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

quartz fabrics in the alpine fault mylonites influence of pre existing preferred orientations on fabric development during progressive uplift strong quartz crystallographic preferred orientations cpos were developed during dislocation creep in the mylonite zone exposed in the hanging wall of the dextral reverse alpine fault zone new zealand the cpos have a consistent asymmetry indicating a high ratio of simple to pure shear strain with a shear sense of dextral up to the nw consistent with the mesoscopic shear sense indicators and with slip on the active fault there is a transition from y maxima and asymmetric single girdles in mylonites and ultramylonites within 300 m of the present fault trace to cross girdle fabrics in the protomylonites further from the fault the strong y maxima or single girdle cpos are ascribed to high ductile shear strains under amphibolite facies conditions while the cross girdle patterns found in the protomylonites are interpreted to represent deformation under lower temperature conditions however the observed fabric transition cannot logically be attributed to variations in temperature during the last increment of deformation the highly oriented y maximum fabrics formed at high temperature contain very few grains suitably oriented for basal slip so that the slip systems activated during subsequent shear at lower temperatures during exhumation were prism or rhomb further from the fault where shear strains under high temperature conditions were lower weaker fabrics developed under these conditions were modified at higher levels in the crust into crossed girdle patterns this interpretation implies that intense localisation of shear strain along the fault zone within the lower crust must have occurred in order for the high temperature fabrics to become sufficiently intense to be preserved this in turn implies that deep seated localised shear was taking place early during the evolution of the current oblique slip plate boundary fault the results of this study also indicate that the current model that operation of certain slip systems in quartz is mostly a function of temperature is incorrect future work should consider the effects of deformation history total strain and the presence of other mineral phases

age of desert dunes near birdsville southwest queensland abstract a mild controversy has arisen concerning the age of sand ridges in the eastern simpson desert around birdsville stratigraphic evidence indicates a holocene age but thermoluminescence tl dating of two sand samples from the area gave ages of about 34 ka and almost 78 ka wollongong laboratory in an attempt to resolve the difficulty sand samples were collected and dated by optically stimulated luminescence osl from a dune east of birdsville though low the dune is fully exposed in section so that basal sand as well as sediment from the substrate below the gibber were sampled the substrate gave dates of 36 ka the basal sand about 10 ka and sand from higher levels about 9 ka no younger sand was present and the dune is construed as the clay cemented core of a dune from which loose sand has been stripped by the wind samples of uncemented sand from the crests and flanks of higher dunes and from a clayey lee side mound in the same area gave dates around 1 ka or less

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

fabric analysis by orientation distribution functions abstract crystalline materials natural or artificial may consist of several phases minerals the crystal structures and relative amounts of which will generally be known in order to fully characterize such a material also the form and spatial distribution of the phases the grain structure and lattice defects and their distribution must be specified by appropriate distribution functions among these the orientation distribution function texture fabric structure plays an important role it can be deduced from experimental pole figures by series expansion methods in textured materials two different symmetries can be distinguished the crystal symmetry and the statistical sample symmetry special consideration must be given to the inversion centre as an element of either of these symmetries and in friedels law a complete description of all possible sample symmetries can be given in terms of black white symmetry groups the determination of the odd part of the texture function is strongly related to these groups and the various kinds of the inversion centre each combination of a certain crystal symmetry group with a certain sample symmetry group induces a certain space group in the orientation space the proper consideration of which minimizes the required amount of numerical calculations the texture function odf is the most important factor in the relation between anisotropic properties of single crystals and the polycrystalline material changes of the odf can be used as a sensitive indicator for solid state processes having occurred in the material

an evaluation of criteria to deduce the sense of movement in sheared rocks some of the most useful criteria for the deduction of the sense of shear are summarized for use in areas where unequivocal field evidence is lacking apparently conflicting evidence from rotated pressure shadow regions around porphyroclasts and porphyroblasts is clarified the use of quartz crystallographic fabric asymmetry to deduce the shear sense in the bulk rock should be treated with caution and used only together with detailed microstructural observations

the schneeberg normal fault zone normal faulting associated with cretaceous se directed extrusion in the eastern alps italy austria abstract the cretaceous eo alpine collisional event in the european eastern alps is generally accepted to induce w nw directed thrusting both in basement and in sedimentary cover units this study presents the first evidence of eo alpine w nw directed normal kinematics along the schneeberg normal fault zone which separates eo alpine high pressure rocks in a footwall position from pre alpine basement rocks in a hanging wall position new garnet sm nd data indicate that exhumation of the high pressure rocks along the normal fault zone started around 95 ma ago and continued up to low greenschist brittle conditions at 76 ma as indicated by a rb sr age from a low temperature mylonite the occurrence of pre alpine basement rocks both in the hanging wall and the footwall of eo alpine high pressure rocks suggests exhumation by extrusion processes despite the displacement or removal of parts of the lower portion of the high pressure unit by tertiary strike slip faults eo alpine top to ese thrusting as expected for the structurally lower part of an extruding wedge was found at and below the base of the eo alpine high pressure rocks a rb sr age of 77 ma from a greenschist facies mylonite in this thrust shear zone shows the contemporaneity of deformation at the base and the top of the wedge the tectonic transport direction within the extruding wedge was e se opposite to the w nw direction so far reported for the eo alpine event in the eastern alps the contemporaneity of opposite tectonic transport directions during continental subduction may be explained by a double vergent wedge model with a narrow zone of ductile flow where the high pressure rocks were exhumed

pt paths from modal proportions application to the koralm complex eastern alps thermodynamic pseudosections portray those parts of a petrogenetic grid that are relevant to a given bulk composition and the reactions appearing on them can therefore be used directly to infer the pt path that the rock followed however for many normal bulk compositions the use of pseudosections is hampered by the fact that they display only few large fields of high thermodynamic variance in the pt range of interest here it is discussed how modal information on reaction progress within these fields can be used to determine pt path information for thermodynamically high variant metamorphic assemblages we use this information on reaction progress to contour pseudosections for modal proportions of minerals using the software package thermocalc the approach is applied to di tri and quadrivariant assemblages from the koralm complex in the eastern alps a pt path for these rocks is derived from modal considerations and compared with interpretations of mineral composition contours on the same pseudosection and with conventional thermobarometry it is shown that at least part of the complex must have cooled initially near isobarically from prevalent peak conditions around 700 c and 14 kbar before the rocks commenced a barroviantype decompression path

simple shear deformation and quartz crystallographic fabrics a possible natural example from the torridon area of nw scotland ln this paper the microstructures and crystallographic fabrics of a 30 cm wide deformed quartz vein from the torridon area of nw scotland are described the vein which lies along a joint separating two blocks of proterozoic gneiss was deformed by crystal plastic processes when the rigid joint blocks moved in opposite directions parallel to the vein margins mylonitic foliation within this quartzose ductile shear zone locally displays the classic orientation variation expected for heterogeneous simple shear deformation in thin section the vein is a mylonite composed of dynamically recrystallized elongate quartz grains aligned oblique to the mylonitic foliation fabrics within the central part of the vein have been examined by optical and x ray texture goniometry methods together with orientation distribution function odf analysis the a axis fabric consists of a dominant single point maximum orientated within the xz plane at 9 to the lineation x this point maximum occupies a pole position to the corresponding single girdle c axis fabric for individual positions on the c axis fabric skeleton the orientations of potential crystallographic slip systems slip plane and direction relative to shear zone co ordinates have been calculated by odf analysis the calculation of relative resolved shear stresses schmidfactors for the potential slip systems assuming a simple shear kinematic framework reveals an elegantly simple relationship between individual grain c axis orientation and correspond ing orientations of potential slip systems these results are readily interpreted in terms of bulk simple shear deformation

heterogeneous sub simple deformation in the gol e gohar shear zone zagros sw iran insights from microstructural and crystal fabric analyses petrofabrics and microstructural characteristics of the quartz rich mylonites were investigated in the nw se trending gol e gohar shear zone with length of ca 25 km within the zagros transpression zone sw iran the semi quantitative vorticity analysis using quartz c axis fabric rxz method and rigid porphyroclast geometry rigid grain net method reveals that mean kinematic vorticity number wm increases towards the baghat thrust fault displaying the occurrence of spatial and temporal variations of flow during progressive deformation the wm values show pure shear dominated flow progressively was changed to a simple shear dominated flow toward to the late stages of ductile deformation implying that the accelerating flow path was accompanied with progressive cooling and strain localization at the lower parts of the zone the measured vertical thinning dip parallel elongation suggests that thrust emplacement and metamorphic rock extrusion likely occurred by a combination of simple shear with a pure shear component of deformation i e general shear the estimated deformation temperatures based on the quartz c axis fabric patterns and their opening angles highlight greenschist to amphibolite facies conditions

