dryline on 19 june 2002 during ihop part i airborne doppler and leandre ii analyses of the thin line structure and convection initiation the evolution and finescale structure of a dryline that initiated a line of thunderstorms is presented both the along line variability and mean vertical structure were examined using data collected by an airborne doppler radar and a water vapor differential absorption lidar dial the initiation of convection appeared to result from the diurnally induced easterly flow in the maritime air east of the dryline that typically develops late in the day this flow increased the low level convergence and allowed rising parcels of air to reach the level of free convection the along line variability was largely attributed to numerous misocyclones distorting the thin line of radar reflectivity by advecting dry moist air across the dryline south north of the misocyclone the misocyclones also influenced the location of the updrafts with most of the peak values positioned north of the circulations as a result these updrafts were fortuitously positioned in regions of high mixing ratio where the first convective cells initiated

eclogite blueschist relationships as evidenced by mineral equilibria in the high pressure metabasic rocks of sifnos cycladic islands greece

finescale vertical structure and dynamics of some dryline boundaries observed in ihop abstract several radar fine lines all with a humidity contrast were sampled in the central great plains during the 2002 international h2o project ihop this study primarily uses aircraft and airborne millimeter wave radar observations to dynamically interpret the presence and vertical structure of these fine lines as they formed within the well developed convective boundary layer in all cases the fine line represents a boundary layer convergence zone this convergence sustains a sharp contrast in humidity and usually in potential temperature across the fine line the key question addressed herein is whether at the scale examined here 10 km the airmass contrast itself in particular the horizontal density virtual potential temperature difference and resulting solenoidal circulation is responsible for the sustained convergence and the radar fine line for the 10 cases examined herein the answer is affirmative

origin of gassmann s equations gassmann s relations are receiving more attention as seismic data are increasingly used for reservoir monitoring correct interpretation of underground fluid migration from seismic data requires a quantitative understanding of the relationships among the velocity data and fluid properties in the form of fluid substitution formulas and these formulas are very commonly based on gassmann s equations nevertheless confusion persists about the basic assumptions and the derivation of gassmann s 1951 well known equation in poroelasticity relating dry or drained bulk elastic constants to those for fluid saturated and undrained conditions it is frequently stated for example but quite incorrect to say that gassmann assumes the shear modulus is constant i e mechanically independent of the presence of the saturating fluid this note clarifies the situation by presenting an unusually brief derivation of gassmann s relations that emphasizes the true origin of the constant shear modulus result while also cla

phenomenological understanding of poroelasticity via the micromechanics of a simple digital rock modelmicromechanics basis of poroelasticity

retrograde formation of nacl scapolite in high pressure metaevaporites from the cordilleras beticas spain a permo triassic pelite carbonate rock series with interacalated metabasitic rocks in the cordilleras beticas spain was metamorphosed during the alpine metamorphism at high pressures pmin near 18 kbar the rocks show well preserved sedimentary features of evaporites such as pseudomorphs of talc of kyanite phengitetalc biotite and of quartz after sulfate minerals and relicts of baryte anhydrite nacl and kcl indicating a salt clay mixture of illite chlorite talc and halite as the original rock the evaporitic metapelites have a whole rock composition characterized by high mg mg ca ratios 0 7 variable alkaline and sr ba contents but are mostly k2o rich 8 8 wt the f 2600 ppm cl 3600 ppm and p2o5 0 24 wt contents are also high the pelitic member of this series is a fine grained biotite rock kyanite phengite talc biotite aggregates in pseudomorphs developed in the high pressure stage albite rich plagioclase was formed when the rocks crossed the albite stability curve in the early stages of the uplift scapolite rich in nacl ca ca na mol 24 40 and poor in so4 with cl cl co3 ratios between 0 6 and 0 8 formed as porphyroblasts sometimes replacing up to 60 of the rock in a late stage of metamorphism between 10 and 5 kbar near 600 c no reaction with albite is observed and the scapolite formed from biotite by begin gathered al biotite caco 3 nacl sio 2 hfill al poor biotite scapolite mgco 3 kcl hfill mgcl 2 h 2 o hfill end gathered

thermodynamic variability within the convective boundary layer due to horizontal convective rolls abstract data from the convection and precipitation electrification cape experiment conducted during the summer of 1991 are used to examine and quantify the horizontal variability of temperature and moisture within the convective boundary layer cbl potential temperature variations were only about 0 5 k while variations in water vapor mixing ratio values of 1 5 2 5 g kg 1 were observed throughout the cbl using radar aircraft and sounding data it is shown that horizontal convective rolls are the likely cause of these variabilities the enhanced moisture occurred within the roll updraft regions thus rolls were transporting moist air from the surface upward the observed cloud base heights obtained from cloud photogrammetry were produced from the highest moisture values within the roll updraft regions since the roll ascending branches contained moisture values that were most representative of the observed cloud base heights it is likely that measurements from within the roll updrafts would prov

a high resolution modeling study of the 24 may 2002 dryline case during ihop part i numerical simulation and general evolution of the dryline and convection abstract results from a high resolution numerical simulation of the 24 may 2002 dryline convective initiation ci case are presented the simulation uses a 400 km 700 km domain with a 1 km horizontal resolution grid nested inside a 3 km domain and starts from an assimilated initial condition at 1800 utc routine as well as special upper air and surface observations collected during the international h2o project ihop 2002 are assimilated into the initial condition the initiation of convective storms at around 2015 utc along a section of the dryline south of the texas panhandle is correctly predicted as is the noninitiation of convection at a cold front dryline intersection triple point located farther north the timing and location of predicted ci are accurate to within 20 min and 25 km respectively the general evolution of the predicted convective line up to 6 h of model time also verifies well mesoscale convergence associated with the confluent flow around the dryline is shown to produce an u

high pressure metamorphism in metabasites from the betic cordilleras s e spain and its evolution during the alpine orogeny the nevado filabride complex is the lowest tectonic unit of the betic zone sensu stricto ss of the betic cordilleras s e spain the upper series of this complex consists of a metamorphosed sequence intruded by basic and ultrabasic igneous rocks high pressure metamorphism in the eclogite and blueschist facies is recorded in the metabasites but this was partially obliterated by further successive metamorphic stages in the almandine amphibolite and greenschist facies

paragonite eclogites from dabie shan china re equilibration during exhumation paragonite in textural equilibrium with garnet omphacite and kyanite is found in two eclogites in the ultrahigh pressure metamorphic terrane in dabie shan china equilibrium reactions between paragonite omphacite and kyanite indicate a pressure of about 19 kbar at c 700 c however one of the paragonite eclogites also contains clear quartz pseudomorphs after coesite as inclusions in garnet suggesting minimum pressures of 27 kbar at the same temperature the disparate pressure estimates from the same rock suggest that the matrix minerals in the ultrahigh pressure eclogites have recrystallized at lower pressures and do not represent the peak ultrahigh pressure assemblages this hypothesis is tested by calibrating a garnet zoisite clinozoisite kyanite quartz coesite geobarometer and applying it to the appropriate eclogite facies rocks from ultrahigh and high pressure terranes these four minerals coexist from 10 to 60 kbar and in this wide pressure range the grossular content of garnet reflects the equilibrium pressure on the basis of the reaction zoisite clinozoisite grossular kyanite quartz coesite h o the results of the geobarometer agree well with independent pressure estimates from eclogites from other orogenic belts for the paragonite eclogites in dabie shan the geobarometer indicates pressures in the quartz stability field confirming that the former coesite bearing paragonite eclogite has re equilibrated at lower pressures on the other hand garnets from other coesite bearing but paragonite free kyanite zoisite eclogites show a very wide variation in grossular content corresponding to a pressure variation from coesite into the quartz field this wide variation partly due to a rimward decrease in grossular component in garnet is caused by partial equilibration of the mineral assemblage during the exhumation

