combining in situ isotopic trace element and textural analyses of quartz from four magmatic hydrothermal ore deposits this study couples in situ 16o 17o and 18o isotope and in situ trace element analyses to investigate and characterize the geochemical and textural complexity of magmatic hydrothermal quartz crystals euhedral quartz crystals contemporaneous with mineralization were obtained from four magmatic hydrothermal ore deposits el indio au ag cu deposit summitville au ag cu deposit north parkes cu au deposit and kingsgate quartz mo bi w deposit the internal features of the crystals were imaged using cathodoluminescence and qualitative electron microprobe maps quantitative isotopic data were collected in situ using 157 nm laser ablation inductively coupled plasma mass spectrometry for 40 trace elements in quartz and sensitive high resolution ion microprobe for 3 isotopes in quartz imaging revealed fine oscillatory zoning sector zoning complex macromosaic textures and hidden xenocrystic cores in situ oxygen isotope analyses revealed a 18o range of up to 12 4 0 3 in a single crystal the largest isotopic range ever ascribed to oscillatory zonation in quartz some of these crystals contain a heavier 18o signature than expected by existing models while sector zoned crystals exhibited strong trace element variations between faces no evidence for anisotropic isotope fractionation was found we found 1 isotopic heterogeneity in hydrothermal quartz crystals is common and precludes provenance analysis e g d 18o using bulk analytical techniques 2 the trace element signature of quartz is not an effective pathfinder toward noble metal mineralization and 3 in three of the four samples both textural and isotopic data indicate non equilibrium deposition of quartz

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

sulfur isotopes trace element and textural analyses of pyrite arsenopyrite and base metal sulfides associated with gold mineralization in the pataz parcoy district peru implication for paragenesis fluid source and gold deposition mechanisms in the pataz parcoy district current mining activity is focused on the mesothermal quartz carbonate sulfide veins hosted by the pataz batholith total gold production yielded approximately 8 moz with grades in the mined ore shoots varying between 7 and 15 g t au and locally reaching up to 120 g t au high grade ore shoots are extraordinarily enriched in sulfides representing 10 to 20 modal vol of the vein ore mineralogy is characterized by a complex paragenesis of pyrite arsenopyrite galena sphalerite chalcopyrite and gold gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite a novel combination of secondary ion mass spectrometry laser ablation inductively coupled plasma mass spectrometry and electron probe microanalysis is used to track the compositional evolution of ore fluid s and to investigate the mineralization processes occurring in the pataz parcoy district contrasting with the classical two stage ore sequence previously proposed for the pataz parcoy district we suggest a revised paragenetic sequence i e 1 deposition of pyrite core pyi with homogeneously distributed base metal sulfide inclusions 2 progressive replacement of pyi by arsenian pyrite pyii and arsenopyrite associated with invisible gold deposition and 3 deposition of sphalerite galena chalcopyrite electrum in fractured pyrite and arsenopyrite we propose two models for the formation of base metal sulfide inclusions in pyi i e 1 co precipitation of base metal sulfide with pyi and later redistribution in cracks driven by partial as replacement of pyi to pyii and arsenopyrite and 2 preferential replacement of the pyi along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite

multi stage growth and fluid evolution of a hydrothermal sulphide chimney in the east pacific ridge 1 2 s hydrothermal field constraints from in situ sulphur isotopesx meng and othersin situ sulphur isotopes of hydrothermal sulphides sulphur isotopes can be used as a powerful tool to trace fluid evolution and explore the formation of chimneys to clarify the in situ s isotopic variations of sulphides at the micro scale we analyzed a sulphide chimney collected from the hydrothermal field in the east pacific rise 1 2 s using a sensitive high mass resolution ion micro probe for stable isotopes shrimp si three mineral zones can be identified in the chimney an external outer wall of porous anhydrite and colloform pyrite an internal middle zone of sub euhedral pyrite and massive chalcopyrite and an inner zone of massive pyrite the 34 s v cdt values of the sulphides fall within the range 1 83 7 51 avg 4 05 n 16 and s isotopic values increase from the core 3 09 n 3 to the middle 3 78 n 11 to the edge 6 99 n 2 these results illustrate mineral crystallization processes and the mixing between seawater derived s and magmatic hydrothermal fluids during the growth of the chimney the zones from the edge to the core are characterized by crystal morphologies of colloform anhedral pyrite to massive pyrite with decreasing 34 s values revealing multi stage mineral deposition and sulphur isotopic fractionation in contrast to the increase in 34 s values from the core to the edge in one profile profile a anomalously low 34 s values in fine grained pyrite relative to chalcopyrite in another profile profile b in the middle zone result from s isotopic exchange between seawater so 4 2 and fluid h 2 s due to different fluid seawater mixing possibly caused by variations in permeability and porosity across the chimney

trace metals in pyrite and marcasite from the agua rica porphyry high sulfidation epithermal deposit catamarca argentina textural features and metal zoning at the porphyry to epithermal transition abstract agua rica is a world class cu mo au deposit located in catamarca argentina in which the porphyry and high sulfidation epithermal stages are juxtaposed due to the telescoping of the mineralizing system pyrite is the most abundant sulfide in the analyzed section of the deposit and shows variations in textures and trace metal content determined by la icpms between the porphyry and epithermal stages pyrite from the porphyry stage is fine grained and depleted in most trace elements analyzed except for traces of co up to 276 ppm and ni up to 131 ppm pyrite from the epithermal stage is texturally complex compositionally heterogeneous and the trace metal content varies with depth and within sub stages of mineralization at an intermediate depth 2625 m epithermal pyrite from the cement of the jig saw and clast supported hydrothermal breccias are enriched in cu up to 2961 ppm that correlates with the highest cu grades in the section this pyrite contains micro inclusions of sulfosalt minerals as inferred by la icpms elemental mapping and individual spot ablation profiles they are zoned and show a co rich core an intermediate zone enriched in cu and an outer rim rich in zn at shallower levels 3000 m epithermal pyrite cements in the heterolithic hydrothermal breccia are unusually rich in trace metals that correlate with the highest pb zn au and ag grades the ore stage pyrite occurs as either successive colloform bands on earlier co bearing cores or as veinlets infill the colloform pyrite bands and veinlets are as poor

geological geochronological pyrite geochemical and stable isotope studies of the tantou gold deposit in central china abstract the tantou au deposit is a large scale gold deposit in the xiong ershan area a geochemical study of pyrite was conducted using laser ablation inductively coupled plasma mass spectrometry two types of hydrothermal pyrite were identified in the ores and wall rocks i e the fine euhedral pyrite in brecciated ores py1 and coarse grains disseminated in the quartz sulfide veins py2 the trace elements of the two pyrite types exhibit different concentrations associations and rim core zoning implying different geneses and crystallization processes both pyrites of the two mineralization stages were hydrothermal pyrite however the au as co ni and zn were more rich in py1 while ag cu mo sb and pb were favored in py2 the growth rims of py1 suggest several pulses of fluid activities hydrothermal sulfides from the main ore forming stage have a rb sr isochron age of 124 2 3 1 ma placing the gold mineralization in the early cretaceous the initial 87sr 86sr value of the sulfides is 0 71124 0 00010 suggesting an ancient crust source the paleoproterozoic xiong er group in situ s isotope data acquired from the main sulfides suggest that the ore forming materials underwent isotopic fractionation because of oxidation of the ore forming fluids during the hydrothermal process the c o isotope values of calcite from the postore stage indicate that magmatic fluids were likely the principle sources of carbon and that low temperature alteration has had a significant effect on the levels of co2 and carbonate ions together these results suggest that the tantou au deposit is genetically related to the destruction of the north china craton as a result of lithospheric thinning during the early cretaceous

