dynamic processes of co2 storage in the field 1 multiscale and multipath channeling of co2 flow in the hierarchical fluvial reservoir at cranfield mississippi

shallow gravity driven flow in a poro elastic layer by combining biot s theory of poro elasticity with standard shallow layer scalings a theoretical model is developed to describe axisymmetric gravity driven flow through a shallow deformable porous medium motivated in part by observations of surface uplift around co2 sequestration sites the model is used to explore the injection of a dense fluid into a horizontal deformable porous layer that is initially saturated with another less dense fluid the layer lies between a rigid base and a flexible overburden both of which are impermeable as the injected fluid spreads under gravity the matrix deforms and the overburden lifts up the coupled model predicts the location of the injected fluid as it spreads and the resulting uplift of the overburden due to deformation of the solid matrix in general the uplift spreads diffusively far ahead of the injected fluid if fluid is injected with a constant flux and the medium is unbounded both the uplift and the injected fluid spread in a self similar fashion with the same similarity variable r t1 2 the asymptotic form of this spreading is established results from a series of laboratory experiments using polyacrylamide hydrogel particles to create a soft poro elastic material are compared qualitatively with the predictions of the model

an example of an accretionary forearc basin from northern central anatolia and its implications for the history of subduction of neo tethys in turkey deformed sedimentary sequences of late cretaceous middle eocene age located between the sakarya continent and the anatolian complex have been interpreted as the fill of a forearc basin the history and structure of this basin are critical for understanding the evolution of the neo tethyan subduction in the middle east i test and elaborate upon this interpretation on the basis of three basic outcrop areas of upper cretaceous lower tertiary sedimentary sequences confined to a northeast southwest trending belt in north west ankara these are the alci kinik and orhaniye areas they expose two different sedimentary sequences called alci and orhaniye in the alci area the sequence starts at the base with the continental red clastic rocks on the erosional surface of an underlying ophiolitic melange and continues upward into the shallow marine reefal buildup of the late maastrichtian age the upper half of the alci sequence is separated from its lower half by a local disconformity and dominated by the continental debris flow deposits composed mostly of volcanic material by contrast both the kinik and orhaniye areas are characterized by a thick continuous and coarsening upward sequence overlying conformably the underlying ophiolitic melange the lower half of the orhaniye sequence is dominated by a deep marine flysch its middle part by continental clastic material and the topmost part by the shallow marine reefal buildup lower contact relationships lithologic composition facies distribution internal structures and the regional tectonic settings of both sequences strongly suggest that the above mentioned three outcrops preserve the remnants of a peripheral accretionary forearc basin forming the north northwestern margin of the haymana polath accretionary forearc basin during middle campanian middle eocene time this peripheral basin is here named orhaniye accretionary forearc basin

southward migration of arc magmatism during latest cretaceous associated with slab steepening east pontides n turkey new paleomagnetic data from the amasya region abstract a new paleomagnetic study was carried out on the findikli formation in the amasya region which is to the north of the ankara erzincan neotethyan suture zone in order to better understand the paleogeographic evolution of the pontides tectonic belt during the maastrichtian samples were collected from volcanoclastic sandstones and lavas at 51 sites rock magnetic experiments identified pseudo single domain psd titanomagnetite as the main magnetic carriers at the majority of sites progressive thermal and alternating demagnetization revealed that the characteristic remanent component is removed between 400 and 580 c or 20 100 mt respectively a high temperature component which indicates the presence of titano hematite is found only in some lavas declinations show a systematic dispersion across the study area related to tectonic rotations about vertical axes inclinations are consistent however and yield a mean paleolatitude of 20 0 n 2 5 for the maastrichtian comparison of the results from this study with the reference direction of the east pontides from the turonian campanian is best explained with a model involving slab roll back and marginal basin formation between 90 and 65 ma period

physics and seismic modeling for monitoring co2 storage we present a new petro elastical and numerical simulation methodology to compute synthetic seismograms for reservoirs subject to co2 sequestration the petro elastical equations model the seismic properties of reservoir rocks saturated with co2 methane oil and brine the gas properties are obtained from the van der waals equation and we take into account the absorption of gas by oil and brine as a function of the in situ pore pressure and temperature the dry rock bulk and shear moduli can be obtained either by calibration from real data or by using rock physics models based on the hertz mindlin and hashin shtrikman theories mesoscopic attenuation due to fluids effects is quantified by using white s model of patchy saturation and the wet rock velocities are calculated with gassmann equations by using an effective fluid modulus to describe the velocities predicted by white s model the simulations are performed with a poro viscoelastic modeling code based on biot s theory where viscoelasticity is described by generalizing the solid fluid coupling modulus to a relaxation function using the pseudo spectral method which allows general material variability a complete and accurate characterization of the reservoir can be obtained a simulation that considers the utsira sand of the north sea illustrates the methodology

evidence of late cretaceous oroclinal bending in north central anatolia palaeomagnetic results from mesozoic and cenozoic rocks along the izmir ankara erzincan suture zone

dynamic fluid connectivity during steady state multiphase flow in a sandstone abstract the current conceptual picture of steady state multiphase darcy flow in porous media is that the fluid phases organize into separate flow pathways with stable interfaces here we demonstrate a previously unobserved type of steady state flow behavior which we term dynamic connectivity using fast pore scale x ray imaging we image the flow of n2 and brine through a permeable sandstone at subsurface reservoir conditions and low capillary numbers and at constant fluid saturation at any instant the network of pores filled with the nonwetting phase is not necessarily connected flow occurs along pathways that periodically reconnect like cars controlled by traffic lights this behavior is consistent with an energy balance where some of the energy of the injected fluids is sporadically converted to create new interfaces

