mechanical significance of structural patterns identified by remote sensing studies a multiscale analysis of tectonic structures in crimea abstract based on remote sensing analyses of two panchromatic spot scenes that cover the western and eastern parts of crimea completed with the study of landsat thematic mapper scenes and local aerial photographs we determined the geometry of major structures folds and fractures the strikes of large fractures are quite homogeneous in the studied area three important sets are common n10 ne sw and nw se two strikes are particularly developed in the western part of crimea n25 and n105 along important faults we recognised the sense of motion which often corresponds to the latest or to the major stages of movement we also determined stress tensors by inversion of microtectonic data sets collected in the field combining remote sensing analysis with mechanical studies provides new views on the structural evolution of crimea we thus characterised major tectonic events responsible for most of the deformation in eastern crimea the structural patterns fit well with two major tectonic events 1 the latest one is a plio quaternary faulting event normal slip along n10 faults and strike slip motion along n10 and nw se faults corresponding to a transtensional regime with 3 trending e w 2 large fractures nw se and ne sw sets and fold and thrust development reveal a transpressional regime with 1 trending nne ssw during the berriasian in western crimea we characterised a more complex pattern of four major tectonic events 1 the plio quaternary tectonic phase induced left lateral displacement along nw se faults and normal slip along wsw ene faults and this deformation is in agreement with the strike slip regime that we reconstructed with 3 trending nne ssw 2 as for eastern crimea the berriasian phase was well expressed with folds thrusts and strike slip faults under a transpressional regime with 1 trending n s to nnw sse the two other events well identified in western crimea are 3 a n s directed extension that developed large n105 faults and 4 a nw se directed extension involving ne sw normal faults that we relate to the development of peripheral troughs in the oligocene western crimea suffered a more complicated structural evolution than eastern crimea from eastern to western crimea we also noticed the systematic deviation in the trends of the principal stress axes of the recent stress field and in the berriasian stress field as well these differences may be related to the presence of a major crustal discontinuity the transverse alushta simferopol fault

an offshore onland transect across the north eastern black sea basin crimean margin evidence of paleocene to pliocene two stage compression abstract the tectonic evolution of the black sea bs is a subject of debate there are several unsolved questions 1 the timing and the spatial progression of the bs basin opening and 2 the timing of cenozoic shortening along the northern margin of the eastern bs basin the timing of the main compressional deformations related to the inversion of the greater caucasus gc basin is assumed to be oligo miocene however late cretaceous early paleocene shortening linked to the final closure of the northern branch of the neotethys is also suggested the crimean mountains cm to the north of the eastern bs is one of the key areas to investigate in order to fix the tectonic evolution of the bs to precise the timing of the cenozoic shortening of the eastern bs we focus on an integrated onshore offshore transect from the eastern cm to the sorokin trough north of eastern bs we use newly collected stratigraphic and structural data from the eastern cm and a new interpretation of multichannel seismic lines we define 1 the offshore seismic stratigraphy and constrain the relative chronology of deformations 2 the age of seismic units by correlation of the seismic data with the subbotina 403 well log and 3 we construct an on to off shore transect of eastern cm northern eastern bs region our results evidence a polyphased cenozoic compression in the northern part of the eastern bs 1 paleocene earliest eocene and 2 oligocene miocene maikopian normal faults appear to be related to a formation of the foreland basin instead of evidencing the eastern bs cretaceous rifting finally this study allows precising the shortening phases within eastern cm and eastern bs since the early paleocene linking them to the neotethys closure and the gc tectonic evolution

high resolution palaeosecular variation in northern europe during the last 3200 years variations in the declination inclination and relative palaeointensity of earth s magnetic field during the last 3200 yr have been recorded from a sequence of annually laminated sediments in lake pohjajarvi lat 62 n central finland the magnetic mineralogy is uniform with only small variations in concentration of magnetite of pseudo single domain psd grain size the variations in direction were found to be very similar to records reconstructed from other lakes in finland and northwest russia while the relative palaeointensity curve can be correlated accurately with archaeomagnetic data from central europe

evolution of paleostress fields and brittle deformation of the tornquist zone in scania sweden during permo mesozoic and cenozoic times abstract the nw se oriented sorgenfrei tornquist zone stz has been thoroughly studied during the last 25 years especially by means of well data and seismic profiles we present the results of a first brittle tectonic analysis based on about 850 dykes veins and minor fault slip data measured in the field in scania including paleostress reconstruction we discuss the relationships between normal and strike slip faulting in scania since the permian extension to the late cretaceous tertiary structural inversions our paleostress determinations reveal six successive or coeval main stress states in the evolution of scania since the permian two stress states correspond to normal faulting with ne sw and nw se extensions one stress state is mainly of reverse type with ne sw compression and three stress states are strike slip in type with nnw sse wnw ese and nne ssw directions of compression the ne sw extension partly corresponds to the late carboniferous permian important extensional period dated by dykes and fault mineralisations however extension existed along a similar direction during the mesozoic it has been locally observed until within the danian a perpendicular nw se extension reveals the occurrence of stress permutations the nnw sse strike slip episode is also expected to belong to the late carboniferous permian episode and is interpreted in terms of right lateral wrench faulting along stz oriented faults the inversion process has been characterised by reverse and strike slip faulting related to the ne sw compressional stress state this study highlights the importance of extensional tectonics in northwest europe since the end of the palaeozoic until the end of the cretaceous the importance and role of wrench faulting in the tectonic evolution of the sorgenfrei tornquist zone are discussed

influence of secular variation of the geomagnetic field on production rates of in situ produced cosmogenic nuclides abstract scaling factors are presented that allow a full description of the cosmic ray flux modulation during secular variation of the geomagnetic field these scaling factors are analogous to those determined in a similar work dunai t j earth planet sci lett 2000 176 157 169 that were accurate for field strengths equivalent to present day field strength but cannot accommodate field strength variations strategies to derive the relevant geomagnetic field parameters are discussed and are tested with existing production rate calibrations for 3 he a production rate of 103 4 2 atoms g olivine yr sea level and for zero cutoff rigidity was derived from calibration sites from hawaii western usa and canary islands covering the time range of 2 281 kyr

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

age and geodynamic evolution of the black sea basin tectonic evidences of rifting in crimea the timing and direction of opening of the black sea basin are debated however parts of its margins were inverted during cenozoic and can be studied onshore the crimean mountains are located in the middle of the northern margin of the basin and at the onshore prolongation of the mid black sea high we present the first detailed mapping of large striated normal faults in crimea these faults define graben structures that trend parallel to the continental margin kinematic analysis of the faults combined with new biostratigraphic data show that the syn rift sequence is valanginian to late albian in age it consists of siliciclastic deposits with limestone olistoliths in contrast the post rift late cretaceous carbonaceous sequence of crimea is devoid of normal faults or olistoliths it unconformably overlies the graben structures the onset ages and the trends of extension are quite similar in the northern crimea and the southern turkey inverted margins of the basin the early cretaceous extension directions are normal to the mid black sea high and the black sea margins we conclude that rifting of black sea basin occurred from the valanginian to the late albian 39 ma and drifting during the late cretaceous based on the directions of rifting on the lack of evidence of strike slip motions near the mid black sea high and on published paleomagnetic data we propose that the black sea opened with rotations accommodated by transform faults at its western and eastern margins as a response to asymmetric slab rollbacks of the neo tethys plate the inversion of the crimean margin results from two successive shortening events early eocene ne sw compression eocene to present se nw compression their timing support the idea that compressional stresses generated by continental collisions in turkey were transmitted through the strong black sea lithosphere up to crimea

10be derived sub milankovitch chronology of late pleistocene alluvial terraces along the piedmont of sw tian shan abstract using topographic maps and terrestrial cosmogenic nuclide tcn 10be exposure dating methods we reconstructed a chronology with robust age constraints based on four alluvial terrace abandonment features in two study sites along the sw piedmont of kepingtage mountain in sw tian shan agreement between alluvial terrace abandonment ages and guliya ice core 18o lr04 stack of benthic 18o epica dome c ch4 and solar insolation records suggests that alluvial terraces with 10be age sequences at 63 7 5 9 ka 40 9 3 84 ka 36 2 3 4 ka and 22 1 5 1 4 7 ka correspond to three wetter climate intervals possibly triggered by intensified south asian summer monsoons since the late pleistocene given that the active thrust kepingtage fault experienced sustained uplift during this period we suggest that the abandonment of alluvial terraces that formed since 22 1 5 1 4 7 ka may be related to sudden tectonic uplift the occurrence of these four younger well preserved alluvial terraces may also be related to the fact that the transient climatic incision has been no higher than the temporary tectonic uplift since 22 1 5 1 4 7 ka

inversion of field data in fault tectonics to obtain the regional stress iii a new rapid direct inversion method by analytical means summary a new method for determining the reduced stress tensor with four degrees of freedom the orientations of the three principal stress axes as well as the ratio of principal stress differences using fault slip data or focal mechanisms of earthquakes is presented from a computational point of view the inversion of fault slip data is made in a direct way by purely analytical means as a result the determination process is extremely fast and adaptable on small microcomputers from a physical point of view the method aims at simultaneously i minimizing the angles between theoretical shear stress and actual slip vector and ii having relative magnitudes of shear stress large enough to induce slip despite rock cohesion and friction examples of application to actual fault slip data sets with good or poor variety of fault slip orientations are shown the double significance of the basic criterion adopted results in a more realistic solution of the inverse problem than the single minimization of the shear stria angle

