hydrogeochemical conditions and evolution at the aspo hrl sweden abstract the overall hydrogeochemical conditions at and in the near vicinity of the underground experimental aspo hard rock laboratory hrl in se sweden have been investigated groundwater data from more than 400 samples have been compiled and evaluated the groundwater samples represent depths down to 1700 m below sea level and sampling has been performed prior to and during the hrl tunnel excavation episodic events have to a great extent influenced the hydrochemical evolution since the last glaciation which ended some 13 ka ago at that time glacial melt water was flushed under hydraulic pressure down into the fracture system to a depth of at least several hundred metres the next episodic event took place when the baltic freshwater lake transformed into the brackish litorina sea some 7 ka ago at this time aspo was covered by the sea and these denser more saline waters partly replaced the glacial water down to a depth where the density equilibrated with the replacement sea water at some time around 3 4 ka ago aspo started to rise above sea level and meteoric water began to infiltrate the rock the overall trend of increasing salinity with depth may easily be misinterpreted as a fairly simple groundwater system evolving from a two component evolution path between non saline and saline groundwaters however when combining the results from environmental isotopes and the chemical parameters using a new modelling tool named m3 multivariate mixing and mass balance calculations a higher resolution was obtained and a more complex groundwater pattern which reflects the present and paleo hydrogeological events can be recognised the measured groundwater composition was modelled to be a mixture of meteoric past and present baltic seawater glacial or cold climate recharge and brine type of waters the modelling result shows that the processes considered to have a dominating impact on the present aspo groundwater chemistry are mixing both in disturbed and undisturbed systems calcite dissolution and precipitation redox reactions and biological processes the undisturbed groundwater conditions prior to the hrl tunnel construction at aspo consisted of 1 a dominating proportion of meteoric fresh water in the upper 250 m of the aquifer 2 a brackish saline water consisting of mixing proportions of present and ancient baltic sea water and glacial melt water present to a depth of 250 600 m 3 saline water still containing proportions of glacial water which could represent even older glaciations and brines a large portion of which have been stagnant for perhaps millions of years below a depth of 600 m during the hrl tunnel construction there were changes in the composition of the water flowing into the tunnel at different locations although the variation in salinity was relatively small the variations in the mixing proportions of the different water types were substantial

use of groundwater lifetime expectancy for the performance assessment of a deep geologic radioactive waste repository 2 application to a canadian shield environment 1 f j cornaton et al 2008 introduced the concept of lifetime expectancy as a performance measure of the safety of subsurface repositories on the basis of the travel time for contaminants released at a certain point in the subsurface to reach the biosphere or compliance area the methodologies are applied to a hypothetical but realistic canadian shield crystalline rock environment which is considered to be one of the most geologically stable areas on earth in an approximately 10 10 1 5 km3 hypothetical study area up to 1000 major and intermediate fracture zones are generated from surface lineament analyses and subsurface surveys in the study area mean and probability density of lifetime expectancy are analyzed with realistic geologic and hydrologic shield settings in order to demonstrate the applicability of the theory and the numerical model for optimally locating a deep subsurface repository for the safe storage of spent nuclear fuel the results demonstrate that in general groundwater lifetime expectancy increases with depth and it is greatest inside major matrix blocks various sources and aspects of uncertainty are considered specifically geometric and hydraulic parameters of permeable fracture zones sensitivity analyses indicate that the existence and location of permeable fracture zones and the relationship between fracture zone permeability and depth from ground surface are the most significant factors for lifetime expectancy distribution in such a crystalline rock environment as a consequence it is successfully demonstrated that the concept of lifetime expectancy can be applied to siting and performance assessment studies for deep geologic repositories in crystalline fractured rock settings

an amoeboid olivine inclusion aoi in ck3 nwa 1559 comparison to aois in cv3 allende and the origin of aois in ck and cv chondrites an amoeboid olivine inclusion in ck3 nwa 1559 0 54 1 3 mm consists of a diopside rich interior approximately 35 vol and an olivine rich rim approximately 65 vol it is the first aoi to be described in ck chondrites the apparent paucity of these inclusions is due to extensive parent body recrystallization the aoi interior contains irregular 3 15 m sized al bearing diopside grains approximately 70 vol 2 20 m sized pores approximately 30 vol and traces of approximately 2 m plagioclase grains the 75 160 m thick rim contains 20 130 m sized ferroan olivine grains some with 120o triple junctions a few coarse 25 50 m sized patches of plagioclase with 2 18 m thick diopside rinds occur in several places just beneath the rim the occurrence of olivine rims around aoi 1 and around many aois in cv3 allende suggests that ck and cv aois formed by the acquisition of porous forsteritic rims around fine grained rimless cais that consisted of diopside anorthite melilite and spinel individual aois in carbonaceous chondrites may have formed after transient heating events melted their olivine rims as well as portions of the underlying interiors in aoi 1 coarse plagioclase grains with diopside rinds crystallized immediately below the olivine rim secondary parent body alteration transformed forsterite in the rims of cv and ck aois into more ferroan olivine some of the abundant pores in the interior of aoi 1 may have formed during aqueous alteration after fine grained melilite and anorthite were leached out chondrite groups with large chondrules tend to have large aois aois that formed in dust rich nebular regions where cv and ck chondrites later accreted tend to be larger than aois from less dusty regions

ree and y in groundwater in the upper 1 2 km of proterozoic granitoids eastern sweden assessing the role of composition and origin of groundwaters geochemistry of fractures and organic inorganic aqueous complexation yttrium and rare earth elements yrees are studied in groundwater in the shallow regolith aquifer and the fracture networks of the upper 1 2 km of paleoproterozoic granitoids in boreal europe laxemar and forsmark areas sweden the study includes groundwater sampled via a total of 34 shallow boreholes reaching the bottom of the regolith aquifer and 72 deep boreholes with equipment designed for retrieval of representative groundwater at controlled depths in the fractured bedrock the groundwater composition differs substantially between regolith and fracture groundwater and between areas which affects the dissolved yree features including concentrations and nasc normalized patterns in the fresh groundwater in the regolith aquifers highest yree concentrations occur 10th and 90th percentile laxemar 4 4 82 mu g l 1 forsmark 1 9 19 mu g l 1 especially in the slightly acidic groundwater ph 6 3 7 2 laxemar where the normalized yree patterns are slightly enriched in light rees la nasc y nasc 1 1 2 4 in the recharge areas where redox potentials of the regolith groundwater is more moderate negative ce anomaly laxemar 0 37 0 45 forsmark 0 15 0 92 and positive y anomaly mainly in forsmark 1 0 1 7 are systematically more pronounced than in discharge areas the significant correlations between the yree features and dissolved organic carbon minor elements and somewhat ph suggest a strong control of humic substances hss together with al rich colloids and redox sensitive fe mn hydrous precipitates on the dissolved yree pools in the bedrock fractures the groundwater is circumneutral to slightly basic and displays yree concentrations that are at least one order of magnitude lower than the regolith groundwater and commonly below detection limit in the deep brackish and saline groundwater with some exceptions such as la and y at intermediate depth 50 m where groundwater of meteoric origin percolates the la nasc y nasc values moderately to substantially decrease laxemar 0 24 2 65 forsmark 0 02 0 06 and y and ce anomalies are negligible as compared to the regolith groundwater aqueous speciation modeling predicts substantial binding of dissolved y and la respectively to hss this in turn suggests that the features of the yree pool in the meteoric fracture groundwater are dominantly controlled by the capacity of fracture minerals to sorb hs ligands inherited from the overlying terrestrial regolith in the deep bedrock fractures 100 200 m the yree features vary substantially with the groundwater paleo origin in laxemar where groundwater with pronounced glacial origin percolates the yree concentrations decrease with increasing mixing fraction of glacial melt water there the dissolved yrees are mostly bound to hss and inherited their fractionation features la nasc y nasc 0 15 2 1 from water rock interaction in the intermediate bedrock fractures in forsmark the yree and heavy ree enrichment la nasc y nasc 0 007 0 23 are more systematic in the groundwater with pronounced marine origin due to water mineral interactions in the sea sediment and in the fractures while infiltrating and percolating yree features significantly change in the deep saline groundwater with a long residence time which displays la nasc y nasc similar to those of the local bedrock the findings of this study are relevant in terms of safety assessment for nuclear waste disposal in crystalline rock carrying groundwater influenced by various paleo climatic recharges c 2014 elsevier ltd all rights reserved

implications of the carbonaceous chondrite mn cr isochron for the formation of early refractory planetesimals and chondrules abstract an excellent 53 mn 53 cr isochron for bulk ci cm co cv cb and ungrouped c3 chondrites seems to suggest that each carbonaceous chondrite group acquired its mn cr ratio 4568 1 myr ago this age is indistinguishable from the age of ca al rich inclusions cais which is considered to be the start of the solar system t 0 however carbonaceous chondrites were not assembled until at least 1 5 5 myr after t 0 to judge by the 207 pb 206 pb and 26 al 26 mg ages of the chondrules within them and by the fact that they were not melted by heat from the decay of 26 al presumably therefore these meteorites inherited their bulk mn cr isochron from precursor materials which experienced mn cr fractionation at t 0 as a possible physical mechanism for how the isochron was established initially and later inherited by the carbonaceous chondrites we propose the rapid formation at t 0 of planetesimals that were variably depleted in moderately volatile elements and hence had variably low mn cr the planetesimals and the undepleted high mn cr primitive dust from which they were made shared the same initial e 53 cr and therefore evolved on an isochron we suggest that later impact disruption of the planetesimals produced dusty debris which became mixed in various proportions with unprocessed high mn cr dust before accreting to the carbonaceous chondrite parent bodies with mixing in a closed system the isochron was unchanged we infer that some debris rich material was converted to chondrules prior to accretion the chondrules could have been formed by flash melting of the mixed dust or could instead have been made directly by the impact splashing of molten planetesimals or by condensation from impact generated vapor plumes

oxygen isotope compositions of chondrule phenocrysts and matrix grains in kakangari k grouplet chondrite implication to a chondrule matrix genetic relationship abstract to investigate a possible relationship between chondrules and matrix we studied mineralogy mineral chemistry and in situ o isotope compositions of chondrules clastic matrix grains and amoeboid olivine aggregates aoas in the kakangari k grouplet chondrite most olivines and low ca pyroxenes in the kakangari chondrules matrix and aoas have similar magnesium rich compositions fo 95 97 0 3 0 5 wt mno and en 90 96 respectively these rather uniform chemical compositions of the different chondritic components are likely due to partial fe mg mn equilibration during thermal metamorphism experienced by the host meteorite oxygen isotope compositions of olivine and low ca pyroxene grains in chondrules and matrix plot along a slope 1 line on a three o isotope diagram and show a range from 16 o enriched composition similar to that of the sun to 16 o depleted composition similar to the terrestrial o isotope composition most olivines and low ca pyroxenes in chondrules are 16 o poor and plot on or close to the terrestrial mass fractionation line mean 17 o values 2 standard deviations 0 0 0 8 and 0 2 0 9 for olivine and pyroxene respectively consistent with the previously reported compositions of bulk chondrules 17 o 0 16 0 70 in addition to these 16 o poor grains a coarse grained igneous rim surrounding a porphyritic chondrule contains abundant 16 o rich relict olivines 17 o 24 oxygen isotope compositions of olivines and low ca pyroxenes in matrix show a bimodal distribution 12 out of 13 olivine and 4 out of 17 pyroxene grains measured are similarly 16 o rich 17 o 23 5 2 9 others are similarly 16 o poor 17 o 0 1 1 7 due to slow oxygen self diffusion olivines and low ca pyroxenes largely retained their original oxygen isotope compositions the nearly identical o isotope compositions between the chondrule phenocrysts and the 16 o poor matrix grains suggest both chondrules and matrix of kakangari sampled isotopically the same reservoirs in addition the presence of abundant 16 o rich grains in matrix and the chondrule igneous rim suggests both components acquired similar precursor inventories these observations imply that chondrules and matrix in kakangari are genetically related in the sense that material that formed matrix was one of the precursors of chondrules and chondrules and some fraction of matrix experienced the same thermal processing event the 16 o enriched bulk matrix value compared to the bulk chondrules reported previously is likely due to presence of abundant 16 o rich grains in the kakangari matrix