variation in grain size and morphology of an inland parabolic dune during the incipient phase of stabilization in the hobq desert china abstract a significant increase in rainfall in the summer of 2012 on the southern fringe of the hobq desert inner mongolia resulted in the vegetation and thus stability of dunes in this area our research focuses on a typical parabolic dune which was active in 2011 and became stabilized after vegetation colonization topographic surveys and surface sediment analysis of the morphology and surface sands of the parabolic dune indicate that decreasing mean grain size and sorting values better sorting slightly more positive skewness and increasing kurtosis occurred over the dune surface during the incipient phase of stabilization there was a strong relationship between grain size sorting and dune mobility surface sand from the stabilized dune was generally finer and better sorted than at the same location when the dune was active during 2011 2012 the dune head had moved eastwards by approximately 2 3 m while its two arms expanded outward by approximately 3 2 m the height of the dune decreased and the dune became larger with a decreasing volume once anchored 2013 2014 the overall morphology and the grain size and sorting characteristics of the dune became more constant and quite different than when the dune was active

microscopic anatomy of a hot on cold shear zone insights from quartzites of the main central thrust in the alaknanda region garhwal himalaya

palaeoclimate interpretations of late pleistocene vegetated linear dune mobilization episodes evidence from the northwestern negev dunefield israel abstract the vegetated linear dune vld field of the northwestern nw negev desert situated at the downwind eastern end of the northern sinai nw negev erg constitutes an ideal setting for dating and interpreting its late quaternary dune encroachment episodes this study builds upon the results of roskin et al age origin and climatic controls on vegetated linear dunes in the northwestern negev desert israel quaternary science reviews 30 2011 1649 1674 that presented the stratigraphy of 35 sections and 97 optically stimulated luminescence osl ages from the nw negev dunefield here we refine our analysis of the negev late pleistocene dune mobilizations and stabilizations and interpret their palaeoclimatic controls in light of regional and global sediment records and proxies while initial dune encroachment into and stabilization in the nw negev took place during the last glacial maximum lgm at 23 18 ka spatial and statistical analyses of the osl dataset suggest that since the lgm negev dune activity was concentrated in two significant mobilization stabilization episodes a main episode at 16 13 7 ka and a minor one at 12 4 11 6 ka when the dunes reached their maximum spatial extent and stabilized these episodes include rapid dune encroachment and accretion events and coincide with the heinrich 1 and younger dryas cold events respectively the late pleistocene sand transporting winds were characterized by a westerly direction that resulted in west east vld elongation dune mobilizations may have occurred in response to wintertime east mediterranean cyclonic systems that brought storms of rainfall and strong winds the rapid dune mobilization events and their concurrence with the heinrich 1 and younger dryas cold events suggest a more global control despite the rainfall the elongating vlds were probably sparsely vegetated because of the high wind power their stabilization resulted from a decrease in storminess with the onset of a more arid holocene climate other global low latitude dune mobilizations and stabilizations are concentrated at the end of the late pleistocene leading us to suggest that these were also controlled mainly by global cold events and subsequent changes in windiness the recurring discontinuous aeolian sedimentation pattern found in osl dated vlds provides new and important chronological and sedimentological insight into prominent dune mobilization and stabilization processes the suggested link between global drops in cold event windiness and low latitude dune stabilization episodes emphasizes the prevalence of winds over aridity regarding major dune mobilizations for low latitude dunes even if vegetated

reconstructing palaeoenvironments on desert margins new perspectives from eurasian loess and australian dry lake shorelines abstract desert margins preserve evidence of more extensive arid conditions in the past and represent global hot spots with respect to climate change the balance of scientific evidence now suggests that dryland landscape reactivation did not correspond simply to ice age aridity peaks as previously assumed this paper provides a new perspective on and more nuanced understanding of desert marginal landscapes as palaeoenvironmental archives the two case studies represent ends of a sediment availability spectrum both environments experience substantial spatial and temporal variability in deposition with implications for reconstructing past environments at individual sites recently generated chronostratigraphic data from the dry subhumid dobrogea loess romania are synthesised to provide quantitative insights into the spatial and temporal organisation of loess plateaux loess accumulation peaks during the lgm and mis4 but not at all sites accumulation rates vary substantially between sites comparison of geographical context yields no clear driving mechanism for this variability secondly two transverse lunette dunes in semi arid willandra lakes australia yield comparable chronostratigraphies and distribution of stratigraphic units a first attempt is made to identify changes in wind regime through time on the australian desert margins and suggests that high latitude climate forcing may have acted upon semi arid australia over millennial scales the novel perspectives generated from the new datasets provide unprecedented insights into past climate circulation and land surface processes along desert margins these new perspectives coupled with the new geochronological and quantitative palaeoclimate proxy tools now available represent the next frontier for palaeoenvironmental research on desert margins

metamorphosed and dismembered ophiolite suites in the basement units of the eastern alps abstract the pre alpine basement of the eastern alps contains several ultramafic mafic rock complexes four of which have been investigated although polyphase deformation and metamorphism obscures much of the primary features field petrographical and geochemical evidence favours ophiolitic origins in mid ocean ridge and back arc tectonic settings the stubach complex belongs to the penninic basement of the tauern window and is interpreted as an obducted back arc ophiolite with ultramafic cumulates gabbro and minor amounts of basalt which shows the geochemistry of subduction related magma generation the rating complex belongs to a group of strongly dismembered basement slices carrying the palaeozoic austroalpine sequence of the northern greywacke zone basaltic rocks are accompanied by former metamorphic peridotite containing chromite concentrations nearly all members of an ophiolite suite are present in the speik complex in the austro alpine crystalline basement the source rocks are metamorphic peridotite harzburgite with chromite occurrences cumulate ultramafic and mafic rocks isotropic gabbro basalt and or dolerite and oceanic sediments the plankogel complex also part of the austro alpine crystalline basement represents a tectonic melange blocks of serpentinite and amphibolite derived from metamorphic peridotites and mid ocean ridge basalts together with marble and quartzite are contained in a micaschist matrix admixed is a rock assemblage with alkali basaltic amphibolites interpreted as a seamount environment the ritting plankogel and possibly parts of the speik complexes contain relict high pressure minerals and therefore went through a stage of subduction the inferred ages of all complexes is late precambrian to early palaeozoic the ophiolite suites have their distinct characteristics and contrasting tectonic settings and are therefore considered to be genetically unrelated to each other

age origin and climatic controls on vegetated linear dunes in the northwestern negev desert israel abstract the stabilized northwestern nw negev vegetated linear dunes vld of israel extend over 1300 km 2 and form the eastern end of the northern sinai nw negev erg this study aimed at identifying primary and subsequent dune incursions and episodes of dune elongation by investigating dune geomorphology stratigraphy and optically stimulated luminescence osl dating thirty five dune and interdune exposed and drilled section were studied and sampled for sedimentological analyses and osl dating enabling spatial and temporal elucidation of the nw negev dunefield evolution in a global perspective the nw negev dunefield is relatively young though sporadic sand deposition has occurred during the past 100 ka dunes began to accumulate over large portions of the dunefield area only at 23 ka three main chronostratigraphic units corresponding to three osl age clusters were found throughout most of the dunefield indicating three main dune mobilizations late to post last glacial maximum lgm at 18 11 5 ka late holocene 2 0 8 ka and modern 150 8 years the post lgm phase is the most extensive and it defined the current dunefield boundaries it involved several episodes of dune incursions and damming of drainage systems dune advancement often occurred in rapid pulses and the orientation of vld long axes indicates similar long term wind directions the late holocene episode included partial incursion of new sand reworking of late pleistocene dunes as well as limited redeposition the modern sand movement only reactivated older dunes and did not lengthen vlds this aeolian record fits well with other regional aeolian sections we suggest that sand supply and storage in sinai was initiated by the late pleistocene exposure of the nile delta sands late pleistocene winds substantially stronger than those usually prevailing since the onset of the holocene are suggested to have transported the dune sands across sinai and into the northwestern negev our results demonstrate the sensitivity of vegetated linear dunes located along the northern fringe of the sub tropical desert belt to climate change i e wind and sediment supply

holocene and recent aeolian reactivation of the willandra lakes lunettes semi arid southeastern australia the willandra lakes in semi arid southeastern australia provide some of the most continuous combined palaeoenvironmental and archaeological records on the continent these are best preserved within

