origin of siderite veins in the western carpathians abstract siderite barite veins of the rud any ore field have precipitated from nacl cacl 2 h 2 o co 2 solutions with cacl 2 weight fractions between 0 05 and 0 38 total salinities between 17 and 35 wt and up to 1 8 mol co 2 homogeneous and heterogeneous trapping modes have been distinguished according to volumetric phase ratios of the fluid inclusions which have been trapped at 175 205 c in veiny siderite at 200 230 c in siderite and quartz from drusy cavities and at 90 180 c in the siderite postdating quartz sulfidic assemblage a sequential re equilibration technique has been developed to locate precisely vapour saturated halite liquidus of individual brine inclusions which normally homogenise by halite dissolution slopes of the vapour unsaturated halite liquidi constrained by isochores of coexisting two phase aqueous inclusions have been approximately three to five times steeper in natural polycomponent brines than those in the experimental nacl h 2 o system fluid pressures between 1 and 2 kbar have been determined using this method in drusy quartz associating with siderite crystals oxygen isotope variations 16 8 19 9 v smow in siderite result from a temperature increase from 175 to 230 c whereas nearly constant 13 c values 3 9 to 4 6 v pdb indicate absence of co 2 devolatilisation carbon isotope composition of the parental fluid changed from 9 5 to 8 8 v pdb while the oxygen isotope ratios remained essentially fixed at 7 7 0 3 v smov during formation of siderite the calculated 18 o fluid value is attributed to formation water enriched in 18 o during isotopic exchange with crustal rocks at low fluid rock ratios the 13 c fluid values probably correspond to a mixture of co 2 from dissolved matrix carbonates and that liberated by thermal decarboxylation of organic acids acetates which normally occur in formation waters leachate chemistry data have corroborated high concentrations of cacl 2 and mgcl 2 in the ore forming brines high br concentrations are similar to halite fractionated basinal brines ca 2 and k concentrations in excess of those in normal basinal brines reflect extensive cation exchange with surrounding low to medium grade metamorphites coincidental with calcite and k feldspar dissolution dolomitisation and albitisation of plagioclases high pressures of the siderite forming fluids 1 2 kbar must be linked with a deep circulation 4 8 km of the basinal brines derived primarily from marine water but significantly modified by interaction with low to medium grade paleozoic rocks at low fluid to rock ratios an anti clockwise crystallisation pt path inferred from fluid inclusion and stable isotope data is inconsistent with the siderite precipitation during extensional tectonic regime coincidental with permian triassic rifting suggested in previous models more likely the progressively increasing fluid pressures and temperatures could be attributed to compression and crustal thickening triggered by jurassic subduction in the meliatic hallstatt oceanic suture the superimposed quartz ankerite sulfidic ores have likely crystallised from brines expelled during compression associated with a continental collision during early to middle cretaceous times

ore genesis and hydrothermal evolution of the shaxi porphyry cu au deposit anhui province eastern china evidence from isotopes s sr h o pyrite and fluid inclusions the shaxi porphyry cu au deposit is located in the northern part of the luzong basin on the outer edge of the southern middle lower yangtze river metallogenic belt china it is typical of the porphyry cu au deposits in the metallogenic belt with more than 1 mt cu at 0 55 wt and 45 tons au at 0 47 g t hydrothermal alteration consists of a core of potassic alteration overprinted by a phyllic alteration zone propylitic alteration occurs peripheral to the potassic zone but can also be recognized in the core of the deposit where vein density is low the main mineralization occurs as sulfide veinlets in the potassic zone where it is superposed by phyllic alteration the paragenetic sequence show that chalcopyrite began to precipitate late in stage 1 associated with potassic alteration forming quartz sulfide veins with potassium feldspar halos and reached a peak in stage 3 forming chalcopyrite pyrite quartz anhydrite chlorite illite veins that accompanied phyllic alteration sulfur hydrogen oxygen and strontium isotopes fluid inclusions and pyrite trace element data indicate that the stage 1 assemblage associated with potassic alteration were deposited from a magmatic brine with the change from lithostatic to hydrostatic pressure late in stage 1 the brine generated stage 1 g quartz pyrite chalcopyrite anhydrite bornite molybdenite potassium feldspar veins with minor copper and gold mixing with minor external fluids meteoric water or gypsum saturated groundwater in stage 2 triggered the peripheral propylitic alteration as the proportion of external fluid increased with the onset of hydrostatic conditions it changed the redox state and composition of the hydrothermal system resulting in extensive stage 3 cu and au precipitation with phyllic alteration argillic alteration associated with stage 4 veins was generated by external fluids mixed with minor hydrothermal fluid at shallow depths

