unusual bulk rock compositions in eclogite facies rocks from syros and tinos cyclades greece implications for u pb zircon geochronology low temperature eclogite facies rocks from syros and tinos cyclades greece include meta ophiolitic blocks of unclear origin meta olistostrome or tectonic melange these blocks occur in a matrix of altered serpentinite and or semipelitic to tuffitic schists some samples are characterized by very high trace element concentrations for example eclogites from tinos contain up to 4950 ppm zr and up to 480 ppm y understanding of the geochemical controls on the petrogenesis of these rocks has important consequences for interpretation of geochronological results the emphasis of this study is on the behaviour of zr under eclogite facies p t conditions due to remarkably high modal amounts of zircon some samples from the meta ophiolite suite are suitable for u pb zircon chronology the geological significance of zircon ages can only be correctly interpreted by assessing whether zircon crystallized from a melt or formed during subsequent hydrothermal or metamorphic processes the results of this study lead us to conclude that infiltration of trace element enriched fluids during eclogite facies metamorphism caused local scale compositional changes textural observations document the presence of a fracture network favouring fluid infiltration under high pressure conditions such a system of microfractures might have provided infiltration paths for trace element enriched fluids during earlier stages of high pressure metamorphism in most cases subsequent recrystallization erased any evidence of the early infiltration channels but inclusion of high pressure phases in zircon provide evidence for this model suggesting metasomatic alteration in a subduction zone environment the original fluid source and the conditions e g high f environment highly saline brines under which commonly immobile elements were mobilized remain unclear it is speculated that eclogitization of closely associated metagabbros may have released zr and other trace elements the results of this contribution suggest that new zircon formed during high pressure metamorphism cretaceous u pb zircon ages are interpreted to date subduction metamorphism and not magmatic crystallization

an investigation of cathodoluminescence in albite from the a type georgeville granite nova scotia abstract cathodoluminescence cl reveals red and blue colors within single non turbid albite ab98 99 grains from the georgeville granite nova scotia a 720 nm x ray excited optical luminescence xeol peak characterizes red cl regions while a 280 nm xeol feature dominates blue cl regions synchrotron x ray fluorescence results indicate that red cl and the 720 nm xeol peak intensities relate to total fe concentrations the relationship between red cl and fe content is confirmed by electron microprobe empa and laser ablation inductively coupled mass spectrometry la icp ms the xeol technique is used to exclude the fe k edge as the cause of red cl x ray absorption spectroscopy results indicate that fe in both the red and blue cl regions is fe3 and that red cl activation may relate to the si al order of the feldspar and to the distribution of fe on tetrahedral sites the cl textures combined with empa and la icpms analyses indicate that blue cl albite ab98 regions contain higher concentrations of ca ti pb and rare earth elements and were replaced in part by a more fe rich trace element depleted albite ab99 which displays red cl complex diffraction contrasts and amorphous deposits identified in transmission electron microscope images suggest that aqueous fluids have reacted with both red and blue cl regions fluid inclusion homogenization temperatures of up to 430 c provide a lower estimate of the fluid temperature

zoisite and clinozoisite segregations in metabasites tauern window austria as evidence for high pressure fluid rock interaction high pressure zoisite and clinozoisite bearing segregations are common in garnet and albite bearing amphibolites of the palaeozoic part of the lower schieferhulle south central tauern window austria the zoisite segregations primary assemblage zo qtz cal formed during an early to pre hercynian high pressure event p 0 6 gpa t 500 550 c by hydrofracturing as a result of protolith dehydration zoisite is growth zoned from fe3 poor cores al 2 fe 9 mol to fe3 rich rims 17 mol and has high sr pb and ga contents and lree enriched ree patterns controlling the trace element budget of the segregations hercynian deformation at c 0 7 gpa 600 c kinked and cracked primary zoisite and enhanced breakdown into secondary zoisite 13 mol al 2 fe clinozoisite 40 55 mol al 2 fe albite an 20 calcite and white mica during an eoalpine high pressure event at 0 9 1 2 gpa 400 500 c the clinozoisite segregations primary assemblage czo qtz omp ttn chl cal are mm to cm wide vein like bodies cross cutting fabric elements of the host garnet amphibolite they formed during the eoalpine high pressure event at 0 9 1 2 gpa 400 500 c during alpine exhumation omphacite was pseudomorphed by amphibole albite quartz and clinozoisite oxygen isotope data suggest equilibrium between host metabasite and zoisite segregations and indicate an internal fluid source and fluid buvering by the protolith mobility of p nb and lree changed the protolith s trace element composition in the vicinity of the zoisite segregations mobilization of lree is evidenced by decreasing modal amounts of lree rich epidote and decreasing lree contents in lree rich epidote towards the segregations chang ing the ree patterns of the host metabasite from lree enriched to lree depleted tectonic discrimi nation diagrams based on the trace element content of metabasites should be applied with extreme caution

fluorapatite in carbonatite related phosphate deposits the case of the matongo carbonatite burundi the matongo carbonatite intrusive body in the neoproterozoic upper ruvubu alkaline plutonic complex urapc in burundi is overlain by an economic phosphate ore deposit that is present as breccia lenses the ore exhibits evidence of supergene enrichment but also preserves textures related to the concentration of fluorapatite in the carbonatitic system magmatic fluorapatite is abundant in the ore and commonly occurs as millimeter sized aggregates it is enriched in light rare earth elements lree which is especially apparent in the final generation of magmatic fluorapatite up to 1 32 wt lree2o3 after an episode of metasomatism fenitization which led to the formation of k feldspar and albite the fluorapatite rich rocks were partly brecciated oxygen and carbon isotope compositions obtained on the calcite forming the breccia matrix 18o 22 1 and 13c 1 5 are consistent with the involvement of a fluid resulting from the mixing of magmatic derived fluids with a metamorphic fluid originating from the country rocks in a subsequent postmagmatic event the carbonates hosting fluorapatite were dissolved leading to intense brecciation of the fluorapatite rich rocks secondary carbonate fluorapatite less enriched in lree with 0 07 0 24 wt lree2o3 but locally associated with monazite and coeval siderite constitute the matrix of these breccias siderite has 18o values between 25 4 and 27 7 and very low 13c values from 12 4 to 9 2 which are consistent with the contribution of organic derived low 13c carbon from groundwater these signatures emphasize supergene alteration finally the remaining voids were filled with a lree poor fibrous fluorapatite 0 01 wt lree2o3 forming hardened phosphorite still under supergene conditions pyrochlore and vanadiferous magnetite are other minerals accumulated in the eluvial horizons as a consequence of the supergene processes and fluorapatite accumulation the phosphate ore which contains 0 72 to 38 01 wt p2o5 is also enriched in lree lan ybn from 47 1 to 83 5 ree between 165 and 5486 ppm nb up to 656 ppm and v up to 1232 ppm in the case of phosphate exploitation at matongo ree could prove to have a subeconomic potential to be exploited as by products of phosphates

drained and undrained anisotropic elastic stiffness parameters equations that map drained to undrained elastic stiffness parameters in a cross anisotropic material are presented graphs of various anisotropic stiffness ratios are used to illustrate the important trends a new 2 d graph showing the elastic bound enables measured elastic parameters to be plotted which all lie well within it the 2 d graph enables uncoupled and incompressible materials to be shown plus materials with particular initial effective stress path slopes in an undrained triaxial test bounds more restrictive than the elastic one are also discussed and the likely ranges of various anisotropic stiffness ratios are presented in general undrained anisotropy is much less than drained that is closer to isotropic in undrained plane strain conditions vertical and horizontal moduli are found to be the same in drained plane strain conditions the ratios of the moduli are almost the same as the young s moduli

plastic deformation of an embankment on clay a simplified elastic plastic work hardening stress strain model was used to analyze the results of laboratory triaxial tests on kaolinite grundite and a lacustrine clay from toledo the necessary model parameters were determined from the test results the stress strain model was used to compute the displacements of an embankment on clay a sensitivity analysis was performed to evaluate the influence of the various model parameters on the computer displacements it was found that the preconsolidation pressure which defined the yield point and the initial horizontal stress had the largest influence most of the measured displacements fall within the range of values computed with the upper and lower limits of preconsolidation pressure the effect of plane strain variations in the elastic modulus and compressibility are comparatively unimportant keywords clay elasticity embankment plasticity settlement stress strain model triaxial tests yielding

large calcite and bulk rock volume loss in metacarbonate xenoliths from the querigut massif french pyrenees chemical mass transfer was quantified in a metacarbonate xenolith enclosed within the granodiorite of the querigut massif pyrenees france mass balance calculations suggest a strong decrease of cao sro and co2 contents up to 90 correlated with a decrease of modal calcite content as the contact is approached most other chemical elements behave immobile during metasomatism they are therefore passively enriched only a small increase of sio2 al2o3 and fe2o3 contents occurs in the immediate vicinity of the contact hence in this study skarn formation is characterized by the lack of large chemical element influx from the granitoid protolith a large decrease of the initial carbonate volume up to 86 resulted from a combination of decarbonation reactions and loss of cao and co2 the resulting volume change has potentially important consequences for the interpretation of stable isotope profiles the isotope alteration could have occured over greater distances than those observed today

coupled thermo hydro mechanical processes in the near field of a high level radioactive waste repository in clay formations the present paper provides an overview of key coupled thermo hydro mechanical thm processes in clay formations that would result from the development of a high level radioactive waste repository here in this paper clay formations include plastic clay such as the boom clay of belgium as well as more indurated clay such as the callovo oxfordian and upper toarcian of france and opalinus clay of switzerland first we briefly introduce and describe four major underground research laboratories urls that have been devoted to clay repository research over the last few decades much of the research results in this area have been gained through investigations in these urls and their supporting laboratory and modeling research activities then the basic elements in the development of a waste repository in clays are presented in terms of four distinct stages in repository development for each of these four stages key processes and outstanding issues are discussed a summary of the important areas of research needs and some general remarks then conclude this paper

