fault reactivation in brittle viscous wrench systems dynamically scaled analogue models and application to the rhine bresse transfer zone abstract analogue experiments on oblique rifting and subsequent transpressional reactivation were performed with two layer slabs of sand and silicone in this brittle viscous system transtensional and transpressional wrench faulting was induced by movements of a basal rigid plate the dynamically scaled analogue models are confronted with the structural evolution of the rhine bresse transfer zone rbtz that linked palaeogene rifting in the upper rhine and bresse grabens and that appears to have been transpressively reactivated in neogene to recent times fault patterns produced in the sand layer above the basal silicone layer are compared with structural elements in the sedimentary cover separated from the basement by an evaporitic decollement layer in order to investigate strain rate dependence of fault reactivation and graben inversion transpressional shortening was performed under different displacement rates experimental results suggest that the reactivation of pre existing structures in a brittle cover above a viscous decollement is strongly dependent on the strain rate within the viscous layer under low to intermediate displacement rates 2 6 cm h 1 deformation concentrates within the basal viscous layer and former normal faults within the cover are not reactivated the reactivation at higher displacement rates 5 cm h 1 results in a complete inversion of graben structures within the cover ongoing shortening produces lobed thrust fronts which crosscut pre existing normal faults late pliocene to recent en echelon aligned folds and isolated thrust faults in the cover of the rbtz are attributed to thick skinned reactivation of basement faults a comparison of natural and experimentally obtained structures suggests that fault reactivation occurred under low displacement rates

enso and solar driven sub milankovitch cyclicity in the palaeogene greenhouse world high resolution pollen records from eocene lake messel germany the annually laminated oil shale from the eocene maar lake at messel germany provides unique palaeoenvironmental and palaeoclimatological information for the palaeogene greenhouse phase two palynological analyses of 6 3 and 70 kyr long records with a temporal resolution of 70 and 700 years respectively confirm vegetation and climate variability in the sub milankovitch range this variability clearly corresponds to cyclic climate fluctuations indicating the influence of solar activity and a millennial scale variability of the el nino southern oscillation also seen during the quaternary icehouse system this provides strong evidence of cyclic fluctuations in the sub milankovitch frequency band that represent a pervasive and persistent system not only of the quaternary icehouse but also throughout the entire neogene and the palaeogene greenhouse this is proof for the long term stability of the driving forces of natural climate change on earth fluctuations in the frequency of palynomorphs indicate cyclic short term quantitative changes in the composition of the vegetation these changes were related to precipitation and corresponding fluctuations of the lake level as well as to changes in pollen production transport and deposition supplementary material a complete list of variables and palynomorphs used for pollen diagrams and statistical analyses as well as additional time series analyses are available at https doi org 10 6084 m9 figshare c 3458778

veins in clay rich aquitards as records of deformation and fluid flow events in northern switzerland abstract the jurassic clay rich aquitard sequence underlying the swiss molasse basin is locally penetrated by unusually frequent veins consisting of calcite celestite in particular in the schlattingen 1 and oftringen drill cores the veins are linked to extensional brittle structures with shear senses ranging between dip slip and strike slip deformation triggered transient and localised events of fluid flow within the aquitard followed by sealing of the structures by the vein minerals vein calcite was dated by la icp ms analysis using the u pb method while this was a demanding undertaking given the low u and high common pb contents of calcite 9 significant ages could be obtained two groups of ages can be distinguished namely 31 39 and 11 18 ma both age groups are consistent with the known regional tectonic evolution the older age group corresponds to the main phase of rifting in the upper rhine graben a major crustal discontinuity whose effects were not limited to the graben proper but affected large parts of the molasse basin the younger age group is linked to crustal tilting and related extensional deformation isotopic compositions of o and c in vein calcite from the schlattingen 1 core show substantial variability but do not discriminate between veins of the two age groups in contrast 87sr 86sr ratios in veins show different signatures the depth trend of 87sr 86sr ratios in veins fits well with that in pore water obtained by rock squeezing the two data sets define a trend of values increasing with depth connecting the current values in the embedding malm and keuper aquifer waters this trend is best explained as a near steady state diffusion profile while advective mixing of waters originating from the embedding aquifers to produce the veins implying structures that cross cut the whole low permeability sequence cannot be discarded on the basis of existing data it is considered more likely that the veins have local fluid sources these are mixtures of local pore water with a possible contribution of water from the nearest aquifer implying maximum vertical advection distances in the order of 50 100 m

sedimentary response to tectonics in extensional basins the pechelbronn beds late eocene to early oligocene in the northern upper rhine graben germany

comparative tertiary stratigraphy of the rhine graben bresse graben and molasse basin correlation of alpine foreland events abstract comparative tectonostratigraphic analysis of the tertiary middle eocene pliocene of the rhine bresse graben system and the western molasse basin demonstrates the occurrence of eleven correlative sequences crf i xi these show a close relationship between intra basinal tectonics and depositional history their punctuated sediment accumulation can be related to phases of extra alpine taphrogenesis and alpine orogenesis and to coeval eustatic changes in sea level apparent simultaneity in rift and foredeep sequence development structural deformation and global change in sea level suggests a common causal control in which the development of the alps played an important role

morphologie des constructions microbiennes en contexte de fan delta oligocene exemple du rift rhenan europe occidentale abstract at the eocene oligocene boundary a first paroxysmal phase of subsidence created the rhine rift graben system a lacustrine basin with variable salinity was formed in the graben in the southern part of this basin a large fan delta developed extending northward along the graben axis microbial ecosystems settled on the fringe of the lake in the paludal zone they formed carbonate encrustations on living plants or detrital vegetal remains littoral carbonate facies occur as algal bioherms and stromatolitic reefs in the distal lacustrine zone a discrete nodular texture within the sediment reveals the microbial origin of micrite and gives the limestone a breccial pattern all these facies illustrate the lateral zonation of the different types of constructions from fluvio deltaic to lacustrine in certain cases the microbial coating on plants permits to reconstruct seasonal rhythms and the processes of substratum colonisation