magmatic vapor expansion and the formation of high sulfidation gold deposits chemical controls on alteration and mineralization abstract large bulk tonnage high sulfidation gold deposits such as yanacocha peru are the surface expression of structurally controlled lode gold deposits such as el indio chile both formed in active andesite dacite volcanic terranes fluid inclusion stable isotope and geologic data show that lode deposits formed within 1500 m of the paleo surface as a consequence of the expansion of low salinity low density magmatic vapor with very limited if any groundwater mixing they are characterized by an initial sulfate stage of advanced argillic wallrock alteration alunite commonly with intense silicification followed by a sulfide stage a succession of discrete sulfide sulfosalt veins that may be ore grade in gold and silver fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 c and preserve a record of a vapor rich environment recent data for el indio and similar deposits show that at the commencement of the sulfide stage condensation of cu as s sulfosalt melts with trace concentrations of sb te bi ag and au occurred at 600 c following pyrite deposition euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor saturated melt occurs to fe tennantite with progressive non equilibrium fractionation of heavy metals between melt vapor and solid vugs containing a range of sulfides sulfosalts and gold record the changing composition of the vapor published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock this sulfate stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays from any external contemporary hydrothermal activity subsequent fracturing is localized by the embrittled wallrock to provide high permeability fracture arrays that constrain vapor expansion with minimization of heat loss the sulfide stage vein sequence is then a consequence of destabilization of metal vapor species in response to depressurization and decrease in vapor density the geology mineralogy fluid inclusion and stable isotope data and geothermometry for high sulfidation bulk tonnage and lode deposits are quite different from those for epithermal gold silver deposits such as mclaughlin california that formed near surface in groundwater dominated hydrothermal systems where magmatic fluid has been diluted to less than about 30 high sulfidation gold deposits are better termed solfataric gold deposits to emphasize this distinction the magmatic vapor expansion hypothesis also applies to the phenomenology of acidic geothermal systems in active volcanic systems and equivalent magmatic vapor discharges on the flanks of submarine volcanoes

paleoproterozoic high sulfidation mineralization in the tapajos gold province amazonian craton brazil geology mineralogy alunite argon age and stable isotope constraints the brazilian tapajos gold province contains the first evidence of high sulfidation gold mineralization in the amazonian craton the mineralization appears to be in large nested calderas the tapajos parima or ventuari tapajos geological province consists of a metamorphic igneous and sedimentary sequence formed during a 2 10 to 1 87 ga ocean continent orogeny the high sulfidation mineralization with magmatic hydrothermal alunite is related to hydrothermal breccias hosted in a rhyolitic volcanic ring complex that contains granitic stocks ranging in age from 1 89 to 1 87 ga cone shaped hydrothermal breccias which flare upward contain vuggy silica and have an overlying brecciated cap of massive silica the deposits are located in the uppermost part of a ring structure volcanic cone drill cores of one of the hydrothermal breccias contain alunite natroalunite pyrophyllite andalusite quartz rutile diaspore woodhouseite svanbergite kaolinite and pyrite along with inclusions of enargite luzonite chalcopyrite bornite and covellite the siliceous core of this alteration center is surrounded by advanced argillic and argillic alteration zones that grade outward into large areas of propylitically altered rocks with sericitic alteration assemblages at depth several occurrences and generations of alunite are observed alunite is disseminated in the advanced argillic haloes that envelop massive and vuggy silica or that underlie the brecciated silica cap coarse grained alunite also occurs in branching veins and locally is partly replaced by a later generation of fine grained alunite silicified hydrothermal breccias associated with the alunite contain an estimated reserve of 30 tonnes of gold in rock that grades up to 4 5 g t 1 au seven alunite samples gave 40ar 39ar ages of 1 869 to 1 846 ga with various degrees of apparent minor ar loss stable isotopic data require a magmatic hydrothermal origin for the alunite typical for high sulfidation mineralization the 34s values of most samples of alunite range from 14 0 to 36 9 sulfur isotopic alunite pyrite and oxygen isotopic alunite so4 oh temperatures range from 130 to 420 c the dh2o and 18oh2o values for alunite forming hydrothermal fluids suggest a predominance of magmatic water with a small meteoric contribution a rare sample of supergene alunite has a 34s value of 4 1 and an 40ar 39ar age of 51 3 0 1 ma other than local foliation in the volcanic rocks and recrystallization of alunite near faults the mineralization and associated alteration appears to have been remarkably undisturbed by later metamorphism and by supergene alteration the au mineralization was preserved because of burial by sediments and tuffs in taphrogenic basins that probably developed shortly after mineralization and were probably first exhumed at about 60 ma because high sulfidation mineralization forms at relatively shallow crustal levels the discoveries in tapajos province provide new perspectives for mineral exploration for the amazonian and perhaps for other precambrian cratons

selenium and tellurium resources in kisgruva proterozoic volcanogenic massive sulphide deposit norway abstract the former mining site at kisgruva near kongsberg norway is primarily composed of worked sulphide ore deposits of hydrothermal origin which occur within precambrian metamorphic basement though the original targets at the kisgruva mine site were extraction of copper cu sulphur s and iron fe the sulphide ore also contains exceptionally high concentrations of selenium se and tellurium te hosted within selenides clausthalite and minor naumannite and tellurides hessite and minor altaite and tellurobismuthite both se and te are also present within the sulphide ore in pyrite and chalcopyrite which contain exceptionally high concentrations of up to 688 ppm se and 81 ppm te additionally oxidative weathering of the exposed bedrock has resulted in the accumulation of hyper enriched unconsolidated weathered crust deposits at surface se up to 1590 ppm te up to 63 ppm containing selenite seo32 and tellurite teo32 ions concentrations of se and te are subsequently higher in the weathering products than in the sulphide ore due to fixation on to organic matter 0 4 in weathered ore crusts jarosite formed from oxidation of sulphides from the primary ore ferric oxide and hydroxide phases goethite and haematite increasing demand for se and te to use in green technologies has led to the reassessment of these orebodies and their associated weathered ore crust deposits though these elements are currently considered mining contaminants this and similar sites may be of future economic importance particularly as demand for se and te continues to rise

silica hydrate preserved with δ18o rich quartz in high temperature hydrothermal quartz in the high sulfidation copper gold deposit at el indio chile quartz microcrystals from the el indio au ag cu deposit chile preserve a rare glimpse into the high temperature evolution of silica here we show for the first time that aggregates of euhedral quartz microcrystals preserve cryptocrystalline cores that contain silica hydrates opal and moganite we propose that these phases are metastable remnants of progressive dehydration from a precursor silica hydrate phase evidence for sequential dehydration to from silica hydrate to quartz silica hydrate opal moganite quartz is provided by shrimp 18o microanalytical data that show oscillatory isotopic zoning from 3 6 to 16 2 18o 0 5 coupled with k and al variations we estimate that the precursor silica hydrate deposited between 480 680 c and contained 32 63 wt h2o silica hydrate is metastable with respect to quartz and forms during rapid deposition of silica at high silica supersaturation a consequence of rapid expansion of magmatic fluid into the fracture array that hosts the el indio copper gold deposit modern understanding of ore forming fluids in hydrothermal ore deposits is largely underpinned by the assumption that quartz and its included fluids faithfully record depositional conditions the discovery of silica hydrate affects the paragenetic and geochemical interpretation of quartz and included fluids quartz matured from silica hydrate would record pseudo primary fluid inclusions such that homogenization temperatures record retrograde rather than depositional conditions while 18o data may bias fluid provenance interpretation within sub volcanic systems

