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

seismic velocity model of the crust and upper mantle along profile pancake across the carpathians between the pannonian basin and the east european craton abstract results are presented of a seismic wide angle reflection refraction survey along a profile between the pannonian basin pb and the east european craton eec called pancake the p and s wave velocity model derived can be divided into three sectors the pb the carpathians including the transcarpathian depression and the carpathian foredeep and the south western part of the eec including the trans european suture zone tesz seismic data support a robust model of the vp velocity structure of the crust in the pb the 22 23 km thick crust consists of a 2 5 km thick sedimentary layer vp 2 4 3 7 km s 17 20 km thick upper crystalline crust 5 9 6 3 km s and an up to 3 km thick lower crustal layer vp 6 4 km s in the central part of the carpathians a 10 24 km thick uppermost part of the crust with vp 6 0 km s may correspond to sedimentary rocks of different ages several high velocity bodies vp 5 35 5 95 and 6 05 km s within the sedimentary flysch sequences may represent volcanic sequences the moho depth changes from 25 km to 45 km over ca 100 km distance beneath the carpathians west of tesz the cratonic crust has a typical three layer structure with a pronounced thickening of the lower crust towards the ukrainian shield where a high velocity lower crust vp 7 2 km s is observed two low velocity lenses in the upper crust of the eec are interpreted beneath major sedimentary troughs lviv and volyn podolsk mantle reflectors are observed at depths of 45 km and 75 km below the pb and 10 20 km below the moho in the eec sub moho pn velocities increase from 8 0 km s beneath the pb to 8 1 km s beneath the carpathians and to 8 3 km s beneath the eec s waves of acceptable quality are recorded in the eec their signal to noise ratios increase towards the ukrainian shield

mapping of c4 plant input from north west africa into north east atlantic sediments abstract mapping the abundance of 13c in leaf wax components in surface sediments recovered from the seafloor off northwest africa 0 35 n reveals a clear pattern of 13c distribution indicating systematic changes in the proportions of terrestrial c3 and c4 plant input at 20 n latitude we find that isotopically enriched products characteristic of c4 plants account for more than 50 of the terrigenous inputs this signal extends westward beneath the path of the dust laden sahara air layer sal high c4 contributions apparently carried by january trade winds also extend far into the gulf of guinea similar distributions are obtained if summed pollen counts for the chenopodiaceae amaranthaceae and the poaceae are used as an independent c4 proxy we conclude that the specificity of the latitudinal distribution of vegetation in north west africa and the pathways of the wind systems trade winds and sal are responsible for the observed isotopic patterns observed in the surface sediments molecular isotopic maps on the marine sedimentary time horizons e g during the last glacial maximum are thus a robust tool for assessing the phytogeographic changes on the tropical and sub tropical continents which have important implications for the changes in climatic and atmospheric conditions

an organic geochemical assessment of oceanographic conditions at manop site c over the past 26 000 years eleven sediment samples taken downcore and representing the past 26 kyr of deposition at manop site c 0 57 2 n 138 57 3 w were analyzed for lipid biomarker composition biomarkers of both terrestrial and marine sources of organic carbon were identified in general concentration profiles for these biomarkers and for total organic carbon toc displayed three common stratigraphic features in the time series 1 a maximum within the surface sediment mixed layer 4 ka 2 a broad minimum extending throughout the interglacial deposit and 3 a deep pronounced maximum within the glacial deposit using the biomarker records a simple binary mixing model is described that assesses the proportion of terrestrial to marine toc in these sediments best estimates from this model suggest that 20 of the toc is land derived introduced by long range eolian transport and the remainder is derived from marine productivity the direct correlation between the records for terrestrial and marine toc with depth in this core fits an interpretation that primary productivity at site c has been controlled by wind driven upwelling at least over the last glacial interglacial cycle the biomarker records place the greatest wind strength and highest primary productivity within the time frame of 18 to 22 kyr b p diagenetic effects limit our ability to ascertain directly from the biomarker records the absolute magnitude that different types of primary productivity have changed at this ocean location over the past 26 kyr

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

reconstructing in situ vegetation dynamics using carbon isotopic composition of biopolymeric residues in the central chinese loess plateau abstract carbon isotopic compositions of total organic carbon toc or leaf waxes in soils have been used to reconstruct past changes in the relative abundance of c 3 and c 4 plants however toc contains organic matter of different source organisms plants animals fungi bacteria etc and its isotopic ratios could be modified during diagenesis since different organic fractions e g carbohydrates proteins lipids etc have different isotopic ratios and degradation rates leaf waxes on the other hand are transported by wind and hence represent vegetation input from a large geographic area we report in this paper a new approach to extract in situ paleovegetation information from late quaternary paleosols by determining carbon isotopic compositions of biomarkers derived from aliphatic bio and geopolymers of plant origin we show that c 9 to c 17 n alkenes derived from aliphatic bio and geopolymers are the dominant compounds released by flash pyrolysis of insoluble organic matter isolated from the late quaternary paleosols in the chinese loess plateau because the aliphatic polymeric substances are mainly derived from plant leaves bark and roots the isotopic signatures of these alkenes determined using pyrolysis gas chromatography isotopic ratio mass spectrometry reflect in situ vegetation changes our down core 13 c data from the xifeng loess paleosol profile show significant coherence among biopolymer derived n alkenes leaf wax n alkanes and toc for the past 40 kyr however the different amplitudes of the temporal isotopic changes among these data sets are indicative of variability in in situ and regional vegetation dynamics organic sources and effect of diagenesis our data also imply that below ground biomass is a major source of soil organic matter in the central china loess sediment

reconstruction of late glacial and holocene climate evolution in southern china from geolipids and pollen in the dingnan peat sequence we have carried out a multi proxy analysis of a radiocarbon dated peat core that records the history of paleoclimate change dating from 18 ka in the dingnan region of southern china fatty acid and hydrocarbon distributions total organic carbon toc concentrations pollen assemblages and sediment lithology reveal a succession of three major paleoclimate intervals plant waxes are the predominant origin of the n alkanoic acid and n alkane compositions of this sedimentary sequence contributions of these geolipid components vary relative to toc and with changes in lithology and help to refine a pollen based reconstruction of local paleoclimate evolution a period of cool and fairly wet climate 15 630 10 450 cal abp follows accumulation of coarse fluvial sediments under relatively dry deglacial conditions the second period 10 450 6040 cal abp experienced the warmest climate and the highest precipitation indicated by a minimum c18 1 c18 0 ratio together with the low cpi values of n alkanes and high acl values the third time interval 6040 3800 cal abp was a moderately dry and cool period the climate record of the most recent period 3800 cal abp is obscured by agricultural disturbance the younger dryas 12 900 11 600 cal abp appears in this record as a period of variable and very wet climate during the interval 10 450 6040 cal abp both temperature and the precipitation evaporation ratio maximized therefore we consider this period to represent the holocene optimum which coincides with that of the northern hemisphere moreover our results do not fit the spatially asynchronous pattern of the east asian monsoon holocene optimum in china suggested by previous studies they instead parallel the pattern of global paleoclimate change and consequently show that the evolution of holocene paleoclimate in southern china is consistent with changes in northern hemisphere solar radiation

velocity analysis by iterative profile migration in conventional seismic processing velocity analysis is performed by using the normal moveout nmo equation which is based on the assumption of flat horizontal reflectors imaging by migration either before or after stack is done normally in a subsequent step using these velocities in this paper velocity analysis and imaging are combined in one step and migration itself is used as a velocity indicator because unlike nmo migration can be formulated for any velocity function migration based velocity analysis methods are capable of handling arbitrary structures i e those with lateral velocity variations in the proposed scheme each shot gather profile is migrated with an initial depth velocity model profile migration is implemented in the x domain but the actual implementation of profile migration is not critical as long as it is not done in a spatial wavenumber domain which would preclude handling of lateral velocity variations after migration with an initial velocity model the

thermochronologic evidence for orogen parallel variability in wedge kinematics during extending convergent orogenesis of the northern apennines italy analysis of 146 new apatite u th he ages six new apatite fi ssion track ages and 165 previously published apatite fi ssiontrack aft ages from the northern apennine extending convergent orogen reveals a signifi cant along strike change in post late miocene wedge kinematics and exhumation history east of 11 30 e age patterns and age elevation relationships are diagnostic of ongoing frontal accretion and slab retreat consistent with a northeastward migrating orogenic wave enhanced erosion rates of 1 mm yr over a period of 3 5 ma are recorded on the contractional pro side of the orogen and 0 3 mm yr on the extending retro side west of 11 30 e ongoing exhumation has been restricted to the range core since at least ca 8 ma at rates of 0 4 mm yr increasing to 1 mm yr in the pliocene ca 3 ma accompanied by post pliocene tilting and associated faulting this pattern can be attributed to either continued convergence but a switch in the transfer of material into the wedge to a regime dominated by underplating or out of sequence shortening or a slowdown or cessation of frontal accretion and slab retreat with enhanced pliocene uplift and erosion triggered by a deeper seated process such as lithospheric delamination complete slab detachment or slab tear these fi ndings emphasize that no single model of wedge kinematics is likely appropriate to explain long term northern apennine orogenesis and synconvergent extension but rather that different lithospheric geodynamic processes have acted at different times in different lateral segments of the orogen

neogene quaternary magmatism and geodynamics in the carpathian pannonian region a synthesis in the carpathian pannonian region in neogene times westward dipping subduction in a land locked basin caused collision of two lithospheric blocks alcapa and tisia with the southeastern border of the european plate calc alkaline and alkaline magmatism was closely related to subduction rollback collision and extension from the spatial distribution of the magmatic activity four segments can be defined western segment magmatism occurring on the alcapa block central segment magmatism occurring on both alcapa and the tisia blocks south eastern segment and interior segment both on the tisia block most calc alkaline magmatism in the region resulted from melting of a heterogeneous asthenospheric mantle source modified by addition of fluids and sediment assimilation and fractionation processes at shallow crustal levels occurred in most of the segments strongly masking the deeper source processes long term subduction rollback and or delamination led to contamination of the asthenosphere beneath the western segment here large volume partial melts of the contaminated mantle caused underplating and crustal anatexis leading to mixing of mantle derived calc alkaline magmas with crustal melts in the central segment calc alkaline magmas were formed by subduction and rollback followed by back arc extension and slab breakoff avariable mantle source is indicated in the back arc setting and larger amount of fluid induced metasomatism source enrichment and assimilation nearer to the trench in the interior segment evolution from typical calc alkaline magmas to adakite like ones was related to extension due to fast rotations and transtensional tectonics here calc alkaline magmas formed by decompression melting of a heterogeneous crust mantle lithosphere while adakite like melts resulted from fliud dominated melting of the lithosphere along the south eastern segment slab breakoff was responsible for the generation of typical calcalkaline magmas but in the extreme south of the segment shallow level tearing of the slab followed breakoff strike slip tectonics allowed the rise of hot asthenosphere and generation of adakite like magmas via slab melting along the torn edge of the east european plate alkalic basaltic volcanism with an oib like asthenosphere source followed the calc alkaline stage