the rhinegraben extension subsidence and shoulder uplift abstract we apply a numerical model of the thermal evolution of a continental lithosphere undergoing extensional deformation to the rhinegraben using reasonable parameters the results of computations are in agreement with the present configuration of the rift and of its shoulders as well as with their evolution since the oligocene contrasting evolutions are reconstructed in the northern and southern rhinegraben whereas the northern history is accounted for by a simple model of homogeneous stretching of the lithosphere the history of the southern rhinegraben cannot be explained without introducing two main periods of heterogeneous stretching the results are locally supported by structural analyses of extensional patterns factors of extension average 1 2 in the axial portion of the rhinegraben and 1 15 for the whole rift section suggesting that the total amount of e w extension reaches 6 km

pliocene uplift of the massif central france constrained by the palaeoelevation quantified from the pollen record of sediments preserved along the cantal stratovolcano murat area the french massif central is a key basement relief this region experienced an intense period of alkaline volcanism beginning with the cantal stratovolcano at 11 ma and ending at 3 ma to quantify the palaeoelevation of the cantal stratovolcano and to replace it in the frame of the uplift history of the massif central we first reconstructed the vegetation and climate based on a pollen analysis of the murat diatomites which were deposited in a maar lake the vegetation was organized in three different belts a glyptostrobus swamp around the lake a mixed forest and at higher altitudes a conifer forest the climate estimated using the climatic amplitude method indicates temperatures between 11 4 and 17 c using these estimates and comparison with contemporaneous sites we infer a palaeoelevation for murat between 710 and 930 m a s l this site was therefore uplifted by 130 to perhaps 350 m during the early pliocene leading to a reorganization of the drainage pattern and the capture of rivers flowing from the northern edge of the massif central towards the atlantic ocean our study confirms that the cantal stratovolcano was a high volcano 2500 m before its progressive dismantling during glacial episodes in the pleistocene

a deep reflection seismic line across the northern rhine graben abstract two reflection seismic lines across the tertiary rhine graben in central europe were recorded in 1988 as a joint venture of the french ecors and the german dekorp deep seismic reflection programs in this paper the line across the northern graben is presented the main results are the asymmetry of the graben as documented by the sedimentary fill is accompanied by asymmetric features throughout the entire deep crystalline crust a thin 3 7 s twt reflective lower crust in the east a thick 5 5 s twt relatively transparent lower crust in the west total crustal thicknesses of 8 7 s twt in the east vs 10 5 s twt in the west provided a laterally homogeneous crust existed prior to rifting significant differences in upper and lower crustal thinning must be postulated extension occurred along localized shear zones that are located in the upper crust and at the crust mantle boundary the entire lower crustal layer acts as a decoupling zone

the jura mountains an active foreland fold and thrust belt abstract recently completed in situ stress measurements using the borehole slotter at 33 new test sites within the swiss and french jura mountains combined with previously published stress data allow a detailed description of the contemporary state of stress in this fold and thrust belt and the adjacent foreland five stress provinces can be recognized with two different general orientations of maximum horizontal stress sh 1 the central and southwest provinces with a nnw sse to nne ssw orientation 2 the east northwest and southeast provinces with an e w to nw se orientation stress magnitudes are in general higher in the southern than in the northern jura mountains characteristic of the northern jura is an e w trending zone of low stress magnitudes which can be traced from the bresse depression south of besancon to the eastern end of the jura northwest of zurich boundaries of stress provinces show poor agreement with boundaries of tectonic units in the jura in addition stress provinces extend beyond the boundaries of the jura mountains into their foreland furthermore palaeo stress orientations show large discrepancies with respect to the contemporary stress orientation these findings are considered to indicate a termination of jura thin skinned foreland tectonics which probably took place some time between 9 and 4 ma according to palaeontological and tectonic evidence it is suggested that a new style of tectonics has commenced in the jura mountains deforming both the basement directly below the jura fold and thrust belt and the cover rocks in a similar mode

kinematic and geometric analysis of fault related folds in a rift setting the dannemarie basin upper rhine graben france abstract the upper rhine graben urg developed in the alpine foreland from mid eocene to pliocene as part of the west european rift system the dannemarie basin occupies the sw termination of the urg and is bordered by the vosges fault zone west and the illfurth fault zone east we constructed a 3d model of faults and principal pre and syn rift stratigraphic surfaces using all available subsurface and surface geological and geophysical data the model shows 1 syn rift strata thinning across kilometre scale fault parallel monoclinal flexures associated with basin margin faults and 2 major basin margin faults terminating laterally into major flexures sequential cross section restorations show that these flexures accommodated deposition of over 1300 m of syn rift strata salt series which is 42 63 of the basin fill these folds are interpreted as syn rift fault propagation folds that developed above normal faults their geometry is replicated in a trishear numerical model using reasonable parameter values fold development was controlled principally by 1 reactivation of favourably oriented basement faults 2 the presence of a thick viscous layer principally triassic evaporites allowing decoupling between crystalline basement and competent jurassic cover and 3 a relatively slow deformation rate

