interaction of magmatic fluids and silicate melt residues with saline groundwater in the footwall of the sudbury igneous complex ontario canada new evidence from bulk rock geochemistry fluid inclusions and stable isotopes abstract along the northern margin of the 1 85 ga sudbury igneous complex sic canada a volumetrically minor rock type known as the footwall granophyre fwgp preserves evidence of the interaction of magmatic fluid and groundwater the fwgp comprises veins dikes and irregular bodies of a quartz alkali feldspar plagioclase intergrowth that are most abundant near footwall style cu ni platinum group element mineralization textures and cross cutting relations show that the emplacement of the fwgp created favourable sites for the later deposition of sulfides geochemical and physical evidence show that the fwgp did not form by in situ partial melting of the archean country rocks in the footwall beneath the sic it represents a mobilized injected silicate residue from either the contact between partially melted country rocks and the sic or from the crystallizing sic itself its bulk composition can be modeled as the product of fractional crystallization of a liquid with an initial composition equivalent to granophyric matrix trapped liquid in the lowermost units of the sic norite and sublayer primary fluid saline h 2 o poor and melt silicate h 2 o rich inclusions hosted in quartz from the fwgp have bulk and trace element compositions consistent with those hosted in quartz from the granophyric matrix of the lower units of the sic norite sublayer fluid inclusions contain mixtures of a high salinity 44 70 wt nacl equivalent n 39 na fe rich aqueous magmatic fluid and a lower salinity ca and sr rich groundwater the magmatic end member is thought to be an sic derived volatile phase estimates of the mixing proportions show that primary and secondary inclusions in the fwgp contain 60 100 and 30 80 of the magmatic end member by mass respectively fluids responsible for the remobilization of ore metals represent mixtures containing a much higher proportion of the groundwater end member not less than 70 by mass compared to the fluids trapped in the fwgp at considerable distance 400 m from the sic the chlorine isotope composition of biotite in the fwgp is enriched in 37 cl 37 cl 0 98 to 1 61 scapolite from the high temperature veins and the interstices of rock types in the main mass of the sic shows similar enrichment in 37 cl up to 1 34 whereas biotite from the archean country rocks 37 cl 0 88 to 0 53 and associated groundwater are 37 cl depleted the results of this study lead to two important conclusions concerning genetic and exploration models for the footwall ore zones first magmatic end member fluid introduced into the footwall with the melt from which the fwgp crystallized contained very little cu rarely 100 ppm the main ore metal in the footwall ores this result questions hydrothermal models for footwall ore formation that hypothesize that cu and other ore metals were remobilized from sulfide deposits along the sic contact by magmatic hydrothermal fluids and redeposited in the footwall it is more likely that ore metals were only locally remobilized in the footwall ore zones when metal poor hybrid fluids interacted with pre existing sulfide veins of magmatic origin second inclusions containing the hybrid fluid occur in the fwgp rock type throughout the footwall in both mineralized and unmineralized areas therefore although the fwgp preserves stable cl isotope and fluid inclusion evidence that magmatic fluid was introduced into the footwall detection of this magmatic component alone will not serve as a useful exploration method in contrast mapping the distribution and abundance of fwgp may be ore predictive since fwgp emplacement and its higher abundance in mineralized areas appears to have been a structural and textural prerequisite for footwall ore emplacement

the dykes and structural setting of the volcanic front in the lesser antilles island arc the orientations of dykes from many of the islands of the lesser antilles island arc have been mapped most of these dykes can be interpreted in terms of local or regional swarms derived from specific volcanoes of known age with distinct preferred orientations dykes are known from all cenozoic epochs except the palaeocene but are most common in pliocene miocene and oligocene rocks a majority of the sampled dykes are basaltic intrude volcaniclastic host rocks and show a preference for widths of 1 1 25 m locally dyke swarms dilate their hosts by up to 9 over hundreds of metres and up to 2 over distances of kilometres the azimuths of dykes of all ages show a general ne sw preferred orientation with a second nw se mode particularly in the miocene rocks of martinique the regional setting for these minor intrusions is a volcanic front above a subduction zone composed of three segments saba montserrat guadeloupe martinique st lucia grenada the spacing of volcanic centres along this front is interpreted in terms of rising plumes of basaltic magma spaced about 30 km apart this magma is normally intercepted at crustal depths by dioritic plutons and andesitic dacitic magma generated there plumes which intersect transverse fracture systems or which migrate along the front can avoid these crustal traps throughout its history the volcanic front as a whole has migrated episodically towards the backarc at an average velocity of about 1 km ma the local direction of plate convergence is negatively correlated with the local preferred orientation of dykes the dominant ne sw azimuth mode corresponds closely to the direction of faulting in the sedimentary cover of the backarc and the inferred tectonic fabric of the oceanic crust on which the arc is founded a generalised model of the regional stress field that controls dyke intrusion outside of the immediate vicinity of central volcanic vents is proposed in which the maximum horizontal stress parallels the volcanic front except in the northern segment where subduction of the barracuda rise perturbs the stress field there is also evidence of specific temporal changes in the stress field that are probably due to large scale plate kinematics

