an analytical model of the growth of a frontal discontinuity an analytic semi geostrophic model of frontogcnesis is described which exhibits the growth of a frontal discontinuity surface the initial distribution of temperature on a plane horizontal boundary consists of a warm two dimensional strip embedded in an isothermal background the potential vorticity in the atmosphere above is uniform and positive a barotropic deformation field with axis of dilation along the warm strip forces a discontinuity in the velocity field as the warm air is occluded and becomes detached from the lower boundary the solution demonstrates some important general properties of the inviscid semi geostrophic equations when discontinuities are present in particular the vertical velocity on the lower boundary becomes non zero at the front the maximum value of the vertical velocity occurs here when the front first forms but then lifts off the boundary the front itself constitutes a line of infinite potential vorticity so that the global integral of mass weighted potential vorticity is conserved only if the boundary of the domain is redefined to exclude the front the implications of these properties for numerical modelling are discussed for typical atmospheric rates of deformation forcing the accelerations of air parcels extremely close to the front are large enough to violate the conditions of validity of semi geostrophic theory the conditions of hydrostatic balance are for all practical purposes never violated

spoil pile instabilities with reference to a strip coal mine in turkey mechanisms and assessment of deformations with the increasing adoption of the surface mining of coal problems associated with spoil pile instability which affects resource recovery mining cost and safety and presents environmental hazards have become a matter of prime concern to mine planners and operators the study of geotechnical aspects is thus very important in the rational planning for the disposal reclamation treatment and utilization of spoil material a strip coal mine one of the largest open pit mines in turkey is located in central anatolia and provides coal to a thermal power station coal production is carried out in two adjacent open pits the central pit and south pit a large scale spoil pile instability over an area of 0 3 km2 occurred within the dumping area of the central pit in addition small scale movement occurred in the outside dumping area this paper outlines the results of field and laboratory investigations to describe the mechanisms of the spoil pile instabilities and to assess deformations monitored over a long period following the failure shear test results indicate that the interface between the floor and spoil material dumped by dragline has a negligible cohesion and is the most critical plane of weakness for spoil pile instability back analyses based on the method of limit equilibrium and the numerical modelling technique and observations in the pit revealed that failure occurred along a combined sliding surface consisting of a circular surface through the spoil material itself and a planar surface passing along the interface between the spoil piles and floor the analyses also indicated that pore water pressure ratios of about 0 25 satisfy limiting equilibrium condition and that rainfall about one month before the failure may be a contributing factor to the instability movement monitoring data obtained following the failure over a 1 5 year period suggested that the ongoing deformations were mainly due to compaction of the spoil material based on the monitoring data and the results of the analyses the failure mode of the local instability occurring at the outside dumping area was considerably similar to that of the large instability

experimental tests for the assessment of the shear strength of marble waste dumps the large dumps of waste material called ravaneti from marble quarrying activities in alpi apuane basin are distinguished features of the local landscape they are strongly heterogeneous never compacted and frequently subject to local instabilities the access roads to the marble quarries cross the dumps therefore it is concern of the local authorities to hinder such phenomena in this respect it is of paramount importance to evaluate the shear strength of the material comprising the dumps at the proper scale in this note the results of in situ direct shear and tilt tests on samples of metric size are illustrated together with the interpretation according to a strength criterion relative to rockfills the results of a series of lab tests on the finer fraction of the waste material are also described and interpreted finally qualitative considerations on the local and global stability of the waste dumps related to their shear strength are reported

facetted garnets formed by etching examples from sandstones of late triassic age south germany detrital garnets from the upper triassic keuper of southern germany have well developed facets where they occur in calcite cemented sandstone the grains belong to the pyralspite series and have a homogeneous chemical composition without any zonation is revealed by microprobe analyses it is concluded that the large facets are caused by etching during diagenesis and not by authigenic overgrowth high calcium contents of the pore fluids may have been important in the formation of these garnet facets

quantitative provenance analysis of sediments review and outlook provenance analysis of sediments is aimed at reconstructing the parent rock assemblages of sediments and the climaticphysiographic conditions under which sediments formed inferring sediment provenance from the final product a basin fill is anything but straightforward because the detrital spectrum evolves as the sediment is transported along the pathway from source to basin successful provenance analysis requires that the nature and extent of compositional and textural modifications to the detrital spectrum be recognised if not quantified the history of quantification in sediment provenance studies is summarised and illustrated by tracking two fundamental ideas the concept of the sediment petrological province or petrofacies and the relation between sandstone composition and plate tectonic environment progress in sedimentary provenance analysis has been closely linked with advancements in measurement technology a brief survey of modern data acquisition tools illustrates the possibilities and limitations of modern provenance research an operational definition of quantitative provenance analysis qpa is presented in which the central role of mass balance is acknowledged extension of this definition to include quantitative predictions obtained by forward modelling computer simulation of sediment production as well as methodological improvements in data acquisition and processing is needed to cover likely future developments in qpa the contributions to the special issue quantitative provenance analysis of sediments illustrate the intrinsic multidisciplinarity and rapid expansion of qpa d 2004 elsevier b v all rights reserved

