refinements for footwall red bed diagenesis in the sediment hosted stratiform copper deposits model the emplacement of copper in sediment hosted stratiform copper deposits requires the circulation of a low temperature chloride rich brine in rift filling footwall red beds probably driven by meteoric recharge in adjacent highlands the descending oxygen rich meteoric water may become saline probably by leaching of footwall evaporites or possibly by mixing with brines draining down from contemporaneous evaporite pans and evolve toward a moderately oxidized brine as oxygen is consumed during the diagenetic reddening of the initially nonred coarse grained clastic rift sediments under these conditions the pore solution attains its maximum ability to leach and transport trace amounts of copper from the red beds sediment hosted stratiform copper deposits may form where the brine crosses a redox boundary into reduced sulfide rich gray beds with further consumption of oxygen during reddening the brine may become highly reduced and able to take iron into solution possibly explaining synsediment hosted stratiform copper iron oxide alterations and deposits the timing of copper deposition is clearly linked to the diagenetic reddening of immature footwall sediments in rift basins a process considered to extend over millions of years

a seismically controlled seal breach in a major hydrocarbon province a study from the mauddud formation in the bahrah field kuwait abstract the mauddud formation a late albian aged carbonate oil reservoir is one of the main oil producers in kuwait however it exhibits unreliable oil production from the bahrah field the mauddud formation in the bahrah field is divided into two sub structures by a series of e w faults and shows a slight degradation in oil quality 5api within the up dip structure intersections of the e w faults with nw se faults are associated with deep seated seismic pipes which culminate in pull up features creating the overlying sag like features additionally the mauddud formation shows evidence of baroque saddle dolomite in fracture cements and replacing clasts the baroque dolomite have 3he 4he ratios 0 3 times higher than atmospheric values taken together this seismic and petrographic evidence suggests that the mauddud formation experienced an ingress of radiogenic crustal fluids potentially sourced from the basement seismic pipes therefore are interpreted to be the product of the upward movement of hydrothermal fluids that breach seal rocks causing oil to escape and subsequent calcite cementation an integrated map of a basement magnetic anomaly and current exhalative features on the present day surface shows evidence of a relationship with fault locations on the level of the mauddud formation that were rejuvenated and associated with the remigration of oil this study provides an exceptional example of a seal breach in one of the world s most prolific hydrocarbon provinces it also indicates the importance of a multidisciplinary multi scale approach extending from the basement to the surface in order to understand seal breach in carbonate petroleum systems the overall data is used to assess the main factors that effected the integrity of the seal when this latter is breached by hydrothermal fluids

multi stage ag bi co ni u and cu bi vein mineralization at wittichen schwarzwald sw germany geological setting ore mineralogy and fluid evolution the wittichen co ag bi u mining area schwarzwald ore district sw germany hosts several unconformity related vein type mineralizations within variscan leucogranite and permian to triassic redbeds the multistage mineralization formed at the intersection of two fault systems in the last 250 ma a permo triassic ore stage i with minor u bi quartz fluorite mineralization is followed by a jurassic to cretaceous ore stage ii with the main ag and co mineralization consisting of several generations of gangue minerals that host the sub stages of u bi bi ag ni as bi and co as bi important ore minerals are native elements co and ni arsenides and pitchblende sulphides are absent the miocene ore stage iii comprises barite with the cu bi sulfosalts emplectite wittichenite and aikinite and the sulphides anilite and djurleite besides native bi chalcopyrite sphalerite galena and tennantite the mineral forming fluid system changed from low salinity 5 wt nacl at high temperature around 300 c in permian to highly saline around 25 wt nacl cacl2 at lower temperatures 50 150 c in triassic to cretaceous times thermodynamic calculations and comparison with similar mineralizations worldwide show that the mesozoic ore forming fluid was alkaline with redox conditions above the hematite magnetite buffer we suggest that the precipitation mechanism for native elements pitchblende and arsenides is a decrease in ph during fluid mixing processes ree patterns in fluorite and the occurrence of bi in all stages suggest a granitic source of some ore forming elements whereas e g ag co and ni probably have been leached from the redbeds the greater importance of cu and isotope data indicates that the miocene ore stage iii is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages

crustal kinematics and deep structure of the northern rhine graben germany surface and subsurface geological data unpublished information gleaned from industrial seismic surveys and results from a deep reflection seismic profile across the tertiary northern rhine graben indicate that crustal extension in excess of 6 km was achieved by asymmetric detachment of the upper crust at a depth of about 15 km comparison of a simple geometric kinematic cross sectional model and its depth extrapolation with the dekorp 9 n deep crustal reflection data suggests that extension below the graben was achieved by slip along a gently westward dipping shear zone which truncated and offset lower crustal planar fabrics and which continues into the uppermost mantle the planar lower crustal reflectors probably originated mainly during late variscan permocarboniferous crustal extension and or magmatic underplating

cassiar platform north central british columbia a miogeoclinal fragment from idaho the allochthonous cassiar platform in north central british columbia is a cratonal fragment of ancestral north america juxtaposed against autochthonous north american crust along the tintina northern rocky mountain trench fault the cassiar platform records a neoproterozoic to early paleozoic rift to passive margin history that includes lower cambrian archeocyathan bearing limestones of the rosella formation in the cassiar mountains this study indicates that an extensive oolitic shoal developed toward the western edge of this carbonate platform during the deposition of the nevadella zone parallel to the western limit of thick continental crust initial sr 0 706 isopleth paleogeographic studies from other archeocyathan bearing units in the cordillera indicate that a semicontinuous oolitic shoal was along the western margin of the continental shelf from alaska to mexico there is a distinctive gap in the passive margin record from southeastern washington to southern idaho paleogeographic constraints from the rosella formation and published paleomagnetic data from the overlying sylvester allochthon suggest that this miogeoclinal slice was originally deposited near present day idaho and was transported northward along poorly constrained dextral strike slip faults

