sedimentary architecture and depositional controls of a pliocene river dominated delta in the semi isolated dacian basin black sea abstract sedimentological facies models for semi isolated basins are less well developed than those for marine environments but are critical for our understanding of both present day and ancient deltaic sediment records in restricted depositional environments this study considers an 835 m thick sedimentary succession of mid pliocene age which accumulated in the dacian basin a former embayment of the black sea detailed sedimentological and palaeontological analyses reveal a regression from distal prodelta deposits with brackish water faunas to delta top deposits with freshwater faunas sediments contain frequent hyperpycnal plumes and an enrichment in terrestrial organic material ichnofossils and in situ brackish and freshwater faunas deltaic progradation created thin sharply based sand bodies formed by multiple terminal distributary channels covering a wide depositional area the system experienced frequent delta lobe switching resulting in numerous thin parasequences parasequences are overlain by erosive reddish oxidized sand beds enriched in broken abraded brackish and freshwater shells these beds were formed after sediment starvation on top of abandoned delta lobes during each flooding event a robust magnetostratigraphic time frame allowed for comparison between the observed sedimentary cyclicity and the amplitude and frequency of astronomical forcing cycles our results indicate that parasequence frequencies are significantly higher than the number of time equivalent astronomical cycles this suggests that delta lobe switching was due to autogenic processes we consider the observed facies architecture typical for a delta prograding on a low gradient slope into a shallow brackish protected semi isolated basin furthermore in the absence of significant wave and tidal influence sediment progradation in such a protected depositional setting shaped a delta strongly river dominated

mio pliocene magnetostratigraphy in the southern carpathian foredeep and mediterranean paratethys correlations a full understanding of the mio pliocene palaeogeographical and palaeoenvironmental changes in the circum mediterranean region during the messinian salinity crisis msc is at present hampered by the lack of reliable chronostratigraphic correlations between the mediterranean and paratethys regions here we present magnetostratigraphic ages for the upper miocene to pliocene deposits of the southern carpathian foredeep in romania these ages are in good agreement with those recently obtained from the eastern carpathian foredeep and define a new chronology for the eastern paratethys the meotian pontian boundary is not biostratigraphically

error analysis for the determination of tectonic rotation from paleomagnetic data appendix b is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington d c 20009 document b83 001 2 50 payment must accompany order recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25 this has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence 95 an analytical calculation which is valid when error bars are small shows that the correct error bars are 75 to 80 of the values derived in previous studies i have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used the analytical approximation may be used whenever 95 is less than 10 and the mean inclination is not too close to vertical confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20 25 narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data

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

paleomagnetism of jurassic to miocene sediments from the apenninic carbonate platform southern apennines italy evidence for a 60 counterclockwise miocene rotation abstract the tectonic evolution of the apennine belt southern tyrrhenian sea system is addressed through a paleomagnetic study of lias to langhian sediments from the apenninic carbonate platform southern apennines italy reliable paleomagnetic data gathered from 21 sites document a regional scale post langhian 80 counterclockwise ccw rotation since previous studies of the plio pleistocene clays spread over the orogen had shown a 20 ccw rotation we conclude that the southern apennines rotated by 60 during middle late miocene our data provide evidence that the southeastward drift of calabrian block and synchronous spreading of the southern tyrrhenian sea induced saloon door like deformation of the southern apennines and sicily which underwent similar magnitude although opposite in sign orogenic rotations a paleomagnetically derived paleogeographic reconstruction shows that at 15 ma late langhian the alpine apennine belt collided with a nne oriented carbonate platform corridor surrounded by oceanic basins we speculate that both the end of the corsica sardinia rotation and the eastward jump of the locus of back arc extension from the liguro provencal to the tyrrhenian sea may have been consequences of this event

sulphide speciation in surface sediments of the lagoon of venice a geochemical and mineralogical study abstract three 1 m cores of recent sediments from the lagoon of venice were sampled to obtain the vertical distribution of fe zn cu pb and cd and to study authigenic iron sulphides from the geochemical and mineralogical viewpoints zn cu pb and cd occur in superficial sediments in concentrations many times higher than those of their natural background the existence of zn cd and cu pb couples were revealed by their very similar depth profiles the latter couple is also closely correlated with sulphide sulphur iron is characterized by quite a different behaviour showing a sharp increase at a depth of 35 cm from a geochemical viewpoint authigenic sulphides were distinguished into pyrite and acid volatile sulphides greigite and mackinawite their distribution is characterized by high concentrations of avs in the first 25 cm of sediments dramatically decreasing with depth pyrite present in lower amounts shows the opposite trend although in one core both species were present in comparable amounts mineralogical study of the heavy mineral fraction revealed that the iron sulphides are composed of pyrite organised both in the classic framboidal growth and in unordered micro crystal swarms and iron mixed sulphide aggregates with variable optical patterns and colloform botroidal or massive growth no heavy metals were detected in the crystalline lattice of the sulphides down to 25 cm all types of sulphides occur and with increasing depth pyrite clearly prevails this behaviour may have various causes e g chemico physical control by specific microniches temporal and spatial variations favouring the formation of different types evolution of iron mixed sulphides into more stable forms

strike slip duplexes abstract strike slip fault systems often contain zones of steep imbricate faults geometrically similar to imbricate fans and duplexes in dip slip thrust and normal fault systems they are evident in map view rather than in vertical sections examples of duplexes are cited from both active and ancient systems and from theoretical and physical models duplexes may form at bends on strike slip faults by a process kinematically analogous to the sequential imbrication of ramps on dip slip faults however some may form and many may initiate as non sequential riedel fractures at fault offsets or on straight fault segments this process is more marked than in dip slip systems where primary anisotropy such as bedding exerts more control on fault geometry strike slip duplexes may be shunted along the fault system parallel to the regional slip vector however duplexes or individual horses will usually also move up or down perpendicular to the slip vector because of the unconstrained upper surface to the fault system these factors mean that no section through a strike slip system should be expected to area balance the faults of strike slip duplexes and imbricate fans may root in kinematically necessary low dip faults or may converge downwards and appear in vertical sections as flower structures