numerical model to determine the composition of h2o nacl cacl2 fluid inclusions based on microthermometric and microanalytical data natural fluids approximated by the h2o nacl cacl2 system are common in a wide range of geologic environments including sedimentary basins associated with hydrocarbon occurrences and mvt deposits submarine hydrothermal systems and other metamorphic magmatic and hydrothermal environments we present a comprehensive numerical model and microsoft excel based computer program to determine the compositions of fluid inclusions in the h2o nacl cacl2 system based on microthermometric and microanalytical data the model consists of six polynomial correlation equations that describe liquid salinity as a function of nacl cacl2 ratio and melting temperature on each of the ice hydrohalite halite antarcticite cacl2 4h2o and cacl2 2h2o vapor saturated liquidus surfaces the cotectic and peritectic boundaries are determined from the intersections of the liquidus surfaces the model is implicitly internally consistent and topologically correct the model expands upon the compositional range of applicability and the data types that can be used for compositional determination it reproduces experimental data for all compositions that lie within the h2o nacl cacl2 4h2o compositional triangle in the h2o nacl cacl2 system and yields accurate reproductions of the h2o nacl and h2o cacl2 binaries furthermore in comparison to previously published models the one presented here eliminates systematic errors wavy isotherms and cotectic and peritectic curves with local bumps

footwall type cu ni pge mineralization in the broken hammer area wisner township north range sudbury structure footwall type cu ni pge platinum group element deposits are a major focus of recent exploration in the sudbury mining camp owing to their higher cu and precious metal contents compared to orebodies situated along the lower contact of the sudbury igneous complex the most important footwall type orebodies occur in the onaping levack area of the north range but economic deposits are found along the east range of the structure as well recently promising occurrences were also discovered in wisner township of the north range in this paper we report results from two main footwall type cu ni pge occurrences the broken hammer zone and the south zone of wisner township both discoveries are situated in intensely brecciated zones of the footwall sudbury breccia 1 300 and 500 m respectively north of the present sudbury igneous complex footwall contact the mineralization consists of 1 massive sulfide veins 2 disseminated replacement sulfides and 3 silicate quartz dominated veins although massive sulfide veins account for the major part of the resource sulfide poor disseminations may have similarly high precious metal contents ore assemblages are dominated by chalcopyrite millerite magnetite and or pyrite quartz and hydrous silicates these are accompanied by platinum group minerals pgm and other trace minerals which commonly occur as composite grains within sulfides and hydrous silicates these include minerals typical of footwall type deposits e g merenskyite michenerite hessite but also minerals found only in a few sudbury deposits e g clausthalite sopcheite naumannite bohdanowiczite an unnamed cupdbis 3 mineral is one of the most abundant pgm at broken hammer and might be a pd equivalent of muckeite cunibis 3 statistical investigation of metal distribution patterns using grab sample and drilling data sets from both localities indicate important differences between the two occurrences and the various mineralization styles e g increasing cu cu ni and decreasing pt pt pd ratio with increasing sulfide content metal concentrations recalculated to 100 sulfides decrease by up to two orders of magnitude for all metals from the disseminated to the massive sulfides fluid inclusion studies revealed three fluid generations which are very similar to those described from well known footwall type deposits of the onaping levack area primary polyphase fluid inclusions in cu ni pge bearing assemblages represent a highly saline 30 40 wt nacl equiv magmatic hydrothermal system with a high temperature min 450 500 c and a lower temperature min 300 350 c stage a later low temperature ca rich fluid min 100 200 c is most probably part of a post sudbury igneous complex regional fluid flow in which temperature was controlled by the geothermal gradient and not related to ore forming processes the fluid inclusion data indicate that mobilization of highly saline and relatively high temperature 400 500 c sudbury igneous complex related magmatic hydrothermal fluids similar to those described from the onaping levack embayment also occurred in the wisner footwall although our studies do not rule out the possibility of an initial magmatic sulfide melt emplacement they prove that magmatic hydrothermal fluids played a significant role in the transport and deposition of metals

hydrothermal jarosite and hematite in a pyroxene hosted melt inclusion in martian meteorite miller range mil 03346 implications for magmatic hydrothermal fluids on mars low temperature aqueous processes have been implicated in the generation of jarosite and hematite on the martian surface but little is known regarding the role that high temperature magmatic fluids may have played in producing similar assemblages on mars we have identified jarosite and hematite in a clinopyroxene hosted melt inclusion in martian meteorite mil 03346 that shows evidence of having been hydrothermally precipitated in addition to jarosite and hematite the melt inclusion contains titanomagnetite pyrrhotite potassic chlorohastingsite an iron rich silicate glass and possibly goethite these phases were identified and characterized using scanning electron microscopy sem con focal raman spectroscopy and electron probe microanalysis epma based on observed textural relationships and the compositions of the hosted phases we report that the jarosite bearing melt inclusion in mil 03346 has recorded a fluid rich history that began in the magmatic stage and continued to low temperatures this history begins at entrapment of a volatile rich silicate melt that likely reached fluid saturation after only minor crystallization within the melt inclusion this fluid rich in chlorine reacted with surrounding silicate material to produce the potassicchlorohastingsite as cooling proceeded the liquid phase eventually became more oxidized and reacted with the pyrrhotite sulfide oxidation resulted in so4 2 formation and concomitant acid production setting the stage for jarosite formation once the fluid cooled beyond the upper thermal stability of jarosite 200 c as the fluid cooled below 200 c jarosite continued to precipitate with hematite and or goethite until equilibrium was established or reactions became kinetically unfavorable this work suggests an additional jarosite hematite formation pathway on mars one that may be important wherever magmatic hydrothermal fluids come into contact with primary sulfide grains at the martian surface or subsurface moreover hydrothermal fluids rich in chlorine sulfur and iron are important for ore forming processes on earth and their indirect identification on mars may have important implications for ore formation on mars