multi scale depositional successions in tectonic settings observations in sedimentary basins affected by deformation show that the fault induced depositional accommodation at various spatial and temporal scales is closely linked to basin kinematics the tectonically driven sediment infill displays the history of deepening and shoaling facies that are controlled by the activation of faults and changes in their offset rates simply stated this results in shifting sedimentary facies towards the source area or towards the basin centre in response to increasing or decreasing depositional space we propose a first principle conceptual model for tectonic successions controlled by the balance between the rates of creation of depositional space and sediment supply these sediment bodies are bounded by succession boundaries and comprise sourceward or basinward shifting facies tracts that are separated at a point of reversal due to the relatively steep slopes associated with the evolution of faults changes in sediment supply rates and mass wasting are common in these systems and may complicate the normal rhythm of the shifting facies tracts once tectonic quiescence is achieved and if the basin is connected to the open ocean eurybatic or eustatic base level changes may take over and play a greater role in sedimentary rhythm and cyclicity we illustrate the efficacy of the new concept with a review of examples from extensional contractional and strike slip basins we show that the basic tectonic succession model is applicable at all temporal and spatial scales and whether the tectonics cause subsidence or uplift and in all types of tectonic settings that determine the evolution of sedimentary basins

reactivated basement structures affecting the sedimentary facies in a tectonically quiescent epicontinental basin an example from nw switzerland abstract the jurassic deposits in the southern part of central europe accumulated in a shallow epicontinental sea and their deposition has usually been believed to have corresponded to a phase of tectonic quiescence neither on conventional seismic records nor in outcrops obvious indications of synsedimentary tectonics were found nonetheless subtle variations in lithofacies and thickness occur above faults in the crystalline basement in fact preexisting structures became reactivated in the jurassic during major extensional phases when the tethys and the north atlantic opened this reactivation led to differential subsidence and or to rotation of fault bounded blocks but the sediments were deformed mainly flexurally as vertical movements in the basement were dissipated by triassic salt thus the depositional area was morphologically differentiated into swells and depressions in siliciclastic muddy environments swells were characterized by hardbottoms and hiatus beds depressions were filled by distal tempestites and gravity deposits in carbonate settings reefs nucleated on swells marls and muds were deposited in depressions many of them gravity deposits reactivation of faults occurred only during short episodes and was not synchronous throughout the study area and reactivation of individual faults was episodic and probably controlled by the palaeostress field and the faults orientation reactivation of deep rooted faults is also documented by hydrothermal activity which led to vein mineralization and alteration of minerals today exposed in nearby basement units the chronostratigraphic ages of the hydrothermal processes coincide with phases of enhanced subsidence during the sinemurian aalenian bajocian bathonian and oxfordian in turn facies changes of the sedimentary cover should be useful to predict basement structures when no seismic records are available

low temperature thermochronology of the flanks of the southern upper rhine graben the upper rhine graben urg is the most perceptible part of the european cenozoic rift system uplifted variscan basement of the black forest and the vosges forms the flanks of the southern part of the graben apatite and zircon fission track ft analyses indicate a complex low temperature thermal history of the basement that was deciphered by inverse modelling of ft parameters the models were tested against the observed data and independent geological constraints the zircon ft ages of 28 outcrop samples taken along an e w trending transect across the black forest and the vosges range from 136 to 312 ma the apatite ft ages from 20 to 83 ma the frequency distributions of confined track lengths are broad and often bimodal in shape indicating a complex thermal history cooling below 120 c in the early cretaceous to palaeogene was followed by a discrete heating episode during the late eocene and subsequent cooling to surface temperature the modelled time temperature t t paths point to a total denudation of the flanks of urg in the range of 1 0 1 7 km for a paleogeothermal gradient of 60 c km and 1 3 2 2 km for a paleogeothermal gradient of 45 c km since the late eocene

the southern rhine graben a new view of the initial phase one of the puzzling features of the southern end of the rhine graben is the dinkelberg tabular jura block on the eastern shoulder of the graben it is dissected by a large number of faults the most notable ones forming a field of narrow little grabens and half grabens whose bordering faults converge at the level of the middle triassic evaporites which points to decollement at that horizon the little grabens were traditionally considered to be of oligocene age coeval with the main taphrogenesis of the rhine graben two hypotheses were offered for their formation one ascribing them to extension on the extrados of large basement folds the other to gravity sliding on paleoslopes recent field work uncovered overwhelming evidence for an eocene age of the little grabens the time of the initial phase of rhine graben formation at that time there were neither large basement folds nor paleoslopes of any significance and therefore the two hypotheses offered until now do not work however the map view pattern of the field of faults offers a somewhat unusual way out of the dilemma this pattern is most prominently displayed in the dinkelberg area north of the rhine there a lane of narrow decollement grabens with a mean nne strike is confined within the nw striking dinkelberg graben which is much wider and rooted in the basement it is also very shallow with a subsidence on the order of 100 m the lane of decollement grabens forms a dextral en echelon pattern with respect to the dinkelberg graben suggesting stretching of the post evaporite sequence above a basement essentially extended by strike slip this model though not as clearly expressed is also compatible with the data in the rest of the dinkelberg tabular jura block it also fits surprisingly well a theoretical model by withjack and scheiner 1982 that predicts a dominance of strike slip in the marginal area of a system consisting of extension superimposed on doming

tectonic implications of transpression and transtension upper rhine graben 1 seismic reflection data from the upper rhine graben urg show a series of synclines along the linear eastern boundary faults from north of karlsruhe to the jura mountains similar structures do not characterize the northern segment of the graben the synclinal shape is portrayed by inversion related to transpression on the linear boundary faults coupled with the conserved easterly dip of the sediments farther inside the tilted hanging block the onset of transpression preceded the known early burdigalian unconformity but was also an early miocene event it suggests that the regional compression axis 1 in early miocene had a trend between 315 and 0 the continuous transtension in the northern segment suggests that at no time during the history of the urg was the regional 1 horizontal with a ne sw trend the lack of transpressional structures in the younger plio pleistocene sediments along the entire eastern boundary of the urg suggests a late change in the regional stress field the main eastern boundary faults and synclines north and south of baden baden are all continuous and have the same trend kinematically they form a single graben segment and respond to the regional stress in the same way