last glacial maximum dune activity in the kalahari desert of southern africa observations and simulations abstract it has long been understood that as ephemeral landscape features sand dunes are highly sensitive to environmental change and thus their distribution and the timing of their development may provide clues to past climate dynamics the relationship between climate and dune activity however is neither simple nor straightforward with a range of controls affecting the balance between erodibility the availability of sediment for deflation and erosivity the potential for sediment transport to explore such complex systems over large spatial and temporal scales a number of dune activity indices dai have been created that incorporate wind speed and moisture balances to calculate the potential for and degree of dune mobilisation using modern weather station data these indices have generally been shown to provide reasonable indications of dune activity potential until recently however the detailed quantitative data required to inform these equations has not been available for past climate scenarios and attempts to determine the relative importance of the various controls of dune activity have relied on rough estimations of climatic parameters this paper combines data from monthly general circulation model gcm outputs from the coupled ocean atmosphere gcms for 21 ka with the most detailed dai equation presently available to calculate the potential for dune reactivation in southern africa during the last glacial maximum lgm 18 24 ka based on these data and calculations it is indicated that there was significantly less potential for dune activity across southern africa at 21 ka when compared to the aeolian sediment records from the region this study poses serious and fundamental questions about 1 the reliability of the model outputs 2 the degree to which dais are able to account for the complexity and dynamics of aeolian systems and or 3 the interpretation of dune records as palaeoclimatic proxies at millennial time scales

garnet sm nd data from the saualpe and the koralpe eastern alps austria chronological and p t constraints on the thermal and tectonic history abstract garnets from recrystallized staurolite and kyanite bearing mica schists from the central saualpe base ment representing the host rocks of the type locality eclogites give concordant sm nd garnet whole rockisochronagesbetween88 5 1 7and90 9 0 7ma themillimetre sized mostly inclusion freegrainsshowfairlyhomogeneouselement pro les withpyropecontentsof25 27 narrowrims withanincreasein fe and mn and a decrease in mg document minor local re equilibration during cooling accordingto phengite geothermobarometry peak metamorphic conditions at 90 ma were close to 20kbar and680 c and similar to those recorded by the eclogites the garnet rims record about 575 c 7kbar forthe nal stages of metamorphism a phengitic garnet mica schist sampled at the immediate contact withthe gertrusk eclogite gave a garnet whole rock sm nd age of 94 0 2 7 ma garnet porphyroclasts separated from a pegmatite mylonite of the koralpe plattengneiss near stainzare unzoned and show spessartine contents of 15 composition and sm nd ages of close to 260 mapoint to a magmatic origin for these garnets the garnet data from the saualpe document an intense alpine metamorphism for this part of theaustroalpine basement the mica schists recrystallized during decompression and rapid exhumation atthe nal stages of and immediately following a high p event the koralpe data show that high alpinetemperatures did not reopen the sm nd isotope system implying a closure temperature in excess of c 600 c for this isotopic system in garnet key words alpine orogenesis closure temperature eastern alps high p metamorphism metamorphicand magmatic garnets p t t paths saualpe koralpe basement sm nd geochronology

tectonometamorphic evolution of the koralm complex eastern alps constraints from microstructures and textures of the plattengneis shear zone abstract lattice preferred orientations lpo of quartz have been investigated along a south north oriented section across the plattengneis of the koralm complex eastern alps the plattengneis forms an important shear zone within the austroalpine nappe complex of the eastern alps which has developed during the cretaceous evolution of the alpine orogen the quartz c axes form small circle distributions in the southernmost parts of the koralm complex which represent the uppermost structural level of the plattengneis further to the north two maxima between the y and z directions of the finite strain can be interpreted in terms of preferred slip on the rhomb planes these fabrics continuously grade into type i and type ii crossed girdle distributions in a northward direction a strong maximum near the y axis with the tendency to be distributed along a single girdle with three corresponding maxima of a axes near the margin of the pole figure can be observed in the central and northern parts such lpo are characteristic for both high grade metamorphic conditions and high finite strain the microstructures display that the deformation within the plattengneis shear zone was synmetamorphic a continuous increase of peak temperatures and pressure from approximately 550 c to approximately 750 c from the south to the central parts can be inferred from geothermometric calculations the temperatures then decrease to approximately 650 c from the central parts to the north the related pressures increase from 8 to 16 kbar and then decrease to 10 kbar the lpo changes that have been observed in the study area are best interpreted in terms of temperature dependence of the activation of glide systems within quartz aggregates the temperature and pressure evolution may indicate that the central parts of the koralm complex have been exhumed by larger amounts than the northern and southern parts this is also documented by the lpo evolution therefore we assume that the plattengneis shear zone formed during the exhumation of the koralm complex and is related to the exhumation of high pressure units in the footwall of this shear zone accordingly the kinematics of the plattengneis shear zone is rather extensional than thrust related the implications for the structural evolution of the eastern alps are shortly discussed

heterogeneous deformation and quartz crystallographic fabric transitions natural examples from the moine thrust zone at the stack of glencoul northern assynt quartz crystallographic fabric transitions in well exposed mylonites immediately beneath the moine thrust at the stack of glencoul nw scotland have been investigated by optical microscopy x ray texture goniometry and orientation distribution function analysis a progressive change is observed from asymmetrical kinked single girdle c axis fabrics at 0 5 cm beneath the moine thrust through asymmetrical type i cross girdle fabrics to symmetrical type i cross girdle fabrics at 30 cm beneath the thrust this c axis fabric transition is accompanied by a transition from asymmetrical single a axis maximum fabrics 0 5 cm beneath the thrust through asymmetrical two maxima fabrics to essentially symmetrical two maxima a axis fabrics odf analysis of these s l and l s tectonites indicates that c axis positions on the leading edge of the fabric skeleton are related by a common a direction oriented within the xz plane at a moderate angle to the lineation x in contrast c axis positions on the peripheral trailing edge are related by a positive r rhomb pole oriented close to z a directions lying within this common rhomb plane progressively change through 180 in orientation traced around the c axis fabric skeleton such contrasting single crystal rhomb a preferred orientations on the leading and trailing edges of the fabric skeleton are interpreted as indicating localized grain scale plane strain and flattening deformation respectively they result in tectonites with essentially symmetrical c and a axis fabrics which display strongly asymmetrical positive r and negative z rhomb pole figures the observed transition in quartz c and a axis fabrics is interpreted as indicating an increasing importance of non coaxial plane strain deformation as the moine thrust is approached even immediately 1 cm beneath the thrust however flow has still significantly departed from bulk simple shear and involved an important heterogeneous component of contemporaneous flattening deformation

kinematics of austro alpine cover nappes changing translation path due to transpression upper and middle austro alpine nappes of the eastern alps the structural uppermost subunits of the alps suffered two major superposed deformations d1 d2 during the eo alpine cretaceous orogeny d1 is characterized by nw to w directed thrusting and nappe internal rock flow d2 by large scale folding and imbrication toward the north and northeast structures strain metamorphic history microfabrics and stretching trajectories indicate that the superposition of d2 over d1 structures can be interpreted as a progressive deformation it is concluded that the emplacement of the nappes follows a curved translation path a model which emphasizes non coaxial deformation structures explains the detachment of the nappes the configuration of the separating thrust planes and the distribution of intense deformation zones the overall kinematic history of the austro alpine nappes fits a model in which strike slip shearing horizontal shortening and vertical lengthening act together continuously over a finite deformation zone transpressional model this model emphasizing a gradually changing strain regime eliminates the space problems encountered in models which consider simple south over north imbrication during the alpine orogeny the study stresses two interpretations 1 1 stretching lineations indicate nappe transport directions 2 2 transpression may be a common feature of orogenic belts

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

plastic anisotropy and fabric evolution in sheared and recrystallized quartz single crystals 1 the effect of a lattice preferred orientation on the flow strength of quartz aggregates dynamically recrystallized from single crystals of synthetic quartz was investigated using general shear experiments in a griggs apparatus experiments were conducted at shear strains up to 5 at a temperature of 900 c confining pressure of 1 5 gpa and shear strain rate of 10 5 s 1 three starting orientations of crystal were used to activate three slip systems basal a prism c and prism a although slip induced rotation of the crystal axes in the first two orientations led to the activation of additional slip systems for crystals with higher water contents basal a and prism a orientations are relatively weak and prism c orientations are stronger all three initial crystal orientations undergo dynamic recrystallization with increasing shear strain although the strain required for 100 recrystallization varies 2 for prism c slip 3 8 for basal a slip and 5 for prism a slip for all three starting orientations distinct domains of recrystallized grains develop with c axes parallel to y of the strain ellipsoid ymax replacing recrystallized grains of other orientations the ymax domains increase in size with increasing strain in addition strain markers show that strain is highly localized within the ymax domains indicating geometrical softening of up to an order of magnitude in effective viscosity

