cadomian terranes wrench faulting and thrusting in the central europe variscides geophysical and geological evidence sixty five per cent of the paleozoic basement of western and central europe is hidden by a sedimen tary cover and or sea this work aims to remove that blanket to detect new structures which could used to build a more comprehensive model of the variscan or ogeny it is based on the interpretation of various forms of data a published gravity maps corrected for the ef fects of the crust mantle boundary topography and light sedimentary basins b aeromagnetic maps c measurements of densities and d induced and rema nent magnetizations on rocks from paleozoic outcrops of the upper rhenish area from the northern b ohem ian massif to the eastern paris basin the saxothurin gian is characterized by a 500 km long belt of gravity highs the most important being the kraichgau high most of the corresponding heavy bodies are buried un der a post early visdan cover they are interpreted as relics of late proterozoic terranes overlain by an early to middle paleozoic sequence equivalent to the bo hemian t errane in the bohemian massif the most probable continuation of these dense bohemian ter ranes toward the west is the southern channel north ern brittany cadomian terrane the gravity lows are correlated with variscan granites and pre and early variscan metagranites gravity and magnetic maps demonstrate large scale displacement in devonian early carboniferous times along the parallel and equidistant nw se striking vistula elbe bavarian bray and south armorican dextral wrench faults in the vosges schwarzwald and central massif the faults continue with the east west striking lalaye lubine ba den baden and marche faults and with south vergent thrusts the bavarian faults shift the kraichgau terrane by 150 km relative to the bohemian terrane whereas the offset of the north ern brittany cadomian relative to the northern vosges kraichgau terranes is estimated at 400km along the bray fault sinistral wrench faults are the ne sw striking sillon houiller rheingraben rodl vitis and diendorf faults the southern vosges schwarzwald devonian dinanti an basin is interpreted as a pull apart basin at the south easterly extremity of the bray fault the bohemian and kraichgau body form allochthonous terranes which were thrust over the saxothuringian crust thrusting to the north west was accompanied by back thrusting and led to the forma tion of pop up structures contemporaneous dextral and sinistral wrench faulting resulted in transpressive strain during collision the zonal structure of the varis cides in the sense of kossmat 1927 is relevant only to the rhenohercynian foreland belt kossmat 1927 al ready spoke of a moldanubian region because it dis plays no real zonal structure the saxothuringian zone was formed by terrane accretion their apparent zonal structure is not a pre collisional feature but only the result of accretion and collision

stress regime strain release and geothermal implicationsregional stress field and rifting in western europe in situ stress determination is one possibility to determine stress magnitudes in the earth s crust most measurements especially in the northern alpine foreland have been carried out by using the doorstopper technique stress magnitudes are presented as excess stresses a number of sites where stresses have been determined gave sufficiently high values to statistically determine stress directions for the following tectonic blocks 1 1 western alps 2 2 their immediate foreland with the rhinegraben and 3 3 the rhenish shield bordering on the rift segment of the lower rhine embayment in discussing results of the statistical analyses of stress data it is suggested that stresses measured in the western alps have mainly a topographic origin in the alpine foreland to the north of the rhenish shield topographic stresses are superimposed on active tectonic stress considering the structural and lithological differences the foreland blocks show a different response to the same tectonic stress field which trends for 1 at about 146 this active stress field causes shear rifting in the upper rhinegraben but extensional rifting in the lower rhine embayment in the rhenish shield area only local step faults are observed in direction of 1 due to the ductile behaviour of its basement

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

the continental rift system of the rhinegraben structure physical properties and dynamical processes abstract the geophysical investigation of the continental rift system of the rhinegraben by various methods has progressed to such a stage that details of structure physical properties and seismic activity and relations between these features can be recognised differences in the nature of the crust mantle boundary inside and outside the graben proper seem to be a typical property of continental rifts asymmetries of structure seismic activity temperature in the crust and physical properties in the lithosphere are an important clue to the understanding of rift dynamics these asymmetries indicate that the formation of the rift cannot be explained by the updoming of an asthenolith alone but that taphrogenesis took place in the foreland of the continent continent collision in the alpine mediterranean zone a number of future key experiments is proposed

rhinegraben horizontal stylolites indicating stress regimes of earlier stages of rifting abstract buchner f 1981 rhinegraben horizontal stylolites indicating stress regimes of earlier stages of rifting in j h illies editor mechanism of graben formation tectonophysics 73 113 118 tectonic stylolites horizontal columns and their statistical distribution in middle triassic and jurassic limestones on both flanks of the rhinegraben are described and their relation to the rhinegraben taphrogenesis is discussed a generation of pre middle miocene nne striking horizontal stylolites and a subsequent generation of post lower miocene nw striking horizontal stylolites have been recognized the first generation stylolites indicates a horizontal compression in the nne ssw direction while the second generation indicates a compression in the nw se direction average maxima of joints parallel to the two horizontal stylolite maxima were found joints and their corresponding horizontal stylolites were formed under the same stress regime

palaeostress analysis a contribution to the understanding of basin tectonics and geodynamic evolution example of the permian cenozoic tectonics of great britain and geodynamic implications in western europe abstract microtectonic analysis in association with tectonic sedimentological observations enables us not only to define palaeostress tensors but also to date each of them such a study carried out in central and northeastern england and in southernmost wales has permitted us to point out several tectonic stages during the permian cenozoic period 1 inferred from syn sedimentary faulting in the late permian series the permian early triassic tectonic regime is characterised by a nnw sse oriented extension 2 during the late triassic to the early late jurassic an e w to ene wsw oriented extension was acting as suggested by syn sedimentary normal faulting in keuper lias and middle dogger sediments and post sedimentary normal faulting in oxfordian sediments 3 the following tectonic event probably started during the malm and was particularly active during the early cretaceous it was characterised by a n s to nne ssw oriented extension and was associated with an e w to wnw ese oriented strike slip tectonic regime transtension 4 a locally observed nw se oriented transpressional strike slip tectonic regime is thought to correspond to the laramide inversion phase of the middle paleocene 5 the later tectonic event is characterised by a n s oriented transpressional strike slip regime and affects a paleocene tholeiitic dyke cleveland dyke it is supposed to be synchronous with the so called eocene pyrenean to the early miocene helvetic compressional stages these paleostress tensors are compared with others defined in france the benelux countries and germany and are also collated to the tectonic evolution of oil basins assessed from geophysical analyses these comparisons raise discussions about the paleostress distribution within the geodynamic evolution of the west european shelf

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

reaction enhanced ductility the role of solid solid univariant reactions in deformation of the crust and mantle abstract in collision belts and subduction zones penetrative deformation of thrust sheets may be catalyzed by metamorphic reactions if the reactions have a significant effect on the mechanical properties of rocks reaction enhanced ductility may result if a reaction produces a significant decrease in grain size thus allowing the rock to deform superplastically the product grain size of a reaction is a function of the ratio of nucleation and growth rates this ratio varies along any pressure temperature time ptt path and only attains a significant value at a certain distance from an equilibrium boundary a comparison of rates of change of p and t along typical segments of ptt paths for crustal rocks leads to the conclusion that a high nucleation rate a small grain size and resulting superplastic deformation are more likely to be achieved when reaction boundaries are crossed during underthrusting rather than during the thermal readjustments of a perturbed geotherm following crustal thickening or during uplift an example of reaction enhanced ductility occurs in eclogite facies metagranitoids in the sesia lanzo zone western alps where medium grained plagioclase reacted to fine grained jadeite quartz during early alpine underthrusting microstructural evidence from shear zones shows that the jadeite quartz aggregates were highly ductile and it is inferred that the small grain size allowed superplastic deformation further evidence suggests that this process operated during regional deformation of metagranitoids rubie 1982 the reaction of olivine to spinel or the beta phase by metastable overstepping of the two phase stability fields in a subducting plate ringwood 1975 may result in fine grained products and thus may be analogous to the albite jadeite quartz reaction the consequent decrease in effective viscosity is likely to have important consequences for plate dynamics at and below the depths of major phase transitions