synthetic fluid inclusions xvii pvtx properties of high salinity h2o nacl solutions 30 wt nacl application to fluid inclusions that homogenize by halite disappearance from porphyry copper and other hydrothermal ore deposits fluid inclusions that homogenize by disappearance of the halite crystal after the vapor bubble has disappeared have been reported from a wide range of ore forming systems while this inclusion type is most commonly observed in porphyry copper and similar magmatichydrothermal ore deposits they have also been reported from iron oxide copper gold iocg mississippi valley type orogenic lode greenstone gold massive sulfide unconformity u and mantotype deposits as well as from non ore associated granitoids and oceanic crust the lack of experimental data to interpret microthermometric data from these inclusions combined with poor petrographic characterization of inclusion origin has led to a wide range of inferred pt trapping conditions for the inclusions the relationship between liquid vapor homogenization temperature thl v halite dissolution temperature tmhalite and pressure has been determined using synthetic h2o nacl fluid inclusions that homogenize by halite disappearance the experimental data cover the range thl v 150 to 500 c and tmhalite 275 to 550 c an empirical equation describing the relationship between pressure thl v and tmhalite has been developed to estimate formation pressures from microthermometric data and is valid from pressures along the liquid vapor halite curve to 300 mpa a detailed literature review reveals that the results of this study cannot be applied retroactively to estimate pressures of previously reported inclusions that homogenize by halite dissolution for several reasons first most workers have not collected and reported the data in a manner that allows one to determine if the inclusions have trapped a single homogeneous phase and have not leaked or changed volume following trapping thus it is not possible to determine if the inclusions show consistent microthermometric behavior within a group of coeval inclusions additionally many published studies provide only summaries of results from numerous samples or present the data graphically precluding application of our results to individual inclusions however based on our review it appears that much of the published data for inclusions that homogenize by halite dissolution represent inclusions that have either trapped a halite crystal along with the liquid or have reequilibrated by necking and or stretching results from this study have been used to estimate minimum formation pressures for inclusions from the ditrau alkaline massif transylvania romania the musoshi stratiform copper deposit zaire the bismark skarn deposit northern mexico the naica chimneymanto deposit mexico the questa porphyry molybdenum deposit new mexico and the bingham canyon porphyry cu mo deposit utah in each case pressures estimated using results from the present study are in good agreement with previous pressure estimates however in some cases estimated pressures both our estimates as well as those of other authors appear to be unreasonably high based on the geologic setting at the time of formation these results highlight the currently limited understanding concerning pressures depths of ore formation

genesis of the fuxing porphyry cu deposit in eastern tianshan china evidence from fluid inclusions and c h o s pb isotope systematics abstract the fuxing porphyry cu deposit is a recently discovered deposit in eastern tianshan xinjiang northwestern china the cu mineralization is associated with the fuxing plagiogranite porphyry and monzogranite mainly presenting as various types of hydrothermal veins or veinlets in alerted wall rocks with potassic chlorite phyllic and propylitic alteration developed the ore forming process can be divided into four stages stage i barren quartz veins stage ii quartz chalcopyrite pyrite veins stage iii quartz polymetallic sulfide veins and stage iv quartz calcite veins four types of fluid inclusions fis can be distinguished in the fuxing deposit including hypersline h type vapor rich two phase v type liquid rich two phase l type and trace amounts of pure vapor inclusions p type but only the stage i quartz contains all types of fis the stages ii and iii quartz have two types of fis with exception of h and p types in stage iv quartz minerals only the l type inclusions can be observed the fis in quartz of stages i ii iii and iv are mainly homogenized at temperatures of 357 518 c 255 393 c 234 322 c and 145 240 c with salinities of 1 9 11 6 wt nacl equiv 1 6 9 6 wt nacl equiv 1 4 7 7 wt nacl equiv and 0 9 3 7 wt nacl equiv respectively the ore forming fluids of the fuxing deposit are characterized by high temperature moderate salinity and relatively oxidized condition carbon hydrogen and oxygen isotopic compositions of quartz indicate that the ore forming fluids were gradually evolved from magmatic to meteoric in origin sulfur and lead isotopes suggest that the ore forming materials were derived from a deep seated magma source the cu mineralization in the fuxing deposit occurred at a depth of 1 km and the changes of oxygen fugacity decompression boiling and local mixing with meteoric water were most likely critical for the formation of the fuxing cu deposit

high salinity fluid inclusions in the yinshan polymetallic deposit from the le de metallogenic belt in jiangxi province china their origin and implications for ore genesis a fluid inclusion investigation of the polymetallic mineralization at yinshan from the le de metallogenic belt in jiangxi province of china has been carried out using petrographic and microthermometric techniques the data obtained here indicate that three major types of fluids were involved during the formation of the deposit they are type i vapor rich type ii liquid rich and type iii halite bearing inclusions within the h2o nacl system the high salinity fluids represented by type iii inclusions being unusual to the distal part of an intrusion centered ore forming system such as yinshan have been interpreted as the product of direct exsolution of a crystallizing magma rather than a result of fluid immiscibility from a low salinity fluid evidence used to support such an interpretation includes the mode of homogenization of type iii inclusions exclusively via halite dissolution spatial separation of type i and type iii inclusions on microscopic scale the consistent phase ratios within the inclusions concerned and considerable deviation in homogenization temperature for both type i and type iii inclusions trapping conditions for type i inclusions were estimated to be around 440 degrees c and 260 bars while type iii inclusions were constrained to be trapped at least above 900 bars and 500 degrees c the formation temperatures for type ii inclusions range from 270 to 390 degrees c if a lithostatic pressure of 260 bars is assumed pressure fluctuation determined by this fluid inclusion study coupled with decreases in salinity and temperature as result of the potential fluid mixing are supposed to have played an important role in triggering the precipitation of ore minerals from the hydrothermal solution c 2006 elsevier b v all rights reserved