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

key problems of stratigraphy in the eastern crimea peninsula some insights from new dating and structural data the tectonic evolution of the eastern black sea basin has previously been explained based on offshore and onshore data some of the latter from the crimean mountains cm however changes in the stratigraphy of the cm have recently been proposed the late triassic early jurassic tauric group was assigned as younger albian to clarify the stratigraphy and the tectonic evolution of this area we sampled the eastern cm for micropalaeontological datings nannoplankton the results demonstrate an early cretaceous age for the tauric group in the eastern cm the samples contained substantial amounts of volcanic ash indicating a period of magmatic activity along all the eastern cm our field observations allowed us to propose a new structural map and cross sections using which three main tectonic units were distinguished we define a phase of extension during the early cretaceous and one of shortening during the paleocene early eocene before the main middle eocene limestone unconformity these two phases are related to 1 the opening of the eastern black sea basin along nnw sse trending normal faults and the associated magmatism and 2 north south shortening that could be comparable with the inversion in dobrogea and or with north south shortening linked to the collision of continental blocks in the pontides and taurides domains

a new rock magnetic approach to selecting sediments for geomagnetic paleointensity studies application to paleointensity for the last 4000 years the hypothesis that the ratio of detrital remanent magnetization to anhysteretic remanent magnetization drm arm for sediment samples is a measure of relative geomagnetic paleointensity is critically evaluated by two distinct approaches one approach is a detailed rock magnetic examination of the implicit assumptions of the drm arm method and the construction of a selection process by which to identify sediments that conform to requirements satisfying these assumptions sediments are uniform with respect to drm arm ratio if they contain magnetite in the 1 15 ym particle size range as the predominant magnetic mineral and have variations in magnetite content of less than 20 30 times the minimum concentration the drm arm ratios of these sediments should provide estimates of relative geomagnetic paleointensity relative particle size variations in magnetite are detected with a plot of anhysteretic susceptibility xarm versus low field susceptibility x and the size range 1 15 m is approximately identified by high field hysteresis parameters a rock magnetic evaluation of leboeuf lake sediments with these techniques indicates that these sediments are suitable for a relative plaeointensity study the second approach to evaluating the drm arm ratio as a measure of relative paleointensity is direct comparison with absolute paleointensity data a comparison between the leboeuf lake estimates and thellier thellier results from the western united states supports the conclusion that suitable sediments can record geomagnetic paleointensity fluctuations

geomagnetic paleointensity for the last 100 kyr from the sub antarctic south atlantic a tool for inter hemispheric correlation abstract we report relative paleointensity proxy records from four piston cores collected near the agulhas ridge and meteor rise south atlantic the mean sedimentation rate of the cores varies from 24 cm kyr to 11 cm kyr the two cores with mean sedimentation rates over 20 cm kyr record positive remanence inclinations at 40 41 ka coeval with the laschamp event age models are based on oxygen isotope data from three of the cores augmented by radiocarbon ages from nearby core rc11 83 and by correlation of paleointensity records for the one core with no oxygen isotope data the relative paleointensity proxy records are the first from the south atlantic and from the high to mid latitude southern hemisphere prominent paleointensity lows at 40 ka and 65 ka as well as many other features can be correlated to paleointensity records of comparable resolution from the northern hemisphere the records are attributable in large part to the global scale field and therefore have potential for inter hemispheric correlation at a resolution difficult to achieve with isotope data alone

regional patterns of tectonic stress in europe nearly 1500 stress orientation determinations are now available for europe the data come from earthquake focal mechanisms overcoring measurements well bore breakouts hydraulic fracturing measurements and young fault slip studies and sample the stress field from the surface to seismogenic depths three distinct regional patterns of maximum compressive horizontal stress shmax orientation can be defined from these data a consistent nw to nnw shmax stress orientation in western europe a wnw ese shmax orientation in scandinavia similar to western europe but with a larger variability of shmax orientations and a consistent e w shmax orientation and n s extension in the aegean sea and western anatolia the different stress fields can be attributed to plate driving forces acting on the boundaries of the eurasian plate locally modified by lithospheric properties in different regions on average the orientation of maximum stress in western europe is subparallel to the direction of relative plate motion between africa and europe and is rotated 17 clockwise from the direction of absolute plate motion the uniformly oriented stress field in western europe coincides with thin to medium lithospheric thickness approximately 50 90 km and high heat flow values 80 m w m2 in western europe a predominance of strike slip focal mechanisms implies that the intermediate principal stress is vertical the more irregular horizontal stress orientations in scandinavia coincide with thick continental lithosphere 110 170 km and low heat flow 50 m w m2 the cold thick lithosphere in this region may result in lower mean stresses associated with far field tectonic forces and allow the stress field to be more easily perturbed by local effects such as deglaciation flexure and topography the stress field of the aegean sea and western anatolia is consistent with n s extension in a back arc setting behind the hellenic trench subduction zone the stress field is influenced in places by regional geologic structures e g in the western alps where shmax directions show a slight tendency toward a radial stress pattern not all major geologic structures however appear to affect the shmax orientation e g in the vicinity of the rhine rift system horizontal stress orientations are continuous

numerical modelling of drainage basin evolution and three dimensional alluvial fan stratigraphy abstract a forward numerical model is presented to study the effects of bedrock erodability thrust displacement rate pulsating tectonic activity and sea level fluctuations on drainage basin morphology and stratigraphy of large alluvial fan systems a low value of the bedrock erodability coefficient k b 0 5 10 4 year 2 3 vs thrust rate 2 0 m ky is associated with a time lag between cessation of tectonic activity and maximum sedimentation rates observed on the alluvial fans applying higher k b values ranging between 1 0 and 8 0 10 4 year 2 3 results in higher sediment yields due to more rapid headward catchment erosion and elaborate sideways branching of drainage networks pulsating tectonic activity is reflected in a stratigraphic alternation of prograding and retrograding alluvial fan gravels during tectonic activity fan gravel fronts and coastlines retreat because catchment yields are insufficient to fill the accommodation space created by the flexural response due to thrust loading phases of tectonic quiescence and cessation of flexural subsidence are indicated by progradation of the gravel front depending on the position in the basin the lag time for arrival of the gravel associated with tectonic cessation is several tens to hundred thousands of years a combination of pulsed tectonic activity with sinuous sea level fluctuation leads to a more complex stratigraphic pattern in that case stratigraphic response to tectonic pulses is masked by a similar but higher order frequency stacking pattern especially in the more distal parts

alluvial fan morphology distribution and formation on titan abstract titan is a hydrologically active world with dozens of alluvial fans that are evidence of sediment transport from high to low elevations however the distribution and requirements for the formation of fans on titan are not well understood we performed the first global survey of alluvial fans on titan using cassini synthetic aperture radar sar data which cover 61 of titan s surface we identified 82 fans with areas ranging from 28 km2 to 27 000 km2 a significant fraction 60 of the fans are restricted to latitudes of 50 80 suggesting that fluvial sediment transport may have been concentrated in the near polar terrains in the geologically recent past the density of fans is also found to be correlated with the latitudes predicted to have the highest precipitation rates by titan global circulation models in equatorial regions observable fans are not generally found in proximity to dune fields such observations suggest that sediment transport in these areas is dominated by aeolian transport mechanisms though with some degree of recent equatorial fluvial activity the fan area drainage area relationship on titan is more similar to that on earth than on mars suggesting that the fans on titan are smaller than what may be expected and that the transport of bedload sediment is limited we hypothesize that this has led to the development of a coarse gravel lag deposit over much of titan s surface such a model explains both the morphology of the fans and their latitudinal concentration yielding insight into the sediment transport regimes that operate across titan today

palaeosecular variation of the earth s magnetic field during the last 10000 years based on the annually laminated sediment of lake nautajarvi central finland a palaeomagnetic study of the lake nautajarvi sediment sequence in central finland demonstrates that varved lake sediments can provideregionally applicable secular variations curves for holocene stratigraphic correlation and age control based on x ray radiography and digital image analysis techniques we constructed an inherent and continuous varve chronology for the lake nautajarvi varve sequence which covers nearly 10000 years with an estimated counting error of less than 1 and a mean sedimentation rate of 0 66 mm yr 1 we reconstructed a record of the palaeomagnetic secular variation psv of the earth s magnetic field in this nearly 7 m long section of clastic organic varves mineral magnetic measurements indicated that pseudosingle domain magnetite is the major carrier of the remanence psv shows many of the familiar features of declination and inclination that have previously been recorded in northern europe in addition the lake nautajarvi record contains a continuous record of relative palaeoi

a magnetostratigraphic comparison between 14c years and varve years during the late weichselian indicating significant differences between the time scales a 14c dated magnetostratigraphy of absolute declination and inclination between 12500 and 10000 14c yr bp was recently developed for southern sweden recently also the swedish geochronological time scale based on c 11 500 annually deposited clay varves was connected with the present it should therefore be possible to compare the two chronologies with a reliable magnetostratigraphic record in an appropriate clay varve section we have found such a site within the middle swedish end moraine zone statistical correlations between the two independently dated time scales suggest that at 10500 10200 14cy r bp the varve chronology exceeds the 14c chronology by the order of 500 600 varve yr other correlations indicate that the difference between the two chronologies was less at 11000 14c yr bp and further correlations between the time scales at 12000 14c yr bp suggest that the difference between the chronologies increased steadily from 12000 to 10000 14c yr bp if these correlations are correct they imply that the 14c production rate increased steadily during the late weichselian

the mineral magnetic properties of an annually laminated holocene lake sediment sequence in northern sweden detailed mineral magnetic measurements were conducted on a 9000 year varved lake sediment sequence in northern sweden lake sarsjon the results demonstrate that the paramagnetic susceptibility reflects the concentration of detrital minerogenic material in the lake sediments which is controlled to a large extent by the intensity of the spring snow melt in contrast the concentration of ferrimagnetic magnetite reflected by initial magnetic susceptibility and magnetic hysteresis parameters is positively correlated to the concentration of organic carbon which is most likely of an autochthonous origin this magnetite has magnetic properties that are characteristic of stable single domain magnetite grains produced by magnetotactic bacteria the paramagnetic susceptibility record clearly points to a climatic excursion in the early holocene between 6100 174 bc and 5700 167 bc which can be correlated to an d18o excursion a cold event in the greenland ice cores and lake sediments in southern germany an

contractional kink bands formed by stress deflection along pre existing anisotropies examples from the anglo brabant deformation belt belgium and the north dobrogea orogen romania abstract kink bands within two slate belts the anglo brabant deformation belt belgium and the north dobrogea orogen romania reveal similar problems with respect to linking kink band geometries to expected palaeostress directions in the north dobrogea orogen the two opposite kink band sets of two different systems of conjugate kink bands develop for a wide variety of cleavage orientations in the anglo brabant deformation belt the occurrence of the two opposite kink band sets of a conjugate kink band system opposes the expected occurrence in both cases this can be attributed to stress deflection along a pre existing anisotropy moreover the presence of kink bands in the north dobrogea orogen with curving kink axes and curving kink band boundaries also puts doubt on the direct relationship between kink band geometry and stress the idea of stress deflection along a pre existing anisotropy and the strong control of the pre existing anisotropy on the kink band geometry and orientation has important implications for the use of kink bands as regional palaeostress indicators depending on the relative intensity and relative orientation of the pre existing fabrics here bedding and cleavage different mechanisms of kink band development may operate depending on the mechanism different solutions in terms of inferred palaeostress direction may exist