preliminary evaluation of trace hydrocarbon speciation and abundance as an exploration tool for footwall style sulfide ores associated with the sudbury igneous complex ontario canada deposits of cu ni platinum group elements pge rich sulfides occur along the north range footwall of the sudbury igneous complex ontario canada the deposits have been modified chemically mineralogically and texturally by multiple syn to postmagmatic hydrothermal events and are hosted mainly within sudbury breccia a contact metamorphosed and hydrothermally altered impact breccia the composition of c1 to c6 unsaturated and saturated hydrocarbons in bulk fluid inclusion volatiles in the matrix of the sudbury breccia was investigated using in line rock crushing gas chromatography gc in order to compare the hydrocarbon composition of this rock type in breccia zones containing economic footwall sulfide deposits at the morrison deposit levack mine north range sudbury ontario with barren breccia zones trace hydrocarbons possibly abiogenic in origin occur throughout the sudbury igneous complex footwall and country rocks investigated however there are differences in the composition and abundance of bulk hydrocarbons released from mineralized and barren sudbury breccia when fluid inclusions are opened volatiles released from samples of sudbury breccia from sulfide mineralized and sulfide barren environments showed the following 1 higher average abundances of light saturated hydrocarbons c1 c4 and an approximately 2 higher total abundance of hydrocarbons mol g of rock basis associated with samples from the mineralized study area and 2 comparable average unsaturated hydrocarbon abundances in both settings but a larger range in unsaturated hydrocarbon abundances in the mineralized study area differences in bulk hydrocarbon abundance and composition reflect differences in the abundance and hydrocarbon content of fluid inclusions trapped in the barren and mineralized sudbury breccia zones in addition the compositional modification of circulating fluids by processes and conditions unique to the mineralized sudbury breccia environment may have occurred prior to inclusion entrapment e g modification by mineral catalysts differences in temperature and oxygen fugacity preliminary spatial analysis of the hydrocarbon distribution within and surrounding the morrison deposit shows that the total hydrocarbon abundance in the sudbury breccia does not change with orebody proximity within a single host breccia zone however volatiles trapped in the sudbury breccia matrix near the top of the footwall deposit where it is physically connected to contact style ni cu pge ores have elevated unsaturated hydrocarbon abundances e g propene compared to other parts of the same breccia zone distal to this zone of physical connection samples of the pge enriched sudbury breccia and mineralized veins containing alteration assemblages characteristic of the footwall ore styles have higher unsaturated hydrocarbon abundances and unsaturated saturated ratios compared to sudbury breccia and vein samples that are pge poor localized enrichments in unsaturated hydrocarbons in sudbury breccia zones may be the result of specific ore minerals and metal complexes involving the pge and group viii metals that acted as catalytic agents modifying the composition of initially light saturated hydrocarbon species prior to entrapment in fluid inclusions to apply the analysis of hydrocarbon compositions in trapped fluid inclusions to discriminating mineralized from barren zones of sudbury breccia samples from targeted areas were compared to samples of barren sudbury breccia background although a large data set is presented here to establish these compositional fields analysis of smaller sample subsets from each environment yields a statistically significant separation between the two environments total hydrocarbon abundance c3 c1 ratios and unsaturated saturated hydrocarbon ratios are useful indicators of sulfide ore proximity and may help delineate regions enriched in pge

textural morphological and compositional varieties of modern arc sulfides a case study of the tolbachik volcano kamchatka abstract magma unmixing into separate sulfide and silicate melts is a key process in the formation of magmatic sulfide ore deposits sulfide inclusions in olivine preserve the original chemical composition of the segregated sulfide melt whereas the phase compositions of the solidified sulfide droplets and their textures record the final stages of sulfide evolution sulfide globules hosted in olivine phenocrysts of magnesian basalts from the tolbachik volcano kamchatka display a variety of textures ranging from homogeneous to fine grained to coarse grained and lamellar porous textures and textures associated with the oxidation and dissolution of sulfides were identified as separate categories the outer surfaces of sulfides vary significantly in shape which includes normal spherical or elliptical globules gravitationally layered inclusions thin sulfide foils and concave deformed sulfides in contact with fluid bubbles the estimated cooling rate of olivine phenocrysts responsible for observed crystallization textures varies by five orders of magnitude the fe ni cu ratio also exerts an influence on the resulting texture whereas the size of the globules does not have any significant effect the morphology and textural patterns of individual grains indicates that fine grained textures resulted from the rapid breakdown of a homogeneous solid phase which the sulfide melt solidified into during extremely rapid quenching the presence of large or abundant small pores in sulfides along with channels at the globule periphery indicates the separation of an appreciable amount of dissolved fluid from the sulfide melt during crystallization sulfides in the form of thin foils and planar swarms in healed cracks indicate cyclic pressure changes in the olivine environment which resulted in phenocrysts rupturing and healing the sulfide mineralogy is represented by high temperature sulfides mss monosulfide solid solution and iss intermediate solid solution as well as pyrrhotite pentlandite chalcopyrite cubanite bornite magnetite assemblages which formed at lower temperatures

