multi stage precipitation and redistribution of gold and its collection by lead bismuth and lead immiscible liquids in a reduced intrusion related gold system rirgs dublin gulch western canada abstract dublin gulch reduced intrusion related gold system rirgs located in the selwyn basin area of western canada represents one of the best examples of rirgs mineralization globally and hence can be studied to unravel genesis and evolution of these types of deposits based on textural relationships mineralogy and trace element mineral chemistry three auriferous vein stages were identified the paragenetic sequence for the auriferous vein stages are 1 eagle style es quartz albite low sulfide and sulfosalt content 30 vol as fe w pb bi au ag veins and 3 potato hills style 2 phs 2 high sulfide and sulfosalt content 30 vol fe pb sb zn cu au ag veins in the es and phs 1 veins au is present both as native gold au ag and as invisible gold in arsenopyrite whilst in the phs 2 veins au is present as invisible gold in pyrite native gold micrograins individual grains 1 100 s m in size are observed associated with pb minerals in anhedral to globular cosalite pb2bi2s5 in es veins or galena pbs in the phs 1 veins native gold is also observed as micrograins along arsenopyrite margins and in quartz fractures we suggest a variation on the hydrothermal bi melt collector model to explain the au pb bi association the au ag pb and bi are interpreted to have been locally remobilized from arsenopyrite which shows textures and trace element distribution patterns consistent with fluid and deformation assisted recrystallization we suggest pb and bi were mobilized either as immiscible nanodroplets that coalesced to form larger pb bi liquid accumulations or into the hydrothermal fluid and subsequently exsolved to form immiscible pb bi liquids we propose that remobilized au and ag were collected by these pb bi immiscible liquids subsequent retrograde alteration sulfidation is interpreted to have converted the au ag pb bi alloys to native gold and cosalite es and native gold and galena mineral assemblages phs 1 the similarity of the au ag ratios in native gold and arsenopyrite supports a local source for the native gold micrograins temperatures required to attain liquid pb0 5bi0 5 145 2 c and pb 327 5 c are consistent with arsenopyrite geothermometry es 345 405 c phs 1 380 c these suggested new variations pb bi and pb on the hydrothermal melt bi collector model are important given the common association of native gold with pb bi sulfosalts in many gold deposits and the relatively low temperatures required to maintain these liquids and collect au from the hydrothermal fluid

a study of metal bearing nanoparticles from the kangjiawan pb zn deposit and their prospecting significance abstract over the years using novel methods to find deep seated ore resources has always been a hot research topic in this paper we present a new method to investigate deep seated orebodies by characterizing metal bearing nanoparticles e g morphological features and chemical compositions in various media deep shallow groundwater ascending gas flow and soil via transmission electron microscopy tem from the kangjiawan pb zn deposit the study area the metal bearing nanoparticles collected from different media contain similar contents of ore forming elements e g cu zn pb fe and s and are strongly related to the presence of deep seated orebodies these ore related nanoparticles are grouped into four main categories i amorphous ii single crystal iii poly crystal and iv complex poly crystal in particular many amorphous nanoparticles in different media can transfer ore forming elements and provide mineralization information we propose that the ore forming elements exist and migrate in the form of these four types of nanoparticles the results can explain the geochemical anomalies and provide insights on the role of nanoparticles in post mineralization ore related elemental dispersion and could be useful in exploration for concealed orebodies

enhanced velocity tomography practical method of combining velocity and attenuation parameters acoustic ultrasonic tomography is now a well acepted method for investigating the internal structure of rock samples and rock masses in this article we describe a new parameter to be imaged which combines the robustness of velocity tomography and the sensitivity of attenuation tomography resulting in enhanced velocity tomography the theoretical considerations are illustrated by a computer simulation and then by application to data from a granite sample subjected to induced damage by heating in both cases the enhanced velocity tomography is found to be more sensitive to the internal rock structure than classical velocity tomography and overcomes instability problems characteristic of attenuation tomography

a review of te and se systematics in hydrothermal pyrite from precious metal deposits insights into ore forming processes abstract pyrite is one of the most common minerals in many precious and base metal hydrothermal ore deposits and is an important host to a range of trace elements including au and co and the semi metals as se sb te and bi as such in many hydrothermal ore deposits where pyrite is the dominant sulphide phase it can represent a major repository for these elements furthermore the concentrations and ratios of au as and co in pyrite have been used to infer key ore forming processes however the mechanisms controlling the distribution of te and se in pyrite are less well understood here we compare the te and se contents of pyrite from a global dataset of carlin type orogenic au and porphyry epithermal deposits to investigate 1 the potential of pyrite to be a major repository for these elements and 2 whether te and se provide insights into key ore forming processes pyrite from carlin type low sulphidation and alkaline igneous rock hosted epithermal systems is enriched in te and se compared to pyrite from high sulphidation epithermal and porphyry cu deposits orogenic au pyrite is characterised by intermediate te and se contents there is an upper solubility limit for te as a function of as in pyrite similar to that established for au by reich et al 2005 and this can be used to identify te present as telluride inclusions which are common in some epithermal porphyry and orogenic au deposits physicochemical fluid parameters such as ph redox and temperature as well as crystal chemistry control the incorporation and concentration of se and te in pyrite neutral to alkaline fluids have the ability to effectively mobilise and transport te fluid boiling in porphyry epithermal systems as well as wall rock sulphidation and oxidation in carlin type and orogenic au deposits can effectively precipitate te in association with pyrite and au in contrast se concentrations in pyrite apparently vary systematically in response to changes in fluid temperature irrespective of ph and f o 2 hence we propose that the se contents of pyrite may be used as a new geo thermometer for hydrothermal ore deposits furthermore the comparison of bulk ore and pyrite chemistry indicates that pyrite represents the major host for te and se in carlin type and some epithermal systems and thus pyrite can be considered to be of economic interest as a potential source for these elements

textural control on gold distribution in as free pyrite from the dongping huangtuliang and hougou gold deposits north china craton hebei province china article i nfo pyrite from the dongping huangtuliang and hougou gold deposits hebei province china was investigated using a combination of ore microscopy including back scattered imaging and in situ laser ablation inductively coupled plasma mass spectroscopy la icp ms a range of elements including au te ag pb bi cu co ni and as was analyzed with the aim to constrain the textural controls and influence of superimposed deformation on the distribution of invisible gold in as free pyrite thedatasetshowsexcellentcorrespondence betweenmeasuredhighgoldvaluesandthreekeytexturalcriteria i areasofclusteredtellurideinclusions especiallyindongping ii microshearingandfracturing brecciation dongping and huangtuliang and iii pyrite recrystallization huangtuliang invisible gold is only at trace levels in the hougou and gold bearing telluride minerals are not observed this is considered to result from larger scale remobilization of gold during advanced brecciation and recrystallization of pyrite pyrite grains containing clustered inclusions have by far the highest gold concentrations up to 1 wt with consistent values of thousands of ppm au interpretation of textures and la icp ms data infers that in these areas the distribution of telluride inclusions extends pervasively from micron to nanoscale i e as fields of nanoparticles local employment of coupled dissolution reprecipitation reaction between pyrite and fluids driving the k metasomatic alteration dated at 150 ma is invoked to explain such patterns syn deformational grain scale mobilization of gold and other elements took place leading to a portion of the gold being recrystallized within fractures and microshears the deformational event leads to gold enrichment in the huangtuliang pyrite where brittle fracturing brecciation has been followed by a resorption and recrystallization in the latter case foam textured pyrites again without as can contain up to hundreds of ppm gold theinterpreted sequenceof pyritepost depositional eventsis inaccordancewith the protracted magmaticevolution of the area starting with variscan alkaline intrusions 390 ma and reactivated during the yanshanian orogeny 150 ma thestudyshows i thatas freepyritecanreadilycontainsignificantamountsofinvisiblegold bothasnanoparticles

