early radar echoes from small warm cumulus bragg and hydrometeor scattering abstract studies of small cumulus clouds in florida using x and s band radar 3 and 10 cm wavelengths reveal both hydrometeor and bragg scattering signals turbulent mixing between cloudy and drier environmental air can produce centimeter scale variations in refractive index that can lead to strong mantle echoes around the sides and tops of the clouds when the environmental air is exceptionally dry the s band bragg scattering signals are as strong as 10 dbz at cloud boundaries with weaker echoes in the cloud cores where hydrometeor scattering is also present the bragg signal at s band is typically about 19 db stronger than that at x band as expected from theory however there is in many cases an unexplained bragg like return from the clouds at s band that correlates with the x band echo but is only about 10 db stronger the x band echo is often dominated by backscattering from the cloud droplets and shows adiabatic ascent within the cloud cores fairly often up to at least 1 km above cloud base

caledonian strike slip terrane accretion in w ireland insights from very low grade metamorphism illite chlorite crystallinity and b0 parameter analysis of pelites with detrital white micas in the clew bay galway bay segment of the irish caledonides indicates that b0 data from whole rock and 2 m fractions generally show differences smaller than the errors of the method irrespective of 001 illite crystallinity values probably due to metamorphic recrystallization intermediate pressure metamorphism of the ordovician silurian clew bay group indicates slow subduction allowing partial thermal re equilibration before exhumation in contrast the croagh patrick group laurentian shelf sediments underwent high pressure alteration suggesting rapid subduction exhumation synchronous with strike slip faulting the murrisk group which underwent high intermediate pressure metamorphism in an ordovician back arc forms a separate terrane to the croagh patrick group to the north and also to the ordovician lough nafooey and tourmakeady groups and rosroe formation in the south in which low intermediate pressure alteration occurred these together with the silurian north galway group may have undergone heating due to movement over or deposition on the hot gowlaun detachment as the connemara dalradian was exhumed the south connemara group also underwent a high pressure alteration consistent with its inferred subduction environment evidence of contact alteration due to known or inferred buried late to post caledonian granitoid plutons has been found in the clew bay louisburg clare island croagh patrick murrisk and south connemara groups these show evidence of lower pressure alteration than the surrounding country rocks

geothermal models for the east carpathians abstract in order to explain the high heat flow 73 126 mw m 2 observed at the inner part of the east carpathians a model which takes into account the radiogenic heat generation and the descent of a lithospheric plate has been elaborated calculated geotherms indicate the presence of a high temperature anomaly exceeding 1000 c localized in the upper mantle the geothermal data suggest that both the high heat flow and the building up of the neo volcanic chain are consequences of the lithospheric alpine subduction in the carpathians area

staurolite growth and metamorphic zones in the kalak nappe complex of northeastern porsangerhalvoya north norway abstract four main thrust units have been differentiated in the kalak nappe complex of northeastern porsangerhalvoya all exhibit barrovian type prograde metamorphism although the metamorphic grade increases up the nappe pile the development of planar and non kinematic fabrics is the same in relation to the deformation sequence in each of the thrust sheets early porphyroblast growth preserves a planar fabric developed during burial as a result of overthrusting this was superseded by a randomly oriented and equidimensional non kinematic fabric which developed by recrystallization associated with increased fluid concentrations due to prograde metamorphic dehydration reactions these fabric developments have been preserved in textures associated with the prograde alteration of staurolite and muscovite porphyroblasts with increased fluid concentrations the shear strength of the rock declined and thrust propagation occurred the associated shear stresses caused rotational fabrics in some garnets and aligned mineral growth

