mapping upper mantle anisotropy beneath se france by sks splitting indicates neogene asthenospheric flow induced by apenninic slab roll back and deflected by the deep alpine roots the presence of two regional seismic networks in southeastern france provides us high quality data to investigate upper mantle flow by measuring the splitting of teleseismic shear waves induced by seismic anisotropy the 10 three component and broadband stations installed in corsica provence and western alps efficiently complete the geographic coverage of anisotropy measurements performed in southern france using temporary experiments deployed on geodynamic targets such as the pyrenees and the massif central teleseismic shear waves mainly sks and skks are used to determine the splitting parameters the fast polarization direction and the delay time delay times ranging between 1 0 and 1 5 s have been observed at most sites but some larger delay times above 2 0 s have been observed at some stations such as in northern alps or corsica suggesting the presence of high strain zones in the upper mantle the azimuths of the fast split shear waves define a simple and smooth pattern trending homogeneously wnw ese in the nice area and progressively rotating to nw se and to ns for stations located further north in the alps this pattern is in continuity with the measurements performed in the southern massif central and could be related to a large asthenospheric flow induced by the rotation of the corsica sardinia lithospheric block and the retreat of the apenninic slab we show that seismic anisotropy nicely maps the route of the slab from the initial rifting phase along the gulf of lion 30 22 ma to the drifting of the corsica sardinia lithospheric block accompanied by the creation of new oceanic lithosphere in the liguro provencal basin 22 17 ma in the external and internal alps the pattern of the azimuth of the fast split waves follows the bend of the alpine arc we propose that the mantle flow beneath this area could be influenced or perhaps controlled by the alpine deep penetrative structures and that the alpine lithospheric roots may have deflected part of the horizontal asthenospheric flow around its southernmost tip

two phase orogenic convergence in the external and internal sw alps the nw se trending sector of the sw alps includes the dora maira massif where tertiary eclogites record ultrahigh pressures and rapid exhumation along a ne sw crustal cross section italy france compiled pressure temperature time data in internal zones are correlated with tertiary stratigraphy in external zones to reconstruct orogen evolution revealing a coherent two phase convergence history during the first subduction accretion phase eocene 55 34 ma rapid north south plate convergence caused the subduction and exhumation of high pressure and ultrahigh pressure uhp rocks in a steady state subduction channel this coincided with the north to nnw migration of an underfilled flexural basin across the european foreland nappe stacking within the subduction channel did not create significant relief implying that primarily subduction forces generated this flexural basin from 34 ma onward the second collisional phase was characterized by slower nw se plate convergence the internal units of the sw alps underwent considerable anticlockwise rotation as they became involved in a nw se oriented sinistral transpression zone between the european and adriatic plates to the north of the orogen the north alpine foreland basin became overfilled as a result of high sediment supply from increasing orogen relief in contrast in se france active flexure of the european plate appears to have ceased and sedimentation became limited to small thrust sheet top basins created by continuing gentle ne sw shortening internal units were exhumed slowly from depths of c 20 km principally by erosion in the sw alps the transition between these two phases was marked by the rapid subduction and exhumation of the dora maira uhp unit assuming lithostatic pressure this unit would have been exhumed from 100 km depth requiring a rate that exceeds that generated by plate convergence therefore either exhumation was accelerated by additional stresses locally generated by transpression slab breakoff or high density contrasts or more controversially the ultrahigh pressure occurred at a considerably shallower depth as a result of local overpressure

quantifying the eocene to pleistocene topographic evolution of the soutwestern alps france and italy we evaluate the topographic evolution of the southwestern alps using eocene to pleistocene pollen data combined with existing sedimentological petrographic and detrital geo and thermochronological data we report 32 new pollen analyses from 10 sites completed by an existing dataset of 83 samples from 14 localities situated across the southwestern alps including both the pro and the retro foreland basins the presence of microthermic tree pollen mainly abies picea indicates that this part of the mountain belt attained elevations over 1900 m as early as the oligocene inferred rapid surface uplift during the mid oligocene coincided with a previously documented brief phase of rapid erosional exhumation when maximum erosion rates may have reached values of up to 1 5 2km myr slower long term average exhumation rates of 0 3km myr since the late oligocene helped maintaining the high alpine topography of the southwestern alps until today the relative abundances of meso microthermic tree pollen cathaya cedrusand tsuga and microthermic tree pollen abies picea in the pro and retro foreland basin deposits indicate that the present day asymmetric topography with a relatively gentle western flank and steeper eastern flank was established early in the southwestern alps at least since

late tectonic and metamorphic evolution of the piedmont accretionary wedge queyras schistes lustres western alps evidences for tilting during alpine collision this paper addresses the contribution of extension in the upper crust during syncollisional exhumation of subducted material we present structural data based on the analysis of ductile brittle ductile and brittle deformation features in metapelitic schists and meta basalts from the schistes lustres nappe stack in the piedmont zone of the western alps to link the structures with synkinematic pressure and temperature estimates geothermobarometry was performed using fluid inclusion investigation in quartz together with temperature estimations based on metamorphic chlorite composition samples used for geothermobarometry were collected taking into account the structural framework within veins associated with extensional structures observed at the regional scale the early generation of veins associated with boudinage occurred at 415 345 c and 6 2 5 kbar and subsequent incipient normal faulting occurred at temperatures of 315 235 c and pressures 1 7 kbar the transition from ductile to brittle extension occurred between ca 27 ma and ca 10 ma these results indicate a continuous extension in the upper crust during exhumation and continuous deformation associated with regional scale tilting of the exhumed schistes lustres tectonic pile the extensional tectonic regime in greenschistfacies conditions remains active today in most of the internal alpine zones as the alpine collision continues

crustal seismic velocity structure near faial and pico islands azores from local earthquake tomography the azores archipelago portugal is located on an oceanic plateau in a geodynamic environment prone to intense seismic and volcanic activity in order to investigate the crustal structure in this region we have conducted a local earthquake tomography study in the area of the islands of faial pico and s jorge using data recorded in july 1998 the july 9th 1998 earthquake near faial island triggered an aftershock sequence of thousands of events that lasted for several months and were recorded by a total of 14 stations located on the three islands surrounding the epicentral area in the upper crustal layers consistency is seen between the tomographic results and the islands surface volcanic units beneath the faial central volcano a low vp b6 0 km s anomaly roughly located at 3 7 km depth suggests a connection to the plumbing system possibly the presence of a magma chamber in ne faial a high vp n6 3 km s body was found located at mid lower crust most likely an intrusion of gabbroic composition that is bordered by the registered seismic activity its shape suggesting a tectonic controlled mechanism the relocated hypocenters together with the overall analysis of the tomographic model suggest a tectonic segmentation of faial island the crustal thickness under the islands volcanic buildings of the faial pico area was estimated at around 14 km 2007 elsevier b v all rights reserved

comparison of elements of environmental concern in regular and reclaimed soils near abandoned coal mines ptolemais amynteon northern greece impact on wheat crops abstract a comparative study related to the concentrations of trace elements especially those of environmental concern occurring in regular and reclaimed soils on abandoned coal mines as well as on their respective wheat crops has been undertaken in the vicinity of ptolemais amynteon greece the aim was to assess the impact of land reclamation on the crops the results of elemental analysis show that the concentration of as is 1 5 to 1 7 times higher in the regular soils than in the reclaimed ones similarly co is 2 4 to 2 6 times higher cr is 1 7 to 2 8 times higher ni is 1 9 to3 1 times higher pb is 0 8 to 4 6 times higher and hg is equal to or 1 7 times higher cu cd and se have the same concentration in both kind of soils and mo and u are 1 7 to 2 0 times lower in the regular soils as compared to the reclaimed soils nevertheless all concentrations are within the reported range for regular soils moreover the concentrations of the studied elements in wheat grains harvested from both types of soils are approximately the same the reason for the uniform uptake of elements by the plants is the very low solubility of the elements in the soil solutions this is attributed to the high soil ph and the nature of the occurrence or bonding of the elements in soil minerals

a crustal scale cross section of the south western alps combining geophysical and geological imagery a geotransect across the south western alps from the pelvoux massif external french alps to the dora maira massif internal italian alps through the monviso ophiolitic complex was investigated in the framework of the geo france 3d alpes programme a new interpretative crustal scale section across the south western alps is proposed combining geological and geophysical 2d 3d data the apulian mantle i e the ivrea body might be divided into two rigid pieces separated by the downward prolongation of the penninic frontal thrust these mantle indenters drive the decoupling of the european crust beneath the high to ultra high pressure metamorphic nappes the deep structure results from the stacking of crustal slices extracted from the european lithosphere the proposed struc tural model provides a basis for discussing the evidence of the crustal scale partitioning of the current strain pattern as well as the location of the seismicity

3 d crustal structure along the north anatolian fault zone in north central anatolia revealed by local earthquake tomography summary 3 d p wave velocity structure and vp vs variations in the crust along the north anatolian fault zone nafz in north central anatolia were investigated by the inversion of local p and s wave traveltimes to gain a better understanding of the seismological characteristics of the region the 3 d local earthquake tomography inversions included 5444 p and 3200 s wave readings obtained from 168 well located earthquakes between 2006 january and 2008 may dense ray coverage yields good resolution particularly in the central part of the study area the 3 d vp and vp vs tomographic images reveal clear correlations with both the surface geology and significant tectonic units in the region we observed the lower limit of the seismogenic zone for north central anatolia at 15 km depth final earthquake locations display a distributed pattern throughout the study area with most of the earthquakes occurring on the major splays of the nafz rather than its master strand we identify three major high velocity blocks in the mid crust separated by the izmir ankara erzincan suture and interpret these blocks to be continental basement fragments that were accreted onto the margin following the closure of neo tethyan ocean these basement blocks may have in part influenced the rupture propagations of the historical 1939 1942 and 1943 earthquakes in addition large variations in the vp vs ratio in the mid crust were observed and have been correlated with the varying fluid contents of the existing lithologies and related tectonic structures

p wave velocity tomography from local earthquakes in western mexico in western mexico the subduction of the rivera and cocos plates beneath the north america plate has deformed and fragmented the overriding plate forming several structural rifts and crustal blocks to obtain a reliable subsurface image of the continental crust and uppermost mantle in this complex area we used p wave arrivals of local earthquakes along with the fast marching method tomography technique we followed an inversion scheme consisting of 1 the use of a high quality earthquake catalog and corrected phase picks 2 the selection of earthquakes using a maximum location error threshold 3 the estimation of an improved 1 d reference velocity model and 4 the use of checkerboard testing to determine the optimum configuration of the velocity nodes and inversion parameters surprisingly the tomography results show a very simple vp distribution that can be described as being controlled by geologic structures formed during two stages of the separation of the rivera and cocos plates the earlier period represents the initial stages of the separation of the rivera and cocos plates beneath western mexico the later period represents the more advanced stage of rifting where the rivera and cocos plates had separated sufficiently to allow melt to accumulate below the colima volcanic complex during the earlier period 14 or 10 1 6 ma ne sw oriented structures lineaments such as the southern colima rift were formed as the two plates separated during the second period 1 6 ma to the present the deformation is attributed to magma generated within and above the tear zone between the rivera and cocos plates rising beneath the region of the colima volcanic complex the rising magma fractured the overlying crust forming a classic triple rift junction geometry this triple rift system is confined to the mid to lower crust perhaps indicating that this rifting process is still in an early stage this fracturing along with fluid circulation and associated heat advection within the fractures can easily explain the observed distribution of vp as well as many of the results of previous seismological studies also surprisingly we find no evidence at deep crustal depths to support either a trenchward migration of the volcanic arc or toroidal asthenospheric flow through the slab tears bounding the jalisco block to the nw and se

