevation of 5023 m above sea level at moderate wavelengths of m relief is or less for most of tibet as opposed to the much higher relief of up to 6 km on the plateau edges where glacial and fluvial dissection is greater because of higher levels of precipitation the only faults manifesting significant topographic relief are the relatively small scale generally north trending graben systems primarily in southern tibet and several large scale fault systems near the edges of tibet the flatness of tibet implies that 1 there has been little deformation especially shortening of the uppermost crust north of the graben systems during the late cenozoic and 2 shallow crustal isostatic compensation has been acting to level the surface of the plateau

modern and holocene aeolian dust variability from talos dome northern victoria land to the interior of the antarctic ice sheet abstract high elevation sites from the inner part of the east antarctic plateau sample windborne dust representative of large portions of the southern hemisphere and are sensitive to long range atmospheric transport conditions to polar areas on the periphery of the ice sheet conversely the aeolian transport of particles from high elevation ice free areas can locally represent a relatively important additional input of dust to the atmosphere and the interplay of atmospheric dynamics dust transport and deposition is strictly related to the regional atmospheric circulation behaviour both at present day and in the past the understanding of the spatial extent where local sources can influence the mineral dust budget on the ice sheet is fundamental for understanding the atmospheric dust cycle in antarctica and for the interpretation of the dust history in marginal glaciological settings in this work we investigate the spatial variability of dust flux and provenance during modern pre industrial and holocene times along a transect connecting talos dome to the internal sites of the antarctic plateau and we extend the existing documentation of the isotopic sr nd fingerprint of dust sized sediments from victoria land source areas dust flux grain size and isotopic composition show a marked variability between talos dome mid point d4 and dome c vostok suggesting that local sources play an important role on the periphery of the ice sheet microscope observations reveal that background mineral aerosol in the taldice core is composed by a mixture of dust volcanic particles and micrometric sized fragments of diatoms these latter representing a small but pervasive component of antarctic sediments a set of samples from victoria land mostly consisting of regolith and glacial deposits from high elevation areas was collected specially for this work and the isotopic composition of the dust sized fraction of samples was analyzed results reveal a close relationship with the parent lithologies but direct comparison between source samples and firn ice core dust is problematical because of the ubiquitous volcanic contribution to the environmental particulate input in the talos dome area the frequency of events potentially suitable for peripheral dust transport to talos dome appears relatively high for present day conditions according to back trajectories calculations and the related air flow pattern well defined from a seasonal and spatial perspective also as expected from palaeo data these events appear extremely uncommon for internal sites

the younger dryas relevant in the australian region an assessment of australian climate during the younger dryas chronozone ydc is presented this review focuses on securely dated records from sites of continuous deposition placing greatest emphasis on temperature reconstructions with records of effective precipitation i e the combined effect of precipitation minus evapotranspiration also considered while there is a paucity of australian records covering the last glacial interglacial transition particularly those which directly infer temperature sufficient data exist to examine ydc climate from southern and eastern australia temperature reconstructions from tasmania based on both chironomid and pollen data show no evidence for younger dryas cooling by contrast there is evidence for cooling associated with the antarctic cold reversal from tullabardine dam pollen data and the sediment organic content from eagle and platypus tarns in tasmania records from a number of eastern australian mainland sites provide no evidence of effective precipitation shifts concurrent with the younger dryas chronozone similarly reconstructions of discharge from the murray darling basin which covers a large proportion 14 of the australian continent and dust transport from a larger portion of the continent also show no evidence of climate shifts concomitant with the younger dryas of research published in the past decade only one study located in the great australian bight claims evidence of a ydc cooling andres et al 2003 by contrast this review suggests that there is no conclusive evidence for cooling or indeed any distinctive climate patterning during the younger dryas chronozone in australia

palaeohydrology of lowland rivers in the murray darling basin australia abstract this study derives a new function describing the relationship of channel bankfull discharge qbf to channel width in modern rivers of the murray darling basin mdb of southeastern australia and applies this to dated palaeochannels of seven rivers to quantify late quaternary discharge history in this important basin all rivers show high mis3 and mis2 qbf declining in the holocene the qbf of modern mdb rivers is correlated with total catchment precipitation but comparison with palaeochannel qbf estimates shows that while enhanced runoff efficiency is necessary to account for much larger late pleistocene palaeochannels either lower or higher precipitation rates could have prevailed a strong association between relative palaeo qbf enhancement and temperature suggests a temperature mediated mechanism controlling river discharge such as the fraction of precipitation stored as snow and thawing in spring the enhancement of orographic rainfall or co2 feedbacks with vegetation cover significantly enhanced mis3 qbf requires an additional mechanism such as increased rainfall these findings are consistent with others that increased moisture availability was associated with past colder climates although this was not necessarily the result of enhanced precipitation

deep seismic reflection evidence for continental underthrusting beneath southern tibet the himalaya and adjacent tibetan plateau constituting earth s largest region of elevated topography and anomalously thick crust formed as a consequence of cenozoic collision between india and asia itself considered the archetypal continent continent collision1 3 here we report the first results from an attempt to image the structure of the crust beneath this region using deep seismic reflection profiling our 100 km long profile acquired in the tethyan himalaya shows a mid crustal reflection that prob ably marks the active thrust fault along which the indian plate is underthrusting southern tibet upper crustal reflections with geo metries suggestive of large scale structural imbrication of the upper crust and moho reflections from the base of the double normal thickness crust underlying the region these results lend substantial support to the view that crustal thickening beneath southernmost tibet was accomplished by wholesale underthrusting of indian continental crust beneath the structurally imbricated upper crust comprising the tethyan himalaya

crustal structure and variability of the himalayan border of tibet reversed critical wide angle reflection profiles of the crust mantle boundary south of the yarlung zangbo suture in tibet reveal a deep 70 km moho extending north from the high himalayas whilst to the south the moho is 15 km higher even further south reflections from 35 km depth may correspond to the moho of peninsular india

