large scale three dimensional gravity analysis of the lithosphere below the transition zone from western europe to the east european platform abstract large scale three dimensional gravity modelling using data averaged on a 1 grid has been carried out for the transition area from western europe to the east european craton the model consists of two regional layers of variable thickness the sedimentary cover and the crystalline crust with lateral variation of average density removal of the calculated gravity effect of the crustal model from the observed gravity field reveals residual anomalies of mantle origin this is confirmed by the correlation between mantle gravity anomalies and upper mantle velocity heterogeneities imaged by seismotomographic studies the tornquist teisseyre zone ttz marked in general by a gradient zone of mantle gravity anomalies is considered as a deep density section traced in the upper mantle down to a depth of 200 km across this suture zone a dramatic change of the structure physical properties and composition of the lithosphere of the continent occurs the different characters of the mantle gravity anomalies over the two main parts of the ttz the danish scandinavian and polish segments are explained by the peculiarities of their evolution and the different character of the prevailing tectonic regimes during the proterozoic cenozoic

velocity structure of the western mediterranean from inversion of p wave traveltimes residuals along ray paths with a penetration depth of 70 300km in the western mediterranean the inversion procedure is based on the backus gilbert formalism for linear inversion of traveltime data extended for 2 d and 3 d inhomogeneous media by yanovskaya 1980 and gobarenko yanovskaya 1983 p wave traveltime residuals are derived along 87 ray paths from analyses of the isc bulletin data the p wave velocity patterns constructed after the inversion for the depth interval 50 300 km are characterized by well pronounced low velocity zones in the french massif central the tyrrhenean sea and the ligurian sea and by a high velocity zone in southern italy and sicily these patterns are discussed in terms of geophysical data regional isostatic anomalies heat flow for the region several possible mechanisms mantle convection compositional changes in the low velocity layer causing the obtained correlation between different geophysical fields are discussed

upper mantle structure under western europe from fundamental and higher mode surface waves using the nars array summary a generalized inversion of a new data set consisting of surface wave phase velocities and sn traveltimes has resulted in a new shear velocity and density model for the west european platform wepl 2 the surface wave phase velocity data set consists of fundamental and higher mode mode 1 6 measurements from 25 to 70mhz using the network of autonomously recording stations nars array which was specifically designed for higher mode surface wave measurements the sn traveltime data set consists of isc readings for selected european events major features of wepl 2 are a high velocity lid of 80 140 km depth underlain by a pronounced low velocity zone between 160 and 220 km depth the transition zone 400 650 km depth is characterized by high shear velocities with respect to prem the density shows a positive gradient from 60 to 140 km depth followed by an approximately constant value down to 400 km depth a model for the baltic shield scsh 2 is obtained by combination of nolet s 1977 higher mode phase velocity data set for western europe including the baltic shield and the present phase velocities for the platform this shield model shows an absence of the low velocity layer and low shear velocities in the top of the transition layer with respect to wepl 2 density although less well resolved shows lower values for the shield structure between 200 and 350 km depth

saharan wind regimes traced by the sr nd isotopic composition of subtropical atlantic sediments last glacial maximum vs today new nd sr isotopic data on the 30 m lithic particles of surface and last glacial maximum sediments recovered along the african margin between the equator and the gibraltar strait are presented in combination with grain size measurements this 30 m size fraction allows us to eliminate any hemipelagic contribution that could occur in the coarser fractions in the eolian fraction both sr and nd isotopic tracers reveal the same major northwestern origin mauritania mali southern algeria and morocco the archaean formations of the western saharan shield could be the source of the very unradiogenic ratios observed here the more southern regions senegal guinea act only as secondary sources a similar pattern is observed for the lgm lithic particles are mostly transported by both trade and saharan air layer sal winds along an approximate ne sw axis this main feature matches the southern plume characterizing the dust transport observed during winter no significant latitudinal shift of the belt winds is observed between the lgm and today at the lgm however dust fluxes were 2 4 times higher than today leading to a more archaean type imprint in the deposits we do not observe any clear relationship between the latitudinal variability of the upwelling systems identified in this region at the lgm and the location of the major wind systems both enhanced aridity on the continent and increased wind speed probably occurred together over western tropical africa during the last glacial period

garnet zoning and metamorphism of the barrovian type area scotland a microprobe investigation of the high grade metamorphic zones from the barrovian type area in angus scotland shows the importance of local zones of retrograde cation exchange between garnet staurolite and biotite the interpretation of this zoning established during a slow cooling history is critical to any study of metamorphic reactions or conditions the extent and intensity of these diffusion effects are dependent on a number of parameters including grainsize fabric orientation heating and cooling history and the modal abundance of the phases increasing diffusion within garnets with metamorphic grade and the subsequent retrograde effects are modelled using temperature time transformation diagrams and provide information on the activation energy for fe mg diffusion in garnet

tracing dust sources and transport patterns using sr nd and pb isotopes continental dust transported through the atmosphere can be a tracer of atmospheric circulation and transport as well as being a source of information about climate in the dust s source area this information about the provenance of dust transported from desert areas and deposited elsewhere on the oceans and continents can be evaluated using several observational techniques satellite imagery has been used to this end in recent decades and air mass back trajectories have been calculated to trace dust deposits back to their source area another method consists of analysis of the concentration and composition of certain tracers in the dust itself and comparing them to soils and sediments from possible source areas this method has the advantage of being useable for paleo atmospheric circulation and paleo dust transport studies whereas satellite imagery and air mass back trajectories are restricted to relatively recent times we review here different kinds of isotopic tracers that have been used to trace dust provenance but special attention is focused on the use of sr nd and pb isotopes we evaluate their use in studies of both spatially as well as temporally varying continental dust source and transport

large scale 3 d gravity analysis of the inhomogeneities in the european mediterranean upper mantle methods and the results of estimating the anomalies characterising the density inhomogeneities in the european mediterranean upper mantle are described these anomalies were obtained by subtracting the gravity effect of a crustal density model derived from seismic velocities from the observed gravity field averaging over an area of 1o 1o the 3 d density model of the study region comprises two regional layers of varying thickness with lateral variation of average density the sedimentary cover and the crystalline crust the average densities for model layers were evaluated by using a velocity density conversion function and taking into account sediment consolidation with depth clear correlation between residual gravity anomalies and both velocity heterogeneities and thermal regime data of the upper mantle has been revealed an agreement of positive anomalies over the alps the adriatic plate and the calabrian arc with high velocity domains in the upper mantle and reduced temperatures at the subcrustal layer are caused by lithospheric roots and thickened lithosphere below these structures gravity residual lows revealed over the western mediterranean basin and pannonian basin are in correspondence with both low velocities and high temperatures in the upper mantle these anomalies are the result of the presence of asthenosphere in shallow near moho depths below these basins

tectonosphere of the earth upper mantle and crust interaction abstract the endogenic geological processes which include tectonic magmatic and metamorphic processes form regular combinations called endogenic regimes these regimes are geosynclinal orogenic platform rift tectonic magmatic activation diwa taphrogenic plateau basalt oceanic basins and mid oceanic ridges the endogenic regimes are connected with the peculiarities of the structure composition and state of the entire tectonosphere i e not only of the crust but of the upper mantle as well heat flow is a major factor controlling the type of the regime the other conditions are the temperature distribution in the tectonosphere and the degree and type of penetrability of the tectonosphere to melts and fluids there is a certain regular succession of regimes the structural evolution of the tectonosphere and the transformation of the matter in it are in close relationship the main trend in the development of the tectonospheric material is directed towards geochemical depletion of the upper mantle by fractioning at the initial stages fractioning occurred mostly by degassing and under these conditions the continental crust was formed rich in non compatible elements at that stage the calc alkaline magmas prevailed as the upper mantle was depleted and began to lose its volatiles the mechanism of fractioning changed degassing was substituted for selective melting and in this environment most of the tholeiitic magmas were formed this change in magma composition and in fractioning mechanism was combined with the destruction of the continental crust and the formation of the oceanic crust the diwa regime and the rifts were the first steps in the destruction of continental crust the stages that followed were represented by taphrogenic regimes at various levels these kinds of regimes were manifested in deep continental and marine depressions compensated and not compensated by sediments taphrogenic regimes are advancing from the east and west onto the eurasian continent in the east they form marginal seas and cause subsidence of the eastern parts of the chinese platform in the west they produce collapses of the crust in the mediterranean area the major crisis occurred between the palaeozoic and mesozoic and since that time the process of substitution of the continental crust by the oceanic crust has proceeded over increasingly large territories the evolution of the tectonosphere instigated by the changes in its matter was further complicated by temporal and spatial irregularities in deep heat escape which caused the alternation of excited and quiescent endogenic regimes tectonomagmatic periodicity and their co existence the combination of all these phenomena creates the structural inhomogeneity of the earth s crust at any stage of its history

tectonics and topography for a lithosphere containing density heterogeneities the purpose of this paper is to clarify the dynamic role of lithospheric density heterogeneities in particular with respect to mountain building and other processes of intraplate deformation density anomalies within or just beneath the lithosphere constitute major sources for tectonic stress fields the product of their magnitude by their depth is shown to characterize their ability to induce deformation this rule of the density moment directly yields the lithospheric thickening or thinning rate when applied to structures of large lateral extent for anomalies of lateral extent that is small in comparison with their depth the deformation is vertically inhomogeneous and has been computed with the help of simple physical models of a stratified viscous newtonian lithosphere the analytical treatment is based on fourier transform continent continent collision thickens not only the crust but the entire lithosphere the cold root underlying a mountain chain induces strong regional compressive stresses able to sustain the mountain bulding process without further help from forces transmitted from far away thus the continental lithosphere is in a somewhat metastable mechanical state adiabatic i e rapid thickening or thinning tends to grow further once initiated tectonic phases of strong compression correspond to the climax of such instabilities the response of models with cold lithospheric roots of various intensities has been computed both in two and three dimensions they yield velocity distributions and stress fields instructive comparisons are made with earthquake focal mechanisms and in situ stress measurements in the alpine and appalachian regions in the presence of lateral variations of the mechanical properties of the lithosphere the tectonic style is not only function of the local topography and of the nature of its compensation deformations in neighbouring provinces are coupled as shown by 3 dimensional models for example thickening sustained by a cold lithospheric root may generate extension in peripheral zones of weakness these last results illustrate the point that the computation of regional tectonic stresses requires the knowledge of the density anomalies within the lithosphere on the one hand and of geometrical constraints related to lateral mechanical heterogeneities on the other