the significance of partial melting processes in hydrothermal low sulfide cu ni pge mineralization within the footwall of the sudbury igneous complex ontario canada we present new results and review existing data highlighting different aspects of the genetic relationship between partial melting and hydrothermal mineralizing processes in the contact aureole of the sudbury igneous complex at the basal contact of the igneous complex in the footwall breccia crystallized partial melt pods and veins referred to as footwall granophyres are abundant and intrude all rock types including the breccia matrix as well as massive ni cu sulfide ore the final crystallization of these melts was accompanied by the segregation of high salinity fluids dominantly in the temperature range of 450 to 550 c as revealed by ti inquartz thermometry and studies on primary fluid inclusions in mineralized parts of the footwall breccia there is clear evidence that interaction of partial melts exsolved fluids and preexisting magmatic sulfides occurred in the deeper footwall of the sudbury igneous complex similar footwall granophyres occur as networks of veins intruding impact brecciated sudbury breccia country rocks and have an intimate spatial association with hydrothermal low sulfide assemblages highly enriched in pt pd and au with a unique assemblage of pgm including malyshevite and lisiguangite it is suggested that partial melting processes were widespread in the contact and proximal footwall environment of the igneous complex and they were important in providing high salinity magmatic fluids to a hydrothermal system responsible for redistribution of base and precious metals we describe observations which may evidence the migration of partial melts from the contact into the deeper footwall furthermore we suggest a cogenetic model for the precipitation of sulfide hydrous silicate assemblages in close spatial association to footwall granophyres we emphasize that the use of footwall granophyres in mineral exploration for cu ni pge ores in the footwall of the sudbury igneous complex is clearly justified mapping of footwall granophyre vein networks highlights areas that were proximal to the contact environment and point out structural pathways that may have been used by syn or postgenetic mineralizing fluids in a given area widespread partial melting appears to have occurred in the footwall of other large mafic ultramafic complexes such as bushveld and duluth and similar genetic relationships of partial melting and ore forming hydrothermal processes may have possibly existed also in these systems

a textural mineralogical and statistical study of the footwall breccia within the strathcona embayment of the sudbury structure the footwall breccia is one of the main ni cu pge ore hosting units of the sudbury camp this polymict matrix supported contact metamorphosed breccia occurs between the sudbury igneous complex and the footwall rocks along the west north and east margins of the sudbury structure in areas where there are depressions or embayments in the footwall the footwall breccia and basal units of the sudbury igneous complex are thickened and the footwall breccia is variably mineralized mineralogical and textural variations of footwall breccia samples from the strathcona embayment in proximity to the fraser mine suggest that the mineralogy and texture of this unit vary as a function of proximity to the sudbury igneous complex proximity to ore and location within the embayment the most mafic footwall breccia mineralogy is present proximal to the base of the sudbury igneous complex within a transition zone the presence of relatively mafic hydrous and cl rich silicate minerals e g biotite and amphibole characterize the footwall breccia matrix around ore zones and form an alteration halo of up to 5 m thick textural variations include a coarsening of quartz and feldspar grains with increasing proximity to the sudbury igneous complex contact textural coarsening also occurs from the margins of the strathcona embayment to the center together these mineralogical and textural variations influence the color of the footwall breccia matrix and can explain some of the gray colors that are typical of mineralized footwall breccia these variations also constrain the timing of formation of this unit and suggest that at least three phases of footwall breccia exist

multi stage hydrothermal processes involved in low sulfide cu ni pge mineralization in the footwall of the sudbury igneous complex canada amy lake pge zone east range the amy lake pge zone is a low sulfide type cu ni pge mineralization in the east range footwall of the 1 85 ga sudbury igneous complex occurring in a 100 m wide sudbury breccia belt that coincides with an impact related major fracture zone bay fault zone detailed hydrothermal alteration mapping fluid inclusion trace element and stable isotope studies revealed a complex alteration and mineralization history in a multi source multi stage sudbury related hydrothermal system the two major stages of syn sudbury hydrothermal activity are characterized by similarly high salinity high temperature fluids that are 1 locally derived from footwall granophyre bodies and typified with high ni cu and pge s ratios and high ree contents magmatic hydrothermal stage and 2 a more voluminous cu ni pge rich fluid flux probably originated from the sudbury igneous complex footwall contact hydrothermal stage the second hydrothermal flux was introduced by brittle fractures in the area and resulted in a complex zonation of alteration assemblages and mineralization governed by local footwall composition the sudbury related hydrothermal event was overprinted by shear related epidote veining and calcite chlorite replacement both regionally present in the sudbury structure based on analogies the most important factors involved in the formation of hydrothermal low sulfide mineralization are proposed to be 1 accumulation of pge enriched fluids 2 large scale brittle structures as conduits to these fluids and 3 adequate host rock composition as a chemical trap resulting in sulfide and pgm precipitation in environments meeting these criteria hydrothermal pge mineralization is known to have formed not only in the sudbury footwall but also from mafic ultramafic intrusions associated with primary magmatic pge from several locations around the world

emplacement of sharp walled sulfide veins during the formation and reactivation of impact related structures at the broken hammer mine sudbury ontario broken hammer is a hybrid cu ni platinum group element pge footwall deposit located in archean basement rocks below the impact induced sudbury igneous complex sic canada the deposit consists