oxygen isotopic evolution of amoeboid olivine aggregates in the reduced cv3 chondrites efremovka vigarano and leoville amoeboid olivine aggregates aoas from the reduced cv chondrites efremovka vigarano and leoville consist of forsteritic olivine feni metal and a refractory component composed of spinel al diopside anorthite secondary ferrous olivine and alkali rich minerals nepheline and sodalite commonly observed in the oxidized cvs are rare mineralogy and chemical compositions of aoas are similar to those predicted by equilibrium thermodynamic condensation models suggesting that aoas formed primarily by gas solid condensation over a narrow temperature range slightly below the temperatures over which most ca al rich inclusions cais formed aoas in the reduced cvs preserve a 1st generation 16o rich signal 17 18o 40 similar to that observed in many cais suggesting that these refractory objects originated from a common source in the solar nebula in fact aoas and many fine grained cais may have formed by the same processes but at slightly different temperatures and can be considered a single class of refractory objects alteration of the aoas is manifested by differing extents of 16o depletion in original aoa minerals feo enrichment in olivine and formation of interstitial very fine grained na bearing phases from the six aoas and one fine grained melilite pyroxene rich cai examined in this study five distinct patterns of alteration were identified 1 one unaltered aoa from vigarano is characterized by 16o rich forsterite without feo rich rims and interstitial na bearing phases 2 weak alteration in the melilite pyroxene rich cai is characterized by incomplete 16o depletion in some melilite and precipitation of na bearing phases near the cai rim 3 oxygen isotopic composition and mineralogy are correlated in two aoas from leoville with 16o rich olivine 16o poor anorthite and a range of intermediate compositions in al diopside this pattern is consistent with model diffusion between original grains and a 16o poor reservoir during a relatively short term 60 yr high temperature 900 1100 c event 4 original forsterite has been enriched in feo but remained 16o rich in one aoa from vigarano this result is consistent with the slower rate of diffusion of o than fe and mg in olivine at least some interstitial phases are 16o rich and na bearing phases are abundant in this aoa 5 in contrast oxygen isotopic composition and fo content are correlated in two aoas from efremovka the olivine in these aoas tends to have forsteritic 16o rich cores and feo rich 16o depleted rims the general correlation between oxygen isotopic composition and fo content is difficult to model by diffusion and may have formed instead by aqueous dissolution and precipitation along the margins of preexisting olivine grains independent evidence for aqueous alteration of the efremovka aoas is provided by oh rich signals detected during ion beam sputtering of some of the 16o poor olivine elevated 16oh count rates and order of magnitude increases in 16oh detected during single analyses reflect trapping of an aqueous phase in 16o depleted olivine an elevated 16oh signal was also detected in one analysis of relatively 16o poor melilite in the melilite pyroxene cai from vigarano suggesting that this object also was altered by aqueous fluid

observations of nearshore circulation alongshore uniformity 1 nearshore circulation observed for 4 months on a 200 m long stretch of natural beach during the sandyduck field experiment is shown to be alongshore uniform an alongshore momentum balance between wind and wave forcing and bottom stress cross shore integrated between the shoreline and approximately 4 m water depth holds on each of five instrumented cross shore transects skill 0 87 the corresponding five best fit drag coefficients are similar consistent with the assumption that terms in the momentum balance associated with alongshore nonuniformity are negligible in addition the alongshore nonuniformity of the circulation and bathymetry were examined at five cross shore locations except near the shoreline the circulation and bathymetry were rarely strongly alongshore nonuniform and the circulation nonuniformities were usually no larger than expected from current meter noise alone near the shoreline the bathymetry was more irregular and the circulation was often detectably nonuniform although no relationship between bathymetric and circulation nonuniformities was found the closure of the alongshore momentum balances on cross shore transects and the observed alongshore uniformity of the circulation on four of five alongshore transects demonstrates that the simplified dynamics of alongshore uniform circulation are valid during the experiment

hydraulic testing of low permeability formations a case study in the granite of cadalso de los vidrios spain abstract in recent years the study of low permeability geological formations has undergone considerable development this is mainly due to the use of natural geological barriers to confine waste disposals preventing leaking water from bringing contaminants into contact with the biosphere and the groundwater resources in that context the spanish geological survey igme spanish acronym supported by the national radioactive waste management agency enresa spanish acronym and with the technical advice of the swedish nuclear fuel and waste management company skb designed and built a mobile hydrogeological unit umh spanish acronym for low permeability formations characterization which has been operational since 1997 and has been used for different purposes among other possibilities the umh allows conducting constant transient state flow rate injection tests constant head transient state injection tests pseudo stationary state injection tests pressure fall off tests slug tests and pulse tests the main objectives of this article are to describe the hydraulic characterization methodology used by igme to carry out hydraulic tests in low permeability environment to compare different testing methods and to summarize the results that have been obtained when characterizing the leucogranites of cadalso de los vidrios in spain the study area presents an increasing interest for granite production inside the community of madrid the petrological and structural characteristics of the granite rocks and the core samples extracted from a 200 m deep borehole investigation are described the packer tests are conducted with the mobile hydrogeological unit the tests are interpreted with the help of analytical solutions the main software used is hytool an open source matlab toolbox that provides a library of analytical solutions and a set of routines to facilitate hydraulic tests interpretation the results allow the elaboration of a comparative analysis of the applied hydraulic tests and to define the hydraulic conductivity optimum application interval most suited for each of the used methods hydraulic conductivity values obtained varies from 3 20 10 7 m s for the upper weathered layer to 2 80 10 12 m s for the test section from 97 36 to 116 15 m depth finally the hydraulic conductivity values obtained in this area are compared with other case studies of granite formations around the world

olivine in terminal particles of stardust aerogel tracks and analogous grains in chondrite matrix abstract the dearth of both major and minor element analyses of anhydrous silicate phases in chondrite matrix has thus far hindered their comparison to the wild 2 samples we present 68 analyses of olivine fa 0 97 in the coarse grained terminal particles of stardust aerogel tracks and a comprehensive dataset 10 3 analyses of analogous olivine grains 5 30 m isolated in ci cm cr ch co cv3 oxidized cv3 reduced c3 ungrouped acfer 094 and ningqiang l ll 3 0 4 eh3 and kakangari chondrite matrix these compositions reveal that wild 2 likely accreted a diverse assortment of material that was radially transported from various carbonaceous and ordinary chondrite forming regions the wild 2 olivine includes amoeboid olivine aggregates aoas refractory forsterite type i and type ii chondrule fragments and or microchondrules and rare relict grain compositions in addition we have identified one terminal particle that has no known compositional analog in the meteorite record and may be a signature of low temperature aqueous processing in the kuiper belt the generally low cr content of feo rich olivine in the stardust samples indicates that they underwent mild thermal metamorphism akin to a petrologic grade of 3 05 3 15

the classification and complex thermal history of the enstatite chondrites we have carried out instrumental neutron activation analyses of 11 enstatite chondrites and electron microprobe analyses of 17 enstatite chondrites most of which were previously little described we report here the third known eh5 chondrite lew 88180 and an unusual el6 chondrite lew 87119 new data on four el3 chondrites alh 85119 eet 90299 pca 91020 and mac 88136 which is paired with mac 88180 and mac 88184 the second el5 chondrite til 91714 and an unusual metal rich and sulfide poor el3 chondrite lew 87223 the often discussed differences in mineral composition displayed by the eh and el chondrites are not as marked after the inclusion of the new samples in the database and the two classes apparently experienced a similar range of equilibration temperatures however texturally the el chondrites appear to have experienced much higher levels of metamorphic alteration than eh chondrites of similar equilibration temperatures most of the petrologic type criteria are not applicable to enstatite chondrites and unlike the ordinary chondrites texture and mineralogy reflect different aspects of the meteorite history we therefore propose that the existing petrologic type scheme not be used for enstatite chondrites we suggest that while textural type reflects peak metamorphic temperatures the mineralogical type reflects equilibration during postmetamorphic probably regolith processes unlike the ordinary chondrites and eh chondrites el chondrites experienced an extensive low temperature metamorphic episode there are now a large number of enstatite meteorite breccias and impact melts and apparently surface processes were important in determining the present nature of the enstatite chondrites

a continuum representation of fracture networks part i method and basic test cases abstract a method to represent fracture networks as grid cell conductivities in a continuum model is described and evaluated the method is developed for a sparsely fractured rock with a conductivity field that is dominated by major fractures and fracture zones for such a fracture system it is believed that an accurate description of the correlation and anisotropy structure is essential the proposed method will capture these features of the fracture system the basic approach of the method is to evaluate accurate cell conductivity values for a staggered grid arrangement i e velocities are stored at cell walls and scalars at cell centres the balance of forces i e the darcy law is evaluated for a control volume centred around the point where the velocity component is stored fractures are assumed to have a thickness and conductivity the conductivity of a velocity control volume is calculated from the intersecting volume between the fracture and the velocity control volume intersecting volumes with their respective conductivities are added up to form the control volume conductivity the general conclusion is that the method results in accurate simulations it is expected that the method can be utilised in many practical groundwater simulations this statement is based on the results from three test cases with analytical solution and one test case where results are compared with those from established theories

inter diffusion coefficients parallel to the c axis in iron rich clinopyroxenes calculated from microstructures subsolidus marginal zoning in calcium poor clinopyroxenes and intermediate zoning in discontinuously zoned subcalcic to calcium rich clinopyroxenes from ironrich igneous rocks is used to calculate the interdiffusion coefficient dca fe mg parallel to the crystallographic caxis wagner s mathematical models describing the displacement of interfaces in solids as the result of isothermal diffusion are adopted the steady state heat flow equation is used to approximate the diffusion times the calculated interdiffusion coefficients are of a reasonable order of magnitude viz 6 0 10 20 2 0 10 17cm2 sec 1 at about 900 c

boat towed radio magnetotelluric and controlled source audio magnetotelluric study to resolve fracture zones at aspo hard rock laboratory site sweden boat towed radio magnetotelluric rmt measurements using signals between 14 and 250 khz have attracted increasing attention in the near surface applications for shallow water and archipelago areas

delineating fracture zones using surface tunnel surface seismic data p s and s p mode conversions a surface tunnel surface seismic experiment was conducted at the aspo hard rock laboratoryto study the seismic response of major fracture systems intersecting the tunnel a newly developedthree com

experimental study of incongruent evaporation kinetics of enstatite in vacuum and in hydrogen gas variations in bulk mg si ratios in the various groups of chondritic meteorites indicate that mg si fractionation occurred in the primitive solar nebula enstatite mgsio3 evaporates incongruently forming forsterite mg2sio4 as an evaporation residue therefore evaporation of enstatite produces mg si variations in solid mg rich and gas si rich and must be considered as a probable process responsible for mg si fractionation recorded in chondrites to understand the evaporation kinetics of enstatite incongruent evaporation experiments on enstatite single crystals have been carried out in vacuum and in hydrogen gas at temperatures of 1300 to 1500 c a polycrystalline forsterite layer is formed on the surface of enstatite by preferential evaporation of the sio2 component both in vacuum and in hydrogen gas the thickness of the forsterite layer in vacuum increases with time in the early stage of evaporation and later the thickness of the forsterite layer remains constant several microns this is due to the change in the rate limiting process from surface reaction plus nucleation and growth to diffusion in the surface forsterite layer the activation energy of the diffusion controlled evaporation rate constant of enstatite is 457 58 kj mol a thinner forsterite layer is formed on the surface of enstatite in hydrogen gas than in vacuum evaporation of enstatite in hydrogen gas is also considered to be controlled by diffusion of ions through the forsterite layer the thin forsterite layer formed in hydrogen gas is ascribed to the enhanced evaporation rate of forsterite in the presence of hydrogen gas the results are applied to incongruent evaporation under the solar nebular conditions the steady thickness of the forsterite of nebular pressure temperature conditions is estimated to be submicron because of the enhanced evaporation rate of forsterite under hydrogen rich nebular conditions if evaporated gases are taken away immediately and no back reaction occurs an open system because enstatite grains in the solar nebula would be comparable to the estimated steady thickness of forsterite evaporation of such enstatite grains under kinetic conditions could play an important role in producing variations in mg si ratios between solid and gas in the solar nebula

shear instabilities of wave driven alongshore currents the present state of research into and understanding of shear waves is appraised in this paper these motions which result from an instability of an alongshore wave driven current are described their theoretical explanation is recounted and the history of their discovery is related the various investigations into their genesis which attempted to develop an understanding of when and why they occur are summarized and more recent research into their finite amplitude development is discussed focusing on the understanding gained attention is also given to observations of shear waves made in the field and attempts to observe them in the laboratory finally work that still needs to be done is described