timing of rotational motion of apuseni mountains romania paleomagnetic data from tertiary magmatic rocks paleomagnetic results are reported from 8 sites in eocene to oligocene magmatic rocks and 27 sites in middle miocene to upper miocene volcanic rocks of the apuseni mountains following af demagnetization 29 sites were selected for tectonic interpretation these results together with previously published data imply a northward displacement of the area studied between the late cretaceous and oligocene followed by a large clockwise rotation prior to the middle miocene after which no significant movement has occurred these results agree with other data from the carpatho pannonian domain showing a period of great mobility during the early miocene

putative greigite magnetofossils from the pliocene epoch greigite crystals of bacterial origin are widespread in modern sedimentary environments but their occurrence in the fossil record remains controversial grains from romanian pliocene aged sediments have now been identified as bacterial in origin tentatively placing them among the oldest known greigite magnetofossils

evolution of the sibisel shear zone south carpathians a study of its type locality near răsinari romania and tectonic implications romanian executive agency for higher education research development and innovation pn ii id pce 2011 3 0217 pn ii id pce 2011 3 0030

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

towards an astrochronological framework for the eastern paratethys mio pliocene sedimentary sequences of the focsani basin romania abstract a reliable geological timescale for the neogene sedimentary deposits of the romanian carpathian foredeep did not exist so far due to the lack of accurate isotopic datings and straightforward magnetostratigraphic correlations here we present a new chronology for the upper miocene to pliocene deposits of the westernmost part of the eastern paratethys based on high resolution magnetostratigraphic data from the focsani basin the thick and continuous river sections of putna 2 35 km and rimnicu s rat 7 32 km yield excellent magnetostratigraphic results and allow an unambiguous correlation to the polarity timescale for the interval between 7 and 2 5 ma the new age control permits the calculation of accumulation rates for each polarity zone which shows a significant increase at approximately 5 8 6 my the upper miocene to pliocene sedimentary rocks of the focsani basin display cyclic alternations of sandy units and finer intervals the calculated values for the average duration of the observed sedimentary cycles are very close to the average duration of precession 21 7 ky which indicates that the sedimentary cycles from the eastern carpathian foredeep deposits are astronomically forced we show that the usage of the unambiguous time control offered by magnetic polarity stratigraphy would give a more realistic picture of the processes that have taken place in this tectonically active region

tertiary tectonic and sedimentological evolution of the south carpathians foredeep tectonic vs eustatic control abstract a detailed seismic sequence stratigraphy study based on a dense network of seismic profiles is integrated with structural observations from interpreted geological sections to derive a tectonic and sedimentological model for the miocene pliocene evolution of the south carpathians foredeep getic depression following paleogene and older orogenic phases the first tectonic event which affected the studied area was characterised by early miocene large scale extension to transtension which is responsible for the opening of the getic depression as a dextral pull apart basin further middle miocene contraction caused wnw ese oriented thrusts and associated piggy back basins the last tectonic episode recognised in the studied area relates to general transpressive deformations during the late miocene early pliocene interval a first nw se oriented dextral episode is followed by second n s sinistral deformations the detailed sequence stratigraphy study allows for the definition of the dominant tectonic control of the sedimentary sequences in foreland basins a eustatic control may be associated but has a clear subordinated character

on late oligocene to pliocene depocentre migrations and the evolution of the carpathian pannonian system abstract the late oligocene to pliocene evolution of foredeep basins of the eastern alps carpathians fold and thrust belt is marked by pronounced internal to external and lateral depocentre shifts the latter shifts covering a present along arc distance of 1700 km portray accelerating rates of foredeep depocentre migration particularly so in the late early and in the middle miocene from about 7 to about 45 cm yr lateral depocentre migration came to a close at the beginning of the late miocene the subsequent late miocene to pliocene foredeep infill history was characterized by exponentially increasing accumulation rates in the intersection area of the east european ukrainian and moesian platforms successive steps in the evolution of the foredeep basins had pronounced counterparts in the intra carpathian area the beginning of acceleration of foredeep depocentre migration in latest early miocene times was coeval with the inception of intra carpathian extensional tectonics the extremely rapid middle miocene depocentre shift coupled with a change in direction of foredeep depocentre migration corresponded with maximum extension in the intra carpathian area the ensuing end of foredeep depocentre migration around the middle late miocene transition was coeval with the end of extension of the intra carpathian area which in turn was followed by the inception of overall thermal subsidence at about 11 5 ma the timing of and spatial relationships between discrete coeval events in arc and intra arc evolution put unambiguous geological constraints on geodynamic modelling of the evolution of the carpathian pannonian system it is speculated that the geological observations may best be understood in terms of the surficial effects of lateral migration of slab detachment such effects would mirror the dominant role of a concentrating slab pull taken to result in e g a time progressive acceleration of foredeep depocentre migration

structural applications and discussion of a paleomagnetic post paleozoic data base for the central mediterranean abstract a post paleozoic paleomagnetic data base has been compiled for the central mediterranean with the intention of listing directions at the highest possible level of data combination the value of the entries depends on the number and quality of data available the most reliable data are those based on regionally distributed localities and sites where the age is known to a stage and where tectonic correction has been made these represent a whole tectonic unit in a given period of time the lowest quality directions are those based on few samples and isolated in space and time in the tectonic interpretation of the listed data this variation in quality of data has been taken into consideration indications for cenozoic movements having a fundamental influence on the now observable distribution of the clockwise and counter clockwise rotated paleomagnetic directions were treated first and those for older movements afterwards microplate block and nappe movements were considered as possible mechanisms for the rotation of these the last two mechanisms explained satisfactorily the occasional local deviations from a general pattern other differences however such as those which exist between the northern calcareous alps or the tisza unit and the counter clockwise rotated superunit of the central mediterranean which are large and persisted through a longer period of time are best explained by independent movement of the whole unit