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

petrogenesis of collision related plutonics in central anatolia turkey central anatolia exhibits good examples of calc alkaline and alkaline magmatism of similar age in a collision related tectonic setting continent island arc collision in the central anatolia region late cretaceous post collisional plutonic rocks intrude palaeozoic mesozoic metamorphic rocks overthrust by upper cretaceous ophiolitic units to make up the central anatolian crystalline complex in the complex three different intrusive rock types may be recognised based on their geochemical characteristics i calc alkaline behrekdag cefalikdag and celebi ii subalkaline transitional baranadag and ii alkaline hamit the calc alkaline and subalkaline plutonic rocks are metaluminous i type plutons ranging from monzodiorite to granite the alkaline plutonic rocks are metaluminous to peralkaline plutons predominantly a type ranging from nepheline monzosyenite to quartz syenite all intrusive rocks show enrichment in lile and lree relative to hfse and have high 87sr 86sr and low 143nd 144nd ratios these characteristics indicate an enriched mantle source region s carrying a subduction component inherited from pre collision subduction events the tectonic discrimination diagram of rb vs y nb suggests that the calc alkaline subalkaline and alkaline plutonic rocks have been affected by crustal assimilation combined with fractional crystallisation processes the coexistence of calc alkaline and alkaline magmatism in the central anatolian crystalline complex may be attributed to mantle source heterogeneity before collision the former carries a smaller intraplate component and pre subduction enrichment compared to the latter either thermal perturbation of the metasomatised lithosphere by delamination of the thermal boundary layer tbl or removal of a subducted plate slab breakoff is the likely mechanism for the initiation of the post collisional magmatism in the complex

a survey of transverse drainages in the susquehanna river basin pennsylvania abstract although large scale transverse drainages tds such as those of the susquehanna river above harrisburg pa have been recognized since the nineteenth century only two systematic surveys have been published of tds ver steeg 1930 oberlander 1965 a topographic and statistical analysis of tds in the susquehanna river basin using google earth and associated overlays identified 653 tds in the study area 95 of which contain streams with discharges of

noble gas and carbon isotopic evidence for co2 driven silicate dissolution in a recent natural co2 field secure storage of anthropogenic carbon dioxide co2 in geological reservoirs requires predicting gas water rock interactions over millennial timescales noble gases and carbon isotope measurements can be used to shed light on the nature of competing dissolution precipitation processes over different timescales from the fast dissolution of gaseous co2 in groundwater to more sluggish reactions involving dissolution and precipitation of newly formed minerals in the reservoir here we study a compilation of gas analyses including noble gases and 13c of co2 from nine different natural co2 reservoirs amongst these reservoirs the bravo dome co2 field new mexico usa shows distinct geochemical trends which are explained by degassing of noble gases from groundwater altering the composition of the gas phase this groundwater degassing is synchronous with the dissolution of co2 in groundwater progressive creation of alkalinity via co2 promoted mineral dissolution is required to explain the observed positive correlation between co2 3he and 13c of the gas phase a unique feature of bravo dome the differences between bravo dome and other natural co2 reservoirs are likely explained by the more recent filling of bravo dome reflecting co2 water rock interactions over thousands of years rather than over millions of years in older reservoirs

characterization of the magnetic fabric of rocks abstract an inextensive system of magnetic susceptibility anisotropy factors is suggested which is sufficient in the majority of practical applications for characterizing the magnetic fabric of rocks the system involves three newly devised factors the corrected anisotropy degree the shape factor and the difference shape factor the first of these characterizes the quantity of anisotropy somewhat better than the commonly used anisotropy degree the shape factor characterizes the quality of anisotropy i e the shape of the susceptibility ellipsoid in a convenient way its definition is based on a certain analogy between the anisotropy ellipsoid and the strain ellipsoid the difference shape factor can replace the shape factor when only the differences between the principal susceptibilities are given while the mean susceptibility is unknown

paleogeographic setting and depositional architecture of a sand dominated shelf depositional system miocene utsira formation north sea basin abstract the middle late miocene utsira sandstone of the north sea basin contains a fully preserved regional marine sand deposit that records a stable paleogeographic setting of shelf sand transport and accumulation within an epeiric shelf sea which persisted for ca 8 myr the sediment dispersal system was defined by 1 sediment input through a prograding strandplain platform coast to shelf bypass and regional basin centered transport and deposition within an elongate seaway 2 a high energy marine regime 3 very low rates of sediment supply and accumulation in the accommodation dominated seaway 4 high sediment reworking ratio and consequent abundance of autochthonous sediment 5 regional along strike sediment transport and 6 local to subregional landward sediment transport shelf systems were primarily nourished by sediment reworked from the shetland strandplain which prograded eastward into the central viking trough the viking strait lay between the constructional platform and the nondepositional horda platform southward longshore transport on the high energy shoreface and shallow shelf platform constructed the mounded south viking shelf shoal southward building sandy banner banks that formed along the recurved arc of the platform margin nourished the shoal system low angle sigmoid clinoforms with downstepping aggradational tops are distinctive architectures of the strike fed sand bodies the combination of strong marine currents and slow but continual sand supply from the shetland strandplain created regional sandy shelf depositional systems that individually covered 3500 to 6000 sq km of basin floor defining elements of the shelf shoal systems include their location within the basin axis mounded morphology stratal architecture and construction by amalgamated marine sand facies