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

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

crustal shear zones and thrust belts their geometry and continuity in central africa the precambrian orogenic belts of africa are often defined by ductile shear zones which developed in response to large displacements and which mark orogenic fronts between mobile and stable parts of the crust they are thought to represent the major crustal reflectors seen by seismic reflection profiling in younger orogenic belts these orogenic fronts are connected by shear zones that transfer displacement or accommodate different displacements between orogenic segments smaller shears within an orogenic belt occur as a result of differential movements these shear zones are seen to pass from flat lying to steep structures and may have a thrust or strike slip sense they compare with the staircase trajectories characteristic of foreland thrust belts in common with thrust belts the geometry of the shear zones can be used to estimate displacement direction as can regional extensional fabrics developed in the associated high strain tectonites central africa has been previously described as a complex network of late proterozoic mobile belts the recognition of similar displacements and time equivalence in these belts allows their reinterpretation in terms of a linked thrust and strike slip shear zone system an example is the damaran lufilian zambezi and ukingan system these orogenic belts share a similar displacement picture and broad time equivalence and were apparently linked in a lower crustal shear zone of continental dimensions this shear zone system appears to have developed under a single tectonic framework

evolution of the stress field pattern in the south of the rhine graben from the eocene to the present a stress field evolution from the eocene to the present is proposed for the southern part of the rhine graben stress tensor determinations are supported by striated microfaults and calcite twin lamellae analyses both methods lead to the determination of 1 a an e w extension contemporaneous with the opening of the graben and 2 b a n s compressive event which may be related with alpine tectonics it is shown that a n s compressive event occurred prior to the oligocene extension a permutation between the 1 and 2 axes is proposed to explain the transition between compression and extension a 1 2 inversion during the oligocene is compatible with compression in the southern part of the rhine graben infilling horizontal 1 and extension vertical 1 more to the north during the miocene the jura emplacement corresponds to a n s compression in this area there is no significant variation of the 1 direction south of the rhine graben from the eocene to the late miocene the 1 direction only turns to a n140 direction during the pliocene or the quaternary

on the nonlinear helmholtz response of almost enclosed tidal basins with sloping bottoms short relatively deep tidal basins which are connected to the open sea by a narrow strait may exhibit either an amplified resonant or damped choked response to the tide at the entrance here particular attention is given to the lowest mode of response which is the helmholtz or pumping mode for which the sea level within the basin executes a spatially uniform oscillation when the basin s sidewalls slope the restoring process of this oscillator is nonlinear possible consequences of this nonlinearity are that the basin may exhibit either long lasting high waters and short peaked low waters or long term regular modulation of its tidal amplitude or a chaotic modulation of its tidal amplitude or bent resonance horns implying that resonant and choked tidal responses may exist simultaneously for the same parameter regime related field observations will be discussed

crustal velocity field of western europe from permanent gps array solutions 1996 2001 we derive a new geodetic velocity field for western europe and the western mediterranean by rigorously combining 1 a selection of 36 itrf2000 sites 2 a solution from a subset of sites of the european permanent gps network euref epn 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy of the order of i mm yr 1 or better its analysis shows that central europe defined as east of the rhine graben and north of the alps and the carpathians behaves rigidly at a 0 4 mm yr 1 level and defines a stable europe reference frame in that reference frame we find no significant motion at sites located west of the rhine graben and on the iberian peninsula which sets an upper bound of 0 6 mm yr 1 on horizontal motion across the rhine graben and the pyrenees we find that the current strain pattern in the western alps combines e w extension and right lateral shear we confirm a counterclockwise rotation of the adriatic microplate which appears to control the strain pattern along its boundaries in the friuli area the alps and the apennines our results also suggest that the africa eurasia plate motion in the western mediterranean may be 40 50 per cent slower that the nuvel1a plate motion model and rotated 20 30 counterclockwise

the role of transiently fine grained reaction products in syntectonic metamorphism natural and experimental examples it is proposed that one of the most important mechanisms of interrelationship between deformation and metamorphism is the facilitation of one of several grain size sensitive deformation mechanisms resulting from the formation of fine grained products of a metamorphic reaction during prograde metamorphism such effects are likely to be transient because grain coarsening and textural equilibration are likely in response to rising temperature conditions thus deformation mechanisms are often difficult to infer from such naturally deformed rocks in localized shear zones exhibiting retrogressive metamorphism evidence of enhanced deformability by such mechanisms is most likely to be preserved because cooling conditions inhibit grain growth and both deformed and undeformed rocks are likely to be preserved an experimental study has been made of the effects of deformation on serpentinite under conditions of progressive dehydration but with controlled pore pressure a marked weakening near linear viscous rheol

simulation of foreland basin stratigraphy using a diffusion model of mountain belt uplift and erosion an example from the central alps switzerland foreland basin stratigraphy can be considered as the result of three interacting processes thrust deformation which builds the tectonic load sedimentary and erosional processes which redistribute that load and the flexural response of the lithosphere the resultant stratigraphy of foreland basins is commonly composed of a small number of shallowing and coarsening upward cycles bounded by regional unconformities to understand the development of these unconformities we present a simple model of these three processes coupling an evolving thrust wedge on a linear elastic plate with erosion and sedimentation defined by the diffusion equation applied to topography our model demonstrates the development of regional unconformities without recourse to either eustasy or complex viscoelastic models for the continental lithosphere the model describes the thrust wedge foreland basin system in terms of four parameters 1 the effective elastic thickness of the foreland plate te 2 the sediment transport coefficient k 3 the thrust wedge advance rate 4 the surface slope of the thrust wedge the model is applied to the oligocene miocene north alpine foreland basin nafb of eastern switzerland the stratigraphy of the nafb can be simplified into two large scale shallowing upward cycles separated by an unconformity at the base of the burdigalian 22 ma geological information is taken from the nafb to estimate suitable values for the parameters listed above assuming a linear elastic lithospheric rheology the te value is estimated at 10 5 km from decompacted sediment columns data to constrain the sequential development of the thrust wedge come from structural geology the early stages 40 24 ma of compression involved a relatively low angle thrust wedge with an advance rate of approximately 2 4 mm yr at about 24 ma the wedge advance slowed down and thickened by underplating crystalline basement of the foreland plate the value for the transport coefficient has been estimated from previous studies prior to attempting to simulate the broad scale geometry of the nafb the role of each parameter was assessed individually the values for te and k are held constant throughout the simulation of the nafb at 7 5 km and 500 m yr respectively the geometry of the base burdigalian unconformity is reproduced by variations in the parameters describing the thrust wedge the surface slope angle of the wedge is increased from 2 5 to 4 over 0 2 m y and the rate of thrust advance is decreased from 2 mm yr to 0 2 mm yr during the thickening event between 24 and 23 8 ma the rejuvenation of the internal parts of the thrust load causes backtilting of the foreland basin sediments and after a time lag erosion of the distal stratigraphy over the forebulge so simulating the base burdigalian unconformity

on the origin of the southern permian basin central europe abstract a detailed study of the structural and stratigraphic evolution of the southern permian basin during latest carboniferous to early jurassic times supported by quantitative subsidence analyses and forward basin modelling for 25 wells leads us to modify the conventional model for the rotliegend zechstein development of this basin the late permian early jurassic tectonic subsidence curves are typical for a permian to early triassic extensional stage that is followed by thermal subsidence however a purely extensional model is extremely problematic because active faulting during this time is minor and generally hard to document using inverse techniques to model the subsidence curves we quantitatively show that a significant component of late permian and triassic tectonic subsidence can be explained by thermal relaxation of early permian lithospheric thinning and by delayed infilling of paleo topographic depressions that developed during the early permian in this interpretation stephanian autunian wrenching resulted in thermal destabilisation of the lithosphere deep fracturing of the crust disruption and erosion of its sedimentary cover and regional uplift of the area of the future southern permian basin upon termination of wrench tectonics and associated volcanism towards the end of the autunian the southern permian basin began to subside in response to thermal contraction of the lithosphere the evolving basin was isolated from the world oceans and had subsided possibly up to some 700 m below their level at the beginning of upper rotliegend sedimentation after catastrophic flooding of this paleo topographic depression at the beginning of the zechstein changing sea level sedimentation and subsidence rates remained essentially in balance although the effects of triassic rifting overprinted parts of the southern permian basin its overall subsidence pattern persisted well into the jurassic in contrast to the remainder of the southern permian basin permian and triassic crustal extension contributed significantly to the subsidence of the polish trough

origin of granulite terranes and the formation of the lowermost continental crust differences in composition and pressures of equilibration between exposed regional granulite terranes and suites of granulite xenoliths of crustal origin indicate that granulite terranes do not represent exhumed lowermost crust as had been thought but rather middle and lower middle crustal levels application of well calibrated barometers indicate that exposed granulites record equilibration pressures of 0 6 to 0 8 gigapascal 20 to 30 kilometers depth of burial whereas granulite xenoliths which also tend to be more mafic record pressures of at least 1 0 to 1 5 gigapascals 35 to 50 kilometers depth of burial thickening of the crust by the crystallization of mafic magmas at the crust mantle boundary may account for both the formation of regional granulite terranes at shallower depths and the formation of deep seated mafic crust represented by many xenolith suites