icelandic holocene palaeolimnomagnetism abstract sediments spanning the last 9000 y from two sites in lake vatnsdalsvatn lat 66 n long 23 e in northwest iceland hold repeatable palaeomagnetic direction records the vatnsdalsvatn sediments have mean palaeomagnetic inclinations of 76 close to that expected for a geocentric axial dipole field and direction fluctuations of around 20 from the mean the palaeomagnetic directions are stable under alternating field partial demagnetization experiments a time scale for the vatnsdalsvatn sediments has been estimated from 14 c dating the pattern of palaeomagnetic secular change shows few similarities with british records 2000 km distant and a central north american record 5000 km distant

holocene climatic instability a prominent widespread event 8200 yr ago the most prominent holocene climatic event in greenland ice core proxies with approximately half the amplitude of the younger dryas occurred 8000 to 8400 yr ago this holocene event affected regions well beyond the north atlantic basin as shown by synchronous increases in windblown chemical indicators together with a significant decrease in methane widespread proxy records from the tropics to the north polar regions show a short lived cool dry or windy event of similar age the spatial pattern of terrestrial and marine changes is similar to that of the younger dryas event suggesting a role for north atlantic thermohaline circulation possible forcings identified thus far for this holocene event are small consistent with recent model results indicating high sensitivity and strong linkages in the climatic system

seismic model of the crust and upper mantle in the scythian platform the dobre 5 profile across the north western black sea and the crimean peninsula the scythian platform scp with a heterogeneous basement of baikalian variscan cimmerian age is located between the east european craton eec on the north and the crimean caucasus orogenic belt and the black sea bs basin on the south in order to get new constrains on the basin architecture and crustal structure of the scp and a better understanding of the tectonic processes and evolution of the southern margin of the eec during mesozoic and cenozoic time a 630 km long seismic wide angle refraction and reflection warr profile dobre 5 was acquired in 2011 october it crosses in a w e direction the fore dobrudja trough the odessa shelf of the bs and the crimean plain the field acquisition included eight chemical shot points located every 50 km and recorded by 215 stations placed every 2 0 km on the land in addition the offshore data from existing profile 26 placed in the odessa shelf were used the obtained seismic model shows clear lateral segmentation of the crust within the study region on four domains the fore dobrudja domain km 20 160 an offshore domain of the karkinit trough at the odessa shelf of the bs km 160 360 an onshore domain of the central crimean uplift crimean plain km 360 520 and the indolo kuban trough at the kerch peninsula km 520 620 that is the easternmost part of the crimea two contrasting domains of the scp within the central part of the dobre 5 profile the karkinit trough and the central crimean uplift may represent different stages of the scp formation a deep karkinit trough with an underlying high velocity 7 16 km s 1 lower crust body suggests its rifting related origin during early cretaceous time the central crimean uplift represents a thick up to 47 km crustal domain consisting of three layers with velocities 5 8 6 4 6 5 6 6 and 6 7 7 0 km s 1 which could be evidence of this part of the scp originating on the crust of precambrian craton eec the thick heterogeneous basement of the central crimean uplift shows inclusions of granitic bodies associated with magmatic activity related with variscan orogeny within the scp general bending and crustal scale buckling of the central crimean uplift with a wavelength of 230 km could be an effect of the alpine compressional tectonics in the adjacent crimean mountains the extended rifted continental margin of the scp eec at the odessa shelf and buckling uplifted domain of the central crimean uplift affected by compressional tectonics are separated by the n s oriented western crimean fault the crust of the southern margin of the eec is separated from the scp which originated on the eec crust tectonised and reworked during the palaeozoic mesozoic by the crustal fault of w e orientation which corresponds with the golitsyn fault observed at the surface between the eec and the scp the fore dobrudja domain with a thick 10 km heterogeneous basement and two subhorizontal layers in the crystalline crust with velocities 6 2 6 3 and 6 4 6 65 km s 1 differs from the scp crust and its origin could be very similar to that of the trans european suture zone and palaeozoic west european platform

favoured states of palaeostress in the earth s crust evidence from fault slip data abstract in a major survey of published palaeostress estimates obtained by the use of fault slip data over 2000 stress tensors from shallow crustal levels have been compiled the results are derived from regions where deformation is dominated by brittle processes and consist of incomplete stress tensors in which the orientations of the principal stresses 1 2 3 are known together with the stress ratio 2 3 1 3 the orientations of the stress axes display a preferred orientation with a tendency for one of the axes to be vertical this accords with anderson s assumed standard state stress configuration near to the earth s free surface although the tendency is strong there are frequent deviations from the arrangement in 25 of cases the steepest stress axis deviates by more than 25 from the vertical in undertaking studies of palaeostress it would be therefore unwise to use methods that assume a priori one vertical stress axis unless previous local results indicate this to be the case normal strike slip and thrust stress arrangements with 1 2 and 3 as the steepest stress respectively occur in the database with frequencies approximately in the ratio 2 2 1 in the compiled results the raw stress ratios which have a theoretical range from 0 to 1 show a lack of very high values and to a lesser extent very low values this suggests that triaxial stress states are more common than axial compression deviatoric stress and axial tension deviatoric stress however this relative abundance of triaxial stress states is considered to be a natural feature of a uniform distribution of stress tensors in addition there is a marked bias in the collated ratios towards values less than 0 5 and this is expressed by an overall mean of 0 39 several possible explanations for the distribution of stress ratios are discussed these explanations are related to the tendency for tectonic deformation to be of plane strain type coupled with volume change and to the fact that gravitational loading makes an important contribution to the state of stress in the crust

magnetic hysteresis properties of greigite fe3s4 and a new occurrence in holocene sediments from swedish lappland a new occurrence of ferrimagnetic greigite fe3s4 is reported in freshwater holocene sediments from gaskkamus gorsajavri in swedish lappland the presence of greigite was inferred from the mineral magnetic analysis of sediment cores the greigite bearing sediments possess a high saturation isothermal remanent magnetisation to susceptibility sirm ratio a characteristic shared by other natural sediments known to contain greigite the hysteresis properties measured using a vibrating sample magnetometer of natural greigite extracted from lake sediments show much higher saturation coercivity b0 c and mrsms ratio values approximately 50 mt and 0 5 respectively than synthetic samples of greigite approximately 12 mt and 0 2 the results suggest that synthetic greigite samples contain crystals ranging from small non remanence carrying superparamagnetic grains to large multi domain grains in contrast the natural samples probably consist predominantly of pseudo single domain and single domain crystals capable of carrying a chemical remanent magnetisation however the unstable nature of greigite under laboratory conditions creates difficulty in characterising its physical attributes

structural and geodynamic ideas on the galati izvoarele seismic prone area eastern romania the galati izvoarele region located in eastern romania came into the public attention relatively recent when hosted an unusual intense earthquake sequence during september november 2013 several hundred shallow crust earthquakes were recorded in the area there were several attempts to explain the phenomenon and hypotheses more or less documented have been formed some speculations occurred on the potential connection between the seismic swarm and oil industry activities the paper summarizes the results of local geophysical surveys conducted in the area jointly analysed with the observed seismicity the main results of the study reveal the galati izvoarele region as a seismic active area belonging to the northwest prolongation of north dobrogea mobile zone the earthquakes were generated mainly in a highly fragmented local graben like structure transversally superposed on the descending slope of the north dobrogea promontory the graben fault system was and might be re activated each time when tectonic forces acting in the carpathians foreland intensify changes in the intensity of tectonic forces may reflect in the slip acceleration along peceneaga camena fault as observed at the baspunar geodynamic observatory for example the paroxysmal phase of the galati izvoarele swarm was shortly preceded by a significant increase of the peceneaga camena fault slip rate recorded at baspunar geodynamic observatory to conclude the galati izvoarele region must be seen as a seismic prone area and any significant increase of the tectonic stress in the carpathians foreland may generate another seismic sequence in an unpredictable future

relative paleointensity of the geomagnetic field during the brunhes chron abstract we conducted a paleomagnetic study of four sediment cores taken from different regions in the low latitudes of the pacific ocean in order to recover relative paleointensity variations during the brunhes chron three cores have good age control from oxygen isotope stratigraphy we extensively examined rock magnetic uniformity by the iso thermal remanent magnetization irm acquisition and the alternating field demagnetization of the anhysteretic remanent magnetization arm and the irm only rock magnetically homogeneous sediments were used biogenic magnetites were found in all but one core and their dissolution in early diagenesis was not significant the four cores showed coherent variations of the remanent intensity normalized by the arm implying that these variations represent the behavior of the geomagnetic field long term paleointensity variations during the brunhes chron are characterized by an asymmetric pattern rapid increases in the intensity occurred just after the brunhes matuyama transition in the mid brunhes from about 500 to 400 ka and during the last 100 ka and gradual decreases between them the first one supports the idea of rapid regeneration of the geomagnetic field after polarity reversals 1 the other two may have been triggered by very short polarity reversals

influence of lithologic erodibility on alluvial fan area western white mountains california and nevada differences in lithologic erodibility and sediment storage within a drainage basin affect the relationship between alluvial fan area and drainage basin area along the western white mountains large fans are produced by basins underlain by resistant rocks which have steep and narrow trunk stream canyons with little sediment in storage small fans are produced by basins composed of erodible lithologic units which have wider valley floors lower valley side slopes and considerably more sediment stored along trunk stream canyons than is the case in basins underlain by resistant rocks

comparison of oxygen isotope records from the gisp2 and grip greenland ice cores recent results1 2 from the greenland ice core project grip summit ice core suggest that the climate in greenland has been remarkably stable during the holocene but was extremely unstable for the time period represented by the rest of the core spanning the last two glaciations and the intervening eemian inter glacial here we present the complete oxygen isotope record for the greenland ice sheet project 2 gisp2 core drilled 28 km west of the grip core we observe large rapid climate fluctuations throughout the last glacial period which closely match those reported for the grip core however in the bottom 10 of the cores spanning the eemian interglacial and the previous glacia tion there are significant differences between the two records it is possible that ice flow may have altered the chronological sequences of the stratigraphy for the bottom part of one or both of the cores considerable further work will be necessary to evaluate the likelihood of this and the extent to which it will still be possible to extract meaningful climate information from the lowest sections of the cores