tertiary palaeomagnetic data for the carpatho pannonian region in the light of miocene rotation kinematics abstract the tectonic interpretation of the palaeomagnetic data for the neogene history of the carpatho pannonian region has usually been based on the palaeomagnetic data for the pre cenozoic complexes here a review of the tertiary palaeomagnetic data is given for the sites with two or more sets of data new site mean directions are calculated for most areas new area mean directions are given with a uniform criterion for the limitation of the normally distributed sub populations based on radiometric data some neogene volcanic sequences are subdivided into two complexes with separate area mean directions the possible influence of the areal tilts on the area mean palaeomagnetic directions is analysed and conclusions on the horizontal rotations are drawn the palaeomagnetic rotations are interpreted in the light of the author s kinematic model for the neogene history of the carpatho pannonian region the rotation of both the southeastern unit by about 100 clockwise and the northwestern unit by about 35 anti clockwise are supported by palaeomagnetic data in addition some rotations predicted by the model are documented by palaeomagnetic data as follows 1 the anti clockwise rotation of the flanks of the darno line gemer bukk area with sinistral displacements in the early miocene 2 the anti clockwise rotations along the southeastern margin of the northwestern unit with sinistral displacements before 10 ma 3 the anti clockwise rotation of the ukrainian carpathians before 12 ma some palaeomagnetic rotations have not been predicted by the kinematic model but occur in the regions where deformations are quite probable these unexpected palaeomagnetic rotations throw a new light on some details of the kinematics 1 the advance of the outer west carpathian nappes later than 14 ma is documented by the increased palaeomagnetic inclination of the pieniny andesites 2 the movement of the central and inner west carpathians later than 12 ma is recorded in the palaeomagnetic rotations of the central and east slovakian volcanites this movement seems to reflect a bay of thin crust within the underthrust european plate margin or more precisely the reaction of the eastern contour of the bay on the drag of the northwestern unit towards the northeast by the still rotating southeastern unit the rotation and deformation of the northwestern unit in the miocene have to be taken into account in the reconstructions of the pre neogene situations since they intensely influenced the arrangement of all older palaeotectonic and palaeogeographic zones the southeastern unit also suffered intense rotation and deformation in the miocene unfortunately there are almost no palaeomagnetic data available for its tertiary complexes

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

counter clockwise rotations in the southern apennines during the pleistocene paleomagnetic evidence from the matera area sediments from late pliocene to early pleistocene age have been sampled at six different localities sections 38 sites in the matera area which is in the southern part of peninsular italy basilicata three of the localities are from the apenninic belt the other three from the bradano unit both of them west of the earlier sampled apulian unit stepwise thermal demagnetisation revealed that usually two important components contribute to the natural remanent magnetisation nrm of these clay sediments a low temperature lt component removed between 100 and 300 320 c and a high temperature ht component removed between 300 320 and 430 450 c the ht component is a characteristic remanent magnetisation chrm for the sediments and has a clear primary pre folding origin in fresh unweathered sediments the lt component is identical in direction to the ht component but there is evidence that moderate weathering replaced a high intensity primary lt component with a low intensity secondary lt magnetisation the ht magnetisation is affected by this weathering process in a decrease of its intensity a counter clockwise deflection in declination is observed for the sites sampled in the apenninic belt the ht directions reveal a 23 counter clockwise rotation relative to the magnetic north dm 336 6 and im 57 2 sites in the bradano unit have no tectonic rotation dm 359 1 and im 56 3 earlier sampled sites from the apulian unit also showed no tectonic rotation dm 359 4 and im 57 0 paleomagnetic data support the hypothesis that the southern apennines rotated in the middle late pleistocene after the major phase of extension in the southern part of the tyrrhenian basin and contemporaneous with a regional compressional phase

kinematic evolution of the romanian carpathians abstract the regional pattern of contraction and extension directions and the evolution of the strain field from paleogene to neogene times enabled a reconstruction of the migration path of the carpathian collision front the carpathian nappes were thrust around the moesian plate during paleogene and early neogene times and protruded into a small oceanic embayment between the moesian and european plates the arc structure of the carpathian fold thrust belt was formed in late neogene times as a result of the eastward escaping tisza dacia block due to n directed convergence of the adriatic plate and the retreating subduction of an oceanic slab brittle deformation structures in the romanian carpathians suggest three tectonic events related to major plate motions 1 paleogene to middle miocene ne to ene contraction caused right lateral curved strike slip faults 2 middle miocene to pliocene fan shaped orientations of contraction directions were caused by right lateral oblique convergence in the southern carpathians frontal convergence in the southern eastern carpathians and left lateral convergence in the northern eastern carpathians 3 pleistocene to holocene general e w extension and n s contraction in the carpathian arc and local ese wnw contraction in the vrancea area is related to the late roll back stage and break off of the subducted slab in the bend area

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

paleomagnetic reconstruction of the cenozoic evolution of the eastern mediterranean abstract a total of 113 paleomagnetic sites were sampled along an anatolian s n transect from the arabian platform the hatay region the eastern taurides the kirsehir block the sivas basin and the eastern pontides reliable characteristic remanent paleomagnetic directions were retrieved from 37 of these sites spanning in time from paleocene to miocene in a general way declinations are westerly deviated and inclinations are shallower than the geocentered dipole value at the present latitudes when combined with previously published results these data indicate that a large scale counterclockwise rotation of anatolia of some 25 has occurred since the miocene assuming that the pole of rotation of anatolia with respect to europe has remained constant in time at the location given by macclusky et al j geophys res 105 2000 5695 on the basis of the geodetic data this rotation implies that a large westward displacement 500 km at the average latitude of 40 has taken place assuming that the rotation was initiated by the arabia europe collision about 12 ma ago this corresponds to an average displacement of about 40 mm year together with previous results from the western part of the aegean arc these results indicate that the main trends of the cenozoic evolution of the eastern mediterranean appear to consist of two post early miocene rotations of opposite senses a clockwise rotation of the western part of the aegean tectonophysics 146 1988 183 around a pole situated in northern albania and a counterclockwise rotation around the pole given by mcclusky et al j geophys res 105 2000 5695 comparison with gps data suggest that both rotations are still active today

