pre neogene controls on present day fault activity in the west netherlands basin and roer valley rift system southern netherlands role of variations in fault orientation in a uniform low stress regime the west netherlands basin wnb and the neighbouring roer valley rift system rvrs form the most prominent tectonic features of the onshore netherlands the two basins have a common tectonic origin and similar mesozoic evolution their neogene quaternary evolution however is markedly different while the wnb is tectonically seismically inactive and is characterised by uniform neogene quaternary subsidence in the rvrs fault controlled intra plate deformation has taken place since late oligocene times with pronounced seismic activity considering the present day ne sw regional extension as well as the similar basin orientation and mesozoic evolutions one would not expect strikingly different neotectonic activity in the two basins detailed analysis of mesozoic tertiary and quaternary fault patterns revealed that 1 the palaeozoic mesozoic tectonic fabric has great influence on the cenozoic deformation style of the basin system 2 present day faulting in the rvrs is related to the reactivation of pre existing faults and 3 the mesozoic fault pattern is slightly different in the two basins using a novel technique three dimensional 3 d slip tendency analysis we aim to determine whether these differences in fault orientation are substantial enough to produce significantly different resolved stresses along the faults this modelling not only tests a common geological phenomena but indirectly also delivers important constraints regarding the origin of faulting in the study area during the analysis 3 d geometric models of 84 mapped faults were investigated the results of this recently developed modelling technique reveal that the faults in both basins should behave similarly under the condition of a laterally homogeneous regional stress field which is in disagreement with the present day tectonic activity of the region on the other hand the modelling also reveals that the predicted tendency of slip is very sensitive to the ratio of the minimum horizontal and the vertical stress s as an explanation for the pronounced fault activity in the rvrs and the tectonic quietness of the wnb it is proposed that either the regional extension in the wnb is weaker in term of higher s ratio than that in the rvrs or the slip thresholds in the two basins are different the study emphasised that differentiation in the tectonic evolution has already started in the tertiary therefore it is reasonable to assume that the different tectonic stress field and or slip threshold between the two areas is directly related to the origin of the cenozoic rifting in the rvrs several hypotheses are discussed to account for these two possibilities taking into account the lithospheric structure and the cenozoic tectonic evolution of the two basins as well as surrounding areas 2004 elsevier ltd all rights reserved

the skien lavas oslo rift petrological disequilibrium and geochemical evolution the skien lavas which form the earliest phase of basaltic magmatism within the permo carboniferous oslo rift contain multiple generations of clinopyroxene which exhibit strong petrological and geochemical disequilibrium three principal core compositions have been identified 1 low jadeite high mg cr diopside cores crmgdi with strongly depleted trace element signatures which are believed to be xenocrystic in origin 2 mg rich cr poor diopside cores mgdi with moderately depleted trace element signatures which probably represent early cognate growth and 3 more dominant low mg phenocrystic diopside cores phendi several samples contain crmgdi or mgdi cores which have been subjected to resorption and partial re equilibration with their host melts indicative of extensive disequilibrium and magma mixing these three core types are overgrown by trace element enriched ti augite which also forms megacrysts and late stage lava groundmass calculated ti augite melt partition coefficients show clinopyroxene compatibility of the m hree zr hf and y the lile sr and nb remain incompatible esr300 and end300 of ti augite overgrowths phenocrystic diopside and mgdi diopside cores show that intrasample isotopic disequilibrium existed when the host basalts were erupted all epsilon values lie within the range of data previously published for the skien lavas detailed examination of the chemical isotopic and textural disequilibrium features seen in these lavas has enabled us to place constraints upon the magmatic evolution of this basalt suite ranging from xenocryst incorporation to cognate multistage pyroxene growth as well as identifying clear evidence of magma mixing and possible crustal contamination

southern ocean isopycnal mixing and ventilation changes driven by winds observed and predicted changes in the strength of the westerly winds blowing over the southern ocean have motivated a number of studies on the response of the antarctic circumpolar current and southern ocean meridional overturning circulation moc to wind perturbations and led to the hypothesis of the eddy compensation regime wherein the moc becomes insensitive to wind changes in addition to the moc tracer transport also depends on mixing processes here we show in a high resolution process model that isopycnal mixing by mesoscale eddies is strongly dependent on the wind strength this dependence can be explained by mixing length theory and is driven by increases in eddy kinetic energy the mixing length does not change strongly in our simulation simulation of a passive ventilation tracer analogous to cfcs or anthropogenic co2 demonstrates that variations in tracer uptake across experiments are dominated by changes in isopycnal mixing rather than changes in the moc we argue that to properly understand tracer uptake under different wind forcing scenarios the sensitivity of isopycnal mixing to winds must be accounted for

age relations among oslo rift magmatic rocks implications for tectonic and magmatic modelling abstract this paper presents a compilation of 67 published and unpublished radiometric age determinations by the rb sr method on magmatic rocks in the continental oslo rift in southeast norway the data include most major rock types and structural units in the subaerial part of the rift the implications of these data with respect to the tectonomagmatic evolution of the rift and processes in the mantle and crust are discussed the oslo rift was active for about 60 million years the earliest recorded magmatic activity was the intrusion of basaltic and syenitic sills in the pre rift lower paleozoic sediments at about 300 ma extrusion of plateau lavas of basaltic and intermediate composition rhomb porphyries started about 295 ma and lasted to about 275 ma with largest magma volumes and highest extrusion rate from 295 to 285 ma in the vestfold graben segment gs one flow per 250 000 years and 0 30 km3 per 103 years the main faulting activity and graben formation occurred during this period the plateau volcanism was succeeded by a stage of bimodal central volcanoes most of which later underwent caldera collapses ring dykes and central intrusions in these calderas give ages in the range 268 266 ma in the vestfold and 266 243 ma in the akershus gs large composite intrusive complexes were emplaced in the periods 27 268 and 273 241 ma in the vestfold and akershus gs respectively a rate of propagation of the rift from ssw towards the nne has been estimated to 1 2 cm y 1 on the basis of 87 sr 86 sr initial ratios and type of magmatic products we estimate magmas to have been emplaced into the crust only during the first 20 25 ma of the magmatic period some of the magmatism appears to be initiated by movement along precambrian fault zones which were reactivated during the oslo rifting event

the structure and evolution of the wessex basin southern england an example of inversion tectonics abstract the wessex basin of southern england consists of four main sub basins each sub basin is thought to be fundamentally controlled by the normal reactivation of hercynian basement thrust and wrench or transfer faults post hercynian polyphase reactivation of both east west thrust and northwest southeast transfer faults tended to compartmentalise the basement thereby leading to the initiation of discrete permian cretaceous depocentres while rifting was confined to the western portions of the area during the permo triassic easterly migration in the mesozoic allowed the initiation of the weald and channel basins the sub basins represent therefore simple sinistral pull apart basins opening along northwest southeast faults this same fault direction is postulated to have also played a major role in controlling and or modifying the development of european basins in general major pre aptian uplift and erosion is largely attributed to the thermal effects and hence the isostatic uplift of the basin associated with continental rifting of the bay of biscay and the north atlantic margins major inversion and hence basin destruction began in the late cretaceous early tertiary with the uplift of the channel weald and vale of pewsey basins and culminated in the oligocene miocene synchronous with the helvetic phase of alpine deformation wessex basin inversion was facilitated by the thrust reactivation of variscan faults above an intracrustal detachment surface the same surface which allowed upper crustal extension and hence basin initiation in the permo triassic the structural development of the wessex basin both during extension basin formation phase and compression inversion phase was ultimately controlled by the plate motion of africa relative to europe such plate motions successfully predict the observed nw se sinistral motion from the stephanian to the aptian e w sinistral motion during the aptian cenomanian and largely nw se dextral motion from the cenomanian to the present day

reply to comments by l michon and o merle on evolution of the european cenozoic rift system interaction of the alpine and pyrenean orogens with their foreland lithosphere by p dezes s m schmid and p a ziegler tectonophysics 389 2004 1 33

the cenozoic lower rhine basin rifting sedimentation and cyclic stratigraphy in the cenozoic the lower rhine basin formed as a rift at the southeastern terminus of the dutch german central graben while the rhenish massif was uplifted the study focusses on the marginal marine and fluvial fill of the lower rhine basin a basin model is developed support for this study was given by extensive industry outcrop and well data by new stratigraphical and sedimentological observations the ingression and subsequent regression of the cenozoic north sea is analysed using the concept of base level cyclicity as the geohistory of the basin was complex a subsidence curve is constructed furthermore an attempt is made to trace the simultaneous uplift of the rhenish massif

antarctic bottom water warming and freshening contributions to sea level rise ocean freshwater budgets and global heat gain abstractfreshening and warming of antarctic bottom water aabw between the 1980s and 2000s are quantified assessing the relative contributions of water mass changes and isotherm heave the analysis uses highly accurate full depth ship based conductivity temperature depth measurements taken along repeated oceanographic sections around the southern ocean fresher varieties of aabw are present within the south pacific and south indian oceans in the 2000s compared to the 1990s with the strongest freshening in the newest waters adjacent to the antarctic continental slope and rise indicating a recent shift in the salinity of aabw produced in this region bottom waters in the weddell sea exhibit significantly less water mass freshening than those in the other two southern basins however a decrease in the volume of the coldest deepest waters is observed throughout the entire southern ocean this isotherm heave causes a salinification and warming on isobaths from the bottom up to the shallow potential tem