ams radiocarbon dating of organic poor lake sediment an example from linnevatnet spitsbergen svalbard ams radiocarbon dating of specific organic fractions is used to evaluate sources of errors in dating of organic poor lake sediment from linnevatnet a proglacial arctic lake dates on un differentiated bulk organic matter are much too old because of contamination from detrital coal attempts to remove coal from other organic matter were only partially successful a consequence of the wide grain size distribution of the coal even if coal contamination is fully removed the bulk of the remaining organic matter is of aquatic origin and is unsuitable for 14c dating because the lake waters are depleted in 14 c due to dissolution of carbonate minerals terrestrial plant macrofossils provide the only reliable material to date the lake sediment however this material is present in sufficient quantity for ams radiocarbon dating only in cores proximal to the main inlet streams paired dates on terrestrial plants and aquatic insects from the same core level and paired dates on modern aquatic and terrestrial vege

the tectonic expression slab pull at continental convergent boundaries examination of five thrust belt systems developed at continental subduction boundaries suggests that they comprise two distinct groups that display pronounced and systematic differences in structural style topographic elevation denudation metamorphism postcollisional convergence and foredeep basin geometry and facies the distinctive geological features developed within each thrust belt group appear to be causally linked to the relative rates of subduction and convergence via the magnitude of horizontal compressional stress transmitted across the subduction boundary at subduction boundaries where the rate of overall plate convergence is less than the rate of subduction termed here retreating subduction boundaries the transmission of horizontal compressive stress across the plate boundary is small and regional deformation of the overriding plate is by horizontal extension the tectonic expression of these retreating subduction boundaries includes topographically low mountains little erosion or denudation low grade to no metamorphism little to no involvement of crystalline basement in shortening little to no postcollisional convergence anomalously deep foredeep basins and a protracted history of flysch deposition within the adjacent foredeep basin analysis of deflection and gravity data across three retreating subduction boundaries apennine carpathian and hellenic systems shows that subduction is driven by gravitational forces acting on dense subducted slabs at depths between about 40 and 80 km carpathians 50 and 150 km apennines and 50 and 250 km hellenides the total mass anomalies represented by the slabs are approximately 3 1012 6 1012 and 12 1012 n m respectively the slabs are partially supported by flexural stresses transmitted through the subducted lithosphere to the foreland and partially supported by dynamic viscous stresses in the asthenosphere at subduction boundaries where the rate of overall plate convergence is greater than the rate of subduction termed here advancing subduction boundaries the transmission of horizontal compressive stress across the plate boundary is large and regional deformation of the overriding plate is by horizontal shortening the tectonic expression of these advancing subduction boundaries includes topographically high mountains antithetic thrust belts large amounts of erosion and denudation exposure of high grade metamorphic rocks at the surface extensive deformation of crystalline basement to midcrustal depths protracted postcollisional convergence tens of millions of years and a protracted history of molasse deposition within the adjacent foredeep basins analysis of gravity and deflection data across two advancing subduction boundaries developed within the continental lithosphere western to eastern and southern alps and himalayas shows that the thrust sheets have been translated for great distances over the foreland lithosphere relative to the point at which the subduction forces are applied thus obscuring any flexural and gravity signals from the subducted slab however it appears that far field stresses presumably related to global plate motions drive most of the convergent motion across these subduction boundaries the concept that orogenic belts formed above retreating subduction boundaries have recognizable tectonic signatures that differ from those of orogenic belts formed above advancing subduction boundaries suggests that it may be possible to interpret the plate boundary settings in which ancient orogenic belts evolved appendix b is available with entire article on microfiche order from the american geophysical union 2000 floridaavenue n w washington d c 20009 document t92 004 2 50 payment must accompany order

bacterial magnetite and the magnetic properties of sediments in a swedish lake a comparison of the magnetic properties of lake sediments and catchment materials from pajep njakajaure north sweden demonstrates that high concentrations of single domain sd magnetite in the upper 70 cm of gyttja in the deepest part of the basin are not of detrital origin tem and light microscope examination revealed the existence of bacterial cells and magnetosomes in the upper sediments which are responsible for the presence of the sd magnetite most of the fossil magnetosomes appear to have been dissolved through reductive processes at lower depths although some are preserved in the lower sediments and carry a post depositional remanent magnetization pdrm the results highlight the complex effects of post depositional processes on mineral magnetic assemblages and natural remanent magnetization aquisition and demonstrate how mineral magnetic measurements may be used to identify magnetic grain size changes brought about by sediment diagenesis

on solar forcing of holocene climate evidence from scandinavia the focus of this study is the possible correlation between changes in the climate of scandinavian and changes in solar irradiation reliable information about holocene climatic change in sweden and norway is currently available from two main sources the 14c dating of pine wood retrieved from above the present pine tree limit and studies of glacier variations based on proglacial lacustrine sediments and on moraines the reconstructed alpine tree limit reveals that summer temperature in general was warmer during the early holo cene than it was during the late holocene superimposed on this general trend are several fluctuations of a few hundred years duration relatively cold periods with a duration of the order of 300 600 years occurred frequently during the holocene in this paper dates of the major climatic events are compared with an index of solar activity the so called 14c anomalies for most of the last 9000 years a good correspondence is demonstrated between the timing of cold events in scandi

modeling alluvial landform change in the absence of external environmental forcing alluvial fan evolution and morphology are often considered to respond primarily to external forcing e g tectonics climate and base level change here we present a numerical model of alluvial fan evolution that shows that dramatic and persistent fan entrenchment may occur in the absence of such forcing this process is driven by positive autogenic feedbacks between flow width sediment transport and rate of fan aggradation entrenchment is initiated where sediment accommodation space limits continued fan growth our results highlight a need to rethink both the representation of fluvial width adjustment in landscape evolution models and the established framework for the interpretation of fluvial landforms as archives of environmental change

deep seismic survey images crustal structure of tornquist zone beneath southern baltic sea the tornquist zone is europe s longest tectonic lineament and bisects the continent in a nw se direction from the north sea off nw denmark to the black sea new deep seismic reflection and coinci

climate as main factor controlling the sequence development of two pleistocene alluvial fans in the vienna basin eastern austria a numerical modelling approach abstract tectonics climate base level and source lithology are the main controlling factors on alluvial fan development and evolution in this study a numerical model approach was used to investigate climate induced aggradation and degradation cycles the influence of tectonic subsidence and the impact of an axial main river on austria s largest pleistocene alluvial fan setting the mitterndorf basin eastern austria a simulation time frame of 25 ka was applied climatic variations were mainly modelled through variations in sediment supply whereas the impact of subsidence was modelled through variations in slip rates along faults incision and aggradation tendencies of the axial main river were modelled by rising or lowering of the water level the sequence development and geometry of mitterndorf basin s alluvial fans are mainly controlled by pleistocene climate oscillations cold periods generally led to a decrease in vegetation cover and to an increase of periglacial weathering processes which is associated with abundant sediment release and aggradation on fan surface in contrast decreasing sediment supply and increasing precipitation during warmer periods led to fan degradation our models indicate that the alluvial fan development is primarily affected by the distinct sediment supply pulses during phases of short climatic perturbations subsidence becomes the determining factor again when models approach a steady state behaviour similarly the impact of the axial main river becomes more important during simulated warm periods when sediment release to the drainage basin is low the overall basin slope additionally controls the evolution of fan and drainage variations in sediment supply and subsidence do also significantly control the long term evolution of the drainage network during simulated warm periods and thus control the sequence preservation potential of fans and therefore its long term sequence evolution

palaeomagnetic dating of late holocene sediments in fennoscandia abstract palaeomagnetic secular variation curves that have been dated by varve analysis counting annual laminations are used to date four holocene lacustrine sediment sequences from central finland and northwest russia lat 62 66 n several fine scale geomagnetic declination and inclination fluctuations can be identified during the last 3200 yr which is the most accurately dated interval in the present data relative palaeomagnetic dating is a powerful dating tool for sediments of large and deep lakes in northern europe which are difficult to date using the 14 c method because of low organic content contamination by older carbon and or scarcity of terrestrial macrofossils suitable for ams 14 c dating the dating error during the last 3200yr is estimated to be less than 50 yr such accuracy is not readily attainable using other methods

the deep seismic image of the crustal structure of the tornquist zone beneath the skagerrak sea northwestern europe abstract in the sw skagerrak sea a set of deep seismic profiles cross the tornquist zone a complex fault zone extending from the black sea to the north sea these sections show that the scandinavian segment of the tornquist zone represents the boundary between the thick crystalline crust of the fennoscandian shield to the northeast and the thinner basin crystalline crust to the southwest it is associated with a complex area of moho offsets and sub moho reflectors flexural subsidence of the shield edge appears to have occurred during the mesozoic without substantial thinning of the crust on the basin side the thinned crust together with the uppermost mantle appears to have been rigid enough to support segmentation and rotation of lithosphere blocks the deep and narrow fjerritslev trough is located at a bend of the tornquist zone and is observed to contain at least 15 km 8 5 s twt of sediments it is interpreted as a pull apart basin created by transtensional movements along the tornquist zone the presence of at least 6 km 3 s twt of palaeozoic sediments in the fjerritslev trough indicates that this segment of the tornquist zone was active also during this period

stratigraphic and structural characteristics of the romanian black sea shelf abstract the western black sea basin opened during cretaceous times by back arc rifting in association with a north dipping subduction at the rear of the cretaceous early tertiary pontide volcanic arc the sedimentary wedge developed on the shelf of the romanian black sea sector reflects a complex interplay between large scale rifting uplift of the orogenic flanks large scale post rift subsidence and sea level changes we examine the detailed structural configuration of this sector for a regional correlation with the adjacent offshore in ukraine and bulgaria the evolution of the western black sea basin started in the albian cenomanian times when two extensional phases with significantly different directions n s and subsequently e w lead to the formation of a complex interplay between isolated blocks organised in horsts and grabens generally deepening eastwards superposition of normal faults footwall blocks from the two extensional episodes generated a deeply subsided area with enhanced accommodation space i e the histria depression and consequently recorded a larger thickness of paleogene sediments in the post rift stage re activation of faults and associated folding reflects repeated inversion during the late cretaceous oligocene times associated with subsequent periods of non deposition and or erosion during moments of basin fill exposure these periods of inversion recorded in the black sea are controlled by coeval orogenic deformations taking place in the balkans pontides and the crimean thrust belt sea level fluctuations during the neogene and late alpine tectonics in the neighbouring orogens caused massive sedimentation followed by sediment starvation and or significant erosion large thicknesses of sediments accumulated during the pontian presumably associated with an extensional episode deepening the distal parts of the basin and with differential compaction structures the interpretation of a high quality seismic dataset combined with published data allowed the correlation of major structural units and lineaments defined onshore towards the carpathians with the ones deeply buried below the western black sea basin sediments unit correlations are furthermore used to derive an integrated tectonic image of the western black sea area

