the giant dexing porphyry cu mo au deposit in east china product of melting of juvenile lower crust in an intracontinental setting the dexing porphyry cu mo au deposit in east china 1 168 mt at 0 45 cu is located in the interior of the south china craton scc made up of two lithospheric blocks the yangtze and cathaysia blocks the cu mo au mineralization is associated with mid jurassic granodioritic porphyries with three high level intrusive centers controlled by a series of lineaments at the southeastern edge of the yangtze block available age data define a short duration 172 170 ma of the felsic magmatism and the mineralization 171 1 ma the deposit shows broad similarities with deposits in volcanoplutonic arcs although it was formed in an intracontinental setting porphyries associated with mineralization are mainly granodiorites which contain abundant phenocrysts 40 60 and carry contemporaneous microgranular mafic enclaves mmes they are mainly high k calc alkaline and show geochemical affinities with adakite characterized by relatively high mgo cr ni th and th ce ratios the least altered porphyries yielded relatively uniform end t values from 0 9 to 0 6 and wide 87sr 86sr i range between 0 7046 and 0 7058 partially overlapping with the sr nd isotopic compositions of the mmes and mid jurassic mafic rocks in the scc zircons from the porphyries have positive ehf t values 3 4 to 6 9 and low 18o values 4 7 to 6 3 generally close to those of depleted mantle all data suggest an origin by partial melting of a thickened juvenile lower crust involving mantle components e g neoproterozoic mafic arc magmas triggered by invasion of contemporaneous mafic melts at dexing the mmes show textural mineralogical and chemical evidence for an origin as xenoliths formed by injection of mafic melts into the felsic magmas these mmes usually contain magmatic chalcopyrite and have original variable contents of cu up to 500 ppm their geochemical characteristics suggest that they were derived from an enriched mantle source metasomatized by proterozoic slab derived fluids and supplied a part of cu au and s for the dexing porphyry system during their injection into the felsic magmas the 171 1 ma magmatic hydrothermal event at dexing is contemporaneous with the mid jurassic extension in the scc followed by 160 90 ma arc like magmatism in southeastern china with respect to the tectono magmatic evolution of the scc the emplacement of cu bearing porphyries and the associated cu mineralization occurred in response to the transformation from a tensional regime related to mid jurassic extension to a transpressional regime related to the subduction of the paleo pacific oceanic lithosphere

metallogeny of the handagai skarn fe cu deposit northern great xing an range ne china constraints on fluid inclusions and skarn genesis abstract the newly discovered handagai skarn fe cu deposit is located in the northern great xing an range of ne china and is hosted by the ordovician luohe formation the orebodies that form the deposit are generally concordant with the bedding within these sediments and are spatially related to areas of skarn development the fe cu mineralization in this area records four stages of paragenesis namely prograde skarn retrograde skarn quartz sulfide and quartz carbonate stages the handagai deposit is a calcic skarn that is dominated by an andradite diopside epidote actinolite assemblage the mineralogy and geochemistry of the skarn indicate that it formed from a hydrothermal fluid that altered the carbonate units in this area to a garnet and42 95grs4 53 and pyroxene di71 78hd22 29jo0 2 bearing skarn the epidote within the skarn has an epidote end member composition with the chlorite in the skarn dominantly fe rich indicating that these minerals formed in an fe rich environment the petrographic microthermometric and raman spectroscopic analysis of fluid inclusions within garnet epidote actinolite quartz and calcite precipitated at different stages of formation of the handagai deposit indicate that mineralization related fluid inclusions are either liquid rich two phase h2o nacl type i gas rich two phase h2o nacl type ii three phase liquid vapor solid h2o nacl type iii or co2 h2o nacl inclusions type iv the early stages of mineralization are associated with all four types of inclusion whereas the later stages of mineralization are only associated with type i and ii inclusions inclusion homogenization temperatures vary between the four stages of mineralization 370 c 530 c and 600 c 210 c 290 c 190 c 270 c and 150 c 230 c from early to late respectively with salinities also varying between the earlier and later stages of mineralization 11 18 and 45 7 15 6 9 and 3 7 wt nacl equivalent equiv respectively the majority of the inclusions within the handagai deposit have homogenization temperatures and salinities of 200 c 350 c and 4 14 wt nacl equiv respectively indicating that this is a medium high temperature and medium low salinity type deposit the fluid inclusions were trapped at pressures of 11 to 72 mpa corresponding to depths of 0 4 to 2 9 km the geology mineralogy geochemistry and fluid inclusions microthermometry indicate that the handagai deposit formed as a result of contact infiltration metasomatism with the deposition of ore minerals resulting from a combination of factors that include boiling as a result of reduced pressure cooling and fluid mixing

high resolution characterization of vadose zone dynamics using cross borehole radar characterization of the dynamics of moisture migration in the unsaturated zone of aquifers is essential if reliable estimates of the transport of pollutants threatening such aquifers are to be made electrical geophysical investigation techniques such as ground penetrating radar offer suitable methods for monitoring moisture content changes in the vadose zone moreover these tools permit relatively large measurement scales appropriate for hydrological models of unsaturated processes and thus they offer a distinct advantage over conventional measurement approaches ground penetrating radar when applied in transmission mode between boreholes can provide high resolution information on lithological and hydrological features the technique may be applied in tomographic mode and in a much simpler vertical profile mode both modes of measurement have been utilized using two boreholes 5 m apart located at a field site in the uk sherwood sandstone aquifer radar transmission measurements have been used to characterize the change in moisture content in unsaturated sandstone due to controlled water tracer injection continual monitoring of cross borehole radar measurements over an 18 month period has also permitted determination of travel times of natural loading to the system and has revealed the impact of subtle contrasts in lithology on changes in moisture content over time the time series of inferred moisture contents show clearly wetting and drying fronts migrating at a rate of approximately 2 m month 1 throughout the sandstone