26al 26mg systematics of ca al rich inclusions amoeboid olivine aggregates and chondrules from the ungrouped carbonaceous chondrite acfer 094 we report in situ magnesium isotope measurements of 7 porphyritic magnesium rich type i chondrules 1 aluminum rich chondrule and 16 refractory inclusions 14 ca al rich inclusions cais and 2 amoeboid olivine aggregates aoas from the ungrouped carbonaceous chondrite acfer 094 using a cameca ims 6f ion microprobe both aoas and 9 cais show radiogenic 26mg excesses corresponding to initial 26al 27al ratios between 5 x 10 5 and 7 x 10 5 suggesting that formation of the acfer 094 cais may have lasted for 300 000 years four cais show no evidence for radiogenic 26mg three of these inclusions a corundum rich a grossite rich and a pyroxene hibonite spherule cai are very refractory objects and show deficits in 26mg suggesting that they probably never contained 26al the fourth object without evidence for radiogenic 26mg is an anorthite rich igneous type c cai that could have experienced late stage melting that reset its al mg systematics significant excesses in 26mg were observed in two chondrules the inferred 26al 27al ratios in these two chondrules are 10 3 7 4 10 6 and 6 0 3 8 10 6 errors are 2 suggesting formation and myr after cais with the canonical 26al 27al ratio of 5 10 5 these age differences are consistent with the inferred age differences between cais and chondrules in primitive ordinary ll3 0 ll3 1 and carbonaceous co3 0 chondrites

paleo redox boundaries in fractured granite at the earth s surface fe ii often oxidises and forms insoluble fe iii oxyhydr oxides whose particle size and structure depend on solution composition and temperature during formation and afterwards bacterial processes and exposure to reducing environments reduces them again releasing dissolved iron to the groundwater during such cycling the fe isotopes fractionate to an extent that is expected to depend on temperature in this study we report on the use of fe oxides as paleo redox indicators using their structure morphology and fe composition as a clue for formation conditions in samples taken from 120 m drill cores in granite from se sweden x ray amorphous superparamagnetic nanometre sized fe oxides are confined to fractures of the upper 50 m whereas well crystalline fe oxides with particle sizes typical for soils occur down to 110 m we also identified hematite with a particle size of 100 nm similar to hematite of hydrothermal origin the fe isotope composition of the fine grained fe oxides 1 56fe 1 irmm 14 referenced scatter significantly compared to the distribution previously observed for hydrothermal material 0 26 56fe 0 12 and they are dominantly heavier than fe bearing silicates from fractures 0 56 56fe 0 35 this is consistent with formation by low temperature weathering where fe silicates dissolve fe ii oxidises and fe iii oxides precipitate the x ray amorphous nanometre sized nature of near surface fe oxides suggests recent formation the deeper situated well crystalline fe oxides are more mature and we interpret that they record earlier oxidising events they exist in fractures that are not significantly altered indicating formation during periods of oxidation our results show that oxygenated water may reach depths of 110 m in fractured granite the absence of natural low temperature fe oxides from deeper drill cores suggests that oxygenated waters do not readily penetrate beyond about 100 m and suggests that radioactive waste repositories located at a depth of 500 m should be well protected from oxygenated waters

modeling the alongshore current on barred beaches mean alongshore currents observed on two barred beaches are compared with predictions based on the one dimensional time and depth averaged alongshore momentum balance between forcing by breaking waves wind and 10 100 km scale alongshore surface slopes bottom stress and lateral mixing the observations span 500 hours at egmond netherlands and 1000 hours at duck north carolina and include a wide range of conditions with maximum mean currents of 1 4 m s including rollers in the wave forcing results in improved predictions of the observed alongshore current structure by shifting the predicted velocity maxima shoreward and increasing the velocity in the bar trough compared with model predictions without rollers for these data wave forcing balances the bottom stress within the surfzone with the other terms of secondary importance the good agreement between observations and predictions implies that the one dimensional assumption holds for the range of conditions examined despite the presence of small alongshore bathymetric nonuniformities with stronger bathymetric variations the model skill deteriorates particularly in the bar trough consistent with earlier modeling and laboratory studies

mineralogy and petrology of amoeboid olivine inclusions in co3 chondrites relationship to parent body aqueous alteration petrographic and mineralogic studies of amoeboid olivine inclusions aois in co3 carbonaceous chondrites reveal that they are sensitive indicators of parent body aqueous and thermal alteration as the petrologic subtype increases from 3 0 to 3 8 forsteritic olivine fa0 1 is systematically converted into ferroan olivine fa60 75 we infer that the fe si and o entered the assemblage along grain boundaries forming ferroan olivine that filled fractures and voids as temperatures increased fe 2 from the new olivine exchanged with mg 2 from the original aoi to form diffusive haloes around low feo cores cations of mn 2 ca 2 and cr 3 were also mobilized the systematic changes in aoi textures and olivine compositional distributions can be used to refine the classification of co3 chondrites into subtypes in subtype 3 0 olivine occurs as small forsterite grains fa0 1 free of ferroan olivine in petrologic subtype 3 2 narrow veins of feo rich olivine have formed at forsterite grain boundaries with increasing alteration these veins thicken to form zones of ferroan olivine at the outside aoi margin and within the aoi interior by subtype 3 7 there is a fairly broad olivine compositional distribution in the range fa63 70 and by subtype 3 8 no forsterite remains and the high fa peak has narrowed fa64 67 even at this stage there is incomplete equilibration in the chondrite as a whole e g data for coarse olivine grains in isna co3 8 chondrules and lithic clasts show a peak at fa39 we infer that the mineral changes in aoi identified in the low petrologic types required aqueous or hydrothermal fluids whereas those in subtypes 3 3 largely reflect diffusive exchange within and between mineral grains without the aid of fluids

nonlinear shear instabilities of alongshore currents over barred beaches the nonlinear dynamics of finite amplitude shear instabilities of alongshore currents in the nearshore surf zone over barred beach topography are studied using numerical experiments these experiments extend the recent study of allen et al 1996 which utilized plane beach constant slope topography by including shore parallel sandbars the model involves finite difference solutions to the nonlinear shallow water equations for forced dissipative initial value problems and employs periodic boundary conditions in the alongshore direction effects of dissipation are modeled by linear bottom friction forcing for the alongshore currents is specified using a model formulated by thornton and guza 1986 t g distinct classes of flows develop depending on the dimensionless parameter q the ratio of an advective to a frictional timescale for q greater than a critical value qc the flows are linearly stable for q qc q 0 the flow is unstable for small values of q equilibrated shear waves develop that propagate alongshore at phase speeds and wavelengths that are in agreement with predictions from linear theory for the most unstable mode at intermediate values of q unsteady vortices form and exhibit nonlinear interactions as they propagate alongshore occasionally merging pairing or being shed seaward of the sandbar at the largest values of q examined the resulting flow field resembles a turbulent shear flow a net effect of the instabilities at large aq is to distribute the time averaged alongshore momentum from local maxima of the t g forcing located over the sandbar and near the shore into the region of the trough the across shore structure of the time averaged alongshore current is in substantially better qualitative agreement with observations than that given by a steady frictional balance with t g forcing the results point to the possible existence in the nearshore surf zone of an energetic eddy field associated with instabilities of the alongshore current

element mobility studies of two drill cores from the gotemar granite krakemala test site southeast sweden abstract a pilot study was carried out on two relatively deep drill cores 600 m from the gotemar granite massif in s e sweden this granite is typical of the 1400 ma anorogenic granites of the northern hemisphere samples from representative unfractured parts of the cores together with four samples taken along a profile tangential to a fracture plane at 280 m depth were investigated chemically mineralogically and isotopically the results show that after crystallisation subtle and pervasive open system modifications of the trace element chemistry of the granite took place whereas the major element chemistry and minera logical data emphasised the relative homogeneity of the gotemar granite samples investigated trace elements such as u rb and pb revealed irregular distributions which are probably the result of large scale hydrothermal alteration processes this conclusion is supported by isotopic studies which indicate that whole rock samples were open to a gain or loss of pb and possibly u at 420 171 ma ago in addition isotopic data for u pb and u ra are consistent with a recent minor loss of u the pervasive alteration and the more recent mobilisation of u are evident to a depth of at least 600 m the effects are most prevalent along major fracture zones and within the upper 250 300 m of one drill hole where a high frequency of crush zones has been noted higher fe oxidation ratios higher rb contents lower u contents and correspondingly higher th u ratios all characterise this zone

joint inversion of lake floor electrical resistivity tomography and boat towed radio magnetotelluric data illustrated on synthetic data and an application from the aspo hard rock laboratory site sweden joint inversion of lake floor electrical resistivity tomography and boat towed radio magnetotelluric data illustrated on synthetic data and an application from the aspo hard rock laboratory site sweden

site descriptive modelling during characterization for a geological repository for nuclear waste in sweden the swedish programme for geological disposal of spent nuclear fuel is approaching major milestones in the form of permit applications for an encapsulation plant and a deep geologic repository this paper presents an overview of the bedrock and surface modelling work that comprises a major part of the on going site characterization in sweden and that results in syntheses of the sites called site descriptions the site description incorporates descriptive models of the site and its regional setting including the current state of the geosphere and the biosphere as well as natural processes affecting long term evolution the site description is intended to serve the needs of both repository engineering with respect to layout and construction and safety assessment with respect to long term performance the development of site descriptive models involves a multi disciplinary interpretation of geology rock mechanics thermal properties hydrogeology hydrogeochemistry transport properties and ecosystems using input in the form of available data for the surface and from deep boreholes

an experimental study of enstatite formation reaction between forsterite and si rich gas experiments on the reaction between forsterite and si rich gas were carried out in a vacuum furnace using a newly designed double capsule technique a thin layer of enstatite was formed on the surface of the forsterite by the reaction the thickness of the enstatite layer changes in proportion to the square root of time parabolic rate law indicating that the rate is controlled by diffusion in the enstatite layer the activation energy and the logarithm of the pre exponential term of the parabolic rate constant were obtained at505 188 kj mol and3 6 5 6 cm2 s respectively it is difficult to definitely determine the mechanism of the reaction from these values but consideration of strain generation due to volume change during the reaction may suggest that the counter diffusion of silicon and magnesium takes place along the grain boundary in the enstatite layer the degree of the reaction of forsterite with si rich residual gas in the primordial solar nebula is discussed based upon the measured reaction rate and it is suggested that very little enstatite was formed by this reaction in the cooling nebula if the grain size of the forsterite crystals was controlled by homogeneous nucleation theory

the nature and origin of type b1 and b2 caal rich inclusions in the allende meteorite abstract the type b ca al rich inclusions in the allende carbonaceous chondrite form a continuous range from the mineralogically concentrically zoned b1 subtype to the unzoned b2 subtype these subtypes differ in i structure texture grain size and shape ii mineralogical proportions and compositions iii accessory mineralogy iv relative abundance of spinel framboids v rim layering vi major element chemistry and vii degree of secondary alteration these differences together with observations on the crystallization of synthetic melts suggest that the b1 inclusions crystallised relatively rapidly from molten parental material while b2 types crystallised relatively slowly close to the solidus from material that had not been completely melted the same data are used to construct an evaporative residue model for the origin of the parental type b materials in the model dust in the protosolar nebula was heated with removal of more volatile elements leaving completely melted type b1 residues at the highest temperatures and incompletely melted less highly evaporated type b2 residues at lower temperatures

thermochemical stability of low iron manganese enriched olivine in astrophysical environments low iron manganese enriched lime olivine grains are found in cometary samples returned by the stardust mission from comet 81p wild 2 similar grains are found in primitive meteoritic clasts and unequilibrated meteorite matrix lime olivine is thermodynamically stable in a vapor of solar composition at high temperature at total pressures of a millibar to a microbar but enrichment of solar composition vapor in a dust of chondritic composition causes the feo mno ratio of olivine to increase the compositions of lime olivines in primitive materials indicate oxygen fugacities close to those of a very reducing vapor of solar composition the compositional zoning of lime olivines in amoeboid olivine aggregates is consistent with equilibration with nebular vapor in the stability field of olivine without re equilibration at lower temperatures a similar history is likely for lime olivines found in comet samples and in interplanetary dust particles lime olivine is not likely to persist in nebular conditions in which silicate liquids are stable

ca al rich inclusions amoeboid olivine aggregates and al rich chondrules from the unique carbonaceous chondrite acfer 094 i mineralogy and petrology based on their mineralogy and petrography 200 refractory inclusions studied in the unique carbonaceous chondrite acfer 094 can be divided into corundum rich 0 5 hibonite rich 1 1 grossite rich 8 5 compact and fluffy type a spinel melilite rich 50 3 pyroxene anorthite rich 7 4 and type c pyroxene anorthite rich with igneous textures 1 6 ca al rich inclusions cais pyroxene hibonite spherules 0 5 and amoeboid olivine aggregates aoas 30 2 melilite in some cais is replaced by spinel and al diopside and or by anorthite whereas spinel pyroxene assemblages in cais and aoas appear to be replaced by anorthite forsterite grains in several aoas are replaced by low ca pyroxene none of the cais or aoas show evidence for fe alkali metasomatic or aqueous alteration the mineralogy textures and bulk chemistry of most acfer 094 refractory inclusions are consistent with their origin by gas solid condensation and may reflect continuous interaction with sio and mg of the cooling nebula gas it appears that only a few cais experienced subsequent melting the al rich chondrules arcs 10 wt bulk al2o3 consist of forsteritic olivine and low ca pyroxene phenocrysts pigeonite augite anorthitic plagioclase spinel feni metal and crystalline mesostasis composed of plagioclase augite and a silica phase most arcs are spherical and mineralogically uniform but some are irregular in shape and heterogeneous in mineralogy with distinct ferromagnesian and aluminous domains the ferromagnesian domains tend to form chondrule mantles and are dominated by low ca pyroxene and forsteritic olivine anorthitic mesostasis and fe ni metal nodules the aluminous domains are dominated by anorthite high ca pyroxene and spinel occasionally with inclusions of perovskite have no or little feni metal and tend to form cores of the heterogeneous chondrules the cores are enriched in bulk ca and al and apparently formed from melting of cai like precursor material that did not mix completely with adjacent ferromagnesian melt the inferred presence of cai like material among precursors for al rich chondrules is in apparent conflict with lack of evidence for melting of cais that occur outside chondrules suggesting that these cais were largely absent from chondrule forming region s at the time of chondrule formation this may imply that there are several populations of cais in acfer 094 and that mixing of normal cais that occur outside chondrules and chondrules that accreted into the acfer 094 parent asteroid took place after chondrule formation alternatively there may have been an overlap in the cai and chondrule forming regions where the least refractory cais were mixed with fe mg chondrule precursors this hypothesis is difficult to reconcile with the lack of evidence of melting of aoas which represent aggregates of the least refractory cais and forsterite grains