stable isotope geochemistry of the pierina high sulfidation au ag deposit peru influence of hydrodynamics on so42 h2s sulfur isotopic exchange in magmatic steam and steam heated environments abstract the pierina high sulfidation au ag deposit formed 14 5 my ago in rhyolite ash flow tuffs that overlie porphyritic andesite and dacite lavas and are adjacent to a crosscutting and interfingering dacite flow dome complex the distribution of alteration zones indicates that fluid flow in the lavas was largely confined to structures but was dispersed laterally in the tuffs because of a high primary and alteration induced permeability the lithologically controlled hydrodynamics created unusual fluid temperature and ph conditions that led to complete so 4 2 h 2 s isotopic equilibration during the formation of some magmatic steam and steam heated alunite a phenomenon not previously recognized in similar deposits isotopic data for early magmatic hydrothermal and main stage alunite 34 s 8 5 to 31 7 18 o so 4 4 9 to 16 5 18 o oh 2 2 to 14 4 d 97 to 39 sulfides 34 s 3 0 to 4 3 sulfur 34 s 1 0 to 1 1 and clay minerals 18 o 4 3 to 12 5 d 126 to 81 are typical of high sulfidation epithermal deposits the data imply the following genetic elements for pierina alteration mineralization 1 fluid and vapor exsolution from an i type magma 2 wallrock buffering and cooling of slowing rising vapors to generate a reduced h 2 s so 4 6 highly acidic condensate that mixed with meteoric water but retained a magmatic 34 s s signature of 1 3 so 2 disproportionation to hso 4 and h 2 s between 320 and 180 c and 4 progressive neutralization of laterally migrating acid fluids to form a vuggy quartz alunite quartz clay intermediate argillic propylitic alteration zoning magmatic steam alunite has higher 34 s 8 5 to 23 2 and generally lower 18 o so 4 1 0 to 11 5 18 o oh 3 4 to 5 9 and d 93 to 77 values than predicted on the basis of data from similar occurrences these data and supporting fluid inclusion gas chemistry imply that the rate of vapor ascent for this environment was unusually slow which provided sufficient time for the uptake of groundwater and partial to complete so 4 2 h 2 s isotopic exchange the slow steam velocities were likely related to the dispersal of the steam column as it entered the tuffs and possibly to intermediate exsolution rates from magmatic brine the low d values may also partly reflect continuous degassing of the mineralizing magma similarly data for steam heated alunite 34 s 12 3 to 27 2 18 o so 4 11 7 to 13 0 18 o oh 6 6 to 9 4 d 59 to 42 are unusual and indicate a strong magmatic influence relatively high temperatures 140 to 180 c based on 18 o so 4 oh fractionations and partial to complete sulfur isotopic exchange between steam heated sulfate and h 2 s restricted lithologically controlled fluid flow in the host tuffs allowed magmatic condensate to supplant meteoric groundwater at the water table and create the high temperature low ph conditions that permitted unusually rapid so 4 2 h 2 s isotopic equilibration 50 300 days and or long sulfate residence times for this environment late void filling barite 34 s 7 4 to 29 7 18 o so 4 0 4 to 15 1 and later void filling goethite 18 o 11 8 to 0 2 document a transition from magmatic condensate to dominantly meteoric water in steam heated fluids during cooling and collapse of the hydrothermal system these steam heated fluids oxidized the top 300 m of the deposit by leaching sulfides redistributing metals and precipitating barite acanthite gold and goethite hematite gold steam heated oxidation rather than weathering was critical to forming the orebody in that it not only released encapsulated gold but likely enriched the deposit to ore grade au concentrations

sulfosalt melts evidence of high temperature vapor transport of metals in the formation of high sulfidation lode gold deposits in enargite gold high sulfidation vein deposits magmatic fluid is considered responsible for the transport of metals and sulfur into the depositional regime new data from field emission sem analyses of sulfosalt mineral assemblages primarily enargite and tennantite from el indio chile and summitville colorado provide direct evidence of high temperature deposition including the following 1 the preservation of delicate euhedral quartz assemblages in sulfosalts 2 a range of discrete sb rich sulfosalt quartz feldspar and flourapatite vug filling minerals and 3 symplectic sulfosalt chalcopyrite textures that are arguably quenched melts together these features indicate formation from the vapor phase at high temperatures furthermore euhedral quartz crystals from el indio contain high temperature vapor rich fluid inclusions combined these observations are interpreted as suggestive of deposition in response to vapor phase decompression within fracture arrays that may be considered the analogues of the feeder fractures beneath large low grade silver gold deposits such as yanacocha peru

nanoscale liquid inclusions of as fe s in arsenian pyrite a new mode of arsenic incorporation into arsenian pyrite has been discovered electron microprobe analyses and elemental maps of arsenian pyrite from pueblo viejo dominican republic show that its chemical composition varies from fe0 998as0 003 1 001s2 to fe0 963as0 050cu0 003ag0 001 1 017s2 and that arsenic is inversely correlated with fe high resolution transmission electron microscopy hrtem images show that some arsenic in this pyrite is present as nanoscale inclusions of amorphous as fe s in a matrix of arsenian pyrite the amorphous inclusions display negative facets with a cubic or rectangular morphology typical of negative inclusions of pyrite and arsenopyrite or marcarsite respectively and they are oriented parallel to the lattice fringes 100 of the arsenian pyrite matrix elemental maps collected by high angle annular dark field scanning transmission electron microscopy haadf stem show that the inclusions have a higher content of arsenic than the surrounding pyrite and tem edx analyses indicate approximate atomic proportions of 62 at s 28 at fe and 10 at as for the inclusions which are near the minimum melting temperature in the as fe s ternary these observations suggest that the inclusions were trapped as liquids during growth of the surrounding arsenian pyrite although not a new mineral this constitutes a third form for arsenian pyrite which has previously been shown to contain arsenic as either as1 or as3

analysis of borehole seismograms from long valley california implications for caldera structure a three component seismometer was emplaced in a borehole in long valley caldera for a period of 2 months to record local earthquakes to the south mostly in the sierra nevada the seismic records were plotted in depth versus time sections to produce vertical hypocentral profiles for both the vertical and horizontal components the data collected and displayed in this way provide good resolution of the crustal structure at depth and avoid the attenuation and complications introduced by the near surface caldera fill the record sections were then modeled with two dimensional ray tracing to match the observed travel times although nonreversal of the profiles and uncertainties in hypocentral locations introduce ambiguities the final interpretation reveals two separate low velocity bodies which we have tentatively identified as magma beneath the resurgent dome in long valley the first of these is a small 2 km by 6 km body with a depth to top of approximately 3 7 km beneath the surface at the southern end of the resurgent dome the other body appears larger and lies at a depth of 5 5 km beneath the northern end of the resurgent dome

