formation and age of sphalerite mineralization in carbonate rocks of bajocian age in the swiss jura mountains evidence of mesozoic hydrothermal activity a combination of petrographic and geochemical techniques was applied to better constrain the origin and evolution of the fluid systems responsible for the formation of disseminated cd rich up to 0 6 wt sphalerite zns mineralization in the northeastern part of the jura mountains switzerland the rb sr ages of sphalerite samples indicate that a main phase of sphalerite formation occurred near the boundary between the late middle and early late jurassic at around 162 ma the negative 34s values 22 3 to 5 3 suggest that biogenic sulfide sulfur was involved in zns precipitation the strontium isotope composition is more radiogenic than that of contemporaneous seawater reflecting the interaction of mineralizing fluids with silicate rocks lead isotope signatures are very uniform 206pb 204pb 18 63 18 67 207pb 204pb 15 63 15 64 208pb 204pb 38 51 38 63 indicating an isotopically well homogenized fluid system the basement rocks underlying the jurassic strata are considered to be the main source of metals for the sphalerite mineralization the migration of deep sourced hydrothermal saline metal bearing fluids into the bajocian host carbonates containing sedimentary reduced sulfur resulted in the precipitation of sulfides the period of sphalerite formation near the middle late jurassic boundary is characterized by enhanced tectonic and hydrothermal activity in europe related to the opening of the central atlantic and tectonic thermal subsidence during spreading of the alpine tethys our study provides evidence that the bajocian carbonate rocks in the jura mountains area were affected by the circulation of deep sourced metal bearing hydrothermal fluids in response to these continent wide tectonothermal events the presence of sphalerite mineralization and associated geochemical anomalies in zn and cd contents in carbonate rocks may also be used to trace basement features

a late cretaceous and cenozoic reconstruction of the southwest pacific region tectonics controlled by subduction and slab rollback processes abstract a cenozoic tectonic reconstruction is presented for the southwest pacific region located east of australia the reconstruction is constrained by large geological and geophysical datasets and recalculated rotation parameters for pacific australia and lord howe rise pacific relative plate motion the reconstruction is based on a conceptual tectonic model in which the large scale structures of the region are manifestations of slab rollback and backarc extension processes the current paradigm proclaims that the southwestern pacific plate boundary was a west dipping subduction boundary only since the middle eocene the new reconstruction provides kinematic evidence that this configuration was already established in the late cretaceous and early paleogene from 82 to 52 ma subduction was primarily accomplished by east and northeast directed rollback of the pacific slab accommodating opening of the new caledonia south loyalty coral sea and pocklington backarc basins and partly accommodating spreading in the tasman sea the total amount of east directed rollback of the pacific slab that took place from 82 ma to 52 ma is estimated to be at least 1200 km a large percentage of this rollback accommodated opening of the south loyalty basin a north south trending backarc basin it is estimated from kinematic and geological constraints that the east west width of the basin was at least 750 km the south loyalty and pocklington backarc basins were subducted in the eocene to earliest miocene along the newly formed new caledonia and pocklington subduction zones this culminated in southwestward and southward obduction of ophiolites in new caledonia northland and new guinea in the latest eocene to earliest miocene it is suggested that the formation of these new subduction zones was triggered by a change in pacific australia relative motion at 50 ma two additional phases of eastward rollback of the pacific slab followed one during opening of the south fiji basin and norfolk basin in the oligocene to early miocene up to 650 km of rollback and one during opening of the lau basin in the latest miocene to present up to 400 km of rollback two new subduction zones formed in the miocene the south dipping trobriand subduction zone along which the solomon sea backarc basin subducted and the north dipping new britain san cristobal new hebrides subduction zone along which the solomon sea backarc basin subducted in the west and the north loyalty south fiji backarc basin and remnants of the south loyalty santa cruz backarc basin subducted in the east clockwise rollback of the new hebrides section resulted in formation of the north fiji basin the reconstruction provides explanations for the formation of new subduction zones and for the initiation and termination of opening of the marginal basins by either initiation of subduction of buoyant lithosphere a change in plate kinematics or slab mantle interaction

minor and trace element export from a glacierized alpine headwater catchment haut glacier d arolla switzerland major ion concentrations in meltwaters draining glacial environments have been widely reported however concentrations of minor and trace elements have received scant attention this study presents trace and minor element variations in bulk meltwaters draining haut glacier d arolla switzerland based on twice daily sampling throughout the 1999 ablation season which represents the most detailed meltwater quality dataset to date in order to assess the mode of export from the catchment these elements are partitioned into i dissolved and ii particulate associated minor and trace element components a computer based speciation model phreeqci was applied to the bulk meltwater data suggesting that ba be cd cu li rb and sr exist primarily as mobile monovalent or divalent dissolved cations which may be involved in interactions with suspended sediment surfaces conversely the model predicts the precipitation of fe al mn and cr oxi hydroxides suggesting these species may be predominantly transported as colloids which may remove other minor and trace elements from solution by co precipitation reactions laboratory leaching experiments on suspended sediments and fresh rock powder suggests that minor and trace element concentrations may also be influenced by oxy hydroxide precipitation and adsorption desorption reactions with suspended sediment surfaces the quantity and transport mode of trace and minor elements may influence their bioavailability downstream of glacierized headwater catchments further the enrichment of many dissolved minor and trace elements in meltwaters compared with world stream waters coupled with the timing of water and sediment delivery during the summer months may have implications for downstream aquatic environments copyright 2001 john wiley sons ltd

evolution of the louisiade triple junction we derived new finite rotations for the opening of the coral sea using revised magnetic anomaly interpretations and fracture zone data from a gravity anomaly grid based on from satellite altimetry these rotations differ from the finite rotations that describe the opening of the tasman sea this confirms the existence of a triple junction between the australian plate the mellish rise and the louisiade plateau active during the opening of the coral sea 62 to 52 ma magnetic anomalies fracture zones visible on the gravity grid and strike slip faults indicate that extension occurred between the mellish rise and the louisiade plateau and extensional and transform motion occurred between australia and the mellish rise attached to the chesterfield and kenn plateaus the configuration of the triple junction from chron 27 to 26 was either ridge ridge ridge rrr or ridge fault fault rff at chron 26 58 ma the triple junction had a rff configuration and migrated southward as the relative motion between the louisiade plateau and the mellish rise was transferred to the boundary between the mellish rise and the kenn plateau the gravity low between the kenn plateau and the mellish rise is interpreted as a strike slip fault active from about 57 to 52 ma this configuration lasted until seafloor spreading ceased in the coral and tasman seas at about 52 ma our model implies extension in the osprey embayment that might explain small areas of oceanic crust west of the coral sea basin the western boundary of the coral sea was a ne sw strike slip fault active between 58 and 52 ma

the calamine nonsulfide zn pb deposits of belgium petrographical mineralogical and geochemical characterization abstract the belgian nonsulfide zn deposits represent the historical basis for the zinc mining and smelting industry in europe the zinc ores were called calamines and consist of a mixture of zn carbonates smithsonite hydrozincite and zn silicates hemimorphite willemite and zn clays with a variable content of pb minerals the calamines are considered to be oxidation products of primary sulfide ores the most important was the la calamine orebody more than 600 000 tons of zn metal that was continuously exploited for several centuries nonsulfide ores were also exploited at schmalgraf engis dickenbusch fossey rocheux oneux welkenraedt and in other smaller deposits all no longer accessible for study where the calamines extended from the surface to an average depth of 40 to 50 m the primary zn pb sulfide mineralization consists of post variscan hydrothermal veins and replacement bodies mostly occurring in the dinantian visean limestones the sulfides intersect the paleozoic rocks and are truncated and unconformably covered by late cretaceous sediments santonian aachen fm the same setting has been observed for the nonsulfide ores suggesting an early to mid cretaceous weathering consistent with other geological and geochronological data on paleoweathering in europe the extensive occurrence of willemite that appears to be the first deposited nonsulfide mineral is a striking particularity of the belgian calamines most fluid inclusions in willemite 80 and all inclusions in smithsonite are monophase aqueous ice melting temperatures suggest salinities between 0 and 5 wt nacl equiv homogenization temperatures of rare two phase inclusions liquid vapor in willemite display a large variation between 80 and 190 an interval matching the temperature ranges of other willemite ores throughout the world so far considered of hydrothermal origin the stable isotope variation of belgian smithsonites and cerussites is very similar to the range measured in other supergene nonsulfide deposits similar to those of sw sardinia belgian smithsonites exhibit a limited range of 18o values from 27 1 to 30 6 averaging 28 4 0 8 v smow this limited range points to a relatively uniform isotope composition of the oxidizing waters and constant temperatures of smithsonite crystallization carbon isotope values even from the same mine show a considerable range from 11 6 to 1 6 this extensive range indicates at least two carbon sources 13c depleted carbon derived from the organic matter in the soils and 13c enriched carbon originating from marine carbonate host rocks cerussites have oxygen isotope values ranging from 16 8 to 19 3 averaging 17 8 1 0 and carbon isotope values of 18 4 to 14 7 the metallic deposits of eastern belgium have undergone a polyphase history which started with a possibly jurassic sulfide mineralization followed by oxidation under high silica activities and consequently by supergene weathering owing to structure and mineralogical association we do not consider the high homogenization temperatures as reliable minimum temperature estimates of willemite formation however it is possible that the willemite concentrations could have been derived from low temperature localized hydrothermal processes caused by deeply reaching oxidizing fluids smithsonite and hemimorphite often developed at the expenses of willemite have all the characteristics of supergene oxidation products

solute provenance transport and denudation in a high arctic glacierized catchment recent understanding of chemical weathering in glacierized catchments has been focused on mid latitude alpine catchments comparable studies from the high latitudes are currently lacking this paper attempts to address this deficiency by examining solute provenance transport and denudation in a glacierized catchment at 78 n in the svalbard high arctic archipelago representative samples of snow glacier ice winter proglacial icing and glacier meltwater were obtained from the catchment during spring and summer 1993 and analysed for major ion chemistry seasonal variations in the composition of glacier meltwater occur and are influenced by proglacial solute acquisition from the icing at the very start of the melt season and subsequently by a period of discharge of concentrated snowmelt caused by snowpack elution weathering within the ice marginal channels that drain the glacier particularly carbonation reactions continues to furnish solute to meltwater when suspended sediment concentrations increase later in the melt season partitioning the solute flux into its various components sea salt crustal aerosol and atmospheric sources shows that c 25 of the total flux is sea salt derived consistent with the maritime location of the glacier and c 71 is crustally derived estimated chemical denudation 160 meq m 2 a 1 sea salt corrected cation equivalent weathering rate is somewhat low compared with other studied glacierized catchments estimates in the range 450 1000 meq m 2 a 1 which is probably attributable to the relatively short melt season and low specific runoff in the high arctic a positive relationship was identified between discharge and co 2 drawdown owing to carbonation reactions in turbid meltwater

hydrogeochemistry of coal mine water of north karanpura coalfields india implication for solute acquisition processes dissolved fluxes and water quality assessment mine water samples collected from different mines of the north karanpura coalfields were analysed for ph electrical conductivity total dissolved solids tds total hardness th major anions cations and trace metals to evaluate mine water geochemistry and assess solute acquisition processes dissolved fluxes and its suitability for domestic industrial and irrigation uses mine water samples are mildly acidic to alkaline in nature the tds ranged from 185 to 1343 mg l 1 with an average of 601 mg l 1 ca2 and mg2 are the dominant cations while so4 2 and hco3 are the dominant anions a high concentration of so4 2 and a low hco3 hco3 so4 2 ratio 0 50 in the majority of the water samples suggest that either sulphide oxidation or reactions involving both carbonic acid weathering and sulphide oxidation control solute acquisition processes the mine water is undersaturated with respect to gypsum halite anhydrite fluorite aluminium hydroxide alunite amorphous silica and oversaturated with respect to goethite ferrihydrite quartz about 40 of the mine water samples are oversaturated with respect to calcite dolomite and jarosite the water quality assessment shows that the coal mine water is not suitable for direct use for drinking and domestic purposes and needs treatment before such utilization tds th f so4 2 fe mn ni and al are identified as the major objectionable parameters in these waters for drinking the coal mine water is of good to suitable category for irrigation use the mines of north karanpura coalfield annually discharge 22 35 106 m3 of water and 18 50 103 tonnes of solute loads into nearby waterways