fluid chemistry structural setting and emplacement history of the rosario cu mo porphyry and cu ag au epithermal veins collahuasi district northern chile the rosario cu mo ag deposit is located in the collahuasi district of northern chile it comprises high grade cu ag au epithermal veins superimposed on the core of a porphyry cu mo orebody rosario has mining reserves of 1 094 million metric tons mt at 1 03 percent copper an additional 1 022 mt at 0 93 percent copper occurs in the district at the nearby ujina and quebrada blanca porphyry deposits the rosario reserve contains over 95 percent hypogene ore whereas supergene sulfide ores dominate at ujina and quebrada blanca mineralized veins are hosted within lower permian volcanic and sedimentary rocks lower triassic granodiorite and late eocene porphyritic quartz monzonite the rosario fault system a series of moderate southwest dipping faults has localized high grade cu ag au veins at cerro la grande similar high grade cu ag au veins are hosted in north northeast trending sinistral wrench faults normal movement in the rosario fault system is interpreted to have been synchronous with sinistral strike slip deformation at la grande hydrothermal alteration at rosario is characterized by a k feldspar core focused in the rosario porphyry that grades out to a secondary biotite albite magnetite assemblage paragenetic relationships indicate that magnetite was the earliest formed alteration product but has been replaced by biotite albite vein crosscutting relationships indicate that k feldspar formed during and after biotite albite alteration chalcopyrite and bornite were deposited in quartz veins associated with both k feldspar and biotite albite assemblages the early hydrothermal fluid was a hypersaline brine 40 45 wt nacl that coexisted with vapor between 400 degrees and 600 degrees c weakly mineralized illite chlorite intermediate argillic alteration of the early k and na silicate assemblages was caused by moderate temperature 250 degrees 350 degrees c moderate salinity brines 10 15 wt nacl molybdenite was precipitated in quartz veins that formed between the potassic and intermediate argillic alteration events these fluids were 350 degrees to 400 degrees c with salinities between 10 and 15 wt percent nacl porphyry style ore and alteration minerals were overprinted by structurally controlled quartz alunite pyrite pyrophyllite dickite and muscovite quartz phyllic alteration assemblages the quartz alunite pyrite alteration formed at 300 degrees to 400 degrees c from fluids with a salinity of 10 wt percent nacl the pyrophyllite dickite assemblage formed between 250 degrees and 320 degrees c from dilute 5 wt nacl fluids an upward flared zone of muscovite quartz pyrite altered rocks surrounds the fault controlled domain of advanced argillic alteration thick veins 0 5 2 m wide of fault hosted massive pyrite chalcopyrite and bornite precipitated brines with a salinity of 30 wt percent nacl at temperatures of 250 degrees to 300 degrees c pressure depth estimates indicate that at least 1 km of rock was eroded at rosario between formation of the k na silicate and advanced argillic assemblages this erosion was rapid occurring over a period of 1 8 m y the rosario porphyry intruded immediately after the incaic tectonic phase implying that it was emplaced as the domeyko cordillera underwent gravitational collapse expressed as normal faults in the upper crust gravitational sliding potentially accelerated exhumation and helped to promote telescoping of the high sulfidation environment onto the rosario porphyry the hydrothermal system responsible for porphyry cu mineralization at rosario was partially exhumed prior to the formation of high sulfidation ore and alteration assemblages this implies that emplacement of a second blind intrusion occurred somewhere beneath the rosario and cerro la grande high sulfidation vein systems and is supported by the fault geometry and zoning of precious metals and sulfosalts at the district scale

a review of the intracontinental porphyry deposits in the middle lower yangtze river valley metallogenic belt eastern china abstract the middle lower yangtze river valley metallogenic belt mlyb is one of the most important metallogenic belts in eastern china and contains many important porphyry deposits these deposits include the tongshankou cu mo jiguanzui cu au chengmengshan cu mo wushan cu mo fengshandong cu au dingjiashan cu yangjishan au shaxi cu au dongguashan cu au shujiadian cu and anjishan cu deposits etc in this review we summarize the geological characteristics including the stratigraphy structure ore bearing porphyry types vein characteristics and wall rock alteration metallogenic ages and petro geochemistry of representative porphyry deposits in the mlyb we conclude that porphyritic magmatism and metallogeny have occurred in three stages the early ca 149 135 ma and late ca 123 105 ma stages comprise mainly porphyry skarn mineralization whereas the middle ca 133 125 ma stage comprises porphyry mineralization ore bearing porphyries in the mlyb are the high k calc alkaline to calc alkaline series with the majority possess adakitic geochemical signature the ore bearing porphyries with adakitic signature may have originated from magma mixing produced by the delamination of enriched lithospheric mantle and partial melting of the thickened lower crust the enriched mantle derived mafic melts component are very important for generating fertile magma and the 34s and 18o values suggest that ore forming materials were magma derived compared with porphyry deposits in typical magmatic arc settings porphyry deposits in the mlyb do not contain advanced argillic lithocaps or high to intermediate sulfidation systems and the magmatic and ore forming material sources are also very different