organic matter of the mulhouse basin france a synthesis the lower oligocene evaporite sequence of the mulhouse basin france contains organic matter rich marl deposits these marls display an overall cyclic variation of sedimentation rate organic carbon content hydrogen index and selected molecular parameters over a 30 m thick stratigraphic interval the integration of all sedimentological and geochemical parameters has allowed the reconstruction and characterization of the paleoenvironment of deposition the marls were deposited in a perennial lake that was at times connected to the sea two organic facies end members could be assigned to a lake stage with a marine connection and a lake stage that received dominantly continental water input the overall stratigraphic variation in the organic matter content is interpreted to reflect the adaptation of the oligocene flora to the changing paleoclimate and environmental conditions

tectonic implications of faulting styles along a rift margin the boundary between the rhine graben and the vosges mountains 1 seismic reflection data show the effects of the miocene strike slip environment on the boundary between the upper rhine graben urg and the vosges mountains vm the border fault zone exhibits three types of responses to the new nw se directed regional stress regime where it trends n s no new deformation is observed where it trends nne ssw transpression is evident and it develops into a few kilometers wide zone of intense deformation along the ne sw trending southern boundary of vm transpression intensifies with an increase in the perpendicular shortening component and the border fault zone turns into a reverse fault the uplift of the boundary relative to the graben is estimated to be no less than 1000 m near colmar and significantly more along the boundary with the dannemarie basin these estimates and kinematics considerations support the hypothesis that the vosges mountains are mostly a transpressional feature the rhine fault is mapped and suggested to be a lower miocene structure that was formed in response to the change in the regional stress regime

hydroclimatic conditions and fishing practices at late paleolithic makhadma 4 egypt inferred from stable isotope analysis of otoliths abstract the late paleolithic site of makhadma 4 located along the nile river in upper egypt yielded an important ichthyofauna characterized by a very high proportion of tilapia oreochromis niloticus we used isotopic analysis 18o of well preserved otoliths ear stones of tilapia to reconstruct the former hydrological conditions as well as the fishing strategies of the site s inhabitants otoliths from two modern fish captured in the nile river near esna were also examined to test how accurately tilapia otoliths reflect their ambient environment all otoliths were sequentially micromilled to recover high resolution isotopic profiles along the main growth axis comparison of the modern otolith profiles with environmental data shows that tilapia 18o values record seasonal variations of the modern nile hydroclimate but that their values are offset the archaeological otoliths record very large intra individual cyclical variations in 18o values with relatively consistent amplitude as well as very high seasonal maximum values up to 8 3 compared with the modern otoliths the hydrological regime of the water body in which the archaeological fish lived was characterized by a reduced nile water inflow that could not negate the effect of local evaporation during spring the reconstructed hydrological conditions are in accordance with a new model of nilotic behavior that assumes the creation of lakes by damming of the nile as a result of a high eolian activity during hyper arid periods of the late pleistocene although large seasonal evaporation may have resulted in a severe seasonal reduction in the lake s volume and extent the lake was nevertheless maintained for several years cyclic variations in otolith 18o values permit reconstruction of the period of the hydrological cycle during which the fish were captured fishing of young individuals occurred mostly after the maximum input of inflow water from the nile when evaporitic conditions were at their lowest i e during fall

eocene pliocene time scale and stratigraphy of the upper rhine graben urg and the swiss molasse basin smb we present a general stratigraphic synthesis for the upper rhine graben urg and the swiss molasse basin smb from eocene to pliocene times the stratigraphic data were compiled both from literature and from research carried out by the authors during the past 6 years an index of the stratigraphically most important localitites is provided we distinguish 14 geographical areas from the helvetic domain in the south to the hanau basin in the north for each geographical area we give a synthesis of the biostratigraphy lithofacies and chronostratigraphic ranges the relationships between this stratigraphic record and the global sea level changes are generally disturbed by the geodynamic e g subsidence evolution of the basins however global sea level changes probably affected the dynamic of transgression regression in the urg e g middle pechelbronn beds and serie grise corresponding with sea level rise between ru1 ru2 and ru2 ru3 sequences respectively as well as in the molasse basin regression of the umm corresponding with the sea level drop at the ch1 sequence the urgent project upper rhine graben evolution and neotectonics provided an unique opportunity to carry out and present this synthesis discussions with scientists addressing sedimentology tectonics geophysics and geochemistry permitted the comparison of the sedimentary history and stratigraphy of the basin with processes controlling its geodynamic evolution data presented here back up the palaeogeographic reconstructions presented in a companion paper by the same authors see berger et al in int j earth sci 2005

the link between tectonics and sedimentation in back arc basins new genetic constraints from the analysis of the pannonian basin the architecture of sedimentary basins reflects the relationship between accommodation space and sediment supply their rates and localization being variable during basin evolution the mechanisms driving the interplay between tectonics and sedimentation in extensional back arc basins overlying rheological weak zones inherited from an earlier orogenic evolution are less understood a typical example is the pannonian back arc basin of central europe it is floored by continental lithosphere and was affected by large amounts of extension driven by the subduction rollback that took place in the carpathians and or dinarides a novel kinematic and seismic sequence stratigraphic interpretation calibrated by wells allows the quantification of the link between the formation of half grabens and coeval sedimentation in the great hungarian plain part of the basin while the lower order tectonic induced cycles characterize the main phases of extension in various subbasins the higher order cyclicity and associated unconformities define individual moments of fault re activation our novel interpretation of a temporal and spatial migration of extension during miocene times explains the contrasting present day strike of various subbasins as a result of their gradual clockwise rotation incorporating the observed asymmetry in particular the associated footwall exhumation infers that the amount of extension is much larger than previously thought the quantitative link between tectonics and sedimentation has allowed the definition of a novel model of sedimentation in asymmetric basins that can be ported to other natural scenarios of similarly hyperextended back arc basins observed elsewhere

