interplay between subduction retreat and lateral extrusion tectonics of the western carpathians 1 analysis of brittle microstructures reveals three tertiary deformation events in the western carpathians 1 late paleogene bedding parallel extension 2 oligocene to middle miocene nne ssw compression and ese wnw extension 3 post mid miocene nw se extension these regional deformations applied to crustal blocks in the intra carpathian region resulted from forces which were induced by the coupled plate tectonic processes of subduction retreat beneath the carpathian arc and lateral extrusion from the eastern alps toward the carpathian region material flow from the alps spread toward east and ne guided by sinistral strike slip zones along the ne trending continental margin subduction retreat was terminated by mid miocene soft collision of the inner western carpathians with the european foreland ongoing subduction retreat beneath the eastern carpathians caused post mid miocene back arc extension forming the pannonian basin extension spread into the western carpathians by reactivating the extrusion related strike slip faults as normal faults

life cycle of the east carpathian orogen erosion history of a doubly vergent critical wedge assessed by fission track thermochronology apatite fission track b t thermochronology applied to the east carpathian fold and thrust belt in romania constrains the interaction between the erosion history and the tectonic evo lution of the orogen the long lived constant asymmetric topography of the orogen and the erosion pattern as inferred from apatite ft data are in agreement with the style of evolution predicted by doubly vergent critical coulomb wedge models during the miocene up to 4 km of erosion took place over the actively deforming orogen and the erosion patterns forms a mirrored image of the subsurface deforming wedge the erosion products are deposited in flanking molasse basins which subsided contemporaneously due to the growing topographic weight of the wedge deformation of the wedge was presumably active from the early to late miocene but apatite ft ages between 14 and 9 ma and track length modeling predict an acceleration of erosion rates 0 5 0 3 mm yr ini tially in the middle to late miocene 3 2 ma the onset of erosion coincides with the last phase of convergence and a climax in the deformation history these features are interpreted to have been caused by underplating of the european continental margin convergence ceased before the pliocene according to the activity of thrust faults during the pliocene and quaternary up to 2 km of overburden was removed by erosion leading to isostatic rock uplift of the entire region the use of apatite fission track minimum ages supports the general idea that the orogen has a di achronous evolution from north to south the orogen in the southern bend zone has a more juve nile tectonic character and the main erosion phase took place during the pliocene and quaternary 5 0 ma the integrated approach of large scale morphology and fission track analysis confirms the applicability of the theoretical coulomb wedge mechanics to a natural compressive fold and thrust belt the study complements the geometric features of the orogenic wedge with quantified erosion histories and illustrates the effects of orogen evolution on vertical movements in the entire convergent setting

evolution of the transport direction of the carpathian belt during its collision with the east european platform the evolution of the carpathians is in its final stage with intermediate seismic activity 70 200 km mw 4 7 7 localized beneath its southeastern salient vrancea zone our analysis in the transition area between south carpathians and east carpathians reveals that the termination of convergence is characterized by a clockwise rotation of the carpathian belt transport direction using structural maps and cross sections we show that this change of convergence direction had several structural consequences including 1 the pliocene quaternary activation of out of sequence structures in the southern east carpathians and 2 the creation of dextral strike slip faults bounding the mobile belt to the west in the south carpathians our fracture analysis in syntectonic deposits allows us to distinguish and stratigraphically date two fanning stress patterns corresponding to the two last transport directions of the carpathian system 1 a burdigalian to early tortonian stress field with compression directions rotating along with the carpathian curved orogenic belt but with transpression nw se compression and a low strain partitioning along east trending internal strike slip faults in the south carpathians and 2 a late tortonian to pleistocene rotated and smaller radial stress pattern with n s compression in the south carpathians the rotation of the convergence direction is interpreted as the result of the miocene migration and progressive collision of the carpathian system with the thick crust of the nw trending tornquist teisseyre line and its prolongation in romania the area able to subduct determined by thickness of crust entering the subduction zone was progressively restricted to a foreland corner in front of the southeastern carpathians the progressive collision forced the convergence to slow down and rotate from eastward to southeastward in late miocene the dobrogea hills in front of the latest migrating system may represent the late neogene ne sw flexural bulge of the subducting foreland panel this clockwise rotation of the transport direction can be compared with the clockwise rotation that occurred in other subduction systems tyrrhenian subduction caribbean subduction etc which were controlled by the location of oceanic versus continental crust in front of the orogenic belt

crustal structure of the carpathian pannonian region from ambient noise tomography we use ambient noise tomography to investigate the crust and uppermost mantle structure beneath the carpathian pannonian region of central europe over 7500 rayleigh wave empirical green s functions are derived from interstation cross correlations of vertical component ambient seismic noise recordings 2005 2011 using a temporary network of 54 stations deployed during the south carpathian project 2009 2011 56 temporary stations deployed in the carpathian basins project 2005 2007 and 100 permanent and regional broad band stations rayleigh wave group velocity dispersion curves 4 40 s are determined using the multiple filter analysis technique group velocity maps are computed on a grid of 0 2 0 2 from a non linear 2 d tomographic inversion using the subspace method we then inverted the group velocity maps for the 3 d shear wave velocity structure of the crust and uppermost mantle beneath the region our shear wave velocity model provides a uniquely complete and relatively high resolution view of the crustal structure in the carpathian pannonian region which in general is validated by comparison with previous studies using other methods to probe the crustal structure at shallow depths 30 km are relatively fast presumably related to shallowing of the moho consequent on the extensional history of the pannonian region

neogene kinematics of the transylvanian basin romania the transylvanian basin is a major sedimentary basin located in the eastern part of the european alpine orogenic system it has a sedimentary fill more than 5 km up to 8 km in some small areas thick of upper cretaceous to upper miocene deposits it represents the main gas producing province in romania and central eastern europe in this article we analyze seismic lines and structural data from the basin as well as from its northern eastern and southeastern borders these data indicate a tectonic origin for the neogene structures from the transylvanian basin these structures include 1 northeast and southwest dipping thrust faults and 2 east northeast and west northwest striking strike slip faults having normal or reverse slip secondary structures such as salt diapirs and folds are related to these faults structural data from the basin and its border indicate a neogene overall compressional transpressional regime having maximum principal stress oriented north to northeast daniel ciulavu received a diploma in geology and geophysics at the university of bucharest in 1989 and his ph d in geology at the vrije universiteit amsterdam netherlands in 1999 he worked two years for geasol s a romania in hydrogeology coal and alluvial gold exploration since 1991 he has been on the staff of the university of bucharest where he teaches the courses on structural geology in the department of geophysics and kinematic analysis for master s students corneliu dinu received a diploma in geology in 1966 and his ph d in 1976 at the university of bucharest romania after graduation he worked as field geologist for prospectiuni s a romania since 1970 he has been on the staff of the university of bucharest where he is professor of structural geology and basin analysis since 1990 he has served as the dean of sciences at the faculty of geology and geophysics university of bucharest alexandru szakacs received a diploma in geology in 1974 and his ph d in 2000 at the university of bucharest romania he is senior geologist at the romanian institute of geology he has 25 years of experience in studying the neogene volcanism of the carpathian pannonian area he has also worked on the neogene volcanism of the cordillera betica spain dorin dordea received a diploma in geology in 1974 at the university of cluj romania his field of activity is remote sensing he has worked in several areas in africa and romania since 1999 he has served as the chief geologist of prospectiuni s a bucharest romania he is now working on the application of remote sensing in mining exploration