minor elements in layered sphalerite as a record of fluid origin mixing and crystallization in the navan zn pb ore deposit ireland this study tests the utility of the minor to trace element composition of sphalerite to discriminate between possible sources of ore forming fluids and to constrain processes involved in ore genesis of the world class irish type navan zn pb orebody ireland detailed petrography and electron microprobe microanalyses were performed on layered sphalerite previously analyzed for zn fe and s isotope compositions layered sphalerite displays a wide range of chemical composition at both sample and crystal scales the color style and scale of layering show variations with chemical composition but none of these correlations are consistent between samples however there are strong intersample correlations between chemical and s fe zn isotope compositions at the millimeter scale sphalerite precipitated from deep hydrothermal fluids with 34s enriched sulfide is enriched in cd sb cu and ag whereas fe and as are enriched in sphalerite precipitated from shallow bacteriogenic brines with isotopically light s significant chemical variations also occur at the micrometer scale in sphalerite regardless of its genetic affinity these variations are interpreted as being due to variations in temperature ph and sulfur activity following the arrival at the site of deposition of pulses of hydrothermal fluids at specific stages of sphalerite growth therefore the chemistry of sphalerite coupled with its texture appears to be a powerful tool to elucidate fluid typing and ore genesis the results support the hypothesis that layered sphalerite forms by rapid crystallization due to mixing of two fluids of contrasting physicochemical properties a process required for the formation of irish type and some other hydrothermal deposits including most notably mississippi valley type mvt deposits the existence of layered sphalerite coupled with its texture and chemical composition may therefore provide useful insight for the mineral exploration industry in ireland and elsewhere

sulfate brines in fluid inclusions of hydrothermal veins compositional determinations in the system h2o na ca cl so4 sulfate is among the most abundant ions in seawater and sulfate bearing brines are common in sedimentary basins among other environments however the properties of sulfate bearing fluid inclusions during microthermometry are as yet poorly constrained restricting the interpretation of fluid inclusion compositions where sulfate is a major ion the schwarzwald mining district on the eastern shoulder of the upper rhinegraben rift is an example of a geologic system characterized by sulfate bearing brines and constraints on the anion abundances chloride versus sulfate would be desirable as a potential means to differentiate fluid sources in hydrothermal veins in these regions here we use the pitzer type formalism to calculate equilibrium conditions along the vapor saturated liquidus of the system h2o na ca cl so4 and construct phase diagrams displaying the predicted phase equilibria we combine these predicted phase relations with microthermometric and crush leach analyses of fluid inclusions from veins in the schwarzwald and upper rhinegraben to estimate the compositions of these brines in terms of bulk salinity as well as cation and anion loads sodium versus calcium and chloride versus sulfate these data indicate systematic differences in fluid compositions recorded by fluid inclusions and demonstrate the application of detailed low temperature microthermometry to determine compositions of sulfate bearing brines thus these data provide new constraints on fluid sources and paleo hydrology of these classic basin hosted ore forming systems moreover the phase diagrams presented herein can be applied directly to compositional determinations in other systems

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

spatial temporal analysis of a seismic series using the principal components method the antequera series spain 1989 a method for the characterization of a seismically active zone from a distribution of hypocenters is presented this method is based on principal components analysis a powerful multivariant statistical technique that is used to find the rupture local ellipsoid rle the ellipsoid is a planar structure with which two variations of the method are developed the spatial principal components analysis and the spatial temporal principal components analysis using these methods it is possible to find the dominating tendencies in the fracturing of the seismically active volume as well as the temporal evolution of the process the methodology developed has been applied to a series of earthquakes that occurred near antequera spain with the result that the main fracture series trends n70 80 e moreover the temporal evolution of the system from the most relevant rle has been characterized

geochemical modeling of zns in biofilms an example of ore depositional processes the precipitation of nearly pure nanocrystalline zinc sulfides primarily sphalerite and wurtzite within a biofilm dominated by sulfate reducing bacteria of the family desulfobacteriaceae has been observed in the flooded tunnels of an abandoned mine in southwestern wisconsin zns accumulations are limited to biofilms growing on old mine timbers zns deposits which comprise about 20 percent of the volume of the biofilm formed in less than 30 yr from solutions containing only a few milligrams per liter mg l zn 2 a model is proposed wherein sulfate reduction is followed by the formation of aqueous metal sulfide clusters that aggregate to form 1 to 3 nm diameter crystals that are transported and agglomerate to form micron scale aggregates geochemical modeling shows how reduction of sulfate leads to exclusive precipitation of zns until most of the zn 2 is consumed the model also predicts a series of discrete metal sulfide precipitation events that may be used to interpret sulfide mineral paragenesis of low temperature cu pb zn ore deposits for example the paragenesis of essentially monomineralic and mixed sulfide layers in mississippi valley type strataform and strata bound pb zn cu and sedex deposits can be predicted thermodynamically if the rate of aqueous sulfide generation does not outstrip the flux of metals into the system based on the characteristics of zns produced by sulfate reducing bacteria features of ore deposit minerals consistent with a biogenic origin can be identified these include microstructures formed by coarsening of nanophase materials the presence of micron scale spherical aggregates in organic rich microenvironments and spatially heterogeneous patterns of sulfide mineral distribution consistent with local variations in redox potential and activity of sulfate reducing bacteria