compositions and phase relations of calcic amphiboles in epidote and clinopyroxene bearing rocks of the amphibolite and lower granulite facies central massachusetts usa calcic amphiboles coexisting with epidotegroup minerals zoisite clinozoisite epidote and or clinopyroxene plagioclase quartz garnet occur in amphibolites and calc silicate rocks that underwent amphibolite to lower granulite facies metamorphism in the acadian metamorphic high of central massachusetts usa across the region peak metamorphic conditions range from about 580 c and 6 2 kbar to 730 c and 6 3 kbar the coexistence of most ca amphiboles with fe3 rich epidote group minerals suggests the presence of fe3 in most of these amphiboles an empirical fe3 estimation for the microprobe analyses is based on two constraints the na ca content of the m4 sites of ca saturated gravimetrically analyzed hornblendes gives the relation ca m4 c 1 479 na m4 c 2 c corrected the second constraint is the stoichiometric equation ca m4 na m4 fm 15 where fm is the sum of all cations exclusive of ca na and k solving the two equations simultaneously gives 20 185 0 479 ca m4 1 479 fm starting with the uncorrected values of ca m4 u and fm m4 u u uncorrected of the all ferrous formula the normalization factor nf for calculating the corrected cations of the ferric formulas is 20 185 0 478 ca m4 u 1 479 fm u from the deficient oxygen the fe3 content which is equal to 2 23 ox can be calculated determinations of fe3 contents of four hornblende separates by mossbauer spectroscopy are in agreement with the calculated values the ca amphiboles show systematic changes in composition with increasing grade of metamorphism within the amphibolite and lower granulite facies zones increasing edenite and tschermakite substitution increasing ti content and increasing fe2 fe2 mg ratio in addition the coexisting clinopyroxenes are also characterized by an increase in fe2 fe2 mg ratio in quartz free rocks with coexisting ca amphibole and plagioclase there is an increase in the ratio x ab x ed where x ab na na ca in plagioclase and x ed na in the amphibole a site these chemical changes in mineral composition together with the disappearance of epidote at the transition to granulite facies metamorphic conditions are attributed to the continuous reaction albite epidote fe mg hornblende fe mg clinopyroxene anorthite naalsi 1 hbl h2o

three dimensional printing for geoscience fundamental research education and applications for the petroleum industry three dimensional 3 d printing provides a fast cost effective way to produce and replicate complicated designs with minimal flaws and little material waste early use of 3 d printing for engineering applications in the petroleum industry has stimulated further adoption by geoscience researchers and educators recent progress in geoscience is signified by capabilities that translate digital rock models into 3 d printed rock proxies with a variety of material and geometric scaling options 3 d printing of near identical rock proxies provides a method to conduct repeatable laboratory experiments without destroying natural rock samples rock proxy experiments can potentially validate numerical simulations and complement existing laboratory measurements on changes of rock properties over geologic time scales a review of published research from academic government and industry contributions indicates a growing community of rock proxy experimentalists three dimensional printing techniques are being applied to fundamental research in the areas of multiphase fluid flow and reactive transport geomechanics physical properties geomorphology and paleontology further opportunities for geoscience research are discussed applications in education include teaching models of terrains fossils and crystals the integration of digital data sets with 3 d printed geomorphologies supports communication for both societal and technical objectives broad benefits that could be realized from centralized 3 d printing facilities are also discussed

partially retrograded eclogites of the munchberg massif germany records of a multi stage variscan uplift history in the bohemian massif eclogites with a wide range in bulk composition are present in the munchberg massif part of the variscan basement of the bohemian massif in north east bavaria new analyses of the primary phases garnet omphacite phengite and amphibole as well as the secondary phases clinopyroxene ii various amphiboles biotite phlogopite plagioclase margarite paragonite prehnite and pumpellyite reveal a complex uplift history new discoveries were made of samples with very jadeite rich primary omphacite as well as a secondary omphacite in a symplectite with albite various geothermobarometric techniques together with thermodynamic databases incorporating separately determined activity composition values and experimental data have clustered the minimum conditions for the primary assemblages to the p t range 650 60 c 14 3 1 kbar however jadeite in omphacite kyanite paragonite in phengite and zoisite grossular in garnet kyanite quartz relationships suggests pressures of 25 28 kbar at the same temperatures the fact that the secondary omphacite plagioclase assemblage yields pressures within a few hundred bars of the minimum pressures for the plagioclase free assemblages strongly suggests that the minimum values are serious underestimates zoning inclusion suites and breakdown reactions of primary phases in addition to new minerals formed during uplift define a polyphase metamorphic evolution which from geochronological evidence occurred solely within the variscan cycle the complex breakdown in other bohemian massif eclogites and the distinct variation in their temperatures during uplift suggest a multi stage thrusting model for the regional evolution of the eclogites such an evolution has significance with respect to incorporation of mantle slices into crustal sequences and fluid derivation from successively subducted units possibly driving the breakdown reactions

multiscale pore network representation of heterogeneous carbonate rocks a multi scale network integration approach introduced by jiang et al 2013 is used to generate a representative pore network for a carbonate rock with a pore size distribution across several orders of magnitude we predict the macroscopic flow parameters of the rock utilising i 3d images captured by x ray computed micro tomography and ii pore network flow simulations to capture the multi scale pore size distribution of the rock we imaged four different rock samples at different resolutions and integrated the data to produce a pore network model that combines information at several length scales that cannot be recovered from a single tomographic image a workflow for selection of the number and length scale of the required input networks for the network integration process as well as fine tuning the model parameters is presented mercury injection capillary pressure data were used to evaluate independently the multi scale networks we explore single scale two scale and three scale network models and discuss their representativeness by comparing simulated capillary pressure versus saturation curves with laboratory measurements we demonstrate that for carbonate rocks with wide pore size distributions it may be required to integrate networks extracted from two or three discrete tomographic data sets in order to simulate macroscopic flow parameters this article is protected by copyright all rights reserved

the role of convectively generated gravity waves on convective initiation a case study abstracta case study of a convection initiation ci event involving a mesoscale gravity wave is presented this severe convection event occurred in east china on 5 june 2009 high frequency automatic weather station aws data visible satellite data and doppler radar data were combined to depict the features of the gravity wave and the development of several convection centers the gravity wave was manifested by a surface pressure dip and surface wind shift propagating westward away from the early convection the pressure dip propagated at a speed of 30 m s 1 which is comparable with that in previous observational studies of convectively generated gravity waves a special focus is on the initiation of a deep convection cell in anhui province which resulted in 25 deaths surface observations showed two precursors before ci including a convergence line and wind shift at the eastern end of the convergence line high resolution numerical simulations with the weather research and forecasting wrf model

