reply to comments on how much does the upward advection of the supergradient component of boundary layer wind contribute to tropical cyclone intensification and maximum intensity

geotraverses across the swiss alps the alpine chain marks the collision zone between the european and african lithospheric plates the earth s crust below the alps has been thickened by tectonic activity to form a root of crustal material which extends to a depth of approximately 60 km here we present the initial results of three seismic reflection traverses across the alps which show large scale crustal indentations resulting from collision between continental plates as well as the nappeforming style of deformation produced by compression of attenuated ocean crust the data suggest that the gross structural deformation of the collision zone results from large scale crustal indentations the descending european crust is delaminated and deformed by wedges of the african crust protruding northwards below the alps the nappe forming deformation seems to be restricted to the upper 10 20 km of the penninic domain in the core of the alps

rewriting the climatology of the tropical north atlantic and caribbean sea atmosphere abstract the jordan mean tropical sounding has provided a benchmark reference for representing the climatology of the tropical north atlantic and caribbean sea atmosphere for over 50 years however recent observations and studies have suggested that during the months of the north atlantic hurricane season this region of the world is affected by multiple air masses with very distinct thermodynamic and kinematic characteristics this study examined 6000 rawinsonde observations from the caribbean sea region taken during the core months july october of the 1995 2002 hurricane seasons it was found that single mean soundings created from this new dataset were very similar to c l jordan s 1958 sounding work however recently developed multispectral satellite imagery that can track low to midlevel dry air masses indicated that the 1995 2002 hurricane season dataset and likely jordan s dataset as well was dominated by three distinct air masses moist tropical mt saharan air layer sal and midlatit

efficient method for coupling field data and numerical modeling for the estimation of transverse mixing coefficients in meandering rivers abstracta numerical model has been developed employing an orthogonal stream tube gridding system for the investigation of mixing patterns in meandering rivers the proposed model couples field data and modeling it uses a measured velocity field to solve the advection diffusion equation this equation provides a practical simulation with greater accuracy and lower computational cost for estimation of mixing in meandering channels with a long full mixing length the model has been used to estimate the transverse mixing coefficient in surveyed subreaches of the north saskatchewan river in canada good agreement was observed between the numerical and measured tracer concentrations using reasonable values for the transverse mixing coefficient the average dimensionless transverse mixing coefficient from the calibrated numerical model for the surveyed reach was 0 39 which was consistent with values estimated using empirical formulas for transverse mixing coefficients in natural meandering rivers the estimat

rheological stratification of the lithosphere abstract the rheology of the lithosphere is estimated on the basis of pore pressure dependent frictional failure in the brittle regime and power law steady state creep in the ductile regime different petrological models of the continental and oceanic lithosphere combined with different geotherms and thicknesses are used to generate models covering a variety of geodynamic situations results show that the depth dependence of lithospheric rheology varies with the tectonic province and that in many instances the continental lithosphere has one at the bottom of the crust or two the previous one plus another at mid crustal levels soft ductile layers sandwiched between brittle layers the depth distribution of geophysical parameters seismicity seismic wave velocity and electrical conductivity matches the theological predictions well the lithospheric rheological profiles are used to analyze observed variations in the structural style of deformed continental margin and oceanic terranes in the southeastern canadian cordillera the large scale characteristics of the system show a satisfactory agreement with the inferred rheological structure sub horizontal decollements should be the rule rather than the exception where the lithospheric rheology is strongly stratified

syn rift evolution of the pripyat trough constraints from structural and stratigraphic modelling the pripyat trough is a late devonian rift basin it forms part of the larger pripyat dniepr donets rift system which has a length in excess of 800 km and separates the ukrainian shield from the voronezh massif the pripyat trough contains a well resolved stratigraphic sub division within the syn rift basin fill sequence which allows the duration and rate of rifting to be determined using 2 d forward and reverse structural and stratigraphic modelling the analysis shows that rifting was extremely rapid sequential decompaction and flattening of 2 d cross sections has been applied to six syn rift time horizons between top upper devonian 364 ma and top middle devonian 377 ma and used to quantify the syn rift development of basin cross sectional area in time the evolution of basin cross sectional area shows that some initial rifting had occurred prior to the middle frasnian 369 ma however most rifting occurred in the famennian 367 364 ma forward syn rift modelling using the flexural cantilever model of rift basin formation has also been applied to quantify the magnitude of extension within the pripyat trough in time forward syn rift models are constrained by the intra syn rift flattened and decompacted cross sections and the observed evolution of the cross sectional area most rapid rift basin formation is shown to have occurred in the famennian with over 66 of basin cross sectional area forming in less than 5 myr and with approximately 80 or more of total extension occurring in less than 3 myr this period of most rapid extension during the famennian coincides with the most active period of volcanicity total devonian extension across the pripyat trough is estimated to be of the order of 11 14 km with a maximum stretching factor of approximately 1 12 extensional strain rates are estimated to be of the order of 0 8 10 15 s 1

deep structure of the crust along the fennoscandia sarmatia junction zone central belarus results of a geophysical geological integration abstract the eurobridge 96 seismic refraction and wide angle reflection profile in belarus crosses the 2 0 1 9 ga palaeoproterozoic central belarus belt cb subdivided by ne trending minsk fault into the northwestern nwcb and southeastern secb sub terranes differing in their styles of tectonothermal evolution the first interpretation of the eurobridge 96 profile however did not indicate any difference between the nwcb and secb and revealed a high velocity zone beneath the secb with a p wave velocity of 6 6 km s at a depth of 6 km which does not correlate with any pronounced positive bouguer anomaly we present a detailed analysis of the seismic and gravity data obtained along the eurobridge 96 profile complemented with petrological and petrophysical observations on the main rock types of the cb our integrated interpretation shows that the dip orientation of the main reflectors and the p wave velocity and density are different in the nwcb and secb the minsk fault zone is distinguished as an area of relatively high velocities 6 2 km s in the upper crust increased reflectivity in the middle crust se of the minsk fault may be explained by a laminated structure composed of alternating tectonically deformed amphibolite facies and granulite facies rocks that produce a certain seismic anisotropy this seismic anisotropy is proposed as an alternative explanation for the high p wave velocity in the middle crust beneath the secb that does not result in any corresponding positive gravity anomaly the laminated structure beneath the secb might be formed during the uplift of the nwcb and juxtaposition of the nwcb and secb

reappraisal of deep seismic reflection profile viii across the pripyat trough two deep 24 s multi channel seismic reflection profiles each 200 km in length were shot across the pripyat trough a late devonian rift basin in belarus in the 1980s by the polessian geophysical expedition of the former soviet union additional post stack processing and migration on one of these profile viii has been applied at uppsala university and allows a re evaluation of the crustal structure of the pripyat trough with particular focus on the deeper parts previous interpretations showed numerous steeply dipping faults extending from the surface to depths of 30 40 km and sometimes penetrating into the mantle which was defined to be located at the top of a reflective zone beginning at about 10 s twt this reflective zone recorded to depths of 16 s twt was interpreted as a mixture of crustal and mantle rocks based on the original stacked section and the further processing the reflective zone is reinterpreted to be reflective lower crust not upper mantle and the moho is identified to be at 45 50 km about 15 s twt the major basin bounding faults appear to be listric at depth and sole into the top of the reflective lower crust rather than be truncated by it the newly interpreted crustal structure is consistent with a model of continental rifting involving brittle failure in a thick upper crustal layer and ductile shear in the lowermost crust with some degree of detachment between crust and mantle within the lower crustal ductile layer