major element compositions of fluid inclusions from hydrothermal vein type deposits record eroded sedimentary units in the schwarzwald district sw germany mixing of sedimentary formation fluids with basement derived brines is an important mechanism for the formation of hydrothermal veins we focus on the sources of the sediment derived fluid component in ore forming processes and present a comprehensive fluid inclusion study on 84 jurassic hydrothermal veins from the schwarzwald mining district sw germany our data derive from about 2300 fluid inclusions and reveal differences in the average fluid composition between the northern central and southern schwarzwald fluids from the northern and southern schwarzwald are characterised by high salinities 18 26 wt nacl cacl2 low ca ca na mole ratios 0 1 0 4 and variable cl br mass ratios 30 1140 in contrast fluids from the central schwarzwald show even higher salinities 23 27 wt nacl cacl2 higher ca ca na mole ratios 0 2 0 9 and less variable cl br mass ratios 40 130 these fluid compositions correlate with the nature and thickness of the now eroded sedimentary cover rocks compared to the northern and the southern schwarzwald where halite precipitation occurred during the middle triassic the sedimentary basin in the central schwarzwald was relatively shallow at this time and no halite was precipitated accordingly cl br ratios of fluids from the central schwarzwald provide no evidence for the reaction of a sedimentary brine with halite whereas those from the northern and southern schwarzwald do instead elevated ca ca na high so4 contents and relatively low cl br imply the presence of a gypsum dissolution brine during vein formation in the central schwarzwald which agrees with the reconstructed regional triassic geology hence the information archived in fluid inclusions from hydrothermal veins in the crystalline basement has the potential for reconstructing sedimentary rocks in the former overburden

evolution and structure of the upper rhine graben insights from three dimensional thermomechanical modelling the evolution and geometry of the tertiary upper rhine graben were controlled by a continually changing stress field and the reactivation of pre existing crustal discontinuities a period of wnw ese extension in the late eocene and oligocene was followed by lateral translation from the early miocene onwards this study utilizes 3d finite element techniques to simulate extension and lateral translation on a lithospheric scale brittle and creep behaviour of lithospheric rocks are represented by elastoplasticity and thermally activated power law viscoplasticity respectively contact elements allocated with cohesion and frictional coefficients are used to describe pre existing zones of weakness in the elastic brittle field our results suggest that 1 extension is accommodated along listric border faults to midcrustal depth of 15 16 km beneath pure shear stretching occurs without a need for localized shear zones in lower crust and upper mantle 2 ductile flow at midcrustal depth across the graben accounts for the pronounced halfgraben morphology thereby the shape of the border faults their frictional coefficients and sedimentary loads have profound effects on the rate of ductile flow across the graben 3 horizontal extension of 8 8 5 km and sinistral displacement across the rift of 3 4 km are needed to accommodate the observed sediment thickness

experimental calibration of the sphalerite cosmobarometer abstract the pressure and temperature dependence of the composition of sphalerite in equilibrium with troilite metallic iron has been determined experimentally at 2 5 and 5 0 kbar between 400 and 800 c using both the aqueous and anhydrous alkali halide flux recrystallization techniques the measured pressure effect is larger than that calculated by us and by schwarcz et al 1975a and is described by the equation t in kelvins p kbar 3 576 0 0551 t 0 0296 t log mole fes assuming temperatures of final equilibration between sphalerite and troilite of 350 c for iron meteorites and 600 c for enstatite chondrites published analyses of sphalerites provide estimates of pressures of formation and possible radii of parent objects of meteorites as follows ia irons landes sardis gladstone bogou odessa toluca 0 0 to 3 5 kbar 0 to 442 km e6 enstatite chondrites yilmia pillistfer 0 2 to 0 7 kbar 0 to 198 km

inclusions of sedimentary brines in post variscan mineralizations in the federal republic of germany a study by neutron activation analysis abstract the post variscan vein mineralizations in the federal republic of germany are characterized by highly saline fluid inclusions t e t mice 26 to 20 c t h 1 ca 22 000 60 000 mg kg 1 cl 85 000 200 000 mg kg 1 and br 550 2 600 mg kg 1 composition and salinity of the inclusion solutions are similar to brines in deep sedimentary basins it is assumed that formation waters of the na ca cl type migrated out of permo triassic sediment troughs into culmination zones of the variscan orogen where they were heated and caused mineralizations through cooling and mixing with sulfate bicarbonate waters when reascending

on the growth of colloform textures a case study of sphalerite from the galmoy ore body ireland abstract colloform textures have been described from many of the world9s sulphide ore deposits and involve formation of distinct microcrystalline layers these textures provide information related to sequential stages of ore formation yet their mechanism of growth is poorly understood this study has analysed a series of colloform samples from the galmoy zn pb mine ireland results indicate that the growth sequence is not always intuitive and layers that appear stratigraphic upon cursory observation may not be the crystal preferred orientation cpo of discrete colloform layers abruptly switches between different orientation axes examination of the same layers using in situ laser sulphur isotope analysis reveals equally striking changes in 34 s signature between end member bacteriogenic 25 and hydrothermal 10 sources although these results combined with petrographic observation allow the determination of a probable growth history there is no correlation between shifting cpo and 34 s signature trace element analysis reveals changes in trace element sequestration between colloform layers cadmium and chlorine rich layers correspond to a hydrothermal sulphur source whereas iron rich layers correspond to a bacteriogenic sulphur source in the absence of alternative mechanisms we suggest that the most likely factors influencing cpo changes are temperature and degree of supersaturation during two fluid mixing