coherent structures in the boundary and cloud layers role of updrafts subsiding shells and environmental subsidence coherent structures such as updrafts downdrafts shells and environmental subsidence in the boundary and cloud layers of shallow convection are investigated using a new classification method using large eddy simulation data the new method first filters out background turbulence and small scale gravity waves from the coherent part of the flow composed of turbulent coherent structures and large scale transporting gravity waves then the algorithm divides this coherent flow into updrafts downdrafts shells subsidence ascendance and four other flow structures using an octant analysis the novel method can systematically track structures from the cloud free boundary layer to the cloud layer thus allowing systematic analysis of the fate of updrafts and downdrafts the frequency and contribution of the coherent structures to the vertical mass flux and transport of heat and moisture can then be investigated for the first time updrafts subsidence and downdrafts subsiding shells to a lesser extent are shown to be the most frequent and dominant contributors to the vertical transport of heat and moisture in the boundary layer contrary to previous perspective environmental subsidence transport is shown to be weak in the cloud layer instead downdrafts shells are the main downward transport contributors especially in the trade inversion layer the newly developed method in this study can be used to better evaluate the entrainment and detrainment of individual or an ensemble of coherent structures from the unsaturated boundary layer to the cloud layer

on the thermal regime of some tectonic units in a continental collision environment in romania an analysis of the evolution of the main tectonic units in romania shows that the thermal regime of the lithosphere should be derived according on the one hand to the particular tectonic interactions the various tectonic units have been involved in and on the other hand to the investigated depth interval a steady state conduction model of the crustal temperature field based on the heat flow distribution and information on the structure is presented for the romanian territory it shows large lateral thermal variations between tectonic units as a result of different geological and thermal histories within the frame of a complex modelling of the thermal evolution of the lithosphere in the east carpathians as proposed in this study the zero order thermal effects of the pre miocene oceanic subduction of the eurasian plate are evaluated the deep thermal structure of the subducted slab is derived and shown to be compatible with the velocity structure of the lithosphere and the intermediate depth seismicity of the vrancea area

metamorphic and structural diachroneity in the finnmarkian nappes of north norway two periods of garnet growth gt1 and gt2 have been found in the finnmarkian nappes of north norway in the kolvik nappe the lowest nappe gt1 has preserved an s2 syntectonic spiral inclusion fabric in the olderfjord nappe an earlier s1 fabric and an interkinematic inter d1 d2 fabric have been preserved in gt1 whilst only the s1 fabric has been found in gt1 in the brennsvik nappe the highest nappe in each nappe gt2 overgrew a penetrative fabric s2 wrapped around gt1 in the kolvik nappe inclusion fabrics may be continuous from gt1 into gt2 but in the higher nappes there is a distinct break gt2 may have been partially syntectonic with d3 in the brennsvik nappe chemically gt1 in the kolvik nappe and in parts of the olderfjord and brennsvik nappes has antithetic fe mn zoning in all nappes xca and xmg are weakly zoned in gt1 xmg increases outwards and is greater in the higher nappes in gt1 suggesting higher nucleation temperatures in the olderfjord and brennsvik nappes gt2 is marked by increasing xca probably due to changing garnet plagioclase equilibria although the fe mg ratio remains constant xmg is higher in gt2 than gt1 basement rocks within the nappe pile have an early pre finnmarkian growth gt1 and a later finnmarkian growth gth correlated with gt2 on the basis of chemical zoning patterns the diachroneity of gt1 is ascribed to progressively earlier compared to the structural development cessation of overstepping of garnet forming reactions before peak metamorphism in the higher nappes resulting in earlier structural events being preserved

role of convective mixing and evaporative cooling in shallow convection large eddy simulations of shallow convection are used to evaluate the role of convective mixing and evaporative cooling in the vertical transport of mass heat and moisture in non precipitating shallow convection evaporative cooling is found to increase mass flux and the magnitude of heat and moisture fluxes comparing twin large eddy simulations with either suppressed or active evaporative cooling nonetheless subsiding shells transport mass downward even when evaporative cooling is suppressed emphasizing that evaporative cooling is not the primary cause of existence of subsiding shells and accompanied buoyancy reversal instead vertical convective mixing is found to be the primary reason of buoyancy reversal evaporative cooling yet accelerates downdrafts updrafts in the shell cloudy regions as well as increases the cloud cover in the lower cloud layer the cloudy regions are more humid and the liquid water potential temperature is lower compared to the evaporative cooling suppressed experiment the primary effect of evaporative cooling is thus to increase the updraft core anomalies thus enhancing vertical turbulent fluxes