mechanical basis for low angle normal faulting in the basin and range province low angle normal faults seem to violate the criterion that relates fault dip to stress orientation to explain such faults one must postulate a 45 rotation of principal stress directions at mid crustal depths which is difficult to understand on the basis of previous elastic crust models such a stress rotation is shown to be a natural consequence of a low viscosity lower crust

radiative dynamical consequences of dry tongues in the tropical troposphere abstract dry layers are frequently observed in atmospheric soundings from the climatologically humid western pacific warm pool region some 2400 soundings from the toga coare field program were objectively examined for humidity drops layers in which relative humidity decreases rapidly with height indicative of the bases of dry layers these occur throughout the lower and middle troposphere with frequency peaks near 550 the 0 c level 800 and 950 mb a composite constructed from these sounding data indicates the following almost all dry layers are too dry and not warm enough to be interpreted as conservative vertical displacements rather they apparently consist of filaments or tongues of low moist static energy air advected into the column often from the subtropics dry tongues are anomalously virtually warm near their bases with a slight cool layer below that is they sit atop sharp stable layers or inversions the authors hypothesize that radiation is responsible for the thermal structure o

a minimal three dimensional tropical cyclone model abstract a minimal 3d numerical model designed for basic studies of tropical cyclone behavior is described the model is formulated in coordinates on an f or plane and has three vertical levels one characterizing a shallow boundary layer and the other two representing the upper and lower troposphere respectively it has three options for treating cumulus convection on the subgrid scale and a simple scheme for the explicit release of latent heat on the grid scale the subgrid scale schemes are based on the mass flux models suggested by arakawa and ooyama in the late 1960s but modified to include the effects of precipitation cooled downdrafts they differ from one another in the closure that determines the cloud base mass flux one closure is based on the assumption of boundary layer quasi equilibrium proposed by raymond and emanuel it is shown that a realistic hurricane like vortex develops from a moderate strength initial vortex even when the initial environment is slightly stable to deep convect

a minimal axisymmetric hurricane model solutions of an axisymmetric version of the minimal three dimensional numerical model of a tropical cyclone developed by zhu et al 2001 are described and compared with those of the three dimensional model vortex evolution is similar in the two models during the early stages of intensification but the period of rapid intensification occurs earlier in the axisymmetric model due to the higher effective resolution obtained using a staggered grid there are marked differences at later times when in the three dimensional model asymmetric structures develop the findings are compared with those of an earlier study by anthes 1972 the axisymmetric model is used to investigate certain fundamental aspects of tropical cyclone dynamics including the emergence of a region of supergradient winds in the boundary layer and the evolution of regions satisfying necessary conditions for inertial and barotropic instability supergradient winds develop in the boundary layer within a radius of about 100 km of the vortex axis at an early stage of evolution and appear to be a natural feature of the vortex boundary layer the development of flow regions satisfying necessary conditions for inertial and barotropic instability occur later and may be attributed inter alia to the upward transfer of air with relatively high angular momentum from the boundary layer to the middle and upper layers by the secondary circulation of the vortex and the downward transfer of air with relatively low angular momentum to the middle layer a linear analysis of a two layer slab symmetric flow suggests why inertial instability does not occur in the axisymmetric model barotropic instability does not appear to be the mechanism responsible for the growth of asymmetries in the calculations using the three dimensional version of the model copyright 2002 royal meteorological society

evidence for late proterozoic subduction from 700 myr old blueschists in china in a comprehensive review of the world s blueschists ernst1 noted an apparent absence of these high pressure low temperature rocks in the precambrian and ascribed it to a cooling of the earth in the phanerozoic eon as blueschists are thought to be formed in subduction zones the absence of precambrian blueschists has been adduced as evidence that plate tectonics did not operate on the early earth2 although this conclusion is not inevitable in that ancient mobile belts are more likely to have been obliterated than younger ones3 the presence of paired metamorphic belts of kyanite sillimanite and andalusite sillimanite grade in proterozoic gondwanaland supports the existence of a subducted slab but with ancient geothermal gradients too high to form blueschists along the convergent plate boundary4 5 on the other hand data from inclusions in african diamonds support the opposing view that archaean continental geotherms were similar to those of today6 here we present rb sr and k ar ages of 698 718 myr for phengitic mica from high pressure pelitic schists from the aksu region of china which are interleaved with blueschists we interpret these dates as representing the time of the blueschist facies metatmorphism suggesting that subduction was occurring in the late proterozoic

transverse mixing in an unregulated northern river transverse mixing in an unregulated northern river in canada was studied in different discharge conditions with and without ice cover the distribution of cumulative discharge was constructed on the basis of river cross sectional shapes and a modified streamtube method was proposed to describe transverse mixing the modified method only uses raw field data to calibrate the modeled concentration profiles and thus can produce a reliable mixing coefficient even with relatively low quality field data the effects of river discharge and ice cover on the transverse mixing coefficient were examined in a fixed study reach it was found that the transverse mixing coefficient increased approximately linearly with river discharge from 84 to 960 m3 s the dimensionless transverse mixing coefficient scaled with river shear velocity and river depth appeared unaffected within 14 by the river discharge in both open water and ice covered conditions and its value was 21 smaller in the ice covered condition than

dynamics of lower tropospheric vorticity in idealized simulations of tropical cyclone formation abstractidealized simulations are conducted using the cloud model version 1 cm1 to explore the mechanism of tropical cyclone tc genesis from a preexisting midtropospheric vortex that forms in r

fault plane reflection processing and 3d display the darling fault western australia abstract a steeply dipping event observed on a 2d profile across the darling fault western australia is identified as a fault plane reflection based on an analysis of shot records and traveltime modelling a 3d image of the same event is formed from a lowfold 3d survey preliminary interpretation of this unmigrated time surface illustrates the usefulness of 3d graphics display in showing strike dip and morphology of a fault plane

the donbas foldbelt its relationships with the uninverted donets segment of the dniepr donets basin ukraine abstract the donbas foldbelt df is a thrust faulted and folded inverted segment of the dniepr donets basin ddb it lies between the scythian and east european platforms north of the black sea and is conventionally thought to have formed in the early permian as part of the late palaeozoic hercynian uralian orogenic frame of cratonic europe the ddb itself formed as a result of late devonian intracratonic rifting and contains a thick up to 22 km late palaeozoic and mesozoic sedimentary succession the deformed strata preserved at the erosional surface of the df are mainly carboniferous the donets segment of the ddb displays mild inversion structures that are transitional to those in the df recently acquired regional seismic reflection data in the donets part of the ddb allow these structures to be imaged in the subsurface for the first time a widespread early permian unconformity occurring throughout the ddb is much more pronounced on its southern margin than on its northern one and appears to be related to profound uplift of the southern flank of the basin and the neighbouring ukrainian shield rather than to crustal shortening faults associated with the early permian unconformity are extensional in style gentle folds and other local structures in the southern flank and axis of the donets segment are mainly located in areas associated with early permian salt movements no significant development of compressional structures of early permian age can be seen in the seismic data where it is available in contrast there is ample evidence of latest cretaceous earliest tertiary compressional deformation in the ddb including the subsurface expression of structures along strike of the main folds of the df a review of geological evidence in the df also indicates that the main period of shortening that can be definitely constrained in time is latest cretaceous earliest tertiary the eastern part of the df records intense late triassic aged cimmerian deformation but none of clearly permian age it is tentatively concluded that the main phases of trans compressional tectonics forming the df were cimmerian and especially alpine rather than hercynian uralian