factors controlling copper solubility and chalcopyrite deposition in the sungun porphyry copper deposit iran the sungun porphyry copper deposit is hosted in a diorite granodioritic to quartz monzonitic stock that intruded eocene volcanosedimentary and cretaceous carbonate rocks copper mineralization is associated mainly with potassic alteration and to a lesser extent with sericitic alteration based on previously published fluid inclusion and isotopic data by hezarkhani and williams jones most of the copper is interpreted to have deposited during the waning stages of orthomagmatic hydrothermal activity at temperatures of 400 to 300 c these data also indicate that the hydrothermal system involved meteoric waters and boiled extensively in this work thermodynamic data are used to delineate the stability fields of alteration and ore assemblages as a function of fs2 fo2 and ph the solubility of chalcopyrite was evaluated in this range of conditions using recently published experimental data during early potassic alteration 450 c copper solubility is calculated to have been 50 000 ppm whereas the copper content of the initial fluid responsible for ore deposition is estimated from fluid inclusion data to have been 1200 3800 ppm this indicates that initially the fluid was highly undersaturated with respect to chalcopyrite which agrees with the observation that veins formed at t 400 c contain molybdenite but rarely chalcopyrite copper solubility drops rapidly with decreasing temperature and at 400 c is approximately 1000 ppm within the range estimated from fluid inclusion data whereas at 350 c it is only 25 ppm these calculations are consistent with observations that the bulk of the chalcopyrite deposited at sungun is hosted by veins formed at temperatures of 360 60 c other factors that in principle may reduce chalcopyrite solubility are increases in ph and decreases in fo2 and acl our analysis shows however that most of the change in ph occurred at high temperature when chalcopyrite was grossly undersaturated in the fluid and that the direction of change in fo2 increased chalcopyrite solubility we propose that the sungun deposit formed mainly in response to the sharp temperature decrease that accompanied boiling and partly as a result of the additional heat loss and decrease in acl which occurred as a result of mixing of acidic cu bearing magmatic waters with cooler meteoric waters of lower salinity

kinematic microphysical and electrical aspects of an asymmetric bow echo mesoscale convective system observed during steps 2000 1 five hours of detailed observations of the asymmetric bow echo mesoscale convective system on 11 12 june 2000 during the steps project are presented data sources included polarimetric and doppler radars a vhf lightning mapper and the national lightning detection network nearly every 99 vhf lightning source occurred within 10 km of the convective line charge identification within the much of the convective line revealed evolution during the first 3 h from a normal polarity dipole upper positive charge near 9 km msl 30 c over mid level negative charge near 7 km 16 c to a normal polarity tripole with the addition of lower positive charge near 4 km 1 c during the final 2 h the charge structure resembled an inverted dipole with negative charge overlaying positive when the bow echo occurred during hour 2 part of the cells associated with severe winds developed an inverted tripolar charge structure and produced predominantly positive cloud to ground lightning stratiform lightning was infrequent normally initiating in the convective line and propagating rearward along two pathways a downward sloping upper pathway near 9 km and a more common constant altitude lower pathway near 6 km 10 c some flashes initiated within the stratiform region during this time but only after stratiform reflectivities increased significantly in the mixed phase region these flashes initiated near the bright band 4 km and tapped negative charge above and positive charge below possible mechanisms to explain the observations are discussed

comment new osl dating of uk loess indications of two phases of late glacial dust accretion in se england and climate implications michele l clarke antoni e milodowski jon e bouch melanie j leng and kevin j northmore 2007 journal of quaternary science 22 361 371

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

high cu grades in porphyry cu deposits and their relationship to emplacement depth of magmatic sources observations at several porphyry cu deposits indicate that in those formed above source magma chambers emplaced to relatively shallow levels roofs 3 4 km deep zones of higher cu grade are associated with the oldest intrusions of a central porphyry cluster abundant early a type quartz veins secondary feldspar alteration and usually high fe fe cu low s fe cu sulfide oxide mineral assemblages in deposits for which source magma chambers were deeper roofs 5 km porphyries closest in age to ore are spatially less directly related to mineralization in these higher cu grades in early mineralization comprise swarms of veinlets with alteration halos that include sericite as well as secondary feldspar and biotite sulfide oxide assemblages are usually of lower fe fe cu and higher s fe cu these differences in deposit characteristics appear to correspond with a change from two phase chloride bearing aqueous fluids that would exsolve from magma at shallow depths to one phase fluids deeper