cenozoic uplift and subsidence in the north atlantic region geological evidence revisited abstract the topographic evolution of the passive margins of the north atlantic during the last 65 myr is the subject of extensive debate due to inherent limitations of the geological geomorphological and geophysical methods used for studies of uplift and subsidence we have compiled a database of sign time and amplitude where possible of topographic changes in the north atlantic region during the cenozoic 65 0 ma our compilation is based on published results from reflection seismic studies aft apatite fission track studies vr vitrinite reflectance trends maximum burial sediment supply studies mass balance calculations and extrapolation of seismic profiles to onshore geomorphological features the integration of about 200 published results reveal a clear pattern of topographic changes in the north atlantic region during the cenozoic 1 the first major phase of cenozoic regional uplift occurred in the late palaeocene early eocene ca 60 50 ma probably related to the break up of the north atlantic between europe and greenland as indicated by the northward propagation of uplift it was preceded by middle palaeocene uplift and over deepening of some basins of the north sea and the surrounding areas 2 a regional increase in subsidence in the offshore marginal areas of norway the northern north sea the northern british isles and west greenland took place in the eocene ca 57 35 ma 3 the oligocene and miocene 35 5 ma were characterized by regional tectonic quiescence with only localised uplift probably related to changes in plate dynamics 4 the second major phase of regional uplift that affected all marginal areas of the north atlantic occurred in the plio pleistocene 5 0 ma its amplitude was enhanced by erosion driven glacio isostatic compensation despite inconclusive evidence this phase is likely to be ongoing at present

initiation of melting beneath the oslo rift a melt inclusion perspective abstract this study of the most primitive magmas in the permo carboniferous oslo magmatic system aims at understanding the initial phases of magmatism in a rift related environment primary melt inclusions are investigated from two compositional types of pyroxene cr diopside and ti augite found within the alkaline skien basalts southern norway data from the analyses of melt inclusions in this tectonic setting indicate that the melting process is complex in both types of pyroxene two groups of melt inclusions can be identified together with rare co 2 fluid inclusions in the cr diopsides these are termed the cd high fe feo 9 wt and cd low fe feo the two groups of melt inclusions found in the ti augites are called ta high na na 2 o 2 wt and ta low na na 2 o 2 o 5 contents

the oslo rift a review the tectonomagmatic history of the oslo rift may be subdivided into 5 main periods stage 1 300 ma development of a shallow depression stage 2 300 295 ma roughly simultaneous onset of widespread basalt volcanism b1 and vertical movement along nnw sse to n s trending faults stage 3 295 275 ma main rifting period accompanied by volcanism dominated by rhomb porphyry lavas latites stage 4 275 240 ma change of magmatic style from basaltic shield volcanism to central volcanoes of mixed compositions many of which went through caldera collapses intrusion of composite batholiths of intermediate to granitic compositions stage 5 240 ma dike intrusions may have continued into triassic time both the crust and total lithosphere under the rift are thinned relative to the precambrian basement on both sides a 12 km thick high density and high velocity body occupies the lower crust along the rift axis and extends under the eastern and western rift shoulder petrological and geochemical data imply that this massive layer represents dense cumulates and gabbroic rocks formed from mantle derived magmas in deep crustal magma chambers two mantle sources one nearly undepleted age corrected nd of about 1 and sr of 10 to 15 the other mildly depleted nd of about 4 sr of 10 contributed melts to the oslo rift magmatism the two sources are interpreted as different parts of a heterogeneous upper mantle which before the rifting event belonged to the subcontinental lithosphere on their way to the surface the mantle derived magmas were retained in deep crustal magma chambers where they underwent extensive fractional crystallization some also suffered moderate contamination anatectic melts and melts formed by mixing between mantle derived and anatectic melts gave rise to syenitic and granitic intrusions

neotectonics and intraplate continental topography of the northern alpine foreland research on neotectonics and related seismicity has hitherto been mostly focused on active plate boundaries that are characterized by generally high levels of earthquake activity current seismic hazard estimates for intraplate domains are mainly based on probabilistic analyses of historical and instrumental earthquake catalogues the accuracy of such hazard estimates is limited by the fact that available catalogues are restricted to a few hundred years which on geological time scales is insignificant and not suitable for the assessment of tectonic processes controlling the observed earthquake activity more reliable hazard prediction requires access to high quality data sets covering a geologically significant time span in order to obtain a better understanding of processes controlling on going intraplate deformation the alpine orogen and the intraplate sedimentary basins and rifts in 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 deformation of the northern alpine foreland is still on going and will continue in the future this has major implications for the assessment of natural hazards and the environmental degradation potential of this densely populated area we examine relationships between deeper lithospheric processes neotectonics and surface processes in the northern alpine foreland and their implications for tectonically induced topography for the environmental tectonics project entec the upper and lower rhine graben urg and lrg and the vienna basin vb were selected as natural laboratories the vienna basin developed during the middle miocene as a sinistral pull apart structure on top of the east alpine nappe stack whereas the upper and lower rhine grabens are typical intracontinental rifts the upper rhine graben opened during its late eocene and oligocene initial rifting phase by nearly orthogonal crustal extension whereas its neogene evolution was controlled by oblique extension seismic tomography suggests that during extension the mantle lithosphere was partially decoupled from the upper crust at the level of the lower crust however whole lithospheric folding controlled the mid miocene to pliocene uplift of the vosges black forest arch whereas thermal thinning of the mantle lithosphere above a mantle plume contributed substantially to the past and present uplift of the rhenish massif by contrast oblique crustal extension controlling the late oligocene initial subsidence stage of the lower rhine graben gave way to orthogonal extension at the transition to the neogene the entec project integrated geological geophysical geomorphologic geodetic and seismological data and developed dynamic models to quantify the societal impact of neotectonics in areas hosting major urban and industrial activity concentrations the response of europe s intraplate lithosphere to late neogene compressional stresses depends largely on its thermo mechanical structure which in turn controls vertical motions topography evolution and related surface processes

antarctic ocean and sea ice response to ozone depletion a two time scale problem theresponseofthesouthernoceantoarepeatingseasonalcycleofozonelossisstudiedintwocoupledclimate models and is found to comprise both fast and slow processes the fast response is similar to the interannual signature of the southern annular mode sam on sea surface temperature sst onto which the ozone hole forcing projects in the summer it comprises enhanced northward ekman drift inducing negative summertime sst anomalies around antarctica earlier sea ice freeze up the following winter and northward expansion of the sea ice edge year round the enhanced northward ekman drift however results in upwelling of warm waters from below the mixed layer in the region of seasonal sea ice with sustained bursts of westerly winds induced by ozone hole depletion this warming from below eventually dominates over the cooling from anomalous ekman drift the resulting slow time scale response years to decades leads to warming of ssts around antarctica and ultimately a reduction in sea ice cover year round this two time scale behavior rapid cooling followed by slow but persistent warming is found in the two coupled models analyzed one with an idealized geometry and the other with a complex global climate model with realistic geometry processes that control the time scale of the transition from cooling to warming and their uncertainties are described finally the implications of these results are discussed for rationalizing previous studies of the effect of the ozone hole on sst and sea ice extent

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

middle paleocene uplift of the brabant massif from central belgium up to the southeast coast of england during the middle paleocene laramide phase several basins in europe experienced subsidence while others experienced uplift previous studies have shown that during the laramide phase some basins surrounding the brabant massif experienced subsidence into shallow depocentres this study discusses how the brabant massif simultaneously experienced uplift along its wnw ese caledonian structural axis from central belgium in the east up to the southeast coast of england ipswich in the west uplift resulted in erosion of the formerly deposited chalk group on top of the axis of the brabant massif the erosion products of the chalk group were reworked in the latest danian to earliest thanetian deposits that filled the surrounding depocentres early to middle thanetian pulsed marine transgressions caused flooding and deposition across the entire region including the previously uplifted axis of the brabant massif the depositional thicknesses however indicate that the axis of the brabant massif remained a relative high up to the middle thanetian both the geometry and timing of the middle paleocene vertical surface movements of the brabant massif and surrounding areas are very similar to those described for other structural entities in central and northern europe despite their often strongly differing mesozoic tectonic evolutions we discuss several mechanisms that might have triggered these vertical surface movements of which lithospheric folding seems the most likely

kinematic analysis of the upper rhine graben boundary fault system this paper presents a new set of kinematic data for the central part of the upper rhine graben fault slip measurements were gathered covering the near field of a 200 km long segment of the graben boundary faults on both sides the resulting kinematic analysis shows a strong predominance of strike slip faulting and some oblique slip and pure normal faulting overall there is a regional coherence in the orientations of the extensional and shortening axes associated with both types of faulting throughout the entire study area the data set is best interpreted as the result of more or less continuous sinistrally transtensive kinematics with a nw se to nnw sse oriented or subvertical shortening and a ne sw to e w oriented extensional direction local transpressive overprints are not reflected in the pattern of brittle deformation in the near field of the boundary fault system we conclude that the opening history of the rhine graben may be less complex than hitherto assumed

discussion on evolution of the european cenozoic rift system interaction of the alpine and pyrenean orogens with their foreland lithosphere by p dezes s m schmid and p a ziegler tectonophysics 389 2004 1 33 the evolution and origin of the european cenozoic rift system ecris is a matter of debate for several decades e g tapponnier 1977 bergerat 1987 ziegler 1992 michon et al 2003 this rift system was characterized by the development of several grabens in the pyrenean and alpine forelands and by a magmatic activity starting at the k t transition dezes et al 2004 propose an additional reappraisal and interpret the ecris formation and the associated volcanism as resulting from the alpine and pyrenean collision and the emplacement of a mantle plume at depth below western europe our remarks on this paper will be focused on three different topics which make the final conclusions of dezes et al i e origin of the extension in the ecris highly questionable

sand injectites from source to emplacement an example from the miocene age frimmersdorf seam garzweiler open cast mine lower rhine embayment

north sea rift system abstract the mesozoic north sea rift forms an integral part of the arctic north atlantic rift system rifting activity in the north sea commenced during the earliest triassic during the mid jurassic the central north sea underwent a temporary doming stage crustal extension peaked during the late jurassic earliest cretaceous abated subsequently and terminated altogether during the paleocene the saucer shaped cenozoic post rift basin straddles the axis of the viking and central grabens this speaks for the applicability of a depth dependent pure shear model rather than a simple shear model geophysical data indicate an important discrepancy between upper and lower crustal attenuation across the north sea rift suggesting that during rifting processes the mono discontinuity was seriously destabilized this requires a basic modification of currently favoured crustal stretching models