some aspects of hurricane inner core dynamics and energetics abstract the energy cycle of the mature hurricane resides in the secondary circulation that passes through the storm s eyewall by equating the generation of energy in this cycle to boundary layer dissipation an upper bound on wind speed is derived this bound depends on the degree of thermodynamic disequilibrium between the tropical ocean and atmosphere on the difference between sea surface and outflow absolute temperatures and also on the ratio between the enthalpy exchange and surface drag coefficients such a bound proves to be an excellent predictor of maximum wind speeds in two different axisymmetric numerical models and does not appear to depend on the existence of the hurricane eye but further consideration of the detailed dynamics of the eye and eyewall show that the intensification of hurricanes is accelerated by feedbacks associated with a component of eye subsidence forced by radial turbulent diffusion of momentum this radial momentum diffusion is an inevitable by product of the strong fr

geophysical constraints on the crustal structure of the east european platform margin and its foreland based on the polcrust 01 deep reflection seismic profile abstract a new 240 km long deep seismic reflection profile polcrust 01 was recently acquired in se poland crossing the east european platform eep margin south east of the north german polish caledonides ngpc here we document geophysical field work and subsequent data processing and modeling results obtained from reflection seismic data are augmented by results of the first arrival tomography applied to co located extended offset refraction data as well as potential field modeling and comparison with the available wide angle reflection refraction data our preferred model of the crustal structure derived by integrating seismic potential field and geological data is composed of crustal blocks terranes separated by nearly vertical faults these are i intact part of the eep ii ysogory terrane iii malopolska terrane and iv carpathian mts with their basement reflective lower crust of the eep can be an inherited feature of crustal extension rifting or compressional tectonics acting at the cratonic margin the teisseyre tornquist zone ttz is depicted as a caledonian transcurrent accretion zone corresponding with the near vertical tomaszow fault bounding the ysogory terrane to the east the crust of the ysogory terrane suggests eep affinity although its middle lower crust thickness is highly reduced the malopolska terrane seems to be internally subdivided into blocks of different magnetic properties of the lower crust the carpathian frontal thrust is associated with a change in the rock properties in the deep basement an unknown crustal block which is not visible in seismic data alone the interpreted structure of the caledonian terranes and their tectonic boundaries favors a transcurrent style of a crustal accretion along the central and se polish segments of the ttz implying a very complex nature of the caledonian accretionary belt of central europe from an array of terranes displaced along the ttz to an accretionary wedge of the collisional ngpc orogen between nw poland and southern north sea area

toward clarity on understanding tropical cyclone intensification abstractthe authors review an emerging paradigm of tropical cyclone intensification in the context of the prototype intensification problem which relates to the spinup of a preexisting vortex near tropical storm strength in a quiescent environment in addition the authors review briefly what is known about tropical cyclone intensification in the presence of vertical wind shear the authors go on to examine two recent lines of research that seem to offer very different views to understanding the intensification problem the first of these proposes a mechanism to explain rapid intensification in terms of surface pressure falls in association with upper level warming accompanying outbreaks of deep convection the second line of research explores the relationship between the contraction of the radius of maximum tangential wind and intensification in the classical axisymmetric convective ring model albeit in an unbalanced framework the authors challenge a finding of the second line of research that appears

crustal laminations in deep seismic profiles in france and neighbouring areas summary remarkable crustal features appear on the ecors profiles carried out in northern france and the bay of biscay as well as on the swat profiles shot in the western channel and the celtic sea the most striking one is the occurrence of flat laminations in the lower crust dipping events and laminations are also present in the upper and lower crust especially in the swat profiles they can readily be related to tectonic events variscan in age some of them identified in the field the flat laminations in the lower crust are at first interpreted as resulting from delamination shearing magmatism and metamorphism at the crust mantle transition during the variscan orogeny this interpretation raises some difficulty concerning the space and time correlation of the laminations with the variscan orogeny they seem to have been emplaced after the permian triassic infilling of the plymouth bay basin and before the early cretaceous opening of the bay of biscay an early to middle jurassic age is suggested a period when large cratonic basins were formed without noticeable extension heat flow increase and magmatism are proposed as a second hypothesis for the formation of the lower crust laminations choosing between orogenic and non orogenic causes of these laminations will require further deep seismic profiles together with good velocity determination

the role of boundary layer friction on tropical cyclogenesis and subsequent intensification a recent idealized high resolution numerical model simulation of tropical cyclogenesis is compared with a simulation in which the surface drag is set to zero it is shown that while spin up occurs in both simulations the vortex in the one without surface drag takes over twice as long to reach its intensification begin time when surface friction is not included the inner core size of the simulated vortex is considerably larger and the subsequent vortex intensity is significantly weaker than in the case with friction in the absence of surface drag the convection eventually develops without any systematic organization and lies often outside the radius of azimuthally averaged maximum tangential winds the results underscore the crucial role of friction in organizing deep convection in the inner core of the nascent vortex and raise the possibility that the timing of tropical cyclogenesis in numerical models may have an important dependence on the boundary layer parameterization scheme used in the model

self stratification of tropical cyclone outflow part ii implications for storm intensification tropical cyclones intensify and are maintained by surface enthalpy fluxes that result from the thermodynamics disequilibrium that exists between the tropical oceans and atmosphere while this general result has beenknownfor at least a half century the detailednatureof feedbacksbetweenthermodynamic anddynamic processes in tropical cyclones remains poorly understood in particular the spatial relationship between surface fluxes and the radial entropy distribution apparently does not act to amplify the entropy gradient and therefore the surface winds in previous work this problem was addressed by accounting for the radial distribution of convective fluxes of entropy out of the boundary layer this led to the conclusion that a radial gradient of such convective fluxes is necessary for intensification part i showed that the assumption of constant outflow temperature is incorrect and argued that the thermal stratification of the outflow is set by small scale turbulence that limits the richardson number the assumption of richardson number criticality of the outflow allows one to derive an equation for the variation of outflow temperature with angular momentum this in turn leads to predictions of vortex structure and intensity that agree well with tropical cyclones simulated using a full physics axisymmetric model here it is shown that the variation of outflow temperature with angular momentum also permits the vortex to intensify with time even in the absence of radial gradients of entrainment into the boundary layer an equation is derived for the rate of intensity change and compared to simple models and to simulations using a full physics model

dniepr donets rift deep structure and evolution from dss profiling abstract forward modelling has been applied to refraction and wide angle reflection traveltime data along two profiles crossing the intracratonic dniepr donets rift ddr a devonian sedimentary basin located in the southwestern part of the eastern european platform between the ukrainian shield and the voronezh massif the 2 d p wave velocity models show that the crystalline crust beneath the rift basin is thinner and characterised by higher velocity values of almost 1 0 km s than beneath the shield differences along the strike of the ddr are also indicated the two profiles cross the dniepr and donets segments of the ddr and reveal respectively sedimentary infill thickness of 7 and 20 km and crystalline crustal thicknesses of 31 and 17 km in both cases the crystalline crust comprises two distinct velocity layers beneath the dniepr basin the moho lies at 38 km and the upper mantle velocity is 8 4 km s in the donets region the crustal layers are underlain by velocity boundaries at depths of 37 and 42 km with velocities of 7 6 and 8 0 km s respectively the velocity models are interpreted to indicate that a key process in the formation and evolution of the ddr was the exchange of material between the crust and uppermost mantle it is hypothesised that the extended and faulted pre rift shield crust was intruded by mantle melts during rifting and that crust mantle material exchange may also have occurred during the subsequent cooling and subsidence stage of development rifting was less intense in the dniepr segment of the ddr compared to the donets to explain other differences in uppermost mantle structure between the two segments of the ddr it is postulated that density reduction of some portion of the donets subcrustal mantle occurred in response to compressional deformation and inversion during the permian uralian orogeny