an overview of the platinum group element nanoparticles in mantle hosted chromite deposits abstract this paper reviews the occurrence of platinum group elements nanoparticles pge nps in mantle hosted chromite deposits showing that pge nps are more frequently found in these deposits than previously thought a comparison of published experimental data with observations in natural samples reveal that pge nps might form at the pressure 1 0 5 gpa temperature 1200 c and f o 2 fmq 1 conditions in which chromite deposits form in the upper mantle the crystallization of pge nps may take place earlier or simultaneously to the segregation of chromite and or sulfide liquids from silicate melts if the pges are dissolved in the silicate melt the segregation of pge nps could be linked to local changes in f o 2 and f s 2 during the early crystallization of chromite and or olivine mobile crystals of chromite and droplets of sulfide melts entrained in the basaltic parent melt may also play an additional role as physical collectors of pge nps providing a complementary or even an alternative mechanism for the fractionation of pges in high temperature silicate melts furthermore hydrothermal alteration of the chromite deposits during seafloor metamorphism or exhumation i e retrograde metamorphism of upper mantle rocks has also a significant effect on the internal structure of the oxides and sulfides that host the pge nps frequently pge nps are found along the replacement contacts between primary and secondary minerals suggesting that pge nps can also form during low temperature alteration events 200 600 c finally heating events overimposed on chromite deposits previously affected by hydrous metamorphism may enhance fluid infiltration subsequently triggering chemical mineralogical or textural responses in the oxide or sulfide matrices hosting the pge nps promoting coarsening of metal nanoparticles the interplay between these processes can explain the wide spectrum of particle sizes of pge inclusions that are observed in many altered chromite deposits which can vary from a few nanometers to larger than a micron these studies provide evidence that pge nps can eventually form under a wide spectrum of thermal and pressure conditions and show that aqueous fluids may play a relevant role in producing pge nps during metamorphism and metasomatism of mantle hosted chromite deposits

geochemistry hydrology and mineralogy of the sand bulge area laguna madre flats south texas abstract the sand bulge area of the laguna madre flats is a silicoclastic coastal sabkha lying between padre island and the intracoastal waterway on the gulf coast of southwest texas the sabkha is sporadically inundated by wind tidal flooding of water from an adjacent lagoon laguna madre saline interstitial brines are formed by infiltration of partially evaporated ponded flood water manometric data indicate that the brine seeps downward through the sabkha and laterally west toward the intracoastal waterway icww some of the brine may flow seaward east through incised pleistocene stream valleys most of the sabkha in this area is covered with blue green algal mat precipitation of microcrystalline mg calcite algal micrite in brine ponds or within the algal mat induced by algal or bacterial action removes much of the calcium from recharge water before it reaches the sabkha watertable thus though brine salinities reach 240 per mil low calcium concentrations prevent the precipitation of gypsum and thermodynamic calculations indicate that the brines are undersaturated with respect to gypsum gypsum does not presently occur in the sabkha sediments in this area contrary to earlier observations fisk 1959 it is suggested that emplacement of the icww altered the rate and direction of water flow through the sabkha leading to less saline brines and possibly to the dissolution of previously formed gypsum

ore genesis of the late cretaceous larong porphyry w mo deposit eastern tibet evidence from in situ trace elemental and s pb isotopic compositions abstract the late cretaceous ca 92 ma larong porphyry w mo deposit 39 44 mt wo3 0 1541 a newly discovered deposit in the easternmost bangong nujiang metallogenic belt bnmb is located in eastern tibet the w mo mineralization occurs as veins and stock works hosted in monzogranite porphyry granodiorite porphyry and surrounding quartz schist and can be divided into two main paragenetic stages the w mineralization stage stage i consists of various k feldspar quartz scheelite veins and the quartz sulfide stage stage ii is dominated by molybdenite and pyrite of which the latter can be further subdivided into three sub stages here we present la icpms in situ trace elements and s pb isotopes of sulfides from the larong deposit in order to constrain the sources of ore forming elements and the processes of mineralization our study shows that pyrite is rich in co and as molybdenite is rich in w pb and bi and chalcopyrite has high sn contents these results are consistent with the mineralization characteristics of the larong deposit where the main metallogenic elements are w and mo accompanied by bi sn and cu overall sulfides from the larong deposit have calculated 34svcdt values ranging from 0 25 to 6 37 suggesting a predominantly magmatic origin for sulfur from stage ii 1 to stage ii 2 to stage ii 3 the average 34svcdt values of pyrite change from 0 33 to 1 88 to 5 34 showing a progressive and gradual change in redox and temperature conditions molybdenite has high pb isotopic ratios 208pb 204pb 39 356 39 908 207pb 204pb 15 747 15 928 206pb 204pb 18 843 20 120 but low re contents and pyrite has low ni contents implying that the ore forming materials were mainly derived from the crust we propose that the w mo mineralization is genetically related to the late cretaceous monzogranite porphyry with the mineralization of w and mo occurring as a result of decreases in temperature and oxygen fugacity of the ore forming fluid exsolved from the magma in combination with previous studies our study led to the identification of three w dominated polymetallic metallogenic events and mineralization potential of igneous rocks in the bnmb

the use of x ray tomography in the study of water repellents and consolidants abstract to reduce the weathering rate of natural building stones a wide variety of water repellents and consolidants are commercially available although a lot of research is performed on these products it remains difficult to determine which product is appropriate to use for a certain type of building stone each type of building stone has its own petrographic characteristics mineralogy texture leading to typical physical and technical properties which influence its rate of decay the localisation of the products inside a stone type is not only depending on the properties of the products themselves but also linked to the texture and structure of the stone the impregnation depth of the products strongly influences their efficiency and is therefore a key issue in the determination if a product is functional for a certain type of stone x ray micro ct has recently been introduced as a non destructive material evaluation technique for engineering and geology purposes the fact that micro ct can provide information about the internal structure and properties of natural building stones is a major advantage in the study of their conservation firmly linked with more classical research techniques this non destructive technique offers an extra dimension to the cultural heritage research in this paper non destructive x ray computed micro tomography micro ct turns out to be a powerful tool as it can visualise the presence of water repellents and consolidants inside the stone and can help to detect the influence that these treatments exert on porosity and pore size distribution for the visualization of the product its atomic number and density and the amount of product inside the natural building stone is crucial besides the contrast in attenuation the resolution of the micro ct also needs to be taken into account to obtain a good contrast between stone and product by doping with 3 bromopropyltrimethoxysilane more contrast occurs between the stone material and the conservation product when the amount of product inside the samples is very low and the product is homogeneously spread inside the sample the doped product is difficult to distinguish from the stone material due to the resolution of the micro ct when the amount of doped product inside the stone material reaches a certain threshold value the dope will appear in the 2d cross sections derived from micro ct creating a good visualization of the products inside the stone samples

nano mineralogy and geochemistry of high grade diasporic karst type bauxite from parnassos ghiona mines greece abstract in the present work a combination of various techniques is utilized for the study of nano mineralogy and geochemistry of high grade karst type bauxite al rich and fe depleted samples al2o3 ca 80 wt from the parnassos ghiona mines located in greece initial characterization using pxrd and electron microscopy in microscale and mesoscale sem eds including stem mode proved the presence of fe cr ti containing diaspore anatase and minor rutile the study by means of 57fe mossbauer spectroscopy in correlation with magnetic susceptibility measurements and complemented with synchrotron based spectroscopies at the microscale sr micro xrf and micro xanes exafs indicated that fe3 in contrast to 6 cr3 is not exclusively a component of the diaspore structure while cr3 substitutes al3 in octahedral sites of diaspore 6 cr3 6 al3 the electron microscopy in nanoscale tem eds eels revealed that fe exists in the form of peculiar fe3 bearing nanominerals most likely maghemite type phases between 25 and 45 nm in size in addition to the fe3 ions substituting al3 in the diaspore structure moreover it was proven that tio2 polymorph mineral nanoparticles particularly rounded anatase mesocrystals and nanocrystals and individual needle shaped rutiles are dispersed into the diaspore matrix thus diaspore in the studied bauxite concerns in fact a distinct fe3 cr3 alooh low t authigenic phase demonstrated for the first time in literature on the other hand the observed tio2 mineral nanoparticles formed together with diaspore during diagenesis and fe nanominerals formed during epigenesis were hitherto unknown not only for the allochthonous karst type bauxite deposits of greece but also for the overall bauxite deposits worldwide

petrogenesis of bismuth minerals in the dabaoshan pb zn polymetallic massive sulfide deposit northern guangdong province china abstract located in the northern guangdong province the dabaoshan pb zn polymetallic massive sulfide deposit is one of the most important regions to have produced fe cu pb zn and s in southern china while much progress has been made with respect to the geology and geochemistry of the deposit a better understanding of ore genesis is warranted this ore body contains abundant bismuth element only few studies exist on the distribution characteristics and existing states of bismuth electron microprobe study yields that native bismuth tellurides e g hedleyite and sulfide minerals are the main forms in which this element is found the occurrence and characteristics of native bismuth and its mineral assemblages are different with high t gold bearing deposits but are more similar to those of mid low temperature hydrothermal deposits our research shows that the bi te at dabaoshan derived from the late yanshanian dacite porphyry the bi te rich ore forming fluid developed during intrusion of the dacite and mineralized along fractures and overprint the earlier pb zn mineralization during the early overprinting event the ore forming fluid was rich in bi and te and poor in s under uniform mid temperature conditions as the hydrothermal fluids evolved they became enriched with ag and pb sulfur was rich in the fluid during the late overprinting event this may have been related to dissolution of sulfide the low abundances of bi te and ag in sulfide minerals e g galena and sphalerite indicate that ore genesis and the ore forming materials were different between the pb zn and bi te ag stages thus new geological and geochemical data were used to delineate the sequence ore genesis of dabaoshan pb zn mineralization

