geophysical geological transect and tectonic evolution of the swiss italian alps a complete alpine cross section integrates numerous seismic reflection and refraction profiles across and along strike with published and new field data the deepest parts of the profile are constrained by geophysical data only while structural features at intermediate levels are largely depicted according to the results of three dimensional models making use of seismic and field geological data the geometry of the highest structural levels is constrained by classical along strike projections of field data parallel to the pronounced easterly axial dip of all tectonic units because the transect is placed close to the western erosional margin of the austroalpine nappes of the eastern alps it contains all the major tectonic units of the alps a model for the tectonic evolution along the transect is proposed in the form of scaled and area balanced profile sketches shortening within the austroalpine nappes is testimony of a separate cretaceous age orogenic event west directed thrusting in these units is related to westward propagation of a thrust wedge resulting from continental collision along the meliata hallstatt ocean further to the east considerable amounts of oceanic and continental crustal material were subducted during tertiary orogeny which involved some 500 km of n s convergence between europe and apulia consequently only a very small percentage of this crustal material is preserved within the nappes depicted in the transect postcollisional shortening is characterized by the simultaneous activity of gently dipping north directed detachments and steeply inclined south directed detachments both detachments nucleating at the interface between lower and upper crust large scale wedging of the adriatic or apulian lower crust into a gap opening between the subduced european lower crust and the pile of thin upper crustal flakes alpine nappes indicates a relatively strong lower crust and detachment between upper and lower crust

the eastern jura relations between thin skinned and basement tectonics local and regional the thesis area of hans cloos in the eastern jura straddles the boundary between the paleogene structures of the tabular jura a part of the southeastern end of the rhine graben and the neogene folds and thrusts of the folded jura a recent reflection seismic survey in the area adjacent to the east provides new information on the subsurface structure and the relation between three superposed tectonic events the main boundary fault zones of a deep and complexly faulted late paleozoic trough trending ene were reactivated in the early tertiary faulted flexures and small folds rooted in the basement and paleozoic with an amplitude of usually 100 to 300 m were produced rather than the normal faults typical for the extensional fields of the rhine bresse graben system in the west and the bavarian molasse basin in the east this suggests their being part of a transform zone between these extensional fields during jura decollement in the neogene these inherited deeply rooted sub decollement structures remained passive their small size is kinematically incompatible with the intense subsequent thrusting and folding of the thin mesozoic tertiary skin however thrust ramps were apparently nucleated at the respective southern foot of these paleogene flexures and folds the best defined and simplest of these composite structures is the mandach structure within the tabular jura a south facing flexure of about 300 m relief developed in the paleogene by reactivation of the northern border fault zone of the paleozoic trough in the neogene a north vergent decollement thrust which is connected with the regional jura decollement in the middle triassic evaporites was initiated at its site

dispersal of buoyancy driven flow in porous media with inclined baffles here we explore the effect of a series of low permeability tilted baffles on the ascent of a buoyant fluid injected into a porous rock from a linear well motivated by several industrial processes particularly co2 sequestration we first consider both theoretically and experimentally the dynamics associated with flow past an individual inclined baffle if the incident flux is sufficiently large then a pool of injectate grows beneath the baffle and spills over both ends partitioning the flux but otherwise the injectate only flows over the updip end of the baffle leaving a stagnant zone under the downdip part of the baffle in a multi layered system the flow may then be described using nonlinear recurrence relations based on the flow past an individual baffle using this approach in the particular case in which there is a regular distribution of baffles we show that on a scale greater than individual baffles the flow adjusts to a plume of constant width rising at an angle to the vertical which depends on the geometry of the baffles this constant width plume may be described by an effective directional permeability at angles to the vertical where we find where is the effective permeability of the regions between baffles within the boundaries of this plume the majority of pore space is bypassed indeed the plume scale effective porosity is largely associated with the pools of injectate which collect beneath each baffle we show that since the constant width plume has such a large lateral extent the total pore space occupied by the plume per unit height is larger than for a homogeneous formation furthermore these pools lead to a large surface area between injectate and formation water which enhances the reaction of the injectate with the formation water however we also show that in steady state it may be hard to determine this plume scale effective porosity since the ratio of the effective darcy speed and the effective interstitial speed of the plume only relates to the porosity of the updip part of these pools in which the injectate is flowing