why do model tropical cyclones grow progressively in size and decay in intensity after reaching maturity abstractthe long term behavior of tropical cyclones in the prototype problem for cyclone intensification on an f plane is examined using a nonhydrostatic three dimensional numerical model after reaching a mature intensity the model storms progressively decay while both the inner core size characterized by the radius of the eyewall and the size of the outer circulation measured for example by the radius of the gale force winds progressively increase this behavior is explained in terms of a boundary layer control mechanism in which the expansion of the swirling wind in the lower troposphere leads through boundary layer dynamics to an increase in the radii of forced eyewall ascent as well as to a reduction in the maximum tangential wind speed in the layer these changes are accompanied by changes in the radial and vertical distribution of diabatic heating as long as the aggregate effects of inner core convection characterized by the distribution of diabatic heating are able to draw absolute angula

structural features and evolution of the dniepr donets basin ukraine from regional seismic reflection profiles abstract a set of regional multichannel seismic reflection profiles crossing the dniepr donets dd basin in ukraine 100 200 km long and with a spacing of 10 15 km along strike illuminates the structure of the whole sedimentary cover the rift filled with pre and syn rift devonian sequences and overlain with post rift carboniferous permian mesozoic and palaeogene fill is clearly seen on all sections a basement layer previously identified as a riphean rift succession by refraction seismic studies constitutes in the main strata of the devonian and early carboniferous successions the structure of the rift is characterised by large scale rotational fault blocks and half grabens carried by basin parallel to normal marginal faults or by major horst blocks the total thickness of the devonian and younger succession is up to 19 km in the study area post rift carboniferous and mesozoic sediments cover the rift flanks and increase in thickness towards the rift axis and to the southeast the cumulative thickness of the carboniferous succession alone reaches 11 km with the maximum depth of their base at about 15 km major post rift tectonic events took place at the end of early visean in the middle of serpukhovian in permian times and between the mesozoic and cenozoic tectonic reactivations during carboniferous and early permian times were most pronounced in the southeastern part of the dd basin while they were least pronounced in the northwestern part of the basin merging with the pripyat trough where they are barely observed the most active development of salt structures and stocks corresponds with the periods of tectonic reactivation

lithosphere structure of the ukrainian shield and pripyat trough in the region of eurobridge 97 ukraine and belarus from gravity modelling abstract the southern segment of the seismic profile eurobridge eurobridge 97 eb 97 located in belarus and ukraine crosses the suture zone between two main segments of the east european craton fennoscandia and sarmatia as well as sarmatia itself at the initial stage of our study a 3 d density model has been constructed for the crust of the study region including the major part of the osnitsa mikashevichi igneous belt omib superimposed by sediments of the pripyat trough pt and three domains in the ukrainian shield the volhyn domain vd with the anorthosite rapakivi korosten pluton kp the podolian domain pd and the ros tikich domain rtd the model comprises three layers sediments with maximum thickness 6 km in the pt and two heterogeneous layers in the crystalline crust separated at a depth of 15 km 3 d calculations show the main features of the observed gravity field are caused by density heterogeneities in the upper crust allocation of density domains deeper than 15 km is influenced by moho topography fitting the densities here reveals an increase up to 2960 kg m 3 in the modelled bodies accompanied by a moho deepening to 50 km in contrast a moho uplift to a level of 35 37 km below the kp and major part of the pt is associated with domains of reduced densities an important role for the deep odessa gomel tectonic zone dividing the crust into two regions one of basically archean consolidation in the west pd and rtd and one of proterozoic crust in the east kirovograd domain was confirmed 2 d density modelling on the eb 97 profile shows that in the upper crust three main domains of different precambrian evolution the omib with the superimposed pt the vd with the kp and the pd can be distinguished deeper in the middle and lower crust layered structures having no connection to the surface geology are dominant features of the models least thickness of the crust was obtained below the kp greatest crustal thickness more than 50 km was found below the pd characterised also by maximum deviation of velocity density relation in the rocks from a standard one the velocity and density models along the eb 97 profile have been interpreted together with inferred v p v s ratios to estimate crustal composition in terms of sio 2 content in the course of the modelling the status of the pd as a centre of archean granulitic consolidation has been confirmed the crustal structure of the anorthosite rapakivi kp is complex for the first time a complicated structure for the lower crust and lower crust upper mantle transition zone beneath the kp has been determined the peculiarities of the crustal structure of the kp are quite well explained in terms of formation of rapakivi anorthosite massifs as originating from melt chambers in the upper mantle and lower crust an important role for the south pripyat fault spf repeatedly activated during proterozoic palaeozoic times has been ascertained at the subplatform stage of crustal evolution the spf was probably a magma channel facilitating the granitic intrusions of the kp in the palaeozoic the fault was reactivated during rifting in the pt

dnieper donets palaeorift abstract the devono carboniferous intra cratonic dnieper donets palaeorift transects the southwestern part of the east european platform in a nw se direction it is characterized by linear bounding faults penetrating much of the crust substantial crustal thinning and syn rift volcanic activity the dnieper donets rift developed on cold precambrian shield type continental crust its rifting stage spans early frasnian to late visean times during its post rift evolution an elongate saucer shaped basin subsided the axis of which coincides with the trace of the underlying rift the palaeozoic donets rift is superimposed on a late proterozoic rift a thermal perturbance of the asthenosphere is thought to have provided the driving mechanism for the development of the palaeozoic dnieper donets rift rapid thinning of the subcrustal lithosphere in response to advecting asthenospheric melt was coupled with tensional fracturing of the crust and melting of its lower part this caused an upward displacement of the moho discontinuity post rift subsidence of the dnieper donets graben was governed by lithospheric cooling the southeastern parts of this rift system were inverted during the uralian orogeny

tropical cyclone evolution in a minimal axisymmetric model revisited an improved version of a minimal model for a tropical cyclone is described the model is used to revisit some fundamental aspects of vortex behaviour in the prototype problem for tropical cyclone intensification after rapidly intensifying to a mature phase in which the maximum tangential wind speed remains quasi steady for a few days the vortex ultimately decays in a 20 day simulation the vortex never becomes globally steady in particular the upper anticyclone continues to expand for the duration of the integration these results are consistent with those of recent studies using more sophisticated numerical models as in the latter models an important feature of the dynamics of spin up is the development of supergradient winds in the boundary layer and the vertical advection of the associated high tangential momentum air from the boundary layer to spin up the eyewall region this mechanism while consistent with some recently reported results is not part of the classical theory of spin up