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

the late oligocene to early miocene early evolution of rifting in the southwestern part of the roer valley graben the roer valley graben is a mesozoic continental rift basin that was reactivated during the late oligocene the study area is located in the graben area of the southwestern part of the roer valley graben rifting initiated in the study area with the development of a large number of faults in the prerift strata some of these faults were rooted in preexisting zones of weakness in the mesozoic strata early in the late oligocene several faults died out in the study area as strain became focused upon others some of which were able to link into several kilometer long systems within the late oligocene to early miocene northwestward prograding shallow marine syn rift deposits the number of active faults further decreased with time a relatively strong decrease was observed around the oligocene miocene boundary and represents a further focus of strain onto the long fault systems miocene extensional strain was not accommodated by further growth but predominantly by displacements along the long fault systems since the oligocene miocene boundary coincides with a radical change in the european intraplate stress field the latter might have contributed significantly to the simultaneous change of fault kinematics in the study area

crustal kinematics and deep structure of the northern rhine graben germany surface and subsurface geological data unpublished information gleaned from industrial seismic surveys and results from a deep reflection seismic profile across the tertiary northern rhine graben indicate that crustal extension in excess of 6 km was achieved by asymmetric detachment of the upper crust at a depth of about 15 km comparison of a simple geometric kinematic cross sectional model and its depth extrapolation with the dekorp 9 n deep crustal reflection data suggests that extension below the graben was achieved by slip along a gently westward dipping shear zone which truncated and offset lower crustal planar fabrics and which continues into the uppermost mantle the planar lower crustal reflectors probably originated mainly during late variscan permocarboniferous crustal extension and or magmatic underplating

implications of continuous structural inversion in the west netherlands basin for understanding controls on palaeogene deformation in nw europe a detailed analysis of high quality 3d seismic and borehole data provides new insights into the palaeogene tectonic history and inversion of the west netherlands basin the inversion characteristics are compared with those of other basins in the region to provide constraints on the palaeogene compressional tectonic movements in nw europe the inversion of the west netherlands basin which is characterized by the doming of the basin centre and by the reactivation of pre existing faults in a reverse mode was found to be the result of a continuous inversion process rather than a distinct tectonic pulse the intensity of the tectonic movements was not uniform throughout the eocene and was strongest during the latest eocene these characteristics are similar to those of other basins in the southern north sea region and in the english channel area in addition a good correlation exists between alpine tectonic events and the palaeogene inversion phases in light of these observations the latest eocene inversion pulse in the southern north sea region can be considered as the culmination of a long term inversion process that originated from the alpine collision

paleostresses of the groningen area the netherlands results of a seismic based structural reconstruction article i nfo we describe a novel workflow to reconstruct paleostresses in the subsurface where the traditional outcrop based method that uses fault slip measurements is not possible we use 3d seismic data and structural restoration to determine fault surfaces and slip vectors these data are then used as input for paleostress reconstruction algorithms the study area of ca 750 km 2 is situated in the groningen block the netherlands excellent quality 3d seismic data were used to interpret 11 horizons and approximately 80 faults between the tertiary and the top rotliegend indicators of fault slip direction are fault undulations sedimentary structures offset by faults and shapes of horizon cut outs these indicators were used as a basis of 3d restoration of the interpreted horizons a stepwise restoration approach was chosen that removed younger deformation to obtain slip vectors for older deformation events in a following work step numeric dynamic analysis nda was used to calculate paleostress tensors for the middle and lower tertiary upper cretaceous and upper rotliegend sequences the results presented in this paper are consistent with existing paleostress interpretations for nw europe however in contrast to previous studies they are derived from a subsurface volume where paleostress information was lacking until now issues that need further study include the effect of the size of the study area on the assumptions of a homogenous stress field and an analysis of the ambiguity of the interpretation of fault slip indicators on 3d seismic data

the pyrenean inversion phase in northern belgium an example of a relaxation inversion the analysis of 2d seismic and well data provides new insights into the late eocene to earliest oligocene dynamics along the southern border of the north sea area belgium from the start of the priabonian onwards the northwestern part of the campine basin and the london brabant massif to its west experienced subsidence and developed into a shallow trough simultaneously several other southern north sea basins including the central and eastern part of the campine basin and the roer valley graben were inverted by what is generally referred to as the pyrenean inversion phase inversion caused broad flexural uplift and minor reverse fault movements the characteristics of inversions in the southern north sea basins are very similar to each other and to those described for a phase of intraplate stress relaxation the results of this study therefore suggest that the pyrenean inversion phase was triggered by a regional stress relaxation that started around the bartonian priabonian boundary and ended before the onset of the oligocene

workflow for analysis of compositional data in sedimentary petrology provenance changes in sedimentary basins from spatio temporal variation in heavy mineral assemblages the field of provenance analysis has seen a revival in the last decade as quantitative data acquisition techniques continue to develop in the 20th century many heavy mineral data were collected these data were mostly used as qualitative indications for stratigraphy and provenance and not incorporated in a quantitative provenance methodology even today such data are mostly only used in classic data tables or cumulative heavy mineral plots as a qualitative indication of variation the main obstacle to rigorous statistical analysis is the compositional nature of these data which makes them unfit for standard multivariate statistics to gain more information from legacy data a straightforward workflow for quantitative analysis of compositional datasets is provided first 1 a centred log ratio transformation of the data is carried out to fix the constant sum constraint and non negativity of the compositional data next 2 cluster analysis is followed by 3 principal component analysis and 4 bivariate log ratio plots several 5 proxies for the effects of sorting and weathering are included to check the provenance significance of observed variations and finally a 6 spatial interpolation of a provenance proxy extracted from the dataset can be carried out to test this methodology available heavy mineral data from the southern edge of the miocene north sea basin are analysed the results are compared with available information from literature and are used to gain improved insight into miocene sediment input variations in the study area

olivine clinopyroxenite xenoliths in the oslo rift se norway olivine clinopyroxenite xenoliths in a basalt flow at krokskogen in the oslo rift consist mainly of al ti rich clinopyroxene and alteration products after olivine possibly also orthopyroxene the clinopyroxene contains primary inclusions of cr al bearing titanomagnetite pyrite and devitrified glass and secondary fluid inclusions rich in co2 on the basis of petrography mineral compositions and bulk major and trace element chemistry it is concluded that the xenoliths represent cumulates with about 5 trapped liquid formed from a mildly alkaline basaltic magma microthermometrical analysis of secondary or pseudosecondary fluid inclusions give a minimum pressure of formation of 5 5 to 6 kbars that is a depth greater than 16 17 km the host lava has initial nd 4 16 0 17 and sr 5 50 0 26 which is believed to reflect the isotopic composition of the lithospheric mantle source region under south norway in early permian time the isotopic character of the magma which gave rise to the xenoliths is preserved in clinopyroxenes which have ndt 1 9 to 2 6 and srt 1 1 to 1 8 the isotopic differences between the host magma and the xenoliths reflect some degree of crustal contamination of the xenolith s parent magma

arcuate thrust systems in sandbox experiments a comparison to the external arcs of the western alps in the external western alps two regional structural arcs were generated during tertiary northwest directed collision between the apulian indenter and the european passive margin these arcs distinguished by their geographic position and their age are examined by using a new compilation of structural data and comparing these to the results of sandbox analogue experiments the principal western alpine arc comprises two orthogonal synchronous thrust systems in the late eocene early miocene major shortening 105 km was toward the northwest to west northwest and minor shortening 11 km was toward the southwest shortening in each branch decreased toward the core of the arc during the late miocene and pliocene the jura arc accommodated 35 km of northwest directed shortening while 10 5 km of southwest to south southwest directed shortening was accommodated on the digne thrust system sandbox experiments were used to investigate the role of the motion vector of a rigid rectangular indenter orthogonal diagonal curved or rotational paths and the mechanical stratigraphy of the foreland in the evolution of upper crustal arcuate systems e g presence of a basal easy slip silicone horizon comparison of experimental results with the external alpine arc suggests that the indenter followed a slightly diagonal path with respect to the european margin from the eocene to the early miocene and curved counterclockwise by 10 15 in the middle miocene mechanical stratigraphy experiments support the hypothesis that thick triassic evaporites played a primary role in the evolution of the jura arc the influence of mechanical stratigraphy was most prominent during weak deformation at the external boundaries of the alpine orogen jura fold and thrust belt digne thrust