late quaternary changes in desert dust inputs to the red sea and gulf of aden from 87sr 86sr ratios in deep sea cores abstract strontium isotope ratios of the hcl insoluble residue isr and foraminifera of cores from the red sea and gulf of aden are used to monitor effects of hydrothermal fluvial and desert dust transport to these regions during the past 0 5 ma while the gulf of aden was open ocean during low glacial sea levels the red sea was a semi isolated basin allowing the possibility to study the effects regional versus global inputs during glacial interglacial cycles the isr from the gulf of aden and the red sea display different ranges of 87 sr 86 sr ratios of 0 7085 0 7107 and 0 7062 0 7085 respectively these reflect mixtures between three components granitic hydrothermal and loess strontium with representative 87 sr 86 sr of 0 711 0 706 and 0 7085 respectively gulf of aden isr represent mixtures of the loess and granitic sources while red sea isr are mixtures of the loess and sea floor hydrothermal sources in the gulf of aden loess sources dominate during glacials indicating intensification of the ne moonsonal wind regime and granitic sources dominate during interglacials reflecting wetter conditions related to an enhanced regional sw monsoon red sea isr show no clear glacial interglacial distinction but display a general temporal increase in 87 sr 86 sr ratios over the past 380 ka toward loess like values indicating increasing loess contributions toward the present day the ranges of isr 87 sr 86 sr ratios in the red sea and the gulf of aden were distinct prior to the last glacial period 87 sr 86 sr ratios following major climate transitions at 10 80 130 190 240 and 330 ka bp that coincide with sapropel episodes in the eastern mediterranean which originated from the african monsoonal system and indicate enhanced wetness in the desert belt 87 sr 86 sr ratios of foraminifera show a very narrow range from 0 70912 to 0 70917 over 530 ka and in most samples are consistent with the contemporaneous global ocean in the red sea foraminifera and pteropods show slightly more variability than the gulf of aden a few red sea samples fall slightly above the seawater trend in marine isotope stages 5 and 9 and below during the last deglaciation suggesting local effects that occurred when the flow of surface ocean water from the gulf of aden to the red sea was limited and the red sea behaved like an amplifier basin

lineaments and basement domains an alternative view of dalradian evolution this paper examines the evidence for basement structures of predominantly non caledonoid trend which appear to have influenced the development of the dalradian belt in scotland a number of domains or blocks separated by dominantly trans caledonoid lineaments are recognized on the basis of geophysical stratigraphical and geochemical patterns these are thought to reflect fault bounded depositional basins controlled by basement lineaments during the extensional phases of the caledonian 9orogeny9 in addition the recognition of a number of these domains and lineaments in the structural metamorphic and igneous data sets for the dalradian belt shows the continuing influence of these basement controlled features throughout the compressional and uplift phases of the orogenesis a possible tectonic model is proposed which envisages the depositional basins forming in a setting dominated by caledonoid trending transcurrent faults and a major pull apart basin forming on a trans caledonoid axis

the effect of dust deposition on the soils of the land of israel abstract loess and aeolian dust affected soil formation to different degrees in most parts of the land of israel in the arid desert the loess was re eroded from slopes and sedimented as fluvial loess in along the valleys by flood water in areas with slight precipitation loess remains on slopes sedimentation rates are slower and loessial serosems are formed in the mildly arid areas in the northern negev the loess covers most of the landscape and occurs in thick sequences intercalated with several superimposed strongly developed loessial brown soils sedimentary and weathering processes occurred simultaneously and sediment palaeosols profiles up to 12 m thick were formed in areas further away from the desert aeolian deposition decreased as a result loessial brown soils grade into dark brown grumic soils and grumusols aeolian dust input also affected soils of the sand dunes of the coastal plain and in the terra rossa soils of the mountainous region

three dimensional interpretation of gravity data from sedimentary basins using an exponential density depth function in mapping the topography of the basement of deep sedimentary basins by gravity modelling the accuracy can be improved by incorporating an exponential increase in density with depth for calculating the gravity effect of a three dimensional 3d structure with such an exponential density depth relation a frequency domain forward algorithm based on series expansion is presented the numerical evaluation of which can be performed efficiently by fast fourier transform the algorithm can be applied in a recursive procedure to give the inverse solution in terms of basement relief the inversion procedure is satisfactorily tested on a 2d synthetic example and a 3d field example of gravity data from the western margin of the pannonian basin in eastern austria where up to 2 2 km of tertiary sediments overlie an igneous or metamorphic basement the results are confirmed by basement intersections in several wells

on application of three dimensional interactive modeling in gravity and magnetics by h j gotze and bernd lahmeyer geophysics 53 1096 1108 august 1988 gotze and lahmeyer present the main principles and results new automatic system for the interactive modeling of three dimensional 3 d gravity and magnetic fields the high efficiency of the system is demonstrated convincingly on a practical example of a geologic study in the northwest german basin the importance and timeliness of this work are beyond doubt nonetheless a few remarks on the analytical results seem to be appropriate

multiple dust sources in the sahara desert the importance of sand dunes 1 we determine the current sources of dust in the sahara desert using quantitative correlation between the number of days with dust storms nds derived from remote sensing data of high temporal resolution with the distribution of the soil types and geomorphic units during 2006 8 the source of over 90 of the nds was found to be sand dunes leptosols calcisols arenosols and rock debris in contrast to previous studies only few dust storms originated from playas and dry lake beds land erodibility was estimated by regressing the nds to the number of days with high speed wind events and was found to be high for sand dunes clay and fine silt grains and aggregates are scarce in sand dunes which most likely produce dust particles through aeolian abrasion of sand grains thus saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the sahara

the micromorphology of gypsum and halite in reg soils the negev desert israel gypsum and halite are the most common salts in reg soils developed on alluvial parent material under extremely arid conditions in the negev desert israel the aim of this paper is to document the changes in the micromorphology of these salts at different stages of reg soil development on two alluvial fan chronosequences the micromorphological analyses included thin section observations and scanning electron microscope and electron microprobe analyses in this arid soil environment gypsum and halite possess a variety of crystal forms which may change with depth in a single profile and or between profiles of different ages the variety of crystal forms results from changes in the microenvironmental conditions that occur in desert reg soils over time poikilitic lenticular gypsum is found in all reg soils and is distributed throughout the profiles the conditions needed for such crystals to form are high ionic impurities and deposition in a void system where space is not limiting microcrystalline alabastrine gypsum is only found in mature reg soils and is crystallized when the profile has high amounts of fine material and a well developed desert pavement in a well developed reg soil profile indicators such as a well developed desert pavement and high amounts of fine earth limit the leaching depth and cause gypsum deposition from supersaturated soil solutions under high evaporation rates close to the surface prismatic and fibrous gypsum are less common low amounts of prismatic gypsum are found in young and mature soils while fibrous gypsum is found only in mature soils in re cemented shattered gravel the halite crystal form is mainly cubic with low amounts of host material incorporated into the crystal it occurs predominantly in mature reg soil profiles through the crystallization from supersaturated soil solutions at the depth of maximum water penetration although the alabastrine prismatic and fibrous gypsum and cubic halite are deposited in a displacive manner no correlation was found between their occurrence and the distribution of shattered gravel in the soil profile

restoration of the cretaceous uplift of the harz mountains north germany evidence for the geometry of a thick skinned thrust reverse movement on the harz northern boundary fault was responsible for the late cretaceous uplift of the harz mountains in northern germany using the known geometry of the surface position and dip of the fault and a published cross section of the base permian horizon we show that it is possible to predict the probable shape of the fault at depth down to a detachment level we use the inclined shear method with constant heave and argue that a shear angle of 30 was most likely in this case the detachment level is at a depth of ca 25 km kinematic restoration of the harz mountains using this fault geometry does not produce a flat horizon rather it results in a ca 4 km depression airy heiskanen isostatic equilibrium adjustment of the harz mountains restores the base permian horizon to the horizontal as well as raising the moho to a depth of 32 km a typical value for northern germany restoration also causes a rotation of tectonic fabrics within the harz mountains of about 11 clockwise we show that this model geometry is very good fit to the interpreted dekorp basin 9601 deep seismic profile

soils in the mediterranean region what makes them different mediterranean climates are characterized by winter rains with some months of excess rainfall over evatranspiration warm and dry summer months with moisutre deficits drying out soils and their annual vegetation xeric moisture regime they are found on western parts of all continents between the cooler temperature zone and the hot dry desert zone the largest mediterranean region surrounding the mediterranean sea extends over 4 300 000 km2 and exhibits a wide variety of soils and geo ecosystems characteristics landscape attributes are the high proportion of mountains with sleep slopes significant additions of saharan desert dust to practically all soils of the region and a large proportion of limestone and other calcareous rocks as soil parent materials characteristics soil behavior features are moderate weathering with pervection leaching lessivage of mostly 2 1 clays into b horizons xeralfs luvisols hematite induced reddening of the clays due to summer dehydration of free iron oxyhydroxides carbonate dissolution and reprecipitation with prevalence of calcic horizons xerolls calcisols in semiarid regions and development of vertisols mostly in lowlands where deep layers of swelling cracking clays have sedimented shallows soils on nearly bare slopes mostly a result of erosion subsequent to deforestation are frequent leptosols cambiosols inceptisols entisols red or brown mediterranean soils are no longer used as a separate classification group in modern well defined soil property controlled taxonomies soil taxonomy fao system but were partially replaced by duchaufour s term fersiallitic soils in some classification systems terra rossa continues to be used in some classification for hard limestone derived red soils mostly shallow the effects of man s past and current interference with the lanscape are pervasive in most regions and predictions for possible future effects on the soils and ecosystems due to greenhouse gas induced warming and rainfall change are partly negative partly still too uncertain

localized uplift in the scottish dalradian rb sr mica ages are reported here from the dalradian meta sediments of the angus region in the scottish highlands fig 1 in a study of the uplift history of this classic metamorphic terrain the samples come from across the barrovian metamorphic zones1 and provide evidence of diachroneity in both metamorphism and later cooling thus the oldest mineral ages and hence earliest cooling are found in the highest grade metamorphic rocks to the north the results show the importance of tectonically controlled localized uplift processes given that erosion is an important influence on the thermal development of metamorphic rocks2 the constant or steadily decaying isostatic uplift rates often assumed in models of orogenic belts2 3 may be a marked oversimplification of the real events