evidence for deformation induced k feldspar replacement by myrmekite several examples of deformation induced myrmekite have been found in two amphibolite facies mylonites derived from granitic protoliths namely a muscovite poor s c mylonite and a single foliation muscovite poor mylonitic gneiss back scattered sem and conventional optical microscopy show that in both rock types syntectonic myrmekitic intergrowths of oligoclase and quartz formed on the two sides of k feldspar grains that faced the local inferred incremental shortening direction for the mylonite myrmekite does not occur on the two ends of the grain that faced the incremental stretching direction the replacement of k feldspar by plagioclase and quartz results in a volume decrease and is favoured on high normal stress sites around the grains we suggest that the ambient temperature pressure and chemical activities were such that the replacement reaction was favoured but the addition of extra strain energy along the high pressure sides of the grains localized the reaction at these sites this energy could arise from elastic strain or strain associated with tangled dislocations or twin boundaries the relative roles of stress and strain energy concentrations in driving the replacement reaction are not known but both were probably important

characterization of organic rich material in an evaporitic environment the lower oligocene of the mulhouse basin alsace france evaporitic sediments from the max borehole mulhouse potash basin southern rhine graben were studied over an interval of about 40 m in the vicinity of sylvite beds total organic carbon toc analyses of 450 samples showed that marly layers interbedded within the evaporites have toc values that fluctuate in a rhythmic manner the highest values are found near the top of the clay anhydrite layers and the lowest values are recorded near the top of the halite rich beds geochemical elemental analysis of kerogen gas chromatography of bitumen and palynological studies of 26 samples showed that the organic matter is mainly of algal origin a and b groups a third category of organic material c group may have been derived from a mixture of continental supply and in situ bacterial productivity

lithospheric cross sections of the european cenozoic rift system abstract the lithospheric structure of the european cenozoic rift system ecris is presented in transects through the southern rhine graben and the rhenish massif hessen depression emphasizing the geophysical structure of the lithosphere based on seismic refraction reflection investigations teleseismic tomography electromagnetic depth sounding models and gravity aeromagnetic earthquake uplift subsidence and heat flow data the rift is clearly expressed in the rhine graben but is not evident at the surface in the area of the rhenish massif where its existence is indicated by seismicity it is characterized by abnormal crustal and upper mantle structures which vary considerably in horizontal direction for example under the rhine graben the crust is thinned to 25 km but at 40 km depth anomalously high velocities are observed in contrast beneath the rhenish massif the crust is thickened to 35 37 km and under its eastern part a high velocity thin upper mantle slice is seen at 30 km depth within the lower crust which towards the hessen depression is gradually replaced by normal variscan mantle with the moho near 30 km depth under the western part of the rhenish massif p and s wave velocities are reduced below 50 km depth which is not seen east of the rhine river under the rhine graben the existence of a low velocity upper mantle above 100 km cannot be generalized but is restricted to confined regions

inversion of the broad fourteens basin offshore netherlands a small scale model investigation abstract the southern north sea exhibits spectacular examples of graben inversion which have been extensively documented by oil industry exploration the broad fourteens basin which is located at the southern limit of the southern permian salt basin displays numerous structural patterns of positive inversion which are related to the inversion which are related to the presence and thickness of zechstein salts in the northern part of the broad fourteens basin the zechstein salt is rather thick 500 m allowing decollement of the mesozoic series during both extension and compression salt is missing to the southern part of this graben and both mesozoic series and palaeozoic basement display similar patterns of deformatiqn the mechanical significance of inversion patterns was investigated through laboratory experiments on brittleductile models models were built with sand and silicone putty that represent respectively the frictional behaviour of the mesozoic cover as well as the palaeozoic basement and the viscous behaviour of a decollement layer mainly composed of zechstein salts which is intercalated between them the models were scaled to fit natural configurations observed in the broad fourteens basin all small scale experiments were carried out in two steps 1 graben formation with synkinematic sedimentation and 2 compression at various angles of obliquity to the graben experimental results show that the structures generated by or reactivated during inversion are strongly dependent on a the strength of the decollement layer which is a function of the layer thickness and of the displacement velocity applied at the model boundaries and b the strength of the sedimentary overburden which is a function only of its thickness for a given lithology reactivation of normal faults occurs when the angle between the compression and the direction of the normal faults is smaller than 45 the ductile layer which can be a source for diapirs during extension plays during compression an important ro1e in the thrusting of the graben fill onto the adjacent platforms

replacement of pyroxene by hornblende isochemically balanced with replacement of plagioclase by garnet in a metagabbro of upper amphibolite grade in a garnet clinopyroxene hornblende metagabbro from the archean basement north of the cape smith wakeham bay belt quebec canada the following major mineral reactions have been observed 1 clinopyroxene hornblende and 2 plagioclase hornblende or fe ti oxides garnet it is argued that these reactions are synchronous and form part of one solid solution reaction system h2o cpx hbl plag fe ti oxides grt cpx hbl plag fe ti oxides qtz a new petrological mixing method is described which starting from the present reaction products estimates the proportions and compositions of the reactants for which the reaction system is completely isochemical the reaction system also explains the observed hornblende quartz symplectic intergrowths and the abundance of ilmeno hematite the isochemical character could also hold for the h2o involved the reaction is probably an adjustment to increasing pressure combined with cooling and can be correlated with the metamorphic peak of the hudsonian metamorphic episode

seismic reflectivity of mylonite zones in the crust deep fault zones are characterized by mylonitic rocks with strong preferred orientation of constituent minerals and retrograde mineral assemblages sonic velocities are consequently lower for propagation directions normal to mylonite foliation than in surrounding unmylonitized rocks synthetic seismograms computed for low velocity near horizontal thick mylonite zones of complex laminated geometry show multicyclic reflections with amplitudes up to twice those generated by a single interface seismic characteristics of mylonite zones are sufficient to produce reflections in crystalline rocks provided noise levels are relatively low

recent surface displacements in the upper rhine graben preliminary results from geodetic networks abstract datasets of the gnss upper rhine graben network gurn and the national levelling networks in germany france and switzerland are investigated with respect to current surface displacements in the upper rhine graben urg area gurn consists of about 80 permanent gnss global navigation satellite systems stations the terrestrial levelling network comprises 1st and 2nd order levelling lines that have been remeasured at intervals of roughly 25 years starting in 1922 compared to earlier studies national institutions and private companies made available raw data allowing for consistent solutions for the urg region we focussed on the southern and eastern parts of the investigation area our preliminary results show that the levelling and gnss datasets are sensitive to resolve small surface displacement rates down to an order of magnitude of 0 2 mm a and 0 4 mm a respectively the observed horizontal velocity components for a test region south of strasbourg obtained from gnss coordinate time series vary around 0 5 mm a the results are in general agreement with interseismic strain built up in a sinistral strike slip regime since the accuracy of the gnss derived vertical component is insufficient data of precise levelling networks is used to determine vertical displacement rates more than 75 of the vertical rates obtained from a kinematic adjustment of 1st order levelling lines in the eastern part of urg vary between 0 2 mm a and 0 2 mm a indicating that this region behaves stable higher rates up to 0 5 mm a in a limited region south of freiburg are in general agreement with active faulting we conclude that both networks deliver stable results that reflect real surface movements in the urg area we note however that geodetically observed surface displacements generally result from a superposition of different effects and that a separation in tectonic and non tectonic processes needs additional information and expertise

the reaction garnet clinopyroxene quartz 2 orthopyroxene anorthite a potential geobarometer for granulites a mineralogic geobarometer based on the reaction garnet clinopyroxene quartz 2 orthopyroxene anorthite is proposed the geobarometric formulations for the fe and mg end member equilibria are begin gathered p text fe text text bars text 32 text 097 t text text 26385 text 22 text 79 t 848 t1 text n t 848 text hfill text 3 655 0 0138t text left frac text t 848 text text 2 t right hfill text text 3 text 123 t1 text n frac a a text n text plag a text fs text p ddot u text x 2 a text alm text gt a text hed text opx hfill p text mg text bars 9 text 270 t 4006 0 9305 text t 848 t1 text n t 848 text hfill text 1 1963 text text 6 0128 text x 10 text 3 t left frac t 848 2 t right hfill text 3 489 text t1 text n frac a an text plag text a text ens text opx text a text pyr text gt text a text diop text cpx text hfill end gathered the end member thermodynamic data have been taken from the data base of helgeson et al 1978 and saxena and erikson 1983 the activities of pyroxene components and anorthite in plagioclase have been modelled after wood and banno 1973 and newton 1983 respectively the activities of pyrope and almandine are calculated from the binary interaction parameters for garnet solid solutions proposed by saxena and erikson 1983