surface flux induced tropical cyclogenesis within an axisymmetric atmospheric balanced model the wishe wind induced surface heat exchange instability theory for tropical atmospheric disturbances suggests that maximum warming occurs at the position of maximum surface wind applying this concept to axisymmetric cyclones leads to outward migration of the radius of maximum wind without amplification therefore the fundamental wishe feedback loop cannot explain tropical cyclogenesis on its own additional restrictions for the surface flux induced heating are necessary this study investigates in detail the effect of such restrictions on surface flux induced tropical cyclogenesis within the framework of a simple axisymmetric balanced model previously developed by the author this model is based on the assumption of zero potential vorticity and formulated in potential radius coordinates heating is restricted by an efficiency parameter that was previously introduced by emanuel in a similar but more simplified model to account for the reduction of net latent heating in an unsaturated atmosphere as in emanuel s model it is found in the linearized and in the nonlinear model that a negative gradient of the efficiency parameter is necessary to initiate tropical cyclogenesis in this case wind amplification primarily takes place in the region where the gradient of the efficiency parameter is negative this region migrates inward shrinks due to frontogenesis and becomes the tropical cyclone s eyewall it is shown that cyclogenesis becomes possible even when the surface heat exchange is wind speed independent in the case of a zero gradient outward propagation with no amplification takes place if a cold anomaly is present at the vortex centre the wind speed increases slightly but no cyclogenesis occurs if on the other hand moisture fluxes can modify the initially uniform profile cyclogenesis appears after anegative gradient is established horizontal diffusion is necessary to prevent a frontal collapse during the development and acts to transport momentum to regions where no wind is generated by heating however inward momentum diffusion does not accelerate the development as it was found previously in the model of emanuel this cyclogenesis process can already be qualitatively reproduced analytically by the linearized version of the model which additionally includes horizontal diffusion effects copyright 2006 royal meteorological society

axisymmetric balance dynamics of tropical cyclone intensification and its breakdown revisited abstractthis paper revisits the evolution of an idealized tropical cyclone like vortex forced by a prescribed distribution of diabatic heating in the context of both inviscid and frictional axisymm

coincident seismic reflection refraction studies of the continental lithosphere a global review nearly 50 coincident seismic reflection refraction studies to depths of at least the moho provide an improved understanding of the continental lithosphere some conclusions include the following 1 a transparent upper crust a common observation on vertical reflection profiles cannot generally be correlated with velocity gradients or low velocity zones rather a commonly transparent upper crust may be explained by short wavelength steeply dipping features in the brittle upper crust and to a lesser degree by signal contamination from source generated noise 2 the reflective lower crust in extensional terranes appears to be characterized by a high average seismic velocity 6 6 7 3 km s and to consist of laminated high and low velocity layers with typical thicknesses of 100 200 m 3 landward dipping reflectors observed in the middle to lower crusts of convergent zones have been identified as paired high and low velocity slabs which represent oceanic crust and mantle accreted via underplating to the continental margin 4 the crust mantle boundary may differ sufficiently when imaged with vertical incidence and wide angle data to justify the retention for the present of the concept of separate reflection and refraction mohos while there is good evidence that these features are coincident within measurement uncertainties in most regions recently recorded data from the basin and range admit the possibility for noncoincidence in that area 5 upper mantle reflections which cannot be migrated into the lower crust remain rare despite isolated unequivocal examples thus the upper mantle appears to be relatively homogeneous at seismic reflection wavelengths and to lack the laminations inferred for the lower crust the wide angle method will likely provide the most reliable information on the velocity structure and physical state of this portion of the lithosphere for some years to come 6 there appear to be clear and consistent basic differences between convergent and extensional terranes which have been identified from coincident experiments these differences may be sufficiently universal to infer the tectonic history of poorly exposed terranes 7 no truly three dimensional coincident experiment i e including three dimensional migration has been conducted but some three dimensional data have been collected using both methods measurements of attenuation poisson s ratio and anisotropy within the crust using coincident data sets remain frontiers

upper lithospheric seismic velocity structure across the pripyat trough and the ukrainian shield along the eurobridge 97 profile abstract we present new results on the structure resulting from palaeoproterozoic terrane accretion and later formation of one of the aulacogens in the east european platform seismic data has been acquired along the 530 km long n s striking eurobridge 97 traverse across sarmatia a major crustal segment of the east european craton the profile extends across the ukrainian shield from the devonian pripyat trough across the palaeoproterozoic volyn block and the korosten pluton into the archaean podolian block seismic waves from chemical explosions at 18 shot points at approximately 30 km intervals were recorded in two deployments by 120 mobile three component seismographs at 3 4 km nominal station spacing the data has been interpreted by use of two dimensional tomographic travel time inversion and ray trace modelling the high data quality allows modelling of the p and s wave velocity structure along the profile there are pronounced differences in seismic velocity structure of the crust and uppermost mantle between the three main tectonic provinces traversed by the profile i the pripyat trough is a ca 4 km deep sedimentary basin fully located in the osnitsk mikashevichi igneous belt in the northern part of the profile the velocity structure is typical for a precambrian craton but is underlain by a ca 5 km thick lowest crustal layer of high velocity the development of the pripyat trough appears to have only affected the upper crust without noticeable thinning of the whole crust this may be explained by a rheologically strong lithosphere at the time of formation of the trough ii very high seismic velocity and vp vs ratio characterise the volyn block and korosten pluton to a depth of 15 km and probably also the lowest crust the values are consistent with an intrusive body of mafic composition in the upper crust that formed from bimodal melts derived from the mantle and the lower crust iii the podolian block is close to a typical cratonic velocity structure although it is characterised by relatively low seismic velocity and vp vs ratio a pronounced sw dipping mantle reflector from moho to at least 70 km depth may represent the proterozoic suture between sarmatia and volgo uralia the structure from terrane accretion or a later shear zone in the upper mantle the sub moho p wave seismic velocity is high everywhere along the profile with the exception of the area above the dipping reflector this velocity change further supports a plate tectonic origin of the dipping mantle reflector the profile demonstrates that structure from palaeoproterozoic plate tectonic processes are still identifiable in the lithosphere even where younger metamorphic equilibration of the crust has taken place

deep seismic survey images crustal structure of tornquist zone beneath southern baltic sea the tornquist zone is europe s longest tectonic lineament and bisects the continent in a nw se direction from the north sea off nw denmark to the black sea new deep seismic reflection and coinci

the mechanics of continental extension and sedimentary basin formation a simple shear pure shear flexural cantilever model abstract deep seismic reflection data and earthquake seismology show the fundamental importance of major crustal faults during extension of continental lithosphere controlling the development of rifted sedimentary basins major basement faults are generally planar and extend down to 10 15 km depth corresponding to the base of the seismogenic layer beneath this depth deformation gives way to distributed ductile shear in the lower crust and lithospheric mantle a mathematical model is described of the geometric thermal and flexural isostatic response of the lithosphere to extension by planar faulting of the upper crust and plastic distributed deformation in the lower crust and mantle during faulting upper crustal footwall and hanging wall blocks behave as two mutually self supporting flexural cantilevers their response to isostatic forces induced by extension generates footwall uplift and hanging wall collapse for extension on multiple faults interference of footwall uplift and hanging wall collapse gives rise to the familiar block rotations of rift tectonics the flexural cantilever model is able to predict crustal structure and sedimentary basin geometry for faults of arbitrary spacing horizontal displacement and polarity the effects of fault spacing fault polarity and the amount of extension as well as erosion of footwall uplift on crustal structure and basin geometry during both syn rift and post rift stages of basin evolution are explored models of passive rifting involving lithosphere extension in response to the build up of far field tectonic forces and decompression induced partial melting of the upper asthenosphere and lower lithosphere appear to conform to the main geological observations the role of active rifting driven by locally derived deviatoric tensional forces generated by mantle plumes remains uncertain