100 000 years of african monsoon variability recorded in sediments of the nile margin abstract multiproxy analyses were performed on core ms27pt recovered in hemipelagic sediments deposited on the nile margin in order to reconstruct nile river palaeohydrological fluctuations during the last 100 000 years the strontium and neodymium isotope composition of the terrigenous fraction and the major element distribution reveal large and abrupt changes in source oscillating between a dominant aeolian saharan contribution during arid periods and a dominant nile river contribution during pluvial periods iron content shows a strong correlation with strontium and neodymium isotopes this allows the use of a high resolution continuous fe record as a proxy of blue nile sediment input over the last 100 000 years the detailed fe record with approximately 10 years resolution during pluvial periods is consistent with subtropical african records of well dated lake level fluctuations and thus constitutes a first continuous high resolution record of the east african monsoon regime intensity over ethiopia the detailed fe record shows the two main known pluvial periods attributed to strengthening of the african monsoon over ethiopia the nabtian period from 14 to 8 ka cal bp and the saharan period from 98 to 72 ka bp for the first time the last glacial period marine isotope stage mis 2 3 and 4 is documented with a continuous record showing large oscillations between high and low east african palaeo monsoon regimes the end of the nabtian period occurred at 8 ka in core ms27pt i e much earlier than on the east equatorial african region where it ended around 5 5 ka we interpret this as evidence that the southward shift of the rain belt occurred 3000 years earlier over the eastern ethiopian highland and propose that the gradual southward migration of the rain belt was associated with highly variable intensity and longer rainy seasons from 8 to 5 ka during the last glacial period two wet periods are present around 60 50 ka bp and 38 30 ka bp these two humid periods are in phase with the rise of atmospheric ch4 concentrations suggesting that wetland tropical african area was one of the sources of the atmospheric ch4 during the mis 3 during the last glacial maximum and mis 4 high saharan aeolian influxes in phase with records of aeolian dust deposited in east antarctica are documented this study highlights the importance of reconstructions of monsoon rainfall fluctuation at high temporal resolution to better understand the link between low and high latitude climate variability at millennial timescales

distribution of natural and anthropogenic lead in mediterranean soils abstract the concentrations and isotopic composition of pb have been combined with a selective sequential dissolution procedure to track the distribution of anthropogenic and natural pb in the soil of semiarid climate and the penetration pathway of petrol pb within the soil profile soil samples were collected from soil profiles adjacent to a major highway 8 23 m and from soil profiles 500 m away from the same highway the selective sequential dissolution procedure was used to determine the distribution of pb between the different soil components soil carbonate organic matter fe oxides and hydrous oxides and aluminosilicates natural pb is associated mainly with aluminosilicates 60 and fe oxides 30 and only a small fraction with the soil carbonate and organic matter 10 in contrast to the distribution of natural pb the distribution of anthropogenic pb which accumulates mainly in the upper part of the soil profile is 40 with the soil carbonate 10 with organic matter 35 with fe oxides and only 15 with aluminosilicates on the basis of concentration and isotopic composition of total pb the deeper horizon of the roadside soil 10 30 cm and the soil sampled 500 m from the highway seem uncontaminated however the isotopic composition of the labile components in the soil pbcarb pborg and pbfe ox indicates that these soils are actually contaminated this contamination implies that over the period of vehicle pollution 40 yr petrol pb has penetrated through the entire roadside soil profile 25 30 cm furthermore pb isotopes in aluminosilicates of the upper part of the roadside soil indicate that this pb too is anthropogenic measurements of pb concentration and isotopic composition in roadside soil profiles sampled in 1997 and archived samples collected at the same location in 1982 provided a unique opportunity to trace petrol pb penetration into the soil

lithosphere structure of europe and northern atlantic from regional three dimensional gravity modelling summary large scale 3d gravity modelling using data averaged on a 1 grid has been performed for the whole european continent and part of the northern atlantic the model consists of two regional layers of variable thickness the sediments and the crystalline crust bounded by reliable seismic horizons the seismic basement and the moho surface inner heterogeneity of the model layers was taken into account in the form of lateral variation of average density depending on the type of geotectonic unit density parametrization of the layers was made using correlation functions between velocity and density for sediments sediment consolidation with depth was taken into account offshore a sea water layer was included in the model as a result of the modelling gravity effects of the whole model and its layers were calculated along with the gravity modelling an estimation of isostatic equilibrium state has been carried out for the whole model as well as for its separate units residual gravity anomalies obtained by subtracting the gravity effect of the crust from the observed field reach some hundred mgal 10 5 ms 2 in amplitude they are mainly caused by density heterogeneities in the upper mantle a mantle origin of the residual anomalies is substantiated by their correlation with the upper mantle heterogeneities revealed by both seismological and geothermal studies regarding the character of the mantle gravity anomalies type of isostatic compensation crustal structure age and supposed type of endogenic regime a classification of main geotectonic units of the continent was made as a result of the modelling a clear division of the continent into two large blocks precambrian east european platform eep and variscan western europe has been confirmed by their specific mantle gravity anomalies 0 50 10 5 ms 2 and 100 150 10 5 ms 2 correspondingly this division coincides with the tornquist teisseyre zone ttz marked by a gradient zone of mantle anomalies in the central part of the eep over the russian plate an extensive positive mantle anomaly probably indicating a core of ancient consolidation of the eep has been distinguished to the west and to the east of this anomaly positive mantle anomalies occur which coincide with a deep suture zone ttz and an orogenic belt the urals positive mantle anomalies of the alps the adriatic plate and the calabrian arc correlating well with both high velocity domains in the upper mantle and reduced temperatures at the subcrustal layer are caused by thickened lithosphere below these structures negative mantle anomalies revealed in the western mediterranean basin and in the pannonian basin are the result of thermal expansion of the asthenosphere shallowing to near moho depths below these basins

three dimensional gravity modelling of the european mediterranean lithosphere summary residual gravity anomalies characterizing the density heterogeneities in the upper mantle of the alpine belt of western europe are determined residual anomalies were calculated on a 1 x 1 grid by subtracting the gravity effect of the density model for the earth s crust from the observed gravity field our 3 d density model consists of two regional layers of varying thicknesses with a lateral variation in average density the sedimentary cover and the crystalline crust offshore the model is supplemented by a sea water layer this 3 d density model is based on a generalized velocity model represented by structure maps of the main seismic horizons the seismic basement and the moho boundary and a map of the average p wave velocity in the consolidated crust the density distribution within the model layers was obtained using the correlation functions between p wave velocity and density for sediments sediment consolidation with depth was taken into account the gravity effect of the model approximated by parallelepipeds 1 x 1 in planar size was calculated by a program designed for solving 3 d gravity problems the program takes into account the spherical configuration of the earth this method also permits the estimation of the isostatic state of the crust a mantle origin of residual gravity anomalies is confirmed by their close correlation with upper mantle velocity heterogeneities established by both seismic tomography and thermal regime data the residual gravity field is inverted into the distribution of anomalous density within the uppermost mantle layer between the moho and a bottom level at 200 km depth the most important anomalies are the high density domains caused by the thick lithosphere of the adriatic plate and by the lithosphere roots beneath the alps and the calabrian arc negative density anomalies over the pannonian basin and the western mediterranean basins reach 0 04 to 0 05 x lo3 kg m 3 due to thermal expansion of the asthenosphere

dust transport and synoptic conditions over the sahara arabia deserts during the mis6 5 and 2 1 transitions from grain size chemical and isotopic properties of red sea cores abstract the red sea situated between the sahara and arabia deserts is a natural trap for fine grained particles transported by winds and floods from weathered materials in these deserts derived from the proterozoic crustal granitic and basaltic terrains and phanerozoic carbonates the accumulated fine particles provide valuable information on the climate conditions in the source regions and modes of atmospheric circulation over the red sea region here we report on the grain size mineralogy chemical composition and nd and sr isotope ratios of fine grained insoluble residues ir from acid leaching that were recovered from two deep sea cores kl23 and kl11 drilled in the northern and central red sea respectively we focus on the mis6 5 and mis2 1 transitions kl23 samples are closer to the sahara granitoids field and display significant variations during the mis6 5 transition between end of 7 to 2 and 87sr 86sr of 0 7096 to 0 7114 smaller variations occurred during the mis2 1 transition between end of 5 to 6 and 87sr 86sr of 0 7104 to 0 7118 the kl11 values are closer to the blue nile field which comprises mixtures of granitoid and basalt derived particles during the mis6 5 transition their end varies from 4 to 1 and in 87sr 86sr from 0 7059 to 0 7091 during periods equivalent to sapropels s5 and s1 both cores appear to converge to similar isotope ratios of e nd 2 and 87sr 86sr 0 7095 indicating derivation from the granitoid terrains of the arabian nubian shield occurring adjacent to the red sea and possibly distributed by runoff in terms of synoptic conditions the data indicate that during glacials dust was blown to the northern red sea from the northern sahara desert in association with the mediterranean winter cyclones and to the central red sea from the ethiopian plateau by southern winds that are associated with monsoonal circulation during interglacials especially sapropel intervals monsoonal rains caused erosion and flooding at the arabian nubian shield margins of the red sea during the heinrich events associated with the studied intervals h11 and h1 dust from mixed basaltic granitic terrains was blown from all of the regional sources in the red sea region reflecting severe regional aridity and transport of dust by regional winds when monsoonal activity and mediterranean cyclone activity were weak