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

correlation of strain and the anisotropy of magnetic susceptibility in the onaping formation evidence for a near circular origin of the sudbury basin abstract measurements of finite strain the anisotropy of magnetic susceptibility the magnetic carrier of the susceptibility and fieldwork have been carried out in the onaping formation of the sudbury basin ontario the magnetic fabric indicates that changes in the magnitude and type of magnetic susceptibility ellipsoids closely mirror the changing pattern of deformation from northwest to southeast across the onaping formation outcrops a quantitative correlation has been established between finite strain measurements and the magnetic susceptibility results and this allows the number of available strain measurements to be extended by more than 500 samples the finite strain results suggest a deformation path in which the onaping formation was first affected by nw se directed horizontal layer parallel shortening which produced an upright tectonic cleavage subsequently components of overthrust nw directed simple shear were superimposed upon the already deformed rocks of the onaping formation the result of removing the strain according to the sequence of superimposed deformations revealed by the deformation path suggests that the sudbury basin was nearly circular in shape prior to its deformation consequently a major objection to the meteorite impact theory for origin of the sudbury structure is eliminated

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

paleomagnetic reconstruction of the cenozoic evolution of the eastern mediterranean abstract a total of 113 paleomagnetic sites were sampled along an anatolian s n transect from the arabian platform the hatay region the eastern taurides the kirsehir block the sivas basin and the eastern pontides reliable characteristic remanent paleomagnetic directions were retrieved from 37 of these sites spanning in time from paleocene to miocene in a general way declinations are westerly deviated and inclinations are shallower than the geocentered dipole value at the present latitudes when combined with previously published results these data indicate that a large scale counterclockwise rotation of anatolia of some 25 has occurred since the miocene assuming that the pole of rotation of anatolia with respect to europe has remained constant in time at the location given by macclusky et al j geophys res 105 2000 5695 on the basis of the geodetic data this rotation implies that a large westward displacement 500 km at the average latitude of 40 has taken place assuming that the rotation was initiated by the arabia europe collision about 12 ma ago this corresponds to an average displacement of about 40 mm year together with previous results from the western part of the aegean arc these results indicate that the main trends of the cenozoic evolution of the eastern mediterranean appear to consist of two post early miocene rotations of opposite senses a clockwise rotation of the western part of the aegean tectonophysics 146 1988 183 around a pole situated in northern albania and a counterclockwise rotation around the pole given by mcclusky et al j geophys res 105 2000 5695 comparison with gps data suggest that both rotations are still active today

tectonomagmatic evolution of bimodal plutons in the central anatolian crystalline complex turkey abstract the nw trending agacoren intrusive suite ais on the east side of the salt lake tuz golu turkey is part of a curvilinear volcanoplutonic complex along the western edge of the central anatolian crystalline complex cacc granitoids constitute the predominant lithological group within the ais and range in composition from monzonite through granite to alkali feldspar granite gabbroic rocks occur as irregular intrusive bodies with sinusoidal irregular contacts with the granitoid plutons and vary from dioritic compositions at the contacts to cumulate amphibole gabbros in their center these gabbroid to granitoid rocks are all subalkaline and display tholeiitic to calcalkaline affinities respectively modeling of the major element and trace element chemistry of the granitoids to gabbroids together with their field relations suggest that these rocks formed synchronously from a melt source that involved both mantle and crustal components mafic magmas were likely derived from a metasomatized u

vertical axis rotations in fold and thrust belts comparison of ams and paleomagnetic data in the western external sierras southern pyrenees abstract geometry and kinematics of fold and thrust belts can be complex settings when oblique structures and vertical axis rotations var take place during thrust emplacement many techniques can be used to unravel such complex tectonic histories from classic ones like strain analysis and changes of paleocurrents to more modern approaches such as paleomagnetism and calcite twin analysis in this paper anisotropy of magnetic susceptibility is compared to vertical axis rotations deduced from paleomagnetic data along three cross sections in the external sierras and the jaca basin southwestern pyrenees these data enable us to state that 1 ams represents pre tilting deformation fabrics and magnetic lineation behaves like a passive marker during later deformation and 2 a primary record of the paleomagnetic field can be found in the area therefore the difference with the paleomagnetic reference is the local var the comparison of the two datasets allows us to draw the following conclusions a the changes in both paleomagnetic var and magnetic lineation orientation between neighbouring sites are similar and b there is a significant linear regression between var and trend changes in magnetic lineation deviations in magnetic lineation with respect to the expected local magnetic lineation permit vertical axis rotations to be quantified using the ams dataset the combined analysis of paleomagnetic and ams data enables 1 a quicker comparison of the kinematic evolution in areas with similar ams patterns 2 the identification of anomalous orientations of magnetic lineation linked to vars and 3 the use of ams analysis as a homogeneity test for vars determined from other techniques ams is proposed as a suitable preliminary technique to select further sites for paleomagnetic analysis since paleomagnetic laboratory procedures are much more time consuming than ams measurements ams does not usually modify sample remanence and hence samples can be used for both types of analysis