wave equation migration velocity analysis i theory we present a migration velocity analysis mva method based on wavefield extrapolation similarly to conventional mva our method aims at iteratively improving the quality of the migrated image as measured by the flatness of angle domain common image gathers adcigs over the aperture angle axis however instead of inverting the depth errors measured in adcigs using ray based tomography we invert image perturbations using a linearized wave equation operator this operator relates perturbations of the migrated image to perturbations of the migration velocity we use prestack stolt residual migration to define the image perturbations that maximize the focusing and flatness of adcigs our linearized operator relates slowness perturbations to image perturbations based on a truncation of the born scattering series to the first order term to avoid divergence of the inversion procedure when the velocity perturbations are too large for born linearization of the wave equation we do not invert directly the image perturbations obtained by residual migration but a linearized version of the image perturbations the linearized image perturbations are computed by a linearized prestack residual migration operator applied to the background image we use numerical examples to illustrate how the backprojection of the linearized image perturbations i e the gradient of our objective function is well behaved even in cases when backprojection of the original image perturbations would mislead the inversion and take it in the wrong direction we demonstrate with simple synthetic examples that our method converges even when the initial velocity model is far from correct in a companion paper we illustrate the full potential of our method for estimating velocity anomalies under complex salt bodies

microbial communities and lipid records of the linxia basin ne tibetan plateau implications for enhanced aridity in the late miocene abstract the linxia basin on the north eastern tibetan plateau in northwest china bears continuous and thick lacustrine fluvial sediments with environmental significance to central asian aridification however limited efforts have been made on investigating the microbial community evolution even though lipid biomarkers have been successfully employed to reconstruct paleoenvironmental conditions in this area this study used the ancient dna and n alkanes preserved in the lacustrine fluvial sediments from the linxia basin and employed high throughput sequencing and geochemical analyses to understand the climatic conditions spanning the past 29 million years the characteristics of n alkanes indicate that the organic matter was derived from mixed sources bacteria algae and higher plants and a series of n alkane proxies acl n c21 n c22 paq and pwax established that the climate shifted to arid conditions at approximately 8 ma it is noteworthy that the relative abundance trends of two classes of microbes proteobacteria and firmicutes were negatively correlated furthermore the increasing firmicutes and the relatively decreasing proteobacteria at approximately 8 ma also corroborated this arid event in addition during this period there was an extremely low abundance of archaea which might correspond to severe climatic conditions around 8 ma therefore this study suggests that the microbial communities could serve as a potential tool for the reconstruction of paleoenvironments

towards a mechanical model for the formation of the pannonian basin abstract new maps showing crustal and lithospheric thickness variations in the pannonian basin and the surrounding east alpine carpathian and dinaric mountains have been prepared on the basis of recent seismic seismologic and electromagnetic data a map presenting miocene faults of regional significance has been also constructed for the same region by using a wealth of recently available national and or more local studies it is suggested that observed crustal and lithospheric structural contrasts have been controlled primarily by neogene kinematic history of the region kinematic history is characterized by the following main patterns 1 1 indentation by adria and large scale backthrusting in the southern alps 2 2 eastward escape and extension of the eastern alps 3 3 extensional collapse in the pannonian basin area 4 4 formation of broad wrench fault systems along strike in the dinarides and southern carpathians and the western carpathians with dextral and sinistral shear respectively 5 5 compression and accretion of the external thrust and fold belt in the eastern carpathians these kinematic patterns are thought to be interrelated and all are manifestations of the late stage evolution of an overthickened orogenic wedge in order to arrive at a better understanding of the mechanism of extension which formed the pannonian basin deep crustal seismic profiles hydrocarbon exploration reflection lines and borehole data have been analyzed in the little hungarian plain this plain represents the transition zone between the alps and the pannonian lowlands and the results are illustrated by eight interpreted cross sections one result of regional importance is the clear recognition that the transdanubian central range at the southeastern flank of the little hungarian plain is composed of alpine pre senonian thrust sheets this finding marks the end of a century of debate the allochthony of the substrata of the pannonian basin can be now considered proven another result of more general interest is that these cross sections document the mode of lithospheric extension preexisting compressional detachment planes reactivate as low angle normal faults and lead to tectonic unroofing of deeply buried metamorphic terranes characterized by ductile flow along subhorizontal lineation

composition and provenance of terrigenous organic matter transported along submarine canyons in the gulf of lion nw mediterranean sea abstract previous projects in the gulf of lion have investigated the path of terrigenous material in the rhone deltaic system the continental shelf and the nearby canyon heads this study focuses on the slope region of the gulf of lion to further describe particulate exchanges with ocean s interior through submarine canyons and atmospheric inputs nine sediment traps were deployed from the heads to the mouths of lacaze duthiers and cap de creus submarine canyons and on the southern open slope from october 2005 to october 2006 sediment trap samples were analyzed by cuo oxidation to investigate spatial and temporal variability in the yields and compositional characteristics of terrigenous biomarkers such as lignin derived phenols and cutin acids sediment trap data show that the dense shelf water cascading event that took place in the months of winter 2006 january february and march had a profound impact on particle fluxes in both canyons this event was responsible for the majority of lignin phenol 55 4 and cutin acid 42 8 inputs to submarine canyons with lignin compositions similar to those measured along the mid and outer continental shelf which is consistent with the resuspension and lateral transfer of unconsolidated shelf sediment to the canyons the highest lithogenic normalized lignin derived phenols contents in sediment trap samples were found during late spring and summer at all stations i e 193 46 g vp g 1 lithogenic at deep slope station when river flow wave energy and total particle fluxes were relatively low during this period lignin compositions were characterized by elevated cinnamyl to vanillyl phenol ratios 3 at almost all stations high p coumaric to ferulic acid ratios 3 and high yields of cutin acids relative to vanillyl phenols 1 all trends that are consistent with high pollen inputs our results suggest marked differences in the sources and transport processes responsible for terrigenous material export along submarine canyons mainly consisting of fluvial and shelf sediments during winter and atmospheric dust inputs during spring and summer

controls of structural inheritance on orogenic curvature and foreland basin sedimentation insights from the przemyśl area western carpathians abstract orogenic curvatures can have various origins and are widely debated worldwide in the poland ukraine border area the outer western carpathians are characterized by a marked curvature the origin of this curvature was analysed by integrating stratigraphic information with structural constraints and anisotropy of the magnetic susceptibility ams data hangingwall frontal ramp domains are characterized by a relatively simple deformation dominated by layer parallel shortening and folding around a regional nw se trending axis recorded by an ams lineation with a similar trend on the other hand the n s trending hangingwall oblique ramp domain is characterized by maximum ams axes recording transpressional strain either dominated by simple shear sub horizontal ams lineation or pure shear steeply plunging ams lineation components early miocene basin inversion with two distinct depocentres created a number of different detachment surfaces and thickness variations for the sedimentary successions involved in thrusting the main depocentre of the lower middle miocene foredeep was originally located in the recess area of the curved carpathian front on the other hand the occurrence of a salient to the west resulted in the axial zone of the foreland flexure being filled with allochthonous units thereby dramatically reducing the accommodation space for foredeep sediments in this area our results suggest that thrust belt geometry was controlled by the inherited mesozoic extensional basin architecture

α emitting mineral inclusions in apatite their effect on u th he ages and how to reduce it u th rich mineral inclusions in apatite are often held responsible for erroneously old u th he ages because they produce parentless he three aspects associated with this problem are discussed here first simple dimensional considerations indicate that for small mineral inclusions the parentless helium problem might not be as serious as generally thought for example a mineral inclusion that is 10 the length width and height of its host apatite needs to be a thousand times more concentrated in u and th to produce an equal amount of he therefore single isolated inclusions smaller than a few m are unlikely to contribute significant helium for larger or more abundant inclusions the parentless helium problem can be solved by dissolution of the apatite and its inclusions in hot hf second besides creating parentless helium inclusions also complicate ejection corrections mathematical exploration of this latter problem for spherical geometries reveals that for randomly distributed inclusions the probability distribution of single grain ages is predicted to have a sharp mode at the mean age with tails towards younger and older ages multiple grain measurements will yield accurate and precise age estimates if 10 or more randomly distributed emitting mineral inclusions are present in a sample third thermal modeling indicates that mineral inclusions have a non trivial but minor 5 c effect on the closure temperature these predictions were tested on apatites from rapidly cooled migmatites of naxos greece which contain abundant u rich zircon inclusions thirty seven samples were subjected to two kinds of treatment the pooled age i e the synthetic multi grain age computed from a number of single grain analyses of four inclusion free samples 13 apatites prepared in hno3 is 10 9 ma close to apatite and zircon fission track ages from the same rock u th he ages of 14 inclusion bearing samples dissolved in hno3 range between 9 and 45 ma with a pooled age of 22 6 ma the ages of 19 hf treated samples range between 5 and 16 ma with 10 of 14 single grain samples between 9 and 13 ma and a pooled age of 10 9 ma these observations agree with the theoretical predictions and support the addition of hf treated apatite u th he dating to the thermochronological toolbox

kinematic artifacts in prestack depth migration strong refraction of waves in the migration velocity model introduces kinematic artifacts coherent events not corresponding to actual reflectors into the image volumes produced by prestack depth migration applied to individual data bins because individual bins are migrated independently the migration has no access to the bin component of slowness this loss of slowness information permits events to migrate along multiple incident reflected ray pairs thus introducing spurious coherent events into the image volume this pathology occurs for all common binning strategies including common source common offset and common scattering angle since the artifacts move out with bin parameter their effect on the final stacked image is minimal provided that the migration velocity model is kinematically correct however common image gathers may exhibit energetic primary events with substantial residual moveout even with the kinematically accurate migration velocity model

latitudinal change of normal paraffin composition in the northwest pacific sediments abstract we analyzed normal saturated paraffins n paraffins in 70 surface sediments in the northwest pacific to examine the spatial distribution of organic materials all sediments show bimodal n paraffin abundance patterns against carbon number with maxima at c 16 and c 31 indicating that n paraffins in marine sediments are a mixture of long chain n paraffins from land based higher plant waxes and short ones from marine organisms we observed in this study a significant change of carbon preference index cpi from 2 5 in low latitudes to 4 5 in mid high latitudes around 19 25 n the following influences are discussed as the cause of cpi offset between low and mid high latitudes 1 meteorological conditions 2 n paraffin composition of higher land plants 3 contribution of petroleum components and 4 mixing ratio of higher land plants and marine organisms however none of them can be the possible cause of the cpi offset because n paraffin content and composition vary significantly according to the species of a bacterium difference of the species of bacterial communities between low and mid high latitudes may be a possible reason for the cpi offset found in sediment from the northwest pacific