characterisation of pore water in crystalline rocks abstract the mass of pore water present in the rock matrix of a crystalline rock mass is significant and its influence on fracture groundwater and future deep repositories needs to be understood yet the rock matrix has a hydraulic transmissivity generally well below 10 10 m 2 s 1 inhibiting sampling of pore water by conventional sampling techniques various innovative techniques for the chemical and isotopic characterisation of pore water in crystalline rocks are applied and evaluated direct sampling of pore water was facilitated by collecting seepage water in a specially designed borehole located at a depth of 420 m in the aspo underground research laboratory aspo hrl sweden over a period of 7 5 a during the entire time span seepage waters collected from different sampling sections showed constant but individual chemical and isotopic compositions compositional differences compared to nearby fracture groundwaters indicate that the collected waters originated from the low permeability rock mass without mutual influence via more conductive microfractures within the metre scale they are interpreted as representing pore water in a transient state of diffusive interaction with different types of old palaeowaters which have periodically characterised the fracture network at the aspo hrl over geological times thousands to hundreds of thousands of years pore water compositions derived by indirect methods out diffusion and diffusive isotope equilibration experiments from originally saturated drillcore samples collected at the laxemar and forsmark sites sweden can be interpreted within a wider palaeohydrogeological framework the chemical and isotope compositions of the pore water show distinct trends related to rock type and with depth becoming more saline at greater depth at both sites concentration gradients established between pore water and fracture groundwater commonly coincide with higher fracture frequency and transmissivity in the host rocks differences developed in the attainment of near steady state conditions between pore water and fracture water from laxemar and forsmark support a different hydrogeological and therefore hydrogeochemical evolution at least during holocene times the observed compositional differences between pore water and fracture groundwater support diffusion dominated solute transport in the low permeable rock masses which is consistent with measured and experimentally derived hydraulic properties from the present investigations it can be concluded that in such rock masses the diffusion accessible porosity extends over significant distances of at least metres to tens of metres

chemical compositions of refractory inclusions in the murchison c2 chondrite abstract samples from ten refractory inclusions in murchison some of which are splits of inclusions whose mineralogical and petrographic characteristics are known have been analysed for thirty six elements by neutron activation six inclusions have group ii or group iii patterns or variants of such patterns two inclusions bb 5 and much 1 have large negative yb anomalies unaccompanied by correspondingly large negative eu anomalies it is possible that the latter condensed originally with group iii patterns and preferentially took up eu in later exchange processes under reducing conditions one inclusion sh 2 has heavy ree enrichment factors that increase with the refractoriness of the ree indicating the presence of an extremely high temperature or ultrarefractory ree condensate but it also has a heavy ree light ree ratio that indicates mixing of that component with a lower temperature ree condensate the frequency of highly fractionated ree patterns and absence of group i patterns suggest that refractory inclusions in murchison stopped equilibrating with the nebular gas at higher temperatures than most allende coarse grained inclusions the lower ir os and ru re ratios of some murchison inclusions compared to those of allende coarse grained inclusions indicate that condensate alloys that contributed noble metals to the former also stopped equilibrating with the nebular gas at higher temperatures than those that contributed noble metals to the latter murchison inclusions tend to be lower in non refractory elements than allende coarse grained inclusions suggesting that on average the former underwent less severe secondary alteration than the latter

high cesium concentrations in groundwater in the upper 1 2 km of fractured crystalline rock influence of groundwater origin and secondary minerals abstract dissolved and solid phase cesium cs was studied in the upper 1 2 km of a coastal granitoid fracture network on the baltic shield aspo hard rock laboratory and laxemar area se sweden there unusually high cs concentrations up to 5 6 g l 1 occur in the low temperature 1 median laxemar 3 7 g l 1 and groundwater with marine origin aspo hrl 4 2 g l 1 overall lower but variable cs concentrations were found in other types of groundwater the similar concentrations of cs in the saline groundwater which had a residence time in the order of millions of years and in the marine groundwater which had residence times in the order of years shows that duration of water rock interactions is not the single and primary control of dissolved cs in these systems the high cs concentrations in the saline groundwater is ascribed to long term weathering of minerals primarily cs enriched fracture coatings dominated by illite and mixed layer clays and possibly wall rock micaceous minerals the high cs concentrations in the groundwater of marine origin are in contrast explained by relatively fast cation exchange reactions as indicated by the field data and predicted by 1d solute transport modeling alkali cations with low energy hydration carried by intruding marine water are capable of nh 4 in particular and k to some extent replacing cs on frayed edge fes sites on illite in the fracture coatings the result is a rapid and persistent at least in the order of decades buildup of dissolved cs concentrations in fractures where marine water flows downward the identification of high cs concentrations in young groundwater of marine origin and the predicted capacity of nh 4 to displace cs from fracture solids are of particular relevance in the disposal of radioactive nuclear waste deep underground in crystalline rock

mineralogy and petrography of amoeboid olivine aggregates from the reduced cv3 chondrites efremovka leoville and vigarano products of nebular condensation accretion and annealing amoeboid olivine aggregates aoas from the reduced cv chondrites efremovka leoville and vigarano are irregularly shaped objects up to 5 mm in size composed of forsteritic olivine fa 50 melting we infer that aoas are aggregates of high temperature nebular condensates which formed in cai forming regions and that they were absent from chondrule forming regions at the time of chondrule formation the absence of low ca pyroxene and depletion in moderately volatile elements mn cr na k suggest that aoas were either removed from cai forming regions prior to condensation of these elements and low ca pyroxene or gas solid condensation of low ca pyroxene was kinetically inhibited

fun with panurge high mass resolution ion microprobe measurements of mg in allende inclusions the performance characteristics of panurge a modified cameca ims3f ion microprobe have been studied at a mass resolving power of 5000 for the purpose of determining isotopic ratios at a precision level approaching that of counting statistics using beam switching the techniques used for this type of measurement are described using this approach the isotopic composition of mg and si and the atomic ratio of al mg in minerals from the allende inclusion wa and the allende fun inclusion cl have been measured with the ion microprobe at high mass resolving power enrichments in 26 mg of up to 260 have been found mg and al mg measurements on cogenetic spinel inclusions and host plagioclase crystals yield mg al isochrons in excellent agreement with precise mineral isochrons determined by thermal emission mass spectrometry the measurements confirm the presence of substantial excess 26 mg in wa 26 mg 27 al 5 x 10 5 and its near absence in cl 26 mg 27 al 4 x 10 6 in wa plagioclase data for which 27 al 24 mg 300 to 1000 define a linear array with 26 mg 27 al 3 x 10 5 and with initial 26 mg 24 mg composition 30 greater than in high mg phases this suggests a metamorphic reequilibration of mg in allende plagioclase at least 0 6 my after wa formation there were no variations in detected 26 mg 27 al in wa plagioclase associated with concentration of 26 mg into isolated clusters we have confirmed by ion probe measurements that the mg composition in allende cl is highly fractionated and is uniform among pyroxene melilite plagioclase spinel crystals and spinel included in melilite and plagioclase crystals likewise the si composition is mass fractionated and is the same in pyroxene melilite and plagioclase

partitioning of ca and al between forsterite and silicate melt in dynamic systems with implications for the origin of ca al rich forsterites in primitive meteorites we report the results of dynamic crystallization experiments that were specifically designed to study the dependence of ca and al partitioning between forsterite and melt in rapidly cooling ca and al rich melts the partitioning of ca between olivine and silicate melt is found to be independent of the cooling rate within the range of 1 5 to 1000 c hr and at cao contents of up to 25 wt within analytical uncertainty our data plot on the equilibrium partitioning curve obtained by libourel 1999 the partitioning behavior of al at high cooling rates is more complex aluminum is much more heterogenously distributed in the olivine and the co existing melt than ca but no systematic trend of al partition coefficient with cooling rate is observed we apply the results of the experiments to the formation of meteoritic forsterites with relatively high contents of ca and al although these forsterites are found frequently inside chondrules the ca contents of their host chondrules are far too low to crystallize these high ca forsterites this is also true for very rapid cooling of chondrule melts the parental melt of these forsterites requires cao contents above 20 wt

petrology and origin of amoeboid olivine aggregates in cr chondrites amoeboid olivine aggregates aoas are irregularly shaped fine grained aggregates of olivine and ca al rich minerals and are important primitive components of cr chondrites the aoas in cr chondrites contain feni metal and some aoas contain mn rich forsterite with up to 0 7 mno and mn fe ratios greater than one additionally aoas in the cr chondrites do not contain secondary phases nepheline and fayalitic olivine that are found in aoas in some cv chondrites the aoas in cr chondrites record a complex petrogenetic history that included nebular gas solid condensation reaction of minerals with the nebular gas small degrees of melting and sintering of the assemblage a condensation origin for the mn rich forsterite is proposed the mn rich forsterite found in idps unequilibrated ordinary chondrite matrix and aoas in cr chondrites may have had a similar origin a type a calcium aluminum rich inclusion cai with an aoa attached to its wark lovering rim is also described this discovery reveals a temporal relationship between aoas and type a inclusions additionally a thin layer of forsterite is present as part of the wark lovering rim revealing the crystallization of olivine at the end stages of the wark lovering rim formation the ca al rich nodules in the aoas may be petrogenetically related to the ca al rich minerals in wark lovering rims on type a cais aoas are chondrite components that condensed during the final stage of wark lovering rim formation but in general were temporally spatially or kinetically isolated from reacting with the nebula vapor during condensation of the lower temperature minerals that were commonly present as chondrule precursors

oxygen isotopes in crystalline silicates of comet wild 2 a comparison of oxygen isotope systematics between wild 2 particles and chondritic materials abstract oxygen three isotope ratios of nine crystalline silicate particles from comet wild 2 were measured to investigate oxygen isotope systematics of cometary materials we are able to analyze particles as small as 4 m using an ion microprobe with a 1 2 m beam by locating the analysis spots with an accuracy of 0 4 m three particles of mn rich forsterite known as low iron manganese enriched lime olivine showed extremely 16 o rich signatures 18 o 17 o 50 similar to refractory inclusions in chondrites the three mn rich forsterite particles may have formed by condensation from an 16 o rich solar nebula gas other particles consist of olivine and or pyroxene with a wide range of mg molar mgo feo mgo from 60 to 96 their oxygen isotope ratios plot nearly along the carbonaceous chondrite anhydrous mineral ccam and young and russell lines with 17 o 17 o 0 52 18 o values of 3 0 to 2 5 these data are similar to the range observed from previous analyses of wild 2 crystalline silicates and those of chondrules in carbonaceous chondrites six particles extracted from stardust track 77 show diverse chemical compositions and isotope ratios two mn rich forsterites feo poor pigeonite and three feo rich olivines with a wide range of 17 o values from 24 to 1 6 these results confirmed that the original projectile that formed track 77 was an aggregate 6 m of silicate particles that formed in various environments the 17 o values of ferromagnesian wild 2 particles including data from previous studies increase from 23 to 2 5 with decreasing mg 17 o values of mn rich forsterite particles mg 98 99 8 cluster at 23 those of feo poor particles mg 95 97 cluster at 2 and those of feo rich particles mg 90 scatter mainly from 1 5 to 2 5 compared to chondrules in primitive chondrites the systematic trend between mg and 17 o among the wild 2 particles is most similar to that reported for cr chondrite chondrules we argue that cr chondrites and some cometary materials share multiple common chemical and isotope characteristics we suggest that many of the crystalline silicate particles formed in the outer regions of the asteroid belt or regions that share the common properties and were transported to comet forming regions and accreted into comet wild 2