volatile control of contrasting trace element distributions in peralkaline granitic and volcanic rocks anomalous enrichments of zr 500 ppm zn 100 ppm nb 25 ppm y 60 ppm th 20 pm u 5 ppm lree 230 ppm and hree 35ppm and high rb sr 5 characterize peralkaline granites in contrast to their peraluminous and calc alkaline equivalents within the peralkaline suite comenditic and pantelleritic volcanics exhibit two to five fold increases in the concentrations of these trace elements over comagmatic granites these cannot be explained by crystal liquid fractionation processes and require the evolution of a sodium enriched fluid corresponding trace element increases in the granites in areas of alkali metasomatism support this argument and reflect the partial confinement of this volatile phase within the high level magma chambers ree studies in particular might eventually allow an evaluation of the role of cl versus f and co3 complexing in the evolution of the volatile fluid

mobilization and enrichment of high field strength elements during late and post magmatic processes in the shuiquangou syenitic complex northern china abstract the shuiquangou syenitic complex consists of melasyenite and leucosyenite in the northeastern part there is a small area where the leucosyenite was affected by alteration the altered leucosyenite contains much higher concentrations of high field strength elements hfse especially nb zr ree and y compared to fresh leucosyenite ree patterns of the altered leucosyenite show moderate negative eu anomaly in contrast to the slightly positive to non anomalous eu signature of the fresh syenitic rocks allanite from the hydrothermal mineral assemblage in the altered leucosyenite also contains much higher concentrations of ree and ti than the euhedral magmatic allanites in unaltered leucosyenite the enrichment of hfse in altered leucosyenite was interpreted to be caused by the hydrothermal fluids based on mineral chemistry and whole rock data within the fresh leucosyenite allanite occurs in two habits euhedral ones indicating a primary magmatic origin and anhedral ones suggesting a late magmatic origin the latter has higher concentrations of ree and ti than the former the anhedral allanite was presumed to be formed coeval with the alteration of the euhedral allanite as a result of residual magmatic fluid derived directly from the syenitic magma the alteration of magmatic euhedral allanite and the enrichment of ree and ti in the anhedral late magmatic allanite suggest that these elements were mobilized by the residual magmatic fluid both residual late magmatic and hydrothermal fluids have an inferred composition characterized by high alkalic and f contents suggesting that f may be the most ligand that complexed the high valence cations

rare earth element mobility in the roffna gneiss switzerland the roffna gneiss a deformed hercynian granite porphyry within the penninic nappes of eastern switzerland underwent extreme cataclasis with the progressive development of phengite towards the margins of the nappe under conditions of the glaucophane schist to greenschist facies this resulted in the selective mobilization of major and trace elements over distances of 10 s to 100 s of meters and the resetting of the rb sr whole rock isotopic systems some 100 my ago the component ratios and compositionvolume relationships of progressively deformed gneiss samples studied here suggest that this process was essentially isovolumetric the mineralogy of the deformation sequence appears to have been controlled by a reaction involving the breakdown of microcline albite and biotite and the formation of phengite and quartz the fluids introduced mg and h2o promoting the development of phengite and removed the na being released by the breakdown of albite the fluids were most probably derived from the surrounding triassic carbonates and quartzites these relatively high fo2 and carbonate rich fluids also introduced rare earth elements ree into the gneiss the gneiss was progressively enriched in eu up to 60 y up to 40 and yb up to 100 these enrichments are associated with the development of epitaxial xenotime around zircon in the most phengite rich sample while the ree were mobile uranium and thorium were essentially immobile the formation of xenotime was suggested to explain the observed heavy ree enrichment when large differences in the ree contents were found for replicate analyses using hf and then lithium metaborate for dissolution these differences arose because xenotime like monazite can be difficult if not impossible to dissolve in hydrofluoric acid due to the possibility of incomplete sample dissolution we now recommend fusion with lithium metaborate for all ree lu hf or sm nd studies

the prediction of total heave of a slab on grade floor on regina clay several analytical methods for the prediction of total heave of desiccated expansive soils have been proposed for various geographic regions the proposed method herein is based on a general theory for unsaturated soil the in situ stress conditions as assessed from the corrected swelling pressure and the required soil moduli are deduced from the constant volume oedometer test verification of the proposed method was accomplished using data accumulated from the monitoring of movements of a floor slab in a light industrial building in north central regina saskatchewan a leak in a water line buried under the floor slab resulted in a maximum heave of about 106 mm of the three final pore water pressure distributions assumed the one where pressure is constant with depth and equal to atmospheric pressure appears to be representative of the field conditions corresponding to the maximum measured heave the measured heave represents 89 of the predicted heave for the zero pore water pressure distribution it

u pb zircon dating of paleozoic volcanic rocks from the rheno hercynian zone new age constraints for the steinkopf formation lahn dill area germany small and volumetrically subordinate outcrops of alkali rhyolitic to trachytic metavolcanic rocks are widespread in the lahn dill area of the rheinisches schiefergebirge germany these occurrences are either related to late early devonian or to middle devonian episodes of volcanic activity an unambiguous age assignment for the time of eruption could not be established so far most volcanic rocks of the study area are not suitable for application of u pb geochronology a notable exception is the steinkopf rock suite in the sw lahn dill area but a straightforward interpretation of the la icp ms u pb data is hampered by complex zircon populations recording various processes including crystallization from newly formed melt inheritance assimilation of country rocks variable degrees of pb loss and fluid assisted zr mobility a plausible evaluation of u pb zircon data of two metatrachytes and a metavolcaniclastic rock document a coherent age group at ca 390 384 ma and a probable eruption age at ca 385 ma suggesting a relationship to middle devonian givetian igneous processes zircon bearing veinlets in a metatrachyte indicate post eruptive infiltration of external hydrothermal fluids and or internal zr redistribution in late devonian to early carboniferous time 364 10 ma but this process is of rather limited importance

full displacement pressuremeter testing in sand an alternative approach to pressuremeter testing in sand where the pressuremeter is pushed closed ended is discussed observations from cone penetration testing in sands are used to provide a theoretical background to the expected stress conditions around a full displacement pressuremeter probe pushed into sand the anticipated stress paths followed during the pressure expansion phase of the test are discussed data from both self boring and full displacement pressuremeter tests in sand are presented to support some of the suggested theoretical background key words pressuremeter testing in situ testing sand

field and geochemical characteristics of mesoarchean to neoarchean volcanic rocks in the storo greenstone belt sw greenland evidence for accretion of intra oceanic volcanic arcs abstract the storo greenstone belt southern west greenland consists of thrust imbricated slices of mesoarchean 3060 ma and neoarchean ca 2800 ma mafic to ultramafic volcanic rocks volcaniclastic sediments and gabbro anorthosite associations the belt underwent polyphase metamorphism at upper amphibolite facies conditions between 2650 and 2600 ma the contacts between the mesoarchean and neoarchean volcanic rocks and surrounding eoarchean to neoarchean tonalite trondhjemite granodiorite ttg gneisses are tectonic and typically bounded by high grade mylonites regardless of age the volcanic rocks are dominated by mafic amphibolites with a tholeiitic basalt composition near flat to slightly enriched light rare earth element lree patterns la smcn 0 91 1 48 relatively flat to slightly depleted heavy ree hree gd ybcn 1 0 1 28 and pronounced negative nb ta anomalies nb nb 0 34 0 73 on chondrite and primitive mantle normalized diagrams these geochemical characteristics are consistent with subduction zone geochemical signatures and partial melting of a shallow

the prediction of one two and three dimensional heave in expansive soils the prediction of heave in unsaturated expansive soils has historically been studied primarily as a one dimensional type analysis this paper proposes a methodology that can be used for the predic

zirconolite allanite and hoegbomite in a marble skarn from the bergell contact aureole implications for mobility of ti zr and ree zirconolite allanite and hoegbomite are present as accessory phases in a metasomatically altered spinel calcite marble from the contact with the bergell intrusives switzerland italy textural relationships indicate a step wise alteration of spinel to 1 hoegbomite or corundum magnetite 2 margarite and 3 chlorite replacement of spinel by hoegbomite can be described by the substitution 1 94 mg2 fe2 zn2 mn2 ca2 ti4 0 12 oh where al3 and fe3 are held constant the average composition of the bergell hoegbomites is given by the formula fe 0 97 2 mg0 69zn0 04ti0 17al3 94fe 0 06 3 o7 98 oh 0 02 and seems to be imposed by the composition of pre existing spinel during the first two steps of spinel alteration calcite was replaced by anorthite phlogopite and the rare earth element ree bearing minerals zirconolite allanite and sphene were formed allanites have characteristic chondrite normalized ree patterns with enrichment in the light ree the zirconolite patterns show a marked increase in concentration from la to ce followed by an almost constant section sphene lacks detectable la and its ree patterns vary from grain to grain contemporaneous formation of phlogopite ree bearing minerals and hoegbomite during replacement of the spinel calcite marble indicates that the metamorphic fluid introduced potassium along with ree and other high valence cations ti4 zr4 u4 th4a3804265 nb5a3804265 y3a3804265 possibly as polynuclear complexes the abundance of fluorine bearing phlogopite and fluor apatite as well as their close association with ree bearing minerals and hoegbomite suggests f and po 4 3 as likely ligands for complexing of the above mentioned elements

geikielite mg al spinel titanoclinohumite association from a marble quarry near rajapalaiyam area part of the 550 ma old southern granulite terrain southern india abstract geikielite and titanoclinohumite in association with fo mg al spl ap phl an fassaitic cpx chu cal dol assemblage are being reported for the first time from a marble quarry in the vicinity of rajapalaiyam town this locality forms part of the madurai block of the 550 ma southern granulite terrain and exhibits metamorphic p t conditions ranging from 7 9 kbars at 800 1000 c as deduced from the sil opx grt crd bt bearing pelitic assemblages the role of co 2 in the formation of the granulites has been dealt with most of the papers but only recently attention is being paid to the role of f rich halogenated fluids in the formation of humite bearing minerals and in the migration of elements like ti zr and ree the metamorphic fluid activity which led to the formation of the above unique fo spl ap chu assemblage including the geikielite and titanoclinohumite minerals can be associated with intrusive granites the charnockitic pods in the deformed calcitic marble zone may also have helped in providing ti p and zr k rich halogenated fluid activity seems to be common to the 550 ma eastern gondwana segments

