geochemical identification of episodes of gold mineralisation in the barberton greenstone belt south africa abstract the morphology and mineral chemistry of gold and associated sulphides at sheba fairview and new consort gold mines in the barberton greenstone belt bgb identify two main types of mineralization the first type occurs associated with sulphides mainly pyrite either as inclusions 10 30 m or as sub microscopic gold the second gold type consists of large gold grains 100 m within the silicates mostly quartz la icp ms studies reveal that some gold and associated sulphide grains contain high values of cl br na and i the elemental relationships reflect the different chemistry and precipitation processes of possible source fluids and identify several episodes of mineralisation in the study area one of them formed due to a boiling process in a supercritical hydrothermal environment this paper reports on the compositional characteristics of these gold grains the significance of the halogen contents and the implications for possible sources of the gold and associated sulphides

fluid inclusions in the stripa granite and their possible influence on the groundwater chemistry fluid inclusions in quartz and calcite of the proterozoic stripa granite central sweden demonstrate that the rock and its fracture fillings have a complex evolutionary history the majority of inclusions indicate formation during a hydrothermal stage following emplacement of the stripa pluton total salinities of quartz inclusions range from 0 18 eq wt nacl for unfractured rock and from 0 10 eq wt for fractured rock vein calcites contain up to 25 eq wt nacl but the inclusion size is larger and the population density is lower homogenization temperatures are 100 150 c for unfractured rock and 100 250 for fractured rock pressure corrections assuming immediate post emplacement conditions of 2 kbar give temperatures about 160 c higher measurements of fluid inclusion population densities in quartz range from about 108 inclusions cm3 in grain quartz to 109 inclusions cm3 in vein quartz residual porosity from inclusion densities has been estimated to be at least 1 which is two orders of magnitude greater than the flow porosity breakage and leaching of fluid inclusions is proposed as an hypothesis for the origin of major solutes na ca cl in the groundwater evidence for the hypothesis is based on 1 mass balance only a small fraction of the inclusions need to leak to account for salt concentrations in the groundwater 2 chemical signatures brcl ratios of fluid inclusion leachates 0 0101 match those ratios for the deep groundwaters 0 0107 3 leakage mechanisms micro stresses from isostatic rebound or mining activities acting on irregular shaped inclusions could cause breakage and provide connection with the flow porosity and 4 experimental studies water forced through low permeability granites leach significant quantities of salt this hypothesis is consistent with the available data although alternate hypotheses cannot be excluded

new caledonian eclogite province in norway and potential laurentian taconic and baltic links field observations and 4 0 ar 3 9 ar isotopic dating indicate that eclogites exposed in the lofoten islands north norway formerly presumed to be proterozoic features most likely formed as a result of early to middle paleozoic i e caledonian metamorphism the lofoten eclogites occur in shear zones that cut baltic precambrian continental basement this unusual style of occurrence is shared only with caledonian shear zone eclogites of the allochthonous bergen arcs of western norway our findings help to link scandinavian eclogites with those on the laurentian side of this collisional zone in east greenland ordovician to silurian eclogites also are found locally throughout the southern appalachian continuation of the orogen in eastern north america we compare the pressures ages and tectonic and structural settings of the eclogites along the 10 000 km length of the appalachian caledonian system our synthesis supports the idea that laurentian taconic elements may be preserved in high level nappes in norway the rare deep crustal metamorphic relicts also appear to be shared between baltica and laurentia offering a new perspective in which to view the geodynamic evolution of this once earth spanning orogenic system

use of doppler radar to assess ice cloud particle fall velocity size relations for remote sensing and climate studies knowledge of ice crystal terminal velocities both for individual crystals and for size distributions is important for an adequate representation of ice particle sedimentation in climate models while the terminal velocities t of individual crystals of simple shapes have been measured theoretical relations of the form t adb where d is the maximum particle dimension obtained using expressions for the aerodynamic drag force are often more useful because they can be applied to a wide range of particle sizes and heights and temperatures in the atmosphere for high tropospheric ice clouds the coefficient a has been found to vary over 1 order of magnitude the exponent b is generally within the range 0 7 1 4 aerodynamic drag force calculations show that a and b are related a and b can also be used to characterize terminal velocity particle characteristic size relations for size distributions in this study we use collocated vertically pointing measurements of ice cloud radar reflectivity doppler velocity and ir brightness temperatures to estimate the vertical profiles of cloud particle characteristic size cloud ice water content and vertically averaged value of the coefficient a emphasizing cirrus clouds we analyze variations in terminal velocity size relations for individual particles and corresponding variations for ensembles of particles for example in relations between the reflectivity weighted terminal velocity and the median volume size and between the mass weighted terminal velocity and the median volume size the retrievals indicate that a ranges from 250 to almost 4000 cgs units similar to the range found from the theoretical calculations the coefficient a tends to decrease as a characteristic particle size e g median size increases as a simplification for climate modeling efforts we present an empirical relation between median size and a although there is a fair amount of variability about this relation using the doppler measurements and retrieval data we also derive relations between the mass weighted terminal velocity and cloud ice water content such relations are useful for representing fallout of ice particles in climate and cloud resolving models

regional variations in fluid formation and metal sources in mvt mineralization in the pennine orefield uk implications from rare earth element and yttrium distribution sr nd isotopes and fluid inclusion compositions of hydrothermal vein fluorites abstract the pennine orefield is one of the most important ore fields for pb zn ba f mineralization in great britain it is subdivided into the northern pennine orefield npo consisting of the alston and askrigg blocks and the southern pennine orefield spo the alston block is underlain by the early devonian weardale granite and the askrigg block by the coeval wensleydale granite the potential relationship between the batholiths and the mineralization is a matter of debate we here studied the rare earth elements and y rey geochemistry sr nd isotopes and fluid inclusion fi compositions of fluorites from the two structural blocks in the npo and found that the fluorite mineralization in these blocks differ substantially the rey in askrigg fluorites show features that are characteristic for leaching of adjacent lower carboniferous limestones in contrast alston fluorites have significantly higher rey concentrations lack reysn limestone signatures and show a decoupling of redox sensitive eu from its trivalent rey neighbours neodymium isotopes indicate a similar crustal source of rey in both blocks but higher rey concentrations and lower y ho ratios suggest lower carboniferous shales as potential rey source in the alston block the fluids that precipitated the alston fluorites experienced temperatures 250 c prior to mineral formation as evidenced by eu geothermometry fluorite formation however occurred at much lower temperatures as suggested by homogenization temperatures in fi that fall within ranges of 105 159 c in alston and 99 160 c in askrigg fluorites mineralization of the mississippi valley type usually lack association with igneous activity we show that some of the fluids responsible for the npo mineralization were influenced by magmatic sources the rey systematics in alston fluorites may be linked to an interaction of the permian age whin sill dolerite with the basement granite which heated fluids and focussed fluid flow into the overlying sedimentary rocks in the askrigg block where such a dolerite intrusion was not described fluorites lack any positive eusn anomalies indicating that these fluids had never been subjected to temperatures exceeding 200 250 c

environment and collapse eastern anatolian obsidians at urkesh tell mozan syria and the third millennium mesopotamian urban crisis the early to middle bronze age transition in northern mesopotamia has received great attention for the apparent concurrence of aridification deurbanisation and the end of the akkadian empire around 2200 bce our understanding of the crisis has been almost exclusively shaped by ceramics demography and subsistence exchange and the associated social networks have been largely neglected here we report our sourcing results for 97 obsidian artefacts from urkesh a large urban settlement inhabited throughout the crisis before the crisis six obsidian sources located in eastern anatolia are represented among the artefacts such a diversity of eastern anatolian obsidians at one site is hitherto unknown in mesopotamia it implies urkesh was a cosmopolitan city with diverse visitors or visitors with diverse itineraries during this crisis however obsidians came from only two of the closest sources two to three centuries passed before varied obsidians reappeared even when an obsidian source reappears the raw material seems to have come from a different collection spot we discuss the likely exchange mechanisms and related social networks responsible for the arrival of obsidians at urkesh and how they might have changed in response to climatic perturbations and regional government collapse

stability of pargasite during ultrahigh temperature metamorphism a consequence of titanium and ree partitioning orthopyroxene clinopyroxene plagioclase needles and symplectite along the cleavage planes and grain boundaries of fluorine bearing titanian ferroan pargasite from the highland complex sri lanka are interpreted as evidence for dehydration melting at ultrahigh temperature conditions high ti up to 0 4 pfu and f x f up to 0 56 content in pargasite extends its stability to higher temperatures and the composition indicates the dehydration melting reaction may take place at ultrahigh temperatures 950 c at a pressure around 10 kbar close to peak metamorphic conditions the increase of ti content close to the grain boundaries and cleavage planes in pargasite indicates titanium partitioning from the melt during dehydration melting enhanced the stability of the mineral toward ultrahigh temperature conditions the ree content in the pargasite shows a similar behavior to that of titanium the cores with no breakdown assemblage consist of low and flat ree concentrations with respect to the high and eu depleted rim clinopyroxene in symplectite and needle shaped lamellae within the pargasite porphyroblasts have similar ree patterns with slightly low concentrations relative to that of pargasite in the breakdown assemblage lrees are partitioned mainly into plagioclase while the hrees are partitioned into orthopyroxene the ree enrichment in the pargasite rims signals their relative partitioning between pargasite rims and melt modeling of the partitioning of ti and rees associated with pargasite breakdown demonstrates that its stability is greatly enhanced at uht conditions this investigation implies that the stability of hydrous minerals such as amphibole can be extended to uht conditions and expands our knowledge of metamorphism in the lower crust