a hydrothermal origin for the large xinqiao cu s fe deposit eastern china evidence from sulfide geochemistry and sulfur isotopes abstract the xinqiao cu s fe deposit in the tongling ore district middle lower yangtze river valley metallogenic belt mlyb eastern china is located along the northern margin of the yangtze craton the stratiform and skarn type xinqiao mineralization comprises five stages namely the early skarn stage i garnet and diopside late skarn stage ii epidote dominated iron oxides stage iii hematite and magnetite colloform pyrite stage iv and quartz sulfides stage v there are three pyrite types at xinqiao i e colloform py1 stage iv fine grained py2 from py1 recrystallization stage v and coarse grained py3 stage v pyrites scanning electron microscope sem imagery for py1 reveals that they are cubic microcrystalline pyrite aggregates and the eds and xrd data indicate that some py1 contain minor siderite impurities electron microprobe analysis empa and la icp ms geochemical data demonstrate that the three pyrite types have relatively high fe s ratios and distinctly high mn cu and as concentrations compared to py2 and py3 py1 has higher pb bi and ag but lower co ni se cd te and au ratios of fe s 0 837 to 0 906 se te 2 39 to 14 50 and co ni 0 67 to 4 67 of the xinqiao pyrites resemble typical hydrothermal pyrites 34 s cdt of py1 0 6 to 2 7 average 0 58 py2 1 8 to 2 5 average 2 1 and py3 1 9 to 4 4 average 3 5 are close to those of the xinqiao skarn type orebodies 1 3 to 4 1 but distinct from those of the upper carboniferous huanglong formation limestone 9 5 to 15 4 suggesting that the three pyrite types especially py1 were genetically linked to the yanshanian jurassic cretaceous magmatic hydrothermal events with py1 probably reflecting rapid crystallization during fluid mixing we interpret that the xinqiao stratiform mineralization may have been associated with the jitou quartz diorite stock as may be the case also for the skarn type mineralization hosted in the contact between the yanshanian jitou stock and the lower permian qixia formation limestone overall the xinqiao cu s fe mineralization may have been generated by the jurassic cretaceous tectono thermal event in eastern china

pyrite textures and trace element compositions from the granodiorite hosted gold deposit at jonnagiri eastern dharwar craton india implications for gold mineralization processes

trace element substitution and grain scale compositional heterogeneity in enargite abstract enargite cu3ass4 is a relatively common sulphide mineral and is considered diagnostic for deposits of intermediate to high sulphidation type analysis of enargite bearing samples from deposits in the zijinshan porphyry high sulphidation epithermal cu au orefield southeastern china provides evidence for the diversity of trace elements that may be hosted within enargite and their range of concentrations enargite is shown to host sb te sn zn and ge at concentrations up to several thousand ppm the mineral also incorporates measurable concentrations of mo cd bi pb fe se ag au w ga and in element mapping electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry provides evidence for grain scale heterogeneity in enargite in the form of oscillatory grain scale compositional zonation with respect to sb sn te and several other trace elements element mapping also clearly shows an inverse correlation between the concentrations of as and te and between as and sn incorporation of sn and te into the enargite structure is achieved by substitution of sn4 and te4 for as5 charge balance is maintained by incorporation of fe2 zn2 and other divalent cations potentially including cu2 into the cu site the complex intra grain zoning results from evolving fluids multiple phases of growth in turn leading to an overprinting of primary distribution patterns observed patterns are also influenced by equilibrium partitioning between enargite and co existing minerals nevertheless trace element signatures in enargite from different parts of the zijinshan ore system show notable differences enargite from the high sulphidation stage typically shows a marked enrichment in te and sn whereas enargite from intermediate sulphidation stage is relatively depleted in te and sn and comparatively enriched in sb and se these differences represent a potential vector for exploration within porphyry high sulphidation epithermal systems furthermore the presence of te rich enargite may be a prospective guide to high au grade mineralization the notable concentrations of precious metals au ag and critical elements notably te and ge within enargite make this mineral of particular interest from the perspective of potential recovery of these economically important elements the observed grain scale zoning and inherent variability within any given sample emphasize that spot analysis of trace elements alone without consideration of such heterogeneity may provide quantitative data of limited use and potentially lead to misleading interpretations

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

molybdenite re os dating and la icp ms trace element study of sulfide minerals from the zijinshan high sulfidation epithermal cu au deposit fujian province china abstract the zijinshan cu au deposit located in fujian province is the largest high sulfidation epithermal hse deposit in southeastern china and is usually regarded as a major part of the porphyry cu system in the zijinshan ore field molybdenite samples collected from the cu mineralization zone yield a first weighted mean re os age of 111 31 0 70 ma which is explained as the time of dickite alunite alteration combining the newly reported muscovite 40ar 39ar and zircon u pb ages 113 ma the mineralization of zijinshan is likely to initiate before ca 110 ma this result is obviously older than the re os age of the adjacent luoboling porphyry cu mo deposit 105 ma pyrite chalcopyrite bornite digenite and covellite collected from the deep potassic middle phyllic and upper epithermal zones are used to conduct la icp ms trace element analysis the spatial zonings of mineralization and alteration and the regular variations of trace elements in sulfides at vertical direction imply a potentially complete transition from porphyry to epithermal mineralization and the deep origin of ore forming fluids mineralogical and trace element characteristics indicate that the chalcopyrite formed in both stages whereas bornite is the product of epithermal mineralization rather than a porphyry stage residue the majority of digenite and covellite has hypogene genesis pyrite and digenite in the epithermal zone are major carriers of primary au au in pyrite is te bi related and exists as solid solutions or different sized telluride and bi sulfosalt inclusions compared to as te and bi played more important roles to scavenge au and ag and achieve the primary au enrichment differently au in digenite is independently locked in digenite lattice bornite and digenite are good carriers of primary ag which mainly exists as solid solutions the high sulfidation state stage is the major period for concentrations of primary au and ag the upward increase of au in primary sulfides of hse cu zone implies that the distribution pattern of upper au enrichment and lower cu enrichment is not only caused by supergene process but is also controlled by hypogene trend based on the mineralization and alteration zonings the spatial variation of trace elements and the presented re os age the ore forming fluids of the zijinshan cu au deposit most likely originate from deep region rather than from the adjacent luoboling porphyry deposit the zijinshan and the luoboling deposits should belong to two independent hydrothermal systems

trace element concentrations in porphyry copper deposits from metaliferi mountains romania a reconnaissance study there are fifteen miocene intrusions with porphyry copper mineralization in the metaliferi mountains romania most are associated with epithermal au ag te bi se ge vein systems the investigation of fifty samples from six deposits rosia poieni bucium tarni a colnic rovina valea morii and bolcana indicated bulk rock mean values of 0 16 0 88 ppm au 1000 ppm in bornite in the porphyry type mineralization galena forms microinclusions in pyrite chalcopyrite and bornite and contains up to 3750 ppm ag 17 380 ppm se 1570 ppm ge and 780 ppm te galena and pyrite from the epithermal mineralization in the m gura bolcana troi a system contain concentrations of ag and se ten times lower than in the same minerals from the porphyry copper mineralization the present data show that te is a significant trace element in the potassic zone of the investigated porphyry systems the data also shows that this does not correlate with the presence or absence of ophiolitic basement or with variation in the chemistry of the host intrusions tellurium enrichment in porphyry type deposits of the metaliferi mountains supports their genetic relationship with the spatially associated epithermal systems

measurement of capillary pressure curve of dnapl in a water saturated sandstone fracture this paper describes a methodology for the measurement of the capillary pressure curve of dense nonaqueous phase liquids dnapls in a water saturated sandstone induced fracture details of specimen preparation capillary barrier design and capillary pressure measurement setup procedure and results are given the aperture distribution of the induced fracture was estimated using the x ray com puted tomography ct technique the primary drainage or invasion of dnapls in the water saturated induced fracture was simulated using the invasion percolation ip approach it was found that the invasion process was highly dependent on the spatial distribution of the fracture apertures the ip model matched the experimentally measured entry pressure very well but deviated from the measured capillary pressure curve at the midrange and high nonwetting phase saturations the ip model tended to yield an l shaped function with a fairly flat portion at the midrange saturation and a sharp rise at the high end the measured capillary pressure curve was observed to follow the well known brooks corey porous media function these discrepancies between the measured and predicted results could be attributed to the fact that the ip model did not consider the effects of fracture surface roughness and undulation for a fracture with small apertures these two factors could make the fracture behave more as a porous medium than a parallel plate channel doi 10 1061 asce gt 1943 5606 0000590 2012 american society of civil engineers