the swiss alps and their peripheral foreland basin stratigraphic response to deep crustal processes 1 this paper gives a synoptic view of the cenozoic evolution of the swiss alps and their northern foreland basin in this orogen deep crustal processes subduction nappe stacking underplating and exhumation are intimately linked with surface processes surface uplift erosion basin formation and basin axis migration within the foreland basin the spatial pattern of subsidence and alluvial fan construction suggests that an increase in flexure of the foreland plate and the creation of relief in the orogen migrated from east to west in the course of collision in the orogen itself crustal thickening involved lower crust of the adriatic margin in the east and the european margin in the west exhumation of upper crustal units occurred earlier in the east as compared with the west an adriatic mantle wedge the ivrea body and its associated wedge of lower crustal material are identified as an extra lithospheric load which contributed to downward flexure of the european plate as a result of enhanced subsidence of the foreland plate relief was generated presumably in order to adjust to critical taper geometry it appears therefore that the westward motion of the adriatic wedge ultimately caused the contemporaneous westward propagation of the location of enhanced rates of alluvial fan construction coeval strike slip and n s convergence juxtaposed the adriatic wedge sequentially to different european upper crustal units which resulted in different styles of crustal structure and evolution along strike within the orogen

permian continental basins in the southern alps italy and peri mediterranean correlations the late carboniferous to permian continental successions of the southern alps can be subdivided into two main tectono sedimentary cycles separated by a marked unconformity sealing a middle permian time gap generally estimated at over 10 ma the lower cycle 1 between the variscan crystalline basement and the early permian is mainly characterised by fluvio lacustrine and volcanic deposits of calc alkaline acidic to intermediate composition which range up to a maximum thickness of more than 2 000 m the upper cycle 2 which is devoid of volcanics is mostly dominated through the mid late permian by alluvial sedimentation which covered the previous basins and the surrounding highs giving rise to the subaerial verrucano lombardo val gardena groden red beds up to about 800 m thick the palaeontological record from the terrigenous deposits of both the above cycles consists mainly of macro and microfloras and tetrapod footprints the age of the continental deposits is widely discussed because of the poor chronological significance of a large number of fossils which do not allow reliable datings however some sections are also controlled by radiometric calibrations the comparison with some selected continental successions in southern europe allows to determine their evolution and set up correlations a marked stratigraphic gap shows everywhere between the above mentioned cycles 1 and 2 as in the southern alps the gap reaches the greatest extent during the mid permian near the illawarra reversal geomagnetic event 265 ma in western europe however such as in provence and sardinia the discussed gap persists upwardly to late permian and early triassic or slightly younger times i e to the onset of the alpine sedimentary cycle even though in northeastern spain iberian ranges balearic islands this gap results clearly interrupted by late guadalupian lopingian deposits the above two major tectonosedimentary cycles reflect in our view two main geodynamic events that affected the southern europe after the variscan orogenesis the late carboniferous early permian transformation of the gondwana eurasia collisional margin into a diffuse dextral transform margin and the middle late permian opening of the neotethys ocean with the onset of a generalised extensional tectonic regime and the progressive westward marine ingression

on the use of seismic data to monitor the injection of co2 into a layered aquifer abstract one method to monitor the migration of co2 through a confined layered aquifer is to use time lapse seismic reflection data we examine how such information may be combined with a flow model for a co2 plume spreading through a water saturated aquifer to provide constraints on the migration of a plume of injected co2 we focus on the estimation of the partitioning of the injected flux between the different layers in a multi layer geological formation and on estimation of the permeability of each layer since there is a minimum depth of the injected co2 which is detectable seismically we show that even in a one layer formation the model predicts two different possible permeabilities for the formation corresponding to a fast pressure driven flow and a slower buoyancy controlled flow these two estimates of the permeability are sensitive to changes in the seismic detection threshold if there is additional data on the bottom hole well pressure we can distinguish between the solutions in a multi layer system supplied from a single well the non uniqueness in the inversion process leads to uncertainty in both the partitioning of the flux between the layers and the permeability of the different layers in the formation the model constraints lead to a relatively small range of possible distributions of the flux but if there is a lack of information about the relative pressure in the different layers near the well there is a much larger range of possible values for the permeability of each layer we develop some simple bounds on the problem by considering the case in which the near well pressure difference between the layers is related to either the vertical hydrostatic or the vertical co2 static pressure difference we examine the implications of the technique for interpreting the historic data set relating to co2 injection at the sleipner field north sea in which there are nine distinct layers in the formation this leads to estimates for the possible flux partitioning between the layers and also some constraints on the possible range of effective permeability in each layer estimates of the partitioning of the flux can inform estimates of the efficiency of co2 injection in the different layers however the uncertainty in the estimate of the effective permeability leads to uncertainty in estimates of the propagation speed of the flow in each layer and hence assessments of the hazards of leakage and of the rate of capillary trapping or dissolution of co2 following injection