an electrical resistivity lithospheric model in the carpathian orogen from romania abstract magnetotelluric mt results in the carpathian orogen and its surrounding areas the scythian and moesian platforms as well as the transylvanian depression are presented joint interpretation of mt data and other geophysical information provides an approximate lithospheric model along one profile which transverses from west to east the transylvanian depression the neogene volcanic chain the flysch nappes the foreland and the moesian and scythian platforms the model reveals the alpine palaeo plane of consumption probably caused by the collision of two lithospheric plates generating the subduction exhibited in the eastern carpathians of the flysch nappes primary socles the thickness of the flysch nappes the platform basement structure and partial melting of the asthenospheric material in two depth ranges 80 100 km to the west and more than 150 km east of the palaeo plane

modeling of subgrid scale mixing in large eddy simulation of shallow convection abstract this paper discusses an extension of the approach proposed previously to represent the delay of cloud water evaporation and buoyancy reversal due to the cloud environment mixing in bulk microphysics large eddy simulation of clouds in the original approach an additional equation for the mean spatial scale of cloudy filaments was introduced to represent the progress toward microscale homogenization of a volume undergoing turbulent cloud environment mixing with the evaporation of cloud water allowed only when the filament scale approached the kolmogorov microscale here it is shown through a posteriori analysis of model simulations that one should also predict the volume fraction of the cloudy air that was diagnosed in the original approach the resulting model of turbulent mixing and homogenization referred to as the model is applied in a series of shallow convection simulations using various spatial resolutions and compared to the traditional bulk model this work represents an intermedi

strike slip restoration of the barents sea caledonides terrane finnmark north norway the trollfjord komagelv t k fault is a major wnw ese trending dextral strike slip fault which cuts the caledonides of northern norway with a palaeomagnetically determined displacement of 500 1000 km although earlier interpretations suggested a pre caledonian age for the strike slip displacement our analysis shows that the fault movement was intimately associated with late caledonian thrusting the epizone high intermediate baric type metamorphism of the barents sea caledonides has been used to constrain their restored position relative to other units in the caledonides in northern scandinavia this indicates a postmetamorphic dextral displacement along the t k fault of 415 km the kalak nappe complex straddles the line of the t k fault but has not been cut by it despite this relationship it is argued that the kalak nappe complex was emplaced prior to strike slip fault movement north of the fault structures reflect blind thrusting and passive roof duplex development refolded by en echelon strike slip structures indicating that t k fault movement started after thrusting south of the fault structures in the gaissa thrust belt have been affected by strike slip movement although final thrust movements deformed the t k fault the kalak nappe complex north of the t k fault was carried passively by the strike slip block while to the south major thrusting occurred

measurements of turbulent mixing and subsiding shells in trade wind cumuli abstracthigh resolution measurements of the turbulent thermodynamic and microphysical structure of the edges of trade wind cumuli have been performed with the airborne cloud turbulence observation system lateral entrainment of subsaturated air into the cloud region leads to an evaporative cooling effect the negatively buoyant air partly enhances the compensating downdraft forming a subsiding shell at cloud edge based on the presented observations the subsiding shell is divided into a turbulent and humid inner shell adjacent to the cloud interior and a nonbuoyant nonturbulent outer shell in the trade wind region continuous development of shallow cumuli over the day allows for an analysis of the properties of both shells as a function of different cloud evolution stages the shallow cumuli are divided into actively growing decelerated and dissolving based on cloud properties as the cumuli evolve from actively growing to dissolving the subsaturated environmental air is mixed deeper and deeper i

