cenozoic evolution of the eastern black sea a test of depth dependent stretching models abstract subsidence analysis of the eastern black sea basin suggests that the stratigraphy of this deep extensional basin can be explained by a predominantly pure shear stretching history a strain rate inversion method that assumes pure shear extension obtains good fits between observed and predicted stratigraphy a relatively pure shear strain distribution is also obtained when a strain rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form the timing of opening of the eastern black sea which occupied a back arc position during the closure of the tethys ocean has also been a subject of intense debate competing theories called for basin opening during the jurassic cretaceous or paleocene eocene our work suggests that extension likely continued into the early cenozoic in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism further basin deepening also appears to have occurred in the last 20 myr this anomalous subsidence event is focused in the northern part of the basin and reaches its peak at 15 10 ma we suggest that this comparatively localized shortening is associated with the northward movement of the arabian plate we also explore the effects of paleowater depth and elastic thickness on the results these parameters are controversial particularly for deep water basins and margins but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy

active inversion tectonics simple shear folding and back thrusting at rioni basin georgia abstract the rioni basin located between the greater and lesser caucasus in georgia is an outstanding example of ongoing inversion tectonics marine and continental deposits of cretaceous neogene age have been locally uplifted since the end of miocene the uplifted area totals 1300 km 2 and plio quaternary river deposits have been raised up to 200 m above the surrounding plains inversion tectonics has been accompanied by the development of south vergent asymmetrical folds and strike slip faults along the border of the uplifted area the folds have locally an en echelon geometry and microtectonic data indicate rotation of the paleostress direction over time suggesting simple shear deformation in the interiors of the uplifted area there are gentle symmetrical folds and one main active south dipping reverse fault corresponding to a backthrust morphostructural evidence as well as the tilting of quaternary strata the offset of quaternary alluvial deposits and the presence of crustal seismic activity indicate that compressional tectonics is still active the combination of field data with seismic reflection sections shows that inversion tectonics took place through a series of north dipping blind thrusts and a wedge with passive back thrusting uplift and contraction are more developed along the eastern part of the study area suggesting the westward propagation of the closure of the transcaucasian depression

cross sectional anatomy and geodynamic evolution of the central pontide orogenic belt northern turkey geophysical data allowed the construction of a 250 km long lithospheric scale balanced cross section of the southern black sea margin espurt et al in lithosphere 6 26 34 2014 in this paper we combine structural field data stratigraphic data and fault kinematics analyses with the 70 km long onshore part of the section to reconstruct the geodynamic evolution of the central pontide orogen these data reveal new aspects of the structural evolution of the pontides since the early cretaceous the central pontides is a doubly vergent orogenic wedge that results from the inversion of normal faults extensional subsidence occurred with an ene trend from aptian to paleocene we infer that the black sea back arc basin also opened during this period which was also the period of subduction of the tethys ocean below the pontides as in the western pontides the cretaceous paleocene subsidence was interrupted from latest albian to coniacian time by uplift and erosion that was probably related to a block collision and accretion in the subduction zone the restoration of the section to its pre shortening state paleocene shows that fault related subsidence locally reached 3600 m within the forearc basin structural inversion occurred from early eocene to mid miocene as a result of collision and indentation of the pontides by the kirsehir continental block to the south with 27 5 km 28 shortening along the section studied the inversion was characterized by nne trending shortening that predated the late neogene dextral escape of anatolia along the north anatolian fault and the modern stress field characterized by nw trending compression within the eocene boyabat basin

the black sea basins structure and history new model based on new deep penetration regional seismic data part 1 basins structure and fill abstract this work is based upon results of interpretation of about 8872 km long regional seismic lines acquired in 2011 within the international project geology without limits in the black sea the seismic lines cover nearly the entire black sea basins including russia turkey ukraine romania and bulgaria sectors a new map of acoustic basement relief and a new tectonic structure scheme are constructed for the black sea basins the basement of the black sea includes areas with oceanic crust and areas with highly rifted continental crust a chain of buried seamounts which were interpreted as submarine volcanoes of late cretaceous santonian to campanian age has been identified to the north of the turkish coast on the shatsky ridge probable volcanoes of albian age have also been recognized synorogenic turbidite sequences of paleocene eocene and oligocene ages have been mapped in the cenozoic numerous compressional and transpressional structures were formed in different parts of the black sea basin during the pleistocene quaternary turbidites mass transport deposits and leveed channels were formed in the distal part of the danube delta