zircon and titanite u pb dating of the zhangjiawa iron skarn deposit luxi district north china craton implications for a craton wide iron skarn mineralization abstract the north china craton hosts numerous iron skarn deposits containing more than 2600 mt of iron ores mostly with an average grade of 45 wt fe which have been among the most important source of high grade iron ores for the last three decades in china these deposits typically form clusters and can be roughly divided into the western and eastern belts which are located in the middle of trans north china orogen and to the west of the tan lu fault zone in the eastern part of north china craton respectively the western belt mainly consists of the southern taihang district as well as the linfen and taiyuan ore fields whereas the eastern belt comprises the luxi and xu huai districts the zhangjiawa deposit in the luxi district has proven reserves of 290 mt at an average of 46 fe up to 65 the iron mineralization occurs mainly along contact zones between the kuangshan dioritic intrusion and middle ordovician marine carbonate rocks that host numerous evaporite intercalations titanite grains from the mineralized skarn are closely intergrown with magnetite and retrograde skarn minerals including chlorite phlogopite and minor epidote indicating a hydrothermal origin the titanite grains have extremely low ree contents and low th u ratios consistent with their precipitation directly from hydrothermal fluids responsible for the iron mineralization ten hydrothermal titanite grains yield a weighted mean 206 pb 238 u age of 131 0 3 9 ma mswd 0 1 1 which is in excellent agreement with a zircon u pb age 130 1 ma of the ore related diorite this age consistency confirms that the iron skarn mineralization is temporally and likely genetically related to the kuangshan intrusion results from this study when combined with existing isotopic age data suggest that iron skarn mineralization and associated magmatism throughout both the eastern and western belts took place coevally between 135 and 125 ma with a peak at ca 130 ma as such those deposits may represent the world s only major phanerozoic iron skarn concentration hosted in precambrian cratons the magmatism and associated iron skarn mineralization coincide temporally with the culmination of lithospheric thinning and destruction of the north china craton implying a causal link between the two

mineral weathering processes in podzolic soils on granitic materials and their implications for surface water acidification many areas where concern has arisen over the recent acidification of their surface waters contain podzolic soils developed upon granitic materials the mineral weathering processes in these soils are reviewed and the ways in which such processes could be altered by acid deposition are considered the most weatherable primary minerals are plagioclase feldspar biotite and fine grained dioctahedral mica and their decomposition which is mediated by organic acids leads to the formation of proto imogolite allophane vermiculite and smectite other clay minerals occurring in podzols such as kaolinite and halloysite as well as gibbsite are probably inherited from previous weathering cycles although a present day pedogenic origin should not be ruled out entirely the possibility is considered that the partial replacement of soil organic acids by mineral acids introduced through precipitation could bring about significant differences in mineral weathering leading to more acid soils with more dissolved ionic aluminium in soil and stream waters the weathering products involved in the mobilization of aluminium from podzols are likely to be proto imogolite allophane and hydroxy al interlayered vermiculite or smectite another possibility is that sand and silt sized plagioclase feldspars are more reactive than previously realized

diagenetic f rich ferroan calcite and zircon in the offshore scotian basin eastern canada significance for understanding thermal evolution of the basin in the scotian basin offshore eastern canada an unusual combination of high heat flow in the cretaceous and the abundance of halite has resulted in unusual diagenetic minerals such as sphalerite the newburn h 23 well is the most distal well in the basin with good core samples and has two previously unknown diagenetic mineral occurrences fluorine rich ferroan calcite and diagenetic zircon this study uses sem backscattered electron images and eds analyses emp wds mineral analyses and raman spectroscopy to determine mineral chemistry and textures to investigate the diagenetic and thermal significance of these minerals late diagenetic fe calcite contains 1 2 5 wt fluorine mostly from adsorption but rarely as small fluorite crystals fluoride is also adsorbed on the surfaces of some framework minerals and chlorite fluoride was transported in highly saline formation brines derived from the argo salt formation zircon grains 20 40 m in size have crystal outlines that are straight adjacent to pores partially lobate filling porosity and cross cutting other grains these may be diagenetic some zoned detrital zircon grains show 1 3 m wide diagenetic outgrowths neoformation of diagenetic zircon requires temperatures of 250 c transport of zirconium is favored by ligands in low ph solution principally fluoride and phosphate anions with zirconium mobilized during the alteration of metamict detrital zircon under low grade metamorphic conditions the presence of diagenetic sphalerite and the documented mid cretaceous thermal event in the scotian basin indicate conditions that could have been suitable for the formation of diagenetic zircon in this well suitable geological conditions for such diagenetic formation of zircon will be found in a subsiding rift basin with early evaporites that are affected by a subsequent phase of volcanism due to new rifting or subduction

k o ocr relationships in soil the relationships between k o and ocr are investigated for primary loading unloading reloading conditions the study reviews laboratory data from over 170 different soils and presents an approach common to clays silts and sands simple empirical methods for predicting k o for normally consolidated and overconsolidated soils are evaluated the validity of the methods is supported by statistical analyses on the basis of the findings only the effective stress friction angle o and prior stress history ocr and ocrmax are needed to predict approximate values of k o

hydrologic issues associated with nuclear waste repositories significant progress in hydrology especially in subsurface flow and solute transport has been made over the last 35 years because of sustained interest in underground nuclear waste repositories the present paper provides an overview of the key hydrologic issues involved and to highlight advances in their understanding and treatment because of these efforts the focus is not on the development of radioactive waste repositories and their safety assessment but instead on the advances in hydrologic science that have emerged from such studies work and results associated with three rock types which are being considered to host the repositories are reviewed with a different emphasis for each rock type the first rock type is fractured crystalline rock for which the discussion will be mainly on flow and transport in saturated fractured rock the second rock type is unsaturated tuff for which the emphasis will be on flow from the shallow subsurface through the unsaturated zone to the repository the third rock type is clay rich formations whose permeability is very low in an undisturbed state in this case the emphasis will be on hydrologic issues that arise from mechanical and thermal disturbances i e on the relevant coupled thermo hydro mechanical processes the extensive research results especially those from multiyear large scale underground research laboratory investigations represent a rich body of information and data that can form the basis for further development in the related areas of hydrologic research

multiple stages of hydrothermal ree remobilization recorded in fluorapatite in the paleoproterozoic yinachang fe cu ree deposit southwest china abstract the yinachang deposit in the kangdian region southwest china contains large amounts of fe cu and ree and formed at 1700 ma in this deposit there are three stages of alteration and mineralization including pre ore na fe alteration fe ree mineralization and cu ree mineralization in the fe ree mineralization stage ree rich fluorapatite with total ree concentrations ranging from 10 700 to 34 000 ppm formed together with magnetite in the following cu ree mineralization stage large amounts of ree especially lree were leached out of the ree rich fluorapatite due to the interaction between fluorapatite and cl f co2 and ca rich but ree unsaturated fluids the leaching of ree was associated with the removal of si na th u pb and ba and modification of the oxygen isotope signature in the fluorapatite during a 840 ma tectonothermal event ree rich fluorapatite underwent the second interaction with oxidized f co2 and possibly cl rich but na and ca deficient fluids due to fluid fluorapatite interaction ree were removed from the fluorapatite but were immediately reincorporated into new phases within the fluorapatite thus the altered fluorapatite contains abundant ree mineral inclusions including bastnasite ce monazite ce and minor xenotime y a very small portion of the lree were transported out of the fluorapatite and formed bastnasite ce and monazite ce grains in the vicinity of the altered fluorapatite in addition to the metasomatism of fluorapatite allanite and primary synchysite ce from the cu ree mineralization stage were also altered with variable replacement of allanite by an assemblage of synchysite ce chlorite bastnasite ce and primary synchysite ce by bastnasite ce these styles of alteration were possibly synchronous with the second alteration phase of the fluorapatite this study demonstrates that ree can be mobilized during multiple stages of hydrothermal activities and highlights the significant controls fluid compositions have on ree transportation and deposition in hydrothermal system

analysis of the railway heave induced by soil swelling at a site in southern france in order to better understand the heave observed on the railway roadbed of the french high speed train tgv at chabrillan in southern france the swelling behaviour of the involved expansive clayey marl taken from the site by coring was investigated the aim the study is to analyse the part of heave induced by the soil swelling first the swell potential was determined by flooding the soil specimen in an oedometer under its in situ overburden stress on the other hand in order to assess the swell induced by the excavation undertaken during the construction of the railway a second method was applied the soil was first loaded to its in situ overburden stress existing before the excavation it was then flooded and unloaded to its current overburden stress after the excavation the swell induced by this unloading was considered finally the experimental results obtained were analyzed together with the results from other laboratory tests performed previously and the data collected from the field monitoring this study allowed estimating the heave induced by soil swelling subsequently the part of the heave due to landslide could be estimated which corresponds to the difference between the monitored heave and the swelling heave

on the thm behaviour of a sheared boom clay sample application to the behaviour and sealing properties of the edz abstract in this study the effect of the temperature increase on the hydro mechanical properties of sheared boom clay samples is investigated two samples of boom clay are resaturated in a new hollow cylinder triaxial cell with a short drainage path and then sheared by performing an axisymmetric triaxial loading the effect of the undrained heating under deviatoric stress is studied on the first sample it is shown that undrained temperature increase leads to an increase of pore water pressure and consequently to a decrease of the effective mean stress which brings the sample to failure for an initially sheared sample the failure occurs along the existing shear band which behaves as a weakness plane in the sample the responses of the local strain measurement transducers clearly show the sliding of rigid blocks when failure occurs in the sample the effect of the presence of a shear band on the permeability of the other boom clay sample is investigated at ambient temperature and at 80 c it is shown that the presence of a shear band does not affect significantly the permeability these results confirm the good self sealing properties of boom clay at ambient and at high temperature