geochemistry and origin of saline groundwaters in the fennoscandian shield chemical and isotopic analyses of water from drill holes and mines throughout the fennoscandian shield show that distinct layers of groundwater are present an upper layer of fresh groundwater is underlain by several sharply differentiated saline layers which may differ in salinity relative abundance of solutes and o h sr and s isotope signature saline groundwater can be classified into four major groups based on geochemistry and presumed origin brackish and saline waters from 50 200 m depth in coastal areas around the baltic sea exhibit distinct marine chemical and isotopic fingerprints modified by reactions with host rocks these waters represent relict holocene seawater inland three types of saline groundwater are observed an uppermost layer of brackish and saline water from 300 900 m depth saline water and brines from 1000 2000 m depth and superdeep brines which have been observed to a depth of at least 11 km in the drill hole on the kola peninsula u s s r electrical and seismic studies in shield areas suggest that such brines are commonly present at even greater depths the salinity of all inland groundwaters is attributed predominantly to water rock interaction the main solutes are cl ca na and mg in varying proportions depending on the host rock lithology the abundance of dissolved gases increases with depth but varies from site to site the main gas components are n2 ch4 up to 87 vol and locally h2 the 13c value for methane is highly variable 25 to 46 and it is suggested that hydrothermal or metamorphic gases trapped within the surrounding rocks are the most obvious source of ch4 the uppermost saline water has meteoric oxygen hydrogen isotopic compositions whereas values from deeper water plot above the meteoric water line indicating considerably longer mean residence time and effective low temperature equilibration with host rocks geochemical and isotopic results from some localities demonstrate that the upper saline water cannot have been formed through simple mixing between fresh water and deep brines but rather is of independent origin the source of water itself has not been satisfactorily verified although superdeep brines at least may contain a significant proportion of relict precambrian hydrothermal or metamorphic fluids

co 2 melts and granulite metamorphism the discovery that granulites contain co2 rich fluid inclusions while amphibolites in the same terrane contain h2o rich or mixed co2 h2o inclusions1 has led to a debate over the processes that produce granulite metamorphism one theory2 4 maintains that granulites form as the result of a massive influx of co2 from lower crustal or mantle sources such an influx could be responsible for the marked depletion many granulite terranes show in large ion lithophile elements2 5 others however maintain that granulite facies metamorphism is a necessary complement of crustal melt ing6 9 recently lamb and valley10 11 have argued that granulite metamorphism may be a product of any one of three processes co2 streaming partial melting or recrystallization of originally dry rocks here we suggest that these processes need not be independent and that they all may be related to the passage of melts through the crust

a hot spring in granite of the western tianshan china the western tianshan range is a major cenozoic orogenic belt in central asia exposing predominantly paleozoic rocks including granite ongoing deformation is reflected by very rugged topography with peaks over 7000 m high active tectonic deformation is tied to an e w trending fracture and fault system that sections the mountain chain into geologically diverse blocks that extend parallel to the orogen in the muzhaerte valley upwelling hot water follows such a fault system in the muza granite about 20 l min 1 na so4 cl water with a temperature of 55 c having a total mineralization of about 1 g l 1 discharge from the hot spring the water is used in a local spa that is frequented by the people of the upper ili river area its waters are used for balneological purposes and the spa serves as a therapeutic institution the major element composition of the hot water is dominated by na and by so4 and cl ca is a minor component dissolved silica 1 04 mmol l 1 corresponds to a quartz saturation temperature of 116 c and a corresponding depth of the source of the water of about 4600 m this temperature is consistent with na k and na li geothermometry the water is saturated with respect to fluorite and contains 7 5 mg l 1 f as a consequence of the low ca concentration the water is undersaturated with respect to the primary minerals of the reservoir granite at reservoir temperature causing continued irreversible dissolution of granite the waters are oversaturated with respect to ca zeolite minerals such as stilbite and mesolite and it is expected that zeolites precipitate in the fracture pore space and in alteration zones replacing primary granite the stable isotope composition of o and h supports a meteoric origin of the water the cl br mass ratio of 1500 suggests that the salinity results from halite dissolution salts leached from powders of muza granite show the same cl br signature as the hot spring water sodium chloride is stored in fluid and solid inclusions in the granite which have been introduced to quartz by ductile shearing and faulting related to ongoing orogenesis the hot water remobilizes the salt that is continuously liberated by the tectonic deformation water granite interaction contributes a thenardite component na2so4 to the major element composition by albite dissolution in h2so4 the water rock interaction along faults and fractures transforms and alters muza granite to a low temperature epigranite

distinguishing nemrut dag and bingol a obsidians geochemical and landscape differences and the archaeological implications abstract distinguishing the geochemically similar bingol a and nemrut dag peralkaline obsidians is a major challenge in near eastern obsidian sourcing despite abundant claims in the literature otherwise this study reveals that bingol a and nemrut dag obsidians are distinguishable with adequate source sampling and highly accurate and repeatable data for geochemically important elements earlier research has endeavored to link a simple geochemical trend peralkalinity to specific locations at nemrut dag but existing schemes to distinguish bingol a and nemrut dag obsidians cannot validly link compositional clusters to the landscape this study demonstrates that additional elements are required to attribute artifacts to specific obsidian bearing lava flows at the volcano limitations of this newly analyzed collection of geo referenced nemrut dag and bingol specimens suggests caution is still warranted in sourcing peralkaline obsidians but a few archaeological implications are clear new sourcing results from tell mozan in northeastern syria refute a widespread assumption that one can use maximal efficiency to deduce whether peralkaline obsidian artifacts originated from nemrut dag or bingol a the ability to discern among these sources also enables inquiries into issues of cultural and technological preferences regarding these obsidians

late stage anhydrite gypsum siderite dolomite calcite assemblages record the transition from a deep to a shallow hydrothermal system in the schwarzwald mining district sw germany abstract the majority of hydrothermal vein systems of economic interest occur at relatively shallow crustal levels although many of them formed at significantly greater depths their present position is a consequence of uplift and erosion although many aspects of their formation are well constrained the temporal chemical evolution of such systems during uplift and erosion is still poorly understood these vein minerals comprise calcite dolomite ankerite siderite magnesite anhydrite and gypsum forming the last gangue assemblages in jurassic and tertiary sulphide fluorite quartz barite veins of the schwarzwald mining district sw germany mineral textures of samples from nine localities reveal that in these sequences mineral precipitation follows a recurring pattern early calcite is followed by anhydrite or gypsum siderite and or dolomite this succession may repeat up to three times in situ la icp ms u pb age dating of 15 carbonates from three subsequent generations of the late stage vein assemblage yield robust ages between 20 and 0 6 ma each mineral sequence forms in a distinctive period of about 2 5 ma these ages clearly relate these late stage mineral phases to the youngest geological episode of the schwarzwald which is associated with the cenozoic rhine graben rifting and basement uplift based on thermodynamic modelling the formation of the observed mineral assemblages required an deeply sourced mg fe and so4 rich fluid b which was episodically mixed with a shallow crustal hco3 rich fluid a as a consequence of fluid mixing concentrations of mg fe and so4 temporarily increased and initiated the formation of the observed sulphate carbonate mineral sequences this discontinuous large scale vertical fluid mixing was presumably directly related to episodes of active tectonics associated with the cenozoic strike slip regime of the upper rhine graben analogously episodic fluid mixing is a major key in the formation of older jurassic to early tertiary pb zn fluorite quartz barite assemblages in the same specific vein systems albeit involving different fluid compositions late stage hydrothermal 20 70 c vein assemblages reported in this study record the transition from deep 2 km to very shallow 0 1 km crustal conditions as a consequence of successive uplift increasing proportions of shallower and cooler 50 70 c fluids could take part in such mixing processes associated changes in the fluid composition caused the vein mineralogy to change from sulphide quartz fluorite barite to calcite anhydrite gypsum siderite dolomite as the system passively ascended closer to the surface

halite and sylvite as solid inclusions in high grade metamorphic rocks solid inclusions of halite and sylvite formed during regional and contact metamorphism have been identified by microscopy and by electron microprobe analysis in rocks from campolungo switzerland and cornone di blumone italy the solid inclusions occur in several of the major minerals crystallized during metamorphism and have been observed as idiomorphic crystals and dendrites the compositions measured in 100 analyses from campolungo switzerland and 40 analyses from cornone di blumone italy extend across the two phase region in the system kcl nacl indicating that the salt inclusions are high temperature precipitates in both localities compositionally zoned and unzoned crystals have been found measured compositions on the temperature maximum of the two phase region indicate at least 500 c which can be compared with 500 20 c determined by mercolli 1982 and walther 1983 from the mg content of calcites from campolungo the solid inclusions have been trapped apart from co2 rich and saline h2o rich fluid inclusions which have been described by mercolli 1982 as the earliest preserved fluid inclusions in the rocks the early precipitation of salt minerals at campolungo indicates that fluids were saturated with nacl and kcl at 500 c and pressures of 2 000 bars or higher similar relationships exist between solid and fluid inclusions in the rocks of cornone di blumone which formed at temperatures as high as 800 c and pressures between 0 5 and 1 kilobar ulmer 1983 the entrapment of halite and sylvite as solid inclusions preserves the composition of the minerals which may therefore be useful as geothermometers