the southern caspian a compressional depression floored by a trapped modified oceanic crust the south caspian intracontinental depression floored by oceanic basement is a relatively stable block with minor deformation surrounded by active fold thrust belts of arcuate form talesh alborz and kopeh dagh mountains which have undergone intense late cainozoic crustal shortening the basin is interpreted as a neogene quaternary compressional depression bounded by multi role mountain bordering reverse faults and apparently floored by a late paleozoic triassic or late mesozoic early tertiary modified oceanic crust trapped along an old geosuture it may be a relic of an old paleozoic triassic ocean or else a marginal sea developed behind a mesozoic paleogene ocean and analysis of geological and geophysical data enables a scheme to be suggested the general arcuate shape of the alborz and the talesh bordering mountain belts follows the pattern of the supposed rigid and thickened ocean crust of south caspian depression a tectono sedimentary study of the south caspian region coupled w

the sarcheshmeh porphyry copper deposit kerman iran a mineralogical analysis of the igneous rocks and alteration zones including halogen element systematics related to cu mineralization processes abstract the giant sarcheshmeh porphyry copper deposit is located 65 km southwest of kerman city southeastern iran numerous miocene porphyry stocks and dykes intruded thick sequences of upper cretaceous sedimentary and eocene volcanic rocks hypogene and supergene porphyry cu mineralization occurs within the granodioritic porphyry and host rock sequence which was extensively altered to a dominantly potassic phyllic and argillic assemblage with interstitial to distal propylitic types biotite bearing assemblages occur as both primary phenocrysts and secondary replacements showing variable size colour and shape fluorine contents 0 22 to 1 33 wt and x mg 0 54 to 0 71 in biotites from the potassic and phyllic zones are higher than those of non mineralized granitoids f 0 09 to 0 56 wt x mg 0 43 to 0 54 whereas their cl contents cl 0 05 to 0 24 wt are lower than those of the non mineralized granitoids cl 0 11 to 0 45 the biotites from the phyllic zone have higher log f h 2 o f hf and log f h 2 o f hcl values than those of the potassic zone as well as the granitoid and andesitic dykes the log f hf f hcl values determined for the granitoid potassic and phyllic zones are similar though more negative than those of the andesitic dykes the log f hf f hcl values have a similar range for biotite from the granitoid and potassic and phyllic zones the halogen fugacity ratios established for fluids associated with the sarcheshmeh deposit from their f and cl contents in biotite show that the granitoid potassic zone and phyllic zone are increasingly affected by meteoric waters the fluids that circulated in the phyllic zone are predominantly of meteoric origin possibly overprinting original phyllic zone halogen contents the cl intercept values of biotite in the granitoid and phyllic and potassic are similar to other ore forming systems and tend to be more cl rich than cl intercept values of biotites in common igneous rocks calculated f cl intercept values for biotite in the granitoid and potassic zone are also consistent with many other porphyry copper forming systems

the role of water rock interaction and fluid evolution in forming the porphyry related sisson brook w cu mo deposit new brunswick sisson brook is a subeconomic w cu mo deposit associated with devonian porphyritic intrusions and hosted by metagabbro mafic metavolcanics felsic metavolcanics and metasediments four stages of veining and alteration have been recognized early mineralization consisted of disseminated and vein bearing molybdoscheelite accompanied by pervasive amphibole alteration subsequent scheelite and molybdenite deposition was restricted largely to quartz veins and was associated with biotitization both stages of mineralization were concentrated in metagabbro and mafic metavolcanics the final mineralization stage consisted of wolframite and chalcopyrite in quartz vein stockworks associated with phyllic alteration and developed mainly in felsic metavolcanics and metasedimentary rocks analyses of amphibole and mass balance calculations show that na super was added to the rock and that si super 4 mg super 2 and ca super 2 were leached during molybdoscheelite mineralization a relatively high f sub o 2 fluid is indicated by increases in the fe super 3 fe super 2 ratio of the alteration amphibole and a low f sub s 2 by the associated iron enrichment mass balance calculations show that mg super 2 and ca super 2 continued to be leached during scheelite molybdenite mineralization and si super 4 which had previously been leached was added to the rock with k super and na super fluid inclusion data suggest that w cu mo mineralization was deposited from a comparatively low salinity aqueous liquid at temperatures between 330 degrees and 430 degrees c the highest temperatures were attained during the second stage of mineralization at which time minor hypersaline fluids also circulated in the hydrothermal system a model is proposed in which hydrothermal activity was initiated by the circulation of meteoric formational waters in metagabbro adjacent to moderately high level porphyry intrusions this stage was marked by low fluid rock ratios which controlled mineralization by fixing molybdoscheelite with ca supplied by the host rocks an increase in temperature during subsequent molybdenite scheelite mineralization was the result of the introduction of orthomagmatic fluids from the porphyries the major change in mineralizing conditions was an increase in f sub s 2 which permitted deposition of molybdenite and gave rise to scheelite instead of molybdoscheelite scheelite deposition was caused by the high ca contents of the host rocks and or destabilization of kwo super 4 ion pairs as a result of biotitization fluid rock ratios reached a maximum during deposition of wolframite and chalcopyrite reflecting the influx of meteoric waters through large open fracture systems the wolframite and chalcopyrite were deposited as a result of decreasing temperature or in the case of chalcopyrite and or decreasing ph and or increasing f sub s 2 the study demonstrates the importance of fluid rock interaction and the nature of the host lithologies in controlling this style of w cu mo mineralization

monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques automated monitoring of freeze thaw cycles and fracture propagation in mountain rockwalls is needed to provide early warning about rockfall hazards conventional geoelectrical methods such as electrical resistivity tomography ert are limited by large and variable ohmic contact resistances requiring galvanic coupling with metal electrodes inserted into holes drilled into rock and which can be loosened by rock weathering we report a novel experimental methodology that combined capacitive resistivity imaging cri ert and microseismic event recording to monitor freeze thaw of six blocks of hard and soft limestones under conditions simulating an active layer above permafrost and seasonally frozen rock in a nonpermafrost environment our results demonstrate that the cri method is highly sensitive to freeze thaw processes it yields property information equivalent to that obtained with conventional ert and offers a viable route for nongalvanic long term geoelectrical monitoring extending the benefits of the methodology to soft hard rock environments contact impedances achieved with cri are less affected by seasonal temperature changes the aggregate state of the pore water liquid or frozen and the presence of low porosity rock with high matrix resistivities than those achieved with ert microseismic monitoring has the advantage over acoustic emissions that events were recorded in relevant field distances of meters to decameters from cracking events for the first time we recorded about 1000 microcracking events and clustered them in four groups according to frequency and waveform compared to previous studies mainly on ice cracking in glaciers the groups are attributed to single or multiple stage cracking events such as crack coalescence

porphyry cu mo au deposits related to melting of thickened mafic lower crust examples from the eastern tethyan metallogenic domain abstract most porphyry cu deposits in the world occur in magmatic arc settings and are formed in association with calc alkaline arc magmas related to subduction of oceanic lithosphere this contribution reviews a number of significant porphyry cu deposits in the eastern tethyan metallogenic domain they widely occur in a variety of non arc settings varying from post late collisional transpressional and extensional environments to intracontinental extensional environments related to orogenic and anorogenic processes their spatial temporal localization is controlled by strike slip faults orogen transverse normal faults lineaments and their intersections in these non arc settings these deposits are dominated by porphyry cu mo deposits with minor porphyry cu au and epithermal au deposits and exhibit a broad similarity with those in magmatic arcs the associated magmas are generally hydrous relatively high fo2 high k calc alkaline and shoshonitic and show geochemical affinity with adakites they are distinguished from arc magmas and or oceanic slab derived adakites by their occurrence as isolated complexes high k2o contents 1 2 8 5 and much wider range of end t values 10 to 3 and positive ehf t values 4 6 to 6 9 these potassic magmas are most likely formed by partial melting of thickened juvenile mafic lower crust or delaminated lower crust but also involving various amounts of asthenospheric mantle components key factors that generate hydrous fertile magmas are most likely crust mantle interaction processes at the base of thickened lower crust in non arc settings rather than oceanic slab dehydration as in arc settings breakdown of amphibole in thickened lower crust e g amphibole eclogite and garnet amphibolite during melting is considered to release fluids into the fertile magmas leading to an elevated oxidation state and higher h2o content necessary for development of porphyry cu mo au systems copper and au in hydrous magmas are likely derived from mantle derived components and or melts which either previously underplated and infiltrated at the base of the thickened lower crust or were input into the primitive magmas by melt mantle interaction in contrast mo and part of the s in the fertile magmas are probably supplied by old crust during melting and subsequent ascent

mo isotope fractionation during hydrothermal evolution of porphyry cu systems we present mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the kerman region iran the data provide new insights into controlling processes on mo isotope fractionation during the hydrothermal evolution of porphyry systems the mo isotope compositions of 27 molybdenite samples show wide variations in 97mo ranging from 0 37 to 0 92 the data reveal that molybdenites in the early and transitional stages of mineralization preferentially 2h polytypes 97mo mean 0 35 have higher 97mo values than late stage mainly 3r polytypes 97mo mean 0 02 molybdenites this trend suggests that fractionation of mo isotopes occurred in high temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower 97mo values taking into account the genetic models proposed for porphyry cu deposits along with the temperature dependent fractionation of mo isotope ratios it is proposed that large variations of mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore forming fluid phases with different density ph and o2 properties i e brine and vapor the fractionation of mo isotopes during fluid boiling and rayleigh distillation processes likely dominates the mo isotope budget of the remaining ore forming fluids for the late stage of mineralization the lower 97mo values in the late stage of mineralization can be explained by depletion of the late ore forming hydrothermal solutions in 97mo as these fluids have moved to considerable distance from the source finally the relationship observed between mos2 polytypes 2h and 3r and their mo isotopic compositions can be explained by the molecular vibration theory in which heavier isotopes are preferentially partitioned into denser primary 2h mos2 crystals

contribution of mantle components within juvenile lower crust to collisional zone porphyry cu systems in tibet most porphyry cu mo au deposits are found in magmatic arcs worldwide and are associated with hydrous high fo2 calc alkaline magmas derived from a mantle wedge that was metasomatized by the fluids from a subducted oceanic slab recently such deposits have been documented as occurring widely in collisional settings where they are associated with potassic magmas generated during the collisional process but the genesis of the fertile magmas and the mechanism of metallic enrichment remain controversial here we present new geochemical and sr nd hf isotopic data from the post collisional fertile and barren porphyries of the miocene gangdese porphyry belt in the tibetan orogen an orogen formed by the collision of india and asia in the early cenozoic both types of porphyry are characterized by high k2o contents and have geochemical affinities with adakite but the fertile magmas were most likely derived from the melting of a thickened juvenile mafic lower crust formed by the underplating of earlier asthenospheric melts at the base of crust whereas the derivation of the barren magmas involved variable amounts of old lower crust in tibet the melting of sulfide bearing phases in the juvenile mantle components of the tibetan lower crust probably provided cu au and s to the fertile magmas the breakdown of amphibole during melting at the source released the fluids necessary for the formation of the porphyry cu deposits in tibet the thickened crust up to 70 80 km due to collision is thought to be responsible for a decrease in the fo2 of the fertile magmas during their ascent to the upper crust thus preventing the generation of more porphyry cu au and epithermal au deposits in this collisional zone