deposition of anthropogenic aerosols in a southeastern tibetan glacier 1 measurements of elemental carbon ec water insoluble organic carbon wioc and inorganic ions from a very high resolution snow firn core retrieved from a glacier on the southeastern tibetan plateau reveal increasing concentrations associated with deposition of anthropogenic aerosols during the period 1998 2005 ec wioc and so42 concentrations in the core were 4 7 56 0 and 4 2 ng g 1 in 1998 but increased to 16 8 144 4 and 162 1 ng g 1 in 2005 respectively comparison of ec to so42 and k concentrations indicates a relatively greater impact of fossil fuel burning on ec deposition compared to biomass burning significant contribution of secondary oc production is apparent from the low ec wioc ratios ec concentrations show large seasonal variability with nonmonsoon precipitation containing more than double the concentrations found in monsoon snowfall since snow cover on the tibetan plateau extends to its maximum aerial extent during the nonmonsoon season the high ec concentrations in snowfall during this time can cause advanced snowmelt and enhanced radiative forcing

slab break off abrupt cut or gradual detachment new insights from the vrancea region se carpathians romania slab break off is a plate tectonic process which does not only return lithospheric material into the deeper mantle but also has severe effects on surface movements and seismic hazard slab pull induced seismicity is reduced when the subducted slab decouples from the overlying crust in the vrancea region se carpathians strong earthquakes frequently occur at intermediate depths 70 180 km in a laterally small volume while the crust shows low but distributed seismicity the stress pattern shows similar partitioning with vertical extension in the slab and no preferred orientation in the overlying crust both features indicate a decoupling between slab and overlying crust either by slab break off or delamination however the strong vertical elongation of the slab requires that the upper end of the slab is fixed vertically thus a soft coupling is assumed that is strong enough to enable elongation of the slab but weak enough to inhibit quasi static stress transfer to the overlying crust

high resolution teleseismic body wave tomography beneath se romania ii imaging of a slab detachment scenario summary non linear teleseismic bodywave tomography with data of the 1999 calixto field experiment carpathian arc lithosphere x tomography in romania provides high resolution imaging of the upper mantle structure in this paper we present the relative p wave velocity distribution of the lithosphere asthenosphere system smearing from strong crustal velocity anomalies into the upper mantle is successfully suppressed by traveltime corrections with an a priori 3 d regional crustal velocity model see martin et al 2005 herein referenced as paper 1 our high resolution image shows a high velocity body beneath vrancea and the moesian platform with a ne sw orientation between 70 and 200 km depth beneath 200 km a change in the orientation from ne sw to n s can be observed the body reaches a maximum depth of about 350 370 km the velocity perturbation is maximal between 110 and 150 km depth 5 2 5 8 per cent and almost constant for depths beneath 200 km 3 2 3 8 per cent as most authors of previous studies agree on miocene subduction along the arc followed by soft continental collision we interpret the high velocity body as the subducted yet not fully detached slab the ne part of the slab appears to be mechanically coupled to the moesian lithosphere and hosts the intermediate depth seismicity in contrast the aseismic sw part is interpreted as decoupled from the overlying lithosphere and torn off from the underlying lithospheric material beneath 200 km depth low velocity anomalies nw of the slab above 110 km depth are interpreted as a shallow asthenospheric upwelling further low velocity anomalies are in agreement with a lithosphere asthenosphere boundary at 110 150 km depth below the moesian platform and deeper than 200 km under the east european platform eep the tomographic images support models proposing slab rollback during subduction collision followed by slab steepening and lithospheric delamination the different degrees of mechanical coupling of the slab to the overlying lithosphere allow to understand the loci of seismicity as volumes of stress concentration independent on the specifics of data interpretation our high resolution image is a novel contribution to understand the process of ongoing lithospheric detachment associated with strong intermediate depth seismicity in se romania

observed vertical redistribution of black carbon and other insoluble light absorbing particles in melting snow 1 light absorbing impurities in snow reduce snow albedo producing a positive radiative forcing warming the surface air and snowpack and accelerating snow melt as the snow melts black carbon bc and other insoluble light absorbing particulate impurities ilap are retained at the snow surface because their scavenging efficiency with meltwater is 100 so concentrations of ilap in surface snow increase with snow melt further reducing snow albedo the magnitude of this positive feedback depends on the scavenging efficiency of bc and other ilap with snow meltwater we present results from field measurements of the vertical distribution of bc and other ilap in snow near barrow alaska the dye 2 station in greenland and tromso norway during the melt season amplification factors due to melt are calculated for the concentrations in surface snow of bc and all ilap at barrow and dye 2 melt scavenging rates are estimated melt amplification appears generally to be confined to the top few centimeters of the snowpack where it increases concentrations of bc and other ilap by up to a factor of about five scavenging fractions of ilap due to percolation of meltwater are estimated at 10 30 with the rates for bc being comparable or a few percent lower the lack of distinction may result from the particles in snow being internal mixtures of both bc and other ilap so that scavenging efficiencies for these internally mixed particles are determined by the total particle size and hydrophobicity rather than being different for individual particle components

thermo mechanical controls on the mode of continental collision in the se carpathians romania abstract the carpathians orogenic system with its along arc variations in topography developed in the aftermath of continental collision is associated with unusual foredeep basins large scale strain and seismicity concentration and high velocity mantle bodies the east carpathians continental collision was non cylindrical leading to large scale variations in thrust nappe kinematics orogenic uplift patterns and foredeep subsidence controlled by the mechanics and geometry of the lower plate thermo mechanical modelling demonstrates that in this low rate convergence regime the subducted lithosphere had enough time to interact with the mantle to advance towards a thermal resettlement this is favored by the low degree of metamorphism mechanical weakness of the lower plate and the lack of active surface processes at the contact with and in the upper plate in contrast low buoyant thick lower crust and active surface processes keep the continuity of the slab intact and promote the development of typical foredeep basins the model explains in a self consistent manner the unusual geometry of the vrancea seismogenic slab in the bend zone of the romanian carpathians the model is also consistent with the presence of two high velocity bodies inferred from seismic tomography studies and explains the depth zonation of seismicity in the vrancea area differences between the northern part of east carpathians and the southeastern bend of the carpathians arc are largely controlled by lateral variations in crustal structure topography emplacement and surface processes along the arc mechanical heterogeneity of the carpathians subduction leads to the development of two end member modes of collision allowing a study of these states and their transition lithospheric configuration and tectonic topography appear to be prime factors controlling variations in slab behavior in the se carpathians at the terminal phase of continental convergence slab delamination roll back and depocenter migration appear to play a more limited role at shallow and lithospheric levels

palaeozoic terranes and their lithospheric boundaries within the trans european suture zone tesz a review the trans european suture zone tesz is a broad and complex zone of terrane accretion separating ancient lithosphere of the baltic shield and east european craton eec from the younger lithosphere of western and southern europe there is debate about the number of terranes involved and their origins the most significant terrane boundaries originally oceanic sutures are poorly exposed and are defined using faunal provinciality prominent geophysical lineaments may represent sub terrane boundaries within composite terranes the avalonia composite terrane was amalgamated to baltica in latest ician time the provenance of the malopolska and moravo silesian terranes whose neoproterozoic basement is suspect with respect to baltica but with which they nonetheless share faunal affinities is still debated the extent of the variscide rhenohercynian zone defines the southern limit of the early palaeozoic accreted terranes terranes within the bohemian massif exhibit hp metamorphism recording subduction driven collision prior to incorporation in the tesz collage itself associated with a hp event in romania the saxothuringian zone and rheic suture are directly juxtaposed with the eec and the crustal structure of the tesz has been much modified by post palaeozoic tectonism deep seismic reflection data where available show that the oceanic sutures are frequently associated with inclined reflectivity zones irz in the lithospheric mantle here inferred to mark relict subduction zones interpreting the age of subduction is complicated by offset of originally coplanar mantle and crustal segments of the irz resulting from early orogenic lithospheric delamination at the moho interface and or post orogenic reordering processes the mantle irz appear to indicate a n directed polarity for early palaeozoic subduction apparently incompatible with the geological evidence which indicates subduction of the tornquist sea beneath avalonia and a large amount of underthrusting of avalonia by baltica possible explanations for these apparently incompatible observations are evaluated