phase relations of epidote blueschists phase diagrams have been computed for minerals in the system ncmash using the optimised thermodynamic data base of berman 1988 augmented by data on glaucophane and pumpellyite to illustrate the relationships between rocks containing epidote and sodic amphibole and those containing assemblages characteristic of neighbouring metamorphic facies the stoichiometries of stable bounding equilibria yield a simple list of mineral parageneses that serves to define an epidote blueschist facies and surrounding metamorphic facies the calculations suggest that when iron free the pairs zoisite glaucophane and clinozoisite glaucophane do not possess a stability field the natural fe bearing paragenesis of epidote sodic amphibole occupies a closed field in the pt diagram whose size increases dramatically as the ratio fe3 al in the minerals is increased where garnet is involved in bounding reactions such as with respect to eclogite and garnet bearing albite epidote amphibolite the epidote blueschist field decreases in size as the ratio fe2 mg is increased the classic blueschist to greenschist transition reaction is best developed in rocks with large fe3 and fe2 contents and is possibly metastable in mgal rich rocks in the latter a wedge of albite epidote actinolite barroisite amphibolite separates the epidote blueschist from the greenschits paragenesis field a first occurrence of garnet divides the epidote blueschist field into a lower temperature garnet free zone and a higher temperature garnet bearing zone although the temperatures calculated for this garnet isograd seem high the locations of all the facies boundaries are influenced by h2o activity however even minor amounts of co2 in the fluid phase x co2 0 005 render the epidote sodic amphibole paragenesis metastable so that facies boundaries cannot be shifted by varying the co2 content of the fluid phase below 600 c no mutual boundaries exist between the amphibolite facies and the epidote blueschist and eclogite facies respectively the calculated low pressure limit for the eclogite paragenesis pyralspite omphacite jd 50 quartz typical metabasite compositions is 12 to 14 kbars with h2o activity 0 9 or 1 5 to 2 kbar lower for jd 30

analysis of convergence boundaries observed during ihop_2002 abstract an analysis of six convergence boundaries observed during the international h2o project ihop 2002 is presented the detailed kinematic and thermodynamic structure of these boundaries was examined using data collected by an airborne doppler radar and a series of dropsondes released by a jet flying at 500 mb the former and latter platforms were able to resolve the meso and meso scale circulations respectively convection initiated on three of the days while no storms developed in the regions targeted by the mobile platforms on the other days referred to as null cases the airborne radar resolved the finescale structure of four drylines a cold front and an outflow boundary on the six days horizontal profiles through radar detected thin lines revealed bell shaped distributions and there appeared to be a seasonal dependence of the peak values of radar reflectivity the echo profiles through the fine line in may were in general greater than those plotted for the june cases there was

relative geobarometry from high pressure rocks of quartzofeldspathic composition from the sesia zone western alps italy in the sesia zone of the western alps italy early alpine blueschist to eclogite facies metamorphism of rocks of quartzofeldspathic composition has produced the same high pressure assemblage of quartz na pyroxene na amphibole paragonite phengite zoisite garnet magnetite sphene and fe sulphide the qfs assemblage over an area 150 km2 relative gradients in pressure and temperature over this region are reflected in the variations in mineral chemistries of the individual phases of the quartzofeldspathic assemblage through continuous reactions mineralogical discontinuities do not occur in the qfs assemblage of this region increases in the jadeite content of the pyroxenes xjd 0 48 to xjd 0 93 and in the glaucophane content of the amphiboles xgl 0 89 to xgl 0 96 occur from the southwest to the northeast of the region studied analysis of coexisting garnets and pyroxenes indicate that the compositional variation of amphiboles and pyroxenes is associated with a decrease in the grossular component of the coexisting garnet zoned pyroxenes and garnets together with the regional trends in mineral chemistries suggest that the evolution of the qfs assemblage with increasing pressure may be modelled by pressure sensitive continuous reactions in which amphibole zoisite and the more jadeitic pyroxene constitute the high pressure assemblage chemographic constraints permit the positioning in pressure temperature space of the compositional isopleths of those model continuous reactions involving these phases which meet the textural and chemical criteria observed in the natural assemblages the low dp dt slope 20 bars c of these isopleths causes the continuous reactions to be useful for geobarometric calculations at pressures above the absolute breakdown of albite to jadeite plus quartz in addition the pseudobinary loops for the other continuous reactions which are potentially useful geobarometers and involve either the naalca 1mg 1 exchange or the mgca 1 exchange are calculated comparison of mineral chemistries with the isopleths yields a relative barometric scheme for the localities studied with these barometric observations it is possible to show that the p t path which the sesia body travelled towards the final recorded state was one of increasing pressure other blueschist and eclogite occurrences from syros and sifnos which contain rocks of quartzofeldspathic composition are also examined

continuous reactions with amphibole garnet and plagioclase end member continuous and degenerate reactions are derived for the multisystem with the six components na2o cao mg fe o al2o3 sio2 h2o among the phases plagioclasess garnetss amphiboless cpx opx olivine spinel quartz and an aqueous fluid the chemography of this system is degenerate due to the co linearity 2opx ol qtz this co linearity has its implications both on reaction space and phase equilibria from a total of 28 reaction systems reaction space is derived for nine subsystems phases in parentheses are absent case a1 cpx ol cpx opx and cpx qtz case a2 spl ol spl opx and spl qtz case b ol opx ol qtz and opx qtz in the absence of either cpx or spl case a three reactions form an invariant point either cpx or spl where the co linear phases olivine opx and quartz coexist on the transformation line 2opx ol qtz changing mineral compositions force invariant points to move along the line with the different reaction curves changing their relative position according to schreinemakers rules zero contours i e the location where a phase s disappear s in reaction space correspond to singular points in phase diagrams two types are distinguished singular points of indispensable and of substitutable phases in the first case the phase disappears from the entire bundle while in the second it disappears from a single reaction in the specific case where the substitutable phases are also the co linear ones two of the three co linear phases disappear simultaneously two of the three reaction curves coincide in the system including cpx and spl case b three reactions ol opx ol qtz and opx qtz oppose three invariant points ol opx and qtz invariant points no longer move along the line 2opx ol qtz the coincidence of the zero contours of all three co linear phases in reaction space the result of the chemographic degeneracy causes the respective singular points to coincide in the phase diagrams this is the location where curves must be rearranged in a bundle to conform schreinemakers rules the reaction grs1prp2 2 ol an is fourth order degenerate and part of all nine subsystems cases a and b it can be used to relate the different phase diagrams to one another

summary of convective storm initiation and evolution during ihop observational and modeling perspective abstract the data rich international h2o project ihop 2002 experiment is used to study convective storm initiation and subsequent evolution for all days of the experiment initiation episodes were almost evenly divided between those triggered along surface based convergence lines and elevated initiation episodes that showed no associated surface convergence the elevated episodes occurred mostly at night and the surface based episodes occurred during the afternoon and evening surface based initiations were mostly associated with synoptic fronts and gust fronts and less so with drylines and bores elevated initiations were frequently associated with observable convergent or confluent features in the rapid update cycle ruc wind analysis fields between 900 and 600 hpa the ruc10 3 h forecast of the precipitation initiation episodes were correct 44 of the time allowing a tolerance of 250 km in space and for the forecast being early by one period however the accuracy was closely tied to the scale of

petrogenetic grids for metacarbonate rocks pressure temperature phase diagram projection for mixed volatile systems isothermal or isobaric phase diagram sections as a function of fluid composition x f are widely used for interpreting the genetic history of metacarbonate rocks this approach has the disadvantages that 1 the influence of a key metamorphic variable either pressure p or temperature t is obscured 2 the diagrams are inappropriate for systems that are not fluid saturated these problems are avoided by constructing phase diagram projections in which the volatile composition of the system is projected onto a p t coordinate frame i e a petrogenetic grid the univariant curves of such p t projections trace the conditions of the invariant points of isothermal or isobaric phase diagram sections thereby defining the absolute stability of high variance mineral assemblages with and without a coexistent fluid phase petrogenetic grids for metacarbonate rocks are most useful for the study of regional metamorphism and for systems in which fluid composition has not been externally controlled a calculated example of a p t projection for the system cao mgo sio2 h2o co2 suggests that many assemblages e g calcite tale enstatite fluid magnesite tremolite antigorite diopside dolomite and calcite forsterite tremolite in mixed volatile systems have stability fields that make them useful as p t indicators consideration of the principles governing projection topology demonstrates that the univariant curves around a fluid present invariant point cannot be oriented independently with respect to the direction of compositional variation in the fluid phase this has the interesting predictive implication that if the direction of compositional variation along one univariant curve around an invariant point is known then the direction of compositional variation along the remaining curves can be determined solely from topologic constraints the same constraints can be applied to systems containing simple mineral solutions or melts in order to predict compositional variations