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

thermal history of the westernmost eastern alps penninic rhenodanubian flysch nappes helvetic nappes and subalpine molasse thrust sheets the frontal part of the westernmost eastern alps comprises from top to bottom of the austroalpine and penninic nappes ultrahelvetic slices and two helvetic thrust sheets thrust upon the northern alpine molasse basin the thermal evolution of the penninic rhenodanubian flysch nappes the helvetic nappes and the allochthonous part of the alpine molasse basin is constrained by vitrinite reflectance measurements and apatite fission track dating and implemented in a tectonic evolution scheme within the helvetic nappes vitrinite reflectance increases regionally from north to south and stratigraphically from the campanian maastrichtian wang formation to the toarcian mols member apatite fission track ages from penninic and subalpine molasse units are consistently younger than the deposition age they indicate therefore a post depositional thermal overprint exceeding approximately 120 c the upper temperature limit of the apatite partial annealing zone 1d thermal modelling suggests that the penninic nappes attained deepest burial between the latest cretaceous and early palaeocene with the penninic basal thrust being located at approximately 8 km in the north compared to approximately 12 km in the south deepest burial of the upper helvetic nappe occurred between the latest eocene and early miocene its base was buried down to approximately 10 5 km in the north compared to 11 5 km in the south exhumation of the entire nappe stack started in the early to middle miocene for both penninic and helvetic models a heatflow minimum during the cenozoic deformation max 27 32 mw m2 followed by an increase from the middle miocene onwards up to 60 mw m2 was assumed

gravity currents with residual trapping motivated by geological carbon dioxide co 2 storage we present a vertical equilibrium sharp interface model for the migration of immiscible gravity currents with constant residual trapping in a two dimensional confined aquifer the residual acts as a loss term that reduces the current volume continuously in the limit of a horizontal aquifer the interface shape is self similar at early and at late times the spreading of the current and the decay of its volume are governed by power laws at early times the exponent of the scaling law is independent of the residual but at late times it decreases with increasing loss owing to the self similar nature of the current the volume does not become zero and the current continues to spread in the hyperbolic limit the leading edge of the current is given by a rarefaction and the trailing edge by a shock in the presence of residual trapping the current volume is reduced to zero in finite time expressions for the up dip migration distance and the final migration time are obtained comparison with numerical results shows that the hyperbolic limit is a good approximation for currents with large mobility ratios even far from the hyperbolic limit in gently sloping aquifers the current evolution is divided into an initial near parabolic stage with power law decrease of volume and a later near hyperbolic stage characterized by a rapid decay of the plume volume our results suggest that the efficient residual trapping in dipping aquifers may allow co 2 storage in aquifers lacking structural closure if co 2 is injected far enough from the outcrop of the aquifer

draining viscous gravity currents in a vertical fracture we consider the flow of instantaneous releases of a finite volume of viscous fluid in a narrow vertical fracture or hele shaw cell when there is a still narrower vertical crack in the horizontal base of the cell the predominant motion is over the horizontal surface but fluid also drains through the crack progressively diminishing the volume of the current in the fracture when the crack is shallow on the scale of the current it saturates immediately with the draining fluid in this case we obtain an exact analytical solution for the motion when the crack is deeper and does not saturate immediately we calculate numerically the motion of the fluid in both the fracture and the crack in each case the current advances to a finite run out length and then retreats we describe both phases of the motion and characterize the run out length in terms of the controlling parameters

modeling leakage pathways in subsurface formations fluid drainage through multiple fractures in porous media insights from hele shaw cell experiments abstract arresting the recent observed warming of the earth s climate is a challenge requiring the reduction of anthropogenic emissions of carbon dioxide one option for reducing emissions into the atmosphere is to capture and sequester the released carbon dioxide in geological formations however potential geological storage first requires a risk assessment of carbon dioxide escaping to overlying layers and back to the atmosphere through leakage pathways in the formation this in turn requires an understanding of fluid flow through the leakage pathways in this study the effect of leakage pathways on the flow of a gravity current was investigated using an analogue system a hele shaw cell fluid was introduced through the top edge of the cell and flowed out through one or more holes in its impermeable base the height of the accumulated fluid above the base of the cell at various points along its length and the outflow rate of fluid through the holes was measured this measurement was conducted with varying conditions of the location number and strength of source as well as the location and number of holes at steady state the fluid motion was in accordance with darcy s law for horizontal flow in a long thin current in another set of experiments in which inflow was stopped and the fluid was allowed to drain out of a single open hole the outflow rate was in accordance with darcy s law for one dimensional flow in the vertical direction until the fluid height above the hole fell below a certain limit this threshold height was found to be 1 3 cm which was similar in magnitude to the length of the hole a time series of photographs tracked the flow of colored dye the photographs demonstrated that at steady state the fluid traveled for some distance beyond the hole before draining through it this implies that contaminants may be transported in a formation even beyond an outlet before finally draining out through it the photographs also documented the shape of the interface between the newly introduced dye and the ambient fluid in the cell these shapes were found to be different in a cell placed horizontally versus one placed on an incline suggesting that the geometry and flow conditions in a formation affecting the transport of an injected fluid these findings may be used as a basis for predicting behavior of a fluid injected into a fractured formation in the subsurface