aeolian dust in east antarctica epica dome c and vostok provenance during glacial ages over the last 800 kyr aeolian mineral dust archived in antarctic ice cores represents a key proxy for quaternary climate evolution the longest and most detailed dust and climate sequences from polar ice are provided today by the vostok and by the epica dome c edc ice cores here we investigate the geographic provenance of dust windborne to east antarctica during early and middle pleistocene glacial ages using strontium and neodymium isotopes as tracers the isotopic signature of antarctic dust points towards a dominant south american origin during marine isotopic stage mis 8 10 12 and back to mis 16 and 20 as deduced from edc core data provide evidence for a persistent overall westerly circulation pattern allowing efficient transfer of dust from south america to the interior of antarctica over the last 800 kyr some small but significant dissimilarity between old and recent glacial ages suggests a slightly reduced patagonian contribution during ancient glaciations

a thin viscous sheet model for continental deformation summary for the purposes of describing its large scale and long term deformation the continental lithosphere is regarded as a continuum obeying a newtonian or a power law rheology the flow of a thin sheet of power law material overlying an inviscid substrate is studied under the assumption that vertical gradients of the horizontal velocity are negligible a numerical model is used to investigate the deformation of such a sheet under conditions approximating those of continent continent collision the material flows in response to forces applied to its boundaries for example the indenting of one continent by another and to forces in its interior arising from gradients in crustal thickness the horizontal divergence of the flow produces changes in the crustal thickness and hence a time dependent form to the flow itself for a given set of boundary conditions the flow depends on the stress exponent in the power law rheology n and on the argand number which is a measure of the ratio between the stress arising from crustal thickness contrasts and the stress required to deform the material at the ambient strain rates when the effective viscosity of the medium is very high ar o crustal thickness variations do not influence the flow if the material is newtonian n l the deformation associated with an influx of material approximating an indenter is of much greater lateral dimension than the width of the indenter whereas when material has a power law rheology n 3 5 are used the deformation is confined to a region of lateral extent comparable to that of the indenter as ar increases the forces arising from crustal thickness contrasts exert more influence on the flow and the maximum crustal thickness that can be sustained by a given influx of material is related by a simple expression to the effective viscosity of the medium at the ambient strain rates in the limit of a very weak medium ar 10 the lithosphere is unable to sustain appreciable crustal elevation contrasts the results of these numerical experiments show that systems in which the effective viscosities are such that the maximum deviatoric stresses are between 1 kbar

crustal deformation of the lhasa terrane tibet plateau from project indepth deep seismic reflection profiles international deep profiling of tibet and the himalaya indepth deep reflection data in the yangbajain damxung graben of southern tibet yield evidence of magmatism and deformation beneath the southern lhasa terrane and yarlung zangbo suture shallow reflections and low velocity first arrivals indicate a thin quaternary graben fill of generally less than a few hundred meters thickness underlying stratified reflections extending to a maximum of about 11 5 km depth likely originate from deformed paleozoic cenozoic supracrustal strata of the lhasa terrane a prominent undulatory band of reflections within the crystalline basement extends beneath the length of the yangbajain damxung graben depth ranges from 12 km to 18 km this horizon has been interpreted to mark the top of a midcrustal partial melt zone underlying southern tibet the undulatory character of this horizon additionally suggests that it may be tectonically deformed a somewhat deeper subhorizontal wide angle reflection extends southward beneath the outcrop of the yarlung zangbo suture indicating that the suture is cut off or superposed by a younger structure at depth three gently north dipping reflections at 19 km 24 km and 27 km depth beneath the gangdese batholith are suggestive of a midcrustal duplex and may mark the northward downdip extension of the late oligocene early miocene gangdese thrust system a prominent 40 north dipping reflection imaged in the deep crust beneath the gangdese batholith between 40 and 60 km depth might mark the downdip expression of the yarlung zangbo suture or alternatively a younger reverse fault in the lower crust or both viewed in aggregate the reflection data are suggestive of moderate postcollisional shortening of the upper crust of the lhasa terrane accompanied by melting of the middle crust although the data are permissive of wholesale underthrusting or fluid injection of indian continental crust beneath the lhasa terrane they show no direct evidence for this having occurred

simultaneous miocene extension and shortening in the himalayan orogen the south tibetan detachment system separates the high grade metamorphic core of the himalayan orogen from its weakly metamorphosed suprastructure it is thought to have developed in response to differences in gravitational potential energy produced by crustal thickening across the mountain front geochronologic data from the rongbuk valley north of qomolangma mount everest in southern tibet demonstrate that at least one segment of the detachment system was active between 19 and 22 million years ago an interval characterized by large scale crustal thickening at lower structural levels these data suggest that decoupling between an extending upper crust and a converging lower crust was an important aspect of himalayan tectonics in miocene time

spatial variability and hydrologic evolution of australian lake basins analogue for pleistocene hydrologic change and evaporite formation abstract processes evident in basins across hydrologic gradients from humid to arid regions today provide analogues for systems that may have operated in some individual basins during periods of past hydrologic change thus lakes in humid regions today with low salinity sedimentary facies and with morphology controlled largely by wave action may closely resemble past lacustral pluvial phases experienced in zones which today are relatively arid and saline conversely playas controlled today by groundwater and in some cases subject to defletion may resemble those arid and dune building stages experienced by basins in sub humid regions today as they underwent glacial age desiccation in any such sequence of spatial or temporal gradients from humid to more arid conditions the frequency of basin filling and drying modulates the rate of evaporitive loss of interstitial waters from the exposed basin surface this in turn controls the salinity evolution of the interstitial and local groundwaters the notion of closed systems for terminal lakes while satisfactory for analysis of surface water budgets is quite inapplicable to the evolution of brines where surfacewater groundwater exchange during the high salinity drying stages becomes a controlling factor affecting all salt budgets in these systems evaporites may only be preserved when the sub surface waters have evolved to salinites near saturation for the salts concerned if sub surface waters are frequently diluted by surfacewater groundwater exchange evaporites will not be preserved in the record even though the surface system appears hydrologically closed the process of interstitial water evolution which controls efflorescence deflation and salt weathering exerts a dominating influence on basin geomorphic expression as well as on hydrochemical fractionation