analysis of rock fall and rock fall avalanche seismograms in the french alps this study reviews seismograms from 10 rock fall events recorded between 1992 and 2001 by the permanent seismological network sismalp in the french alps a new seismic magnitude scale was defined which allowed us to compare and classify g round motion vibrations generated by these alpine rock falls each rock fall has also been cha racterized by its ground motion duration t30 at an epicentral distance of 30 km no relation was found between rock fall parameters fall height runout distance volume potential energy and rock fall s eismic magnitudes derived from seismogram amplitudes on the other hand the signal duration t30 shows a rough correlation with the potential energy and the runout distance highlighting the co ntrol of the propagation phase on the signal length the signal analysis suggests the existence of at le ast two distinct seismic sources one corresponding to the initial rupture associated with an elastic r ebound during the detachment and the other one generated by the rock impact on the slope although the fall phenomenon includes other complex processes fragmentation of the block interaction with topography plastic deformation during and after impact 2d finite element simulations of thes e two seismic sources are able to retrieve the main seismogram characteristics

geochemical controls on leaching of lignite fired combustion by products from greece abstract the mobility of inorganic pollutants is of key concern for a range of industrial and engineering applications of fly ash produced during the combustion of lignite in power generation this paper investigates the role that the geochemical features of lignite the ash composition and the partitioning of elements during combustion play in determining leaching properties of lignite fired by products the work is based on surveys on three lignite fired power plants in greece calcium rich ashes show a high abatement potential for so 2 and other gaseous pollutants for most elements the concentrations in the parent lignite and the ashes follow the same trend relative enrichments in cd co cr cu mo ni pb u v w zn fingerprint the regional and local geological settings of the lignite basins the total and leachable concentrations of highly volatile elements are strongly influenced by the interaction with ubiquitous free lime a broad array of elements is highly insoluble in alkaline ash while a few oxyanionic forming elements display substantial mobility their mode of occurrence in the parent lignite plays a primary role in the leaching of combustion ashes the outcomes of this study may assist in addressing the impact of co firing high ash or high ca alternative fuels on the leaching properties of combustion by products

use of laser ablation icp ms to determine trace element distributions in coals with special reference to v ge and al laser ablation icp ms has been used to produce element profiles from polished coal samples the elements analysed v ge ni cu zn sr and ba were those known to have an organic association with the addition of al and fe as controls on the clay and pyrite abundances the element profiles were compared with the petrography and a statistical analysis was also carried out sporinite was found to have low trace element concentrations inertinite higher concentrations of detrital elements and vitrinite higher concentrations of v ge and al the relationships between these elements are explored and all are thought to be present in the organic matter and not as minerals it is thought that these elements became concentrated during diagenesis with the possibility that some of the al could be residual the cu ni ratio in the pyrite is relatively constant suggesting constant ionic proportions during diagenesis and possibly a seawater source

first seismic evidence for continental subduction beneath the western alps the first discovery of ultrahigh pressure coesite in the european alps 30 years ago led to the inference that a positively buoyant continental crust can be subducted to mantle depth this had been considered impossible since the advent of the plate tectonics concepts although continental subduction is now widely accepted there remains debate because there is little direct geophysical evidence of a link between exhumed coesite at the surface and subducted continental crust at depth here we provide the first seismic evidence for continental crust at 75 km depth that is clearly connected with the european crust exactly along the transect where coesite was found at the surface our data also provide evidence for a thick suture zone with downward decreasing seismic velocities demonstrating that the european lower crust underthrusts the adriatic mantle these findings from one of the best preserved and long studied ultrahigh pressure orogens worldwide shed decisive new light on geodynamic processes along convergent continental margins

neogene to ongoing normal faulting in the inner western alps a major evolution of the late alpine tectonics 1 widespread brittle extension occurs in the internal zones of the southwestern alps forming a dense fault network which overprints the compressional structures the extension has been followed by transcurrent motions in terms of paleostress this extension is radial to the belt close to the crustal penninic front and multidirectional in the eastern part of the internal zones the paleostress field of the strike slip phase is coherent with the extensional one and compatible with dextral shear along longitudinal faults globally we propose that the internal zones of the southwestern alps underwent a single neogene transtensive tectonic regime to strengthen our structural results the current tectonics has been analyzed using seismotectonic tools this approach allowed the recognition of several active faults moreover the ongoing tectonics is coherent with the observed brittle deformation the fault network controls the present day seismicity the combined seismotectonic and structural approaches give coherency and continuity from the neogene to ongoing extensional tectonics in the southwestern alps in the framework of the whole western alps a synthesis of our results with neotectonic related data allowed us to provide an accurate map of the neogene to present kinematics of the belt extension which appears as a major feature of the internal zones has been coeval with the propagation of thrusts in the outer zones during neogene times the geodynamic processes which rule this major tectonic evolution of the belt remain a matter of debate

high resolution 3 d p wave model of the alpine crust summary the 3 d p wave velocity structure of the alpine crust has been determined from local earthquake tomography using a set of high quality traveltime data the application of an algorithm combining accurate phase picking with an automated quality assessment allowed the repicking of first arriving p phases from the original seismograms the quality and quantity of the repicked phase data used in this study allows the 3 d imaging of large parts of the alpine lithosphere between 0 and 60 km depth our model represents a major improvement in terms of reliability and resolution compared to any previous regional tomographic studies of the alpine crust first order anomalies like crust mantle boundary moho and the ivrea body in the western alps are well resolved and in good agreement with previous studies in addition several consistent small scale anomalies are visible in the tomographic image a clear continuation of the lower european crust beneath the adriatic moho in the central alps is not observed in our results the absence of such a signature may indicate the eclogitization of the subducted european lower crust in the central alps in agreement with previous results the additional analysis of focal depths in our new 3 d p wave model shows that all studied earthquakes in the northern foreland have occurred within the european crust waveforms and focal depths suggest that at least one of the analysed events south of the alps is located in the adriatic mantle

trace element contents in the domeniko lignite deposit elassona basin central greece abstract trace elements concentrations were determined in 38 lignite samples and their corresponding 850 c ash from two boreholes of the domeniko coal deposit upper miocene in elassona basin central greece the methods used were instrumental neutron activation analysis inaa inductively coupled plasma atomic emission spectroscopy icp aes and atomic absorption spectroscopy aas the results showed that all studied elements occur in concentrations within the range of reported values for different coal bearing basins of greece the elements u th cs eu ce la li mo y pb and hg are enriched in the ashes when compared to their average concentration on the earth s crust yb y lu th la sm eu ce and v showed positive r 0 75 to intermediate 0 65 r

the diffuse transition between the zagros continental collision and the makran oceanic subduction iran microearthquake seismicity and crustal structure summary the nature of the transition between the zagros intra continental collision and the makran oceanic subduction is a matter of debate either a major fault cutting the whole lithosphere or a more progressive transition associated with a shallow gently dipping fault restricted to the crust microearthquake seismicity located around the transition between the transition zone is restricted to the west of the jaz murian depression and the jiroft fault no shallow micro earthquakes seem to be related to the nnw sse trending zendan minab palami active fault system most of the shallow seismicity is related either to the zagros mountain belt located in the west or to the ns trending sabzevaran jiroft fault system located in the north the depth of microearthquakes increases northeastwards to an unusually deep value for the zagros of 40 km two dominant types of focal mechanisms are observed in this region low angle thrust faulting mostly restricted to the lower crust and strike slip at shallow depths both consistent with ns shortening the 3 d inversion of p traveltimes suggests a high velocity body dipping northeastwards to a depth of 25 km this high velocity body probably related to the lower crust is associated with the deepest earthquakes showing reverse faulting we propose that the transition between the zagros collision and the makran subduction is not a sharp lithospheric scale transform fault associated with the zendan minab palami fault system instead it is a progressive transition located in the lower crust the oblique collision results in partial partitioning between strike slip and shortening components within the shallow brittle crust because of the weakness of the pre existing zendan minab palami faults

present day vertical isostatic readjustment of the western alps revealed by numerical modelling and geodetic and seismotectonic data the active tectonics of the western alps reveals contrasting regimes ongoing extension at the heart of the chain and transpression compression at its external sectors the active processes currently affecting this region are still a matter of debate the classical models proposed in the literature invoke eurasia adria plate collision counterclockwise motion of the adria micro plate slab retreat of the subducted continental lithosphere and slab detachment more recently several authors prefer the hypothesis of tectonics driven by isostasy buoyancy forces to better understand the influence of these processes on the velocity strain and stress fields at the surface and in the crust we developed 2d viscoelastic numerical models along a vertical cross section perpendicular to the western alps we run our models with different driving forces in order to investigate one by one the geodynamic processes proposed in the literature results are compared with available geodetic geological and seismotectonic data in order to bring into coincidence model predictions and observations an important vertical isostatic readjustment must be included in the modelling together with a slight horizontal compression 0 5 mm year 1 probably due to africa eurasia convergence we show that the subduction process in this alpine region is likely to be dead and that buoyancy forces may be dominating the present day tectonics the geological society of london 2010

the geological significance of manganese distribution in jurassic cretaceous rocks of the pindos basin peloponnese greece abstract the jurassic mid cretaceous radiolarite series of the pindos zone of the peloponnese is a deep water sediment sequence it comprises jurassic red mudstones siliceous mudstones and ribbon bedded cherts and cretaceous red mudstones siliceous mudstones cherts calc turbidites and terrigenous turbidites bedded manganese ores occur both in cherty calc turbidites and ribbon bedded cherts in order to determine the origin of mn enrichment the transition element geochemistry and mineralogy has been determined for sediment samples from seven representative sections of the radiolarite series representing an along and across strike section of the pindos basin smectite and palygorskite are the principal clay minerals with lesser mica sepiolite and chlorite fe al ratios in jurassic rocks are close to values in continental detritus but increase upwards to the middle cretaceous nevertheless the association of volcanic rocks with jurassic sediments is circumstantial evidence that the minor mn enrichment is the result of hydrothermal processes the hypothesis that high fe al in cretaceous sediments is due to ophiolitic detritus is untenable in the peloponnese where sediment is derived from sources lacking ophiolites the fe enrichment must therefore result from hydrothermal processes which may be related to formation of oceanic crust in the pindos arvi zones mn concentrations are associated with diagenetic cherts at the top of calc turbidites in these settings mn correlates positively with ca and negatively with fe suggesting that the concentration of beds of ore is diagenetic

accurate time frequency wavenumber analysis to study coda waves summary an accurate method is developed to characterize the seismic coda phases recorded by smallaperture arrays the coda is modelled as a superposition of several interfering wavelets identified by their arrival time frequency content backazimuth and apparent velocity of propagation the wavelets are caused by the diffraction and refraction of the direct wavefield by heterogeneities of the propagation medium the deterministic modelling is different from the statistical one generally used to retrieve mean parameters of the medium as the complexity of the medium increases separation of interfering wavelets needs an accurate time frequency wavenumber decomposition method that consists of detection and characterization of the different coherent wavelets propagating through the array detection is realized by mean time frequency decomposition based on the ridges algorithm the multiple signal classification music algorithm allowing a higher separation of simultaneous wavelets in the wavenumber domain is then used to characterize the propagation parameters of the detected components an optimal use of the music algorithm assumes the knowledge of the number of sources that simultaneously propagate through the array the new iterative technique presented here allows the automatic determination of this number of sources this methodology is applied to synthetic signals simulated in a heterogeneous medium results obtained show that i the diffracted wavefield may be more energetic than the primary direct one and ii the relative energy diffracted by each heterogeneity is strongly dependent on the location of the array within the medium the well controlled results obtained for the synthetic examples allow interpretations of the observations made during the annot experiment in the southern french alps in 1998 where four small aperture arrays were deployed with small distances between each array 10 km the time azimuth velocity evolutions determined for the earthquakes recorded during this experiment are used to characterize the heterogeneous structures of the medium