trace element rich brines in eclogitic veins implications for fluid composition and transport during subduction primary and pseudosecondary fluid inclusions occur in oscillatory and sector zoned omphacite in eclogitic veins from the monviso ophiolitic complex in the western alps the inclusions contain aqueous brines and daughter crystals of halite sylvite calcite dolomite albite anhydrite and or gypsum barite baddeleyite rutile sphene fe oxides pyrite and monazite this daughter mineral suite indicates high solubilites of na k ca mg fe zr ti p ba ce la th and s species and provides direct evidence for transport of high fieldstrenght large ion lithophile and light rare earth elements as dissolved species during subduction fluid inclusion heterogeneities preserved within and between adjacent grains in the veins however suggest that the scale of fluid equilibration was small a crack seal geometry in some of the veins implies that fluid release in pulses rather than steady flow controlled mineral deposition and growth in the veins from these observations we develop a model of fluid release and entrapment in which pulses of fluid are associated in time with increments of shear and tensile failure the rate of fluid release and the reduction in porosity both depend on the rate of plastic flow vein fluids may initially be derived from decreptitation of early fluid inclusions in the host eclogites small scale fluid heterogeneities implied by the fluid inclusions in the veins are best interpreted in terms of limited fluid flow and hence limited metasomatism we conclude that element recycling into the mantle wedge during subduction will depend at least as strongly on fluid transport mechanisms as on element solubilities in the fluid phase at monviso despite evidence for high trace element solubilities in saline brines the elements were not removed from the downgoing slab prior to teaching depths of 40 km

fluorine as a tool in the petrogenesis of quartz bearing magmatic associations applications of an improved f oh biotite apatite thermometer grid abstract fluorine contents of whole rock and biotites allow to discriminate quartz bearing magmatic associations through the nature of protoliths and petrogenetic processes f and rb are used to discriminate crustal and mantle derived melts with the exception of calcalkaline association in which mantle contribution may be significant the other quartz bearing associations are essentially derived from crustal melting by biotite and or amphibole vapor absent reactions based on experimental data and on an improved biotite apatite thermometer grid closure temperatures from near liquidus to near solidus conditions as well as fh2o fhf evolution during cooling are determined for the different magmatic associations it appears that the liquidus temperature and fh2o fhf decreases in the order high silica alkaline high k calcalkaline and calcalkaline associations while the solidus temperature follows an inverse order the fh2o fhf values for the peraluminous associations vary over a wide range and overlap the fh2o fhf values of the high k calcalkaline and calcalkaline associations

saline groundwaters in the hercynian granites chardon mine france geochemical evidence for the salinity origin abstract in this study the chemical evolution of high cl chardon mine groundwaters is modelled as a mixing between an oxidising recharge and an old marine component on which the water rock interaction is superimposed chemical and isotopic similarities with saline carnmenellis mine groundwaters are emphasised and a general comparison with other brines is discussed the cation content of deep granitic groundwaters is indicative of the water rock interaction in the case of chardon and carnmenellis groundwaters the high na cl ratio can still be related to the contribution of a brine of sedimentary origin to the water salinity the differences in the hydrochemistry related to their geological context only appears at the trace metals level on the contrary brines in plutonic rocks which exhibit a low na cl ratio represent groundwaters having a residence time in the host rock long enough to equilibrate with secondary aluminosilicates in that case the brine origin is difficult to assess if only based on the water cation content

water soluble chlorides in massive seafloor serpentinites a source of chloride in subduction zones abstract dissolved cation and anion species were measured in the water soluble fraction of massive seafloor serpentinites leached with distilled h 2 o soluble chloride contents ranged from 0 09 to 0 51 wt average 0 26 wt so 4 2 to 0 09 wt mg 2 to 0 16 wt and na to 0 09 wt the concentration of evolved ions was the same in samples equilibrated with water at 25 and 230 c demonstrating that a significant amount of cl present in serpentinites occurs as water soluble salts a nearly equal amount of cl exists in the leached serpentinite likely sited in serpentinite itself the formation of intergranular salts in the serpentinite can be explained by seawater hydrothermal alteration of peridotite hydration reactions and h 2 o incorporation in the serpentine leave the residual fluid with ever increasing salinity and ultimately lead to precipitation of water soluble chlorides chlorine isotope ratios in the water soluble fraction average 1 49 vs standard mean ocean chlorine smoc from a core at the iberian abyssal plain and 0 16 from a much younger core at hess deep the 37 cl value of insoluble cl is 0 33 higher than the soluble fraction the nonzero 37 cl values demonstrate that the cl in the serpentinites is not an artifact of seawater incorporation during drilling the following conclusions are presented 1 serpentinite may be the major conduit for surficial chlorine transfer to mantle depths and an important part of the global chlorine cycle the cl flux in serpentinites into the mantle is larger than all other previously identified fluxes 2 cl is sited in both a water soluble and insoluble component 3 a high salinity fluid plume is evolved during serpentinite dehydration of a subducting slab the high salinity fluid affects metamorphic reactions and melting properties above the slab and can cause intense metasomatism the unusual bulk composition of the whiteschist from dora maira can be explained by channeled passage of a high salinity fluid 4 high salinity fluids reduce the stability field of serpentine causing its dehydration to occur over a broad interval which may partly explain the broad locus of intermediate depth earthquakes

diversity in obsidian use in the prehistoric and early historic middle east abstract the presence of obsidian in the near east has always evoked a response about its exotic nature and origins it was not until 1960s however that this was put onto a scientific footing when colin renfrew and his collaborators began to explore obsidian in turkey and the mediterranean their characterisation of the sources allowed them to attribute artefacts to different sources and suggest models of dispersal and distribution since then considerably more artefacts have been attributed to sources although mostly only small numbers from individual sites this has led to various interpretations of how obsidian was obtained and used new studies have considered least cost path analysis network analysis and agent based modelling increasingly new methods of provenancing of artefacts have also meant that large number of artefacts can be analysed relatively speedily and efficiently portable instruments allow data to be collected outside laboratories avoiding restrictions imposed by export licenses or simplifying work on museum collections here we employ richness and diversity indexes to elucidate some of the patterns in obsidian source use and argue that there are several reasons why the provenancing of large proportions of assemblages will be critical in exploiting the true potential of obsidian studies in the near east even though the initial haphazard small sample approach has been quite effective in sketching out the big picture

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

ten seconds in the field rapid armenian obsidian sourcing with portable xrf to inform excavations and surveys armenia has one of the most obsidian rich natural and cultural landscapes in the world and the lithic assemblages of numerous palaeolithic sites are predominantly if not entirely composed of obsidian recent excavations at the middle palaeolithic cave of lusakert 1 recovered on average 470 obsidian artifacts daily after sourcing more than 1700 artifacts using portable xrf pxrf in our field house our team sought to shift pxrf based obsidian sourcing into the field itself believing that the geological origins of artifacts would be useful information to have on site during an excavation or survey despite increasing use of portable instruments previous studies have principally focused on collections in museums and other archives and as a result obsidian sourcing has remained embedded in post excavation studies one critical factor in the uptake of obsidian sourcing in the field is the time needed to measure each artifact frequently 2 6 min in previous studies here we report our two methods of obsidian sourcing including source matching done automatically by the pxrf instrument s onboard software in only 10 s our tests with armenian geological specimens and palaeolithic artifacts demonstrate the high efficacy of our two methods which are sufficiently fast to become syncopated with our excavation and survey activities by reducing measurement times from a mode of 300 s in recent studies to just 10 s here we show how and why to shift pxrf based obsidian sourcing from the context of white lab coats to that of muddy boots

networks and neolithisation sourcing obsidian from kortik tepe se anatolia abstract this paper details the use of obsidian sourcing to reconstruct networks of interaction or communities of practice amongst populations of south eastern anatolia and the near east in the context of neolithisation during the late 11th early 10th millennia bc edxrf was used to elementally characterise 120 artefacts of epi palaeolithic pre pottery neolithic a date from kortik tepe in south eastern anatolia four eastern anatolian sources are represented mainly bingol a b and nemrut dag plus the first evidence for the use of mus obsidian when the source data is integrated with the artefacts techno typological attributes it is possible to locate the assemblage within an upper tigris tradition with some interesting local differences which stands in stark contrast to contemporary practices in northern mesopotamia and the levant these local and regional distinctions support recent views of the neolithic being much more heterogeneous with a mosaic of community specific local traditions of subsistence practices raw material choices and lithic technologies during the younger dryas early holocene