some seismic signatures in the romanian crust abstract some new seismic reflection data in the w of the moesian platform focsani depression and transylvania depression show seismic patterns which reflect the local structure and evolution of the each area these local areas were affected by subsidence which over printed the changes on the old pattern the old and more or less reflective lower crust was fractured and some rigid blocks have preserved the reflectivity up to the present the ba ilesti section illustrates a transparent or diffractive upper crust and a well marked lower crust by an alternation of reflective and non reflective zones the crystalline crust of the r mnicu sa rat section has two patterns one relatively reflective near the bottom of the depression the w side whilst the other on the e flank of depression is transparent the e flank seems to be more fractured due to some tensile fractures originating in the bending stress during subsidence the t rgu muressection has a specific crustal pattern a near transparent crystalline crust overlies a very large crust mantle transition zone which is fragmented in alternated reflective and transparent blocks

new seismic and tomography data in the southern part of the harghita mountains romania southeastern carpathians connection with recent volcanic activity the southern part of the southeastern carpathians represents the site of the most recent volcanic eruptions of the entire carpathian pannonian region the products of these eruptions range from 42 to 10 ka radiocarbon ages in the south harghita mountains high k calc alkaline rocks with adakite like features and at 1 2 0 6 ma k ar ages in the persani mountains alkali basalts they were emplaced in a post collisional regime ciomadul volcano is located at the southernmost part of the nw se oriented c limani gurghiu harghita range crossing the inner part of the southeastern carpathians and in the rough proximity of the vrancea seismic zone at ca 60 km toward nw its magma generation is attributed to geodynamic events closely related to the seismogenic area a number of particular geophysical and geochemical features located in the study region including 1 the abrupt attenuation of the seismic waves originating from the vrancea intermediate depth foci 2 the most intense heat flow anomaly in romania 3 the most prominent 3he 4he anomaly measured in natural postvolcanic gas emanations are all in favor of the hypothesis of a still existing hot local magma chamber data acquired during recent seismic monitoring of the vrancea zone and its neighborhoods suggest an enhancement of the local seismicity beneath the southern edge of the south harghita mts both at crustal and subcrustal levels at the same time recent tomography images obtained using local earthquake data correlate well with the presence of a vertically extended low velocity zone coming from the upper mantle to the assumed magmatic chambers located in the crust the present data supporting the presence of an active crustal magma chamber beneath ciomadul allow us to consider that future volcanic activity at this volcano cannot be discarded

tertiary tectonic evolution of the external east carpathians romania abstract paleostress calculation and analysis of mesoscopic structures are integrated with depth interpreted geological profiles based on seismic studies and well correlation to derive a tertiary tectonic model for the east carpathians following early miocene and older orogenic phases the first tectonic event that affected the studied area is characterised by a wsw ene oriented shortening of middle miocene late burdigalian in age resulting deformations induced ene ward thrusting of tarcau and marginal units as well as the internal part of the subcarpathian nappe a second shortening event with an e w to wsw ene contraction direction took place in the late miocene sarmatian characterised by further foreland thrusting of the subcarpathian nappe and out of sequence deformation in the tarcau and marginal folds nappes along strike differences in deformation mechanisms are controlled by the friction coefficients along the main detachment layers by the lateral variations in the wedge thickness and by the involvement in the northern part of the thrusting system of the thick competent east european platform tear faulting occurred in both tectonic events the main resulting structure being the triangle zone developed south of the trotus valley the latest miocene latest sarmatian early pliocene is characterised by a strike slip stress field with nne ssw compression and wnw ese tension axis left lateral faults being dominant the last deformation which affected the studied area is characterised by nnw sse shortening during the pliocene major deformations taking place mainly in the sw most bending zone

kinematics of the alpine west carpathian orogen and palaeogeographic implications we present the euler rotations of the plates involved in the alpine west carpathian orogen the rotations are defined to a large extent by the magnetic anomalies of the atlantic ocean a few extra rotations occurred during two collisions and a mid cretaceous event at variance with earlier reconstructions we additionally control the rotations by the orientation of palaeomagnetic declinations the plate rotations are integrated into a model illustrated by palaeogeographical maps special features of the model are 1 subdivision of the northern margin of adria into the two plates pelso and austroalpine west carpathia on the basis of palaeomagnetic data 2 eohellenic obduction of meliata units onto the eastern margins of pelso and austroalpine west carpathia from the tethys side 3 first eoalpine collision of the marginal plates of adria with tisza far off the west european plate margin 4 a 80 90 rotation of austroalpine west carpathia during the eoalpine collision 5 subdivision of the neoalpine collision into a palaeogene stage of predominantly strong se nw shortening and a neogene stage of predominantly lateral extrusion westward and eastward in principle the maps show quantitative ocean spreading subduction and plate rotations however possible modifications of the model discussed in this paper limit the quantitative evaluation

crustal constraints on the origin of mantle seismicity in the vrancea zone romania the case for active continental lithospheric delamination abstract the vrancea zone of romania constitutes one of the most active seismic zones in europe where intermediate depth 70 200 km earthquakes of magnitude in excess of m w 7 0 occur with relative frequency in a geographically restricted area within the 110 bend region of the southeastern carpathian orogen geologically the vrancea zone is characterized by a a laterally restricted steeply nw dipping seismogenic volume 30 70 200 km situated beneath b thickened continental crust within the highly arcuate bend region of the carpathian orocline and c miscorrelation of hypocenters with the position of known or inferred suture zones in the carpathian orogenic system geologic data from petroleum exploration in the eastern carpathians published palinspastic reconstructions and reprocessing of industry seismic data from the carpathian foreland indicate that 1 crust of continental affinity extends significantly westward beneath the external thrust nappes sub carpathian marginal folds and tarcau of the eastern carpathians 2 cretaceous to miocene strata of continental affinity can be reconstructed westward to a position now occupied by the transylvanian basin and 3 geologic structure in the carpathian foreland including the moho is sub horizontal directly to the east and above the vrancea seismogenic zone taken together these geologic relationships imply that the vrancea zone occupies a region overlain by continental crust and upper mantle and does not appear to originate from a subducted oceanic slab along the length of the carpathian orogen accordingly the vrancea zone appears to potentially be an important place to establish evidence for active lithospheric delamination

effects of sources transport and postdepositional processes on levoglucosan records in southeastern tibetan glaciers tibetan glaciers are substantially influenced by smoke aerosols derived from intensive biomass burning bb emissions in surrounding regions however knowledge regarding the impact of smoke aerosols on tibetan glaciers is limited here we present levoglucosan records extracted from two southeastern tibetan set glaciers we found that zuoqiupu zqp glacier situated on the windward side of the mountains is more strongly affected by bb aerosols when compared with cuopugou cpg glacier on the leeward side on zqp glacier the highest levoglucosan concentration was detected at an elevation near the equilibrium line altitude ela the injection height of smoke plumes and the actions of post depositional processes on the glacier surface determined the distribution patterns of levoglucosan concentrations at different altitudes spatiotemporal variability in levoglucosan and black carbon bc distributions after deposition may be caused by the different source characteristics and by different post depositional geochemical behaviors on the glacier surface intense wildfires can lead to extremely high concentrations higher than 25 ng ml 1 of black carbon in ice near the surface of set glaciers and can therefore play an important role in glacial melt during the pre monsoon season