ultrastructure aggregation state and crystal growth of biogenic nanocrystalline sphalerite and wurtzite in this study we investigated the size submicrometer scale structure and aggregation state of zns formed by sulfate reducing bacteria srb in a srb dominated biofilm growing on degraded wood in cold tsimilar to8degreesc circumneutral ph 7 2 8 5 waters draining from an abandoned carbonate hosted pb zn mine high resolution transmission electron microscope hrtem data reveal that the earliest biologically induced precipitates are crystalline zns nanoparticles 1 5 nm in diameter although most nanocrystals have the sphalerite structure nanocrystals of wurtzite are also present consistent with a predicted size dependence for zns phase stability nearly all the nanocrystals are concentrated into 1 5 mum diameter spheroidal aggregates that display concentric banding patterns indicative of episodic precipitation and flocculation abundant disordered stacking sequences and faceted porous crystal aggregate morphologies are consistent with aggregation driven growth of zns nanocrystals prior to and or during spheroid formation spheroids are typically coated by organic polymers or associated with microbial cellular surfaces and are concentrated roughly into layers within the biofilm size shape structure degree of crystallinity and polymer associations will all impact zns solubility aggregation and coarsening behavior transport in groundwater and potential for deposition by sedimentation results presented here reveal nanometer to micrometer scale attributes of biologically induced zns formation likely to be relevant to sequestration via bacterial sulfate reduction bsr of other potential contaminant metal loid s such as pb2 cd2 as3 and hg2 into metal sulfides the results highlight the importance of basic mineralogical information for accurate prediction and monitoring of long term contaminant metal mobility and bioavailability in natural and constructed bioremediation systems our observations also provoke interesting questions regarding the role of size dependent phase stability in biomineralization and provide new insights into the origin of submicrometer to millimeter scale petrographic features observed in low temperature sedimentary sulfide ore deposits

the mixing hypothesis and the origin of mississippi valley type ore deposits anderson 1991 proposed that methane generated from the heating of kerogen in the wall rocks of mississippi valley type mvt deposits diffuses into the ore zone reducing sulfate and precipitating the ore minerals this hypothesis has been tested by calculating the diffusion of methane from wall rock into a flowing solution at 150 c methane pressures in the ore zone quickly reach a steady state which depends on the assumed methane pressure in the wall rock and the flow velocity calculated methane pressures in the ore solution are not sufficient to generate a gas phase but other dissolved gases such as co 2 may contribute sufficiently to make this happen sulfate reduction and sulfide precipitation will occur whether or not a gas phase forms but many mvt ores have a tabular form or are located in the upper part of breccias suggesting that there was a gas phase control recent experimental results chou and burruss 2007 offer an explanation for the fact that very light carbon isotopes are not commonly found in mvt deposits the main obstacles to further development of these ideas is our lack of understanding of the thermochemical sulfate reduction reaction and the fact that little attention has been paid to possible sources of methane in the vicinity of ore deposits

shear wave velocity structure below the iberian peninsula as obtained by a detailed analysis of surface waves abstract a tentative tomography of iberia based on broadband surface wave data is performed for the first time in this paper we have complemented a previous study of the northern half of the iberian peninsula with a study of the southern half of the peninsula based on a detailed analysis of rayleigh wave dispersion now we present the first shear velocity contour maps at different subcrustal depths quality digital records provided by the nars array have been used standard techniques as multiple filtering and time variable filtering are employed to efficiently remove higher mode interference and improve isolation of the fundamental mode rayleigh wave from the seismograms and thus to calculate the interstation rayleigh wave group velocity frequency domain wiener deconvolution is used to determine the interstation phase velocity we perform simultaneous inversion of phase and group velocity dispersion data by means of the stochastic inverse operator the inversion results previously reported for the northern iberian region together with the results obtained here are used for 3 d mapping of shear wave velocity over the iberian peninsula lateral variation in velocity at five depth intervals chosen in agreement with the theoretical earth models determined by joint inversion is displayed for the lithosphere and asthenosphere of iberia