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

synchronous variability in the southern hemisphere atmosphere sea ice and ocean resulting from the annular mode zonally symmetric fluctuations of the midlatitude westerly winds characterize the primary mode of atmospheric variability in the southern hemisphere during all seasons this is true not only in observations but also in an unforced 15 000 yr integration of a coarse resolution r15 coupled ocean atmosphere model here it is documented how this mode of atmospheric variability known as the southern annular mode sam generates ocean circulation and sea ice variations in the model integration on interannual to centennial timescales that are tightly in phase with the sam the positive phase of the sam is associated with an intensification of the surface westerlies over the circumpolar ocean around 608s and a weakening of the surface westerlies farther north this induces ekman drift to the north at all longitudes of the circumpolar ocean and ekman drift to the south at around 308s through mass continuity the ekman drift generates anomalous upwelling along the margins of the antarctic continent and downwelling around 458s the anomalous flow diverging from the antarctic continent also increases the vertical tilt of the isopycnals in the southern ocean so that a more intense circumpolar current is also closely associated with positive sam in addition the anomalous divergent flow advects sea ice farther north resulting in an increase in sea ice coverage finally positive sam drives increases in poleward heat transport at about 308s while decreases occur in the circumpolar region ocean and sea ice anomalies of the opposite sign occur when the sam is negative the ocean and sea ice fluctuations associated with the sam constitute a significant fraction of simulated ocean variability poleward of 308s year round the robustness of the mechanisms relating the sam to oceanic variability suggests that the sam is likely an important source of large scale variability in the real southern hemisphere ocean

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

integrated study on the topographic and shallow subsurface expression of the grote brogel fault at the boundary of the roer valley graben belgium abstract the grote brogel fault gbf is a major wnw ese striking normal fault in belgium that diverges westward from the nw se striking western border fault system of the roer valley graben the gbf delimits the topographically higher campine block from the subsiding roer valley graben and is expressed in the digital terrain model dtm by relief gradients or scarps by integrating dtm electrical resistivity tomography ert cone penetration test cpt and borehole data we studied the quaternary activity of the gbf and its effects on local hydrogeology in the shallow subsurface

neotectonic reactivation of shear zones and implications for faulting style and geometry in the continental margin of ne brazil abstract the eastern continental margin of south america comprises a series of rift basins developed during the breakup of pangea in the jurassic cretaceous we integrated high resolution aeromagnetic structural and stratigraphic data in order to evaluate the role of reactivation of ductile neoproterozoic shear zones in the deposition and deformation of post rift sedimentary deposits in one of these basins the paraiba basin in northeastern brazil this basin corresponds to the last part of the south american continent to be separated from africa during the pangea breakup sediment deposition in this basin occurred in the albian maastrichtian eocene miocene and in the late quaternary however our investigation concentrates on the miocene quaternary which we consider the neotectonic period because it encompasses the last stress field this consisted of an e w oriented compression and a n s oriented extension the basement of the basin forms a slightly seaward tilted ramp capped by a late cretaceous to quaternary sedimentary cover 100 400 m thick aeromagnetic lineaments mark the major steeply dipping ductile e w to ne striking shear zones in this basement the ductile shear zones mainly reactivated as strike slip normal and oblique slip faults resulting in a series of miocene quaternary depocenters controlled by ne e w and a few nw striking faults faulting produced subsidence and uplift that are largely responsible for the present day morphology of the valleys and tablelands in this margin we conclude that precambrian shear zone reactivation controlled geometry and orientation as well as deformation of sedimentary deposits until the neogene quaternary

compositional variations major and trace elements of clinopyroxene and ti andradite from pyroxenite ijolite and nepheline syenite alno island sweden compositional variations major and trace elements of clinopyroxene and ti andradite from pyroxenite ijolite and nepheline syenite alno island sweden

pb sr nd isotopic behavior of deeply subducted crustal rocks from the dora maira massif western alps italy ii what is the age of the ultrahigh pressure metamorphism pb nd and sr isotope data are reported from two localities on mineral separates from mg rich metapelites and associated rocks that have been subducted to depths of at least 100 km for which metamorphic conditions are estimated at 28 33 kilobars pressure and 700 800 c and then returned to the surface initial isotope ratio data from the granitoid country rock are similar to those found in the metapelites the initial ratios indicate predominantly recycled aged granitic crustal materials for the sources of all of the samples five zircon samples 4 from pyrope megacrysts and 1 from fine grained pyrope quartzite lenses in the metapelites accurately define a chord yielding intercept ages of 304 10 and 38 0 1 4 ma in a concordia diagram zircon from the country rock also plots along the chord the zircon data together with initial nd and sr data indicate that the sedimentary sources of the rocks were derived mainly or entirely from sialic hercynian rocks ellenbergerite from pyrope megacrysts and monazite from the fine grained ground mass yield slightly younger ages of 30 34 ma apparently reflecting lower blocking temperatures than that of zircon sm nd data from a pyrope megacryst give an errorchron corresponding to an age of 38 ma in agreement with the zircon date a major question concerns the timing of the ultrahigh pressure metamorphism experimental data suggest that pyrope and quartz coesite as well as ellenbergerite formed by various metamorphic reactions if as generally assumed the ultrahigh pressure metamorphism occurred ca 100 ma ago our data require that the zircon did not experience measurable lead loss at that time but lost major amounts of lead 38 ma ago during late alpine metamorphism estimates of diffusion rates for nd in pyrope further suggest that the apparent sm nd age of 38 ma for the megacryst is not consistent with that model those problems are resolved if the ultrahigh pressure metamorphism occurred 38 40 ma ago but problems remain from ar ar dates of 100 ma on phengite an inferred 120 ma age for zircon lead loss from another study and possibly by the very rapid uplift required if the metamorphism is that young

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 and temporal variations in river terrace formation preservation and morphology in the lower meuse valley the netherlands the lower meuse valley crosses the roer valley rift system and provides an outstanding example of well preserved late glacial and holocene river terraces the formation preservation and morphology of these terraces vary due to reach specific conditions a phenomenon that has been underappreciated in past studies a detailed palaeogeographic reconstruction of the terrace series over the full length of the lower meuse valley has been performed this reconstruction provides improved insight into successive morphological responses to combined climatic and tectonic external forcing as expressed and preserved in different ways along the river new field data and data obtained from past studies were integrated using a digital mapping method in gis results show that late glacial river terraces with diverse fluvial styles are best preserved in the lower meuse valley downstream sub reaches traversing the venlo block and peel block while holocene terrace remnants are well developed and preserved in the upstream sub reaches traversing the campine block and roer valley graben this reach to reach spatial variance in river terrace preservation and morphology can be ascribed to tectonically driven variations in river gradient and subsurface lithology and to river driven throughput of sediment supply

characterization and quantification of active faulting in the roer valley rift system based on high precision digital elevation models the roer valley rift system rvrs is located in the northern prolongation of the upper rhine graben during the cenozoic the evolution of the rvrs was influenced by two different rift systems situated in the north and in the south the north sea rift system and the west european rift system respectively during the last decades moderate seismicity revealed the continuous activity of the graben border faults the peel boundary fault zone pbfz and the feldbiss fault zone ffz we use a high precision digital elevation model dem to characterize and quantify the present day deformation along these faults the fault pattern shows similarity to a strike slip structure however analysis of the dem reveals that the recent to quaternary formations and landforms affected by the fault activity are only vertically offset this suggests a pure normal faulting mode for the main border faults and a direction of extension perpendicular to the graben i e ne sw quantification of the offset dated markers allows the determination of the displacement rates along the fault segments in the southeastern part of the rvrs the vertical displacement rates inferred for the ffz and the southeastern pbfz range between 55 and 65 mm ky and around 65 mm ky respectively in contrast the displacement rates determined for the northwestern segment of the pbfz are around 200 mm ky we explain these differences between the northwestern and southeastern parts of the rvrs by the large scale geometry of the graben the rvrs being symmetric in the south east and asymmetric half graben in the north west the deformation is accommodated by two border faults ffz and the south eastern part of the pbfz in the south east and by only one fault in the north west the north western segment of the pbfz in addition the thickness of the neogene main depocentre in the northwestern half of the rvrs indicates a larger amount of extension in this part of the graben than in the south east the combination of the graben geometry and the amount of extension can explain the differences in the displacement rate

the mesozoic and tertiary basins of the bohemian massif and their evolution abstract the bohemian massif is a major positive element within the structural framework of the alpine carpathian foreland its basement became consolidated during the variscan orogeny crustal thicknesses range between 32 5 km and 40 km during the late carboniferous and early permian the bohemian massif became dissected by a conjugate system of wrench faults which controlled the accumulation of a continental coal bearing series late permian red beds were deposited on intramontane topographic depressions in triassic to mid jurassic times the bohemian massif formed a high from which clastics were shed into adjacent basins during the late jurassic and late cretaceous it became transected by nw se trending sedimentary basins the sub hercynian and laramide phases of foreland compression resulted in deformation and uplift of the bohemian massif the eger graben a 350 km long volcanotectonic zone cutting across the bohemian massif in an ene wsw direction came into evidence during the oligocene and is at present inactive the crust of the bohemian massif forms the autochthonous substratum of the outer carpathians which are paralleled by the neogene carpathian foredeep the neogene intramontane neo autochthonous vienna basin is superimposed on the alpine carpathian nappe systems and developed under a tensional setting