thrust related very low grade metamorphism in the marginal part of an orogenic wedge scandinavian caledonides the pattern and characteristics of thrust related very low grade metamorphism in the marginal part of an orogenic wedge have been investigated by combining a clay mineral crystallinity survey with detailed structural mapping of the thin skinned foreland thrust belt along the external part of the scandinavian caledonides this external part is composed of late neoproterozoic to ordovician sedimentary sequences of the autochthonous cover and lower allochthon which are overlain by the higher caledonian nappes middle and upper allochthonous units stages of the scandian phase of thrust wedge development are described which are related to the very low grade metamorphic history the initial stage involved the emplacement of cooled nappes belonging to the middle and upper allochthons with very low grade peak metamorphic conditions attained within the underlying lower allochthon cover sediments as they were progressively buried and deformed beneath the thrust wedge during this initial emplacement the isotherms are considered to have been undisturbed and dipping parallel to the wedge surface the following stages of wedge development consisted of extensive post metamorphic imbrication of the underthrusted cover sediments with a transition from basal accretion and uplift at the rear to accretion and forward propagation at the wedge s toe during accretion into the wedge the externally dipping isograd surfaces were extensively displaced from deeper levels toward higher tectonic horizons the last stage of wedge development considered here was characterized by late out of sequence thrusting with enhanced epizonal metamorphic grades developed in the vicinity of the fault zones which either resulted from further displacement of the isograds toward higher levels or from localized heating via intense fluid activity overall the pattern of metamorphic grade fabric relationships and physical calculations of heat transfer based on the geometry of the thrust wedge suggest that neither inverted temperature gradients nor shear heating were likely causes of the metamorphism in this flat lying part of the orogenic wedge the description of inverted very low grade metamorphic isograds in other marginal parts of the scandinavian caledonides which have been previously attributed to either the rapid emplacement of hot thrust nappes or the effects of dissipative shear heating are discussed in terms of variations in both the critical wedge geometry and its controlling boundary conditions

a refined view of vertical mass transport by cumulus convection the purpose of this letter is to show that the traditional view of transport by shallow cumulus clouds needs important refinement on the basis of a straightforward geometrical analysis of large eddy simulation results of shallow cumulus clouds we conclude 1 that the upward mass transport by clouds is strongly dominated by regions close to the edge of clouds rather than by the core region of clouds and 2 that the downward mass transport is dominated by processes just outside the cloud the latter finding contradicts the accepted view of a uniformly descending dry environment we therefore advocate a refined view which distinguishes between the near cloud environment and the distant environment the near cloud environment is characterized by coherent descending motions whereas the distant environment is rather quiescent and plays no significant role in vertical transport

k ar and 40ar 39ar whole rock ages of slate phyllite from allochthonous basement and cover in the tectonic windows of finnmark norway evaluating the extent and timing of caledonian tectonothermal activity slate phyllite samples collected within allochthonous basement rocks raipas super group exposed in the komagfjord and alfa kvaenangen tectonic windows in finnmark northern norway display variably discordant 40 ar 39 ar age spectra in which apparent ages systematically increase from ca 400 425 ma recorded at low experimental temperatures to dates as old as ca 1750 1800 ma in some high temperature increments the apparent age variations are not matched by fluctuations in apparent k ca ratios and are therefore interpreted to reflect intracrystalline gradients in the concentration of 40 ar within constituent fine grained white mica the gradients are suggested to have developed as a result of a variable caledonian thermal rejuvenation of white mica argon systems which had initially cooled through argon retention temperatures at ca 1700 1800 ma following the sveco karelian orogeny the extent of whole rock spectra discordancy is related to the proximity of the basal thrust of the structurally overlying kalak nappe complex whole rock sample suites were also collected structurally downward 0 6 20 m from the kalak thrust within penetratively cleaved allochthonous cover sequences lomvatn formation exposed along the northern edge of the komagfjord window these display discordant 40 ar 39 ar age spectra with most intermediate temperature gas fractions recording mutually similar apparent 40 ar 39 ar ages of 410 430 m y observed variations in k ar and 40 ar 39 ar ages suggest that a late caledonian tectonothermal event ca 420 425 ma variably affected the allochthonous basement and cover units exposed in the two finnmark windows this thermal overprint is interpreted to have developed during emplacement of the structurally overlying kalak nappe complex while it was maintained at post scandian metamorphic temperatures in excess of at least 350 c although the effects of a late cambrian early ordovician orogenic event have been described from portions of the kalak nappe complex no clear record of correlative tectonothermal activity has been documented within structurally underlying tectonic units it is therefore likely that most of the paleozoic metamorphism and deformation observed along the eastern margin of the caledonide orogen in northern scandinavia developed during eastward transport of previously assembled composite scandian nappes into their present structural position on the baltoscandian platform between ca 400 and 425 ma