transcurrent nature of the teisseyre tornquist zone in central europe results of the polcrust 01 deep reflection seismic profile teisseyre tornquist zone ttz corresponds to a crustal boundary between the precambrian east european platform eep and the palaeozoic west european platform although the zone has been controlling phanerozoic evolution of large parts of central europe its course geometry and origin are still poorly constrained deep reflection seismic profile polcrust 01 recently acquired in se poland for the first time allowed a precise comparison of the ediacaran and later tectonic patterns to the deep crustal features of the ttz and adjacent areas the ttz corresponds to the subvertical tomaszow fault separating the radom kra nik elevation composed of the typical eep crust from the bilgoraj narol block bnb in the sw with a thinned crystalline basement showing affinities to the eep crust the bnb is a part of the larger caledonian ysogory terrane as evidenced by its lower palaeozoic stratigraphy and gravity data thus for the first time the proximal baltican affinity of this unit has been documented unambiguously the ysogory terrane is delimited from the sw by the subvertical cieszanow fault zone corresponding to the holy cross suture the adjacent malopolska terrane is characterized by a distinct early palaeozoic stratigraphy and lower middle crust exhibiting sw dipping reflective packages interpreted as ne verging thrust and shear zones of a neoproterozoic orogen the observations from the polcrust 01 profile and regional comparisons indicate that the ttz is a major caledonian transcurrent zone between poland and east romania in central poland the ttz likely forms a narrow subvertical contact between the eep and a proximal kuiavia terrane as constrained by the deep refraction seismic data to the nw the zone extends towards the pomeranian part of the caledonide fold and thrust belt related to the avalonia baltica collision zone thor suture south east of poland the ttz corresponds to the rava ruska fault zone established as a caledonian suture separating adjacent terrane probably of a baltican affinity the east romanian part of the ttz conforms with the sf ntu gheorghe fault separating reworked eep crust of the pre dobrogean depression from the north dobrogea unit bearing a strong variscan and cimmerian overprint

geodynamics of dobrogea romania new constraints on the evolution of the tornquist teisseyre line the black sea and the carpathians abstract dobrogea is the only place south of poland where the tornquist teisseyre line europe s longest lineament outcrops to characterize and date the tectonic activity of this line and to understand its relations with the neighboring structures e g the carpathians and the black sea basin the fracturing of late jurassic to neogene rocks in north central and south dobrogea is analyzed these paleostress reconstructions indicate that the dobrogea orogen was built under a n s compression with strain partitioning between thrusting at its front and dextral reverse slip along the peceneaga camena and capidava ovidiu faults during the late jurassic barremian from aptian to coniacian the dobrogea platform was characterized by se directed extension compatible with the aptian cenomanian rifting of the western black sea followed by the se directed drifting of a part of the moesian block i e the istanbul block on its southern extremity the tornquist teisseyre line does not show evidence for any large scale alpine strike slip movements postulated by many the peceneaga camena fault being reactivated in latest cretaceous paleogene as a pure reverse fault during the late tertiary the carpathian compression was poorly transmitted to dobrogea extension dominated the neogene deformation which indicates a weak coupling between the carpathians and its foreland

architecture of the south eastern carpathians nappes and focsani basin romania from 2d ray tracing of densely spaced refraction data abstract a velocity model of the upper crust maximum depth 10 15 km of the earthquake prone vrancea area romania from 2d forward ray tracing of densely spaced refraction data is presented the model is derived from more than 11 000 travel times recorded at stations 100 m apart picked from 42 shot gathers along a 140 km line crossing the south eastern carpathian bending zone and the adjacent deep foreland focsani basin the model refines basement structure beneath the south eastern carpathian nappe stack and focsani basin and documents reverse faults on which crystalline rocks or highly metamorphosed mesozoic sedimentary cover of the crystalline basement have been elevated to depths as little as 3 5 4 km with a vertical displacement of at least 2 2 5 km beneath the external carpathian nappes in the vrancea zone fault systems flower structures and normal faults associated with the overall tectonic subsidence of the foreland basin are also inferred some of the basement fault systems appear to be recently active since they involve overlying young tertiary quaternary sedimentary layers and may be associated with intracrustal earthquakes recorded in the area

fluvial fan deltas linking channel processes with large scale morphodynamics 1 alluvial fan deltas are built by aggrading and avulsing river channels a numerical model of flow and sediment transport in channels is combined with a condition for channel avulsion to describe evolution of the fan surface the model combines elements of two recent approaches 1 diffusional models of depositional basin filling which describe the evolution of overall morphology and 2 cellular models of channel evolution which provide simplified descriptions of channel dynamics here the cellular formulation is used simply as a template for discretizing a standard set of equations describing flow and sediment transport within channels the basic formulation is thus grid invariant and the results are in actual rather than arbitrary time and length scales the model captures the interaction between microscale channel morphodynamics including converging and diverging flow and avulsion and morphodynamics at the macroscale fan it provides a starting point for the study of a wide range of topics including the three dimensional stratigraphy of fan delta deposits and the response of fan deltas to engineering activities

preferred directions of flow on alluvial fans in this paper modifications of the method used to delineate flood plains on active alluvial fans for the national flood insurance program are suggested given new data regarding the deviations of channels from the medial radial line at the apex of the fan in the original methodology it was assumed that every point on an alluvial fan contour had an equal probability of being impacted during a flood event that is a uniform probability distribution was assumed data now available suggest that a normal distribution better describes the probability of points on an alluvial fan contour being hit during a flood event results from an example of the application of the modified methodology are compared with the results obtained using the original methodology

variscan tectonics in the holy cross mountains poland and the role of structural inheritance during alpine tectonics abstract the present study was carried out in the holy cross mountains hcm of south central poland and includes computation of palaeostresses following angelier s method and field structural analysis the palaeozoic basement of the hcm comprises two tectonic units separated by the major wnw ese striking holy cross fault hcf fold analysis indicates a n s to nne ssw direction of variscan shortening micro structures and fold analysis from upper devonian rocks further reveal 1 a brittle tectonic event due to a nw se compression preceding folding that could be related to pre late carboniferous tectonics due to block transport within the tornquist teisseyre zone ttz and 2 polyphase variscan folding comprising a an early stage of n s shortening marked by north verging ramps b a main folding event and axial cleavage formation involving n s to nne ssw shortening and c a late stage of shortening deforming older folds and cleavage a mainly extensional tectonic regime dominated from the permian until the cretaceous during which time the hcf was reactivated as a normal fault large nw se faults bordering the mid polish trough mpt developed subsequent tectonic inversion of the mpt resulted in basin uplift mid polish swell mps palaeostress computations from mesozoic strata suggest a ne sw direction for the main maastrichtian paleocene shortening phase in addition to two minor brittle events resulting from n s and e w compression analysis of local folds in the mesozoic cover indicates a causal relationship with the maastrichtian paleocene reactivation of older faults in particular en echelon folds in the radomsko elevation suggest a sinistral reactivation of the palaeozoic hcf folds in the southwestern part of the hcm argue for reactivation in the reverse mode of a nw se trending fault bordering the mps that originated in the mesozoic in palaeozoic strata post variscan brittle deformation and micro fault reactivation are attributed to the tectonic events of maastrichtian paleocene age reactivation of n s fractures is demonstrated in the rzepka quarry where fractures in devonian dolomites are filled by calcite probably formed during a late variscan event and by younger late permian early triassic sediments they were subsequently reactivated as dextral strike slip faults during the ne sw maastrichtian paleocene compression

continental rift development in precambrian and phanerozoic europe europrobe and the dnieper donets rift and polish trough basins abstract upper crustal structure and lower crustal and mantle character of the european continental lithosphere differ significantly from west to east the processes of rifting of phanerozoic western europe s hotter thinner crust compared with the more stable thicker 45 vs 30 km proterozoic crust of the east european craton is being investigated by europrobe case studies of western and eastern european sedimentary basins the dnieper donets basin transects the southwestern part of the east european platform in a nw se direction lying between the ukrainian shield and the voronezh massif rifting took place from early frasnian until perhaps the late visean and was accompanied by major volcanic activity the distribution of both was affected by pre existing basement fault systems the syn and post rift sedimentary succession may be as thick as 20 km in the donets trough basin evolution and the present crustal geometry have been much affected by inversion during the permian in association with uralian orogenesis tectonic events of bathonian oxfordian 168 154 ma and turonian santonian 91 84 ma age are also recorded in the basin stratigraphy the polish trough lies along the boundary between the phanerozoic and proterozoic european crustal domains coincident with the trans european suture zone the presence of this rheological boundary may be paramount in structurally controlling the position of the trough tectonic subsidence analysis indicates an initial late rotliegendes early triassic syn rift phase of development subsequently episodes of increased tectonic subsidence rate occurred during the oxfordian tithonian 157 146 ma and beginning in the cenomanian 95 90 ma the oxfordian tithonian episode is likely the signature of a second extensional event correlated with intensification of rifting within the arctic north atlantic rift system while the cenomanian and later is a precursor to mild compressional intraplate orogenic movements present day crustal structure reflects the docking of phanerozoic crust against the proterozoic during palaeozoic orogenies permo carboniferous wrenching and transtensional modifications leading to formation of the polish trough as well as modifications during the late cretaceous early tertiary inversion process

the shutdown of an anoxic giant magnetostratigraphic dating of the end of the maikop sea abstract paratethys the lost sea of central eurasia was an anoxic giant during oligocene early miocene maikop series times with a size matching the modern day mediterranean sea and a history of anoxic conditions that lasted for over 20 myrs the eastern part of this realm black sea caspian sea domain holds key records for understanding the build up maintenance and collapse of anoxia in marginal seas here we show that the collapse of anoxic maikop conditions was caused by middle miocene paleogeographic changes in the paratethys gateway configuration when a mid langhian badenian tarkhanian transgression flooded and oxygenated the eastern paratethys we present an integrated magneto biostratigraphic framework for the early middle miocene tarkhanian chokrakian karaganian regional stages of the eastern paratethys and date the lithological transition from anoxic black shales of the maikop series to fossiliferous marine marls and limestones of the regional tarkhanian stage for this purpose we selected two long and time equivalent sedimentary successions exposed along the belaya and the pshekha rivers in the maikop type area in ciscaucasia southern russia we show that a significant but short marine incursion took place during the tarkhanian ending the long lasting maikop anoxia of the basin our magnetostratigraphic results reveal coherent polarity patterns which allow a straightforward correlation with the time interval 15 12 ma of the geomagnetic polarity time scale the tarkhanian flooding occurred during a relatively short normal polarity interval that correlates with c5bn resulting in an age of 14 85 ma the regional tarkhanian chokrakian stage boundary is located within c5adn at an age of 14 75 ma and the chokrakian karaganian boundary is tentatively correlated with c5acn and an age of 13 9 13 8 ma our new tarkhanian flooding age reveals a paleogeographic scenario that is different from many previous reconstructions instead of envisaging marine connections to the indian ocean we show that major changes in connectivity between the eastern and central paratethys seas have caused the influx of marine waters during the tarkhanian an increase in marine connectivity with the mediterranean during a short episode of rapid sea level rise triggered mixing and ended the widespread anoxia in the eastern paratethys the mixing episode was short lived 100 kyr as the sea level rise slowed down and connectivity degraded because of tectonic uplift in the gateway area