evolution of the lithosphere in the area of the rhine rift system the rhine rift system rrs forms part of the european cenozoic rift system ecris and transects the variscan orogen permo carboniferous troughs and late permian to mesozoic thermal sag basins crustal and lithospheric thicknesses range in the rrs area between 24 36 km and 50 120 km respectively we discuss processes controlling the transformation of the orogenically destabilised variscan lithosphere into an end mesozoic stabilised cratonic lithosphere as well as its renewed destabilisation during the cenozoic development of ecris by end westphalian times the major sutures of the variscan orogen were associated with 45 60 km deep crustal roots during the stephanian early permian regional exhumation of the variscides was controlled by their wrench deformation detachment of subducted lithospheric slabs asthenospheric upwelling and thermal thinning of the mantle lithosphere by late early permian times when asthenospheric temperatures returned to ambient levels lithospheric thicknesses ranged between 40 km and 80 km whilst the thickness of the crust was reduced to 28 35 km in response to its regional erosional and local tectonic unroofing and the interaction of mantle derived melts with its basal parts re equilibration of the lithosphere asthenosphere system governed the subsidence of late permian mesozoic thermal sag basins that covered much of the rrs area by end cretaceous times lithospheric thicknesses had increased to 100 120 km paleocene mantle plumes caused renewed thermal weakening of the lithosphere starting in the late eocene ecris evolved in the pyrenean and alpine foreland by passive rifting under a collision related north directed compressional stress field following end oligocene consolidation of the pyrenees west and northwest directed stresses originating in the alps controlled further development of ecris the rrs remained active until the present whilst the southern branch of ecris aborted in the early miocene extensional strain across ecris amounts to some 7 km plume related thermal thinning of the lithosphere underlies uplift of the rhenish massif and massif central lithospheric folding controlled uplift of the vosges black forest arch

new late cretaceous and paleogene paleomagnetic results from south china and their geodynamic implications 1 to better understand the tectonic evolution of south china block scb in response to the india asia collision we present new paleomagnetic results from late cretaceous and paleogene red bed formations of the hengyang basin of hunan province in the interior part of the scb stepwise thermal demagnetization of the rocks isolated a high temperature component the tilt corrected mean direction from the late cretaceous rocks is d 15 6 i 29 9 with a95 5 7 n 26 sites corresponding to a paleopole at 71 9 n 236 3 e with a95 4 7 which passes reversal tests the tilt corrected mean direction d 358 9 i 35 4 with a95 5 0 n 22 sites from the paleogene rock which passes the reversal test gives a pole at 82 6 n 300 6 e with a95 4 4 the low field anisotropy of magnetic susceptibility results suggest that the red beds have not experienced significant strain due to compaction or tectonic stress while the anisotropy of isothermal remanence results suggest that postdepositional compaction in these red beds produced no more than 3 4 of inclination shallowing these paleomagnetic and rock magnetic tests imply that the remanence is primary on the basis of paleomagnetic results obtained from coeval basalts in mongolia and siberia we suggest that no significant latitudinal motion has taken place between the scb and siberia since the late cretaceous the significant latitudinal discrepancy between the scb and european block could be due to nonrigid behavior of the eurasian plate since the late cretaceous a 16 7 5 0 clockwise rotation of the scb during the late cretaceous to the paleogene could be related to the collision of india and asia in the west and the subduction of the circum pacific plate to eastern asia in the east

a comparison of burial maturity and temperature histories of selected wells from sedimentary basins in the netherlands sedimentary basins in the netherlands contain significant amounts of hydrocarbon resources which developed in response to temperature and pressure history during mesozoic and cenozoic times quantification and modelling of burial maturity and temperature histories are the major goals of this study allowing for a better understanding of the general geological evolution of the different basins as well as petroleum generation all major basins in the netherlands encountered at least one time of inversion and therefore moderate to high amounts of erosion in order to determine the amount of inversion the basins have experienced a 1d study was performed on 20 wells within three basins west netherlands central netherlands and lower saxony basins new vitrinite reflectance values were obtained and existing data re evaluated to gain a good data base the burial histories of six wells two for each studied basin are presented here to demonstrate the differences in basin evolution that led to their present shape and petroleum potential the permo triassic subsidence phase can be recognized in all three basins but with varying intensity in the jurassic the basins experienced different relative movements that culminated in the cretaceous when the influence of the inversion caused erosion of up to 2 500 m most wells show deepest burial at present day whereas the timing of maximum temperature differs significantly springer verlag 2007

the cenozoic evolution of the roer valley rift system integrated at a european scale the roer valley rift system rvrs is located between the west european rift and the north sea rift system during the cenozoic the rvrs was characterized by several periods of subsidence and inversion which are linked to the evolution of the adjacent rift systems combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the cenozoic evolution and quantification of the subsidence during the early paleocene the rvrs was inverted laramide phase the backstripping method shows that the rvrs was subsequently mainly affected by two periods of subsidence during the late paleocene and the oligocene quaternary time intervals separated by an inversion phase during the late eocene during the oligocene and miocene periods the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70 80j counter clockwise integration of these results at a european scale indicates that the late paleocene subsidence was related to the evolution of the north sea basins whereas the oligocene quaternary subsidence is connected to the west european rift evolution the distribution of the inverted provinces also shows that the early paleocene inversion laramide phase has affected the whole european crust whereas the late eocene inversion was restricted to the southern north sea basins and the channel area finally comparison of these deformations in the european crust with the evolution of the alpine chain suggests that the formation of the alps has controlled the evolution of the european crust since the beginning of the cenozoic

slip tendency analysis as a tool to constrain fault reactivation a numerical approach applied to three dimensional fault models in the roer valley rift system southeast netherlands we describe a new numerical approach to constrain the three dimensional 3 d pattern of fault reactivation taking advantage of the knowledge of the tectonic stress field the ratio of the resolved shear and normal stresses slip tendency as well as the direction of the shear stress is calculated at every location on the faults modelled by triangulated surfaces although the calculated contact stresses represent only a first order approximation of the real stresses comparison of the 3 d pattern of slip tendency with the frictional resistance of the fault can provide useful constraints on the probability of fault reactivation the method was applied to 3 d geometrical fault models in the roer valley rift system southeast netherlands which is presently characterized by pronounced tectonic activity the input stress tensors were constrained by published stress indicators the analysis demonstrated that the observed fault activity could be explained within a reasonable range of frictional parameters and input stress magnitudes in addition a fairly good correlation was found between the predicted slip directions and the focal mechanisms of local earthquakes this suggests that in the study area fault models being valid in the uppermost part of the crust are suitable to constrain fault reactivation even in the deeper part of the seismogenic layer the analysis further demonstrated that fault hierarchy and the regional tectonic contexts of the fault system are important factors in fault reactivation therefore they always should be taken into account during evaluation of the calculated slip tendency and slip direction patterns

neotectonics of the netherlands a review abstract earthquakes and vertical land movements inferred from geodetic levelling results demonstrate that the netherlands is situated on a tectonically active part of the earth s surface tectonic subsidence analyses of the sedimentary records in the basins and the history of tectonic uplift inferred from meuse river terraces show that the current tectonic activity is part of a deformation phase which began in the late early miocene which we take as the start of the neotectonic period the neotectonic faulting mode is normal slip this is in accordance with the present day orientation of the maximum horizontal stress and the vertical orientation of the maximum stress however the neotectonic fault zones are reactivated variscan or older wrench faults these faults have been reactivated repeatedly during the mesozoic and cenozoic in normal and wrenching modes and therefore represent fundamental crustal weakness zones as a result the surficial neotectonic fault pattern resembles the inherited wrenching fault pattern although the faulting mode is normal slip this is illustrated for the area where normal faults have displaced the meuse fluvial terrace system in the southeastern part of the netherlands the neotectonic vertical motions in and around the roer valley rift system have affected the courses of the rhine and meuse rivers from pliocene times until the present in addition a fluvial terrace staircase developed along the meuse river in response to the uplift of the ardennes rhenish massif and its foreland for example near maastricht furthermore small fault scarps are present along segments of the bounding fault zones of the roer valley graben the peel boundary fault zone and the feldbiss fault zone in other parts of the netherlands the neotectonic vertical motions have no direct expression in the morphology examples of possible indirect control on the morphology in these areas occur in glacial landscapes the zuiderzee basin and the coastal zone

interplay between climatic tectonic and anthropogenic forcing in the lower rhine graben the roer river the roer is a small river which drains the rhenish shield and confluences with the meuse river up to now the geological climatological biostratigraphical and pedological setting of the roer valley were not sufficiently integrated to disentangle the effects of external forcing factors on the roer river in this study we perform a detailed and integrated reconstruction of the fluvial morphology and palaeogeography of the roer river in order to determine responses to combined climatic tectonic and anthropogenic forcing factors the roer river has formed five terrace levels since the weichselian late pleniglacial fluvial planform of the roer river was predominantly climate controlled during the lateglacial and early holocene reach to reach variations in river terrace formation and fluvial planform change occur due to variations in tectonic setting subsurface geology base level fluctuations and the confluence with tributary systems differential subsidence by active faulting in the roer valley graben during the early lateglacial caused a preferential usage of the down tilt channels of the up to then double channel belt systems in the roer valley this preferred channel avulsion towards a fault zone leaving an underfit system on the up tilted side and the clustering of holocene roer channels along that fault zone meet the criteria for a lateral response of the roer river to a tectonic forcing anthropogenic influences in the form of deforestation and land use changes during the late holocene are responsible for the formation of a final terrace level and overbank sediments 2019 elsevier b v