calendar time interpolation of amplitude maps from 4d seismic data a calendar time interpolation method for 2d seismic amplitude maps done in two steps is presented the contour interpolation part is formulated as a quadratic programming problem whereas the amplitude value interpolation is based on a conditional probability formulation the method is applied on field data from the sleipner co2 storage project the output is a continuous image movie of the co2 plume besides visualization the output can be used to better couple 4d seismic to other types of data acquired the interpolation uncertainty increases with the time gap between consecutive seismic surveys and is estimated by leaving a survey out blind test errors from such tests can be used to identify problems in understanding the flow and possibly improve the interpolation scheme for a given case field life cost of various acquisition systems and repeat frequencies are linked to the time lapse interpolation errors the error in interpolated amplitudes increased by 3 4 per year of interpolation gap for the sleipner case interpolation can never fully replace measurements

benchmarking of vertically integrated co2 flow simulations at the sleipner field north sea abstract numerical modeling plays an essential role in both identifying and assessing sub surface reservoirs that might be suitable for future carbon capture and storage projects accuracy of flow simulations is tested by benchmarking against historic observations from on going co2 injection sites at the sleipner project located in the north sea a suite of time lapse seismic reflection surveys enables the three dimensional distribution of co2 at the top of the reservoir to be determined as a function of time previous attempts have used darcy flow simulators to model co2 migration throughout this layer given the volume of injection with time and the location of the injection point due primarily to computational limitations preventing adequate exploration of model parameter space these simulations usually fail to match the observed distribution of co2 as a function of space and time to circumvent these limitations we develop a vertically integrated fluid flow simulator that is based upon the theory of topographically controlled porous gravity currents this computationally efficient scheme can be used to invert for the spatial distribution of reservoir permeability required to minimize differences between the observed and calculated co2 distributions when a uniform reservoir permeability is assumed inverse modeling is unable to adequately match the migration of co2 at the top of the reservoir if however the width and permeability of a mapped channel deposit are allowed to independently vary a satisfactory match between the observed and calculated co2 distributions is obtained finally the ability of this algorithm to forecast the flow of co2 at the top of the reservoir is assessed by dividing the complete set of seismic reflection surveys into training and validation subsets we find that the spatial pattern of permeability required to match the training subset can successfully predict co2 migration for the validation subset this ability suggests that it might be feasible to forecast migration patterns into the future with a degree of confidence nevertheless our analysis highlights the difficulty in estimating reservoir parameters away from the region swept by co2 without additional observational constraints

the origin of neogene tectonic rotations in the galatean volcanic massif central anatolia a paleomagnetic study was carried out on neogene volcanic rocks at 30 sites within the galatean massif 40 4 n 31 5 e to determine possible block rotations due to stress variations two phases of rotation could be characterized as the result of neogene volcanic activity we suggest that the first stage of rotation was isolated in early middle miocene calc alkali rocks with a relative counterclockwise rotation of r r 20 2 9 3 with respect to eurasia this accommodates the south westward rotational collapse of the western anatolia peninsula across a pole on the bitlis suture in the neotectonic period on other hand a relative clockwise rotation of r r 27 3 6 4 with respect to eurasia is predicted in contrast to the uniform clockwise rotations extremely large clockwise rotations up to 264 are restricted in a narrow zone between two dextral faults we believe that the second stage rotations support the idea of individual microblock rotations due to deformation along the north anatolian fault zone

stratigraphy and facies distribution of the utsira formation and the pliocene sequences in the northern north sea abstract the upper cenozoic deposits of the northern north sea have been analysed in order to establish a regional and detailed stratigraphy the utsira formation is subdivided into four log units and mapped and two main depocentres are outlined the lower part of the utsira formation consists of thick marine mounded sand bodies interpreted as overall stacked lowstand fan deposits while the upper part of the formation consists of more clayey silty intervals indicating increased relative sea level the succeeding progradational pliocene deposits are subdivided into 13 high frequency depositional sequences and are mapped the sequences are grouped into four composite sequences each of the four pliocene composite sequences is composed of one or two rather locally distributed prograding sequences lowstand sequence set succeeded by one or two more widely distributed aggrading prograding sequences transgressive highstand sequence set boundaries between the composite sequences are recorded as marked changes in distribution of depocentres and sequence architecture the regional uplift of scandinavia is believed to be the main control on sediment input feeding the succeeding general prograding pliocene sequences oscillations of the eustatic sea level punctuated the tectonically controlled progradation and affected variations in the accommodation space and thus created the high frequency sequences