geochemistry and evolution of ore forming fluids of the yueshan cu au skarn and vein type deposits anhui province south china abstract the yueshan mineral belt is geotectonically located at the centre of the changjiang deep fracture zone or depression of the lower yangtze platform two main types of ore deposits occur in the yueshan orefield cu au fe skarn deposits and cu mo au pb zn hydrothermal vein type deposits almost all deposits of economic interest are concentrated within and around the eastern and northern branches of the yueshan dioritic intrusion in the vicinity of the zongpu and wuhen intrusions there are many cu pb zn au s vein type and a few cu fe au skarn type occurrences fluid inclusion studies show that the ore forming fluids are characterised by a cl s na k chemical association hydrothermal activity associated with the above two deposit types was related to the yueshan intrusion the fluid salinity was high during the mineralisation processes and the fluid also underwent boiling and mixed with meteoric water in comparison the hydrothermal activity related to the zongpu and wuhen intrusions was characterised by low salinity fluids chlorine and sulphur species played an important role in the transport of ore forming components hydrogen and oxygen isotope data also suggest that the ore forming fluids in the yueshan mineral belt consisted of magmatic water mixed in various proportions with meteoric water the enrichment of ore forming components in the magmatic waters resulted from fluid melt partitioning the ore fluids of magmatic origin formed large cu au deposits whereas ore fluids of mixed magmatic meteoric origin formed small to medium sized deposits the sulphur isotopic composition of the skarn and vein type deposits varies from 11 3 to 19 2 and from 4 2 to 10 0 respectively these variations do not appear to have been resulted from changes of physicochemical conditions rather due to compositional variation of sulphur at the source s and by water rock interaction complex water rock interaction between the ore bearing magmatic fluids and sedimentary wall rocks was responsible for sulphur mixing lead and silicon isotopic compositions of the two deposit types and host rocks provide similar indications for the sources and evolution of the ore forming fluids hydrodynamic calculations show that magmatic ore forming fluids were channelled upwards into faults fractures and porous media with velocities of 1 4 m s 9 8 10 1 to 9 8 10 7 m s and 3 6 10 7 to 4 6 10 7 m s respectively a decrease of fluid migration velocity in porous media or tiny fractures in the contact zones between the intrusive rocks and the triassic sedimentary rocks led to the deposition of the ore forming components the major species responsible for cu transport are deduced to have been cucl cucl2 cucl32 and cucloh whereas au was transported as au2 hs 2s2 au hs 2 auhs and auh3sio4 complexes cooling and a decrease in chloride ion concentration caused by fluid boiling and mixing were the principal causes of cu deposition gold deposition was related to decrease of ph total sulphur concentration and fo2 which resulted from fluid boiling and mixing geological and geochemical characteristics of the two deposit types in the yueshan mineral belt suggest that there is a close genetic relationship with the dioritic magmatism geochronological data show that the magmatic activity and the mineralisation took place between 130 and 136 ma and represent a continuous process during the yanshanian time the cooling of the intrusions and the mineralisation event might have lasted about 6 ma the cooling rate of the magmatic intrusions was 80 to 120 c my 1 which permitted sufficient heat supply by magma to the ore forming system

copper deposition during quartz dissolution by cooling magmatic hydrothermal fluids the bingham porphyry abstract scanning electron microscope cathodoluminescence imaging is used to map successive generations of fluid inclusions in texturally complex quartz veinlets representing the main stage of ore metal introduction into the porphyry cu au mo deposit at bingham utah following conventional fluid inclusion microthermometry laser ablation inductively coupled plasma mass spectrometry la icpms is applied to quantify copper and other major and trace element concentrations in the evolving fluid with the aim of identifying the ore forming processes textures visible in cathodoluminescence consistently show that the bulk of vein quartz q1 characterized by bright luminescence crystallized early in the vein history cu fe sulfides are precipitated later in these veins in a microfracture network finally filled with a second generation of dull luminescing q2 quartz mapping of brine and vapor inclusion assemblages in these successive quartz generations in combination with la icpms microanalysis shows that the fluids trapped before and after cu fe sulfide precipitation are very similar with respect to their major and minor element composition except for copper copper concentrations in inclusions associated with ore formation drop by two orders of magnitude in a tight pressure temperature interval between 21 and 14 mpa and 425 350 c several hundred degrees below the temperature of fluid exsolution from the magma copper deposition occurs within a limited p t region in which sulfide solubility shows strong normal temperature dependence while quartz solubility is retrograde this permits copper sulfide deposition while secondary vein permeability is generated by quartz dissolution the brittle to ductile transition of the quartz feldspar rich host rocks occurs in the same temperature range which further enhances vein reactivation and promotes cooling and expansion of fluids ascending across the transition from lithostatic to hydrostatic conditions