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

style and intensity of late cenozoic deformation in the nagoorin basin eastern queensland australia and implications for the pattern of strain in an intraplate setting eastern australia was affected by late cenozoic intraplate deformation in response to far field stress transmitted from the plate boundaries but little is known about the intensity and pattern of this deformation we used recently surveyed two dimensional seismic reflection lines and aeromagnetic data and data from the recently released australian stress map to investigate the structure of the nagoorin basin in eastern queensland the western margin of the nagoorin beds was displaced by the boynedale fault which is a nnw striking sw dipping oblique strike slip reverse fault with a vertical throw of c 900 m and c 16 km sinistral displacement a significant part of this large sinistral displacement is interpreted to have occurred prior to late cenozoic time several low angle 30 thin skinned thrusts with a flat ramp geometry also displaced the nagoorin beds which are interpreted to have developed along detachment surfaces in oil shales and claystone the boynedale fault is a segment within longer nnw striking faults that include the north pine and west ipswich fault systems in eastern queensland these nnw striking faults are potentially active and may accommodate neotectonic thrust movement in response to the present day ne sw orientation of s results of this study in conjunction with previous information on sedimentary basins in eastern australia indicate that cenozoic contractional deformation is stronger at the continental margins possibly due to the presence of pre existing rift related structures

the nature of mineralizing fluids of the kipushi zn cu deposit katanga democratic repubic of congo quantitative fluid inclusion analysis using laser ablation icp ms and bulk crush leach methods fluid inclusions from the epigenetic zn cu deposit of kipushi central african copper belt katanga democratic republic of congo have been subjected to an integrated microthermometric bulk crush leach and laser ablation inductively coupled plasma mass spectrometric la icp ms study to elucidate the physicochemical conditions of ore formation and the origin of the mineralizing fluids the kipushi deposit is hosted in carbonates and partly in siliciclastic rocks that have undergone regional low grade greenschist facies metamorphism and which were strongly deformed during the lufilian orogeny main deformation phase 550 ma investigation of host rock gangue and ore samples enabled reconstruction of the paragenesis of ore deposition the main zn cu ge pb sulfide mineralization was accompanied by three generations of hydrothermal dolomite and a generation of coarse grained quartz primary and pseudosecondary fluid inclusions in these minerals contain predominantly halite saturated aqueous brines 30 43 wt nacl equiv with locally unidentified trapped solids these inclusions mostly decrepitate upon heating before total homogenization which could suggest that they also trapped excess carbonic vapor they show petrographic and microthermometric evidence for postentrapment reequilibration prohibiting their use as accurate geothermometers and geobarometers previous studies on chlorite and sphalerite geothermometry framed the formation temperature of the kipushi cu zn deposit between 290 to 380 c younger fluids are present as secondary inclusions in the gangue minerals and as primary fluid inclusions in sphalerite from a minor secondary mineralization phase these two phase aqueous inclusions have a slightly lower salinity 23 31 wt nacl equiv and have homogenization temperatures ranging from 170 to 80 c in successive fluid inclusion assemblages sporadically some mixed aqueous carbonic and gaseous co2 ch4 inclusions are present but their genetic position is un clear and they are insignificant with regard to the mineralization process as a whole crush leach bulk analysis of the fluid inclusions show that the mineralizing fluids had a molar cl br ratio close to or somewhat higher than the seawater value which rules out a major contribution from bittern brines and suggests that the fluids gained their salinity primarily by the dissolution of evaporites younger fluids that circulated through the deposit after the main phase of ore formation have cl br and na br signatures indicative of a greater involvement of halite dissolution brines values much higher than that of seawater la icp ms analyses of the mineralizing fluids reveal that they have molar li na ca na mg na mn na and sr na in the range of natural high salinity fluids in metamorphic environments worldwide however they have relatively high molar fe na zn na pb na and especially very high ba na ratios their molar k na is also somewhat higher than for other low grade metamorphic fluids but is nevertheless in agreement with the values predicted by the k na geothermometer at the conditions of ore formation this suggests that the major element composition of the fluids was buffered by fluid mineral equilibria their relatively high metal contents ba zn fe and pb suggest that they interacted with and leached these elements from felsic basement rocks at higher temperatures whatever the origin of the fluids their salinity and the metals their uniformly high ba and ore metal content together with the absence of barite and the occurrence of ba silicates at kipushi indicates that sulfide mineralization occurred when the metal bearing fluids encountered a reducing h2s rich reservoir the ubiquitous presence of preexisting metamorphosed carbonic material shungite in the sulfides and host rock and a sulfur isotope signature of the ores in agreement with thermogenic sulfate reduction suggests that this condition was likely created due to the high initial reduced carbon content of the host rocks at kipushi which seems to be exceptional in the copper belt therefore we postulate that a critical factor in the formation of major vein type zn cu mineralization was the presence of a hydrocarbon rich facies of the lower nguba carbonates at kipushi

the new england batholith constraints on its derivation from nd and sr isotopic studies of granitoids and country rocks abstract nd and sr isotopic compositions are reported for the granitic suites which comprise the late palaeozoic to earliest mesozoic new england batholith of eastern australia some of the granitic suites are typically i type in their mineralogy chemistry and isotopic compositions implying a derivation from igneous infracrustal source rocks whereas other suites have characteristics consistent with a derivation from a protolith which was predominantly sedimentary and relatively felsic s types the i type granitoids of the nundle suite have nd values 3 3 to 6 1 that are amongst the most primitive yet documented for a relatively felsic sio 2 65 plutonic suite and these values imply a derivation from either a depleted upper mantle source or more probably a complex source region involving both volcanic arc rocks and detrital material their compositions are distinctly more primitive than those of the new england super suite which constitutes the permian core of the batholith this extensive super suite comprising granitoids traditionally designated as i type has an overall range in initial nd and sr isotopic compositions of 1 7 to 4 6 and 0 70458 to 0 70624 respectively although the majority of plutons have initial nd isotopic compositions which fall into a very narrow range 1 0 1 5 units this limited range is remarkable considering the extreme lithological diversity and range in chemical composition of the analysed samples sio 2 47 74 and implies a source region of considerable volume having reasonably uniform isotopic compositions but variation in chemistry a similarly uniform source isotopically is also indicated for the s type granitoids of the carboniferous hillgrove suite and carboniferous permian bundarra suite with initial nd values of 0 8 to 2 3 and initial 87 sr 86 sr compositions of 0 70474 to 0 70577 showing only limited ranges five pelites three felsic and four mafic greywackes representing typical country rocks from different stratigraphic levels have initial nd values 1 7 to 6 6 and initial 87 sr 86 sr compositions 0 70378 to 0 70585 which essentially mirror the compositional variation in the granitoids a chemical mineralogical and isotopic bimodality in these sediments indicates two very distinctive sources one felsic rhyodacitic the other relatively mafic andesitic which were separated spatially and temporally in many but not all areas of early to mid palaeozoic new england a model is presented in which the s type granitoids are derived from a predominantly felsic source i e pelites and felsic greywackes whereas some of the granitoids belonging to the new england super suite may have been derived from source rocks consisting of both felsic and mafic sedimentary components the distinction between many s type and i type granitoids in new england is unclear for two principal reasons a because the granitoids and their respective source rocks are relatively young geologically so that their isotopic systems have not evolved to any considerable extent and b because of the intrinsic igneous chemical compositions of any sedimentary component that may be involved in their genesis

geometry bed topography and drainage system structure of the haut glacier d arolla switzerland as part of an integrated study of the hydrology meltwater quality and dynamics of the haut glacier d arolla switzerland the glacier s drainage network structure was determined from patterns of dye recovery in 342 injection experiments conducted from 47 moulins distributed widely across the glacier this structure was compared with theoretical predictions based upon reconstructed patterns of water flow governed by a the subglacial hydraulic potential surface and b the subglacial bedrock surface these reconstructions were based on measurements of ice surface and bedrock topography obtained by a combination of ground survey and radio echo sounding techniques the two reconstructions simulate the drainage system structures expected for a closed channels in which water is pressurized by the overlying ice and b gravity driven open channel flow the closed channel model provides the best fit to the observed structure even though theoretical calculations suggest that under summer discharge conditions open channel flow may be widespread beneath the glacier possible reasons for this apparent discrepancy are discussed

rapid change in drift of the australian plate records collision with ontong java plateau earth s largest and thickest oceanic plateau the ontong java plateau is currently colliding with the australian plate but it has been difficult to date the start of this momentous event with much accuracy now a team from the university of queensland presents strong evidence for a collision starting about 26 million years ago the dating comes from geochronological data on hotspot volcanoes in the tasman sea east of australia which reveal a link between collision of the plateau with the melanesian arc and motion of the australian plate the timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the pacific including the archetypal hawaiian chain suggesting that immense oceanic plateaus like ontong java can contribute to initiating rapid change in plate boundaries and motions on a global scale geochronological data on hotspot volcanoes in eastern australia are presented which reveal a strong link between collision of the plateau with the melanesian arc and motion of the australian plate the timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the pacific including the archetypal hawaiian chain and thus provide strong evidence that immense oceanic plateaus can contribute to initiating rapid change in plate boundaries and motions on a global scale the subduction of oceanic plateaux which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood basalt provinces is an important factor in many current models of plate motion1 2 3 4 and provides a potential mechanism for triggering plate reorganization5 to evaluate such models it is essential to decipher the history of the collision between the largest and thickest of the world s oceanic plateaux the ontong java plateau and the australian plate but this has been hindered by poor constraints for the arrival of the plateau at the melanesian trench here we present 40ar 39ar geochronological data on hotspot volcanoes in eastern australian that reveal a strong link between collision of the greenland sized ontong java plateau with the melanesian arc and motion of the australian plate the new ages define a short lived period of reduced northward plate motion between 26 and 23 myr ago coincident with an eastward offset in the contemporaneous tracks of seamount chains in the tasman sea east of australia these features record a brief westward deflection of the australian plate as the plateau entered and choked the melanesian trench 26 myr ago from 23 myr ago australia returned to a rapid northerly trajectory at roughly the same time that southwest directed subduction began along the trobriand trough6 the timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the pacific plate including the archetypal hawaiian chain7 and thus provide strong evidence that immense oceanic plateaux like the ontong java can contribute to initiating rapid change in plate boundaries and motions on a global scale

debris transport in a temperate valley glacier haut glacier d arolla valais switzerland hambrey m j goodsell becky glasser n f 2005 debris transport in a temperate valley glacier haut glacier d arolla valais switzerland journal of glaciology 51 172 pp 139 146