fluid induced mineral composition adjustments during exhumation the case of alpine stilbite stilbite is locally present as a very late mineral on fractures and fissures of granitic basement in the central swiss alps stilbite samples from the gotthard rail base tunnel provide evidence that they originally formed as a k absent variety at depth however all stilbite samples from surface outcrops above the tunnel display significant potassium concentrations interestingly water from fractures in the tunnel at 50 c is oversaturated with respect to stilbite and essentially potassium free whereas waters from high alpine brooks above the tunnel and at other high alpine areas have unusually high k na ratios the data suggest that stilbite that may actively form on fissures at tunnel level as a k absent variety by precipitation from water older stilbite that originally formed as coatings on fracture walls was gradually exhumed and uplifted and finally reached the today s erosion surface about 2 000 m above the tunnel however the stilbite reaches the erosion surface as a k rich variety as a result of interaction of the original low k stilbite with surface water and near surface groundwater this leads to the conclusion that minerals once formed at depth may significantly change their composition once they reach the ground water zone on their way to the erosion surface in the case of the stilbite if surface outcrops would have been the only source of samples and data the k rich composition could have been mistaken for the composition of the mineral when it formed which is not the case late stage compositional readjustments may be difficult to discern in samples from surface outcrops the provided data show that original mineral compositions may be adjusted by late stage water rock interaction in a highly selective way

pxrf characterisation of obsidian from central anatolia the aegean and central europe the obsidian sources of central anatolia the aegean and central europe have been studied in detail over the past 50 years various analytical techniques have been employed to discriminate artefacts from each of these and to reconstruct their zones of distribution this paper presents a pxrf method that allows mass sampling of artefacts focusing on three neighbouring regions particularly where these zones overlap successful discrimination of the obsidian source for products could be achieved using three dimensional scatter plots of trace elements rb sr zr pxrf can thus be appreciated as a powerful tool in the region enabling non destructive on site analyses in contexts where the export of artefacts is often difficult if not impossible the ability to rapidly process large assemblages also has major implications for generating data sets of sufficient resolution to transform archaeological interpretation

climatology of high cloud dynamics using profiling arm doppler radar observations abstractice cloud properties are influenced by cloud scale vertical air motion dynamical properties of ice clouds can be determined via doppler measurements from ground based profiling cloud radars here the decomposition of the doppler velocities into reflectivity weighted particle velocity vt and vertical air motion w is described the methodology is applied to high clouds observations from 35 ghz profiling millimeter wavelength radars at the atmospheric radiation measurement program arm southern great plains sgp climate research facility in oklahoma january 1997 december 2010 and the arm tropical western pacific twp site in manus july 1999 december 2010 the doppler velocity measurements are used to detect gravity waves gw whose correlation with high cloud macrophysical properties is investigated cloud turbulence is studied in the absence and presence of gw high clouds are less turbulent when gw are observed probability density functions of vt w and high cloud macrophysical propert

occurrence and origin of marialitic scapolite in the humboldt lopolith n w nevada the occurrence and origin of marialitic scapolite in the humboldt lopolith was investigated in the field and in the laboratory using petrographic and experimental techniques scapolite occurs in three modes as a pervasive replacement of plagioclase and other minerals in gabbro diorite and extrusive rocks as a poikiloblastic mineral in scapolitite dikes and as a fracture filling mineral with analcime albite and sphene in scapolite veins additional secondary minerals associated with scapolite include epidote prehnite hornblende and diopside salite clinopyroxene relations with these minerals suggest that most marialitic scapolite grew at temperatures around 400 c scapolite composition varies from eqan12 to eqan37 containing from 72 to 96 atomic cl in the r position experiments on systems of similar compositions indicate that nacl h2o fluid having more than 40 mol nacl is needed to stabilize the scapolite

halogen rich scapolite and biotite implications for metamorphic fluid rock interaction abundant cl rich scapolite and biotite indicate high cl activities during greenschistthrough amphibolite facies regional metamorphism of metasedimentary rocks northwest of the idaho batholith biotite zone granofels contain up to 40 modal percent cl rich scapolite the strict stratigraphic control on the occurrence ofscapolite and the fine scale interlayering of cl rich and cl poor metasedimentary rocks suggest that scapolite was formed during regional metamorphism by reaction of plagioclase with calcite and halite mass balance constraints on the formation of scapolite show that prior to metamorphism sedimentary units containing l0 modal percent halite along restricted sedimentary horizons 0 5 to 20 cm thick would have been sufficient to form the most scapolite rich layers the abundance ofcl rich phases decreases abruptly with the appearance ofzoisite bearing assemblages in the metasedimentary rocks suggesting infiltration of low cl hro at higher grades scapolite compositions range from 32 to 62 equivalent anorthite eqan and 0 7 6 to 0 06 xo there is a general increase in eqan and decrease in x with increasing metamorphic grade however local variations in scapolite composition suggest hat metamorphic fluid compositions were heterogeneous and internally bufered biotites coexisting with scapolite contain up to 0 51 wto o cl biotite grade and 2 58 wto o f kyanite sillimanite grade biotite compositions indicate significant differences inlogffir fr values of fluids in equilibrium with low grade biotiteand carbonate rich granofels differences in the inferred metamorphic fluid compositions are observed in some cases down t o a s c a l e o f l c m cl is strongly partitioned into an aqueous fluid relative to solid phases and is removed by metamorphic devolatilization and infiltration by dilute fluids therefore the occurrence of bufered activity gradients in cl as indicated by scapolite and biotite compositions suggests that metamorphic fluid flow was highly channelized and aqueous fluid rock interaction was limited high and variable cl activities were not smoothed out by aqueous fluid rock interaction through two regional metamorphic events

lithium and strontium isotopic systematics of waters around ontake volcano japan implications for deep seated fluids and earthquake swarms abstract since 1976 earthquake swarms have occurred beneath the southeast flank of ontake volcano in central japan electrical conductivity surveys have shown that these earthquake swarms are associated with the upwelling of deep seated fluid to investigate the nature of the deep seated fluid we analyzed 7 li 6 li and 87 sr 86 sr ratios of water samples collected from springs and wells around ontake volcano in 2000 2003 2005 2007 and 2009 the li and sr isotopic compositions of these water samples are largely explained by binary component mixing between near surface meteoric water and non surface fluid at each sampling site on the basis of their cl li and cl sr ratios we singled out water samples whose li and sr isotopic ratios were minimally affected by meteoric water contamination to represent non surface fluids the li and sr isotopic compositions of most ontake non surface fluids except for samples from the earthquake swarm region can be explained as the result of volcanic fluids reacting with basement rocks where they acquired upper crustal signatures we attribute the fluid associated with the region of earthquake swarms to the lower crust beneath the study area

magmatic co 2 and saline melts from the sybille monzosyenite laramie anorthosite complex wyoming there are three populations of fluid inclusions in quartz from the sybille monzosyenite early co2 secondary co2 and rare secondary brines the oldest consist of low density co2 0 70 inclusions that appear to be co magmatic the densities of these inclusions are consistent with the inferred crystallization conditions of the sybille monzosyenite namely 3 kilobars and 950 1000 c the other types of inclusions are secondary they contain co2 0 50 and secondary brine inclusions that form trains radiating out from a decrepitated inclusion the sites of these decrepitated inclusions are now marked by irregularly shaped fluid inclusions and solid inclusions of salt and carbonate rather than fluid inclusions feldspar contain abundant solid inclusions these consist of magmatic minerals hedenbergite hornblende ilmenite apatite and graphite intimately associated with k na chlorides we interpret these relations as follows the sybille monzosyenite formed from a magma that contained immiscible droplets of a halide rich melt along with a co2 vapor phase the salt was trapped along with the other obvious magmatic minerals during growth of the feldspars co2 may have also been included in the feldspars but it probably leaked later during exsolution of the feldspars and was not preserved both the saline melt and the co2 vapor were trapped in the quartz the melt inclusions in the quartz later decrepitated perhaps due to progressive exsolution of fluids to produce the secondary h2o and co2 inclusions these observations indicate that the sybille monzosyenite which is a markedly anhydrous rock was actually vapor saturated rather than being h2o however the vapor was co2 rich and possibly related to an immiscible chloride rich melt

chlorine isotopes in fluid inclusions determination of the origins of salinity in magmatic fluids abstract thermal ionisation mass spectrometry tims of the cs 2 cl ion has been used to determine the 37 cl value of paleofluids trapped in fluid inclusions modifications to the existing published method have lowered the precision by a factor of 2 0 09 1 thereby allowing real differences to be measured with greater certainty the method has been applied to determine 37 cl of two sets of magmatic fluids trapped in fluid inclusions samples were studied from the capitan pluton in new mexico and the sw england batholith both of which have high temperature fluids whose d and 18 o signatures are distinctly magmatic relative to standard mean ocean chloride smoc the 37 cl values of the capitan samples cluster around 0 whereas those from sw england cluster around 1 8 the br cl ratios of the capitan fluid inclusions are low indicative of halite dissolution and are comparable to local high salinity waters derived from leaching permian evaporites the br cl ratios of the sw england fluid inclusions are much higher and within the range of values normally considered to be magmatic we conclude that the 37 cl value of the capitan magmatic fluids confirms the evidence from br cl ratios that cl was derived from an evaporite source whereas the 37 cl value of the sw england fluids appears to be more representative of a deep magmatic source

composition of fluids in the lower crust inferred from metamorphic salt in lower crustal rocks knowledge of the rheological properties of the lower crust and the metamorphic processes that operate there is important for our understanding of orogenic processes and granite genesis the rheological properties critically depend on whether fluids are present in the lower crust1 2 and if present on their composition3 4 5 6 fluid inclusion7 8 9 and phase equilibria4 10 studies of lower crustal granulites have shown that fluids with low water activities due to the presence of dissolved components such as ch4 n2 co co2 and chlorides 11 are present at least episodically in the lower crust here we report the occurrence of a solid salt solution nacl kcl found together with chlorine rich amphibole and biotite in lower crustal granulites a desiccation mechanism explains how salt and chlorine rich minerals formed from an originally water rich fluid through a short lived series of hydration reactions in the granulites during which chlorine was progressively enriched in the fluid consequently it would appear that fluid was present in the lower crust in only small amounts and was not stable over geologically long periods of time leading to the conclusion that the lower crust is devoid of a free fluid phase during most of its history