hydrocarbon prospects in the western black sea of ukraine the ukrainian part of the western black sea consists of the odessa shelf which has shallow water up to 100 m and covers an area of 35 000 km2 and the northeastern part of the western black sea basin southwest of the crimea peninsula with water depths of 100 2200 m over an area of 50 000 km2 figure 1

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

northern caucasus basin thermal history and synthesis of subsidence models abstract burial histories of the eastern central and western parts of the northern caucasus basin are reconstructed on the basis of well data and seismic sections subsidence began in the early triassic after the late carboniferous permian orogeny triassic sediments were mainly removed during late triassic early jurassic uplift and erosion platform cover began to form in the middle jurassic and albian sediments covered the whole territory of the basin thermal modelling shows that jurassic eocene subsidence was mainly controlled by late triassic early jurassic intrusive warming this heating event induced thermal uplift of the whole territory followed by exponentially decelerating subsidence due to cooling of the lithosphere in the southern areas adjacent to great caucasus subsidence was also affected by caucasian extensional and compressional events in the oligocene early miocene the eastern and the central basins underwent rapid long wavelength subsidence maikopian subsidence the geodynamic cause of this subsidence is probably associated with the mantle flow appearance after cessation of the tethyan subduction due to reequilibration of subducted slab while in the late miocene quaternary times the eastern and the western basins underwent foreland type asymmetrical subsidence due to loading of the great caucasus orogen the central basin was uplifted according to flexural modelling the main component of orogen loading was the lithospheric root load delamination of the latter under the central caucasus caused rapid uplift of the orogen and adjacent basin

western versus eastern black sea tectonic evolution pre rift lithospheric controls on basin formation abstract we demonstrate the key role of pre rift rheology on the kinematics of basin formation in the western and eastern black sea basins constraints on modelling results are provided by a large data set based on more than 50 000 km of multichannel seismics offshore and onshore wells regional gravity and magnetic surveys refraction seismics and field studies the model supports the presence of important differences in the thickness and in the thermal state of the lithosphere which rifted to form the western middle barremian and the eastern middle paleocene black sea subbasins a 200 km and a 80 km thick pre rift lithosphere appear to have driven the deformation in the western and in the eastern black sea respectively differences in the geometry and in the mechanical properties of the pre rift lithosphere have a strong control on the depth of necking and thus on the basin morphology the model sheds light on palaeotectonic and palaeogeographic reconstructions duration of rifting events location of subsiding areas and erosional surfaces the western and the eastern parts of the black sea appear to be two distinct basins characterised by different evolutionary paths determined by different pre rift conditions

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

postglacial water level changes of a small lake in southern quebec canada sediment stratigraphy and palaeobotanical data from five cores were used to reconstruct the postglacial water level changes of a small lake in southern quebec the cores were taken along two transects from the centre of the lake to the margins lake level was relatively high before 11 000 cal bp when sedimen tation was characterized by the deposition of silty gyttja 13 000 cal bp and marl 13 000 11 000 cal bp from 11 000 to 7000 cal bp a sediment hiatus was indicated by the lack of two regional pollen zones between the marl and the overlying gyttja suggesting either nondeposition or erosion of the previously deposited sedi ments due to a low lake level the lake level was approximately 2 m lower than present on the basis of macrofossil assemblages a rise in the water level of about 1 m occurred around 7000 cal bp which was interrupted by a second lowering between 6100 and 4400 cal bp as indicated by a hiatus in the pollen stratigra phy during this low period the water level was at leas