where and how long ago was water in the western north atlantic ventilated maximum entropy inversions of bottle data from woce line a20 1 a maximum entropy me method is used to deconvolve tracer data for the joint distribution of locations and times since last ventilation the deconvolutions utilize world ocean circulation experiment line a20 repeat hydrography for cfc 11 potential temperature salinity oxygen and phosphate as well as global ocean data analysis project glodap radiocarbon data combined with surface boundary conditions derived from the atmospheric history of cfc 11 and the world ocean atlas 2005 and glodap databases because of the limited number of available tracers the deconvolutions are highly underdetermined leading to large entropic uncertainties which are quantified using the information entropy of relative to a prior distribution additional uncertainties resulting from data sparsity are estimated using a monte carlo approach and found to be of secondary importance the me deconvolutions objectively identify key water mass formation regions and quantify the local fraction of water of age or older last ventilated in each region ideal mean age and radiocarbon age are also estimated but found to have large entropic uncertainties that can be attributed to uncertainties in the partitioning of a given water parcel according to where it was last ventilated labrador irminger seawater l water is determined to be mostly less than 40 a old in the vicinity of the deep western boundary current dwbc at the northern end of a20 but several decades older where the dwbc recrosses the section further south pointing to the importance of mixing via a multitude of eddy diffusive paths overflow water lies primarily below l water with young waters 40 a at middepth in the northern part of a20 and waters as old as 600 a below 3500 m

structural style and reservoir development in the west netherlands oil province the area of the rijswijk concession largely coincides with the onshore part of the west netherlands basin to date oil has been produced from ten fields with a total stock tank oil initially in place stoiip of ca 210 x 106 m3 1 3 x 109 bbls reservoirs comprise continental and shallow marine elastics of late jurassic to early cretaceous age deposited in syn rift and post rift settings the west netherlands basin was created during late jurassic and early cretaceous rifting characterised by divergent oblique slip faulting this created a nw se trending block faulted depression between the london brabant massif and the zandvoort ridge shallow marine elastics and marls were deposited in the subsequent post rift stage during the latest cretaceous and early tertiary regional uplift and convergent oblique slip faulting resulted in basin inversion and reverse reactivation of pre existing normal faults due to the transpressional nature of the basin inversion narrow asymmetrical anticlines were formed often bounded by upwardly divergent reverse faults in the hanging wall blocks of former normal faults these structures constitute the general trap geometry of all cretaceous oil fields in the basin the acquisition of 3d seismic data has resulted in significantly enhanced structural definition and has led to the development of new structural and depositional models which improve the prediction of reservoir development and risk assessment

early pleistocene tiglian sites in the netherlands a revised view on the significance for quaternary stratigraphy abstract the tiglian a b and c form the main subdivision of the early pleistocene tiglian stage in northwest european chronostratigraphy since the 1960 s we re evaluated the sedimentary context and new and legacy pollen assemblages of the classic type localities of these tiglian pollen zones in the dutch german border area and roer valley graben following recalculation of new upland pollen sums we found that the three fold subdivision of the tiglian stage is too simplistic and lacks a sound stratigraphic basis the tiglian a is only found locally and cannot be positively identified in the rvg the tiglian b in the tegelen maalbeek area is not unique since similar occurrences are present at other depths in the rvg sedimentary and pollen analysis suggests tiglian c as defined in the tegelen maalbeek type area could have been deposited in a very short amount of time although this does contradict mammal data the t b c cycle preserved in the type area likely represent a single example of multiple similar early pleistocene climate cycles the sediments of the so called cool or cold phase of pollen zone t c 4c in the stratotype of the tiglian c substage are interpreted as having formed during the onset of crevassing and therefore its significance as a regional climate indicator is discussed we conclude that the extrapolation of the tiglian pollen zones into chronostratigraphical substages is questioned and it is concluded that the chronostratigraphical subdivision of the early pleistocene based on palynological characteristics and palaeobotanical analyses requires reconsideration based on independent dating and land sea record integration

decadal changes in southern ocean ventilation inferred from deconvolutions of repeat hydrographies changes in southern ocean ventilation imprint on dissolved gases nutrients radiocarbon temperature and salinity we deconvolve tracer measurements for the distribution g of times and locations of last ventilation using a maximum entropy approach decadal changes of gare quantified by deconvolving hydrographies measured during the early 1990s and again some 15 years later our analysis reveals coherent changes across the 5 meridional sections analyzed the fraction of water younger than 30 years decreased by 20 decade south of 40 s in circumpolar deep water cdw and increased by 10 decade north of 40 s in subantarctic mode water samw ventilation locations shifted with more water south of 40 s being ventilated north of the subantarctic front these ventilation changes impacted cfc uptake with concentrations south of 40 s less than and north of 40 s higher than expected for steady flow the inferred changes imply increased samw formation and cdw upwelling consistent with strengthened westerly winds

middle miocene mass transport deposits in the southern part of the roer valley graben abstract from the late early miocene onwards a north west propagating delta was built out in the differentially subsiding roer valley graben the lower part of this delta sequence consists of the lignite bearing fine sands and silts of the heksenberg member a maximum flooding surface at the top of a transgressive system tract in the lower part of the delta acted as a shear surface along which the overlying middle miocene deltaic deposits slid downslope forming mass transport deposits seismic events sea level fluctuations and gas charging are considered potential triggers for slope failure the past presence of gas might be indicated by high amplitude seismic anomalies in the rotated blocks in the head domain of the mass transport deposits gas could have had a biogenic origin for example from the lignite in the heksenberg member or migrated from deeper sources into the delta

new insight in the tectonics of the southern rhine graben jura region using local earthquake seismology 1 a new seismic data set was acquired using a dense temporary network of mobile seismic stations it is combined with existing seismological data for the southern rhine graben the data yielded some new focal mechanisms and allowed for a detailed local earthquake tomography these methods give new insight in the structure of the crust and stress conditions in the area by combining the tomography with the earthquake hypocenter locations and focal mechanisms some of the structures in the p wave velocity model are interpreted as active faults the eastern boundary fault zone of the graben is found to be activated in a left lateral strike slip sense the southern continuation of these faults is formed by variscan structures in the basement a change in orientation of the graben axis between the main graben and its southern end have played a role during the development of the system this difference in orientation caused the development of the dannemarie and allschwil subbasins during a late stage of the opening of the rhine graben this study shows evidence for active faulting in the basement underneath the detachment of the jura mountains these faults which are interpreted as reactivated permo carboniferous troughs coincide with the frontal thrusts of the jura mountains it might be that these structures in the basement have influence on the detachment tectonics in the region

decoupled extensional faulting and forced folding in the southern part of the roer valley graben belgium abstract during late oligocene incipient rifting the southern part of the roer valley graben was characterized by normal faulting and forced folding of its paleogene pre rift strata the 2d seismic data used in this study shows that these faults and forced folds were geometrically decoupled from faults or fault zones in the underlying triassic and older strata geometric decoupling consistently took place in an interval that comprises latest triassic to early jurassic soft claystones on top of triassic alternations of evaporites and claystones layers this mechanically weak interval probably inhibited the upward propagation of re activated underlying faults resulting in the formation of the observed forced folds monoclines in the overlying paleogene pre rift strata strain from the sub detachment faults was distributed along the mechanically weak interval towards detachment edges leading to the consistent presence of faults in the footwall domain of the supra detachment monoclines the mechanically weak interval was thereby able to maintain the kinematic coherency between geometrically decoupled under and overlying deformation throughout late oligocene rifting

from peat bog to lignite seam a new method to calculate the consolidation coefficient of lignite seams wielkopolska region in central poland only one quantitative method is described in the literature to estimate the consolidation coefficient of lignite seams more studies concentrate on the compaction of plant tissues which explains why the obtained results are overestimated moreover most studies do commonly not determine the consolidation of the whole peat bog but usually those of some of its elements only we propose a new approach which conceptually is fairly close to the hager et al fortschr geol rheinld westf 29 319 352 1981 method our method has been tested on an example of the first middle polish lignite seam and the second lusatian lignite seam from some wielkopolska lignite deposits in central poland the consolidation coefficients cc range between 2 34 and 2 56 for the second lusatian lignite seam and between 1 80 and 2 14 for the first middle polish lignite seam

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

aquisgrani terrae motus factus est part 2 evidence for medieval earthquake damage in the aachen cathedral germany abstract during archaeological and geotechnical investigations the carolingian part of the aachen cathedral germany was excavated the aachen cathedral was the first building in germany to join the unesco world heritage list in the rock walls of the fundament and medieval floors open cracks were found subsidence of the mortar floor of about 50 cm with lateral dragging which was reconstructed during the construction of the cathedral can be observed the main building is founded on devonian limestones and shales pleistocene loess and roman urban debris the loess and loamy sediments show angular cracks and fragments which are not related to permafrost features but are interpreted as shear and extensional fractures some of the cracks are filled with black clay from below as they open downwards these structures are interpreted as injection features caused by thixotropy of clays open cracks lateral spread and injections structures occur usually during earthquakes with a magnitude higher than 5 5 the historical german earthquake catalogues provide three important passages for historical earthquakes in the region of aachen both fall into a relatively short time interval one occurred in winter 803 ad another one in 823 ad and the last one in 829 ad between ash wednesday and easter both notes tell of earthquake shaking and significant structural damage and fatalities this and the constructional history allowed dating of the event favouring the 803 ad event as the causative damaging earthquake observed in the aachen cathedral

how much deep water is formed in the southern ocean three tracers are used to place constraints on the production rate of ventilated deep water in the southern ocean the distribution of the water mass tracer po4 phosphate star in the deep sea suggests that the amount of ventilated deep water produced in the southern ocean is equal to or greater than the outflow of north atlantic deep water from the atlantic radiocarbon distributions yield an export flux of water from the north atlantic which has averaged about 15 sv over the last several hundred years cfc inventories are used as a direct indicator of the current production rate of ventilated deep water in the southern ocean although coverage is as yet sparse it appears that the cfc inventory is not inconsistent with the deep water production rate required by the distributions of po4 and radiocarbon it has been widely accepted that the major part of the deep water production in the southern ocean takes place in the weddell sea however our estimate of the southern ocean ventilated deep water flux is in conflict with previous estimates of the flux of ventilated deep water from the weddell sea which lie in the range 1 5 sv possible reasons for this difference are discussed