behaviour of major elements and some trace elements li rb cs sr fe mn w f in deep hot waters from granitic areas abstract analyses of selected hot springs in more than sixty areas in granites from europe are presented concentrations of major elements and of some trace elements li rb cs sr fe mn w f in high ph waters are not significantly affected by processes during uprise from the deep reservoir to the surface re equilibrations mixing with surficial waters normalized to k or na concentrations of all other elements are related to the aquifer temperature the knowledge of aquifer temperature and total electric charge of mobile elements cl s possibly f allows us to predict both major elements within 50 and trace elements within a factor 2 or 3 concentrations in alkaline waters from granites

non destructive pxrf analysis of museum curated obsidian from the near east abstract non destructive pxrf has the potential to expand sample populations of archaeological provenancing studies by facilitating access to museum collections of artefacts in this study we use museum curated obsidian for the sites of tell brak mersin yumuktepe and tell arpachiyah and geological obsidian samples from central turkey to demonstrate that non destructive pxrf is comparable to other techniques in differentiating between near eastern obsidian sources secondly we use multivariate analysis to evaluate whether non destructive pxrf is sufficiently accurate and precise to enable comparison with legacy datasets from previous analysis using pixe and icp ms multivariate analyses show that instrumental offsets between the results from pxrf and other analytic techniques are less than source to source variation typical for most anatolian obsidian outcrops and pxrf identified geochemical groups are directly comparable to legacy datasets non destructive pxrf analysis indicates that during the chalcolithic east gollu dag and nenezi dag continued to be the major sources of obsidian to communities in central anatolia and the bingol range and mountains surrounding lake van supplied sites east of the levant variations in the analysed assemblages suggest a number of obsidian exchange networks existed during this period

cloud radar doppler spectra in drizzling stratiform clouds 2 observations and microphysical modeling of drizzle evolution sites is presented the evolution of the doppler spectra moments is consistent with the onset and growth of drizzle particles and can be used to assist modeling studies of drizzle onset and growth time height radar observations are used to exhibit the coherency of the doppler spectra shape parameters and demonstrate their potential to improve the interpretation and use of radar observations in addition a simplified microphysical approach to modeling the vertical evolution of the drizzle particle size distribution in warm stratiform clouds is described and used to analyze the observations the formation rate of embryonic drizzle droplets due to the autoconversion process is not calculated explicitly however accretion and evaporation processes are explicitly modeled the microphysical model is used as input to a radar doppler spectrum forward model and synthetic radar doppler spectra moments are generated three areas of interest are studied in detail early drizzle growth near the cloud top growth by accretion of the well developed drizzle and drizzle depletion below the cloud base due to evaporation the modeling results are in good agreement with the continental and maritime observations this demonstrates that steady state one dimensional explicit microphysical models coupled with a forward model and comprehensive radar doppler spectra observations offer a powerful method to explore the vertical evolution of the drizzle particle size distribution

chemistry isotope values δd δ18o δ34sso4 and temperatures of the water inflows in two gotthard tunnels swiss alps water inflows in the gotthard highway tunnel and in the gotthard exploration tunnel are meteoric waters infiltrating at different elevations on both sides of an important orographic divide limited interaction of meteoric waters with gneissic rocks produces ca hco3 and na ca hco3 waters whereas prolonged interaction of meteoric waters with the same rocks generates na hco3 to na so4 waters waters circulating in triassic carbonate evaporite rocks have a ca so4 composition calcium na so4 waters are also present they can be produced through interaction of either na hco3 waters with anhydrite or ca so4 waters with a local gneissic rock as suggested by reaction path modeling an analogous simulation indicates that na hco3 waters are generated through interaction of ca hco3 waters with a local gneissic rock the two main so4 sources present in the alps are leaching of upper triassic sulfate minerals and oxidative dissolution of sulfide minerals of crystalline rocks values of 34sso4 9 are controlled either by bacterial so4 reduction or leaching of upper triassic sulfate minerals most waters have temperatures similar to the expected values for a geothermal gradient of 22 c km and are close to thermal equilibrium with rocks however relatively large descending flows of cold waters and ascending flows of warm waters are present in both tunnels and determine substantial cooling and heating respectively of the interacting rocks the most import upflow zone of warm na rich waters is below guspisbach in the gotthard highway tunnel at 6 2 9 0 km from the southern portal these warm waters have equilibrium temperatures of 65 75 c and therefore constitute an important low enthalpy geothermal resource

metamorphic fluids in the deep crust evidence from the adirondacks unusual mineral assemblages of tremolitic hornblende diopside enstatite quartz have been examined to estimate the temperature t and water fugacity at the time of the granulite fades metamorphism in the adirondacks the pyroxenes are closely represented by the system cao mgo sio2 allowing application of experimental data1 with only small corrections for reduced values of activities tremolite equilibria2 buffered log 3 0 0 1 equivalent to 0 9 kbar of water pressure at 7 kbar 710 c nearby marbles contain wollastonite calcite quartz and buffered 1 1 kbar consistent with 5 9 kbar inferred local gradients in fluid compositions suggest that deep crustal fluid conditions are complex and heterogeneous indicating that fluid movements whether of mantle3 or deep crustal origin are channelized rather than pervasive thus some granulite facies rocks were wholly or partly closed systems with respect to externally derived fluids permitting localized buffering of fluid compositions recognition of restricted fluid mixing limits theories that call for massive amounts of pervasive fluid flow to facilitate melting cause metasomatism or to stabilize granulite facies mineralogy

high salinity fluids the result of retrograde metamorphism in thrust zones abstract highly saline fluid inclusions in vein quartz from caledonian thrust zones of northern norway are associated with late orogenic retrograde metamorphic reactions several retrograde reactions have been observed in pelitic lithologies and all involve the rehydration of earlier higher grade metamorphic assemblages the most common products of these reactions are chlorite and sericite which have formed at the expense of garnet kyanite staurolite and hornblende chlorite geothermometry suggests temperatures between 330 and 370 c for the formation of the retrograde chlorite a range of total fluid salinities has been determined by microthermometry between 27 and 50 wt these high fluid salinities result from relatively rapid rehydration reactions during limited infiltration of the thrust zones by aqueous fluids crush leach analyses show the fluids to be multi component fluids whose electrolyte contents are na and cl dominated but with appreciable contents of ca k fe and sr geochemical modelling of the fluid compositions suggests that the concentrations of the major elements in solution were buffered by the retrograde rehydration reactions the source of the infiltrating fluids which caused the retrogression is not identifiable from their major element chemistry surface derived meteoric sea or sedimentary formation waters fluids may have utilised pre existing thrust zones as fluid pathways and are considered to have been important in the retrogression in the structurally higher parts of the caledonian allochthon at deeper levels however metamorphic fluids produced by devolatilisation reactions in underthrust units may have migrated upwards into the thrust zones and resulted in the retrogression of the hangingwalls of overlying higher grade nappes

halogen geochemistry of fluid during amphibolite granulite metamorphism as indicated by apatite and hydrous silicates in basic rocks from the bamble sector south norway abstract the halogen chemistry of apatites biotites amphiboles and titanites from metabasites in the proterozoic bamble sector amphibolite granulite facies transition zone norway has been studied to gather data on the behaviour of halogens during original magmatism and subsequent metamorphism three groups of apatites could be recognized 1 f oh apatites with more than 50 mole f and virtually no cl 2 f oh apatites with up to 15 mole of cl 3 cl rich apatites with up to 6 73 wt cl the latter are the most cl rich metamorphic apatites ever reported the f contents of coexisting biotite do not follow this division but their cl contents do log z sfnc hf z sfnc h 2 o values for the coexisting fluid phase calculated from biotite are slightly lower than those calculated from apatite log z sfnc hcl z sfnc h 2 o values in the coexisting fluid phase calculated from biotite are substantially higher than those calculated from apatite the log z sfnc hf z sfnc h 2 o reflects the composition of the peak metamorphic fluid phase the apatites show three types of patterns of f contents 1 w shaped 2 rimward increasing and 3 rimward decreasing pattern 2 reflects progressive metamorphism pattern 3 is thought to reflect growth starting near peak metamorphism and going on during retrograde dilution of the peak metamorphic fluid by a newly introduced aqueous one some apatites show local resorption effects along cracks no regional trend in calculated log z sfnc hf z sfnc h 2 o values is present as different from other granulite terrains the bamble biotites and amphiboles from granulite facies samples do not have higher halogen contents as those from the amphibolite facies area the samples show that halogen bearing fluids were controlled at a very restricted scale during peak as well as retrograde metamorphism