silver base metal epithermal vein and listwaenite types of deposit crnac rogozna mts kosovo part i ore mineral geochemistry and sulfur isotope study abstract pb zn ag vein and listwaenite types of mineralization in crnac deposit western vardar zone were deposited within several stages i the pre ore stage comprises pyrite arsenopyrite pyrrhotite quartz kaolinite and is followed by magnetite pyrite ii the syn ore stage is composed of galena sphalerite tetrahedrite and stefanite and iii the post ore stage is composed of carbonates pyrite arsenopyrite and minor galena the vein type mineralization is hosted by jurassic amphibolites and veins terminate within overlying serpentinites mineralized listwaenites are developed along the serpentinite amphibolite interface the reserves are estimated to 1 7 mt of ore containing in average 7 6 lead 2 9 zinc and 102 g t silver sulfides from the pre and syn mineralization assemblage of the vein and listwaenite types of mineralization from the crnac pb zn ag deposit have been analyzed using microprobe crush leachates and sulfur isotopes the pre ore assemblage precipitated under high sulfur fugacities f s 2 10 8 10 6 bar from temperatures ranging between 350 c and 380 c most likely water rock reactions boiling and or increase of ph caused an increase of 34 s of pyrite toward upper levels within the deposit the decomposition of pre ore pyrrhotite to a pyrite magnetite mixture occurred at a fugacity of sulfur from f s 2 8 7 10 10 to 9 6 10 9 bar and fugacity of oxygen from f o 2 2 4 10 30 to 3 1 10 28 bars indicating a contribution of an oxidizing fluid i e meteoric water during pre ore stages of hydrothermal activity the crystallization temperatures obtained by the sphalerite galena isotope geothermometer range from 230 to 310 c the 34 s values of pre and syn ore sulfides pyrite galena sphalerite 34 s 0 3 5 9 point to magmatic sulfur values of 34 s of galena and sphalerite are decreasing upwards due to precipitation of early formed sulfide minerals post ore assemblage precipitated at temperature below 190 c based on data presented above we assume two fluid sources i a magmatic source supported by sulfur isotopic compositions within pre and syn ore minerals and a high mol of fluorine found within pre and syn ore leachates and ii a meteoric source deduced by coincident pyrite magnetite intergrowth sulfur isotopic trends within syn ore minerals and decrease of crystallization temperatures from the pre ore stage 380 350 c towards the syn ore 310 215 c and post ore stages

porphyry copper deposit formation by sub volcanic sulphur dioxide flux and chemisorption the processes that create economic grade accumulations of metals above magma chambers are unclear high temperature laboratory experiments show that rapid reactions between magmatic gases and earth s crust can trigger efficient metal deposition

recent and long term behavior of the brawley fault zone imperial valley california an escalation in slip rate the brawley fault zone bfz and the brawley seismic zone constitute the principal transfer zone accommodating strain between the san andreas and im perial faults in southernmost california the bfz ruptured along with the imperial fault in the 1940 mw 6 9 and the 1979 mw 6 4 earthquakes although in each case only minor slip apparently occurred on the bfz several other episodes of slip and creep have been documented on the bfz historically until this study it has been unclear whether the past few decades reflect average behavior of the fault two trenches were opened and a series of auger holes were bored across three strands of the bfz at harris road to compare the amount of slip observed historically with the displacements observed in the paleoseismic record evidence is presented across the westernmost strand of the bfz and across the entire bfz at harris road to show that both the average vertical slip rate observed in modern times since 1970 and the vertical creep rate excluding coseismic slip observed during the 1970s are sig nificantly higher than the long term average across the westernmost strand the long term vertical rate is 1 2 1 5 0 5 mm yr and the average rate since about a d 1710 is determined to be no greater than 2 0 mm yr in contrast the average vertical rate between 1970 and 2004 across that strand was at least 4 3 mm yr and the 1970s vertical aseismic creep rate was 10 mm yr likewise across the entire bfz the long term vertical rate is 2 8 4 1 1 4 mm yr whereas the rate between 1970 and 2004 was at least 7 2 mm yr and the 1970s aseismic creep rate was 10 mm yr the long term strike slip rate cannot be determined across any strands of the bfz but may be significant in contrast to the commonly accepted higher sedimentation rates inferred for the entire imperial valley we find that the average sedimentation rate on the downthrown side of the bfz adjacent to mesquite basin in the millennium preceding the onset of agricultural influences was at most 3 5 mm yr finally a creep event occurred on the bfz during our study in 2002 and is documented herein online material appendices 1 and 2 trench logs and color versions of figures 7 8 and 10

in situ trace element and sulfur isotope analysis of pyrite in a paleoproterozoic gold placer deposit pardo and clement townships ontario canada extensive pyrite bearing auriferous cobble and boulder conglomerates are present in the basal 30 in of the mississagi formation in pardo and clement townships ontario canada the sedimentology of the conglomerates combined with regional geology indicates limited fluvial transport in a gravel bed braided river with local hyperconcentrated flows with material derived from a highly restricted catchment area postdepositional overprinting of the conglomerates is related to the penokean orogeny at 1 85 to 1 5 ga and alkali metasomatism at similar to 1 7 ga several pyrite varieties including detrital and postdepositional recrystallized and altered grains are present in the conglomerates detailed in situ laser ablation inductively coupled plasma mass spectrometry la icpms analysis of pyrite revealed that the gold in the deposit is intimately associated to large detrital pyrite grains as invisible au with lesser amounts of free gold postdepositional pyrite and pyrite overgrowths have very low au content elements such as pb bi sb te ag and hg together with au were mobilized during hydrothermal alteration and dissolution of detrital pyrite grains small scale transport and reprecipitation formed part of the postdepositional pyrite and free gold in immediate contact with postdepositional grains in contrast ni co and as were not mobilized external fluid infiltration is negligible and is indicated only by minor compositionally distinct late sulfide veinlets crosscutting the conglomerates sulfur isotope analysis of detrital pyrite yields generally positive delta 34 s values 0 97 9 26 0 the delta 34 s sulfur isotope composition of pyrite overgrowths and postdepositional grains overlaps the isotopic range of the detrital grains suggesting a near closed s system during postd epositional processes however the detrital pyrite tends to have slightly negative delta 33 s while the postdepositional and overgrowth pyrite are either neutral or slightly positive the s isotope composition of the detrital pyrite is compatible with an origin of s as dissolved sulfate in an ocean under a low oxygen atmosphere the potential source of the au bearing detrital pyrite appears to have been an as yet undiscovered archean deposit located within 1 to 8 kin of the placer deposit

evolution of high level magmatic hydrothermal systems new insights from ore paragenesis of the veladero high sulfidation epithermal au ag deposit el indio pascua belt argentina