geology and alteration geochemistry of the porphyry cu au deposit at bajo de la alumbrera argentina this paper describes the igneous geology alteration mineralogy and geochemistry as well as the ore mineralization history of bajo de la alumbrera a world class porphyry copper gold deposit in northwestern argentina the deposit occurs in the k rich calc alkaline farallon negro volcanic complex located 200 km east of the main andean porphyry copper belt of chile the deposit consists of a composite stock of dacitic porphyry intrusions and extends into the surrounding andesitic volcanic rocks two of the earliest intrusions now occupying the center of the intrusive complex show intense hydrothermal alteration and mineralization these two porphyries host the highest ore grades and were subsequently intruded by several weakly mineralized or barren porphyries intense quartz magnetite k feldspar alteration pervades the first mineralized porphyry whereas similar but lower intensity alteration affected the second laterally this alteration grades into potassic alteration secondary k feldspar and biotite which affects all porphyries except the latest dikes andesitic wall rocks within a hundred meters of the intrusions are dominated by dark hydrothermal biotite an outer halo of propylitic alteration epidote chlorite albite calcite extends up to 1 km into the andesites feldspar destructive alteration sericite pyrite clay minerals gypsum overprints the potassic and propylitic alteration in the volcanic rocks and all porphyries the alteration is locally controlled by faults and late fractures and developed most pervasively upon the outer part of the potassic zone and toward the transition to propylitic alteration in the upper part of the deposit mass balance calculations show small positive changes in net volume for the potassic alteration and minor volume decreases for the chlorite epidote and feldspar destructive alteration the intensely quartz magnetite veined sample of quartz magnetite alteration indicates a total volume increase of 350 percent copper and gold are intimately associated at all scales they occur as composite gold sulfide grains chalcopyrite rarely bornite show a close correlation of ore grades in sample assays and have a closely overlapping distribution on the mine scale a well developed ore shell coincides with potassic alteration and partly with the distribution of intense quartz magnetite veins even though the bulk of the ore minerals now occupy texturally late positions in vugs and fractures a barren zone with intense quartz magnetite potassic alteration and veins but little or no sulfides is interpreted as the focus of upflow of high temperature ore fluids prior to ore mineral saturation and coprecipitation of copper sulfides and gold in the ore shell

mobility and h2o loss from fluid inclusions in natural quartz crystals petrographic observations on quartz crystals from the mole granite australia and other localities shed new light on the mechanisms of post entrapment modification of fluid inclusions these modifications include migration away from pseudosecondary trails changes in fluid salinity and density shape distortion and the formation of sweat haloes around strongly deformed inclusions increases in fluid salinity which usually are associated with inclusion migration indicate water losses of up to 50 however la icp ms analysis of unmobilized and mobilized inclusions of the same trail reveals basically unchanged ratios of major and trace element cations with the exception of li which seems to be incorporated into the crystal lattice during migration despite the fact that all these modifications are closely related to deformation processes they occur not only in mechanically deformed quartz but also in free standing crystals in the latter samples stress has been generated internally as a result of brazil twinned growth and compositional zonation these observations and their interpretation leads to a list of practical criteria that should help in differentiating between reliable and suspect fluid inclusions in other samples

cloud to ground lightning in linear mesoscale convective systems recently three distinct archetypes for midlatitude linear mesoscale convective systems mcss have been identified those comprising convective lines with trailing stratiform precipitation ts leading stratiform precipitation ls and parallel stratiform precipitation ps while cloud to ground cg lightning in ts mcss has received a great deal of study in recent years linear mcss exhibiting leading or parallel stratiform precipitation have received comparatively little attention this paper documents the arrangement and frequency of cg lightning for four ls and four ps mcss that occurred during may 1996 and may 1997 on average the ls cases bore some similarity to previously studied ts mcss they produced predominantly positive cg lightning 1cg early in their lifetimes concomitant with convective precipitation and late in their lifetimes concomitant with stratiform precipitation in contrast with previously published results for mcss in general the ls mcss in the present study overall had relatively low negative cg 2cg flash densities yielding higher percentages of 1cgs than other mcs archetypes while the ps systems had higher average flash densities than the ls systems they did not exhibit prolonged 1cg modes early in their lifetimes and they produced a lower overall fraction of 1cgs notably the presence of line parallel flow may render a somewhat unique electrical character in ps systems in particular the ps mcss in this study exhibited enhanced cg lightning in the vicinity of decaying convective cells that were embedded within their stratiform precipitation regions

genesis of the yandong porphyry cu deposit in eastern tianshan nw china evidence from geology fluid inclusions and isotope systematics abstract the yandong porphyry cu deposit 372 mt at 0 58 cu is located in the center of the eastern tianshan xinjiang nw china multiple stage hydrothermal activities have resulted in potassic chlorite sericite phyllic and propylitic alteration in this deposit the yandong deposit formed in four stages i e an early quartz magnetite pyrite stage i a quartz pyrite chalcopyrite stage ii a quartz chalcopyrite pyrite molybdenite stage iii and a late quartz carbonate stage iv three evolutionary episodes were observed by a detailed fluid inclusion study 1 early ore stage i fluids were trapped under two phase conditions as evidenced by the coexistence of vapor rich v type inclusions homogenization temperatures 410 494 c average salinity 2 2 wt nacl equiv liquid rich l type inclusions homogenization temperatures 311 430 c average salinity 9 5 wt nacl equiv and hypersaline h type inclusions trapped at 300 bars or a depth of approximately 1 km assuming lithostatic pressure conditions 2 main ore stage ii and iii fluid inclusions in quartz were also trapped under two phase conditions boiling as identified by the coexistence of v and l type fluid inclusions l type inclusions homogenized between 161 and 390 c average 270 c with salinities of 1 6 9 9 wt nacl equiv average 4 9 wt nacl equiv and a depth of 1 km 100 bars hydrostatic pressure conditions 3 late ore stage iv fluids are represented by inclusions in barren quartz carbonate veinlets characterized by homogenization temperatures ranging from 123 to 261 c average 179 c and salinities between 0 7 and 4 7 wt nacl equiv average 2 0 wt nacl equiv the initial hydrothermal fluids are characterized by high temperature high salinity and high oxygen fugacity belonging to a h 2 o nacl system hydrogen and oxygen isotope data indicate that the hydrothermal fluids have a dominantly magmatic signature and mixed with abundant meteoric waters in the quartz carbonate stage sulfur stable isotope suggests that the ore forming metals came primarily from the tonalite magma that sourced from the subducted oceanic slab involving some mantle peridotites during ascent the cu mineralization of the yandong porphyry deposit occurred at a shallow crustal level approximately 1 km and the fluid boiling or phase separation decrease of temperature as well as fluid rock interaction were likely important factors responsible for metal accumulation and deposition in the magmatic hydrothermal system