groundwater chemistry and water rock interactions at stripa groundwaters from near surface to a depth of 1232 m in the stripa granite have been sampled and analyzed for major and trace constituents the groundwater composition consists of two general types a typical recharge water of ca hco3 type 700 m depth of high ph 8 10 that reaches a maximum of 1250 mg l in total dissolved solids tds intermediate depths show mixtures of the two types that are highly fracture dependent rather than depth dependent any borehole can vary significantly and erratically in tds for either a horizontal or vertical direction the general transition from ca hco3 type to na ca cl type correlates with the depth profile for hydraulic conductivity that drops from 10 8 m s to 10 11 m s or lower thermomechanical stress from heater experiments clearly shows an effect on the groundwater composition that could be caused by changing flow paths leakage of fluid inclusions or both dissolution and precipitation of calcite fluorite and barite aluminosilicate hydrolysis and addition of a saline source possibly fluid inclusion leakage play the major roles in defining the groundwater composition the low permeability of the stripa granite has produced a groundwater composition that appears intermediate between the dilute shallow groundwaters typical of recharge in a crystalline rock terrain and the saline waters and brines typical of cratonic shield areas at depth

glacier hydrochemistry solute provenance and chemical denudation at a surge type glacier in kuannersuit kuussuat disko island west greenland abstract in 1995 1998 han 11 km terrestrial surge of kuannersuit glacier an outlet glacier of the largest ice cap on disko island west greenland affected the catchment dramatically in order to estimate solute fluxes and provenances bulk meltwaters were sampled at the main subglacial outlet during the initial part of the quiescent phase the hydrochemistry is significantly influenced by a subglacial basaltic weathering regime with absence of carbonate minerals the results show that marine and aerosol derived solutes have minimal contribution to the total ion content whereas sequestration of atmospheric co 2 associated with carbonation of ca rich feldspar and reactive volcanic glass is more dominant than previously reported from glacierized catchments application of a sampling strategy dividing water samples into four groups to determine the content of dissolved hco 3 and co 3 2 shows that the cationic equivalent weathering rate range is 683 860 meq m 2 a 1 and solute flux ranges between 76 and 98 t km 2 a 1 the crustal denudation rate is estimated to 26 t km 2 a 1 and the transient co 2 drawdown amounts to 8500 13700 kg c km 2 a 1

fluid transfers at a basement cover interface part ii large scale introduction of chlorine into the basement by mesozoic basinal brines significant fracture and porosity sealing characterizes the sedimentary cover basement interface in the northwestern margin of the aquitaine basin france dolomite and calcite and sometimes fluorite barite and quartz constitute most of the fracture fillings they contain primary inclusions of brines having chlorinities in the range of 3 3 to 5 5 mol cl kg solution with total homogenization temperatures in between 65 and 130 c for quartz and slightly lower for dolomite barite fluorite and calcite crush leach analyses indicate that brines are characterized by na k ratios of 5 to 40 na li ratios of 20 to 530 and cl br ratios of 200 to 1000 which are rather typical of deep basinal brines the fluid 18o signature is estimated to be 6 6 1 8 smow for a crystallization temperature of 100 20 c between 80 and 120 c and the d value is 30 10 smow the fluid source for the fracture filling mineral is interpreted as a deep sedimentary brine expelled during a period of maximum subsidence in the aquitaine basin which migrated along the sediment cover basement interface which is characterized by high permeabilities below the toarcian shales the sealing is likely to be linked to the mixing of the brines with dilute ascending hot waters these dilute waters infiltrated from emerged zones convected and heated at depth reaching temperatures of 100 c up to 150 c on the basis of cation geothermometry extensional activity of probable cretaceous age related to the gascogne gulf rifting could be considered as the most likely cause of a significant fluid migration event at the basement cover interface all along the margins of the french massif central these processes are large scale as shown by the similarities of mineral sequences fluid types and general features of most of the f ba pb zn deposits located at the basement sedimentary cover interface the mass transfer of cl linked to this stage is significant and accounts for the early introduction of large amounts of chlorine in the granitoid microporosity this probably explains the significant chlorine concentrations of the present day fluids recovered in the granitoid aquifer

solute dynamics of meltwater of gangotri glacier garhwal himalaya india the present study investigates solute dynamics of meltwater of gangotri glacier system in terms of association of different chemical compounds with the geology of the area in the meltwater the presence of cations varied as c mg2 c ca2 c na c k while order of concentration of anions has been c hco3 c so42 c cl c no3 in years 2003 and 2004 the magnesium and calcium are found as the dominant cations along with bicarbonate and sulphate as dominant anions the high ratios of c ca2 mg2 total cations and c ca2 mg2 c na k indicate that the meltwater chemistry of the gangotri glacier system catchment is mostly controlled by carbonate weathering attempts are made to develop rating curves for discharge and different cations sporadic rise in discharge without corresponding rise in concentration of most of cations is responsible for their loose correlation in a compound valley glacier like gangotri glacier

major ion chemistry of the ganga brahmaputra river system weathering processes and fluxes to the bay of bengal the ganga brahmaputra one of the world s largest river systems is first in terms of sediment transport and fourth in terms of water discharge a detailed and systematic study of the major ion chemistry of these rivers and their tributaries as well as the clay mineral composition of the bed sediments has been conducted the chemistry of the highland rivers upper reaches of the ganga the yamuna the brahmaputra the gandak and the ghaghra are all dominated by carbonate weathering ca mg and hco3 account for about 80 of the cations and anions in the lowland rivers the chambal the betwa and the ken hco3 excess over ca mg and a relatively high contribution of na k to the total cations indicate that silicate weathering and or contributions from alkaline saline soils and groundwaters could be important sources of major ions to these waters the chemistry of the ganga and the yamuna in the lower reaches is by and large dictated by the chemistry of their tributaries and their mixing proportions illite is the dominant clay mineral about 80 in the bedload sediments of the highland rivers kaolinite and chlorite together constitute the remaining 20 of the clays in the chambal betwa and ken smectite accounts for about 80 of the clays this difference in the clay mineral composition of the bed sediments is a reflection of the differences in the geology of their drainage basins the highland rivers weather acidic rocks whereas the others flow initially through basic effusives the ganga brahmaputra river system transports about 130 million tons of dissolved salts to the bay of bengal which is nearly 3 of the global river flux to the oceans the chemical denudation rates for the ganga and the brahmaputra basins are about 72 and 105 tons km yr 1 respectively which are factors of 2 to 3 higher than the global average the high denudation rate particularly in the brahmaputra is attributable to high relief and heavy rainfall

fluid evolution at the variscan front in the vicinity of the aachen thrust quartz carbonate chlorite veins were studied in borehole samples of the rwth 1 well in aachen veins formed in devonian rocks in the footwall of the aachen thrust during variscan deformation and associated fluid flow primary fluid inclusions indicate subsolvus unmixing of a homogenous h2o co2 ch4 n2 na k cl fluid into a h2o na k cl solution and a vapour rich co2 h2o ch4 n2 fluid the aqueous end member composition resembles that of metamorphic fluids of the variscan front zone with salinities ranging from 4 to 7 nacl equiv and maximum homogenisation temperatures of close to 400 c pressure estimates indicate a burial depth between 4 500 and 8 000 m at geothermal gradients between 50 and 75 c 26 mpa but pressure decrease to sublithostatic conditions is also indicated probably as a consequence of fracture opening during episodic seismic activity a second fluid system mainly preserved in pseudo secondary and secondary fluid inclusions is characterised by fluid temperatures between 200 and 250 c and salinities of 5 nacl equiv bulk stable isotope analyses of fluids released from vein quartz calcite and dolomite by decrepitation yielded dh2o values from 89 to 113 13cch4 from 26 9 to 28 9 vpdb and 13cco2 from 12 8 to 23 3 vpdb the low d and 13c range of the fluids is considered to be due to interaction with cracked hydrocarbons the second fluid influx caused partial isotope exchange and disequilibrium it is envisaged that an initial short lived flux of hot metamorphic fluids expelled from the epizonal metamorphic domains of the stavelot venn massif the metamorphic fluid was focused along major thrust faults of the variscan front zone such as the aachen thrust a second fluid influx was introduced from formation waters in the footwall of the aachen thrust as a consequence of progressive deformation mixing of the cooler and lower salinity formation water with the hot metamorphic fluid during episodic fluid trapping resulted in an evolving range of physicochemical fluid inclusion characteristics

paleostress field evolution of the australian continent since the eocene 1 although the low order present stress field of most continents is fairly well established information on paleostress fields is generally sparse knowledge of paleostresses is crucial for understanding brittle tectonic reactivation through time the indian australian plate lends itself well to a reconstruction of paleostresses as it has undergone enormous changes in plate driving forces through the tertiary and there is a rich record of fault reactivation from sedimentary basins we reconstruct the plate boundary configuration and age area distribution of ocean crust around australia through time to obtain estimates for ridge push slab pull and collisional forces acting on the indian australian plate since the eocene other model parameters we explore are the effects of the australian antarctic discordance and the mechanical strength of the australian continental margin we apply these constraints to model the orientation of the maximum horizontal compressive stress shmax regime for the present early miocene and early eocene using the commercial software abaqus along with the optimization software nimrod o we use an elastic two dimensional plane stress finite element model with a resolution of 0 2 in both longitude and latitude realistic elastic parameters representing different rock types and geologic provinces for the australian continent have been included to model the stress field of a heterogeneous plate we show that spatially significant rotations of shmax directions can be modeled as a consequence of perturbations of shmax in areas of juxtaposed rigid and compliant rheologies the absence of the collisional papua new guinea boundary in the miocene and reduced ridge push force from the south result in stress directions considerably different from the present stress directions over the northern australian continent in the early miocene in particular show large disparity with present stress directions stress orientations for the australian plate during the early eocene are controlled predominantly by ridge push forces arising from spreading in the wharton basin in the indian ocean and vary substantially with stress directions in the early miocene and the present because of the drastically different plate geometry and boundary configurations fault reactivation histories observed on the northwest shelf of australia and in the bass strait region are consistent with modeled changes in stress directions through time

alpine subglacial hydrology abstract the size and shape of subglacial flow pathways exert a strong influence over the pressure and speed at which meltwaters are routed through glaciers these characteristics in turn influence glacier sliding velocity and the quantity and quality of bulk meltwaters discharging from glaciers in this paper we summarise four empirical research approaches that have been developed to improve our understanding of the subglacial hydrology of predominantly temperate based alpine glaciers investigations of bulk meltwater discharge and chemistry tracer studies proglacial bedrock investigations and borehole investigations as a result of linking these studies to conceptual or numerical models three arborescent and four non arborescent or distributed subglacial drainage configurations are described these drainage networks may be neither spatially nor temporally persistent but may compete with and replace each other on a seasonal basis a qualitative model of the temporal and spatial evolution of a typical alpine subglacial drainage system is advanced on the basis of research conducted at haut glacier d arolla switzerland

late cenozoic intraplate faulting in eastern australia abstract the intensity and tectonic origin of late cenozoic intraplate deformation in eastern australia is relatively poorly understood here we show that cenozoic volcanic rocks in southeast queensland have been deformed by numerous faults using gridded aeromagnetic data and field observations structural investigations were conducted on these faults results show that faults have mainly undergone strike slip movement with a reverse component displacing cenozoic volcanic rocks ranging in ages from 31 to 21 ma these ages imply that faulting must have occurred after the late oligocene late cenozoic deformation has mostly occurred due to the reactivation of major faults which were active during episodes of basin formation in the jurassic early cretaceous and later during the opening of the tasman and coral seas from the late cretaceous to the early eocene the wrench reactivation of major faults in the late cenozoic also gave rise to the occurrence of brittle subsidiary reverse strike slip faults that affected cenozoic volcanic rocks intraplate transpressional deformation possibly resulted from far field stresses transmitted from the collisional zones at the northeast and southeast boundaries of the australian plate during the late oligocene early miocene and from the late miocene to the pliocene these events have resulted in the hitherto unrecognized reactivation of faults in eastern australia