local tomography and focal mechanisms in the south western alps comparison of methods and tectonic implications abstract we investigate how focal solutions and hypocenter locations may depend on the ray tracing algorithm and the strategy of velocity inversion using arrival times from a temporary seismological network in the south western alps a local earthquake tomography has been performed by paul et al paul a cattaneo m thouvenot f spallarossa d bethoux n and frechet j 2001 a three dimensional crustal velocity model of the south western alps from local earthquake tomography j geophys res 106 19367 19390 with the method developed by thurber thurber c h 1993 local earthquake tomography velocity and vp vs theory in seismic tomography theory and practice iyer h m and irahara eds chapman and hall new york 563 583 another inversion of the same data set is performed here using a different tomography code relying on a shooting paraxial method and cubic interpolation of velocities the resulting images display the same main features although thurber s code appears to be more robust in regions with scarce ray coverage and strong velocity contrasts concerning hypocenter location in piemont units one major result is the concentration of hypocenters at the boundary between the mantle wedge of the ivrea body and the european crust forty six focal mechanisms are shown that were computed using both the take off angles in the minimum 1 d model and in the 3 d velocity structures resulting from the two inversions the sets of focal solutions are very similar proving the reliability and the coherency of the focal solutions the widespread extension in the core of the western alps is confirmed whereas a few compressive solutions are found east of the piemont units these results constrain the sharp change of stress tensor and evidence a decoupling of strain beneath the east of dora maira massif up to beneath the north of argentera massif on a geodynamical point of view seismicity and focal mechanism distribution are compatible with the present day models published for the western alps where the major feature is the lithospheric thickening schmid s m and kissling e 2000 the arc of the western alps in the light of geophysical data on deep crustal structure tectonics 19 62 85 implying widespread extension in the core of the western alps sue c thouvenot f frechet j and tricart p 1999 widespread extension in the core of the western alps revealed by earthquake analysis j geophys res 104 25611 25622 however the existence of compressive events dealing at depth with the boundary of ivrea body allows to postulate that this geological structure is still tectonically active even if field work has not shown this so far the insubric line appears to extend toward the south at depth as a blind fault and to play a key role in the dynamics of the south western alps

concentration and mode of occurrence of trace elements in marine oil shale from the bilong co area northern tibet china abstract the bilong co oil shale zone is located in the south qiangtang depression this zone together with the shengli river changshe mountain oil shale zone in the north qiangtang depression northern tibet plateau represents a potentially large marine oil shale resource in china with the aim of better understanding geochemistry of marine oil shale 18 samples from the bilong co area are studied and 56 elements in them are determined the contents of mo se cd cs as bi u rb pb th li sr and zn are enriched from 1 3 to 35 0 times as compared with the average concentration in the crust clarke values whereas the other elements are slightly higher lower than the respective clarke values compared to common australian oil shales the contents of ce co cs f ga hf nb nd pb pr rb sc sn th and zr in the bilong co oil shale samples exhibit relatively high levels whereas as br cd cr cu dy er eu ho lu mo ni se tb tm u v y yb and zn are relatively depleted however the distribution patterns of trace elements are quite similar indicating that trace element speciation in oil shale is governed by general processes rather than by individual geochemical mechanisms within one particular sample the elements in the bilong co oil shale may be classified into three groups of association according to their modes of occurrence i e groups a b and c group a si al k na ti zr sc th sn nb ga ta be hf cs li rb ash rees is strongly correlated with ash yield and mainly has an inorganic affinity group b cr w mg mn br f sr ba has weakly or negatively positive correlation coefficients with an exception of f with ash yield group c zn bi cd ca fe pb hg co cu ni p mo se u as v shows negative correlation coefficients with ash yield with an exception of bi and possibly has an organic affinity

3 d modelling of alpine mohos in southwestern alps summary we present and discuss a 3 d geometrical model of the moho topography in the southwestern alps to achieve this objective we used the potential of 3 d modelling software i e a 3 d geomodeller to combine gravity seismic and seismological constraints in a same and coherent 3 d space a new regional bouguer gravity anomaly map of the southwestern alps was calculated and filtered to isolate the moho signature in the southwestern alps then two alternative 3 d models were computed with data from the literature based on seismic and seismological constraints the first one represents an european lithospheric mantle decoupled from the european orogenic crust which is back thrusted by the ivrea body whereas the second 3 d model illustrates the subduction of a 20 km thick piece of lower continental crust coupled with the european upper mantle beneath the ivrea body according to the geological knowledge of these units we then assigned a density value to each modelled layer and we computed their gravity effects to compare them with the filtered moho map of the southwestern alps first of all the significant discrepancies of the moho gravity signature generated by these two geometrical models reveal that subduction of continental crust is no more active in the present day configuration of the southwestern alps therefore the first 3 d model was refined by a stochastic 3 d gravity inversion based on this processing our investigations confirm the presence of three superposed mohos in the southwestern alps and underline that

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

three dimensional interface modelling with two dimensional seismic data the alpine crust mantle boundary summary we present a new approach to determine the 3 d topography and lateral continuity of seismic interfaces using 2 d derived controlled source seismic reflector data the aim of the approach is to give the simplest possible structure consistent with all reflector data and error estimates we define simplicity of seismic interfaces by the degree of interface continuity i e shortest length of ovsets and by the degree of interface roughness least surface roughness the method is applied to structural information of the crust mantle boundary moho obtained from over 250 controlled source seismic reflection and refraction profiles in the greater alpine region the reflected and refracted phases from the moho interface and their interpretation regarding crustal thickness are reviewed and their reliability weighted weights assigned to each reflector element are transformed to depth errors considering fresnel volumes the 2 d derived reflector elements are relocated in space 3 d migration and interpolation is performed between the observed reflector elements to obtain continuity of model parameters interface ovsets are introduced only where required according to the principle of simplicity the resulting 3 d model of the alpine crust mantle boundary shows two ovsets that divide the interface into a european an adriatic and a ligurian moho with the european moho subducting below the adriatic moho and with the adriatic moho underthrusting the ligurian moho each sub interface depicts the smoothest possible i e simplest surface fitting the reflector data within their assigned errors the results are consistent with previous studies for those regions with dense and reliable controlledsource seismic data the newly derived alpine moho interface however surpasses earlier studies by its lateral extent over an area of about 600 km by 600 km by quantifying reliability estimates along the interface and by obeying the principle of being consistently as simple as possible

a three dimensional crustal velocity model of the southwestern alps from local earthquake tomography a temporary network of 65 short period seismological stations was installed in the southwestern alps during the second half of 1996 it complemented the permanent monitoring networks obtaining an average interstation distance of 10 km travel time data from 446 local earthquakes and 104 quarry blasts were inverted simultaneously for hypocenter parameters and three dimensional velocity structure the p wave velocity model displays strong lateral contrasts both at shallow and deeper levels a low velocity anomaly stands out at shallow depths beneath the digne and castellane nappes in the southwestern part of the investigated area farther east the monviso ophiolitic massif appears to have a much larger extension at depth than previously assumed the largest and strongest anomaly is located under the dora maira massif and the westernmost po plain it correlates with the well known ivrea body which is classically interpreted as a wedge of adriatic upper mantle at the best resolved depths 10 and 15 km it appears as a rather thin 10 to 15 km north south elongated high velocity 7 4 to 7 7 km s 1 anomaly with very sharp edges extending to the south as far as 10 km north of the surface trace of the frontal penninic thrust special care was taken with regard to the quantitative estimation of the resolution for the main anomalies using the inversion of synthetic travel time data

widespread extension in the core of the western alps revealed by earthquake analysis the western alps are an active collision belt whose current stress field is inhomogeneous muller et al 1992 we report new seismological data which significantly improve our knowledge of this stress field about 1600 earthquakes which occurred in the western alps during the last 10 years were precisely located and 79 new focal solutions were computed the analysis of this database shows that widespread extension affects all the internal zones of the belt to better constrain the associated stress regime six stress tensors were computed using the gephart and forsyth 1984 method they show that the current tectonics of the western alps are contrasted with close variation in the stress regime transpression to the front of the belt contrasting with extension in the core of the belt the extensional direction is radial to the arcuate geometry of the belt and bounded outboard by the former thrust of the internal zones onto the external zone suggesting extensional reactivation of this inherited crustal discontinuity such widespread extension within the inner part of an actually ongoing collision belt cannot be explained by simple collision related tectonics we propose that intrabelt buoyancy forces such as those produced by a slab retreat or slab break off interfere with the boundary forces driven by the ongoing europe africa convergence

reliability of earthquake location procedures in heterogeneous areas synthetic tests in the south western alps italy abstract the accuracy of procedures for locating earthquakes and tomographically imaging 3 d velocity structures is influenced by factors such as network geometry errors in picking seismic phases modeling errors and velocity model uncertainties the main purpose of this study is to investigate the importance of different error sources through synthetic experiments the synthetic data sets were generated for a realistic 3 d velocity model of the south western alps adopting a precise raytracing technique the actual station configuration and recorded seismicity during the passive seismological experiment geofrance3d alps conducted between august 1996 and february 1997 were used the station configuration corresponded to an enhancement of the regional networks operating in the area with the addition of temporary stations in addition synthetic data sets were corrupted by applying different error schemes furthermore to assess the locating capabilities of the regional networks synthetic data sets were constructed for synthetic events placed in correspondence to the nodes of a regular three dimensional 3 d grid we mimicked the actual data management scheme for synthetic data processing we re located the earthquakes performed an inversion for a minimum 1 d velocity model with station corrections and then ran a complete 3 d velocity model inversion one of the main results confirming earlier studies was that earthquake locations in strongly heterogeneous areas obtained using a regional 1 d model can have significant errors even a minimum 1 d model with station corrections does not significantly improve the accuracy of parameter locations in the south western alps for high precision locations a 3 d model is needed however a 3 d model cannot be reconstructed from noise contaminated data recorded by a sparse regional network

moho depth and poisson s ratio in the western central alps from receiver functions summary current knowledge about deep crustal structure of the alpine orogen has mainly been derived from p wave velocity models obtained from active and passive seismic experiments a complementary s wave model to provide lithological constraints necessary for unique structural interpretation has been missing to date in this paper we present important new information on s wave velocity model in the alps we applied the receiver function method using 6 yr of high quality data from 61 permanent and temporary stations sampling the western central alps we determined first order crustal features moho depth h and average vp vs ratio with the h stacking technique that uses timing of direct and multiple p to s converted phases from the moho interface synthetic tests reveal a dipping moho interface expected beneath an orogen causes a systematic bias of h and potentially leading to misinterpretation we thus applied corrections determined from synthetic data to remove the bias providing better fit of recovered moho depths with active seismic estimates for each site we also obtained independent h and estimates based on the timing of the strong ps phase our results show a gently south southeast dipping european moho at a depth of 24 30 km beneath the northern alpine foreland steepening rapidly towards the europe africa suture zone to reach a maximum depth of 55 km south of the suture the moho of the adriatic crust promontory of the african plate is at 35 45 km depth in the previously ill constrained western alps we found the european moho at 30 km depth beneath the more external units dipping east northeast to reach 50 55 km in the inner core of the alps the poisson s ratio clearly correlates with the tectonic units that comprise the alps average crustal values in the european alpine foreland are close to 0 25 in the alps we observe low values 0 22 in the highly deformed nappes of the mesozoic helvetic and southern alps indicating a thickening of felsic upper crustal material in contrast the poisson s ratio is significantly higher 0 26 in the penninic and austroalpine units near the suture zone this rapid and significant change marks a clear rupture between the alpine forelands and the suture domain we assign this high poisson s ratio to doubling of mafic lower crust consistent with results from previous active seismic experiments a continuation of the lower crustal wedge into the central part of the western alps however seems unlikely based on low observed poisson s ratios