petrology structure and geotectonic implications of glaucophane bearing eclogites and related rocks from the malpica tuy mt unit galicia northwest spain abstract the malpica tuy mt unit is a narrow band of basement in galicia northwest spain composed of mica schists paragneisses and calc alkaline to peralkaline orthogneisses with minor amounts of metamorphosed basic rocks garnet omphacite glaucophane barroisite rutile phengite paragonite kyanite zoisite developed in eclogites s s and eclogitic impure sandstones garnet phengite rutile zoisite in the calc alkaline orthogeneisses and garnet phengite rutile chloritoid kyanite in the metasediments biotite breakdown in the orthogneisses and related hornfelses produced garnet with development of coronitic textures plagioclase porphyroblasts with aligned inclusions of rutile and phengite are a common feature of many paragneisses the minimum p t conditions for the equilibrium of garnet omphacite parageneses at the peak of the metamorphism were 600 c 12 2 kbar the mineral chemistry of the orthogneisses and metasediments is compatible with these conditions furthermore the structural data also suggest an in situ origin for the eclogites i e the same as the metamorphism of the enclosing rocks the crystalline area surrounding the mt unit is mainly composed of metasediments and anatectic granites the t at the peak of the metamorphism was higher than 700 c the p being of the order of 5 kbar the two domains represent different parts of the hercynian foldbelt tectonically juxtaposed the juxtaposition is the result of complex tangential tectonics three main phases of compressive deformation having been recognized a first stage of subduction of a thinned crust the materials of the mt unit and subsequent obduction development of hydrated minerals in eclogitic rocks with emplacement of these materials over an already metamorphosed crustal area is suggested the mt unit would represent a remnant of a hercynian thrust nappe

pore throat sizes in sandstones tight sandstones and shales pore throat sizes in siliciclastic rocks form a continuum from the submillimeter to the nanometer scale that continuum is documented in this article using previously published data on the pore and pore throat sizes of conventional reservoir rocks tight gas sandstones and shales for measures of central tendency mean mode median pore throatsizes diameters are generally greater than2 mm in conventionalreservoir rocks range from about 2 to 0 03 mm in tight gas sandstones and rangefrom0 1to0 005 mminshales hydrocarbonmolecules asphaltenes ring structures paraffins and methane form another continuum ranging from 100 a 0 01 mm for asphaltenes to 3 8 a 0 00038 mm for methane the pore throat size continuum provides a useful perspective for considering 1 the emplacement of petroleum in consolidated siliciclastics and 2 fluid flow through fine grained source rocks now being exploited as reservoirs

formation and diurnal variation of the dryline abstract the formation and diurnal evolution of the dryline during fair weather have been investigated through the use of a two dimensional mesoscale model that includes condensation evaporation budget equations of surface energy and moisture field as well as turbulence and radiation parameterizations a moderately strong vertical wind shear was introduced on a sloping terrain where the soil is very dry on the west side but moist on the east initially a weak easterly geostrophic wind exists to the east but a weak westerly geostrophic wind to the west of the dryline during daytime deepening of the mixed layer due to vertical mixing especially on the west side forces the dryline to advance eastward the westerly wind on the west side is maintained by downward transport of westerly momentum due to strong vertical mixing the easterly wind on the east side is strengthened due to the inland sea breeze circulation therefore the resulting low level convergence sustains a strong moisture gradient along

implications to garnet clinopyroxene geothermometry of non ideal solid solution in jadeitic pyroxenes garnet clinopyroxene geothermometry has been applied to numerous rock types from the blueschist and eclogite terrain of the sesia zone in the western alps discrepancies in apparent temperatures of up to 600 c have been found suggesting substantial deviation from ideal behaviour of the garnet clinopyroxene equilibria in certain assemblages assemblages containing jadeitic pyroxenes rather than omphacitic or diopsidic pyroxenes yield very low kd 2 0 values and correspondingly high apparent temperatures 1 000 c the garnets coexisting with high na pyroxenes have compositions similar to those coexisting with omphacitic pyroxenes departure from ideal behaviour of these garnets is likely to be minor and is accomodated in the formulation of the geothermometer numerous examples of coexisting garnet clinopyroxene pairs indicate that there is no obvious relationship of kd with jadeite content in pyroxenes with jadeite content less than 70 but at higher values kd varies inversely with the jadeite content the dependence of kd upon the jadeite content in the high na pyroxenes is believed to be due to the preference of m2 sites for fe2 in the enstatite jadeite substitution fe2 mgna 1al 1 this substitution is usually very limited and has no demonstrable effect upon x fe cpx when the m1 fe2 mg content of the pyroxenes is high as in omphacitic and diopsidic pyroxenes however when the m1 fe2 mg content is low as in jadeitic pyroxenes the non ideality of the enstatite type exchange has a marked effect on x fe cpx and consequently on garnet clinopyroxene calculations

observations of convection initiation failure from the 12 june 2002 ihop deployment abstract observations of the development of cumulus convection which reached depths of several kilometers but failed to develop into sustained precipitating cumulonimbus clouds an event the authors term convection initiation failure are presented from the 12 june 2002 international h2o project ihop case the investigation relies heavily on remote and in situ data obtained by mobile truck borne doppler radars mobile mesonets mobile soundings and stereo cloud photogrammetry data collection was focused in northwestern oklahoma near the intersection of an outflow boundary and dryline thunderstorms developed along the dryline during the late afternoon approximately 40 km east of the domain intensively observed by the ground based observing systems farther west within the region of dense observations analyzed herein cumulus congestus clouds formed along an outflow boundary multiple doppler wind syntheses revealed that the boundary layer vertical velocity field was dominated by thermals rather t

matrix analysis of metamorphic mineral assemblages and reactions assemblage diagrams are widely used in interpreting metamorphic mineral assemblages in simple systems they can help to identify assemblages which may represent equilibrium states to determine whether differences between assemblages reflect changes in metamorphic grade or variations in bulk composition and to characterize isograd reactions in multicomponent assemblages these questions can be approached by investigating the rank composition space range and reaction space null space of a matrix representing the compositions of the phases involved singular value decomposition svd provides an elegant way of 1 finding the rank of a matrix and detemining orthonormal bases for both the composition space and the reaction space needed to represent an assemblage or pair of assemblages and 2 finding a model matrix of specified rank which is closest in a least squares sense to an observed assemblage although closely related to least squares techniques the svd approach has the advantages that it tolerates errors in all observations and is computationally simpler and more stable than non linear least squares algorithms models of this sort can be used to interpret multicomponent mineral assemblages by straightforward generalizations of the methods used to interpret assemblage diagrams in simpler systems svd analysis of mineral assemblages described by lang and rice 1985 demonstrates the utility of the approach