diagenetic thermal evolution of organic matter by raman spectroscopy abstract vitrinite reflectance is considered one of the most reliable indicators of thermal maturity in sedimentary basins and is widely used to calibrate numerical models that assess hydrocarbon generation expulsion from source rocks nevertheless ambiguities in vitrinite reflectance can occur from variations in composition and preservation state of organic facies temperature pressure conditions and the abundance of organic matter resulting in incorrect or uncertain assessments of petroleum systems this study presents an original application of raman spectroscopy to assess the diagenesis catagenesis of kerogen between the immature and mid mature stages of hydrocarbon generation kerogens were isolated from 33 intervals of drill cuttings from a 5 km thick oligocene miocene siliciclastic section of the malembo formation lower congo basin angola their raman spectra were obtained and derived parameters were compared to depth and to previously reported equivalent vitrinite reflectance values the best correlations between thermal maturity and raman parameters were found for d g band distance fwhm of the g band d g area ratio ra2 ratio calculated as s dl d dr gl g band ratio and the d g width ratio the raman parameters were not influenced by varying kerogen composition mixed type ii iii the technique offers the potential to reduce the risk of source rock thermal maturity assessment even when organic facies rich in amorphous organic matter are present

burial and exhumation history of the polish outer carpathians discriminating the role of thrusting and post thrusting extension abstract several tectonic processes have been proposed to be important in the alpine to the recent evolution of the polish outer carpathians i e paleogene neogene thrusting post thrusting extension quaternary reactivation of compression this work tests the effect of these processes on exhumation of the wedge in order to verify their timing and relative role in shaping the polish outer carpathians aft ahe and zhe analyses were performed on samples collected along the study region this allowed the reconstruction of their post depositional minimum heating depth of burial and timing of cooling and exhumation after deposition samples from the innermost units were heated up to temperatures of ca 60 120 c ca 4 9 km whereas samples from the outer units were heated to temperatures lower than 60 c ca 4 km cooling and exhumation occurred progressively later from west to east between ca 25 and 10 ma in the western sector between ca 15 and 5 ma in the eastern sector these results have been put in relationship with single structural features to understand the relative role of thrusts and normal faults in the eastern sector of the study region samples at the footwall of significant normal faults show a higher degree of reset and younger ages than samples located at the hangingwall this implies that in this sector extensional tectonics played an important role in exhumation however proper tectonic exhumation only had a minor role the major exhumation mechanism being erosion which is enhanced in the footwalls and reduced in the hangingwalls in the western sector of the polish outer carpathians only in few cases evidence of enhanced erosion to the footwall of major normal faults could be observed based on the present data in this region the wedge exhumed mainly as a response to thrusting and normal faulting only played a minor role locally modifying the pattern of erosion finally no major exhumation events occurred after miocene pointing to a minor relevance of recent compression unreset zhe dates were used to estimate exhumation of source rocks through the zhe prz and to outline the provenance of sediments forming the polish outer carpathians exhumation occurred both in response to the variscan late devonian to triassic and alpine late jurassic to early paleocene orogeneses suggesting sedimentary provenance both from the southern margin and from the basement heights within the outer carpathian basin

interplay between the thermal evolution of an orogenic wedge and its retro wedge basin an example from the ukrainian carpathians the carpathian pannonian region is made up of the wide extensional pannonian basin surrounded by the carpathian mountain belt the pannonian basin formed in the miocene by extension in a retro wedge position while thrusting was still active at the carpathian front the ukrainian region is an ideal area to reconstruct the relationship between the pannonian basin and the carpathians due to the relatively simple structural setting and to the progressive but neat transition between the two domains this study uses low temperature thermochronometry and vitrinite reflectance analysis to investigate the effect of the opening of the pannonian basin on the thermal and burial exhumation histories of the ukrainian carpathians the results show heating and burial maxima in the central units of the wedge up to 170 c and 6 km respectively tapering out toward both the innermost and the outermost thrust sheets cooling and exhumation occurred by means of a first rapid stage between ca 12 and 5 ma exhumation rates of up to 1 mm yr followed by a slower stage from ca 5 ma to the present exhumation rates within 0 5 mm yr timing and spatial pattern of exhumation are compatible with post thrusting erosion enhanced by isostatic uplift the extent of exhumation progressively decreases toward the pannonian basin characterized by a thinned crust no further significant influence of the pannonian basin opening on the thermal and burial history of the ukrainian carpathians may be inferred based on our results whereas the comparison of the tectonothermal evolution of the two domains suggests that they are both controlled by the same lithospheric processes

a method for estimating apparent displacement vectors from time lapse seismic images reliable estimates of vertical inline and crossline components of apparent displacements in time lapse seismic images are difficult to obtain for two reasons first features in 3d seismic images tend to be locally planar and components of displacement within the planes of such features are poorly resolved second searching directly for peaks in 3d crosscorrelations is less robust more complicated and computationally more costly than searching for peaks of 1d crosscorrelations i estimate all three components of displacement with a process designed to mitigate these two problems i address the first problem by computing for each image sample a local phase correlation instead of a local crosscorrelation i address the second problem with a cyclic sequence of searches for peaks of correlations computed for lags constrained to one of the three image axes

fluid inclusions in marmarosh diamonds evidence for tectonic history of the folded carpathian mountains ukraine abstract fissures in the nappes of the folded carpathians contain euhedral quartz crystals known as marmarosh diamonds study of marmarosh diamonds collected from the nappes in the ukrainian part of the carpathians showed that these quartz crystals contain abundant primary syngenetic methane rich and aqueous inclusions many of the early inclusions show evidence of explosion decrepitation under conditions of internal overpressure caused by tectonic uplift of the enclosing sediments during miocene times regional mapping of morphologic and microthermometric characteristics of inclusions indicates that the decrepitated inclusions display characteristic textural features and homogenization temperature patterns within the different nappes suggesting that the various nappes have experienced significantly different burial uplift histories thus inclusions reveal an increase in depth of burial from the inner regions of the folded flysch carpathians towards the outer regions about 2 km for the marmarosh nappe 5 km for the rahiv nappe 7 km for the porculec and chornogora nappes and 10 km for the krosno zone the corresponding average geothermal gradients decreased from about 40 45 c km for the marmarosh nappe to about 20 25 c km the krosno zone it is also concluded that the marmarosh nappe followed a p t path close to the original inclusion isochore because inclusions from quartz crystals collected within this nappe show no evidence of decrepitation on the other hand inclusions in quartz from the krosno zone show very intense explosion features and the highest fluid densities that have been recorded for the region suggesting that the krosno zone was the most buried part of the ukrainian folded carpathians during formation of the inclusions

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

cenozoic structural evolution thermal history and erosion of the ukrainian carpathians fold thrust belt abstract the carpathians are part of the alpine carpathian dinaridic orogen surrounding the pannonian basin their ukrainian part constitutes an ancient subduction accretion complex that evolved into a foreland fold thrust belt with a shortening history that was perpendicular to the orogenic strike herein we constrain the evolution of the ukrainian part of the carpathian fold thrust belt by apatite fission track dating of sedimentary and volcanic samples and cross section balancing and restoration the apatite fission track ages are uniform in the inner southwestern part of the fold thrust belt implying post shortening erosion since 12 10 ma the ages in the leading and trailing edges record provenance i e sources in the trans european suture zone and the inner carpathians respectively and show that these parts of the fold thrust were not heated to more than 100 c syn orogenic strata show sediment recycling in the interior of the fold thrust belt the most thickened and most deeply eroded nappes the apatite ages were reset eroded and redeposited in the syn orogenic strata closer to the fore and hinterland the lag times are only a few million years two balanced cross sections one constructed for this study and based on field and subsurface data reveal an architecture characterized by nappe stacks separated by high displacement thrusts they record 340 390 km shortening a kinematic forward model highlights the fold thrust belt evolution from the pre contractional configuration over the intermediate geometries during folding and thrusting and the post shortening erosional unloading configuration at 12 10 ma to the present day geometry average shortening rates between 32 20 ma and 20 12 ma amounted to 13 and 21 km ma respectively implying a two phased deformation of the ukrainian fold thrust belt

tertiary subduction and slab break off model of the carpathian pannonian region abstract this paper illustrates the application of multidisciplinary data analysis to the carpathian pannonian region and presents a new tertiary development model that incorporates all multidisciplinary parameters during the late cretaceous eocene the future carpathian orogen was part of the larger alpine carpathian orogen formed by the southeastward subduction 135 55 ma of the penninic ocean and the ultimate collision 55 40 ma of the european and adriatic continents the subduction in the alpine region ended by the slab break off of the subducting oceanic lithosphere from the continental one and by the related magmatism 43 24 ma while the eocene alps were under continental collision the eocene remnant carpathian flysch basin rcfb was still subducting the carpathians and eastern parts of the alps started to occupy the region of the present carpathians during the early miocene the oceanic plate underlying the rcfb subducted southwestwards later westwards while the northeastward and eastward migration velocity of the accreting plate boundary decreased through time the slower subduction rate caused a steeper dip of the subducting slab the beginning of the eggenburgian 22 19 ma and following duration of extension in the orogenic hinterland accompanied by the asthenosphere upwelling the onset of the crustally derived volcanism above the risen asthenosphere and the younger mantle derived volcanism progressively less contaminated by the crustal material all contemporaneous with a shortening in the carpathian accretionary wedge the subduction of the rcfb finally led at the end of the early miocene to a collision with the continental margin along the westernmost part of the present carpathian arc the subduction roll back of the subducting slab of the rcfb under the advancing inner carpathians the oblique closure of the basin the progressive change of the subduction to collision from the west to the east along the carpathian arc drove a scissors like break off of the subducting oceanic slab along the west carpathians the break off in the east carpathians was driven by the weight of a subducting oceanic slab and buoyancy of the attached continental slab the break off started in the west of the carpathian arc in the early miocene ran along the arc to its present position in the bend area between the east and south carpathians and separated the oceanic slab that subducted passively under its own weight from the european continental margin the lateral propagation rate of the slab tear decreased with time the break off related volcanism was synchronous with the final stages of the collision

wave equation reflection traveltime inversion with dynamic warping and full waveform inversion abstractin reflection seismology full waveform inversion fwi can generate high wavenumber subsurface velocity models but often suffers from an objective function with local minima caused mainly by the absence of low frequencies in seismograms these local minima cause cycle skipping when the low wavenumber component in the initial velocity model for fwi is far from the true model to avoid cycle skipping we discovered a new wave equation reflection traveltime inversion werti to update the low wavenumber component of the velocity model while using fwi to only update high wavenumber details of the model we implemented the low and high wavenumber inversions in an alternating way in werti we used dynamic image warping diw to estimate the time shifts between recorded data and synthetic data when compared with correlation based techniques often used in traveltime estimation diw can avoid cycle skipping and estimate the time shifts accurately even when shifts vary rapidly hence by minimizing tr

abrupt wind regime changes in the north atlantic ocean during the past 30 000 60 000 years 1 the inputs of higher plants in blake outer ridge subtropical western north atlantic during marine isotope stage 3 mis3 have been recorded at high resolution by quantification of c23 c33 odd carbon numbered n alkanes and c20 c30 even carbon numbered n alkan 1 ols in sediment sections of ocean drilling program site 1060 the changes of these proxies at this open marine site are mainly related to eolian inputs their concentrations and fluxes exhibit major abrupt variations that are correlated with dansgaard oeschger d o patterns in greenland ice cores the ratios between interstadials and stadials range between 2 and 9 times the intense flux increases in the d o stadials are linked to strong enhancements of the westerly wind regime at these subtropical latitudes during stadials the observed variation was paralleled by changes in wind blown dust and the polar circulation index in greenland ice which is in agreement with previously hypothesized atmospheric teleconnections between northern and middle low latitudes of the northern hemisphere the close correspondence between sedimentary and ice core proxies is evidence that crossings of the glacial climate thresholds involved major reorganizations of the troposphere the observed large rise in higher plant biomarkers indicates that climate stabilization in the d o stadial conditions led to main increases in wind intensity