diffusion kinetics of cr in olivine and 53mn 53cr thermochronology of early solar system objects we have determined the diffusion coefficient of cr in olivine as function of temperature oxygen fugacity fo2 and crystallographic orientation and used these data to develop a quantitative understanding of the resetting of the short lived 53 mn 53 cr decay system in olivine during cooling within meteorite parent body the diffusion of cr in olivine was found to be anisotropic and effectively indepen dent of fo2 between wustite iron buffer and two orders of magnitude above this buffer the diffusion data were used to calculate the spatially averaged mean closure temperature of the 53 mn 53 cr decay system in olivine as function of the initial temperature cooling rate and grain size and also the closure age profile of this system in olivine single crystal as function of radial distance and a dimensionless parameter that incorporates the effects of various parameters that affect the closure age we also present a thermochronolgic formulation that permits retrieval of cooling rates from the extent of resetting of the bulk 53 mn 53 cr closure age of olivine during cooling this method was applied to determine the cooling rate of the pallasite omolon which showed 53 mn 53 cr bulk age of olivine that is 10 myr younger than the age of the solar system the calculated cooling rate which is 20 40 c myr at 985 1000 c is in good agreement with the metallographic cooling rate at 500 c when the two results are considered in terms of a cooling model in which the reciprocal temperature increases linearly with time the inferred cooling rate of omolon which seems to be a sample from the core mantle boun dary yields a burial depth of 30 km in a parent body of at least 100 km radius

numerical modeling of the transient hydrogeological response produced by tunnel construction in fractured bedrocks abstract groundwater inflows into tunnels constructed in fractured bedrocks not only constitute an important factor controlling the rate of advancement in driving the tunnel but may pose potential hazards drawdowns caused by tunnel construction may also induce geotechnical and environmental impacts here we present a numerical methodology for the dynamic simulation of the hydrogeological transient conditions induced by the tunnel front advance the methodology is based on the use of a cauchy boundary condition at the points lying along the tunnel according to which water discharge q is computed as the product of a leakage coefficient and the head difference h h where h is the prescribed head at the tunnel wall and h is the hydraulic head in the fractured rock in the close vicinity of the tunnel at a given position of the tunnel is zero until the tunnel reaches such position when it is assigned a positive value the use of step wise time functions for allows an efficient and accurate simulation of the transient hydrogeological conditions at and around the tunnel during the excavation process the methodology has been implemented in tranmef 3 a finite element computer code for groundwater flow in 3d fractured media developed at the university of a coruna spain and has been used to simulate the impact of a tunnel on the groundwater system at the aspo island sweden this tunnel was constructed to access an underground laboratory for research on radioactive waste disposal the large amount of available data at this site provides a unique opportunity to test the performance of the numerical model and the proposed methodology for tunnel advance with just minor calibration the numerical model is able to reproduce accurately the measurements of inflows into the tunnel at several reaches and hydraulic heads at surface drilled boreholes these results obtained at the aspo site lead us to conclude that accurate predictions of the transient hydrogeological responses induced by tunneling works in fractured bedrocks can be achieved provided that a sound hydrogeological characterization of large scale fracture zones is available

diverse fractionation patterns of rare earth elements in deep fracture groundwater in the baltic shield progress from utilisation of diffusive gradients in thin films dgt at the aspo hard rock laboratory abstract rare earth elements rees were studied in groundwater in fractures at depths between 144 m and 450 m in proterozoic granitoids on the baltic shield at a coastal site in south eastern sweden aspo hard rock laboratory a specially designed device was used to sample the groundwater under in situ high pressure and low redox conditions the rees were measured via both diffusive gradients in thin films dgt samplers after approximately three week deployment times and after conventional filtration 0 45 m membrane filters the concentrations of reedgt were lower than the ree0 45 m concentrations in all 14 studied groundwaters this is explained by development of a diffuse boundary layer dbl in the solution at the dgts caused by the low flow and in some of the groundwaters additionally by the presence of organically complexed ree that diffuse slowly in the diffusive gel of the dgt among the 14 studied groundwaters there was a huge range in reedgt fractionation patterns ranging from enrichment to a nearly three order of magnitude depletion of the heavy rees hrees despite a relatively homogenous bedrock granitoids the hree enrichment is explained by preservation of the fractionation signature as hree enriched sea water intruded and flowed through the fractures supported by the high proportion of modelled ree fulvic acid complexes in these waters the strong hree depletion which occurred in saline groundwater was ascribed to an advanced ree equilibrium between the groundwater and primary and or secondary minerals and the pore water in the bedrock yet other groundwaters had flat or moderately hree depleted patterns which in some cases may have been caused by mixing of small portions of surficial waters with saline groundwater

petrographic and oxygen isotopic study of refractory forsterites from r chondrite dar al gani 013 r3 5 6 unequilibrated ordinary and carbonaceous chondrites we have conducted petrographic chemical and in situ oxygen isotopic studies of refractory forsterites from unequilibrated ordinary and carbonaceous chondrites as well as an unequilibrated r chondrite refractory forsterites occur in all types of unequilibrated chondrites and all have very similar chemical composition with low feo and high refractory lithophile element rle contents refractory forsterites are typically enriched in 16o relative to normal olivine independent of the bulk o isotope ratios of the parent meteorites analyses of refractory forsterites spread along a 17o mixing line with 17o ranging from 2 to 10 due to similarities in oxygen isotopes and chemical compositions we conclude that refractory forsterites of various types of chondrites come from a single common reservoir implications of this hypothesis for the chemical and o isotope evolution of silicates in the early solar nebular are discussed

a review and comparison of fracture mineral investigations and their application to radioactive waste disposal abstract a compilation and comparison of fracture mineral studies from the canadian and fennoscandian shields and the french massif central shows many similarities indicating larger external control over fracture mineral deposition with different rock types exerting local controls the sites investigated represent a wide range of geological settings and host rock types ranging from felsic intrusive and extrusives to ultramafic intrusives and volcanics that span an age range from 2 5 to 0 36 ga typical fracture minerals found at canadian shield sites include calcite quartz chlorite and clays and these do not appear to be dependant on age erosional depth or geological environment the fennoscandian shield has a much larger variety of fracture filling minerals with epidote zeolites prehnite fluorite pyrrhotite fe oxides serpentine graphite magnesite and barite in addition to the minerals typically found at canadian shield sites the major control on fracture mineral type is most likely variations in rock type and fluid chemistry and temperature the c and o isotopic range of calcite is very similar among sites late stage hydrothermal calcite with strongly depleted 18o values is common at many sites all of the sites have calcite with 18o isotopic values in the range of 5 to 20 pdb indicative of formation from meteoric water or basinal brines that have undergone varying degrees of water rock interaction one canadian and a few swedish sites have calcite in the shallower portion of the rock that shows isotopic evidence of dissolution and re precipitation in equilibrium with the present day waters there are some striking similarities in fluid inclusion data among sites most sites have an elevated temperature 100 300 c low salinity group of fluid inclusions within the nacl h2o system and a lower temperature 50 150 c higher salinity group of fluid inclusions within the nacl cacl2 h2o system fluid inclusion density plots show some evidence of simple cooling but most sites show two or more fluids were responsible for calcite formation the origin of most of these fluids was magmatic hydrothermal or meteoric water that had undergone varying degrees of water rock interaction but basinal brines and seawater were also possible sources several techniques and methods have been used to further characterize calcites strontium isotopes and rare earth elements can be useful to recognize different families of calcite uranium th dating has found many old calcites beyond the useful range of the technique but also some relatively young calcites that may be related to interglacial periods where fluid inclusion data exists formation temperatures were not consistent with a glacial water origin crush and leach experiments with ion and gas chromatography and thermal ion mass spectrometry have characterized inclusion fluids but special care must be used to ensure only one generation is sampled at a time cathodoluminescence and scanning electron microscopy with energy dispersive spectrometry has been useful in identifying multiple fluid generations within single calcite samples laser ablation and raman spectrometry are additional techniques that are useful in determining individual fluid inclusion chemistry and isotopes

sorbing tracer experiments in a crystalline rock fracture at aspo sweden 1 experimental setup and microscale characterization of retention properties 1 mineralogical and retardation properties of rock materials responsible for water rock interaction in in situ migration experiments with sorbing radioactive tracers were studied in laboratory experiments the porosity was studied by water saturation measurements and the pmma method was used for detailed porosity characterization of heterogeneity distributions and porosity profiles toward the fracture surface mylonite and altered diorite sampled in the rim zone of the fracture and representative bulk rock types were investigated by batch sorption measurements with crushed materials and through diffusion and in diffusion experiments in intact rock pieces autoradiography was used for visualization of in diffusion profiles of sorbing tracers the use of detailed porosity information and quantitative data on heterogeneity in porosity is shown to significantly improve the interpretation and evaluation of laboratory scale diffusion experiments we show through the combined approach of detailed porosity characterization and laboratory sorption and diffusion investigations that we can distinguish retention properties of bulk rock and altered rock and provide qualitative and quantitative data of heterogeneous rock properties that expand the possibility for including relevant processes in the interpretation of the results of in situ tracer tests

fe ni metal in primitive chondrites indicators of classification and metamorphic conditions for ordinary and co chondrites we report the results of our petrological and mineralogical study of fe ni metal in type 3 ordinary and co chondrites and the ungrouped carbonaceous chondrite acfer 094 fe ni metal in ordinary and co chondrites occurs in chondrule interiors on chondrule surfaces and as isolated grains in the matrix isolated ni rich metal in chondrites of petrologic type lower than type 3 10 is enriched in co relative to the kamacite in chondrules however ni rich metal in type 3 15 3 9 chondrites always contains less co than does kamacite fe ni metal grains in chondrules in semarkona typically show plessitic intergrowths consisting of submicrometer kamacite and ni rich regions metal in other type 3 chondrites is composed of fine to coarse grained aggregates of kamacite and ni rich metal resulting from metamorphism in the parent body we found that the number density of ni rich grains in metal number of ni rich grains per unit area of metal in chondrules systematically decreases with increasing petrologic type thus fe ni metal is a highly sensitive recorder of metamorphism in ordinary and carbonaceous chondrites and can be used to distinguish petrologic type and identify the least thermally metamorphosed chondrites among the known ordinary and co chondrites semarkona is the most primitive the range of metamorphic temperatures were similar for type 3 ordinary and co chondrites despite them having different parent bodies most fe ni metal in acfer 094 is martensite and it preserves primary features the degree of metamorphism is lower in acfer 094 a true type 3 00 chondrite than in semarkona which should be reclassified as type 3 01

origin and residence time of salinity in the aspo groundwater system abstract the origin of salinity within the aspo groundwater system is investigated by combining interpretations of conservative dissolved ions and of stable isotope ratios in water the interpretation concludes that the groundwater salinity results from a mixing between baltic sea water intrusion and a deep seated saline groundwater of marine origin this conclusion supports the geochemical model developed for the aspo site the residence time of the deep salinity is assessed by comparing the 36 cl content of dissolved salt at different depths and the secular equilibrium value of the host rock the 36 cl of deepest levels corresponding to the highest salinity is in equilibrium with rock suggesting a penetration of the deep salinity into the host rock more than 1 5 ma ago

correlation between dissolved 4he concentration and 36cl in groundwater at aspo sweden abstract tunnel excavation at aspo island sweden has caused severe groundwater disturbance gradually extending deeper into the tunnel as present day baltic seawater intrudes through fractures connecting to the surface however the paleo hydrogeochemical conditions have remained in the deep highly saline waters that have avoided mixing a correlation has been observed between dissolved 4he concentration and cl ion concentration measured every two years from 1995 to 2001 at aspo groundwater mixing conditions can be examined by the correlations between 1 cl 36cl cl and 3h concentrations subsurface production is responsible for the majority of the 36cl and excess dissolved 4he of interstitial groundwater in fractures the secular equilibrium ratio of 36cl cl in rock was theoretically estimated to be 5 05 0 82 10 14 based on the neutron flux intensity a value comparable to the measured 36cl cl ratio in rock and groundwater the degassing crustal 4he flux was estimated to be 2 9 10 8 1 3 10 6 ccstp cm2a using the hto diffusion coefficient for the aspo diorite the 4he accumulation rate ranges from 6 8 10 10 for the in situ accumulation rate to 7 0 10 9 ccstp gwater a considering both 4he in situ production and the degassing flux assuming 4he is accumulated constantly in groundwater by comparing the subsurface 36cl increase with 4he concentrations in groundwater the 4he accumulation rate was determined from data for groundwater arriving at the secular equilibrium of 36cl cl the 4he accumulation rate was found to be 1 83 0 72 10 8 ccstp gwater a without determining the magnitude of degassing 4he flux