dynamics of subsiding shells in actively growing clouds with vertical updrafts abstractthe dynamics of a subsiding shell at the edges of actively growing shallow cumulus clouds with updrafts is analyzed using direct numerical simulation the actively growing clouds have a fix

area perimeter relation for rain and cloud areas following mandelbrot9s theory of fractals the area perimeter relation is used to investigate the geometry of satellite and radar determined cloud and rain areas between 1 and 1 2 x 106square kilometers the data are well fit by a formula in which the perimeter is given approximately by the square root of the area raised to the power d see equation in the pdf where d is interpreted as the fractal dimension of the perimeter it is concluded that rain and cloud perimeters are fractals they have no characteristic horizontal length scale between 1 and 1000 kilometers

thrust tectonics deep structure and crustal subduction in the alps and himalayas the structural restoration of collision orogenic belts onto crustal templates provides important insights into the tectonic evolution deep structure and amounts of plate convergence after the initial contact between two continental masses balanced cross sections have been constructed parallel to the local displacement directions across the western alps and western himalayas and demonstrate very large amounts of crustal shortening above intra crustal detachments to achieve a balance substantial volumes of lower crust must have been subducted beneath the two tectonic hinterlands a model of eclogite metamorphism is invoked to facilitate this subduction and to explain the varying isostatic responses of the alpine and himalayan hinterlands patterns of eclogite metamorphism are controlled by the geometry of thrust profiles on a lithospheric scale the development of crust mantle detachments being of crucial importance such a profile is proposed for the himalayas suggesting that relatively small volumes of the footwall crust succumbed to eclogite metamorphism in the alps however a steeper thrust profile apparently developed emplacing mantle onto crust causing wholescale eclogite metamorphism in the underlying franco swiss crust the resultant density increase would provide a mechanism of isostatic collapse and flexural subsidence in the po plain region

tertiary cooling and exhumation history in the maramures area internal eastern carpathians northern romania thermochronology and structural data the tertiary kinematic history of the maramures area is constrained by integrating thermochronological fission track and uth he analysis data with field based structural investigations this study focuses on the tectonic evolution of the northern rim of the tisza dacia block during collision with the european margin cretaceous nappe stacking related metamorphism as well as late cretaceous exhumation are evidenced by zircon fission track data subsequent palaeogene to early miocene sedimentation led to burial heating and annealing of fission tracks in apatite final tectonic uplift was initiated during the convergence of tisza dacia with the european margin associated with transpressional deformation 16 to 12 ma this led to mid miocene exhumation recorded by apatite fission track cooling ages in the western part of the study area transtension between 12 and 10 ma caused brittle deformation along ew trending strike slip faults and swne trending normal faults delimiting blocks that were tilted towards the sw this fragmentation of the crust led to enhanced exhumation at rates of 1 mm a in the central part of the study area as is documented by middle to late miocene cooling ages 13 to 7 ma the outside estimate for the total amount of exhumation since middle miocene times is 7 km