lateral migration thermoluminescence chronology and colour variation of longitudinal dunes near birdsville in the simpson desert central australia the longitudinal dunes of the simpson desert in the vicinity of birdsville have been reworked largely during the holocene from dunes deposited up to 80000 years ago or earlier the widespread asymmetry of these roughly northward trending dunes with steeper eastern faces and more gentle western faces supports wind rose data showing sand transporting winds from the southwest obliquely intersecting the dunes while this suggests a change in the wind pattern since the dune field was oriented it does not indicate that the dunes are necessarily shifting leeward eastward as a consequence it is hypothesized that the direction of migration is controlled by the extent to which the dunes are vegetated relatively well vegetated dunes can accrete sand on their gentle stoss slopes and erode on their lee slopes causing them to shift westward and hence obliquely into the wind a condition that probably prevails in wetter regions and during episodes of relatively humid climate in contrast in very dry areas or during arid phases sand can move unimpeded up a sparsely vegetated stoss face and over the crest to form an avalanche or slip face on the lee side thereby causing the dunes to shift eastward despite evidence that longitudinal dune crests can shift laterally to some extent the dunes in the western part of the simpson desert have not migrated either westward or eastward more than 100m or so from their pleistocene cores aeolian transport and partial or complete removal of iron cutans from around quartz grains results in dunes of widely varying colour yet of similar age

dune mobility in the st anthony dune field idaho usa effects of meteorological variables and lag time abstract the st anthony dune field sadf is a 300 km2 expanse of active to stabilized transverse barchan barchanoid and parabolic sand dunes located in a semi arid climate in southeastern idaho the northeastern portion of the sadf 16 km2 was investigated to examine meteorological influences on dune mobility understanding meteorological predictors of sand dune migration for the sadf informs landscape evolution and impacts assessment of eolian activity on sensitive agricultural lands in the western united states with implications for semi arid environments globally archival aerial photos from 1954 to 2011 were used to calculate dune migration rates which were subsequently compared to regional meteorological data including temperature precipitation and wind speed observational analyses based on aerial photo imagery and meteorological data indicate that dune migration is influenced by weather for up to 5 10 years and therefore decadal weather patterns should be taken into account when using dune migration rates as proxies from climate fluctuation statistical examination of meteorological variables in this study indicates that 24 of the variation of sand dune migration rates is attributed to temperature precipitation and wind speed which is increased to 45 when incorporating lag time

late cretaceous exhumation of the metamorphic gleinalm dome eastern alps kinematics cooling history and sedimentary response in a sinistral wrench corridor abstract the metamorphic gleinalm dome eastern alps was uplifted and exhumed within a releasing structure in a sinistral wrench corridor during the late cretaceous the dome is confined by a system of ductile shear zones including low angle normal faults and steep sinistral tear faults which define a large releasing structure with the metamorphic dome in its center the fabrics developed within all ductile shear zones record processes which were operating during decreasing temperatures from initial epidote amphibolite upper greenschist facies conditions with crystal plastic fabrics in quartz to temperatures below ca 300 c with predominantly cataclastic fabrics a cooling path based on 40ar 39ar amphibole 95 4 1 2 ma and muscovite ages 87 6 0 6 84 3 0 7 ma together with sphene zircon and apatite fission track data indicate cooling through ca 500 c at ca 94 ma to below ca 250 200 c at 65 ma subsidence of the adjacent late cretaceous kainach gosau basin occurred synchronously with cooling and uplift of the gleinalm dome internal depositional patterns record rapid subsidence at the time of cooling with internal synsedimentary block rotation above an intra crustal ductile normal fault the sinistral wrench corridor of the eastern alps developed by sinistral displacement of the austroalpine units against a relatively stable europe during the late cretaceous

sticky dunes in a wet desert formation stabilisation and modification of the australian desert dunefields independent dating evidence and dune morphology indicate great stability of the australian dunefields most dunefields have seen only minor superficial modification since they were formed up to 1 million years ago despite quite large changes in climate conditions this stability may be partly due to the relatively dense vegetation cover on australian dunes under the marginally arid climate but new studies supported by many older observations suggest that sticky dunes where sand grains are bonded or cemented may form under a broader range of wind climates than widely thought and have greater resistance to reworking new mapping of the australian continental dunefields from satellite imagery shows a previously unrecognised diversity of dune morphologies dune orientation continuity connectedness crest planform crest sharpness spacing and setting all show patterns of variation over the continent these are consistent with the overall low sand supply and variable wind climate that contribute to the dominance of longitudinal dunes but also with only superficial modification of the dunes after their initial formation the longevity of the dunes is likely also partly due to the stabilisation of dune sand by pedogenesis the bonding of sand by pedogenic calcium carbonate gypsum silica and translocated clays the extremely low mobility of the sand dunes has led to preservation of dunes of great age with stacked accretionary units and multiple palaeosols

a fully predictive model for aeolian sand transport abstract this paper presents the development calibration and verification of a fully predictive model for wind blown dry sand the model is based on the modification of the well known bagnold equation by including the threshold shear velocity which is also slightly modified to ensure a smoother transition from the non transport regime to the transport regime the sand transport rate is related to the static and dynamic grain roughness by using a semi empirical roughness predictor which is calibrated based on sand transport data from wind tunnel experiments with a flat mobile sand surface the model input for dry sand is the wind velocity at one height above the surface and the sand characteristics d50 d90 the effects of moisture vegetation and shells on the sand transport process are included by fairly simple expressions which are acting on the shear velocity the threshold value and the transport rate in all 105 high quality data sets have been used for verification of the proposed predictive model about 72 of the predicted values are within a factor of 2 of measured values of the transport rate

kinematics of cretaceous nappe tectonics in the austroalpine basement of the koralpe region eastern austria krohe a 1987 kinematics of cretaceous nappe tectonics in the austroalpine basement of the koralpe region eastern austria tectonophysicz 136 171 196 the austroalpine basement of the koralpe area austria was affected by penetrative ductile deformation in the cretaceous three metamorphic events have been established ht lp metamorphism of unknown age a hercynian mt mp metamorphism and a cretaceous eo alpine mt mp metamorphism in the koralpe area cretaceous rb sr cooling ages of muscovite indicate temperatures of at least 500 o c during the eo alpine event the most intense deformation occurred along intracrustal shear zones plattengneis north to northeast directed thrusting is indicated by an inverted metamorphic gradient regional transposition of an older foliation s c fabrics and oblique quartz fabrics after development of high temperature mylonites low angle normal shear zones low temperature mylonites cut the uppermost parts of the austroalpine basement and indicate an extensional tectonic setting at about 85 to 90 ma s c and quartz fabrics indicate downdip movements of the hanging wall towards the northeast intracrystalline a slip in quartz caused strong preferred lattice orientation in high and low temperature mylonites during the e alpine deformation the basal a slip system is more pronounced at lower temperatures whereas a prism a system predominates at higher temperatures the overall kinematic history of the austroalpine nappe complex in the study area suggests a model in which an intracrustal south over north imbrication took place in an early stage of eo alpine collision these movements were outlasted by sinistral strike slip movement possibly due to oblique collision along irregular margins of the austroalpine and brianpnnais complexes the collision imbrication process resulted in crustal thickening isostatic uplift and thus extension of the higher parts of the crust low angle normal faulting initiated sedimentation in the intramontane c tic gosau basins of late cretaceous age

particle size fractionation of eolian sand along the sinai negev erg of egypt and israel eolian sand fractions along the west east transport system of the northern sinai peninsula northwestern negev erg of egypt and israel were analyzed in this study with regard to source dune geomorphology eolian transport and paleoclimate the studied erg is composed of active linear seif dunes in northern sinai western part and stabilized vegetated linear dunes in the nw negev dune field eastern part linear seif dunes differ from vegetated linear dunes in their vegetation cover linearity internal structure and dynamics sand samples were analyzed for sand grain morphology and particle size distribution although both dune types are continuous landforms with similar orientations and sand grain roundness values the linear dunes of sinai are coarser grained than the negev vegetated linear dunes the vegetated linear dunes have a variable but higher proportion of very fine sand 50 125 m content and a varying but lower sand fining ratio defined as the ratio of fine sand percentage to very fine sand percentage from these observations we infer that fractionation of sand occurred along the studied eolian transport path during periods of enhanced windiness very fine sands are suggested to have been transported by saltation and low suspension from source deposits and sand sheets we suggest that a significant proportion of the very fine sand fraction of nile delta sands has been transported downwind through northern sinai during the late pleistocene especially when linear dunes reached the nw negev due to last glacial period windiness and probably larger sediment supply generally decreasing wind velocities and increasing precipitation along the west east dune transport path enhanced vegetative cover in the northern negev and enabled deposition of the very fine sand component within the dunes and probably further downwind our results suggest that particle size distribution can elucidate much about erg history over time scales of a glacial interglacial cycle especially in cases where the sand provenance is of a single dominant source