environmental geochemistry and quality assessment of mine water of jharia coalfield india a long mining history and unscientific exploitation of jharia coalfield caused many environmental problems including water resource depletion and contamination a geochemical study of mine water in the jharia coalfield has been undertaken to assess its quality and suitability for domestic industrial and irrigation uses for this purpose 92 mine water samples collected from different mining areas of jharia coalfield were analysed for ph electrical conductivity ec major cations ca2 mg2 na k anions f cl hco3 so4 2 no3 dissolved silica h4sio4 and trace metals the ph of the analysed mine water samples varied from 6 2 to 8 6 indicating mildly acidic to alkaline nature concentration of tds varied from 437 to 1 593 mg l 1 and spatial differences in tds values reflect the variation in lithology surface activities and hydrological regime prevailing in the region so4 2 and hco3 are dominant in the anion and mg2 and ca2 in the cation chemistry of mine water high concentrations of so4 2 in the mine water of the area are attributed to the oxidative weathering of pyrites ca mg so4 and ca mg hco3 are the dominant hydrochemical facies the drinking water quality assessment indicates that number of mine water samples have high tds total hardness and so4 2 concentrations and needs treatment before its utilization concentrations of some trace metals fe mn ni pb were also found to be above the desirable levels recommended for drinking water the mine water is good to permissible quality and suitable for irrigation in most cases however higher salinity residual sodium carbonate and mg ratio restrict its suitability for irrigation at some sites

the new england batholith eastern australia geochemical variations in time and space the new england batholith australia is part of the upper paleozoic new england fold belt with most plutons intruded into the deformed trench complex metasedimetary rocks in the southeast part of the fold belt the batholith was emplaced in two major periods of plutonism the first during the upper carboniferous and the second during the upper permian and triassic with a major phase of metamorphism and deformation including westward overthrusting of the trench complex sedimentary rocks between the two periods on the basis of petrography geochemistry and isotopic characteristics the granitoids of the batholith are subdivided into five named intrusive suites and a group of leucoadamellites the differences between the six groups are considered to reflect differences in their source rock types the carboniferous granitoids are peraluminous s type and are divided into the bundarra plutonic suite a belt of very coarse grained adamellites with cordierite garnet and the hillgrove plutonic suite a belt of biotite rich garnet deformed adamellites and granodiorites both suites have 18o greater than 10 negative 34s 87sr 86sr initial ratios about 0 706 are ilmenite bearing and have low feo3 ratios the bundarra plutonic suite however is consistently sio2 rich greater than 70 contains cordierite and has higher 18o than the hillgrove plutonic suite the two s type suites are inferred to have formed by partial melting of the deepest parts of a wedge of trench complex sedimentary rocks oceanwards of an andean volcanic chain to the west analagous to the lower tertiary s type plutons of the sanak baranof plutonic belt of southern alaska of the remaining four groups of plutons emplaced during the upper permian and triassic two are metaluminous i type granitoids one the clarence river plutonic suite new name a group of k poor granodiorites and tonalites with low 87sr 86sr initial ratios average 0 7035 and the other the moonbi plutonic suite a group of k rich adamellites with low 87sr 86sr initial ratios average 0 7045 18o less than 10 and 34s positive the clarence river plutonic suite is inferred to have formed from the partial melting of a large ion lithophile element poor gabbro source region and the moonbi plutonic suite from a large ion lithophile element rich shoshonite source region a third group the uralla plutonic suite is less metaluminous has higher 87sr 86sr initial ratios average 0 706 18o only just less than 10 and negative 34s and is considered to have formed in a region containing a physical mixture of metaluminous and peraluminous source rocks gabbro and metasedimentary rocks plutons of the fourth group are leucoadamellites largely emplaced after the other suites with low 18o indicating an i type source it is argued that this group has resulted from low degrees of dry partial metling of an i type source region that had undergone an earlier melting event these four groups of plutons are largely confined to a narrow belt parallel to but 100 km west of the present rifted margin of australia their origin may be related to crustal thickening attendant on the overthrusting that occurred early in the permian and or a temperature increase in the lower crust due to the recovery of normal continental geotherms following the cessation of subduction

structural framework of the zagros fold thrust belt iran abstract data gleaned from the literature on the zagros have been compiled and used in conjunction with new interpretations to provide a better picture of the structures sedimentation history and deformation of this hydrocarbon rich mountain belt the belt parallel mountain front the n s trending kazerun izeh and e w trending bala rud fault zones are defined as the master structural elements of the belt these fault zones divide the zagros basin into zones with different stratigraphic successions and different rheological profiles this resulted in different structural styles developing along the belt during the subsequent collision the kazerun and izeh fault zones acted as the depositional system transition zone between the lurestan and fars regions in jurassic cretaceous time and partly controlled the distribution of the kazhdumi formation one of the major source rocks by the end of the cretaceous the nw se trending mountain front fault divided the present folded belt of the zagros into a major foreland basin to the southwest and a piggyback basin to the northeast activity along other major transfer fault zones including the izeh kazerun and bala rud fault zones occurred at this time and controlled the sedimentation and subsidence of the dezful embayment the main target region for hydrocarbon exploration these fault zones controlled the thickness of the asmari formation one of the main reservoirs and also the considerable thickness and facies changes of the gachsaran formation the major seal to the asmari formation the present morphology of the mountain belt is interpreted as being mainly related to the pinning of the mountain front fault to the northwest of the dezful embayment and to the north of the strait of hormuz

low latitude meteoric fluid flow along the cloncurry fault cloncurry district nw queensland australia geodynamic and metallogenic implications hydrothermal alteration within the mount isa block mib is typically largely to have ceased at the end of the isan orogeny ca 1 50 ga however late large brittle quartz rich vein systems including those of the cloncurry fault cut mesoproterozoic tectonic fabrics intrusions and products of regional na ca hydrothermal alteration associated features display affinities to iron oxide cu au ore deposits including specular hematite bearing veins and cu au u lree ba mineralization stable isotope data suggest late veins in the vicinity of the cloncurry fault eastern fold belt efb formed from fluids with 18oh2o and dh2o 250 c of 4 to 3 and 22 to 4 respectively the high dh2o moderate 18oh2o and cacl2 nacl rich character of the saline fluids indicates they were mixtures of low latitude meteoric fluids and evaporite derived basinal brines which with time became progressively dominated by meteoric water deposited barite and cooled the low latitude meteoric signature demonstrates that the fault fracture systems were active when in equatorial regions paleomagnetic data for the mib and the australian protocontinent together with structural and thermal considerations and geochronological arguments suggest the veins probably formed sometime after 1 10 ga and potentially as late as during the alice springs orogeny ca 0 34 ga the late quartz veining was unrelated to two phases of regional na ca alteration and economically significant fe oxide cu au mineralization at 1 60 1 58 and 1 53 1 50 ga

thin skinned thrusting in the northern new england orogen central queensland australia regional cross sections of the northern new england orogen and eastern bowen basin in eastern queensland indicate that the climactic permian triassic deformation involved thin skinned tectonics with the development of a mountain front represented by a syncline formed by crustal delamination with wedging of a thrust sheet from the east the thrust sheet is exposed in the folded zone of the bowen basin and is characterized by upright nnw trending folds in late permian sediments the folds have a chevron to flattened chevron style and formed mainly by flexural slip at about 60 shortening with detachment from an underlying basement of paleozoic rocks farther east the basement is overlain by pervasively cleaved rocks of the gogango overfolded zone in which structures show a consistent westerly vergence these rocks overlie an inferred passive roof duplex in the underlying basement together the folded zone of the bowen basin and the gogango overfolded zone constitute a foreland fold thrust zone with a shortening of 50 90 km this implies that the new england orogen has been thrust west along a major east dipping detachment

hydraulics of subglacial cavities modele theorique du comportement a l etat stationnaire des cavites remplies d eau et interconnectees sur le lit du glacier

geochemical mineralogical and microbiological characterization of a sulphide bearing carbonate rich gold mine tailings impoundment joutel quebec abstract the results of an integrated geochemical and mineralogical study conducted at the agnico eagle gold mine tailings impoundment joutel quebec are correlated with bacterial populations determined from an enumeration of 3 groups of thiobacilli the tailings were determined to contain approximately 5 wt sulphide s predominantly as pyrite and up to 30 wt carbonate minerals chiefly as dolomite ankerite and siderite the objective of the study was to evaluate the potential for the development of acidic drainage and dissolved metal migration in carbonate rich tailings impoundments and to compare the results of the geochemical and microbiological characterization of the tailings sulphide oxidation reactions have proceeded to a depth of 20 100 cm below the tailings surface pyrrhotite consistently shows more alteration than pyrite and arsenopyrite pyrrhotite is altered mainly through the replacement by goethite the most abundant thiobacilli are neutrophilic bacteria of the thiobacillus thioparus type the maximum most probable number values for these bacteria occur 20 40 cm below the tailings surface a depth that coincides with the disappearance of oxide coatings this observation coupled with the sharp decline in gas phase o 2 concentration suggests that rapid bacterially mediated s oxidation is occurring at this depth the pore water ph throughout the tailings varies between 6 5 and 8 5 no low ph waters were observed in the impoundment these neutral ph conditions are attributed to the effect of acid consuming carbonate mineral dissolution reactions which are also indicated by increased concentrations of mg and ca and alkalinity in the shallow zone of the tailings as a result of these acid neutralization reactions dissolved metal concentrations are low

origin and evolution of high salinity zn pb mineralising fluids in the variscides of belgium high salinity na ca cl rich fluids 20 wt salts in inclusions in gangue and ore minerals from mesozoic mississippi valley type mvt deposits in the verviers synclinorium eastern belgium and in cretaceous vein calcites at the variscan front were investigated by microthermometric and crush leach analysis the mvt deposits formed at temperatures of 110 c while the cretaceous vein calcites were precipitated at temperatures 50 c their cl br content cl br ratio between 246 and 458 suggests that the fluids probably originated by the evaporation of seawater during basin development at the southern margin of the caledonian brabant massif in the late palaeozoic the na ca k content na 29 700 49 600 ppm ca 25 700 46 200 ppm k 1 000 5 620 ppm is similar to that of the mineralising fluids in other pb zn districts interpreted to be of evaporative origin e g newfoundland east tennessee polaris furthermore comparison of the na ca k content of the fluids with that of an evolved evaporitic brine enables the recognition of major water rock interactions that modified the fluid composition it indicates that the ambient fluids participated in the early diagenetic dolomitisation of upper palaeozoic carbonates and also in the albitisation of plagioclase in lower palaeozoic siliciclastics of the caledonian basement illitisation of smectites or dissolution of k feldspar probably controlled the k content of the fluids a model is proposed where the bittern brines migrated down into the deep subsurface because of their density during extension after the variscan orogeny these fluids were finally expelled along extensional faults resulting in the formation of zn pb deposits