high chlorine alteration minerals and calcium rich brines in fluid inclusions from the strathcona deep copper zone sudbury ontario the strathcona deep copper zone consists of a complex suite of massive sulfide veins that occupy a series of fractures in the footwall gneisses and sudbury breccia it is characterized by the occurrence of branching quartz veinlets and hydrothermal alteration selvages along the margins of massive sulfide veins hornblende or actinolite epidote calcite and ferropyrosmalite fe mn 8 si 6 o 15 oh c1 10 occur in the inner zones of the alteration selvages adjacent to the massive sulfide veins annite chlorite and albite are developed in the outer zones fe rich silicates of the alteration assemblages contain significant amounts of chlorine ferropyrosmalite contains 5 79 to 6 54 wt percent cl hornblende contains up to 2 99 wt percent cl annite contains up to 2 13 wt percent cl primary fluid inclusions in the quartz from the branching veinlets are mutiphase consisting of vapor liquid and more than four solids the solid crystals of opened inclusions identified by scanning electron microscope are na ca k k pb k fe and fe mn chlorides the sequence of melting events and the nature of the solid phases suggest that the trapped fluids are nacl cacl 2 h 2 o solutions with minor k fe mn and pb these fluid inclusions are highly saline avg 60 wt nacl cacl 2 calcium rich ca na 1 by weight and homogenize to liquid at temperatures 260 degrees to 420 degrees c 342 degrees or 35 degrees c mean or std dev two options are proposed for the origin of the fluids melt fluid phase separation during sulfide liquid crystallization and convection of ambient fluids across the contact of the sulfide veins the cl rich fluids may have participated in the precipitation of pd and probably other platinum group elements pge at a later stage but they did not transport the pge very far from the magmatic sulfide veins

multiple hydrothermal processes in footwall units of the north range sudbury igneous complex canada and implications for the genesis of vein type cu ni pge deposits systematic regional sampling along the contact zone of the 1 85 ga age sudbury igneous complex with the archean levack gneiss footwall in the north range of the sudbury structure revealed textural mineralogical and fluid inclusion systematics of post sudbury igneous complex hydrothermal processes that affected the various lithologies at late stages of emplacement of the sudbury igneous complex and formation of magmatic fe ni cu sulfide deposits a partial melt from the levack gneiss invaded the contact zone this partial melt is revealed by small microdikes and irregular bodies of granophyric quartz plagioclase with megacrysts of hornblende clinopyroxene and titanite plagioclase hornblende equilibrium was established at 750 to 800 c and 1 10 to 1 55 kbars pressure corresponding to about a 4 to 6 km depth under lithostatic conditions f cl wt percent ratios around 15 for accessory apatite and hornblende indicate that a cl rich fluid phase separated during the crystallization of the footwall granophyre this is expressed as miarolites the cl rich fluid 50 wt nacl equiv salinity was trapped as primary fluid inclusions in quartz at around 480 c minimum temperature and around 1 1 kbars minimum pressure during supercooling these inclusions are rich in ca fe mn and k as well as na chloride this fluid may have interacted with earlier primary magmatic sulfide causing remobilization and reprecipitation of cu ni platinum group elements pge in veins and disseminations in the footwall these veins are parallel to the sudbury igneous complex footwall contact and are characterized by chalcopyrite pentlandite millerite magnetite stilpnomelane ferropyrosmalite epidote and chlorite michenerite moncheite merenskyite froodite insizwaite sobolevskite gold and bi ni sulfides are associated with sulfides epidote quartz actinolite and chlorite are common in the alteration selvages of the veins compositions and assemblages of platinum group minerals pgm indicate their precipitation below 575 to 485 c primary highly saline fluid inclusions about 40 wt nacl equiv in quartz indicate crystallization at 400 to 480 c and around 1 6 kbars minimum t and p respectively late carbonate epidote actinolite chlorite veins and alteration overprinted the earlier assemblages at about 300 to 400 c with some bornite millerite native silver and other bi sulfides the second stage of hydrothermal activity is characterized by regional carbonic aqueous nacl co 2 ch 4 h 2 o type immiscible fluids that were trapped as secondary inclusions in quartz from various lithologies no mineralization is related to this stage along the north range boiling of these fluids took place during a pressure drop from lithostatic to hydrostatic conditions during uplift from about a 5 to 6 to a 3 to 4 km depth at 300 to 350 c high 20 26 wt nacl equiv and low salinity 6 12 wt nacl equiv fluids coexisted with different carbonic species contents the predominant north south and northwest southeast orientations of fluid inclusion planes reveal that mobilization of carbonic aqueous solutions may be related to the northwesterly oriented thrusting in the sudbury structure during the late stages 1 8 1 7 ga of the penokean orogeny and to predominantly north south faulting in the north range the third stage of fluid mobilization also took place mostly along northerly and northwesterly oriented fractures aqueous fluids were ca rich brines 20 40 wt salinity with temperatures between 150 and 250 c some of these fluids also circulated in fractures parallel to the sudbury igneous complex footwall contact ne sw thus they locally may have interacted with the earlier sulfide assemblages and are also responsible for formation of late veinlets with chalcopyrite epidote quartz chlorite assemblages mobilization of these fluids took place under litho and hydrostatic conditions at about a 4 to 6 km depth this hydrothermal activity is related to a regional tectonothermal event during emplacement of northwesterly oriented sudbury dikes 1 24 ga regional scale fluid inclusion studies along the north range highlight the role of multiple hydrothermal processes in the metallogenic evolution of the sudbury igneous complex and especially in the distribution of copper and precious metals in the footwall units