p wave tomography of the mantle under the alpine mediterranean area 1 we study the upper mantle p wave velocity structure below the euro mediterranean area down to 1000 km depth by seismic travel time tomography we invert summary residuals constructed with both regional and teleseismic first arrival data reported by the international seismological centre isc 1964 1995 introducing some alternative strategies in the travel time tomographic approach and a new scheme to correct teleseismic data for global mantle structure our high resolution model pm0 5 is parameterized with three dimensional 3 d linear splines on a grid of nodes with 0 5 spacing in both horizontal directions and 50 km vertical spacing we obtain about 26 root mean square rms reduction of residuals by inversion in addition to roughly 31 reduction after summary rays formation and selection sensitivity analyses are performed through several test inversions to explore the resolution characteristics of the model at different spatial scales the distribution of large scale fast anomalies suggests that two different stages of a convection process presently coexist in very close regions the mantle dynamics of western central europe is dominated by blockage of subducted slabs at the 660 km discontinuity and ponding of seismically fast material in the transition zone contrarily in the eastern mediterranean fast velocity material sinks into the lower mantle suggesting that the flow of the cold downwelling here is not blocked by the 660 km discontinuity on a smaller scale the existence of tears in the subducted slab lithospheric detachment all along both margins of the adriatic plate as proposed by some authors is not supported by our tomographic images

a comparison of sedimentary aliphatic hydrocarbon distribution between the southern okinawa trough and a nearby river with high sediment discharge twelve surface sediments from the southern okinawa trough ot and nine surface sediments from a nearby river the lanyang river lr with high sediment discharge were analyzed for comparison of their aliphatic hydrocarbon distributions performing cluster analysis on all hydrocarbon data of lr and ot sediments showed that the two areas had a similarity level of only 0 15 meaning that they were quite dissimilar the average ratio of terrigenous to aquatic n alkanes was 0 99 for lr sediments and 9 64 for ot sediments indicating that the concentrations of n alkanes in lr and ot sediments were quite different furthermore the mean pristane phytane ratios for lr and ot sediments were 1 01 and 2 57 respectively the difference between them was significant student s t test at the 99 significance level the carbon preference index cpi of c25ec33 n alkanes averaged 3 26 range 2 16e4 59 for lr sediments and 2 92 range 2 35e5 24 for ot sediments no significant difference was found between the two cpi averages student s t test at the 99 confidence level however higher plant n alkanes generally maximized at c29 for lr sediments but maximized at c31 for all ot sediments strongly indicating significant differences in the origins of the hydrocarbons in these two areas all present results appear to suggest that lr sediments are not a major hydrocarbon source for ot sediments in addition there was no positive linear correlation between diploptene hop 22 29 ene and terrestrial higher plant n alkanes for lr and ot sediments

using image warping for time lapse image domain wavefield tomography abstracttime lapse seismic data are widely used for monitoring subsurface changes a quantitative assessment of how reservoir properties have changed allows for better interpretation of fluid substitution and fluid migration during processes such as oil and gas production and carbon sequestration full waveform inversion fwi has been proposed as a way to retrieve quantitative estimates of subsurface properties through seismic waveform fitting however for some monitoring systems the offset range versus depth of interest is not large enough to provide information about the low wavenumber component of the velocity model we evaluated an image domain wavefield tomography idwt method using the local warping between baseline and monitor images as the cost function this cost function is sensitive to volumetric velocity anomalies and it is capable of handling large velocity changes with very limited acquisition apertures where traditional fwi fails we described the theory and workflow of our method la

building and exhumation of the western carpathians new constraints from sequentially restored balanced cross sections integrated with low temperature thermochronometry western carpathian orogeny has been the subject of intense scientific debate due to the occurrence of enigmatic features leading several authors to provide contrasting geological models in this paper a new interpretation for the tectonic evolution of the western carpathians is provided based on i an analysis of the stratigraphy of the mesozoic tertiary successions across the thrust belt domains ii a reappraisal of the stratigraphy and sedimentology of the tectonic melange i e the so called pieniny klippen belt marking the suture between the inner and outer carpathians and iii the construction of a series of balanced and restored cross sections validated by 2d forward modeling our analysis provides a robust correlation of the stratigraphy from the outer to the inner carpathians independently of the occurrence of oceanic lithosphere in the area and allows for the reinterpretation of the tectonic relationships among the inner carpathians the outer carpathians and the pieniny klippen belt and the exhumation mechanisms affecting this orogenic belt in order to constrain the evolution during the last 20 ma our model also integrates previously published and new apatite fission track and apatite u th sm he data these latter indicate a middle late miocene exhumation of the pieniny klippen belt in this study the recent regional uplift of the pieniny klippen belt is described for the first time using a 2d kinematic model for the tectonic evolution of the western carpathians

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

tertiary evolution of the intra carpathian area a model abstract the outer carpathian flysch nappes encircle an intra carpathian domain which can be divided into two megatectonic units north pannonian and tisza mostly on the basis of contrasting mesozoic and palaeogene facies development we see two major kinematic problems to be solved 1 1 the present distribution of the mesozoic and palaeogene facies is mosaic like and some belts form exotic bodies within realms of austroalpine affinity 2 2 late eocene palinspastic reconstruction of the outer carpathian flysch nappes suggest that the entire intra carpathian area must have been located several hundreds of kilometres to the south and to the west of its present position neogene extension can account for shortening in the external carpathian nappes but is unable to explain mesozoic facies anomalies and offsets of palaeogene formations we suggest that evolution of the intra carpathian area involved first late palaeogene early miocene juxtaposition of the north pannonian and tisza megatectonic units accompanied by the closure of the external carpathian flysch troughs thereafter extension of this amalgamated unit occurred which was compensated by thrusting of flysch nappes onto the european foreland and formation of molasse foredeeps eastward escape of the north pannonian unit from the alpine collisional belt involved left lateral shear along the pieniny klippen belt and right lateral shear along the mid hungarian zone parts of the late palaeogene basin and an early miocene volcanic edifice were dissected offset and elongated by several 100 kms the driving mechanism of the eastward escape of the intra carpathian area can be related to the collision of apulia and europe and the subduction of the external carpathian crust under the pannonian units the escape ceased gradually in the early miocene when oblique collision between the north pannonian unit and european continent occurred neogene extension of the pannonian region was an areal deformation the extension at locally variable rate resulted in the break up of the heterogenous floor of the neogene basin the driving mechanism of basin extension and contemporaneous compressional deformation of the external carpathians is thought to be related to ongoing subduction involving the marginal part of the attenuated european continental crust tectonic activity in the carpathians and basin subsidence and volcanism shifted in time and in unison from the west toward the east southeast

the western carpathians interaction of hercynian and alpine processes abstract the complicated structural and rheologic properties of western carpathian lithosphere reflect the complex geodynamic history of the carpathian orogen based on critical analysis of earlier models new interpolation of existing geophysical data and results of integrated modelling a new map of the lithosphere thickness for the carpathian pannonian region has been constructed the map allows for the distinction of a frontal orogen collision zone in the ne from increased lithosphere thickness as well as a zone of oblique collision with the bohemian massif in the west where lithosphere is not significantly thickened the moho discontinuity beneath the western carpathian hinterland danube and east slovak basins as defined by deep reflection seismic profiling is relatively shallow this probably reflects recent crustal extension related to oblique collision between the european plate and the alcapa block and an increase of the asthenospheric updoming from the middle miocene onward crustal thickness reflects the combined effects of deep seated orogenic processes and mantle thermal evolution beneath the pannonian basin system in this study we focus particularly the structures of 1 the late alpine collision and neogene back arc basin development including deep seated contacts between colliding plates a zone of slab detachment the compressional accretionary wedge of the outer western carpathian flysch belt and extensional structures produced by subduction rollback and asthenosphere upwelling 2 early alpine structures related to cretaceous thrust stacking including subhorizontal reflection packages interpreted as multi generational extensional structures the underplated intra penninic oravic continental ribbon and ophiolite traces of the meliatic oceanic suture and 3 north dipping reflectors interpreted as remnant hercynian lithotectonic fragments with opposed vergency to the subducted alpine units

biomarker records of palaeoenvironmental variations in subtropical southern africa since the late pleistocene evidences from a coastal peatland abstract southern africa s unique global position has given rise to a dynamic climate influenced by large sea surface temperature gradients and seasonal fluctuations in the inter tropical convergence zone due to the semi arid climate of the region terrestrial palaeorecords are rare and our understanding of the long term sensitivity of southern african terrestrial ecosystems to climatic drivers is ambiguous a 810 cm continuous peat core was extracted from the mfabeni peatland with a 14 c basal age of c 47 thousand years calibrated before present kcal yr bp positioning it as one of the oldest known sub tropical coastal peatlands in southern africa this peat core provides an opportunity to investigate palaeoenvironmental changes in subtropical southern africa since the late pleistocene biomarker n alkane n alkanoic acid and n alkanol analysis in conjunction with previously published bulk geochemical data was employed to reconstruct organic matter om sources rates of om remineralisation and peatland hydrology our results showed that the principal om source into the peatland was emergent and terrestrial plants with exception of shallow lake conditions when submerged macrophytes dominated c 44 5 42 6 29 7 26 1 23 1 16 7 7 1 and 2 2 kcal yr bp n alkane proxies suggest that local plant assemblages were predominantly influenced by peatland hydrology by incorporating temperature sensitive n alkanoic acid and n alkanol proxies it was possible to disentangle the local temperature and precipitation changes we report large variations in precipitation intensities but subdued temperature fluctuations during the late pleistocene the holocene period was characterised by overall elevated temperatures and precipitation compared to the preceding glacial period interspersed with a millennial scale cooling event a close link between the mfabeni archive and adjacent indian ocean marine core records was observed suggesting the regional ocean surface temperatures to be the dominant climate driver in this region since the late pleistocene

basement involved reactivation in foreland fold and thrust belts the alpine carpathian junction austria the late eocene early miocene alpine carpathian fold and thrust belt ftb lies in the transition between the eastern alps and the western carpathians se of the bohemian crystalline massif our study shows the involvement of crystalline basement from the former european jurassic continental margin in two distinct events a first extensional event coeval with eggerian karpatian c 28 16 ma thin skinned thrusting reactivated the rift basement fault array and resulted from the large degree of lower plate bending promoted by high lateral gradients of lithospheric strength and slab pull forces slab break off during the final stages of collision around karpatian times c 17 16 ma promoted large wavelength uplift and an excessive topographic load this load was reduced by broadening the orogenic wedge through the reactivation of the lower plate deep detachment beneath and ahead of the thin skinned thrust front with the accompanying positive inversion of the basement fault array and ultimately by the collapse of the hinterland summits enhanced by transtensional faulting although this work specifically deals with the involvement of the basement in the alpine carpathian junction the main conclusions are of general interest to the understanding of orogenic systems