a gis based reconstruction of late quaternary paleohydrology lake eyre arid central australia lake eyre is the terminal playa in a large closed basin which receives the majority of its moisture from the summer monsoon modern lake eyre receives intermittent floodings at times of increased monsoon intensity generally associated with the la nin a phase of the enso cycle lake eyre was a perennial lake during several phases of increased monsoon activity during the late quaternary specifically about 125 ka 80 ka 65 ka and 40 ka magee 1997 late quaternary environments and palaeohydrology of lake eyre arid central australia unpubl ph d thesis australian national university canberra these lake highstands are reflected by elevated shorelines mapped around lake eyre and to a lesser degree around the frome gregory system to the southeast of lake eyre comprehensive research in the lake eyre catchment over the last several decades has constrained the ages and elevations of these shoreline deposits which now enable us to use digital elevation models to map these paleo lakes by incrementally filling each lake meter by meter the areas and volumes of the paleo lakes are calculated and the paleohydrologic processes including the flow direction across spillovers are reconstructed at the peak 125 ka highstand lake eyre stood at 10 m australian height datum ahd and covered nearly 35 000 km 2 more than three times the area of the current playa together with the frome gregory system it held 430 km 3 of water by contrast the deepest historic filling held 30 km 3 these lake levels represent climatic conditions very different from the modern situation due to discontinuous preservation of the shoreline deposits around the lakes and due to the scale of the lake systems mapping the former levels of lake eyre and the frome gregory system has been impossible prior to the availability of a digital elevation model paramatizing the area volume relationships of water required to fill the lake to varying levels will provide data for quantification of climate and precipitation changes over time h 2003 elsevier b v all rights reserved

distributed deformation in southern and western tibet during and after the india asia collision field and radiometric data are used to describe and date strain and stress states in southern longitude 88 o to 91oe latitude 28 o to 30on and western tibet longitude 79 o to 82oe latitude 30 o to 34on we factorize deformation into syncollisional and postcollisional and we present stretching lineation and displacement orientation maps two sections across the indian shelf sequence and stress orientations calculated from mesoscale fault slip data in southern tibet syncollisional stretching and displacement directions trend 90 46 o and displacement is top to south synkinematic low grade metamorphism is dated at 50 ma at one locality in the indian shelf sequence underlying the main mantle thrust of the indus yarlung suture this implies paleocene onset of continental collision for the investigated section postcollisional structures comprise a backthrust group which includes foreland and hinterland directed thrusts reverse and strike slip faults and folds it dominates postcollisional deformation is concentrated along the indus yarlung suture and portrays n s compression otrend of 8o 17 o o2 of 97o 17o a strike slip group consists of conjugate strike slip faults is concentrated in east trending narrow highly deformed zones and indicates that n s compression is locally compensated by e w extension oof 15o 29 o o3 of 103o 30o synkinematic muscovite dates postcollisional deformation as late early miocene 17 5 ma at one locality at the suture strike slip and oblique normal 03 of 600 23 o oof 144o 21 o and normal o3 114o 16 o faulting dated between late miocene and recent and including active deformation represents dominant e w and minor n s extension due to e w stretching of southern tibet and oroclinal bending along the himalayan arc restoring syncollisional and postcollisional deformation yields a minimum of 67 258 km shortening across the indian shelf sequence incorporating recently published contraction estimates across the eastern himalaya yields minimum shortening between undeformed india and the indus yarlung suture of 66 536 km the himalaya tibet orogenic system south of the indus yarlung suture had an initial width of 811 km in the southern tibetan section in western tibet imbrication of an ophiolite sequence of the bangong nujiang suture is top to south stretching lineation trend of 15o 18o and o3 of active deformation trends ese faulting along the shiquanhe fault zone which transfers displacement from the northern part of the karakorum fault to a system of rifts in western central tibet indicates dextral strike slip alternating with sinistral oblique normal faulting and block rotations around vertical axes during a prolonged shearing history the indian shelf sequence south of mount kailas shows top to south imbrication stretching lineation trend of 52o 60o both indian shelf rocks and oligocene miocene kailas conglo merates record backthrusting and backfolding oof 33 o and recent e w extension 03 of 85o 28o

distribution transport and deposition of mineral dust in the southern ocean and antarctica contribution of major sources 1 a model based investigation of the transport distribution and deposition of mineral dust in the southern hemisphere sh is performed by using the gfdl atmospheric model am2 the study represents an attempt to quantify the contribution of the major sources by tagging dust based on its origin we evaluate the contribution of each source to the emission distribution mass burden and deposition of dust in the southern ocean and antarctica and show that each source produces distinctive meridional transport vertical distribution and deposition patterns the dust in sh originates primarily from australia 120 tg a 1 patagonia 38 tg a 1 and the inter hemispheric transport from northern hemisphere 31 tg a 1 a small fraction of it 7 tg a 1 is transported and deposited in the southern ocean and antarctica where dust from south america australia and northern hemisphere are essentially located in the boundary layer mid troposphere and upper troposphere respectively these three sources contribute to nearly all the dust burden in the southern ocean and antarctica south america and australia are the main sources of the dust deposition but they differ zonally with each one dominating half of a hemisphere along 120 e 60 w the half comprising the atlantic and indian oceans in the case of the south american dust and the pacific half in the case of the australian dust our study also indicates a potentially important role of northern hemisphere dust as it appears to be a significant part of the dust burden but contributing little to the dust deposition in antarctica

continuous 150 k y monsoon record from lake eyre australia insolation forcing implications and unexpected holocene failure our reconstructed history of lake eyre provides the first continuous continental proxy record of australian monsoon intensity over the past 150 k y this continental record s broad correspondence to the marine isotope record demonstrates that this very large catchment with its hydrology dependent on a planetary scale climate element responds to milankovitch scale climate forcing abrupt transitions from dry phases to wet phases ca 125 and 12 ka coincide with northern hemisphere winter insolation minima rather than southern hemisphere summer insolation maxima indicating that northern hemi sphere insolation exerts a dominant control over the intensity of the australian monsoon stratigraphic and dating uncertainties of other wet phases preclude conclusive correlation to specific insolation signals but within the uncertainties are consistent with northern hemisphere forcing regardless of the hemispheric forcing the low intensity of the early holocene australian monsoon by comparison with the last interglacial and particularly the last high level lacustrine event at 65 60 ka when all forcing elements were modest is an enigma that can be explained by a change in boundary conditions within australia