sequential inversion of local earthquake traveltimes and gravity anomaly the example of the western alps summary we present a joint analysis of gravity anomaly and seismic arrival time data recorded in the western alps seismological data were collected by a network of 126 permanent and temporary stations implemented in 1996 a set of 550 local events has been recorded gravity data result from the addition of two new gravity surveys to an existing data base a published velocity model obtained by local earthquake tomography let was used to construct an initial 3 d gravity model using a linear velocity density relationship birch s law while the synthetic bouguer anomaly field calculated for this model has the same shape and wavelength as the observed anomaly its amplitude is strongly underestimated to derive a crustal velocity density model that accounts for both types of observations we performed a sequential inversion of seismological and gravity data the variance reduction of the arrival time data for the final sequential model was comparable to the variance reduction obtained by simple let moreover the sequential model explained 90 per cent of the observed gravity anomaly the main features of our model compared with the let model are 1 an important broadening of the high velocity anomaly associated with the high velocity high density ivrea body 2 a 10 km thick low velocity zone beneath the nappes of digne and castellane and 3 a high velocity zone at more than 25 km depth under the internal zone of the range

seismotectonic investigations in the inner cottian alps italian western alps an integrated approach abstract this work integrates the results of recent geological structural studies with new seismological data for the inner cottian alps to investigate the connection between faults and seismicity the major post metamorphic tectonic feature of this sector is represented by a n s structure named lis trana deformation zone ltz since the late oligocene this structure accommodated right lateral late oligocene early miocene and subsequently normal post early miocene displacements in the pleistocene the activity of the ltz seems to have caused the development of lacustrine basins inside the valleys that drain this sector of western alps the present day seismicity joins the northern part of the ltz and southwards other minor sub parallel structures in transversal cross section hypocentres highlight steep surfaces focal mechanisms calculated along this structure show both extensional and strike slip solutions mostly with one roughly n s striking nodal plane both sub horizontal with ne sw to ene wsw trend and steeply dipping p axes with n s to nw se sub horizontal t axes are observed even if clear evidence of quaternary tectonic activity in the area is missing on the basis of the available seismological and geological data we propose that in the inner northern cottian alps the present day seismic activity may be connected to the ltz interpreted as minor sub parallel fault strand of the canavese line the kinematics of this structure is consistent with the focal mechanisms calculated in this area structural and seismological data indicate that ltz is active under a bulk dextral transtensive regime since the late oligocene in the inner cottian alps in agreement with the data published for the adjacent domain of the chain

geochemistry of terrestrial oil shale from the lunpola area northern tibet china abstract the lunpola oil shale is the largest oil shale resource in tibet twenty four samples of oil shale mudstone and dolomite were collected from the lunpola oil shale for mineralogical and trace element analyses the vertical distribution and mode of occurrence of trace elements in this terrestrial oil shale were also discussed oil shale samples from the lunpola area have high toc contents 5 1 10 6 high ash yields 74 8 84 7 low total sulfur contents 0 19 1 03 and high shale oil contents 5 0 10 3 the major minerals in the oil shale samples are clays quartz calcite and dolomite with minor quantities of feldspar siderite hematite magnesite and pyrite other minerals such as halite zeolite barite anhydrite and mirabilite were detected in some oil shale samples the contents of as ba be bi cd ce cs hg la li mo nd pb pr rb se sm th u w and zr are enriched from 1 30 to 125 times as compared to their average crust abundance clarke values whereas the other elements are slightly higher or lower than their respective clarke values compared to common australian oil shale the lunpola oil shales contain higher as ba be ce co cs ga gd hf nb nd pb pr rb sc sm sn th and zr but lower cd cu lu mo ni se sr u v and zn elements associated with organic matter and or fe sulfides are highly enriched in all oil shale deposits suggesting that their speciation in oil shale is governed by general processes e g high organic matter content and anoxic environment whereas elements associated with clay minerals exhibit various enrichments indicating that their speciation in oil shale is governed by individual geochemical mechanisms e g source rocks the elements in the lunpola oil shale may be classified into three groups of associations according to their modes of occurrence group a elements tio 2 sc hf zr be li w v zn sio 2 al 2 o 3 rb ga sn cr ta cs k 2 o th na 2 o rees and ash yield have high positive correlations with ash yield and a mainly inorganic affinity group b elements as toc mno ni fe 2 o 3 cd co cu mo se mgo bi pb and hg show a negative correlation with ash yield and most elements possibly have a likely organic affinity and or fe sulfide affinity group c elements sr cao u and p 2 o 5 show a weak or negligible correlation with ash yield with the exception of cao elements of environmental concern as bi hg mo pb se and u are present in high contents and are clustered in the second association i e they are hosted mainly in fe sulfides and or organic matter

three dimensional vp and vp vs velocity models of the los angeles basin and central transverse ranges california we use p and s arrival times from 5225 earthquakes and 53 explosions recorded by the southern california seismographic network to invert for the three dimensional p velocity v p and the p and s velocity ratio v p v s in the central transverse ranges and the los angeles basin to model long wavelength features of the velocity structure we invert for the models by interpolating models determined successively from a sparse medium to a dense grid with 40 20 and 10 km spacing of horizontal grid nodes layers of grid nodes are placed at depths of 1 4 6 8 12 16 and 20 km the data variance decreased about 80 in the gradational inversion ample data from the 1994 northridge and other earthquake sequences the rich background seismicity and the dense station distribution along with controlled sources made the model well resolved except along the edges to the southwest in the offshore region and at depths greater than 20 km the v p model images the shape of the los angeles and east ventura basins down to depths of 8 and 12 km three low velocity areas at 1 km depth in the los angeles basin that coincide with recent sediment depositional areas are also imaged the north edge of the peninsular ranges the santa monica and the san gabriel mountains form discontinuous high velocity ridges extending to depths of 20 km the high v p v s ratios in the near surface are consistent with high pore fluid pressures in the basin sediments at depth beneath the east ventura basin the high v p v s and high v p suggest the presence of ophiolitic assemblages or mid miocene volcanics in contrast a body with normal v p and low v p v s that is identified in the upper crust beneath santa monica bay may be a fragment of quartz rich continental crust the v p model of both the ventura and the los angeles basins shows features that suggest deformation of the hanging wall or basin closure at seismogenic depths of 16 km the hypocenters of moderate sized and large earthquakes are located within or adjacent to high v p velocity bodies in most cases these high velocity bodies form the upper block consistent with shortening of the lower crust as described in thick skinned tectonic interpretations

geological factors influencing the concentration of trace elements in the philippi peatland eastern macedonia greece abstract six peat samples obtained from the holocene and the weichselian of the philippi peat deposit eastern macedonia greece were analyzed for 48 trace elements by inductively coupled plasma mass spectrometry icp ms the ash contents of these samples were also determined most of the trace elements are associated with the minerals in the peat while ge mo pb se ta tl u and w display a greater affinity with the organic matter compared with crustal averages clarke concentrations the philippi peat is enriched in some elements ag as au cd mo se te u and w because of the respective mineralizations in the area the philippi peat is also enriched in cr cu mo pb sc sn t v y and zn in comparison with typical fen peats as well as in as cr mo se and u in comparison with typical coals climatic and hydrogeological conditions strongly influenced the peat forming environment resulting in a differentiation between holocene and weichselian peat generally the holocene peat contains lower concentrations of trace elements in the northern and southern part of the fen than the weichselian one the opposite trend is observed in the fen area close to the western basin margins

extensional neotectonics around the bend of the western central alps an overview the western alps active tectonics is characterized by ongoing widespread extension in the highest parts of the belt and transpressive compressive tectonics along its borders we examine these contrasting tectonic regimes using a multidisciplinary approach including seismotectonics numerical modeling gps morphotectonics fieldwork and brittle deformation analysis extension appears to be the dominant process in the present day tectonic activity in the western alps affecting its internal areas all along the arc shortening in contrast is limited to small areas located along at the outer borders of the chain strike slip is observed throughout the alpine realm and in the foreland the stress orientation pattern is radial for 3 in the inner extensional zones and for 1 in the outer transcurrent tranpressional ones extensional areas can be correlated with the parts of the belt with the thickest crust quantification of seismic strain in tectonically homogeneous areas shows that only 10 20 of the geodesy documented deformation can be explained by the alpine seismicity we propose that alpine active tectonics are ruled by isostasy buoyancy forces rather than the ongoing shortening along the alpine europe adria collision zone this interpretation is corroborated by numerical modeling the neogene extensional structures in the alps formed under increasingly brittle conditions a synthesis of paleostress tensors for the internal parts of the west alpine arc documents major orogen parallel extension with a continuous change in 3 directions from ene wsw in the simplon area to n s in the vanoise area and to nnw sse in the briancon area minor orogen perpendicular extension increases from n to s this second signal correlates with the present day geodynamics as revealed by focal plane mechanisms analysis the orogen parallel extension could be related to the opening of the ligurian sea during the early middle miocene and to compression rotation of the adriatic indenter inducing lateral extrusion

petrology mineralogy and geochemistry of lignites from crete greece abstract coal from the deposit of plakia island of crete greece was examined petrologically for the determination of rank maceral composition and trace element geochemistry the coal is of lignite to subbituminous b rank r o ran 0 36 0 44 some samples are rich in resinite this was subdivided into two groups based on its morphological and fluorescence properties mineral matter in the coals consists predominantly of silicate and sulphur bearing minerals the low temperature ash lta is dominated by quartz illite and gypsum whereas the mineralogy of the high temperature ash hta is comprised of silicates fe bearing minerals and anhydrite the coals are enriched in the elements as cr co cu mn mo rb se u v ce and nd when compared to world coals thorium zn and most of the rees are present in concentrations within the mean range for most coals bromine cl and se are volatilized at 1000 c while u th v cr co cu mo and zn are enriched in the coal ash by a factor of 2 8 also there are positive correlations among as mo u and s in the coal as well as between the amount of sulphur bearing minerals in coal ash and total concentration of as mo and u in the coal sulphur content in the coals ranges from 3 5 to 5 7 approximately 4 8 33 6 of sulphur is volatilized at 120 c and a large percentage of total sulphur is volatilized at 1000 c this has an important implication for the use of the plakia coals for power generation because of the emission of so x compounds to the atmosphere fluidized bed combustion and flue gas desulphurization processes are recommended to achieve reduction in trace element and sulphur emissions the hta is relatively acidic and the high content of sio 2 in the ash may create erosion problems in the boilers finally potential problems of slagging and fouling are anticipated based on the indices e g base acid ratio of the lignitic ash

a seismotectonic picture of the inner southern western alps based on the analysis of anomalously deep earthquakes abstract the anomalously deep seismicity beneath the western po plain is here analyzed to shed light on the complex and still poorly understood tectonic configuration of the internal side of the western alps area the original dataset including 590 earthquakes deeper than 20 km recorded during the last 25 years has been accurately relocated with hypodd using both catalog and cross correlation differential times we found that the distribution of seismic events faithfully mirrors the presence of two distinct tectonic domains axial belt domains 1 and 2 originally belonging to the paleogene alpine wedge and now anomalously juxtaposed beneath the sedimentary infill of the western po plain shallow low magnitude earthquakes 8 km and accommodated in correspondence of the fault could be linked to its neogene activity coeval with the northward translation of the retreating adriatic slab