time variations of the k0 coefficient in overconsolidated clays due to morphological evolution of slopes the incision of a natural or an artificial slope in a clay deposit initiates a morphological evolution and determines variations of the internal state of stress in the deposit this evolution can be analyzed considering the variations over time of the lateral stress at rest coefficient k0 this paper is focused on the evolution of the k0 in overconsolidated clay deposits submitted to the incision of natural slopes the proposed idea is that under specific morphological and evolutionary conditions a value of k0 1 could be considered reliable even for medium high oc clay deposits this idea is here discussed with the support of in situ and laboratory data from i pressuremeter tests performed in overconsolidated clay deposits in central italy and ii a scaled physical modeling experiment reproducing a normally consolidated clay deposit this study suggests that when dealing with clay deposits subjected to a simultaneous vertical and horizontal unloading due to slope incision the k0 coefficient should be considered a parameter variable as a function of the different stress strain evolutions experienced by each portion of the deposit the portions involved in the slope incision had different evolutions and are represented by different k0 values as a consequence diverse amounts of decrease distinguish the evolution of the k0 for natural rather than artificial slopes

the mobility of zirconium and other immobile elements during hydrothermal alteration abstract development of zircon and other zr phases in hydrothermal deposits indicates that zr can be highly mobile in these systems mobility is most common in but not restricted to f rich hydrothermal systems related to alkalic f rich igneous suites these suites can range from peralkaline through metaluminous to peraluminous a few examples are neither alkalic nor f rich three locations in the trans pecos magmatic province texas u s a demonstrate this hydrothermal zr mobility all three igneous systems are alkalic and f rich but vary in alkali al ratios peralkaline rhyolites and trachytes in the christmas mountains contain as much as 2100 ppm zr mostly in aegirine or arfvedsonite zircon is rare or absent fluorspar replacement deposits in limestone at contacts with the rhyolites contain as much as 38 000 ppm zr occurring as small disseminated zircons the deposits also are enriched in a variety of incompatible elements including be rare earth elements ree y nb mo hf pb th and u the sierra blanca intrusions a series of mildly peraluminous f rich rhyolite laccoliths contain as much as 1000 ppm zr mostly as zircon hydrothermal zircon occurs as overgrowths on magmatic grains as veinlets connected to overgrowths and in fluorspar replacement bodies in adjacent limestone the highest zr concentrations in fluorspar are 200 ppm metaluminous quartz monzonite from the infiernito caldera contains 400 600 ppm zr mostly as zircon euhedral zircon in quartz fluorite veins in the quartz monzonite indicates mobility of zr zirconium concentrations in the veins are unknown but the paucity of zircon suggests little zr enrichment relative to the host zircon and more rarely zirconolite occur in skarn in the ertsberg district of irian jaya indonesia unlike in texas related igneous rocks are metaluminous and the hydrothermal system was f poor worldwide hydrothermal zircon other zr phases and ti and al bearing phases occur in skarn epithermal precious metal veins volcanogenic massive sulfide deposits and mylonites we propose that differences in zr mineralogy of igneous source rocks is an important factor in determining the availability of zr to hydrothermal fluids although zr concentrations in the sierra blanca and christmas mountains rhyolites are similar zr enrichment in fluorspar was much greater in the christmas mountains we suggest that hydrothermal solutions could easily break down aegirine and arfvedsonite to release zr but that zircon was only moderately attacked therefore far more zr was available for transport and subsequent deposition in the christmas mountains than at sierra blanca availability of other trace elements probably is also governed by their mineral host although zr mobility is most common in f rich hydrothermal systems related to alkalic and f rich igneous systems mobility at ertsberg may have been promoted by sulfate complexing

suction effects in deep boom clay block samples extensive investigations have been and are being carried out on a stiff clay from an underground research laboratory located at mol belgium called boom clay in the context of research into deep nuclear waste disposal suction effects in deep boom clay block samples were investigated through the characterisation of the water retention and of the swelling properties of the clay the data obtained allowed an estimation of the sample initial suction that was reasonably compatible with the in situ state of stress at a depth of 223 m the relationship between suction and stress changes during loading and unloading sequences were also examined by running oedometer tests with suction measurements a rather wide range of the ratio s v being s the suction and v the effective vertical stress was obtained 0 61 1 different from that proposed by bishop et al 1974 finally the effect of suction release under an isotropic stress close to the estimated sample suction was investigated a slight swelling 1 7 was observed and further compression provided a satisfactory value of the overconsolidation ratio confirming the suggestions of taking some precautions before putting a swelling sample in contact with water as suggested by graham et al 1987 the various experimental data gathered in this study finally evidenced a relatively good state of conservation of the block sample used

zircon solubility in alkaline aqueous fluids at upper crustal conditions field evidence and thermodynamic data at ambient conditions suggest that complexing of zr with hydroxyl ions at high ph enhances the solubility of zircon we tested this hypothesis by measuring the solubilities of the assemblages zircon zrsio 4 baddeleyite z b and zircon quartz z q in neutral to alkaline fluids at 0 2 gpa and 450 750 c in neutral to alkaline fluids 0 0 1 1m naoh zircon dissolved incongruently in quartz undersaturated fluids to form baddeleyite at 450 c various na zr silicates precipitated from fluids saturated and undersaturated in quartz we observed no significant dependence of solubility on temperature the measured solubilities of zircon in pure h 2o at 600 and 750 c are only slightly higher than the procedural blank of 3 3 10 7 m zr however the measured solubility of zircon increases with increasing aqueous silica suggesting that zirconium complexes with silica in the fluid at 600 c linear regression of experimental results yielded ln zr 0 25 2 9 ln si where terms in parentheses represent molal concentrations zircon solubility also seems to increase with increasing hydroxyl concentration in the fluid enhanced solubility in silica rich alkaline fluids may cause dissolution reprecipitation of zircon and resetting of its isotopic clocks suggesting that some zircon u pb ages may correspond to fluid events

drying induced shrinkage of boom clay an experimental investigation drying induced shrinkage of geomaterials may have a strong effect on geostructure stability and deformation the settlement of foundations and fracture openings in slopes roads and tunnel walls may be due to drying shrinkage however there is still a lack of knowledge concerning shrinkage evolution with time and shrinkage propagation within the material in this study the shrinkage of a specific clayey rock boom clay under drying conditions is investigated experimentally this rock is a deep geological formation which is under study for high level and long term radioactive waste storage in belgium two experimental campaigns are presented the first based on the vapour equilibrium drying technique and coupled with sample size manual measurement aims to characterize the material shrinkage in balanced states the second based on the convective drying technique and coupled with shape monitoring using x ray tomography aims to analyse how shrinkage develops before reaching a steady state both app

the oxygen isotopic composition of uranium minerals a review abstract uranium ore is an essential material in the preparation of nuclear fuel for civilian as well as military uses uranium is first extracted from uranium bearing minerals using a variety of reagents and is precipitated from solutions as yellow cake prior to isotope enrichment processes the disintegration of the former eastern bloc in the 1990s and frequent unrest in the middle east have underscored the need for better characterizing source uranium ores for forensic and attribution purposes the world s major deposits of u occur in several distinctly different geological environments fourteen principal types of u deposits and rocks with elevated uranium contents are recognized with more than 40 subtypes combining our own analysis and literature data we have amassed over 250 oxygen isotope data from 13 major u producing countries which vary widely from 32 to 11 however interpreting the oxygen isotopic composition of uraninite in terms of the composition of the fluid from which it precipitated or interacted with requires knowledge of the fractionation factor and temperature of interactions which are not always available since each deposit type occurs within a unique geologic setting and is generally formed from chemically distinct fluids the chemical compositions of the uranium ores are also distinct uranium deposits that form in igneous rocks have higher trace element compositions relative to sandstone hosted deposits our data shows that one of the most useful techniques for distinguishing between uranium ore is to use a combination of 18 o values and rare earth elements e g la yb ratios these methods may allow investigators to trace uranium ore back to the source

yield states and stress strain relationships in a natural plastic clay reply natural clays are commonly anisotropic due to their mode of deposition and lightly overconsolidated because of a variety of subsequent geological processes they exhibit marked changes in stiffness when they yield yield stresses from individual tests can be generalized into a yield surface for the clay if displacements during loading are taken into account by calculating specific volumes v 1 e throughout the tests this paper describes tests on 76 mm diameter triaxial samples of natural plastic lake agassiz clay from winnipeg the samples were carefully trimmed reconsolidated to approximately their in situ stresses and loaded in stress controlled tests along various stress paths in p q stress space the tests produced well defined yield envelopes in p q p v and q v plots and in corresponding plots where the stresses were normalized with respect to the vertical preconsolidation pressure vc comparison of one dimensional yielding states with results from k0 triaxial tests that were continu

compression characteristics and index properties of tills and intertill clays in southern saskatchewan canada compression characteristics and index properties of unweathered tills and clays from repeated glaciations follow a predictable pattern at 10 sites along a 1300 km transect across southern saskatche

the measurement of soil stiffness in the triaxial apparatus this paper describes a simple technique for accurately measuring the mean local axial strains of triaxial samples over a central gauge length the technique makes use of an axial displacement gauge which is a development of one devised by burland symes 1982 which makes use of electrolytic levels the device can resolve to less than 1 m over a range of 15 mm is simple to mount on the specimen and is not damaged when the sample is taken to failure the results of undrained triaxial tests are presented for a wide spectrum of soil types ranging from sands through intact reconstituted and remoulded low plasticity till undisturbed london clay to intact unweathered chalk the test results show that conventional external measurements of displacement contain errors which are frequently so large that their use in the determination of soil stiffness at working levels of stress is invalid the errors mainly result from tilting of the sample bedding at the end platens and the effects of compliance in the app