role of the 3 d distributions of load and lithospheric strength in orogenic arcs polystage subsidence in the carpathians foredeep abstract it has been widely documented that the depth of foredeeps does not always reflect the topography of the neighboring orogens in many cases the topographic load is insufficient to explain basin subsidence such is the case of the se carpathians where an anomalously deep almost 13 km foreland basin has evolved since the middle miocene badenian a peculiar feature of this basin is its position relative to the orogen in contrast to typical foredeeps which deepen towards the belt the maximum depth of this basin is 10 20 km out of the orogen the subsidence in the carpathians bend foreland is characterized by two stages the first is middle miocene badenian in age and is related to ne sw extension when fault bounded basins were formed modeling shows that the foreland underwent small pre orogenic uniform thinning the modeling also predicts

orogen parallel extension in the southern carpathians a structural study including a kinematic analysis based on sense of shear criteria recorded in fault rocks is combined with fission track dating a two stage alpine tectonic evolution is proposed for the major tectonic units which constitute the southern carpathians of the parang mountains area upper cretaceous top to the sse nappe stacking was followed by wsw ene orogen parallel extension in the eocene top to the ene shearing in lower greenschist facies mylonites from the eastern part of the danubian window parang mountains is associated with a low angle detachment at the base of the brittlely deformed getic nappe the getic detachment below the dome shaped getic detachment east dipping at the eastern termination of the danubian window the danubian units were rapidly exhumed hence the eastern part of the danubian window represents a greenschist facies core complex as a working hypothesis it is proposed that this orogen parallel stretch was originally n s oriented and that it formed when the rhodopean fragment which includes the getic and supragetic nappes moved northward into an oceanic embayment past the western margin of moesia this eocene extension was part of a process of oroclinal bending in the area of the southern carpathians and their continuation into the balkan mountains extension was followed by about 50o clockwise rotation of the southern carpathians associated with dextral wrenching along the northern boundary of moesia and compression in the moldavides of the eastern carpathians 1998 elsevier science b v all rights reserved

palaeomagnetic study of some neogene magmatic rocks from the oas ignis văratec tibles mountains romania summary for this palaeomagnetic study 199 sites were sampled in the northern part of the east carpathians oas ignisl v ratec tibles sector after af alternating field demagnetization 155 sites were selected for further analyses a good agreement between the measured palaeomagnetic poles for the pontian the pannonian and the reference polar wander path of eurasia was made evident in the southern part of the ignis mountains the sarmatian volcanic rocks were affected by a 30 counterclockwise rotation with respect to europe post emplacement

the paleomagnetism of the upper cretaceous magmatic rocks in the banat area of south carpathians tectonic implications abstract forty four sites were sampled in upper cretaceous magmatic rocks in the western part of the southern carpathians banat area for a paleomagnetic study after detailed af demagnetization only 10 sites yielded primary remanent magnetizations the directions of which are similar to those identified in senonian magmatic rocks from the apuseni mountains and the ha eg and rusca montan basins the mean paleomagnetic pole for these three areas is compared with those from coeval formations of stable europe and stable africa this comparison shows a large clockwise rotation both with respect to africa and europe and a northward transport to reach their present day position during the tertiary the relations with adjacent zones of the tethys mobile belt are also discussed

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

palaeomagnetic constraints on the geodynamic evolution of the gibraltar arc subduction zone roll back was recently put forward as a convincing model to explain the geometry and evolution of the gibraltar arc for other subduction related arc systems of the mediterranean such as the calabrian arc and the hellenic arc palaeomagnetic rotation data from neogene extensional basins provided important constraints on geodynamic evolution models here we present the results of a palaeomagnetic study of 13 continuous sections that are located in e w transects across the neogene sedimentary basins of morocco and spain they provide evidence that no significant rotation about vertical axes has occurred in the gibraltar arc since the late tortonian comparison with other mediterranean arc systems shows strong similarities as regards geodynamic evolution the timing of rotation in the gibraltar arc is markedly older than in the calabrian and hellenic arcs and suggests that it is related to the first neogene extensional phase of the western mediterra

source side shear wave splitting and upper mantle flow in the romanian carpathians and surroundings we present shear wave splitting measurements from 5 earthquakes that occurred in the vrancea seismic zone of the carpathian arc s waves from these events all with magnitudes 5 4 mw and deeper than 88 km were recorded at broadband stations of the global seismic network and the geoscope and geofon networks and used by us to measure shear wave splitting corrected for sub station splitting and anisotropy in order to carry out these corrections we used published shear wave splitting parameters thus isolating contributions to observed splitting from the vrancea source region and upper mantle surrounding the carpathian arc the resulting 32 good observations of source side shear wave splitting along with 54 null splitting observations which yield two potential splitting directions clearly show that upper mantle anisotropy is strongly variable in the region of the tightly curved carpathian arc shear waves taking off from vrancea along paths that sample the east and southern carpathians have fast anisotropy axes parallel to these ranges whereas those leaving the source region to traverse the upper mantle beneath the transylvanian basin i e mantle wedge side trend ne sw shear waves sampling the east european and scythian platforms are separable into two groups one characterized by fast shear trends to the ne sw and a second deeper group with trends to nw se also the majority of null splits occur along paths leaving vrancea in these ne e azimuths we interpret these results to indicate the presence of at least three distinct upper mantle volumes in the carpathians region the upper mantle beneath the carpathian arc is strongly anisotropic with fabrics parallel to the local arc strike the transylvanian basin upper mantle fabrics trend ne sw and the anisotropy beneath the westernmost east european platform may be characterized by a shallow nw se trending fabric concentrated in the cratonic lithosphere of the east european platform and a second deeper fabric with e w trend marking asthenospheric flow beneath the craton s base this more complex anisotropy beneath the western edge of the east european platform would account for both the variability of observed splitting of waves that sample this volume and also the strong prevalence of nulls observed along eastward departing azimuths