metamorphic evolution of two different eclogites in the franciscan complex california u s a the eclogites in california u s a have been regarded as tectonic blocks which formed 150 160 ma ago and have been tectonically incorporated into younger rocks of the franciscan complex of 90 130 ma however in ward creek northern california two different types of eclogites were identified type i is a typical tectonic block and type ii is a possible in situ eclogite formed during the franciscan metamorphism most eclogites in the franciscan complex are type i eclogites type i eclogites in ward creek consist of garnet omphacite epidote glaucophane phengite rutile barroisite quartz and have coarse grained gneissic texture they have precursors of the epidote amphibolite facies and are overprinted in various degrees by blueschist facies retrograde metamorphism remnants of metamorphic rinds which consist of actinolite talc chlorite and formed during metasomatic interaction with serpentinizing peridotite occur at the margins of type i eclogite blocks type ii eclogites are medium grained and consist of garnet chloromelaniticclinopyroxene epidote glaucophane paragonite phengite rutile quartz petrochemical characters of type ii eclogites are similar to those of in situ eclogitic schists in the ward creek metabasite sequence epidote amphibolite f facies precursors metamorphic rinds and overprint of retrogressive blueschist facies metamorphism are not found in type ii eclogites garnets in type ii eclogites are medium grained unaltered and idioblastic and have higher spessartine contents sp14 25 whereas garnets in type i eclogites are coarse grained and chloritized and have lower spessartine contents sp2 7 the pt conditions of peak metamorphism for type ii eclogites are 380 10 11 5 kb type i eclogites follow a counter clockwise pt path from the epidote amphibolite through eclogite to blueschist facies whereas the presumable in situ type ii eclogites follow a clockwise pt path from the blueschist to eclogite facies

characteristics of dryline passage during cops 91 abstract the characteristics of dryline passage are documented through an analysis of data from an instrumented surface mesonetwork in the texas panhandle and western and central oklahoma during the cooperative oklahoma profiler studies field program some eastward moving drylines at the surface during the day were characterized by monotonic drops in dewpoint after dryline passage others were marked by a series of rapid drops punctuated by periods of no change after dryline passage which suggests that the dryline often progresses in discrete steps rather than continuously the dryline during the daytime was not always collocated with a pressure trough although the strongest dryline observed was analyses of surface pressure traces indicated that westward moving drylines during the evening did not display behavior characteristic of strong intense density currents as had been found in other studies evidence is presented in one case of 90 min oscillations in water vapor and wind behind the dryline

the triple point on 24 may 2002 during ihop part ii ground radar and in situ boundary layer analysis of cumulus development and convection initiation abstract cumulus formation and convection initiation are examined near a cold front dryline triple point intersection on 24 may 2002 during the international h2o project ihop a new lagrangian objective analysis technique assimilates in situ measurements using time dependent doppler derived 3d wind fields providing output 3d fields of water vapor mixing ratio virtual potential temperature and lifted condensation level lcl and water saturated i e cloud volumes on a subdomain of the radar analysis grid the radar and lagrangian analyses reveal the presence of along wind i e longitudinal and cross wind i e transverse roll circulations in the boundary layer bl a remarkable finding of the evolving radar analyses is the apparent persistence of both transverse rolls and individual updraft vertical vorticity and reflectivity cores for periods of up to 30 min or more while moving approximately with the local bl wind satellite cloud images and single camera ground photogrammetry imply tha

singular equilibria in paragonite blueschists amphibolites and eclogites chemographic constraints from high pressure mafic rocks of the introduction nevado filabride complex betic rif mountain belts se spain the relevance of singular equilibria has been largely and from worldwide high pressure terrains have been used to unravel recognized in chemical systems of interest for the earth phase relationships between amphibole garnet clinopyroxene and sciences after the early experiments of konovalov on albite in the system na2o cao feo mgo al2o3 sio2 h2o azeotropic or congruent transformations ricci 1951 ncfmash at quartz paragonite clinozoisiteand waterexhaustively discussed the fundamentals of singularities saturated conditions extensive analysis of element partitioning two types of singularities were recognized the first between amphibole and clinopyroxene suggests that the fe mg called type m and most relevant is associated with azeopartition coefficient is low at low temperature and high pressure tropic points and the second called type k is related to conditions high temperature blueschists low temperature eclogites the intersection of solvi with compositional loops as and a progressive increase is achieved by an increase in temperature occurs in the alkali feldspar system at low pressures or by a decrease in pressure or by a decrease in the sodium content morse 1970 examples and discussion of both type m of the clinopyroxene mass balance analysis of paragonite eclogites and type k singular points in igneous systems have been and amphibolites suggests that at least two singular reactions are given by morse 1980 e g see chapters 16 and 18 the possible in ncfmash clinopyroxene paragonite quartz widespread occurrence of singularities in igneous systems amphibole albite clinozoisite water garnet absent and is obviously related to the extremely large compositional amphibole clinozoisite garnet clinopyroxene paragonite range of silicate liquids the well known concept of quartz water albite absent albite absent singular equithe thermal barrier or thermal divide implies the librium is relevant for the blueschist eclogite transition whereas occurrence of singular equilibria and their importance garnet absent equilibrium may control the eclogite to amphibolite in the petrogenesis of granites e g modelled in the binary transition a complex arrangement of divariant reactions singular system kalsilite silica lindsley 1966 or basalts e g in reactions and conjugate non degenerate reactions arises in topologies the binary system forsterite silica or in the ternary system at the blueschist eclogite amphibolite transitions schreinemakers forsterite silica diopside or forsterite silica anorthite analysis in p t diagrams and mixed variable t xm xc and presnall et al 1979 has been widely discussed p xm xc diagrams suggest that complex pressure temperature in contrast the significance and implications of singular paths are not mandatory if a recurrent appearance and disappearance point nets at subsolidus conditions have been largely of similar phase assemblages is observed in paragonite bearing mafic undervalued although korzhinskii 1963 analysed azeorocks the p t location of the singular curve net is discussed in tropic transformations in subsolidus open systems only the context of nevado filabride complex mafic rocks recently have applications to metamorphic assemblages

seismic wave attenuation and dispersion resulting from wave induced flow in porous rocks a review one major cause of elastic wave attenuation in heterogeneous porous media is wave induced flow of the pore fluid between heterogeneities of various scales it is believed that for frequencies below 1 khz the most important cause is the wave induced flow between mesoscopic inhomogeneities which are large compared with the typical individual pore size but small compared to the wavelength various laboratory experiments in some natural porous materials provide evidence for the presence of centimeter scale mesoscopic heterogeneities laboratory and field measurements of seismic attenuation in fluid saturated rocks provide indications of the role of the wave induced flow signatures of wave induced flow include the frequency and saturation dependence of p wave attenuation and its associated velocity dispersion frequency dependent shear wave splitting and attenuation anisotropy during the last four decades numerous models for attenuation and velocity dispersion from wave induced flow have been developed with varying degrees of rigor and complexity these models can be categorized roughly into three groups according to their underlying theoretical framework the first group of models is based on biot s theory of poroelasticity the second group is based on elastodynamic theory where local fluid flow is incorporated through an additional hydrodynamic equation another group of models is derived using the theory of viscoelasticity though all models predict attenuation and velocity dispersion typical for a relaxation process there exist differences that can be related to the type of disorder periodic random space dimension and to the way the local flow is incorporated the differences manifest themselves in different asymptotic scaling laws for attenuation and in different expressions for characteristic frequencies in recent years some theoretical models of wave induced fluid flow have been validated numerically using finite difference finite element and reflectivity algorithms applied to biot s equations of poroelasticity application of theoretical models to real seismic data requires further studies using broadband laboratory and field measurements of attenuation and dispersion for different rocks as well as development of more robust methods for estimating dissipation attributes from field data