s wave attenuation characteristics beneath the vrancea region in romania new insights from the inversion of ground motion spectra the s wave attenuation characteristics beneath the vrancea region in romania are analyzed from the spectra frequency range 0 5 20 hz of more than 850 recordings at 43 accelerometric stations of 55 intermediate depth earthquakes m 4 0 7 1 that occurred in the vrancea seismogenic zone the method commonly chosen for this type of investigation in the case of crustal earthquakes is the generalized inversion technique git e g andrews 1986 castro et al 1990 yet the vrancea dataset is entirely different from common crustal datasets because of the strong clustering of the hypocenters within a very small focal volume there are only few crossing ray paths from sources to receivers as a consequence inhomogeneities in the attenuation properties are not averaged out which leads to unphysical results if the standard git approach is adopted the problem is discussed qualitatively by performing tests with synthetic data and solved quantitatively by adapting the git technique in view of these peculiarities with the optimally adapted inversion scheme it is possible to unravel differences in the attenuation characteristics between two or more sets of stations the results show that the attenuation of seismic waves is roughly comparable in the low frequency range 4 5 hz but stronger by up to an order of magnitude at higher frequencies within the carpathian mountain arc as compared with the foreland area modeling this strongly frequency dependent lateral variation of seismic attenuation by a significantly lower q beneath vrancea 1 provides a very good fit of observed strong motion characteristics 2 sheds new light on the distribution of intensities of the previous strong earthquakes 3 will have strong implications for future hazard assessment and 4 is fully compatible with structural models from deep seismic sounding tomography and teleseismic attenuation

revised crustal architecture of the southeastern carpathian foreland from active and passive seismic data 1 integration of active and passive source seismic data is employed in order to study the nature of the relationships between crustal seismicity and geologic structures in the southeastern se carpathian foreland of romania and the possible connection with the vrancea seismogenic zone vsz of intermediate depth seismicity one of the most active earthquake prone areas in europe crustal epicenters and focal mechanisms are correlated with four deep industry seismic profiles the reprocessed danube and carpathian integrated action on process in the lithosphere and neotectonics dacia plan profile and the deep reflection acquisition constraining unusual lithospheric activity ii and iii dracula profiles in order to understand the link between neotectonic foreland deformation and vrancea mantle seismicity projection of crustal foreland hypocenters onto deep seismic profiles identifies several active crustal faults in the se carpathian foreland and suggests a mechanical coupling between the mantle located vsz and the overlying foreland crust the coupled associated deformation appears to take place on the trotus fault the sinaia fault and the newly detected ialomita fault seismic reflection imaging reveals the absence of west dipping reflectors in the crystalline crust and a slightly east dipping to horizontal moho in the proximity of the vrancea area these findings argue against previously purported mechanisms to generate mantle seismicity in the vsz including oceanic lithosphere subduction in place and oceanic slab break off furthermore suggesting that the vrancea seismogenic body is undetached from the overlying crust in the foreland

black carbon and mineral dust on two glaciers on the central tibetan plateau sources and implications sources and implications of black carbon bc and mineral dust md on two glaciers on the central tibetan plateau were estimated based on in situ measurements and modeling the results indicated that bc and md accounted for 11 1 and 4 0 of the albedo reduction relative to clean snow while the radiative forcing varied between 11 and 196 and 1 89 w m 2 respectively assessment of bc and md contributions to the glacier melt can reach up 88 to 434 and 35 to 187 mm w e respectively contributing 9 23 and 4 10 of the total glacier melt a footprint analysis indicated that bc and md deposited on the glaciers originated mainly from the middle east central asia north china and south asia during the study period moreover a potentially large fraction of bc may have originated from local and regional fossil fuel combustion this study suggests that bc and md will enhance glacier melt and provides a scientific basis for regional mitigation efforts

vrancea99 the crustal structure beneath the southeastern carpathians and the moesian platform from a seismic refraction profile in romania the vrancea99 seismic refraction experiment is part of an international and multidisciplinary project to study the intermediate depth earthquakes of the eastern carpathians in romania as part of the seismic experiment a 300 km long refraction profile was recorded between the cities of bacau and bucharest traversing the vrancea epicentral region in nne ssw direction the results deduced using forward and inverse ray trace modelling indicate a multi layered crust the sedimentary succession comprises two to four seismic layers of variable thickness and with velocities ranging from 2 0 to 5 8 km s the seismic basement coincides with a velocity step up to 5 9 km s velocities in the upper crystalline crust are 5 9 6 2 km s an intra crustal discontinuity at 18 31 km divides the crust into an upper and a lower layer velocities within the lower crust are 6 7 7 0 km s strong wide angle pmp reflections indicate the existence of a first order moho at a depth of 30 km near the southern end of the line and 41 km near the centre constraints on upper mantle seismic velocities 7 9 km s are provided by pn arrival times from two shot points only within the upper mantle a low velocity zone is interpreted travel times of a plp reflection define the bottom of this low velocity layer at a depth of 55 km the velocity beneath this interface must be at least 8 5 km s geologic interpretation of the seismic data suggests that the neogene tectonic convergence of the eastern carpathians resulted in thin skinned shortening of the sedimentary cover and in thick skinned shortening in the crystalline crust on the autochthonous cover of the moesian platform several blocks can be recognised which are characterised by different lithological compositions this could indicate a pre structuring of the platform at mesozoic and or palaeozoic times with a probable active involvement of the intramoesian and the capidava ovidiu faults especially the intramoesian fault is clearly recognisable on the refraction line no clear indications of the important trotus fault in the north of the profile could be found in the central part of the seismic line a thinned lower crust and the low velocity zone in the uppermost mantle point to the possibility of crustal delamination and partial melting in the upper mantle

moho topography and lower crustal wide angle reflectivity around the tesz in southern scandinavia and northeastern europe abstract the moho topography is strongly undulating in southern scandinavia and northeastern europe a map of the depth to moho shows similarities between the areas of the teisseyre tornquist zone ttz in poland and the fennoscandian border zone fbz which is partly coinciding with the sorgenfrei tornquist zone stz in denmark the moho is steeply dipping at these zones from a crustal thickness of approximately 32 km in the young palaeozoic platform and basin areas to approximately 45 km in the old precambrian platform and baltic shield the moho reflectivity pmp waveform in the polonaise 97 refraction wide angle seismic data from poland and lithuania is variable ranging from sharp to strongly reverberating signals of up to 2 s duration there is little or no lower crustal wide angle reflectivity in the thick precambrian platform whereas lower crustal reflectivity in the thin palaeozoic platform is strongly reverberating suggesting that the reflective lower crust and upper mantle is a young phenomena from stochastic reflectivity modelling we conclude that alternating high and low velocity layers with average thicknesses of 50 300 m and p wave velocity variations of 3 4 of the background velocity can explain the lower crustal reflectivity sedimentary layering affects the reflectivity of deeper layers significantly and must be considered in reflectivity studies although the reverberations from the deeper crust cannot be explained by the sedimentary layering only the reflective lower crust and upper mantle may correspond to a zone that has been intruded by mafic melts from the mantle during crustal extension and volcanism

elemental and organic carbon measurements with a two step heating gas chromatography system in snow samples from the tibetan plateau in this study an optimized two step heating gas chromatography system is used to measure elemental carbon ec and organic carbon oc content in snow and ice with the ability to quantify the elemental and organic carbon species in a snow or ice sample of 60 80 g in this system oc and ec are transformed into co2 in a stream of oxygen at 3408c and 6508c respectively the resulting co2 is accumulated in two molecular sieve traps and then put into a gas chromatograph equipped with a flame ionization detector by heating the traps to 2008c in a helium stream background contamination mainly caused by impurities in the oxygen stream and accuracy are dominated by the variability of the blank loads on the pre cleaned filters which are 0 50 0 04 1 mgc for oc and 0 38 0 04 1 mgc for ec the system is suitable for snow and ice sample measurements with the same precision as shown for the blank tests ec and oc concentrations have been measured in snow samples collected from different glaciers on the tibetan plateau the results allow quantification for the first time of the different carbonaceous particle contents on the tibetan plateau and other regions the concentrations of ec and oc particles in snow show a clearly decreasing trend from east to west and from north to south on the plateau excluding the pamirs region the highest mean ec content 79 2 ng g 1 was found in the northeast region and the lowest 4 3 ng g 1 was found in the western himalaya we note that even slight surface melting results in fresh snow getting dirtier especially in regions with higher pollution such as seen on a glacier in the qilian shan here the ec and oc concentrations in the fresh snow average 6 6 and 87 5 ng g 1 but after 2 days of surface melting they increased to 52 6 and 195 5 ng g 1 this suggests that surface snow melting can reduce snow albedo due to the accumulation of carbonaceous particles