tracing the transport of anthropogenic lead in the atmosphere and in soils using isotopic ratios the isotopic composition of lead in aerosols and soils in israel is used to characterize the sources of anthropogenic lead in the region to ascertain the isotopic composition of natural rock derived lead in specific areas and to determine rates of anthropogenic lead migration in soils the isotopic composition of lead currently emitted from cars in israel 206pb207pb 1 115 2 is controlled by alkyl lead produced in france and germany in addition to petrol lead two more sources of anthropogenic lead can be detected in sampled aerosols the first one has low concentrations of lead 4 ng m3 and 206pb207pb 1 157 and is most likely lead emitted in turkey that traveled across the eastern mediterranean basin the second type of aerosols contains a mixture of lead emitted in several countries including turkey greece and ukraine 206pb207pb value of 1 155 1 160 pb 20 30 ng m3 anthropogenic lead is more accessible for acid leaching than natural lead therefore it is more labile in the soil the isotopic composition of lead in the acid leached fraction of near road soil profiles record the histor of alkyl lead emission in the country based on changes in the isotopic composition of lead with soil depth it is estimated that anthropogenic lead migrates into the soil at approximately 0 5 cm y a soil profile from a relatively remote area is less contaminated by anthropogenic lead and displays a different distribution of lead isotopic values with depth the isotopic composition of lead suggests that natural lead in soils developed on carbonate bedrock is derived from clays either from the rock esidue the clay fraction in the carbonate bedrock or from airborne clay but not from lead released from the carbonate fraction in the rock

bulk composition of northern african dust and its source sediments a compilation abstract this paper presents a review of bulk compositional data of northern african dust and its potential source sediments and includes elemental isotope and mineralogical data northern african dust represents about one half of the total global atmospheric mineral dust burden and its uplift transport and deposition have strong impacts on climate and various terrestrial and marine ecosystems the chemical data set shows that an average northern african dust exhibits comparable si fe and mn contents with respect to the average composition of the upper continental crust is slightly depleted in the alkali metals k and na and enriched in ti and p however the complete data set yields clear evidence that northern african dust and its source sediments are compositionally heterogeneous on a regional scale and that this heterogeneity can be used to differentiate between major potential source areas on the basis of so called source markers an evaluation of these compositional fingerprints shows that the following parameters and especially their combination are effective in the discrimination of the most active source areas in northern africa ratio of ca mg fe wt calcite or carbonate content palygorskite occurrence and abundance illite kaolinite ratio nd 0 value and 87sr 86sr ratio for example the data set corroborates previous ideas which assign carbonate illite and palygorskite rich mineral dusts to north west ern source regions because most of the above listed source markers do not change substantially during transport even far traveled dusts may be assigned to specific potential source areas in northern africa some limitations of the presented data set are also discussed our compilation reveals some substantial gaps in the knowledge of the composition of source sediments and mineral dusts from important potential source areas that should be filled in the future the here compiled data set can be used as a reference frame when incorporating the composition of source sediments e g mineralogy into global or regional dust transport models and can be compared with source analysis by remote sensing or back trajectory analysis however source apportionment studies supported by our data set will not only be useful for actual dust samples but will also be helpful for the understanding of paleo wind directions and hence paleo climatological conditions through the investigation of quaternary eolian sediments deposited in and around northern africa

gravity interpretation of a unified 2 d acoustic image of the central alpine collision zone summary four individual deep seismic reflection profiles across the eastern and southern swiss alps have been combined along the trend of the bouguer gravity anomalies onto the european geotraverse the profiles were migrated ray theoretically with the migration velocity model derived from a smoothed reinterpretation of the seismic wide angle profiles running parallel to the strike of the alpine arc the contours of this velocity model were ray theoretically depth migrated together with the combined digitized line drawings of the seismic reflection profiles the resulting acoustic image depicts the subduction of parts of the lower crust of the european plate beneath the adriatic promontory of the african plate at a low angle of 15 based on the interpretation of the seismic data orogenic crustal thickening is attributed to the stacking of crystalline nappes onto the upper crust of the european plate and wedging of the european and adriatic middle and lower crusts the latter being ill constrained by the seismic evidence alone the south vergent thrusting of the southern alps can be accounted for by the observed downbending of the adriatic moho and the lower crust in conjunction with the inferred wedging at mid crustal levels using the geometric constraints provided by seismic data gravity modelling of the alpine lithosphere asthenosphere system relative to stable central european platform clearly favours a gently inclined subduction zone reaching down to at least 200 km depth such a gently dipping subduction zone is at odds with prominent models on alpine geodynamics which favour a near vertical orientation of the subducting lithosphere verschluckung in agreement with the wedging hypothesis indirectly inferred from the seismic data the short wavelength part of the alpine gravity anomaly requires a middle crust of anomalously high density in the axial zone of the orogen both seismic and gravimetric evidence therefore suggest that late orogenic lithospheric shortening and crustal thickening was governed by the mechanical decoupling of the upper middle and lower parts of the crust the amount of subducted lower crustal material cannot be constrained by gravity modelling since its gravity effect cannot be separated from the effect of the subducting slab

gravity field over northern eurasia and variations in the strength of the upper mantle the correlation of long wavelength gravity anomalies in northern eurasia with seismic velocity anomalies in the upper mantle reverses in sign between western and eastern eurasia the difference between western and eastern eurasia can be explained by the presence of a low viscosity zone in the uppermost mantle beneath eastern eurasia that is absent to the west the location of the lateral change in viscosity corresponds with the geologic boundary between the older shields and platforms of the baltics russia and siberia and the younger geologically active mountain belts of eastern asia this relation provides evidence that differences in the strength of the upper mantle control the locus of intracontinental deformation

crustal temperature and mantle heat flow in europe abstract the map of the surface heat flow in europe was supplemented by the crustal thickness pattern and data on crustal radioactivity and transformed to the mantle moho heat flow distribution using a model of radioactivity decreasing exponentially with depth a z a 0 exp z d with a0 2 wm 3 and d 10km we computed generalized one dimensional steady state conductive temperature depth curves for the major tectonic units of europe the available information on the heat flow tectonic age heat flow heat generation and heat flow crustal thickness relationships were summarized and discussed in terms of crustal structure the mohorovicic discontinuity is clearly not an isothermal surface neither is the outflow of heat from the upper mantle constant but both parameters may vary within broad limits the moho temperature can be as low as 280 c in the shield areas however it can exceed 900 c in some young intrarnontane depressions or rift structures regional variations of the moho heat flow can be as large as 30 40 mwm 2 the value of the moho temperature reflects primarily the tectonic stabilization of the crust as a result of the deep seated processes in the upper mantle

the deep lithosphere in the alps a model inferred from p residuals abstract the tomographic studies of the alps and their surroundings based on the relative p residuals indicated two lithosphere roots attaining depths over 200 km separated by an upwelling of the lithosphere asthenosphere transition beneath the central part of this mountain range the directional dependence of relative p velocities indicates an anisotropic wave propagation in the subcrustal lithosphere beneath the alps and their surroundings the presented model of the deep lithosphere structure suggests several phases of the tectonic development of this region collision of a tip of the adriatic plate with europe in the eastern alps and dextral strike slip movement of the adriatic ending with underthrusting of europe beneath the western alps and counterclockwise rotation the latter contributes to a steep plunge of both plates beneath the eastern alps and to stress accumulation in the friuli region a model with delamination of the rigid upper crust and its rotation resolves some of the inconsistencies between the near surface and deep tectonics and also explains the distribution of seismicity

3 d gravity analysis of the dniepr donets basin and donbas foldbelt ukraine abstract the dniepr donets basin ddb is a linear nw se trending late palaeozoic and younger sedimentary basin on the east european platform separating the ukrainian shield from the voronezh massif its northwestern dniepr segment has the characteristics of a typical rift basin to the southeast through a transition zone of approximately 200 km length the ddb is progressively uplifted and compressionally deformed into the correlatable donbas foldbelt df along the axis of the dniepr segment a series of gravity highs has been previously explained by high density crystalline crust beneath the axis of the basin caused by intrusion of mafic and ultramafic rocks in this paper the results of a 3 d gravity analysis using a gravity backstripping technique is described that investigates the crustal and upper mantle structure in the region of the ddb df transition zone and df a residual gravity field i obtained by subtracting the gravity influence of the sedimentary succession of the ddb from the observed field reveals a distinct positive anomaly along the axis of the rift basin increasing in amplitude to the southeast in concert with increasing sedimentary thickness a residual gravity field ii derived by removing the gravity effects of a modelled homogeneous crystalline crust from residual field i reaches 200 and 100 mgal amplitude in the df for two respective moho models based on different interpretations of the published crust and upper mantle seismic velocity models the first of these model a assumes crustal thickening beneath the transition zone and df to a moho depth up to 50 km whereas the second model b assumes a moho shallowing to depths in the range 35 37 km along the whole basin axis for each residual anomaly ii the best fitting 3 d distribution of average density in the crystalline crust has been computed both models indicate the existence of a high density body in the crystalline crust along the ddb axis increasing in density from the dniepr segment to the df with higher average crustal density required in the case of moho model a 3 17 103 kg m 3 versus 3 06 103 kg m 3 for model b the preferred interpretation of the density models is one in which the denser crystalline crust underlying the ddb df transition zone and df is explained by intrusion of mafic and ultramafic rocks during late palaeozoic rifting processes invocation of processes related to the uplift and inversion in the df are not required to explain the observed gravity field although reworking of the crust during permian and younger tectonism in the df cannot be ruled out

the calabrian arc and the ionian sea in the dynamic evolution of the central mediterranean in the central mediterranean area it is possible to recognize three main realms the tyrrhenian sea the pelagian block and the ionian block these domains are limited by important fracture zones that are easily recognizable on land and offshore these fracture zones can be grouped into four main trends 1 the nw se trend which is characterized by dextral horizontal movements 2 the ne sw trend which is generally characterized by sinistral lateral horizontal movements 3 the e w trend which also shows dextral shear movements and 4 the n s trend which is characterized by normal faults only the tyrrhenian sea realm is characterized by a thinned crust of oceanic type and is connected to the apenninic chain by means of listric faults from a geophysical point of view the area shows a high heat flow which follows the main structural trends and positive gravimetric anomalies which are compatible with seismic refraction data and can be explained by the proposed model the pelagian block shows a continental crust about 20 km thick which progressively increases beneath the sicilian chain here an abrupt interruption with the tyrrhenian block takes place in the pelagian realm rifting processes developed according to the nw se and n s trend the n s trend characterizes the westernmost zone of the realm where volcanic processes and a relatively high heat flow can also be observed the ionian block is characterized by the following a thinned crust 17 20 km which increases 40 km towards the southern calabrian chain a thick sedimentary sequence high positive bouguer anomalies 300 mgal and very low heat flow 50 mw m 2 geophysical and structural analyses allowed us to evaluate the post tortonian evolution of the whole area under consideration this evolution resulted in continental crust formation according to a rigid plastic deformation model according to our model the ionian block can be considered as a domain characterized by a thinned continental crust and affected by intrusive material derived from the upper mantle furthermore this domain of probably jurassic age can be considered as a pelagic basin bordered by the pelagian block to the west and by the apulian block to the east northeast this basin according to its position with respect to the apenninic and sicilian chains has not been affected by tectogenesis and still represents a site of continuous sedimentation from a kinematic point of view the ionian realm can be linked with the pelagian block shifting towards the east northeast whereas it is limited towards the north by an e w fracture zone which regulates the opening of the tyrrhenian sea and the counterclockwise rotation of the apenninic chain according to the proposed model the opening of the tyrrhenian sea can be considered as a megaextension fracture which developed parallel to the maximum principal stress direction and evolved as a triangular shaped structural feature in preparing the model the authors have taken into account a large set of data collected both on land and offshore