structural controls on the localization of cu deposits in the kerman cu metallogenic province of iran using geoinformatic techniques abstract the sarcheshmeh area is located in the kerman cu metallogenic province kcmp in the southeastern part of the uramia dokhtar magmatic arc in iran the sarcheshmeh contains numerous cu deposits making it ideal for the study on the structural controls in the magmatic arc the study area is cut by major first order and minor second order faults and contains different types of cu occurrences which have been here studied using geoinformation techniques git which consist of remote sensing techniques gis analyses and careful field investigations the outcome of this study has confirmed that the cu mineralization in kcmp is structurally controlled in faults on a regional scale the major faults together with their second order splays form a braided fault pattern containing predominantly se trending faults on a local scale the main faults together with their splays form a rhombohedral pattern which is due to a transtensional deformation related to the formation of pull apart basins along the kcmp this tectonic regime prepared the suitable environment for the ascent and final emplacement of felsic plutons in a broad linear zone trending se the cu mineralization and accompanying alteration zones are hosted by the second order faults

hydrochemistry mineralogy and chemical fractionation of mine and processing wastes associated with porphyry copper mines a case study from the sarcheshmeh mine se iran abstract the sarcheshmeh is one of the largest oligo miocene porphyry cu deposits in the world comparative hydrochemical mineralogical and chemical fractionation associated with mining efflorescence salts and processing wastes of this mine are discussed hydrochemical results showed that rock waste dumps reject wastes and old impoundments of tailings are the main sources of acid mine drainage waters amd that contain potentially toxic metals such as cd co cu mn ni and zn as well as al episodic fluxes of highly contaminated acidic waters were produced in a tailings dam over a short period of time secondary soluble minerals provide important controls on the quality of amd produced especially in old dry tailings impoundments secondary sulfate minerals such as gypsum magnesiocopiapite hydronium jarosite kornelite and coquimbite were found in rock waste drainages and in old weathered reject wastes highly soluble secondary minerals such as gypsum eriochalcite and bonattite are also observed in an evaporative layer on old tailings impoundments chemical fractionation patterns of potentially toxic elements showed that the geochemical behavior of metals is primarily controlled by the mineralogical composition of waste samples elements such as co cr cu mn ni and zn are readily released into the water soluble fraction from efflorescence salts associated with rock waste drainages as well as from the evaporative layer of old tailings potentially toxic elements such as as mo and pb are principally adsorbed or co precipitated with amorphous and crystalline fe oxides but they may also be associated with oxidizing primary sulfides and residual fractions following the development of the dammed tailings pond the secondary minerals were dissolved producing acidic waters contaminated by al 154 mg l 1 cu 150 mg l 1 cd 0 31 m gl 1 co 2 13 mg l 1 mn 73 7 mg l 1 ni 1 74 mg l 1 zn 20 3 mg l 1 and cl 1690 mg l 1 therefore the potential use of recycled water from the sarcheshmenh dammed tailings pond is diminished by the presence of corrosive ions like cl in highly acidic fluids that promote corrosion of pipes and pumps in the water recycling system

borehole time domain reflectometry in layered sandstone impact of measurement technique on vadose zone process identification the hydraulic behaviour of the vadose zone of a layered sandstone aquifer has been investigated using borehole based time domain reflectometry tdr both a commercially available portable packer tdr system trime b3l borehole packer probe and specially designed borehole emplaced tdr probes were used to monitor seasonal fluctuations in water content in the vadose zone of a layered sandstone over 1 year under natural rainfall loading the data show that the vadose zone contains seasonal perched water tables that form when downward percolating water reaches layers of fine grained sandstone and siltstone and causes local saturation the formation of perched water tables is likely to lead to lateral flow bypassing the less permeable finer layers this contrasts with behaviour inferred from previous studies of the same aquifer that used borehole radar and resistivity which suggested its vadose zone behaviour was characterized by uniform downwards migration of wetting fronts to investigate the impact of measurement technique on observed response the tdr data reported here were used to produce simulated zero offset profile zop borehole radar responses this simulation confirmed the limited ability of zop borehole radar to detect key vadose zone processes because the phenomenon of critical refraction minimizes the sensitivity of the results to high water content layers the ability of the resistivity method to detect perched water table responses is also limited because of the relatively large sampling volume of the technique the study illustrates that inappropriate technique selection results in hydrological process mis identification with serious consequences for the usefulness of data in hydrological modeling

quantification of co2 generation in sedimentary basins through carbonate clays reactions with uncertain thermodynamic parameters abstract we develop a methodological framework and mathematical formulation which yields estimates of the uncertainty associated with the amounts of co 2 generated by carbonate clays reactions ccr in large scale subsurface systems to assist characterization of the main features of this geochemical process our approach couples a one dimensional compaction model providing the dynamics of the evolution of porosity temperature and pressure along the vertical direction with a chemical model able to quantify the partial pressure of co 2 resulting from minerals and pore water interaction the modeling framework we propose allows i estimating the depth at which the source of gases is located and ii quantifying the amount of co 2 generated based on the mineralogy of the sediments involved in the basin formation process a distinctive objective of the study is the quantification of the way the uncertainty affecting chemical equilibrium constants propagates to model outputs i e the flux of co 2 these parameters are considered as key sources of uncertainty in our modeling approach because temperature and pressure distributions associated with deep burial depths typically fall outside the range of validity of commonly employed geochemical databases and typically used geochemical software we also analyze the impact of the relative abundancy of primary phases in the sediments on the activation of ccr processes as a test bed we consider a computational study where pressure and temperature conditions are representative of those observed in real sedimentary formation our results are conducive to the probabilistic assessment of i the characteristic pressure and temperature at which ccr leads to generation of co 2 in sedimentary systems ii the order of magnitude of the co 2 generation rate that can be associated with ccr processes