energy release in subvolcanic environments implications for breccia formation mechanical pdelta v energy is released from hydrous magmas in subvolcanic environments by the two generally sequential processes of second boiling and subsequent decompression the second boiling process h 2 o saturated melt crystals h 2 o vapor releases sufficient pdelta v energy in the model system previously established by burnham 1979 and burnham and ohmoto 1980 to cause fracture failure of even the strongest wall rocks tensile strength approximately 3 77 x 10 10 ergs kg super 1 to depths of 4 or 5 km following fracture failure moreover expansion of already exsolved h 2 o and exsolution of additional h 2 o upon decompression into the model fracture system releases additional pdelta v energy 9 7 x 10 10 ergs kg super 1 of magma sufficient to lift an equivalent mass of rock nearly 1 km in the absence of frictional resistance this latter energy although a conservative value is model dependent to the extent that it is affected by changing any one of the following six independent model parameters 1 bulk composition of the magma hornblende biotite granodiorite in the model 2 depth of emplacement of the magma body approximately 2 3 km p t 0 6 kb 3 mass fraction of h 2 o in the initial melt f o w 0 027 2 7 wt h 2 o 4 mass fraction of melt in the magma at the time of emplacement f o m 1 0 100 liquid 5 tensile strength of the wall rocks 3 77 x 10 10 ergs kg super 1 and 6 depth to the top of the fracture once formed approximately 2 3 km p f 0 3 kb although all of these parameters except the first are of major importance in the formation of hydrothermal breccias generally the mass fraction of h 2 o in the initial melt f o w is regarded as the single most important factor in the formation of breccia bodies in typical porphyry type systems f o w not only determines primarily whether or not the second boiling reaction releases enough pdelta v energy to produce fractures it also determines the magnitude of the decompressional energy released into the fractures if formed magmas in which f o w 0 02 to 0 04 at liquidus temperatures generally release sufficient pdelta v energy not only to produce extensive porphyry type fracture systems but also to produce the breccia bodies these systems commonly contain magmas in which f o w 0 02 on the other hand generally do not release sufficient energy for extensive breccia formation except in structurally weak wall rocks at depths shallower than approximately 2 km magmas in which f o w raquo 0 04 at near liquidus temperatures are incapable of emplacement in the subvolcanic environment

geology of the post collisional porphyry copper molybdenum deposit at qulong tibet porphyry deposits are usually thought to form from subduction related calc alkaline magmas in magmatic arc settings although some porphyry deposits also occur in post collisional extensional settings the post collisional deposits remain poorly understood here we describe the igneous geology alteration mineralogy and mineralization history of qulong a newly discovered porphyry cu mo deposit in southern tibet that belongs to the post collisional class the deposit is associated with miocene monzogranite granodiorite intrusions and is hosted partly by jurassic andesitic dacitic volcanic rocks the deposit contains 7 1 mt cu and 0 5 mt mo metal the 19 5 ma granodioritic monzogranitic rongmucuola pluton with diorite enclaves is the earliest miocene intrusive unit it was intruded by a regularly shaped stock p porphyry and then thin dikes x porphyry of monzogranite at about 17 7 ma the main cu mo mineralization is associated with the p porphyry a barren diorite porphyry intruded the p and x porphyries around 15 7 ma petrologic trends of the intrusions suggest that the miocene intrusions have similar origins and probably formed by fractionation of a deeper magma chamber emplacement of miocene porphyries controlled by the qulong anticline is in direct response to the rapid uplift erosion of the gangdese arc batholiths in southern tibet miarolitic cavities and unidirectional solidification textures key evidence for volatile separation have been recognized in the p and x porphyries respectively early potassic alteration characterized by quartz k feldspar anhydrite pervades the p porphyry and rongmucuola pluton laterally this alteration grades into quartz biotite anhydrite k feldspar which affects all miocene intrusions except the latest dioritic porphyry wall rocks of rongmucuola pluton and jurassic andesitic dacitic volcanics within 1 1 5 km of the porphyries are dominated by pervasive potassic alteration an outer halo of propylitic alteration epidote chlorite calcite extends up to 2 km away from the deposit feldspar destructive alteration sericite chlorite clay minerals has overprinted most of the potassic and part of the propylitic alteration the alteration is strongly pervasive in the interior of the porphyry bodies and occurs as vein halos away from the porphyry bodies the earliest quartz k feldspar alteration and veins are barren whereas approximately 60 of the cu reserves is associated with slightly later quartz biotite anhydrite alteration barren assemblages are related to irregular quartz k feldspar anhydrite veins which are truncated by the x porphyry cu sulfide bearing assemblages are associated with discontinuous chalcopyrite biotite and continuous quartz anhydrite chalcopyrite molybdenite veins deposition of cu mo with abundant anhydrite occurred during or between emplacement of closely related porphyries from high temperature magmatically derived fluids and was probably caused by the disproportionation of so