reconnaissance study of mineral matter and trace elements in greek lignites abstract mineral matter in low temperature ashes major oxides and trace elements were determined for twenty eight selected lignite samples and their respective 1000 c ashes from various locations in greece using x ray diffraction x ray fluorescence spectroscopy and inaa lignites ashed at lower temperature 150 c reveal the presence of quartz feldspars layer silicates pyrite gypsum bassanite and anhydrite in all samples in northwestern greece epirus kozani florina and ptolemais calcite siderite magnesite epsomite hexahydrite jarosite and meta aluminite coexist with the common occurring minerals large variation in the concentration of major constituents in the 1000 c ashes is observed sio 2 varies from 11 98 to 87 72 al 2 o 3 from 4 53 to 23 36 fe 2 o 3 from 3 01 to 39 72 cao from 0 55 to 43 05 mgo from 0 18 to 9 17 and so 3 from 0 02 to 32 72 smaller variations are exhibited by tio 2 na 2 o k 2 o and p 2 o 5 these variations are attributed to the depositional environment high concentrations of pb 548 ppm zn 2991 ppm ba 1520 ppm as 1131 and 1675 ppm mo 565 and 712 ppm w 191 420 ppm and sb 69 ppm are reported in the 1000 c ashes of the selected lignites from serres and drama northern greece samples from another location in northern greece serres yield 5000 ppm u while in drama dipotama u concentration reaches as high as 17 600 ppm the u enrichment of lignites in these locations is attributed to the leaching of this element from the superimposed u bearing volcanic rhyodacitic rocks of oligocene age in southern greece peloponnesus lignite samples from megalopolis xidias drossato and vounargo show high f ranging from 154 to 218 ppm present results indicate that not only the wide variety and combination of elements that can be used to fingerprint lignitic basins but also the possibility of extracting such valuable elements from lignites and their ashes whenever the concentration and economics warrants such an undertaking

collapse of a hercynian tibetan plateau into a late palaeozoic european basin and range province the large width the importance of crustal shortening and the likelihood of thick crust in the late palaeozoic hercynian or variscan belt of southern europe suggest a tectonic evolution analogous to the evolution of the tibetan plateau and its neighbouring himalaya1 and of the altiplano and other high plateaux of the andes here we extend dewey and burke s analogy1 of the hercynian chain with tibet to include the subsequent stage of pervasive normal faulting and crustal extension and thinning which characterize the active tectonics of tibet parts of the high andes and the basin and range province of western north america it appears that normal faulting and rifting also characterize the late palaeozoic tectonic activity of the hercynian chain

a comparative evaluation of minerals and trace elements in the ashes from lignite coal refuse and biomass fired power plants abstract coal being a limited source of energy extraction of energy from other sources like lignite coal refuse and biomass is being attempted worldwide the minerals and inorganic elements present in fuel feeds pose different technological and environmental concerns lignite ash refuse ash and biomass ash collected from indian power plants burning lignite coal refuse and mustard stalk respectively were analyzed for physico chemical characteristics and trace elements the lignite ash has high sio 2 cao mgo al 2 o 3 and so 3 the refuse ash has high sio 2 and fe 2 o 3 but low so 3 the biomass ash has high sio 2 but low al 2 o 3 and high cao mgo k 2 o na 2 o so 3 and p 2 o 5 a substantial presence of chloride 2 1 was observed in the biomass ash quartz is the most abundant mineral species other minerals are mullite hematite gehlenite anhydrite and calcite in the lignite ash orthoclase in the refuse ash albite sanidine gehlenite anhydrite and calcite in the biomass ash ashes with high concentrations 100 mg kg of trace elements are lignite ash v

active deformation at the southwestern alps ligurian basin junction france italy boundary evidence for recent change from compression to extension in the argentera massif abstract several hundred earthquakes of small and moderate magnitude occur each year at the southwestern alps ligurian basin junction in addition the historical seismicity data attests for earthquakes of magnitude close to 6 5 despite the seismic hazard and the vulnerability of this region the present day driving mechanism of deformation and the major structures accommodating these deformations remain unclear this littoral area presents a strong topographic gradient from 3000 masl on the argentera alpine massif to 2500 m u s l in the ligurian basin and a strong structural inheritage resulting from 50 my geological evolution combining different processes such as continental collision and ocean basin opening we present new results about the kinematics of the corsica sardinia continental block with respect to the western alpine belt from 7 years of continuous gps measurements we show that a small part of the nubia eurasia convergence is certainly transferred northward of the maghrebides deformation belts to the corsica sardinia block in the southwesternmost alps from torino to the mediterranean coast the baselines reveal differential motions of lengthening between the po plain and the argentera and shortening between the argentera and the ligurian domain in a region where few focal solutions are available we determine seven new focal mechanisms located in the argentera massif these new data underline a quaternary change from compression to extension in that part of the western alpine belt the focal mechanisms calculated attest for extensional faulting at shallow level between 1 and 11 km depth we add 7 focal mechanisms from the literature to calculate the stress tensor a homogeneous solution indicates a direction of extension broadly perpendicular to the topographic axis culmination of the argentera in contrast the earthquakes recorded below 15 km at the northwestern margin of the po plain testify reverse faulting and a compressional state of stress in the deep crust thus we point out that the stress field is vertically heterogeneous in the crust of the argentera area the ligurian domain is mainly characterized by reverse and strike slip faulting the major earthquakes are located in the northern margin and at the ocean continent transition these earthquakes are assumed to result from the reactivation in a compressional state of stress of the structures formed during the oligo miocene opening of the ligurian basin finally we propose three hypotheses to explain the current deformation at the alps ligurian basin junction taking into account the far field kinematics between the nubia and the eurasia plates the topographic gradient between the argentera massif and the ligurian oceanic floor and the distribution of the deformations

high resolution surface wave tomography of the european crust and uppermost mantle from ambient seismic noise taking advantage of the large number of seismic stations installed in europe in particular in the greater alpine region with the alparray experiment we derive a new high resolution 3 d shear wave velocity model of the european crust and uppermost mantle from ambient noise tomography the correlation of up to 4 yr of continuous vertical component seismic recordings from 1293 broad band stations 10 w 35 e 30 n 75 n provides rayleigh wave group velocity dispersion data in the period band 5 150 s at more than 0 8 million virtual source receiver pairs 2 d rayleigh wave group velocity maps are estimated using adaptive parametrization to accommodate the strong heterogeneity of path coverage a probabilistic 3 d shear wave velocity model including probability densities for the depth of layer boundaries and s wave velocity values is obtained by nonlinear bayesian inversion a weighted average of the probabilistic model is then used as starting model for the linear inversion step providing the final v s model the resulting s wave velocity model and moho depth are validated by comparison with previous geophysical studies although surface wave tomography is weakly sensitive to layer boundaries vertical cross sections through our v s model and the associated probability of the presence of interfaces display striking similarities with reference controlled source seismology css and receiver function sections across the alpine belt our model even provides new structural information such as an 8 km moho jump along the css ecors crop profile that was not imaged by the reflection data due to poor penetration across a heterogeneous upper crust our probabilistic and final shear wave velocity models have the potential to become new reference models of the european crust both for crustal structure probing and geophysical studies including waveform modelling or full waveform inversion

mapping b values in france using two different magnitude ranges possible non power law behavior 1 the first step in probabilistic seismic hazard assessment is the characterization of seismic sources the fundamental assumption is that the gutenberg richter power law can be applied and is valid at all scales in this study we found that the power law model may not be verified in the southeastern regions of france frequency magnitude distributions are mapped using 2 different magnitude ranges 1 3 0 4 4 using only homogeneous instrumental data 2 3 5 m max observed using instrumental and historical data b values estimated on these two magnitude ranges are similar in the pyrenees and the rhine basin however they differ significantly in the southern alps the slopes estimated on magnitude range 3 0 4 4 are much steeper b 1 4 than the slopes estimated on magnitudes above 3 5 0 9 b 1 1 until a clear identification of the underlying processes is made a conservative option i e lowest b values should be considered for probabilistic estimation of hazard in the eastern part of france

some considerations concerning the use of correlation coefficients and cluster analysis in interpreting coal geochemistry data the mode of occurrence of trace elements in coal is important from both scientific and environmental viewpoints because the behavior of trace elements in coal utilization depends not only on their concentration but also on their chemical form or mode of occurrence statistical methods are one of the more commonly used indirect approaches for interpreting element modes of occurrence these methods include correlation coefficients between elements and ash as well among the elements themselves cluster and factor analysis using data sets derived from a suite of 75 samples from a bulgarian lignite deposit we demonstrate that statistical analysis of subsets with different ash ranges and with slightly different suites of elements can lead to substantially different conclusions concerning the element modes of occurrence in this example we assume that direct information on the element modes of occurrence such as mineralogy or selective leaching behavior is absent statistical methods however can provide useful insights into trace element modes of occurrence for properly constrained sample suites

lithospheric architecture of the south western alps revealed by multiparameter teleseismic full waveform inversion the western alps although being intensively investigated remains elusive when it comes to determining its lithospheric structure new inferences on the latter are important for the understanding of processes and mechanisms of orogeny needed to unravel the dynamic evolution of the alps this situation led to the deployment of the cifalps temporary experiment conducted to address the lack of seismological data amenable to high resolution seismic imaging of the crust and the upper mantle we perform a 3 d isotropic full waveform inversion fwi of nine teleseismic events recorded by the cifalps experiment to infer 3 d models of both density and p and s wave velocities of the alpine lithosphere here by fwi is meant the inversion of the full seismograms including phase and amplitude effects within a time window following the first arrival up to a frequency of 0 2 hz we show that the application of the fwi at the lithospheric scale is able to generate images of the lithosphere with unprecedented resolution and can furnish a reliable density model of the upper lithosphere in the shallowest part of the crust we retrieve the shape of the fast dense ivrea body anomaly and detect the low velocities of the po and se france sedimentary basins the geometry of the ivrea body as revealed by our density model is consistent with the bouguer anomaly a sharp moho transition is followed from the external part 30 km depth to the internal part of the alps 70 80 km depth giving clear evidence of a continental subduction event during the formation of the alpine belt a low velocity zone in the lower lithosphere of the s wave velocity model supports the hypothesis of a slab detachment in the western part of the alps that is followed by asthenospheric upwelling the application of fwi to teleseismic data helps to fill the gap of resolution between traditional imaging techniques and enables integrated interpretations of both upper and lower lithospheric structures

crustal structure of the alps as seen by attenuation tomography abstract we develop a simple tomographic approach exploiting the decay rate of coda waves to map the absorption properties of the crust in a region delimited approximately by the rhine graben to the north the apennines to the south the massif central to the west and the dinarides to the east our dataset comprises 40 000 coda records of about 2000 weak to moderate crustal earthquakes with magnitude ranging from 2 8 to 6 and recorded by broad band accelerometric and short period stations after proper choice of a coda window minimizing the effects of variable epicentral distances we measure the coda quality factor q c in five non overlapping frequency windows covering the 1 32 hz band for all available source station pairs these measurements are subsequently converted into maps of absorption quality factor q i using a linearized approximate relation between q c and q i in practice the following procedure is applied in each frequency band 1 we divide the target region into 40 40 km cells 2 for each source station pair we assign the measured q c value to each pixel intercepted by the direct ray path 3 the results are averaged over all paths and subsequently smoothed with a 3 3 pixels moving window our approach is consistent with the high sensitivity of q c to the value of q i between source and station our tomographic approach reveals strong lateral variations of absorption with length scales ranging from 100 km to 1000 km at low frequency 1 hz the correlation with the surface geology is clear cenozoic and mesozoic sedimentary basins resp crystalline massifs being recognized as high resp low absorption regions furthermore the q i map delineates finer geological features such as the ivrea body the rhone valley or felsic intrusions in the central alps at high frequency 16 hz only the thickest cenozoic sedimentary deposits show up as high attenuation regions and a north south dichotomy is apparent in the absorption structure the limit between low attenuation regions to the north and high attenuation region to the south correlates geographically with the location of the periadriatic lineament pl a major late alpine crustal to lithospheric scale structure furthermore the attenuation structure seems to prolong the pl to the west along a line marked by large historical earthquakes the apennines orogenic belts exhibit a distinct frequency behavior with high attenuation at low frequency and low attenuation at high frequency low frequency absorption may likely be explained by the relatively thick cover of cenozoic sedimentary materials as well as by shallow geothermal activity we hypothesize that the frequency dependence of the attenuation structure in particular in the apennines is caused by a change of the wavefield composition which accentuates the sensitivity of the coda to the deeper parts of the medium as the frequency increases

atlantic tropical systems of 1992 abstract a total of 69 tropical waves also known as african and easterly waves were counted in the atlantic basin during the 1992 hurricane season as was the case in 1991 the waves were in general relatively weak these waves led to the formation of only four tropical depressions in the atlantic hurricane basin of which one intensified into a tropical storm and another intensified into hurricane andrew andrew was the only 1992 atlantic hurricane to originate from a tropical wave there were five additional tropical depressions that were primarily initiated by systems of nontropical origin these produced three hurricanes and one tropical storm it appears that tropical waves led to the formation of practically all of the eastern pacific tropical cyclones in 1992