high resolution holocene climate and hydrological variability from two major mediterranean deltas nile and rhone high resolution records of sea surface temperatures ssts and terrestrial n alkanes terr alkanes combined with pollen from the same sedimentary sequences were generated to assess variations in the nile river discharge over the holocene these independent proxy records indicate a period of wetter conditions in the nile watershed during the early holocene consistent with insolation driven enhanced monsoon precipitation known as the african humid period ahp the detection of a dry episode around 9200 yr bp in the terr alkane and pollen time series suggests a temporary weakening of the monsoon intensity most probably triggered by extratropical cooling in the north atlantic an interval of c4 grass expansion between 8800 and 8400 yr bp was also evidenced from the terr alkane distribution and confirmed by palynological data ssts of the coastal waters off the nile delta reveal strong fluctuations in the early holocene followed by a slight warming and two pronounced cold intervals around 3500 yr bp and 150

low latitude hydro climatic changes during the plio pleistocene evidence from high resolution alkane records in the southern south china sea abstract high resolution records of long chain n alkane biomarkers from the southern south china sea reveal tightly response of n alkane distribution to hydro climate changes over the past 5 ma with increasing longer chain n c31 alkanes indicating a correlation with drier conditions and increasing shorter chain n c27 alkanes with wetter conditions the variations of the c31 c27 ratio or the alkane chain length index imply humid conditions before 2 9 ma progressively reduced moisture since then and to bigger fluctuations between wet and dry conditions since 1 2 ma this long term hydro climate trend is superimposed by glacial dry and interglacial wet patterns over the plio pleistocene glacial cycles combined with other proxy records our results indicate that precipitation over the tropical asia pacific strengthened before the onset of the northern hemisphere glaciation and the mid pleistocene climate transition at about 1 2 ma these dramatic humidity changes over major climate transitions imply a crucial role of tropical hydrology dynamics on global climate change in the late cenozoic

transform faulting extension and subduction in the carpathian pannonian region the carpathian arc formed during the cretaceous to miocene continental collision of europe with a smaller continental fragment following southward and westward subduction of an oceanic terrane during and after the last stages of thrusting in the outer carpathians a set of discrete basins opened up inside the carpathian loop these basins are regions of local extension which appear to be associated with strike slip faults in general northeast and northwest trending sets of conjugate shears reflect east west extension of the intra carpathian region during the middle and late miocene palinspastic reconstruction of the basins indicates approximately 75 to 100 km of extension comparable to the magnitude of synchronous crustal shortening in the east carpathians extension may have occurred to accommodate continued westward a type subduction after plate convergence was prohibited by geometrical constraints and suggests that in this region miocene subduction is driven by forces acting on the downgoing plate

holocene cyclic climatic variations and the role of the pacific ocean as recorded in varved sediments from northeastern china we present an n alkane and compound specific carbon isotope record of the past 9 ka from the annually laminated sedimentary sequence of lake xiaolongwan northeastern china the n alkane distribution suggests that lake xiaolongwan has undergone a shift from an oligotrophic state with low algal production and little emergent submerged macrophytes in the early holocene to a eutrophic state with high algal production and abundant emergent submerged macrophytes since the middle holocene the pattern of variation observed in the biomarker proxies acl the n alkane average chain length paq aquatic macrophyte versus aquatic macrophyte and terrestrial plant ratio and lptp lake productivity terrigenous organic production is throughout the record similar to that of the total organic carbon the variation of compound specific carbon isotopic values in the middle and short chain alkanes was mainly regulated by lake productivity and the accumulating organic pool through time in this forested region where the vegetation is dominated by c 3 plants the long chain n alkanes c27ec31 are predominantly derived from leaf wax lipids the compound specific d 13 c27e31 value is sensitive to effective precipitation and therefore represents a useful indicator of regional monsoonal precipitation spectral analysis on the d 13 c27e31 time series reveals significant periodicities of 87e89 205e212 1020e1050 and 1750e2041 years on the centennial timescale the quasi periodicities around 88 and 210 years suggest a strong link between solar activity and monsoon rainfall the millennial monsoon cycle in northeastern china is associated with sea surface temperature sst variations in two active centers of the summer monsoon the western pacific subtropical high wpsh and the okhotsk high increasing sst in the subtropical sea may cause a northwards shift of the wpsh which extends the monsoon rain band meiyu to northeastern china and thus increasing rainfall in that region meanwhile decreasing sst in the okhotsk sea may strengthen the okhotsk high bringing more moisture into northeastern china we suggest that the pacific ocean is a main regulator for summer monsoon rainfall in northeastern china at present and at different time scales during the holocene

upper mantle structures beneath the carpathian pannonian region implications for the geodynamics of continental collision abstract the carpathian pannonian system of eastern and central europe represents a unique opportunity to study the interaction between surface tectonic processes involving convergence extension and convective overturn in the upper mantle here we present high resolution images of upper mantle structure beneath the region from p wave finite frequency teleseismic tomography to help constrain such geodynamical interactions we have selected earthquakes with magnitude greater than 5 5 in the distance range 30 95 which occurred between 2006 and 2011 the data were recorded on 54 temporary stations deployed by the south carpathian project 2009 2011 56 temporary stations deployed by the carpathian basins project 2005 2007 and 131 national network broadband stations the p wave relative arrival times are measured in two frequency bands 0 5 2 0 hz and 0 1 0 5 hz and are inverted for vp perturbation maps in the upper mantle our images show a sub vertical slab of fast material beneath the eastern alps which extends eastward across the pannonian basin at depths below 300 km the fast material extends down into the mantle transition zone mtz where it spreads out beneath the entire basin above 300 km the upper mantle below the pannonian basin is dominated by relatively slow velocities the largest of which extends down to 200 km we suggest that cold mantle lithospheric downwelling occurred below the pannonian basin before detaching in the mid miocene in the vrancea zone of se romania intermediate depth 75 180 km seismicity occurs at the ne end of an upper mantle high velocity structure that extends sw under the moesian platform oblique to the southern edge of the south carpathians at greater depths 180 400 km a sub circular high velocity anomaly is found directly beneath the seismicity this sub vertical high velocity body is bounded by slow anomalies to the nw and se which extend down to the top of the mtz no clear evidence of a residual slab is observed above the mtz beneath the eastern carpathians these observations suggest that intermediate depth seismicity in vrancea zone is unlikely to be due to slab tearing but rather could be explained by either gravitational instability or delamination of mantle lithosphere

sources of long chain fatty acids in deep sea sediments from the bering sea and the north pacific ocean abstract the distributions and compound specific carbon isotope ratios of long chain n fatty acids and long chain n alkanes in two sedimentary cores collected from the north pacific ocean and the bering sea have been examined long chain fatty acids were further fractionated into three sub fractions esterified free and polar to investigate their sources the 13 c values of these fractions clarified the sources of different fatty acids the esterified fraction had lighter 13 c values 30 1 0 70 similar to those of the long chain n alkanes 30 2 1 08 consistent with a mainly terrestrial plant origin in contrast the long chain fatty acids except c 28 from the polar and free fractions had heavier isotopic values 27 5 1 06 suggesting a mixed origin from terrestrial and marine organisms the esterified fatty acids from the north pacific ocean and the bering sea can be used as terrestrial biomarkers

variations of terrestrial input and marine productivity in the southern ocean 48 s during the last two deglaciations various biomarkers n alkanes n alcohols and sterols have been studied in a piston core tsp 2pc taken from the southern ocean to reconstruct the paleoenvironmental changes in the subantarctic region for the last two deglaciations mass accumulation rates of terrestrial higher molecular weight n alkanes and n alcohols and marine dinosterol and brassicasterol biomarkers increased significantly at the last two glacials and stayed low during interglacial peaks early holocene and the eemian these records indicate that the enhanced atmospheric transport of continental materials and the increased marine biological productivity were synchronously linked in the southern ocean at the last two glacials this suggests that increased glacial dust inputs have relieved iron limitation in the subantarctic southern ocean these two processes however were not linked at the cooling phase from the eemian to marine isotope stage mis 5d during this period paleoproductivity may have been influenced by the latitudinal migration of the high production zone associated with the antarctic polar front

organic geochemistry of the mcmurdo dry valleys soil antarctica abstract organic geochemical studies of 12 soil samples from wright and taylor valleys of the mcmurdo dry valleys ross desert in southern victoria land antarctica were carried out long chain n alkanoic acids c 20 c 34 with predominance of even carbon numbers were abundant in all the samples 3 hydroxy acids c 8 c 30 with a predominance of even carbon numbers were found in the samples together with 2 and 1 hydroxy acids dicarboxylic acids c 8 c 31 were detected having near unity values of carbon preference indices mainly the c 13 dicarboxylic acid predominated visual kerogen revealed that amorphous materials are major components 68 98 with small amounts of very fine coals 2 32 but no woody and herbaceous materials the occurrence of mature isomers of steranes and triterpanes the paucity of n alkenoic acids and data from the microscopic study suggest that organic components in the soil samples are derived from erosion of beacon supergroup sedimentary rocks and past biological debris containing vascular plan waxes as well as wind transported cyano bacterial mats including cyanobacteria microalgae bacteria and fungi rather than from living organisms

image warping waveform tomography imaging the change in physical parameters in the subsurface requires an estimate of the long wavelength components of the same parameters in order to reconstruct the kinematics of the waves propagating in the subsurface one can reconstruct the model by matching the recorded data with modeled waveforms extrapolated in a trial model of the medium alternatively assuming a trial model one can obtain a set of images of the reflectors from a number of seismic experiments and match the locations of the imaged interfaces apparent displacements between migrated images contain information about the velocity model and can be used for velocity analysis a number of methods are available to characterize the displacement between images in this paper we compare shot domain differential semblance image difference penalized local correlations and image warping we show that the image warping vector field is a more reliable tool for estimating displacements between migrated images and leads to a more robust velocity analysis procedure by using image warping we can redefine the differential semblance optimization problem with an objective function that is more robust against cycle skipping than the direct image difference we propose an approach that has straightforward implementation and reduced computational cost compared with the conventional adjoint state method calculations we also discuss the weakness of migration velocity analysis in the migrated shot domain in the case of highly refractive media when the born modelling operator is far from being unitary and thus its adjoint migration operator poorly approximates the inverse

major element analysis of cyclic black shales paleoceanographic implications for the early cretaceous deep western tethys lower cretaceous sediments are frequently characterized by a well expressed cyclicity while the processes influencing environments above the carbonate compensation depth ccd are reasonably well understood almost nothing is known about the deep ocean cretaceous sub ccd sediments from the tethys and atlantic oceans typically show rhythmic black green shale successions to gain insight into the nature of these black green shale cycles we performed detailed geochemical analyses x ray fluorescence rock eval and reactive iron analysis on a 3 m long section of latest aptian age the major element distribution of the analyzed shale sequence indicates a periodic change from a high productivity and well oxygenated green shale mode to a low productivity oxygen deficient black shale mode it is proposed here that the preservation of organic matter was dependent on the strength of salinity driven deepwater generation furthermore the data show that the corg content covaries with changes in the detrital composition therefore we hypothesize that tethyan deepwater circulation was sensitive to changes in the monsoonal system time series analysis suggests that these changes are periodic in nature although we are currently unable to prove that the dominant periodicity is related to the precession component of the milankovitch frequencies