the strain dependent spatial evolution of garnet in a high pressure ductile shear zone from the western gneiss region norway a synchrotron x ray microtomography study reaction and deformation microfabrics provide key information to understand the thermodynamic and kinetic controls of tectono metamorphic processes however they are usually analysed in two dimensions omitting important information regarding the third spatial dimension we applied synchrotron based x ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite garnet eclogite in four dimensions where the 4th dimension is represented by the degree of strain in the investigated samples which cover a strain gradient into a shear zone from the western gneiss region norway we focused on the spatial transformation of garnet coronas into elongated garnet clusters with increasing strain the microtomographic data allowed quantification of garnet volume shape and spatial arrangement evolution with increasing strain the microtomographic observations were combined with light microscope and backscatter electron images as well as electron microprobe empa and electron backscatter diffraction ebsd analysis to correlate mineral composition and orientation data with the x ray absorption signal of the same mineral grains with increasing deformation the garnet volume almost triples in the low strain domain garnet grains form a well interconnected large garnet aggregate that develops throughout the entire sample we also observed that garnet coronas in the gabbros never completely encapsulate olivine grains in the most highly deformed eclogites the oblate shapes of garnet clusters reflect a deformational origin of the microfabrics we interpret the aligned garnet aggregates to direct synkinematic fluid flow and consequently influence the transport of dissolved chemical components ebsd analyses reveal that garnet shows a near random crystal preferred orientation that testifies no evidence for crystal plasticity there is however evidence for minor fracturing neo nucleation and overgrowth microprobe chemical analysis revealed that garnet compositions progressively equilibrate to eclogite facies becoming more almandine rich we interpret these observations as pointing to a mechanical disintegration of the garnet coronas during strain localization and their rearrangement into individual garnet clusters through a combination of garnet coalescence and overgrowth while the rock was deforming

spatial and temporal evolution of injected co2 at the sleipner field north sea time lapse three dimensional 3d seismic surveys have imaged an accumulation of injected co 2 adjacent to the sleipner field in the north sea basin the changing pattern of reflectivity suggests that co 2 accumulates within a series of interbedded sandstones and mudstones beneath a thick caprock of mudstone nine reflective horizons within the reservoir have been mapped on six surveys acquired between 1999 and 2008 these horizons have roughly elliptical planforms with eccentricities ranging between two and four in the top half of the reservoir horizon areas grow linearly with time in the bottom half horizon areas initially grow linearly for about eight years and then progressively shrink the central portions of deeper reflective horizons dim with time amplitude analysis of horizons above within and below the reservoir show that this dimming is not solely caused by acoustic attenuation instead it is partly attributable to co 2 migration and or co 2 dissemination which reduce the impedance contrast between sandstone and mudstone layers growth characteristics and permeability constraints suggest that each horizon grows by lateral spreading of a gravity current this model is corroborated by the temporal pattern of horizon velocity pushdown beneath the reservoir horizon shrinkage may occur if the distal edge of a co 2 filled layer penetrates the overlying mudstone if the buoyant plume draws co 2 upward or if the effective permeability of deeper mudstone layers increases once interstitial brine has been expelled topographic control is evident at later times and produces elliptical planforms especially toward the top of the reservoir our results show that quantitative mapping and analysis of time lapse seismic surveys yield fluid dynamical insights which are testable shedding light on the general problem of co 2 sequestration

an inverse method for estimating thickness and volume with time of a thin co2 filled layer at the sleipner field north sea migration of co 2 through storage reservoirs can be monitored using time lapse seismic re ection surveys at the sleipner field injected co 2 is distributed throughout nine layers within the reservoir these layers are too thin to be seismically resolvable by direct measurement of the separation between re ections from the top and bottom of each layer here we develop and apply an inverse method for measuring thick ness changes of the shallowest layer our approach combines di erences in traveltime down to a speci c re ection together with amplitude measurements to determine layer thicknesses from time lapse surveys a series of synthetic forward models were used to test the robustness of our inverse approach and to quantify uncertainties in the absence of ambient noise this approach can unambiguously resolve layer thickness if a realistic ambient noise distribution is included layer thicknesses of 1 6 m are accurately retrieved with an uncertainty of 0 5 m we used this approach to generate a thickness map of the shallowest layer the delity of this result was tested using measurements of layer thickness determined from the 2010 broadband seismic survey the calculated volume of co 2 within the shallowest layer increases at a rate that is quadratic in time despite an approximately constant injection rate into the base of the reser voir this result is consistent with a diminished growth rate of the areal extent of underlying layers finally the relationship between caprock topography and layer thickness is explored and potential migration pathways that charge this layer are identi ed