terminal fall velocity and the fastex cyclones knowledge of water drop and ice crystal terminal velocities is particularly important for an adequate representation of particle sedimentation in cloud resolving and large scale models in this paper a new method is proposed to retrieve terminal fall velocity from airborne doppler radar observations to extract the terminal fall velocity from the doppler information which mixes the three wind components and the terminal fall velocity statistical considerations are introduced stating that for a long sampling time span a whole aircraft mission for instance and for moderate storms such as stratiform precipitation the mean vertical air motions should vanish with respect to the mean terminal fall velocity statistical power law relationships between terminal fall speed and radar reflectivity are then developed as well as profiles of mean terminal fall velocity this underlying hypothesis of the method is validated with in situ measurements of the vertical wind component averages of convective scale retrievals of the vertical wind component and terminal fall speed radar reflectivity vt z relationships derived from in situ measurements of the drop size distribution these comparisons all indicate that the vertical air motion can indeed be neglected with respect to the terminal fall speed a detailed analysis of the statistical relationships obtained in liquid and ice phases for six frontal cyclones at different stages of development shows that a universal vt z rain relationship can be proposed for north atlantic frontal cyclones at mature stage this result and further arguments developed in the paper suggest that the drop size distributions are equilibrium distributions in the ice phase such a universal relationship is not found it is nevertheless suggested in this study that such a general relationship might be derived if the frontal cyclones are split into categories depending on their stage of development these vt z universal relationships can be introduced in large scale model parametrization schemes in order to better describe the sedimentation of ice and water and dynamical microphysical interactions occurring within north atlantic frontal cyclones finally a procedure is proposed to estimate the most representative type of ice particle from 2d p in situ sensor and airborne doppler radar measurements it consists of calculating the mean flight level z and the vt z relationships in the ice phase for several theoretical ice habits and to identify the ice habit that reasonably reproduces both the radar derived mean flight level z and vt z ice relationship copyright 2003 royal meteorological society

mantle derived fluids in the basement of the deccan trap evidence from stable carbon and oxygen isotopes of carbonates from the killari borehole basement maharashtra india we report here for the first time geochemical mineralogical and stable carbon and oxygen isotopic data on the crystalline basement rocks of the 1993 killari earthquake region of maharashtra india which is covered by a thick suite of deccan volcanics our results revealed the hitherto unknown amphibolite granulite nature of the 2 5 ga basement which contains 2 00 2 28 wt of co2 the stable carbon 13c and oxygen 18o isotopic measurements on carbonates separated from two basement samples kil 13 440 5 m depth and kil 20 499 6 m depth collected from the klr 1 borehole drilled in the epicentral region showed the respective values of 6 23 and 6 22 versus pdb for 13c and 7 94 and 8 11 versus smow for 18o the samples plot in the primary igneous carbonatite field indicating the mantle origin of the carbonates derived through the process of mantle metasomatism from the deep mantle carbon reservoir this would suggest large scale crust mantle thermal fluid interaction beneath the killari seismogenic region which is characterized by massive upwarping of the high velocity mafic crust and retrograde metamorphism

internal differentiation of the archean continental crust fluid controlled partial melting of granulites and ttg amphibolite associations in central finland fault bound blocks of granulite and enderbite occur within upper amphibolite facies migmatitic tonalitic trondhjemitic granodioritic ttg gneisses of the iisalmi block of central finland these units record reworking and partial melting of different levels of the archean crust during a major tectonothermal event at 2 6 2 7 ga anhydrous mineral assemblages and tonalitic melts in the granulites formed as a result of hydrous phase breakdown melting reactions involving amphibole at peak metamorphic conditions of 8 11 kbar and 750 900 c a nominally fluid absent melting regime in the granulites is supported by the presence of carbonic fluid inclusions the geochemical signature of light rare earth element lree depleted mafic granulites can be modelled by 10 30 wt partial melting of an amphibolite source rock leaving a garnet bearing residue the degree of melting in intermediate granulites is inferred to be less than 10 wt and was restricted by the availability of quartz pressure temperature estimates for the ttg gneisses are significantly lower than for the granulites at 660 770 c and 5 6 kbar based on the p t conditions melting of the ttg gneisses is inferred to have occurred at the wet solidus in the presence of an h 2 o rich fluid a hydrous mineralogy abundant aqueous fluid inclusions and the absence of carbonic inclusions in the gneisses are in accordance with a water fluxed melting regime low ree contents and strong positive eu anomalies in most leucosomes irrespective of the host rock composition suggest that the leucosomes are not melt compositions but represent plagioclase quartz assemblages that crystallized early from felsic melts furthermore similar plagioclase compositions in leucosomes and adjacent mesosomes are not a migmatite paradox as both record equilibration with the same melt phase percolating along grain boundaries

tem aem observations of cl rich amphibole and biotite and possible petrologic implications cl rich amphibole and biotite 2 9 and 2 8 wt cl respectively were analyzed with high resolution transmission electron microscopy hrtem selected area electron diffraction saed and x ray emission analytical electron microscopy aem the samples are from archean granulite facies metamorphosed iron formations located in the beartooth mountains montana u s a two types of amphibole and biotite were found 1 high cl prograde hastingsite and biotite and 2 retrograde amphibole of grunerite composition containing no detectable amount of cl but intergrown with submicrometer sized slabs ofci rich annite 2 8 wt fe rich talc fe rich clinojimthompsonite and very wide chain silicate tem aem study of prograde hastingsite and biotite suggests that cl is dissolved in the crystal structures and that cl distribution is homogeneous aem analyses show that cl occupies up to about 30 and 15 of the oh positions in hastingsite and biotite respectively calculations of the cl oh exchange reaction for apatite indicate a high 10g ahoo ah o ratio of about 1 8 2 2 suggesting equilibrium with a cl rich fluid speciation and solubility modeling of the equilibrium between an aqueous fluid and the cl rich apatite biotite and hastingsite suggest that reactions with a saline brine of about 25 wt naci could explain the cl enrichment in these hydrous phases whereas the brine may coexist with an immiscible c02 dominated vapor during the granulite facies metamorphism in light of low calculated h20 activities and c02 rich fluid inclusions this explanation is consistent with the results from studies of natural and synthetic fluid inclusions and phase equilibrium experiments reported in the literature the widespread occurrence of cl rich amphibole and biotite in granulite facies rocks thus has significant implications for the nature of high grade metamorphism tem aem observations of submicrometer sized inclusions of cl rich phases within retrograde amphibole may help to explain the commonly observed heterogeneities of electron microprobe cl analyses found in samples from a variety of geologic settings microprobe analyses using typical beam diameters may sample areas with different proportions of submicroscopic intergrowths this will give apparent cl heterogeneities and fortuitous correlations between cl and concentrations of k ai and si although compositional correlations sometimes indicate reciprocal effects that are likely important for amphibole we emphasize the potential danger of artifacts resulting from submicroscopic solid inclusions additional tem aem studies on complex samples are needed to explain the compositional heterogeneities with confidence

timing of paleozoic orogeny and extension in the continental shelf of north central norway as indicated by laser 40ar 39ar muscovite dating metamorphic rocks of lofoten norway represent a leading edge of the baltic craton that was partly subducted beneath laurentia during caledonian orogeny we find that muscovite porphyroblasts in lofoten record a remarkably complete history of cooling and unroofing and yield data about lofoten9s tectonic evolution in the interval from 425 to 265 ma these data confirm that culminating metamorphism of basement and allochthonous rocks in lofoten occurred during the scandian phase of orogeny permian ages for muscovite are the youngest obtained for regional metamorphic rocks anywhere in scandinavia and appear to record significant basement unroofing during extensional evolution of the norwegian greenland seaway regional age variations of muscovite in lofoten can be related to present crustal thickness devonian to permian sedimentation in the norwegian seaway and extensional structures and they indicate the timing of multiple extension events in the evolution of norway9s passive margin the results of this study show that 40 ar closure profiles in porphyroblasts can form even in active tectonic settings characterized by rapid and episodic unroofing

assessing the applicability of portable x ray fluorescence spectrometry for obsidian provenance research in the maya lowlands recent innovations in portable energy dispersive x ray fluorescence pxrf spectrometry have increased its utility for the geochemical characterization of obsidian artifacts for archaeological provenance research however concerns over the utility of pxrf instrumental analyses have been raised focused on the validity and reliability of the geochemical data produced here we adopt the framework of richard hughes on reliability validity and scale in obsidian sourcing research 1998 whereby reliability addresses instrument stability and issues of measurement while validity pertains to an instrument s ability to discern geochemical source provenance this is done in order to test the utility of pxrf instruments for archaeological provenance research k means cluster analysis was used to test the accuracy of pxrf through statistical comparison of data acquired via laboratory and portable energy dispersive xrf instruments multivariate analysis was employed to demonstrate obsidian source representation at two classic maya archaeological sites in southern belize uxbenka and ek xux and to test the validity of data obtained from a pxrf instrument in answering archaeological research questions pertaining to regional interactions between lowland maya polities results suggest that portable xrf instruments produce internally consistent results however data acquired from a pxrf instrument are not statistically equivalent to other xrf instruments this is to say that while pxrf is not a reliable technique it is valid for questions pertaining to geochemical source representation