microstructural characterization and in situ sulfur isotopic analysis of silver bearing sphalerite from the edmond hydrothermal field central indian ridge abstract a close zn ag association has been noted recently in several polymetallic sulfide ore deposits from the indian ocean however the role of nanotextural controls on invisible silver distribution within sphalerite a significant ag carrier is still not well understood in this study typical zn sulfide samples from the edmond vent field central indian ridge can be roughly classified into three different groups based on their chemical compositions and mineral textures among them sulfosalt bearing fe poor zinc sulfides in sulfate dominant outer chimney walls usually contain higher contents of ag cu and pb up to wt levels than fe rich massive to disseminated sphalerite in zn fe rich chimney fragments coated by silicified crusts such sphalerite is represented by colloform botryoidal aggregates of optically anisotropic zns with a strongly disordered structure or hexagonal habit which are actually formed by coalescence and agglomeration of colloidal nanocrystalline particles using high resolution transmission electron microscopy hrtem and in situ micro xrd techniques we have investigated the ultrastructure and crystal chemistry of the 1 1 1 twin boundaries and wurtzite type stacking faults that occur in ag rich colloform or porous dendritic sphalerite submicroscopic electrum and ag nanoparticles appear to nucleate on the micro nano pore walls as cavity fillings or occur along grain boundaries between chalcopyrite tennantite inclusions and the host sphalerite interestingly the inhomogeneous distribution of precious metals and other chalcophile elements is generally concordant with the extent of recrystallization intragranular porosity as well as various degrees of structural disordering imperfectness i e bulk defect density in zns domains lattice defects and interfaces may play a limited role in promoting the simultaneous introduction of exotic impurities into colloform sphalerite during rapid growth even though certain morphological traits and aggregation state at the nanoscale seem to support a biogenic origin of these zns particles characterized by admixed polytypic intergrowth structures the mineralogical and geochemical features of highly defective sphalerite crystals in addition to their microscale s isotope signatures with relatively high 34 s values exhibit signs of abiologically mediated rapid precipitation caused by extensive mixing and cooling at edmond the physicochemical conditions and seafloor disequilibrium processes indicated by zns formation mechanism might facilitate the incorporation and enrichment of ag or other trace elements in hydrothermal sphalerite

stratiform copper deposits hosted by low energy sediments ii nature of source rocks and composition of metal transporting water several factors suggest that hematite bearing sediments composed principally of alluvial fan sediments were the source of metal transporting water and of metals in stratiform copper deposits hosted by low energy sediments first such sediments are associated with all examples of larger stratiform copper deposits hosted by low energy sediments second a zonal sequence corresponding to an approximate sulfide solubility product increase is developed laterally into the basin from sandy sediments in contact with the hematite bearing sediments and upward from the contact of the ore hosting sediments with the hematite bearing sediments third the zonal sequence is developed basinward from pinchouts and wedge downs of the hematite bearing sediments and copper mineralization is absent from host horizons where hematite bearing sediments are not developed fourth authigenic mineral assemblages with the exception of hematite sulfides and organic carbon are similar in both the host sediments and in the hematite bearing sediments the authigenic and evaporite mineral assemblages and the nature of associated sediments indicate that most occurrences of the hematite bearing sediments were probably deposited in closed continental basins published sedimentological and paleogeographic analyses show that the rotliegende associated with the kupferschiefer hosted deposits was deposited in a closed continental basin no consistent composition of the hematite bearing sediments is evident although basalt flows or basalt derived clastic components occur in the alluvial fan sediments associated with three of the larger stratiform copper deposits authigenic and evaporite minerals and compositions of modern continental closed basin waters show that the waters originally within the closed basins were na cl so 4 types with variable mg ca and so 4 contents in equilibrium with hematite and with a ph constrained either by carbonate minerals atmospheric carbon dioxide or by quartz microcline muscovite chloride concentrations were likely to have been about six times seawater waters with higher mg and lower ca contents were likely to be associated with alluvial fan sediments containing basalt or dolomite derived clastic components water rock ratios in the alluvial fan sediments were probably 33 percent or less if the 50 cm hypothesis i e that chalcocite in stratiform copper deposits hosted by low energy sediments was precipitated as a result of bacterial sulfate reduction within 50 cm of the surface of the host sediment is true then metal transporting waters were being released from the hematite bearing sediments very early in their burial history if so the metal transporting water was the original closed basin water with a temperature of less than 50 degrees c

quartz veins with associated sb pb ag au mineralization in the schwarzwald sw germany a record of metamorphic cooling tectonic rifting and element remobilization processes in the variscan belt a combination of textural observations from 38 permian sb pb ag au bearing quartz veins in the schwarzwald sw germany with isotopic fluid inclusion and geochemical data allows to refine genetic models for this common type of mineralization to understand the origin of mineralogical diversity and the correlation with large scale tectonic events textures record four main mineralization stages i fe as sb au ii pb zn cu iii pb sb and iv ag sb stage i sulfides dominated by pyrite and arsenopyrite formed due to cooling of low salinity metamorphic fluids during the permian with maximum homogenization temperatures of 400 c invisible gold in arsenopyrite pyrite marcasite and stibnite was remobilized and locally precipitated as electrum at the end of stage i minerals of stages ii and iii comprise a rich diversity of sb bearing sulfosalts including e g bournonite zinkenite and jamesonite this assemblage formed during jurassic times due to mixing of high salinity mid and upper crustal fluids up to 27 wt nacl cacl2 with homogenization temperatures between 50 and 250 c stage iii is marked by a rich variety of pb sb sulfosalts its local abundance is directly related to the presence of stage i mineralization and its extent of remobilization during a significant influx of pb in the jurassic cretaceous the formation of the upper rhine graben during the tertiary reactivated especially ne sw oriented veins percolating ag rich fluids reacted with earlier stage iii pb sb sulfosalts forming ag rich minerals stage iv such as miargyrite pyrargyrite and stephanite the transition from metamorphic fluids to basinal saline e g pb bearing brines over hundreds of millions of years as is shown in this study and present in other variscan occurrences indicates a possibly typical poly stage characteristic of sb deposits worldwide which has however not been investigated in detail so far