application of best worst method and additive ratio assessment in mineral prospectivity mapping a case study of vein type copper mineralization in the kuhsiah e urmak area iran abstract this study proposes the application of a hybrid methodology combining the best worst method bwm and additive ratio assessment aras approaches to mineral prospectivity mapping the aras approach is used to prioritize and rank individual cells the bwm on the other hand is useful for assigning weights to the spatial proxies of the mineralized system representing mappable expressions of the ore forming processes a dataset of vein type copper mineralization including geochemical geophysical geological and remotely sensed data from the kuhsiah e urmak area iran was translated into a set of mappable spatial proxies representing the genetic processes involved in the formation of the vein type copper mineralization a hybrid bwm aras method was applied to the spatial proxies used to generate the mineral potential map the results of the proposed methodology were statistically compared to those obtained from the index overlay and technique for order of preference by similarity to ideal solution topsis methods using the rate of correct classification in confusion matrices and demonstrating the superiority of the proposed methodology a field trip was conducted to assess the most prospective target zones and to collect samples for analysis the majority of these samples returned significant copper contents with copper ores observed in most of the polished sections prepared from these samples considering these results the newly proposed bwm aras approach appears to offer a viable alternative to the conventional methods applied to knowledge driven mineral prospectivity mapping

increasing magmatic oxidation state from paleocene to miocene in the eastern gangdese belt tibet implication for collision related porphyry cu mo au mineralization in the gangdese belt of southern tibet paleocene eocene magmas record the final stage of neo tethyan subduction and are associated with few economic porphyry deposits in contrast magmas formed during later stages of the india asia collision in the oligo miocene are associated with several large porphyry cu mo au deposits especially in the eastern part of the belt 89 e 93 e in a previous study we showed that these oligocene miocene magmas were more hydrous than the earlier paleocene eocene magmas in this study we show that the later magmas were also more oxidized paleocene eocene rocks from the eastern gangdese belt are characterized by low zircon ce4 ce3 ratios mostly 50 32 3 141 9 average 74 3 30 1 n 33 and higher f o2 values fmq 0 8 2 9 average 1 8 0 8 n 6 estimated from magnetite ilmenite pairs estimates of magmatic oxidation state from amphibole compositions also show an increase from fmq 1 2 to 2 1 average 1 6 0 2 n 40 in the paleocene eocene to 2 0 to 2 8 average 2 5 0 2 n 58 in the miocene sparse whole rock fe3 fe2 ratios show the same general trend the amphibole results are systematically shifted to higher fmq compared to data from magnetite ilmenite pairs but their trend is internally consistent the higher oxidation states and water contents of miocene igneous rocks from the eastern gangdese belt may explain their unique association with large porphyry deposits in tibet because it has been shown from other studies that the potential for hydrous calc alkaline magmas to transport au is maximized near fmq 1 0 and cu at higher f o2 fmq 1 0 in comparison the somewhat less oxidized and less hydrous paleocene eocene magmas would have been less fertile for the formation of such deposits we suggest that these differences reflect the tectonomagmatic evolution of the cenozoic gangdese collisional orogen from early collision related magmatism in the paleocene eocene to late collisional magmatism in the miocene asthenospheric upwelling following slab breakoff in the miocene caused interaction between mantle derived magmas and previously subduction modified tibetan lithosphere the resultant evolved magmas had high oxidation states and water contents which are favorable properties for the subsequent formation of magmatic hydrothermal porphyry cu mo au deposits

risk quantification with combined use of lithological and grade simulations application to a porphyry copper deposit abstract the uncertainty in the recoverable tonnages and grades in a mineral deposit is a key factor in the decision making process of a mining project currently the most prevalent approach to model the uncertainty in the spatial distribution of mineral grades is to divide the deposit into domains based on geological interpretation and to predict the grades within each domain separately this approach defines just one interpretation of the geological domain layout and does not offer any measure of the uncertainty in the position of the domain boundaries and in the mineral grades this uncertainty can be evaluated by use of geostatistical simulation methods the aim of this study is to evaluate how the simulation of rock type domains and grades affects the resources model of sungun porphyry copper deposit northwestern iran specifically three main rock type domains porphyry skarn and late injected dykes that control the copper grade distribution are simulated over the region of interest using the plurigaussian model the copper grades are then simulated in cascade generating one grade realization for each rock type realization the simulated grades are finally compared to those obtained using traditional approaches against production data