neogene anticlockwise rotation of central anatolia turkey preliminary palaeomagnetic and geochronological results abstract a palaeomagnetic and geochronological study was carried out on fifty sites from the neogene volcanic province of central anatolia results from this analysis show that there has been a progressive anticlockwise rotation of this region over the period spanning at least the last 10 12 ma we interpret this rotation as having resulted from the collision of arabia with anatolia along the bitlis suture if we assume a constant rate of rotation we obtain a rate of 2 4 ma this value is significantly higher than the present day rotation rate obtained from gps 1 3 0 1 ma and also implies that these rocks have been rotating at their present rate since well before collision occurred along the bitlis suture 12 ma a geologically unreasonable conclusion if however we combine these data with data from other palaeomagnetic studies with good age control the resultant curve seems to show three distinct linear segments 1 0 5 ma with a very slow rate of rotation 1 2 ma 2 5 12 ma where we observe a rapid increase of rotation rate to 6 5 ma and 3 12 ma when the rotation rate is again essentially zero 0 041 ma these results are generally consistent with a model calling for middle miocene collision along the bitlis suture and late plio pleistocene initiation of motion along the north and east anatolian fault zones

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

quantitative analysis of time lapse seismic monitoring data at the sleipner co2 storage operation the co2 storage operation at sleipner in the norwegian north sea provides an excellent demonstration of the application of time lapse surface seismic methods to co2 plume monitoring under favorable conditions injection commenced at sleipner in 1996 with co2 separated from natural gas being injected into the utsira sand a major saline aquifer of late cenozoic age co2 injection is via a near horizontal well at a depth of about 1012 m below sea level bsl some 200 m below the reservoir top at a rate approaching 1 million tonnes mt per year with more than 11 mt currently stored

jurassic cretaceous paleomagnetism and paleogeography of the pontides turkey published paleomagnetic data from the pontides indicate anomalously low jurassic and early cretaceous paleolatitudes compatible with the southern neo tethyan african continental margin and significantly different from paleolatitudes predicted for the northern eurasian neo tethyan margin we present a new set of paleomagnetic data from 50 late cretaceous sites mainly from the western pontides and from the eastern pontides and 11 early jurassic sites mainly from the eastern pontides fold tests indicate that the characteristic magnetization components predate eocene folding late cretaceous site mean declinations are northerly in the eastern pontides and rotated to the west by a few tens of degrees in the western pontides late cretaceous site mean declinations are affected by local clockwise rotation in one sampling region close to the north anatolian fault the mean late cretaceous inclinations and resulting paleolatitudes are 41 1 23 5 n and 43 7 25 5 n for the western and eastern pontides respectively for the eastern pontides the early jurassic liassic mean inclination is 60 5 yielding a paleolatitude of 41 4 n considerably further north than previous paleolatitude estimates for the eastern pontides at this time the paleolatitude estimates for the western and eastern pontides are consistent with these units being close to the eurasian continental margin during liassic and late cretaceous time

reliability of magnetic fabric of weakly deformed mudrocks as a palaeostress indicator in compressive settings abstract in this work we compare the results of anisotropy of magnetic susceptibility ams with palaeostress analysis at local scale the ams data refer to 14 sites from weakly deformed mudrocks lower and middle miocene lacustrine sediments from two areas of the internal part of the ebro foreland basin the bardenas reales and monegros areas nine sites display a magnetic fabric related to a subtle tectonic overprint showing a roughly e w magnetic lineation whereas the rest of sites most of them located at the monegros area show a sedimentary fabric without a well defined magnetic lineation palaeostress data result from fault populations and joint sets exposed in the limestone beds interbedded with the mudrocks at the nearest possible outcrop from the ams site the origin of the magnetic lineation is related to a n s compression coeval with the earliest diagenesis of the studied sediments prior to consolidation the comparison between magnetic fabric and palaeostress data demonstrates the coaxiality between the ams and palaeostress ellipsoids both at local and regional scales thereby validating the reliability of ams as palaeostress indicator in compressive settings

rapid reactions between co2 brine and silicate minerals during geological carbon storage modelling based on a field co2 injection experiment the dissolution of co2 into formation brines and the subsequent reactions of the co2 charged brines with reservoir minerals are two key processes likely to increase the security of geological carbon dioxide storage these processes will be dependent on the permeability structure and mineral compositions of the reservoirs but there is limited observational data on their rates in this paper we report the cation and anion concentrations and sr oxygen and carbon isotopic compositions of formation waters from four extraction wells sampled at surface over 6 months after commencement of co2 injection in a five spot pattern for enhanced oil recovery at the salt creek field wyoming sampled fluids separated from the minor oil component exhibit near monotonic increases in alkalinity and concentrations of cations but little change in cl and br concentrations and oxygen and deuterium isotope ratios the increases in alkalinity are modelled in terms of reaction with reservoir calcite and silicate minerals as the changes in fluid chemistry and sr isotopic compositions are inconsistent with simple addition of injected fluids sampled over the course of the experiment the reservoir mineral chemical and isotopic compositions are characterised by sampling core as well as surface exposures of the frontier formation elsewhere in wyoming the evolution of the fluid chemistries reflects extensive dissolution of both carbonate and silicate minerals over the course of the six months sampling implying rapid dissolution of co2 in the formation waters and reaction of co2 bearing brines with formation minerals rates of co2 diffusion into the brines and advection of co2 charged brines in the reservoir are sufficiently slow that if present calcite should react to be close to equilibrium with the fluids this allows estimation of the co2 partial pressures in the sampled fluids and comparison with the thermodynamic driving force for the relatively rapid average plagioclase dissolution rates of 10 12 mol m 2 s 1