the pliocene and quaternary fluvial archives of the rhine system abstract the river rhine is one of the few major fluvial systems that connect the areas of the alpine glaciers and scandinavian ice sheet and so provides a key for correlating the two glacial areas in northern and middle europe the fluvial sequences of the rhine valley include at least 11 pleistocene terraces in the lower rhine area 2 pliocene and 12 pleistocene terraces in the middle rhine area resulting in 15 different pliocene and pleistocene terraces based on the correlation between lower and middle rhine the formation of fluvial terraces is significantly influenced by climatic and tectonic processes the terrace staircases are a result of uplift in the middle rhine area and the southern part of the lower rhine area whereas subsidence in the northern part of the lower rhine area resulted in buried stacked sequences magnetostratigraphic data provide chronological constraints for the terrace deposits in the lower rhine embayment and middle rhine region the matuyama brunhes boundary is a reliable marker horizon for the upper terrace fluvial deposits exposed in the karlich clay pit in the middle rhine area the first appearance of volcanic heavy mineral grains in the terrace sediments in loess and soils can be correlated from the middle rhine area through the lower rhine embayment to the netherlands the first occurrence of nordic components in terrace sediments of the lower rhine area is known from gravel on top of the kempen krefeld beds and so are younger than the holsteinian but older than the penultimate glaciation in the lower middle rhine area 40ar 39ar dating of tephra layers intercalated in the aeolian and fluvial sediments provide age constraints the upper pleistocene aeolian sediments overlying the terrace deposits have been dated by luminescence methods and the tephra from the laacher see eruption 12 860 bp is present in the younger lower terrace deposits

a method for quantifying the impacts and interactions of potential vorticity anomalies in extratropical cyclones the theory of potential vorticity pv allows us to describe the life cycle of mid latitude baroclinic systems in terms of the individual impacts and interactions of distinct pv anomalies embedded in the background flow pv anomalies associated with the undulating tropopause the low level thermal field and key diabatic processes such as the latent heat release within the cloudy systems of the cyclone are often considered as evolving features regulated by their lateral and vertical mutual interactions and their interaction with the stratospheric high latitude pv reservoir under some balance flow assumptions pv inversion can be used to quantify the contribution of the pv anomalies to the cyclone depth or other attributes at various stages of its life cycle a static approach but it is less clear how to diagnose with similar quantitative detail the various types of time dependent interactions among the anomalies and mean flow that govern the processes of cyclogenesis and cyclolysis a dynamic approach this paper presents a method that implements the concepts of pv thinking quantitatively the method first applies a piecewise pv inversion scheme formulated according to the charney nonlinear mass wind balance approximation then it combines a prognostic system of balance equations that are consistent with the applied inversion scheme with a factor separation technique by switching on and off the pv anomalies of interest various flow configurations are generated and the corresponding solutions to the prognostic equations can be algebraically combined to isolate the magnitude of both the individual and the synergistic effects of the pv anomalies on the spatial pattern of geopotential height tendency and vertical motion around the cyclone with low computational cost the potential of the method to elucidate the relative importance of physically meaningful pv anomalies for the growth or decay of baroclinic systems is illustrated for the intense mediterranean cyclone of 10 12 november 2001 using the ncep meteorological grid analyses at 12 h intervals the upper level pv anomalies contributed very significantly during the whole life cycle of this mediterranean cyclone surface thermal anomalies were fundamental during the development period and induced the general northeastward movement of the system during the later stages during the mature stage of the cyclone the interaction between the two types of anomalies became the dominant effect all other contributions including the individual and synergistic effects of diabatically generated pv were generally most relevant during this mature stage copyright 2008 royal meteorological society