rifting and lower crustal reflectivity a case study of the intracratonic dniepr donets rift zone ukraine 1 intracratonic rifting caused by late devonian extensional stresses in the east european craton created the largest rift zone in europe the pripyat dniepr donets rift southeast ukraine the rift basin is approximately 2000 km long up to 170 km wide and 22 km deep wide angle refraction and reflection seismic data from the donbas basin deep seismic refraction and reflection experiments dobre 99 project together with gravity and magnetic data are analyzed for the structure and evolution of the donbas fold belt which is the uplifted and deformed part of the dniepr donets basin the seismic data are used for identification of large scale crustal structures and modeling of the seismic velocities of the crust and uppermost mantle a ray trace based velocity and density model is derived by joint inversion of gravity and traveltime data the inversion result reveals a zone of high density and velocity beneath the basin at middle to lower crustal levels slightly offset to the ne of the rift axis full waveform synthetic seismograms matching the observed data show high amplitude and low frequency arrivals from this high density body as well as from the moho we interpret the high amplitude low frequency signals as reflections from layered magmatic rocks which intruded into the ductile lower crust during the main rift phase and subsequently were sorted by fractional crystallization the intrusive material thickened the lower crust by approximately 50 this may explain the enigmatic flat moho topography across the rift zone which has been significantly stretched 1 3 the rifting initiated in the late devonian frasnien as a consequence of back arc extension in relation to subduction of the paleo tethys ocean the subducting oceanic slab may have enriched the mantle with volatiles and created convection leading to strong partial melting upwelling and continued rifting in the famennien we interpret the asymmetrical rift geometry as a combination of pure and simple shear tectonic processes

simple shear deformation of the skagerrak lithosphere during the formation of the oslo rift abstract simple shear deformation of the entire lithosphere has been postulated by wernicke 1985 and others but up to now unequivocal seismic evidence in support of this hypotheses has been lacking here we describe well defined seismic reflectors below the skagerrak sea one of which is interpreted as a low angle fault underlying the skagerrak graben segment of the permian oslo rift this reflective lineament can be traced from the mid crust through the lower crust offsetting moho and continuing downwards to ca 50 km depth 16 s a separate mantle reflection beneath the graben may be associated with an earlier period of thrusting the 1730 km of deep seismic reflection data in skagerrak indicate that the crust and mantle inherited a pronounced structural fabric from the proterozoic grenvillian sveconorwegian orogeny during formation of the oslo rift reactivation of these implied weak zones as localized detachment planes would explain the extensional deformation style of the non magmatic skagerrak graben

crustal structure of the midcontinent rift system results from glimpce deep seismic reflection profiles interpretation of great lakes international multidisciplinary program on crustal evolution glimpce seismic reflection profiles indicates that the midcontinent keweenawan 1100 ma rift system of volcanic rocks and postvolcanic and interbedded sedimentary rocks extends to depths as great as 32 km about 10 5 s reflection time along profiles crossing western central and eastern lake superior and the northern end of lake michigan this area may overlie the greatest thickness of intracratonic rift deposits on earth times to moho reflections vary along strike from 11 5 to 14 s about 37 46 km depth in the west to 17 s about 55 km in the center and 13 to 15 s about 42 49 km in the eastern end of lake superior the prerift crust however was thinned 25 30 km beneath the central rift compared with its flanks providing evidence for crustal extension by factors of about 3 4 the midcontinent rift system differs from phanerozoic rifts in having total crustal thicknesses equal to or greater than the surrounding presumably unextended regions

migration why doesn t it work for deep continental data summary conventional migration of deep seismic reflection data often produces disappointingly poor results even when the original unmigrated data are of high quality and are relatively noise free surprisingly deep data often subjectively appear to be best migrated at velocities which are up to 50 less than appropriate interval velocities derived from crustal refraction experiments or directly from stacking velocities the explanation for this behaviour is that near surface features distort and attenuate the seismic wave field and produce apparent discontinuities in deep reflections since these discontinuities are spurious they are not associated with the appropriate large diffractions which real discontinuities at depth would produce during the process of migration reflections are invented in order to cancel out the missing diffractions thereby producing a smiley section which appears overmigrated since the lateral extent of individual smiles increases with increasing migration velocity increasing two way time and increasing seismic wavelength the effect is almost unnoticeable on conventional shallow seismic data but is overwhelming for deep crustal data

continental rift development in precambrian and phanerozoic europe europrobe and the dnieper donets rift and polish trough basins abstract upper crustal structure and lower crustal and mantle character of the european continental lithosphere differ significantly from west to east the processes of rifting of phanerozoic western europe s hotter thinner crust compared with the more stable thicker 45 vs 30 km proterozoic crust of the east european craton is being investigated by europrobe case studies of western and eastern european sedimentary basins the dnieper donets basin transects the southwestern part of the east european platform in a nw se direction lying between the ukrainian shield and the voronezh massif rifting took place from early frasnian until perhaps the late visean and was accompanied by major volcanic activity the distribution of both was affected by pre existing basement fault systems the syn and post rift sedimentary succession may be as thick as 20 km in the donets trough basin evolution and the present crustal geometry have been much affected by inversion during the permian in association with uralian orogenesis tectonic events of bathonian oxfordian 168 154 ma and turonian santonian 91 84 ma age are also recorded in the basin stratigraphy the polish trough lies along the boundary between the phanerozoic and proterozoic european crustal domains coincident with the trans european suture zone the presence of this rheological boundary may be paramount in structurally controlling the position of the trough tectonic subsidence analysis indicates an initial late rotliegendes early triassic syn rift phase of development subsequently episodes of increased tectonic subsidence rate occurred during the oxfordian tithonian 157 146 ma and beginning in the cenomanian 95 90 ma the oxfordian tithonian episode is likely the signature of a second extensional event correlated with intensification of rifting within the arctic north atlantic rift system while the cenomanian and later is a precursor to mild compressional intraplate orogenic movements present day crustal structure reflects the docking of phanerozoic crust against the proterozoic during palaeozoic orogenies permo carboniferous wrenching and transtensional modifications leading to formation of the polish trough as well as modifications during the late cretaceous early tertiary inversion process

evidence for early proterozoic plate tectonics from seismic reflection profiles in the baltic shield plate tectonics provides the linking framework for all tectonic and magmatic activity seen today but it is not known when plate tectonics first developed on earth new deep seismic reflection and

magmatism and the geodynamics of rifting of the pripyat dnieper donets rift east european platform abstract the distribution of volcanism in the late devonian pripyat dnieper donets rift within the east european platform based upon the results of deep drilling indicates that pre existing basement structures and the major rift bounding faults played an important role in channelling the magmas towards the surface major and trace element and sr nd isotopic studies of the most primitive basic and ultrabasic magmas combined with estimates of the amount of extension 1 1 to 1 3 strongly suggest that magmatism was triggered by the upwelling of a thermally and geochemically anomalous mantle plume from the deep mantle during the late frasnian the peak of the magmatism occurred in the famennian coincident with the maximum amount of lithospheric extension magmatism rifting and domal basement uplife were contemporaneous at several localities within the eep suggesting that the thermal and geodynamic evolution of the platform could have been influenced by a cluster of mantle plumes during the late devonian