geochemical fingerprinting of trans atlantic african dust based on radiogenic sr nd hf isotopes and rare earth element anomalies mineral dust is an important component of earth s climate system and biogeochemical cycles on a global scale in order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites we must be able to identify the source provenance of dust here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long range african dust lrad collected between 2003 and 2011 in the trade winds on the caribbean island of barbados we find systematic differences between sr nd hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport these results indicate that coherent geochemical source signatures of lrad can be preserved even after transport across thousands of kilometers we investigated the possibility of identifying the potential source areas through comparisons with literature data however these data are almost entirely based on measurements of soil and sediment samples this could lead to biases because of soil aerosol particle size and composition differences nonetheless our data suggest that many samples are linked to sources in mali and sub saharan regions radiogenic nd hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites in order to establish firmer links between lrad and dust source areas however we require much more data on the geochemical composition of aerosols from potential source areas in north africa

dust provenance in antarctic ice during glacial periods from where in southern south america 1 the origin of dust deposited in east antarctica is not fully understood yet this study demonstrates that contrary to nd sr isotopes are strongly fractionated in the finest sized material representing potential dust sources in south america analysis of nd isotopes suggests that argentine loess southern ocean sediments and antarctic dust may all have a related origin or can represent comparable mechanisms of eolian sediment transport and deposition this analysis also concludes that the patagonian signature can explain a high proportion of the isotopic composition of dust trapped in antarctic ice during glacial periods the puna altiplano plateau emerges as the second possible important sediment contributor explaining the crustal like signature found in east antarctic dust and should be considered as a potential source area when quaternary paleoclimate is reconstructed from argentine loess antarctic dust and south atlantic sediment records

finite strain calculations of continental deformation 2 comparison with the india asia collision zone numerical experiments on a thin viscous sheet model for deformation of continental lithosphere subjected to an indenting boundary condition yield distributions of crustal thickness of stress and strain rate and of latitudinal displacements that may be compared with observations in the india asia collision zone a simple indenting boundary condition applied to initially laterally homogeneous sheets obeying a power law rheology produces results that are in broad agreement with the observations provided that the power law exponent is three or greater and the sheet can support vertically integrated stress differences of 2 1013 5 1012 n m 1 in regions in front of the indenter under these conditions the calculated deformation shows accommodation of convergence primarily by crustal thickening to produce a plateau in front of the indenter palaeomagnetic data from india and tibet and the observed distribution of topography suggest that much of the post eocene convergence of india with asia has been taken up by deformation within asia that involved crustal thickening the principal difference between calculation and observation is the absence from the calculated strain rate fields of east west extension of the plateau in front of the indenting boundary the calculations show that once such a plateau is formed the buoyancy force associated with the crustal thickness contrast inhibits further thickening and the plateau strains at less than half the rate of its immediate surroundings seismically determined regional strain rates exhibit a similar distribution with the tibetan plateau straining at about one quarter the rate of the tien shan and ningxia gansu regions calculated principal compressive stress orientations and regional strain rates agree with the seismically determined quantities in the mongolia baikal tien shan tibet and ningxia gansu regions of asia to within the uncertainty of the latter the vertically integrated stresses that are calculated for the viscous sheet are comparable with those that can be supported by a theologically stratified continental lithosphere obeying laboratory determined flow laws we suggest that the thin viscous sheet model described in this paper and its companion gives a simple and physically plausible description of the observed deformation in central asia in this description the predominant mechanism of accommodation of continental convergence is diffuse crustal thickening with shear on vertical planes playing a subsidiary role once large crustal thickness contrasts have been established

a box model of the blocked outflow scenario for the messinian salinity crisis abstract part of the kilometre thick messinian evaporites of the mediterranean basin is thought to have formed in a configuration of continuous inflow of water and salt from the atlantic ocean in combination with blocked return flow this mechanism is here examined for the first time quantitatively using a simple box model with parametrised exchange between sub basins and including a representation of mixing we also explore systematically the conditions under which the blocked outflow state arises the main results are 1 the rate of salinity increase is fast 2 the western and eastern sub basin evolve in concert except when exchange at the connecting strait is greatly reduced and then only when the basins are poorly stratified and 3 near complete separation from the atlantic is required to reach saturation unless mediterranean waters are strongly stratified

dust composition changes from taylor glacier east antarctica during the last glacial interglacial transition a multi proxy approach abstract mineral dust is transported in the atmosphere and deposited in oceans ice sheets and the terrestrial biosphere temporal changes in locations of dust source areas and transport pathways have implications for global climate and biogeochemical cycles the chemical and physical characterization of the dust record preserved in ice cores is useful for identifying of dust source regions dust transport dominant wind direction and storm trajectories here we present a 50 000 year geochemical characterization of mineral dust entrapped in a horizontal ice core from the taylor glacier in east antarctica strontium sr and neodymium nd isotopes grain size distribution trace and rare earth element ree concentrations and inorganic ion cl and na concentrations were measured in 38 samples corresponding to a time interval from 46 kyr before present bp to present the sr and nd isotope compositions of insoluble dust in the taylor glacier ice shows distinct changes between the last glacial period lgp in this study ranging from 46 7 15 3 kyr bp the early holocene in this study ranging from 14 5 8 7 kyr bp and zero age samples the 87sr 86sr isotopic composition of dust in the taylor glacier ice ranged from 0 708 to 0 711 during the lgp while the variability during the early holocene is higher ranging from 0 707 to 0 714 the end composition ranges from 0 1 to 3 9 during the lgp and is more variable from 1 9 to 8 2 during the early holocene the increased isotopic variability during the early holocene suggests a shift in dust provenance coinciding with the major climate transition from the lgp to the holocene the isotopic composition and multiple physical and chemical constraints support previous work attributing southern south america ssa as the main dust source to east antarctica during the lgp and a combination of both local ross sea sector dust sources and ssa after the transition into the holocene this study provides the first high time resolution data showing variations in dust provenance to east antarctic ice during a major climate regime shift and we provide evidence of changes in the atmospheric transport pathways of dust following the last deglaciation