crystal chemical effects on the partitioning of trace elements between mineral and melt an experimental study of melilite with applications to refractory inclusions from carbonaceous chondrites the partitioning behavior of the trace elements be sc ba la ce and tm between melilite and liquid has been determined using stepwise integration of a rayleigh fractionation equation for ion microprobe analyses of synthetic zoned melilite crystals distribution coefficients between melilite and liquid d mel l i were determined over the entire range of melilite spinel crystallization for one bulk composition corresponding to that of an average type b inclusion from the allende c3v carbonaceous chondrite beryllium is incompatible in gehlenitic meliliters e g d mel l b e 0 5 for x ak 0 3 but compatible in akermanitic melilites e g d mel l b e 1 9 for x ak 0 75 barium d mel l b a 0 04 0 05 sc d mel l s c 0 01 0 02 la d mel l l 0 07 0 29 ce d mel l c e 0 05 0 21 and tm d mel l t m 0 03 0 14 are all incompatible in melilites in the range ak25 ak75 variations in d mel l i as a function of x ak are explicable in terms of a simple thermodynamic treatment of trace element partitioning based on crystal chemical considerations characteristic trace element zoning patterns are predicted for early crystallizing melilite from meliliterich type b inclusions for example concentrations of the rees in melilite should continually decrease with increasing degrees of crystallization opposite the behavior normally expected of an incompatible element concentrations of be should rise with increasing degrees of crystallization even when the element is compatible again opposite the behavior normally expected of compatible elements in general zoning patterns of trace elements in melilite from type b inclusions are consistent with those predicted for fractional crystallization from a melt in a closed system trace element zoning patterns in meteoritic melilite crystals constrain the origin and thermal histories of ca al rich inclusions from carbonaceous chondrites

drainage beneath ice sheets groundwater channel coupling and the origin of esker systems from former ice sheets abstract the nature of the drainage system beneath ice sheets is crucial to their dynamic behaviour but remains problematic an experimentally based theory of coupling between groundwater and major channel systems is applied to the esker systems in the area occupied the last ice sheet in europe which we regard as a fossil imprint of major longitudinal drainage channels we conclude that the large scale distribution and spacing of major eskers is consistent with the theory of groundwater control in which esker spacing is partly controlled by the transmissivity of the bed it is concluded that esker patterns reflect the large scale organisation of the subglacial drainage pattern in which channel development is coupled to groundwater flow and to the ice sheet s dynamic regime the theory is then used to deduce basal meltwater recharge rates and their spatial variability from esker spacing in an area in which the ice sheet was actively streaming during its final retreat patterns of palaeo groundwater flow and head distribution and the seasonally varying magnitude of discharge from stream tunnels at the retreating ice sheet margin major channel esker systems appear to have been stable at least over several hundred of years during the retreat of the ice sheet although major dynamic events are demonstrably associated with major shifts in the hydraulic regime modelling suggests that glaciation can stimulate deep groundwater circulation cells that are spatially linked to channel locations with groundwater flow predominantly transverse to ice flow that the circulation pattern has the potential to create large scale anomalies in groundwater chemistry and that the spacing of channels will change through the glacial cycle influencing water pressures in stream tunnels subglacial hydraulic gradients and effective pressure if the latter is reduced sufficiently it could trigger enhanced bed deformation thus coupling drainage to ice sheet movement it suggests the possibility of distinctive phases of sediment deformation and drumlin mobilisation during a glacial cycle

origin of low ca pyroxene in amoeboid olivine aggregates evidence from oxygen isotopic compositions amoeboid olivine aggregates aoas in primitive carbonaceous chondrites consist of forsterite fa 50 objects is texturally and mineralogically intermediate between aoas and al rich chondrules it consists of euhedral forsterite grains pigeonite augite anorthitic mesostasis abundant anhedral spinel grains and minor fe ni metal it is surrounded by a coarse grained igneous rim largely composed of low ca pyroxene with abundant fe ni metal sulfide nodules the mineralogical observations suggest that only spinel grains in this igneous object were not melted the spinel is 16o rich 17o 22 whereas the neighboring plagioclase mesostasis is 16o depleted 17o 11 we conclude that aoas are aggregates of solar nebular condensates forsterite fe ni metal and cais composed of al diopside anorthite spinel and melilite formed in an 16o rich gaseous reservoir probably cai forming region s solid or incipiently melted forsterite in some aoas reacted with gaseous sio in the same nebular region to form low ca pyroxene some other aoas appear to have accreted 16o poor pyroxene normative dust and experienced varying degrees of melting most likely in chondrule forming region s the most extensively melted aoas experienced oxygen isotope exchange with 16o poor nebular gas and may have been transformed into chondrules the original 16o rich signature of the precursor materials of such chondrules is preserved only in incompletely melted grains

calcium aluminum rich inclusions and amoeboid olivine aggregates from the cr carbonaceous chondrites calcium aluminum rich refractory inclusions cais in cr chondrites are rare 1 vol fairly small 500 m and irregularly shaped and most of them are fragmented based on the mineralogy and petrography they can be divided into grossite hibonite rich melilite rich and pyroxene anorthite rich cais other types of refractory objects include fine grained spinel melilite pyroxene aggregates and amoeboid olivine aggregates aoas some of the pyroxene anorthite rich cais have igneous textures and most melilite rich cais share similarities to both the fluffy and compact type a cais found in cv chondrites one major difference between these cais and those in cv cm and co chondrites is that secondary mineral phases are rare in situ ion microprobe analyses of oxygen isotopic compositions of 27 cais and aoas from seven cr chondrites demonstrate that most of the cais are 16o rich 17o of hibonite melilite spinel pyroxene and anorthite 22 and isotopically homogeneous within 3 4 likewise forsterite spinel anorthite and pyroxene in aoas have nearly identical 16o rich compositions 24 17o 20 deg in contrast objects which show petrographic evidence for extensive melting are not as 16o rich 17o less than 18 o secondary alteration minerals replacing 16o rich melilite in melilite rich cais plot along the terrestrial fractionation line most cr cais and aoas are mineralogically pristine objects that largely escaped thermal metamorphism and secondary alteration processes which is reflected in their relatively homogeneous 16o rich compositions it is likely that these objects or their precursors condensed in an 16o rich gaseous reservoir in the solar nebula in contrast several igneous cais are not very enriched in 16o probably as a result of their having melted in the presence of a relatively 16o poor nebular gas if the precursors of these cais were as 16o rich as other cr cais this implies either temporal excursions in the isotopic composition of the gas in the cai forming regions and or radial transport of some cai precursors into an 16o poor gas the absence of oxygen isotope heterogeneity in the primary minerals of melilite rich cais containing alteration products suggests that mineralogical alteration in cr chondrites did not affect oxygen isotopic compositions of their cais

the onset of metamorphism in ordinary and carbonaceous chondrites ordinary and carbonaceous chondrites of the lowest petrologic types were surveyed by xray mapping techniques a variety of metamorphic effects were noted and subjected to detailed analysis using electron microprobe scanning electron microscopy sem transmission electron microscopy tem and cathodoluminescence cl methods the distribution of cr in feo rich olivine systematically changes as metamorphism increases between type 3 0 and type 3 2 igneous zoning patterns are replaced by complex ones and cr rich coatings develop on all grains cr distributions in olivine are controlled by the exsolution of a cr rich phase probably chromite cr in olivine may have been partly present as tetrahedrally coordinated cr3 separation of chromite is nearly complete by petrologic type 3 2 the abundance of chondrules showing an inhomogeneous distribution of alkalis in mesostasis also increases with petrologic type tem shows this to be the result of crystallization of albite residual glass compositions systematically change during metamorphism becoming increasingly rich in k glass in type i chondrules also gains alkalis during metamorphism both types of chondrules were open to an exchange of alkalis with opaque matrix and other chondrules the matrix in the least metamorphosed chondrites is rich in s and na the s is lost from the matrix at the earliest stages of metamorphism due to coalescence of minute grains progressive heating also results in the loss of sulfides from chondrule rims and increases sulfide abundances in coarse matrix assemblages as well as inside chondrules alkalis initially leave the matrix and enter chondrules during early metamorphism feldspar subsequently nucleates in the matrix and na re enters from chondrules these metamorphic trends can be used to refine classification schemes for chondrites cr distributions in olivine are a highly effective tool for assigning petrologic types to the most primitive meteorites and can be used to subdivide types 3 0 and 3 1 into types 3 00 through 3 15 on this basis the most primitive ordinary chondrite known is semarkona although even this meteorite has experienced a small amount of metamorphism allan hills alh a77307 is the least metamorphosed co chondrite and shares many properties with the ungrouped carbonaceous chondrite acfer 094 analytical problems are significant for glasses in type ii chondrules as na is easily lost during microprobe analysis as a result existing schemes for chondrule classification that are based on the alkali content of glasses need to be revised

shear instabilities in the longshore current a comparison of observation and theory abstract low frequency 0 01 hz oscillations in the surf zone longshore current with wavelengths too small 300 m to be surface gravity waves were observed during the 1986 superduck experiment at duck north carolina the observations suggest that these oscillations are dynamically linked to the mean longshore current in the surf zone leading bowen and holman to propose that the observed oscillations are manifestations of a shear instability in the longshore current in this paper field data from both the superduck experiment a barred beach and the l980 nsts experiment at leadbetter beach santa barbara california a plane beach are used to compare quantitatively the model of bowen and holman which is extended to include the effects of dissipation due to bottom friction with observation observed frequency cyclic wavenumber f k spectra constructed from alongshore arrays of velocity measurements made in about 1 5 2 m of water in the trough of the bar at superduck and in about 1 m at nsts

oxygen isotopic diversity of chondrule precursors and the nebular origin of chondrules feo poor type i porphyritic chondrules formed by incomplete melting of solid dust precursors via a yet elusive mechanism two settings are generally considered for their formation i a nebular setting where primordial solids were melted e g by shock waves propagating through the gas and ii a collisional planetary setting here we report a method combining high current electron microprobe x ray mapping and quantitative measurements to determine the chemical characteristics of relict olivine grains inherited from chondrule precursors we find that these olivine crystals are ca al ti poor relative to host olivine crystals their variable 17o even in individual chondrule is inconsistent with derivation from planetary interiors as previously argued from 120 triple junctions also exhibited by the chondrules studied herein this indicates that chondrule precursors correspond to solid nebular condensates formed under changing physical conditions we propose that porphyritic chondrules formed during gas assisted melting of nebular condensates comprising relict olivine grains with varying 17o values and ca al ti rich minerals such as those observed within amoeboid olivine aggregates incomplete melting of chondrule precursors produced ca al ti rich melts cat melts allowing subsequent crystallization of ca al ti rich host olivine crystals via epitaxial growth on relict olivine grains incoming mgo and sio from the gas phase induced i the dilution of cat melts as attested by the positive al ti correlation observed in chondrule olivine crystals and ii buffering of the o isotope compositions of chondrules as recorded by the constant 17o values of host olivine grains the o isotopic compositions of host olivine grains are chondrule specific suggesting that chondrules formed in an array of environments of the protoplanetary disk with different 17o values possibly due to variable solid gas mixing ratios

field observations of shear waves in the surf zone 1 alongshore propagating meanders of the mean alongshore current in the surf zone called shear waves have periods of a few minutes and wavelengths of a few hundred meters here shear wave properties are estimated with arrays of current meters deployed for 4 months within 300 m of the shoreline of a sandy beach shear wave velocity fluctuations are approximately horizontally isotropic with root mean square values between 10 and 40 of the mean 3 hour averaged alongshore current v cross shore variations of the time averaged shear wave momentum flux are consistent with shear wave energy generation close to shore where the breaking wave driven mean alongshore current v and current shear vx are strong and with shear wave energy dissipation and transfer back to the mean flow farther offshore where v and vx are weak in case studies where v is a narrow jet near the shoreline the observed strong decay of shear wave energy levels seaward of the jet and the cross shore and alongshore structure of shear waves within the jet are similar to predictions based on the linearly unstable modes of the observed v shear wave energy levels also are high in a marginally unstable case with a strong but weakly sheared v

crystallization sequences of ca al rich inclusions from allende an experimental study the equilibrium crystallization sequence at 1 atmosphere in air of a melt corresponding in composition to the average composition of type b ca al rich inclusions from the allende meteorite is spinel 1550 c melilite 1400 c ak22 anorthite 1260 c ti al rich clinopyroxene 1230 c ti fassaite the melilite becomes increasingly akermanitic with decreasing temperature the pyroxene is similar in composition to fassaites from type b inclusions preliminary results suggest that the crystallization sequence is similar at oxygen fugacities near the iron wustite buffer the results of these experiments have been integrated with available phase equilibrium data in the system cao mgo al 2o 3 sio 2tio 2 and a phase diagram for predicting the crystallization sequences of liquids with compositions of coarse grained ca al rich inclusions has been developed available bulk compositions of coarse grained inclusions form a well defined trend in terms of major elements extending from type a and bl inclusions near the spinel melilite join to more pyroxene rich type b2 inclusions the trend deviates from the expected sequence of solid condensates from a nebular gas at p 10 3 atm if pure diopside is assumed to be the clinopyroxene that condenses the type a b1 end of the trend is similar in composition to calculated equilibrium condensates at 1202 1227 c and the trend as a whole parallels the sequence of condensates expected from diopside condensation at 1170 c the trend is consistent to first order with the condensation of solid ti rich fassaite in place of pure diopside at higher temperatures than those at which pure diopside is predicted to condense partially molten condensates may be likely in this case or if the nebular pressure is higher than 10 3 atm