magmatic vapor expansion and the formation of high sulfidation gold deposits structural controls on hydrothermal alteration and ore mineralization abstract high sulfidation copper gold lode deposits such as chinkuashih taiwan lepanto philippines and goldfield nevada formed within 1500 m of the paleosurface in volcanic terranes all underwent an early stage of extensive advanced argillic silica alunite alteration followed by an abrupt change to spatially much more restricted stages of fracture controlled sulfide sulfosalt mineral assemblages and gold silver mineralization the alteration as well as ore mineralization stages of these deposits were controlled by the dynamics and history of syn hydrothermal faulting at the sulfate stage aggressive advanced argillic alteration and silicification were consequent on the in situ formation of acidic condensate from magmatic vapor as it expanded through secondary fracture networks alongside active faults the reduction of permeability at this stage due to alteration decreased fluid flow to the surface and progressively developed a barrier between magmatic vapor expansion constrained by the active faults and peripheral hydrothermal activity dominated by hot water flow in conjunction with the increased rock strength resulting from alteration subsequent fault slip inversion in response to an increase in compressional stress generated new highly permeable fractures localized by the embrittled altered rock the new fractures focused magmatic vapor expansion with much lower heat loss so that condensation occurred sulfide stage sulfosalt sulfide and gold silver deposition then resulted from destabilization of vapor phase metal species due to vapor decompression through the new fracture array the switch from sulfate to sulfide assemblages is therefore a logical consequence of changes in structural permeability due to the coupling of alteration and fracture dynamics rather than to changes in the chemistry of the fluid phase at its magmatic source

linking high grade gold mineralization to earthquake induced fault valve processes in the porgera gold deposit papua new guinea processes responsible for high grade gold enrichment are of significant economic interest and have long been elusive structural and geophysical models postulate that earthquake induced fault valve processes are frequently responsible for gold mineralization in structurally controlled hydrothermal systems although a comprehensive geochemical record of these processes has been lacking the porgera gold deposit papua new guinea provides an opportunity to examine the complex processes surrounding high grade au mineralization in structurally controlled hydrothermal systems new high resolution trace element and sulfur isotope data obtained in situ by laser ablation inductively coupled plasma mass spectrometry and sensitive high resolution ion microprobe stable isotope analysis of pyrite across a well constrained paragenetic sequence reveal a temporal evolution in fluid chemistry the data uncover a stratigraphy of repeated high au negative 34 s and low au positive 34 s zones within individual pyrite crystals present in the highest grade gold event stage ii results provide the first clear geochemical documentation of rapid complete switching in ore forming processes preserved in individual pyrite crystals throughout an evolving hydrothermal system it is postulated that geochemical variations are attributable to rapid au deposition during pressure release due to fault failure followed by switching to more reduced rock buffered metal poor fluids from adjacent sediments as the rupture seals the cyclicity of this process is reflected in the pyrite zonation seen at the porgera deposit this study demonstrates the usefulness of applying contemporary analytical techniques to pyrite in hydrothermal systems to gain new insights into ore genesis and fluid pathways revealing that deposition of exceptionally high grade ore at the porgera deposit was the result of multiple events in a fluctuating ore forming environment

no mass independent sulfur isotope fractionation in auriferous fluids supports a magmatic origin for archean gold deposits the source of the auriferous fluids that formed archean greenstone gold deposits remains controversial metamorphic fluids fluids derived from felsic magmas mantle fluids and meteoric water have all been suggested we report the results of ion microprobe sensitive high resolution ion microprobe stable isotopes multiple sulfur isotope analyses 32 s 33 s 34 s conducted to constrain the source of sulfur in four archean gold deposits the analyses are of pyrite samples that are genetically related to the gold mineralization from the bellerophon victory and wallaby deposits in the eastern goldfield superterrane of the yilgarn craton western australia together with sulfide from black shale from the golden mile deposit and st ives gold camp ore associated pyrite from the beattie gold deposit of the abitibi greenstone belt of the superior craton in canada was measured to test whether the results obtained from the yilgarn craton apply to other archean gold deposits sulfur analyses from sulfide from shale show mass independent fractionation mif with 33 s as high as 1 8 whereas those from the 4 archean gold deposits are dominated by mass dependent fractionation with only a minor contribution of mif sulfur in this respect archean gold deposits contrast with archean nis deposits which are dominated by mif sulfur the absence of mif in the pyrite from the four archean gold deposits analyzed in this study is consistent with the auriferous fluid originating from a felsic magma or mantle source but inconsistent with the metamorphic and meteoritic fluid hypotheses

multistage processes linked to tectonic transition in the genesis of orogenic gold deposit a case study from the shanggong lode deposit east qinling china abstract the shanggong lode deposit represents one of the largest mesozoic orogenic gold deposits in the east qinling metallogenic belt of central china here we investigate the texture trace element and sulfur isotopic composition of pyrite from this deposit to gain insights in the ore genesis three types of pyrite are recognized by its texture py1 is represented by coarse grained cubic and pentagonal dodecahedron belonging to the stage i quartz pyrite vein py2 comprises fine grained disseminated pentagonal dodecahedron belonging to stage ii quartz sulfides vein py2 can be further divided into core and rim porous cores py2c carrying abundant visible mineral inclusions and significantly higher arsenic concentration and clean rims py2r with low arsenic systematic la icpms trace elements and sims sulfur isotopic analyses reveal two distinct stages of mineralization with diverse source materials 1 the early stage is represented by py1 which contains 0 65 70 ppm au average 11 6 ppm with relatively low and variable concentrations of cu ag te pb zn and bi the 34 s values of py1 range from 2 7 to 7 2 suggesting that the sulfur source for the early stage fluid was mainly derived from the taihua and xiong er groups and that the depleted 34 s values reflect changes of ph f o2 and fluid rock interaction 2 the main stage is represented by py2 which contains au in the range of 0 14 189 ppm average 39 7 ppm the py2 carries significantly higher contents of compatible elements ni co v and cr and ore metals e g au ag pb zn as te than those in py1 with the ore metals occurring as invisible lattice bound or nanosized particles and visible micron sized inclusions the 34 s values of py2 show marked depletion with a range of 16 3 to 11 7 attributing to the fractionation between barite and sulfide minerals together with previous studies and trace element characters in py2 we identify a contribution of au from mantle source into the ore forming fluid system during the main stage we propose that the two stages of gold mineralization in the shanggong deposit in response to the collisional assembly of qinling orogenic belt preserve evidence for diverse metal sources with the early stage derived from partial melting of the lower crust taihua and xiong er groups in the compressional stage and the main stage characterized by mantle contribution in a post collisional extensional setting our findings may have important implications for the exploration of regional triassic gold and molybdenum deposits

the fluid evolution of the nimbus ag zn au deposit an interplay between mantle plume and microbial activity abstract the nimbus ag zn au volcanic hosted massive sulfide vhms deposit represents an exceptional orebody in the yilgarn craton of western australia it is located in a zone of juvenile crust running n s through the eastern goldfields superterrane however unlike most other vhms occurrences associated with the 2690 2680 ma rift sequence teutonic bore jaguar bentley erayinia it is hosted by the ca 2705 ma plume related stratigraphy which is more typically associated with komatiite hosted nickel sulfide mineralization the nimbus deposit displays hybrid vhms epithermal characteristics resulting from low temperature and shallow water conditions which developed a quartz carbonate sericite dominated alteration assemblage in the dacite host rocks sulfide mineralization comprises pyrite sphalerite galena arsenopyrite ag sb pb bi sulfosalts and rare chalcopyrite in this study we applied a combination of in situ analytical techniques to monitor the evolving sulfur isotope signature of the mineralizing fluids and propose that the nimbus vhms deposit developed as a result of a bimodal fluid history in the first stage the hydrothermal system powered by plume related magmatism deposited a series of barren pyrite lenses with colloform textures their variable but consistently negative mass independent sulfur isotope fractionation signature 33s 0 81 reflects the interaction between mantle derived magmatic fluids and archean seawater the ubiquitous presence of carbon rich porous textures and the remnants of carbonaceous nests in colloform pyrite also indicate a significant contribution of microbial sulfate reducers during the incipient stages of sulfide precipitation the gradual formation of colloform lenses eventually sealed the hydrothermal system establishing a physical barrier that limited the interaction with seawater this process promoted the onset of higher temperature and pressure conditions required to form the high grade zn ag mineralization sourcing sulfur and fluids largely from a magmatic reservoir 33s 0 09 whereas the identification of a predominantly magmatic sulfur source is supported by sulfur isotope signatures the recognition of a magmatic origin of the fluid may only be inferred indirectly it is consistent with the observed quartz sericite alteration style and the proposed mechanism of sulfide deposition via decompression which does not require any interaction with seawater the trace element distribution of the ore related sulfides also supports a closed hydrothermal system developed through multiple fluid pulses indeed this ore forming scenario is commonly favored by high confining pressures which at nimbus were established following the deposition of the colloform pyrite lenses that progressively sealed the hydrothermal system creating the favorable conditions for mineralization