post cretaceous to recent stress fields in the se moesian platform bulgaria abstract the reconstruction of the stress fields in the se moesian platform in bulgaria has been made by means of earthquake fault plane solutions tectonic fracture and fold patterns and physical electrical anisotropy in rocks restricted stratigraphically from the early cretaceous up to the late pliocene the philosophy of the study is that the recognition of the older stress fields for a given area can be successful if the characteristics of the youngest ones are known the contemporary stress field is discussed using the fault plane solutions from earthquakes and the kinematics of the activated faults the reconstruction of the post pliocene paleo stress field was made by studies of conjugate shear joints systems in upper pliocene limestones measurements of elements of tectonic fractures were also performed in situ on more than 60 outcrops of rocks aged from aptian to pliocene a limited number of sites were studied for electrical anisotropy using the azimuthal vertical electrical sounding method a more complete study of the tectonic meso and micro structures has been performed on the sarmatian sediments in the se moesian platform this study includes a description of the discovered folds brittle tectonic analysis and reconstruction of the post sarmatian paleo stress field as a result it was deduced that the compression after the early cretaceous period is ne sw directed the direction of compression since sarmatian to early quaternary was nw se a clockwise rotation of the main stress axes was established for a number of sites the contemporary contraction is directed also nw se according to the fault plane solutions determined for crustal earthquakes in the region this result is tested using the data from the gps measurement recently performed in this part of the balkan peninsula it could be suggested that there has been a clockwise rotation of the stress field due to the evolution of curved fold thrust belt in the south eastern carpathians and the collision of the balkanides with the moesian platform

far field strain transmission and contractional step overs abstract in contractional subduction collisional settings convergence is accommodated by the formation of thin and thick skinned thrust and fold belts the transmission of such deformation over larger distances into orogenic foreland areas is influenced by the inherited rheological characteristics of continental lithosphere lateral rheological variations parallel to the strike of continental foreland areas creates contrasting geometries and sequences of deformation that interact during orogenic build up we investigate the far field transmission of strain within a continental lithosphere characterized by a laterally variable rheology through physical analogue modelling rheological weak crustal zones were introduced at distance from an advancing backstop to study the progressive along strike linkage and interference of structures during contraction the results reveal that rheologically weak crustal zones localise far field contractional deformation when the size of weak zones by means of their horizontal extend to depth ratio is large deformation localises at the boundaries of the weak zone where they lead to the formation of large offset faults subsequently the faults migrate along strike into areas that are rheologically stronger when the size of the weak zone is reduced a large scale contractional step over forms in orogenic forelands where rheologically contrasting domains transmit out of sequence deformation by a gradual migration of thrust offsets and fold amplitudes along their strike these results show that crustal scale orogenic step overs do not always reflect variations in the geometry of the plate boundary indenter or along strike gradients in shortening rates such features may also form in response to variations in rheology as the ones created by inherited extensional basins situated at large distances from plate boundaries in the orogenic foreland

correction of in situ cosmogenic nuclide production rates for geomagnetic field intensity variations during the past 800 000 years we present integrated relative production rates for cosmogenic nuclides in rock surfaces which take into account reported variations of the geomagnetic field intensity during the past 800 000 yr the calculations are based on the model simulating cosmic ray particle interactions with the earth s atmosphere given by masarik and beer simulation of particle fluxes and cosmogenic nuclide production in the earth s atmosphere j geophys res 104 d10 12099 12111 1999 corrections are nearly independent on altitude between sea level and at least 5000 m the correction factors are essentially identical for all stable and radioactive cosmogenic nuclides with half lives longer than a few hundred thousand years at the equator integrated production rates for exposure ages between 40 000 to 800 000 yr are 10 to 12 higher than the present day values whereas at latitudes 40 geomagnetic field intensity variations have hardly influenced in situ cosmogenic nuclide production correction factors for in situ 14c production rates differ from those of longer lived nuclides they are always smaller than 2 because the magnetic field intensity remained rather constant during the past 10 kyr when the major fraction of the 14c extant today was produced

a regional 8200 cal yr bp cooling event in northwest europe induced by final stages of the laurentide ice sheet deglaciation the most notable change in 18o in greenland ice cores during the holocene occurs at 8200 cal yr bp here we present a new high resolution marine record from the northern north sea along with tree ring data from germany which contain evidence of a pronounced temperature drop 2 c contemporaneous with that of the greenland ice core records the synchronous timing of the cooling event in the greenland ice cores marine record and tree ring data from northwest europe reflects a regional influence on the north atlantic ocean atmospheric system suggesting a prominent role of the north atlantic thermohaline circulation the operation of the north atlantic ocean circulation is sensitive to variation in the freshwater budget implying that any change in freshwater flux is capable of altering the north atlantic circulation system we hypothesise minor but long term freshwater fluxes in the final stages of the deglaciation of the laurentide ice sheet as a forcing mechanism 1998 john wiley sons ltd

a reassessment of post depositional remanent magnetism preliminary experiments with natural sediments abstract realignment of magnetic grains below the sediment water interface is thought to impart a post depositional remanent magnetization pdrm however there is little convincing evidence in the published literature that pdrm is the dominant mechanism by which sediments become magnetized we report here preliminary results from two kinds of laboratory experiments designed to investigate whether post depositional reorientation of magnetic particles is likely to occur in nature in the first experiment we monitored changes in the magnetization of natural sediments in response to changing laboratory fields our results are inconsistent with post depositional reorientation of magnetic particles in a second experiment we put live worms in a multi core tube with the original sediment water interface intact remagnetization was only observed in samples taken from a mound of fecal pellets formed at the surface these pellets had been suspended by a worm and redeposited in the laboratory field the other samples which were not resuspended but nonetheless bioturbated by the worms showed no change in magnetization our preliminary results do not support the hypothesis that post depositional reorientation occurs in natural undisturbed sediments below the sediment water interface

the geological history of the istria depression romanian black sea shelf tectonic controls on second third order sequence architecture the istria depression or sub basin of offshore romania lies at the intersection of the trans european tornquist teisseyre zone and the black sea back arc basin just outboard of the east carpathian orogenic welt its late mesozoic cenozoic succession records an extraordinary cpolyphase history of subsidence and sedimentation interrupted by several quite spectacular 2nd 3rd order erosional unconformities reflecting the interplay between these teetonic domains the unconformities divide the succession into a number of stratigraphic sequences the sub basin first developed as a transtensional rift in the triassic early jurassic evolving into a narrow oceanized trough in later jurassic this was tilted west during the early cretaceous by uplift and rifting in the western black sea and the residual late jurassic topography was filled and buried by a west facing clastic evaporite wedge late aptian albian post rift subsidence and spreading in the western black sea imposed a strong easterly tilt encouraging the partial evacuation of its early cretaceous sedimentary fill by gravity driven mass wastage the incised valley topography was subsequently buried in the later cretaceous and early cenozoic during the mid late cenozoic the black sea basin experienced intermittent periods of partial to complete isolation from the world ocean and significant base level drawdown the first major sea level fall occurred in the eocene when the istria depression was deeply incised to be healed by oligocene shales during the subsequent rise yet another period of drawdown and exposure occurred in mid miocene with extensive shelf margin mass wastage and erosion followed by reflooding and deposition of a transgressive backstepping sequence in mid late miocene messinian drawdown in the mediterranean caused a further period of isolation and falling base level the shelf margin was again exposed and experienced widespread mass wastage and slumping a marine connection was re established in late messinian rising sea level eroded the earlier slumped sequence and the margin was healed by a lowstand prograding wedge in late miocene early pliocene this was followed by shelf sedimentation in the plio pleistocene periodically interrupted by canyon incision events testifying to continued climatically or tectonically imposed base level fluctuations several direct and indirect tectonic factors were responsible for valley canyon incision within the istria depression and erosion of the romanian black sea shelf margin these include 1 the local structural framework 2 direct tectonic uplift and tilting and 3 more indirect tectonically imposed isolation encouraging significant base level falls

rapid early holocene environmental changes in northern sweden based on studies of two varved lake sediment sequences mineral magnetic organic carbon and pollen studies of two varved holocene lake sediment sequences in the boreal forest of northern sweden indicate that significant environmental changes took place between c 6000 and 5700 bc this interval is characterized by an increase in mineral matter accumulation which is a proxy for winter snow accumulation and a statistically significant decrease in total pollen influx predominantly pinus betula and alnus which may reflect lower spring and summer temperatures and increased frost frequency notable increases in the influx of deciduous tree species including quercus and corylus suggest a rapid change to warmer conditions between 5700 and 5600 bc given dating errors associated with the varve chronologies and the greenland ice core timescales the cold interval can be considered to reflect a regional possibly global climatic cooling which is often referred to as the 8 2 kyr bp cooling event however the younger age of the cold event in northern sweden does not support the hypothesis of forcing by the sudden drainage of laurentide glacial lakes into the north atlantic unless a minimal 300 year delay in ocean atmospheric coupling is accepted the data contribute to a complex picture of early holocene environmental change in response to deglaciation of the northern hemisphere

strain indicators and magnetic fabric in intraplate fault zones case study of daroca thrust iberian chain spain abstract anisotropy of magnetic susceptibility ams has been applied to the study of shallow fault zones although interpretation of the results requires establishing clear relationships between petrofabric and magnetic features magnetic behaviour of fault rocks and an extensive knowledge of p t conditions in this work we demonstrate that magnetic methods can be applied to the study of heterogeneous fault zones provided that a series of requisites are met a major fault zone within the iberian plate daroca thrust showing transpressional movements during cenozoic time was chosen for this purpose because of the exceptional outcrops of fault gouge and microbreccia and its relevance within the context of the northeastern iberian plate magnetic fabrics were analysed and the results were compared with foliation and s c structures measured within the fault zone clay mineral assemblages suggest maximum burial depths shallower than 2 km