the trace metal content of amphibole as a proximity indicator for cu ni pge mineralization in the footwall of the sudbury igneous complex ontario canada alteration veins containing cl poor actinolite and actinolitic hornblende are a common feature throughout the archean aged gneisses and granitoids along the northern margin of the sudbury igneous complex ontario canada crosscutting relations and structural measurements show that the veins postdate the sudbury impact event but predate the emplacement of footwall style cu ni pge platinum group element sulfide ores the veins are four to five times more abundant in brecciated mineralized outcrop than in unbrecciated barren outcrop analyses of vein hosted amphibole by electron microprobe emp and laser ablation icp ms la icp ms show elevated concentrations of ni up to 100 times background increasing from 100 ppm to 1 0 wt cu up to 4 times background and sn up to 2 5 times background in proximity to sulfide veins copper and sn contents in amphibole are only anomalous within 10 to 20 m of mineralization and require quantification by la icp ms however anomalous ni concentrations in vein hosted amphibole may be detected with a high level of confidence solely by emp up to 700 m from mineralization in rocks that contain no visible sulfides in hand sample or thin section and show no bulk rock ni or cu anomalies the relationship between the ni content in amphibole in ppm and mineralization proximity distance d in meters is given by the following equation batchmode documentclass fleqn 10pt legalpaper article usepackage amssymb usepackage amsfonts usepackage amsmath pagestyle empty begin document ni amp 5100 d 0 45 end document the data indicate wide scale ni mobility in hydrothermal solutions in the sudbury footwall the formation of ni rich amphibole in the fracture networks by either the growth of primary ni rich amphibole or metasomatic ni enrichment of preexisting ni poor amphibole was associated with circulation of a sodium and halogen rich fluid between 390o and 550oc nickel may have been released into the footwall environment by extensive hydrothermal alteration of ni rich contact style sulfide ores that lie in the hanging wall of the cu rich footwall style ores in the footwall rocks pre existing fracture networks now amphibole bearing veins acted as common structural pathways first for the circulation of early ni rich fluids associated with leaching in the contact region and the onset of footwall mineralization and second for the emplacement of cu rich footwall style sulfide veins other metal concentrations in amphibole pb zn co show no relationship to mineralization proximity these metals may have been derived locally from country rocks during alteration reactions that promoted amphibole growth in the fractures identification of fracture hosted amphibole with anomalous ni contents in thin section or ni cu sn anomalous amphibole grains liberated from surface weathered rocks hosting sulfide veins may serve as useful proximity indicators for hidden footwall style sulfide deposits at sudbury

the distribution of base metals and platinum group elements in magnetititeand its host rocks in the rio jacare intrusion northeastern brazil anomalously high pt and pd values have been found in three magnetite bodiesin the rio jacare intrusion of northeastern brazil the intrusion hosting thesemagnetite bodies consists predominantly of pyroxenite and gabbro one magnetitebody occurs in the lower zone and two in the upper zone of the intrusion thesebodies contain approximately 0 04 percent ni 0 1 percent cu 0 18 percent s 1ppb ir 3 ppb rh 160 ppb pt 120 ppb pd and 37 ppb au they are much richer inplatinum group elements pge than the surrounding silicate rocks and there aresignificant correlations among all of the pge and between pge and ni howeverthe correlations between pge and au cu and s are much weaker than correlationsbetween au cu and s in the magnetite bodies palladium rich minerals especially bismuthides andantimonides are the most abundant platinum group minerals pgm in most casesthese occur with interstitial silicates or within silicate inclusions inmagnetite and ilmenite grains and are associated with co bearing pentlandite andin a few cases with co ni sulfarsenides and arsenides sperrylite ptas2 is the most abundant pt mineral and is associated with silicates interstitial tomagnetite and ilmenite grains and sometimes with co ni arsenides at sites wherethe igneous mafic minerals have been altered to amphiboles sperrylite may bealtered to pt fe alloys other alloys present include pd sn cu pt cu pt ni and pt au it is suggested that ni and pge were concentrated in the magnetite bodies bythe coprecipitation of a small quantity of sulfide with the magnetite these pge bearingbase metal sulfides subsequently exsolved pgm the association of pd mineralswith base metal sulfides and the small variation in the pt pd ratio ca 1 4 suggests that the pge have not been extensively remobilized in the magnetitite in contrast the strong correlation between s cu and au suggests that inaddition to the redistribution of s it is likely that cu and au wereremobilized it is not possible to say whether the redistribution of sulfur wasdue to late magmatic fluids dissolving s or the later metamorphic events the association of pge enrichment with magnetite layers in the rio jacareintrusion contrasts with that of the bushveld stillwater great dyke and munnimunni complexes in these complexes pge enriched layers or reefs are found inthe lower third of the complexes and the oxide associated with the reefs ischromite magnetite bearing layers which form from an evolved magma in theupper parts of the intrusions are generally barren of pge because at the timeof magnetite crystallization the pge had already precipitated either insulfides or pgm however in a number of intrusions e g rincon del tigre skaergaard stella and rio jacare the upper magnetite bearing portion of theintrusion shows pge enrichment this enrichment is rarely associated withvisible sulfides but suggests a possible new target for pge exploration