engineering geological characterization of coal mine waste material and an evaluation in the context of back analysis of spoil pile instabilities in a strip mine sw turkey abstract coal mine waste material which usually consists of a mixture of coarse grained particles to rock fragments grading to fine grained particles causes geotechnical and environmental problems on disposal a study of the geotechnical aspects of the problem is therefore important in rational planning for the disposal reclamation treatment and use of such material spoil pile instability has been a continuing problem in the eskihisar strip coal mine of southwestern turkey particularly shallow seated circular failures appearing along the haul road and instabilities covering large agricultural areas outside the dumping yard increase the importance of spoil pile stability the fact that the height of spoil piles dumped by trucks on both sides of the haul road will increase much more in the future has focused the attention of the miners to this problem this study outlines the geotechnical characteristics of waste material from the tertiary coal bearing rocks derived from field and laboratory investigations and describes the causes and mechanism of spoil instabilities which threaten the safety of the haul road and the agricultural areas in the vicinity of the pit gradation results suggest that fines and coarser material were approximately equally represented in the spoil the percentage of fines is indicative of material degradation as evidenced by slaking tests site observations and numerous back analysis of investigated failures reveal that the failures do not penetrate the foundation material and only occur along circular surfaces through the spoil material it is also noted that surface water infiltration reducing the effective shear strength of the spoil material contributes to failures shear test results indicate that the spoil is a nearly cohesionless material with a residual internal friction angle of about 33 which confirms the values derived from standard penetration tests it is also noted from back analyses that the spoil material exhibits a shear strength at or approaching the residual value at the time of failure the use of shear strength parameters defined by the linear mohr coulomb envelope yields results that are comparable with those obtained when the non linear failure envelope is used provided that such strength parameters were defined at the operating normal stress levels on the failure surfaces

feedback between erosion and active deformation geomorphic constraints from the frontal jura fold and thrust belt eastern france a regional tectono geomorphic analysis indicates a pliocene to recent rock uplift of the outermost segment of the jura fold and thrust belt which spatially coincides with the intra continental rhine bresse transfer zone elevated remnants of the partly eroded middle pliocene sundgau foret de chaux gravels identified by heavy mineral analyses allow for a paleo topographic reconstruction that yields minimum regional latest pliocene to recent rock uplift rates of 0 05 0 02 mm year this uplift also affected the pleistocene evolution of the ognon and doubs drainage basins and is interpreted as being tectonically controlled while the ognon river was deflected from the uplifted region the doubs deeply incised into it focused incision of the doubs possibly sustained ongoing deformation along anticlines which were initiated during the neogene evolution of the thin skinned jura fold and thrust belt at present this erosion related active deformation is taking place synchronously with thick skinned tectonics controlling the inversion of the rhine bresse transfer zone this suggests local decoupling between seismogenic basement faulting and erosion related deformation of the mesozoic cover sequences

effective parameters for the particle breakage of calcareous sands an experimental study abstract calcareous sediments have different behavior under monotonic and cyclic loadings compared to that of terrigenous soils particle breakage is considered the most important feature of calcareous soils and has been used in many experimental investigations recently this phenomenon affects some characteristics of carbonate sediments such as compressibility shearing strength and permeability in this study experiments were conducted to evaluate the parameters that affect the particle breakage of calcareous sands including confining pressure relative density axial strain drainage conditions and grain size distribution the input energy per unit volume of the soil was also calculated to analyze the effect of this parameter on the particle breakage in the testing program two calcareous sands from different locations in the persian gulf namely bushehr port bp and hormuz island hi sands were used for the triaxial compression tests the experimental results showed that the input energy played an important role in the particle breakage behavior of used soils in comparison to other parameters considered in this study axial strain as a representation of the effect of deviatoric loading had major influences on the amount of crushing the results also indicated that hi sand particles yielded at a higher stress than bp sand

the dynamical consequences for tropopause folding of pv anomalies induced by surface frontal collapse it has been noted previously that during frontal collapse dynamical processes lead to the formation of potential vorticity pv anomalies in the vicinity of the surface front these processes can either be associated with diffusion in the presence of the tight temperature gradients or with intrusion into the atmosphere of the vanishingly thin layer adjacent to the surface this paper explores the dynamical consequences of these pv anomalies on the parent baroclinic wave cyclone the method used is to find the vertical motion attributable to these anomalies the location and magnitude of this vertical motion is clearly key to the dynamical influence of the anomalies as we are dealing with a three dimensional evolving cyclone with an emergent tropopause fold the calculation of vertical motion needs to be capable of accounting for the role of the highly deformed tropopause hence we develop and use a nonlinear balance model approach the result shows that the pv anomalies near the surface front induce downward vertical motion at the tropopause fold and thus they act to amplify this feature this role of diffusion associated with surface frontal collapse is the key finding of this paper an analysis is made of the role of upper and lower level pv anomalies on the overall rate of the wave development