modelling carbon dioxide accumulation at sleipner implications for underground carbon storage an analytical solution to the equations describing the flow of a buoyant fluid released into a porous medium below a horizontal impermeable boundary is used to model the growth of co2 accumulations beneath thin mudstone beds in the utsira sand reservoir at sleipner in the north sea here supercritical co2 has been injected at a rate of 1 mt yr since 1996 and imaged by time lapse seismic data in 1999 2001 and 2002 the co2 rises as a narrow plume and is partially trapped by a number of thin mudstones before reaching the caprock to the reservoir the radii of the individual layers of trapped co2 increase as the square root of time since initiation as predicted by the modelling for constant input flux however apparent negative initiation times for horizons low in the reservoir suggests that net input fluxes for these layers have decreased with time most probably as the spreading layers have increased their leakage rates accumulation of co2 in the layers higher in the reservoir was initiated up to 3 yr after injection started modelling of the thickness profiles across three of the higher layers suggests that their net input fluxes have increased with time the observation that the central thicknesses of the deeper layers have remained approximately constant or have slightly decreased since first imaged in 1999 is consistent with the model predictions that the central thickness is directly proportional to net input flux however estimates of the permeability of the reservoir from the rate of increase of the radii of the co2 accumulations are an order of magnitude less than measured permeabilities on the reservoir sandstone permeabilities estimated from the modelling of layer thickness changes scatter in the same range these discrepancies may arise from 1 approximations in the model not being valid 2 the measured permeabilities not being representative of the permeability for two phase flow on the scale of the reservoir or considered less likely 3 that much less co2 is being stored in the imaged co2 accumulations than estimated from the seismic reflection profiles the most probable cause of the discrepancy is that the relative permeability for the co2 phase is significantly reduced at lower co2 saturations

the alpine nappe stack in western austria a crustal scale cross section based on an n s oriented crustal scale cross section running east of the rhine valley in vorarlberg western austria we address the alpine nappe stack and discuss the boundary between central and eastern alps for our cross section we used surface geology drillings and reinterpreted seismic lines together with published sections the general architecture of the examined area can be described as a typical foreland fold and thrust belt comprising the tectonic units of the subalpine molasse ultra helvetic penninic and austroalpine nappes these units overthrusted the autochthonous molasse along the south dipping listric alpine basal thrust the european basement together with its autochthonous cover dips gently towards the south and is dissected by normal faults and trough structures the seismic data clearly show an offset not only of the top of the european basement but also of the mesozoic cover and the lower marine molasse this indicates an activity of the structures as normal faults after the sedimentation of the lower marine molasse the subalpine molasse is multiply stacked forming a triangle zone at the boundary with the foreland molasse the shortening within the subalpine molasse amounts to approximately 45 km 67 as deduced from our cross section with the lower marine molasse as a reference the hinterland dipping duplex structure of the helvetic nappes is deduced from surface and borehole data there are at least two helvetic nappes needed to fill the available space between the molasse below and the northpenninic above this is in line with the westerly located nrp20 east transect schmid et al tectonics 15 5 1047 1048 1996 schmid et al the transmed atlas the mediterranean region from crust to mantle 2004 where the two helvetic nappes are separated by the santis thrust yet in contrast to the helvetic nappes in the nrp20 east transect both of our helvetic nappes comprise cretaceous and jurassic strata this change is explained by an eastward down stepping of the santis thrust along a pre existing approximately n s striking lateral ramp bounding an inverted jurassic graben structure below the rhine valley this causes the santis thrust to detach the base cretaceous west of the rhine valley and the base jurassic units east of it this graben controlled change in detachment level leads to the formation of quite different nappe stacks on either side of the rhine valley and a fault controlled appearance of the boundary between the central and eastern alps

the effect of a fissure on storage in a porous medium we consider the two dimensional buoyancy driven flow of a fluid injected into a saturated semi infinite porous medium bounded by a horizontal barrier in which a single line sink representing a fissure some distance from the point of injection allows leakage of buoyant fluid our studies are motivated by the geological sequestration of carbon dioxide co2 and the possibility that fissures in the cap rock may compromise the safe long term storage of co2 a theoretical model is presented that accounts for leakage through the fissure using two parameters which characterize leakage driven both by the hydrostatic pressure within the overriding fluid and by the buoyancy of the fluid within the fissure we determine numerical solutions for the evolution of both the gravity current within the porous medium and the volume of fluid that has escaped through the fissure as a function of time a quantity of considerable practical interest is the efficiency of storage which we define as the amount of fluid remaining in the porous medium relative to the amount injected this efficiency scales like t 1 2 at late times indicating that the efficiency of storage ultimately tends to zero we confirm the results of our model by comparison with an analogue laboratory experiment and discuss the implications of our two dimensional model of leakage from a fissure for the geological sequestration of co2