structure and tertiary tectonic history of the mulhouse high upper rhine graben block faulting modified by changes in the alpine stress regime 1 the mulhouse high horst is situated in the southernmost upper rhine graben and changes in its tectonic history record the interaction with the adjacent alpine front recently released seismic data show that the mulhouse high consists of the sierentz and the altkirch tilted blocks separated by the ferrette fault zone with a throw of several hundred meters during the eocene early rupelian main rifting phase the mulhouse high was the elevated flank of the dannemarie basin with sedimentation affected by the nearby southern boundary of the rhine graben the miocene jura compression extended into the mulhouse high creating a series of semiparallel buried folds with no evidence for thin skin tectonics the change to a nw se regional compressive stress reactivated the main graben faults as wrench faults it also resulted in transpression on the ne sw trending faults particularly the northern segment of the illfurth fault zone consequently the northern part of the mulhouse high was uplifted strike slip motion along the ferrette fault zone is shown to be small

tracing tectonic deformation using the sedimentary record the study of sediments and sedimentary basins in terms of their tectonic environment requires a multidisciplinary approach and has increasingly drawn both techniques and objectives from fields outside sedimentology the application of different theoretical experimental and empirical resources provided by structural geology geochemistry geophysics scale modelling and field geology complement sedimentological methods with the combined aim of achieving a deeper understanding of the origins evolution and significance of sedimentary sequences in terms of their tectonic history studies presented in this volume range across a wide spectrum from the analysis of sedimentary sequence architecture at basin scale down to the chemical properties of individual grains and include studies from a range of tectonic settings the volume will be of interest to those involved with or contemplating studies involving the linkages between tectonics and sedimentation as well as a wider audience to whom the results of such studies may provide fresh insight

anatomy and kinematics of oblique continental rifting revealed a three dimensional case study of the southeast upper rhine graben germany the upper rhine graben is a north northeast trending small displacement crustal scale rift of tertiary age retrodeformation of its southeastern part demonstrates that it is a product of sinistral oblique rifting early extension was toward 80 later the major stretching axis changed to a 60 direction the modeling results suggest that the eastern main border fault developed first and that faulting later propagated into the evolving graben interior considerable along strike variations in heave throw and displacement are evident displacement partitioning causes warping of the rift floor with a 30 35 km wavelength we consider this to be a characteristic of oblique rifting contact deformation of the wall rocks to the major faults may have caused widespread smaller scale faulting and brecciation and may be the location of later movements close spatial coincidence of the depth projections of some of the faults studied and the hypocenters of recent small earthquakes indicates continuing activity of the fault system apparently three fault segments in the freiburg area are currently active and may be an increased earthquake risk

plio pleistocene transpressional reactivation of paleozoic and paleogene structures in the rhine bresse transform zone northern switzerland and eastern france pliocene to recent uplift and shortening in the southern rhinegraben is documented by deformation of pliocene fluvial gravels deposited on a nearly planar surface as well as by progressive deflection and capture of rivers this deformation is suggested to result from thick skinned tectonic movements as evidenced by ob servations on seismic records which demonstrate a spatial coincidence between en chelon anticlines at the surface and faults located in the crystalline basement these findings contradict the often invoked thin skinned tectonism in the recent tectonic history of the rhine graben in particular the transfer zone between the rhinegraben and the bressegraben is very suitable for reactivation under the present day stress field thick skinned reactivation of faults in the basement is also expressed by focal plane mechanisms of recent earth quakes showing strike slip rather than reverse faulting characteristics this is of importance for the densely populated and industrialised southern rhinegraben pre viously affected by large earthquakes in historical times e g basel 1356

eocene oligocene tectonics and kinematics of the rhine saone continental transform zone eastern france a tectonic analysis of brittle deformaton was performed in the rhine saone transform in order to decipher and understand the deformation processes in a typical continental hansfer zone cenozoic major and minor fault patterns are described and brittle structures are interpreted in terms of paleostress orientations the eocene n s compression related to africa eurasia convergence is marked mainly by strike slip faults it was followed by a major phase of crustal extension mainly oligocene in age related to the west european rifting this extensional phase is expressed by normal faults tension gashes and extensional strike slip faults which are especially abundant in the transform zone these two events are found to be quite different in terms of distribution of horizontal shess trajectories the trend of ol axes is very homogeneous for the n s compression whereas o3 orientations associated with the major extension vary from e w in most of the rift system to i v se within the transform zone finally the mio pliocene tectonic emplacement of the jura fold and thrust belt is marked in the field by strike slip faults associated with a well defined trend of ol oriented w iiw e se to nw se the preexisting basement fracture pattern between the grabens was also considered in order to estimate which faults were likely to have been reactivated during the oligocene transform kinematics and the theoretical shear motion on these inherited fault surfaces when submitted to e w extension was calculated left laterauextensional reactivation of a preexisting 60 n trending fault system in the brittle upper crust is likely to have accommodated the shear strain arising between the rift segments in response to crustal stretching two independent numerical modelings based on distinct element and finite element analyses respectively enabled us to verify and to refine the hypothesis of transform kinematics related to e w extension and inducing regional perturbations of extensional stress trajectories the overall mechanism and the transtensional kinematics of the rhine saone transform zone are thus tightly conshained the inherited crustal anisotropy the large scale perturbations of extensional stress trajectories and the development of distributed brittle deformation within the sedimentary cover are found to play a major role in the tectonic evolution of continental rift transform systems