fracturing and fluid flow in a sub decollement sandstone or a leak in the basement crack seal texture within fracture cements in the triassic el alamar formation ne mexico shows that the fractures opened during precipitation of quartz cements later overlapping calcite cements further occluded pore space previous workers defined four systematic fracture sets a oldest to d youngest with relative timing constrained by crosscutting relationships quartz fluid inclusion homogenization temperatures are higher within set b 148 20 c than in set c 105 12 c these data and previous burial history modelling are consistent with set c forming during exhumation fluid inclusions in set c quartz have higher salinity than those in set b 22 9 v 14 2 wt nacl equivalent respectively and set c quartz cement is more enriched in 18 o 20 2 v 18 7 vsmow under most assumptions about the true temperature during fracture opening the burial duration the amount of cement precipitated and fluid flow patterns it appears that the fracture fluid became depleted in 18 o and enriched in 13 c this isotopic evolution combined with increasing salinity suggests that throughout fracture opening there was a gravity driven influx of fluid from upsection jurassic evaporites which form a regional decollement fracture opening amid downward fluid motion suggests that fracturing was driven by external stresses such as tectonic stretching or unloading rather than increases in fluid pressure

post variscan hydrothermal vein mineralization taunus rhenish massif germany constraints from stable and radiogenic isotope data abstract post variscan hydrothermal base metal mineralization of the taunus ore district se rhenish massif germany has been studied through combination of stable s c o and radiogenic pb isotope geochemistry based on field and textural observations five hydrothermal mineralization types can be distinguished these are 1 tetrahedrite tennantite bearing quartz ankerite veins 2 quartz veins with pb zn cu ores 3 giant quartz veins 4 metasomatic dolomite in devonian reef complexes and 5 calcite quartz mineralization in devonian reefs the 18ov smow quartz values of base metal veins are in the range of 18 0 21 5 whereas those of giant quartz veins have lower values of 15 9 18 6 this difference reflects the higher fluid fluxes and smaller extent of rock buffering for the giant quartz veins hydrothermal carbonates from the tetrahedrite and pb zn cu veins have variable but distinctly negative 13cv pdb values they can be explained by contributions from fluids that had picked up low 13cv pdb carbon via oxidation of organic matter and from fluids that interacted with devonian reef carbonate having positive 13cv pdb metasomatic dolomite has positive 13cv pdb values that closely reflect those of the precursor limestone by contrast carbonates of calcite quartz mineralization have negative 13cv pdb values which are negatively correlated with the 18o values this pattern is explained by fluid mixing processes where contributions from descending cooler fluids with rather low salinity were dominant the isotope data suggest that tetrahedrite veins pb zn cu veins and giant quartz veins formed from fluid mixing involving two end members with contrasting chemical features this is supported by fluid inclusion data adeyemi 1982 that show repeated alternation between two different types of fluid inclusions which are hotter intermediate to high salinity nacl cacl2 fluids and cooler low salinity nacl dominated fluids the metal rich saline fluids were likely generated at the boundary between the pre devonian basement and the overlying devonian carboniferous nappe pile fault activation resulted in strong fluid focusing and upward migration of large volumes of hot na ca brines which mixed with cooler and more dilute fluids at shallower crustal levels variable contributions from both fluid types local fluid fluxes temperature variations and variations in ph and oxidation state have then controlled the vein mineralogy and metal inventory

origin of the zalesi u ni co as ag bi deposit bohemian massif czech republic fluid inclusion and stable isotope constraints the zalesi vein type deposit is hosted by early paleozoic high grade metamorphic rocks on the northern margin of the bohemian massif the mineralization is composed of three main stages uraninite arsenide and sulfide the mineral assemblages formed at low temperatures 80 to 130 c locally even lower and low pressures 100 bars the salinity of the aqueous hydrothermal fluids 0 to 27 wt salts and their chemical composition vary significantly early fluids of the oldest uraninite stage contain a small admixture of a clathrate forming gas possibly co2 salinity correlates with oxygen isotope signature of the fluid and suggests mixing of brines 18o around 2 relative to standard mean ocean water smow with meteoric waters 18o around 4 smow the fluid is characterized by highly variable halogen ratios molar br cl 0 8 10 3 to 5 3 10 3 molar i cl 5 7 10 6 to 891 10 6 indicating a dominantly external origin for the brines i e from evaporated seawater which mixed with iodine enriched halite dissolution brine the cationic composition of these fluids indicates extensive interaction of the initial brines with their country rocks likely associated with leaching of sulfur carbon and metals the brines possibly originated from permian triassic evaporites in the neighboring polish basin infiltrated into the basement during post variscan extension and were finally expelled along faults giving rise to the vein type mineralization cenozoic reactivation by low salinity low 18o around 10 smow fluids of mainly meteoric origin resulted in partial replacement of primary uraninite by coffinite like mineral aggregates

new insights into the genesis of willemite zn2sio4 from zinc nonsulfide deposits through trace elements and oxygen isotope geochemistry abstract willemite is a common mineral mainly occurring in the so called hypogene nonsulfide zn pb mineralizations deposited from what have been interpreted as high temperature hydrothermal or metamorphic fluids considering that a comprehensive compilation of geochemical data on willemite is currently lacking the aim of this study is to provide evidence for specific geochemical signatures of willemites with contrasting genesis for this work we analyzed a range of specimens taken from the mineralogy collection of the natural history museum in london the specimens are from several deposit types 1 stratiform hypogene deposits franklin and sterling hill usa 2 structurally controlled hypogene deposits star zinc excelsior surprise lusaka area zambia kabwe zambia berg aukas and tsumeb namibia 3 supposedly supergene deposits mumbwa area zambia and altenberg vieille montagne belgium textures and structures of the willemite bearing specimens were initially investigated by scanning electron microscope energy dispersive analysis sem eds trace element concentrations were later measured in situ on selected willemite crystals by laser ablation la icp ms statistical analyses principal component analysis pca multivariate analysis of variance post hoc tukey hsd test conducted on the data obtained by la icp ms showed that statistically significant differences exist between willemites derived from the various considered deposits the high t stratiform willemite samples contain significant amounts of mn and mg and result statistically different from the all the other analyzed specimens structurally controlled hypogene willemites characterized by lower mn and mg concentrations and by higher pb cu as b ge contents are statistically inhomogeneous both at the district and at the deposit scale high t willemite from the lusaka area contains more mn than the low t hydrothermal deposits that show instead higher concentrations of other elements e g pb cu ge among the willemite generations associated with the supposedly supergene mineralizations only the mumbwa willemites form a cluster that is significantly displaced from the other deposits the 18o isotopic compositions match the mentioned trace element distribution willemites with similar origin are characterized by similar oxygen isotopic ratios on the basis of the present work willemite types can be the distinguished as follows high t willemites are characterized by high mn mg concentrations between 100 ppm to unit wt and by low and positive 18o compositions around 3 to 5 v smow low t hydrothermal willemites show mn mg concentrations below 50 ppm associated with high pb cu as ge concentrations above 100 ppm they also have high and positive 18o compositions between 9 and 15 v smow willemites derived from either cold or warm meteoric fluids have possibly low concentrations of the above elements and negative 18o compositions 3 and 9 v smow the supposedly supergene altenberg vieille montaigne willemite having low mn mg and high pb ge as concentrations and showing 18o compositions between 11 and 12 5 should have formed from low t hydrothermal fluids

syn to late orogenic quartz veins marking a retrograde deformation path in a slate belt examples from the high ardenne slate belt belgium abstract an integrated structural petrographic and microthermometric methodology has been applied on syn to late orogenic quartz veins from the high ardenne slate belt belgium to define their relative timing the quartz precipitates which do not show any mutual cross cutting relationships represent the meso scale brittle accommodation during fold initiation amplification and locking crystal plastic deformation structures and p t trapping conditions indicate that the different processes accommodating folding occurred in a progressive manner along a retrograde deformation path associated with the gradual exhumation of the slate belt from ca 7 5 to 6 km depth successive veining occurred from peak metamorphic conditions ca 300 c and 190 mpa measured in extrados veins to subsequent lower p t conditions in the periphery of a lenticular vein ca 275 c and 180 mpa late orogenic saddle reef filling ca 245 c and 160 mpa and the core of a lenticular vein ca 220 c and 150 mpa open cavity growth and fluid assisted brecciation indicate that veining occurred under overpressured fluid conditions it is therefore fair to assume that the high ardenne slate belt acted at least episodically as a mid crustal overpressured fluid reservoir not only in the earliest and latest stages but also during the main stage of orogeny

geochemical constraints on the origin of the kicking horse and monarch mississippi valley type lead zinc ore deposits southeast british columbia canada two mississippi valley type mvt ore deposits kicking horse and monarch have been studied with the aim of comparing the ores at the two localities and to characterize the origin of the mineralizing fluids and the ore formation process es both deposits are hosted by the middle cambrian cathedral formation carbonate host rocks kicking horse on the north and monarch on the south flank of the kicking horse valley near field se british columbia the ore bodies are situated at the transition of western basinal to eastern shallow water strata of the paleo pacific passive margin succession in the cordilleran foreland province of the western canada sedimentary basin both deposits are related spatially to normal faults in both localities the ore minerals are dominated by pyrite sphalerite and galena dolomite minor quartz and calcite are also present in close association with the ores the salinity 21 30 wt nacl eq and homogenization temperatures 63 182 c measured in fluid inclusions in carbonate quartz and sphalerite lie within the typical range of mvt fluid conditions the good stoichiometry 50 53 mol caco3 low 18o values 21 to 14 vienna peedee belemnite and relatively high homogenization temperatures 95 c of the dolomite suggest the dolomites were formed under burial diagenesis the ore forming fluids probably interacted with siliciclastic units based on elevated li contents and 87sr 86sr ratios which are highest in the dolomite type after the main ore stage we propose that the ores formed from the mixing of a downward infiltrating sulfur bearing halite dissolution fluid with an upward migrating metal rich evaporated seawater fluid which had already undergone minor mixing with a dilute fluid

origin of the saline paleofluids in fault damage zones of the jabal qusaybah anticline adam foothills oman constraints from fluid inclusions geochemistry abstract the jabal qusaybah anticline in north oman is affected by syn folding strike slip and extensional fault zones developed during foreland deformation ahead of the northern oman mountains thrust wedge in cenozoic times migration of fluids in fault damage zones is recorded in complex calcite vein networks by employing the microthermometric and compositional microanalysis of the fluid inclusions crush leach two distinct generations of veins have been studied the aim was to determine the source of elevated salinity in fluids involved in their cementation and explain their compositional evolution through fluid rock interactions the ionic ratios na br and cl br obtained from crush leach analysis give supporting evidence that the elevated salinity of fluid inclusions in both vein groups originated from an evaporated seawater beyond the onset of halite precipitation residual brines the results reveal a gradual increase in salinity of the fluids f cl molar ratios as well as li cl molar ratios these results imply the progressively increasing contribution of evaporitic residual brines and fluids that interacted with or were derived from siliciclastic rocks we suggest that the most likely origin of the former fluids is provided by residual brines associated with precipitation of the ara evaporites cambrian the regional driving mechanism for such a significant fluid migration is believed to be compaction driven upward flow that was channeled into faults and fractures during major deformational events