comparison of fixed and moving vessel flow measurements with an adp in a large river a comparison of three dimensional flow velocity measurements made with an acoustic doppler profiler adp from fixed and moving vessels at cross sections of the parana river argentina was performed the purpose was to design a rapid and reliable procedure for quantifying the velocity field and related parameters such as bed shear velocity and the identification of secondary circulations in large rivers using an adp the fixed vessel measurements were performed over a period of 10 min at three vertical profiles along two of the sections these data were then compared with the results of ten moving vessel repeat transects made at each of the sections and which intersected the fixed vessel sampling locations using a number of different adp setup configurations from the velocity profiles obtained with both fixed and moving vessel measurements total bed shear velocity values were computed by applying the law of the wall the results indicate there can be significant differences between velocities obtained using the moving vessel method and fixed vessel measurements averaged over 10 min these differences in horizontal velocity can be significantly reduced by averaging five or more moving vessel transects with corresponding shear velocities calculated from five transect averages showing differences ranging between 10 and 15 dependent on the adp configuration location of the at a point vertical velocity profile in relation to large scale bed roughness may also be an influential factor and ideally the bed morphology should be quantified together with the adp derived velocities when using the adp to identify secondary flow cells it was found that although one cross section transect can provide a reasonable overall picture an average of five cross sections is necessary to resolve the finer details of flow the implications for applications that use moving vessel techniques for measurement and analysis of three dimensional flow structures including secondary flows are highlighted

seismic velocity structure across the fennoscandia sarmatia suture of the east european craton beneath the eurobridge profile through lithuania and belarus

riphean rifting and major palaeoproterozoic crustal boundaries in the basement of the east european craton geology and geophysics abstract the east european craton which occupies the northeastern half of the european continent is characterized by the presence of giant even transcratonic systems of riphean meso to neoproterozoic rifts aulacogens the largest of these riphean rift systems tend to follow the course of palaeoproterozoic sutures and junction zones that subdivide the craton into three crustal segments with autonomous development histories these segments named fennoscandia volgo uralia and sarmatia are marked by distinct t magsat anomalies genetically the intersegment junction zones represent different types of collisional and accretional interaction between the component crustal segments of the craton in accordance with this the riphean rift systems vary in width the presence or absence of moho uplifts and other properties like for instance heat flow values however all of them follow belts of weakly magnetized crust studded with local magnetic maxima due to the presence of mafic rocks associated with the rifting the rift system intersegment junction zone relationships in consequence similarly represent a range of variation and cannot be referred to one single model

hurricane boundary layer theory in the light of the plethora of definitions for the hurricane boundary layer we advocate a dynamical definition based on the distribution of agradient flow we seek also to clarify the fundamental role of the boundary layer in the hurricane intensification process in particular we contrast the differences between unsteady boundary layers that are able to facilitate the spin up of the vortex above and steady boundary layers that cannot if slaved to the time dependent vortex aloft the latter can spin up the interior vortex only indirectly by changing its thermodynamic properties through vertical advection of these from below and adjustment to thermal wind balance these differences are highlighted by an analytical demonstration that the application of a zero vertical gradient condition on velocity above a steady boundary layer does not provide a direct means of allowing the boundary layer to determine the flow in the interior vortex this result assumes that frictional forces are negligible at this boundary finally echoing a few previous insights we question the applicability of conventional boundary layer theory at radii of strong ascent into the eyewall where the flow is akin to that of separation in aerodynamic boundary layers copyright c 2010 royal meteorological society

the dynamics of intensification in a hurricane weather research and forecasting simulation of hurricane earl 2010 we use a high resolution numerical simulation of atlantic hurricane earl 2010 to increase our understanding of earl s intensification in relatively strong vertical shear in the context of a recent paradigm for tropical cyclone intensification the integrity of the simulation is judged by comparing analyses thereof with those of the unprecedented observational data gathered in earl consistent with the classical view of spin up the amplification of the tangential wind field above the boundary layer is found to occur as the absolute angular momentumsurfaces are drawn inwards by the aggregate heating of the rotating convective clouds in the interior of the vortex in addition to this classical pathway spin up occurs within the inner core boundary layer where the maximum tangential winds occur the latter is another element of the new paradigm despite the detrimental influence of the shear on the vortex alignment and on depressing the pseudo equivalent potential temperature outside the developing eyewall the combined eddy processes associated with the vortical plume structures in and around the developing eyewall region are shown to contribute to an enhanced overturning circulation and an intensifying storm these eddy processes are distinctly agradient effects that are not features of the classical spin up mechanism it remains to be understood how the rotating convective updraughts combine to produce the diagnosed structures of the eddy terms themselves and how vortex rossby waves and other eddies contribute to the alignment of the vortex during intensification

tectonic styles of early proterozoic ore deposition in the fennoscandian shield the early proterozoic metallogenic events of the fennoscandian shield are connected with two major stages of crustal evolution the karelian continental development 2 5 2 1 ga and the svecofennian orogeny 2 0 1 75 ga the karelian continental development was dominated by deposition of terrestrial sediments and tholeiitic volcanism on archaean crust a tensional regime probably associated with a mantle plume and partial melting of the upper mantle culminated in the generation of an ene wsw trending rift zone which was intruded by tholeiitic magma 2 44 ga ago some 15 layered igneous bodies hosting cr pge ni cu and fe v ti deposits are known in the kemi suhanko and koillismaa belts these mafic ultramafic bodies originally formed either several lopoliths or one single layered igneous complex with a minimum length of 260 km nw se and nnw sse trending dolerite dykes intruded the rifted and attenuated archaean crust 2 25 2 0 ga ago preceding ocean opening the coeval ne sw trending dolerite dykes in the northern part of the shield are interpreted as manifestation of an aulacogen the failed arm of a triple armed rift system oceanic crust is preserved in 1 96 ga old ophiolite complexes the cu co zn ni and cr contents of the outokumpu type deposits derive from hydrothermal leaching of oceanic crust and were discharged together with chemogenic cherts and carbonates from ascending hydrothermal fluids on the seafloor above fissure vents in the northern part of the shield rifting and probably ocean opening resulted in the formation of the layered tholeiitic sedimentary complex of the petsenga ni cu district intruded by mineralized mafic ultramafic magma the age of this event is poorly constrained the basin was subsequently closed and continental collision of the kola suture was accompanied by southward obduction of the lapland granulite belt on the archaean crust during the svecofennian orogeny the divergent continental margin was converted into an active margin early subduction of oceanic crust produced oceanic island arcs intruded by 1 93 1 9 ga old tonalites and trondhjemites subsequent subduction of oceanic crust generated 1 9 1 87 ga old continental island arcs associated with massive sulphide cu zn pb ag au deposits the island arcs were accreted to the archaean crust in a concave belt containing the ore districts of kiruna skellefte vihanti pyhasalmi aijala orijarvi and bergslagen bimodal volcanic suites with felsic calc alkaline and mafic tholeiitic volcanites are attributed to rifting of the overriding plate above subduction zones ni cu deposits in synorogenic 1 9 1 87 ga old mafic ultramafic intrusions occur in linear fault controlled belts at the margin of the archaean crust the generation of ni bearing tholeiitic to komatiitic magma is explained by partial melting of the mantle wedge above the early subduction zone magma differentiation and magma upwelling along transcurrent faults on the continental margin sulphur was probably assimilated from the supracrustal wall rocks 1 89 1 87 ga old early svecofennian granitoids are associated with porphyry type cu mo au deposits widespread late svecofennian s type 1 84 1 75 ga granitic magmatism generated minor mo u w sn and ree deposits emphasis is laid on the importance of geotectonic models as a basis for further exploration in the fennoscandian shield