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

the significance of hiatus beds in shallow water mudstones an example from the middle jurassic of switzerland abstract limestone beds formed in nearly carbonate free shallow water mudstones by discontinuous sedimentation and erosion are called hiatus beds anaerobic oxidation of organic matter by microbes provided excess alkalinity inducing carbonate precipitation a multiphase history of such beds is documented from the swiss jurassic by several cementation and dissolution phases four cement types occur micrite as earliest cement 13c 10 to 20o oo stellate calcite between micrite cemented parts 13c 5 to 10o oo fibrous calcite cement in dissolution cavities 13c 30o oo and blocky calcite in remaining pores 13c 5o oo except for the late blocky cement all cements contain pyrite indicating carbonate precipitation within the sulfate reduction zone after early cementation by micrite the beds moved relatively upwards into a shallower geochemical zone and some even to the seafloor because of erosion cavities formed during reburial by dissolution in the upper part of the sulfate reduction zone and in the upper part of the methanogenic zone strongly reduced sedimentation rates provided the requisite stable geochemical conditions for at least several thousands of years which permitted precipitation and dissolution of carbonate by biochemical processes and diffusion this happened on short lived swells caused by differential subsidence and rotation along listric faults when basement structures became reactivated during the extensional stress regime from opening of the tethys during the jurassic and cretaceous breakup of pangea the shelf area increased and differential subsidence on these newly formed shelves was the main factor responsible for the observed post paleozoic maximum in hiatus beds and hiatus concretions

determination of displacements in the upper rhine graben area from gps and leveling data the upper rhine graben is a north northeast trending rift system which belongs to the european cenozoic rift system today the southern part of the graben is seismically still active earthquakes of magnitude 5 have a recurrence time of approximately 30 years in order to monitor and to determine the displacements in the study area gps measurements have been carried out in two campaigns 1999 and 2000 and observations of the available permanent stations have been processed in 2002 owing to the small size of deformations expected high accuracy requirements must be met by the gps processing in order to achieve these requirements precise antenna modeling has been introduced into the processing as expected the short time span has not enabled to detect significant displacements from the gps measurements the deformation analysis shows that the horizontal displacement rates do not exceed 1 mm year which is compatible with the geological information owing to the fact that the accuracy of positioning with gps for the vertical coordinates is lower than for the horizontal coordinates the determination of vertical displacements has been carried out using the leveling technique in the area of freiburg first order and second order leveling lines have been chosen for the detection of local displacements on the weinstetten on the lehen schonberg and on the main border fault mbf some sections of these faults are still active today significant vertical displacements have been observed at the weinstetten fault in the area of bad krozingen and on the mbf in freiburg the displacement rates 1925 1984 are 0 17 0 01 mm year and 0 25 0 02 mm year respectively the results agree very well with the results of seismotectonic investigations and show that ongoing displacements can be found on the northern part of the lehen schonberg fault in the vicinity of eichstetten and on the mbf in the vicinity of freiburg

the evolution of the south hunsruck and taunus borderzone abstract the main fabric development of the south hunsruck and taunus borderzone htb occurred during late variscan homoaxial backfolding of an early variscan stack of thrust sheets in a narrow wsw ene trending zone several hundred kilometres long rotation and uplift of the southern rhenohercynian zone was accompanied by the subsidence of the southward adjacent northernmost parts of the saxothuringian zone and the development of the saar nahe basin during the latest carboniferous changing stress conditions gave rise to the development of normal faults along the htb and an extensive tholeiitic and rhyolitic volcanism contemporaneous uplift of the hunsruck is reflected by coarse elastics in the saar nahe basin subsequently the htb became covered by latest carboniferous early permian and mesozoic sediments cretaceous uplift of the rhenish shield caused their erosion the faultzone separating the rhenohercynian hunsruck and taunus from the permo carboniferous saar nahe basin is characterised by reverse and normal faults conjugate shear indicated by slickensides on steep oblique fracture planes as well as slight folding and small scale thrusting in post variscan sediments may be attributed to compressional foreland deformation reactivating variscan joint fabrics and fault systems timing of these deformations is ambiguous and could partly be related to dextral shear during the cenozoic subsidence of the rhine graben cenozoic sediments of the upper rhine graben overstep the northeastern parts of the htb seismic investigations indicate that the htb is associated with a system of southeast hading listric planes extending beneath the moho occasional dip slip earthquakes occur along these fractures

numerical modelling of water transport processes in partially connected tidal basins abstract in the paper two types of numerical models a lumped parameter model and a high resolution two dimensional hydrodynamic model are used to analyse the response of a system of partially connected tidal basins to inhomogeneous open sea forcing the equations of the lumped parameter model suitable for an arbitrary number of basins with sloping walls are formulated based on one dimensional continuity and momentum equations numerical solutions to the equations are thoroughly examined showing the influence of inhomogeneous open sea forcing and of geometrical parameters of the basins on the tidal range and the water transport through the system with particular emphasis given to inter basin water exchange and cumulative water transport through basins boundaries the results of the lumped parameter model simulations for the tidal basins of the german wadden sea are successfully compared with the results of calculations with the two dimensional hydrodynamic model which is used to investigate in more detail circulation patterns and the influence of specific local features of inlet bathymetry on the hydrodynamic processes in the study area the influence of wind on the basins response is discussed as well

the origins of granulites a metamorphic perspective although many recent reviews emphasize a uniformity in granulite pressure temperature p t conditions and paths granulites in reality preserve a spectrum of important petrogenetic features which indicate diversity in their modes of formation a thorough survey of over 90 granulite terranes or occurrences reveals that over 50 of them record p t conditions outside the 7 5 1 kbar and 800 50 c average granulite regime preferred by many authors in particular an increasing number of very high temperature 900 1000 c terranes are being recognized both on the basis of distinctive mineral assemblages and geothermobarometry petrogenetic grid and geothermobarometric approaches to the determination and interpretation of p t histories are both evaluated within the context of reaction textures to demonstrate that the large range in p t conditions is indeed real and that both near isothermal decompression itd and near isobaric cooling ibc p t paths are important amphibolite granulite transitions promoted by the passage of co 2 rich fluids as observed in southern india and sri lanka are exceptional and not representative of fluid related processes in the majority of terranes it is considered on the contrary that fluid absent conditions are typical of most granulites at or near the time of their recorded thermal maxima itd granulites are interpreted to have formed in crust thickened by collision with magmatic additions being an important extra heat source erosion alone is not however considered to be the dominant post collisional thinning process instead the itd paths are generated during more rapid thinning 1 2 mm yr exposure related to tectonic exhumation during moderate rate or waning extension ibc granulites may have formed in a variety of settings those which show anticlockwise p t histories are interpreted to have formed in and beneath areas of voluminous magmatic accretion with or without additional crustal extension ibc granulites at shallow levels very rapid 5 mm yr extensional thinning subsequent to collision it is suggested that the preservation of ibc paths rather than itd paths in many granulites is primarily related to the rate and timescale of extensional thinning of thickened crust and that hybrid itd to ibc paths should also be observed most ibc granulites and probably many itd granulites have not been exposed at the earth s surface as a result of the tectonic episodes which produced them but have resided in the middle and lower crust for long periods of time 100 2000 ma following these events the eventual exhumation of most granulite terranes only occur through their incorporation in later tectonic and magmatic events unrelated to their formation

subsidence analysis and modelling of the roer valley graben se netherlands abstract the roer valley graben southeastern netherlands forms the most northern branch of the european cenozoic rift system sedimentary backstripping of exploration wells provides control on vertical tectonic motions during the complex post paleozoic geodynamic evolution of the area the roer valley graben evolved by repeated reactivation of permo carboniferous fracture systems at least three episodes of extension related subsidence are recorded these occurred during the late permian early triassic 255 240 ma the middle jurassic 168 165 ma and the late cenozoic 36 0 ma a late jurassic early cretaceous stretching phase is weakly inferred from incomplete data crustal stretching values calculated from the tectonic subsidence curves can account for the reflection seismic controlled crustal configuration of the roer valley graben area results demonstrate a close relationship between the roer valley graben and the basins in the north sea during the mesozoic in contrast the cenozoic evolution of the roer valley graben is independent from that of the north sea and is related to the development of the rhine graben

deep crustal granulites with migmatitic and mylonitic fabrics from the zambezi belt northeastern zimbabwe abstract high p granulites contained in two allochthonous tectonic units were thrust southwards onto the northern margin of the zimbabwe craton during the pan african zambezi orogeny in the lower sheet the masoso metamorphic suite contains mafic garnet granulite assemblages formed during a high p t metamorphic event although the suite as a whole is predominantly granitic the garnet granulites occur as relicts within narrow mafic layers characterized by migmatitic and mylonitic fabrics the annealed mylonites represent surfaces of deep crustal tectonic imbrication that formed immediately before the pan african orogeny gabbros which intruded the granulites after the main phase of migmatization have formed corona textures that document a low p t metamorphic event at mid crustal levels the style of deformation then changed and the masoso suite with its mylonitic layers was folded and thrusted southwards onto the archaean zimbabwe craton