assessment of solute and suspended sediments acquisition processes in the bara shigri glacier meltwater western himalaya india various physico chemical parameters of meltwater samples from bara shigri glacier collected during 2012 2013 were analysed to understand the dissolved ion chemistry and solute acquisition processes regulating major ion chemistry of the study area ionic dominance of anions followed the trend as hco3 so4 2 cl no3 whereas ionic dominancy of cations varied as ca2 mg2 k na for both the years high share of ca mg in the total cations and also dominancy of ca mg over na k for both the years demonstrate that solute acquisition processes in the meltwater of bara shigri glacier are mainly governed by the weathering of carbonates the piper plot identified ca hco3 as the dominant water type followed by caso4 type of water in the study area the average value of partial pressure of carbon dioxide pco2 for meltwater of the bara shigri glacier was 10 2 6 atm in 2012 and 10 2 3 atm in 2013 and were higher than the pco2 value of atmosphere 10 3 5 atm it indicates that the meltwater is in disequilibrium with respect to the atmosphere contents of suspended sediment in the meltwater were 1432 mg l in july and 596 mg l in september 2012 whereas in 2013 suspended sediment contents were 1093 mg l in august and 425 mg l in september following discharge pattern of the bara shigri glacier we found that bara shigri and gangotri glaciers demonstrate the higher rate of regional melting

geochemistry of highly saline fluids in siliciclastic sequences genetic implications for post variscan fluid flow in the moravosilesian palaeozoic of the czech republic ubiquitous post variscan dolomites occur in zn pb cu veins at the nizk jesenik mountains and the upper silesian basin lower and upper carboniferous siliciclastics at the eastern part of the bohemian massif crush leach stable isotope oxygen and carbon and microthermometry analysis of the fluid inclusions in dolomites enable understanding the geochemistry origin and possible migration pathways of the fluids homogenisation temperatures of fluid inclusions range between 66 and 148 c with generally higher temperatures in the nizk jesenik mountains area than in the upper silesian basin the highest homogenisation temperatures up to 148 c have been found near major regional faults and the lowest in a distant position or at higher stratigraphic levels highly saline 16 6 28 4 eq wt nacl h2o nacl cacl2 mgcl2 fluids occur in inclusions na cl br systematics of trapped fluids and a calculated oxygen isotopic fluid composition between 0 9 and 3 0 v smow indicate that the fluid was derived from evaporated seawater stable isotopic modelling has been used to explain stable isotopic trends isotopic values 13c 6 0 2 0 v pdb 18o 15 5 22 5 v smow of dolomites resulted from fractionation and crystallisation within an open system at temperatures between 80 and 160 c rock buffering explains the isotopic composition at low w r ratios organic matter maturation caused the presence of isotopically light carbon in the fluids and fluid rock interactions largely controlled the fluid chemistry k li br and na contents k cl i cl and li cl molar ratios the fluid chemistry reflects well the interaction between the fluid and underlying limestones as well as with clay and organic rich siliciclastics no regional trends in temperature or fluid geochemistry favour a fluid migration model characterised by an important vertical upward migration along major faults a permeable basement and fractured sedimentary sequence enhanced the general nature of the fluid system fluid characteristics are comparable with the main post variscan fluid flow systems in the polish cracow silesian ore district and german sedimentary basins

fossil travertine system and its palaeofluid provenance migration and evolution through time example from the geothermal area of acquasanta terme central italy abstract the geothermal area of acquasanta terme has often been studied for its active and fossil travertine deposits to elucidate fluid origin geodynamic and hydrological setting even though present day thermal springs are usually used to obtain most information the three travertine terraces bordering the tronto river contain a plethora of information a combination of elemental and isotope analyses 18o 13c and 87sr 86sr ratio fluid inclusion microthermometry and u th dating is used to verify the hydrogeology and its timing these analyses point out two fluid reservoirs with distinctly different fluids one with low salinity of 0 7 wt nacl eq and another with 28 5 wt nacl eq which corresponds to the fluid composition of present day spring fluids furthermore it is demonstrated that geothermal sources were intermittently active in the past 221 ka mainly during uneven numbered marine isotope stages which are related to humid interglacial periods and resulted in three different travertine terraces around 210 5 126 5 and 36 5 ka accordingly an uplift rate for this area could be estimated at around 1 mm ka the fluids were tapped at a depth of approximately 3 km in the tectonized cataclastic fraction of the triassic anidriti di burano formation the calcare cavernoso formation and are originally meteoric based on geochemical evidence of a uniform 87sr 86sr ratio of 0 707914 0 00019 and a 18oaragonite value of 11 90 0 34 which has been depressed by elevated precipitation temperatures between 22 2 and 50 c the characterization and dating of fossil travertine deposits gives valuable data providing insights in long term fluid flow and orogenic uplift rates adding valuable information to present day spring fluid characterization

petrology of two tertiary oil shale deposits from queensland australia sediments from two queensland tertiary lacustrine oil shale deposits the lowmead and duaringa basins have been petrologically characterized from standard x ray powder diffraction analyses backscattered electron microscopy and electron microprobe data the results presented illustrate the potential of backscattered electron imagery for the study of diagenesis in fine grained organic rich sediments the lowmead formation consists of lamosites claystones and brown coals deposited in freshwater lacustrine and fringing peat swamp environements their dominant constituents are kaolinite and quartz with opaline silica and siderite important as eogenetic phases despite its similar geological setting the duaringa formation contains a more varied lithological assemblage with less organic matter being preserved freshwater lacustrine claystones and lamosites are interbedded with carbonate sediments deposited during periods of saline alkaline conditions in the lake within these carbonate sediments major growth of eogenetic mineral phases occurred principally dolomite and analcite as in the lowmead basin siderite is an important eogenetic phase in the duaringa formation two types of sideritic ironstone band occur throughout both basins sphaerosiderites within claystone coal sediments and fine grained bands of siderite within lamosites the bulk mineralogy of the siliciclastic detritus shows no significant trends with depth within either basin

petroleum migration fluid mixing and halokinesis as the main ore forming processes at the peridiapiric jbel tirremi fluorite barite hydrothermal deposit northeastern morocco the jbel tirremi fluorite barite sulfide deposit in northeastern morocco is hosted in a jurassic aged structurally high carbonate platform known as the jbel tirremi dome the host rocks consist of unmetamorphosed flat lying early jurassic dolomitized limestones locally intruded by eocene lamprophyre dikes the orebodies consist mostly of fluorite and barite and occur as open space fillings and partial to massive replacement of the enclosing medium to coarse grained dolomitized limestones the ore mineralogy is dominated by fluorite of different colors and habits barite and to a lesser extent sulfides rare earth element compositions along with fluid inclusion halogen and isotopic data suggest that the fluorite barite mineralization and the spatially associated eocene alkaline magmatism are petrogenetically unrelated pointing instead to the regional circulation of hydrothermal basinal brines mixed to various degrees with meteoric water in a dominantly closed rock buffered system at progressively higher temperatures and fluid rock ratios in this respect fluid inclusion microthermometric measurements show that the ore bearing hydrothermal system developed in two separate stages of fluorite barite mineralization as also revealed by isotopic data both stages precipitated from saline fluids at shallow crustal levels i e 82 degrees c and possibly up to 218 degrees c whereas in the second stage the mineralizing fluid had a similar temperature range but lower salinities similar to 20 10 wt nacl equiv the recorded high salinities are interpreted to represent the involvement of a mixture of halite dissolution water and evaporated seawater component oxygen delta o 18 21 7 to 29 6 0 v smow and carbon delta c 13 7 9 to 0 2 0 v pdb isotope data along with strontium sr 87 sr 86 0 70300 070789 and lead pb 206 pb 204 17 961 20 96 pb 207 pb 204 15 511 15 697 pb 208 pb 204 37 784 39 993 isotope ratios suggest the involvement of a mixture of oil bearing fluids basinal brines and meteoric fluids that interacted extensively with the early jurassic host carbonates the underlying triassic salt bearing diapir associated siliciclastic rocks and the highly fractionated and greisenized hercynian granitic crystalline basement resulting in the release of fluoride metals and other constituents to form the jbel tirremi deposit petroleum bearing fluid released from overpressured portions of the guercif basin at lithostatic pressures and bittern brines dominated the first stage of mineralization mixing of saline oxidized cacl2 and sulfate rich bittern brine with oil bearing fluid resulted in fluorite precipitation of stage i conversely during the second stage of mineralization the hydrothermal system was open to the influx of oxidized meteoric water as a consequence of the upward migration of the triassic salt bearing diapir and associated pressure decrease the shift from stage i to stage ii is associated with the evolution of the system from lithostatic to mostly hydrostatic pressure conditions stage i mineralization is thought to have occurred during the late miocene in response to rapid sedimentation and high subsidence rates and subsequent hydrocarbon migration associated with the outward migration of the rif thrust front conversely stage ii mineralization occurred coevally with the uplift phase during tortonian time

the origin of intraplate deformation in the atlas system of western and central algeria from jurassic rifting to cenozoic quaternary inversion abstract analysis of petroleum exploration data supplemented by paleostress data enabled discussion of the origin of the deformation in the western and central saharan atlas algeria this intraplate area has recorded the breakup of pangea late triassic the opening of the maghrebian tethys since the dogger and subsequently its closure oligocene to present however the two periods of strong coupling between europe and africa late lutetian and pleistocene which correspond to rapid uplifts of the atlas system and important deformations are not collision related they can be correlated to the beginning and the end of the development of the western mediterranean sea

hydrogeochemistry and quality of groundwater of coastal unconfined aquifer in amol ghaemshahr plain mazandaran province northern iran groundwater of the unconfined aquifer 1 100 sq km of a two tier coastal aquifer located in the amol ghaemshahr plain mazandaran province northern iran is classified into fresh and brackish water types fresh groundwater fgw samples n 36 are characterized by ca2 na mg2 k and hco3 cl so4 2 no3 spearman s rank correlation coefficient matrices factor analysis data values of the c ratio av 0 89 and cai and values of the molar ratios of ca2 hco3 ca2 so4 2 mg2 hco3 and mg2 so4 2 indicate that the ionic load in the fgw is derived essentially from carbonic acid aided weathering of carbonates and aluminosilicates saline sea water trapped in the aquifer sediments now admixed with the groundwater and ion exchange reactions values of the cai and na cl molar ratio suggest that the part of the ca2 mg2 content in 23 fgw samples is derived from clay minerals of the aquifer matrix and part of the na content in 20 12 and 3 fgw samples is derived respectively from alkali feldspar weathering clay minerals of the aquifer matrix and rain water and or halite brackish groundwater bgw samples n 4 contain cl as the dominant anion and their average total ionic concentration 38 65 meq l is 1 79 times higher than that of the fgw samples 21 50 meq l bgw pockets were generated by non conservative mixing of fgw with the upconed saline water from the underlying saline groundwater zone of the semi confined aquifer along bore wells involved in excessive extraction of groundwater from the unconfined aquifer groundwater belongs essentially to high salinity low sodium irrigation water class

isotope major minor and trace element geochemistry of late magmatic fluids in the peralkaline ilimaussaq intrusion south greenland abstract the persodic 1 16 ga old ilimaussaq intrusion consists of alkali granites syenites and agpaitic nepheline syenites these rocks are cut by late magmatic veins and lenses consisting of albite aegirine ussingite na2alsi3o8 oh fluorite and occasionally quartz oxygen isotope compositions of quartz indicates both orthomagmatic 18oqtz 8 5 and country rock influenced 18oqtz 10 origin while albite and aegirine do not contain fluid inclusions suitable for investigations ussingite contains secondary hydrocarbon fluid inclusions fluorite contains brine inclusions of primary and secondary origin with up to 26 3 wt naclequiv and quartz contains predominantly secondary brine inclusions with up to 29 7 wt naclequiv or ch4 h2o nacl mixtures these fluids are interpreted to reflect fluids in equilibrium with late stage melts at ilimaussaq at 450 c the carbon and hydrogen isotope composition of ch4 in ussingite 13c 6 to 3 d 121 is indicative of a magmatic abiogenic origin however the isotopic composition of ch4 in fluid inclusions in quartz veins resembles the signature of thermogenic ch4 13c 43 to 23 d 176 to 121 but the higher hydrocarbons are mostly 13c depleted in relation to ch4 up to 7 3 which is typical of abiogenically derived hydrocarbons ion chromatography of fluid inclusion leachates from the late stage veins reveals cl br ratios of 100 as such values seem to be typical of peralkaline magmatic rocks at least in the gardar province of south greenland it is suggested that this ratio is typical of gardar magmatic fluids and may be characteristic of the cl br ratio of the lithospheric mantle from which these alkaline melts are derived