case study intermediate field mixing for a bank discharge in a natural river the intermediate field mixing characteristics of the gold bar wastewater treatment plant effluent into the north saskatchewan river at edmonton were evaluated this region may be considered to be the early part of the transverse mixing region where local channel characteristics are important an extensive field study was conducted to delineate the bathymetry of the study area and evaluate the mixing characteristics by means of a steady state dye test the topographic and limited velocity results of the field study were used to create and validate a depth averaged hydrodynamic model of the study reach in order to extract streamtube information the results from the hydrodynamic model were used to interpret the mixing characteristics of the study reach as well as extract channel characteristics from the analysis it is evident that the distribution of effective transverse mixing coefficient is highly dependent on local river conditions the use of the hydrodynamic model to extract channel characteristics provided a reasonable estimate of mixing characteristics without requiring detailed field velocity data the trade off is more detailed bathymetry data is required to have a realistic model plume averaged channel characteristics rather than cross sectional averaged were shown to produce more realistic transverse mixing coefficients assumed gaussian profile distributions were successfully applied suggesting that for a bank discharge if the maximum bank concentration and mass flux are known this technique could be applied

results of dekorp 2 s and other reflection profiles through the variscides summary the first dekorp profile dekorp 2 s a 250 km long line perpendicular to the variscan strike direction has provided evidence of major crustal shortening during the variscan orogeny sporadic dipping events in a generally transparent upper crust are interpreted as thrust faults while the highly reflective lower crust fits into the general picture of palaeozoic provinces correlations are established between certain reflectivity patterns and rheology moho depths and reflecting lamellae are considered to be post variscan

the 1 80 1 74 ga gabbro anorthosite rapakivi korosten pluton in the ukrainian shield a 3 d geophysical reconstruction of deep structure the deep structure of the gabbro anorthosite rapakivi granite amcg type korosten pluton kp in the northwestern ukrainian shield was studied by 3 d modelling of the gravity and magnetic fields together with previous seismic data the kp occupies an area of ca 12 500 km 2 and comprises several layered gabbro anorthositic intrusions enveloped by large volumes of rapakivi type granitoids between 1 80 and 1 74 ga the emplacement of mafic and associated granitoid melts took place in several pulses the 3 d geophysical reconstruction included a modelling of the density distribution in the crust using the observed bouguer anomaly field constrained by seismic data on moho depth and b modelling of the magnetic anomaly field in order to outline rock domains of various magnetisation size and shape in the upper and lower crust the density modelling was referred to three depth levels of 0 to 5 5 to 18 and 18 kin to moho respectively the 3 d reconstruction demonstrates close links between the subsurface geology of the kp and the structure of the lower crust the existence of a non magnetic body with anomalously high seismic velocity and density is documented most plausibly it represents a gabbroic stock a parent magma chamber with a vertical extent of ca 20 km penetrating the entire lower crust this stock has a half cylindrical shape and a diameter of ca 90 kin it appears to be connected with a crust mantle transitional lens previously discovered by eurobridge seismic profiling the position of the stock relative to the subsurface outlines of the kp is somewhat asymmetric this may be due to a connection between the magmatism and sets of opposite dipping faults initially developed during late palaeoproterozoic collisional deformation in the sarmatian crustal segment continuing movements and disturbances of the upper mantle and the lower crust during post collisional tectonic events between 1 80 and 1 74 ga may account for the long lived recurrent amcg magmatism less

on the distribution of subsidence in the hurricane eye two hurricane eye features that have yet to be adequately explained are the clear air moat that forms at the outer edge of the eye and the hub cloud that forms near the circulation centre to investigate whether these features can be explained by the spatial distribution of the subsidence field we have derived an analytical solution of the sawyer eliassen transverse circulation equation for a three region approximation with an unforced central eye region of intermediate or high inertial stability a diabatically forced eyewall region of high inertial stability and an unforced far field of low inertial stability this analytical solution isolates the conditions under which the subsidence is concentrated near the edge of the eye the crucial parameter is the dimensionless dynamical radius of the eye defined as the physical radius of the eye divided by the characteristic rossby length in the eye when this dimensionless dynamical radius is less than 0 6 there is less than 10 horizontal variation in the subsidence rate across the eye when it is greater than 1 8 the subsidence rate at the edge of the eye is more than twice as strong as at the centre of the eye when subsidence is concentrated at the edge of the eye the largest temperature anomalies occur near there rather than at the vortex centre this warm ring structure as opposed to a warm core structure is often observed in the lower troposphere of intense hurricanes copyright 2007 royal meteorological society

an analysis of the observed low level structure of rapidly intensifying and mature hurricane earl 2010 abstract we examine dynamic and thermodynamic aspects of atlantic hurricane earl 2010 during its intensification and mature phases over four days of intensive measurements during this period earl underwent an episode of rapid intensification maturity secondary eyewall replacement re intensification and the early part of its decline the observations are used to appraise elements of a new model for tropical cyclone intensification the results affirm the conventional vortex interior and boundary layer spin up mechanisms that form dynamical elements of the azimuthally averaged view of the new intensification model the average maximum tangential winds beneath the eyewall are found to exceed the gradient wind by between 20 and 60 the results suggest also that the gradient wind balance approximation in the low level vortex interior above the strong inflow layer may not be as accurate in the inner core region of a tropical cyclone during its intensification as has been widely held an analysis of the low level thermodynamic structure affirms the radial increase of moist equivalent potential temperature e with decreasing radius during the intensification process a necessary ingredient of the new model for maintaining convective instability in the presence of a warming upper troposphere an unanticipated finding is the discovery of an unmixed boundary layer in terms of e within several hundred kilometres of the vortex centre in the inner core region this finding is not consistent with the axisymmetric eruption of the boundary layer into the eyewall unless there are non conservative eddy processes acting to modify the entropy of ascending air

lithospheric structure along wide angle seismic profile georift 2013 in pripyat dnieper donets basin belarus and ukraine

an air sea interaction theory for tropical cyclones part ii evolutionary study using a nonhydrostatic axisymmetric numerical model abstract in part i of this study an analytical model for a steady state tropical cyclone is constructed on the assumption that boundary layer air parcels are conditionally neutral to displacements along the angular momentum surfaces of the hurricane vortex the reversible thermodynamics implied by this assumption allows the mature storm to be thought of as a simple carnot engine acquiring heat at the high temperature ocean surface and losing heat near the low temperature tropopause although the oceanic heat source is universally recognized as the sine qua non for the mature hurricane there is also wide acceptance of conditional instability of the second kind cisk which makes no specific reference to surface heat fluxes as the formative mechanism this ambivalence is seen in that all numerical simulation studies find it essential to have transfer from the ocean surface yet all start from a conditionally unstable atmosphere the hypothesis put forward in part i based on the steady state theory is t

implications of new upb zircon chronology to early proterozoic crustal accretion in northern sweden abstract u pb ages ranging from 1 89 to 1 78 ga are reported for zircon populations formed during major magmatic events in the proterozoic development of northern sweden the studied area includes parts of the continental and the marine svecokarelian domains of the baltic shield the ages record crustal accretion and reactivation off the margin of an exposed archaean craton and show that magmatism was broadly coeval throughout the entire north swedish portion of the svecokarelian province irrespective of regions involved a detailed chronostratigraphy is presented for the skellefte district of northern sweden and comparisons are made with the evolution in other parts of the svecokarelian province two main magmatic phases commencing at 1 89 and 1 79 ga ago are recognized the first represents large scale volcanism and plutonism which in the skellefte district was characterized by the introduction of mainly mantle derived magmas or by magmas formed from rocks with short crustal residence time in the vicinity of the archaean craton some distance to the north the crust generating processes included the mobilization of archaean sources and appear to have continued until c 1 85 ga ago a relatively long period of consolidation and denudation separates this magmatic phase from the one at c 1 79 ga ago the generation of these later migmatite associated granites in the svecokarelian province coincided in time and was possibly associated with those processes which gave rise to the initial plutonism in the neighbouring transscandinavian granite porphyry belt