the onset of dune formation in the strzelecki desert south australia abstract this study is concerned with the late quaternary climatic chronology of the strzelecki desert dunefields in central australia the sand ridges comprise layers of quartz sand some of which include palaeosol horizons with carbonated rootlets providing excellent opportunity for dating of alternations of dune building and stability by using optically stimulated luminescence osl deduced from the osl age of the oldest aeolian layer dated we conclude that the onset of aridity dates back to at least 65 ka older phases of aeolian activity though following a fluvial depositional phase 160 ka ago cannot be excluded although no aeolian layers giving evidence for this have been found in the two dunes dated here unconsolidated dune sands in the upper part of one section with late holocene 4 ka to modern depositional ages indicate a reactivation of the dunefield in recent times from the crosscheck of 14 c ages of the carbonated rootlets with osl results it is concluded that under the given environmental conditions radiocarbon dating of the calcareous rootlets is not able to provide reliable ages for the phase of soil development

the australian desert dunefields formation and evolution in an old flat dry continent a new map the first based on interpretation of satellite imagery reveals both the complexityofaustralia sdunefieldsandtheirrelationshipswithtopography climateandsubstrate of the five main sand seas the mallee strzelecki and simpson in eastern australia cover quaternary sedimentary basins whereas the great victoria and great sandy dunefields in the west are formed by reworking of valley and piedmont sediments in a non basinal landscape of low relief ridge and valley topography these dunefields cover large areas of the arid zone and semi arid zone and small areas of dunes in sub humid areas around the margins of the continent reflecting past expansion of arid climates during glacial stages of the last several glacial cycles several areas of low relief stand out as being largely dune free the limestone nullarbor plain clay plains of the georgina basin and floodplains of rivers in the carpentaria lake eyre and murray darling drainage basins where sand is rare or not transported by diminished late quaternary rivers the yilgarn block of southwestern australia is also surprisingly free of dunes possibly as a result of long deep weathering everywhere the history of climate change is evident in dune morphology and distribution including large areas where the sand dune orientations are markedly divergent from modern sand moving wind directions

11 11 dune morphology and dynamics this chapter discusses the key types of sand dunes and how they can be classified and assesses the major controls on their development the processes of dune dynamics are reviewed leading to a discussion of the concept of equilibrium in solitary dune form recent advances in modeling are reviewed that show how interactions between dunes may result in equilibrium at the dune field scale rather than at the single dune scale

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

seasonal variation of crescentic dune morphology and morphometry strzelecki simpson desert australia the general absence of contemporary dune building in the australian arid zone finds the occurrence of crescentic dune genesis and evolution at gurra gurra waterhole a somewhat enigmatic event amongst prevalent inactive linear dunescapes crescentic dune construction is geographically restricted to areas of dominant unidirectional high windiness and minimal vegetation parameters that are generally uncommon in arid australia today the influence of seasonal multidirectional winds can see dune form undergo continual transition between quasi equilibrium and disequilibrium such dynamic antithesis is depicted in seasonal mathematical comparisons of the planimetric attributes length and width dimensional equilibrium is a transient feature at gurra gurra waterhole and not characteristic of this dunescape copyright 2001 john wiley sons ltd

transpressional collision structures in the upper crust the fold thrust belt of the northern calcareous alps abstract two major structural events characterize the tectonic evolution of the northern calcareous alps nca 1 late early cretaceous to late eocene nw directed dextral transpressional stacking of nappes as an expression of the formation of the austroalpine orogenic wedge and 2 miocene sinistral wrenching due to eastward lateral extrusion of crustal wedges along the central eastern alps three first order detachment horizons are defined by differences of competence within areas of facies transition preexisting normal faults control the thrust architecture transpressional contraction in the nca is indicated by a nw directed thrusting oblique to both the long axis of the nca and the edge of the orogenic foreland b the occurrence of en echelon arrays of thrusts and folds laterally displaced by dextral strike slip faults the thrusts and strike slip faults are kinematically connected to each other and dissect the nca into rhomboidal blocks c ne directed extension parallel to fold and ramp axes and the internal strike of the nca and d clockwise rotation 30 of the entire nca around a vertical axis kinematic and dynamic analysis of mesoscale fault striae data related to transpressional stacking indicates a nw trend of contraction directions and in general a ne trend of the extension directions parallel to fold axes and branch lines of thrusts before rotation the average contraction direction was probably parallel to the generally w directed shear direction recorded in the crystal plastically deformed central part of the eastern alps three balanced cross sections across the nca yield a minimum of 54 65 total shortening

morphological variability in the linear dunefields of the strzelecki and tirari deserts australia linear dunefields dominate the arid centre of the australian continent the morphological variability of linear dunes in the strzelecki and tirari deserts of australia was assessed using a dune classification scheme based on quantifiable variables of substrate spacing and junction frequency the use of high spatial resolution aster satellite imagery enabled detailed analysis including spectral characterisation of substrate at both local and regional scales the classification of the linear dunes revealed close relationships between substrate type and dune spacing reflecting local sediment availability increasing dunefield organisation downwind is reflected in reduced numbers of dune junctions and may suggest the attainment of dynamic morphological and sedimentological equilibrium both downwind evolution and sediment nourishment from local sources play a role in linear dune formation maps illustrating the spatial distribution of planimetric variables provide a useful tool for investigating linear dune behaviour although additional variables such as height and dunefield age add to the complexity of dune formation and must also be considered

linear dune accumulation chronologies from the southwest kalahari namibia challenges of reconstructing late quaternary palaeoenvironments from aeolian landforms abstract the linear dunes of the southern kalahari dunefield constitute one of the major palaeoenvironmental proxies in the region the application of optically stimulated luminescence osl dating since the1990s and advancements in the depth of sampling using augering equipment over the past few years have permitted the reconstruction of linear dune accumulation chronostratigraphies for entire dune profiles from base to crest these methods are applied to four dunes in the mariental stampriet region of the southern kalahari dunefield sampled at predominantly 0 5 m intervals individual dunes record multiple phases of dune construction but with only a few phases recorded consistently between two or more of the dunes results from the 48 osl ages produced here extend the aeolian accumulation record for the southern kalahari dunefield through the last three glacial interglacial cycles with two ages from the early part of mis6 a synthesis of all existing luminescence ages for the southern kalahari reveals that the dunefield has been partially active throughout much of the past 120 ka there are no clear clusters of ages within osl age errors this is in contrast to previous syntheses of ages for this region in addition these new data from mariental stampriet dunes show that clusters in grouped dune osl ages can be spuriously produced as a function of reducing the sampling frequency with depth within the dunes from 0 5 to 1 mintervals this has significant implications for previous conclusions regarding discrete phases of aeolian accumulation based on sampling at 1 m intervals and less vertically intensive sampling techniques the total luminescence data set of 136 ages for the southern kalahari implies that this dunefield has been close to the threshold of reactivation throughout much of the late quaternary

shear stress partitioning in sparsely vegetated desert canopies shear velocity ratios were derived for six neighbouring localities representing rangeland abandoned farmland and a playa in the semi arid region of the sonoran desert near surface and above canopy wind speeds mostly below saltation threshold were used to evaluate the partitioning of shear velocities and shear stresses between the plant canopy and the surface the technique utilized represents an alternative to the threshold shear velocity ratio rt approach of musick and gillette land degradation and rehabilitation 1990 2 87 94 and results demonstrate the need for partitioning over a range of wind speeds shear velocity ratios were variable over the playa and abandoned farmland while variance in near surface wind speeds was highest over shrub dominated sites the relationship between lateral cover lc and shear velocity r is comparable to previous findings utilizing rt although methodological differences result in mean shear velocity ratios less than shear velocity ratios derived for threshold conditions with respect to the model of raupach et al journal of geophysical research 1993 98 d2 3023 3029 this may be attributed to the difference between measured shear stresses and the average shear stress on the exposed surface at high lateral covers shear velocity ratios are lower than threshold shear velocity ratios due to increased wake interactions or decreased drag on the shrub elements at higher wind speeds

thermometrically inferred cooling rates from the plattengneis koralm region eastern alps abstract closure of fe mg exchange between garnet and biotite is used to estimate cooling rates from the koralm region of the austro alpine nappe complex east of the tauern window in the eastern alps maximum cooling rates for a 700 m thick mylonitic shear zone the plattengneis are at least an order of magnitude higher than those of surrounding country rocks the cooling rate history inferred for the plattengneis suggests exponentially decreasing cooling rates whilst the cooling history of the surrounding country rocks is inferred to involve an approximately constant cooling rate the fast cooling rates in the shear zone are interpreted as evidence for an additional energy input from an internal heat source which may have been heat that was released during deformation related to the alpine nappe stacking processes