measurement of aperture distribution capillary pressure relative permeability and in situ saturation in a rock fracture using computed tomography scanning we develop an experimental technique that uses computed tomography ct scanning to provide high resolution measurements of aperture distribution and in situ saturation along with capillary pressure and relative permeability for the same rough walled fracture we apply this technique to an induced fracture in a cylindrical basalt core undergoing water drainage we find that the sum of the water and gas relative permeabilities is much 1 at intermediate saturations and the water relative permeability shows a sharp change over a narrow range of average water saturation in situ saturation maps show channeling of gas and significant retention of the wetting phase water the capillary pressure initially increased and then decreased with decreasing water saturation although this type of capillary behavior is atypical for unsaturated flows we find that the sizes of the gas filled apertures are consistent with the measured capillary pressure

textures and trace element signatures of pyrite and arsenopyrite from the gutaishan au sb deposit south china the gutaishan deposit is a slate hosted lode au sb deposit in the xiangzhong sb au metallogenic province south china the deposit has a proven reserve of ca 9 t gold at an average grade of 13 g t and contains 2500 t sb the deposit represents the product of a complex ore forming process comprising four different stages of which the third stage is the main gold stibnite bearing stage scanning electron microscopy electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry were used to investigate the occurrence of visible gold and the distribution of invisible gold in pyrite and arsenopyrite visible gold displays textural complexity with four distinct categories defined and assumed to have formed directly precipitated from ore forming fluid and remobilized from pyrite and arsenopyrite pyrite and arsenopyrite occur as ten and four texturally distinct subtypes all host invisible gold which is lattice bound trace element mapping of selected pyrite and arsenopyrite grains reveals a marked compositional zoning with respect to au and other elements in both minerals observed decoupled behavior between au and as in some grains contradicts the paradigm of coupled au and as substitution evidence suggests that the gutaishan deposit likely represents an evolving au sb mineralization event recorded by the complex texture and geochemical signatures of visible gold sulfides and sulfosalts

numerical simulations examining the relationship between wall roughness and fluid flow in rock fractures understanding how fracture wall roughness affects fluid flow is important when modeling many subsurface transport problems computed tomography scanning provides a unique view of rock fractures allowing the measurement of fracture wall roughness without destroying the initial rock sample for this computational fluid dynamics study we used several different methods to obtain three dimensional meshes of a computed tomography scanned fracture in berea sandstone these volumetric meshes had different wall roughnesses which we characterized using the joint roughness coefficient and the fractal dimension of the fracture profiles we then related these macroscopic roughness parameters to the effective flow through the fractures as determined from navier stokes numerical models thus we used our fracture meshes to develop relationships between the observed roughness properties of the fracture geometries and flow parameters that are of importance for modeling flow through fractures in field scale models fractures with high joint roughness coefficients and fractal dimensions were shown to exhibit tortuous flow paths be poorly characterized by the mean geometric aperture and have a fracture transmissivity 35 times smaller than the smoother modeled fracture flows

invisible gold distribution on pyrite and ore forming fluid process of the huangshan orogenic type gold deposit of zhejiang se china implications from mineralogy trace elements impurity and fluid inclusion studies the huangshan orogenic type gold deposit in zhejiang of se china occurred in quartz pyrite veins it is hosted by phyllonite that underwent greenschist facies metamorphism along a large jiangshan shaoxing tectonic belt with a ne sw direction trace elemental characteristics ore forming process and invisible gold on different forms of pyrite and quartz are studied the au associated pyrite can be classified into two categories recrystallized pyrite and euhedral pyrite the precipitation of invisible au on pyrite is mainly derived by co and ni with auhs2 complex in the mineralizing fluids in different events the xps results revealed that valence states of au3 replaced 2fe2 in the pyrite and au0 replaced si4 in the quartz structure the electron paramagnetic resonance and trace elemental results suggested that the element pairs of ge li al in quartz and mn co ni in pyrite have distinct impurities as identified a fluid inclusion study showed that the auriferous quartz is characterized by low saline and co2 rich fluids coexistence of the type i type iii inclusions and same range of homogenization temperature with different mode are evidences of immiscible fluid process the temperature pressure values of ca 250 c 1250 bar and ca 220 c 780 bar for gold precipitation have been calculated by intersection of coexisting fluids during the entrapment the huangshan orogenic type gold deposit may be associated with the wuyi yunkai orogeny during the early paleozoic including an upper mid greenschist facies metamorphism 450 420 ma all the features suggest that the huangshan gold deposit is probably a product linking with the early paleozoic orogeny in south china

arsenopyrite pyrite association in an orogenic gold ore tracing mineralization history from textures and trace elements laser ablation inductively coupled plasma mass spectrometry la icp ms spot analysis and element mapping coupled with high resolution focused ion beam scanning electron microscopy fib sem imaging has been performed on au hosting sulfides from a proterozoic orogenic gold deposit tanami gold province north central australia gold distribution patterns in the arsenopyrite pyrite assemblage which probably crystallized toward the end of the au forming event suggest a process of initial scavenging of au into arsenopyrite and subsequent remobilization of that au following brittle fracture gold expelled from the sulfide lattice during the remobilization event is reconcentrated around the margins of the same arsenopyrite grains and within swarms of crosscutting microfractures the distribution of pb bi and ag closely mimic au indicating that these elements were also reconcentrated preservation of oscillatory zonation patterns for co ni sb se and te in arsenopyrite imply however that no significant degree of sulfide recrystallization took place residual concentrations of invisible gold in grain centers are 5 ppm in arsenopyrite and 1 ppm in coexisting pyrite the presence of submicron sized pores is suggestive of a fluid driven process rather than solid state diffusion micron scale 2 10 m remobilized gold is accompanied by fine particles 200 nm 2 m and nanoparticles 200 nm of gold the extensive variation of au concentrations within single arsenopyrite grains underlines the significance of textures when using trace element data to understand how gold ores evolved

geochronology and geochemistry of the dianfang gold deposit western henan province central china implications for mineral exploration abstract the dianfang gold deposit located in the xiong ershan waifangshan region within the southern margin of the north china craton consists of eastern and western ore blocks which are hosted in the dianfang breccia pipe and paleoproterozoic volcanic rocks respectively the eastern ore block which occurs within the southern and hanging wall margins of the dianfang breccia pipe and in fractures in the rhyolites of the jidanping formation consists of rhyolite hosted and breccia hosted disseminated gold mineralization structurally controlled by ene striking faults the western ore block contains gold bearing quartz sulfide veins and minor disseminated rhyolite hosted gold mineralization that occurs in the annular fractures around the hougou breccia pipe the two ore blocks have long been researched and prospected as two different genetic types detailed fieldwork and microscopic observations reveal that the eastern and western ore blocks contain the same hydrothermal alteration and mineral assemblages which include k feldspar quartz sericite chlorite epidote carbonate pyrite galena sphalerite marcasite and chalcopyrite as well as minor magnetite anatase cervelleite matildite and bismuthinite gold occurs as electrum inclusions in pyrite or along microfractures in sulfides and quartz zircon u pb geochronology of the granite porphyry around the hougou breccia pipe constrains the timing of breccia pipe formation to 145 9 ma which is consistent with the formation age of the dianfang breccia pipe 145 8 ma indicating that the two breccia pipes formed coevally at the end of the late jurassic rather than during the paleoproterozoic as was suggested by previous studies the hydrothermal sulfides from the main orebody yield a rb sr isochron age of 119 5 1 8 ma suggesting that the eastern and western ore blocks formed coevally at the end of the early cretaceous in situ mineral trace element data as well as sulfur and lead isotope data suggest that the eastern and western ore blocks were formed by a common ore forming fluid that evolved from a magmatic hydrothermal system that was genetically related to a hidden late mesozoic granite pre existing fractures and breccia then served as ideal conduits for fluid flow accumulation and gold deposition consequently we propose that the ene striking faults developed in and around the breccia pipes and the annular brittle faults around the breccia pipes are good targets for future gold exploration at the dianfang gold deposit based on these results and data from other gold deposits of similar ages around the margins of the north china craton we argue that the gold deposits in xiong ershan region formed under conditions of lithospheric extension from the late jurassic to the early cretaceous which resulted from lithospheric thinning due to the westward subduction of the pacific plate

gold telluride nanoparticles revealed in arsenic free pyrite pyrite the most abundant sulfide on earth and a common component of gold deposits can be a significant host for refractory gold this is the first documentation of pore attached composite au telluride nanoparticles in arsenic free pyrite trace elements mapping in pyrite from an intrusion hosted au deposit with orogenic overprint dongping china shows trails of tellurides overlapping co ni zonation intragranular microfracturing anomalous anisotropy and high porosity are all features consistent with devolatilization attributable to the orogenic event the pyrite hosted nanoparticles are likely the frozen solid expression of te rich au ag pb bearing vapors discharged at this stage nanoparticle formation as presented here provides the smallest scale tool to fingerprint au trapping during crustal metamorphism