eocene pliocene time scale and stratigraphy of the upper rhine graben urg and the swiss molasse basin smb we present a general stratigraphic synthesis for the upper rhine graben urg and the swiss molasse basin smb from eocene to pliocene times the stratigraphic data were compiled both from literature and from research carried out by the authors during the past 6 years an index of the stratigraphically most important localitites is provided we distinguish 14 geographical areas from the helvetic domain in the south to the hanau basin in the north for each geographical area we give a synthesis of the biostratigraphy lithofacies and chronostratigraphic ranges the relationships between this stratigraphic record and the global sea level changes are generally disturbed by the geodynamic e g subsidence evolution of the basins however global sea level changes probably affected the dynamic of transgression regression in the urg e g middle pechelbronn beds and serie grise corresponding with sea level rise between ru1 ru2 and ru2 ru3 sequences respectively as well as in the molasse basin regression of the umm corresponding with the sea level drop at the ch1 sequence the urgent project upper rhine graben evolution and neotectonics provided an unique opportunity to carry out and present this synthesis discussions with scientists addressing sedimentology tectonics geophysics and geochemistry permitted the comparison of the sedimentary history and stratigraphy of the basin with processes controlling its geodynamic evolution data presented here back up the palaeogeographic reconstructions presented in a companion paper by the same authors see berger et al in int j earth sci 2005

the rand granite in the southern schwarzwald and its geodynamic significance in the variscan belt of sw germany the rand granite is a heterogeneous metamorphosed granitoid rock complex with numerous wallrock inclusions situated in the moldanubian zone at the southern margin of the central schwarzwald gneiss complex it is a largely mylonitized elongated body and is thrust over the badenweiler lenzkirch zone forming a nappe with shear zones along its northern and southern boundaries it comprises meta granites meta trondhjemites and biotite augen gneisses derived from monzogranites to granodiorites mineral behaviour indicates that the magmatic body has been deformed under upper greenschist facies conditions nappe thrusting which also affected the south schwarzwald gneiss complex occurred in visean time during high temperature low pressure metamorphism kinematic indicators in the mylonites document e to ese directed nappe transport highly transpressive relative to the trend of the nappe boundaries and the foliation the trondhjemites formed at 351 5 4 ma predating the variscan ht metamorphism they have initial end values of 6 6 to 6 7 and relatively low initial 87sr 86sr ratios 0 7042 to 0 7063 indicating a predominant mantle origin the granites and protoliths of the biotite augen gneisses probably crystallised between 436 and 377 ma suggested by u pb zircon model ages they are different from the trondhjemites with low initial end values 4 7 to 3 3 and higher initial 87sr 86sr ratios 0 7068 0 7077 indicating that large part of the rand granite originated from anatexis of continental crust internal structure of zircons from the rand granite reveals mixing of magmas derived from both mantle and crust sources these new data support an interpretation that the rand granite developed along an active continental margin and therefore represents a possible root of a variscan magmatic arc

a new approach to provenance studies electron microprobe analysis of detrital garnets from middle jurassic sandstones of the northern north sea reading provenance from heavy mineral suites is hampered by the depletion of diagnostic but unstable heavy minerals through intrastratal solution a common phenomenon in deep sedimentary basins such as the north sea this paper demonstrates the potential of electron microprobe analysis in overcoming this problem by concentrating on the compositional variations shown by detrital garnets which are relatively resistant to intrastratal solution studies of the garnets from the brent group middle jurassic of the murchison and tern oilfields in the northern north sea reveal that three distinct areas supplied detritus association 1 which characterizes the broom formation in both areas and recurs higher in the sequence in the tern field is ascribed to an orkney shetland source the location of the areas supplying the garnets of association 2 best represented in murchison and association 3 common to both fields is less clear their ultimate sources clearly include high grade metamorphics and therefore probably lie on the norwegian landmass the orkney shetland platform or conceivably the scottish landmass but the possibility of recycling makes it difficult to judge their immediate provenances nevertheless the presence of three garnet associations indicates that the most widely accepted model of brent sedimentation with sands derived from a domal uplift in the outer moray firth and channelled northward along the viking graben is untenable

exhumation of the central alps evidence from 40ar 39ar laserprobe dating of detrital white micas from the swiss molasse basin 40ar 39ar single grain laserprobe dating of detrital white micas from early oligocene to middle miocene 31 14 ma sedimentary rocks of the central swiss molasse basin reveals three distinct clusters of cooling ages for the hinterland two palaeozoic age clusters reflect cooling after the variscan orogeny with only limited reheating during the alpine orogeny the third tertiary age cluster reflecting late alpine cooling is restricted to sediments younger than 20 myr old micas with cooling ages 30 myr are interpreted to originate from the footwall of the simplon detachment fault thus representing formerly exposed upper levels of the present day lepontine metamorphic dome erosion of these levels is reflected by an increase of low grade metamorphic lithic grains in the sandstones this interpretation puts constraints on the timing of exhumation as well as on the evolution of the drainage pattern of the central alps