polyorogenic 40ar 39ar mineral age record within the kalak nappe complex northern scandinavian caledonides the kalak nappe complex is composed of variably retrogressed middle proterozoic basement and imbricated polydeformed metasedimentary cover successions which at least in part appear to have originated within the late proterozoic early palaeozoic baltoscandian miogeocline mafic alkaline plutons seiland igneous suite occur within uppermost structural units of the nappe complex 40 ar 39 ar incremental release mineral ages suggest local differences in tectonothermal evolution within the kalak nappe complex post metamorphic cooling dates of c 490 ma are locally recorded by hornblende within the structurally highest tectonic unit suggesting significant orogenic activity occurred during and or immediately prior to the arenig a distinctly later metamorphic overprint occurred in the silurian and was of sufficient magnitude to everywhere rejuvenate ar systems in muscovite and nepheline and locally in hornblende this was followed by relatively rapid post metamorphic cooling through hornblende and muscovite ar closure temperatures between c 425 and 415 ma the complex tectonic history suggested for the kalak nappe complex is generally similar to that previously outlined for the central swedish caledonides together 40 ar 39 ar mineral ages from these widely separated areas indicate that significant tectonothermal activity occurred along the baltoscandian margin prior to the silurian this activity appears at least in part to have been associated with formation of a late cambrian early ordovician accretionary wedge over a westward dipping subduction zone during initial closure of the iapetus ocean

subsiding shells around shallow cumulus clouds abstract in this study large eddy simulations les are used to gain more knowledge on the shell of subsiding air that is frequently observed around cumulus clouds first a detailed comparison between observational and numerical results is presented to better validate les as a tool for studies of microscale phenomena it is found that horizontal cloud profiles of vertical velocity humidity and temperature are in good agreement with observations they show features similar to the observations including the presence of the shell of descending air around the cloud second the availability of the complete 3d dataset in les has been exploited to examine the role of lateral mixing in the exchange of cloud and environmental air the origin of the subsiding shell is examined by analyzing the individual terms of the vertical momentum equation buoyancy is found to be the driving force for this shell and it is counteracted by the pressure gradient force this shows that evaporative cooling at the cloud edge

a new geodynamic model for the seismicity and in situ stresses of the mediterranean region abstract the application of plate tectonic concepts to mediterranean seismicity involves contradictions and anomalies which explains why there is such a great number of conflicting theories each of them based on different geophysical data a new model designed to take into account and explain all the data known to date is presented this is a magmatic vertical chimney where the magma is moved upwards while rotating thus exerting vertical pressure on the periphery of the lithospheric lid moreover it has some relevance to geological structures if this model is correct earthquake prediction can be viewed from an entirely different angle

transition from diagenesis to metamorphism near the front of the variscan regional metamorphism cantabrian zone northwestern spain abstract distribution of paleotemperatures has been studied in paleozoic rocks of the variscan fold and thrust belt of the nw cantabrian zone spain by a combined application of illite crystallinity ic and conodont color alteration index cai results show that the diagenetic metamorphic grade increases with the increase in rock age as marked by decreasing ic values and increasing cai values moreover the cai isogrades roughly reflect the structural traits of the area indicating that maximum temperatures were attained during sedimentary burial previous to folding the geothermal paleogradient obtained suggests conditions near the boundary between low and middle p t conditions there is evidence of at least two thermal events during the tectonothermal development of the belt the main stage is interpreted as the result of the burial of the rocks characterized by late diagenesis conditions that occurred under a geothermal gradient of 35 c km 1 the narrow zone with low anchizonal conditions in the w