crustal properties from s wave and gravity data along a seismic refraction profile in romania vrancea 99 is a seismic refraction line that was carried out in 1999 to investigate the deep structure and physical properties of the upper lithosphere of the southeastern carpathians and its foreland it runs from the city of bacau to the danube river traversing the vrancea epicentral area of strong intermediate depth seismicity and the city of bucharest interpretation of p wave arrivals led to a velocity model that displays a multi layered crust with velocities increasing with depth the range of p wave velocities in the sedimentary cover increases from n to s and a structuring of the autochthonous basement of the moesian platform is observed the crystalline crust displays thickness variations but at the same time the lateral velocity structure along the seismic line remains almost constant an intra crustal boundary separates an upper crust from the lower crust within the upper mantle a low velocity zone is detected at a depth of about 55 km the interpretation of observable s waves resulted in a velocity model that shows the same multi layered crust with s velocities increasing similarly with depth as the p waves the corresponding poisson s ratio is highly variable throughout the crust and ranges from 0 20 0 35 for the sedimentary cover to 0 22 0 25 for the crystalline crust the interpretation of the vp vs and poisson s ratio in petrological terms suggests a large variety of rocks from sand and clay to sandstone limestone and dolomite within the sedimentary cover within the crystalline crust the most probably rock types are granite granodiorite granite gneiss and or felsic amphibolite gneiss in the upper part and gneiss and or amphibolite in the lower part based on the 2 d seismic velocity model a density model is developed density values are assigned to each layer in agreement with the p wave velocity model and with values accepted for the geological units in the area after several iterations a good fit between the computed and observed bouguer anomalies was obtained along the seismic line

a crustal model for the eastern alps region and a new moho map in southeastern europe in the last two decades south central europe and the eastern alps have been widely explored by many seismic refraction experiments e g celebration 2000 alp 2002 sudetes 2003 although quite detailed images are available along linear profiles a comprehensive three dimensional crustal model of the region is still missing this limitation makes this region a weak spot in continental wide comprehensive representations of crustal structure to improve on this situation we select and collect 37 published active source seismic lines in this region after geo referencing each line we sample them along vertical profiles every 50 km or less along the line and derive p wave velocities in a stack of homogeneous layers separated by discontinuities depth of crystalline basement top of lower crust and moho we finally merge the information using geostatistical methods and infer s wave velocity and density using empirical scaling relations we present here the resulting crustal model for a region encompassing the eastern alps dinarides pannonian basin western carpathians and bohemian massif covering the region within 45 circ text 51 circ hbox n and 11 circ text 22 circ hbox e with a resolution of 0 2 circ times 0 2 circ we are also able to extend and update the map of moho depth in a wider region within 35 circ text 51 circ hbox n and 12 circ text 45 circ hbox e gathering moho values from the collected seismic lines other published dataset and using the european plate reference epcrust as a background all the digitized profiles and the resulting model are available online

postcollisional lithospheric evolution of the southeast carpathians comparison of geodynamical models and observations seismic evidence and thermal and topographic transients have led to the interpretation of lithospheric removal beneath the southeast carpathians region a series of numerical geodynamic experiments in the context of the tectonic evolution of the region are conducted to test the surface crustal response to lithosphere delamination and slab break off the results show that a delamination type removal plate like migrating instability causes a characteristic pattern of surface uplift subsidence and crustal extension shortening to occur due to the lithospheric deformation and dynamic thermal forcing of the sublithospheric mantle these features migrate with the progressive removal of the underlying lithosphere model results for delamination are comparable with observables related to the geodynamic evolution of the southeast carpathians since 10 ma the mantle structure inferred by seismic tomography migrating patterns of uplift 1 5 km and subsidence 2 km in the region crustal thinning in the carpathian hinterland and thickening at the focsani depression and regional extension in the carpathian corner e g opening of brasov basin correlating with volcanism e g harghita and persani volcanics in the last 3 myr

subsidence analysis and tectonic evolution of the external carpathian moesian platform region during neogene times abstract the miocene pliocene subsidence of the tectonic platforms in the romanian carpathians foreland is analysed using standard 1d backstripping techniques for individual wells combined in two regional sections and six contour maps the subsidence patterns were integrated together with previous paleostress and kinematic studies in order to derive the tertiary kinematics of the buried faults in the carpathians lower plate the study revealed accelerated subsidence during the early miocene in the western part of the moesian platform getic depression in direct relationship with the opening of a wsw ene trending extensional basin the largest subsidence recorded in the front of the carpathians took place during the late miocene due to final e ward emplacement of the thrust sheets the late miocene subsidence showed anomalous high values between the intramoesian and trotus faults as a result of the orogenic collision with the east european platform northward and acceleration of the subduction process in the se carpathians corner further pliocene subsidence continued only in the latter region the depocenter being shifted southward near the junction with the south carpathians foreland

architecture of the focsani depression a 13 km deep basin in the carpathians bend zone romania 1 in front of the se carpathians bend a very deep basin focsani depression developed in miocene to recent times an important part of its subsidence occurred after the main stages of thrusting in the carpathians apparently the basin lies in the wrong place and evolved in the wrong time in this study we constrain its architecture and evolution by analyzing a large database consisting of more than 1000 km two dimensional seismic lines and more than 60 wells around 13 km thick badenian to quaternary 16 5 myr sediments were deposited in the central part of the focsani depression during the badenian 16 5 13 myr the foreland south of trotus fault underwent ne sw directed extension and nw trending basins opened in the eastern moesian platform a nw se oriented area of subsidence stretched from the transylvania basin through the focsani depression to the se of the moesian platform while thrusting was going on in the east european scythian platform east carpathians and getic depression starting with the sarmatian 13 10 myr the focsani depression depocenter moved out of the carpathian belt coeval with the exhumation of the south and the east carpathians north of the trotus fault the basin became wider and was tilted toward the belt tilting was accompanied by dextral shearing mainly along the intramoesian and peceneaga camena faults after sarmatian times subsidence occurred practically only sse of trotus fault during meotian pontian 10 5 myr subsidence slowed down stronger pliocene quaternary subsidence is coeval with normal faulting and shearing in moesian platform the western margin of the focsani depression was then tilted eastward coeval with the exhumation of the bend zone and opening of the intramontane basins in the inner part of the belt

deep seismic soundings in romania this paper describes the deep seismic soundings performed in romania the technique of field works the characteristics of the recorded waves and the main results obtained on the profiles is analysed

slab in the wrong place lower lithospheric mantle delamination in the last stage of the eastern carpathian subduction retreat a model with a new type of delamination of the lower lithospheric mantle is proposed to explain the pliocene to recent tectonic evolution of the eastern carpathians we suggest that after the continental collision in middle miocene time break off of the west dipping subducting slab occurred at a depth of 70 km slab break off propagated horizontally toward the east inducing lithospheric delamination and movement of the vrancea slab into its present position delamination was followed by rapid asthenospheric rise resulting in magma generation and the explosive alkaline basaltic magmatism of the persani mountains contamination of the former subduction related magmatic reservoirs with the alkalic basaltic material and differentiation processes produced the harghita calc alkaline and shoshonitic rocks the asthenospheric rise induced crustal uplift which is the triggering mechanism for extension and formation of the brasov gheorghieni hinterland basins the extension was accommodated by shortening and folding in the foreland the vertical vrancea slab appears in our model as a segment of delaminated lower lithospheric mantle that is seismically active due to the ongoing pull of the eclogitized oceanic crust the model explains the displaced and shallow position of the slab relative to the eastern carpathian suture zone