the upper rhenish shield basement vosges upper rhinegraben and schwarzwald main structural features deduced from magnetic gravimetric and geological data abstract interpretation of magnetic and gravimetric data and correlations with geological observations on outcrops and in boreholes have enabled the construction of a geological sketch map of the pre westphalian basement in the area of the upper rhenish shield the map demonstrates the contrast between the heavy and magnetic saxothuringian characterized by palaeozoic units metamorphosed to varying degrees and intruded by early carboniferous basites and the lighter moldanubian consisting mainly of gneisses and granites geological structures and tectonic features are recorded beneath the mesozoic and cenozoic cover the present picture of the basement is mainly the result of late visean early namurian structural features represented by a linear arrangement of magmatic bodies and the distribution of strike slip and thrust faults the major structural features are the e w vittel lalaye lubine baden baden fault that marks the border between saxothuringian and moldanubian the n35 left lateral wrench fault system running along the present rhinegraben the n60 grain of the northern vosges and the saar basin and the s verging crustal thrusts of moldanubian

surveys on environmental tectonics abstract until now research on neotectonics and related seismicity has mostly focused on active plate boundaries characterized by generally high earthquake activity current seismic hazard estimates for intraplate areas are commonly based on probabilistic analyses of historical and instrumental earthquake data the accuracy of these hazard estimates is limited by the nature of the data e g ambiguous historical sources and by the restriction of available earthquake catalogues to time scales of only few hundred years which are geologically insignificant and not suitable to describe the tectonic processes causing earthquakes this is especially relevant to intraplate regions where faults show slow slip rates resulting in long average recurrence times for large earthquakes 10 3 10 6 yr the alpine orogen and intraplate sedimentary basins and rifts of its northern foreland are associated with a much higher level of neotectonic activity than hitherto assumed seismicity and stress indicator data combined with geodetic and geomorphologic observations demonstrate that the northern alpine foreland is being actively deformed this has major implications for the assessment of their natural hazards and environmental degradation the nw european lithosphere has undergone a polyphase evolution with an intensive interplay of upper mantle thermal perturbations and stress induced intraplate deformation a number of recent findings point to an important role of lithospheric folding in thermally weakened lithosphere of the northwestern european foreland the eu funded interdisciplinary environmental tectonics research network entec addresses relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland its objectives are to quantify the effects of ongoing alpine collision on nw european foreland intraplate deformation and its impact on surface geomorphology and natural hazards three natural laboratories have been selected 1 the lower rhine graben lrg 2 the upper rhine graben urg and 3 the vienna basin vb these three areas record the manifestation of neotectonics within the alpine orogen vb at its front urg and in the far field area lrg

rheological controls on the geometry of deep faults and the tectonic delamination of the continental crust recent seismic reflection profiles indicate that the deep faults in the continental crust may decouple deep within the crust or at the moho in the contribution it is argued that the decoupling horizons were initially zones across which variations in flow strength occur due to mineralogical differences in the principal rock types these can result in the tectonic delamination of the crust and at the moho calculations reveal marked strength differences across the moho once initial delamination occurs weak planes of mylonite develop along such surfaces and are preferentially reactivated during any subsequent deformation it is postulated that during tectonism the continental crust 1 does not act at depth as a single rigid entity 2 should not be considered as being firmly attached to the upper mantle and 3 is capable of moving independantly of the upper mantle

successive post variscan stress fields in the french massif central and its borders western european plate comparison with geodynamic data abstract structural analysis and particularly microtectonic methods have made it possible to define the different stages of brittle deformation of the massif central basement and the surrounding sedimentary cover from the end of the hercynian orogeny to the end of the tertiary during the stephanian a compressional tectonic regime prevailed regional faults appeared or were react vated reactivation as a result of initial n s compression becoming nw then e w these regional strike slip faults caused local extension which led to the formation of small coal bearing basins this compressional regime which marked the end of the formation of pangea was followed by a series of extension episodes permian triassic extension oscillating around n s e w to nw se extension in the early and middle jurassic and finally n s to ne sw extension in the late jurassic to cretaceous the normal faults formed during these episodes strongly influenced the distribution of emerging continents and sedimentary basins from the campanian 75 ma to the present the convergence of africa and eurasia involved the distribut on of stresses in the west european plate several tectonic episodes are distinguished in the massif central during the eocene approximately n s compression predominated general e w extension in the late eocene oligocene resulted in grabens with general northerly strike mainly in the centre of the massif central and on its east and southeast borders lastly compression varying from nw se to e w in the north and south of the massif central prevailed during the alpine orogenic phase at the end of the miocene these successive stages of brittle deformation are interpreted in the context of the evolution of the west european plate and its displacement in relation to the african plate the correspondences between the major geodynamic periods and the distribution of stresses over the west european continent are noted as well as the problems which remair to be resolved

the effect of a topographic high on the morphological stability of a two inlet bay system abstract the cross sectional stability of two tidal inlets connecting the same back barrier lagoon to the ocean is investigated the condition for equilibrium is the cross sectional area tidal prism relationship in an earlier study van de kreeke j 1990 can multiple inlets be stable estuarine coastal and shelf science 30 261 273 using the same equilibrium condition it was concluded that where two inlets connect the same basin to the ocean ultimately one inlet will close one of the major assumptions in that study was that the water level in the basin fluctuated uniformly in hindsight this assumption might be too restrictive for example in the wadden sea the back barrier lagoon consists of a series of basins rather than one single basin separated by topographic highs these topographic highs limit but do not exclude the exchange of water between the sub basins for this reason in the present study a topographic high in the form of a weir was added separating the back barrier lagoon in two sub basins the water level in the sub basins rather than in the back barrier as a whole is assumed to fluctuate uniformly for this schematization the hydrodynamic equations are solved using a finite difference method the results together with the equilibrium condition yield the equilibrium flow curve for each of the inlets the intersections of the two equilibrium flow curves represent combinations of cross sectional areas for which both inlets are in equilibrium the stability of the equilibriums was investigated using a non linear stability analysis resulting in a flow diagram calculations were carried out for different inlet and weir characteristics sinussoidal tides were the same for both inlets the results show that for relatively large wetted cross sectional areas over the topographic high approaching the situation of a single basin there are no combinations of inlet cross sectional areas for which both inlets are in a stable equilibrium this supports the conclusion in the earlier study for relatively small wetted cross sectional areas over the topographic high there is one set of stable equilibriums in that case the two inlet bay system approaches that of two single inlet bay systems

secondary cleavages in ductile shear zones abstract secondary cleavages developed at late stages in ductile shear zones show several features that are inconsistent with progressive simple shear in the zone these are the orientation of a single secondary cleavage oblique to the shear zone boundaries conjugate sets with opposite senses of shear and multiple sets with the same sense of shear these features can be explained if the bulk flow is partitioned into slip along discrete failure planes parallel to the primary foliation s coaxial stretching along the foliation and spin

recent crustal movements in the southern black forest western germany precise levelling data are examined in the southern black forest massif by comparing them analytically along levelling profiles instead of generalizing regional vertical motion trends the method emphasizes the current activity of accurately located individual structural elements measured recent crustal movement rates range from 0 2 to 1 1 mm year for the 1930 1961 1972 period the inferred motions corresponding to aseismic fault creep based on the near infrared band image of a landsat mss scene a lineament map of the study area is compared with the recent crustal movement rcm map the upper rhine graben eastern border fault between badenweiler and freiburg displays the highest rcm these displacements are consistent with the geological motion and the topographic expression of that structure within the massif both the lineament map and the rcm map demonstrate the predominant role played by wnw ese to nw se striking structures in accommodating the deformation moreover with the seismic dislocations in the southern black forest taking place also mainly on n120 and n20 faults it is most probable that these active structures are deep reaching zones of crustal weakness to some extent seismicity and rcm appear however to be mutually exclusive in their spatial distribution the seismic black forest flexure and dinkelberg block being opposed to the aseismically moving eastern and northern parts of the study area