dissolved rare earth elements in the southern ocean cerium oxidation and the influence of hydrography abstract analysis of dissolved ree distributions in the southeastern atlantic ocean has revealed that progressive oxidative removal of dissolved ce from deepwater 1 km occurs over the mixing time of the oceans ce anomaly ce ce values measured in deep waters from the southeastern atlantic are similar to but slightly higher than those from deep ocean stations throughout the indian and pacific oceans typically falling in the range 0 08ce ce 0 12 only deepwater samples from the north atlantic exhibit values greater than ce ce 0 12 with the exception of southeastern atlantic bottomwaters which are influenced by antarctic bottomwater covariation of dissolved ree concentrations with salinity and or dissolved si concentrations at this site has allowed dissolved ree compositions for various southern ocean water masses to be predicted end member concentrations for antarctic bottom water aabw derived in this way indicate high dissolved ree concentrations similar to average pacific deep water but with significantly enhanced dissolved ce concentrations and less pronounced hree enrichment this result is consistent with the proximity of our study site to active aabw deepwater formation and evolution of that water mass during transport to the pacific ocean

density inhomogeneities of the upper mantle of the central balkans summary a 3 d density model was created for the central balkans area down to a depth of 670 km on the basis of seismic both artificial sources and earthquakes and gravity data this model is based on density columns constructed for the main geological units of the study region the densities for these columns were obtained using the density variation method this method makes it possible to extrapolate the density distribution from the well studied uppermost layers to the deeper levels of the earth the constructed 3 d density model was interpreted in relation to the available data on the heat flow and the seismicity of the region the subdivision of the region by the maritza fault into two parts the southern part including the rhodope massif and the northern part including the structures of alpine activation of srednogorie and the balkanides was confirmed the upraised position of the 400 km boundary within the upper mantle which was established from the density modelling is assumed to be a sign of development of recent geodynamical processes over the srednogorie block from the viewpoint of seismicity prediction a finding of mantle inhomogeneities orthogonal to the maritza suture is of great importance

crustal structure in the carpatho pannonian region insights from three dimensional gravity modelling and their geodynamic significance a three dimensional gravity modelling of the carpatho pannonian region was carried out to get a better image of the moho boundary and the most prominent intra crustal density heterogeneities at first only the major density boundaries were considered the bottom of the tertiary basin fill the moho discontinuity and the lithosphere to asthenosphere boundary density contrasts were represented by relative densities the improved density model shows a transitional unit of high density at the base of the crust along the teisseyre tornquist zone in the western carpathians an extensive relatively low density unit was inferred in mid crustal levels the border zone between the southern carpathians and the transylvanian basin is characterized by a sharp step like contact of the two crustal units the moho configuration reveals important information on the tectonic evolution of the region zones of continental collision are represented by thick moho roots eastern alps eastern carpathians transpressional orogenic segments however are different in the western carpathians the moho is a flat surface in the dinarides a medium moho root is observed the southern carpathians are characterized by a thick crustal root the differences are explained with the presence or absence of subductible oceanic crust along the carpathians during the extrusion of pannonian blocks

properties of the lithosphere in collisional belts in the mediterranean a review abstract a brief review of the lithosphere asthenosphere properties is given for the mediterranean area the strongest lateral heterogeneities are found in the proximity of tectonically active areas such as collisional belts high s wave velocities below about 70 km denote the presence of deep seated almost aseismic lithospheric roots under the western alps the north central apennines and the cordillera betica an alternative explanation of the data related to mechanisms of intermediate and deep focus earthquakes in the tyrrhenian sea and aegean sea is discussed in the frame of the dynamic subduction model proposed by freund et al 1980 which postulates that the slab is disrupted in blocks and pulled down gravitationally

clay mineral accumulation rates in the arabian sea during the late quaternary abstract the regional variations in clay mineral concentrations in 39 turbidite free and undisturbed deep sea sediment cores from the arabian sea are compared with distribution patterns of clay mineral accumulation rates during the holocene and the last glaciation dust plumes from the red sea area arabia mesopotamia iran and pakistan can be traced by accumulation rates of mineral specific dust loads during the late quaternary the major proportions of aeolo marine sediments in the western arabian sea were derived from arabia during the summer season the clay mineral assemblage in these dust plumes consists of illite smectite kaolinite chlorite and palygorskite in decreasing order of abundance the distribution pattern of palygorskite in particular reveals that dust transport from southern arabia occurs mainly with northwesterly to westerly winds in the mid troposphere dust plumes from iran and pakistan which are characterized by high chlorite content are dispersed by northwesterly winds over the northwestern arabian sea dust contributions from the red sea area which are rich in smectite and characterized by the occurrence of amphiboles are transported to the gulf of aden the amount of dust related to northeast monsoon winds during the winter season appears to be negligible when compared to the proportions borne on other dust bearing winds in addition to aeolian contributions we distinguish two fluvial contributions a chlorite illite kaolinite and quartz rich assemblage from oman and pakistan into the gulf of oman and a smectite rich assemblage which is dominant off southern india originating from rivers that drain the indian subcontinent the significant difference between the holocene and glacial accumulation rates of wind transported clay minerals consist in the higher abundance of quartz illite and chlorite in the northwestern arabian sea during the last glaciation this pattern indicates intensified dust contributions by northwesterly winds from the persian gulf area which was dry during glacial times

amphibolite facies metamorphism in shear zones in the buchan area of ne scotland a major system of steep caledonian shear zones of regional extent has been identified in ne scotland the shear zones affect a wide range of lithologies including argyll and southern highland group dalradian younger basic intrusives and their hornfelses and also the earlier of the more acid intrusions the observed fabrics and parageneses are consistent with low pressure amphibolite facies metamorphism these shear zones represent a phase of movement which occurred in the 490 465 ma interval when ambient temperatures were still high and it is concluded that this is the principal control on the metamorphic grade achieved within the shear zones although local anomalies may exist

a three dimensional model of the crust and upper mantle along the alpine part of the european geotraverse egt abstract we investigated the structure of the crust and the upper mantle in the alpine part of the european geotraverse by integrating gravity and seismic refraction data into a three dimensional 3 d model of the crust the gravity data came from swiss italian and german sources the study area included the swiss molasse basin north of the alps and the po plain in the south to enhance the resolving power of this data for short wavelength anomalies in the alps 550 additional stations were surveyed on a 10 km wide swath from lake constance bordering switzerland and the federal republic of germany to bergamo italy the bouguer anomalies were reduced with 3 d models for the effect of the sediments of the swiss molasse basin the po plain and other bodies of known geometry such as the quaternary sediments of the alpine valleys and the mafic and ultramafic rocks of the ivrea body this resulted in a map of stripped bouguer anomalies a 3 d model of the crust was built using seismic data the densities were determined by a least squares inversion technique after subtraction of the model effect from the stripped bouguer anomalies we found a residual gravity anomaly of more than 400 km length that can be explained with a positive density anomaly in the upper mantle which is in agreement with seismological results these findings fit well into a tectonic model with subducted material of higher density and seismic velocity in the upper mantle beneath the boundary between the european plate and the adriatic promontory african plate

glacial isostasy and long term crustal movements in fennoscandia with respect to lithospheric and asthenospheric processes and properties abstract the last glacial loading unloading cycle gave rise to a crustal deformation today seen as an elliptic uplift cone centered over the fennoscandian baltic shield with a maximum uplift of 830 m in the center and a surrounding subsidence trough the mass flow took place in a low viscosity asthenosphere in the order of 1020 poise the flexural rigidity was high in the order of 1025 nm the present uplift represents a linear uplift factor that may be driven by phase boundary displacements and or readjustments in the low velocity zones within the lower lithosphere the long term crustal movements represent deformations of similar geometry and shape indicating a strong influence from the shape of the lithosphere the egt profiles provide new and independent observational data that seem to be in perfect agreement with those obtained from crustal movements the downwarping of the lithosphere explains the repetition of similar geometry and shape of the crustal deformations it also explains the high flexural rigidity established the recording of a low viscosity asthenosphere confirms the conclusions drawn from the uplift area the absence of deformation of the lower boundary of the asthenosphere indicates that the loading unloading was fully compensated within the asthenosphere by horizontal flow hence confirming the model of the glacial isostatic deformation of morner 1979a 1980a

upper mantle heterogeneities beneath central europe summary an inversion of isc travel time data from selected earthquakes in the distance range 30 90 to 53 stations in central europe has been used to model velocity down to 600 km depth the model explains 0 1 0 2s of the residuals as for other array studies leaving 0 5 s unexplained as noise the uppermost 100 km of the mantle and crust contains inhomogeneities that correlate remarkably well with the geology this may be due to deep seated thermal anomalies or in some areas to delays introduced by passage of the rays through sedimentary cover the deeper anomalies are smaller and unrelated to those in the lithosphere which suggests that the asthenosphere is decoupled from the rigid lithosphere the structure at 600 km depth is again quite inhomogeneous and might be due to undulations of the 650 km discontinuity the models show some suggestion of a high velocity slab trending from east to west beneath the alps