kinematics of an arcuate fold thrust belt the southern eastern carpathians romania abstract flysch and molasse nappes of the eastern carpathians strike mainly n s and were folded and imbricated since the late early cretaceous boundaries of stratigraphic and structural units and calculated fold trend axes from the southern part of the eastern carpathians indicate a curvature of the orogen by 80 kinematic data from fault slip analysis of all nappe systems exposed in the arc document an overall nw se contraction nappes of the external moldavides nappe complex underwent deformation since the late cretaceous peaking in the miocene and exhibit fanning subhorizontal contraction axes from e w in the n striking part of the eastern carpathians through wnw ese and nw se in the northern part of the arc to nnw sse in its southwestern part geometric relations between faults and folds indicate that this fan pattern reflects an extended interval and was contemporaneous to nappe stacking and subsequent continental collision statistical analysis reveals correlation between orientation of the fanning kinematic axes and the structural trend where fanning of subhorizontal contraction axes is systematically smaller than change of strike of fold thrust structures orogen parallel extension in the tarcau nappe of the moldavides nappe complex is estimated to be 20 this low value of orogen parallel extension indicates a primary arc in contrast to bending of a previously straight fold thrust belt low orogen parallel extension and the observed pattern of structural and kinematic axes can be simulated in sand wedge indentation models where the indenter moves oblique to its margins in these models thrust traces and fold axes are curved around the arc but are parallel to the margins of the indenter away from the corner area the movement directions of the thrust faults in the models are deflected from normal to fault strike towards the movement direction of the indenter leading to fanning contraction directions similar to those observed in the eastern carpathian arc thus the main controlling factors on arc formation were the plate margin geometry i e the shape of the upper plate and the movement direction of the upper plate relative to the orientation of its margins the influence of the geometry of the continental margin in the lower plate was mainly by imposing constraints on the movement direction of the upper plate

high resolution teleseismic body wave tomography beneath se romania i implications for three dimensional versus one dimensional crustal correction strategies with a new crustal velocity model summary the calixto carpathian arc lithosphere x tomography experiment offers a dense high quality data set to study the lithospheric asthenospheric system underneath se romania an earthquake prone region in se europe to increase the image resolution of structures in the uppermost mantle the application of crustal traveltime corrections by a priori information before the teleseismic traveltime inversion has become a well accepted procedure for such a correction we present a regional 3 d crustal seismic velocity model that serves as the basis for a high resolution teleseismic tomography forthcoming paper by martin et al our 3 d crustal model is based on recent research in the region we collect new results from two long range seismic refraction lines 3 d refraction tomography and teleseismic ps conversions adding previously published models of the sediment distribution conrad and moho depths as well as crustal seismic p wave velocities we compile a 3 d crustal model for se romania this 3 d model does not contain shallow small scale heterogeneities 10 km but it reflects the large scale structures such as variations in sediment thickness average seismic velocities and 3 d moho depth it is well suited for the correction of teleseismic traveltime residuals a prerequisite for a high resolution teleseismic tomography study for example traveltime delays of up to 1 3 s are caused by the almost 20 km thick layer of sediments in the focsani basin such delays are comparable to or larger in size than the expected upper mantle traveltime residuals we study the significance of 3 d crustal traveltime corrections relative to 1 d station corrections and show that the complex basin structures in se romania require a 3 d approach to reduce the smearing of crustal anomalies into the mantle by modelling synthetic mantle structures with a slab as it is expected for se romania we also investigate how to adapt the inversion strategy if crustal corrections are applied significant improvements are found by including the already corrected crustal layers in the inversion procedure thereby enabling the inversion algorithm to project still remaining uncertainties in the less resolved upper crustal layers however the fixing of the upper layers during the inversion due to the a priori knowledge of the crustal velocity anomalies clearly leads to smearing of uncorrected anomalies that are possibly located close to the crust mantle boundary

3 d upper crustal tomographic structure across the vrancea seismic zone romania abstract the vrancea99 and vrancea2001 seismic refraction experiments are part of a multidisciplinary project to study the eastern carpathians in romania the objectives of these studies are intended to disclose a more detailed picture of the crustal and upper mantle structures above the seismically active vrancea region in this paper we provide additional constraints for the upper crustal structures of the area the 1999 campaign consisted of a 320 km long n s profile and a 70 km long e w profile the intersecting 2001 profile extended in e w direction from the hungarian border to the black sea in order to enhance the model resolution first arrival data from local crustal earthquakes were also included this configuration allowed for the first time to derive a 3 d velocity model for the upper crust of the romanian carpathian orogen within a 115 235 km wide region centred over the vrancea seismic zone the 3 d model reveals lateral velocity variations which were not visible on the in line interpretations it allows us to distinguish between foreland platform areas foreland basins and the carpathian orogen clear velocity differences between the foreland basins south and southeast of the eastern carpathians and the focsani basin further north indicate different pre miocene sedimentary compositions and geological evolutions of these foreland platforms the involved moesian and scythian platforms are separated by the trotus fault system which is observed as a velocity discontinuity an upper crustal high velocity zone above the northern vrancea seismic zone could also be identified this high velocity zone is explained by a middle pliocene to pleistocene e w oriented out of sequence thrust of the crystalline basement below the decollement of the flysch nappes

the moho depth map of the european plate summary the european plate has a 4 5 gy long and complex tectonic history this is reflected in the present day large scale crustal structures a new digital moho depth map is compiled from more than 250 data sets of individual seismic profiles 3 d models obtained by body and surface waves receiver function results and maps of seismic and or gravity data compilations we have compiled the first digital high resolution map of the moho depth for the whole european plate extending from the mid atlantic ridge in the west to the ural mountains in the east and from the mediterranean sea in the south to the barents sea and spitsbergen in the arctic in the north in general three large domains within the european plate crust are visible the oldest archean and proterozoic crust has a thickness of 40 60 km the continental variscan and alpine crust has a thickness of 20 40 km and the youngest oceanic atlantic crust has a thickness of 10 20 km

near vertical seismic reflection image using a novel acquisition technique across the vrancea zone and foscani basin south eastern carpathians romania the dacia plan danube and carpathian integrated action on process in the lithosphere and neotectonics deep seismic sounding survey was performed in august september 2001 in south eastern romania at the same time as the regional deep refraction seismic survey vrancea 2001 the main goal of the experiment was to obtain new information on the deep structure of the external carpathians nappes and the architecture of tertiary quaternary basins developed within and adjacent to the seismically active vrancea zone including the focsani basin the seismic reflection line had a wnw ese orientation running from internal east carpathians units across the mountainous south eastern carpathians and the foreland focsani basin towards the danube delta there were 131 shot points along the profile with about 1 km spacing and data were recorded with stand alone reftek 125s also known as btexansq supplied by the university texas at el paso and the passcal institute the entire line was recorded in three deployments using about 340 receivers in the first deployment and 640 receivers in each of the other two deployments the resulting deep seismic reflection stacks processed to 20 s along the entire profile and to 10 s in the eastern focsani basin are presented here the regional architecture of the latter interpreted in the context of abundant independent constraint from exploration seismic and subsurface data is well imaged image quality within and beneath the thrust belt is of much poorer quality nevertheless there is good evidence to suggest that a thick 10 km sedimentary basin having the structure of a graben and of indeterminate age underlies the westernmost part of the focsani basin in the depth range 10 25 km most of the crustal depth seismicity observed in the vrancea zone as opposed to the more intense upper mantle seismicity appears to be associated with this sedimentary basin the sedimentary successions within this basin and other horizons visible further to the west beneath the carpathian nappes suggest that the geometry of the neogene and recent uplift observed in the vrancea zone likely coupled with contemporaneous rapid subsidence in the foreland is detached from deeper levels of the crust at about 10 km depth the moho lies at a depth of about 40 km along the profile its poor expression in the reflection stack being strengthened by independent estimates from the refraction data given the apparent thickness of the meta sedimentary supracrustal units the crystalline crust beneath this area is quite thin b20 km supporting the hypothesis that

light absorbing impurities in snow cover across northern xinjiang china light absorbing impurities lais e g black carbon bc organic carbon oc mineral dust md deposited on snow cover reduce albedo and accelerate its melting northern xinjiang nx is an arid and semi arid inland region where snowmelt leads to frequent floods that have been a serious threat to local ecological security there is still a lack of quantitative assessments of the effects of lais on snowmelt in the region this study investigates spatial variations of lais in snow and its effect on snow albedo radiative forcing rf and snowmelt across nx results showed that concentrations of bc oc only water insoluble oc md ranged from 32 to 8841 ng g 1 77 to 8568 ng g 1 and 0 46 to 236 g g 1 respectively weather research and forecasting chemistry model suggested that residential emission was the largest source of bc snow ice and aerosol radiative modelling showed that the average contribution of bc and md to snow albedo reduction was 17 and 3 respectively rf caused by bc significantly exceeded rf caused by md in different scenarios changes in snow cover duration scd caused by bc and md decreased by 1 36 0 61 to 6 12 3 38 d compared with md bc was the main dominant factor in reducing snow albedo and scd across nx