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

oblique crustal detachment in the variscan schwarzwald southwestern germany the schwarzwald is part of the central polymetamorphic crystalline belt of the variscan orogen moldanubian belt from north to south it consists of four terranes the metasedimentary zone of baden baden the polymetamorphic central schwarzwald gneiss complex the sedimentary metamorphic zone of badenweiler lenzkirch and the hotzenwald complex the largest of these terranes is the central schwarzwald gneiss complex csgc whose rocks record a history of protracted regional metamorphism and anatectic melt generation during variscan convergence between 350 and 325 ma the csgc became detached from a high temperature lower crustal substratum and was emplaced southeastward over paleozoic clastics volcanic rocks and crystalline slivers of the zone of badenweiler lenzkirch and the hotzenwald complex kinematic indicators suggest that these early convergent movements on retrograde shear zones and the concomitant crustal thickening were superseded by movements on divergent shear zones the ascent of voluminous granitic plutons from a mid crustal zone of melt generation into the upper crust was probably triggered by a change in the crustal kinematics from overall convergence to overall divergence at about 325 ma in detail this process was probably diachronous detachment of upper crust and large scale melt generation in the middle crust of the schwarzwald was probably facilitated by the tectonic stacking of water rich pelitic clastics and gneiss slivers with relatively even proportions of crystalline and pelitic materials

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

deformation of leucogranites of the crystalline main central sheet in southern tibet china abstract towards the top of the main central sheet in southern tibet china leucogranites intrude metamorphic rocks related to rocks of the main central thrust in the himalayas our study shows that the leucogranites suffered a northward shear deformation the significance of this event is discussed in terms of gravity driven decollement of the 10 000 m thick tethyan sedimentary pile over its crystalline basement

short scale variations of tectonic regimes in the western european stress province north of the alps and pyrenees the data of the european part of the world stress map wsm are used to study the western european stress province north of the alps and pyrenees the study area is characterised by an almost homogeneous n 145 degrees e orientation of the maximum horizont

melt enhanced deformation a major tectonic process convergent tectonics between continental crustal blocks result in deep burial and anatexis of supracrustal rocks anatectic and or mantle derived melts combine to form a melt weakened zone in the thickened lower crust the accumulation of melt eventually leads to crustal failure along melt lubricated shear zones rapid 1 mm yr vertical component movements of large crustal blocks result we refer to these crustal displacements as tectonic surges the melt lubricated shears are characterized by the close association of sheared country rocks with foliated or massive igneous sills and plutons rocks that formed at different crustal levels are juxtaposed across these shear zones one result of surges with large lateral component of movement is metamorphic inversion with high pressure and high temperature metamorphic rocks structurally over lower pressure and temperature assemblages large and rapid vertical surges may displace crust containing abundant melt and may result in high t p including granulite facies metamorphism and preservation of metamorphic textures caused by rapid decompression

global mapping functions for the atmosphere delay at radio wavelengths i have developed expressions for calculating the ratios mapping functions of the line of sight hydrostatic and wet atmospheric path delays to their corresponding zenith delays at radio wavelengths for elevation angles down to 3 the coefficients of the continued fraction representation of the hydrostatic mapping function depend on the latitude and height above sea level of the observing site and on the day of the year the dependence of the wet mapping function is only on the site latitude by comparing with mapping functions calculated from radiosonde profiles for sites at latitudes between 43 s and 75 n the hydrostatic mapping function is seen to be more accurate than and of comparable precision to mapping functions currently in use which are parameterized in terms of local surface meteorology when the new mapping functions are used in the analysis of geodetic very long baseline interferometry vlbi data the estimated lengths of baselines up to 10 400 km long change by less than 5 mm as the minimum elevation of included data is reduced from 12 to 3 the independence of the new mapping functions from surface meteorology while having comparable accuracy and precision to those that require such input makes them particularly valuable for those situations where surface meteorology data are not available

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

tectonic evolution of the lufilian arc central africa copper belt during neoproterozoic pan african orogenesis abstract the lufilian arc of central africa also called katangan belt or copperbelt is a zone of low to highgrade metasedimentary and subsidiary igneous rocks of neoproterozoic age hosting highgrade cucou and pbzn mineralizations the lufilian arc is located between the congo and kalahari cratons and defines a structure which is convex to the north three major phases of deformation characterize the construction of the lufilian arc the first phase d1 called the kolwezian phase developed folds and thrust sheets with a northward transport direction d1 deformation occurred in the lufilian arc between ca 800 and 710 ma with a peak in the range 790 750 ma it is here correlated with the main deformation in the zambezi belt southward verging folds with the same trends as the d 1 structures were previously linked to a second tectonic event named kundelunguian phase of the lufilian orogeny we show in this paper that they are backfolds developed during d1 along katangan ramps and especially along the kibaran foreland the second phase d2 of the lufilian orogeny is the monwezi phase including several large leftlateral strikeslip faults which have been activated successively during this deformation phase the eastern block of the belt rotated clockwise giving the present day nwse trend of d1 structures in this part of the lufilian arc and generating its convex geometry the mwembeshi dislocation the major transcurrent shear zone separating the zambezi and lufilian arc was mostly active during the d2 deformation phase d2 deformation occurred between ca 690 and 540 ma such a long time interval is attributed to the migration of strikeslip faults developed sequentially from south to north and probably to a slow convergence velocity during the collision between the congo and kalahari cratons the third phase d3 of the lufilian orogeny is a late event called the chilatembo phase marked by structures transverse to the trends of the lufilian arc this deformation and the post d 2 uppermost kundelungu sequence ks3 plateaux group are younger than 540 ma and probably early paleozoic

lithospheric memory state of stress and rheology neotectonic controls on europe s intraplate continental topography abstract to date research on neotectonics and related continental topography development has mostly focused on active plate boundaries characterized by generally high deformation rates the intraplate sedimentary basins and rifts of the northern alpine foreland are associated with a much higher level of neotectonic activity than hitherto assumed seismicity and stress indicator data combined with geodetic and geomorphologic observations demonstrate that europe s intraplate lithosphere is being actively deformed this has major implications for the assessment of its natural hazards and environmental degradation the lithosphere of the northern alpine foreland has undergone a polyphase evolution with an intense interplay between upper mantle thermal perturbations and stress induced intraplate deformation that points to the importance of lithospheric folding of the thermally weakened lithosphere in this paper we address relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland with special emphasis on tectonically induced topography the objectives are to quantify the effects of ongoing alpine collision and atlantic ridge push on the intraplate deformation in europe and its impact on topography evolution and related natural hazards this paper reviews the four dimensional topographic evolution of the european lithosphere through a multi disciplinary approach linking geology geophysics and geotechnology until now research on neotectonics and related topography development of intraplate regions has received little attention our study examines a number of selected natural laboratories in continental europe from orogen through platform to continental margin these natural laboratories include the carpathians pannonian system the northwest european platform iberia and the atlantic continental margin we focus on lithosphere memory and neotectonics with special attention to the thermo mechanical structure of the lithosphere mechanisms of large scale intraplate deformation late neogene anomalies in subsidence and uplift and links with surface processes and topography evolution

emplacement related microstructures in the margin of a deformed pluton the san jose tonalite baja california mexico abstract in the san jose tonalite pluton baja california mexico interior magmatic fabrics give way progressively to subparallel solid state fabrics with s c structures near the margins the outer rim marginal northern unit approximately 1 km thick is inferred to have been deformed during the emplacement of the inner parts of the magma chamber the rocks show a transition from strongly deformed at the outer edge to progressively less deformed towards the inner edge of the marginal northern unit a small amount of melt appears to have been present during the deformation as indicated by 1 apparent contact melting between some grains of plagioclase and 2 coarse grained aggregates and single grains of quartz k feldspar and or more sodic plagioclase in fracture controlled openings in primary plagioclase crystals the more sodic plagioclase typically grew as rims on the walls of the openings in twin continuity with the primary plagioclase the deformed rocks have a prominent foliation marked mainly by aggregates of biotite with contributions by hornblende and titanite grains as well as apparently recrystallized aggregates of quartz and or feldspar at least some of which may have originated as zones of fragmentation many primary grains of plagioclase hornblende biotite and titanite show evidence of brittle deformation and fragmentation the shapes of aggregates in the folia relationships between incipient folia and residual primary grains and occurrences of many folia in narrow zones transecting strong minerals plagioclase and hornblende suggest that brittle processes may have controlled at least some of the foliation development however evidence of strain induced grain boundary migration and bulge nucleation of new grains of quartz and plagioclase indicates that dislocation creep also played a part in the deformation recrystallization of plagioclase together with intrusion of the pluton at greenschist facies ambient temperatures confirms high temperature deformation with heat derived from the cooling magma

pressure temperature time paths and a tectonic model for the evolution of granulites petrologic studies and application of well calibrated mineralogic thermometers and barometers reveal several important features common to many granulite terrains 1 peak metamorphic pressure and temperature conditions cluster around values of 7 5 pm 1 kbar and 800 pm 50 c implying average geothermal gradients of 30 35 c km 2 in comparison with upper amphibolite facies rocks especially in paired amphibolite granulite terrains it is evident that granulites are distinguished from amphibolites by the former s higher metamorphic temperatures but not higher pressure 3 initial cooling of granulite terrains from peak conditions is nearly isobaric for garnet closure temperatures of 600 pm 50 c the dp dt retrograde paths inferred from compositionally zoned garnet rims are 2 8 b c in most granulites 4 primary coarse sillimanite is found in most granulites and retrograde kyanite is known in a few these data suggest that granulites form as a result of anomalous thermal gradients