a uniform isotopic and chemical signature of dust exported from patagonia rock sources and occurrence in southern environments patagonia is considered to be the most important source of dust from south america that is deposited in surrounding areas and we present here a systematic sr and nd isotopic study of sediment currently being exported eolian and suspended riverine sediments from patagonia have a homogeneous chemical and isotopic composition that results from the mixing of by products from explosive andean volcanism derived from the extensive jurassic silicic province of chon aike and pyroclastic materials from the basic to intermediate southern andean quaternary arc which are easily denudated and dispersed the main andean uplift and the glaciations that began in the late tertiary account for the extensive distribution of these sediments in the extra andean region the present geochemical signature of patagonian sediments was produced during the pleistocene along with the onset of the southern andean explosive arc volcanism previously published compositions of sediments from other southern south american source regions assumed to be representative of patagonia are distinct from our data considering the alleged importance of patagonia as a dust source for different depositional environments in southern latitudes it is surprising to verify that the chemical and isotopic signatures of patagonian sourced sediments are different from those of sediments from the southern ocean the pampean region or the antarctic ice sediments from these areas have a crustal like geochemical signature reflecting a mixed origin with sediment from other southern south american sources whereas patagonian sediments likely represent the basic to intermediate end member composition

tectonic geomorphology of australia the australian continent is actively deforming in response to far field stresses generated by plate boundary interactions and buoyancy forces associated with mantle dynamics on the largest scale several 10 3 km the submergence of the northern continental shelf is driven by dynamic topography caused by mantle downwelling along the indo pacific subduction system and accentuated by a regionally elevated geoid the emergence of the southern shelf is attributed to the progressive movement of australia away from a dynamic topography low on the intermediate scale several 10 2 km low amplitude c 100 200 m long wavelength c 100 300 km topographic undulations are driven by 1 anomalous smaller scale upper mantle convection and or 2 lithospheric scale buckling associated with plate boundary tectonic forcing on the smallest scale 10 1 km fault related deformation driven by partitioning of far field stresses has modified surface topography at rates of up to c 170 m ma 21 generated more than 30 50 of the contemporary topographic relief between some of australia s highlands and adjacent piedmonts and exerted a first order control on long term 10 4 10 6 a bedrock erosion although australia is often regarded as tectonically and geomorphologically quiescent neogene to recent tectonically induced landscape evolution has occurred across the continent with geomor phological expressions ranging from mild to dramatic australia is one of the lowest flattest most arid and most slowly eroding continents on earth the average elevation of the continent is only c 330 m above sea level asl maximum local topographic relief is everywhere 1500 m defined by elevation ranges with 100 km radii and two thirds of the con tinent is semi arid to arid with the exception of localized upland areas in the flinders and mt lofty ranges and the eastern highlands bedrock

antarctic dome c ice core dust at 18 k y b p isotopic constraints on origins we have determined the source area from which dusts from the last glacial maximum lgm section of the dome c ice core were derived by comparing their strontium and neodymium isotopic ratios with those of samples from potential source areas the87sr 86sr and143nd 144nd isotope ratios of the dusts deposited 18 k y b p at the east antarctic dome c site were compared with potential antarctic australian southern african and south american sources the isotope ratios clearly define the patagonian provenance of the dust with the other potential source areas being at most minor contributors contributions by volcanic ash and tephra to the dust sample were also determined to be minimal based on the patterns of rare earth elements knowing the source of the dusts places constraints on the aeolian trajectory by which it was transported to antarctica and this serves as a test of the simulation of southern hemispheric circulation by atmospheric global circulation models during the lgm

alluvial evidence for major climate and flow regime changes during the middle and late quaternary in eastern central australia as a low gradient arid region spanning the tropics to the temperate zone the lake eyre basin has undergone gentle late cenozoic crustal warping leading to substantial alluvial deposition thereby forming repositories of evidence for palaeoclimatic and palaeohydrological changes from the late tertiary to the holocene auger holes and bank exposures at five locations along the lower 500 km of cooper creek a major contributor to lake eyre in the eastern part of the basin yielded 85 luminescence dates tl and osl that combined wit a further 142 luminescence dates from northeastern australia have established a chronology of multiple episodes of enhanced flow regime from about 750 ka to the holocene mean bankfull discharges on cooper creek upstream of the innamincka dome at 250 230 ka or oxygen isotope stages ois 7 6 are estimated to have been 5 to 7 times larger than those of today however substantially less reworking has occurred during and after ois 5 than before lower cooper creek appears to have similarly declined in the tirari desert adjacent to lake eyre there is evidence of widespread alluvial activity perhaps during but certainly before the middle pleistocene yet the river became laterally restricted in ois 7 to 5 while the quaternary has been characterised by a dramatically oscillating wet dry climate since oxygen isotope stage ois 7 or 6 there has been a general decline in the magnitude of the episodes of wetness to which the eastern part of central australia has periodically returned during the last full glacial cycle cooper creek s periods of greatest runoff and sand transport were not during the last interglacial maximum of ois 5e 132 122 ka but later in ois 5 when sea levels and global temperatures were substantially below those of 5e or today fluvial activity returned in ois 4 and 3 but not to the extent of mid and late ois 5 strongly seasonal but still powerful flows transported sand and fed source bordering dunes in ois 5 and 3 this chronology of fluvial activity in the late quaternary broadly coincides with that for rivers of southeastern australia and suggests that the wet phases in eastern central australia have not been governed as much by the northern monsoon as by conditions in the western pacific close to the east coast both north and south flow confinement within the innamincka dome has locally amplified cooper creek s energy and here evidence exists for short but high magnitude episodes of flow during the last glacial maximum and in the early to middle holocene conditions that were capable of forming large palaeochannels but that were not long lived enough to rework the river s extensive floodplains elsewhere along its length

geochemical and microbiological fingerprinting of airborne dust that fell in canberra australia in october 2002 during the night of 22 23 october 2002 a large amount of airborne dust fell with rain over canberra located some 200 km from australia s east coast and at an average altitude of 650 m it is estimated that during that night about 6 g m 2 of aeolian dust fell we have conducted a vast number of analyses to fingerprint some of the dust and used the following techniques grain size analysis scanning electron microscope imagery major trace and rare earth elemental plus sr and nd isotopic analyses organic compound analyses with respective compound specific isotope analyses pollen extraction to identify the vegetation sources and molecular cloning of 16s rrna genes in order to identify dust bacterial composition dna analyses show that most obtained 16s rrna sequences belong mainly to three groups proteobacteria 25 bacteriodetes 23 and gram positive bacteria 23 in addition we investigated the meteorological conditions that led to the dust mobilization and transport using model and satellite data grain sizes of the mineral dust show a bimodal distribution typical of proximal dust rather than what is found over oceans and the bimodal aspect of size distribution confirms wet deposition by rain droplets the inorganic geochemistry points to a source along near the darling river in nw new south wales a region that is characteristically semiarid and both the organic chemistry and palynoflora of the dust confirm the location of this source area meteorological reconstructions of the event again clearly identify the area near bourke cobar as being the source of the dust this study paves the way for determining the export of australian airborne dust both in the oceans and other continents