significance of primary hilltop loess in reconstructing dust chronology accretion rates and sources an example from the negev desert israel 1 although high latitude loess sequences have been studied extensively for reconstructing past climates loess in desert margins has been mostly overlooked moreover many low latitude loess studies have focused on secondary reworked sequences for which paleoclimatic inferences are complicated owing to postdepositional processes acting under local control in this respect the spatial distribution of the loess and its different types are crucial in this study we differentiate primary and secondary loess using remote sensing and field criteria we present remote sensing and geographic information system procedures for mapping loess distribution in general and for identifying pristine hilltop loess sequences in particular then we present the mineralogical and textural analyses combined with optically stimulated luminescence ages of one such primary hilltop loess sequence in the negev desert that show that the late pleistocene negev loess started accumulating at 95 ka much earlier than previously proposed 70 ka it was preceded by a previously unknown middle pleistocene period of loess formation at 180 130 ka the ages also suggest that the threshold of dust accretion rate needed for loess formation is 0 02 mm a 1 30 g m 2 a 1 a factor of 2 or more lower than previously thought 0 04 to 1 0 mm a 1 our results also provide insights into causes of late pleistocene loess accretion and its close association with regional dune field activity the methodology for mapping the loess distribution may potentially be generalized to help understanding loess formation in other more remote desert areas

the glen kyllachy granite and its bearing on the nature of the caledonian orogeny in scotland the tomatin findhorn granite in the nw grampian highlands has been separated into two distinct complexes a late tectonic glen kyllachy granite tectonically foliated and a post tectonic findhorn granite flow foliated for the glen kyllachy complex rb sr analyses of muscovites from the granite and from an associated suite of cross foliated pegmatites yield an emplacement age of 443 5 15 ma whole rock rb sr data support field and textural evidence that the pegmatite and granite emplacement was late tectonic to the last f3 phase of caledonian folding initial granite 87 sr 86 sr of 0 7176 supports field and geochemical evidence of derivation from upper crustal metasediments first metamorphosed during the grenville event for the findhorn granite concordant rb sr and k ar mineral data establish an age of 413 5 ma and an initial 87 sr 86 sr of c 0 706 indicates a lower crustal and or mantle source this age and isotopic contrast between these granites is characteristic of the whole grampian region in which a plutonic hiatus between c 440 and 415 ma coincides with the peak of sedimentary accretion in the southern uplands and may be explained in terms of the lack of hydrous materials passing down the associated subduction zone structural metamorphic and radiometric evidence suggests a that the late f3 glen kyllachy pegmatites are comparable with the 442 7 ma old syn f3 pegmatites in the n highlands both pegmatite suites are situated in the axial zone of the metamorphic caledonides displaced by the great glen fault and b that the caledonian c 454 ma old peak tectonic metamorphic event d2 previously documented in the n highlands coincides with a caradocian basin closure along the highland boundary fault for silurian events in the n highlands we propose a separate subduction history in this region the peak of calc alkaline plutonism was accompanied by continuous folding and westward thrusting at the same time as a plutonic hiatus in the grampian highlands current evidence suggests that the c 160 km or greater sinistral movements on the great glen fault were not initiated until late silurian early devonian time

strontium isotopic chemical and sedimentological evidence for the evolution of lake lisan and the dead sea precise strontium isotope ratios combined with chemical analyses and sedimentological information are used to monitor the water sources and the evolution of the dead sea and its late pleistocene precursor lake lisan 70 18 kyr b p the materials analyzed include bulk aragonite water leached soluble salts and residual aragonite and gypsum from the lisan formation in the perazim valley near the sw shore of the dead sea the residual aragonite and the associated soluble salts display systematic fluctuations in 17sr86sr ratios between 0 70803 and 0 70806 and from 0 70805 to 0 70807 respectively in individual soluble salt residual aragonite pairs the soluble salt displays a higher 87sr86sr ratio gypsum samples yield 17sr86sr ratios similar to the soluble salts from adjacent layers in the section this shows that in individual samples the source of sr in aragonite was distinct from that in soluble salts and the gypsum the sterility of the lisan sediments their strictly nonbioturbated fine lamination and their high content of chloride salts indicate that lake lisan was a saline or even hypersaline water body in the absence of alternative sources of hco3 and s042 the abundance of primary aragonite and gypsum in the lisan column reflects an import of very large volumes of freshwater into the otherwise saline lake resulting in a density stratification of this water body the history of the upper water layer and that of the lower brine is reflected in the chemical and strontium isotope composition of the aragonite and in that of the associated soluble salts and in the gypsum samples respectively whereas the bicarbonate and much of the ca2 required for aragonite crystallization were supplied by the freshwater the complementary ca2 and sr 2 were added by the lower brine the upper water layer of lake lisan acted as a so42 capacitor during the lake s rise periods it was removed therefrom as prominent gypsum beds upon climatic induced drier period mixing or even complete overturn of the lake the evolution of lake lisan took place between two distinct modes the first was characterized by an extensive supply of freshwater and resulted in a rise of the lake s level a density layered structure and precipitation of aragonite the second mode was marked by a diminishing freshwater input resulting in mixing or complete overturn of its water and precipitation of gypsum these two modes reflect the climatic evolution of the region in the late pleistocene which fluctuated between drier and wetter periods the transition to the holocene is accompanied by the dry up of lake lisan and its contraction to the present dead sea

large scale p velocity structures in the euro mediterranean area summary the 3 d velocity structure beneath the euro mediterranean domain is investigated down to 1200 km by using teleseismic p arrival times collected by the euro mediterranean seismological centre emsc in strasbourg the simultaneous iterative reconstruction technique sirt is used to invert the data while the direct problem is formulated by using a spherical block partition of the model space and an analytical ray tracing so that the whole ray path lies in the investigated 3 d model box only events located within epicentral distances of 30 70 are considered in this study after reviewing the sirt method a synthetic test has shown the reliability of the results for structures beneath the lithosphere while for shallower parts of the model and depths larger than 900 km limited reliability is achieved for the upper mantle the model shows clear correlations with major known surface tectonic features in particular a well marked sub vertical slab in the calabrian arc and the presence of a roughly north orientated slab in the aegean area at greater depths our model shows slow velocities around 600 km beneath the two main hercynian massifs in europe

rapid development of negative ce anomalies in surface waters and contrasting ree patterns in groundwaters associated with zn pb massive sulphide deposits ground and surface waters collected from two undisturbed zn pb massive sulphide deposits the halfmile lake and restigouche deposits and active mines in the bathurst mining camp bmc nb canada were analysed for the rare earth elements ree ree contents are highly variable in waters of the bmc with higher contents typical of waters with higher fe and lower ph there are significant differences between ground and surface waters and between groundwaters from different deposits the ree contents of surface waters are broadly similar within and between deposit areas although there are spatial variations reflecting differences in ph and redox conditions surface waters are characterised by strong negative ce anomalies ce ce nasc as low as 0 08 produced by oxidation of ce3 to ce4 and preferential removal of ce4 from solution upon leaving the shallow groundwater environment groundwaters and seeps typically lack significant ce anomalies reflecting generally more reducing conditions in the subsurface environment and indicating that ce oxidation is a rapid process in the surface waters deeper groundwaters at the halfmile lake deposit are characterised by ree patterns that are similar to the host lithologies whereas most groundwaters at the restigouche deposit have lree depleted patterns compared to nasc halfmile lake deposit groundwaters have generally lower ph values whereas restigouche deposit groundwaters show greater heavy ree complexation by carbonate ions shallow waters at the halfmile lake and stratmat main zone deposits have unusual patterns which reflect either the adsorption of light ree onto colloids and fracture zone minerals and or precipitation of ree phosphate minerals middle ree enrichment is typical for ground and surface waters and is highest for neutral ph waters the labile portion of stream sediments are generally more middle ree enriched than total sediment and surface waters indicating that the ree are removed from solution by adsorption to fe and mn oxyhydroxides in the order middle ree light ree heavy ree

lithospheric wedging in the western alps inferred from the ecors crop traverse the ecors crop traverse integrates vertical and wide angle seismic reflection gravity and magnetic studies along a 190 km profile across the western alps the combination of geophysical and geologic data constrains the deep structure along the traverse although alternative models are not excluded the model that best fits the data of crustal accretion implies that after the consumption of the piemontese ocean continental collision proceeded by lithospheric wedging of the subducting european continental foreland in the internal zones further shortening may have been achieved by an unknown amount of penetrative deformation and by back thrusting

short residence time and fast transport of fine detritus in the judean desert clues from 7be in settled dust 1 the cosmogenic isotope 7be t1 2 53 3d was measured in sediments collected from dust traps deployed in the judean desert which is part of the dead sea drainage basin the results show that a the 7be dry deposition flux in the dead sea region is 2 0 0 6 104 atoms cm 2 y 1 during summer and winter and 5 3 0 7 104 atoms cm 2 y 1 during fall b the residence time of dust in the dead sea drainage basin is less than one year c the recycled component of the cosmogenic isotope 10be t1 2 1 39 106y in judean desert dust is potentially small and d the 7be inventory atoms cm 2 in dust settled in the drainage basin did not reach steady state between consecutive rare events of desert winter floods suggesting a short transport rate of fine detritus material from the marginal terraces into the dead sea provided 10be behaves similarly as implied by the common geochemistry and cosmogenic origin of 7be and 10be we suggest 10be in lake lisan pleistocene dead sea detrital sediments as a potential proxy for paleo flood frequency and dust transport