modelling the quasi equilibrium dynamics of the atmosphere the prime need in forecasting atmospheric motions is to predict the synoptic pattern accurately and to fill in as much mesoscale detail on it as possible the problem is difficult because the atmospheric fields contain almost discontinuous structures such as fronts and inversions and the large scale flow may separate around mountains this paper demonstrates that such phenomena may be described as quasi equilibrium structures where the fluid remains close to a minimum energy state this minimum is shown to correspond to geostrophic and hydrostatic balance and the implied quasi equilibrium evolution to correspond to the lagrangian form of the geostrophic momentum equations examples of flows that can be treated include boundary layers separating at surface fronts and mountain blocking with associated drag by including diabatic effects the inland penetration of sea breezes can also be studied the quasi equilibrium idea can be applied globally but describes only a limited subset of tropical motions primitive equation models attempt to produce these structures by relying on explicit geostrophic adjustment this paper presents evidence that this is not always adequate especially when the structures contain discontinuities implicit algorithms are described which may be more effective

geotechnical characterization of mining rock waste dumps in central evia greece open pit mining using drill and blast has been taking place in central evia greece for many decades this is so due to the presence of ferronickel ores in the area as a consequence of the mining activity large volumes of overburden upper cretaceous limestone are being annually extracted and deposited at predefined sites creating rock waste dumps or embankments in the context of optimum land surface use and better stability conditions a geotechnical characterization of these waste dumps has taken place and is presented in the current paper first image analyses are performed on fragmented limestone muckpiles and the degree and intensity of rock fragmentation due to blasting is assessed results compare reasonably well with computations based on the kuz ram empirical model for fragmentation analysis overall muckpiles on excavation faces consist of boulders and cobbles by 80 90 per weight following a laboratory investigation program is executed on samples retrieved from the waste dumps based on the results the dumps consist of heavily coarse grain material mostly classified as gc according to modified proctor tests and in situ density tests using the troxler device compaction on the crest of the dumps is characterized as very high while permeability is empirically considered as medium to high as far as the friction angle of the waste dump material is concerned this is estimated based on observations i e recorded inclinations of existing dumps combined with an empirical model from the literature generally it is considered that the friction angle varies considerably with the overburden pressure within the dump s body nonetheless if a single value approach is necessary for simplicity purposes and stability considerations then a friction angle of about 40 characteristic value is suggested as a reasonable assumption

data compilation from large drained compression triaxial tests on coarse crushable rockfill materials abstractinvestigating the mechanical properties of rockfills requires laborious time consuming and expensive large scale testing therefore practitioners frequently adopt design parameters based

solutions to a model of a front forced by deformation a semi geostrophic deformation model of a front studied by b j hoskins and f p bretherton is studied further it is shown that a unique solution of the lagrangian conservation laws governing the motion can still be constructed after the front has formed this solution shows that separate upper and lower fronts propagate into the fluid and are separated by a region where only smooth variations occur finite difference solutions of the primitive equations are also given which converge to a front with the correct mean slope and maximum long front velocity but without the correct variation in slope through the depth of the fluid

high resolution 40ar 39ar dating using a mechanical sample transfer system combined with a high temperature cell for step heating experiments and a multicollector argus noble gas mass spectrometer 40ar 39ar dating of young 5 10 16 mol 36ar is better than 0 5 1 0 1 n 4 8 we illustrate the system performance by 40ar 39ar dating of whole rock samples and mineral separates from the oman ophiolite as well as from the siebengebirge heldburg and rhon volcanic provinces in central germany

new geochemical results indicate a non alpine provenance for the alpine spectrum epidote garnet hornblende in quaternary upper rhine sediment abstract the heavy mineral assemblage of late pleistocene to modern rhine river sediment in the upper rhine graben is dominated by garnet green amphibole and epidote this so called alpine spectrum has been taken to indicate an exclusive derivation from the alps and has hitherto been investigated with optical methods only we present the first single grain geochemical data set of garnet and amphibole from the upper rhine river and some of its main tributaries we use the new data to test the alleged alpine provenance in the rhine our results show that the provenance of garnet mostly pyrope rich almandine is grain size dependent particularly the pyrope content indicates that the 0 063 0 25 mm size fraction has an alpine provenance whereas 0 25 0 5 mm grains derived from the black forest and the vosges which flank the upper rhine graben they mainly comprise of paleozoic metamorphic and igneous rocks supplying a suite of heavy minerals similar to the alpine spectrum to the rhine river amphibole mostly mg hornblende has an increasing tio2 content from the south to the north of the graben which also indicates an input from the graben shoulders the new data indicate that the so called alpine spectrum of heavy minerals in rhine river sediment of the upper rhine derived to significant degrees from non alpine sources furthermore our results indicate a relatively uniform provenance for the rhine river system during the past 1 ma