geochemical processes and petrogenetic evolution of rodingite dykes in the ophiolite complex of othrys central greece rodingite dykes occur in serpentinised harzburgites in the othrys ophiolite hydrogrossular and diopside along with chlorite appeared first and mark the initiation of rodingitisation of the dolerite protolith subsequently calcite formed after diopside and consequently reacted with chlorite to enrich the rodingites in diopside and garnet apatite also forms at the late stages of alteration several geochemical exchanges were triggered by variably alkaline and continuously evolving fluids passing through the serpentinising peridotites a possible t xco2 path along with a reaction series are proposed for the development of the rodingitic assemblages that entail a fluid phase leaching of the peridotite was triggered by fluids very rich in co2 and carbonate complexes are thought to be responsible for mobilization of cr and ni under such conditions ree also were mobile and the presence of co32 and po43 ions that complexed them further assisted their transportation zr mobilised at increased ph conditions with the aid of the oh and po43 during the late stage of alteration and due to the incorporation of more saline fluids after formation of calcite and apatite in the two metasomatic stages respectively the ree complexes were destabilised due to reduced activity of co32 and po43 and free rees were able to precipitate onto garnet cr and ni hydroxides were precipitated after formation of calcite in the rodingite the saline fluids were also reducing hence eu remained in its divalent state and was highly absorbed on garnet surfaces the rodingitisation at othrys ophiolite occurred in a subduction regime as it is implicated by the very rich in co2 fluid phase which is readily explained by involvement of subducted carbonate sediments and is favoured by the development of structural zones that acted as conduits to the metasomatising fluid phase

the water retention properties of a natural unsaturated loess from northern france the water retention properties of a natural loess from northern france were investigated on intact block samples that were excavated along a high speed train line tgv that experienced stability problems during heavy rain episodes suction measurements were made by using the filter paper method and an in house constructed high capacity tensiometer hct so as to determine the water retention curve of the loess the results showed that an alternative approach using a previously wetted filter paper could fruitfully be used with suction values reasonably compatible with the hct measurements the water retention curve obtained exhibited a peculiar form with no hysteresis observed around the natural water content 14 4 and two hysteresis loops on both the wet and dry sides of the curve it is hypothesised that this zone with no hysteresis corresponds to the natural variations of the water content under seasonal changes providing a range of natural suction between 20 and 80 kpa and it is suggested that th

polymetallic mineralization at the browns deposit rum jungle mineral field northern territory australia the rum jungle mineral field northern territory australia forms part of the paleoproterozoic pine creek orogen the geology of the area comprises two archean granitic basement domes overlain by a paleoproterozoic sequence of metasedimentary and subordinate metavolcanic rocks the rocks have been deformed and metamorphosed to greenschist facies during the 1880 ma barramundi orogeny but the original stratigraphic succession has been preserved the browns deposit browns and its extension browns east hosted within black carbonaceous pelites of the paleoproterozoic whites formation is the largest base metal deposit found to date in the pine creek orogen present resource estimates are 39 million metric tons mt at 0 44 percent cu 3 61 percent pb 0 11 percent co and 0 09 percent ni browns and 31 mt at 1 29 percent cu 1 28 percent pb 0 13 percent co and 0 13 percent ni browns east major sulfide minerals in the ore zone are galena sphalerite chalcopyrite pyrite and the main carrier of ni and co siegenite ni co 3 s 4 digenite group minerals and bornite ca bearing plumbogummite pbal 3 po 4 2 oh 5 h 2 o arsenopyrite and gersdorffite are present in minor quantities ore minerals occur as fine grained wisps parallel to the main bedding parallel foliation and as coarse grained mono and polyminerallic aggregates that crosscut the foliation total noncarbonate carbon contents of unaltered rocks range from 1 07 to 7 51 wt percent total sulfur contents range from 2 13 to 6 14 wt percent petrographic studies and raman spectroscopy identify three varieties of carbonaceous matter primary syngenetic premetamorphic epigenetic grain coating and postmetamorphic epigenetic uraniferous migrated altered rocks are rarely encountered values of 34 s for sulfides range from 5 to 15 per mil and are interpreted to reflect a combination of inorganic thermochemical reduction of seawater and bacterial activity no specific sulfur isotope patterns for individual minerals can be established indicating nonequilibrium conditions homogeneous lead isotope signatures of galena 206 pb 204 pb 16 20 16 22 207 pb 206 pb 15 48 15 51 208 pb 207 pb 35 86 35 92 suggest that all pb was derived from a single crustal source and paragenetically late crosscutting galena appears to have been remobilized from bedding parallel galena despite the occurrence of uranium in similar rocks nearby uranium is quantitatively insignificant in the browns deposit and is not genetically related to base metal mineralization instead it is linked to brittle deformation in the waning stages of orogenesis the browns deposit differs from other well known sediment hosted stratiform ore deposits both the zambian copperbelt and the polish kupferschiefer deposits are copper dominant and hosted in sedimentary sequences with significant psammitic components the pb zn ag deposits of the proterozoic australian zinc province also have significant carbonate in their host rocks e g carbonaceous dolomitic and siltstone at mcarthur river and lack economically interesting cu co and ni the nearby woodcutters pb zn ag deposit in rocks of similar age also differs in structural setting veins dominant metals and pb isotopes from the browns deposit

ree bearing minerals in a ti rich vein from the adamello contact aureole italy zirconolite aeschynite ce titanite and apatite have been found as minor or accessory minerals in a ti rich tio2 2 1 4 5 wt hydrothermal vein occurring in dolomite marbles at the contact with a tonalite intrusion of the tertiary adamello batholith northern italy the vein consists of four distinct mineral zones comprising from margin to center 1 forsterite calcite 2 pargasite calcite titanite sulfides 3 phlogopite calcite titanite sulfides and 4 titanian clinohumite spinel calcite sulfides zirconolite occurs in two vein zones only in the phlogopite zone it is invariably anhedral often corroded and exhibits complex chemical zonation patterns in the titanian clinohumite zone zirconolite is idiomorphic and characterized by a pronounced discontinous chemical zoning but shows no evidence of corrosion the considerable compositional variation observed for zirconolite in wt ree2o3 0 74 16 8 uo2 0 59 24 0 tho2 0 67 17 1 is due to the zoning and may be attributed to four major substitutions described by the exchange vectors 1 th u mg fe2 ca 1 ti 1 2 ree al ca 1 ti 1 3 ree fe2 nb ta ca 1 ti 1 4 hf zr 1

impact of excavation damage on the thermo hydro mechanical properties of natural boom clay abstract boom clay has been considered as a potential host rock for the geological radioactive waste disposal in belgium in this context it is important to well understand the thermo hydro mechanical behaviour of this clay around the disposal galleries in this study the effect of excavation damage on the thermo hydro mechanical properties of natural boom clay around the connecting gallery excavated in 2002 in the mol underground research laboratory hades high activity disposal experimental site was investigated several samples taken from a horizontal borehole drilled in july 2012 were tested the thermal conductivity in three different orientations perpendicular parallel and 45 to the bedding plane was measured using the needle probe method the results show a cross anisotropy of natural boom clay and an impact of the excavation damage on the thermal property of samples near the gallery to further investigate the anisotropy behaviour bender element tests were carried out under unconfined conditions to determine the small strain shear modulus also in three different orientations the obtained results confirm the anisotropic behaviour of boom clay moreover the evolution of small strain shear modulus with the distance from the gallery axis r was found to be similar to that of thermal conductivity the values in the zone near the gallery are lower than those in the far field from these experimental data an extent of the excavation damaged zone edz of 4 m from the connecting gallery axis was determined further investigations on the microstructure of several samples taken at different distances r by mercury intrusion porosimetry mip and scanning electron microscope sem methods were carried out macro pores of diameter 5 m were identified in the samples near the gallery the identified macro pores were related to the effect of excavation damage and a damage variable was thus defined allowing a damage model to be developed the values of the two model parameters have been determined from the observed relationship between macro porosity and thermal conductivity comparisons between the predicted and experimental results in terms of small strain shear modulus and hydraulic conductivity show a reasonable agreement

ree mobilization during small scale high pressure fluid rock interaction and zoisite fluid partitioning of la to eu a zoisite quartz segregation and its adjacent host metabasite from the tauern window austria have been investigated in detail to study the geochemical behaviour of ree during high pressure fluid rock interaction and the role of zoisite the segregation formed at t 500 to 550 c p 0 6 gpa because of decompressional dehydration of the host metabasite during the formation of the segregation the ree la to tb and dy to lu were geochemically decoupled in the metabasite la to tb are incorporated in allanite and were leached from the host rock by the fluid phase this decoupling and the leaching of la to tb significantly alter the ree patterns of the host rock in the immediate vicinity of the segregation from lree enriched to lree depleted based on a mass balance calculation for la ce nd sm and eu the composition of the fluid from which the segregation was precipitated is calculated the fluid is lree enriched with la sm n 3 7 individual ree contents range from eu 2 4 1 1 ppm up to ce 90 20 ppm ree 190 50 ppm calculated partition coefficients dreezoisite fluid are generally 1 and increase from dlazoisite fluid 0 08 0 02 to deuzoisite fluid 0 8 0 4 indicating a stronger preference of zoisite for mree than for lree to describe the fractionation of la relative to sm between zoisite and fluid the la sm exchange coefficient between zoisite and fluid is calculated the derived exchange coefficient kd la sm zoisite fluid 0 2 0 1 suggests that a fluid in equilibrium with zoisite will have a three to ten times higher la sm ratio than coexisting zoisite