grain boundary dissolution porosity in quartzofeldspathic ultramylonites implications for permeability enhancement and weakening of mid crustal shear zones abstract quartzofeldspathic ultramylonites from the alpine fault zone one of the world s major active plate boundary scale fault zones have quartz crystallographic preferred orientations cpo and abundant low angle 10 misorientation are decorated by faceted pores commonly with uniformly oriented pyramidal shapes only grain boundaries with 10 misorientation angles in polymineralic aggregates are decorated by pores mean grain boundary pore densities are 5 108 cm 2 grain boundary pores are dissolution pits generated during syn deformational transient grain boundary permeability nucleating on dislocation traces at dilatant grain boundary interfaces they have not been removed by subsequent grain boundary closure or annealing pore decoration could have led to grain boundary pinning triggering a switch in the dominant deformation mechanism to grain boundary sliding which is supported by evidence of cpo destruction in matrix quartz pore decorated grain boundaries have significantly reduced surface area available for adhesion and cohesion which would reduce the tensile and shear strength of grain boundaries and hence the bulk rock grain boundary decoration also significantly decreased the mean distance between pores potentially facilitating dynamic permeability consequently these microstructures provide a new explanation for strain weakening and evidence of fluid flow along grain boundaries in mylonites at mid crustal conditions

airflow and roughness characteristics over partially vegetated linear dunes in the southwest kalahari desert there is little understanding of the flow field surrounding semi vegetated linear dunes and predictions of dune mobility are hampered by a lack of empirical data concerning windflow in an attempt to characterize the near surface airflow upwind of and over partially vegetated linear dunes in the southwest kalahari desert this study presents measurements of vertical and horizontal wind velocity profiles across cross sectional transects of seven partially vegetated linear dunes vegetation surveys combined with velocity measurements from vertical arrays of cup anemometers placed up to 2 3 m above the ground surface were used to gain information concerning the modification of airflow structure caused by the intrusion of the dunes into the atmospheric boundary layer and to predict the variability of aerodynamic roughness z0 from interdune to crest the results suggest an acceleration of flow up the windward slopes of the dunes and as such the data correspond to classical theory concerning flow over low hills essentially jackson and hunt 1975 principles where the theory is incapable of explaining the airflow structure and acceleration characteristics this is explained in part by the presence of a spatially variable vegetation cover over the dunes the vegetation is important both in terms of the varying aerodynamic roughness z0 and problems concerning the definition of a zero plane displacement d it is considered that any attempts to characterize surface shear stress over the kalahari linear dunes in order to predict sand transport and dune mobility will be hampered by two problems these are the progressively non log linear nature of the velocity profiles over the dunes caused by flow acceleration and the production of thin near surface boundary layers caused by areally variable aerodynamic roughness as a result of the partially vegetated nature of the dunes

the spodumene deposit at weinebene koralpe austria the weinebene spodumene deposit is located in carinthia about 270 km southwest of vienna it is hosted by the medium to high grade metamorphic rocks of the koralpe the spodumene bearing pegmatites form unzoned dikelike bodies in eclogitic amphibolites and kyanite bearing micaschists with concordant foliations their lateorogenic emplacement is probably of variscan age a younger probably alpine metamorphic event affected the pegmatites it caused extensive recrystallization of the micaschist hosted pegmatites but had only a minor impact on the amphibolite hosted ones the spodumene bearing pegmatites have been traced over a length of 1 5 km along strike and to about 450 m down dip their average thickness is 2 m with a maximum of 5 5 m emplacement of the pegmatites caused an alteration halo of several dm in the hosting amphibolites characterized by biotitization and formation of holmquistite an aplitic spodumene free seam of about 10 cm symmetrically borders the pegmatites no contact phenomena are observed along the micaschist hosted dikes spodumene is the only lithium bearing mineral its average content is 22 vol equivalent to 1 68 wt li2o in the amphibolite hosted pegmatites and 15 vol equivalent to 1 13 wt li2o in the micaschist hosted dikes such a significant difference is also shown by rubidium 1 100 ppm vs 880 ppm and cesium 60 ppm vs 25 ppm beryllium and tin are the only other significant trace elements they show average contents of about 100 ppm and 120 ppm respectively with maxima of 1 690 ppm beryllium and 1 500 ppm tin no correlation is found between lithium tin and beryllium niobium and tantalum are very low a na k ratio of 1 2 emphasizes the predominance of albite over microcline there is no discernable correlation between spodumene and albite contents or between lithium and any other alkalies the average k rb ratio is 20 pointing to the high degree of fractionation spodumene contains 7 4 li2o and 0 45 feo there is no difference in the spodumene chemistry between the amphibolite hosted and the micaschist hosted pegmatites strong structural and textural evidence mineral zoning bulk composition corresponding to thermal minima in relevant experimental systems and trace element signature support an igneous derivation of the pegmatites however no granitic intrusion is exposed in the area and the pegmatites could have been displaced from their source by tectonic events

regional scale chemical transport modeling in support of the analysis of observations obtained during the trace p experiment 1 data obtained during the trace p experiment is used to evaluate how well the cfors stem 2k1 regional scale chemical transport model is able to represent the aircraft observations thirty one calculated trace gas and aerosol parameters are presented and compared to the in situ data the regional model is shown to accurately predict many of the important features observed the mean values of all the model parameters in the lowest 1 km are predicted within 30 of the observed values the correlation coefficients r for the meteorological parameters are found to be higher than those for the trace species for example for temperature r 0 98 among the trace species ethane propane and ozone show the highest values 0 8 r 0 9 followed by co so2 and noy no and no2 had the lowest values r 0 4 analyses of pollutant transport into the yellow sea by frontal events are presented and illustrate the complex nature of outflow biomass burning from se asia is transported in the warm conveyor belt at altitudes above 2 km and at latitudes below 30n outflow of pollution emitted along the east coast of china in the postfrontal regions is typically confined to the lower 2 km and results in high concentrations with plume like features in the yellow sea during these situations the model underpredicts co and black carbon among other species an analysis of ozone production in this region is also presented in and around the highly industrialized regions of east asia where fossil fuel usage dominates ozone is nmhc limited south of 30 35n ozone production is nox limited reflecting the high nmhc nox ratios due to the large contributions to the emissions from biomass burning biogenics sources and biofuel usage in central china and se asia

late quaternary palaeoenvironmental change in the australian drylands in this paper we synthesise existing palaeoenvironmental data from the arid and semi arid interior of the australian continent for the period 40 0 ka moisture is the predominant variable controlli

paleomagnetic chronology and paleoenvironmental records from drill cores from the hetao basin and their implications for the formation of the hobq desert and the yellow river abstract reconstructing the cenozoic environmental history of hetao basin in the northern part of the ordos plateau in north china is important not only for revealing the evolution of the yellow river but also for understanding the formation of the hobq desert here we present the stratigraphic framework of drill core dr01 with length of 2503 18 m and the results of magnetostratigraphic and esr dating and multi proxy analyses of drill core wedp05 with length of 274 60 m from the hetao basin the magnetostratigraphic and esr results indicate that core wedp05 spans the last 1 68 ma stratigraphic sequence of core dr01 indicates that the hetao area was uplifted and eroded during the early cenozoic before subsiding to form a sedimentary basin subsequently the basin was a fluvio lacustrine environment during the pliocene and then experienced alternating desert and fluvio lacustrine conditions during the quaternary sedimentary facies and multi environmental proxy analyses of core wedp05 indicate that the basin was occupied by a fluvio lacustrine system during the following intervals 1 47 1 30 ma 1 17 1 07 ma 0 68 0 60 ma and from 0 47 ma to the last interglacial and that a desert environment developed during the lake regression phases of 1 30 1 17 ma 1 07 0 68 ma and 0 60 0 47 ma the presence of aeolian sand at the base of core wedp05 suggests that the origin of the hobq desert can be traced back to the early pleistocene and resulted from the erosion and transportation of exposed fluvio lacustrine sediments by near surface winds associated with the asian winter monsoon a large river channel in the hetao basin may have existed as early as the pliocene which was occupied by the yellow river when its upper reaches formed by at least 1 6 ma subsequently at least since 1 2 ma the yellow river formed its drainage system around the hetao basin and controlled the paleoenvironment evolution of the basin

heat sources of cretaceous metamorphism in the eastern alps a discussion abstract the alpine orogenic cycle is characterised by a series of early metamorphic events that occurred in the cretaceous the eoalpine events a collection of data on peak metamorphic conditions pt paths and on relationships between structure and metamorphism for these events in the eastern alps shows that 1 eoalpine metamorphism occurred largely simultaneously with pervasive deformation 2 the eoalpine thermal peak was reached near the pressure peak 3 lower grade structurally higher rocks reached their metamorphic peak earlier than higher grade structurally lower rocks and there is a wide spread of metamorphic ages 4 low grade metamorphic conditions are probably more perturbed than high grade conditions and 5 there is a conspicuous regional distribution of metamorphic grade with amphibolite and eclogite facies metamorphism occurring predominantly in two regions located symmetrically west and east of the tauern window possible heating mechanisms are discussed that can satisfy these observations and a review of previous thermal models is provided it is shown that models which rely on conductive heat transfer cannot account for all of these observations in order to assess other heat sources the effects of shear heating are evaluated here with simple model calculations and a straightforward comparison of length and time scales of dissipative heat production the results suggest that shear heat episodically released during the stacking of the austroalpine nappe pile may be a significant contributor to the observed thermal perturbation