3d cartographic modeling of the alpine arc we built a 3d cartography of the alpine arc a highly non cylindrical mountain belt using the 3d geomodeller of the brgm french geological survey the model allows to handle the large scale 3d structure of seventeen major crustal units of the belt from the lower crust to the sedimentary cover nappes and two main discontinuities the insubric line and the crustal penninic front it provides a unique document to better understand their structural relationships and to produce new sections the study area comprises the western alpine arc from the jura to the northwest up to the bergell granite intrusion and the lepontine dome to the east and is limited to the south by the ligurian basin the model is limited vertically 10 km above sea level at the top and the moho interface at the bottom we discarded the structural relationships between the alps sensus stricto and the surrounding geodynamic systems such as the rhine graben or the connection with the apennines the 3d model is based on the global integration of various data such as the dem of the alps the moho isobaths the simplified geological and tectonic maps of the belt the crustal cross sections ecors crop and nfp 20 and complementary cross sections specifically built to precise local complexities the database has first been integrated in a gis project to prepare their implementation in the geomodeller by homogenizing the different spatial referencing systems the global model is finally interpolated from all these data using the potential field method the final document is a new tri dimensional cartography that would be used as input for further alpine studies

present day geodynamics in the bend of the western and central alps as constrained by earthquake analysis summary the contrasted tectonics of the western central alps is examined using a synthesis of 389 reliable focal mechanisms the present day strain regime is mapped and interpolated for the entire alpine belt based on a newly developed method of regionalization the most striking feature is a continuous area of extension which closely follows the large scale topographic crest line of the alpine arc thrusting is observed locally limited to areas near the border of the alpine chain a majority of earthquakes within the alps and its forelands are in strike slip mode stress inversion methods have been applied to homogenous subsets of focal plane mechanisms in order to map regional variations in stress orientation the stress state is confirmed to be orogen perpendicular both for 3 in the inner extensional zones and 1 in the outer transcurrent transpressional zones extensional areas are well correlated with the part of the belt which presents the thickest crust as shown by the comparison with the bouguer anomaly and the average topography of the belt in the northwestern swiss alps extension is also correlated with currently uplifting zones these observations and our strain stress analyses support a geodynamic model for the western alps in which the current activity is mostly a result of gravitational body forces earthquakes do not provide any direct evidence for ongoing convergence in the alpine system but a relationship with ongoing activity of complex block rotations of the apulian microplate cannot be ruled out

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

mechanical behavior of western alpine structures inferred from statistical analysis of seismicity 1 two seismic arcs 150 km and 120 km long located in the western alps 50 km apart from each other are characterized by different statistical patterns in energy and space domains for the two arcs we found power law distributions in energy domain with a lower b value and fall off for large events for the easternmost arc only and roughly similar spatial damage by comparing the shape and the statistical parameters of these distributions with those provided by numerical models of rock damage we suggest a relatively more brittle behavior for one area with respect to the other we discuss the implications of the observed distributions in terms of tectonics and of mechanics of faulting we suggest three candidates to drive the relative changes in seismicity distribution between the two arcs the earthquake depth the host rock composition and the inherited fracturing patterns

coals of greece a review of properties uses and future perspectives abstract greece relies heavily on lignites to satisfy its domestic needs for power generation and produces some of the cheapest and most cost effective kwh within the european community currently it mines 70 tons year of soft brown coal to cover over 70 of the country s domestic power needs brown coal in greece is found in 68 coal basins of various sizes generally it is of poor quality that is of low calorific values and relatively high ash content henceforth a detailed knowledge of maceral and ash composition is essential to appropriately construct boilers to avoid abrasion of mechanical parts fouling and corrosion of boilers and to take appropriate environmental measures though the composition of the maceral groups is relatively the same in almost all greek coal basins the composition of maceral subgroups especially that of huminite varies substantially this variation affects boiler s performance since the maximum heat release takes place at various heights inside the boiler humotelinitic brown coals rich in resinite release their thermal energy at lower temperatures than humocollinitic coals which have low resinite contents furthermore coal ash rich in gypsum anhydrite and other minerals with hardness less than 3 do not affect the mechanical parts of the boiler whereas coal ash rich in quartz feldspars and pyrites do finally greek brown coals have variable trace elemental composition coals from basins surrounded by carbonate rocks western greece do not exhibit high concentrations of heavy elements whereas coals from basins surrounded by mafic rocks north central greece are rich in cr ni cu and zn while coal basins surrounded by igneous rocks north eastern greece are rich in pb zn co hg as and u

atlantic tropical systems of 1994 and 1995 a comparison of a quiet season to a near record breaking one abstract totals of 70 and 63 tropical waves also known as african or easterly waves were counted in the atlantic basin during the 1994 and 1995 hurricane seasons these waves led to the formation of 9 of the 12 total number of tropical cyclones in 1994 and 19 of the 21 total number of tropical cyclones in 1995 tropical waves contributed to the formation of 75 of the eastern pacific tropical cyclones in 1994 and 73 in 1995 upper and lower level prevailing wind patterns observed during the below normal season of 1994 and the very active one of 1995 are discussed tropical wave characteristics between the two years are compared

mode of occurrence of trace elements in the pellana lignite se peloponnese greece mineralogical and geochemical analyses of the pellana lignite se peloponnese greece were carried out in order to predict the mode of occurrence of trace elements and their mobility during lignite combustion for power generation lignite and ash samples after combustion at 750 c of two cores from this deposit were examined the mean ash content is 30 to 43 and c contents on dry ash free basis range from 45 to 60 respectively the mineral phases contained in the lignite are quartz k feldspars mixed layer clays illite rich micas gypsum and pyrite factor analysis on geochemical data shows that the elements as ba mn mo sb se sr u and v have both organic and inorganic affiliation to study the mobility of each element during combustion the relative enrichment factor was calculated the most depleted and hence the most mobile elements proved to be hf nb and sb while se ba and bi are moderately depleted in case of the pellana lignite utilization we should expect environmental problems associated with the elements as ba bi hf mn mo nb sb and se these elements may be either volatilized during combustion or leached from fly ash disposal areas into underground waters causing severe environmental and health impacts

quantification of mineral matter in the argonne premium coals using interactive rietveld based x ray diffraction abstract the mineral matter in the eight reference north american coal samples of the argonne premium coal series has been investigated on a quantitative basis using x ray diffraction xrd techniques x ray diffraction data obtained from electronic low temperature oxygen plasma ash lta residues from ashes produced by heating the coals in air at 370 c and also from the raw coals themselves were evaluated using an interactive data processing system siroquant based on rietveld interpretation methods the results from the three types of material lta 370 c ash and raw coal were compared for each sample this allowed the components present in the raw coals in crystalline form to be recognised separately from mineral artifacts produced particularly in the low rank coals from interaction of organically associated elements ca s etc during the two ashing processes after the allowance for the production of any artifacts the quantitative mineral assemblages identified from xrd of the raw coals were found to be consistent even for coals having a relatively low ash percentage around 5 with the results obtained from the respective mineral concentrates prepared by the ashing methods the effects of heating the coal to 370 c could also be distinguished relative to the raw coal or the lta through changes in components such as pyrite and the clay minerals although some areas of uncertainty exist particularly with magnesium in the low rank coals the calculated chemical compositions of the coal ash derived from the mineral mixtures identified for each coal were also found to be consistent with the results of direct chemical analysis of the respective coal ash materials

tomographic inversion of local earthquake data from the hengill grensdalur central volcano complex iceland parameters is generally low however a quantitative analysis of resolution provides an unambiguous assessment of well resolved volumes within the better resolved regions of the model the averaging volumes are 1 2 km and 2 4 km in vertical and horizontal extent respectively results of tomographic inversion image three distinct bodies of anomalously high velocity two of these extend from near the surface to a depth of about 3 km these high velocity volumes are located directly beneath the surface expressions of the extinct grensdalur volcano and the extinct husmuli basalt shield the third high velocity structure occurs in the depth range of 3 4 km but does not extend to the surface these three high velocity bodies are interpreted to be solidified magmatic intrusions relatively low velocities underlay limited portions of the trace of the present accretionary axis and a low velocity body is imaged in the roots of the active hengill volcano the volume of lower velocities located beneath the surface expression of the hengill volcano is interpreted to be a region of partial melt

are there really superposed mohos in the southwestern alps new seismic data from fan profiling reflections summary the moho preserves imprints of the regional geodynamic evolution of the lithosphere as such its detailed topography in divergence or convergence zones has a strong bearing on any geodynamic model this is still more critical where 3 d effects are expected as in the case of the alpine chain which exhibits in its western part a short radius of curvature while its trend rotates by 180 the deep structure of this zone characterized by a peculiar imbrication of high density material of lower crust or mantle origin remains a puzzle in september 1999 a new controlled source seismology experiment was carried out in the southwestern alps in the area between the pelvoux dora maira and argentera massifs five shots were recorded with 130 seismic stations deployed on a total of nine fan and one in line profiles it aimed at getting information on the moho depth in a hitherto blank area and discussing the existence of the hypothetical brianconnais mantle flake mapped in 1986 by the ecors crop experiment fan profiles recorded at critical distance for reflections from the european moho allowed us to map in detail the thickening of the crust from the mediterranean coastline 27 km to the root zone 55 km the zone just south of the pelvoux massif is characterized by a rather flat 40 km deep moho which distorts the isobaths in thickening the crust along the durance valley beneath the argentera massif and just north of it we evidence a strong dip of the moho down to 51 km whereas previous maps predicted depths of 40 46 km only a new detailed map of the european moho can be drawn which integrates depth data measured at 300 reflection midpoints however the experiment could not establish the continuity of the brianconnais mantle flake over a large area in the internal alps we observed several reflectors in the 15 31 km depth range one of them is the ubaye reflector a 20 km long 23 31 km deep structure it might correspond to the brianconnais mantle flake although it is located much farther south than the reflector mapped in 1986 new investigations will be necessary to state whether its origin is crustal or due to wedging of mantle material