apatite fission track data from central anatolian granitoids turkey constraints on neo tethyan closure 1 apatite fission track age versus elevation profiles and temperature time path modeling indicate an early to middle paleocene 57 62 ma rapid exhumation of the middle to late cretaceous granitoids in central anatolia and an oligocene 28 30 ma rapid exhumation of the eocene kosedag batholith in the ne sivas region part of eastern central pontides the early to middle paleocene rapid exhumation is thought to result from a regional compressional regime following the collision of the eurasian plate and the tauride anatolide platform at the closure of the izmir ankara erzincan branch of the northern neo tethys the oligocene accelerated exhumation of the kosedag batholith is contemporaneous with the oligo miocene closure of the southern neo tethys which juxtaposed the amalgamated eurasian and tauride anatolide platform and the african arabian plate along the bitlis zagros suture in southeast anatolia the compressional regime due to this collision affected a large area between the greater caucasus in the north and northern african arabian plate in the south

middle eocene paleomagnetic data from the eastern sakarya zone and the central pontides implications for the tectonic evolution of north central anatolia 1 a paleomagnetic investigation has been carried out on middle eocene volcanic rocks at 23 sites in the eastern sakarya zone and the central pontides of north central anatolia in order to better understand the regional tectonic evolution of the main zones of northeastern anatolia in the middle eocene the results constrain the tectonic evolution of the area when evaluated in conjunction with earlier published paleomagnetic directions from 92 localities small counterclockwise rotations in the range of r r 1 3 1 4 to r r 17 2 16 8 with respect to eurasia are observed in the central pontides on the northern side of the north anatolian fault naf clockwise rotations ranging between r r 8 5 15 1 and r r 29 7 12 0 are observed between the naf and the sungurlu fault sf in the eastern sakarya zone counterclockwise rotations of r r 18 9 12 4 to r r 42 2 6 9 are observed to the south of the sf our findings combined with previous data support the indentation model of kaymakci et al 2000 2003a 2003b which postulates the collision and northeast directed indentation of the kirsehir block into the sakarya zone this model which was developed to explain the evolution of the cankiri basin can also explain the variable magnitudes of paleomagnetically determined rotations thrust directions and the curvature of the north anatolian ophiolite belt

formation of the late palaeozoic early mesozoic karakaya complex and related ophiolites in nw turkey by palaeotethyan subduction accretion several pre jurassic tectonic units in nw turkey are crucial to the current debate regarding the timing and direction of subduction of palaeotethys a major ocean that separated eurasia and gondwana in late palaeozoic early mesozoic times the most critical unit is the karakaya complex a deformed low grade assemblage of oceanic origin which comprises a nw verging se dipping stack of tectonostratigraphic units here interpreted as a palaeotethyan accretionary complex the units display lithologies consistent with origins in seamount trench abyssal and rifted carbonate platform settings clastic basin sequences developed on top of the complex other relevant tectonostratigraphic units in the area include ultrabasic rocks of supra subduction zone affinity which tectonically overlie permian carbonate platform units with intervening metamorphic soles and melanges restored structural trends suggest the presence of a southward dipping palaeotethyan subduction zone bordering gondwana related units during the late permian triassic this was probably additional to more important regional northward subduction along the southern margin of eurasia from the eastern mediterranean to the himalayas

composite magnetic fabric in weakly deformed black shales abstract the anisotropy of magnetic susceptibility ams of weakly deformed sediments of the subalpine terres noires french alps is due to phyllosilicates matrix contribution and detrital titanomagnetites ferromagnetic contribution of variable grain size various rock magnetic and anisotropy techniques have been carried out to understand the origin of the scattering of maximum and minimum susceptibility axes we demonstrate the major contribution of the matrix both to susceptibility and ams anisotropy even when mean matrix susceptibility is weak this suggests that phyllosilicates are better oriented within the foliation plane and that intrinsic anisotropy of the detrital titanomagnetite grains is probably weaker than expected also the separation of the two magnetic subfabrics of three selected sites by coupling together low field ams hfa high field ams and aas anisotropy of anhysteretic remanence demonstrates the existence of a competition between two magnetic lineations and an interchange of the intermediate and minimum ams axes as a result of fine titanomagnetite this is the first evidence of the so called intermediate fabric as predicted by theory