chlorine and alkali geochemical halos in the footwall breccia and sublayer norite at the margin of the strathcona embayment sudbury structure ontario the ni cu platinum group element ores in the sublayer and footwall breccia of the sudbury structure have distinctive geochemical halos in the fraser mine f cl ratios of the sublayer rocks appear to decrease na2o k2o ratios of the footwall breccia samples decrease and cl in both units increases with proximity to mineralization these halos are interpreted to result from interaction of residual magmatic fluids with host rocks which altered the host rock mineralogy and precipitated cl bearing minerals the results of this study together with the results of previous studies suggest that most ores at sudbury including sublayer and footwall breccia hosted contact ores and sudbury breccia hosted footwall ores are surrounded by cl and possibly alkali halos and that these geochemical signatures may be used to identify rocks that are proximal to mineralization

fluid sources and hydrothermal architecture of the sudbury structure constraints from femtosecond la mc icp ms sr isotopic analysis of hydrothermal epidote and calcite abstract this study presents new sr isotopic data on hydrothermal mineral assemblages from different stratigraphic levels within the sudbury impact structure determined using femtosecond la mc icp ms these data provide new insights into the origin of the hydrothermal fluids that have circulated through and around the sudbury igneous complex sic and further define the overall hydrothermal architecture of the structure early blocky miarolitic epidote from the sic has a narrow range of initial 87 sr 86 sr 0 70710 to 0 70742 similar to the sic 0 70648 to 0 70736 that is consistent with the precipitation from orthomagmatic fluids derived from the sic the 87 sr 86 sr values of later replacement miarolitic and vein epidote from different stratigraphic levels of the sic and of replacement and amygdule epidote from the overlying onaping formation are distinctly higher up to 0 71753 than those of the blocky miarolitic epidote these data suggest that the fluids responsible for this late epidote were not derived from the sic and more likely represent basement derived fluids that passed through the sic and onaping formation the sr isotopic composition of syngenetic laminated calcite in the post impact vermillion formation suggests precipitation from proterozoic seawater 87 sr 86 sr 0 70295 whereas some vermilion formation related syngenetic laminated calcite and epigenetic discordant and replacement mineralized calcite with more radiogenic values suggest precipitation from seawater modified through interaction with the vitric and lithic fragments present in the onaping formation the formation of some replacement and amygdule carbonate in the onaping formation also involved mixing between seawater and basement derived fluids of similar chemical and isotopic composition to those responsible for the replacement epidote hosted by the sic and onaping formation the sr isotopic composition of hydrothermal epidote from throughout the sudbury structure indicates a fluid connection between the footwall and hanging wall of the sudbury igneous complex

deriving terrain factors from high resolution lunar images a case study of the mons rumker region abstract mons rumker is a preferred candidate landing region for china s chang e 5 ce 5 mission from where it is of great significance to select safe landing areas lunar terrain factors from digital elevation model dem data limited by their low resolutions 10 m pixel are inapplicable to evaluating the lunar landing area safety in spite of the fact that lunar remote sensing imagery has higher resolution 50 cm pixel in this paper we extracted terrain factors in divided square girds by the aid of the high resolution lunar reconnaissance orbiter lro narrow angle camera nac images namely flat area percentage fap distribution pattern of uneven objects nni based on the double threshold otsu method and roughness based on gray level histogram analysis mons rumker can be divided into four geological units named as ld b1 b2 and b3 respectively unit b1 has a higher roughness and a lower fap unit b2 and b3 are characterized with the highest fap and the lowest roughness nnis of unit b1 b2 and b3 are 1 while ld s is

fluid inclusion characteristics of hydrothermal cu ni pge veins in granitic and metavolcanic rocks at the contact of the little stobie deposit sudbury canada abstract cu and precious metal enriched massive ore and veins occur at contacts of two fe ni cu sulfide orebodies of the little stobie mine sudbury with metavolcanic rocks of the elsie mountain formation and the murray granite veins contain chalcopyrite pyrrhotite pentlandite platinum group minerals quartz carbonate chlorite amphibole and other minerals a granitic dike resulting from partial re melting of the murray granite cuts back into the sudbury igneous complex near little stobie mine and contains barren veinlets with similar mineralogy but no sulfides quartz from ore veins contains fluid inclusions that were trapped during several stages early high temperature fluids at least 180 270 c in orebody 1 and 280 350 c in orebody 2 were extremely saline and occur as polyphase isolated and fracture controlled inclusions with halite sylvite fe mn as well as pb ba chloride daughter minerals and other unknown solids late secondary aqueous inclusions are not chloride saturated they were trapped at a minimum of 80 150 c their microthermometric behavior may be modeled in the cacl 2 nacl h 2 o system with salinity of 21 27 cacl 2 equiv wt very late secondary inclusions have either ca rich saline or very dilute about 1 equiv wt nacl compositions and homogenization temperatures of 200 300 c with the exception of these very late secondary inclusions the association of co 2 ch 4 rich inclusions with aqueous ones was usually observed the density of these carbonic fluids decreased from early to late stages microthermometric data from barren veins are fundamentally different from those of early inclusions from orebodies this implies that these heavy metal rich fluids were responsible for ore deposition in veins the minimum pressure of entrapment for early fluids was 1800 2200 bars late ca rich brines were trapped at lower minimum pressure 200 900 bars high pressure data are in agreement with the estimated minimum paleodepth of crystallization of south range ores later fluids were probably trapped during the uplift of orebodies and their host rocks comparison of data to other cu pge au rich ore of the sudbury structure suggests that the presence of co 2 rich fluids in south range deposits and their absence in north range deposits may be related to different metamorphic histories the high temperature hydrothermal fluids were driven by the heat of the sudbury igneous complex these very saline fluids interacted with primary magmatic ores remobilized metals and redeposited them along convenient structures such as fracture zones and breccias in and along various units near the footwall contact the identification of such highly saline fluid inclusions with high heavy metal content may be useful in the exploration for cu pge au enriched footwall vein type ores in the sudbury structure