in situ u pb and trace element analysis of accessory minerals in the kiruna district norrbotten sweden new constraints on the timing and origin of mineralization northern norrbotten sweden is a key part of baltic shield and provides a record of magmatic tectonic and related superimposed fe oxide apatite and iron oxide copper gold iocg mineralization during the svecokarelian orogeny titanite and allanite from a range of mineral deposits in the area have been analysed for u pb isotope systematics and trace element chemistry using laser ablation quadrupole inductively coupled plasma mass spectrometry la icp ms analyses of a single sample from the regional scapolite albite alteration give an age of 1903 8 ma 2 and may be contemporaneous with the early stages of fe mineralization 1890 1870 ma analyses of titanite and allanite from undeformed iocg deposits indicate initial alteration at 1862 16 ma in many deposits subsequent metamorphic effects reset titanite isotope systematics from 1790 to 1800 ma resulting in a spread of u pb isotope analyses along concordia in some instances core regions may record evidence of early thermal events at around 2050 ma titanite and allanite from deformed iocg deposits on major shear zones record ages from 1785 21 ma to 1777 20 ma corresponding to deformation metamorphism and secondary hydrothermal alteration as a result of late orogenic movements the lack of intracrystalline variations in titanite and allanite trace element chemistry suggests that hydrothermal fluid chemistry and metal source were the main controls on mineral trace element chemistry titanite from undeformed fe oxide apatite and iocg deposits is typically light rare earth element lree enriched and shows low u th ratios and low ni in both intermediate to acid and basic volcanic hosted deposits this is consistent with a granitic source for metals minor variations in trace element patterns are consistent with the influence of aqueous complex formation on relative ree solubility deposits related to the nautanen deformation zone have relatively heavy ree hree enriched titanite and lree depleted allanite with high u th ratios and elevated ni contents consistent with leaching of metals from the local basic volcanic rocks all hydrothermal titanites are high field strength element enriched nb ta zr indicating their transport as a result of either high salinities or high f contents or both the data overall support models of iocg type mineralization as a result of regional circulation of saline hydrothermal fluids in association with major crustal structures with at least some metallic components derived from the granitoid rocks of the area all the deposits here show evidence of subsequent metamorphism although penetrative fabrics are restricted to regional scale deformation zones

the proterozoic albitite hosted valhalla uranium deposit queensland australia a description of the alteration assemblage associated with uranium mineralisation in diamond drill hole v39 the valhalla uranium deposit located 40 km north of mount isa queensland australia is an albitite hosted mesoproterozoic u deposit similar to albitite hosted uranium deposits in the ukraine sweden brazil and guyana uranium mineralisation is hosted by a thick package of interbedded fine grained sandstones arkoses and gritty siltstones that are bound by metabasalts belonging to the ca 1 780 ma eastern creek volcanics in the western succession of the mount isa basin alteration associated with u mineralisation can be divided into an early main and late stage the early stage is dominated by laminated and intensely altered rock comprising albite reibeckite calcite titano magnetite brannerite the main stage of mineralisation is dominated by brecciated and intensely altered rocks that comprise laminated and intensely altered rock cemented by brannerite apatite uranoan zircon uraninite anatase albite reibeckite calcite and hematite the late stage of mineralisation comprises uraninite red hematite dolomite calcite chlorite quartz and pb fe cu sulfides brannerite has u pb and pb pb ages that indicate formation between 1 555 and 1 510 ma with significant pb loss evident at ca 1 200 ma coincident with the assemblage of rodinia the oldest ages of the brannerite overlap with 40ar 39ar ages of 1 533 9 ma and 1 551 7 ma from early and main stage reibeckite and are interpreted to represent the timing of formation of the deposit these ages coincide with the timing of peak metamorphism in the mount isa area during the isan orogeny lithogeochemical assessment of whole rock data that includes mineralised and unmineralised samples from the greater mount isa district reveals that mineralisation involved the removal of k ba and si and the addition of na ca u v zr p sr f and y u th ratios indicate that the ore forming fluid was oxidised whereas the crystal chemistry of apatite and reibeckite within the ore zone suggests that f and text po 3 4 were important ore transporting complexes 18o values of co existing calcite and reibeckite indicate that mineralisation occurred between 340 and 380 c and involved a fluid having 18ofluid values between 6 5 and 8 6 reibeckite d values reveal that the ore fluid had a dfluid value between 98 and 54 the mineral assemblages associated with early and main stages of alteration plus 18ofluid and dfluid values and timing of the u mineralisation are all very similar to those associated with na ca alteration in the eastern succession of the mount isa basin where a magmatic fluid is favoured for this style of alteration however isotopic data from valhalla is also consistent with that from the nearby mount isa cu deposit where a basinal brine is proposed for the transport of metals to the deposit based on the evidence to hand the source fluids could have been derived from either or both the metasediments that underlie the eastern creek volcanics or magmatism that is manifest in the mount isa area as small pegmatite dykes that intruded during the isan orogeny

an assessment of the earth pressure coefficient in overconsolidated clays the determination of the earth pressure coefficient k0 in a natural clay deposit is a problem of considerable significance in geotechnical engineering while the methods for evaluation of k0 are reliable for normally consolidated soils significant difficulties still exist in evaluating k0 in overconsolidated clays given that it is influenced by the stress history of the material together with the age structure mineralogical composition and depositional environment indeed some of these factors are responsible for the soil becoming anisotropic the existing framework for prediction of k0 in overconsolidated soils does not account for any influences caused by anisotropy the work reported in this paper evaluates the validity of a revised relationship between k0oc and ocr overconsolidation ratio using data obtained from laboratory investigations the tests were performed on reconstituted and undisturbed samples of belfast upper boulder clay london clay and gault clay tests were also performed on re

titanium mobility in metamorphic systems a review abstract titanium is a dispersed lithophile element commonly regarded as chemically immobile at sub magmatic temperatures however a growing number of field studies demonstrate that ti is somewhat mobile in certain environments this review examines the current state of knowledge concerning the mobility of ti during alteration and metamorphism of crustal rocks also considered are relevant ti oxide solubility data from experiments and determinations of ti concentrations in natural waters where ti mobility is well documented its length scale is 10 m however ti may move greater distances in deep crustal shear zones the solubility of ti oxides in geologic fluids is strongly temperature dependent under low to medium grade metamorphic conditions ti mobility is limited by the low solubility of ti oxides in the associated fluids under eclogite conditions ti mobility is probably limited not by ti oxide solubility which reaches 1 ti but by restricted fluid flow in low permeability rocks

yielding and plastic behaviour of boom clay an underground research laboratory url has been excavated in a deposit of boom clay at a depth of 223 m by the sck cen belgian organisation near the city of mol this url is devoted to research into nuclear waste disposal this paper presents the results of an investigation carried out in the triaxial apparatus on specimens that were trimmed from blocks extracted during excavation sequences in the url in order to characterise the mechanical behaviour of the natural boom clay and to examine the effect of initial and induced anisotropy on its constitutive behaviour two series of triaxial tests were carried out special attention was devoted to the yield behaviour and the effects of stress history experimental results showed a clear relation between the shape of yield curves and stress history the yield curve of the clay in its initial state was oriented along the k0 line illustrating the anisotropy of fabric that was generated during the soil deposition subsequent isotropic compression up to 9 mpa

evolution of rodingites along stratigraphic depth in the iti and kallidromon ophiolites central greece abstract rodingitised rocks were collected from the neighbouring iti and kallidromon ophiolites they comprise metasomatic assemblages after serpentinised lherzolite and harzburgite gabbro and dolerite dykes the main mineral phases in the metasomatised mantle and gabbroic rocks include grossularitic garnet chlorite and diopside whereas epidote group minerals were mainly developed at the expense of the dolerite dykes the fluid phase involved in the metasomatic reactions was highly alkaline in the metasomatising peridotites and less alkaline in the altered gabbro and dolerite under such conditions ti is assumed to have remained immobile in the whole process while zr remained constant in the stratigraphically upper rodingitised gabbro and dolerite transportation of rare earth elements zr cr and ni from the altered mantle segment to the upper gabbro level was assisted by the presence of carbonate and hydroxyl ligands after consequent breakdown of the carbonate complexes these elements were deposited in the rodingitised gabbro and dolerite rare earths were mainly integrated in the neoblastic diopside whereas cr and ni likely formed insoluble hydroxides in that less reducing environment the metasomatic event happened in the mantle wedge close to the subduction of the pelagonian carbonates that strongly enriched the fluid phase in co 2 the entrance of an externally derived hydrothermal fluid was responsible for the reduction of ph at the higher levels and the calculated influx of si in the system

study on the hydraulic conductivity of boom clay the hydraulic conductivity is a parameter in geotechnical engineering practice that is key in seepage and consolidation analysis experimental results show that the hydraulic conductivity is mainly governed by the soil porosity and correlations with void ratio are usually proposed the validity of these correlations has been verified for soft clays and sands however few studies have included stiff clays in this work the hydraulic conductivity of boom clay a stiff clay taken from the essen site in belgium was determined from both consolidation and constant head percolation tests the data obtained was then analyzed to evaluate the existing correlations to predict the hydraulic conductivity in addition as these correlations usually require a referred hydraulic conductivity at a known void ratio the existing methods are often difficult to use in practice thus a new method was developed allowing the prediction of hydraulic conductivity without the referred value which was based on two existing co

stress release undrained storage and reconsolidation in simulated underwater clay triaxial testing has examined the influence of storage time and reconsolidation procedures on normally consolidated and overconsolidated samples of reconstituted clay prepared with high pore water pressures to simulate underwater deposits samples of illite were consolidated one dimensionally off loaded without drainage stored undrained reconsolidated and sheared undrained the storage times were 15 min 1 day and 7 days reconsolidation pressures were 1 isotropic to 2 isotropic to and 3 anisotropic to the results were compared with specimens that had not been off loaded different undrained storage times had no effect on the strengths after reconsolidation but the strengths were affected by the reconsolidation pressures anisotropic reconsolidation produced the best agreement between the control specimens and samples in terms of their strengths and af values the duration of storage time did affect stress strain parameters such as the undrained compression modulus e50 and the pore

proterozoic seawater felsic volcanics interaction w bergslagen sweden evidence for high ree mobility and implications for 1 8 ga seawater compositions mg enrichment in diffusely bounded schistose alteration zones occurring in proterozoic submarine felsic volcanics ne of hjulsjo w bergslagen is shown to result from felsic rock seawater interaction in a sub seafloor hydrothermal system the alteration is apparently in two stages feldspar being altered first to a kaolinite type clay which is then replaced by mg chlorite