exposed cross sections through the continental crust implications for crustal structure petrology and evolution abstract the continental crust is exposed in cross section at numerous sites on the earth s surface these exposures which appear to have formed by obduction along great faults during continental collision may be recognized by exposures of deep crustal rocks exhibiting asymmetric patterns of metamorphic grade and age across the faults and by distinctive bouguer anomaly patterns reflecting dipping basement structure and an anomalously deep mantle from an examination of five complexes which meet these criteria it is concluded that the most prominent layering in the crust is not compositional but metamorphic the lower crust consists of granulite facies rocks of mafic to intermediate composition while the intermediate and shallow levels consist predominantly of amphibolite facies gneisses and greenschist facies supracrustal rocks respectively post metamorphic granitic intrusions are common at intermediate to shallow levels position of discontinuities in refraction velocity where present commonly correspond to changes in composition or metamorphic grade with depth the continental crust is characterized by lateral and vertical heterogeneities of varying scale which are the apparent cause of the complex seismic reflections recorded by cocorp field observations coupled with geochemical data indicate a complex evolution of the lower crust which can include anatexis multiple deformation polymetamorphism and reworking of older crustal material the complexity of the crust is thus the result of continuous evolution by recycling and metamorphism through time in a variety of tectonic environments

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

the late and post variscan tectonic evolution of the western border fault zone of the bohemian massif wbz paleostress analysis and evaluation of the stratigraphic unconformities reveal an extremely polyphase development of one of the most prominent fault zones of central europe usually known as the franconian line fl because the fl is just one fault zone although it is the most important fault zone within a complex fault system a more appropriate term is used herein western border fault zone of the bohemian massif wbz the reconstruction of the paleostress history was carried out by analysing sequences of individual strain increments that belong to the same stratigraphic units e g late variscan granites tertiary basalts a succession of at least 15 paleostress directions and tectonic regimes have been determined since late variscan time

matrix mosaics brittle deformation and elongate porphyroclasts granulite facies microstructures in the striding athabasca mylonite zone western canada abstract the late archean striding athabasca mylonite zone western canadian shield is a 400 km long linked system of granulite facies mylonite belts developed in the continental crust the granulite facies mylonites 800 1000 c at 0 8 1 1 gpa developed in subsets of the anhydrous mineral assemblage clinopyroxene orthopyroxene garnet plagioclase quartz hornblende comparison of the microstructures of the striding athabasca mylonites with published descriptions of natural and experimental deformation of geological and analogue materials at elevated homologous temperatures provides some insight into the role played by different processes in the development of the striding athabasca mylonites in addition to dislocation creep and dynamic recrystallisation extensive mass transfer occurred contemporaneously with brittle fracture and cataclasis during granulite facies metamorphism the microstructure and extreme phase dispersal in anhydrous polymineralic matrix mosaics is indicative of efficient grain scale and aggregate scale diffusion grain boundary mobility and mass transfer at relatively slow strain rates despite their annealed appearance the granoblastic matrix mosaics developed synkinematically deformation induced dilation may enhance metamorphic reactions where products are more voluminous than reactants in the porphyroclast population highly elongate 20 1 monocrystalline orthopyroxenes appear to be fragments of dismembered kinked parent grains rather than stretched porphyroclasts granulite facies mylonites should not be treated as direct analogues of greenschist facies mylonites in particular it is essential to evaluate the potential positive feedback between structural and metamorphic processes in highly strained high temperature shear zone rocks

effects of a shallow flood shoal and friction on hydrodynamics of a multiple inlet system prior studies have shown that frictional changes owing to evolving geometry of an inlet in a multiple inlet bay system can affect tidally driven circulation here a step between a relatively deep inlet and a shallow bay also is shown to affect tidal sea level fluctuations in a bay connected to multiple inlets to examine the relative importance of friction and a step a lumped element parameter model is used that includes tidal reflection from the step the model is applied to the two inlet system of katama inlet which connects katama bay on martha s vineyard ma to the atlantic ocean and edgartown channel which connects the bay to vineyard sound consistent with observations and previous numerical simulations the lumped element model suggests that the presence of a shallow flood shoal limits the influence of an inlet in addition the model suggests an increasing importance of friction relative to the importance of the step as an inlet shallows narrows and lengthens as observed at katama inlet from 2011 to 2014

the tectonic history of kohistan and its implications for himalayan structure the tectonic history of kohistan northern pakistan involves two collisional events cleavage and folding developed at 90 100 ma along the northern suture between the kohistan island arc and the asian plate at the same time there was major folding and shearing of the lower part of the kohistan arc approximately 100 km south of the suture this deformation was followed by ocean subduction south of the kohistan arc generating the kohistan calc alkaline batholith with subsequent ocean closure during the eocene and obduction of the kohistan arc together with the adjacent part of the asian plate over the indian continental crust the construction of balanced cross sections through the imbricated upper part of the indian continental crust in the footwall to this southern suture indicates a minimum displacement of 470 km requiring the western himalayan hinterland to be underlain by a large wedge of indian middle to lower crust there is some shortening of the overriding kohistan and asian plates by thrusts and shear zones but it is insufficient to satisfy the palaeomagnetic data there must be major crustal shortening involving thrusts in the hindu kush and pamirs north of kohistan the post eocene thrust direction which for most of pakistan is towards 160 is almost perpendicular to that immediately to the east in the himalayan belt generating complex refolded thrust patterns in the hazara syntaxis and large scale folding and rapid uplift with associated brittle faulting and seismic activity adjacent to the nanga parbat syntaxis these different thrust trends indicate that major thrust movement as well as the folds and deformation fabrics cannot always be related to plate movement vectors but are modified by or develop from complex rotations during place collision or from the gravitational spreading of a thickened crust a regional approach is required to recognize and correctly attribute the various components in thrust displacements

towards the determination of displacements in the upper rhine graben area using gps measurements and precise antenna modelling abstract the upper rhine graben is a north northeast trending rift system which belongs to the european cenozoic rift system today the southern part of the graben is seismically still active earthquakes of magnitude 5 have a recurrence time of approximately 30 years the eucor urgent project focuses on the seismic hazards and neotectonics in the upper rhine graben and the surrounding areas within the framework of this project five institutions have created and have been maintaining a gps network in the upper rhine graben and the surrounding area in order to monitor horizontal and vertical displacements in the study area two gps campaigns have been carried out in the network to monitor and to determine the horizontal and vertical displacements in the study area the first one was observed in 1999 and the second one in 2000 in 2002 2 weeks of data of the available permanent gps reference stations in the area have also been included in the investigations these permanent stations belong to the european reference frame permanent network international gps service network satellite positioning service of baden wurttemberg reseau gps permanent france rgp reseau gps permanent dans les alpes regal and the agnes operated by the swiss positioning service due to the small size of the displacements expected high accuracy requirements must be met in the gps processing in order to achieve this the results of the available absolute antenna calibrations have been considered in the data processing too the results have shown that the application of absolute antenna calibration models is crucial for the derivation of a highly accurate displacement field without these models large discrepancies on the level of few centimetres can be observed at those stations where the observations were carried out by different antennas in the various campaigns as expectedly due to the short time span no significant displacement could be detected in the study area however the deformation analysis shows that the horizontal displacements do not exceed the level of 1 mm yr this value agrees with the results of other investigations

the metamorphic evolution of granulites at fyfe hills implications for archaean crustal thickness in enderby land antarctica granulites at fyfe hills in enderby land antarctica crystallized at temperatures in excess of 850 c and possibly as high as 1000 c and at pressures of 8 10kbar during the mid to late archaean a number of features including repeated retrograde metamorphism at 5 5 8kbar retrograde reaction textures and rimward zoning in pressure sensitive systems suggest that following peak metamorphism the granulites stabilized at a depth of 18 26 km after stabilization the granulites cooled near isobarically to temperatures of 600 700 c assuming a total crustal thickness of 35 40 km during this late archaean interval of isobaric cooling the peak metamorphic crustal thickness is estimated at 35 56 km this estimate is significantly less than the 60 70 km obtained by summing the depths of the present levels of exposure 26 34 km and the thickness of the crust presently beneath fyfe hills approxi mately 35km and is therefore consistent with independent evidence for extensive post archaean thickening of the enderby land crust