petrogenesis of dongguashan skarn porphyry cu au deposit related intrusion in the tongling district eastern china geochronological mineralogical geochemical and hf isotopic evidence the dongguashan skarn porphyry cu au deposit located in the tongling district of the middle lower yangtze river valley metallogenic belt mlyb consists of skarn ore bodies in the upper part and porphyry ore bodies in the lower part both of which are hosted in quartz diorite and quartz monzodiorite zircon u pb age and geochemical studies show that the quartz diorite of the dongguashan intrusion formed at 140 3 2 0 ma mswd 0 19 and belongs to the high potassium calc alkaline series it is enriched in large ion lithophile elements lile and light rare earth elements lree depleted in high field strength elements hfse and heavy rare earth elements hree and has a slightly negative eu anomaly 176hf 177hf values of the rims of zircons show a variable range 0 282087 0 282391 corresponding with calculated ehf t values of 10 72 to 21 46 plagioclases in the quartz diorite have unbalanced structure characterized by bright andesine and labradorite an 37 0 65 5 cores with higher contents of fe and sr and are corroded by dark oligoclase an 13 8 27 6 rim major elements trace elements hf isotope and the composition of plagioclases indicate that the parental magma of the dongguashan intrusion was produced by the mixing of underplating mafic magma and felsic magma formed by remelting of paleoproterozoic and neoarchean crustal rocks neoproterozoic crust may also provide some material to the felsic magma mafic magma played a key role and made the parental magma rich in water sulfur metals cu au and gave it a high oxygen fugacity during its magmatic evolution the parental magma underwent fractional crystallization of hornblende apatite sphene and other mafic minerals some quartz diorite and quartz monzodiorite samples that show adakitic signatures may result from injection of mafic magma some inherited zircons of the quartz diorite in the dongguashan intrusion gave ages of 2 40 2 50 ga 1 95 2 05 ga and 0 74 0 81 ga coming from ultramafic mafic and andesitic igneous rocks and this indicates that there may have been three periods 2 4 2 0 and 0 8 ga of magmatic activity in the tongling district

potential use of time domain reflectometry for measuring water content in rock abstract quantifying water movement through bedrock materials requires a technique which can accurately measure water content at precise locations within the medium time domain reflectometry tdr is widely used to measure the water content of soil and has a measurement sensitivity which is tightly confined to the area immediately surrounding the probes this study applies tdr to the measurement of water content in rocks the technique was evaluated using sandstone and welded tuff in a series of laboratory experiments a block of each rock type was instrumented with a series of evenly spaced tdr probes each block was first saturated with water and then allowed to air dry the water content was determined gravimetrically using the tdr over a period of several weeks the results indicate that the tdr technique can be used to determine the water content of rock with an accuracy comparable with that reported for the technique used in soils

hydrothermal evolution of the sar cheshmeh porphyry cu mo deposit iran evidence from fluid inclusions abstract the sar cheshmeh porphyry cu mo deposit is located in southwestern iran 65 km southwest of kerman city and is associated with a composite miocene stock ranging in composition from diorite through granodiorite to quartz monzonite field observations and petrographic studies demonstrate that the emplacement of the sar cheshmeh stock took place in several pulses each with associated hydrothermal activity molybdenum was concentrated at a very early stage in the evolution of the hydrothermal system and copper was concentrated later four main vein groups have been identified i quartz molybdenite anhydrite k feldspar with minor pyrite chalcopyrite and bornite ii quartz chalcopyrite pyrite molybdenite calcite iii quartz pyrite calcite chalcopyrite anhydrite gypsum molybdenite iv quartz calcite gypsum pyrite dolomite early hydrothermal alteration produced a potassic assemblage orthoclase biotite in the central part of the stock propylitic alteration occurred in the peripheral parts of the stock contemporaneously with potassic alteration and phyllic alteration occurred later overprinting earlier alteration the early hydrothermal fluids are represented by high temperature 350 520 c high salinity up to 61 wt nacl equivalent liquid rich fluid inclusions and high temperature 340 570 c low salinity vapor rich inclusions these fluids are interpreted to represent an orthomagmatic fluid which cooled episodically the brines are interpreted to have caused potassic alteration and deposition of group i and ii quartz veins containing molybdenite and chalcopyrite propylitic alteration is attributed to a liquid rich lower temperature 220 310 c ca rich evolved meteoric fluid influx of meteoric water into the central part of the system and mixing with magmatic fluid produced albitization at depth and shallow phyllic alteration this influx also caused the dissolution of early formed copper sulphides and the remobilization of cu into the sericitic zone the main zone of the copper deposition in sar cheshmeh where it was redeposited in response to a decrease in temperature

mineral chemistry of hydrothermal biotite from the kahang porphyry copper deposit ne isfahan central province of iran abstract the kahang porphyry cu deposit located northeast of isfahan city in central of iran is associated with a composite miocene stock and ranges in composition from diorite through granodiorite to quartz monzonite field observations and petrographic studies show that the emplacement of the kahang stock occurred in several pulses each associated with its related hydrothermal activity early hydrothermal alteration started with a potassic style in the central part of the system and produced a secondary biotite k feldspar magnetite assemblage accompanied by chalcopyrite and pyrite mineralization propylitic alteration that took place at the same time as the potassic alteration occurred in the peripheral portions of the stock subsequent phyllic alteration overprinted earlier potassic and propylitic alterations biotite grains from the potassic and phyllic zones show distinct chemical compositions the feo tio2 mno k2o and na2o concentrations in biotite from the phyllic alteration zone are lower than those from the potassic alteration zone the f and cl contents of biotite from the potassic alteration zone display relatively high positive correlation with the xmg the fluorine intercept values iv f from the potassic and phyllic alteration zones are strongly correlated with the fluorine chlorine intercept values iv f cl biotite geothermometry for the potassic and phyllic alteration zones based on the biotite geothermometer of beane 1974 yields a temperature range of 422 to 437 c mean 430 c and 329 to 336 c mean 333 c respectively the position of data in log xf xoh ratio vs xmg and xfe diagram suggests that biotite formed under dissimilar composition and temperature conditions in the potassic and phyllic alteration zones calculated log fugacity ratios of fh2o fhf fh2o fhcl and fhf fhcl show that hydrothermal fluids associated with the potassic alteration were distinctively different from those fluids associated with the phyllic alteration zone at kahang porphyry cu deposit the results of this research indicate that the chemistry of biotite is related to the chemical composition of the magma and the prevailing physical conditions during crystallization