2 5d seismic velocity modelling in the south eastern romanian carpathians orogen and its foreland 2 5 d seismic velocity modelling in the south easter romainan carpathians orogen and its foreland

late miocene quaternary volcanism tectonics and drainage system evolution in the east carpathians romania abstract middle miocene sarmatian convergence created the fold and thrust belt of the eastern carpathians of romania which subsequently experienced post collisional crustal deformation combined with calc alkaline and alkalic basaltic volcanism in late miocene quaternary time this deformation led to the rise of the c limani gurghiu harghita volcanic mountains and to the subsidence of the n s oriented intramontane borsec bilbor gheorgheni ciuc and brasov pull apart basins and the e oriented monocline related f g ras basin the regional drainage network is the composite of 1 older e se and s flowing rivers which cross the carpathians radiate towards the foreland and were probably established during the middle miocene sarmatian collision event 2 a more recent drainage system related to the contemporaneous development of the volcanoes and intramontaneous basins which generally drains westward into the transylvanian basin since late miocene time and has been capturing the older river system the older river drainage system has also been modified by late pliocene quaternary folding thrusting and monoclinal tilting along the pericarpathian orogenic front and by reactivated transverse high angle basement faults which cross the eastern carpathian foreland

paleostress characterization of the wallachian phase in its type area southeastern carpathians romania abstract the wallachian phase is defined in the east carpathians a convex to the east mountain belt in romania as a tectonic event occurring between pliocene and quaternary times this event formed folds and minor thrusts structures that are usually located in internal parts of the somewhat older fold and thrust belt structure this location contrasts with the location one would predict from their recent age and contrasts with the older cretaceous middle tortonian piggyback thrust mode of propagation in the southeastern carpathians this late overstep sequence of thrusting resulted from a modification in the stress field our data indicate that the direction of compression changed from nw se to n s during middle tortonian time this is further supported by stratigraphic dating of structures and thereby paleostresses indicating that the wallachian episode was not a brief event at the pliocene quaternary boundary but lasted from middle tortonian to early pleistocene

characteristics of romanian lithosphere from deep seismic reflection profiling abstract the tectonic units of romania contain both alpine orogenic regions and platforms the investigations of crustal structure by near vertical reflection seismic profiling are based on less than 100 lines unequally distributed and of limited lengths 5 30 km the seismic features studied are the crustal seismic reflectivity and transparency dipping events and diffractions and the moho and subcrustal reflectivity the major common features are a reflective sedimentary cover of mostly neogene layers a weak signal from the sedimentary basement boundary a quasi transparent upper crust a mid crust with short and subhorizontal events a transparent or layered lower crust and a moho that is either poorly visible or evidenced by a zone with reflection bands and some subcrustal reflections the moesian platform together with the adjacent carpathian foredeep show a mid crust with short and subhorizontal events a crust mantle transition zone in the west an unclear or prominent moho and some subcrustal reflectivity the northern part of the carpathian foredeep shows strong seismic layering of the lower crust the central part of the transylvanian depression is characterized by short and subhorizontal events at mid crustal level a slightly reflective lower crust with diffractions and a weak moho signal the southern sector of the pannonian depression is generally marked by a reflective lower crust the tectonic significance of these seismic signatures is interpreted as follows a brittle upper crust a decoupling mid crustal zone a lower crust with brittle to ductile behaviour a possible extensional or isostatic rebalanced moho and laminated zones with reduced viscosities at the lower crust and upper mantle levels a series of crustal models based on the reflection seismic sections are presented for several areas of romania

a note on the geochronology of the iberian alkaline province abstract a critical assessment of previously published ages and new k ar results for two complexes in the iberian alkaline province monchique and sintra lead to the conclusion that two separate magmatic episodes occurred around 72 and 82 ma since emplacement of these alkaline rocks is undoubtedly related to rifting and subsequent changes in the atlantic ocean floor spreading geometry accurate timing of magmatic events within the iberian alkaline province is of fundamental significance

late pliocene quaternary tectonics in the frontal part of the se carpathians insights from tectonic geomorphology abstract the romanian east carpathians display large scale heterogeneities along the mountain belt unusual foredeep geometries significant post collisional and neotectonic activity and major variations in topography mostly developed in the aftermath of late miocene sarmatian 11 ma subduction underthrusting and continental collision between the east european scythian moesian foreland and the inner carpathians tisza dacia unit in particular the se corner of the arcuate orogenic belt represents the place of still active large scale differential vertical movements between the uplifting mountain chain and the subsiding focsani foredeep basin in this key area we have analysed the configuration of the present day landforms and the drainage patterns in order to quantify the amplitude timing and kinematics of these post collisional late pliocene quaternary vertical movements a river network is incising in the upstream a high topography consisting of the external carpathians nappes and the pliocene lower pleistocene sediments of the foreland further eastwards in the downstream this network is cross cutting a low topography consisting of the middle pleistocene holocene sediments of the foreland geological observations and well preserved geomorphic features demonstrate a complex succession of geological structures the late pliocene holocene tectonic evolution is generally characterised by coeval uplift in the mountain chain and subsidence in the foreland at a more detailed scale these vertical movements took place in pulses of accelerated motion with laterally variable amplitude both in space and in time after a first late pliocene uplifting period subsidence took place during the earliest pleistocene resulting in a basal quaternary unconformity this was followed by two quantifiable periods of increased uplift which affected the studied area at the transition between the carpathians orogen and the focsani foreland basin in the late early pleistocene and the late middle to late pleistocene both large scale deformation events affected the western focsani basin flank tilting the entire structure with 9 during the late early pleistocene and uplifted it as a block during the early late pleistocene the late early pleistocene tilting resulted in 750 m uplift near the frontal monocline and by extrapolation in a presumed 3000 m uplift near the central parts of the carpathians the late middle to late pleistocene cumulative uplift reaches 250 m and correlates with a contemporaneous progradation of the uplifted areas towards the focsani basin the uplifting events are separated by a second quaternary unconformity on the whole the late pliocene quaternary evolution of the carpathians orogen focsani basin structure indicate large scale differential uplift during the latest stages of a continuous post collisional orogenic evolution