methane hydrate recycling offshore of mauritania probably after the last glacial maximum to what extent methane liberated from marine hydrate will enter the ocean during a warmer world is unknown although methane release due to hydrate dissociation has been modelled it is unclear whether or not methane will reach the seafloor during a warmer world and therefore contribute to oceanic and atmospheric budgets here we show using a new three dimensional 3 d seismic dataset that some hydrate deposits surround the gas chimneys passing through the hsz bottom water warming since the last glacial maximum lgm is interpreted to cause hydrate dissociation but critically some of the released methane was not vented to the ocean the released gas caused seal failure and free gas entered the hydrate stability zone hsz through vertical gas chimneys to where new hydrate accumulations formed this process is a new evidence for methane recycling and could account in part for the lack of methane in ice core records that cover warming events during the late quaternary this research provides new insight into how methane could be recycled rather than vented during a warmer world

why are there no clockwise rotations along the north anatolian fault zone mechanical analysis of lithospheric deformation associated with an intracontinental transform fault suggests that it should be associated with a pattern of vertical axis rotations governed by the length of the fault its displacement and the mechanical properties of the lithosphere paleomagnetic results from two transects across the north anatolian fault zone indicate that there have been no measurable clockwise rotations on a regional scale associated with neogene dextral strike slip motion along the fault the data come from two groups of volcanic rocks that have been dated by k ar whole rock geochronology and have yielded ages ranging from 45 3 3 1 m y to 41 8 1 3 m y eocene and 21 7 1 5 m y to 7 5 0 2 m y miocene the absence of clockwise rotations suggests one of the following explanations 1 in contrast to the assumptions underlying current mechanical analyses deformation in the upper crust may not directly reflect the flow in the lithosphere and is localized along a single fault trace 2 deformation is distributed but rotations have been prevented by the presence of elongate fault blocks subparallel to the trace of the main fault 3 displacement along the north anatolian fault may be too small or the rheologic properties of the lithosphere such that rotations about vertical axes cannot be resolved instead of the predicted clockwise rotations measured declinations show that there has been approximately 30 of anticlockwise rotation of both the eocene and miocene volcanic rocks this suggests that no significant rotation occurred between eocene and miocene times and that the anticlockwise rotation occurred either immediately before or concurrent with the plio pleistocene slip on the north anatolian fault

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

topographic controls on gravity currents in porous media we present a theoretical and experimental study of the propagation of gravity currents in porous media with variations in the topography over which they flow motivated in part by the sequestration of carbon dioxide in saline aquifers we consider cases where the height of the topography slopes upwards in the direction of the flow and is proportional to the nth power of the horizontal distance from a line or point source of a constant volumetric flux in two dimensional cases with n 1 2 the current evolves from a self similar form at early times when the effects of variations in topography are negligible towards a late time regime that has an approximately horizontal upper surface and whose evolution is dictated entirely by the geometry of the topography for n 0 result in a transition from an early time similarity solution towards a topographically controlled regime that has an approximately horizontal free surface we also analyse the evolution over topography that can vary with different curvatures and topographic exponents between the two horizontal dimensions finding that the flow transitions towards a horizontally topped regime at a rate which depends strongly on the ratio of the curvatures along the principle axes finally we apply our mathematical solutions to the geophysical setting at the sleipner field concluding that topographic influence is unlikely to explain the observed non axisymmetric flow

fluid transport in geological reservoirs with background flow this paper presents fundamental analysis of the injection and release of fluid into porous media or geological reservoirs saturated by a different fluid undergoing a background flow and tests the predictions using analogue laboratory experiments the study reveals new results important for an understanding of the transport of hazardous contaminants through aquifers and the long term fate of carbon dioxide in geological sequestration using numerical and asymptotic analysis we describe a variety of flow regimes that arise and demonstrate an almost instantaneous control of injected fluid by the far field conditions in geological reservoirs for a continuous input the flow develops a horizontal interface between the injected and ambient fluids the background flow thereby effectively caps the height of the injected fluid into a shallower region of vertical confinement for a released parcel of fluid gravitational spreading is found to become negligible after a short time a dominant control of the interface by the background pressure gradient arises and stems from the different velocities at which it drives the injected and ambient fluids individually similarity solutions describing these dynamics show that the parcel approaches a slender triangular profile that grows horizontally as where is time a rate faster than relaxation under gravity shock layers develop at the front or back of the parcel depending on whether it is more or less viscous than the ambient fluid new analytical results describing the long term effects of residual trapping due to capillary retention are developed which yield explicit predictions for the time and length scales on which a parcel of becomes retained we end by applying our results to geological contexts concluding that even slight background motion can have considerable implications for long term transport through the subsurface

dual sensor streamer technology used in sleipner co2 injection monitoring co2 has been injected into the saline aquifer utsira fm at the sleipner field since 1996 in order to monitor the movement of the co2 in the sub surface the seventh seismic monitor survey was acquired in 2010 with dual sensor streamers which enabled optimal towing depths compared to previous surveys we here report both on the time lapse observations and on the improved resolution compared to the conventional streamer surveys this study shows that the co2 is still contained in the subsurface with no indications of leakage the time lapse repeatability of the dual sensor streamer data versus conventional data is sufficient for interpreting the timelapse effects of the co2 at sleipner and the higher resolution of the 2010 survey has enabled a refinement of the interpretation of nine co2 saturated layers with improved thickness estimates of the layers in particular we have estimated the thickness of the uppermost co2 layer based on an analysis of amplitude strength together with time separation of top and base of this layer and found the maximum thickness to be 11 m this refined interpretation gives a good base line for future time lapse surveys at the sleipner co2 injection site