metamorphic evolution and fluid composition of garnet clinopyroxene amphibolites from the tatra mountains western carpathians relics suggesting an early high pressure eclogite facies stage have been identified in the garnet and clinopyroxene bearing amphibolites of the tatra mountains in the variscan basement of the western carpathians slovakia in these rocks primary omphacite cpx i has been wholly converted to symplectites of diopside cpx ii and plagioclase apart from minor inclusions in the garnet cores amphibole and plagioclase are secondary minerals formed in the kelyphitic rims between garnet and clinopyroxene several generations of amphibole pargasite hornblende cummingtonite actinolite are evidence of a transformation down to greenschist facies conditions thermobarometric calculations from mineral inclusions in the garnet cores yield 670 700 c and 10 15 kbar recording the initial path from upper amphibolite to eclogite facies conditions the attainment of the eclogite facies stability field is inferred from the composition of a reconstructed omphacite jd36 implying a minimum peak pressure of 15 16 kbar conditions of around 650 c and 8 10 kbar record the post eclogite breakdown and partial re equilibration in the amphibolite facies region the earliest fluid inclusions contain high density nitrogen dominated water absent fluid younger are polyphase brines and two phase h2o n2 ch4 inclusions with signs of heterogeneous entrapment of coexisting gas rich and water rich immiscible phases pure nitrogen 0 5 mol ch4 is considered to have been the major component during the high pressure metamorphism in contrast the later aqueous inclusions are interpreted to represent retrogression related fluids the brines have originated by leaching and re entrapment of saline melt inclusions observed in tonalitic trondhjemitic layers of the amphibolite enclosing the eclogitic relics a similar mechanism is assumed for the origin of the h2o n2 ch4 inclusions these represent relics of the primary eclogite facies related n2 inclusions re equilibrated and re entrapped during retrogression under increasing water activity a possible source of n2 and cl rich fluids was primary amphibole which decomposed during the prograde metamorphism from the amphibolite to the eclogite facies the metamorphic pt path is generally clockwise reflecting a steep increase in pressure and temperature during burial followed by decompression and cooling the retrograded eclogites occur in boudins within an allochthonous unit of an inverted metamorphic sequence their exhumation was facilitated by tectonic transport along a ductile shear zone during the variscan orogeny

innovative applications of laser scanning and rapid prototype printing to rock breakdown experiments we present the novel application of two technologies for use in rock breakdown experiments i e close range ground based 3d triangulation scanning and rapid prototype printing these techniques aid analyses of form process interactions across the range of scales relevant to breakdown m m this is achieved through a the creation of dems which permit quantitative description and aanalysis of rock surface morphology and morphological change and b the production of more realistically shaped experimental blocks we illustrate the use of these techniques alongside appropriate data analysis routines in experiments designed to investigate the persistence of fluvially derived features in the face of subsequent wind abrasion and weathering these techniques have a range of potential applications in experimental field and lab based geomorphic studies beyond those specifically outlined here copyright 2008 john wiley sons ltd

mesoscale thermodynamic influences on convection initiation near a surface dryline in a convection permitting ensemble abstractin this study the authors examine initiation of severe convection along a daytime surface dryline in a 10 member ensemble of convection permitting simulations results indicate that the minimum buoyancy bmin of pbl air parcels must be small bmin 0 5 c for successful deep convection initiation ci to occur along the dryline comparing different ensemble members reveals that cape magnitudes allowing for entrainment and the width of the zone of negligible bmin extending eastward from the dryline act together to influence ci since pbl updrafts that initiate along the dryline move rapidly northeast in the vertically sheared flow as they grow into the free troposphere a wider zone of negligible bmin helps ensure adequate time for incipient storms to mature which itself is hastened by larger cape local bmin budget calculations and trajectory analysis are used to quantify physical processes responsible for the reduction of negative buoyancy prior to ci here the grid resolved forcing and fo

equilibration conditions of eclogite lenses from isla margarita venezuela implications for the tectonic evolution of the metasedimentary juan griego group abstract the constituent primary and secondary minerals in a suite of fifteen samples of eclogite amphibole eclogite and garnet amphibolite scattered as boudins and pods in metapelitic schists and gneisses on isla margarita venezuela have been analysed by electron microprobe to augment existing bulk rock chemical data the large sample population available allows spurious effects of stoichiometric fe3 calculation procedures and bulk rock influence to be recognised and eliminated all samples belong to one population with a relatively homogeneous character the equilibration temperatures are derived from fe 2 mg fractionation between garnet and clinopyroxene and range from 525 650 c jadeite contents of clinopyroxene and the persistence of minor stable albite constrain pressures to between 13 and 19 kbar combined with new evidence for high pressure metamorphism in the enclosing metapelites and with existing data on an eclogitic metabasic unit exposed in north eastern isla margarita la rinconada group these data show convincingly that the margarita crustal block is and has been a relatively coherent unit ever since the entire complex suffered high pressure metamorphism in late mesozoic times

modelling the permeability evolution of carbonate rocks abstract diagenesis is a major control on the distribution of porosity and permeability in carbonate rocks and therefore impacts fluid flow in the subsurface while changes in porosity can be directly related to diagenetic petrographic characteristics such as cement distribution and dissolution features quantifying how these textures relate to attendant changes in permeability is more challenging here we demonstrate for the first time how pore scale models representing typical carbonate sediments and their diagenetic histories can be used to quantify the evolution of petrophysical properties in carbonate rocks we generate 3d pore architecture models i e the spatial distribution of solid and pores from 2d binarized images representing the typical textural changes of carbonate sediments following hypothetical diagenetic pathways for each 3d rock model we extract the pore system and convert this into a network representation that allows flow properties to be calculated the resulting porosity and permeability evolution scenarios display several diagenetic tipping points where the decrease in permeability is dramatically larger than expected for the associated decrease in porosity the effects of diagenesis also alter the capillary entry pressures and relative permeabilities of the synthetic cases providing trends that can be applied to real rocks indeed values of porosity and absolute permeability derived from these synthetic 3d rock models are within the range of values measured from nature such diagenetic pathway models can be used to provide constraints on predicted flow behaviour during burial and or uplift scenarios using diagenetic back stripping of real carbonate rocks

reaction spaces and p t paths from amphibole eclogite to greenschist facies in the austroalpine domain oetztal complex the transition from feldspar amphibolite to eclogite is a very wide p t field that extends from some where close to 5 kbar where the garnet amphibole pair starts to appear to 10 20 kbar at albite out reaction then up to 25 30 kbar where an hydrated phase such as amphibole can be stable with pyroxene and garnet thus the assemblage garnet py amphibole tr epidote cz plagioclase ab clinopyroxene di quartz qz fluid is commonly reported in a large number of metamorphic terrains these mineral phases are complex solid solutions which adapt to variations in environmental conditions mainly by means of continuous reactions the reaction space introduced by thompson in 1982a provides a very elegant and powerful tool to approach these high variance assemblages the reactions

metamorphism and phase relations in carbonate rocks from the nevado filabride complex cordilleras beticas spain application of the ttn rt cal qtz gr buffer phase relations and metamorphic conditions have been studied in metacarbonate rocks from the nevado filabride complex cordilleras beticas through forward modeling in many rock samples the assemblage titanite rutile calcite quartz graphite buffered the composition of the c o h fluid present during metamorphism over a wide range of p t conditions fluid compositions computed for this buffer are essentially binary h2o co2 mixtures this buffer also constrains the chemical potentials of tio2 cao and sio2 consequently it is possible to make a thermodynamic projection through these components to predict the stable phase relations consistent with the buffer using this method phase relations have been analyzed in a rock containing the buffer assemblage and paragonite albite phengite epidote and chlorite the equilibrium p t conditions for this assemblage are constrained by minimization of the differences between predicted and observed mineral compositions to be 560 15 c and 9 5 1 kbar conditions obtained compare well with those estimated from other studies in different lithologic units the inferred metamorphic fluid composition is h2o rich

an observational study of the dryline abstract this study presents analyses of data collected in the vicinity of a cloud free dryline that occurred in western oklahoma on 24 may 1989 observations reveal sharp contrasts across the quasi stationary north south dryline during midafternoon of greatest significance is a pronounced gradient of virtual potential temperature although horizontal convergence and vorticity also maximize at the dryline the environment of the 24 may dryline is dominated by vertical mixing that maintains a convective boundary layer cbl on both sides of the dryline the dryline resembles a mixing zone containing varying proportions of hot dry air to the west side and warm moist air from the lowest 200 m within 10 km to the east of the dryline the mixing zone slopes eastward from the surface dryline location then becomes a quasi horizontal elevated moist layer above the cbl east of the dryline saturation point analysis indicates that the mixing zone is characterized by a single mixing line structure defined by