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

geochemical characterization of contemporary fine detritus in the dead sea watershed abstract reconstruction of paleo synoptic conditions e g past atmospheric circulation involves tracing the origins and routes of transport of particles comprising eolian archives i e desert dust lacustrine deposits that accumulated in the quaternary lakes filling the dead sea basin include remobilized eolian desert dust that was washed to the lakes by floods here we analyze the mineralogical chemical compositions e g mg al ratios and 87sr 86sr and 143nd 144nd end values isotope ratios of fine siliciclastic particles that form the modern surface cover of the dead sea watershed e g loess mountain soils and flood particles that are mobilized to the lake during distinct synoptic conditions the data comprises reference data set that can be used for paleo synoptic interpretation enhancing our ability to decipher the paleoclimate history during the quaternary in the levant the end values and 87sr 86sr ratios of the fine detritus lie between 8 and 6 and 0 7035 to 0 7188 reflecting the values of erosional products of granitoids that are exposed in the sahara and arabia deserts and the unradiogenic sr from local soils in the dead sea watershed particles with low mg al ratios i e 0 17 0 31 are transported by the western winds associated with the mediterranean cyclones transporting dust from the sahara while particles with high mg al ratios 0 27 0 68 are associated with storms blowing dusts from east to the dead sea watershed saudi arabia and syrian deserts during red sea trough synoptic conditions fine particles blown from the sahara deserts during winter storms are rapidly washed to the lake by subsequent floods whereas the particles blown during dry storms associated with red sea trough synoptic conditions accumulate on the surface of the dead sea watershed and can be washed later to the lake during extensive rain events

geochemical and isotopic characterization of the bodele depression dust source and implications for transatlantic dust transport to the amazon basin the bodele depression chad in the central sahara sahel region of northern africa is the most important source of mineral dust to the atmosphere globally the bodele depression is purportedly the largest source of saharan dust reaching the amazon basin by transatlantic transport here we have undertaken a comprehensive study of surface sediments from the bodele depression and dust deposits chad niger in order to characterize geochemically and isotopically sr nd and pb isotopes this dust source and evaluate its importance in present and past african dust records we similarly analyzed sedimentary deposits from the amazonian lowlands in order to assess postulated accumulation of african mineral dust in the amazon basin as well as its possible impact in fertilizing the amazon rainforest our results identify distinct sources of different ages and provenance in the bodele depression versus the amazon basin effectively ruling out an origin for the amazonian deposits such as the belterra clay layer by long term deposition of bodele depression material similarly no evidence for contributions from other potential source areas is provided by existing isotope data sr nd on saharan dusts instead the composition of these amazonian deposits is entirely consistent with derivation from in situ weathering and erosion of the precambrian amazonian craton with little if any andean contribution in the amazon basin the mass accumulation rate of eolian dust is only around one third of the vertical erosion rate in shield areas suggesting that saharan dust is consumed by tropical weathering contributing nutrients and stimulating plant growth but never accumulates as such in the amazon basin the chemical and isotope compositions found in the bodele depression are varied at the local scale and have contrasting signatures in the silica rich dry lake bed sediments and in the calcium rich mixed diatomites and surrounding sand material this unexpected finding implies that the bodele depression material is not pre mixed at the source to provide a homogeneous source of dust rather different isotope signatures can be emitted depending on subtle vagaries of dust producing events our characterization of the bodele depression components indicate that the bodele calcium rich component identified here is most likely released via eolian processes of sand grain saltation and abrasion and may be significant in the overall global budget of dusts carried out by the harmattan low level jet during the winter

structure of the lithosphere below the southern margin of the east european craton ukraine and russia from gravity and seismic data abstract the present study was undertaken with the objective of deriving constraints from available geological and geophysical data for understanding the tectonic setting and processes controlling the evolution of the southern margin of the east european craton eec the study area includes the inverted southernmost part of the intracratonic dnieper donets basin ddb donbas foldbelt df its southeastern prolongation along the margin of the eec the sedimentary succession of the karpinsky swell ks the southwestern part of the peri caspian basin pcb and the scythian plate sp these structures are adjacent to a zone along which the crust was reworked and or accreted to the eec since the late palaeozoic in the bouguer gravity field the southern margin of the eec is marked by an arc of gravity highs correlating with uplifted palaeozoic rocks covered by thin mesozoic and younger sediments a three dimensional 3d gravity analysis has been carried out to investigate further the crustal structure of this area the sedimentary succession has been modelled as two heterogeneous layers mesozoic cenozoic and palaeozoic in the analysis the base of the sedimentary succession top of the crystalline precambrian basement lies at a depth up to 22 km in the pcb and df ks areas the residual gravity field obtained by subtracting the gravitational effect of the sedimentary succession from the observed gravity field reveals a distinct elongate zone of positive anomalies along the axis of the df ks with amplitudes of 100 140 mgal and an anomaly of 180 mgal in the pcb these anomalies are interpreted to reflect a heterogeneous lithosphere structure below the supracrustal sedimentary layers i e moho topography and or the existence of high density material in the crystalline crust and uppermost mantle previously published data support the existence of a high density body in the crystalline crust along the ddb axis including the df caused by an intrusion of mafic and ultramafic rocks during late palaeozoic rifting a reinterpretation of existing deep seismic sounding dss data on a profile crossing the central ks suggests that the nature of a high velocity density layer in the lower crust crust mantle transition zone is not the same as that of below the df rather than being a prolongation of the ddb df intracratonic rift zone the present analysis suggests that the ks comprises at least in part an accretionary zone between the eec and the sp formed after the palaeozoic

sources and transport routes of fine detritus material to the late quaternary dead sea basin abstract the sources and routes of transport of fine detritus material fdm to the lakes filling the late quaternary dead sea basin were studied by petrographic mineralogical grain size chemical and sr nd isotope analyses on sediments of the late quaternary lacustrine formations including river flood material dust and loess from the lake watershed the lacustrine formations comprise two sedimentary facies one that consists of alternating laminae of primary aragonite and silty detritus material aad facies and another that consists mainly of laminated detritus particles and generally lacks aragonite ld facies the aad facies characterizes the glacial intervals e g mis2 and 4 when lake levels were high while the ld facies characterizes interglacials e g mis1 5 and warmer glacial intervals e g mis3 when lake levels were low the detritus of both aad and ld facies show similar mineralogy mainly quartz and calcite grains with minor feldspars and clays but distinct grain sizes 8 10 m and 50 60 m respectively and distinct 87 sr 86 sr and end 0 711 0 712 and 7 to 8 versus 0 709 0 710 and 5 respectively the aad and ld fdm comprise desert dust of mixed granitic basaltic composition that was blown from the sahara desert and from the nile delta to the northern negev desert e g the loess deposits and the judean mountains bordering the dead sea basin mainly during glacial intervals along with enhanced mediterranean rain fronts the aad fdm reflects an enhanced transport of saharan granitic dust to the vicinity of the lake mainly during glacials the ld fdm was recycled from the loess surface cover of the negev desert mainly during interglacials and warm glacial intervals

clay distribution over the landscape of israel from the hyper arid to the mediterranean climate regimes abstract the current study evaluates clay distribution in modern surface sediments mainly soils to which desert dust is a major contributor the mineralogical composition of the clay fraction of seventy seven samples was analyzed by x ray diffraction twenty nine soil and dust samples were also analyzed for their bulk chemical composition the samples are settled dust soils developed on various sedimentary rocks stream and lake sediments they were collected along a climate gradient from hyper arid to mediterranean regimes in israel the purpose of the study is to decipher the main factors that control variable clay distribution along this gradient including annual precipitation substrate type and topography the common clay composition for most samples of all sources is illite smectite is kaolinite illite trace amounts of chlorite palygorskite goethite and quartz might be present pedogenic processes are recognized even under arid climate where loessial soils display kaolinite depletion and more illitic is phases than dust two main processes shape clay composition under a mediterranean climate regime regardless of the parent material a smectitization process occurs in leached low permeable clayey soils and reaches optimum evolution with 90 smectite or smectitic is this evolutionary trend is also recognized in poorly drained soils of catenary chains that are related to other soil types like terra rossa hamra and pale rendzina kaolinitization and apparently illite pedogenic formation occur in well drained red mediterranean soils of the terra rossa and hamra types to the detriment of smectitic is phases of parent materials in the most evolved terra rossa and hamra soils kaolinite becomes the principal mineral and illite is significantly enriched pedogenic evolution of the clay fraction mineralogical composition affects bulk chemical composition of most soil types clay inheritance from the bedrock is rather limited in leached soils it is widely recognized in pale rendzina soils by the presence of smectite or smectite and palygorskite derived from late cretaceous or eocene chalks respectively streams clay composition like that of dust is fairly uniform as streams average various sources across their drainage basins however composition variations can be attributed to local contribution from certain sources

models for the tectonothermal evolution of the eastern dalradian of scotland the preserved array of pressures in the eastern dalradian indicates that considerable syn to post metamorphic differential uplift has occurred this inferred differential uplift suggests that buchan sillimanite zone rocks originally lay at higher structural levels than presently adjacent cooler kyanite zone rocks to the west a number of features are believed to coincide with the western margin of the sillimanite zone these are a maximum in temperature sharp thermal features a high strain zone and a train of metabasites these features are explained by invoking syn metamorphic movement between the buchan sillimanite zone and the kyanite zone to its west involving some horizontal component of movement it is suggested that the lateral now eroded equivalents of the buchan area once provided part of the required tectonic thickening for other parts of the dalradian areas surrounding the buchan area suffered tectonic burial followed by metamorphism during uplift relative to the buchan area

mineralogical and chemical variability of mountain red brown mediterranean soils the purpose of the current study was to quantitatively explore the dynamics of clay pedogenesis in red brown soils of the terra rossa type and associated soils mainly rhodoxeralfs of the mediterranean region with respect to bedrock and dust composition and the impact of the vegetation translocated elements silicon and potassium fifteen non cultivated shallow and leached mountain pedons were sampled in israel along three transects that represent various rainfall ranges and bedrock lithologies bulk and clay fraction chemical and mineralogical compositions as well as grain size were determined quantitative relative analysis of clay minerals displayed a large variability that was largely affected by leaching leaching was dependent on rainfall amount and bedrock soil permeability in general if the better soils were drained and leached the higher were the amounts of both kaolinite and illitic phases soil clay assemblages lay between two mineralogical end members one with dominance of smectite and the second with high values of kaolinite and illitization parameters potassium and silicon were mobile in soils relative to aluminum but under high rainfall or certain vegetation translocation by vegetation reached a degree that promoted illite or smectite formation local combinations of rainfall bedrock soil permeability and vegetation translocation of potassium and silicon dictated a large variability in clays including illite formation within a restricted group of red brown mediterranean soils