palaeomagnetism and magnetic properties of the cappadocian ignimbrite succession central turkey and neogene tectonics of the anatolian collage abstract the cappadocian ignimbrite succession of central southern anatolia comprises at least nine major and two minor calc alkaline rhyolitic sheets emplaced at 1 2 ma intervals between 11 2 and 1 1 ma it records the last phase of neotethyan subduction during final emplacement of the tauride orogen in southern turkey this study reports magnetostratigraphy and describes associated rock magnetic properties remanence resides in ti poor titanomagnetites haematisation is locally produced by post emplacement oxidation but does not contribute significantly to the palaeomagnetic signature although secondary processes within the ignimbrite sheets have produced composite isothermal remanent magnetisation spectra and variable intensities of magnetisation weak anisotropy of magnetic susceptibility describes tensors with maximum axes close to bedding and minimum axes perpendicular to this plane directions of kmax with weak imbrication mostly suggest flow away from centres of eruption located by gravity and remote sensing older ignimbrites upper and lower goreme akdag zelve from the cardak centre are all of normal polarity later ignimbrites partly erupted from the derinkuyu centre comprise the sarimaden r cemilkoy r tahar r kizilkaya r incesu n and valibaba sofular r ignimbrites the overall reversed group mean is d i 174 51 n 10 units r 9 84 95 6 6 k 55 and all magnetisation directions from the upper goreme 9 0 ma onwards are rotated anticlockwise with respect to eurasian and african palaeofields this sense of rotation characterises most of central anatolia and averages 9 5 in this sector the rotation rate from 8 to 1 ma bp was 1 25 ma but it appears to have accelerated during the latter part of the quaternary to about an order higher than rates determined from gps rotation has resulted from extrusion of fault blocks during tectonic escape of the anatolian collage to the southwest and followed crustal thickening as the afro arabia plate has continued to impinge differentially into eurasia cenozoic magnetic inclinations are systematically shallower across anatolia than inclinations expected from the geocentric dipole model and the apparent polar wander of bordering major plates only part of this difference 400 km can be accommodated by northward movement and crustal thickening in central anatolia since mid miocene times shallow inclinations observed in the aegean region extend into turkey they are observed in young volcanics and appear to reflect a regional geomagnetic anomaly the pattern of neotectonic declinations across anatolia shows rotations that are strongly anticlockwise rotated in the east near the arabian pincer but diminish towards the west to become zero or slightly clockwise at the western extremity of the collage rotations also seem to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprus arc

palynological and foraminiferal biostratigraphy of upper pliocene nordland group mudstones at sleipner northern north sea abstract the nordland group is an important stratigraphical unit within the upper cenozoic of the northern north sea at its base lies the utsira sand a dominantly sandy regional saline aquifer that is currently being utilized for carbon dioxide sequestration from the sleipner gas and condensate field a mudstone drape immediately overlies the utsira sand forming the caprock for this aquifer the upper part of the utsira sand was recently dated as early pliocene but the precise age of the overlying nordland group mudstones has remained uncertain dinoflagellate cyst pollen and spore foraminiferal and stable isotopic analyses have been performed on these mudstones from a conventional core within the interval 913 10 906 00 m drilled depth in norwegian sector well 15 9 a 11 the samples lie closely above the utsira sand results give a gelasian late late pliocene age for this interval with a planktonic foraminiferal assemblage at 913 10 m indicating warm climatic conditions and an age between 2 4 and 1 8 ma an abundance of the cool tolerant dinoflagellate cysts filisphaera filifera and habibacysta tectata at 906 00 m along with evidence from pollen and foraminifera points to deposition during a cool phase of the gelasian dating the mudstone drape provides useful insights into depositional processes it seems likely that the utsira sand a basinal lowstand deposit became progressively starved of clastic input as sea level rose and shorelines retreated the mudstone drape is interpreted as a highstand deposit perhaps including a maximum flooding surface overlying prograding wedges of the nordland group form a regressive succession characterized by increased sedimentary input and rates of deposition of at least 25 cm per 1000 years which is more than five times that of the utsira sand this is the first published study of a dinoflagellate cyst assemblage from the upper pliocene of the northern north sea the new dinoflagellate cyst species echinidinium nordlandensis head sp nov and echinidinium sleipnerensis head riding sp nov are formally described

bounds on low frequency seismic velocities in partially saturated rocks the most common technique for estimating seismic velocities in rocks with mixed pore fluid saturations is to use gassmann s relations with an effective fluid whose density and compressibility are averages of the individual pore fluid properties this approach is applicable only if the gas oil and brine phases are mixed uniformly at a very small scale so the different wave induced increments of pore pressure in each phase have time to diffuse and equilibrate during a seismic period in contrast saturations that are heterogeneous over scales larger than the characteristic diffusion length i e patchy saturation will always lead to higher seismic velocities than if the same fluids are mixed uniformly at a fine scale critical saturation scales separating uniform from patchy behavior are typically of the order 0 1 1 cm for laboratory measurements and tens of centimeters for field seismic frequencies for low seismic frequencies velocities corresponding to patchy and homogeneous saturations represent a