nebular history of amoeboid olivine aggregates minor element ca cr and mn concentrations in amoeboid olivine aggregates aoas from primitive chondrites were measured and compared with those predicted by equilibrium condensation in the solar nebula cao concentrations in forsterite are low particularly in porous aggregates a plausible explanation appears that an equilibrium ca activity was not maintained during the olivine condensation cao and mno in forsterite are negatively correlated with cao being higher in compact aggregates this suggests that the compact aggregates formed either by a prolonged reheating of the porous aggregates or by condensation and aggregation of forsterite during a very slow cooling in the nebula

amoeboid olivine aggregates with low ca pyroxenes a genetic link between refractory inclusions and chondrules amoeboid olivine aggregates aoas in primitive unmetamorphosed and unaltered carbona ceous chondrites are uniformly 16 o enriched 17 o 20 and consist of forsterite fa2 feni metal and a refractory component individual cais and fine grained minerals interspersed with forsterite grains composed of al diopside anorthite spinel and exceptionally rare melilite a u k15 some cais in aoas have compact igneous textures melilite in aoas is replaced by a fine grained mixture of spinel al diopside and anorthite spinel is corroded by anorthite or by al diopside in 10 of 500 aoas studied in the cr cv cm co ch cb and ungrouped carbonaceous chondrites acfer 094 adelaide and lew85332 forsterite is replaced to a various degree by low ca pyroxene there are three major textural occurrences of low ca pyroxene in aoas i thin 10 m discontinuous layers around forsterite grains or along forsterite grain boundaries in aoa peripheries ii haloes and subhedral grains around feni metal nodules in aoa peripheries and iii thick up to 70 m continuous layers with abundant tiny inclusions of feni metal grains around aoas aoas with low ca pyroxene appear to have experienced melting of various degrees in the most extensively melted aoa in the cv chondrite leoville only spinel grains are relict forsterite anorthite and al diopside were melted this aoa has an igneous rim of low ca pyroxene with abundant feni metal nodules and is texturally similar to type i chondrules based on these observations and thermodynamic analysis we conclude that aoas are aggregates of relatively low temperature solar nebular condensates originated in 16 o rich gaseous reservoir s probably cai forming region s some of the cais were melted before aggregation into aoas many aoas must have also experienced melting but of a much smaller degree than chondrules before and possibly after aggregation melilite and spinel reacted with the gaseous sio and mg to form ca tschermakite caal2sio6 diopside camgsi2o6 solid solution and anorthite solid or incipiently melted olivine in some aoas reacted with gaseous sio in the cai or chondrule forming regions to form low ca pyroxene mg2sio4 sio g h2o g mg2si2o6 h2 g some low ca pyroxenes in aoas may have formed by oxidation of si bearing feni metal mg2sio4 si in feni 2h2o g mg2si2o6 2h2 g and by direct gas solid condensation mg g sio g h2o g mg2si2o6 s h2 g from fractionated mg si ratio solar nebular gas although bulk compositions of aoas are rather similar to those of type i chondrules on the projection from spinel onto the plane ca2sio4 mg2sio4 al2o3 these objects plot on different sides of the anorthite forsterite thermal divide suggesting that type i chondrules cannot be produced from aoas by an igneous fractionation formation of low ca pyroxene by reaction of aoas with gaseous sio and by melting of silica rich dust accreted around aoas moves bulk compositions of the aoas towards chondrules and provide possible mechanisms of transformation of refractory materials into chondrules or chondrule precursors the rare occurrences of low ca pyroxene in aoas may indicate that either aoas were isolated from the hot nebular gas before condensation of low ca pyroxene or that condensation of low ca pyroxene by reaction between forsterite and gaseous sio was kinetically inhibited if the latter is correct then the common occurrences of pyroxene rich type i chondrules may require either direct condensation of low ca pyroxenes or sio2 from fractionated nebular gas or condensation of gaseous sio into chondrule melts copyright 2004 elsevier ltd

oxygen and magnesium isotopic compositions of amoeboid olivine aggregates from the semarkona ll3 0 chondrite amoeboid olivine aggregates aoas in the ll3 0 semarkona chondrite have been studied by secondary ion mass spectrometry the aoas mainly consist of aggregates of olivine grains with interstitial al ti rich diopside and anorthite oxygen isotopic compositions of all phases are consistently enriched in 16o with 17 18o 50 the initial 26al 27al ratios are calculated to be 5 6 0 9 2 10 5 these values are equivalent to those of aoas and fine grained calciumaluminum rich inclusions fgis from pristine carbonaceous chondrites this suggests that aoas in ordinary chondrites formed in the same 16o rich calcium aluminum rich inclusion cai forming region of the solar nebula as aoas and fgis in carbonaceous chondrites and subsequently moved to the accretion region of the ordinary chondrite parent body in the solar nebula

amoeboid olivine aggregates aoas in the efremovka leoville and vigarano cv3 chondrites a record of condensate evolution in the solar nebula abstract amoeboid olivine aggregates aoas in the efremovka leoville and vigarano cv3 chondrites were studied using petrographic and microanalytical techniques to evaluate the origins of these inclusions and their relationships to other chondrite components our data support the idea that the inclusions formed by dust growth in the solar nebula as condensates and that they preserve a record of mineralogical and chemical evolution spinel rich nodules and ribbons in aoas often show group ii trace element patterns and formed either by fractional condensation or by condensation following partial vaporization the dominant olivine component in aoas can be explained as a condensate produced in the same way but with fractionation occurring at a lower temperature other spinel rich material in aoas appears to be a vaporization residue ca rich pyroxene anorthite patches in aoas show chemical signatures similar to those observed for spinel or melilite bearing regions but with lower refractory element and higher mg and si contents supporting the idea that the patches formed by reaction between cai like material and mg si rich gas different trace element patterns group ii and non group ii refractory are sometimes found for al rich regions ca pyroxene anorthite or melilite bearing in a given aoa suggesting that aoas agglomerated from materials that formed under different conditions and that they did not subsequently homogenize aoas appear to have originated in a system with near canonical solar composition and a low pressure gas 10 6 10 4 bar over a range of temperatures mainly 1200 1384 k under somewhat non equilibrium conditions relative to predicted equilibrium condensates most aoas show an apparent paucity of metal possibly reflecting differential density dependent sorting between olivine and metal grains during aggregate formation trace element data are consistent with a simple model involving melting and igneous fractionation of aoa like olivine to produce type i chondrule olivine but other data suggest that open system melting of chondrules occurred in a different gaseous environment than that which produced aoas

the generation of surfzone eddies in a strong alongshore current abstractthe surfzone contains energetic two dimensional horizontal eddies with length scale larger than the water depth yet the dominant eddy generation mechanism is not understood the wave resolving model funwavec is used to simulate surfzone eddies in four case examples from the sandyduck field experiment that had alongshore uniform bathymetry the funwavec model is initialized with the observed bathymetry and the incident wave field in 8 m depth and reproduces the observed cross shore structure of significant wave height and mean alongshore current within the surfzone the wave resolving funwavec modeled e f ky spectra and the bulk frequency and ky integrated rotational velocities are consistent with the observations below the sea swell band 0 05 hz demonstrating that the model can be used to diagnose surfzone eddy generation mechanisms in the mean squared perturbation vorticity budget the breaking wave vorticity forcing term is orders of magnitude larger than the shear instability gene

lime silicates in amoeboid olivine aggregates in carbonaceous chondrites indicator of nebular and asteroidal processes mno feo ratios in olivine from amoeboid olivine aggregates aoas reflect conditions of nebular condensation and can be used in concert with matrix textures to compare metamorphic conditions in carbonaceous chondrites lime low iron mn enriched olivine was identified in aoas from y 81020 co3 05 kaba cv 3 1 and in y 86009 cv3 y 86751 cv3 nwa 1152 cr cv3 but was not identified in aoas from efremovka cv3 1 3 4 or allende cv 3 6 according to thermodynamic models of nebular condensation lime olivine is stable at lower temperatures than mn poor olivine and at low oxygen fugacities dust enrichment 95 in our study whereas efremovka aoas are slightly fe rich fo 92 aoa olivines from kaba are mostly forsteritic but rare fe rich olivine precipitated from an aqueous fluid a combination of precipitation of fe rich olivine and diffusion of fe into primary olivine grains resulted in iron rich compositions fo97 59 in allende aoas variations from fine grained nonporous matrix toward higher porosity and coarser lath like matrix olivine can be divided into six stages represented by 1 y 81020 efremovka nwa 1152 2 y 86751 lithology b 3 y 86009 4 kaba 5 y 86751 lithology a 6 allende these stages are inferred to represent general degree of metamorphism although the specific roles of thermally driven grain growth and diffusion versus aqueous dissolution and precipitation remain uncertain

numerical simulation of nearshore circulation on field topography under random wave environment abstract in order to investigate surf zone hydrodynamics through two dimensional numerical simulations of nearshore circulation under random wave environment a nearshore circulation model shorecirc and a random wave model swan were combined and utilized using this combined model a numerical simulation of the october 2 1997 sandyduck field experiment was performed for this simulation field topography and an input offshore spectrum were constructed using observed data sets synchronized with the experiment the wave breaking model in swan was modified by using breaker parameters varied according to bottom slope the simulation results were compared with the experimental data which revealed a well developed longshore current as well as with results using other combinations which were shorecirc and its original monochromatic wave driver and shorecirc and the default of swan the results from the novel combined model agreed well with the experimental data the results of the present simulation also indicate that alongshore field topography influences shear fluctuation of longshore currents

model data comparisons of shear waves in the nearshore 1 observations of shear waves alongshore propagating meanders of the mean alongshore current with periods of a few minutes and alongshore wavelengths of a few hundred meters are compared with model predictions based on numerical solutions of the nonlinear shallow water equations the model after ozkan haller and kirby 1999 assumes alongshore homogeneity and temporally steady wave forcing and neglects wave current interactions eddy mixing and spatial variation of the nonlinear bottom drag coefficient although the shapes of observed and modeled shear wave velocity spectra differ and root mean square velocity fluctuations agree only to within a factor of about 3 aspects of the cross shore structure of the observed 0 5 1 0 m above the seafloor and modeled vertically integrated shear waves are qualitatively similar within the surf zone where the mean alongshore current v is strong and shear waves are energetic observed and modeled shear wave alongshore phase speeds agree and are close to both v and clin the phase speed of linearly unstable modes consistent with previous results farther offshore where v is weak and observed and modeled shear wave energy levels decay rapidly modeled and observed c diverge from clin and are close to the weak alongshore current v the simulations suggest that the alongshore advection of eddies shed from the strong sheared flow closer to shore may contribute to the offshore decrease in shear wave phase speeds similar to the observations the modeled cross and alongshore shear wave velocity fluctuations have approximately equal magnitude and the modeled vorticity changes sign across the surf zone

overview of geological and hydrogeological conditions of the aspo hard rock laboratory site abstract the site of the underground facility the aspo hard rock laboratory was excavated at a depth of 450 m below the island of aspo and has been extensively investigated by geological hydrogeological and hydrochemical methods as part of the geoscientific research for disposal of nuclear waste in sweden the geological history of the area dates back to 1 85 ga and is dominated by granitoids belonging to the trans scandinavian igneous belt but also includes basic sheets and xenoliths and dikes of fine grained granite seven tectonic episodes giving rise to fracture mineralization are recognised the major discontinuities and fracture zones were characterised from surface investigations before the tunnel construction work started these structural features were also identified in the tunnel and are as predicted the major water conducting features sets of open fractures in the nnw nw and n s directions and the brittle fine grained granite are other important water conductors groundwater flow modelling shows that the location of aspo island has a major impact on the current distribution of groundwater salinity due to varying hydraulic boundary conditions in the late and post glacial period

modeling surf zone tracer plumes 1 waves mean currents and low frequency eddies 1 a model that accurately simulates surf zone waves mean currents and low frequency eddies is required to diagnose the mechanisms of surf zone tracer transport and dispersion in this paper a wave resolving time dependent boussinesq model is compared with waves and currents observed during five surf zone dye release experiments in a companion paper clark et al 2011 compare a coupled tracer model to the dye plume observations the boussinesq model uses observed bathymetry and incident random directionally spread waves for all five releases the model generally reproduces the observed cross shore evolution of significant wave height mean wave angle bulk directional spread mean alongshore current and the frequency dependent sea surface elevation spectra and directional moments the largest errors are near the shoreline where the bathymetry is most uncertain the model also reproduces the observed cross shore structure of rotational velocities in the infragravity 0 004 f 0 03 hz and very low frequency vlf 0 001 f 0 004 hz bands although the modeled vlf energy is 2 3 times too large similar to the observations the dominant contributions to the modeled eddy induced momentum flux are in the vlf band these eddies are elliptical near the shoreline and circular in the mid surf zone the model data agreement for sea swell waves low frequency eddies and mean currents suggests that the model is appropriate for simulating surf zone tracer transport and dispersion