alteration paragenesis and mineral chemistry of the tjarrojakka apatite iron and cu au occurrences kiruna area northern sweden the northern norrbotten area in northern sweden is an important mining district and hosts several deposits of fe oxide cu au type one of the best examples of spatially and possibly genetically related apatite iron and copper gold deposits in the region is at tjarrojakka 50 km wsw of kiruna the deposits are hosted by strongly sheared and metamorphosed intermediate volcanic rocks and dolerites and show a structural control the tjarrojakka iron deposit is a typical apatite iron ore of kiruna type and the tjarrojakka copper occurrence shows the same characteristics as most other epigenetic deposits in norrbotten the host rock has been affected by strong albite and k feldspar alteration related to mineralisation resulting in an enrichment of na k and ba fe and v were depleted in the altered zones and added in mineralised samples ree were enriched in the system with the greatest addition related to mineralisation y was also mobile associated with albite alteration and copper mineralisation the tjarrojakka iron and copper deposits show comparable hydrothermal alteration minerals and paragenesis which might be a product of common host rock and similarities in ore fluid composition or overprinting by successive alteration stages mineralogy and mineral chemistry of the alteration minerals apatite scapolite feldspars amphiboles and biotite indicate a higher salinity and ba k ratio in the fluid related to the alterations in the apatite iron occurrence than in the copper deposit where the minerals are enriched in f and s the presence of hematite barite and in so4 in scapolite suggests more oxidising rich conditions during the emplacement of the tjarrojakka cu deposit from existing data it might be suggested that one evolving system created the two occurrences with the copper mineralisation representing a slightly later product

estimation of in situ stresses using anisotropic elasticity and suction measurements sampling and specimen preparation produce changes in mean effective stresses and pore water pressures even with perfect sampling the paper takes an existing simplified three parameter cross anisotropic elastic model and uses it to model these changes the required ratio of cross anisotropic parameters j 3g can be obtained from standard ciu triaxial tests if measurements are also made of suctions in unloaded specimens in the laboratory then a combination of j 3g the measured suction and the effective overburden pressure permits an estimation of the horizontal effective pressure and the k0 at rest coefficient this can be helpful in numerical modelling that needs to start from in situ conditions and in planning pressure levels for reconsolidation of clay specimens in the laboratory tests were done on belfast upper boulder clay from a depth of 28 m values of horizontal in situ effective stress estimated from these measurements compare favorably with conventional estimates of the at rest coef

deep sampling and testing in soft stratified clay a 37 m thick layer of stratified clay encountered during a site investigation at swann s bridge near the sea coast at limavady northern ireland is one of the deepest and thickest layers of this type of material recorded in ireland a study of the relevant literature and stratigraphic evidence obtained from the site investigation showed that despite being close to the current shoreline the clay was deposited in a fresh water glacial lake formed approximately 13 000 bp the 37 m layer of clay can be divided into two separate zones the lower zone was deposited as a series of laminated layers of sand silt and clay whereas the upper zone was deposited as a largely homogeneous mixture a comprehensive series of tests was carried out on carefully selected samples from the full thickness of the deposit the results obtained from these tests were complex and confusing particularly the results of tests done on samples from the lower zone the results of one dimensional compression tests unconsolidated und

transport and deposition of ree in h2s rich fluids evidence from accessory mineral assemblages abstract it is shown in four examples from geologically different environments that accessory or minor minerals rich in rare earth elements ree are often texturally associated with base metal sulfides the examples demonstrate that ree can migrate in hydrothermal fluids containing large amounts of reduced sulfur s ii species i e h 2 s hs and s 2 in certain fluids complexes of ree with s ii species may be important for the ree transport but most probably only in the absence of other strong ligands such as fluoride carbonate or possibly phosphate textural relationships and geochemical data suggest that the formation of ree bearing minerals in s ii rich environments is genetically related to the precipitation of basemetal sulfides

hydrothermal mobility of ti zr and ree examples from the bergell and adamello contact aureoles italy contact metamorphic marbles affected by metasomatic fluids at the contact to the bergell and adamello intrusives contain various accessory minerals zirconolite allanite titanite rutile geikielite hoegbomite which provide new evidence for the hydrothermal mobility of ti and zr in both examples ti and zr migrated along with u th y and ree in a metasomatic fluid rich in potassium the composition of the main minerals fluorine rich phlogopite pargasite and titanian clinohumite and the abundance of fluor apatite demonstrate that fluorine and phosphorus were important components of the fluid the textural relationships indicate that the formation of the accessory phases is linked to the crystallization of the hydrous minerals

rare earth element mobility in vesicular lava during low grade metamorphism a geochemical comparison of basaltic relicts and spilitic domains from two burial metamorphosed flows in central chile of similar original composition and rich and poor in amygdules respectively demonstrates a relationship between initial vesicularity and rare earth element ree mobility during spilitization the ree were partly leached from permeable parts of the flows and precipitated in voids now amygdules and veinlets the ree excluding eu moved coherently in the highly amygdaloidal flow spilitic domains and amygdules inherited the basaltic ree pattern besides being characterized by a positive eu anomaly epidotes separated from amygdules have a ree distribution which mimics that of the basalt the absolute contents range widely suggesting local and or temporal ree variations in the metamorphic fluids pumpellyite differs by being strongly enriched in heavy ree similar ratios of th hf and ta in samples as contrasting as relict basalt and a geode are consistent with coherent leaching coherent mobility when established for a rock system can be used to elucidate for example whether minerals in cross cutting veins were formed by local redistribution or from introduced material

regional scale fluid flow and element mobility in barrow s metamorphic zones stonehaven scotland the geochemistry of metamorphic quartz vein formation in barrow s index mineral zones north of stonehaven scotland was investigated in order to assess regional fluid flow and mass transfer metamorphic grade in the dalradian metasediments increases to the north northwest away from the highland boundary fault hbf and associated ophiolitic rocks of the highland border complex hbc passing through the chlorite chl biotite bt garnet grt chloritoid cld and staurolite st zones syn metamorphic fluid infiltration at 462 8 8 ma breeding et al in am mineral 89 1067 2004 produced considerable quartz veining vein abundance varies from about 5 to 15 volume percent of the outcrops veins tend to be more abundant in metapelitic layers than in metapsammitic ones metamorphic veins are surrounded by centimeter to decimeter wide zones of chemical and mineralogical alteration selvages porphyroblasts particularly bt grt cld and st are typically larger in selvages than in wallrocks distal to veins the altered selvages underwent fluid driven addition of na ca and sr and loss of k rb and ba alteration is most intense within 750 m of the hbf but is still very significant at the northern end of the field area some 2 km away mg fet fet total iron was either unchanged or increased due to alteration silica was added at some chl and bt zone localities near the hbf pb mass transfer was variable although pb was added at a number of locations rare earth elements ree were generally immobile but light ree and possibly heavy ree were lost at one field site the gain of na and ca and loss of k promoted the growth of plagioclase at the expense of micas particularly muscovite in selvages and wallrock inclusions throughout the field area and probably some calcite and or dolomite growth directly adjacent to the hbf the ca gains were also critical for epidote production in the bt zone gains of ca and increases in mg fet helped to stabilize grt at the expense of cld and st in some selvages hornblende and cummingtonite were discovered in strongly altered metapelitic rocks at one cld zone locality the metasomatism puts important constraints on the processes of mass transfer and suggests two models for regional fluid flow in the first model fluid flow in a direction of increasing temperature downward along the hbf added na and ca and removed k from the dalradian in the second model fluid flow upward from the hbc transported na and ca into the overlying dalradian and at the same time stripped out k the latter model is favored because it can most readily account for silica addition near the hbf but neither model can be ruled out at present in either case the veins represent fractures that transmitted very large time integrated fluid fluxes of at least 104 m3 fluid m2 rock consequently the veins were conduits for regional fluid flow that caused considerable open system chemical and mineralogical alteration during metamorphism

the muscovite granites parental rocks to the nanling range tungsten mineralization in south china abstract muscovite granites mgs in the nanling range south china occur as satellite intrusions within or surrounding batholitic biotite monzogranites bms the mgs are massive and fine grained with a porphyritic texture and contain quartz k feldspar and albite in nearly equal portions the accessory minerals in the mgs include alumina rich minerals e g mn and fe rich garnet andalusite topaz and tourmaline anatase rutile wolframite cassiterite xenotime chalcopyrite molybdenite and volatile rich minerals e g microlite topaz tourmaline fluorite and calcite compared with the bms the mgs are geochemically enriched in major elements of si k and na and incompatible trace elements of rb cs y u nb ta w sn pb bi li and be and depleted in major elements of fe mg ca ti and p and compatible trace elements of ba sr co ni cr cd v as well as zr and hf the chondrite normalized ree patterns of the mgs are flat with large negative eu anomalies the mineralogical and geochemical features of the mgs indicate that they crystallized from highly fractionated granitic magmas zircons separated from the mg samples which were collected from six different tungsten deposits show characters of hydrothermal origin according to their morphologies chemical compositions and inclusions in situ u pb dating of the zircons yields a weighted mean 206pb 238u age of 133 4 1 0 ma this age is similar to the mean age of the zircons from wolframite bearing quartz veins wqvs in the nanling range 133 7 1 3 ma reported from our previous study zircon hf isotopes also reveal that the mgs and the wqvs are homologous these mineralogical geochemical and zirconological features indicate that the mgs are the parental rocks of the tungsten deposits in the nanling range this study provides a new guidance for the exploration of magmatic hydrothermal tungsten deposits

occurrence of contrasting skarn formations in dolomites of the traversella deposit ivrea italy metasomatic columns hosted in dolomitic marbles in the thermal aureole of the traversella monzodiorite ivrea italy differ by their mineralogy and or mineral composition three groups have been distinguished in group a the first zone always contains forsterite calcite and the second zone contains clinopyroxene the last zone is made of wollastonite a1 andradite rich garnet a 2 or grossular rich garnet a 3 in group b tremolite instead of forsterite occurs in the first two zones in group c columns there are only two zones and clinohumite or chondrodite characterize the first zone

effects of freeze thaw and softening on a natural clay at low stresses weathering processes such as softening and freeze thaw cycling affect the properties of clays care must therefore be taken when selecting strength and compressibility parameters for analysis of natural slopes compacted clay embankments and trench excavations in which significant proportions of the cross section can be affected by climatic weathering samples of plastic lake agassiz clay from winnipeg were consolidated anisotropically in the laboratory to axial stresses less than or equal to the in situ effective overburden pressure they were therefore all overconsolidated with respect to the field preconsolidation pressure the samples were then loaded under drained or undrained conditions along steeply rising stress paths in p q stress space one group of samples was tested immediately to identify the undisturbed behavior a second group was subjected to freeze thaw cycles and a third group allowed to swell freely before testing the freeze thaw cycling produced increased compressibility and pore