neogene tectonic evolution of the southern and eastern carpathians constrained by paleomagnetism the neogene geodynamic evolution of the southeastern carpatho pannonian system is constrained by the timing and magnitude of vertical axis tectonic rotations derived from paleomagnetic analysis we report results from 13 paleomagnetic localities 139 sites 993 samples of middle miocene to pliocene sediments of the eastern carpathians region the southern carpathians region and the actively deforming bbend areaq between these two regions absolute age control of the sampled sediments is provided by previous magnetostratigraphic analysis our results indicate 1 systematic 308 clockwise rotations occurred in the southern carpathians after 13 ma 2 tectonic rotation had ceased in the investigated eastern and southern carpathians regions after 9 ma except in the bend area where recent clockwise rotations took place after 5 ma this pattern of rotations implies a concentration of tectonic activity during the middle to late miocene collision of the carpathian arc with the european platform followed by relative tectonic quiescence through the pliocene except in the bend area subject to late stage slab pull d 2005 elsevier b v all rights reserved

mesozoic plate tectonic reconstruction of the carpathian region abstract palaeomagnetic palaeobiogeographic and structural comparisons of different parts of the alpine carpathian region suggest that four terranes comprise this area the alcapa tisza dacia and adria terranes these terranes are composed of different mesozoic continental and oceanic fragments that were each assembled during a complex late jurassic cretaceous palaeogene history palaeomagnetic and tectonic data suggest that the carpathians are built up by two major oroclinal bends the alcapa bend has the meliata oceanic unit correlated with the dinaric vardar ophiolite in its core it is composed of the western carpathians eastern alps and southern alcapa units transdanubian range bukk this terrane finds its continuation in the high karst margin of the dinarides further elements of the alcapa terrane are thought to be derived from collided microcontinents czorsztyn in the n and a carbonate unit tisza in the se the tisza dacia bend has the vardar oceanic unit in its core it is composed of the bihor and getic microcontinents this terrane finds its continuation in the serbo macedonian massif of the balkans the bihor getic microcontinent originally laid east of the western carpathians and filled the present carpathian embayment in the late palaeozoic early mesozoic the vardar ocean occupied an intermediate position between the western carpathian austroalpine transdanubian high karst margin and the bihor getic serbo macedonian microcontinent the vardar and pindos oceans were opened in the heart of the mediterranean adriatic microcontinent in the late permian middle triassic vardar subducted by the end of jurassic causing the bihor getic serbo macedonian microcontinent to collide with the internal dinaric western carpathian margin an external penninic vahic ocean tract began opening in the early jurassic separating the austroalpine western carpathian microcontinent and its fauna from the european shelf further east the severin ceahlau magura also began opening in the early jurassic but final separation of the bihor getic ribbon and its fauna from the european shelf did not take place until the late middle jurassic the alcapa and the tisza dacia were bending during the albian maastrichtian the two oroclinal bends were finally opposed and pushed into the gates of the carpathian embayment during the palaeogene and neogene at that time the main n s shortening in distant alpine and hellenic sectors was linked by a broader right lateral shear zone along the former vardar suture

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

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

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

early diagenetic greigite as a recorder of the palaeomagnetic signal in miocene pliocene sedimentary rocks of the carpathian foredeep romania summary during the miocene pliocene the carpathian region represented the westernmost part of the so called eastern paratethys a palaeobioprovince that covered central and eastern europe as well as parts of southwest asia previous palaeomagnetic investigations provide a highresolution magnetochronology for the sedimentary sequences of the carpathian foredeep and indicate a marked transition in magnetic carriers from iron oxides to iron sulphides in chron c3r here we demonstrate using detailed rock magnetic investigations and scanning electron microscope sem analyses that the major magnetic iron sulphide mineral is greigite fe3s4 thermomagnetic runs indicate an irreversible decrease in magnetization with increasing temperature up to 400 c and sem observations indicate octahedral grain morphologies and fe s ratios that are indicative of greigite hysteresis loops have rectangular shapes which are typical of single domain behaviour with coercivity and coercivity of remanence at values of bc 35 45 mt and bcr 52 67 mt respectively first order reversal curve diagrams have contours that close around single domain peaks with bc values of 45 90 mt isothermal remanent magnetization component analysis reveals a small dispersion for the greigite component dispersion parameter dp 0 15 log units indicating a narrow grain size distribution a positive fold test inclination shallowing and two positive reversal tests are additional arguments for the syn depositional formation of this greigite we thus argue that most of the greigite was formed under early diagenetic conditions that is within 1000 yr of deposition of the sediment in this setting and that it thus can be considered as a reliable recorder of the palaeomagnetic signal in this situation the appearance of greigite during chron c3r between 6 0 and 5 5 ma in the carpathian foredeep is most likely related to regional tectonic and or climatic events that reshaped the basin configuration and changed the palaeoenvironmental conditions