graben width controlling syn rift sedimentation the palaeogene southern upper rhine graben as an example eocene to early oligocene syn rift deposits of the southern upper rhine graben urg accumulated in restricted environments sedimentation was controlled by local clastic supply from the graben flanks as well as by strong intra basinal variations in accommodation space due to differential tectonic subsidence that in turn led to pronounced lateral variations in depositional environment three large scale cycles of intensified evaporite sedimentation were interrupted by temporary changes towards brackish or freshwater conditions they form three major base level cycles that can be traced throughout the basin each of them representing a stratigraphic sub unit a relatively constant amount of horizontal extension l in the range of 4 5 km has been estimated for the urg from numerous cross sections the width of the rift lf however varies between 35 and more than 60 km resulting in a variable crustal stretching factor between the bounding masterfaults apart from block tilting tectonic subsidence was therefore largely controlled by changes in the initial rift width l0 the along strike variations of the graben width are responsible for the development of a deep trough like evaporite basin potash basin in the narrowest part of the southern urg adjacent to shallow areas in the wider parts of the rift such as the colmar swell in the north and the rhine bresse transfer zone that delimits the urg to the south under a constant amount of extension the along strike variation in rift width is the principal factor controlling depo centre development in extensional basins

evolution and structure of the upper rhine graben insights from three dimensional thermomechanical modelling the evolution and geometry of the tertiary upper rhine graben were controlled by a continually changing stress field and the reactivation of pre existing crustal discontinuities a period of wnw ese extension in the late eocene and oligocene was followed by lateral translation from the early miocene onwards this study utilizes 3d finite element techniques to simulate extension and lateral translation on a lithospheric scale brittle and creep behaviour of lithospheric rocks are represented by elastoplasticity and thermally activated power law viscoplasticity respectively contact elements allocated with cohesion and frictional coefficients are used to describe pre existing zones of weakness in the elastic brittle field our results suggest that 1 extension is accommodated along listric border faults to midcrustal depth of 15 16 km beneath pure shear stretching occurs without a need for localized shear zones in lower crust and upper mantle 2 ductile flow at midcrustal depth across the graben accounts for the pronounced halfgraben morphology thereby the shape of the border faults their frictional coefficients and sedimentary loads have profound effects on the rate of ductile flow across the graben 3 horizontal extension of 8 8 5 km and sinistral displacement across the rift of 3 4 km are needed to accommodate the observed sediment thickness

upper rhine graben role of preexisting structures during rift evolution 1 the evolution of the cenozoic upper rhine graben was controlled by a repeatedly changing stress field and the reactivation of a complex set of crustal discontinuities that had come into evidence during permo carboniferous times a comparison of the spatial and temporal thickness distribution of synrift deposits with preexisting fault patterns permits to infer a sequence of distinct basin subsidence phases that can be related to changes in the ambient stress field reactivation of a system of late palaeozoic fault systems outlining troughs and highs controlled the nucleation of initially separated middle and late eocene basins the depocenters of which coincided with a preexisting wsw ene trend during oligocene crustal extension the individual basins coalesced resulting in the development of the ssw nne striking upper rhine graben during the late oligocene chattian change in stress field the upper rhine graben was probably reactivated as a dextral strike slip system with the central graben segment forming a releasing bend during the early miocene aquitanian a major reorientation of the regional stress field is held responsible for the main subsidence phase of the northern parts of the upper rhine graben this is reflected by a counterclockwise rotation and northeastward shift of the depocenter axis and later by the middle miocene uplift and erosion of the southern parts of the upper rhine graben during the plio quaternary the upper rhine graben was reactivated as a sinistral strike slip system with the central graben segment forming a restraining bend

retrodeformation of the southern upper rhine graben new insights on continental oblique rifting abstract surface flattening retrodeformations of the southern upper rhine graben urg are presented in this paper the two models presented cover the southwestern and southeastern parts of the urg colmar france and freiburg germany areas respectively results from these models indicate that the urg resulted from a sinistrally oblique extension for a significant part of the rifting early extension was along a nearly e w i e orthogonal direction and concentrated on the main border faults deformation then propagated toward the graben interior as stretching direction rotated counter clockwise of 20 40 systematic along strike variation of cumulated heave throw and slip is also shown it is suggested that this along strike variation of fault displacement could be a characteristic feature of oblique continental rifting in general offset analyses of selected geological horizons indicate that some fault segments vosgian fault near selestat france were possibly active prior to deposition of early tertiary sediments finally close spatial coincidence between major fault segments and recent earthquakes hypocenters indicates that part of the fault system at least in the freiburg area is still active

the south western black forest and the upper rhine graben main border fault thermal history and hydrothermal fluid flow the thermal history of the south westernmost black forest germany and the adjacent upper rhine graben were constrained by a combination of apatite and zircon fission track ft and microstructural analyses after intrusion of palaeozoic granitic plutons in the black forest the thermal regime of the studied area re equilibrated during the late permian and the mesozoic interrupted by enhanced hydrothermal activity during the jurassic at the eastern flank of the upper rhine graben along the main border fault the analysed samples show microstructural characteristics related to repeated tectonic and hydrothermal activities the integration of microstructural observations of the cataclastic fault gouge with the ft data identifies the existence of repeated tectonic related fluid flow events characterised by different thermal conditions the older took place during the variscan and or mesozoic time at temperatures lower than 280 c whereas the younger was probably contemporary with the cenozoic rifting of the upper rhine graben at temperatures not higher than 150 c