response of southern ocean ventilation to changes in midlatitude westerly winds abstractchanges in ventilation of the southern hemisphere oceans in response to changes in midlatitude westerly winds are examined by analyzing the ideal age tracer from global eddy permitting ocea

estimating changes in ocean ventilation from early 1990s cfc 12 and late 2000s sf6 measurements transient tracer measurements can constrain the rates and pathways of ocean ventilation and act as proxies for biogeochemically relevant gases such as co2 and oxygen various techniques have deduced changes in ocean ventilation over decadal timescales using transient tracer measurements made on repeat sections but these require a priori assumptions about mixing in the ocean interior here we introduce a simple direct observational method that takes advantage of the similar atmospheric increase rates of chlorofluorocarbon 12 and sulfur hexafluoride but with a time lag offset of 1415 years such repeat measurements can be directly compared without prior assumptions about mixing a difference larger than similar to 2 years between modern sulfur hexafluoride and historical chlorofluorocarbon 12 tracer ages implies a change in ventilation although lack of difference does not necessarily imply no change several tracer data sets are presented which suggest changes in ventilation in the south pacific and north atlantic oceans

slab breakoff a model for syncollisional magmatism and tectonics in the alps slab breakoff is the buoyancy driven detachment of subducted oceanic lithosphere from the light continental lithosphere that follows it during continental collision in a recent paper davies and von blanckenburg 1994 have assessed the physical conditions leading to breakoff by quantitative thermomechanical modeling and have predicted various consequences in the evolution of mountain belts breakoff will lead to heating of the overriding lithospheric mantle by upwelling asthenosphere melting of its enriched layers and thus to bimodal magmatism breakoff will also lead to thermal weakening of the subducted crustal lithosphere thereby allowing buoyant rise of released crustal slices from mantle depths in this paper we present a test of this model in the tertiary evolution of the european alps in the alps both basaltic and granitoid magmatism occur between 42 and 25 ma following the closure of oceanic basins by subduction and continental collision the granitoids are now well established to result from mixing of basalt with assimilated continental crust to identify the tectonically crucial origin of the partial mantle melts we have compiled all published geochemical and isotopic data of numerous mafic dykes occurring throughout the whole alpine arc their trace element and isotopic composition suggests that they have been formed by low degree melting of the mechanically stable lithospheric mantle we see no evidence for melting of asthenospheric mantle it was thus not decompressed to depths shallower than 50 km once initiated rapid lateral migration of slab breakoff will result in a linear trace of magmatism in locally thermal weakened crust this explains why all alpine magmatic rocks intruded almost synchronously along a strike slip fault the periadriatic lineament a compilation of ages from penninic high pressure rocks subducted to depths of up to 100 km shows that subduction took place at circa 55 40 ma followed by uplift at 40 35 ma from the short time interval between their uplift and the onset of magmatism we infer that both processes have been induced by the breakoff the slab breakoff model fulfills its predictions in the case of the alps and therefore supports the assumptions made in the theoretical model on a geological basis we believe that the characteristic association of magmatic activity with the return of high pressure rocks to the surface allows the identification of this process in the earth s mountain belts

the south scandinavian crust structural complexities from seismic reflection and refraction profiling abstract pioneering work on mapping the scandinavian crust commenced in the early 1960s and since then numerous profiling surveys have been undertaken particularly as part of the on going eugeno s project however the most significant contribution to mapping crustal structural details came from the m v mobil search cruises in the skagerrak and off the west coast of norway 16 s twt reflection profiling all past and present crustal profiling results have been integrated to produce detailed maps of moho depths and crustal thicknesses for south scandinavia the thinnest crust is found in the north sea and skagerrak approximately 20 km while east central sweden features very thick crust approximately 50 km other interesting features are the apparent correlation between crustal thinning and sedimentation subsidence magmatic activity earthquake occurrences and the tectonic age of the crust moho depths and the crustal thicknesses clearly reflect the tectonic evolution and the present structural features of the region investigated

centrifuge modelling of the influence of crustal fabrics on the development of transfer zones insights into the mechanics of continental rifting architecture abstract centrifuge analogue experiments are used to model the reactivation of pre existing crustal fabrics during extension the models reproduced a weakness zone in the lower crust whose geometry was varied in order to investigate its role in controlling the architecture of rift segments and related transfer zones the typical rift system geometry was characterised by two offset rift segments connected by a major transfer zone in which boundary faults were oblique to the extension vector and displayed a significant transcurrent component of movement the transfer zone was also characterised by cross basin faults with both trend and strike slip component of movement opposite to that displayed by the master faults typically different structural patterns were obtained by changing the offset angle between the rift segments supporting that the structural pattern at transfer zones is strongly influenced by the orientation of pre existing discontinuities with respect to the stretching vector in the models the aspect ratio ratio of length vs width of the transfer zone shows a positive correlation with the offset angle i e the more the inherited fabric is parallel to the extension direction the longer and narrower the transfer zones in case of staircase offset of the rift segments 90 the structural pattern was characterised by two isolated rift depressions linked by a narrow transfer zone in which border faults with alternating polarity overlapped prominent rise of the ductile lower crust was also observed at the transfer zone many of these geometrical features display striking similarities with natural rift systems the results of the current experiments provide useful insights into the mechanics of continental rift architecture supporting that rift propagation width and along axis segmentation may be strongly controlled by the reactivation of pre existing pervasive crustal fabrics

episodic activity of a dormant fault in tectonically stable europe the rauw fault ne belgium abstract our knowledge about large earthquakes in stable continental regions comes from studies of faults that generated historical surface rupturing earthquakes or were identified by their recent imprint in the morphology here we evaluate the co seismic character and movement history of the rauw fault in belgium which lacks geomorphological expression and historical present seismicity this 55 km long normal fault with known neogene and possibly early pleistocene activity is the largest offset fault west of the active roer valley graben its trace was identified in the shallow subsurface based on high resolution geophysics all the layers within the late pliocene mol formation 3 6 to 2 59 ma are displaced 7 m vertically without growth faulting but deeper deposits show increasing offset a paleoseismic trench study revealed cryoturbated but unfaulted late glacial coversands overlying faulted layers of mol formation in between those deposits the fault tip was eroded along with evidence for individual displacement events fragmented clay gouge observed in a micromorphology sample of the main fault evidences co seismic faulting as opposed to fault creep based on optical and electron spin resonance dating and trench stratigraphy the 7 m combined displacement is bracketed to have occurred between 2 59 ma and 45 ka the regional presence of the sterksel formation alluvial terrace deposits limited to the hanging wall of the rauw fault indicates a deflection of the meuse rhine confluence 1 0 to 0 5 ma by the fault s activity suggesting that most of the offset occurred prior to at this time interval in the trench sterksel formation is eroded but reworked gravel testifies for its former presence hence the rauw fault appears as typical of plate interior context with an episodic seismic activity concentrated between 1 0 and 0 5 ma or at least between 2 59 ma to 45 ka possibly related to activity variations in the adjacent continuously active roer valley graben

small scale faulting in the upper cretaceous of the groningen block the netherlands 3d seismic interpretation fault plane analysis and regional paleostress abstract over the last years field based studies have shown that fault surfaces can exhibit a considerable self affine topography it is reasonable to assume that similar undulations are also present in fault interpretations from 3d reflection seismic data however both the interpretation uncertainty and geophysical resolution limits hinder their analysis this study analyses a set of small scale non reactivated faults in the upper cretaceous chalk group upper ommelanden formation of the nw part of the groningen block the netherlands in a high quality pre stack depth migrated 3d seismic data set the studied faults are fully contained inside the chalk group in an area located between the major tectonic bounding faults of the nw groningen block over 200 faults with offsets in the order of 30 50 m were interpreted across an area of ca 150 km 2 showing a clear preferential orientation for strike dip and dip direction detailed interpretations and 3d fault plane analyses show undulations on the fault plane we show that these undulations are not an interpretation or gridding artefact and interpret these to indicate direction of fault slip these results were used to calculate a paleostress tensor using all faults to calculate a single stress tensor for the entire study area by numerical dynamic analysis based on the orientation position and a thickness analysis it is interpreted that these faults formed due to the tectonic reactivation of salt structures in the latest cretaceous the calculated paleostress state shows a general nw se extension with a vertical maximum principle stress and a stress ratio of about 0 3 indicating that the studied faults are not the result of dewatering this interpretation agrees both with a nearby salt tectonic reconstruction as well as field based paleostress results from the uk belgium and france a first look at other surveys from the dutch sector indicates that similar faults are present in other areas with different orientations we propose that a dedicated analysis of these faults across on and offshore europe would allow extending the stress map of the late cretaceous into areas where the chalk is not outcropping