focussed ion beam transmission electron microscopy applications in ore mineralogy bridging micro and nanoscale observations abstract focussed ion beam scanning electron microscopy fib sem is a relatively new analytical tool that has been little applied to problems of ore genesis the technique enables high resolution cross section imaging and can be used to prepare thinned foils for study by transmission electron microscopy tem fib sem methods applied to sulphides and related compounds represent an in situ approach for sample characterisation and thus provides for crystal chemical data that can be placed into the geological context of a given ore deposit we present four study cases these deal with minor element incorporation and release in zns intergrowths and replacement among cu fe sulphides fabrics in au bearing as free pyrite and symplectites of bi sulphosalts within galena the data is discussed in the context of polytypism and planar defects for minor element incorporation and release superstructure ordering and formation of fine particles 100 2500 nm or nanoparticles

single fractures under normal stress the relation between fracture specific stiffness and fluid flow abstract fracture specific stiffness and fluid flow through a single fracture under normal stress are implicitly related through the geometry of the void space and contact area that comprise the fracture data from thirteen different rock samples each containing a single fracture show that relationships between fracture specific stiffness and fluid flow through a fracture fall into two general classes of behavior fractures either fall on a loosely defined universal curve relating fluid flow to fracture specific stiffness or else the flow is weakly dependent on fracture specific stiffness the second relationship shows that flow decreases slowly with increasing fracture specific stiffness the first relationship shows that flow decreases rapidly for increases in fracture specific stiffness to understand this behavior computer simulations on simulated single fractures were performed to calculate fluid flow fracture displacement and fracture specific stiffness as a function of normal stress simulated fractures with spatially correlated and uncorrelated aperture distributions were studied fractures with spatially uncorrelated aperture distributions tend to exhibit a weak dependence of fluid flow on fracture specific stiffness because these fractures tend to have multiple connected paths across the sample which can support flow with uniformly distributed contact area thus an increment in stress will increase the stiffness of the fracture without greatly reducing the amount of fluid flow on the other hand fractures with spatially correlated aperture distributions tend to belong to the universal relationship because correlated fractures tend to have only one or two dominant flow paths and the contact area is limited to a few regions resulting in a compliant fracture thus an increment in stress on a spatially correlated fracture will result in an increase in stiffness and rapid decrease in fluid flow these spatial correlations in fracture void geometry can be differentiated in the laboratory based on the observed fracture specific stiffness fluid flow relationship for a single fracture under normal loading

evidence of upgrading of gold tenor in an orogenic quartz carbonate vein system by late magmatic hydrothermal fluids at the madrid deposit hope bay greenstone belt nunavut canada abstract evidence of secondary gold enrichment due to the addition of new gold into an earlier orogenic quartz carbonate vein deposit by magmatic hydrothermal fluids is strongly suggested for the madrid deposit hosted in the hope bay greenstone belt in nunavut canada the conclusion is based on an extensive in situ microanalytical protocol sem confocal raman microspectroscopy microthermometry decrepitate mound analysis la icp ms cathodoluminescence sims not previously applied to gold systems this approach was used to characterize the mineralogy and fluid inclusion systematics associated with the upgrading event mineralization comprised of only ag bearing gold electrum 89 8 at au avg n 8 is present throughout all investigated laminated and brecciated orogenic quartz veins however in high grade vein intersections where gold grades are locally elevated up to 122 g t assemblages containing tennantite tetrahedrite chalcopyrite electrum 80 7 at au avg n 15 ag pb au tellurides occur that are texturally late stage relative to electrum only mineralization subdomains of quartz coeval with this later assemblage are optically and texturally distinct from earlier orogenic quartz this late mineral assemblage is absent in all low grade vein intersections 1 g t au avg examined where only electrum is identified quartz hosted fluid inclusions h2o nacl co2 of intermediate salinity 16 7 1 2 wt nacl equiv n 93 were identified only in the high grade vein samples and are present along healed planes associated with tennantite tetrahedrite chalcopyrite electrum ag pb au telluride assemblages in situ sims 18o analyses of quartz combined with temperature constraints from mineral equilibria show that early orogenic vein quartz and late quartz subdomains associated with gold upgrading precipitated from fluids with similar 18oh2o values of 4 5 12 4 n 10 and 5 5 to 11 8 n 13 respectively isotopic data suggests that meteoric water was a negligible component in fluids responsible for gold precipitation microthermometry and raman spectroscopy show that upgrading fluids were distinct in composition compared to the earlier metamorphic fluids h2o nacl co2 ch4 n2 4 6 1 6 wt nacl equiv n 33 and later canadian shield basement brines h2o nacl 22 4 1 2 wt nacl equiv n 12 which have also been identified in the fluid inclusion record at madrid laser ablation icp ms analyses indicate the gold upgrading fluids are enriched in as sb zn pb and lile cs ba rb sr these data are consistent with late fluids derived from an evolved magmatic hydrothermal system trace element mapping of pyrite coupled with principle component analysis of the data confirms a strong correlation between au and ag te sb bi w as in upgraded veins whereas only au and as strongly correlate in low grade veins the study suggests that gold upgrading either involving newly introduced gold or remobilization of existing gold can be linked to the incursion of a late magmatic hydrothermal fluid that post dated formation of the main orogenic type auriferous quartz vein system the geological setting and mineral chemical features suggest an intrusion related i e porphyry or intermediate sulfidation epithermal mineralization style for the later event this work provides another example of the importance of compositionally distinct cumulative hydrothermal events in the development of high grade gold deposits in orogenic settings

a 2d and 3d nanostructural study of naturally deformed pyrite assessing the links between trace element mobility and defect structures the links between deformation induced micro and nanostructures and trace element mobility in sulphide minerals have recently become a popular subject of research in the earth sciences due to its connections with metallic ore paragenesis it has been shown that plastic deformation in pyrite creates diffusion pathways in the form of low angle grain boundaries that act as traps for base and precious metals however the plastic behavior of pyrite and the physiochemical processes that concentrate these trace elements in deformation induced micro and nanostructures remain poorly understood in this study we develop strategies for 2d and 3d analysis of naturally deformed sulphides by combining electron backscatter diffraction electron channeling contrast imaging and atom probe tomography on pyrite in an attempt to better understand the underlying diffusion processes that mobilize trace elements the combined results reveal structures associated with crystal plastic deformation in the form of dislocations stacking faults and low angle grain boundaries that are decorated by as and co although our data support a dislocation impurity pair diffusion model we have evidence that multiple diffusion mechanisms may have acted simultaneously in this study we applied new data processing techniques that allow for orientation measurement of nanostructural crystal defects from atom probe tomography data dislocations within our studied sample occur along the 110 planes suggesting glide on 110

major and trace element and multiple sulfur isotope composition of sulfides from the paleoproterozoic surda copper deposit singhbhum shear zone india implications for the mineralization processes abstract the present study combines major and trace element composition and sulfur s isotope data of pyrite and chalcopyrite from the surda copper sulfide deposit in the singhbhum shear zone the most important copper and uranium producing belt singhbhum cu u belt in india three textural and compositional types of both pyrite and chalcopyrite were distinguished unzoned to partially zoned pyrite ia with high co up to 54900 ppm and low ni content is earliest followed by oscillatory zoned pyrite ib with high as up to 25600 ppm and co up to 46800 ppm both occurring in pyrite i chalcopyrite i pyrrhotite magnetite apatite vein cobaltite type substitution fe1 xcox s1 xasx 2 is suggested for pyrite ib gold occurs in pyrite i as minor invisible gold and as electrum inclusions it also occurs along with cu mn ni hg ag pb sb zn ce y u and th in micro fractures that transgress the primary zoning pattern defined by as co and ni in pyrite ib the early inclusion rich chalcopyrite generation chalcopyrite i contains high concentration of zn and se and minor to trace amounts of co ni hg pb sb te and bi appeared in between pyrite i and ii low co high ni up to 37700 ppm content pyrite ii and inclusion free chalcopyrite ii enriched in co ni hg bi mn ag sb v and pb are cogenetic and occurring in pyrite ii pyrrhotite pentlandite chalcopyrite ii violarite vein low co and ni containing pyrite iii chalcopyrite iii occur mainly as disseminated grains the relative timing of formation of pyrite ii chalcopyrite ii with pyrite iii chalcopyrite iii remains uncertain pyrite chalcopyrite textures indicate that all pyrite chalcopyrite formed at some time prior to the end of deformation and metamorphism both in situ and mineral separates of all pyrite types and associated chalcopyrite yield a narrow range of positive 34s values between 3 8 and 6 9 suggesting sulfur being derived from a similar source consistent positive 34s values and other circumstantial evidence indicate that most sulfur was derived from seawater sulfate or modified seawater brine evaporite 33s values revealed mass dependent fractionation mdf signature it is proposed that incorporation of mdf sulfur of the mineralization event in paleoproterozoic singhbhum cu u belt took place after the great oxidation event the high se concentrations 260 400 ppm and se s ratios for both pyrite i and ii from surda deposit 4 4 5 7 10 4 suggest a low temperature of the cu rich ores 250 350 c and precipitation from a metalliferous fluid with a high se s ratio 10 4 to 10 3 consistent with igneous input of these elements