sedimentary basin inversion and intra plate shortening abstract sedimentary basin inversion the shortening of formerly extensional basins is accommodated mainly by compressional reactivation of extant faults and fractures across a wide range of scales as such inversion is a large scale manifestation of byerlee friction the dynamic criterion for fault reactivation governing the effective shear strength of the shallow crust basin inversion generates distinctive deformational architecture and it is implicated strongly in sedimentary basin exhumation as a principal source of horizontal stress inversion drives significant sedimentary porosity reduction and resultant fluid flow upper crustal deformation is critically dependent on fluid overpressure i e pore fluid pressures greater than would be calculated from a hydrostatic gradient and perhaps more than in any other tectonic setting overpressures are potentially large during sedimentary basin inversion this review therefore includes discussion of the role of fluid overpressure in inversion and the evidence for it collectively inversion has profound implications good and bad for the prospectivity of many petroliferous sedimentary basins thus recognizing the evidence for basin inversion quantifying its magnitude and understanding the mechanisms that accommodate inversion and other phenomena affected by it have become essential components of the basin analyst s remit

change of tectono stratigraphic regime in the australian plate during the 99 ma mid cretaceous and 43 ma mid eocene swerves of the pacific the clockwise bend at 99 ma mid cretaceous in linear volcanic chains in the tropical pacific coincides with a change from pre 99 ma head on chilean type subduction of the pacific plate beneath eastern gondwana to 99 43 ma sinistral oblique mariana type subduction and strike slip breakup by simple sea floor spreading between australia and antarctica and by backarc spreading in the southwest pacific the 99 ma breakup of australia from antarctica is documented by a mid cretaceous unconformity this tectono stratigraphic change founded modern australia with a mountain chain along an upper plate margin in the east and lowlands on the lower plate margin in the south the counterclockwise bend at 43 ma mid eocene the emperor hawaiian bend coincides with the onset of structure in the challenger rift of new zealand the eromanga cooper basin of central australia and the oil shale grabens of coastal queensland

fluid inclusions and ore precipitation mechanism in the giant xikuangshan mesothermal antimony deposit south china conventional and infrared microthermometric constraints abstract the giant xikuangshan antimony deposit located in the xiangzhong central hunan basin south china is the largest antimony deposit in the world stibnite is the predominant ore mineral and gangue minerals consist of quartz calcite fluorite and barite the ore mineral assemblages include early stage quartz stibnite fluorite quartz stibnite and barite quartz stibnite and late stage calcite stibnite in spite of numerous research works on the xikuangshan deposit during the past several decades the signatures of the ore forming fluids and the ore precipitation mechanisms are poorly constrained in order to characterize the fluids responsible for antimony mineralization and ascertain the genetic processes in the xikuangshan ore district conventional and infrared microthermometric measurements have been performed in this study on fluid inclusions hosted in transparent minerals quartz fluorite and barite and opaque stibnite respectively four types of fluid inclusions were identified for the early stage mineralization based on their phase assemblages including type i pure liquid inclusions type ii two phase liquid rich aqueous inclusions type iii two phase vapor rich aqueous inclusions and type iv pure vapor inclusions stibnite only contains type i and type ii inclusions while all types of fluid inclusions are common in the gangue minerals the homogenization temperatures and salinities of fluid inclusions in stibnite and associated gangue minerals in this ore district display significant differences fluid inclusions in stibnite exhibit relatively low homogenization temperatures 112 323 c and higher salinities 0 2 15 4 wt nacl equiv than inclusions in coexisting gangue minerals 119 366 c 0 2 4 2 wt nacl equiv usually about 50 c less than the intergrown gangue minerals according to the petrography of fluid inclusions and the relationship between their homogenization temperature and salinity it was concluded that stibnite and gangue minerals in the xikuangshan ore district are not co genetic instead they were deposited from two distinctly different hydrothermal solutions fluid mixing was responsible for stibnite precipitation but the precipitation of gangue minerals resulted from fluid boiling due to an abrupt drop in pressure the xikuangshan deposit is a typical example of mesothermal deposits rather than an epithermal deposit as previously considered

an evaluation of trace element release associated with acid mine drainage the determination of trace element release from geologic materials such as oil shale and coal overburden is important for proper solid waste management planning the objective of this study was to determine a correlation between trace element residency and concentration to trace element release using the following methods 1 sequential selective dissolution for determining trace element residencies 2 toxicity characteristic leaching procedure tclp and 3 humidity cell weathering study simulating maximum trace element release two eastern oil shales were used a new albany shale that contains 4 6 percent pyrite and a chattanooga shale that contains 1 5 percent pyrite each shale was analyzed for elemental concentrations by soluble adsorbed organic carbonate and sulfide phases all leachates were analyzed to determine total trace element concentrations

the influence of pre existing thrust faults on normal fault geometry in nature and in experiments relations between normal faults and pre existing thrust faults are classically described in terms of three basic situations normal faults can cross cut thrust faults they can branch out from thrust faults at depth on a de collement level or they can entirely reactivate thrust planes the mechanical aspects of these types of interaction were studied by analogue modelling in which sand simulates the brittle rocks and silicone putty an interlayered de collement the models underwent compression producing thrust faults with variable dips followed by extension three possible ways of interaction are described here a no interaction occurs in the case of low dip thrust faults 32 1 and normal faults are developed independently displaying a listric geometry b branching at depth on the de collement level occurs when dip of the thrust faults reaches 32 1 in this case the dip of the normal faults whose geometry becomes planar decreases with increasing thrust dip we suggest that this change in dip of normal faults depends upon the rotation of stress tensor axes along the pre existing fault zone where a drop in the friction coefficient is likely to occur c reactivation occurs in brittle material when dip of the pre existing fault exceeds 41 1

chemical models of solute acquisition in glacial melt waters chemical models for the evolution of bulk melt waters can be constructed by assuming that rock mineral weathering and solute acquisition are controlled by carbonate equilibria different open and closed system models are defined by variations in the rates of weathering relative to the rate of hydrogen ion supply by the dissolution and dissociation of co2 and can be recognized by characteristic ph and relationships the observed and inferred compositions of englacial and subglacial melt suggest that mixing is unlikely to be conservative and that closed system conditions result where post mixing weathering reactions occur the final composition of bulk melt waters is determined by the mixing ratio between englacial and subglacial melt the extent of post mixing evolution and opportunity for mixing with ground waters or re equilibration with the atmosphere

the composition of the englacial and subglacial component in bulk meltwaters draining the gornergletscher switzerland a new method of hydrograph separation for bulk meltwaters draining alpine glaciers is proposed it is based on the two component subglacial and englacial mixing model of collins 1978 but allows the composition of the subglacial component to vary between ascending and descending lines of the hydrograph the mean englacial component can be derived from linear relationships between sulphate concentrations and other ions in bulk meltwaters on certain occasions during the ablation season the maximum concentration of ions in the subglacial component can be determined from the linear relationship between bulk meltwater sulphate concentrations and discharge the bulk discharge is then a direct measure of the mass fraction of the englacial component at maximum discharge the contribution of the subglacial component approaches zero which has implications for the storage and mixing of waters in subglacial reservoirs further the subglacial component is not of constant composition and may itself be a mixture of dilute supraglacial and concentrated subglacial water

diurnal hydrological physicochemical controls and sampling methods for minor and trace elements in an alpine glacial hydrological system summary we present diurnal i 0 45 and 0 1 m pore size filtered and ii operationally defined labile particulate associated major minor and trace element concentrations and fluxes in glacial outflow waters draining haut glacier d arolla switzerland we use speciation modelling phreeqci and water suspended sediment interaction experiments are utilised under conditions analogous to the subglacial channellised hydrological system in order to assess controls on and the most suitable sampling methods to investigate short term variations in the mode of major minor and trace element species export from a glacierised headwater catchment 0 45 m pore size filtered major ions sr and u are exported in glacial outflow waters predominately as mobile monovalent or divalent ions or as carbonate complexes and are controlled by hydrological variations over diurnal cycles exhibiting an inverse concentration with increasing meltwater discharge conversely 0 45 m pore size filtered concentrations of most minor and trace elements e g fe mn co ba and pb exhibit variations that are not strongly inter correlated with meltwater discharge or suspended sediment concentrations ssc over diurnal periods the use of 0 45 and 0 1 m pore size filter membranes indicates that significant colloidal material is not passing through the 0 45 m pore size filters and these unsystematic variations are not a result of colloid measurement speciation modelling applied to meltwaters and observations during water rock interaction experiments suggest that these unsystematic temporal variations reflect physicochemical controls this includes sorption and the oversaturation and precipitation of fe and al oxi hydroxides and the co precipitation of other species diurnal ph variations appear important in controlling such short term physicochemical controls which limits such species use for hydrological investigations the percentage of total elemental fluxes exported as the labile particulate associated flux paf for each minor and trace element changes dramatically between and during the diurnal cycles reflecting species specific sensitivity to hydrological and physicochemical controls hydrological interpretations of hydrochemical data must be made carefully when using chemical determinations by icp ms since we demonstrate that measurements will comprise of any material that passes through the filter this can lead to higher concentration measurements than if determined by ion chromatography which measures truly ionic dissolved species

debris entrainment at the ice bedrock interface in sub freezing temperature conditions terre adelie antarctica the debris rich ice from the bottom 6 m of the 82 m deep caroline coastal antarctic record of last interglacial natural environment ice core reaching bedrock and from five 2 m long surface cores at moraine prudhomme in terre adelie antarctica is described and compared to debris laden ice from the core drilling site d10 isotopic total gas content co2 concentration and sem investigations of embedded particles together with ice textures and fabrics rule our pressure melting regelation around bed obstacles or freezing on as possible mechanisms for the debris entrainment at the ice bedrock interface it is suggested that the debris entrapment by purely mechanical means e g shearing is an efficient process in forming basal ice layers bil at sub freezing temperatures from authors

episodic behavior of gondwanide deformation in eastern australia insights from the gympie terrane the mechanisms that drove permian triassic orogenesis in australia and throughout the cordilleran type gondwanan margin is a subject of debate here we present field based results on the structural evolution of the gympie terrane eastern australia with the aim of evaluating its possible role in triggering widespread orogenesis we document several deformation events d d in the gympie terrane and show that the earliest deformation d occurred only during the final pulse of orogenesis 235 230 ma within the broader gondwanide orogeny in addition we found no evidence for a crustal suture suggesting that terrane accretion was not the main mechanism behind deformation rather the similar spatiotemporal evolution of permian triassic orogenic belts in australia antarctica south africa and south america suggest that the gondwanide orogeny was more likely linked to large scale tectonic processes such as plate reorganization in the context of previous work our results highlight a number of spatial and temporal variations in pulses of deformation in eastern australia suggesting that shorter cycles of deformation occurred at a regional scale within the broader episode of the gondwanide orogeny similarly to the cenozoic evolution of the central and southern andes we suggest that plate coupling and orogenic cycles in the late paleozoic to early mesozoic gondwanide orogeny have resulted from the superposition of mechanisms acting at a range of scales perhaps contributing to the observed variations in the intensity timing and duration of deformation phases within the orogenic belt