wetting and drying of australia over the past 300 ka alternately dry and wet climatic episodes across central and eastern australia during the past 300 ka have greatly affected australia9s rivers lakes and dune fields evidence of widespread climate and flow regime changes has been provided by 75 thermoluminescence tl dates and 18 u th dates from alluvial and eolian sediments fluvial conditions dominated part of the last two interglacials stage 5 and 7 resulting in large sand loads in rivers in the present simpson desert and southeastern australia during the last interglacial fluvial activity in central australia peaked at 110 ka stage 5 pluvial probably 5 10 ka behind world temperature and sea level maxima following the last late interglacial wet phase aridity associated with dune building spread from central australia toward its margins achieving greatest intensity during the last glacial maximum a less widespread wet phase identified at about 55 35 ka stage 3 subpluvial is associated with high lake levels and paleochannel activity in southeastern australia this tl record of variable continental aridity in australia correlates well with global changes including the variable eolian dust flux into central china the northern pacific ocean and antarctica

patagonian origin of glacial dust deposited in east antarctica vostok and dome c during glacial stages 2 4 and 6 abstract the source area of continental dust deposited at both vostok and dome c sites east antarctica during the glacial stages stage 2 18 ka last glacial maximum stage 4 60 ka and stage 6 160 ka of the last two climatic cycles has remained constant the isotopic composition 87 sr 86 sr and 143 nd 144 nd of the ice core dust has been compared with the isotopic composition of the potential source areas antarctica new zealand southern africa australia and south america this comparison reveals the southern south american provenance of the dust for all three glacial periods as has already been shown for the lgm 1 we show that the patagonian loess and the marine shelf sediments from the argentine continental shelf which was variably emerged during glacial periods display different isotopic compositions and that the composition of the patagonian loess best matches the signature of the ice core dust the identification of the patagonian region as the source of the windblown dust deposited over east antarctica during all the latest glacial periods permits a better understanding of paleo atmospheric circulations of the last climatic cycles and a better constraint on the parametrization of dust sources for paleoatmospheric general circulation models

relationships between desert dunes during the late quaternary in the lake frome region strzelecki desert australia transverse and linear dunes near the ephemeral lake frome in the strzelecki desert of australia provide evidence for a genetic geomorphic relationship between desert dune types transverse dunes overlying palaeoshorelines lie upwind from linear dunes the sedimentology of both dune types is similar suggesting reworking or downwind transport of the same source material over time clay pellets from several horizons within the linear and transverse dunes provide evidence for fluctuating water tables and high evaporation rates during those periods of aeolian activity along with saltinflux associatedwith thedeflation oflakefrome weconclude thatthe nature andinitiation of dune activity is controlled not only by aridity but by local hydrology osl ages from both transverse and linear dunes indicate aeolian activity at 66 57ka and 22 11ka transverse dune building took place around 106 111ka linear dune activity initiated at least 66ka ago with reactivation around 43 28ka followed by pedogenesis in response to humid conditions widespread dune reactivation from around 22ka correlates broadly with the last glacial maximum and late glacial period consistent with evidence of cold arid conditions and dune activity in australia copyright 2007 john wiley sons ltd

continental underplating model for the rise of the tibetan plateau abstract subduction of continental lithosphere entrained in an oceanic plate for distances of several hundred kilometers can lead to continental underplating whereby the continental crust with or without its lithospheric mantle is detached at depth from the main part of the sinking slab and rises buoyantly beneath the overriding plate the rising continental material causes first extension in the overriding plate as the asthenosphere flows laterally and later rapid isostatic uplift when it reaches the base of the overriding lithosphere this continental underplating model is applied to the geology of the tibetan region and the following stages are identified 100 ma to 50 ma oceanic subduction leading to continental collision 50 ma to 20 ma pause in convergence with possible delamination of indian crust 20 ma to 5 ma continental subduction initially at an angle of 30 of indian lithosphere along the main central thrust 5 ma to 2 ma rise of the continental lithosphere displacing the asthenosphere beneath tibet and causing widespread graben formation 2 ma to present contact between the underplating indian continental lithosphere and the overlying asian crust leading to rapid rise of the surface altitude by 3 4 km present day convergence between india and tibet albeit at a rate much less than the total india eurasia convergence continues as continental underthrusting

provenance of dust to antarctica a lead isotopic perspective antarctic ice preserves an 800 kyr record of dust activity in the southern hemisphere major efforts have been dedicated to elucidate the origin of this material in order to gain greater insight into the atmospheric dust cycle on the basis of pb isotopes in antarctic dust samples and potential sources this contribution demonstrates for the first time that patagonia is the main contributor of dust to antarctica during interglacial periods as well as glacials although the potential importance of tierra del fuego remains unclear because of its geochemical similarities to patagonia an important new finding is that the puna altiplano sector of the continent is a second important dust source to eastern antarctica during both glacials and interglacials being more prominent during interglacials the data indicate south america is the primary dust source to antarctica during both glacials and interglacials

tertiary structural evolution of the gangdese thrust system southeastern tibet structural and thermochronological investigations of southern tibet xizang suggest that intracontinental thrusting has been the dominant cause for formation of thickened crust in the southernmost tibetan plateau since late oligocene two thrust systems are documented in this study the north dipping gangdese system gts and the younger south dipping renbu zedong system rzt west of lhasa the gangdese thrust juxtaposes the late cretaceous forearc basin deposits of the lhasa block the xigaze group over the tethyan sedimentary rocks of the indian plate whereas east of lhasa the fault juxtaposes the late cretaceous eocene andean type arc the gangdese batholith over tethyan sedimentary rocks near zedong 150 km southeast of lhasa the gangdese thrust is marked by a 200 m thick mylonitic shear zone that consists of deformed granite and metasedimentary rocks a major south dipping backthrust in the hanging wall of the gangdese thrust puts the xigaze group over tertiary conglomerates and the gangdese plutonics north of xigaze and west of lhasa a lower age bound for the gangdese thrust of 18 3 0 5 ma is given by crosscutting relationships the timing of slip on the gangdese thrust is estimated to be 27 23 ma from 40 ar 39 ar thermochronology and a displacement of at least 46 9 km is indicated near zedong the age of the gangdese thrust gt is consistent with an upper age limit of 24 ma for the initiation of movement on the main central thrust in places the younger renbu zedong fault is thrust over the trace of the gt obscuring its exposure the rzt appears to have been active at circa 18 ma but had ceased movement by 8 1 ma the suture between india and asia has been complexly modified by development of the gts rzt and locally strike slip and normal fault systems