the sharav cyclone observations and some theoretical considerations a special study of the sharav cyclones indicates that they are the result of large scale weak baroclinicity enhanced by vigorous boundary layer baroclinicity between the north african coast and the mediterranean it is illustrated how the jet stream plays a major role in the vertical circulation in producing a complex cyclonic circulation dominated by at least three mechanisms large scale interior baroclinicity boundary layer baroclinicity and jet stream related circulations the main characteristics of the sharav cyclone also called the saharan depression or khamsin depression in the mediterranean are reviewed unlike the cold winter cyclone the sharav cyclone is a spring cyclone its tracks lie mainly along the north african coast and turn to the north near the southeastern mediterranean its warm front is active and is sometimes associated with extremely high surface temperatures its cold front is shallow the sharav cyclone moves eastward relatively fast typically faster than 10 m s 1 and with a small speed variability in general there is an upper level trough to the west of the surface low and the surface horizontal scale is of the order of 500 1000 km finally it is frequently associated with heavy dust sand storms and low visibilities some of these features are illustrated in a case study of the april 28 30 1986 cyclone vertical cross sections indicate a deep circulation associated with the exit region of an upper level jet in addition to presenting evidence that the sharav cyclone is a deep tropospheric circulation it is shown that the transverse indirect circulation at the exit region of the jet is a major component of its circulation the classic two level baroclinic model phillips 1954 is applied the effects of the major diabatic heating due to the sensible heat flux above the north african desert and the large north to south temperature gradients are incorporated through the thermal wind of the basic state the model predicts the fast eastward motion the relatively smaller horizontal scale and the fast growth rate furthermore the model predicts an annual maximum growth rate in april and a secondary peak in october which agrees with the frequency of occurrences of the sharav cyclones

uplift patterns and orogenic evolution in the scottish dalradian rb sr and k ar mineral ages from the dalradian rocks of angus and perthshire indicate considerable diachronism of cooling following the caledonian regional metamorphism the oldest mineral ages 515 ma are similar to the independent estimates of peak metamorphic age and hence indicate very rapid cooling they occur in the highest grade samples of the angus region and are associated with localized uplift regional rapid uplift events at 460 440 ma and 410 390 ma may also be recognized and correlated with structural and igneous activity and metamorphic age dates within the scottish highlands thermal models show the importance of localized and discontinuous uplift in determining both the timing of metamorphism and the shape of the p t paths they suggest that the major diachronous metamorphism and granite production in the scottish highlands is depth controlled rather than representing major lateral diachronism of thickening or heat sources localized uplift may exercise considerable control on mineral facies variation within orogenic belts the local uplift in angus introduces hot high pressure tarfside nappe rocks into higher level tay nappe rocks thus the uniform block uplift models frequently used in the interpretation of metamorphic and structural phenomena in orogenic belts are an oversimplification of the real events

3 d density model for the lithosphere of europe construction method and preliminary results summary a map of the observed gravity field of europe has been constructed by averaging anomalies on a 1 x 1 grid in a combined reduction of bouguer anomalies on land and free air anomalies offshore on the basis of the observed gravity field and recent seismic data on crustal structure a 3 d density model for the lithosphere of europe has been calculated the model is represented by two complementary parts each obtained by its own specific method for the south of eastern europe the 3 d density model of the earth s crust comprising the sedimentary cover and three layers within the crystalline crust upper intermediate and lower crust was obtained by the following procedure 1 the velocity model was transformed into a density distribution using the velocity density relation 2 the gravity field of this density distribution was calculated by solving the 3 d direct gravity problem 3 the residual gravity field was obtained by subtracting the total gravity effect of the model and the regional component from the oberved gravity field 4 the isostatic equilibrium of the model was evaluated 5 in accordance with the residual anomalies and isostasy estimates some changes mainly in density distribution within the sedimentary cover were entered into the initial density model and the final version of the density model was obtained for the consolidated crust as well as for areas with density inhomogeneities within the upper mantle the correlation between moho traveltimes and crustal gravity influence obtained from the results of 3 d modelling for the south of eastern europe supplemented by 2 d modelling data available over western europe makes it possible to estimate without solving the direct gravity problem the crustal gravity field for the whole european continent residual anomalies due to subcrustal density inhomogeneities have been interpreted in the light of seismic tomography and heat flow distribution for both parts of the model geological and geodynamical interpretations of the results have been made in particular differences in the deep structure of the two major geoblocks of the continent the west and east european platforms have been confirmed regions of relatively light upper mantle have been outlined beneath the east and north west of the east european platform while a heavier upper mantle has been distinguished below the alps the caucasus and the calabrian arc as well as under the south caspian depression

lithosphere structure of european sedimentary basins from regional three dimensional gravity modelling abstract a three dimensional 3d density model approximated by two regional layers the sedimentary cover and the crystalline crust offshore a sea water layer was added has been constructed in 1 averaging for the whole european continent the crustal model is based on simplified velocity model represented by structure maps for main seismic horizons the seismic basement and the moho boundary laterally varying average density is assumed inside the model layers residual gravity anomalies obtained by subtraction of the crustal gravity effect from the observed field characterize the density heterogeneities in the upper mantle mantle anomalies are shown to correlate with the upper mantle velocity inhomogeneities revealed from seismic tomography data and geothermal data considering the type of mantle anomaly specific features of the evolution and type of isostatic compensation the sedimentary basins in europe may be related into some groups deep sedimentary basins located in the east european platform and its northern and eastern margins peri caspian dnieper donets barents sea basins fore ural trough with no significant mantle anomalies basins located on the activated thin crust of variscan western europe and mediterranean area with negative mantle anomalies of 150 to 200 10 5 ms 2 amplitude and the basins associated with suture zones at the western and southern margins of the east european platform polish trough south caspian basin characterized by positive mantle anomalies of 50 150 10 5 ms 2 magnitude an analysis of the main features of the lithosphere structure of the basins in europe and type of the compensation has been carried out

palaeomagnetic resetting in the barrovian zones of scotland and its relationship to the late structural history the haematite schists in the lowest kyanite and the staurolite barrovian zones exposed in glen lethnot and glen esk angus scotland have a characteristic magnetization with blocking temperatures generally greater than 600 c and less than 695 c and coercivity greater than 200 mt the mean palaeomagnetic direction derived from 54 samples collected from n 10 sites isd 159 i 45 k 47 95 7 1 with the associated south pole position oflat 3 long 22 e dp 5 7 anddm 9 0 this magnetization is younger than folds of d3 generation and older than folds of d4 generation the pole position falls on the aberdeenshire polar wander track in a place consistent with an average kar biotite chrontour age of 455 m y a comparison of the blocking temperatures of magnetization to the estimated peak temperature of metamorphism suggest the magnetization is a chemical remanent magnetization crm possibly acquired during the metamorphic chemical reactions

modelling of sedimentary basins from gravity anomalies with variable density contrast summary the decrease of density contrast with depth in sedimentary basins could be approximated by a quadratic function the sedimentary basin is viewed as a number of outcropping vertical prisms put in juxtaposition at each observation point equations are derived for the gravity anomaly of a vertical prism for a quadratic density function the initial model is obtained by calculating the thicknesses of the prisms at each station by an infinite slab formula the differences between the observed anomalies and the anomalies of the initial model at each station are used to modify the initial model a computer program is developed for initial estimates and refinement of the model the method is applied to interpret the gravity anomaly of san jacinto graben california where sediments filling the graben have a density contrast that can be approximated to a quadratic function finally the convergence of the method is discussed

the significance of a reliable ordovician age for some highland border rocks in central scotland a lower arenig fauna with north american affinities has been rediscovered at dounans aberfoyle central scotland this discovery makes part of the highland border complex younger than the adjacent dalradian rocks and suggests a provenance from the s

how mineralogy and slope aspect affect ree release and fractionation during shale weathering in the susquehanna shale hills critical zone observatory abstract to understand the factors that control rare earth elements ree release and fractionation during shale weathering we investigate the ree contents in solid bedrock regolith stream sediments and natural waters stream and pore waters from a first order catchment developed entirely on gray shales in central pennsylvania usa up to 65 of the ree relative to parent bedrock is depleted from the weathering profiles in the acidic and organic rich soils due to chemical leaching in addition newly formed fine particles were also lost along with the down slope movement of soil waters weathering profiles on the south facing slope show less depletion of ree than those on the north facing slope 33 vs 45 on average we hypothesize that the different degrees of ree depletion on the two transects reflect a history of different chemical weathering rates and possible different surface erosion rates controlled by contrasting slope aspect induced microclimate conditions in addition weathering profiles natural waters and sequential extractions all show a preferential removal of middle ree up to 22 more relative to light ree and heavy ree during shale weathering due to preferential release of mree from rhabdophane furthermore the long term phosphate mineral dissolution rates e g rhabdophane were estimated at 10 15 to 10 14 mol m 2 s 1 under field conditions based on ree depletion profiles strong positive ce anomalies average ce ce n value 1 79 observed in the regolith stream sediments and regolith extractions point to the fractionation and preferential precipitation of ce as compared to other ree due to the generally oxidizing conditions during release transport and redistribution of ree in the surface and subsurface environments positive eu anomalies average eu eu n value 1 30 observed in the natural waters of the catchment are attributed to weathering of plagioclases in the shale bedrock this study highlights the use of ree as natural tracers for low temperature geochemical processes

deep structure of the alps what do we really know abstract in the last five decades the deep structure of the alps has been probed by every geophysical method applicable and the resulting amount of data is unmatched for any other orogen in this study an attempt is made to review the data and the proposed structural models with the aim of separating the certain from the probable and from the speculative information this can be achieved by first reviewing the theoretical resolving power and ambiguity of the applied interpretation methods and then analysing the proposed models the methods reviewed are inversion of surface wave data teleseismic and local earthquake seismic tomography near vertical reflection seismology wide angle reflection and refraction seismology and gravity modelling all information about the moho rated as certain is combined to give a moho map of the alpine area the information rated as certain and probable and additional qualitative arguments are used to discuss a crustal model of the western and central alps represented by two cross sections major structural elements in this crustal model are a thick overthrust penninic nappe system wedging at mid to lower crustal levels a discontinuous moho and strong variations along the strike of the orogen whereas the structures of the european upper crust and of the penninic nappe system are well constrained only few and isolated lower crustal structural elements are rated as certain finally the shape of the lower lithosphere in the alps is discussed by review and comparison of the results from surface wave teleseismic travel time residual and tomographic studies qualitative arguments suggest the existence of a lithospheric root or slab beneath the alps probable tomographic information suggests a south vergent european lithospheric slab beneath the southern alps and the po plain despite the considerable number of studies aimed at resolving the deepest part of alpine orogeny the available quantitative information on the sub moho structure cannot be rated as certain