interaction between structural inheritance and extension direction during graben and depocentre formation an experimental approach abstract analysis of structural rift architecture shows that the graben formation is commonly controlled by the contemporaneous activity of two fault trends with an angular obliquity of approximately 40 inspection of the crustal basement and geophysical data reveals that these faults are parallel to inherited oblique crustal and lithospheric discrete fabrics which are reactivated during the extension event we conducted experiments at crustal scale to determine the role of the coeval reactivation of such oblique inherited fabrics in the graben and depocentre development experimentally the oblique inherited lithospheric faults were simulated by a basal discrete velocity discontinuity vd characterised by two different angles with respect to the extension direction at the intersection of the vds our models show that besides the extension direction which induces the formation of linear or independent en echelon grabens the intersection of the two oblique vd segments controls the location of the depocentre and concentrates subsidence for different stretching direction values the depocentre geometry varies from strongly asymmetric to symmetric when the stretching direction corresponds to the bisecting line of the two vd segments applied to the upper rhine graben central segment of the west european rift our models allow interpretation of the development of the late eocene oligocene depocentres at the intersection of two main oblique inherited structures as the result of a constant nw se extension direction concerning the southern east african rift the graben geometries and the evolution of the subsidence during the mio pliocene period may be explained by the reactivation of two main pan african inherited shear zones with an e w direction of extension

the deep lithosphere in the alps a model inferred from p residuals abstract the tomographic studies of the alps and their surroundings based on the relative p residuals indicated two lithosphere roots attaining depths over 200 km separated by an upwelling of the lithosphere asthenosphere transition beneath the central part of this mountain range the directional dependence of relative p velocities indicates an anisotropic wave propagation in the subcrustal lithosphere beneath the alps and their surroundings the presented model of the deep lithosphere structure suggests several phases of the tectonic development of this region collision of a tip of the adriatic plate with europe in the eastern alps and dextral strike slip movement of the adriatic ending with underthrusting of europe beneath the western alps and counterclockwise rotation the latter contributes to a steep plunge of both plates beneath the eastern alps and to stress accumulation in the friuli region a model with delamination of the rigid upper crust and its rotation resolves some of the inconsistencies between the near surface and deep tectonics and also explains the distribution of seismicity

determining the maximum overburden along thrust faults using a porosity versus effective confining pressure curve abstract this study aims to quantify the tectonically induced thrusting and erosion here we propose and evaluate a laboratory based method for determining the maximum effective stress ever sustained by a sedimentary rock formation the porosities of nineteen samples collected from two deep boreholes of the taiwan chelungpu fault drilling project were measured under different confining stresses the relation between measured porosity and confining pressure compaction curve is bilinear in log log scale the maximum effective stress of the tested rocks was determined from the intersection point of the two straight lines of the compaction curve the maximum effective stresses of the rocks below the sanyi fault reverse fault are close to the in situ vertical effective stress above the sanyi fault hanging wall where the rocks have been thrust the maximum effective stresses of the rocks are significantly greater than the in situ stress with an average value of 29 48 mpa that is the eroded thickness of the formation on the hanging wall of the sanyi fault is 2482 m a value close to that determined from the geological profile 2773 m it is inferred that the total displacements along the thrust sanyi fault is 11 5 km a value close to that determined from the geological profile 14 16 km these results indicate that the proposed laboratory based method is potentially useful for determining the thrusting and erosion in a fold thrust belt and the total displacements along a thrust fault

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

skagerrak graben the offshore continuation of the oslo graben abstract new seismic mapping of skagerrak reveals eight structural provinces in particular the skagerrak graben appears to be the continuation of the oslo graben the skagerrak graben is defined by two major late paleozoic faults trending northeast southwest connecting with the faults bounding the oslo graben extensive rotated block faulting is observed within the graben and a thickness of more than 2 s twt of lower paleozoic sediments has been preserved along the boundary faults sediments of probable late paleozoic age have been deposited as erosional products from the fault scarps and a central uplifted area a substantial part of these sediments may have a volcaniclastic origin the skagerrak graben continues to the north as a province of igneous rocks exposed at the sea floor with precambrian basement on either side the skagerrak graben is flanked by small half grabens containing probable early paleozoic sediments indicating that a wider area was involved in the rift process the formation of the skagerrak graben is related to the dextral strike slip movements along the sorgenfrei tornquist zone in late paleozoic time the kimmerian extensional movements along this zone indicate however a decoupling of the skagerrak graben at this time only minor inversion in the southwestern part of the skagerrak graben reflects the major inversion tectonism along the sorgenfrei tornquist zone in late cretaceous early tertiary times

a new multilayered model for intraplate stress induced differential subsidence of faulted lithosphere applied to rifted basins in plane horizontal stresses acting on predeformed lithosphere induce differential flexural vertical motions a high precision record of these motions can be found in the sedimentary record of rifted basins originally it was proposed that rifted basins experience flank uplift and basin center subsidence in response to a compressive change of in plane stress which agrees well with observed differential motions subsequently published models predicted that the vertical motions may be opposite because of the flexural state of the lithosphere induced by necking during extension however the total flexural and permanent geometry of the lithosphere underlying the rifted basin is the controlling parameter for the in plane stress caused vertical motions the largest part of this preexisting geometry is caused by faulting in the uppermost brittle part of the crust and ductile deformation in the underlying parts of the lithosphere we present a new multilayered model for stress induced differential subsidence taking into account the technically induced preexisting geometry of the lithosphere including faults in the upper crust as continental lithosphere may exhibit flexural decoupling due to a weak lower crustal layer the new multilayer in plane stress model discriminates the geometries of the separate competent layers at a basin wide scale the new model predicts that a compressive change of in plane force results in basin center subsidence and flank uplift confirming the original hypothesis compared to all previous models the new model requires a lower horizontal stress level change to explain observed differential vertical motions

transient response of the southern ocean to changing ozone regional responses and physical mechanisms abstractthe impact of changing ozone on the climate of the southern ocean is evaluated using an ensemble of coupled climate model simulations by imposing a step change from 1860 to 2000 conditions response functions associated with this change are estimated the physical processes that drive this response are different across time periods and locations as is the sign of the response itself initial cooling in the pacific sector is driven not only by the increased winds pushing cold water northward but also by the southward shift of storms associated with the jet stream this shift drives both an increase in cloudiness resulting in less absorption of solar radiation and an increase in net freshwater flux to the ocean resulting in a decrease in surface salinity that cuts off mixing of warm water from below a subsurface increase in temperature associated with this reduction in mixing then upwells along the antarctic coast producing a subsequent warming similar changes in convective activity occur

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

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

la icp ms u pb zircon timescale constraints of the pleistocene latest magmatic activity in the sancy stratovolcano french massif central abstract it has been demonstrated for several years that the u pb zircon system can provide useful dating information for understanding the time evolution of the volcanic systems in addition in situ techniques were successfully used for determining the formation age of young pliocene and pleistocene volcanic rocks and to record the spatial and temporal distribution and the lifetime evolution of the magma chambers generally in the case of large volcanic domains here we show that it is possible to obtain a precision at the percent level on zircon from a short size and late volcanic event from the sancy stratovolcano french massif central la icp ms dating of pleistocene magmatic zircons allow to distinguish the timescale of these late magmatic events within the complex volcanic activity of this large stratovolcano a syenite xenolith enclosed into a trachyte pumice flow were dated at 277 6 3 2 ka and 260 1 3 6 ka respectively whereas an earlier trachyandesite dome was emplaced at 284 4 4 2 ka these different ages allow to propose a minimum evolution time of about 24 8 kyrs for a differentiated magma chamber which corresponds to a short lifetime associated with low magma volumes the duration of this discrete volcanic event should be compared to the hundreds of thousands of years reported for the large volcanic systems interestingly the zircon crystals from the pumices were embedded into a thin layer of glass of trachytic composition demonstrating that these zircons crystallized into the melt only a short time before eruption

the tectonic evolution of the southern dutch north sea during the palaeogene basin inversion in distinct pulses abstract in this paper we discuss the response of a sedimentary basin to compressional reactivation of extensional faults in distinct pulses the inversion of the broad fourteens basin in the southern dutch north sea is used as a case study the first pulse of inversion occurred during the late mesozoic as a result of the sub hercynean phase a second pulse occurred during the mid palaeocene laramide phase a final inversion pulse occurred around the eocene oligocene boundary coinciding with the pyrenean tectonic event we reconstructed the stratigraphic and structural development of the area during the palaeogene in detail basic data are two 2d seismic surveys supported by 74 geophysical wireline logs on which newly constructed depth and thickness maps are based the reconstruction is aided by a quantitative subsidence analysis cessation of compression resulted in relaxation and tensional reactivation of faults caused differential subsidence inheritance of geological structures is a key element in the tectonic activity in the broad fourteens basin during the palaeogene tectonic movement during the palaeogene was always accommodated by reactivation of palaeozoic mesozoic faults the intensity of inversion in the southern north sea basin during the pyrenean phase appears much larger than previously noticed moreover the area affected by the inversion is much wider than during previous phases minor differences in the direction of the local stress field between the tectonic phases and by the deposition of a thick sedimentary succession during the periods of tectonic quiescence between the inversion phases can account for this

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

gravity evidence for an alpine buckling of the crust beneath the paris basin abstract the processing of the gravity data of the paris basin has enlightened the existence of crustal ridges these ridges correspond to the zones of different crustal thicknesses in plan view the ridges are concentric with the alpine orogen and were probably controlled by this tertiary alpine mountain building the thinned zones related with the mesozoic and pre mesozoic basins were already existing before the alpine deformations these are of limited size and clearly associated with the basins on a large scale two different domains have been recognized the first one corresponds with a zone where the crust is 37 km thick it is also the place where the tertiary depocentres developed the second one relates with a zone where the crust is 29 30 km thick it has been uplifted during the alpine orogeny these two observations suggest the existence of a tertiary lithospheric buckling beneath the paris basin