a sedimentological and sequence stratigraphic reinterpretation of the upper cretaceous prairie canyon member mancos b and associated strata book cliffs area utah usa the mancos shale book cliffs eastern utah usa represents the open marine mudstones of the cretaceous western interior seaway and encloses the prairie canyon member which is located over 50 km seaward of interpreted contemporaneous highstand shoreline deposits in the blackhawk formation examination of the member reveals that it does not wholly represent offshore deposition as previously interpreted but instead contains three nearshore facies associations 1 tidally influenced fluvial channel fills 2 fluvial dominated delta fronts and 3 weakly storm influenced shorefaces tidally influenced fluvial channel fills are commonly stacked into multistory bodies that can be traced for tens of kilometers at discrete stratigraphic levels defining incised valley fill networks four such incised valley networks are identified at outcrop fluvial dominated deltas and weakly storm influenced shorefaces are eroded into by and lie at the down dip terminations of incised valley fills and are interpreted as forced regressive and lowstand shoreface deposits one incised valley fill appears to be onlapped by additional fluvial dominated deltas which represent pulses of shoreface progradation during an overall transgression forced regressive lowstand and transgressive shorefaces in the prairie canyon member differ significantly from highstand shorefaces in the blackhawk formation the former are sand poor and weakly wave storm influenced whereas the latter are sand rich and wave dominated this change in shoreface style reflects increased mud supply and an enhanced embayment paleogeography during periods of relative lowering of sea level

the mid hungarian line a zone of repeated tectonic inversions abstract the mid hungarian line is a major tectonic feature of the intra carpathian area separating two terranes of different origin and tectonic structure although this tectonic line was known from borehole records it has not been described in seismic sections the study presents interpreted seismic lines crossing the supposed trace of the mid hungarian line these seismic sections show north dipping normal faults and thrust faults as well as cross cutting young strike slip faults a complex tectonic history is deduced including intra oligocene early miocene thrusting middle miocene extension local late miocene inversion and late miocene pliocene normal faulting and left lateral wrenching in the light of our seismic study we think that the best candidate for the mid hungarian line is a north dipping detachment fault beneath large masses of neogene volcanics the auxiliary structures to the north seen on seismic sections suggest that it moved as a south vergent thrust fault during the palaeogene early miocene which later was reactivated as a set of normal faults the northern alcapa unit overrode the southern tisza dacia unit along this fault zone the same relative positions are observed in the northern termination of the line other structures along the supposed trace of the line are north dipping normal or strike slip faults which frequently were reactivated as smaller thrust faults during the late neogene palaeogene early miocene thrusting along the line might be the result of the opposite tertiary rotations of the two major units as suggested by palaeomagnetic measurements and earlier models

late miocene to early pliocene chronostratigraphic framework for the dacic basin romania abstract new magnetostratigraphic results and calcareous nannofossil data of seven sections in the dacic basin of southern romania covering the latest maeotian to early romanian time span 6 4 4 0 ma allow a correlation with the current astronomical polarity time scale this establishes a chronological framework for the pontian and dacian stages of the paratethys and facilitates to correlate the paratethys stages with those of the mediterranean the maeotian pontian boundary is estimated at 6 15 0 11 ma within subchron c3an 1n while the age of the pontian dacian boundary is 5 30 0 1 ma within subchron c3r the odessian portaferrian and portaferrian bosphorian substage boundaries can be placed at about 6 0 and 5 6 ma at the base and near the end of chron c3r respectively consequently the pontian stage has a duration of approximately 0 85 myr and is coeval with the upper half of the messinian stage the base of the dacian stage corresponds to the onset of the pliocene and is coeval with the pontian kimmerian boundary of the euxinic black sea basin the dacian romanian boundary is recorded either at 4 58 0 05 ma in subchron c3n 2n nunivak or at 4 25 0 05 ma in subchron c3n 1n cochiti the length of the dacian stage is therefore about 0 7 myr or approximately 1 ma the transition of the getian into the parscovian substage can be dated at 4 83 ma within subchron c3n 3n sidufjall or at 4 55 ma within subchron c3n 2n nunivak the occurrence of calcareous nannofossil assemblages in the lower portaferrian and near the portaferrian bosphorian transition belonging to the upper part of the discoaster quinqueramus nn11 zone and in the middle bosphorian belonging to the amaurolithus tricorniculatus nn12 zone indicates the presence of ephemeral marine connections between the paratethys basin and the mediterranean during the late messinian another marine influx inferred from nannofossil species characteristic of the nn12 zone and found in lower dacian sediments near the top of subchron c3n 4n thvera post dates the basal pliocene transgression of the mediterranean basin

palaeomagnetism of the south harghita volcanic rocks of the east carpathians implications for tectonic rotations and palaeosecular variation in the past 5 ma summary lavasofpliocene quaternaryageweresampledinthesouthharghitamountains whichform the southern end of the cu alimani gurghiu harghita volcanic chain of the east carpathians the analyses of 68 volcanic sites in the south harghita mountains provided 62 sites with well constrained directional data n 5 and k 50 in an age interval ranging from 0 5 to 4 3ma the age and polarity for the 62 sites 38 normal and 24 reversed are consistent with the geomagnetic reversal time scale and support the model of the southward migration of the volcanism the distribution of the vgps is fisherian and the mean pole position both from all contributing sites and from the 53 sites older than 2 ma includes the spin axis this result is consistent with the absence of important vertical axis rotations after the emplacement of the volcanicrocksinagreementwithtectonicmodelsforthepliocene quaternaryevolutionofthe bending area of the east carpathians virtual geomagnetic pole dispersions are consistently high compared with global values obtained between 40 and 55 n but closer to the values obtained only from the time averaged geomagnetic field initiative studies for the same latitudinal band our data are compatible with the prediction of the statistical palaeosecular variationmodeltk03 theinclinationanomalyislessthan1 inaccordwiththetotalaverage field global data these palaeomagnetic data from the south harghita volcanic rocks are the first data from the southeastern europe which can be considered in the databases for time averaged field and palaeosecular variation from lavas analyses in the last 5 ma