grain size dependence of garnet composition revealed by provenance signatures of modern stream sediments from the western hohe tauern austria abstract heavy minerals are valuable indicators about the geological framework in the source area the heavy mineral garnet is one of the most widespread heavy minerals in orogenic sediments and its geochemistry provides important information about metamorphic conditions the application of heavy minerals and garnet geochemistry for sedimentary provenance analysis is tested for modern stream sediments collected along three rivers draining the eclogite zone and adjacent geological source units of the western hohe tauern area in the central eastern european alps for comparison with the stream sediments rock outcrops exposed in this area were also sampled the chosen area is very well investigated and provides an excellent place to constrain the relations between source rocks and sediment in first order drainages the influence of grain size is studied in detail by considering grain size fractions ranging from coarse silt to coarse sand 32 to 1000 m in all grain size fractions the heavy mineral assemblages are characterised to a variable extent by epidote zoisite garnet and green calcic amphibole in the smaller grain size fraction apatite is more frequent whereas in the coarser grain size fractions an increase of green calcic amphibole and garnet can be observed electron microprobe analysis of detrital garnet shows the dominance of almandine rich garnet stream sediments within and downstream of the eclogite zone show an increase of pyrope rich garnets interestingly in all samples grossular rich garnets are more frequent in the smaller grain sizes and pyrope rich garnets are more frequent in the coarser grain sizes this is controlled by the original finer size distribution of grossular in the source rocks rather than being a hydraulic effect the heavy mineral assemblages and garnet geochemical data reflect the geological setting of the study area hence confirming the general strength of these methods in sedimentary provenance analysis however the data underline strong grain size control on sediment composition including single grain compositional variations

paleopositions of the western europe hercynides during the late carboniferous deduced from paleomagnetic data consequences for stable europe abstract paleomagnetic investigations have been carried out in different areas of the variscan belt armorican massif central massif ardenne vosges and the black forest in order to unravel the paleogeographic evolution of the hercynides during the carboniferous subsequent to important southerly or northerly drifts the central massif and vosges underwent a large rotation of a still undetermined direction in latest visean namurian times during the namurian westphalian the whole belt was oriented n s all investigated areas yield wsw ene directions for that period these directions question the validity of carboniferous mean poles available for stable europe a european plate rotated counterclockwise by about 40 relative to its permian position would be more consistent with these results during the latest westphalian stephanian period i e within the 310 290 ma timespan the western europe hercynides rotated clockwise by 40 50 perhaps together with the whole of europe late variscan strike slip faulting and overthrusting probably result from that rotation

hot contacts of garnet peridotites in middle upper crustal levels new constraints on the nature of the late variscan high t low p event in the moldanubian central vosges ne france p t paths based on parageneses in the immediate vicinity of former high temperature contact zones between mantle peridotites and granulitic country rocks of the central vosges ne france were derived by applying several conventional thermometers and thermobarometric calculations with an internally consistent dataset the results indicate that former garnet peridotites and garnet spinel peridotites were welded together with crustal rocks at depths corresponding to 1 1 2 gpa the temperature of the crustal rocks was about 650 700 c at this stage whereas values of 1100 c garnet peridotites and 800 900 c garnet spinel peridotites were calculated for the ultramafic rocks after emplacement of the mantle rocks exhumation of the lower crust took place to a depth corresponding to 0 2 0 3 gpa the temperatures of the incorporated peridotite slices were still high 900 1000 c at this stage this is indicated by the presence of high t low p parageneses c 800 c 0 2 0 3 gpa in a small 1 10 m contact aureole around a former garnet peridotite crustal rocks distant to the peridotites equilibrated in the same pressure range at lower temperature 650 700 c high cooling rates 102 103 c ma 1 were calculated for a garnet biotite rock inclusion in the peridotites and for the crustal rocks at the contact by applying garnet biotite diffusion modelling minimum rates of 0 75 7 5 cm a 1 are required for vertical ascent of rock units 30 km vertical distance derived from the crust mantle boundary resulting in a late variscan 340 ma high t low p event

on semi geostrophic flow over synoptic scale topography extension a l aide d une interpretation geometrique des equations des theories semi geostrophiques existantes relatives a un ecoulement au dessus d une crete orographique 2d la methode permet d obtenir des informations meme lorsqu il y a violation locale des hypotheses de normalisation par les echelles le resultat indique que peut etre predite l occurrence de phenomenes tels que vent catabatique trainee et separation dans l ecoulement ce calcul quantitatif exige cependant une version 3d du modele