the evolution of a late cretaceous cenozoic intraplate basin duaringa basin eastern australia evidence for the negative inversion of a pre existing fold thrust belt the duaringa basin in eastern australia is a late cretaceous early cenozoic sedimentary basin that developed simultaneously with the opening of the tasman and coral seas the basin occurs on the top of an earlier permian triassic fold thrust belt but the negative inversion of this fold thrust belt and its contribution to the development of the duaringa basin are not well understood here we present geophysical datasets including recently surveyed 2d seismic reflection lines aeromagnetic and bouguer gravity data these data provide new insights into the structural style in the duaringa basin showing that the nnw striking ne dipping deep seated duaringa fault is the main boundary fault that controlled sedimentation in the duaringa basin the major activity of the duaringa fault is observed in the southern part of the basin where it has undergone the highest amount of displacement resulting in the deepest and oldest depocentre the results reveal that the duaringa basin developed in response to the partial negative inversion of the pre existing permian triassic fold thrust belt which has similar orientation to the extensional faults the duaringa fault is the negative inverted part of a single triassic thrust known as the banana thrust furthermore small syn depositional normal faults at the base of the basin likely developed due to the reactivation of pre existing foliations accommodation faults and joints associated with permian triassic folds in contrast to equivalent offshore basins the duaringa basin lacks a complex structural style and thick syn rift sediments possibly because of the weakening of extensional stresses away from the developing tasman sea

massive hydrothermal dolomites in the southwestern cantabrian zone spain and their relation to the late variscan evolution abstract large scale massive burial dolomitization affected upper carboniferous carbonates of the southwestern variscan cantabrian zone spain replacive and void filling dolomites formed and were post dated by calcite cementation the process of dolomitization was due to the circulation of hypersaline and hydrothermal marine derived brines controlled by rock anisotropies the dolomites probably formed in early permian time during post thrusting orocline formation in an extensional setting lithospheric delamination induced increased heat flow and allowed thermal convection of the fluids the dolomites from the cantabrian zone are excellently exposed and represent an interesting outcrop analogue for hydrocarbon reservoirs elsewhere in comparable geotectonic settings of the european variscan orogen large masses of similar dolomites could have formed if mg rich brines were available

the development of a triassic fold thrust belt in a synclinal depositional system bowen basin eastern australia a synclinal depositional system in eastern australia taroom trough bowen basin was affected by folds and thrusts but the structural style associated with this deformation is not fully understood using gridded aeromagnetic data and 2d seismic reflection data we conducted a structural analysis that unravels the geometry and kinematics of major thrust faults in the eastern central part of the taroom trough major structures are the east dipping cockatoo miles and taroom faults and west dipping burunga and glebe faults our results show that west dipping thrusts have a listric geometry that produced gentle hanging wall anticlines a north striking gentle symmetric syncline and anticline pair is also observed to the west of the burunga fault these observations indicate that the deformation in the central taroom trough was controlled by decollements in the basement rocks the decollements and resultant structures were likely developed in response to mild contraction of the synclinal depositional system during the last phase of the permian triassic hunter bowen orogeny hbo the last phase of the hbo also resulted in the reactivation of pre existing east dipping cockatoo and miles faults the bulk longitudinal strain however in the eastern central bowen basin was low 2 8 shortening with the deformation restricted to a relatively narrow zone in contrast deformation in the northern bowen basin was distributed in a wider fold thrust belt that accommodated a higher amount of strain this change in the pattern of deformation along the eastern part of the bowen basin could possibly be explained by along strike variations in the rates of trench advance

late variscan fluid migration at the variscan thrust front of eastern belgium numerical modelling of the palaeothermal and fluid flow field modelling of the palaeothermal field at the variscan thrust front in eastern belgium indicates significant temperature modifications by late variscan palaeofluids migrating from internal to peripheral parts of the orogen a detailed set of calibration data chlorite geothermometry microthermometry organic rank gives evidence of temporary palaeotemperature variations at the variscan thrust front obviously connected to the migration of hot low saline palaeofluids these thermal events likely enhanced organic maturation vitrinite reflectance conodont alteration of devonian and carboniferous sediments which accumulated long before the variscan orogeny occurred numerical simulation 2d finite element method of the palaeothermal field includes coupled heat transport by thermal conduction and fluid flow palaeothermal scenarios yield successive palaeotemperatures 200 300 c which are indicated by the control data due to relatively short term fluid ascent along the detachment and the imbricate thrust front the simulated flow velocities are up to tens of metre per year lasting several thousand years non steady state solution in the scenarios modelled these thermal events occur in a realm of enhanced bulk temperatures due to elevated basal heat flow densities 90 mw m 2 and an additional burial depth of some kilometres the simulated temperature enhancement due to fluids ascending at the variscan thrust front is several tens degrees the scenarios demonstrate long distance fluid migration during or after deformation of the palaeozoic basin and its effect on the palaeothermal field

the role of pre existing thrust faults and topography on the styles of extension in the gran sasso range central italy abstract structural analysis and field mapping together with simple geometrical and flexural elastic models document that two styles of quaternary extensional tectonics characterized the gran sasso range central apennines italy in the western part of the range extension took place on 10 15 km long range front normal faults with associated 600 1000 m high escarpments showing evidence of late glacial holocene activity this topography has been reproduced with a thin elastic plate subjected to the isostatic forces induced by the movement along high angle 55 65 planar normal faults in the eastern part of the belt extension occurred on shallow dipping normal faults 30 35 which reactivated progressively deeper pre existing thrusts in this area antithetic domino faults formed to accommodate the mechanical adjustment of the hanging wall over a variably dipping major fault surface the eastward increase in shortening due to the earlier compressional phase documented in the gran sasso belt by previous authors accounts for the more developed zones of weakness and high topographic relief in the eastern sector this setting could explain the different styles of extension and the more advanced northeastern limit of normal faulting in the eastern sector this work suggests that normal faults can originate either with low or high angle geometry in the upper crust according to the pre existing tectonic setting and that topography could be important in controlling the geometry and pattern of migrating normal faulting

the impact of supraglacial debris on proglacial runoff and water chemistry debris is known to influence the ablation topography and hydrological systems of glaciers this paper determines for the first time how these influences impact on bulk water routing and the proglacial runoff signal using analyses of supraglacial and proglacial water chemistry and proglacial discharge at miage glacier italian alps debris does influence the supraglacial water chemistry but the inefficient subglacial system beneath the debris covered zone also plays a role in increasing the ion contribution to the proglacial stream daily hydrographs had a lower amplitude and later discharge peak compared to clean glaciers and fewer diurnal hydrographs were found compared to similar analysis for haut glacier d arolla we attribute these observations to the attenuating effect of the debris on ablation smaller input streams on the debris covered area a less efficient subglacial system and possible leakage into a raised sediment bed beneath the glacier strongly diurnal hydrographs are constrained to periods with warmer than average conditions average weather conditions result in a hydrograph with reverse asymmetry conductivity and discharge commonly show anti clockwise hysteresis suggesting the more dilute rapidly routed melt component from the mid glacier peaks before the discharge peak with components from higher up glacier and the debris covered areas arriving later at the proglacial stream the results of this study could lead to a greater understanding of the hydrological structure of other debris covered glaciers with findings highlighting the need to include the influence of the debris cover within future models of debris covered glacier runoff

temperature dependence of silicate weathering in nature how strong a negative feedback on long term accumulation of atmospheric co2 and global greenhouse warming estimation of the temperature dependence of natural feldspar weathering in two catchments at different elevations yields an apparent arrhenius activation energy of 18 4 kcal mol 77 0 kj mol much higher than most laboratory values this finding supports recent suggestions that hydrolytic weathering of silicate minerals may consume carbonic acid and thereby remove atmospheric carbon dioxide more rapidly with increasing temperature than previously thought this result provides a stronger negative feedback on long term greenhouse warming than has been assumed in most models of global carbon cycling the present estimate was determined from the ratio of feldspar weathering rates determined by geochemical mass balance in the southern blue ridge mountains of north carolina united states temperature a function of elevation is the only factor that differs between the two catchments parent rock type aspect hillslope hydrology and vegetation type and successional stage are the same in both

metallogenesis at the terramonte pb zn ag quartz vein portugal geological mineralogical and geochemical evidences abstract the pb zn ag quartz vein from terramonte cuts the neoproterozoic cambrian schist greywacke complex this orebody was partially exploited the paragenetic sequence consists of four stages containing quartz accompanied mainly by arsenopyrite and pyrite in the first stage sphalerite in the second stage galena showing many inclusions of several sulphosalts in the third stage and carbonates in the fourth remobilization stage several sulphide and sulphosalt grains are oscillatory zoned the chemical distinction between lighter and darker zones in backscattered images of arsenopyrite pyrite sphalerite and freibergite is due to substitutions in the mineral lattices but the distinction between these zones in semseyite is due to a higher pb content and a lower sb content in the lighter zone than in the darker zone and the metal and metalloid are the main constituents in the solid solution but are not correlated the sb ag and bi substitute for pb in galena but did not cause any zoning ore deposition was possible due to mixing of a hypersaline fluid with up to 26 wt nacl equivalent and occasionally with cacl2 up to 17 wt which carried the metallic content of the fluid with an extremely low salinity fluid of presumed meteoric origin that percolated down into the basement the metals could have been leached from a mixture of mainly metasediments and also previous sb au deposits by fluids that acquire high salinity in one of two probable ways leaching of salt beds or following seawater evaporation the entire mineralizing event probably occurred at a relatively low temperature possibly between 120 and 230 c remobilization of pb zn ag as sb and cu will be due to the tectonic evolution of the opening of the atlantic ocean this vein is probably of alpine age

rates of chemical denudation and co2 drawdown in a glacier covered alpine catchment solute fluxes from a glacier covered alpine catchment are partitioned into components derived from sea salt acid aerosol dissolution of atmospheric co2 and crustal weathering the bulk of solute is crustally derived coupled sulfide oxidation and carbonate dissolution so cd and carbonation of carbonate minerals generate approximately equal amounts of solute chemical denudation constitutes 1 5 of solid denudation but is significantly higher than the continental average co2 drawdown by weathering reactions varies directly with discharge and suspended sediment load and inversely with meltwater p co2 if it is generally true that flushing rates control co2 drawdown in glacier covered catchments then glacially driven chemical weathering could be a significant factor in carbon cycling and climate change on glacial interglacial time scales

post rift compressional reactivation potential of passive margins and extensional basins poly phase deformation of a compressional nature is a common feature in the post rift evolution of passive margins and rifts the compressional mode of deformation in these sedimentary basins originally formed by extension in an intraplate setting is characterized by a spectrum of spatial wavelengths spanning several tens of kilometres up to several hundreds of kilometres the actual mode of compressional deformation appears to be strongly affected by the rheological structure of the underlying lithosphere the level of the regional intraplate stress field and the geometry of the rifted basin configuration prior to late stage compressional reactivation the interplay of plumes and intraplate compressional deformation can lead to temporal transitions from basin inversion to lithospheric folding these modes of deformation lead to substantial differential vertical motions late stage anomalies in subsidence and uplift patterns the development of innovative combinations of numerical and analogue modelling techniques is the key to differentiating different modes of compressional deformation of passive margins and extensional basins the geological society of london 2008