baltic shield seismicity the results of a regional network the seismicity of the southern part of the baltic shield has been studied for four years by a digital regional seismic network with a station spacing of 100km some 160 earthquakes have been analysed for location focal depth seismic moment fault plane solution and static stress drop more than 90 of the earthquakes occur at depths less than 19km orientation of the horizontal stresses relaxed by the events is very consistent the principal compression is oriented in a nw se direction the geographical distributions of the events show relations to the regional geology the consistency of the stress pattern means that the type of faulting is mainly determined by the strikes of the available faults

pre quaternary sea level changes while the paramount importance of global sea level changes has been widely accepted by quaternary geologists throughout this century it is only within the last decade that such changes in the rest of the phanerozoic have received much attention there are two principal reasons for this arousal of interest first increased exploration of the stratigraphic record across the earth both on land and under the sea and significant improvement in biostratigraphic correlation have drawn attention to what appear to have been globally synchronous events second oceanographic research has demonstrated the importance of tectonically controlled changes in the cubic capacity of the ocean basins notably variations in ridge volume which provide a ready mechanism for sea level changes even at nonglacial times the adjective eustatic was first proposed for global changes of sea level by suess 1906 in his great treatise the face of the earth the corresponding noun is eustasy not eustacy as it is commonly misspelt the unconvinced reader need only think of ecstasy eustatic sea level changes can be inferred as suess recognized by a plotting the temporal spread of marine sediments over the continents and b estimating the depositional depth variations in marine stratal sequences which can be correlated across and between continents to these methods can be added seismic stratigraphy in which biostratigraphically age determined seismic sequences on the con tinental margins are analyzed in terms of cycles of coastal onlap and offiap when the results of these methods are broadly in accord confidence in a eustatic interpretation is increased but the range of confidence can vary considerably it is widely accepted that there was an exceptionally high sea

regional scale groundwater flow in a canadian shield setting a three dimensional numerical analysis of a 5734 km2 watershed situated in the canadian shield has been conducted to illustrate aspects of regional scale groundwater flow in a crystalline rock setting an essential requirement of the analysis is the preservation and accurate description of the complex topography surface water drainage network groundwater salinity distribution and permeability distributions the postglacial evolution of the groundwater flow system was investigated using the finite difference model swift iii robustness was assessed by exploring the sensitivity of groundwater flow to topography variable matrix permeability distribution models pore water salinity and the dissipation of elevated initial pore pressures that result from ice that overlaid the watershed in the last glacial period groundwater flow analyses indicate that freshwater heads in all model layers are highly correlated with the complex surface topography such that the transition from zones of groundwater recharge t

87sr 86sr of brines from the fennoscandian shield a synthesis of groundwater isotopic data from the baltic sea region high salinity ca na cl brines occur in sweden and finland the complex geological history of the fennoscandian shield is reflected by the wide range of saline waters whose chemical compositions have been explained by local water rock interaction simple evolution of relict sea water or freezing of sea water during glacial periods this study deals with the present knowledge of sr isotopes in groundwater from the fennoscandian shield to better constrain the origin of their deep saline component two different mixing trends are seen between aspo island groundwater and the baltic sea the first trend links the north sea to rivers through various dilution levels in the baltic the second trend is a simple linear relationship through aspo groundwaters agreeing with a binary mixing between a baltic end member and a highly sr concentrated fluid strontium isotope compositions are presented for precipitation in finland and sweden the baltic sea and the river waters draining the fennoscandian shield and for g

calcite fracture fillings as indicators of paleohydrology at laxemar at the aspo hard rock laboratory southern sweden isotopic compositions of c 13c o 18o and sr 87sr were determined for calcite fracture fillings in the crystalline rock penetrated by a 1 6 km drill hole at laxemar near the aspo hard rock laboratory ahrl in southern sweden these calcites precipitated from groundwater some time in the past and their 13c 18o and 87sr values reflect those of the source waters the present day groundwater system is hydrochemically stratified with highly saline water underlying more shallow brackish and fresh water the origin of this stratified system is probably related to past glaciations although the ultimate origin of the deep highly saline water is still problematical none of the calcite fracture fillings sampled below 900 m could have precipitated from any of the present day ground waters which in view of the glacial history of the region is not surprising however several shallow calcite fracture fillings are formed by precipitation from the present day groundwater coupled variations in 13c 18o and 87sr isotopes at depths in excess of 900 m suggest that these isotope systems in calcite are recording a time dependent evolution of groundwater composition

effects of wave current interaction on shear instabilities of longshore currents 1 we examine the effects of wave current interaction on the dynamics of instabilities of the surf zone longshore current we utilize coupled models for the simulation of the incident waves and the wave induced nearshore circulation the coupling between the models occurs through radiation stress gradient terms accounting for the generation of nearshore circulation and through wave current interaction terms leading to the modification of the wave field by the generated circulation field simulations are carried out with a realistic barred beach configuration and obliquely incident waves for two frictional regimes the results show that the shear instabilities of the longshore current have a significantly altered finite amplitude behavior when wave current interaction effects are included for beaches with relatively high frictional damping the primary effects are a reduction of the offshore extent of the motions and a delay of the onset of instabilities in addition the energy content of the motions within two surf zone widths is reduced the propagation speed increases and tendency to form offshore directed jets is reduced the horizontal mixing induced by the instabilities is also reduced when wavecurrent interaction is considered leading to a larger peak mean longshore current and a larger offshore current shear these effects appear to be primarily linked to a feedback mechanism whereby the incident wave field gains energy at locations of offshore directed currents for more energetic shear instability fields that occur when frictional damping is small this feedback affects the propagation speed and energy content of the instabilities near and onshore of the current peak only minimally however the offshore extent of the motions and the tendency to shed vortices offshore are still reduced a reduction in the mixing due to the instabilities is evident offshore of the current peak hence the mean longshore current profile is only affected offshore of the current peak the inclusion of wave current interaction significantly affects the shear instability signature observed in the shoreline runup for either frictional regime these results indicate that the energy content and frequency extent of the shoreline response is increased markedly due to the wavecurrent interaction process this effect appears to be related to variations in the forcing of the circulation that arise due to the refraction of the incident waves around offshore directed features of the circulation index terms 4255 oceanography general numerical modeling 4512 oceanography physical currents 4546 oceanography physical nearshore processes

a continuum representation of fracture networks part ii application to the aspo hard rock laboratory abstract a method to represent fracture networks in a continuum model is evaluated by an application to the aspo hard rock laboratory hrl the basic approach of the method is to first generate a fracture network based on data from field measurements and then represent the network as grid cell conductivities using a staggered grid arrangement it is argued that the resulting conductivity fields capture the correlation and anisotropy structures as well as the mean conductivity of the rock in a realistic way the main objective is to evaluate if the suggested method can be used in an application to a real site the objective is formulated in three questions can the method utilize available field data can the generated fields be calibrated and conditioned and are realistic distributions of pressure flow and density obtained from the application to the aspo hrl it is concluded that the hydraulic conductivity fields generated by the suggested method can utilize field data and be calibrated it is also demonstrated that realistic distributions of pressure flow and density can be simulated

amoeboid olivine aggregates from ch carbonaceous chondrites amoeboid olivine aggregates aoas in ch carbonaceous chondrites are texturally and mineralogically similar to those in other carbonaceous chondrite groups they show no evidence for alteration and thermal metamorphism in an asteroidal setting and consist of nearly pure forsterite fa 3 in wt cao 0 1 0 8 cr2o3 0 04 0 48 mno 0 5 anorthite al diopside in wt al2o3 0 7 8 1 tio2 1 fe ni metal spinel and occasionally low ca pyroxene fs1wo2 3 and calcium aluminum rich inclusions cais the cais inside aoas are composed of hibonite grossite melilite ak13 44 spinel perovskite al ti diopside in wt al2o3 up to 19 6 tio2 up to 13 9 and anorthite the ch aoas including cais within aoas have isotopically uniform 16o rich compositions average 17o 23 4 2 3 2sd and on a three isotope oxygen diagram plot along slope 1 line the only exception is a low ca pyroxene bearing aoa 1 103 that shows a range of 17o values from 24 to 13 melilite grossite and hibonite in four cais within aoas show no evidence for radiogenic 26mg excess 26mg in contrast anorthite in five out of six aoas measured has 26mg corresponding to the inferred initial 26al 27al ratio of 4 3 0 7 10 5 4 2 0 6 10 5 4 0 0 3 10 5 1 7 0 2 10 5 and 3 0 2 6 10 6 anorthite in another aoa shows no resolvable 26mg excess an upper limit on the initial 26al 27al ratio is 5 10 6 we infer that ch aoas formed by gas solid condensation and aggregation of the solar nebula condensates forsterite and fe ni metal mixed with the previously formed cais subsequently they experienced thermal annealing and possibly melting to a small degree in a 16o rich gaseous reservoir during a brief epoch of cai formation the low ca pyroxene bearing aoa 1 103 may have experienced incomplete melting and isotope exchange in an 16o poor gaseous reservoir the lack of resolvable 26mg excess in melilite grossite and hibonite in cais within aoas reflects heterogeneous distribution of 26al in the solar nebula during this epoch the observed variations of the inferred initial 26al 27al ratios in anorthite of the mineralogically pristine and uniformly 16o rich ch aoas could have recorded i admixing of 26al in the protoplanetary disk during the earliest stages of its evolution and or ii closed system mg isotope exchange between anorthite and mg rich minerals spinel forsterite and al diopside during subsequent prolonged days to weeks thermal annealing at high temperature 1100 c and slow cooling rates 0 01 k h 1 that has not affected their o isotope systematics the proposed thermal annealing may have occurred in an impact generated plume invoked for the origin of non porphyritic magnesian chondrules and fe ni metal grains in ch and cb carbonaceous chondrites about 5 myr after formation of cv cais

the origin and significance of reverse zoning in melilite from allende type b inclusions in many type b allende inclusions melilite is reversely zoned over restricted portions of each crystal textural relationships and the results of dynamic crystallization experiments suggest that the reverselyzoned intervals in these type melilites result from the co precipitation of melilite with clinopyroxene from a melt prior to the onset of anorthite precipitation when clinopyroxene begins to precipitate the al mg ratio of the melt rises causing the crystallizing melilite to become more gehlenitic an effect which is negated by crystallization of anorthite because the equilibrium crystallization sequence in these liquids is anorthite before pyroxene melilite reverse zoning can occur only when anorthite nucleation is suppressed relative to pyroxene this has been achieved in our experiments at cooling rates as low as 0 5 c hour our experiments further indicate however that reverse zoning does not form at cooling rates 50 c hour probably because the clinopyroxene becomes too al rich to drive up the al mg ratio of the liquid type inclusions with reversely zoned melilites must have cooled at rates greater than those at which anorthite begins to crystallize before clinopyroxene but 50 c hour such rates are far too slow for the type droplets to have cooled by radiation into a nebular gas but are much faster than the cooling rate of the solar nebula itself one possibility is that type b s formed in local hot regions within the nebula where their cooling rate was equal to that of their surrounding gas other possibilities are that their cooling rates reflect their movement along nebular temperature gradients or the influence of a heat source the sun or viscous drag on inclusions as they moved through the nebular gas are potential candidates for such heat sources

dynamic changes in hydrogeochemical conditions caused by tunnel excavation at the aspo hard rock laboratory hrl sweden abstract hydraulic changes caused by tunneling at the aspo hard rock laboratory hrl in sweden have been investigated over a period of 2a using different hydrochemical approaches i e noble gas content isotopic measurements and major ion concentrations the dissolved noble gases 4he and ne contents and the ratio of 3he 4he 40ar 36ar stable isotopes chemical concentrations of major ions and 36cl cl ratios were determined in groundwater samples collected in the tunnel from borehole sections isolated by inflated packers groundwater was categorized into 3 groups based on 4he and cl contents undisturbed groundwater i e prior to tunnel construction with high 4he and cl contents groundwater that has been gradually changed by mixing with baltic seawater and whose 4he and cl contents have gradually increased with increasing depth and groundwater that has been totally changed due to a rapid mixing of baltic seawater and or shallow groundwater and whose 4he and cl contents are extremely low compared with other samples collected at the same surrounding depth the oldest groundwater with a high salinity of more than 14 000 mg l 1 of cl is estimated to be more than 1 8 ma old the groundwater residence time ranges from 0 9 to 900 ka in the mixing zone groundwater in the disturbed zone where rapid mixing has occurred is hard to date reliably and its primary hydrochemical character has already been lost