wave equation traveltime inversion this paper presents a new traveltime inversion method based on the wave equation in this new method designated as wave equation traveltime inversion wt seismograms are computed by any full wave forward modeling method we use a finite difference method the velocity model is perturbed until the traveltimes from the synthetic seismograms are best fitted to the observed traveltimes in a least squares sense a gradient optimization method is used and the formula for the frechet derivative perturbation of traveltimes with respect to velocity is derived directly from the wave equation no traveltime picking or ray tracing is necessary and there are no high frequency assumptions about the data body wave diffraction reflection and head wave traveltimes can be incorporated into the inversion in the high frequency limit wt inversion reduces to ray based traveltime tomography it can also be shown that wt inversion is approximately equivalent to full wave inversion when the starting velocity model is

cretaceous evolution of a metamorphic core complex the veporic unit western carpathians slovakia p t conditions and in situ40ar 39ar uv laser probe dating of metapelites alpine metamorphism related to the development of a metamorphic core complex during cretaceous orogenic events has been recognized in the veporic unit western carpathians slovakia three metamorphic zones have been distinguished in the metapelites 1 chloritoid chlorite garnet 2 garnet staurolite chlorite 3 staurolite biotite kyanite the isograds separating the metamorphic zones have been modelled by discontinuous reactions in the system k2o feo mgo al2o3 sio2 h2o kfmash the isograds are roughly parallel to the north east dipping foliation related to extensional updoming along low angle normal faults thermobarometric data document increasing p t conditions from c 500 c and 7 8 kbar to c 620 c and 9 10 kbar reflecting a coherent metamorphic field gradient from greenschist to middle amphibolite facies 40ar 39ar data obtained by high spatial resolution in situ ultraviolet uv laser ablation of white micas from the rock slabs constrain the timing of cooling and exhumation in the late cretaceous mean dates are between 77 and 72 ma however individual white mica grains record a range of apparent 40ar 39ar ages indicating that cooling below the blocking temperature for argon diffusion was not instantaneous the reconstructed metamorphic p t t path is clockwise reflecting post burial decompression and cooling during a single alpine orogenic cycle the presented data suggest that the veporic unit evolved as a metamorphic core complex during the cretaceous growth of the western carpathian orogenic wedge metamorphism was related to collisional crustal shortening and stacking following closure of the meliata ocean exhumation was accomplished by synorogenic orogen parallel extension and unroofing in an overall compressive regime

stress induced late stage subsidence anomalies in the pannonian basin abstract subsidence sedimentation and tectonic quiescence of the pannonian basin was interrupted a few million years ago by tectonic reactivation this recent activity has manifested itself in uplift of the western and eastern flanks and continuing subsidence of the central part of the pannonian basin low to medium magnitude earthquakes of the carpathian pannonian region are generated mostly in the upper crust by reverse and wrench fault mechanisms there is no evidence for earthquakes of extensional origin 2 d model calculation of the subsidence history shows that a recent increase in magnitude of horizontal compressional intraplate stress can explain fairly well the observed quaternary uplift and subsidence pattern we propose that this stress increase is caused by the overall europe africa convergence in late pliocene consumption of subductible lithosphere at the eastern margin of the pannonian basin was completed and the lithosphere underlying the pannonian basin became locked in a stable continental frame consequently extensional basin formation has come to an end and compressional inversion of the pannonian basin is in progress

environmental and vegetational changes recorded in sedimentary leaf wax n alkanes across the cretaceous paleogene boundary at loma capiro central cuba abstract the stable carbon isotopic compositions 13c and chain length distribution acl and n c31 n c29 n c31 of sedimentary leaf wax n alkanes were investigated across the cretaceous paleogene k pg boundary at loma capiro central cuba to reconstruct paleoenvironmental changes that are recorded in terrestrial higher plants the stratigraphic profiles of the n alkane 13c values show a negative excursion in the lowermost paleocene although its magnitude is much smaller 0 3 than the global signals 1 5 to 2 0 in the surface ocean atmospheric carbon reservoir relations between the n alkane 13c values and the c31 c29 c31 ratios exhibit two different trends suggesting that our 13c records are likely affected by two types of paleoenvironmental factors in addition to the 13c variations in the exogenous carbon reservoir rare occurrence of terrigenous organic matter that is usually transported by rivers suggests that the n alkanes at loma capiro are likely to have been transported by trade winds which recorded paleoenvironmental conditions of the northwestern part of the african continent the n alkane 13c values show a parallel decrease with the acl and c31 c29 c31 values in the first 37 000 yr following the k pg boundary such decreases are consistent with plant physiological responses to reduced net evaporation suggesting a possible influence of the impact induced warm humid condition in the early paleocene in contrast the n alkane 13c values are negatively correlated with the c31 c29 c31 ratios from 40 000 to 67 000 yr after the k pg boundary this time period matches well with that required for the recovery of terrestrial floras from the k pg mass extinction to those with diversity equivalent to the late cretaceous suggesting that the n alkane signals are also likely affected by the plant diversification process after the mass extinction

magnitudes and sources of precipitation and dry deposition fluxes of indestrial and natural leads to the north pacific at enewetak a total atmospheric pb input flux of 7 ng pb cm 2 yr 1 was measured in the north pacific easterlies at enewetak parameters used to measure this flux were ratio of dry deposition flux to precipitation flux pb 210 pb in precipitation and seawater 210 pb flux washout factor and pb concentrations in air rain and dry deposition deposits relations among these parameters established at enewetak were used to recompute and confirm previous estimates of lead fluxes to the oceans ng pb cm 2 yr 1 at the following locations north atlantic westerlies 170 north pacific westerlies 50 and south pacific easterlies 3 prehistoric lead output fluxes to sediments ng pb cm 2 yr 1 at these locations have been previously measured and were 4 enewetak 30 north atlantic westerlies 3 north pacific westerlies 4 south pacific easterlies these data show that the rates of atmospheric inputs of lead to the oceans vary directly with variations in rates of upwind emissions of industrial lead from urban complexes on land in the north pacific and north atlantic present rates of atmospheric lead inputs are 10 fold greater than prehistoric outputs in equatorial regions present inputs and past outputs are more nearly equal these observations disclose the effects of intense industrial atmospheric emissions of lead in the northern hemisphere westerlies which have overwhelmed prehistoric natural fluxes of lead to the oceans the average concentration of lead in marine air at enewetak is 170 pg m 3 and varies less than a factor of 2 from that mean one to 15 of this lead comes from seaspray while the remainder comes from sources on land about 90 of the seaspray lead is industrial while 80 to 99 of that originating from land sources is industrial concentrations of lead in rain at enewetak range from 6 to 63 pg g with a mean value of 28 the mean precipitation flux corrected for recycled lead in sea salts measured by four different methods was 6 ng pb cm 2 yr 1 while the net dry deposition flux measured on horizontal plastic plates was 0 6 ng pb cm 2 yr 1 the total dry deposition flux measured was 6 ng cm 2 yr 1 but 90 of this lead came from recycled seaspray lead isotope tracers show that japan is the major source of industrial lead at enewetak during the dry season while the united states is the major source during the wet season

the relationship between sedimentary organic carbon isotopic composition and organic biomarker compound concentration abstract a study of organic biomarker compounds which could serve as tracers of terrigenous and marine sedimentary organic matter sources was performed on samples from a 208 7 m hydraulic piston core hole dsdp hole 619 from the hemipelagic pigmy basin in the northern gulf of mexico organic carbon normalized concentrations of total long chain c37 c39 alkenones and some individual c27 c29 desmethyl sterols were determined to be useful proportional indicators tracers of preserved marine and terrigenous organic carbon respectively the alkenones whose only known source is marine phytoplankton of the class prymnesiophyceae generally occurred in higher concentrations in interglacial isotope stages 1 and 5a b than in the intervening glacial stages sterols c27 c29 apparently of a dominantly terrigenous origin occurred in lower concentrations during interglacial stages than in glacial stages tracers of both terrigenous and marine organic matter appear to be affected by the differential diagenetic alteration of the biomarker corg ratios as indicated by a simple first order kinetic model the lack of any desmethylor 4a methylsterol which is linearly related to the proportion of marine sedimentary organic matter as scaled by 13corg indicates that either 1 1 sedimentary diagenesis has obscured the biomarker corg vs 13corg record 2 2 phytoplanktonic assemblage changes caused variations in the biomarker corg ratio of the primary input preferential preservation of terrigenous sterols may result in a biased sedimentary record of sterol input which could be misinterpreted as indicating solely terrigenous sterol sources a simple model which characterizes the effects of sedimentary diagenesis on the relationship between corg normalized biomarker ratios and 13corg demonstrates the potential problems of long term differential diagenetic skewing on those tracer records

neogene exhumation in the outer western carpathians terra nova 23 283 291 2011 abstract apatite fission track analysis was used to investigate the cenozoic tectonic evolution of the polish sector of the outer western carpathians where thrusting was overlapped by extension in the last 10 ma the results show a general decrease of burial degree towards the european foreland and a range of cooling ages between 26 and 7 ma younger ages 10 7 ma are confined to the eastern region whereas exhumation in the central western region is about 10 ma older and is characterized by no major age differences among structural units therefore exhumation of the chain is inferred to have occurred since the early miocene when it appears to have been essentially coeval with thrusting whereas extensional tectonics is likely to have played an important role during late miocene exhumation

intra orogenic extension driven by gravitational instability carpathian pannonian orogeny the extensional pannonian basin was formed in a few million years during miocene time synchronously with contraction in the surrounding alpine and carpathian orogens this system is characteristic of a class of extensional basins that form in the midst of active orogenic mountain forming belts the mechanism that causes this type of geological event is enigmatic but usually has been associated with subduction we examine a new hypothesis for intra orogenic extensional basin formation in which gravitational spreading of previously thickened crust triggers gravitational instability of the mantle lithosphere a basin is formed by lithospheric extension as shortening and lithospheric downwelling occur in the surrounding mountain belts this mechanism provides a mechanically self consistent explanation for all of the main structural features of the pannonian carpathian system and presents a plausible alternative to the popular view that subduction and slab rollback have driven the development of this basin

a differential semblance criterion for inversion of multioffset seismic reflection data mean square error leading to least squares inversion of multioffset reflection seismograms is insensitive to velocity trend information except in the immediate vicinity of a kinematically correct model in contrast differential semblance retains sensitivity to velocity trend changes over a wide range of models the differential semblance criterion combines mean square error with the mean square differences of inverted models from data sets at neighboring shot positions or offsets or slownesses differential semblance compares model estimates at nearby acquisition parameters which are similar even when the model velocity trends are incorrect because the method inverts the data so that the estimated model amplitudes are meaningful simple differences between the unstacked model estimates give a reliable measure of velocity error a mathematical investigation indicates that the differential semblance criterion is smooth and convex over a large range of velocity models numerical simulation using synthetic data sets verifies this contention