characterisation of aeolian sediments from the strzelecki and tirari deserts australia implications for reconstructing palaeoenvironmental conditions abstract in arid environments dominated by desert dunes aeolian sediments represent a major source of potential palaeoenvironmental information however the extent to which dune sedimentology can be used for past environmental reconstruction is unclear this paper assesses the value of dune sediments as palaeoenvironmental indicators by investigating the sedimentological characteristics of linear dunes in the strzelecki and tirari deserts of central australia we use thin section microscopy particle size analysis and x ray diffractometry xrd mineralogy to characterise the sediments occurring within the dunefields of the region and examine the stratigraphic record in the context of dune preservation and sediment reworking we find that it is rarely possible to reconstruct past environmental change within desert dunefields purely on the basis of sedimentological evidence however limited palaeoenvironmental information is preserved within dune sediments which can be combined with additional arid zone proxies and geochronological techniques to enable the most reliable reconstruction of past conditions paleosols provide the most informative and unambiguous palaeoenvironmental indicators within dune sediments acting as markers of relative environmental stability paleosols are characterised by pedogenic carbonates and gypsum and illuviated clays in the form of intact grain coatings the potential for incomplete stratigraphic preservation within dunes is a critical consideration for reconstructing palaeoenvironments however the preservation of paleosols indicates that the dunes in this region have not been completely reworked grain coatings provide important evidence both for pedogenesis when they are intact and for aeolian reworking when they are partially abraded abraded cutans are ubiquitous across the region studied linear dune mineralogy of the strzelecki and tirari deserts is dominated by quartz with minor feldspar and clay minerals the latter in the form of grain coatings and aggregates the occurrence of intact sand sized aggregates composed of clay and silt particles at several sites indicates incipient rather than peak aridity and may within this geomorphic context indicate reduced stream discharges grain size shows a regional bias although silt sized material is most likely to have been deposited as long travelled dust the regional grain size characteristics combined with local occurrences of rock fragments and high feldspar content suggest that sediments are mostly derived from local sources

preliminary investigation results on fabrics and related physical properties of an anisotropic gneiss abstract in order to evaluate the fabric dependent anisotropy of a particular gneiss type we assessed the quartz lattice and shape preferred orientations as well as the microcrack pattern statistics in the rock mechanics laboratory several strength and deformability tests on drilled rock samples were run and the seismic wave propagation properties along the rock s principal strain axes were determined in the mechanical tests it turned out that despite a distinct stretching lineation with initially extreme grain elongation the rock performs for the larger part as a transversely isotropic material with the schistosity as plane of isotropy the anisotropy in seismic wave propagation within the plane of schistosity is attributed primarily to a highly anisotropic microcrack pattern the distinct gneissose banding and to a lower degree to the lpo of quartz

how do longitudinal dunes respond to climate forcing insights from 25 years of luminescence dating of the australian desert dunefields abstract this paper presents a meta analysis of 689 luminescence age estimates of australian desert sand dunes this analysis had two aims to examine the hypothesis that quaternary climate changes have forced dune accumulation and to understand longitudinal dune behaviour from the age architecture of sand dunes for which stratigraphic information is often absent or poorly known a novel approach to the analysis of probability density curves of dune age frequency shows that in the mallee dunefield of southeastern australia only the period leading up to and including the last glacial maximum lgm 18 34 ka experienced marked dune growth which cannot be explained by random stochastic activity during the lgm most but not all mallee longitudinal dunes were accumulating more rapidly than before and after in the strzelecki dunefield source bordering sbd longitudinal dune tl n 61 and osl n 40 ages are more frequent at the pleistocene holocene transition but nearby non sbd longitudinal dunes n 21 ages were only active above background levels during the lgm however the strzelecki dune age data set suffers from being drawn from a small number of individual dunes 10 sbd dated using tl 12 sbd dated by osl 7 non sbd dated by osl with a marked bias away from surficial young and basal old depths even during the lgm many dunes do not record active growth and the dunefield was most likely a mosaic of stable dune surfaces and bare mobile patches supported by the scant pollen data from the arid zone hyper aridity has not been experienced in these dunefields these vegetated dunes exhibit conservative behaviour with limited response to the range of climate forcing experienced in the late pleistocene a more complete understanding of dunefield response to quaternary climates would require an intensive and structured dating program to overcome the noise from stochastic processes leading to small scale activity in these dunes and the simultaneous removal of parts of the sedimentary record

modelling palaeosol preservation in aeolian dunes in some of the world s desert and desert marginal areas e g simpson strzelecki australia dunefields preserve well developed palaeosols whereas in other regions with broadly similar climatic regimes and topography e g southwest kalahari the dunes are characterized by very poorly developed internal stratigraphy it has been postulated that dunes such as those in the kalahari may never have had conditions conducive to soil formation or that soils once formed but any evidence of palaeosols has been lost due to reworking this study develops and applies a one dimensional numerical model to simulate dune development soil formation and soil preservation variables in the model allowed experimentation on the influence of sediment supply the time taken for soil to form and the additional resistance to erosion offered by the soil reduced sediment supply plays a vital role in landscape development during periods of initial pedogenesis although re exhumed palaeosols influence sediment supply the effect is minimal although under almost all parameterized conditions more than half and up to 80 90 of those soils initially formed are lost due to reworking evidence of their past formation remains in the large majority of profiles and the dominant factor in controlling the preservation of palaeosols is the frequency of their formation the implication is that where dunes are found without palaeosols the most likely albeit not certain inference is that they have never formed counter intuitively the limited sediment supply means their additional resistance to erosion becomes almost inconsequential to their preservation at least until the unit approaches complete invulnerability short chronostratigraphic hiatuses around palaeosols are normal and although long gaps can occur they are extremely infrequent where such gaps are observed in field studies external forcing factors e g climatic or environmental changes are implied as they are highly unlikely to result from stochastic net preservation copyright 2014 john wiley sons ltd

understanding linear dune chronologies insights from a simple accumulation model abstract dunefields are today often found in regions where environmental conditions are no longer conducive to widespread aeolian transport and deposition and are thus seen as potential archives of palaeoenvironmental information some dune types are more suitable for this purpose than others and linear dunes used here synonymously with longitudinal dunes have been most frequently employed they are commonly found in dryland and dryland marginal regions and they are apparently less migratory than some other dune forms thereby offering the potential for longer environmental histories most recent studies have employed optical osl dating surveys which directly date the emplacement of dune sands to attempt to produce a representative history of aeolian accumulation at a dunefield scale yet such studies have not always given due consideration to the geomorphology of linear dune accumulation although linear dunes do not rework their sand as readily as say barchans dunes it is clear that sand deposited during an aeolian event is likely to have been removed from elsewhere on the dunefield s surface for this reason all dune archives must be assumed to be discontinuous over long timescales the effect of sediment redistribution on dune preservation and thus palaeoenvironmental interpretation is difficult to observe and poorly understood we present a simplified probabilistic model to replicate deposition erosion of sand at a linear dune crest thus simulating the type of profile sampled in many field studies in order to produce a local accumulation history the modelled sand flux incorporates various feedbacks and the simulations are run with varying boundary conditions in which the simulated surface is assumed to be in equilibrium over the multi millennial timescales of the model s duration periodic instabilities in the landscape are generally well recorded by the modelled dune accumulation history particularly when the events involve the system as a whole briefly functioning out of an equilibrium state i e the probabilities of deposition and reworking are not equal however under forcing conditions where the probabilities are unchanged throughout the duration of the model run the results can show apparent structure within the data when sample sizes are low although at large sample sizes the preservation potential decays with burial age according to a power law the model confirms the importance of rigorous sampling strategies for such studies but also suggests that if such precautions are taken the reworking inherent to linear dune aeolian systems does not preclude their use as a quaternary palaeoenvironmental archive of environmental change

the giant shakhdara migmatitic gneiss dome pamir india asia collision zone 1 geometry and kinematics 1 cenozoic gneiss domes comprise one third of the surface exposure of the pamir and provide a window into the deep crustal processes of the india asia collision the largest of these are the doubly vergent composite shakhdara alichur domes of the southwestern pamir tajikistan and afghanistan they are separated by a low strain horst top to sse noncoaxial pervasive flow over the up to 4 km thick south pamir shear zone exhumed crust from 30 40 km depth in the 250 80 km shakhdara dome the top to nne alichur shear zone exposed upper crustal rocks in the 125 25 km alichur dome the gunt shear zone bounds the shakhdara dome in the north and records alternations of normal shear and dextral transpression it contributed little to bulk exhumation footwall exhumation along two low angle normal sense detachments resulted in up to 90 km syn orogenic n s extension extension in the southwestern pamir opposes shortening in a fold thrust belt north of the domes and in particular in the tajik depression where an evaporitic decollement facilitated upper crustal shortening gravitational collapse of the pamir plateau margin drove core complex formation in the southwestern pamir and shortening of the weak foreland adjacent to the plateau overall this geometry defines a vertical extrusion scenario comprising frontal and basal underthrusting and thickening and hanging gravitationally driven normal shear in contrast to the himalayan vertical extrusion scenario erosion in the pamir was minor preserving most of the extruded deep crust including the top of the south pamir shear zone at peak elevations throughout the dome