an evaluation of australia as a major source of dust abstract since australia is the driest inhabited continent it is a natural laboratory to study on a large scale dust its composition its sources transport and geochemical composition this is necessary as there has been a lack of appreciation of the diversity of the australian regolith characterized by a great array of ages and compositions this is particularly true of studies that examined the geochemistry of australian dusts and links with potential deposition sites such as in antarctica and comparison with south america hence the first part of this paper provides an overview of the surficial geology of australia with emphasis on regions from where dust can become deflated a review follows on the investigations of significant dust transport and events in australia the second part of the paper provides a review of the sites of potential deflation of dust it includes the study of different geomorphological sites of dust deflation with a discussion on how dust particles can accumulate in regions linked to large playa lakes that are under the influence of groundwater below them this is an important mode of dust deflation a process of which had insufficiently been detailed before the processes involving evaporative pumping are explained and several illustrations are provided to document those processes and location of dust deposits another region of importance to dust deflation consists of extensive alluvial plains and these are also documented with an area in the upper reaches of the darling river being now documented more fully finally the inter dunal corridors in large dune fields are also mentioned as a source of dust as previous studies already show this second part ends with the description of the two main potential source areas psa of dust in australia and these are the kati thanda lake eyre region of central australia and the darling riverine plain in the upper reaches of the darling river these two regions are important for their geochemical fingerprints for transcontinental studies and supported by satellite imagery that identify dust plumes originating from these regions the third part of the paper examines the geochemical composition of australian psas by paying particular attention to neodymium strontium and lead isotopic ratios from both continents we also suggest the possibility of combining nd and pb isotopes as a way of fingerprinting geochemically between different australian regions and for comparison with other continental psas this part also reviews previous studies that aimed at geochemically fingerprinting the australian regolith by referring also how these studies were applied to reconstruct past environmental conditions

lacustrine fluvial interactions in australia s riverine plains climatic forcing of fluvial systems has been a pre occupation of geomorphological studies in australia since the 1940s in the riverine plain southeastern australia the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world surficial sediments and landforms exceed 140 000 yr in age and geomorphological change recorded in the fluvial fluvio lacustrine and aeolian features have provided a well studied record of quaternary environmental change over the last glacial cycle the region includes the willandra lakes whose distinctive lunette lakes preserve a history of water level variations and ecological change that is the cornerstone of australian quaternary chronostratigraphy the lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the australian continent to date the lake level and palaeochannel records in the lachlan willandra system have not been fully integrated making it difficult to establish the regional significance of hydrological change here we compare the willandra lakes environmental record with the morphology and location of fluvial systems in the lower lachlan an ancient channel belt of the lachlan willandra creek acted as the main feeder channel to willandra lakes before channel avulsion caused the lakes to dry out in the late pleistocene electromagnetic surveys geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion single grain optical dating of floodplain sediments indicates that sedimentation in the new middle billabong palaeochannel had commenced before 18 4 1 1 ka a second avulsion shifted its upper reaches to the location of the present lachlan river by 16 2 0 9 ka the timing of these events is consistent with palaeohydrological records reconstructed from willandra lakes and with the record of palaeochannels on the lachlan river upstream willandra lakes shows high inflows during the last glacial maximum 22 ka but their subsequent drying between 20 5 ka and 19 ka was caused by river avulsion rather than regional aridity this case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains

stratigraphic architecture resulting from late quaternary evolution of the riverine plain south eastern australia the riverine plain of south eastern australia is the result of prolonged cenozoic fluvial activity single thread anabranching and distributary channels and floodplains and associated aeolian dunes characterize the uppermost sequences based on detailed interpretations of late quaternary fluvial sedimentation and surficial stratigraphy for this 77 000 km2 basin earlier prior stream and ancestral stream models of fluvial deposition deduced from limited stratigraphic and chronological evidence are replaced with aggradational palaeochannel and migrational palaeochannel models thermoluminescence dating reveals four distinct phases of palaeochannel activity between 105 and 12 ka the first coleambally phase late in oxygen isotope stage 5 the second kerarbury phase in stage 3 the third gum creek phase before and the fourth yanco phase after the last glacial maximum lgm in stage 2 the first three of these phases were characterized by mixed load laterally migrating sinuous palaeochannels with occasional transitions to a straighter bedload dominated mode and vice versa the first two phases concluded with a bedload dominated episode resulting in aggradational palaeochannels on the surface of the plain and the third phase prior to the lgm did also in its downstream reaches the phase following the lgm was characterized entirely by large mixed load sinuous migrational palaeochannels these exhibited no terminating bedload episode because the onset of holocene climates reduced the size of the flood peaks greatly diminished the supply of bedload from the upper catchments and resulted in streams evolving to their present highly sinuous suspended load form the result is a complex stratigraphic architecture consisting of vertically and laterally accreted units extending over hundreds of kilometres in the form of channel sand stringers sand sheets and derivative aeolian dunes partially or wholly encased in overbank fines

aeolian dust in the talos dome ice core east antarctica pacific ross sea sector victoria land versus remote sources over the last two climate cycles a new ice core taldice drilled at talos dome east antarctica ross sea sector preserves a ca 250 ka long record of palaeoclimate and atmospheric history we investigate dust variability and provenance at the site during glacial periods and the holocene through the sr nd isotopic composition of ice core dust and potential source areas psa we provide new isotopic data on dust sources from victoria land such as regoliths glacial drifts aeolian sands and beach deposits some of these sources are located at high altitude and are known to have been ice free throughout the pleistocene the major features of the taldice dust record are very similar to those from central east antarctica during glacial times south america was the dominant dust supplier for talos dome as well as for the entire east antarctic plateau conversely during the holocene the principal input of mineral dust at talos dome probably derives from proximal sources which are the ice free areas of northern victoria land located at similar altitude with respect to the drilling site atmospheric mobilisation of dust from these neighbouring areas and transport inland to talos dome can be ultimately associated with advection of maritime air masses from the pacific ross sea region copyright 2010 john wiley sons ltd supporting information can be found in the online version of this article