creep and consolidation of a stiff clay under saturated and unsaturated conditions in this paper the one dimensional 1d time dependent behaviour of natural and reconstituted london clay samples under saturated and unsaturated conditions is studied for this purpose a set of 1

petrography and petrogenesis of nephelinized metagabbros from finnmark northern norway plagioclase in olivine metagabbros metasomatized by nepheline syenite magmas was replaced by intergrowths of nepheline and vesuvianite or salite together with smaller amounts of calcic amphibole olivine was simultaneously replaced by diopside the survival of the gross features of protolith textures and clustering of line intersections in composition volume diagrams suggest that nephelinization took place at approximately constant volume and oxygen content nephelinization involved the introduction of na k and fe3 in an infiltrating peralkaline fluid and depletion of fe2 and fetot and was promoted by the primary mineral parageneses of the protoliths concurrent fenitization of quartzo feldspathic gneiss without the generation of feld spathoids shows that the processes of nephelinization and fenitization may result from the same fluid

milankovitch cyclicity and the boom clay formation an oligocene siliciclastic shelf sequence in belgium the boom clay formation of northeast belgium consists of a sequence of alternating laterally persistent beds of silt and clay power spectral analysis of grain size variations indicates regular sedimentary cycles with wavelengths of about 100 and 46cm that had periods of 124 and 57 thousand years ka or less the lateral continuity ofthe beds combined with the regularity and estimated periods of the cycles suggests an indirect link to the 100 and 41 ka orbital milankovitch cycles the variations in meangrain size were caused by changing bottom water turbulence as controlled by storms and or glacio eustatic water depth fluctuations this study confirms that certain marinesiliciclastic sequences can provide proxy records of palaeoclimatic variance

the rožna uranium deposit bohemian massif czech republic shear zone hosted late variscan and post variscan hydrothermal mineralization three major mineralization events are recorded at the ro na uranium deposit total mine production of 23 000 t u average grade of 0 24 u 1 pre uranium quartz sulfide and carbonate sulfide mineralization 2 uranium and 3 post uranium quartz carbonate sulfide mineralization 1 k ar ages for white mica from wall rock alteration of the pre uranium mineralization style range from 304 5 5 8 to 307 6 6 0 ma coinciding with the post orogenic exhumation of the moldanubian orogenic root and retrograde metamorphic equilibration of the high grade metamorphic host rocks the fluid inclusion record consists of low salinity aqueous inclusions together with h2o co2 ch4 co2 ch4 and pure ch4 inclusions the fluid inclusion paragenetic and isotope data suggest that the pre uranium mineralization formed from a reduced low salinity aqueous fluid at temperatures close to 300 c 2 the uraniferous hydrothermal event is subdivided into the pre ore ore and post ore substages k ar ages of pre ore authigenic k feldspar range from 296 3 7 5 to 281 0 5 4 ma and coincide with the transcurrent reorganization of crustal blocks of the bohemian massif and with late stephanian to early permian rifting massive hematitization albitization and desilicification of the pre ore altered rocks indicate an influx of oxidized basinal fluids to the crystalline rocks of the moldanubian domain the wide range of salinities of fluid inclusions is interpreted as a result of the large scale mixing of basinal brines with meteoric water the cationic composition of these fluids indicates extensive interaction with crystalline rocks chlorite thermometry yielded temperatures of 260 c to 310 c during this substage uranium was probably leached from the moldanubian crystalline rocks the hydrothermal alteration of the ore substage followed or partly overlapped in time the pre ore substage alteration k ar ages of illite from ore substage alteration range from 277 2 5 5 to 264 0 4 3 ma and roughly correspond with the results of chemical u pb dating of authigenic monazite 268 50 ma the uranium ore deposition was accompanied by large scale decomposition of biotite and pre ore chlorite to fe rich illite and iron hydrooxides therefore it is proposed that the deposition of uranium ore was mostly in response to the reduction of the ore bearing fluid by interaction with ferrous iron bearing silicates biotite and pre ore chlorite the th data on primary mostly aqueous inclusions trapped in carbonates of the ore substage range between 152 c and 174 c and total salinity ranges over a relatively wide interval of 3 1 to 23 1 wt nacl eq gradual reduction of the fluid system during the post ore substage is manifested by the appearance of a new generation of authigenic chlorite and pyrite chlorite thermometry yielded temperatures of 150 c to 170 c solid bitumens that post date uranium mineralization indicate radiolytic polymerization of gaseous and liquid hydrocarbons and their derivatives the origin of the organic compounds can be related to the diagenetic and catagenetic transformation of organic matter in upper stephanian and permian sediments 3 k ar ages on illite from post uranium quartz carbonate sulfide mineralization range from 233 7 4 7 to 227 5 4 6 ma and are consistent with the early tethys central atlantic rifting and tectonic reactivation of the variscan structures of the bohemian massif a minor part of the late variscan uranium mineralization was remobilized during this hydrothermal event

major minor and trace element mobility in the acidic upland forested catchment of the upper river severn mid wales variations in the major minor and trace element concentrations in two streams within a coniferous forest are described and are related to hydrological and hydrogeochemical factors the rainfall chemistry reflects a maritime influence although there are occasional pollutant inputs ph 4 5 streamwater chemistry variations are strongly dependent upon flow baseflow chemistry determined by reactions in the inorganic soils and bedrock is of a mg ca hco 3 type ph 6 7 5 mineralization yields up to a four fold increase in ca hco 3 zn and so 4 concentrations ph 0 5 units higher stormflow chemistry reflects hydrogeochemical processes in the organic soil horizons the stormflow waters are acidic ph 4 5 and are enriched by an order of magnitude in h ai y co and mn mineral equilibrium calculations have been applied to aluminium hydroxides crystalline and amorphous aluminosilicates and hydroxy aluminium sulphates to determine the degrees of mineral saturation in the streamwaters ion exchange reactions have been evaluated to describe the consequences of natural variations in atmospheric salt loadings and evapotranspiration on the stream water chemistry and to explain low na cl ratios in storm waters

the replacement of plagioclase feldspars by albite observations from hydrothermal experiments oligoclase and labradorite crystals have been experimentally replaced by albite in an aqueous sodium silicate solution at 600 c and 2 kbars the replacement is pseudomorphic and is characterised by a sharp chemical interface which progresses through the feldspar while preserving the crystallographic orientation reaction rims of albite up to 50 m thick can be readily achieved within 14 days re equilibration of plagioclase in an 18o enriched sodium and silica bearing solution results in oxygen isotope redistribution within the feldspar framework structure the observed characteristics of the reaction products are similar to naturally albitised plagioclase and are indicative of an interface coupled dissolution reprecipitation mechanism chemical analyses demonstrate that the albitisation is accompanied by the mobilisation of major minor and trace elements also including elements such as al and ti which are commonly regarded as immobile during hydrothermal alteration the results contribute to developing our understanding of the close association between large scale albitisation and secondary ore mineralisation which is common in nature

laboratory evaluation of k0 for overconsolidated clays most of the laboratory testing methods available for the evaluation of in situ horizontal stresses are applicable to normally consolidated or lightly overconsolidated clays this paper describes a new laboratory method for the determination of in situ horizontal stresses of heavily overconsolidated clays using a stress path triaxial apparatus the proposed method is based on the concept that if the radial stress exceeds the in situ horizontal stress while maintaining the axial stress constant and equal to the in situ vertical effective stress only then will the sample experience significant axial strain the results obtained for undisturbed samples of an overconsolidated clay crust are found to be in agreement with some available methods for verification of the applicability of the proposed method k0 was determined for artificially prepared samples that had been subjected to known stress paths simulating field stress history key words k0 overconsolidation in situ stress in situ test clay crust

a laboratory investigation of thermally induced pore pressures in the callovo oxfordian claystone in the framework of research into radioactive waste disposal it was decided to investigate the thermally induce pore pressure occurring in the callovo oxfordian claystone a possible host rock in which the andra underground laboratory of bure east of france has been excavated thermal pore pressures appear in low permeability soils and rocks because the thermal expansion coefficient of water is significantly higher than that of the solid grains campanella and mitchell 1968 1 ghabezloo and sulem 2009 2 this phenomenon has clearly been observed in various in situ heating tests conducted in opalinus claystone in the mont terri underground research laboratory url in switzerland he d test and in callovo oxfordian cox claystone in the bure url in france ter test wileveau and su 2007 3 the processes of coring transportation storage and specimen trimming induce some desaturation in the sample due to the very low permeability 10 20 m2 of the cox claystone a long period of time is necessary to properly resaturate the sample a mandatory condition to satisfactorily investigate thermal pressurisation particular emphasis was hence put on the previous saturation procedure that was carried out under in situ effective stress condition thermal pressurization has been investigated by performing undrained heating tests while measuring pore pressures changes in a specially adapted thermal isotropic compression cell special care was devoted to calibration procedures to account for the effects of the system on the pore pressure measurements the thermal pressurization coefficient measured appeared to change with temperature mainly because of the changes with temperature of both the water thermal expansion coefficient of water and the drained compression coefficient of the claystone

effective stress paths and yielding in soft clays below embankments current methods of predicting the response of soft clays to surface loading are often unsuccessful because the assumed constitutive relationships including effective stress path behaviour are incorrect in particular the transition from small strain to large strain behaviour i e yielding is frequently not taken into account recent laboratory testing has demonstrated that the behaviour of soft clays is largely controlled by yielding the locus of effective stress states causing yield is known as the yield envelope ye the effective stress paths esp s in soft clay foundations below the centre of six fills were determined from computed total stresses and measured pore water pressures yield behaviour is clearly indicated by esp shapes the yield envelopes inferred from analyses of field data are similar to those obtained from laboratory testing effective stress path shapes vary widely depending on a variety of factors including imposed stress level rate of construction and boundary drainage co