variable vegetation cover and episodic sand movement on longitudinal desert sand dunes abstract longitudinal linear sand dunes of the simpson and strzelecki dunefields in eastern central australia present a paradox low levels of activity today stand in contrast to luminescence dating which has repeatedly shown deep deposits of sand on dune crests dating to within the late holocene in order to investigate the nature of dune activity in the simpson strzelecki dunefield vegetation and sand mobility were investigated by detailed vegetation survey and measurement of rippled area and loose sand depth of dunes at three sites along a climatic gradient the response of both vegetation and sand movement to inter annual climate variability was examined by repeat surveys of two sites in drought and non drought conditions projected plant cover and plant crust cover were found to have inverse linear relationships with rippled area and the area of deep loose sand no relationship was found between these measures of sand movement and the plant frontal area index a negative exponential relationship between equivalent mobile sand depth on dune surfaces and both vascular plant cover and vascular crust cover was also found there is no simple threshold of vegetation cover below which sand transport begins dunes with low perennial plant cover may form small dunes with slip faces leading to a positive feedback inhibiting ephemeral plant growth in wet years and accelerating sand transport rates the linear dunefields are largely within the zone in which plant cover is sufficient to enforce low sand transport rates and in which there is a strong response of vegetation and sand transport to inter annual variation in rainfall both ephemeral plants mostly forbs and crust were found to respond rapidly to large 20 mm month rainfall events on millennial time scales the level of dune activity is controlled by vegetation cover and probably not by fluctuations of wind strength land use or extreme decadal time scale drought may destabilise dunes by removing perennial plant cover accelerating wind erosion

palaeoenvironmental reconstructions from linear dunefields recent progress current challenges and future directions abstract this paper reviews recent progress in the use of linear dunes as geoproxies of late quaternary environmental change summarises the challenges facing their use and explores some potential solutions to these challenges large areas of the swathes of linear dunes which occupy the continental interior of southern africa australia and parts of central asia and southern america currently have limited or negligible aeolian activity they have been recognised as offering potential information about past environments for more than a century but only with the widespread application of luminescence dating during the 1990s did they realistically start to offer the prospect of being an extensive dateable proxy of late quaternary palaeoenvironments and possibly palaeoclimates dating aeolian dune sands with luminescence methods is generally although not always relatively straightforward over the past twenty years a large number 1000 of luminescence ages have been added to the global dataset yet there has also been significant criticism of some of the rationale underpinning much of the interpretation of the records derived at the landscape scale developments of arguably equal importance have come from improved geomorphological understanding based on the wider availability of remotely sensed data and the paradigm of dunefield evolution as a self organising complex system current challenges are identified in three key regions incomplete understanding of how the process geomorphology of linear dunes affect the accumulation and preservation of sediment a lack of clarity regarding the temporal and spatial scale of the response in a dynamic environmental setting and uncertainty surrounding the drivers of changing rates of net accumulation solutions to these challenges lie within diverse research methodologies certainly further field study is required with improvement required in understanding system responses to changing environmental stimuli at scales from sedimentological to landscape in parallel the full implications of complex systems approaches to aeolian geomorphology for linear dunes lag behind the adoption of the concept to some other dune forms e g barchans the relationship between observed dune complexity and age from field data complicates previous suggestions that dune patterning may be purely a function of development time parallel to this lies the need to improve interpretation of the results of dune geochronological studies a suggestion is offered which aims to test the statistical significance of dune accumulation time series by comparison with a modelled system with unchanging external forcing despite the initial promise of linear dune records as a revolutionary source of palaeoenvironmental information in drylands the outcomes to date have been coarse although still valuable in resolution perhaps the most valuable realization has been that geomorphological understanding of these widespread landforms is incomplete

morphodynamics boundary conditions and pattern evolution within a vegetated linear dunefield abstract the controls on the evolution of linear dunefields are poorly understood despite the potential for reactivation of dunefields which are currently stabilized by vegetation under the influence of 21st century climate change the relative roles of local influences i e boundary conditions and morphodynamic influences i e emergent properties remain unclear chronostratigraphic and sedimentological analyses were conducted on two pairs of linear dunes exhibiting different spatial patterning in the strzelecki desert of central australia it was hypothesized that morphodynamic influences via pattern coarsening would mean that dunes from the simpler pattern defined in terms of the frequency of defects i e junctions and terminations would be more mature older landforms optically stimulated luminescence osl dating of full depth regularly sampled profiles was used to establish accumulation histories for the four dunes and supported by sedimentological analysis to investigate possible compositional differences and similarities between the dunes whilst three of the dunes the two more simply patterned dunes and one of the more complex dunes have accumulation histories beginning between 100 ka and 150 ka and document sporadic net accumulation throughout the last interglacial glacial cycle to the late holocene one of the dunes with relatively complex patterning reveals that the majority of the dune accumulation 7 m at that site occurred during a relatively short window at 50 ka there is no clear sedimentological reason for the different behaviour of the younger dune the data suggest that small scale and essentially stochastic nature of the aeolian depositional erosional system can overprint any large scale morphodynamic controls the concept of dating landscape change by pattern analysis is thus not supported by this study and would require very careful interpretation of the scales being considered this further suggests caution when interpreting dune chronostratigraphies palaeoenvironmentally as different dunes are able to respond very differently to the same external stimulus e g climate in the case studied here a mechanism is proposed to account for the rapid accumulation of the anomalous dune by avulsion of the local aeolian accumulation from one dune ridge to another

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

dune mobility and vegetation cover in the southwest kalahari desert as part of a wider project investigating the palaeoenvironmental significance of partially vegetated linear dunes in the southwest kalahari data collected in the latter part of 1992 concerning dune movement and vegetation cover suggest that sediment transport is occurring on some dune surfaces and that the majority of surface activity occurs on the crests and upper slopes of the dunes the data suggest that the limiting variables on surface sediment movement vary on different parts of a dune on interdunes and lower dune slopes the primary limiting variable is available wind energy while on dune crests and upper slopes it is vegetation cover ground cover by litter has much greater importance in protecting the surface sediment from erosion than rooted vegetation from individual data points no evidence is found to support a threshold vegetation cover below which sediment movement occurs rather a gradient of activity is suggested whereby a reduction in vegetation cover increases the potential for sediment movement and surface change however dunes with differing amounts of mean vegetation cover display differing degrees of surface activity and at this scale a vegetation cover threshold in the region of 14 per cent may be recognized

eo alpine eclogitisation of permian morb type gabbros in the koralpe eastern alps austria new geochronological geochemical and petrological data new petrological geochemical and isotopic data sm nd rb sr from meta gabbros eclogites and metapelites from the southern koralpe are presented pl cpx gabbros mostly olivine free that have preserved their magmatic minerals to varying extent occur as relics within eclogites transformation of gabbro into eclogite is documented in different stages ranging from macro to microscale based on textural characteristics the eclogites are classified into four groups types 1 4 typical eclogite parageneses are grt omp zo ky qtz amp phe rut the metapelitic eclogite host rocks are composed of qtz ms bt pl grt ky p t estimates for both metabasites and metapelites range at 1 8 2 0 gpa 600 650 c sm nd mineral isochrons pl cpx for the gabbroic eclogite precursors give ages of between 247 16 and 255 9 ma their initial nd and sr isotopic compositions are clearly within the range of modern depleted mantle values minerals from type 1 metagabbroic eclogites are in clear nd isotopic disequilibrium pervasively recrystallized type 3 eclogites yield grt wr or grt omp zo amp wr ages of 97 5 101 7 and 109 8 ma the metapelitic eclogite host rocks mica schists yield nd dm depleted mantle model ages of 1 44 1 63 ga grt wr isochron ages from these rocks are 86 1 87 4 and 89 3 ma the new data further support the permian early mesozoic rifting event for this part of the austroalpine basement which is related to initial oceanization at the western end of the alpine tethys during alpine plate convergence pre alpine continental basement and oceanic crustal fragments where subducted to depths of c 60 km the most likely time span for the high pressure peak is c 100 10 ma rapid exhumation in the upper cretaceous is inferred from mineral cooling ages between 80 and 60 ma