metallogeny of the syenite related dongping gold deposit in the northern part of the north china craton a review and synthesis abstract the dongping gold deposit is located at the northern margin of the north china craton in hebei province china it is the largest alkaline pluton related au deposit in china the ore deposit is hosted in the 400 386 ma la icpms and shrimp zircon u pb method shuiquangou syenite intrusion which cuts archean aged metamorphic rocks the ore bodies consist of a set of en echelon lenses and veins controlled by shear zones the ores can be divided into auriferous quartz vein stockwork and disseminated ores two stages of gold mineralization can be distinguished the first stage mineralization consists of high grade 10 g t grayish quartz veins enveloped by stockwork and disseminated ores whereas the second stage mineralization occurs as low grade studies of fluid inclusions in quartz indicate that the ore forming fluids have low salinity 0 7 8 1 nacl equivalent in the h2o co2 nacl system and have homogenization temperatures varying from 310 to 350 c the ore forming fluids have 18o values varying from 1 7 to 6 9 with an average of 2 9 and d values from 108 to 66 5 with an average of 85 indicating a magmatic origin with some involvement of meteoric fluid the ore forming fluids have initial 87sr 86sr385ma ratios of 0 705 0 706 and 3he 4he ratios of 0 3 to 5 2 ra ra being the atmospheric ratio of 1 0 indicative of a mantle contribution of the fluids the ores have bulk 34s values varying from 1 to 2 similar to those of the host syenites 34s 1 8 3 and the archean metamorphic rocks 34s 0 04 to 4 4 lead isotope analyses of sulfides stock and disseminated ores quartz veins fresh host syenites and the archean metamorphic rocks have a linear correlation of 208pb 206pb and 207pb 206pb indicating a genetic link between the gold mineralization and the syenites hydrothermal zircons from the high grade ores of the first stage can be distinguished from magmatic zircons based on internal textures on cathodoluminescence images and rare earth element patterns these zircons have been dated at 389 1 0 to 385 5 7 ma whereas those from the second stage low grade auriferous quartz vein were dated at 140 ma la icpms and sim u pb methods we propose a model for the formation of the dongping gold deposit involving a late magmatic hydrothermal process related to a devonian mantle sourced syenites with a late jurassic early cretaceous hydrothermal overprint

fluid inclusion and noble gas studies of the dongping gold deposit hebei province china a mantle connection for mineralization the dongping gold deposit 100 t au occurs about 200 km inboard of the northern margin of the north china craton the deposit is mainly hosted by syenite of a middle paleozoic alkalic intrusive complex that was emplaced into late archean basement rocks both groups of rocks are intruded by late jurassic to early cretaceous crustal melt granite dikes and stocks some within a few kilometers of the deposit the gold ores were deposited during this latter magmatic period at about 150 ma a time that was characterized by widespread regional north south compression that formed the east west trending yanshan deformational belt the ores include both the telluride mineral bearing low sulfide quartz veins and the highly k feldspar altered syenite with most of the resource concentrated in two orebodies 1 and 70 fluid inclusion microthermometry indicates heterogeneous trapping of low salinity e g 5 7 wt nacl equiv fluids that varied from a few to 60 mole percent nonaqueous volatile species laser raman spectroscopy confirms that the vapor phase in these inclusions is dominated by co2 but may be comprised of as much as 9 mole percent h2s and 20 mole percent n2 methane concentrations in the vapor phase are consistently 1 mole percent the variable phase ratios are consistent with fluid immiscibility during ore formation fluid inclusion trapping conditions are estimated to be 250 to 375 c and 0 6 to 1 0 kbar helium isotope studies of fluid inclusions in ore stage pyrites indicate 3he 4he ratios of 2 1 to 5 2 ra ra 1 4 10 6 for air for orebody 1 and 0 3 to 0 8 ra for orebody 70 the former data suggest that at least 26 to 65 percent mantle helium occurs in the fluids that deposited the veins in orebody 1 the lower values for orebody 70 which is characterized by a more disseminated style of gold mineralization are interpreted to reflect an increased interaction of ore fluids with surrounding crustal rocks which may have contributed additional 4he to the fluids a mantle source for at least some of the components of the gold forming fluid is consistent with upwelling of hot asthenosphere and erosion of as much as 100 to 150 km of cool archean lithosphere beneath the craton during this time the dongping deposit is located along the 100 km wide north south gravity lineament which marks the western border of the thinned crust as both regional metamorphism of mesoproterozoic and younger cover rocks and widespread granite magmatism also occurred at ca 150 ma it is unclear as to whether one or both of these also contributed fluid and or metals to the hydrothermal system importantly these new data suggest that economically significant gold deposits of similar mineral style and fluid composition which are scattered along the margins of the craton may all be products of a fluid originally partly sourced within the mantle

multi stage growth and invisible gold distribution in pyrite from the kundarkocha sediment hosted gold deposit eastern india abstract gold mineralization at kundarkocha india is hosted in sheared gray quartz veins that were emplaced in carbonaceous pyritic phyllite gold occurs as enclosed grains within sulfides and free grains in quartz based on characteristic textural and chemical features documented by x ray element imaging electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry analyses four pyrite types were identified in carbonaceous phyllites and auriferous veins rock hosted fine grained syn sedimentary to early diagenetic pyrite framboids pyi have lower contents of co and as but consistently high gold values pyrite of the next generation pyii has numerous silicate and rare sulfide inclusions lower contents of co and ni moderate as values the highest mean value of invisible gold and maximum concentrations of trace elements such as li ti zn rb sr y zr nb la ce ta th u and cr pyrite of the third generation pyiii shows evidence of overgrowth over pyii contains both silicate and sulfide inclusions and are characterized by moderate contents of co high ni and low au values and higher concentrations of large ion lithophile elements but lesser amount of high field strength elements pyrites of the latest type pyiv occur as polycrystalline aggregates that contain inclusions of gold sulfides and rare silicates show oscillatory zoning of co and as and the lowest concentrations of all other trace elements successive decrease in contents of majority of trace elements from pyii to pyiv is attributed to fluid assisted recrystallization during diagenesis and low grade metamorphism later generation pyrites pyii through pyiv exhibit higher au contents regardless of their as values indicating occurrence of invisible gold mostly as nanoparticles at times reaching up to 500 ppm unlike the majority of trace elements that underwent large scale remobilizations gold was somehow locked up in pyrite resulting in a rather lean deposit at kundarkocha

effect of fracture aperture variations on the dispersion of contaminants dispersion of dissolved contaminants in fractured rocks is strongly dependent on the variability of fracture aperture large fracture aperture regions result in significant channeling of the fluid flow accelerating the movement of solutes in a particular direction which may differ locally with respect to the main flow direction from high to low hydraulic potential this may result in very early breakthrough of the contaminants significantly earlier than in the conventional parallel plate simplification of fluid flow in fractured systems in addition flow and transport in the low aperture regions can be orders of magnitude smaller which has major implications for remediating contaminated fractured media in this study we observed the transport of a nonsorbing solute in a naturally fractured rock which was characterized at very high resolution using computed tomography scanning to determine the fracture aperture distribution we compared the observed breakthrough curve of the solute at various flow rates with the predicted breakthrough curve using the fracture s geostatistics and small perturbation analysis as well as direct numerical simulation of flow through the fracture using the measured fracture aperture distribution the experimentally determined fracture transmissivity and dispersivity are within a factor of 2 of those predicted using either the small perturbation approach using the fracture geostatistics or explicit numerical modeling of breakthrough which differ by around 20 indicating that the geostatistics of the fracture aperture can be used to predict the approximate shape of the breakthrough curve for a fracture