flow mechanisms in sulphide minerals abstract the sulphide minerals as a group display a diverse range in strength and mechanical behaviour in crustal environments deforming by a range of different flow mechanisms which can lead to the development of characteristic microfabrics the dependence of creep rate on imposed parameters such as stress difference temperature grainsize effective confining pressure and the activities of various components varies for each type of flow mechanism for particular phases changes in the dominant operative flow mechanism may occur in response to changes in the imposed environmental variables at high applied stress differences low effective confining pressures and low temperatures brittle failure and cataclastic flow are significant deformation mechanisms in some sulphide minerals at elevated confining pressures brittle failure can be suppressed and low temperature plasticity processes involving dislocation glide and or deformation twinning may operate with decreasing applied stress difference and at elevated temperatures even though strain may be accommodated largely by dislocation glide deformation may be rate controlled by recovery processes and dynamic recrystallization may be significant in influencing microfabric development the operation of dislocation glide processes leads to the development of crystallographic preferred orientations at very low applied stress difference various grainsize dependent atomic transfer deformation mechanisms may be important in many fluid present low to medium grade metamorphic environments solution precipitation creep processes are active in the deformation of some sulphide phases in fluid absent situations grain boundary diffusion creep may be significant at higher temperatures where intragranular diffusion is relatively rapid lattice diffusion creep processes are expected to be a major deformation mechanism in fine grained sulphide assemblages at elevated temperatures grain boundary sliding may be an important deformation mechanism

lithologic controls on mineralization at the lagunas norte high sulfidation epithermal gold deposit northern peru the 13 1 moz high sulfidation epithermal gold deposit of lagunas norte alto chicama district northern peru is hosted in weakly metamorphosed quartzites of the upper jurassic to lower cretaceous chimu formation and in overlying miocene volcanic rocks of dacitic to rhyolitic composition the dafne and josefa diatremes crosscut the quartzites and are interpreted to be sources of the pyroclastic volcanic rocks hydrothermal activity was centered on the diatremes and four hydrothermal stages have been defined three of which introduced au ag mineralization the first hydrothermal stage is restricted to the quartzites of the chimu formation and is characterized by silice parda a tan colored aggregate of quartz auriferous pyrite rutile digenite infilling fractures and faults partially replacing silty beds and forming cement of small hydraulic breccia bodies the 34s values for pyrite 1 7 2 2 and digenite 2 1 indicate a magmatic source for the sulfur the second hydrothermal stage resulted in the emplacement of diatremes and the related volcanic rocks the dafne diatreme features a relatively impermeable core dominated by milled slate from the chicama formation whereas the josefa diatreme only contains chimu formation quartzite clasts the third hydrothermal stage introduced the bulk of the mineralization and affected the volcanic rocks the diatremes and the chimu formation in the volcanic rocks classic high sulfidation epithermal alteration zonation exhibiting vuggy quartz surrounded by a quartz alunite and a quartz alunite kaolinite zone is observed company data suggest that gold is present in solid solution or micro inclusions in pyrite in the quartzite the alteration is subtle and is manifested by the presence of pyrophyllite or kaolinite in the silty beds the former resulting from relatively high silica activities in the fluid in the quartzite gold mineralization is hosted in a fracture network filled with coarse alunite auriferous pyrite and enargite alteration and mineralization in the breccias were controlled by permeability which depends on the type and composition of the matrix cement and clast abundance coarse alunite from the main mineralization stage in textural equilibrium with pyrite and enargite has 34s values of 24 8 29 4 and delta 18 mathrm o mathrm s mathrm o 4 values of 6 8 13 9 consistent with h2s as the dominant sulfur species in the mostly magmatic fluid and constraining the fluid composition to low ph 0 2 and logfo2 of 28 to 30 alunite pyrite sulfur isotope thermometry records temperatures of 190 260 c the highest temperatures corresponding to samples from near the diatremes alunite of the third hydrothermal stage has been dated by 40ar 39ar at 17 0 0 22 ma the fourth hydrothermal stage introduced only modest amounts of gold and is characterized by the presence of massive alunite pyrite in fractures whereas barite drusy quartz and native sulfur were deposited in the volcanic rocks the delta 18 mathrm o mathrm s mathrm o 4 values of stage iv alunite vary between 11 5 and 11 7 and indicate that the fluid was magmatic an interpretation also supported by the isotopic composition of barite 34s 27 1 to 33 8 and delta 18 mathrm o mathrm s mathrm o 4 8 1 to 12 7 the 34spy alu isotope thermometry records temperatures of 210 to 280 c with the highest values concentrated around the josefa diatreme the lagunas norte deposit was oxidized to a depth of about 80 m below the current surface making exploitation by heap leach methods viable

uncloaking invisible gold use of nanosims to evaluate gold trace elements and sulfur isotopes in pyrite from carlin type gold deposits one hundred nm resolution secondary ionizing mass spectrometry nanosims was used to determine the distribution of au cu as sb and s and stable isotopes of s 34s 32s in gold bearing pyrite from two refractory carlin type gold deposits west banshee northern carlin trend and turquoise ridge getchell trend located in northern nevada nanosims maps reveal that gold occurs in two discrete episodes in each deposit elevated gold concentrations correlate with elevated concentrations of as sb cu te and lower 34s 32s ratios compared to periods when gold was not deposited precipitation of elevated gold and trace elements at west banshee was followed by precipitation of pyrite with lower gold concentrations whereas at turquoise ridge precipitation of trace element rich pyrite was followed by precipitation of late ore stage minerals these nanosims results are consistent with formation of the deposits by the episodic incursion of gold rich fluids into hydrothermal systems otherwise dominated by gold poor fluids such gold rich fluid pulses may be related to incursions of magmatic fluid which have been shown to have high concentrations of gold arsenic and copper in porphyry and high sulfidation epithermal systems

geochemical and isotopic signature of pyrite as a proxy for fluid source and evolution in the candelaria punta del cobre iron oxide copper gold district chile