a new parameterization for shallow cumulus convection and its application to marine subtropical cloud topped boundary layers part i description and 1d results abstract a new parameterization of shallow cumulus convection is presented the parameterization consists of a mass flux scheme based on a buoyancy sorting entrainment detrainment plume model the mass flux scheme is coupled to a 1 5 order turbulence closure model with an entrainment closure for convective boundary layers model performance is verified using single column model simulations at relatively high vertical resolution of pure trade cumulus convection and a cumulus to stratocumulus transition mixing rates cloud cover and vertical flux profiles as deduced from previously published large eddy simulation studies are well reproduced by the parameterization the model is used to demonstrate that height variations of lateral mixing rates can be successfully captured by a simple implementation of a buoyancy sorting mechanism in the updraft cloud model a companion paper describes the implementation of the scheme in a mesoscale model

from nappe stacking to out of sequence postcollisional deformations cretaceous to quaternary exhumation history of the se carpathians assessed by low temperature thermochronology 1 apatite fission track aft and u th he ahe thermochronology have been combined to constrain the exhumation history of the se carpathians cooling ages generally decrease from cretaceous for the internal basement nappes aft ages to miocene quaternary aft and ahe respectively for the external sedimentary wedge the aft and ahe data show a paleogene age cluster which confirms a suspected but never demonstrated tectonic event the new data furthermore suggest that the se carpathians have been affected by a middle miocene exhumation phase related to continental collision which occurred at rates of 0 8 mm yr similar to the one previously inferred for the east carpathians the se carpathian tectonic evolution however is overprinted by two younger exhumation events in the pliocene pleistocene the first exhumation phase latest miocene early pliocene occurred at high exhumation rates 1 7 mm yr and is interpreted as a tectonic event and or associated with a sea level drop in the paratethys basins during the messinian low stand the youngest recorded tectonic phase suggests rapid pleistocene exhumation 1 6 mm yr and is interpreted to represent crustal scale shortening different in mechanics from collisional processes the data suggest that the se carpathians did not develop as a typical double vergent orogenic wedge instead exhumation was related to a foreland vergent sequence of nappe stacking during collision and was subsequently followed by a large out of sequence shortening event truncating the already locked collisional boundary

tectonic controls of metamorphic field gradients abstract we investigate the effects of horizontal variations in tectonic factors heat production and rate amount and duration of erosion on the magnitudes and gradients of pressure p temperature t and cooling ages observed in mountain belts horizontal gradients of p t and cooling ages are largely controlled by two dimensionless parameters 1 the horizontal length scale over which erosion erosion rate or erosion duration varies and 2 the peclet number pe which describes the relative rates of advection and diffusion of heat in contrast the magnitudes of observed p and t depend strongly on the degree of thickening and original burial depth as well as pe and since horizontal heat conduction can usually be ignored do not depend strongly on p and t gradients generally increase with decreasing and pe for calculations in which either but not both erosion rate or erosion duration is horizontally constant p and t gradients are moderate in magnitude and increase in the direction of increasing total erosion in contrast calculations with horizontally constant total erosion but varying erosion rate and erosion duration show small temperature and pressure gradients pressures and temperatures can increase in the same or in opposite directions depending on the magnitude of calculations with horizontally varying crustal heat production show small but non zero temperature gradients and negligible pressure gradients these results indicate that knowledge of temperature pressure and cooling age gradients in individual mountain belts can constrain fundamental quantities such as magnitude and horizontal gradient of the exhumation rate and the average shear strain rate occurring during exhumation on the basis of their metamorphic field gradients most mountain belts can be divided into one of three groups the first and largest group shows strongly positive p and t gradients precambrian orogenic areas comprise the second group and have small t gradients

a comprehensive mass flux scheme for cumulus parameterization in large scale models abstract observational studies indicate that a mass flux approach may provide a realistic framework for cumulus parameterization in large scale models but this approach through the introduction of a spectral cloud ensemble leads normally to rather complex schemes in this paper the question is addressed whether much simpler schemes can already provide realistic values of the thermal forcing by convection under various synoptic conditions this is done through verifying such a scheme first on data from field experiments for periods of tropical penetrative convection gate marshall islands tradewind cumuli atex bomex and extratropical organized convection sesame 79 and then in a nwp model the scheme considers a population of clouds where the cloud ensemble is described by a one dimensional bulk model as earlier applied by yanai et al in a diagnostic study of tropical convection cumulus scale downdrafts are included various types of convection are represented i e penetrative convection in c