ground satellite observations and atmospheric modeling of dust storms originating in the high puna altiplano deserts south america implications for the interpretation of paleo climatic archives 1 this study provides a detailed description of the sources transport dispersion and deposition of two major dust events originating from the high altitude subtropical puna altiplano plateau 15 26 s 65 69 w in south america a long and severe drought provided the right conditions for the onset of both events in july 2009 and 2010 dust was transported se and deposited over the pampas region and was observed to continue to the atlantic ocean dust monitoring stations located downwind recorded both events and samples were characterized through chemical and textural analysis through a combination of meteorological data and satellite observations calipso and modis detectors we estimate the emission flux for the 2010 event this estimate was used to constrain the hybrid single particle lagrangian integrated trajectory hysplit transport model and simulate the dust event both satellite imagery and model results agree in the location and extension of the dust cloud calipso detected dust between 6000 and 8500 m a s l which remained at this height during most of its trajectory the dust cloud mixed with a strong convective system in the region and the associated precipitation brought down significant amounts of dust to the ground dust particle size analysis for both events indicates that near the sources dust samples show median modes of 12 4 14 1 m similar to modes observed 1300 km away chemical composition of sediments from potential dust sources shows distinct signatures within the puna altiplano plateau the puna sector being clearly different from the altiplano area in addition both sources are markedly different from the patagonian chemical fingerprint these results have important implications to improve the interpretation of paleo environmental archives preserved on the argentine loess antarctic ice cores and southern ocean marine sediments

seismic mapping of crustal structures beneath the indus yarlung suture tibet records of densely spaced shots along the sino us reflection line indepth ii at offsets between 70 and 130 km parallel to the main profile provide an image of the crust straddling the indus yarlung suture the major features are prominent reflections at about 20 km depth beneath and extending out to about 20 30 km north and south of the surface exposure of the suture and north dipping reflectors north of the suture various interpretations for the reflections are possible i they represent a decollement possibly of the gangdise thrust system in this scenario the surface expression of the gangdise thrust as mapped in eastern south tibet is a splay with the decollement continuing southwards and either ending as a blind thrust or ramping up as one of the thrusts within the northernmost tethyan shelf sequence ii the reflections represent fabrics within gneisses partly obliterated by intrusions reaching various levels of the crust the reflection bands may be interpreted in terms of deformation or sedimentary structures belonging to the indian crust the accretionary complex and the basement of the gangdise belt the intrusions could be related to the tethyan leucogranites south of the suture rinbung leucogranite and to the gangdise magmatic arc to the north of the suture iii the reflections represent a fortuitous coincidence of different features north and south of the suture south of the suture the reflections may record the basement cover interface of the indian crust or a thrust system in the tethyan shelf north of the suture they may comprise different levels within the gangdise belt and its basement although it is not possible to discriminate between the suggested scenarios without additional information the seismic mapping points to the importance of post collisional oligocene miocene tectonics which reshaped the suture

environmental character and history of the lake eyre basin one seventh of the australian continent abstract one of the world s largest internally drained endorheic basins the 1 14 million km 2 lake eyre hydrological basin leb covers nearly 15 of the australian continent palaeoclimatic and associated flow regime variations are recorded in an archive of fluvial aeolian and lacustrine sediments that are particularly accessible for deposits from the past 300 ka and are especially relevant for the past 50 ka during which humans have inhabited australia due to its great size economic resources and diverse latitudinal extent it has for over six decades been the focus of environmental scientific and resource based studies across numerous disciplines with an emphasis on assessing the scientific and environmental research over this period this paper is divided into four parts part a provides an introduction and background part b provides the geological history including evidence of substantial tertiary and quaternary climate change part c covers the contemporary environmental conditions and part d presents a conclusion and summary this not only represents the first comprehensive review of current knowledge of any of the world s truly large dryland drainage basins but also highlights how more multi disciplinary research is required key remaining questions revolve around the impact of global weather systems on the leb the lake level story in relation to a more precise picture of late quaternary climate change the role of humans and climate in the demise of the megafauna modern hydrological changes the role of vegetation in altering channel morphology and flow efficiencies and nature of flood transmissions

age constraints on surface deformation recorded by fossil shorelines at cape range western australia laterally continuous terraces along the western flank of cape range western australia record both past sea level highstands and postdepositional vertical displacement four distinct fossil coral reef terraces extend nearly the entire length of the slowly uplifting anticlinal structure 100 km enabling documentation of the timing and degree of deformation induced elevation contamination of past sea level estimates from fossil shorelines here we present detailed elevations of the four terraces using differential global positioning system dgps and airborne light detection and ranging lidar data sets along with new ages for the three upper terraces geochemical dating using strontium isotope stratigraphy techniques revealed from highest to lowest elevation a late miocene reef terrace a late pliocene shoreline and a prominent mid pleistocene reef terrace probably associated with the marine oxygen isotope stage 33 31 interglacial along with a broad last interglacial eemian reef terrace and lagoon which terminate at the modern shoreline laterally variable elevation data integrated with newly defined ages for the terraces demonstrate a gradual and continuous relative deformation in the region that spans at least the last 6 5 m y and constrains the emergence of the cape range to sometime prior to the late miocene this data set also shows that the most recent interglacial shoreline has undergone 1 3 m of vertical warping suggesting minimal deformation since deposition by tracing relative uplift rates over multiple terraces for 100 km of coastline we placed constraints on maximum relative sea level rsl for the older terraces most notably we were able to place strict maximum rsl elevations of 34 m on the pliocene terrace and 16 5 m on the mid pleistocene terrace with probable rsl being somewhat lower

lhasa block and bordering sutures a continuation of a 500 km moho traverse through tibet a north south wide angle fan profile through the yarlung zangbo suture across the lhasa block and through the bangong nujiang suture shows several significant and sharp changes in crustal thickness both sutures appear as vertical 20 km steps in the moho and may have been the loci for eastward strike slip motion of the tibetan lithosphere