provenance of cretaceous synorogenic sandstones in the eastern alps constraints from framework petrography heavy mineral analysis and mineral chemistry abstract the detrital components of cretaceous sedimentary rocks in the northern calcareous alps reflect the early alpine geodynamic evolution of the austroalpine microplate two contrasting source areas are distinguished on the base of light and heavy mineral analysis the first source area is located at the southeastern margin of the austroalpine and is composed of palaeozoic sediments and metamorphic rocks mesozoic carbonate rocks and ultrabasic rocks derived from the suture zone of the vardar meliata ocean the second source area is located in the northwest in a lower austroalpine position near the transpressive plate margin that juxtaposes austroalpine and penninic units this source area comprises palaeozoic low grade metamorphic rocks including high pressure hp rocks late palaeozoic meta sediments mesozoic carbonate rocks and ultrabasic rocks from obducted slices of penninic oceanic crust chemical analyses of detrital white mica amphibole and garnet support the discrimination between the two source areas tourmaline chemistry calls for a significant amount of metasedimentary rocks in the source area granitoid rocks and high grade metamorphic rocks are rare blue amphibole phengite and chloritoid composition suggest the erosion of lower blueschist facies rocks in the northwestern source area we suggest a modified model of austroalpine valanginian to coniacian tectono sedimentary evolution which is based on 1 an onset of subduction of the penninic ocean no earlier than late cretaceous 2 deposition of the analyzed sedimentary rocks in piggyback basins and 3 a reconstruction of provenance as proposed in this study

geomechanical characterization of the volcaniclastic material involved in the 2002 landslides at stromboli during the 2002 eruption the nw flank of stromboli volcano southern italy experienced large landslides that produced tsunami waves with a maximum runup of 10 m in height this paper focuses on the geomechanical behavior of the loose volcaniclastic layers the weakest component of the deposit forming the volcano flank tests on the coarse grained volcaniclastic soil and on the rock material forming the grains were conducted in dry conditions a feature of the subaerial slope the rock material in spite of its high porosity exhibits relatively high stiffness and strength due to the remarkable continuity of the solid skeleton accordingly the volcaniclastic soil is characterized by high shear strength during shear tests however significant grain crushing occurs which partly explains the nonlinear shear strength envelope and the strain softening associated with contractive behavior grain crushing was also found to affect compressibility and its time dependency investigated under oedometric conditions

the last erosional stage of the molasse basin and the alps we present a synoptic overview of the miocene present development of the northern alpine foreland basin molasse basin with special attention to the pattern of surface erosion and sediment discharge in the alps erosion of the molasse basin started at the same time that the rivers originating in the central alps were deflected toward the bresse graben which formed part of the european cenozoic rift system this change in the drainage direction decreased the distance to the marine base level by approximately 1 000 km which in turn decreased the average topographic elevation in the molasse basin by at least 200 m isostatic adjustment to erosional unloading required ca 1 000 m of erosion to account for this inferred topographic lowering a further inference is that the resulting increase in the sediment discharge at the miocene pliocene boundary reflects the recycling of molasse units we consider that erosion of the molasse basin occurred in response to a shift in the drainage direction rather than because of a change in paleoclimate climate left an imprint on the alpine landscape but presumably not before the beginning of glaciation at the pliocene pleistocene boundary similar to the northern alpine foreland we do not see a strong climatic fingerprint on the pattern or rates of exhumation of the external massifs in particular the initiation and acceleration of imbrication and antiformal stacking of the foreland crust can be considered solely as a response to the convergence of adria and europe irrespective of erosion rates however the recycling of the molasse deposits since 5 ma and the associated reduction of the loads in the foreland could have activated basement thrusts beneath the molasse basin in order to restore a critical wedge in conclusion we see the need for a more careful consideration of both tectonic and climatic forcing on the development of the alps and the adjacent molasse basin

analysis of regional gullies within noachis terra mars a complex relationship between slope surface material and aspect abstract the precise mechanisms by which martian hillside gullies erode and their dependence on the local environment remain subjects of debate we studied three sharp rimmed craters in noachis terra and 37 gully profiles using context camera ctx mars orbiter laser altimeter mola and high resolution stereo camera hrsc data we analysed the gully topographic profiles of seven gullies and nine dry ravines we measured slope properties using hrsc elevation data and used thermal inertia to infer material types of the gully sites we compared these with three nearby noachian age craters possessing crater wall slope angles within the range of previously observed gully formations in line with previous findings on individual gullies we found that the slope angles of gullies in our study area consistently reflect the inherited slope angles of the host escarpment suggesting that traditional slope based evidence of fluvial activity in martian gullies needs to be placed in context of its local environment we also observed a direct relationship between gully morphology and local composition of surface units martian gully features and possibly method of erosion appeared heavily influenced by changes in underlying geology and presence of erodible sediment examples included gully shape changing in accordance with type of erodible sediment we suggest that the degraded rims of gully free noachian craters precluded slope angles high enough to trigger creation of precursors to alcoves through mass wasting lack of these hollows has probably prevented the accumulation of enough ice rich sediment for gullies to form in our analysis reveals that there is a complex interdependence between slope processes and the local environment and global martian gully models may not work at the local scale