tectonic magmatic and metallogenic evolution of the tethyan orogen from subduction to collision abstract this paper reviews the tectonic magmatic and metallogenic history of the tethyan orogen from the carpathians to indochina focus is placed on the formation of porphyry cu mo au deposits as being the most characteristic mineral deposit type formed during both subduction and collisional processes in this region relatively little is known about the history of the paleotethys ocean which opened and closed between gondwana and eurasia in the paleozoic and few ore deposits are preserved from this period the neotethyan ocean opened in the permian early triassic as the cimmerian continental fragments the cores of turkey iran tibet and indochina rifted from the northern gondwana margin and drifted northwards these microcontinents docked with the eurasian margin at various points in the mesozoic and cenozoic and formed a complex archipelago involving several small back arc basins and remnants of the paleotethyan ocean the main neotethyan ocean and these smaller basins were largely eliminated by collision with india and africa arabia in the early eocene and early mid miocene respectively although neotethyan subduction continues beneath the hellenic arc and the makran the majority of porphyry type deposits are found in association with neotethyan subduction mainly in the mesozoic and paleogene and syn to post collisional events in the mid paleogene to neogene they are found throughout the orogen but some sections are particularly well endowed including the carpathians balkans rhodopes eastern turkey lesser caucasus nw iran se iran sw pakistan southern tibet and se tibet indochina other sections that appear barren may reflect deeper levels of erosion young sedimentary cover or lack of exploration although there may also be real reasons for low prospectivity in some areas such as minimal subduction e g the western mediterranean region or lithospheric underthrusting as proposed in western tibet over the last decade improved geochronological constraints on the timing of ore formation and key tectonic events have revealed that many porphyry deposits that were previously assumed to be subduction related are in fact broadly collision related some forming in back arc settings in advance of collision some during collision and others during post collisional processes such as orogenic collapse and or delamination of subcontinental mantle lithosphere while the formation of subduction related porphyries is quite well understood collisional metallogeny is more complex and may involve a number of different processes or sources these include melting of orogenically thickened crust previously subduction modified lithosphere including metasomatized mantle underplated mafic rocks or lower crustal arc plutons and cumulates or upwelling asthenosphere e g in response to delamination slab breakoff back arc extension or orogenic collapse the most fertile sources for syn and post collisional porphyry deposits appear to be subduction modified lithosphere because these hydrated lithologies melt at relatively low temperatures during later tectonomagmatic events and retain the oxidized and relatively metalliferous character of the original arc magmatism unusually metallically enriched lithospheric sources do not seem to be required but the amount of residual sulfide phases in these rocks may control metal ratios e g cu au in subsequent magmatic hydrothermal ore deposits relatively au rich deposits potentially form in these settings as observed in the carpathians e g rosia montan turkey kisladag copler and iran sari gunay dalli although the majority of syn and post collisional porphyries are cu mo rich and resemble normal subduction related deposits e g in the gangdese belt of southern tibet this similarity extends to the associated igneous rocks which being derived from subduction modified sources largely retain the geochemical and isotopic character of those original arc magmas while still retaining a broadly calc alkaline character these rocks may extend to mildly alkaline shoshonitic compositions and may display adakite like trace element signatures high sr y and la yb ratios reflecting melting of deep crustal garnet amphibolitic sources but they are otherwise hard to distinguish from normal subduction related magmas small post collisional mafic alkaline volcanic centers are common throughout the orogen but for the most part appear to be barren however similar rocks in other post subduction settings around the world are associated with important alkalic type porphyry and epithermal au cu deposits and the potential for discovery of such deposits in the tethyan orogen should not be overlooked

paleomagnetic evidence for counter clockwise rotations in the southern apennines fold and thrust belt during the late pliocene and middle pleistocene abstract marine and continental clay silt sediments from late miocene to middle late pleistocene age have been sampled in the southern apennines fold and thrust belt to detect the spatial and temporal aspects of tectonic rotations we sampled different parts of the tectonic system sites from both the internal western and the external eastern part the characteristic remanent magnetisation chrm component for the sediments is generally removed from 320 340 up to 450 480 c a counter clockwise rotation is observed for nearly all sites all data indicate that the main tectonic rotations in the southern apennines fold and thrust belt occurred in the middle pleistocene the late miocene to middle pliocene sediments reveal a 39 counter clockwise rotation which is similar to the rotation of the cretaceous carbonate rocks this indicates at least two phases of counter clockwise rotation a first rotation through approximately 15 during the late pliocene possibly contemporaneous with clockwise rotations in sicily 3 05 ma and a second rotation through at least 15 during the middle pleistocene there was also a third smaller rotation through about 9 since the middle pleistocene the results imply that there were no tectonic rotations in the southern apennines fold and thrust belt during the period of major shortening that took place in the early middle miocene nor during the opening of the southern part of the tyrrhenian basin in the latest pliocene earliest pleistocene our data further support the hypothesis that the late oroclinal rotations in the tyrrhenian arc were confined to distinct phases of regional compression

paleomagnetic evidence for a pleistocene clockwise rotation of the calabro peloritan block southern italy abstract a paleomagnetic study of marine marls of early pliocene age and clays of late pliocene to middle pleistocene age from sites along the ionian coast spartivento basin and catanzaro depression of calabria and from sites along the tyrrhenian coast of both calabria and sicily was carried out to determine the amount and timing of tectonic rotation of the underlying calabro peloritan block the magnetisations of the lower pliocene trubi marls have maximum blocking temperatures indicating the presence of magnetite these lower pliocene sediments as well as the younger upper pliocene lower pleistocene clays of this area reveal consistent clockwise rotations of 10 20 there is evidence for a uniform 15 clockwise rotation of the entire calabro peloritan block during the middle pleistocene this is opposite in sense of rotation to the earlier established 23 counterclockwise rotations for the southern apennines but the timing is the same between 0 7 and 0 2 ma the tectonic rotations occur 1 myr after the major phases of extension in the southeastern part of the tyrrhenian basin but simultaneously with the onset of major uplift of the block