hydrogeochemistry groundwater ages and sources of salts in a granitic batholith on the canadian shield southeastern manitoba abstract the hydrogeochemistry of the lac du bonnet granitic batholith has been determined for the region of the whiteshell research area wra in southeastern manitoba canada this work forms part of the geosciences studies performed for the canadian nuclear fuel waste management program over the period 1980 1995 by atomic energy of canada limited aecl knowledge of the variation of groundwater chemistry and its causes is useful in assessing the performance and safety of a nuclear fuel waste vault located at depths of up to 1000 m in a crystalline rock formation of the canadian shield groundwaters and matrix pore fluids have been obtained by standard sampling methods from shallow piezometers in clay rich overburden from packer isolated borehole zones intersecting fractures or fault zones in the bedrock and from boreholes in unfractured rock in aecl s underground research laboratory url eighty six individual fracture groundwaters have been sampled and analysed from permeable zones in 53 boreholes drilled to depths of up to 1000 m in the lac du bonnet batholith in addition 28 groundwaters from piezometers in a large wetland area near the url have been sampled and analysed to determine the influence of clay rich overburden on the bedrock hydrogeochemistry analyses have been made for major and minor ions ph eh trace metals and stable and radioactive isotopes to characterise these groundwaters and relate them to their hydrogeologic regimes shallow groundwaters in the fractured bedrock are generally dilute tds 500 m na ca cl so4 waters of increasing salinity up to 50 g l with depth are found and in some fractures the waters have evolved to a ca na cl composition isotopic data indicate that these waters are warm climate and pre glacial in origin with residence times of over 1 ma pore fluids observed to drain from the unfractured rock matrix in the url facility are almost pure ca cl in composition 90 g l salinity and have a 2h 18o composition displaced well to the left of the global meteoric water line about which all other wra groundwaters lie this information indicates that these pore fluids have undergone prolonged water rock interaction and have residence times of 101 103 ma most of the deeper fracture groundwaters and pore fluids have low br cl ratios and moderate to high 34s values of dissolved so4 which indicates that their salinity could be derived from a marine source such as the basinal sedimentary brines and evaporites to the west of the batholith these fluids may have entered the batholith during early paleozoic times when sedimentary rocks were deposited over the granite and were driven by a hydraulic gradient resulting from higher ground in western canada the hydrogeochemical data and interpretations show that below 500 m in the wra fracture hosted groundwaters are very saline reducing and old and are therefore indicative of stagnant conditions over the period of concern for nuclear waste disposal 1 ma the intact rock matrix at these depths is extremely impermeable as indicated by the presence of pore fluids with unusual geochemical and isotopic characteristics the pore fluids may represent basinal brines that have evolved geochemically and isotopically to their current composition over periods as long as 103 ma

mass transfer and porosity evolution during low temperature water rock interaction in gneisses of the simano nappe arvigo val calanca swiss alps late alpine fissures and fractures in amphibolite facies basement gneisses at arvigo val calanca swiss alps show distinct cm sized reaction selvages parallel to the fracture walls that composed of subgreenschist facies assemblages produced by the interaction of water present in the fracture porosity with the old high grade gneiss assemblages the process of selvage or reaction vein formation occurred in the brittle deformation regime and at temperatures characteristic of first the prehnite pumpellyite facies and then later of the zeolite facies the vein formation occurred during uplift and cooling at very late stages of the alpine orogeny the reaction veins are composed of a selvage of altered gneiss on both sides of the central fracture and a central zone with fissure minerals that have been growing in the open fracture pore space the central zone of the arvigo veins contains an early assemblage with epidote prehnite and chlorite and a late succession sequence of various species of zeolite the veins of the arvigo quarry are convincing evidence that fracture fluids in gneiss and granite have the potential to precipitate ca zeolite this is an important find because many fluids recovered from deep continental drill holes and from geothermal energy exploration are found to be oversaturated in respect to a number of ca zeolite species vein formation during late uplift and cooling of the alps occurred at continuously decreasing t and at hydrostatic pressure 1 coexisting prehnite epidote records temperatures of 330 380 c 2 chlorite formation at temperature of 333 32 c and 3 formation of zeolites 250 c in the selvages the prime reaction is the replacement of plagioclase by albite along a sharp reaction front that separates the selvage from unaltered gneiss in addition to albitisation chloritisation of biotite is the second important reaction in the alteration process the reactions release components for the formation of ca al silicates the water rock interaction is associated with a depletion of al si ca fe and k in the altered wall rock the overall reaction is associated with an increase in porosity of up to 14 2 2 2 in the selvage zone altered wall rock caused by the volume decrease during albitisation and the removal of biotite the propagation of the sharp reaction front through the gneiss matrix occurred via a dissolution reprecipitation mechanism zeolite formation is tied to the plagioclase alteration reaction in the rock matrix which releases components for zeolite formation to a co2 poor aqueous liquid

validity of off the shelf handheld portable xrf for sourcing near eastern obsidian chip debris handheld portable xrf hhpxrf has received considerable recent attention in archaeology especially for obsidian sourcing published studies largely suggest a high potential for success hhpxrf though has been met with debate and scepticism concerns fall into three categories 1 low accuracy and precision 2 data correction schemes and calibration and 3 ignorance of fundamental xrf issues such as specimen size limits and morphology effects the result is that archaeological interpretations in hhpxrf based studies are cast into doubt should interpretations be believed if authors did not follow the perceived best practices to address such questions the validity of hhpxrf for near eastern obsidian sourcing was tested under deliberately sub optimal conditions irregular obsidian debitage near the minimum size limits was sourced with a success rate of 94 based on a rank matches to 100 based on a and b rank matches even under conditions chosen to mimic off the shelf operation

chlorine titanium and barium rich biotites factors controlling biotite composition and the implications for garnet biotite geothermometry barium cl and ti rich biotite occurs together with garnet plagioclase and amphibole within narrow shear zones in 1800 ma old noritic granulites in the flakstadoy basic complex lofoten north norway the granulite facies assemblage plagioclase clinopyroxene orthopyroxene biotite and ilmenite was replaced by an amphibolite facies mineral assemblage including ba cl and ti rich biotite during ductile deformation biotite shows complex compositional variations with respect to the contents of ba k cl ti al fe mg and si there are correlations between si aliv k ba and cl and between alvi and ti titanium and cl are uncorrelated the fe and mg are correlated to both cl and ti multivariate analysis shows that most of the compositional variation of biotite can be described by two exchange reactions this indicates that most of the variation in biotite composition was controlled by two chemical variables of the system the content of the first exchange component ti1 0 fe0 6 al 1 1 vi mg 0 8 in biotite can be related to the original distribution of ti bearing minerals in the igneous protolith the content of the second exchange component al 0 4 iv fe0 8 ba0 5 cl1 0 si 0 4 mg 1 0 k 0 5 oh 1 0 is related to compositional variations of an externally derived ba and cl bearing fluid in equilibrium with biotite the initially low cl content of the externally derived fluid was increasing during bioite forming reactions because oh was preferentially incorporated relative to cl into biotite continued hydration chloridisation reactions resulted in a gradual consumption of the free fluid phase resulting in local fluid absent conditions the composition of biotite reflects the composition of the last fluid in equilibrium with the mineral i e the composition of the fluid immediately before the grain boundaries were fluid undersaturated thus the variations in biotite composition reflect how the fluid was gradually consumed throughout the shear zone rock the correlations between fe mg ba k and cl can be attributed to differences between the structure of the crystal lattices and the sizes of the cation sites of oh phlogopite and cl annite the dependency of the fe mg ratios of biotite on the cl and ti content has a strong effect on the fe mg partitioning between biotite and garnet the relationship between lnkd x ti bt and x cl bt can be expressed by the regression equation lnk d 1 82 2 60x ti bt 5 67x cl bt

halogens in water from the crystalline basement of the gotthard rail base tunnel central alps abstract drilling of the new gotthard rail base tunnel central alps opened a large number of water conducting fractures in granite and gneiss of the crystalline basement the overburden reaches locally more than 2000 m and water and rock temperature is up to 45 c the tunnel crosses a series of steeply dipping fractured rock units that also crop out at the surface above the tunnel recharge water enters the fractured rocks in the high mountainous area migrates gravity driven to the sampling locality in the tunnel along its flow path it reacts with rocks exposed on the fractures where it dissolves the principal granite minerals resulting in high ph na 2 co 3 waters the tunnel waters contain unusually high concentrations of fluoride ranging from 5 to 29 mg l alteration of f bearing biotite to f free chlorite is one of the sources of fluorine the highest f concentrations result from the equilibration of low ca waters with fluorite fluoride concentration is strongly lithology dependent and sharp discontinuities in both concentration and saturation state with respect to fluorite occur at the contacts of the different gneiss and granite slabs chloride concentrations vary between 1 and 1300 mg l in contrast the cl br mass ratio exhibits small variations and centers around 110 suggesting a common source for the cl and br which is independent of the lithology in the northern part of the tunnel cl and br are chiefly derived from saline pore fluids of one lithology which is then mixed with low salinity water along flow paths cl br ratios of the waters in the southern part of the tunnel section are similar to those measured in experimental leachates from different tunnel rocks suggesting that leaching of metamorphic fluids in the pore space is the main source of both cl and br