tectonic evolution of the mid polish trough modelling implications and significance for central european geology abstract the polish basin forms the easternmost part of the permian mesozoic northwest european basin the depocentral axis of the polish basin the mid polish trough mpt is superimposed on the boundary between the west european phanerozoic and east european proterozoic crustal domains within the trans european suture zone the presence of this fundamental crustal boundary may be paramount in structurally controlling the position of the mpt concentrating stresses during post variscan wrench and extensional tectonics in central europe tectonic subsidence analysis of the preserved and reconstructed stratigraphic record of the polish basin indicates the occurrence of an initial late permian early triassic 255 241 ma rifting phase that was followed by subsequent episodes of increased tectonic subsidence during the oxfordian kimmeridgian 157 152 ma and beginning in the cenomanian 97 ma the oxfordian kimmeridgian episode is interpreted as corresponding to a second extensional event which correlated with intersified rifting and wrench activity within the arctic north atlantic rift system and along the northern tethyan margin while the cenomanian may be considered a precursor of compressional deformations in the basin which culminated in basin inversion in the latest cretaceous and paleocene forward modelling results in view of existing geophysical interpretations which show the presence of a deep moho and a very velocity lower crustal layer beneath thempt suggest that permo mesozoic basic development may be related at least in part to the intrusion of mantle material into and densification of the lower crust rather than exclusively to crustal extension and thinning

transfer of deformation in back arc basins with a laterally variable rheology constraints from analogue modelling of the balkanides western black sea inversion the balance between extension and contraction in back arc basins is very sensitive to a number of parameters related to on going subduction and collision processes this leads to complex back arc geometries where a lateral transition between crustal blocks with contrasting rheologies is often recorded one good example is the back arc region of the balkanides pontides orogens where lateral variations in rheologies are observed between the balkanides moesian block and the pontides western black sea basin the latter opened during cretaceous eocene and has been inverted together with the former starting during late middle eocene the inversion generated contrasting geometries along the orogenic strike with a narrow zone of high deformation in the balkanides moesia region wide areas of thrusting with low offsets in the pontides western black sea basin and a transitional zone characterized by highly curved geometries this overall type of inversion is investigated here by the means of analogue modelling testing the role of inherited crustal geometries during inversion our modelling suggests that the contrasting architecture of inverted structures observed in the balkanides pontides domain are the result of pre existing crustal stretching geometries of various blocks inherited from the cretaceous eocene extension the stretched and weak back arc basins can transfer contraction deformation at large distances explaining structures derived by observational studies the collisional deformation recorded in the pontides was transmitted at large distances that are in the range of the contraction structures observed in the centre and northern part of the western black sea in the light of analogue modelling results we argue that the western black sea was a rheologically weaker domain when compared with the adjacent western onshore at the beginning of the inversion in contrast with previous results derived from numerical modelling studies that argued for a strong west black sea domain at the beginning of inversion

late palaeozoic to triassic evolution of the turan and scythian platforms the pre history of the palaeo tethyan closure abstract a number of en echelon arranged southwest facing arc fragments of palaeozoic to jurassic ages sandwiched between two fairly straight east northeast trending boundaries constitute the basement of the scythian and the turan platforms located between the laurasian and tethyside units they have until now largely escaped detection owing to extensive jurassic and younger cover and the inaccessibility of the subsurface data to the international geological community these units are separated from one another by linear gently curved faults of great length and steep dip those that are exposed show evidence of strike slip motion the arc units originally constituted parts of a single silk road arc located somewhere south of the present day central asia for much of the palaeozoic although by the late carboniferous they had been united into a continental margin arc south of the tarim basin and equivalent units to the west and east they were stacked into their present places in northern afghanistan turkmenistan caucasus and the northern black sea by large scale right lateral strike slip coastwise transport along arc slicing and arc shaving strike slip faults in the triassic and medial jurassic simultaneously with the subductive elimination of palaeo tethys this gigantic dextral zone the silk road transpression was a trans eurasian structure and was active simultaneously with another similar system the gornostaev keirogen and greatly distorted eurasia the late palaeozoic to jurassic internal deformation of the dniepr donets aulacogen was also a part of the dextral strain in southern europe when the emplacement of the scythian and turan units was completed the elimination of palaeo tethys had also ended and neo tethyan arcs were constructed atop their ruins mostly across their southern parts the western end of the great dextral zone that emplaced the turan and scythian units horsetails just east of north dobrudja and a small component goes along the tornquist teisseyre lineament

geomagnetic field variations in northern sweden during the holocene quantified from varved lake sediments and their implications for cosmogenic nuclide production rates palaeomagnetic analyses were conducted on two varved lake sediment sequences in northern sweden the magnetic properties of the sediment sequences are dominated by stable single domain magnetite with characteristics typical of bacterial magnetosomes alternating field demagnetization measurements indicate that the single domain magnetite is the dominant carrier of a stable natural remanent magnetization temporal variations in inclination and declination were obtained from a total of four cores and the data points were stacked according to their independent calendar year varve ages statistically significant patterns in inclination and declination form a regional palaeomagnetic secular variation psv curve which possesses features that are identical in form to the uk holocene psv master curve however the calibrated radiocarbon ages of uk features identified prior to 1500 bc are approximately 500 years older than their swedish varve dated equivalents which points to dating errors and or drifting of the geomagnetic field the sediments meet the uniformity criteria proposed for palaeointensity reconstruction and estimates of relative geomagnetic field intensity are calibrated against global dipole moment compilations a calculated nuclide production curve is derived from the reconstructed geomagnetic field intensity which empirically demonstrates the dominant modulation of cosmogenic nuclide production by dipole moment between 5000 bc and ad 1500

modelling alluvial fan morphology a mathematical model which estimates the scale independent sediment surface profile of alluvial fans has been developed this model utilizes a diffusive sediment transport model and an unsteady radial flow conservation relationship these equations are approximately solved assuming a quasi steady state closure with appropriate modelling assumptions for two end member fan types 1 fans where most of the fan surface is depositionally active denoted here as homogeneous and 2 fans characterized by channelling and sediment sorting processes the fundamental result for these two fan types is a dimensionless sediment profile relationship which approximates most fan surfaces the model suggests that the overall dimensionless morphology of alluvial fans is governed more by fundamental diffusion principles in sediment deposition than by individual environmental or basin characteristics additionally this work potentially can be extended to model temporal variation in fan development preliminary comparison with alluvial fan profiles is reasonable indicating that this model provides useful qualitative and quantitative information relating to alluvial fan process and morphology copyright 1999 john wiley sons ltd

map view restoration of aegean west anatolian accretion and extension since the eocene 1 the aegean region greece western turkey is one of the best studied continental extensional provinces here we provide the first detailed kinematic restoration of the aegean region since 35 ma the region consists of stacked upper crustal slices nappes that reflect a complex paleogeography these were decoupled from the subducting african adriatic lithospheric slab especially since 25 ma extensional detachments cut the nappe stack and exhumed its metamorphosed portions in metamorphic core complexes we reconstruct up to 400 km of trench perpendicular ne sw extension in two stages from 25 to 15 ma the aegean forearc rotated clockwise relative to the moesian platform around euler poles in northern greece accommodated by extensional detachments in the north and an inferred transfer fault se of the menderes massif the majority of extension occurred after 15 ma up to 290 km by opposite rotations of the western and eastern parts of the region simultaneously the aegean region underwent up to 650 km of post 25 ma trench parallel extension leading to dramatic crustal thinning on crete we restore a detachment configuration with the mid cycladic lineament representing a detachment that accommodated trench parallel extension in the central aegean region finally we demonstrate that the sakarya zone and cretaceous ophiolites of turkey cannot be traced far into the aegean region and are likely bounded by a pre 35 ma n s fault zone this fault became reactivated since 25 ma as an extensional detachment located west of lesbos island the paleogeographic units south of the izmir ankara sava suture however can be correlated from greece to turkey

seasonal interannual and mesoscale variability of the black sea upper layer circulation derived from altimeter data 1 topex poseidon and ers altimeter data comprising the period from may 1992 to may 1999 are assimilated into a shallow water model for providing a dynamically consistent interpretation of the sea surface height variations and estimation of the temporal and spatial characteristics of the upper layer circulation in the black sea these 7 year long observations offer a new capability for interpretation of major transient and quasi permanent features of the upper layer circulation the instantaneous flow fields involve a complex eddy dominated system with different types of structural organizations in which the eddies and the gyres of the interior cyclonic cell interact continuously among themselves and with meanders and filaments of the rim current the circulation possesses a distinct seasonal cycle whose major characteristic features repeat every year with some year to year variability an organized two gyre winter circulation system disintegrates gradually into a series of interconnecting eddies in the summer and autumn months which are also characterized by more pronounced and complex mesoscale activity in the peripheral flow system our analyses suggest a revised schematic circulation picture of the major quasi permanent and recurrent elements of the black sea

tectonic units of the alpine collision zone between eastern alps and western turkey abstract we present a map that correlates tectonic units between alps and western turkey accompanied by a text providing access to literature data explaining the concepts used for defining the mapped tectonic units and first order paleogeographic inferences along strike similarities and differences of the alpine eastern mediterranean orogenic system are discussed the map allows 1 for superimposing additional information such as e g post tectonic sedimentary basins manifestations of magmatic activity onto a coherent tectonic framework and 2 for outlining the major features of the alpine eastern mediterranean orogen dinarides hellenides anatolides and taurides are orogens of opposite subduction polarity and direction of major transport with respect to alps and carpathians and polarity switches across the mid hungarian fault zone the dinarides hellenides taurides and apennines consist of nappes detached from the greater adriatic continental margin during cretaceous and cenozoic orogeny internal units form composite nappes that passively carry ophiolites obducted in the latest jurassic earliest cretaceous or during the late cretaceous on top of the greater adriatic margin successions the ophiolites on top of composite nappes do not represent oceanic sutures zones but root in the suture zones of neotethys that formed after obduction suturing between greater adria and the northern and eastern neotethys margin occupied by the tisza and dacia mega units and the pontides occurred in the latest cretaceous along the sava izmir ankara erzincan suture zones the rhodopian orogen is interpreted as a deep crustal nappe stack formed in tandem with the carpatho balkanides fold thrust belt now exposed in a giant core complex exhumed in late eocene to miocene times from below the carpatho balkan orogen and the circum rhodope unit its tectonic position is similar to that of the sakarya unit of the pontides we infer that the rhodope nappe stack formed due to north directed thrusting both rhodopes and pontides are suspected to preserve the westernmost relics of the suture zone of paleotethys