large scale waveform inversions of surface waves for lateral heterogeneity 2 application to surface waves in europe and the mediterranean linear surface wave scattering theory is used to reconstruct the lateral heterogeneity under europe and the mediterranean using surface wave data recorded with the network of autonomously recording seismographs nars the waveform inversion of the phase and the amplitude of the direct surface wave leads to a variance reduction of approximately 40 and results in phase velocity maps in the period ranges 30 40 s 40 60 s and 60 100 s a resolution analysis is performed in order to establish the lateral resolution of these inversions using the phase velocity perturbations of the three period bands a two layer model for the s velocity under europe and the mediterranean is constructed the s velocity perturbations in the deepest layer 100 200 km are much more pronounced than in the top layer 0 100 km which confirms that the low velocity zone exhibits pronounced lateral variations in both layers the s velocity is low under the western mediterranean while the s velocity is high under the scandinavian shield in the deepest layer a high s velocity region extends from greece under the adriatic to northern italy several interesting smaller features such as the massif central are reconstructed one of the spectacular features of the reconstructed models is a sharp transition in the layer between 100 and 200 km near the tornquist tesseyre zone this would indicate that there is a sharp transition at depth between central europe and the east european platform the waveform inversion of the surface wave coda leads to good waveform fits but the reconstructed models are chaotic this is due both to a lack of sufficient data for a good imaging of the surface wave energy on the heterogeneities and to an appreciable noise component in the surface wave coda

trace and minor element variations and sulfur isotopes in crystalline and colloform zns incorporation mechanisms and implications for their genesis abstract various models have been proposed to explain the formation mechanism of colloform sphalerite but the origin is still under debate in order to decipher influences on trace element incorporation and sulfur isotope composition crystalline and colloform sphalerite from the carbonate hosted mississippi valley type mvt deposit near wiesloch sw germany were investigated and compared to sphalerite samples from 52 hydrothermal vein type deposits in the schwarzwald ore district sw germany to study the influence of different host rocks formation mechanisms and fluid origin on trace element incorporation trace and minor element incorporation in sphalerite shows some correlation to their host rock and or origin of fluid gangue paragenetic minerals and precipitation mechanisms e g diagenetic processes fluid cooling or fluid mixing furthermore crystalline sphalerite is generally enriched in elements like cd cu sb and ag compared to colloform sphalerite that mainly incorporates elements like as pb and tl in addition sulfur isotopes are characterized by positive values for crystalline and strongly negative values for colloform sphalerite the combination of trace element contents typical minerals associated with colloform sphalerite from wiesloch sulfur isotopes and thermodynamic considerations helped to evaluate the involvement of sulfate reducing bacteria in water filled karst cavities sulfate reducing bacteria cause a sulfide rich environment that leads in case of a metal rich fluid supply to a sudden oversaturation of the fluid with respect to galena sphalerite and pyrite this however exactly coincides with the observed crystallization sequence of samples involving colloform sphalerite from the wiesloch mvt deposit

micro scale sulfur isotope and chemical variations in sphalerite from the bleiberg pb zn deposit eastern alps austria abstract the bleiberg pb zn deposit in the drau range is the type locality of alpine type carbonate hosted pb zn deposits its origin has been the subject of on going controversy with two contrasting genetic models proposed 1 the sedex model with ore forming contemporaneously with sedimentation of the triassic host rocks at about 220 ma vs 2 the epigenetic mvt model with ores forming after host rock sedimentation at about 200 ma or later both models assume that on a deposit or even district scale a fixed paragenetic sequence of ore minerals can be established the results of our detailed petrographic chemical and sulfur isotope study of two key ore samples from two major ore horizons in the wetterstein formation at bleiberg ehk02 erzkalk horizon and blb17 maxer banke horizon demonstrate that there is no fixed paragenetic sequence of ore minerals small scale non systematic variations are recorded in textures sphalerite chemistry and 34 s in each sample texturally different sphalerite types colloform schalenblende fine and coarse grained crystalline sphalerite co occur on a millimeter to centimeter scale these sphalerites represent multiple mineralization stages pulses since they differ in their trace element inventory and in their 34 s nonetheless there is some correspondence of sphalerite micro textures sulfur isotope and chemical composition between the two samples with microcrystalline colloform schalenblende being fe rich having high fe cd 15 and 9 respectively and a light sulfur isotope composition 34 s 26 0 to 16 2 cadmium rich and fe poor sphalerite in both samples has relatively heavier sulfur isotope composition in sample ehk02 this sphalerite has fe cd of 0 5 and 34 s from 6 6 to 4 6 in sample blb17 fe cd is 0 1 and 34 s ranges from 15 0 to 1 5 barite which is restricted to sample ehk02 has 34 s 17 the large variations in 34 s recorded on the mm to cm scale is consistent with variable contributions of reduced sulfur from two different sulfur reservoirs the dominant reservoir with 34 s values 34 s about 5 suggests a hydrothermal source likely linked with thermochemical sulfate reduction tsr based on this small to micro scale study no simple deposit wide paragenetic and sulfur isotope evolution with time can be established in the erzkalk ore sample ehk02 an earlier pb zn ba stage characterized by heavy sulfur isotope values is succeeded by a light 34 s dominated zn pb f stage in contrast the several mineralization pulses identified in the stratiform zn pb f maxer banke ore sample blb17 define a broad trend to heavier sulfur isotope values with time the interaction documented in these samples between two sulfur reservoirs is considered a key mechanism of ore formation