the black sea back arc basin insights to its origin from geodynamic models of modern analogues the black sea is generally thought to be a back arc basin with active extension rifting beginning in late early cretaceous times although some fundamental issues such as the presence or absence of a related magmatic arc and the orientation of the related driving subduction zone remain vaguely defined at best however as shown here the regional structure of the black sea is consistent with that predicted by geodynamic models of modern back arc basin formation in which extension is driven by slab roll back this includes an asymmetric distribution of horst and graben structures in the back arc basin the distribution and spacing of which is related to the strength of the underlying lithosphere which forms the hanging wall of the subduction zone by analogy the intrabasinal structure of the black sea as a whole is explicable as the consequence of a single phase of asymmetric back arc basin formation not two separate phases independently responsible for its western and eastern segments and its underlying lithosphere is rheologically strong as predicted by recent models of precambrian europe and present day tomography

short term exciting long term correcting models for earthquake catalogs a class of probability models for earthquake occurrences called short term exciting long term correcting selc models is presented this class encompasses features of two different classes of models presently used in hazard analysis to characterize earthquake catalogs 1 self exciting models and 2 self correcting models it offers the potential for a unified approach to the analysis and description of different types of earthquake catalogs maximum likelihood estimation methods for the seismicity model parameters and standard errors are presented sample selc models are shown to provide satisfactory fit to a seven year catalog of microearthquakes occurring in parkfield california and a longer seismicity sequence from the san andreas fault zone in central california inferences on seismicity patterns and mechanisms are discussed both significant clustering and strain release are detected the suggested procedure should lead to improved seismic hazard analysis and mapping

late cenozoic burial history and dynamics of the northern caucasus molasse basin implications for foreland basin modelling abstract the collisional history of the caucasus segment of the alpine himalayan fold belt started at the end of the eocene the associated development of the northern caucasus foreland basin occurred during two syn collisional stages each displaying different subsidence patterns the 34 16 ma maikopian or pre foreland stage displays a long wavelength subsidence of a broad area whereas the 16 0 ma foreland stage displays asymmetrical foreland subsidence the first is correlated with the termination of subduction in the southern area and can be associated with mantle flow induced by the re equilibration of the subducted slab the along strike configuration of the second molasse basin stage contradicts the hypothesis in which topographical loading is considered to be the main control on foreland subsidence there is a clear anti correlation between basin depths and orogen heights the deepest parts of the basin are at the tips of the orogen where mountain heights are negligible while the area adjacent to the highest mountains central caucasus is uplifted the influence of other types of loading in foreland basin development has therefore been investigated and it has been possible to find a good fit with both gravity and basin architecture by including only two additional model parameters into the model these are crustal and lithospheric thickening thinning the results demonstrate that crustal thickening and removal of lithospheric roots are responsible for supporting the high central caucasus mountains and uplift of adjacent areas the subsidence of the basins at the orogen tips is explained by loading of lithospheric roots both effects are important in the geographically intermediate areas in general it is concluded that topography should not be considered as the main control on foreland subsidence but only as one of several counterbalancing mechanisms the existing flexural model therefore needs improvements such that it can be related directly to subsurface loading by real structures and processes during collision

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

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

thermo mechanical modelling of black sea basin de formation abstract we present the results of a thermo mechanical modelling study carried out to investigate the effect of pre rift rheology on subsequent basin de formation in the black sea area important differences are inferred for the bulk lithosphere structure and mechanical properties expressed in terms of different estimates for levels of necking in the western and eastern black sea respectively gravity data provide constraints on the mode of flexure in the black sea pointing to significant lateral variations in pre rift lithospheric strength these features strongly affect predictions for mesozoic cenozoic basin stratigraphy and have implications for the presence and development of rift shoulder topography on the margins of the black sea basins differences in lithosphere strength affect the mode of stress propagation from the basin margins into the central parts of the black sea basins during the post rift phase these post rift compressional stresses could be of key importance for long wavelength late neogene differential motions within the basins superimposed on vertical motions induced by rifting and subsequent sediment loading thermo mechanical modelling of integrated lithospheric strength points to a rapid increase of strength during the later stages of post rift evolution and the presence of relatively strong lithosphere in the centre of the basin these features predict preferential shortening induced by compressional activity of surrounding orogens to be primarily accommodated at the basins margins