determination of in situ attenuation from full waveform acoustic logs method for the determination of in situ p and s wave attenuation from full waveform acoustic logs are developed for p waves the peak amplitude ratios of the refracted p waves from two different receivers can be used with geometrical spreading taken into account for s waves owing to the contamination by the guided waves its attenuation cannot be determined directly instead s wave attenuation is determined from the attenuation of the guided waves using the partition coefficients normalized partial derivatives of the phase velocity with respect to the body wave velocities analytical forms of these partition coefficients are presented here along with examples for a number of different rock formations granite limestone sandstone and soft sediments the results show that in high velocity rocks the fluid attenuation controls the guided wave attenuation except near the cut off frequency of the pseudo rayleigh wave for low velocity rock formations especially in the case where the s wave velocity is lower than the fluid velocity the s wave attenuation is the main contributor to the guided wave attenuation synthetic microseisgmogram calculated with the measured body wave attenuation agrees well with the actual microseismograms

prediction of convective initiation and storm evolution on 12 june 2002 during ihop_2002 part i control simulation and sensitivity experiments abstract the 12 13 june 2002 convective initiation case from the international h2o project ihop 2002 field experiment over the central great plains of the united states is simulated numerically with the advanced regional prediction system arps at 3 km horizontal resolution the case involves a developing mesoscale cyclone a dryline extending from a low center southwestward with a cold front closely behind which intercepts the midsection of the dryline and an outflow boundary stretching eastward from the low center resulting from earlier mesoscale convection convective initiation occurred in the afternoon at several locations along and near the dryline or near the outflow boundary but was not captured by the most intensive deployment of observation instruments during the field experiment which focused instead on the dryline outflow boundary intersection point standard and special surface and upper air observations collected during the field experiment are assimilated into the arps at hourly inte

finescale radar observations of the 22 may 2002 dryline during the international h2o project ihop abstract the dryline has long been associated with the development of severe thunderstorms in the southern plains during the spring and early summer months the propagation and structure of the dryline are closely tied to surface processes that are neither well understood nor well resolved with current observational capabilities as a result there are often large errors in forecasts of dryline position and structure improvements in radar technology have allowed for better observations of the dryline in recent years here very finescale radar observations taken with the university of massachusetts amherst umass mobile w band radar during an international h2o project ihop double dryline event on 22 may 2002 in the oklahoma panhandle are presented the observations are placed in the context of the dryline secondary circulation which describes flow in a plane normal to the dryline the narrow half power beamwidth of the antenna on the w band 0 18 permitted the measurements of channels of upward 8

convective initiation at the dryline a modeling study abstract a nonhydrostatic three dimensional version of the colorado state university regional atmospheric modeling system csu rams is used to deduce the processes responsible for the formation of drylines and the subsequent initiation of deep moist dryline convection a range of cumuliform cloud types are explicitly simulated along drylines on 15 16 and 26 may 1991 in accordance with observations in the simulations narrow convergence bands along the dryline provide the lift to initiate deep moist convection the thermally direct secondary convective boundary layer cbl circulations along the dryline are frontogenetic and solenoidally forced maximum updrafts reach 5 m s 1 and the bands are 3 9 km wide and 10 100 km or more in length the updrafts penetrate and are decelerated by the overlying stable air above the cbl reaching depths of about 2000 m in the cases studied moisture convergence along the mesoscale updraft bands destabilizes the local sounding to deep convection while simultaneously

mantle echoes associated with deep convection observations and numerical simulations abstract finescale radar observations of intense thermals starting plumes during the early stages of precipitation formation were collected by an airborne doppler radar on two separate days the radar data were recorded as the aircraft flew underneath the developing echoes mantle echoes echoes that often appear as an inverted u shape were observed on both days striking in one of the scans was the resemblance of the echo to a mushroom cloud resulting from a nuclear explosion numerical simulations using a two dimensional cloud resolving model were run to augment the interpretation of the observations one of the important conclusions was the proposed modification to the default bulk microphysical scheme used in the model the default scheme yields a rush to precipitation leading to the early establishment of large precipitation contents which is not supported by the observations suggested modifications to the scheme are presented

metamorphic evolution of norwegian country rock eclogites as deduced from mineral inclusions and compositional zoning in garnets abstract detailed studies of pre early syn and post eclogite mineral associations in some west norwegian country rock eclogites have made it possible to reconstruct their metamorphic evolution pre eclogite stages are represented by various amphibolite facies associations found in the central parts of prograde zoned garnets early and syn eclogite stages are represented by various eclogitic assemblages containing low and high jd omphacites respectively the former located in the intermediate zones and the latter in the outermost rims of prograde zoned garnets and in the matrix post eclogite stages include granulite amphibolite and greenschist facies associations representing replacement phases after higher grade assemblages p t estimates indicate a prograde evolution along an extremely steep p t gradient 7 9 kbar over 100 200 c while the initial post eclogite evolution involved a nearly adiabatic decompression on the order of 10 kbar

resurrection of a reservoir sandstone from tomographic data using three dimensional printing three dimensional 3 d printing provides an opportunity to build lab testable models of reservoir rocks from tomographic data this study combines tomography and 3 d printing to reproduce a sample of the fontainebleau sandstone at different magnifications to test how this workflow can help characterization of transport properties at multiple scales for this sandstone literature analysis has given a porosity of 11 permeability of 455 md mean pore throat radius of 15 m and a mean grain size of 250 m digital rock analysis of tomographic data from the same sample yielded a porosity of 13 a permeability of 251 md and a mean pore throat radius of 15 2 m the 3 d printer available for this study was not able to reproduce the sample s pore system at its original scale instead models were 3 d printed at 5 fold 10 fold and 15 fold magnifications mercury porosimetry performed on these 3 d models revealed differences in porosity 28 37 compared to the literature 11 and to digital calculations 12 7 mercury may have intruded the smallest matrix pores of the printing powder and led to a greater than 50 increase in measured porosity however the 3 d printed models pore throat size distribution 15 m and permeability 350 443 md match both literature data and digital rock analysis the powder based 3 d printing method was only able to replicate parts of the pore system permeability and pore throats but not the pore bodies other 3 d printing methods such as resin based stereolithography and photopolymerization may have the potential to reproduce reservoir rock porosity more accurately

kinematic observations of misocyclones along boundaries during ihop during the international h2o project mobile radars collected high resolution data of several 0 5 2 kmwide vertically oriented vortices or misocyclones along at least five mesoscale airmass boundaries this study analyzes the properties of the misocyclones in three of these datasets 3 10 and 19 june 2002 to verify findings from finescale numerical models and other past observations of misocyclones and to further the understanding of the role that they play in the initiation of deep moist convection and nonsupercell tornadoes misocyclones inflect or disjoint the swath of low level convergence along each boundary to varying degrees depending on the size of their circulations when several relatively large misocyclones are next to each other the shape of low level convergence along each boundary is arranged into a staircase pattern mergers of misocyclones are an important process in the evolution of the vorticity field as a population of small vortices consolidates into a smaller number of larger ones additionally merging misocyclones may affect the mixing of thermodynamic fields in their vicinity when the merger axis is perpendicular to the boundary misocyclones interact with linear and cellular structures in the planetary boundary layers pbls of the air masses adjacent to each boundary cyclonic low level vertical vorticity generated by both types of structures makes contact with each boundary and sometimes is incorporated into preexisting misocyclones intersections of either type of pbl structure with the boundary result in strengthened pockets of low level convergence and typically strengthened misocyclones