the bollstein odenwald evidence for pre to early variscan plate convergence in the central european variscides new chemical petrological and structural data characterize the pre to early variscan evolution of the eastern or bollstein odenwald which forms a part of the mid german crystalline rise this part of the odenwald crystalline complex is different to the western or bergstrasser odenwald with respect to the age of the magmatic events the structures chemistry and metamorphism the complex is formed by a large anticline composed of an older metamorphosed volcano sedimentary unit and a younger metagranitoid core the volcano sedimentary sequence represents a relic of a pre variscan accretionary prism with relics of older island arc volcanics formed in front of a continental margin during the silurian to lower devonian the prism was intruded by s type granitoids the acidic intrusions were followed by a series of basic intrusives with an island arc signature after the magmatic phases the complex was metamorphosed under probably pre variscan medium pressure and high temperature conditions during variscan times the rocks underwent multiple penetrative deformations under pressure temperature conditions or partial melting the main deformation produced isoclinal folds and had a sense of movement of top to the west during subsequent deformation the anticlinal structure and the otzberg fault zone were formed and later overprinted by two generations of open folds with vertical and horizontal axes the rocks of the bollstein odenwald document multiple plate convergences of pre to early variscan to upper visean age

probabilistic rainfall thresholds for triggering debris flows in a human modified landscape abstract in the carrara marble basin cmb apuan alps italy quarrying has accumulated widespread and thick quarry waste lying on steep slopes and invading valley bottoms the apuan alps are one of the rainiest areas in italy and rainstorms often cause landslides and debris flows the stability conditions of quarry waste are difficult to assess owing to its textural geotechnical and hydrogeological variability therefore empirical rainfall thresholds may be effective in forecasting the possible occurrence of debris flows in the cmb three types of thresholds were defined for three rain gauges of the cmb and for the whole area rainfall intensity rainfall duration id cumulated event rainfall rainfall duration ed and cumulated event rainfall normalized by the mean annual precipitation rainfall intensity emapi the rainfall events recorded from 1950 to 2005 was analyzed and compared with the occurrence of debris flows involving the quarry waste they were classified in events that triggered one or more debris flows and events that did not trigger debris flows this dataset was fitted using the logistic regression method that allows us to define a set of thresholds corresponding to different probabilities of failure from 10 to 90 and therefore to different warning levels the performance of the logistic regression in defining probabilistic thresholds was evaluated by means of contingency tables skill scores and receiver operating characteristic roc analysis these analyses indicate that the predictive capability of the three types of threshold is acceptable for each rain gauge and for the whole cmb the best compromise between the number of correct debris flow predictions and the number of wrong predictions is obtained for the 40 probability thresholds the results obtained can be tested in an experimental debris flows forecasting system based on rainfall thresholds and could have implications for the debris flow hazard and risk assessment in the cmb

shear strength of rockfill a practical method for estimating the shear strength of rockfill is developed the peak drained friction angle prime is found to be closely related to that of rock joints in both cases the values of prime are dependent on sample size stress level surface roughness and on the uniaxial compression strength of the rock friction angles are therefore higher for smaller samples and very high where stresses are low as at the toe or near the face of a rockfill dam test data reviewed shows that the value of prime for rockfill can be quantified by a equivalent roughness r and an equivalent particle strength s the value of r depends on the porosity following compaction and on the degree of particle roundedness and surface smoothness a practical method is proposed for physically measuring the full scale shear strength of in place compacted rockfill

evaluation of garnet discrimination diagrams using geochemical data of garnets derived from various host rocks abstract this work is an attempt to evaluate six different garnet discrimination diagrams one binary diagram and five ternary diagrams commonly used by many researchers the mineral chemistry of detrital garnet is a useful tool in sedimentary provenance studies yet there is no clear cut understanding of what garnet type originates from which host lithology several discrimination diagrams exist for garnet showing distinct compositional fields separated by strict boundaries that are thought to reflect specific types of source rocks for this study a large dataset was compiled n 3532 encompassing major element compositions of garnets derived from various host lithologies including metamorphic igneous and mantle derived rocks in order to test the applicability of the various discrimination schemes the dataset contains mineral chemical data collected from the literature complemented with some new data n 530 from garnet bearing metamorphic and ultramafic rocks in austria and norway discrimination of the tested diagrams only works for a small group of garnets derived from mantle rocks granulite facies metasedimentary rocks and felsic igneous rocks for other garnet types the assignment to a certain type of host rock remains ambiguous this is considered insufficient and therefore the evaluated diagrams should be used with great care we further apply compositional biplot analysis to derive some hints towards future perspectives in detrital garnet discrimination