converging gravity currents over a permeable substrate we study the propagation of viscous gravity currents along a thin permeable substrate where slow vertical drainage is allowed from the boundary in particular we report the effect of this vertical fluid drainage on the second kind self similar solutions for the shape of the fluid fluid interface in three contexts i viscous axisymmetric gravity currents converging towards the centre of a cylindrical container ii viscous gravity currents moving towards the origin in a horizontal hele shaw channel with a power law varying gap thickness in the horizontal direction and iii viscous gravity currents propagating towards the origin of a porous medium with horizontal permeability and porosity gradients in power law forms for each of these cases with vertical leakage we identify a regime diagram that characterizes whether the front reaches the origin or not in particular when the front does not reach the origin we calculate the final location of the front we have also conducted laboratory experiments with a cylindrical lock gate to generate a converging viscous gravity current where vertical fluid drainage is allowed from various perforated horizontal substrates the time dependent position of the propagating front is captured from the experiments and the front position is found to agree well with the theoretical and numerical predictions when surface tension effects can be neglected

modelling carbon dioxide sequestration in layered strata motivated by the geological sequestration of carbon dioxide co2 we study the propagation of gravity currents in a porous medium bounded by a thin layer of much lower permeability we formulate a model for drainage assuming that the fluid remains simply connected throughout using this model we examine the propagation of both two dimensional and axisymmetric currents numerically we find that for the fixed flux situation solutions approach a steady state which is described analytically the approach to this final solution depends on both the permeability contrast and thickness of the thin layer and in many cases the current first overshoots before relaxing back to its ultimate steady state finally we examine propagation along multiple thin lower permeability layers as a reduced order model of the plume of co2 currently being injected at sleipner in the north sea

geometry amount and sequence of thrusting in the subalpine molasse of western austria and southern germany european alps in this paper we review the structure of the most external thrust belt of the alps between the rhein valley and salzburg based on a new tectonic map and the re interpretation of seismic sections specifically we address the correlation between deformation in the subalpine molasse and the alpine thrust belt in general and focus on the control of sedimentary facies on the structural style a dramatic change in architecture from a ramp flat structure to buckle folding is related to a change from coarse grained fans to fine grained deposits within the subalpine molasse additionally the interaction of escape tectonics with postcollisional shortening controls the decrease of late early miocene and younger shortening within the subalpine molasse from 50 km near the rhine valley to almost zero near salzburg transfer of shortening into the hinterland which is the zone of lateral escape ended foreland propagation of the alpine thrusts and initiated a general break back sequence of thrusting throughout this time the thrusts remained active in such a scenario tectonic units on top of the subalpine molasse are expected to undergo clockwise rotation around vertical axes as thrusting in the subalpine molasse is closely related to contemporaneous transport and shortening within the tectonically higher helvetic thrust sheets amounts of miocene differential shortening and related clockwise vertical axis rotation are minimum amounts true clockwise vertical axis rotation is probably larger than the 12 deduced from the subalpine molasse thrust belt

similarity solutions for fluid injection into confined aquifers fluid injection into the deep subsurface such as injection of carbon dioxide co 2 into deep saline aquifers often involves two fluid flow in confined geological formations similarity solutions may be derived for these problems by assuming that a sharp interface separates the two fluids by imposing a suitable no flow condition along both the top and bottom boundaries and by including an explicit solution for the pressure distribution in both fluids when the injected fluid is less dense and less viscous than the resident fluid as is the case for co 2 injection into a resident brine gravity override produces a fluid flow system that is captured well by the similarity solutions the similarity solutions may be extended to include slight miscibility between the two fluids as well as compressibility in both of the fluid phases the solutions provide the location of the interface between the two fluids as well as drying fronts that develop within the injected fluid applications to cases of supercritical co 2 injection into deep saline aquifers demonstrate the utility of the solutions and comparisons to solutions from full numerical simulations show the ability to predict the system behaviour