twenty years of deep seismic reflection profiling in germany a contribution to our knowledge of the nature of the lower variscan crust near vertical reflection studies in germany have concentrated on the following objectives 1 the nature of crustal reflectors 2 a detailed velocity structure 3 zones of increased tectonic activity e g faults approximately 20 years ago the identity between reflectors in the near vertical and the wideangle range was established wide angle events being strongly influenced by velocity gradients a pronounced but limited low velocity body below the urach geothermal anomaly was detected by using an especially long spread length an alternating polarity of deep crustal reflectors could be demonstrated a deep fault zone cutting the whole crust at steep angles and shallow angle overthrust structures were detected in the variscan area there is generally a strong reflectivity in the variscan lower crust between the conrad level at 6 s two way travel time i e 18 km and the moho at 9 10 s i e 27 30 km depth the lower crust seems to consist of thin lenses or lamellae with alternating velocity they were probably generated by an extensive synand post orogenic melting process leaving behind mafic and ultramafic splinters in the lower crust and a compact ultramafic residue in the uppermost mantle the moho being formed as a new and uniform boundary the poorly reflective upper crust is probably dominated by vertically oriented plutons in a rigid environment

the role of tectonic grain size reduction in the rheological stratification of the lithosphere with the aid of published constitutive flow laws for common crustal and upper mantle rock types it is possible to construct curves showing variation of rock strength with depth in the continental lithosphere assuming a particular crustal stratification of rock types and a particular geothermal gradient such exercises lead to the conclusion that marked changes in strength can occur at major petrological interfaces such as the moho discontinuity which are therefore likely to be associated with a tendency for major sub horizontal detachments to form constitutive flow laws used for such purposes are usually assumed to represent steady state flow at constant rock microstructure

calculation and application of clinopyroxene garnet plagioclase quartz geobarometers recently published thermodynamic and experimental data in a variety of chemical systems have been evaluated to derive gibbs free energies for hedenbergite and pyrope these were used to calculate the geobarometric equilibria

on the internal geometry of mylonite zones mylonite zones are generally characterized by abrupt and very large strain transitions which commonly result in excessively anastomosing schistosities on a wide range of scales when compared with nonmylonitic foliations this geometry is very susceptible to remodification during progressive mylonitization resulting in unusual and complex fold lineation and foliation geometries and interrelationships open folds of the mylonitic foliation with axes parallel to the stretching lineation in the surrounding mylonite cannot have formed by the rotation of fold axes through a large angle within their axial planes as has been usually proposed for isoclinal and sheath folds in mylonitic zones open folds initiate with axes parallel or close to the stretching lineation due to the geometric effects of folding a mylonitic foliation which anastomoses around an ellipsoidal pod of less deformed material this initial geometry also allows the generation of fold axes curved within their axial plane through 1800 about the stretching lineation at the time of nucleation successive mylonitic foliations develop during this folding and refolding process with boundaries that truncate and isolate earlier fold hinges and portions of fold limbs as a consequence stretching and intersection lineations can vary from plane to plane through the mylonite zone although careful examination often reveals a weak overprinting stretching lineation parallel to the bulk movement direction for the whole zone fold asymmetry in mylonite zones is a potential indicator of shear sense across a zone if the fold axes lie at an angle to the bulk stretching lineation direction in such circumstances however a single asymmetry projected onto a plane perpendicular to the mylonitic foliation and containing the bulk stretching lineation can indicate either sense of shear depending on a variety of factors these include whether the foliation folded is primary or mylonitic and in the latter case whether the mylonite zone formed with a steep dip and horizontal stretching lineation or in some other orientation the most satisfactory sense of shear indicator is the asymmetry of s and c planes

graben inversion in nature and experiments the inversion of crustal scale basement grabens is studied here through laboratory experiments on small scale models and available oil industry seismic lines from the southern north sea two basic configurations are considered first both the basement and the sedimentary cover are brittle and inversion does not involve any potential decollement between them second the basement and sedimentary cover are separated by a weak ductile layer e g salt which can allow decollement of the cover during both extension and later compression and inversion the second configuration is more complicated and can lead to a large variety of geological structures laboratory experiments were carried out on brittle ductile models built with sand to represent brittle layers basement and sedimentary cover and silicone putty to simulate the decollement layer between basement and cover a mechanically based classification of inversion structures is proposed the effects of some crucial parameters are investigated including obliquity between the direction of shortening and normal faults as well as strength profiles and the presence or absence of salt diapirs the experimental investigation leads to the following conclusions 1 the inversion of the graben by reactivation of normal faults implies that the angle between the direction of compression and the graben is less than 45 2 if there is a superficial decollement e g basement cover interface inversion initiates low dipping thrust faults in the cover localized at graben borders 3 salt diapirs or salt walls localized along the graben borders in the cover are preferential sites for the development of thrust faults and 4 when the cover is decoupled from the basement by a decollement layer inversion induced deformation in the cover which is partitioned between thrust faults along the graben borders and strike slip faults within the graben trending oblique to the graben borders experimental results are compared with field examples in particular from the southern north sea

spatial variations of earthquake occurrence and coseismic deformation in the upper rhine graben central europe abstract seismic activity in the densely populated upper rhine graben urg is an aspect in the public political and industrial decision making process the spatial analysis of magnitude frequency distributions provides valuable information about local seismicity patterns and regional seismic hazard assessment and can be used also as a proxy for coseismic deformation to explore the seismo tectonic setting of the urg we combine five instrumental and one historic earthquake bulletins to obtain for the first time a consistent database for events with local magnitudes m l 2 0 in the whole urg and use it for the determination of magnitude frequencies the data processing results in a dataset with 274 poisson distributed instrumentally recorded earthquakes within the urg between 01 1971 and 02 2012 and 34 historic events since the year 1250 our analysis reveals significant b value variations along the urg that allow us to differentiate four distinct sections i iv with significant differences in earthquake magnitude distributions i basel region in the swiss france german border region b 0 83 ii region between mulhouse and freiburg in the southern urg b 1 42 iii central urg b 0 93 and iv northern urg b 1 06 high b values and thus a relatively low amount of high magnitude events in the freiburg section are possibly a consequence of strongly segmented small scale structures that are not able to accumulate high stresses we use the obtained magnitude frequency distributions and representative source mechanisms for each section to determine coseismic displacement rates a maximum horizontal displacement rate of 41 m a around basel is found whereas only 8 m a are derived for the central and northern urg a comparison with geodetic and geological constraints implies that the coseismic displacement rates cover less than 10 of the overall displacement rates suggesting a high amount of aseismic deformation in the urg

evolution of coronas in norwegian anorthosites re evaluation based on crystal chemistry and microstructures coarse grained garnet pyroxene coronas in anorthositic gabbros of the bergen and sognefjord areas preserve relics of two stages of reaction during cooling from magmatic t 1 ol plag cpx i opxi spn 2 cpxi opxi spn plag cpxii opxii gnt

regional stress field and rifting in western europe abstract baumann h 1981 regional stress field and rifting in western europe in j h illies editor mechanism of graben formation tectonophysics 73 105 111 in situ stress determination is one possibility to determine stress magnitudes in the earth s crust most measurements especially in the northern alpine foreland have been carried out by using the doorstopper technique stress magnitudes are presented as excess stresses a number of sites where stresses have been determined gave sufficiently high values to statistically determine stress directions for the following tectonic blocks 1 western alps 2 their immediate foreland with the rhinegraben and 3 the rhenish shield bordering on the rift segment of the lower rhine embayment in discussing results of the statistical analyses of stress data it is suggested that stresses measured in the western alps have mainly a topographic origin in the alpine foreland to the north of the rhenish shield topographic stresses are superimposed on active tectonic stress considering the structural and lithological differences the foreland blocks show a different response to the same tectonic stress field which trends for 1 at about 146 this active stress field causes shear rifting in the upper rhinegraben but extensional rifting in the lower rhine embayment in the rhenish shield area only local step faults are observed in direction of 1 due to the ductile behaviour of its basement

tides in a system of connected estuaries abstractthe spatial structure of tidal amplitude and phase in a simplified system of connected estuaries an idealized version of florida s intracoastal waterway is analyzed with a linear analytical model this model includes friction the earth s rotation and variable bathymetry it is driven at the connection with the ocean by a co oscillating tide model results compare well with observations of pressure and currents in a section of the intracoastal waterway on the east coast of florida the comparison suggests that the waterway is highly frictional causing the amplitude of the water elevation and tidal velocity to decrease away from the inlets to a minimum in the middle of the waterway the local phase relationship between velocity and water elevation changed nonlinearly from 90 with no friction to 45 with maximum friction in moderately to highly frictional basins the phase lag was consistently less than 45