exploration feature selection applied to hybrid data integration modeling targeting copper gold potential in central iran abstract a sugeno type fuzzy inference system is implemented in the framework of an adaptive neural network to map cu au prospectivity of the urumieh dokhtar magmatic arc udma in central iran we use the hybrid adaptive neuro fuzzy inference system anfis jang 1993 algorithm to optimize the fuzzy membership values of input predictor maps and the parameters of the output consequent functions using the spatial distribution of known mineral deposits generic genetic models of porphyry copper gold and iron oxide copper gold iocg deposits are used in conjunction with deposit models of the dalli porphyry copper gold deposit aftabru iocg prospect and other less important cu au deposits within the study area to identify recognition criteria for exploration targeting of cu au deposits the recognition criteria are represented in the form of gis predictor layers spatial proxies by processing available exploration data sets which include geology stream sediment geochemistry airborne magnetics and multi spectral remote sensing data an anfis is trained using 30 of the 61 known cu au deposits prospects and occurrences in the area in a parallel analysis an exclusively expert knowledge driven fuzzy model was implemented using the same input predictor maps although the neuro fuzzy analysis maps the high potential areas slightly better than the fuzzy model the well known mineralized areas and several unknown potential areas are mapped by both models in the fuzzy analysis the moderate and high favorable areas cover about 16 of the study area which predict 77 of the known copper gold occurrences by comparison in the neuro fuzzy approach the moderate and high favorable areas cover about 17 of the study area which predict 82 of the copper gold occurrences

extent of underthrusting of the indian plate beneath tibet controlled the distribution of miocene porphyry cu mo au deposits miocene igneous rocks in the 1 600 km long e w gangdese belt of southern tibet form two groups separated at longitude 89 e the eastern group is characterized by mainly intermediate felsic calc alkaline plutons with relatively high sr y ratios 23 to 342 low 87sr 86sr i ratios 0 705 to 0 708 and high endi values 5 5 to 6 1 in contrast the western group is characterized by mainly potassic to ultrapotassic volcanic rocks with relatively high th and k2o contents low sr y ratios 11 to 163 high 87sr 86sr i ratios 0 707 to 0 740 and low endi values 4 1 to 17 5 the eastern plutonic group is associated with several large porphyry cu mo au deposits whereas the western group is largely barren we propose that the sharp longitudinal distinction between magmatism and metallogenic potential in the miocene gangdese belt reflects the breakoff of the greater india slab and the extent of underthrusting by the indian continental lithosphere at that time magmas to the east of 89 e were derived by partial melting of subduction modified tibetan lithosphere mostly lower crust triggered by heating of hot asthenospheric melt following slab breakoff these magmas remobilized metals and volatile residual in the crustal roots from prior arc magmatism and generated porphyry cu mo au deposits upon emplacement in the upper crust in contrast magmas to the west of 89 e were formed by smaller volume partial melting of tibetan lithospheric mantle metasomatized by fluids and melts released from the underthrust indian plate they are less hydrous and oxidized and did not have the capacity to transport significant amounts of metals into the upper crust

environmental geochemistry of rare earth elements in cu porphyry mine tailings in the semiarid climate conditions of sarcheshmeh mine in southeastern iran abstract sarcheshmeh mine is one of the largest oligo miocene porphyry cu deposits in the world it is located in the kerman cenozoic magmatic arc in southeastern iran this paper discusses the geo environmental behavior of rare earth elements rees in the sarcheshmeh dammed tailing pond situated in semiarid climate for this purpose solid and water samples were collected to consider 1 weathering oxidation reactions and upward migration of soluble elements 2 super saturation and formation dissolution of the secondary evaporative phases 3 hydro geochemical changes of the surface and groundwater resources 4 flotation of the cu sulfide ore and tailing management strategies the mean values of the rees for fresh and weathered tailings and the evaporative phases were 113 0 103 7 and 74 6 mg kg respectively when compared with the fresh and weathered tailings the evaporative phases showed significant enrichment of hrees and a well depleted pattern of lrees except for that of eu this geochemical pattern suggests a higher solubility and mobility potential of hrees and eu compared with lrees resulting in good fractionation and enrichment of these elements in the surface evaporative layer formed on top of the weathered tailings the water samples showed a range of hydro geochemical features under acidic ph of 2 5 to 4 7 near neutral ph of 6 4 to 7 9 alkaline ph of 8 to 10 and highly alkaline ph 10 conditions the maximum concentration of rees was observed in the acidic waters produced by the weathered tailings after rainfall rees of 489 to 1903 g l although rees decreased as the ph value increased the general trend was compatible with the highest concentration of hrees rather than lrees the speciation calculations indicate that lnso4 ln so4 2 and ln3 are the primary forms of dissolved rees at acidic and near neutral ph and the dominant species was lnso4 lnco3 40 78 ln co3 2 31 68 and lnso4 31 07 were the dominant species under alkaline conditions at high alkaline ph the speciation pattern changed to lnoh2 53 15 ln co3 2 44 88 and lnco3 2 61 where ln denotes lanthanide based on the results and considering previous works it appears that ionic potential plays an important role in the geo environmental behavior of rees of adsorption tendency mobility potential and ionic substitution

spectral characteristics of minerals in alteration zones associated with porphyry copper deposits in the middle part of kerman copper belt se iran abstract visible near infrared and shortwave infrared vnir swir 350 to 2500 nm reflectance spectra obtained from an analytical spectral device asd have been used to define alteration zones adjacent to porphyry copper deposits pcds in the central part of kerman magmatic arc se iran the spectral analysis identified sericite illite halloysite montmorillonite dickite kaolinite pyrophyllite biotite chlorite epidote calcite jarosite and iron oxyhydroxides e g hematite goethite of hydrothermal and supergene origin identified alteration zones are classified into six principal types namely phyllic phyllic propylitic propylitic potassic argillic and advanced argillic the iron oxide minerals in the oxidized zone were also identified using spectral analysis results of spectral analyses of samples are consistent with mineralogical data obtained from x ray diffraction xrd and petrographic studies spectroscopic studies by asd demonstrate that this tool is very useful for semi quantitative and cost effective identification of different types of alteration mineral assemblages furthermore it can provide a valuable tool for evaluating aerial distribution of alteration minerals while coupled with remote sensing data analysis