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

on the slow draining of a gravity current moving through a layered permeable medium we examine the gravitational dispersal of dense fluid through a horizontal permeable layer which is separated from a second underlying layer by a narrow band of much lower permeability we derive a series of analytical solutions which describe the propagation of the fluid through the upper layer and the draining of the fluid into the underlying region the model predicts that the current initially spreads according to a self similar solution however as the drainage becomes established the spreading slows and in fact the fluid only spreads a finite distance before it has fully drained into the underlying layer we examine the sensitivity of the results to the initial conditions through numerical solution of the governing equations we find that for sources of sufficiently large initial aspect ratio defined as the ratio of height to length the solution converges rapidly to the initially self similar regime for longer and shallower initial source conditions this convergence does not occur but we derive estimates for the run out length of the current which compare favourably with our numerical data we also present some preliminary laboratory experiments which support the model

the 3d crustal structure of the alps of eastern switzerland and western austria interpreted from a network of deep seismic profiles abstract a 3d crustal model of the alps of eastern switzerland and western austria was constructed a total of twenty two dimensional deep seismic reflection profiles recorded between 1986 and 1991 were two dimensionally interpreted based on depth migrated line drawings and using correlation with surface geology refraction derived velocity depth models and correlation with intersecting or neighboring profiles the network of crustal cross sections was then unified into 3d surfaces this analysis was restricted to four crustal discontinuities 1 the top of the european basement first european basement unit including the foreland encountered going downward from the topographic surface 2 the top of the lower crust 3 the top of the european moho transition zone and 4 the european moho simulation of the seismic profiles using 3d normal incidence and shot ray tracing enabled the quantification and correction of distortions caused by out of plane reflected energy the inferred 3d crustal configuration is likely the result of the latest phase of alpine shortening during the late tertiary it depicts a smooth sse dipping european moho overlain by a concordant lower crust in the external alpine domain and a presumably wedge shaped body of lower crust in the internal alpine domain in contrast to the lower crustal discontinuities the top of the european basement reveals a highly structured 3d geometry dominated by thrust tectonics the pronounced structural disharmony with respect to the lower crust implies an intracrustal decoupling mechanism during the formation of the external basement uplifts with the zone of decoupling possibly located near the top of the lower crust comparison of the top basement topography with the mapped surface geology indicates a close relation between the basement geometry and the shape of the austroalpine basal thrust delineating the prattigau halfwindow in the west and the engadine window in the east

structural synthesis of the northern calcareous alps transalp segment the northern calcareous alps nca are the site of very large top to north convergent movements during cretaceous tertiary alpine mountain building to determine the amount of shortening the depth of detachment and the style of deformation we retro deformed an approximately 40 40 km area comprising the lechtal and allgau nappes on the basis of all available geological data and processed sections of the transalp reflection seismic experiment coherent 3d models were constructed by splining lines from n s cross sections integration of 3d kinematic modeling and field data shows the following the structure of the lechtal nappe is controlled by the triassic hauptdolomit four main thrusts link to a detachment at 2 6 km depth below sea level shortening estimates vary from 25 east to 42 west additional contraction is accommodated by folding in the east the subjacent allgau nappe can be traced about 10 km down plunge and is shortened by about one third in the western part the downplunge width is at least 15 20 km with restorable shortening of one third the triple inntal lechtal allgau nappes nca nappe system was moved uniformly n s to produce laterally heterogeneus shortening of 40 90 km or 50 67 we suggest that the nca are underlain by substantial amounts of buried molasse sediments and or overthrust units of helvetic and rheno danubian flysch indicating post eocene n s shortening of at least 55 km restored to an initial configuration the basin topography of the nca reveals strong e w thickness variations of the triassic wettersteinkalk and hauptdolomit platform carbonates such variations may pertain to n s trending growth faults which were important precursors to later jurassic extension of the austroalpine passive margin such structures are unlikely to be seen in the conventional n s cross sections but form an essential geometrical and mechanical element in later convergent mountain building

on the flow of buoyant fluid injected into a confined inclined aquifer we study the dispersal of a plume of incompressible buoyant fluid injected into a confined sloping aquifer which has an outflow at a single fault which may be up dip up slope or down dip down slope from the point of injection we develop a long time asymptotic solution for the motion of the injected fluid we show that for the case in which the outflow fault is up dip from the point of injection there is a critical injection rate above which the injected fluid floods the full depth of the aquifer and we show that for the case in which the outflow fault is down dip from the point of injection there is a critical injection rate below which all injected fluid initially flows up dip our analysis leads to expressions for the lateral extent of the injected fluid as a function of time and we consider the implications of the model for the dispersal of supercritical carbon dioxide injected into deep saline aquifers the work also indicates that the geometry of the system may have a significant effect on i the total volume of carbon dioxide which it is possible to sequester in a faulted aquifer and ii the interpretation of the dispersed position of any injected tracers