interplay of tectonics and neogene post collisional magmatism in the intracarpathian region abstract distribution of the neogene calc alkaline magmatism of the carpathian arc is directly related in space and time to the kinematics of the two major terranes of the intracarpathian area alcapa tisia getia along the south eastern border of the european plate in the west carpathians and adjacent areas the volcanic activity occurred between 20 11 ma with large volumes of both acidic and intermediate rocks generally distributed randomly sometimes transversally to the orogenic belt and as rare small occurrences along the flysch belt in the east carpathians the volcanic rocks are distributed along the northern margin of the zemplin block the north easternmost part of the alcapa and eastward along the front of the getic block at the contact with european plate between tokaj slanske vihorlat up to northern calimani mountains the magmatism occurred between 14 9 ma and along the calimani harghita chain between 9 0 2 ma the calc alkaline magmatic rocks of the apuseni mountains are located in the interior of the tisia block and occurred between 14 9 ma the generation of the calc alkaline magmatism is considered here as the result of complex interplay between plate roll back and lithospheric detachment tectonic processes and the break off of the subducted plate mostly in a post collisional setting 1 the magmatites of the western carpathians and the pannonian basin were generated in direct relation to subduction roll back processes over the downgoing slab during the period of lateral extrusion and back arc extension in this area characterized by maximum crustal shortening we can infer further delamination processes to explain the generation of magmas 2 the magmatic rocks from the northern sector of the east carpathians tokaj slanske vihorlat up to the northern calimani mountains resulted after subduction roll back processes and an almost simultaneous break off of the descending plate all along the arc segment during main clockwise rotation of the intracarpathian terranes 3 in the eastern sector of the east carpathians calimani up to harghita mountains the magmatic rocks were generated through partial melting of the subducted slab followed by gradual break off of the subducted plate along strike north to south 4 the apuseni mts magmatic activity resulted in transtensional tectonic regime by decompressional melting of lithospheric mantle during the translation and rotation of tisia getia block

models for relative motion of crustal blocks within the carpathian region based on restorations of the outer carpathian thrust sheets details of the oligocene present day motion of the adriatic block with respect to europe can be determined by palinspastic restorations of the outer carpathians thrust sheets the arcuate nature of the carpathians poses problems for simple restorations of sections because they create converging restoration paths which require large amounts of strike parallel extension 40 50 such large amounts of extension are not seen on maps or in the field a combination of thrust transport directions changing with time between and within thrust sheets and divergent transport directions helps minimise the arc parallel extension necessary 18 25 the pannonian basin can be treated either as an area dominated by strike slip motion rigid block movements or as an area of back arc extension the differences in restoration geometry produced by these two scenarios help to indicate which of the two mechanisms was dominant the consequences of the rigid block restoration indicate the model is inappropriate because it requires approximately 20 clockwise rotation of the adriatic block during the late tertiary it also indicates at least 300 km strike slip motion distributed among the late tertiary faults of the dinaride balkanide and hellenide mountain belts the back arc extension model alleviates the the 20 clockwise rotation of the adriatic block and requires about 200 km distributed strike slip motion in yugoslavia and bulgaria

crustal structure across the tesz along polonaise 97 seismic profile p2 in nw poland abstract the polonaise 97 po lish l ithospheric on set a n i nternational s eismic e xperiment 1997 seismic experiment in poland targeted the deep structure of the trans european suture zone tesz and the complex series of upper crustal features around the polish basin one of the seismic profiles was the 300 km long profile p2 in northwestern poland across the tesz results of 2d modelling show that the crustal thickness varies considerably along the profile 29 km below the palaeozoic platform 35 47 km at the crustal keel at the teisseyre tornquist zone ttz slightly displaced to the northeast of the geologic inversion zone and 42 km below the precambrian craton in the polish basin and further to the south the depth down to the consolidated basement is 6 14 km as characterised by a velocity of 5 8 5 9 km s the low basement velocities less than 6 0 km s extend to a depth of 16 22 km in the middle crust with a thickness of ca 4 14 km the velocity changes from 6 2 km s in the southwestern to 6 8 km s in the northeastern parts of the profile the lower crust also differs between the southwestern and northeastern parts of the profile from 8 km thickness with a velocity of 6 8 7 0 km s at a depth of 22 km to ca 12 km thickness with a velocity of 7 0 7 2 km s at a depth of 30 km in the lowermost crust a body with a velocity of 7 20 7 25 km s was found above moho at a depth of 33 45 km in the central part of the profile sub moho velocities are 8 2 8 3 km s beneath the palaeozoic platform and ttz and about 8 1 km s beneath the precambrian platform seismic reflectors in the upper mantle were interpreted at 45 km depth beneath the palaeozoic platform and 55 km depth beneath the ttz the polish basin is an up to 14 km thick asymmetric graben feature the basement beneath the palaeozoic platform in the southwest is similar to other areas that were subject to caledonian deformation avalonia such that the variscan basement has only been imaged at a shallow depth along the profile at northeastern end of the profile the velocity structure is comparable to the crustal structure found in other portions of the east european craton eec the crustal keel may be related to the geologic inversion processes or to magmatic underplating during the carboniferous permian extension and volcanic activity

crustal structure of the trans european suture zone region along polonaise 97 seismic profile p4 1 the large scale polonaise 97 seismic experiment investigated the velocity structure of the crust and upper mantle in the trans european suture zone tesz region between the precambrian east european craton eec and paleozoic platform that comprises terranes added during the caledonian and variscan orogenies 530 370 and 370 225 ma respectively this experiment included 64 shots recorded by 613 seismic stations during two deployments very good quality data were recorded along five profiles and the longest and most important one p4 is the focus of this paper clear first arrivals and later phases of waves reflected refracted in the crust and moho were interpreted using two dimensional 2 d tomographic inversion and ray tracing techniques the crustal thickness along the profile varies from 30 35 km in the paleozoic platform area to 40 km below and due northeast of the tesz to 43 km in the polish part of the eec and to 50 km in lithuania the paleozoic platform and eec are divided by the polish basin so the upper crustal structure varies considerably in the area of the polish basin the p wave velocity is very low vp 6 1 km s down to depths of 15 20 km indicating that a very thick sedimentary sequence is present we suggest two possible tectonic interpretations of the velocity models 1 baltica indented avalonia obducting its upper crust and underthrusting its lower crust in a tectonic flake structure and 2 a rifted margin of baltica underlies the polish basin this model is similar to other interpretations of seismic profiles recorded in the baltic sea the second model implies that the paleozoic platform solely consists of avalonian lithosphere and the eec of baltica lithosphere it offers a simple explanation of the difference in crustal thickness of the two platforms it also implies that the caledonian and variscan orogenies in this area were relatively soft collisions that left this continental margin largely intact

seismic crustal structure between the transylvanian basin and the black sea romania abstract in order to study the lithospheric structure in romania a 450 km long wnw ese trending seismic refraction project was carried out in august september 2001 it runs from the transylvanian basin across the east carpathian orogen and the vrancea seismic region to the foreland areas with the very deep neogene focsani basin and the north dobrogea orogen on the black sea a total of ten shots with charge sizes 300 1500 kg were recorded by over 700 geophones the data quality of the experiment was variable depending primarily on charge size but also on local geological conditions the data interpretation indicates a multi layered structure with variable thicknesses and velocities the sedimentary stack comprises up to 7 layers with seismic velocities of 2 0 5 9 km s it reaches a maximum thickness of about 22 km within the focsani basin area the sedimentary succession is composed of 1 the carpathian nappe pile 2 the post collisional neogene transylvanian basin which covers the local late cretaceous to paleogene tarnava basin 3 the neogene focsani basin in the foredeep area which covers autochthonous mesozoic and palaeozoic sedimentary rocks as well as a probably permo triassic graben structure of the moesian platform and 4 the palaeozoic and mesozoic rocks of the north dobrogea orogen the underlying crystalline crust shows considerable thickness variations in total as well as in its individual subdivisions which correlate well with the tisza dacia moesian and north dobrogea crustal blocks the lateral velocity structure of these blocks along the seismic line remains constant with about 6 0 km s along the basement top and 7 0 km s above the moho the tisza dacia block is about 33 to 37 km thick and shows low velocity zones in its uppermost 15 km which are presumably due to basement thrusts imbricated with sedimentary successions related to the carpathian orogen the crystalline crust of moesia does not exceed 25 km and is covered by up to 22 km of sedimentary rocks the north dobrogea crust reaches a thickness of about 44 km and is probably composed of thick eastern european crust overthrusted by a thin 1 2 km thick wedge of the north dobrogea orogen