post variscan evolution of the lithosphere in the rhine graben area constraints from subsidence modelling in the area of the cenozoic rhine rift system crustal and lithospheric thicknesses range between 24 and 35 km and 60 and 120 km respectively this rift system transects the deeply truncated variscan orogen and superimposed permo carboniferous wrench induced troughs and late permian and mesozoic thermal sag basins at the time of its westphlian consolidation the variscan orogen was probably characterized by 45 60 km deep crustal roots that were associated with its rheno hercynian saxo thuringian saxo thuringian bohemian and bohemian moldanubian sutures all of which are transected by the cenozoic rhine rift system during the stephanian early permian wrench induced disruption of the variscan orogen subducted lithospheric slabs were detached causing upwelling of hot mantle material during the resulting thermal surge partial delamination and or thermal thinning of the continental mantle lithosphere induced regional uplift at the same time the variscan orogenic roots were destroyed and crustal thicknesses reduced to 28 35 km in response to the combined effects of mantle derived melts interacting with the lower crust regional erosional unroofing of the crust and on a more local scale by its mechanical stretching towards the end of the early permian the potential temperature of the asthenosphere returned to ambient levels with this regional long term thermal subsidence of the lithosphere commenced controlling the development of a new system of late permian and mesozoic thermal sag basins however the evolution of these basins was repeatedly overprinted by minor short term subsidence accelerations that reflect the build up of far field stresses related to rifting in the tethyan and atlantic domains comparison of observed and modelled subsidence curves suggests that in the area of the rhine rift system the lithosphere had equilibrated with the asthenosphere at the end of the cretaceous at depths of 100 120 km before it became thermally destabilized again by cenozoic rifting and plume related magmatism modelled subsidence curves indicate that by the end of early permian times the thermal thickness of the remnant mantle lithosphere ranged between 10 and 50 km in areas that were later incorporated into mesozoic thermal sag basins this corresponds to mid permian thermal lithosphere thicknesses of 40 80 km the geological society of london 2004

plate interactions at the southern end of the rhine graben abstract the southern end of the rhine graben in the basel area originated in the early tertiary as an extensional structure it is the site of a transfer zone that connected the rhine graben with the bresse rhone grabens this transfer zone is located in an area into which a late paleozic trough projects which apparently was reactivated from the beginning of miocene to recent times three distinct phases of slight compression were superimposed on the southern end of the rhine graben the first one in the aquitanian early burdigalian is coeval with the development of the helvetic nappes and the insubric fault zone in the alps the second one in the langhian tortonian interval occurred when the external massifs and an important part of the lombardic fold thrust belt in the southern alps developed and the third pliocene to recent one is contemporaneous with the inactivation of this belt and its incorporation into the foredeep of the northern apennines in the aquitanian the forebulge of the alpine orogen is recognizable as a system of flexures that developed preferably on the margin of the late paleozoic trough the middle late miocene one gave rise to uplift of the black forest vosges domain and a river system flowing from this high to the south in the pliocene to recent one alpine rivers made their appearance flowing first to the west into the rhone system and then as the rhine to the north the pliocene to recent phase seems to be decoupled from the body of the central and southern alps

seasonal wetland carbonate sequences and dynamic catenas a re appraisal of palustrine limestones abstract palustrine carbonate cyclothems are compared directly to well documented peritidal carbonate cyclothems in the case of the latter the trend of increasing degree of exposure seen vertically through a cyclothem has been interpreted as due to the aggradation of the sediment surface relative to the semi diurnal tidal regime palustrine cyclothems also show similar increases in the degree of exposure and this is interpreted as the effect of sediment aggradation in a seasonal wetland regime the resulting changes in the drainage characteristic revealed in a palustrinc cyclothem reflect a type of seasonally variable catenary relationship referred to here as a dynamic catena this model explains the key features of palustrine cyclothems and suggests the importance of seasonal wetland environments in ancient continental settings

simultaneous normal faulting and extensional flexuring during rifting an example from the southernmost upper rhine graben the southern end of the upper rhine graben urg is formed by a major continental transfer zone which was localised by the reactivation of ene oriented basement faults of late palaeozoic origin a combination of subcrop data derived from exploration wells and reflection seismic lines and palaeostress analysis provided new constraints on the timing and kinematics of interacting basement faults rifting in the southern urg began in the upper priabonian under regional wnw ese directed extension oriented roughly perpendicular to the graben axis in the study area this led to the formation of nne trending half grabens simultaneously ene trending basement faults situated in the area of the future rhine bresse transfer zone rbtz were reactivated in a sinistrally transtensive mode in the sedimentary cover the strike slip component was accommodated by the development of en echelon aligned extensional flexures flexuring and interference between the differently oriented basement faults imposed additional but locally confined extension in the sedimentary cover which deviated by as much as 90 from the regional wnw ese extension the interference of regional and local stresses led to a regime approaching radial extension at the intersection between the urg and rbtz

lithospheric necking and regional isostasy at extensional basins 2 stress induced vertical motions and relative sea level changes we investigate long wavelength differential vertical motions at extensional basins which are the result of temporal changes in the intraplate stress field in the lithosphere these stress induced vertical motions are intimately coupled to the state of flexure flexural curvature of the lithosphere we compare a previous model of flexure under the sediment load only fsl model and a recent more consistent model which incorporates regional compensation of other vertical loads induced by lithospheric extension as well these additional loads are controlled by the depth at which the necking of the lithosphere occurs don model tlie fsl model and models assuming a shallow level of necking 15 km are very similar they predict tilting of the basin with the hinge point landward of the shelf edge compression results in uplift of the landward pan of the basin which generally corresponds to the coastal plain or inner to middle shelf and downwarping of the outer shelf and slope the differential vertical motions correspond to relative sea level cycles which are out of phase in different parts of the basin internal architecture of systems tracts can be different from predictions by eustasy by contrast deeper levels of necking 20 km predict a uniform sense of motion landward of the shelf edge type i sequence boundaries can be very easily induced for these conditions and sequence stratigraphie features are probably hard to distinguish from predictions by eustasy these results are for a pure elastic plate rheology stress induced vertical motions for a more realistic depth dependent rheology are more complicated because of the additional effect of stress induced reduction of flexural rigidity for these conditions gradual buildup of tension causes a complete relative sea level cycle for high tensional stress levels total vertical motions become rather similar to vertical motions for compression this may be of importance for the issue of global synchroneity of relative sea level changes