dynamics of the cumulus cloud margin an observational study aircraft observations of shallow to moderately deep cumulus clouds are analyzed with the purpose of describing the typical horizontal structure of thermodynamic and kinematic parameters near the cumulus margin from the cloud center into the ambient clear air the cumuli were sampled in a broad range of environments in three regions the tropical atlantic ocean in winter the sonoran desert during the monsoon and the arid high plains of wyoming in summer the composite analysis of 1624 cumulus penetrations shows thattheverticalmassflux temperature buoyancy thebuoyancyflux andtheturbulentkineticenergyalltend toreachaminimumnearthecloudedge mostofthesevariables andalsotheliquidwatercontent thedroplet concentration and the mean droplet size generally decrease in value from within the cumulus toward the cloud edge slowly atfirst and rapidly close to the cloud edge thesefindingscorroborate recent observational and modeling studies and provide further evidence for significant evaporative cooling in laterally entraining and detraining eddies in the cloud margin a transition zone within 200 m or 10 of the cloud diameter ofthecloudedge thiscoolingexplainsthetendencyfordownwardaccelerating buoyantlydrivensubsidence in the cloud margin

diagenesis and very low grade metamorphism of the antalya unit mineralogical evidence of triassic rifting alanya gazipasa central taurus belt turkey the paleozoic lower mesozoic formations of the antalya unit in southern turkey comprise diagenetic sediments shale mudstone shale siltstone sandstone and scarce spiculite together with very low grade metamorphic lithologies slate metamudstone metasiltstone metasandstone and metalimestone these diagenetic and metamorphic lithologies are dominant in the northern demirtas alanya and southern gazipasa parts of the unit respectively the main minerals of the meta sedimentary rocks are phyllosilicates 2m1 1md 1m illite ia chlorite c v c s i s quartz plagioclase calcite and dolomite the cambrian cretaceous units of the antalya unit differ from the devonian cretaceous northern bolkardagi and aladag units with respect to age lithology and phyllosilicate assemblage but show a considerable similarity to the metamorphic permian triassic mahmutlar nappe of the alanya unit in their phyllosilicate paragenesis although the antalya and precambrian tertiary geyikdagi units seem to have similar lithologies and phyllosilicate associations there are some distinct mineralogical differences such as phyllosilicate polytypes and degree of diagenetic metamorphic alteration ophiolitic fragments olistostromal lithologies phyllosilicate parageneses illite polytype variations anchi epimetamorphic illite crystallinity and relatively low b values suggest that the paleozoic lower mesozoic parts of the antalya unit were metamorphosed in anticlockwise p t t paths in a rifting associated extensional basin the grade of diagenetic metamorphic alteration increases from north to south in the antalya unit related to the higher heat flow due to the southward deepening of the basin vertical diagenetic metamorphic inversion between the lower paleozoic and triassic units is related to higher the heat flux which affected the triassic sediments rather than to thrust tectonics

multi textured garnets from a single growth event an example from northern norway textural relationships between porphyroblasts of biotite and garnet in metasediments in the nordkinn peninsula area of the finnmarkian caledonides of north norway are apparently complex there is evidence for two textural zones in both mineral phases and superficially the development of these appears to have overlapped at least in part in time and space this apparently complex porphyroblast growth history can be considerably simplified if only one period of garnet growth occurred and if different inclusion fabrics developed where garnet replaced biotite porphyroblasts and where it overgrew the matrix foliation the possibility that porphyroblasts with textural evidence for multiphase growth histories actually grew during a single crystallization event is of importance in the interpretation and elucidation of tectonometamorphic relationships