the importance of atmospheric input of terrestrial organic material to deep sea sediments the concentrations of lipids were determined in atmospheric particle gas and rain samples collected from the tropical north pacific to assess lipid sources transport mechanisms and fluxes to the ocean surface four lipid compound classes aliphatic hydrocarbons fatty alcohols fatty acid esters and salts all unequivocally show a terrestrial vascular plant source these aerosol lipids originate from wind erosion of asian and american soils and direct emission from vegetation the major fluxes result from rain rather than dry deposition these fluxes are large enough to have a major potential impact on the inventory of terrestrially derived lipid material found in deep sea sediments this has been showm for n alkanes fatty alcohols fatty acids total lipids and for organic carbon by comparing atmospheric and sediment trap fluxes with sediment accumulation rates it is suggested that some biogenic terrestrial material is more protected from degradation than marine derived material

global temperature calibration of the alkenone unsaturation index uk 37 in surface waters and comparison with surface sediments in this paper we compile the current surface seawater c37 alkenone unsaturation uk 37 measurements n 629 1 to 30 c temperature range to derive a global field based calibration of uk 37 with alkenone production temperature a single nonlinear global surface water calibration of uk 37 accurately predicts alkenone production temperatures over the diversity of modern day oceanic environments and alkenone synthesizing populations t 0 957 54 293 uk 37 52 894 uk 37 2 28 321 uk 37 3 r2 0 97 n 567 the mean standard error of estimation is 1 2 c with insignificant bias in estimated production temperature among the different ocean regions sampled an exception to these trends is regions characterized by strong lateral advection and extreme productivity and temperature gradients e g the brazil malvinas confluence in contrast to the surface water data the calibration of uk 37 in surface sediments with overlying annual mean sea surface temperature anno is best fit by a linear model anno 29 876 uk 37 1 334 r2 0 97 n 592 the standard error of estimation 1 1 c is similar to that of the surface water production calibration but a higher degree of bias is observed among the regional data sets the sediment calibration differs significantly from the surface water calibration uk 37 in surface sediments is consistently higher than that predicted from anno and the surface water production temperature calibration and the magnitude of the offset increases as the surface water anno decreases we apply the global production temperature calibration to the coretop uk 37 data to estimate the coretop alkenone integrated production temperature coretop ipt and compare this with the overlying annual mean sea surface temperature anno we use simple models to explore the possible causes of the deviation observed between the coretop temperature signal as estimated by uk 37 and anno our results indicate that the deviation can best be explained if seasonality in production and or thermocline production as well as differential degradation of 37 3 and 37 2 alkenones both affect the sedimentary alkenone signal

aliphatic hydrocarbons in coastal sediments of the northern cyprus eastern mediterranean the sources and spatial distributions of aliphatic hydrocarbon concentrations were investigated in surficial sediments of the northern cyprus gemi konagi girne and gazi magusa areas aliphatic hydrocarbon levels were determined with a gas chromatography mass spectrometer total aliphatic hydrocarbon n alkanes 25 isoprenoids 2 concentrations in the sediments were found in the range of 1107 6360 ng g results indicated that the sediments were mainly dominated by odd numbered n alkanes n c10 n c34 maximizing at n c17 n c29 and n c31 statistical analyses and diagnostic ratios have been used to determine the possible sources and origins of aliphatic hydrocarbons aliphatic hydrocarbons were showed biogenic character at all sampling areas and were found mainly originated from terrestrial marine and both terrestrial marine plants at gemi konagi gazi magusa and girne respectively

automatic velocity analysis via shot profile migration we described an implementation of differential semblance velocity analysis based on shot profile migration and illustrated its ability to estimate complex strongly refracting velocity fields the differential semblance approach to velocity analysis uses waveform data directly it does not require any sort of traveltime picking the objective function minimized by the differential semblance algorithm can measure either focusing of the image in offset or flatness of the image in scattering angle we showed that the offset variant of differential semblance yields somewhat more reliable migration velocity estimates than does the scattering angle variant and we explain why this is so we observed that inconsistency with the underlying model born scattering about a transparent background can lead to degraded velocity estimates from differential semblance and we showed how to augment the objective function with stack power to enhance ultimate accuracy a 2d marine survey over a target obscured by the lensing effects of a gas chimney provides an opportunity for direct comparison of differential semblance with reflection tomography the differential semblance estimate yields a more data consistent model flatter angle gathers than does reflection tomography in this application resulting in a more interpretable image below the gas cloud

an integrated platform for thermal maturity assessment of polyphase long lasting sedimentary basins from classical to brand new thermal parameters and models an example from the on shore baltic basin poland abstract paleo thermometers in sedimentary basins often drive to misleading thermal modelling when applied alone or only on potentially productive paleozoic source rocks different paleo thermal and thermo chronological data have been used as constraints to model the silurian to cenozoic succession of a recently drilled well in the onshore portion of the baltic basin in northern poland this dataset provides an integrated platform for thermal maturity assessment contributing to the highly debated reconstruction of the thermal history of the baltic basin in the last decade the well stratigraphy consists of a lower paleozoic marine clayey and arenaceous calcareous succession about 1000 m thick that is unconformably overlain by a 2000 m thick permian to cenozoic sequence developed in a continental to shallow marine environment optical microscopy ft ir and raman spectroscopy analysis of organic matter have been coupled with u th he data to produce a robust vitrinite reflectance profile and constrain the 1d thermal modelling of the well in addition such a thermal maturity profile was validated by an independent thermal modelling calibrated by the smectite illitization kinetics both models identify high heat flow conditions up to 1 7 hfu at the end of mesozoic the lower paleozoic succession entered the late oil window of hc generation during this last heating event

aeolian transport and deposition of plant wax n alkanes across the tropical north atlantic ocean long chain n alkanes are terrestrial higher plant biomarkers analysed in marine sedimentary archives to reconstruct continental palaeoclimatic and palaeohydrological conditions latitudinal variation in their concentration and distribution in marine sediments relatively close to the continent has been widely studied but little is known on the extent to which this continental signal extends to the ocean furthermore no studies have examined the seasonal variation in the deposition of these biomarkers in marine sediments here we studied longitudinal variation in the composition of long chain n alkanes and two other terrestrial higher plant biomarkers long chain n alkanols and long chain fatty acids in atmospheric particles as well as longitudinal and seasonal variation in long chain n alkanes in sinking particles in the ocean at different water depths and in surface sediments all collected along a 12 n transect across the tropical north atlantic ocean the highest abundance of all three biomarker classes was closest to the african coast as expected because they are transported with saharan dust and the largest part of the dust is deposited close to the source at this proximal location the seasonal variability in long chain n alkane flux and the chain length distribution of the n alkanes in sinking particles was most pronounced due to seasonal change in the dust source or to change in vegetation composition in the source area related to the position of the intertropical convergence zone itcz in contrast in the open ocean the seasonal variability in both the long chain n alkane flux and chain length distribution of the n alkanes was low the abundance of the alkanes was also lower as expected because of the larger source to sink distance at the western part of the transect close to south america we found an additional source of the alkanes in the sinking particles during spring and autumn in the year 2013 the 13c values of the alkanes in the surface sediment closest to the south american continent indicated that the isotope signal was likely derived from c3 vegetation from the amazon implying an input from the amazon river as there is no significant aeolian input from south america there since the prevailing wind direction is from the east finally the concentration of the alkanes was similar in the material collected from the atmosphere the particles collected while settling through the marine water column and in the surface sediments providing evidence that degradation of long chain n alkanes from the atmosphere to settling at the sediment water interface at deep open ocean sites is minimal

a 27 kyr terrestrial biomarker record in the southern indian ocean terrestrial inputs were reconstructed using high molecular weight n alkane concentrations recorded in the sub antarctic indian ocean core md94 103 45 35 s 86 31 e 3560 m to examine regional changes in the atmospheric circulation over the last 27 kyr this record was compared to the dust content of epica dome c ice and continental data from south africa e g pollen sequences and isotope records in speleothems to get a comprehensive understanding of atmospheric links between low and midlatitudes of the indian ocean terrestrial n alkanes indicate higher glacial than holocene inputs and marked glacial oscillations minimum values during the last glacial maximum lgm are consistent with colder and drier climate and presumably caused by the persistence of subtropical anticyclones over southern africa limiting the amount of rainfall and vegetation growth the otherwise higher glacial n alkanes suggest a stronger influence of the tropical rainfall in southern africa likely associated with a contraction of the polar vortex with respect to its lgm position during northern heinrich events moderate decline of n alkanes suggests reduced rainfall over southern africa possibly caused by weaker tropical easterly winds when according to stott et al 2002 the pacific ocean would have experienced super enso conditions

convergence and extension driven by lithospheric gravitational instability evolution of the alpine carpathian pannonian system summary lithospheric gravitational instability may play a significant role in the neogene alpine carpathian pannonian system where the extensional pannonian basin formed over a 10 myr period simultaneously with contraction in the surrounding alpine and carpathian orogens we investigate the idea that gravitational collapse of low density crust previously thickened in the collision of the european plate with adria has caused the simultaneous development of depth variable lithospheric thinning beneath the pannonian basin and contractional deformation in the carpathian arc implicit in this model is asthenospheric upwelling beneath the basin and lithospheric downwelling beneath the surrounding mountains we investigate the interplay between convergence and extension in this type of continental orogen using 2 d axisymmetric finite element models we show how key model parameters such as crust to lithosphere thickness and viscosity ratios affect the evolution of the system an initially thicker lithosphere enhances mantle instability and leads to a greater degree of thinning of the crust and lithospheric mantle and stronger downwelling in the mantle increasing the viscosity of the crust relative to the mantle slows the growth of the instability and reduces crustal deformation relatively low crustal viscosity however implies too rapid a collapse of initial topography and rapid re equilibration after deformation induced by mantle flow non newtonian viscosity localizes the deformation in a narrower spatial region and a shorter time interval following a relatively slower phase of initial growth in the alpine carpathian pannonian system development of the instability requires lithospheric thickness prior to extension on the order of 150 km and lithospheric mantle viscosity on the order of 2 10 20 pa s with crustal strength similar to that of the mantle

lithospheric gravitational instability beneath the southeast carpathians abstract the southeast corner of the carpathians known as the vrancea region is characterised by a cluster of strong seismicity to depths of about 200 km the peculiar features of this seismicity make it a region of high geophysical interest in this study we calculate the seismic strain rate tensors for the period 1967 2007 and describe the variation of strain rate with depth the observed results are compared with strain rates predicted by numerical experiments we explore a new dynamical model for this region based on the idea of viscous flow of the lithospheric mantle permitting the development of local continental mantle downwelling beneath vrancea due to a rayleigh taylor instability that has developed since the cessation of subduction at 11 ma the model simulations use a lagrangean frame 3d finite element algorithm solving the equations of conservation of mass and momentum for a spatially varying viscous creeping flow the finite deformation calculations of the gravitational instability of the continental lithosphere demonstrate that the rayleigh taylor mechanism can explain the present distribution of deformation within the downwelling lithosphere both in terms of stress localisation and amplitude of strain rates the spatial extent of the high stress zone that corresponds to the seismically active zone is realistically represented when we assume that viscosity decreases by at least an order of magnitude across the lithosphere the mantle downwelling is balanced by lithospheric thinning in an adjacent area which would correspond to the transylvanian basin crustal thickening is predicted above the downwelling structure and thinning beneath the basin