the role of precursory structures on tertiary deformation in the black forest hegau region structural inheritance of preexisting crustal discontinuities is widely accepted to have played a crucial role during the cenozoic tectonic evolution of the northern alpine foreland it is recognised as a process that can strongly influence local fault kinematics and strain patterns the case study presented herein is dedicated to the tectonic analysis of the freiburg bonndorf bodensee fault zone fbbfz located at the external margin of the northern alpine molasse basin and extending into the crystalline black forest massif the structure and kinematics of this crustal scale fault zone are investigated by means of a regional analysis of locally mapped faults kinematic analysis of outcrop scale fractures and slip vector modelling the exceptional possibility of analysing the fault zone exposed from basement to cover allowed for an evaluation of interaction between precursory structures and subsequent deformation features the results of this study show that the crystalline basement structures exposed along the fbbfz had a strong imprint on the map scale fault pattern observable in the mesozoic and tertiary sequences kinematic analysis of outcrop scale fracture systems in the latter units yields evidence for local multi directional extension and strike slip faulting during miocene to recent times while these observations may evoke the interpretation of a multistage palaeostress history along the fbbfz slip vector modelling of a very well exposed fbbfz segment suggests that the various strain records can alternatively be explained by one single regional stress tensor and be related to superordinate deep seated strike slip deformation

deep crustal structure of the rhine graben from dekorp ecors seismic reflection data a summary abstract results of two deep reflection seismic lines crossing the northern and southern part of the rhine graben which were recorded in 1988 by the french ecors and the german dekorp teams indicate that the asymmetry of this rift persists to the base of the crust the brittle ductile transition zone approximately coincides with the top of the lower crust ductile shear zones appear to affect the crust mantle boundary upper crustal extension by faulting accounts for a divergence of the graben flanks by 5 7 km whereas the crustal configuration of the rhine graben suggest an extension value of some 17 km

transfer faults and pull apart model in the rhinegraben from analysis of multisource data from analysis of gravimetric data comparisons of levelings seismic profiling paleostress analysis and seismicity together with remotely sensed and morphological data the rhinegraben may be divided into several rhomb shaped basins separated by ene trending basement highs these data express neotectonic movements and slight spatial differences in the subsidence rate these basins are asymmetrical on one side they are bounded by a large several kilometers of vertical throw normal fault zone on the opposite side there is a megaflexure cut by smaller normal faults shaping tilted blocks since the middle miocene extensional directions are subparallel to the ene trending basement highs that consequently may be interpreted as strike slip fault zones of transfer type across the erstein basement high there is a reversal in the rift asymmetry major bordering fault on the western side to the south on the eastern side to the north when considered in the context of the west european rift the rhinegraben is interpreted in terms of a pull apart depression formed during the horizontal movement of blocks guided by large ene trending transcurrent faults the normal faults that are curved shaped in map view may mark the boundaries between areas where the maximum component 1 of the paleostress field developed in pull apart patterns was changing from horizontal to vertical

paleogeography of the upper rhine graben urg and the swiss molasse basin smb from eocene to pliocene twenty paleogeographic maps are presented for middle eocene lutetian to late pliocene times according to the stratigraphical data given in the companion paper by berger et al this volume following a first lacustrine continental sedimentation during the middle eocene two and locally three rupelian transgressive events were identified with the first corresponding with the early rupelian middle pechelbronn beds and the second and third with the late rupelian serie grise fischschiefer and equivalents during the early rupelian middle pechelbronn beds a connection between north sea and urg is clearly demonstrated but a general connection between north sea urg and paratethys via the alpine sea is proposed but not proved during the late rupelian whereas in the southern urg a major hiatus spans early aquitanian to pliocene times early and middle miocene marine brackish and freshwater facies occur in the northern urg and in the molasse basin omm osm however no marine connections between these basins could be demonstrated during this time after the deposition of the molasse series a very complex drainage pattern developed during the late miocene and pliocene with a clear connection to the bresse graben during the piacenzian sundgau gravels during the late miocene pliocene and quaternary sedimentation persisted in the northern urg with hardly any interruptions the present drainage pattern of the rhine river from alpine area to the lower rhine embayment was not established before the early pleistocene

origin of deformed halite hopper crystals pseudomorphic anhydrite cubes and polyhalite in alpine evaporites austria germany the alpine haselgebirge formation represents an upper permian to lower triassic evaporitic rift succession of the northern calcareous alps eastern alps although the rocksalt body deposits are highly tectonised consisting mainly of protocataclasites and mylonites of halite and mudrock the early diagenetic history can be established from non tectonised mudrock bodies cm sized euhedral halite hopper crystals formed as displacive cubes within mud just during shallow burial the crystals were deformed by subsequent compaction later migrating fluids led to the replacement of halite by anhydrite retaining the shapes of deformed halite cubes polyhalite formed from subsequent enhanced fluid migration mudrock provided water by dewatering while potassium and magnesium were dissolved from primary salt minerals when these fluids interacted with sulphates polyhalite precipitated 40ar 39ar analyses date the polyhalite from within the retaining shapes of deformed halite hopper shaped cubes from two localities to ca 235 232 ma middle triassic at this time ca 20 25 ma after sedimentation polyhalite crystallised at shallow levels