new data on the vrancea nappe moldavidian basin outer carpathian domain romania paleogeographic and geodynamic reconstructions a study has been performed on the cretaceous to early miocene succession of the vrancea nappe outer carpathians romania based on field reconstruction of the stratigraphic record mineralogical petrographic and geochemical analyses extra basinal clastic supply and intra basinal autochthonous deposits have been differentiated appearing laterally inter fingered and or interbedded the main clastic petrofacies consist of calcarenites sub litharenites quartzarenites sub arkoses and polygenic conglomerates derived from extra basinal margins an alternate internal and external provenance of the different supplies is the result of the paleogeographic re organization of the basin margins system due to tectonic activation and exhumation of rising areas the intra basinal deposits consist of black shales and siliceous sediments silexites and cherty beds evidencing major environmental changes in the moldavidian basin organic matter rich black shales were deposited during anoxic episodes related to sediment starvation and high nutrient influx due to paleogeographic isolation of the basin caused by plate drifting the black shales display relatively high contents in sub mature to mature type ii lipidic organic matter good oil and gas prone source rocks constituting a potentially active petroleum system the intra basinal siliceous sediments are related to oxic pelagic or hemipelagic environments under tectonic quiescence conditions although its increase in the oligocene part of the succession can be correlated with volcanic supplies the integration of all the data in the progressive reorientation of convergence direction carpathian model and their consideration in the framework of a foreland basin led to propose some constrains on the paleogeographic geodynamic evolutionary model of the moldavidian basin from the late cretaceous to the burdigalian

gis analysis of depositional slope change at alluvial fan toes in japan and the american southwest abstract slope change at alluvial fan toes provides a clue to understanding differences between alluvial fans and other depositional landforms this paper analyses topographic data for 430 alluvial fans and their adjacent lowlands in japan and the american southwest asw typical humid and arid regions with abundant alluvial fans arcs showing fan toes were identified and representative areas above and below each arc were then delineated based on a gis buffer analysis the mean slope of the area above sa and below the fan toe sb and the ratio of sa to sb rs were computed overall fan slope so total fan length l and angle of the fan apex af were also measured relationships among these morphometric parameters reflect differences in climate and sedimentary processes fans in the asw tend to have straight profiles with similar values for sa and so indicating that fan gradients from deposition resulted from low frequency high magnitude storms have been preserved well under an arid climate higher rs values result from good preservation of both steep fan surfaces and gentle adjacent lowlands which is also ascribable to infrequent sediment redistribution in japan sa tends to be smaller than so and rs is often close to unity reflecting frequent sediment redistribution on fans and across fan toes under a humid climate rs in both the regions tends to converge into unity with increasing l longer alluvial fans are more strongly dominated by fluvial processes than by mass flows especially at their toes longer fans also tend to have small af leading to fluvial processes similar to those on floodplains sediment re mobilisation at the toes of such fans is more frequent resulting in smaller differences between sa and sb

investigating the use of alluvial fan volume to represent fan size in morphometric studies studies of the morphometric properties of alluvial fans have predominantly used a two dimensional planimetric area to represent fan size even though fans are three dimensional sediment deposits but the validity of this substitution has been questioned volumes of fans in nonsubsiding settings were estimated with the objective of investigating the relationship between fan volume and fan area a simple geometric approach was developed so that volumes of noncoalescent fans could be estimated with measurements from topographic maps data were collected from two study areas with humid temperate climates the bow valley in alberta canada and the absaroka range in wyoming usa because these landscapes were glaciated the fans are of paraglacial origin and are not related to contemporaneous tectonic subsidence using functional relation analysis results indicate that the proportional power law relationship between fan volume and fan area is not significantly different from 1 1 in both study areas morphometric relationships between fans and drainage basins are also examined with fan volume and cumulative sediment yield employed as variables

kinematics of back arc inversion of the western black sea basin 1 back arc basin evolution is driven by processes active at the main subduction zone typically assuming the transition from an extensional back arc during the retreat of a mature slab to a contractional basin during high strain collisional processes such a transition is observed in the black sea where the accurate quantification of shortening effects is hampered by the kinematically unclear geometries of cenozoic inversion by means of seismic profiles interpretation quantified deformation features and associated syn tectonic geometries on the romanian offshore this study demonstrates that uplifted areas observed by exploration studies form a coherent thick skinned thrust system with n ward vergence thrusting inverted an existing geometry made up by successive grabens that were inherited from the cretaceous extensional evolution the shortening started during late eocene times and gradually affected all areas of the western black sea basin during oligocene and miocene times deformation being coherently correlated across its western margin the mechanism of this generalized inversion is the transmission of stresses during the collision recorded in the pontides balkanides system syn tectonic sedimentation in the western black sea demonstrates that this process was continuous and took place through the onset of gradual shortening migrating northward although the total amount of shortening is roughly constant in an e w direction individual thrusts have variable offsets deformation being transferred between structures located at distance across the strike of the system the black sea example demonstrates that the vergence and offset of thrusts can change rapidly along the strike of such a compressional back arc system this generates apparently contrasting geometries that accommodate the same orogenic shortening

comment on near surface location geometry and velocities of the santa monica fault zone los angeles california by r d catchings g gandhok m r goldman d okaya m j rymer and g w bawden catchings et al 2008 hereafter referred to as catchings et al effectively duplicated our acquisition of a high resolution seismic reflection profile across a fault scarp near the tip of the santa monica fault one of the major faults in the northern los angeles basin the profiles crossed a distinct topographic scarp which is one of a series of scarps that indicate the fault extends about 11 km across the northern los angeles basin before continuing undersea to the west dolan et al 2000 based primarily on the seismic reflection and refraction data catchings et al argued that there are two active fault strands in the near surface 100 m depth in contrast to the single fault that we interpreted from a combination of seismic reflection geomorphologic and trench data at the same site dolan and pratt 1997 pratt et al 1998 dolan et al 2000 acceptance of the interpretation of catchings et al would significantly change seismic hazard assessments in the west los angeles santa monica area in two ways first the addition of a second shallow active fault strand about 200 m south of the known fault scarp and a zone of rotated strata between the two strands as proposed by catchings et al would widen by 200 m the zone of active faulting and surface deformation inferred in our earlier studies although catchings et al figs 5 and 9 show fault b to reach the surface about 140 m south of the scarp and their fig 10 shows it to be about 100 m south of the scarp if this same geometry were assumed along the portion of the topographic scarps for which it has not been documented the additional zone of inferred active faulting would encompass a substantial area in this densely urbanized corridor second catchings et al argue for a 20 dip for the shallowest 700 m length of

petroleum geology of the black sea abstract the black sea comprises two extensional basins formed in a back arc setting above the northward subducting tethys ocean close to the southern margin of eurasia the two basins coalesced late in their post rift phases in the pliocene forming the present single depocentre the western black sea was initiated in the aptian when a part of the moesian platform now the western pontides of turkey began to rift and move away to the south east the eastern black sea probably formed by separation of the mid black sea high from the shatsky ridge during the palaeocene to eocene subsequent to rifting the basins were the sites of mainly deep water deposition only during the late miocene was there a major sea level fall leading to the development of a relatively shallow lake most of the margins of the black sea have been extensively modified by late eocene to recent compression associated with closure of the tethys ocean gas chromatography mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the black sea can be explained by generation from an oil prone source rock of most probably late eocene age although a wider age range is possible in the basin centres burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post rift basin a palaeozoic source rock may have generated gas condensate in the gulf of odessa in bulgarian waters the main plays are associated with the development of an eocene foreland basin kamchia trough and in extensional structures related to western black sea rifting the latter continue into the romanian shelf where there is also potential in rollover anticlines due to gravity sliding of neogene sediments in the gulf of odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures small gas and oil discoveries around the sea of azov point to further potential offshore around the central azov high in offshore russia and georgia there are large culminations on the shatsky ridge but these are mainly in deep water and may have poor reservoirs there are small compressional structures off the northern turkish coast related to the pontide deformation these may include eocene turbidite reservoirs the extensional fault blocks of the andrusov ridge mid black sea high are seen as having the best potential for large hydrocarbon volumes but in 2200 m of water

deep seismic expression of an ancient plate boundary in europe seismological results on the structure of the upper mantle below europe reveal a marked contrast in seismic properties between precambrian and younger parts of europe the precambrian craton in eastern europe is characterized by high shear wave velocities which can be explained by low temperatures the transition to low seismic velocities below phanerozoic europe coincides with the crustal boundary zone of the craton and exists to depths of at least 140 kilometers despite the long and complex tectonic history of the plate boundary zone the transition is remarkably sharp which rules out any significant lateral transport of asthenospheric material across the suture zone

deep structure of the earth s crust in the contact zone of the palaeozoic and precambrian platforms in poland tornquist teisseyre zone abstract one of the major tectonic problems in europe concerns the southwest margin of the east european platform in the region of the so called polish danish trough in general this margin is assumed to be the tornquist teisseyre t t line running approximately from northwest to southeast in this part of europe determination of deep crustal structure of the contact zone between the precambrian platform and the palaeozoic platform was the main aim of the deep seismic sounding dss programme in poland in 1965 1982 deep seismic soundings of the earth s crust have been made in the t t line zone along nine profiles with a total length of about 2600 km the results of deep seismic soundings have shown that the crust in the marginal zone of the east european platform has highly anomalous properties the width of this zone ranges from 50 km in northwest poland to about 90 km in southeast poland the crustal thickness of the palaeozoic platform in poland is 30 35 km and of the precambrian platform 42 47 km while in the t t tectonic zone it varies from 50 to 55 km above the moho boundary in the t t zone at a depth of 40 45 km there is a seismic discontinuity with p wave velocities of 7 5 7 7 km s boundary velocities mean velocities and stratification of the earth s crust vary distinctly along the t t zone there are also observed high gravimetric and magnetic anomalies in the t t zone the t t tectonic zone determined in this manner is a deep tectonic trough with rift properties the deep fractures delineating the t t tectonic zone are of fundamental importance for the localization of the plate edge of the precambrian platform of eastern europe in the light of dss results the northeastern margin of the t t tectonic zone is a former plate boundary of the east european platform