rare earth and major element geochemistry of eocene fine grained sediments in oil shale and coal bearing layers of the meihe basin northeast china abstract the meihe basin is a paleogene pull apart basin long flame coal lignite and oil shale are coexisting energy resources deposited in this basin ninety seven samples including oil shales coals brown to gray silt and mudstone have been collected from the oil shale and coal bearing layers to discover the rare earth element geochemistry the total ree contents of oil shales and coals are 137 256 g g and 64 152 g g respectively the chondrite normalized patterns of oil shales and coals show lree enrichments hree deficits negative eu anomalies and negligible ce anomalies the chemical index of alteration cia as well as some trace elements is often used to reflect the paleoenvironment at the time of deposition the results show that fine grained sediments in both layers were deposited in dysoxic to oxic conditions and in a warm and humid climate and coals were deposited in a warmer and more humid climate than oil shales oil shales and coals are both in the early stage of diagenesis and of terrigenous origin besides diagrams of some major trace and rare earth elements show that the fine grained sediments of both layers in the meihe basin are mainly from the felsic volcanic rocks and granite and that their source rocks are mostly deposited in the continental inland arc setting the analysis of major elements shows that si al k and ti in both layers are found mainly in a mixed clay mineral assemblage and that si is also found in quartz sodium occurs primarily in clay minerals whereas ca is found mainly in the organic matter in the coal bearing layer iron is mainly controlled by organic matter rather than detrital minerals in contrast in the oil shale bearing layer neither detrital minerals nor organic matter exert a control on the iron content analyzing the relationship between rare earth elements and major elements shows that rees in the oil shales and the coals are both of terrigenous origin and are mainly controlled by detrital minerals rather than by organic matter in both layers rees have no relationship with fine grained phosphates and during the weathering process the rees were not very mobile and were resistant to fractionation

the origin of hydrothermal metalliferous sediments associated with the early mesozoic othris and pindos ophiolites mainland greece abstract metalliferous sediments and sulphides are associated with the jurassic othris and pindos ophiolites central and northern greece these ophiolites formed at an early mesozoic spreading ridge within a small pindos ocean basin created by rifting of the northern margin of gondwanaland ubiquitous terrigenous silt was derived from adjacent continental margins mainly the pelagonian microcontinent to the east in the othris area disseminated massive and vein sulphides occur within and above morb type pillow lavas and volcaniclastic sediments sulphide was precipitated in quartz veins within fault controlled stockworks episode with local epidosite is locally very abundant in extrusives immediately underlying thick si fe rich hydrothermal sediments massive sulphides were precipitated as small fault controlled bodies that are directly overlain by fe rich mudstones and fe rich cherts strongly depleted in mn mudstones relatively enriched in hydrothermal fe mn cu zn pb ree and ba were ponded into small fault controlled hollows around the fringes of the sulphide precipitating field elsewhere e g northern othris manganese rich layers in ribbon radiolarites are strongly enriched in mn and trace elements metal enriched deposits are also found within slices of mid ocean ridge type lavas associated with melange avdella melange structurally underlying the pindos ophiolite nw greece sulphides there are restricted to tiny massive deposits overlying pillow lava and sulphide veins within ophiolitic extrusives pillow lavas are overlain by volcanic talus breccias shed from submarine fault scarps overlying metalliferous mudstones are enriched in fe and other hydrothermal constituents probably derived from nearby sulphide precipitating zones and mixed with lithogenous sediments the metalliferous deposits preserve a variety of hydrothermal deposits within an early mesozoic small ocean basin the pindos sediments reflect mixing of ferruginous hydrothermal constituents with terrigenous sediment possibly during the earlier stages of basin opening the othris sulphide and ferruginous oxide sediments record evidence of a small high temperature hydrothermal field formed near the spreading axis when the ocean neared its maximum width manganese rich cherts in the northern othris area reflect widespread accumulation of hydrothermal constituents on the abyssal plain derived from axial high temperature hydrothermal fields and or related to low temperature off axis discharge

the dynamics of the enso atlantic hurricane teleconnection enso related changes to the north african asian jet affect atlantic basin tropical cyclogenesis abstract the nature of the teleconnection linking enso variability with atlantic basin tropical storm formation is investigated solutions of the linearized barotropic vorticity equation forced with august october el nino event divergence produce upper tropospheric vorticity anomalies over the sahel and at the mouth of the north african asian naa jet over the tropical atlantic these responses are similar in magnitude and orientation to observed enso vorticity variability for this region further investigation reveals that the vorticity anomalies over the subtropical atlantic develop primarily in response to very low wavenumber westward propagating stationary rossby waves excited by el nino related convective activity over the equatorial pacific ocean however the dynamics of this teleconnection change as the atlantic basin hurricane season progresses in august and september the response is dominated by the westward propagating stationary rossby waves that alter vorticity within the naa jet and to it

earthquake relocation using a 3d a priori geological velocity model from the western alps to corsica implication for seismic hazard the region between the inner zones of the alps and corsica juxtaposes an overthickened crust to an oceanic domain which makes difficult to ascertain the focal depth of seismic events using routine location codes and average 1d velocity models the aim of this article is to show that even with a rather lose monitoring network accurate routine locations can be achieved by using realistic 3d modelling and advanced location techniques previous earthquake tomography studies cover the whole region with spatial resolutions of several tens of kilometres on land but they fail to resolve the marine domain due to the absence of station coverage and sparse seismicity to overcome these limitations we first construct a 3d a priori p and s velocity model integrating known geophysical and geological information significant progress has been achieved in the 3d numerical modelling of complex geological structures by the development of dedicated softwares e g 3d geomodeller capable at once of elaborating a 3d structural model from geological and geophysical constraints and possibly of refining it by inversion processes calcagno et al 2008 then we build an arrival time catalogue of 1500 events recorded from 2000 to 2011 hypocentres are then located in this model using a numerical code based on the maximum intersection method font et al 2004 updated by theunissen et al 2012 as well as another 3d location technique the nonlinloc software lomax and curtis 2001 the reduction of arrival time residuals and uncertainties dh dz with respect to classical 1d locations demonstrates the improved accuracy allowed by our approach and confirms the coherence of the 3d geological model built and used in this study our results are also compared with previous works that benefitted from the installation of dense temporary networks surrounding the studied epicentre area the resulting 3d location catalogue allows us to improve the regional seismic hazard assessment more particularly in the south of the argentera massif and in the ligurian basin

trace element contents in composited samples of three lignite seams from the central part of the drama lignite deposit macedonia greece abstract drill core samples of three lignite seams from the central part of the drama lignite deposit and their corresponding 1000 c ash samples were analyzed for their trace element contents by instrumental neutron activation inaa and inductively coupled plasma icp analyses compared to crustal abundances the lignite samples are enriched in as br mo and sb while ba co cr cs eu hf la lu rb sc sm tb yb zn zr and au are depleted while br is negatively correlated with the ash content of the lignite samples ce co cr la sc sm and yb are positively correlated elements from the sorrounding rocks and mineralizations of the drama basin have influenced the inorganic constituents of the lignite

evidence of synextension tilting and doming during final exhumation from analysis of multistage faults queyras schistes lustres western alps abstract during the neogene the internal arc of the western alps underwent extension behind its inverted paleogene frontal thrust while shortening affected the external arc in the core of the internal arc doming of eclogite bearing gneissic nappes has formed the dora maira massif the blueschist bearing schistes lustres of queyras which overlie the western flank of the dora maira dome allow observation of how the neogene extension developed in ductile to brittle conditions during the evolution from chocolate tablet boudinage to cross trend normal faulting the extension kept a tendency to be multidirectional the analysis of variably oriented fault families allows considering them as globally associated with the same long lived tectonic regime focusing on faults bearing several generations of slickenlines and using an adapted right dihedra analysis we propose that faulting accompanied the westwards tilting of the eastern queyras structure this tilting is consistent with the doming of the dora maira massif itself associated with tectonic denudation along its western flank therefore two processes operated simultaneously during final exhumation regional thinning through widespread multitrend normal faulting and more localised tectonic denudation and doming both are consistent with a neogene regime dominated by vertical compression the role of an ascending deep indenter below the internal arc remains to be documented

distribution of environmental sensitive trace elements in the eocene sorgun coals turkey abstract the distribution of trace elements in the lower eocene coal seam mined in the yeniceltek kucukkohne and ayridam coal mines from the sorgun basin was investigated in relation to ash content and maceral composition the coal seam is mainly composed of huminite in the present study 35 samples from five seam sections were collected on the basis of megascopic characteristics results were determined using an energy dispersive polarised x ray fluorescence edp xrf spectrometer on a whole coal dry basis most of the major and trace elements studied are enriched in high ash samples while ba br mn and w show relative enrichments in low ash samples most of elements studied such as ga ce la th nb rb zr v cu u pb sb cs sn cr se y and zn are primarily associated with mineral matter clay minerals arsenic and a part of zn se and sb are probably concentrated in pyrites in the samples element concentrations show statistically significant negative correlations with many macerals and positive relationships with only attrinite that is mainly mixed with mineral matter clay minerals and small quartz grains in the samples nine trace elements as cr mn ni pb sb se th and u considered as potentially hazardous air pollutants are present in low to moderate concentrations the mean values of trace element concentrations display relative enrichments in se 2 8 ppm th 21 ppm and w 26 ppm in the investigated samples in comparison with other coals in the world

the arc of the western alps in the light of geophysical data on deep crustal structure recently two international deep seismic campaigns in the western and central alps etude continentale et oceanique par reflexion et refraction sismique progetto strategico crosta profonda ecors crop roure et al 1996b and national research program 20 nrp 20 pfiffner et al 1997 have been completed here we present a synoptic interpretation of the wealth of geophysical data about deep crustal structure of the alps collected during the past 40 years including the two above mentioned geophysical projects the tectonic reinterpretation of the ecors crop high resolution seismic transect is based on an evaluation of the deep crustal structure by integrating new and literature data on surface geology combined with previously published interpretations regarding the central alps schmid et al 1996 this study reveals substantial differences in geometry and kinematics between transects across the western and central alps respectively at depth the transition between the central and western alps is marked by the western limits of an adriatic lower crustal wedge shaped structure and the northeastern limits of a similar structure made of european lower crustal material at the surface it coincides with a corridor of dextral strike slip along the tonale and simplon lines in addition the thickness of the seismogenic zone shows a remarkable variation from over 40 km beneath the penninic realm of the western alps to less than 20 km in the central alps the formation of the western alpine arc was initiated during convergence and collision before 35 myr ago when the adriatic micro plate moving northward with respect to the european foreland caused sinistral transpression in the western alps while the central and eastern alps underwent head on convergence and collision during the post collisional stage i e after 35 myr ago the arcuate shape of the western alps was accentuated by wnw directed movement and anticlockwise rotation of the adriatic microplate decoupled from the central and eastern alps along the tonale simplon dextral shear zone this led to wedging of lower crustal slices both in the western alps and in the central alps the new tectonic interpretation of the ecors crop transect allows a kinematic model to be established for crustal shortening in the western alps during the past 35 myr the ivrea mantle plays the role of a backstop in our tectonic model we distinguish three episodes of post collisional crustal shortening along the ecors crop transect from 35 to 30 ma the brianconnais basement was back thrusted over the gran paradiso units leading to 30 km of crustal shortening first episode in the early miocene movements concentrated mainly along the penninic frontal thrust and resulted in about 60 km shortening second episode post 12 ma shortening within the external massifs is associated with folding in the jura mountains when the crust was shortened by an additional 30 km third episode

seismicity in central and northern apennines integrating the italian national and regional networks abstract in this paper we present and discuss an improved picture of the seismicity distribution of the umbria marche abruzzi apennines as obtained through the integration of the national and the regional seismic networks operating from 2002 to 2006 during this period both the istituto nazionale di geofisica e vulcanologia ingv national seismic network and the regional networks have been greatly improved we compare the results of the integrated catalogue obtained in this study with the catalogue of the italian seismicity between 1981 and 2001 castello b selvaggi g chiarabba c amato a 2006 csi catalogo della sismicita italiana 1981 2002 versione 1 1 ingv cnt roma http legacy ingv it csi confirming the basic known features of the seismic activity in the region but also evidencing some original and interesting results in particular the new data set allows us to better define the geometry and kinematics of the crustal seismicity which is confined to the upper 20 km and shows a clear general deepening from west to east in the crust we find additional evidence of extensional seismicity below the central portion of the belt and thrust reverse faulting mechanisms at the outer fronts of the apennines looking at the seismicity along the belt it is also possible to observe aseismic regions which could be due to either locked or creeping portions of the apenninic fault system at greater depth the west dipping seismicity distribution down to about 70 km confirms the hypothesis of a slab of adriatic lithosphere subducted below the apennines but also suggests that there are strong lateral heterogeneities and possibly tears in the slab