biomarker stratigraphic records over the last 150 kyears off the nw african coast at 25 n terrigenous and marine biomarkers were investigated in a core oa northwest africa in the northeast atlantic 25n 16w 1445 m depth to assess changes in the sedimentation pattern of organic carbon oc over the last 150 kyears alkenone derived temperatures recorded a warming of 4 5c during the last deglaciation n alkanol mass accumulation rates mar fluctuated in parallel with northeast trade winds netw intensity oc and sterol mar both increased during glacial times indicating enhanced fertility of the ocean in response to intensified netw alkenone oc ratios were higher by a factor of two over stages 4 6 than stages 1 3 thus reflecting distinct coccolithophorid inputs this transition coincides with a major change of alkenone producers inferred from coccolith counts 2000 elsevier science ltd all rights reserved

sedimentary record of marine and terrigenous organic matter delivery to the shatsky rise western north pacific over the last 130 kyr abstract biomarker and carbon isotopic analyses of piston core samples were undertaken to reconstruct changes over the last 130 kyr in the delivery of organic matter from marine plankton and terrestrial sources to sediments on the shatsky rise in the western north pacific marine and terrigenous organic matter delivery was reconstructed from alkenone and n alkane concentrations using multiple regression analysis which gave results consistent with a 13c mass balance model marine organic carbon comprises more than 86 of the total organic carbon throughout the sediment record fluxes of marine organic carbon were higher in glacial times indicating that marine production increased in these periods we conclude that in addition to the southward shift of the subarctic front eolian dust supply at this location played an essential role in enhancing paleoproduction during the last glacial maximum

late quaternary vegetation history of southeast africa the molecular isotopic record from lake malawi abstract accurate reconstructions of past hydrological variability are essential for understanding the climate history of the tropics in tropical africa the relative proportion of vegetation utilizing the c3 vs c4 photosynthetic pathway is mainly controlled by precipitation and thus past hydrological changes can be inferred from the vegetation record in this study biomarkers of terrestrial plants lignin phenols and plant leaf wax carbon isotopes are examined from a well dated sedimentary record from lake malawi to provide a vegetation aridity record of the past 23 cal ka from southeast africa we suggest that the ratio of cinammyl to vanillyl c v lignin phenols in lake malawi sediments mainly reflects inputs of c3 trees woody tissue vs c4 grasses non woody tissue and find that changes in the c v ratio generally support variability noted in the n alkane carbon isotope record together these records provide evidence for increased c4 vegetation grasses surrounding lake malawi during last glacial maximum lgm the younger dryas in the early holocene and from 2 cal ka to the present suggesting drier conditions at these times elevated inputs of c3 vegetation are noted in the intervals from 17 13 6 cal ka and 7 7 2 cal ka indicating wet conditions in southeast africa a relationship is noted between the n alkane average chain length acl and temperature with longer acls associated with higher temperatures higher n alkane carbon preference index cpi values correlate with higher mass accumulation rates of biogenic silica and may result from periodic increased northerly winds over lake malawi which enhance upwelling and diatom productivity while simultaneously increasing erosion and transport of plant leaf waxes to the lake the molecular data produced in this study suggest that the carbon isotopic signature of bulk sediment 13ctoc in lake malawi is primarily a reflection of terrestrial inputs c3 vs c4 vegetation and may not mainly reflect changes in algal productivity as previously thought

velocity inversion by differential semblance optimization differential semblance optimization dso is an approach to inversion of reflection seismograms which avoids the severe convergence difficulties associated with nonlinear least squares inversion the method exploits both moveout and amplitude characteristics of reflections we have implemented a version appropriate to plane wave p tau seismograms and layered constant density acoustic earth models theoretical and numerical analyses of this version of dso indicate that stable and reasonably accurate estimates of both velocity trend and reflectivity can be derived to test dso further we applied it to a marine data set from the gulf of mexico where the method produced results which compare favorably to well log information the method can be extended to incorporate laterally heterogeneous velocity models

3d angle gathers from reverse time migration reverse time migration rtm based on directly solving the two way wave equation provides a natural way to deal with large lateral velocity variations and imposes no dip limitations on the seismic images it has become a standard migration tool for subsalt imaging in the gulf of mexico in addition the adoption of wide azimuth waz data acquisition provides better subsurface illumination and more azimuthal information which significantly aids imaging beneath complex overburdens because waz data are richer in the propagation directions of the waves recorded rtm and waz acquisition go hand in hand

an annually resolved record of western european vegetation response to younger dryas cooling abstract the regional patterns and timing of the younger dryas cooling in the north atlantic realm were complex and are mechanistically incompletely understood to enhance understanding of regional climate patterns we present molecular biomarker records at subannual to annual resolution by mass spectrometry imaging msi of sediments from the lake meerfelder maar covering the allerod younger dryas transition these analyses are supported by conventional extraction based molecular isotopic analyses which both validate the imaging results and constrain the sources of the target compounds the targeted fatty acid biomarkers serve as a gauge of the response of the local aquatic and terrestrial ecosystem to climate change based on the comparison of our data with existing data from meerfelder maar we analyse the short term environmental evolution in western europe during the studied time interval and confirm the previously reported delayed hydrological response to greenland cooling however despite a detected delay of western european environmental change of 135 years our biomarker data show statistically significant correlation with deuterium excess in greenland ice core at annual resolution during this time transgressive cooling this suggests a coherent atmospheric forcing across the north atlantic realm during this transition we propose that western european cooling was postponed due to major reorganization of the westerlies that were intermittently forcing warmer and wetter air masses from lower latitudes to western europe and thus resulted in delayed cooling relative to greenland

vegetation and palaeoclimate in the miocene of ukraine miocene deposits marine and terrestrial distributed throughout the whole territory of ukraine contain numerous palaeontological remains including plant macro and microfossils there are well known occurrences of fossil leaves as well as fruits and seeds the miocene strata of ukraine belong to the central and the eastern paratethys and deposits from these regions have been studied palynologically for the reconstruction of the vegetation of lowland and mountain areas in ukraine palynological data have been complemented with data obtained from carpological and foliar studies to obtain quantitative climate data microfloral records from the ukraine plain and the ukrainian carpathians are analyzed using the coexistence approach the main trends of floral changes were directed by the global climate evolution complicated by regional tectonic processes major vegetation change occurred during the late miocene cooling in southern ukraine the cooling was accompanied by a gradual drying and partial replacement of forest vegetation by herbaceous communities that increased in richness and expanded from east to west

least squares migration of incomplete reflection data a least squares migration algorithm is presented that reduces the migration artifacts i e recording footprint noise arising from incomplete data instead of migrating data with the adjoint of the forward modeling operator the normal equations are inverted by using a preconditioned linear conjugate gradient scheme that employs regularization the modeling operator is constructed from an asymptotic acoustic integral equation and its adjoint is the kirchhoff migration operator we tested the performance of the least squares migration on synthetic and field data in the cases of limited recording aperture coarse sampling and acquisition gaps in the data numerical results show that the least squares migrated sections are typically more focused than are the corresponding kirchhoff migrated sections and their reflectivity frequency distributions are closer to those of the true model frequency distribution regularization helps attenuate migration artifacts and provides a sharper better frequency distribution of estimated reflectivity the least squares migrated sections can be used to predict the missing data traces and interpolate and extrapolate them according to the governing modeling equations several field data examples are presented a ground penetrating radar data example demonstrates the suppression of the recording footprint noise due to a limited aperture a large gap and an undersampled receiver line in addition better fault resolution was achieved after applying least squares migration to a poststack marine data set and a reverse vertical seismic profiling example shows that the recording footprint noise due to a coarse receiver interval can be suppressed by least squares migration

dynamic modeling of the transition from passive to active rifting application to the pannonian basin we examine a number of first order features of pannonian basin evolution in terms of the feedback relation between passive far field induced extension and active raleigh taylor instable upwelling of the astheno sphere we show that active mantle upwelling following a phase of passive extension are viable mechanisms ex plaining the pannonian basin formation the dynamic interplay between far field driven passive extension and active thinning of the mantle lithosphere by convective upwelling beneath the rift zone is modeled using ther momechanical finite element methods our modeling results predict a first phase of passive lithospheric thin ning which is followed by a second phase of late synrift to postrift active mantle lithosphere thinning due to buoyancy induced flow beneath the rift zone we argue that the pattern of coeval extension in the thinning re gion and compression in the flanking regions may be explained by the buoyancy forces due to lithosphere thinning it is demonstrated that timescales of and stresses generated by both processes are comparable the model appears also to explain the occurrence of late shallow mantle related decompression melts in the pannonian region and late regional doming

interpretation of u th he single grain ages from slowly cooled crustal terranes a case study from the transantarctic mountains of southern victoria land low temperature thermochronologic techniques e g apatite fission track aft thermochronology and u th he dating constrain near surface t t paths and are often applied to uplift denudation and landscape evolution studies samples collected in vertical profiles from granitic walls on either side of the ferrar glacier southern victoria land antarctica were analyzed using aft thermochronology and apatite u th he dating to further constrain the lowest temperature thermal history of this portion of the transantarctic mountains aft central ages vary systematically with elevation and together with track length information define a multi stage cooling denudation history in the cretaceous and early tertiary apatite u th he single grain age variation with elevation is not as systematic with considerable intra sample age variation although many complicating factors e g u and th rich micro inclusions fluid inclusions variation in crystal size particle ejection correction zonation and particle ejection correction implantation of he into a crystal or impediment of he diffusion out of a crystal and 147sm derived particles may contribute to age dispersion we found that variation in single grain ages correlated with cooling rate samples that cooled relatively quickly have less variation in single grain ages whereas samples that cooled relatively slowly 3 c m y or resided within an u th he partial retention zone heprz prior to more rapid cooling have a comparatively greater variation in ages decay of u and th via particle emission creates a 4he concentration profile dependent upon the initial parent u th within a crystal variation of single grain ages for samples with non homogeneous u th distributions will be enhanced with long residence time in the partial retention zone i e slow cooling because of the relative importance of loss via volume diffusion and loss via particle ejection with respect to the u th zonation and the grain boundary correction of ages for particle ejection ft correction factor typically assumes uniform u and th distribution within the crystal and when applied to a population of crystals with different u and th distributions will enhance the variation in ages most complicating factors listed above for apatite u th he ages result in ages that are too old we propose that if considerable variation in u th he single grain ages exists that a weighted mean age is determined once outlier single crystal ages are excluded using the criterion of chauvenet or a similar approach we suggest that the true age or most representative age for that age population lies between the minimum u th he age and the weighted mean age we apply this approach coupled with composite age profiles to better constrain the t t history of the profiles along the ferrar glacier significant intra sample variation in single crystal apatite u th he ages and other minerals dated by the u th he method should be expected especially when the cooling rate is slow the variation of u th he single crystal ages is therefore another parameter that can be used to constrain low temperature thermal histories