a process based approach to estimating the copper derived from red beds in the sediment hosted stratiform copper deposit model most estimates of the total tonnage of copper metal leached from footwall red beds to form sediment hosted stratiform copper deposits are based on the amounts of copper at ppm levels that might have been derived from the volume of red beds underlying given sediment hosted stratiform copper deposits that static calculation is replaced here with a process based approach in which the release of copper results from the progressive diagenetic alteration of the footwall aquifers by oxygen rich meteoric water driven by topographic recharge in highlands adjacent to the intracontinental rift basins hosting these deposits the total amount of liberated copper depends on the volume of meteoric water its oxygen content and the duration of the diagenetic leaching of copper estimates suggest that adequate amounts of copper may be derived from footwall red beds within reasonable periods of early and possibly more advanced diagenesis

chemical evolution of ore forming brines basement leaching metal provenance and the redox link between barren and ore bearing hydrothermal veins a case study from the schwarzwald mining district in sw germany abstract six mineralogically exemplary barren and mineralized hydrothermal veins with pb and zn ores of jurassic cretaceous and cenozoic age in the schwarzwald mining district sw germany were chosen to shed light on the origin of their mineralogical diversity the selection of the veins was guided by the fact that they represent the largest number of veins in the region are very well known mineralogically and geochemically and they provide nice examples of barren and mineralized veins of similar age fluid inclusion data from the individual veins overlap implying their diverse mineralogy is not caused by different fluid compositions participating during fluid mixing la icpms data of single fluid inclusions indicate no systematic variations in major elements but significant changes in fluid mixing ratios which caused variable trace element concentrations of different fluid inclusion assemblages in one sample we suggest that different ore gangue assemblages can be produced by mixing of identical fluid endmembers but variable mixing ratios la icpms analyses of single fluid inclusions in barren and mineralized veins record similar base metal and sulfur concentrations hence sulfide mineralization in the veins appears not to be controlled by metal solubility thermodynamic modeling based on the fluid data indicates that the presence of a reducing phase during fluid mixing is required for sulfide mineralization to precipitate la icpms trace element analyses of feldspars biotites chlorites and clay minerals in granites and paragneisses which are the source of the metal content in the ore forming fluids demonstrate that the dominant provenance for pb zn as sb ba tl mo fe and mn are probably paragneisses while co cu and ni are probably sourced from s type granite a rough quantification indicates that

distribution and mobilization of sn in silicate minerals from the mesozoic shizhuyuan w dominated polymetallic deposit south china abstract although mobilization and concentration of elements in super large deposits have become hot topics in recent years studies of the mobilization of metals between minerals using in situ analyses are rare the shizhuyuan w dominated polymetallic deposit in south china is one of the largest non ferrous metal deposits in the world and contains large metal reserves of sn w bi and rare earth elements using laser ablation inductively couple plasma mass spectrometry la icp ms we analyzed trace elements in major silicate minerals and magnetite from granites and skarns of the shizhuyuan deposit tin concentrations of muscovitized biotite range from 196 to 558 ppm muscovite from 57 7 to 332 ppm chloritized biotite from 1 62 to 527 ppm k feldspar from 4 16 to 6 97 ppm kaolinized k feldspar from 1 15 to 9 38 ppm plagioclase from 1 87 to 5 09 ppm sericitic plagioclase from 2 53 to 28 7 ppm kaolinized plagioclase from 0 99 to 17 7 ppm epidote from 1199 to 3382 ppm garnet from 797 to 2860 ppm chloritized garnet from 72 5 to 2548 ppm chlorite from 19 6 to 159 ppm and magnetite from 23 7 to 872 ppm thus sn is mainly hosted in biotite muscovitized biotite garnet and epidote sn occurs as an isomorphous substitution and is predominantly associated with fe3 for fe3 poor minerals sn can isomorphously substitute al in the form of simple cation due to similar radius at the octahedral site such as in k feldspar and kaolinized k feldspar however sn cannot substitute al in the si o tetrahedrons therefore sn and al correlate different in different silicate minerals alteration of biotite to muscovite and chlorite can release a large amount of sn to the magmatic hydrothermal fluids which may be already enriched in sn during the formation of skarn deposits sn f complexes can be converted to cassiterite sno2 to free up f by hydrolysis a significant amount of sn enters the lattices of garnet and epidote therefore release of sn during alteration of garnet to chlorite in a retrograde stage of alteration may have contributed to the mineralization

improvements in the knowledge of the anelastic structure of the iberian peninsula from seismic data of the iliha project summary attenuation coefficients of rayleigh waves propagating across the iberian peninsula and quality factor models were obtained for different two station great circle paths the data used were long period wave trains contained in the seismograms provided by the iliha array installed in the peninsula in the 1980s more than 300 seismograms were analysed to obtain 14 sets of similar paths consisting of either paths totally included in one of the four pure tectonic regions or mixed paths crossing several regions we used the two station method to determine attenuation parameters r and then an inversion method to derive q 1 models the attenuation coefficients of seismic energy in the 10 120 s range are in the range 2 8 10 3 0 1 10 3 km 1 and correlate well with both previous results obtained from analogue wwssn and most seismogeotectonic characteristics of iberia the q models obtained also agree with a few models for iberia determined earlier and they show significant variations from one region to another as a general feature the values are higher in the active seismotectonic regions typical maximum of 2 6 10 3 km 1 than in the more stable ones typical maximum of 1 4 10 3 moreover the maximum of q 1 in the active regions 145 10 3 120 10 3 is higher than in the stable ones 40 10 3 100 10 3 in general both the regionalized attenuation coefficients of rayleigh waves and the quality factor models exhibit a good agreement with previously published lg wave attenuation and coda q distribution patterns in iberia