gold and trace element zonation in pyrite using a laser imaging technique implications for the timing of gold in orogenic and carlin style sediment hosted deposits laser ablation icp ms imaging of gold and other trace elements in pyrite from four different sedimenthosted gold arsenic deposits has revealed two distinct episodes of gold enrichment in each deposit an early synsedimentary stage where invisible gold is concentrated in arsenian diagenetic pyrite along with other trace elements in particular as ni pb zn ag mo te v and se and a later hydrothermal stage where gold forms as either free gold grains in cracks in overgrowth metamorphic and or hydrothermal pyrite or as narrow goldarsenic rims on the outermost parts of the overgrowth hydrothermal pyrite compared to the diagenetic pyrites the hydrothermal pyrites are commonly depleted in ni v zn pb and ag with cyclic zones of co ni and as concentration the outermost hydrothermal pyrite rims are either as au rich as in moderate to highgrade deposits such as carlin and bendigo or co ni rich and as au poor as in moderate to low grade deposits such as sukhoi log and spanish mountain the early enrichment of gold in arsenic bearing syngenetic to diagenetic pyrite within black shale facies of sedimentary basins is proposed as a critical requirement for the later development of carlin style and orogenic gold deposits in sedimentary environments the best grade sediment hosted deposits appear to have the gold climax event toward the final stages of deformation related hydrothermal pyrite growth and fluid flow

dissolution reprecipitation of zircon at low temperature high pressure conditions lanzo massif italy abst r a c t an eclogite facies meta plagiogranite from the lanzo massif western alps italy contains crystals of zircon intimately associated with allanite zircon displays different microtextures ranging from pristine euhedral and magmatic to fractured porous varieties with mosaic zoning and pervasive recrystallization into euhedral microcrystals fractures and voids in the recrystallized zircon microcrystals are mainly filled by high pressure na rich pyroxene electron backscattered diffraction analysis revealed a similar crystallographic orientation for primary magmatic zircon crystals and microcrystals with less than 2 misorientation among neighboring microdomains the textural change is coupled with chemical and isotopic modifications recrystallized zircon domains contain significantly less th and light to mid ree but are richer in sr than magmatic zircon crystals magmatic zircon preserves the protolith u pb age of 163 5 1 7 ma whereas zircon microcrystals have a mean age of 55 1 ma the coexisting allanite also contains inclusions of na rich pyroxene and has chemical features elevated sr and ni contents and lack of eu anomaly indicating formation at high pressure despite being associated texturally with zircon allanite yields a younger th pb age of 46 5 3 0 ma suggesting that the lanzo unit remained at relatively high pressure conditions for 8 m y zircon recrystallization proceeded with volume reduction and loss of material to an alkaline metamorphic fluid that acted as the agent for a coupled dissolution reprecipitation process recrystallization occurred with minimum transport in a low strain environment and was not significantly enhanced by metamictization the source of the fluid for zircon recrystallization is most probably related to prograde devolatilization reactions in the surrounding serpentinite

trace element and fluid inclusion geochemistry constraint for genesis of gold polymetallic mineralization in the songhung deposit dpr korea abstract the songhung deposit is located in the southwestern part of the yangdok metamorphic core complex ymcc in the northern portion of the pyongnam basin the eastern part of the sino korean craton in this paper we present a detailed study on the magma sources of the granitoids yangdok and hoechang graintic intrusions genesis of pyrite and fluid inclusion characteristics for sufficient and additional understanding of tectonic events petrogenesis of the granitoids and mineralization in the study deposit the yangdok granite has lower al2o3 tio2 ratios mean value of 60 58 than the hoechang granite mean value of 994 46 indicating the higher temperature magma source of the former on the rb ba vs rb sr and cao tfeo mgo tio2 vs cao tfeo mgo tio2 discriminant diagrams the magma source of the yangdok granite belongs in the plagioclase rich and clay poor source rocks while those of the hoechang granite plots either in the plagioclase rich and clay poor source rocks for granite and fine grained granite or in the plagioclase poor and clay rich source rocks for granite porphyry and felsite on the nb vs y ta vs yb rb vs y nb and rb vs yb ta tectonomagmatic discrimination diagrams these two granites are connected with the volcanic arc related setting and plot in post collision setting moreover some data of the hoechang granite fall in wpg field suggesting that the volcanic arc setting may be changed to an intraplate setting from middle cretaceous the pyrite trace element geochemistry showing the high co ni ratio than one with an average of 8 2 and high co content and low ni content suggests that its formation was closely linked with i type granitic magma derived hydrothermal fluid mixed with meteoric water it could also be assumed by the co and as contents in pyrite indicating a certain degree of meteoric water in the ore forming fluid it is consonant to the pb s c and o isotope geochemistry in the previous study suggesting that ore forming fluids and metals could be derived from both the yangdok granite and the proterozoic and paleozoic meta sedimentary rocks exposed in the study area all of the pyrite grains have not compositional zoning and the similar distribution patterns of co and ni are appeared in single pyrite grain from core to rim suggesting the stable crystallization environment of pyrites and same ore forming fluid source in pyrite grains the positive correlation between gold and arsenic is appeared the au exists either as a micro and nano size inclusion in pyrite and other minerals or as a solid solution in pyrite lattice based on the petrological and microthermometric characteristics of the fluid inclusions in ore bearing quartz we suggest that the ore forming fluid is represented as nacl h2o or nacl kcl h2o systems with low salinity the absence of co2 enriched phase and vapor only or liquid only primary inclusions in quartz indicates the homogenous magma derived ore forming fluids and a lack of boiling during ore forming process the formation temperature and pressure of this deposit approximately vary from 317 to 326 c and from 105 46 to 111 69 105 pa respectively exhibiting the hydrothermal deposit origin in conclusion the songhung deposit is originated from i type granitic magma source derived hydrothermal fluid which was mixed with meteoric water

a combined chemical isotopic and microstructural study of pyrite from roll front uranium deposits lake eyre basin south australia abstract the common sulfide mineral pyrite is abundant throughout sedimentary uranium systems at pepegoona pepegoona west and pannikan lake eyre basin south australia combined chemical isotopic and microstructural analysis of pyrite indicates variation in fluid composition sulfur source and precipitation conditions during a protracted mineralization event the results show the significant role played by pyrite as a metal scavenger and monitor of fluid changes in low temperature hydrothermal systems in situ micrometer scale sulfur isotope analyses of pyrite demonstrated broad scale isotopic heterogeneity 34 s 43 9 to 32 4 vcdt indicative of complex multi faceted pyrite evolution and sulfur derived from more than a single source preserved textures support this assertion and indicate a genetic model involving more than one phase of pyrite formation authigenic pyrite underwent prolonged evolution and recrystallization evidenced by a genetic relationship between archetypal framboidal aggregates and pyrite euhedra secondary hydrothermal pyrite commonly displays hyper enrichment of several trace elements mn co ni as se mo sb w and tl in ore bearing horizons hydrothermal fluids of magmatic and meteoric origins supplied metals to the system but the geochemical signature of pyrite suggests a dominantly granitic source and also the influence of mafic rock types irregular variation in 34 s coupled with oscillatory trace element zonation in secondary pyrite is interpreted in terms of continuous variations in fluid composition and cycles of diagenetic recrystallization a late stage oxidizing fluid may have mobilized selenium from pre existing pyrite subsequent restoration of reduced conditions within the aquifer caused ongoing pyrite re crystallization and precipitation of selenium as native selenium these results provide the first qualitative constraints on the formation mechanisms of the uranium deposits at beverley north insights into depositional conditions and sources of both sulfide and uranium mineralization and an improved understanding of pyrite geochemistry can also underpin an effective vector for uranium exploration at beverley north and other sedimentary systems of the lake eyre basin as well as in comparable geological environments elsewhere

the coupled geochemistry of au and as in pyrite from hydrothermal ore deposits the ubiquity of au bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of au and as in this sulfide occurs under a wide range of physico chemical conditions despite significant advances in the last 20years fundamental factors controlling au and as ratios in pyrite from ore deposits remain poorly known here we explore these constraints using new and previously published empa la icp ms sims and pixe analyses of as and au in pyrite from carlin type au epithermal au porphyry cu cu au and orogenic au deposits volcanogenic massive sulfide vhms witwatersrand au iron oxide copper gold iocg and coal deposits pyrite included in the data compilation formed under temperatures from 30 to 600 c and in a wide variety of geological environments the pyrite au as data form a wedge shaped zone in compositional space and the fact that most data points plot below the solid solubility limit defined by reich et al 2005 indicate that au1 is the dominant form of au in arsenian pyrite and that au bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native au the analytical data also show that the solid solubility limit of au in arsenian pyrite defined by an au as ratio of 0 02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal chemical properties of pyrite and post depositional alteration compilation of au as concentrations and formation temperatures for pyrite indicates that au and as solubility in pyrite is retrograde au and as contents decrease as a function of increasing temperature from 200 to 500 c based on these results two major au as trends for au bearing arsenian pyrite from ore deposits are defined one trend is formed by pyrites from carlin type and orogenic au deposits where compositions are largely controlled by fluid rock interactions and or can be highly perturbed by changes in temperature and alteration by hydrothermal fluids the second trend consists of pyrites from porphyry cu and epithermal au deposits which are characterised by compositions that preserve the au as signature of mineralizing magmatic hydrothermal fluids confirming the role of this sulfide in controlling metal ratios in ore systems