high selenium in the carboniferous coal measures of northumberland north east england the carboniferous lower and middle coal measures coals of the northumberland coalfield are anomalously rich in selenium se content up to 62 ppm compared to the averages for the common uk and worldwide coals as well as posing an environmental toxicity threat se is now regarded as an important resource for alloys photovoltaic products and nanotechnologies and high se coals in north east england offer an opportunity to assess the se means of occurrence origins transport mechanisms and enrichment in coals at least two generations of pyrite host high se in the sampled coal seams microbial formed disseminated pyrite both cubic and framboidal in habit and later cleat filling pyrite identified by petrographic observations laser ablation methods and sulphur isotope compositions there is a notable se enrichment of up to 250 ppm in later formed cleat filling pyrite trace element enrichment may have been sourced and influenced by seawater distribution during diagenesis and localised dykes and deformation may have acted as an enrichment mechanism for sampled seams in the region the high se coals in northumberland may provide a potential e tech element source and should be considered and carefully managed as coal mining and production are reduced in the area the study also highlights the nature of se enrichment in pyritic coals affected by cleat formation and multiple episodes of mineralisation important as critical element demand continues to increase worldwide

the sign of δ33s is independent of pyrite morphology abstract previous bulk sulphide analyses have suggested a correlation between the morphology of pyrite in archean metasedimentary rocks and the sign of associated 33s however it remains to be determined whether such a correlation exists and what the underlying mechanism is this study measured the multiple sulphur isotopic compositions of pyrite nodules and disseminated pyrite grains from two typical neoarchean shale samples with shrimp si following detailed textural investigations by sodium hypochlorite etching and electron microscopy the roy hill shale sample shows two generations of pyrite in both nodules and disseminated grains reflected by textures the first generation is 33s weakly negative while the second generation is 33s highly positive both generations of pyrite show linear relationships between 34s and 33s although generation two displays wider ranges of 34s and 33s compared with generation one in the 33s 36s diagram generation two plots along the archean reference array ara 36s 33s 1 whereas generation one deviates from the ara in a trend similar to the biological fractionation line 36s 33s 7 the nammuldi shale sample also exhibits two generations of pyrite both of which are 33s and 34s positive albeit of different magnitude for these two shale samples the sign of 33s is not associated with the pyrite morphology a plausible explanation for the morphology specific 33s reported in previous studies could be related to bulk analyses involving pyrite of different generations with opposite 33s furthermore based on the distribution of the earlier nodular and disseminated pyrite in both samples a model involving four stages is proposed for the formation of pyrite nodules studied here 1 formation of pyrite framboids composed of microcrystalline pyrite 2 dissolution of framboidal pyrite and reprecipitation to generate larger single pyrite crystals 3 aggregation of single pyrite crystals into nodules and 4 injection of later hydrothermal fluids

alunite and the role of magmatic fluids in the tambo high sulfidation deposit el indio pascua belt chile the tambo high sulfidation deposit located within the el indio pascua belt in chile produced almost 25 t 0 8 m oz of gold from altered tertiary rhyodacitic volcanic rocks episodic magmatic hydrothermal activity in the district occurred over at least 4 my and is characterized by several stages of acid sulfate alteration including magmatic hydrothermal magmatic steam steam heated and apparent supergene assemblages two stages of aufag mineralization are recognized and are hosted in barite and alunite within hydrothermal breccias and veins isotopic compositions of fluid in alunite show a dominant magmatic signature with only a variable 18 o enriched meteoric water component throughout the entire hydrothermal process alunite 40 ar 39 ar ages constrain the timing of alteration and the duration of the hydrothermal system pre ore alteration occurred at about 10 to 11 ma and was contemporaneous with the volcanism of the tambo formation alunite from this stage of alteration occurs in the matrix of barren breccias and as fine intergrowths of alunite quartzfclays that selectively replaced feldspars and pumice fragments the textural relationships combined with stable isotope systematics suggest a magmatic hydrothermal origin for the alunite with a local magmatic steam overprint early ore stage alunite 8 7f0 2 ma occurs with barite and goldfwalthierite within open spaces of the breccia matrix and has d 34 s values 24 27x typical of magmatic hydrothermal alunite reflecting equilibrium between aqueous h2s and so4 fluid inclusion ratios of h2s so2 approximately 6 are consistent with ratios determined from stable isotope data and indicate reduced fluid conditions during ore deposition vaporphase transport of au and deposition from condensed magmatic vapor rising from the brittle ductile transition is inferred late gold coprecipitated with a third stage of alunite 8 2f0 2 ma that is characterized by nearly uniform chemical compositions and d 34 s values 1x similar to those for associated enargite reflecting disequilibrium between h2s and so4 this third stage of alunite is isotopically and chemically similar to that of post ore coarse banded alunitefhematite quartz veins that crosscut the breccias in the tambo area analyses of fluid inclusion gas from alunite in these veins indicate high so2 and disequilibrium co2 co ch4 h2 species consistent with a magmatic steam origin the gases are also depleted in he and the late goldbearing alunite was probably precipitated from rapidly ascending so2 rich vapors that were flashed from condensed magmatic

sulfur isotope and trace element systematics of zoned pyrite crystals from the el indio au cu ag deposit chile we present a comparative study between early massive pyrite preceding cu ag sulfosalt mineralization in high temperature feeder zones early pyrite and late pyrite that formed during silicic alteration associated with au deposition late pyrite at the el indio high sulfidation au ag cu deposit chile we use coupled in situ sulfur isotope and trace element analyses to chronologically assess geochemical variations across growth zones in these pyrite crystals early pyrite that formed in high temperature feeder zones shows intricate oscillatory zonation of cu with individual laminae containing up to 1 15 wt cu and trace co as bi ni zn se ag sb te au pb and bi late pyrite formed after cu ag sulfosalt mineralization it contains up to 1 14 wt as with trace cu zn pb v mn co ni ge se ag sb te pb and bi as well as colloform cu rich growth bands containing vugs toward the outer edges of some crystals plotting the trace element data in chronological order i e from core to rim revealed that co and ni were the only elements to consistently co vary across growth zones other trace elements were coupled in specific growth zones but did not consistently co vary across any individual crystal the 34s of early pyrite crystals in high temperature feeder zones range from 3 19 to 1 88 0 5 consistent with sublimation directly from a high temperature magmatic vapor phase late pyrite crystals are distinctly more enriched in 34s than early pyrite 34s 0 05 4 77 0 5 as a consequence of deposition from a liquid phase at lower temperatures it is unclear whether the late pyrite was deposited from a small volume of liquid condensate or a larger volume of hydrothermal fluid both types of pyrite exhibit intracrystalline 34s variation with a range of up to 3 31 recorded in an early pyrite crystal and up to 4 48 in a late pyrite crystal variations in 34spyrite at el indio did not correspond with changes in trace element geochemistry the lack of correlation between trace elements and 34s as well as the abundance of microscale mineral inclusions and vugs in el indio pyrite indicate that the trace element content of pyrite at el indio is largely controlled by nanoscale syn depositional mineral inclusions co and ni were the only elements partitioned within the crystal structure of pyrite cu rich oscillatory zones in early pyrite likely formed by nanoscale inclusions of cu rich sulfosalts or chalcopyrite evidence of deposition from a fluid cyclically saturated in ore metals this process may be restricted to polymetallic high sulfidation like deposits