low grade blueschist facies metamorphism of metagreywackes franciscan complex northern california metagreywackes in the eastern belt of the franciscan complex contain the assemblage qtz ab lws chl ph pmp fgl hem cal arg or compatible subassemblages blue amphibole first appears in the westernmost part of the belt and pumpellyite is absent in the eastern part the compositions of the coexisting minerals and the nature of the continuous reactions in these low grade blueschists suggest that the distribution of blue amphibole and pumpellyite in the eastern belt of the franciscan complex reflects differences of effective bulk composition rather than differences in physical conditions of metamorphism in rocks lacking pumpellyite white mica may be essential to the growth of blue amphibole but carbonate plays only a limited role the continuous reaction that limits the appearance of blue amphibole and the disappearance of coexisting pumpellyite has the general form pmp chl ab qtz hem h2o femg 1 fgl lws this reaction requires significant hydration as pressure increases in order to produce blue amphibole most of the eastern belt of the franciscan complex formed in limited ranges of temperature and pressure which are estimated to be 240 280 c 6 5 7 5 kbar pressures in the westernmost part of the area were about 1 kbar lower than in the east pressures of about 8 5 10 kbar are estimated for tectonic blocks that contain sodic clinopyroxene

amphibole evolution in variscan eclogite amphibolites from the savona crystalline massif western ligurian alps italy controls on the decompressional p t t path abstract the variscan metamorphic evolution of eclogite amphibolites from the savona crystalline massif is marked by the occurence of calcic amphiboles microtextural relations together with coupled electron microprobe and x ray investigations on amphiboles pointed out a complex decompressional evolution a prograde stage of the evolution in the eclogite facies temperature conditions estimated as ca 620 c is recorded by compositional zoning and inclusions in garnet the eclogitic event pressure conditions 12kbar produced assemblages of garnet omphacite ca amphibole zoisite quartz and rutile composition and zoning of matrix eclogitic amphiboles reveal that the subsequent evolution in the eclogite facies contemplates a late re equilibration under lower conditions of temperature ca 540 c and pressure the eclogitic amphiboles are pargasitic to edenitic hornblendes and are marked by rather high na contents at the m4 site up to 0 5 apfu the forming of coarse grained diopside plagioclase symplectites and of amphibole plagioclase coronas represent the early results of the destabilization of omphacites and garnets in the amphibolite facies pressure conditions of this stage have been estimated of ca 10 kbar while temperature conditions are poorly constrained however the increase in edenite naalsi 1 at the outermost rims of the matrix eclogitic amphiboles and the very high values of edenite and tschermack al 2 mg 1 si 1 components in the coronitic amphiboles subsilicic pargasites suggest that temperature increase accompanied the early decompression to the amphibolite facies subsequent retrogression in the low grade amphibolite facies resulted in the complete breakdown of omphacite producing finer grained symplectites this stage is also recorded by the amphibole growth magnesio hornblendes to edenitic hornblendes with negligible na amounts at the m4 site at the expense of the clinopyroxene symplectites and as outward rims around the coronitic amphiboles frequently amphibolites are completely recrystallized and do not retain any relic of high pressure assemblages temperature conditions for this late amphibolitic event have been estimated of ca 510 c while pressure conditions are inferred in the range 4 7 kbar such a complicated decompressional evolution is indicative of complex uplift tectonics after a subduction event

low temperature eclogites and eclogitic schists in mn rich metabasites in ward creek california mn and fe effects on the transition between blueschist and eclogite

effects of changes in rock microstructures on permeability 3 d printing investigation rocks are naturally heterogeneous two rock samples with identical bulk properties can vary widely in microstructure understanding how the microstructure and bulk properties of rocks then evolve during experiments and computations simulating diagenesis is inherently a multiscale problem the advent of modern 3 d printing has provided an unprecedented opportunity to link those scales by combining the strengths of digital and experimental rock physics in this study we take a computerized tomography scanned model of a natural carbonate pore space then iteratively digitally manipulate 3 d print and measure the flow properties in the laboratory this approach allows us to access multiple scales digitally and experimentally and test hypotheses about how changes in rock microstructure due to compaction and dissolution affect bulk transport properties in a repeatable manner

finescale vertical structure and evolution of a preconvective dryline on 19 june 2002 abstract high resolution airborne cloud radar data and other international h2o project datasets are used to describe the vertical structure of an unusual prefrontal dryline this dryline observed in northwestern kansas on 19 june 2002 first progressed eastward and tilted toward the west and later became more stationary and reversed its tilt toward the moist side the convective boundary layer cbl depth difference also reversed only in the later phase did the dry side cbl become deeper than on the moist side echo and single dual doppler velocity data in a vertical transect across the dryline suggest a solenoidal circulation dynamically consistent with the observed horizontal buoyancy gradient both this gradient and the solenoidal circulation reversed in the later phase simultaneously confluence toward the dryline increased resulting in an increasing moisture gradient as well as a deepening cbl in the dryline convergence zone it is speculated that the baroclinically generated horizontal vortici

zoned sodic amphibole petrologic indicator of changing pressure and temperature during tectonism in the bathurst area new brunswick canada amphibole zoned from an actinolite core through a barroisite layer to a crossite or ferroglaucophane rim coexists with epidote chlorite albite quartz phengite sphene magnetite and calcite in metabasites of the tetagouche group near bathurst new brunswick stratigraphic structural and regional metamorphic evidence suggests that these rocks were situated in the hangingwall of a se dipping subduction zone during the taconian orogeny using microprobe analyses of the coexisting minerals a dehydration reaction and a subsequent hydration reaction have been balanced in the system sio2 al2o3 tio2 fe2o3 fe mg mn o cao na2o k2o h2o so as to describe the development of the zoned amphiboles relatively large coefficients for magnetite in these reactions accord with the absence of sodic amphibole in associated magnetite free metabasites indicating that ferric iron has a significant effect on the transition from greenschist to epidote blueschist fades relatively small residuals of feo mgo and mno show that these components are only weakly partitioned between the reactant and product assemblages the procedure of holland and richardson 1979 has been used to calculate apparentp t paths that trace the growth histories of the zoned amphiboles from a low p environment to a high p environment although the apparent pressure change is implausibly large and the final temperature implausibly low it is clear that the bathurst metabasites followed a very differentp t path than those of the austrian alps despite their identical mineral assemblage

convective initiation on 19 june 2002 during ihop high resolution simulations and analysis of the mesoscale structures and convection initiation 1 the 19 june 2002 convective initiation ci case from the international h2o project ihop is simulated using the arps at 1 km grid spacing it involves three distinct ci groups ci a ci b and ci c associated with a cold front dryline system initial condition at 1800 utc 19 june 2002 was created using the arps 3dvar including standard as well as special observations the simulation captured the three groups of cis rather well with small timing and spatial errors ci a is most typical of dryline initiation vertical cross sections through the initiation locations show typical dryline structures with an upward moisture bulge forced by lifting along the dryline convergence for ci b the model predicted mesoscale structures agree with special ihop aircraft dropsonde observations closely strong low level convergence from opposing cold front and dryline circulations produces deep symmetric upwelling of moist air and the convection is initiated at the crest of the moisture bulge ci c is more typical of frontal convection where deep convection is first initiated at the front edge of the cold air for ci b and ci c north south moisture bands that have dryline characteristics and can be considered multiple drylines and contain enhanced vertical motion and upward moisture bulges intercept the dryline and cold front respectively providing the most favored locations on the dryline or cold front for initiation furthermore the air parcels feeding the initial cells at ci b and ci c have trajectories along the moisture bands and have already experienced uplifting when they reach the dryline and cold front locations