trace element heterogeneity in molybdenite fingerprints stages of mineralization abstract variations in molybdenite trace element chemistry represent a tool for discriminating discrete events in young magmatic hydrothermal systems and constrain the role of granites in older greenstone belt hosted gold systems we show that besides re and w typical lattice bound elements molybdenite also concentrates chalcophile elements with chalcogenide affinity such as bi pb and te ces elements from the latter group form nano to micron scale inclusions which also attract au and ag incorporation high concentration of all elements is attributable to lattice defects and coherent intergrowths between molybdenite and ce minerals rather than polytypism if both groups are used trace element patterns are useful for interpreting superimposed ore forming processes we test the validity of this hypothesis by carrying out laser ablation inductively coupled mass spectroscopy spot analysis and element mapping on high re molybdenite from the tertiary au deposit at hilltop nv usa and the archean boddington cu au deposit western australia whereas w and ces are affected by both deformation and interaction with subsequent fluids re is only affected by the latter an epithermal overprint at hilltop recorded in a grain with a ce rich halo surrounding a core with re w oscillatory zoning upgrades re content and is also traceable by measurable au at boddington granite derived fluids dilute re in precursor molybdenite but both granite and orogenic deformation assist ce mineral coarsening and au release

la icp ms trace element analysis of magnetite and pyrite from the hetaoping fe zn pb skarn deposit in baoshan block sw china implications for ore forming processes abstract the hetaoping deposit is one of the largest fe zn pb skarn deposit in sw china which is characterized by zn pb mineralization in the upper part and the fe mineralization in the deeper part the fe mineralization is dominated by magnetite and pyrite magnetite can be subdivided into four types primary banded magnetite samples in clinopyroxene actinolite skarn mt 1 primary disseminated magnetite in garnet skarn mt 2 primary disseminated magnetite in clinopyroxene actinolite skarn mt 3 and altered magnetite in clinopyroxene actinolite skarn mt 4 pyrite can be subdivided into three types pyrite in oxide ore stage py 1 pyrite in early sulfide ore stage py 2 and pyrite in late sulfide ore stage py 3 the flat time resolved signals of laser ablation inductively coupled plasma mass spectrometry la icp ms imply that trace elements exist mainly in the form of isomorphism in magnetite and pyrite with the exception some incompatible trace elements e g ca k and na in magnetite and pb bi and ag in pyrite trace element concentrations in magnetite and pyrite demonstrate that the ore forming fluid in hetaoping is of magmatic origin furthermore compared to porphyry iocg kinuna and bif type magnetite the magnetite from hetaoping has relatively low ti v and ni concentrations but high al mn and ca concentrations implying a typical skarn genesis the variation of ti concentrations in magnetite is an indication of the formation temperature and shows that banded magnetite mt 1 precipitated in a relatively high temperature environment compared with disseminated magnetite mt 2 and mt 3 compared to mt 1 and mt 3 mt 2 has a higher si al and w contents and a lower mg and mn contents the mn content increases from py 1 to py 2 and decreases from py 2 to py 3 suggesting that the fluid rock interaction increased from the oxide ore stage to the sulfide ore stage and decreased from sulfide ore stage to post ore stage the variation of the v concentration in magnetite grains indicates a relatively higher oxygen fugacity of mt 2 compared to mt 1 and mt 3 implying that the oxygen fugacity of the ore forming fluid in the garnet skarn zone is higher than that in clinopyroxene actinolite skarn zone the variable oxygen fugacity probably caused spatial zoning of mineralization in hetaoping fe zn pb skarn deposit the temperature and oxygen fugacity of the ore forming fluid and the extent of fluid rock interaction controlled the temporal order and spatial zonation of magnetite and sulfide precipitation which led to the formation of the hetaoping fe zn pb skarn deposit

high resolution cat imaging of fractures in consolidated materials abstract high resolution measurements of fracture aperture of granite and sandstone rocks were performed using cat scanner the aperture distribution was statistically characterized for future experimental and numerical studies on single and multiphase flow and transport the fracture aperture can be measured in situ and non destructively with cat scanning the minimum pixel size is 0 27 0 27 mm but fractures as small as 35 m can be accurately measured using a calibration standard for the variation in ct number due to the missing rock mass in a given pixel a calibration standard for each rock type yields distinctly different calibration slopes about 17 greater for granite compared to sandstone indicating that each rock type should be analyzed against its own calibration standard the aperture distribution is rather heterogeneous and is best described by a lognormal function corroborated by comparing the theoretical to actual ratio of hydraulic to mechanical apertures mechanical roughness of the fractures ranged from 0 17 to 1 5 the variability in fracture aperture displayed only short range structure with correlation lengths of 0 8 mm to 7 mm which is at most one tenth of the minimum dimension width of the fracture plane potential flow channels can be deduced from the fracture aperture distribution

nanoparticles in groundwater of the qujia deposit eastern china prospecting significance for deep seated ore resources abstract the characterization of nanoparticles in groundwater is recognized as an important tool that can be applied to mineral exploration in this paper we investigate the concealed orebodies of the qujia gold deposit in the jiaojia orefield of eastern china by analyzing ore related nanoparticles in groundwater using transmission electron microscopy the nanoparticles contain variable amounts of ore related elements e g ag cu zn la ce pb pt and s some of these elements are rarely found in natural settings unrelated to orebodies or mineral extraction but are strongly linked to concealed orebodies in the study area these nanoparticles which are diverse in their shapes aggregated features and degrees of crystallinity can be grouped in terms of composition as i native metal nanoparticles ii metal based nanoparticles and iii carrier nanoparticles associated with trace elements we propose that these three main types of nanoparticles enable the efficient transport of ore forming elements in groundwater the results of this study provide insights into the migratory behaviour of ore related nanoparticles in groundwater and our methods could be applied for detecting deep seated mineral deposits

in situ trace element and sulfur isotope of pyrite constrain ore genesis in the shapoling molybdenum deposit east qinling orogen china abstract the early cretaceous ca 128 ma shapoling vein type molybdenum mo mineralization associated with the huashan intrusion is a newly discovered deposit in the xiong ershan district east qinling china where pyrite is a ubiquitous mineral phase here we present results from an integrated study on the texture in situ trace element chemistry from laser ablation inductively coupled plasma mass spectrometry la icp ms and sulfur isotopic composition using secondary ion mass spectrometry sims with a view to understand the geochemical variation genesis of mo mineralization and ore forming process the distinct textural patterns as revealed by petrographic observations suggest three types of pyrites py1 is composed of coarse grained euhedral pyrite in the wall rock and early barren quartz vein at stage i py2 is represented by subhedral anhedral grains coexisting with molybdenite in quartz veins at stage ii and py3 forms irregular interstitial grains in the quartz k feldspar molybdenite dominated veins at stage iii the mo enrichment mainly occurred in py3 with co ni ratios 1 and 34s values mainly

sulfur isotope and trace element compositions of pyrite determined by nanosims and la icp ms new constraints on the genesis of the shuiyindong carlin like gold deposit in sw china the shuiyindong carlin like gold deposit the largest one of this type in china is located in the late paleozoic early mesozoic youjiang basin the pyrites in the studied ore bodies no i to v can be divided into four main types plus several sub types 1 as poor pyrites include py1 py1a and py1b py2 and py3 and 2 as rich pyrite py4 py4a and py4b in situ la icp ms analyses show that the as rich pyrite also contains higher au cu sb and tl than the other pyrite types in situ nanosims analyses show the 34s variation of py1 48 1 67 5 py2 2 4 7 6 py3 9 2 14 2 and py4 3 0 6 6 with the average values of 58 1 5 1 11 4 and 3 1 respectively the large 34s variations of as poor pyrites may reflect a sedimentary source however the narrow ranges of 34s values for the as rich pyrite py4 may not reflect a sedimentary but a magmatic or metamorphic origin a metamorphic sulfur source of py4 is favored due to paucity of coeval magmatism in the region and decreasing variations of 34s values from py1 to py4 integrated transmission electron microscope tem and nanosims element mapping show that the distribution and concentration of au are discordant with as and cu at the submicron scale also implied by the occurrence of some of au as nano submicron particles in py4 overall our new data indicate that the ore fluids were not only enriched in au but also in as cu and s taking an alternative of fluid oxidation probably resulting in the decreasing 34s values of py4 our result of i to v orebodies indicates the mixing between the underlying metamorphic fluid and meteoric water integrated variations in 34s and as au cu correlations across individual pyrite grains infer the physicochemical changes of aqueous and or aqueous carbonic fluids along migration paths