sulphide mineralisation in the deep sea hydrothermal vent polychaete alvinella pompejana implications for fossil preservation abstract hydrothermal vent fauna particularly vestimentiferan and polychaete worm tubes are occasionally preserved in the geological record the early stages of mineralisation are particularly important in defining whether or not preservation will occur and they are poorly understood tube samples of the polychaete worm alvinella pompejana collected from 13 n on the east pacific rise have been studied to identify the processes occurring during early pyrite marcasite mineralisation iron sulphide mineralisation is present within the walls of the organic dwelling tube and is induced by microbial fauna preserved within the tube micro layers various microorganisms were observed coating the inner tube surfaces together with 10 100 m sized fe and zn sulphide particles precipitated from vent fluids the microbes and particulate sulphides become entombed within the tube wall as further layers of organic material are secreted by the worm during tube building episodes this results in a laminated tube structure being formed composed of alternating layers of tube material and microbial sulphide rich interlayers the microbial sulphide layers provide a template for further mineralisation and replacement of the microbes with pyrite while degradation of the organic components occurs the iron monosulphides mackinawite and greigite have been identified as intermediatory phases that occur as precursor minerals during the formation of pyrite later marcasite mineralisation is observed to form over some of the pyritised organic layers once mineralisation has replaced most of the organic tube material the structure will then be preserved along with the host sulphide body these observations enhance our understanding of the mechanisms of fossil pyritisation in fine scaled organic structures throughout the geological record

variations of the sequence stratigraphic model past concepts present understandings and future directions the working hypothesis upon which the sequence concepts are based is that the relative sea level change results in changes in the capacity of a basin to accommodate sediment which in turn results in a succession of sequences the interplay between eustasy tectonics sediment flux and physiography yields a predictable geologic response in carbonate clastic as well as mixed carbonate clastic settings the criteria for recognition of sequence boundaries can be varied within a given basin as well as between basins they include but are not restricted to 1 a basinward shift of facies across a sharp bedding contact 2 onlapping stratal geometry and 3 truncation of strata the key to the correct utilization of these concepts is to recognize sequence stratigraphy as an approach or a tool rather than a rigid template observations from the upper albian cretaceous viking formation of the western canadian sedimentary basin are presented to illustrate the stratigraphic expression of clastic depositional sequences on a ramp margin in this setting forced regressions and lowstand shorelines commonly occur incised valleys sometimes occur and submarine fans rarely occur in response to fluctuations of relative sea level the base of the viking formation sometimes is characterized by relatively coarse grainedmore sediments sharply overlying fine grained offshore muds and is interpreted as a third order sequence boundary pebbles occasionally are observed at this contact subsequently a number of higher order sequences within the lower to middle viking are observed and are characterized by the occurrence of forced regressions and lowstand shorelines without associated incised valleys less

origin of the triassic qilinchang pb zn deposit in the western yangtze block sw china insights from in situ trace elemental compositions of base metal sulphides abstract the qilinchang pb zn deposit 5mt of sulphide ore at mean grades of 2 3 9 2 pb and 2 7 22 5 zn is hosted in early carboniferous carbonate rocks and mainly controlled by ne ns and nw trending structural belts between the xiaojiang and zhaotong qujing buried faults ore minerals are sphalerite galena pyrite chalcopyrite and marmatite whereas gangue minerals are dolomite calcite and quartz three generations of pyrite are recognized these include fine grained anhedral pyrite py i medium grained anhedral to subhedral hydrothermal pyrite py ii and coarse grained subhedral to euhedral hydrothermal pyrite py iii while the sphalerite occurs in two forms as fine grained intergrown with galena and associated with py i and py ii laser ablation inductively coupled plasma mass spectrometry la icp ms analysis was performed to evaluate trace element compositions of pyrite and sphalerite from different generations of ores py i has relatively higher concentrations of mg mn co ni and tl py ii in cu as se mo and sb relative to pyrite of other generations the contents of trace elements in py iii are variable but significantly enriched in ti v bi ag and pb compared to py i and py ii this variation indicates that these elements occur as micro mineral inclusions of possible ag pb bearing phases sphalerite of stage i has higher concentrations of mn fe co ni cu ga ge as ag cd in sb hg and pb than stage ii these elements are homogeneously distributed in all samples analyzed the incorporation of these elements is primarily through simple substitution mechanisms e g 2zn2 cu in3 as indicated from binary plots principal component analyses pca applied to la icp ms dataset for pyrite reveal two main clusters py i enriched in ni co and as py ii and py iii high in with v mn cu zn se mo ag sb au and bi likewise the pca also confirms two clusters of elements for sphalerite ge cu as sb ag fe and cd corresponding to sph i and in sn and ga corresponding to sph ii py i has higher co ni ratio ranging from 0 04 to 1 6 compared to py ii and py iii having co ni ratios from 0 to 0 706 and 0 0 696 respectively we report that the pyrites from the qilinchang deposit have co ni ratios slightly lower than typical mississippi valley type mvt deposits 0 2 7 2 and different from iron oxide copper gold iocg and porphyry cu deposits considering these geochemical signatures it can be suggested that the qilinchang deposit was not related to magmatic activities we thus propose that the ore forming fluids responsible for the formation of the deposit were generated from a low temperature environment similar to typical mvt deposits