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

vertical movements in and around the south east carpathian foredeep lithospheric memory and stress field control a 10 km thick basin formed in tertiary to quaternary times in front and overlapping with the south east carpathians the focs depression is part of this system and overlies the vrancea seismogenetic volume thought to correspond to the remnants of the continental slab subducted beneath the carpathians slab detachment and its lateral migration are considered to control vertical movements in the area we present the first complete analysis of subsidence patterns in the depression and derive a substantially different picture the strongest subsidence is sarmatian in age coeval with the main nappe emplacement events subsequently subsidence did not stop and persisted until present times despite cessation of thrusting the main depocen

no significant post eocene rotation of the moesian platform and rhodope bulgaria implications for the kinematic evolution of the carpathian and aegean arcs abstract the region located between the carpathian balkan and aegean arcs the moesian platform and bulgarian rhodope is generally assumed to have been stably attached to the east european craton during the cenozoic evolution of these arcs the kinematic evolution of this region is however poorly constrained by paleomagnetic analysis in this paper we provide new paleomagnetic data 800 volcanic and sedimentary samples from 12 localities showing no significant post eocene rotation of the moesian platform and rhodope with respect to eurasia therefore confirming the stability of this region we compare this result to a provided review of paleomagnetic data from the south carpathians tisza block and the aegean region the tisza block underwent 68 4 16 7 of middle miocene 15 10 ma clockwise rotation with respect to the moesian platform in line with previous rotation estimates based on structural geology the stability of the moesian platform during middle miocene eastward emplacement of the tisza block into the carpathian back arc supports dextral shear along the southern carpathians recorded by 13 6 ma clockwise strike slip related rotations in foreland deposits the new reference direction for the moesian platform and rhodope allows accurate quantification of the rotation difference with the west aegean domain at 38 0 7 2 occurring between 15 and 8 ma to accommodate this rotation we propose that the pivot point of the west aegean rotation was located approximately in the middle of the rotating domain rather than at the northern tip as previously proposed this new scenario predicts less extension southeast of the pivot point in good agreement with estimates from aegean structural geology northwest of the pivot point the model requires contraction or extrusion that can be accommodated by the coeval motion of the tisza block around the northwestern edge of the moesian platform

kinematics of retreating subduction along the carpathian arc romania kinematic axes and resultant vectors of displacement along the carpathian arc and the apuseni mountains aid in the reconstruction of retreating subduction along the carpathians the recent vertical position of the subducted slab below the vrancea area of the eastern carpathians represents the final rollback stage of a small fragment of oceanic lithosphere formerly situated between the moesian and east european plates the ages and locations of the eruption centers of the andesitic volcanic chain along the carpathian arc in the overriding plate as well as the thrust directions are used as markers to reconstruct the rollback area of the subducted slab between the moesian and east european plates

the syn and post collisional evolution of the romanian carpathian foredeep new constraints from anisotropy of magnetic susceptibility and paleostress analyses abstract the first results of anisotropy of the magnetic susceptibility ams data from the romanian carpathian foredeep reveal compression directions generally perpendicular to the highly bended carpathian orogenic arc the distribution of the present day stress field in the pannonian carpathian region reflects pre imposed plate boundaries that were established during late miocene collision analysis of the ams along the eastern and southern carpathian foredeep at the contacts of the orogenic nappe pile the lower plate and the overlying sedimentary rocks indicates that two factors are critical for the distribution of the stress field during and after collision i e 1 the inherited highly bended plate geometry and 2 the quaternary deformation that lead to differential vertical and horizontal movements in the se carpathians the ams analysis was successfully used in the weakly deformed mio pliocene sedimentary rocks from the carpathian foredeep revealing information about the deformation history of the soft non competent rocks where the poor preservation of traditional kinematic indicators e g faults and folds is difficult

provenance analysis as a key to orogenic exhumation a case study from the east carpathians romania provenance analysis of the sediments from foredeep basins is crucial in understanding the contemporaneous orogenic exhu mation processes we report in this paper complex sediment provenance analysis using sandstone petrography and mud stone geochemistry combined with magnetic susceptibility of the upper miocene to pliocene deposits from focsani foredeep basin romania data show a change of source area between 5 and 6 ma from an active volcanic arc towards a recycled orogenic belt concurrent with an important increase of accumulation rate this change was triggered by exhumation and erosion of the outer nappes from east carpathians

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

tomographic imaging of deep velocity structure beneath the eastern and southern carpathians romania implications for continental collision the vrancea seismic zone located beneath the elbow of the eastern and southern carpathians is characterized by intermediate depth seismicity associated with subduction and plate collision among many strong earthquakes that have occurred in the region the 1977 vrancea earthquake march 4 1977 ms 7 1 depth of 86 km caused extensive damage and fatalities the vrancea seismic zone is defined by a tabular region of seismicity that extends from the surface to a depth of 200 km the small size about 80 km in length and 40 km in width and geometry of the seismic zone have made it difficult to interpret the kinematics of subduction and continental collision in the romanian carpathians to better understand the collision subduction environment body wave seismic tomography was used to image the deep structure beneath the eastern and southern carpathians in romania a total of 7837 p and 2292 s arrival times from 433 shallow and intermediate depth earthquakes recorded by local and regional seismic stations were inverted for the three dimensional 3 d seismic velocity structure the travel times and ray paths were calculated by an efficient 3 d ray tracing technique by utilizing the lsqr algorithm p and s wave velocity perturbations were determined from the surface down to a depth of 200 km the high resolution p wave tomographic images reveal a pattern of broad heterogeneity in the velocity structure of the region one of the most important features is a high velocity body existing beneath the carpathian arc at depths between 100 and 170 km this high velocity body outlines a slab dipping near vertically where most of the intermediate depth earthquakes occur beneath the transylvanian basin a high velocity zone is dipping toward the se and may represent the base of lithosphere which is in convergence with the subducted slab low velocity bodies are found along the forearc of the carpathian foredeep down to depths of 70 to 80 km these low velocity bodies may be correlated with the shallow sedimentary layer in the foreland and may represent crustal materials wedged and underthrust along with the subducted lithosphere