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

leakage from gravity currents in a porous medium part 2 a line sink we consider the propagation of a buoyancy driven gravity current in a porous medium bounded by a horizontal impermeable boundary the current is fed by a constant flux injected at a point and leaks through a line sink at a distance from the injection point this is an idealized model of how a fault in a cap rock might compromise the geological sequestration of carbon dioxide the temporal evolution of the efficiency of storage defined as the instantaneous ratio of the rate at which fluid is stored without leaking to the rate at which it is injected is of particular interest we show that the efficiency of storage decays like t 2 5 for times t that are long compared with the time taken for the current to reach the fault this algebraic decay is in contrast to the case of leakage through a circular sink neufeld et al j fluid mech vol 2010 where the efficiency of storage decays more slowly like 1 ln t the implications of the predicted decay in the efficiency of storage are discussed in the context of geological sequestration of carbon dioxide using parameter values typical of the demonstration project at sleipner norway we show that the efficiency of storage should remain greater than 90 on a time scale of millennia provided that there are no significant faults in the cap rock within about 12 km of the injection site

the palaeozoic evolution in the alps from gondwana to pangea more than 50 of the alps expose fragments of palaeozoic basement which were assembled during the alpine orogeny although the tectonic and metamorphic history of the basement units can be compared to that of the variscan crust in the alpine foreland most of the basement pieces of the alps do not represent the direct southern continuation of variscan structural elements evident in the massif central the vosges black forest or the bohemian massif the basement units of the alps all originated at the gondwana margin they were derived from a precambrian volcanic arc suture fringing the northern margin of gondwana from which they were rifted during the cambrian ordovician and silurian a short lived ordovician orogenic event interrupted the general rifting tendency at the gondwana active margin after the ordovician the different blocks drifted from the gondwana margin to their pangea position colliding either parallel to armorica with laurussia or with originally peri gondwanan blocks assembled presently in armorica from the devonian onwards many basement subunits underwent the complex evolution of apparently oblique collision and nappe stacking docking started in the external massifs the penninic and lower and middle austroalpine units in approximately devonian early carboniferous times followed by the upper austroalpine and the south alpine domains in the visean and the namurian times respectively wrenching is probably the best mechanism to explain all syn and post collisional phenomena since the visean followed by post orogenic collapse and extension it explains the occurrence of strike slip faults at different crustal levels the formation of sedimentary troughs as well as the extrusion and intrusion of crustal and mantle derived magmas and allows for contemporaneous rapid uplift of lower crustal levels and their erosion from the stephanian onwards all regions were deeply eroded by large river systems

the influence of capillary effects on the drainage of a viscous gravity current into a deep porous medium the drainage of a viscous gravity current into a deep porous medium driven by both the gravitational and capillary forces is considered in two steps we first study the one dimensional case where a layer of fluid drains vertically into an infinitely deep porous medium we determine a transition from the capillary driven regime to the gravity driven regime as time proceeds second we solve the coupled spreading and drainage problem there are no self similar solutions of the problem for the entire time period so asymptotic analyses are developed for the height depth and front location in both the early time and the late time periods in addition we present numerical results of the governing partial differential equations which agree well with the self similar solutions in the appropriate asymptotic limits

tectonic style and pressure distribution at the northern margin of the alps between lake constance and the river inn hydrocarbon exploration in the molasse basin and the alpine thrust belt has provided new information on the tectonic structure of the foreland margin of the overthrust belt two n s cross sections show the front of the folded molasse as a so called triangle zone in the area north of the hindelang 1 well bavaria and the sulzberg 1 well vorarlberg the triangle zone was described and defined byjones 1982 for the alberta foothills in canada

spatial patterns of mesozoic facies relationships and the age of the rhenish lineament a compilation the age and the southern continuation of the rhenish lineament and its relation to the bressegraben has been an elusive problem for a long time sedimentological data are presented in this paper which show that a major fault zone associated with the rhenish lineament extends southwards underneath the jura mountains of northern switzerland mesozoic facies boundaries occur along this lineament and indicate that the tertiary upper rhinegraben may be an ancient inherited structure which was repeatedly reactivated during mesozoic time while reactivated paleozoic faults seated in the basement are now known to play an important role in defining east west trending facies boundaries and depocenters north south facies boundaries were attributed to autocyclic effects this north south component found in facies boundaries is now attributed to subsidence variations which took place along the rhenish lineament to distinguish increased local subsidence from eustatic sea level rise i e development of accommodation space it is necessary to reinterpret the sedimentary record accordingly this study demonstrates that some sedimentary facies boundaries follow the rhenish lineament over the paleozoic basins of northern switzerland into the bressegraben thereby indicating an ancient structure which had been reactivated during mesozoic time sedimentological analysis shows that there is a relationship between facies boundaries isopach anomalies and basement structure