petrology and crystallization history of multiphase sulfide droplets in a mafic dike from uruguay implications for the origin of cu ni pge sulfide deposits sulfide blebs in a mafic dike belonging to the uruguayan dike swarm replicate at a small scale many features observed in larger platinum group element enriched nickel copper sulfide deposits such as in sudbury and noril sk these blebs formed by the crystallization of droplets of immiscible sulfide liquid form 1 cm sized ovoid geopetal structures with pyrrhotite and pentlandite at the base chalcopyrite and cubanite at the top and titaniferous magnetite at the margins magnetite crystallized first followed by nickel and iron rich monosulfide solid solution which sank to the bottom of the droplets and from which pyrrhotite and pentlandite subsequently exsolved the remaining copper rich liquid in the upper part of the droplets crystallized to form an intermediate solid solution from which chalcopyrite and cubanite subsequently exsolved the final extremely evolved cu fe s rich pd sn pb mo ag bi te and sb bearing liquid crystallized as 10 to 20 sized veinlets filling fractures in the magnetite and adjacent silicate minerals the veinlets crossing the magnetite often terminate in 100 m sized subrounded globules at the contact of the magnetite and the surrounding silicate minerals indicating a direction of veinlet filling away from the center of the blebs textural evidence in the blebs illustrates that as crystallization proceeded and the immiscible sulfide liquid droplets within the dike sank a distance of less than 1 mm relative to the adjacent silicate onto already partially crystallized silicate minerals the sulfide liquid surrounded and resorbed the already solid magnetite grains at the top of the blebs magnetite grains were isolated above the sulfide liquid and partially surrounded by quartz plagioclase and amphibole an assemblage representing a late stage magma that had been drawn into the space created above the droplets as they sank and which is more evolved than that of the surrounding host dike the location of the blebs within the dike isolated from influences external to the dike indicates both that the fracture filling by evolved immiscible cu rich sulfide liquid is related to crystallization processes rather than later tectonic events and that the bismuth tellurium and antimony have a late magmatic origin associated with crystallization of the immiscible sulfide liquid

hydrous sulfide melting experimental evidence for the solubility of h2oin sulfide melts the effect of h 2 o on sulfide melting temperatures has been investigated in the fes pbs zns system at 1 5 gpa revealing that the addition of h 2 o results in a 35 c drop in melting temperature from 900 to 865 c in addition to the melting point depression the solubility of h 2 o is confirmed by the presence of vesicles in the quenched melt no oxide phases were present in any of the run products ruling out oxidation as a cause of the melting point depression confirmation of the solubility of h 2 o in sulfide melts is consistent with the recent suggestion by mungall and brenan 2003 of a magmatic origin for halogen rich alteration associated with magmatic sulfide ore deposits as the hydrous component of the alteration may similarly originate in the fractionating sulfide melt anatectic sulfide melts could be expected to contain more h 2 o than magmatic sulfide melts owing to the lack of a parental silicate melt that buffers the h 2 o content of magmatic sulfide melts fluids expelled from the cooling anatectic melts such as that present during granulite facies metamorphism of sulfide deposits at broken hill australia may have been responsible for associated retrograde hydrothermal alteration

retrograde mineral reactions in saline fluid inclusions the transformation ferropyrosmalite clinopyroxene evidence is presented for retrograde reaction of silicate minerals with saline brine inside fluid inclusions during post entrapment cooling ferropyrosmalite fe mn 8si6o15 oh cl 10 where fe mn has previously been interpreted as a daughter mineral in saline inclusions in magmatic quartz from altered granodiorite associated with the vyhne klokoc fe skarn deposit of slovakia based on combined raman spectroscopic microthermometric and sem edx techniques this phase is shown to react on heating above 450 c with a ca enriched saline inclusion fluid to form clinopyroxene this suggests that clinopyroxene was originally present in the inclusions at high temperature and then underwent retrograde reaction with the saline fluid on cooling to form ferropyrosmalite in its simplest form the equilibrium reaction for this transformation is formula 1 in practice the reaction is complicated by the presence of mn and mg the resulting daughter mineral assemblage observed at room temperature is actually a low temperature equilibrium assemblage very different to that originally present at high temperature although silicate daughter minerals such as clinopyroxene are rarely if ever described in fluid inclusions they may have originally been present but underwent similar retrograde reactions ferropyrosmalite itself is likely to be frequently overlooked as in the absence of raman spectroscopic analyses it may be mistaken for one of a range of possible hydrated iron chloride minerals improved raman spectra for ferropyrosmalite are presented which will make future identification easier failure to recognize intra inclusion retrograde reactions such as this may lead to misinterpretation of fluid inclusion chemistry including metal and silica solubilities 1 embed tex math 1 gif