alunite in the pascua lama high sulfidation deposit constraints on alteration and ore deposition using stable isotope geochemistry the pascua lama high sulfidation system located in the el indio pascua belt of chile and argentina contains over 16 million ounces moz au and 585 moz ag the deposit is hosted primarily in granite rocks of triassic age with mineralization occurring in several discrete miocene age phreatomagmatic breccias and related fracture networks the largest of these areas is brecha central which is dominated by a mineralizing assemblage of alunitepyrite enargite and precious metals several stages of hydrothermal alteration related to mineralization are recognized including all types of alunite bearing advanced argillic assemblages magmatic hydrothermal steam heated magmatic steam and supergene the occurrence of alunite throughout the paragenesis of this epithermal system is unusual and detailed radiometric mineralogical and stable isotope studies provide constraints on the timing and nature of alteration and mineralization of the alunite pyrite enargite assemblage in the deposit early preore alteration occurred prior to ca 9 ma and consists of intense silicic and advanced argillic assemblages with peripheral argillic and widespread propylitic zones alunite of this stage occurs as fine intergrowths of alunite quartz kaolinite dickite and pyrophyllite that selectively replaced feldspars in the host rock stable isotope systematics suggest a magmatic hydrothermal origin with a dominantly magmatic fluid source alunite is coeval with the main stage of au ag cu mineralization alunite pyrite enargite assemblage ore which has been dated at approximately 8 8 ma ore stage alunite has an isotopic signature similar to preore alunite and 34salun py data indicate depositional temperatures of 245 to 305 c the d and 18o data exclude significant involvement of meteoric water during mineralization and indicate that the assemblage formed from h2sdominated magmatic fluids thick steam heated alteration zones are preserved at the highest elevations in the deposit and probably formed from oxidation of h2s during boiling of the magmatic ore fluids coarsely crystalline magmatic steam alunite 8 4 ma is restricted to the near surface portion of brecha central postmineral alunite jarosite were previously interpreted to be supergene crosscutting veins and overgrowths although stable isotope data suggest a mixed magmatic meteoric origin for this late stage alteration only late jarosite veinlets 8 0 ma associated with fine grained pseudocubic alunite have a supergene isotopic signature the predominance of magmatic fluids recorded throughout the paragenesis of the pascua system is atypical for high sulfidation deposits which typically involve significant meteoric water in near surface and peripheral alteration and in some systems even ore deposition at pascua the strong magmatic signature of both alteration and main stage alunite pyrite enargite assemblage ore is attributed to limited availability of meteoric fluids this is in agreement with published data for the el indio pascua belt indicating an event of uplift and subsequent pediment incision as well as a transition from semiarid to arid climatic conditions during the formation of the deposit in the mid to late miocene

pyrite physical and chemical textures pyrite may crystallize initially in forms as diverse as framboids or cubes depending upon the temperatures and pressures fluid rich diagenesis or low grade metamorphism clearly results in thorough recrystallization and the common formation of cubes once these have formed the pyrite becomes much more refractory and retains many characteristics even in deposits which have undergone penetrative deformation this is in strong contrast to the behavior of most of the accompanying sulfides which often undergo ductile deformation solid state or chemical remobilization and annealing pyrite deforms sparingly until there is brittle failure however there may be significant pyrite corrosion and regrowth during metamorphism as the result of sulfur exchange with other minerals especially pyrrhotite pyrite fabrics may also be significantly modified by pressure solution or coble creep optical microscopic examination and electron microprobe chemical mapping of pyrites from a variety of mineral deposits including several high grade metamorphic ones reveals that the pyrites frequently contain both physical and chemical textures that may be interpreted in terms of the depositional and the post depositional history of the deposits inclusions of sulfides or other minerals reveal information on the timing of the crystallization or recrystallization of the pyrite chemical mapping of elements such as ni co and as reveals information on the relative time of transport of these elements in the ore fluids

muscovite 40ar 39ar and in situ sulfur isotope analyses of the slate hosted gutaishan au sb deposit south china implications for possible late triassic magmatic hydrothermal mineralization abstract the gutaishan deposit is a slate hosted au sb deposit in the xiangzhong metallogenic province south china the deposit has proven reserves of ca 9 tonnes t of gold with an average grade of 13 g t and 2 500 t of sb with an average grade of 10 in this study muscovite 40ar 39ar and in situ sulfur isotope analyses of pyrite and arsenopyrite were performed to determine the mineralization age and the plausible source of s and au the 40ar 39 ar dating result of muscovite limits the formation age of the gutaishan deposit to ca 223 6 5 3 ma coeval with the adjacent baimashan granite 223 204 ma the in situ 34 s values of pyrite and arsenopyrite coexisting with native gold lie in a range between 3 7 and 2 1 with a mean value of 0 8 and these values are markedly different from those of sedimentary pyrite 7 0 to 23 3 indicating a contribution from magmatic sulfur a magma derived genetic model may therefore be suitable for the gutaishan deposit integrating the available ages of the au sb and sb au deposits and granites in the xiangzhong metallogenic province we propose that a widespread late triassic magmatic hydrothermal au sb mineralization event occurred

involvement of anomalously as au rich fluids in the mineralization of the heilan gou gold deposit jiaodong china evidence from trace element mapping and in situ sulfur isotope composition abstract the mesozoic 120 ma heilan gou gold deposit located in the jiaodong gold province eastern margin of the north china craton ncc consists of several ultra high grade up to 600 g t auriferous quartz veins in the early cretaceous guojialing granodioritic pluton ore related pyrite crystals from this deposit show complex textures in this study emp nano sims trace element mapping and in situ sulfur isotope analyses were conducted to characterize the textural and compositional features two types of pyrite were identified type i crystals py i hosted in gold quartz pyrite veins are generally homogeneous in chemical composition they contain low concentrations of as based on the distinctive textural and compositional signatures between py iia and py iib it is proposed that anomalously as au rich fluids were injected into hydrothermal systems during the late ore forming stage which may have intensively interacted with certain sedimentary rocks the involvement of these fluids firstly documented in this study can largely explain the occurrence of native gold ore shoots at heilan gou in addition the intimate association between as and au highlights the important roles of as in enrichment of au in the jiaodong gold district

ore genesis of axi post collisional epithermal gold deposit western tianshan nw china constraints from u pb dating hf isotopes and pyrite in situ sulfur isotopes abstract the axi gold deposit has long been regarded as a typical paleozoic low sulfidation epithermal deposit located in the western tianshan in the central asian orogenic belt caob sims zircon u pb dating of the ore bearing andesite and dacite yielded concordia ages of 350 8 2 7 ma and 351 3 3 1 ma respectively in situ sims hydrothermal rutile u pb dating yielded two 207pb corrected ages as 306 1 16 9 ma and 303 8 14 6 ma respectively these ages are considerably younger than the zircon sims u pb ages of ore bearing volcanic rocks which precludes a genetic link between the epithermal gold mineralization and the subduction related late devonian early carboniferous magmatism in the western tianshan instead the gold mineralization is interpreted to be genetically related to a buried 300 ma pluton that formed in a post collisional environment combined with previously published zircon hf isotopic compositions of 300 ma felsic intrusive rocks from western tianshan the results show that 300 ma felsic rocks have higher zircon ehf t values than those from 351 ma felsic rocks in the axi deposit these elevated ehf t values suggest that mantle material inputs of 300 ma axi epithermal deposit in a post collisional environment pyrite the most common sulfide in the axi ores displays heterogeneous textures and has a large variation of as contents and sulfur isotopes suggesting complex ore forming processes in the axi deposit this study highlights the importance of in situ isotopes of hydrothermal minerals to decode the ore forming histories of epithermal systems

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