proterozoic eclogites from the lofoten islands northern norway abstract massif lenses and bands of variably retrogressed eclogites occur within the granulite facies proterozoic basement of the lofoten islands in northern norway eclogites are often related to shear and mylonite zones suggesting that deformation and fluid access was important for their formation the eclogitic rocks are restricted to gabbroic or troctolitic rock compositions and show in the least retrogressed samples the typical assemblage garnet omphacite rutile the widespread occurrence of eclogite shows that the whole group of the lofoten islands was affected by high pressure metamorphism eclogites were found on three of the five major islands so far flakstadoy vestvagoy austvagoy thermobarometry reveals minimum conditions during eclogite formation of 680 c 15 kbar on flakstadoy and 540 c 14 kbar on austvagoy geological petrological and geochemical data suggest the following succession of events a intrusion of mafic to mangeritic magmas at about 1 8 ga griffin et al 1978 b incomplete recrystallization under high pressure granulite facies conditions associated with granulitization was the formation of cl rich hydrosilicates granulite formation was incomplete except for zones of intensive deformation c eclogites formed in response to a significant pressure increase in the same high strain zones however scattered eclogite lenses and boudins also occur in gneisses d post eclogite retrogression occurred under middle to high pressure amphibolite facies conditions probably the leknes event at 1 1 ga of griffin et al 1978 eclogite formation was related to crustal thickening during the final stages of early proterozoic magmatism and granulite facies metamorphism

on using the relationship between doppler velocity and radar reflectivity to identify microphysical processes in midlatitudinal ice clouds 1 ground based 35 ghz profiling doppler cloud radar observations of ice clouds were used to derive the power law relation between doppler velocity vd and radar reflectivity z vd azb by removing the vertical air motion from vd the power law can be rewritten as vt azb with vt being the reflectivity weighted particle terminal fall velocity profiles of this relation are variable with height an attempt was made to relate this variability to the dominant microphysical processes in different layers of the cloud based on that the possibility of using profiles of the parameters a and b to distinguish different microphysical regimes was explored the methodology was applied to long term measurements january 1997 to december 2010 at the atmospheric radiation measurement site in the southern great plains principal component analysis was used to determine the modes of the profiles that explain most of the observed variance in the observations profile averaged means and standard deviations of parameters a and b amounted to 0 65 0 42 and 0 03 0 19 respectively furthermore three commonly used microphysical relations related to bulk quantities were used to determine values of a and b these results were found to compare reasonably well with the values obtained from the radar observations finally microphysical considerations showed that radar derived values of parameter b can be explained in terms of particle size distribution moment changes

a new petrogenetic grid for low grade metabasites abstract we have used internally consistent thermodynamic data to present calculated phase equilibria for the system na2o cao mgo al2o3 sio2 h2o ncmash in the range 0 500 c and 0 1 10 kbar involving the phases anorthite glaucophane grossular heulandite jadeite laumontite lawsonite paragonite prehnite pumpellyite stilbite tremolite wairakite zoisite with excess albite clinochlore quartz and pure water average activity terms derived from published mineral chemical data were included for clinochlore glaucophane prehnite pumpellyite tremolite and zoisite the new petrogenetic grid delineates stability fields and parageneses of common index minerals in zeolite prehniteactinolite prehnite pumpellyite pumpellyite actinolite blueschist and greenschist facies metabasites the stability fields of mineral assemblages containing prehnite pumpellyite epidote actinolite albite chlorite quartz were analysed in some detail using activity data calculated from five specific samples for example the prehnite actinolite facies covers a p t field ranging from about 220 to 320 c at pressures below 4 5 kbar the transition from the prehnite actinolite and pumpellyite actinolite to greenschist facies occurs at about 250 300 c at 1 3 kbar and at about 250 350 c at 3 8 kbar p t fields of individual facies overlap considerably due to variations in chemical composition

new investigations of the golludag obsidian lava flows system a multi disciplinary approach abstract the golludag obsidian lava flow system is relatively complex more than ten different obsidian outcrops and knapping workshops have been identified around this volcano their importance for long and short distances obsidian supply has already been demonstrated one of the main problem encountered when studying the golludag obsidian flows is the great chemical similarity of some of them the use of the geochemical approach to solve the problems of obsidian trade around the golludag is therefore insufficient a multi disciplinary program joining archaeology geochemistry and geomorphology was thus started to understand the relationships between the different obsidian flows and to draw the pattern of the golludag obsidian trade our archaeological and geomorphologic approach will help us to understand which obsidian outcrops were available during the palaeolithic and neolithic periods also our geomorphologic approach linked to intensive geochemical analyses will help us to understand the spatial variability of the geochemistry of the obsidian outcrops lithic technology will also give information about the different knapping methods used at the workshops

tourmaline bearing rocks in the singhbhum shear zone eastern india evidence of boron infiltration during regional metamorphism frozen in reaction textures combined with mineral chemistry of tourmaline bearing metamorphic assemblages provide valuable information about fluid rock interaction during orogenesis tourmaline occurs in four distinct mineralogical associations in the singhbhum shear zone ssz of the precambrian east indian craton the tourmaline bearing rocks are associated intimately with pelitic to psammopelitic and quartzofeldspasthic rocks including meta granite the rocks were affected by two sets of folding f1 and f2 and ductile shearing associated with f1 during ca 1 6 1 8 ga tectonic activity in this belt quantitative geothermobarometry and the stability relations of the metamorphic assemblages developed in the pelitic rocks establish the presence of two episodes of metamorphism a prograde m1 event that culminated at 480 40 c 6 4 0 4 kbar and an m2 event that caused retrogression of the m1 assemblages field and petrographic observations in combination with data on chemical composition of tourmaline indicate three stages of tourmaline growth the earliest stage is represented by pretectonic pre metamorphic greenish yellow tourmaline cores in the tourmalinite from the surda area association a the textural relations demonstrate that in the second stage greenish yellow cores of oscillatory zoned tourmaline in the metagranite albite quartz biotite chlorite muscovite apatite magnetite association c very fine tourmaline grains in muscovite schist muscovite quartz association b and greenish yellow cores of tourmaline in biotite muscovite schist biotite muscovite magnetite chlorite apatite quartz association d crystallized during the f1 m1 events post tectonic greenish blue tourmaline belonging to the third stage replaces the earlier tourmaline grains along their margins and cracks compositionally tourmalines of all four associations fall in the alkali group most of the data fall in the dravite field with a few analyses straddling the boundary between schorl and dravite an abrupt compositional change was noted across the different color zones in the tourmaline grains this change is explained by one or more of the coupled substitutions al nar 1 car naal 1 and mg fe 1 where r mg fe2 mn integrating the field petrographic and phase compositional data it has been demonstrated that tourmaline growth in the second and third stages was induced by infiltration driven b metasomatism during prograde metamorphism of the rocks deep seated magma was the source of the b bearing hydrothermal fluid

the effect of temperature and cataclastic deformation on the composition of upper crustal fluids an experimental approach abstract we investigated the potential of common crystalline rocks to facilitate the geochemical evolution of continental basement brines and to serve as a metal source for hydrothermal ore deposits we performed leaching experiments on typical crystalline basement rocks granite and gneiss a redbed sandstone and their mineral separates feldspar quartz and biotite at variable t 25 180 275 and 350 c p ambient pressure 0 9 1 4 and 1 9 kbar grain size fractions the modification of the fluid chemistry during water rock interaction strongly depends on grain size leachates using pure h 2 o of fine grained rock powders have lower na cl and cl br ratios but much higher chlorinities by a factor of up to 40 compared to leachates from coarse grained rock powders the cl br ratios of all leachates are lower than that of their respective whole rocks smaller grain sizes of the starting materials yield element ratios cl br and na cl similar to those found in natural fluids emphasizing the influence of cataclastic deformation on the fluid chemistry of crustal fluids during our leaching experiments pb zn cu and w are released by felsic minerals while biotite alteration releases ni as and additional zn and cu our experiments confirm that crystalline rocks may serve as metal source for hydrothermal ore deposits short term water rock interactions along cataclastic fault zones in the brittle crust may influence the geochemical evolution of upper crustal fluids this is further suggested by low f cl and cl br ratios in some of the leachates being very similar to halogen systematics in natural fluid samples

timing of low temperature mineral formation during exhumation and cooling in the central alps switzerland abstract construction of the new gotthard rail base tunnel through the central alps provided a truly unique sample of a fissure assemblage formed during exhumation and cooling of the central alps the base of the tunnel is at 500 m a s l and the overburden at the sampling locality amounts to 2000 m the fissure assemblage apophyllite kf laumontite and quartz occurs within the southern aar granite it formed during exhumation and erosion of the alpine orogen apophyllite and laumontite mark very late fissure minerals in the central swiss alps only followed by stilbite hematite and calcite the data from a combined study of 40 ar 39 ar age dating of apophyllite apatite fission track analysis and the petrology of rock samples from tunnel and the from the mountains above the tunnel reflect the late stages of an aging orogen apatite fission track analysis yields an exhumation rate of 0 46 mm yr a cooling rate of 12 3 c m y and a geothermal gradient of 27 c km at the time of apophyllite formation combining these data with the 40 ar 39 ar plateau age of 2 ma for the formation of apophyllite a minimum formation temperature and depth of 68 c at 2550 m below the present day erosion surface follow at this time the position of the sample location was 550 m below the tunnel level assemblage stabilities and computed temperature time evolution of fissures in the aar massif indicate that laumontite formed between 11 and 2 ma ago at temperatures between 180 and 70 c chemical components for forming laumontite were provided from dissolution of minerals of the alpine greenschist facies variscan granitoid rocks of the aar massif basement systematic variations in the composition of laumontite are an effect of decreasing temperature