tomography of the alpine region from observations of seismic ambient noise we use correlations of the ambient seismic noise to study the crust in western europe cross correlation of 1 year of noise recorded at 150 three components broadband stations yields more than 3 000 rayleigh wave group velocity measurements these measurements are used to construct rayleigh group velocity maps of the alpine region and surrounding area in the 5 80 s period band in the 5 10 s period band the seismic noise recorded in europe is dominated by surface waves originating from the northern atlantic ocean this anisotropy of the noise and the uneven station distribution affect the azimuthal distribution of the paths where we obtain reliable group velocity measurements as a consequence our group velocity models have better resolution in the northeast direction than in the southwest direction finally we invert the resulting rayleigh wave group velocity maps to determine the moho depth our results are in good agreement with the result of the numerous active experiments in the alps and provide a continuous image of the alpine structure

comparison of coal composition and elemental distribution in selected seams of the sydney and stellarton basins nova scotia eastern canada selected high to medium volatile bituminous coal seams of carboniferous age from the sydney and stellarton basins nova scotia eastern canada were analyzed for their organic and inorganic components these studies evaluated a the evolution of the ancestral mires coal facies that formed various seams b the lateral and vertical distribution of various elements within coal facies lithotypes and c the mode of occurrence of various elements coal facies fluctuated between rheotrophic and minerotrophic mires with occasional flooding or drowning of the mire forming inorganic partings these partings are the source for most lithophile elements including b cr u v and rare earth elements most of the lithophile elements are associated with a distinct mainly syngenetic mineral phase associated with the clay minerals which is derived from the erosion of a hinterland source chlorine ca and minor amounts of as and mn are organically bound arsenic is mostly associated with fine grained framboidal pyrite as solid solution other chalcophile elements such as cu pb and zn in the sydney basin occur as a syngenetic sulfide mineral phase whereas these elements in the stellarton basin are associated with syngenetic and epigenetic sulfides arsenic cl and mo and part of the cu and pb are possibly derived from a mineralized brine that was originated from the dissolution of windsor group evaporites the lateral variation of elements suggests that the coal beds in the sydney basin are enriched in as cl mn and pb whereas those of the stellarton basin are enriched in cr and ni the donkin resource block of the sydney basin has the lowest concentration of as mn ni and pb which make it attractive from a development perspective

geochemistry and origin of elements in some uk coals abstract twenty four uk coals ranging in rank with 4 6 37 6 volatile matter were analysed for 46 major and trace elements the samples were obtained from the uk coal bank and are representative of the major uk coal fields the major element distributions are interpreted in terms of the mineralogical variations quartz and kaolinite are largely responsible for the si and al carbonates for ca and mg and pyrite for fe also exerting an influence in some samples are siderite al phosphate minerals and illite based on statistical relationships with the major elements rb cr th ce zr y ga la ta nb and v are thought to be mainly present in the clay minerals and as mo sb tl se and bi and pb are probably present in pyrite strontium and ba are concentrated in a restricted number of samples related to the phosphate minerals germanium is the only element for which a major organic association can be demonstrated elements with an indirect association with the organic matter are na cl and br in porefluids and possibly te the ash content is controlled mainly by the detrital input and the trace elements related to the ash content are therefore those elements associated with the clay minerals variations with rank would appear to be mainly related to the moisture content porefluids the trace elements associated with the quartz and clay minerals are thought to be dominantly detrital in origin the non detrital elements essentially those contained in pyrite are thought to have been incorporated in the depositional environment from waters with enhanced salinities through seawater ingress hence there are positive relationships between s and trace element concentrations

the october november 2010 earthquake swarm near sampeyre piedmont region italy a complex multicluster sequence during one month in october and november 2010 the region of sampeyre western alps italy was struck by a seismic activity of several hundred events the location of 287 events recorded at least by three stations showed a diffuse swarm ranging between 8 and 13 km depth the number of earthquakes in the database was increased thanks to a detailed analysis of the continued recordings of the nearest station doi which allowed identifying 2612 earthquakes the temporal distribution of the seismicity is characterized by the alternation of active and quiescent periods moment magnitude was computed for 730 events by a p wave spectral analysis of the doi station data the estimated magnitudes range between 0 7 and 3 15 the b value of the cumulated frequency magnitude distribution is around 1 4 spatio temporal analysis of the located earthquakes highlighted an overall northward migration of the seismicity from spatio temporal criteria the seismicity was divided in three clusters each cluster is characterized by its own focal mechanism family the stress tensor determined from the focal mechanisms indicates probable stress heterogeneities at small spatial scale the observed migration of the seismicity could be compatible with earthquake triggering by fluid diffusion processes

exhumation controlled by transcurrent tectonics the argentera mercantour massif sw alps new apatite fission track aft and u th he ages from the argentera mercantour external crystalline massif of the sw alps document an exhumation history along transcurrent dextral faults significant aft age differences across the strikes of the main faults have been obtained from the ne 12 9 ma to the sw 5 2 ma and are linked to vertical uplifts along these right lateral transpressional structures such segmentation is not observed in ahe ages ahe ages have preserved younger ages 4 5 ma on the eastern hangingwall side of the high durance extensional system such an exhumation history is interpreted to result from a transition of transpressional to transtensional regimes at 8 5 ma during continuing adria europe convergence these data show that recent extensional deformation in the sw alps can be related to the development of a transtensional domain in the ubaye embrunais depression linked to ongoing strike slip deformation along the argentera mercantour

3d crustal structure from local earthquake tomography around the gulf of arta ionian region nw greece during summer of 1995 local seismicity was recorded in the area around the gulf of arta in northwestern greece by a dense temporary seismic network of the 441 local events observed at 37 stations 232 well locatable events with a total of 2776 p phase readings were selected applying the criteria of a minimum of 6 p observations and an azimuthal gap less than 180 this data set is used to compute a minimum 1d velocity model for the region several tests are conducted to estimate model stability and hypocenter uncertainties leading to the conclusion that relative hypocenter location accuracy is about 500 m in latitude and longitude and 1 km in depth the minimum 1d velocity model serves as initial model in the non linear inversion for three dimensional p velocity crustal structure by iteratively solving the coupled hypocenter velocity problem in a least squares sense careful analysis of the resolution capability of our data set outlines the well resolved features for interpretation the resulting 3d velocity model shows generally higher average crustal velocities in the east and the well resolved area of the eastern gulf of arta exhibits a homogeneous velocity around 6 km s for the whole upper crust a pronounced north south trending zone of low velocities in the upper 5 10 km is observed in the area of the katouna fault zone kfz at greater depths below 10 km the kfz is underlain by high velocity material e w profiles suggest a horst graben structure associated with the kfz

earthquake locations and three dimensional crustal structure in the coyote lake area central california previous work on the simultaneous inversion method has been improved and extended to incorporate iterative solution for earthquake locations and laterally heterogeneous structure approximate ray tracing and parameter separation are important elements of the improved method application of the method to p wave arrival time data recorded by stations of the u s geological survey central california network yields a three dimensional model for the velocity structure of the upper crust in an area encompassing the rupture zone of the coyote lake earthquake of august 1979 very strong correlations between the velocity model and the geology and gravity and magnetic anomalies are observed improved estimates of the locations of earthquakes in the study area are also determined the relocation of explosions indicates epicentral accuracies of the order of a kilometer or better based on the revised hypocentral locations it is concluded that the san andreas fault is vertical in this area with no actual offset between the epicenters and the fault trace in contrast the calaveras has two or more active fault surfaces one nearly vertical and another dipping 75 to the northeast

the belledonne border fault identification of an active seismic strike slip fault in the western alps summary in the french western alps east of grenoble we identify the belledonne border fault as an active seismic fault this identification is based on the seismic monitoring of the grenoble area by the sismalp seismic network over the past 12 yr 1989 2000 we located a set of earthquakes with magnitudes ranging from 0 to 3 5 along a 50 km long alignment which runs in a n30 e direction on the western flank of the belledonne crystalline massif available focal solutions for these events are consistent with this direction n36 e strike slip fault with right lateral displacement these events along the belledonne border fault have a mean focal depth of 7 km in the crystalline basement with a probably very low slip rate the belledonne border fault has never been mapped at the surface where the otherwise heavily folded and faulted mesozoic cover makes this identification difficult historical seismicity also shows that over the past two and a half centuries a few events located mainly along the southern part of the belledonne border fault caused damage with the magnitude 4 9 1963 monteynard earthquake reaching intensity vii the most recent damaging event in the study area is the magnitude 3 5 1999 laffrey earthquake intensity v vi although its epicentre lies at the southern tip of the belledonne border fault there is clear evidence that aftershocks were activated by the left lateral slip of a n122 e striking fault the length of the belledonne border fault which could easily accommodate a magnitude 6 event as well as the proximity to the isere valley with its unlithified quaternary deposits up to 500 m thick known to generate marked site effects make the identification of the belledonne border fault an important step in the evaluation of seismic risk in the grenoble area besides the activity observed on the fault will now have to be taken into account in future geodynamic models of the western alps

analysis of seismicity and micro seismicity associated with the october november 2010 sampeyre swarm southwestern alps abstract the study presents a detailed analysis of the swarm that occurred in the area surrounding sampeyre piedmont italy during the period october november 2010 the crisis caught the attention of seismologists because of its intense seismic productivity that has never been observed in the past during the swarm 550 earthquakes were recorded and located by the regional seismic network of northwestern italy rsni http www distav unige it geofisica in the study area however including the micro seismicity mainly earthquakes of magnitude lower than 0 detected through an sta lta short term average long term average based algorithm the number of events goes up to approximately 3250 among all these events approximately two hundred exceeded a local magnitude m l of 1 0 but only two earthquakes exceeded m l 3 0 reaching up to m l 3 2 following a general description of the swarm evolution the study presents the results of a waveform similarity analysis and double difference relocation aimed at identifying groups of earthquakes belonging to common genetic sources a statistical analysis of the resulting earthquake families has revealed a variation of the scaling exponent b value of the gutenberg and richter size frequency model with depth in particular our results have evidenced a slightly higher b value at shallower depths where a distinct family of earthquakes was identified through seismogram cross correlation this may reflect variability in the distribution of fractures in the rock volume involved in the swarm

seismological studies at parkfield i simultaneous inversion for velocity structure and hypocenters using cubic b splines parameterization a model for the 3d p and s wave velocity structure at parkfield has been developed by the systematic inversion of arrival times for microearthquakes and surface vibroseis sources recorded by nearby calnet stations and by the local borehole installed 10 station high resolution seismic network there a modification of the linear b splines model parameterization method of thurber 1983 to a cubic b splines formulation through tests inverting synthetic data sets for the parkfield configuration is found to produce smooth velocity distributions that still retain some small scale features application of the method to 953 p wave and 288 s wave arrivals from 111 microearthquakes and 8 vibroseis locations throughout the study area yields a velocity structure having variable resolution a low velocity zone appears to coincide with the creeping segment of the san andreas fault zone northwest of the 1966 parkfield earthquake epicenter an increase of about 15 per cent in seismic velocities is seen from the northeast to southwest across this segment of the fault zone the higher velocities to the southwest apparently correspond to the granitic basement the contrast across the fault is subdued to the southeast along the 1966 rupture zone a high vp vs ratio of 1 9 is seen in a 2 km wide volume near the location of the 1966 main shock hypocenter presumably the nucleation zone for the expected m 6 parkfield earthquake