identification of hydrothermal alteration minerals for exploring of porphyry copper deposit using aster data se iran the nw se trending central iranian volcanic belt hosts many well known porphyry copper deposits in iran it becomes an interesting area for remote sensing investigations to explore the new prospects of porphyry copper and vein type epithermal gold mineralization two copper mining districts in southeastern segment of the volcanic belt including meiduk and sarcheshmeh have been selected in the present study the performance of principal component analysis band ratio and minimum noise fraction transformation has been evaluated for the visible and near infrared vnir and shortwave infrared swir subsystems of aster data the image processing techniques indicated the distribution of iron oxides and vegetation in the vnir subsystem hydrothermal alteration mineral zones associated with porphyry copper mineralization identified and discriminated based on distinctive shortwave infrared swir properties of the aster data in a regional scale these techniques identified new prospects of porphyry copper mineralization in the study areas the spatial distribution of hydrothermal alteration zones has been verified by in situ inspection x ray diffraction xrd analysis and spectral reflectance measurements results indicated that the integration of the image processing techniques has a great ability to obtain significant and comprehensive information for the reconnaissance stages of porphyry copper exploration in a regional scale the results of this research can assist exploration geologists to find new prospects of porphyry copper and gold deposits in the other virgin regions before costly detailed ground investigations consequently the introduced image processing techniques can create an optimum idea about possible location of the new prospects

rock moisture measurements techniques results and implications for weathering rock moisture is an important factor for the intensity and distribution of frost weathering processes however quantitative measurements are scarce which is partly due to the lack of reliable measurement techniques this paper presents five different techniques for obtaining rock moisture data while collecting rock pieces and two dimensional geoelectric measurements allow determination of the spatial moisture distribution the temporal variability can be derived from conductivity and time domain reflectometry records computer simulations using rock properties and climatic records as input data render it possible to clarify the important aspects that are responsible for the moisture distribution it proved to be advisable to use several methods to check and validate the results the results obtained in study areas in the bavarian alps make it clear that direct rainfall is the main source of rock moisture the influence of snow is limited to the immediate vicinity of the snow fields and is not equally pronounced at different times and positions rock moisture levels are higher in summer than they are in winter since in winter less water is supplied in liquid form northerly exposed rockwalls are generally more moist than those exposed in a southerly direction which is due to the different insolation as well as to the wind direction during rainfall in every position the rock is on average wetter on the inside than it is on the surface this means that shallow frost cycles as typical for south exposed sites are not affecting weathering since they take place at a depth level that is mostly dried out numerous spatial and temporal patterns of rockfall found in the same study areas can be explained through variations in rock moisture thus the moisture content of the rock is considered to be one of the major controlling factors of the frost shattering rate copyright 2005 john wiley sons ltd

application of time domain reflectometry to determination of volumetric water content in rock time domain reflectometry tdr is a widely used technique for measuring soil water content to examine its applicability to rock the authors applied tdr to a variety of rocks in the laboratory the obtained relationships between the apparent dielectric constant and the volumetric water content showed a behavior that can be partly explained by the effect of gaps between the tdr probe and rock for rocks with an effective porosity smaller than that of soil the well known model presented by topp et al 1980 for soil tended to overestimate the water content for such rocks it was determined that an individual calibration was needed for accurate determination of water content if no experimental calibration is possible frequently used mixing models may be used to establish the calibration function our investigations suggest that tdr showed the potential for measuring the apparent dielectric constant of rock and further for determining water content in rock

fluid inclusion evidence for hydrothermal fluid evolution in the darreh zar porphyry copper deposit iran abstract the darreh zar porphyry copper deposit is associated with a quartz monzonitic granodioritic porphyritic stock hosted by an eocene volcanic sedimentary complex in which magmatic hydrothermal fluids were introduced and formed veins and alteration within the deepest quartz rich and chalcopyrite poor group a veins lvhs2 inclusions trapped high salinity high temperature aqueous fluids exsolved directly from a relatively shallow magma 0 5 kbar these late fluids were enriched in nacl and reached halite saturation as a result of the low pressure of magma crystallization and fluid exsolution these fluids extracted cu from the crystallizing melt and transported it to the hydrothermal system as a result of ascent the temperature and pressure of these fluids decreased from 600 to 415 c and approximately 500 315 bars at these conditions k feldspar and biotite were stabilized type a veins were formed at a depth of 1 2 km under conditions of lithostatic pressure and abrupt cooling upon cooling and decompressing the fluid intersected with the liquid vapor field resulting in separation of immiscible liquid and vapor this stage was recorded by formation of lvhs1 lvhs3 and vl inclusions these immiscible fluids formed chalcopyrite pyrite quartz veins with sericitic alteration envelopes b veins under the lithostatic hydrostatic pressure regime at temperatures between 415 and 355 c at 1 3 km below the paleowater table as the fluids ascended copper contents decreased and these fluids were diluted by mixing with the low salinity external fluid therefore pyrite dominated quartz veins were formed in purely hydrostatic conditions in which pressure decreased from 125 bars to 54 bars and temperature decreased from 355 to 298 c during the magmatic hydrothermal evolution the composition and p t regime changed drastically and caused various types of veins and alterations the abundance of chalcopyrite precipitation in group b veins suggests that boiling and cooling were important factors in copper mineralization in darreh zar