metal fractionation between magmatic brine and vapor determined by microanalysis of fluid inclusions the major and trace element compositions of individual fluid inclusions from a range of magmatic hydrothermal ore deposits were analyzed by laser ablation inductively coupled plasma mass spectrometry to explore the behavior of ore forming components during fluid phase separation boiling in high temperature saline fluid systems data from 13 samples showing unambiguous evidence for coeval trapping of a liquid brine and a coexisting vapor phase identify two groups of elements with drastically different geochemical behavior na k fe mn zn rb cs ag sn pb and tl preferentially partition into the brine probably as cl complexes whereas cu as au probably as hs complexes and b selectively partition into the vapor fluid phase separation is probably a major previously underestimated process in the chemical differentiation that contributes to the extreme range of selective element enrichments in magmatic hydrothermal systems from deep plutons through porphyry style and greisen deposits to epithermal mineralization and volcanic fumaroles

molybdenite re os and albite 40ar 39ar dating of cu au mo and magnetite porphyry systems in the yangtze river valley and metallogenic implications abstract the area of the middle lower yangtze river valley eastern china extending from wuhan hubei province to western zhenjiang jiangsu province hosts an important belt of cu au mo and fe deposits there are two styles of mineralization i e skarn porphyry stratabound cu au mo fe deposits and magnetite porphyry deposits in several nne trending cretaceous fault bound volcanic basins the origin of both deposit systems is much debated we dated 11 molybdenite samples from five skarn porphyry cu au mo deposits and 5 molybdenite samples from the datuanshan stratabound cu au mo deposit by icp ms re os isotope analysis nine samples from the same set were additionally analyzed by ntims on re os results from the two methods are almost identical the re os model ages of 16 molybdenite samples range from 134 7 2 3 to 143 7 1 6 ma 2 the model ages of the five samples from the datuanshan stratabound deposit vary from 138 0 3 2 to 140 8 2 0 ma with a mean of 139 3 2 6 ma their isochron age is 139 1 2 7 ma with an initial os ratio of 0 7 8 1 mswd 0 29 these data indicate that the porphyry skarn systems and the stratabound deposits have the same age and suggest an origin within the same metallogenic system albite 40 ar 39 ar dating of the magnetite porphyry deposits indicates that they formed at 123 to 125 ma i e 10 20 ma later both mineralization styles characterize transitional geodynamic regimes i e the period around 140 ma when the main ns trending compressional regime changed to an ew trending lithospheric extensional regime and the period of 125 115 ma of dramatic ew trending lithospheric extension

the evolution of a porphyry cu au deposit based on la icp ms analysis of fluid inclusions bajo de la alumbrera argentina the chemical and physical evolution of magmatic to hydrothermal processes in the porphyry cu au deposit of bajo de la alumbrera northwestern argentina has been reconstructed with a quantitative fluid inclusion study fluid inclusion petrography microthermometry and single inclusion microanalysis by excimer laser ablation inductively coupled plasma mass spectrometry la icp ms are combined to determine the evolution of pressure temperature and ore metal concentrations including cu and au in the fluids complementary hydrogen and oxygen isotope analyses are used to further constrain the water sources in the evolving system the combined data provide a new level of insight into the mechanisms of metal sourcing and ore mineral precipitation in a porphyry style magmatic hydrothermal system based on previously reported observations of the igneous geology alteration geochemistry and veining history of the subvolcanic porphyries at alumbrera the distribution of fluid inclusion types in space and time is documented six major inclusion types are distinguished the highest temperature brine inclusions up to 750 c p 1 kbar are mainly recorded in barren quartz magnetite veins in the core of the alteration system these polyphase brine inclusions halite sylvite multiple opaque and transparent daughter crystals are interpreted as the most primitive magmatic fluid recorded at the level of the deposit they are of moderately high salinity 50 60 wt nacl equiv dominated by nacl kcl and fecl 2 and contain on average 0 33 wt percent cu and 0 55 ppm au upon cooling and decompression these saline liquids exsolve a vapor phase which is preferentially enriched in cu relative to its main salt components but probably plays a minor role in the formation of this particular deposit because of the inferred small mass fraction of vapor cooling and decompression from the highest initial p t conditions down to about 450 c causes magnetite k silicate alteration but no saturation in au or cu sulfides as recorded by continually high ore metal concentrations in the fluid inclusions coprecipitation of cu and au as chalcopyrite and native gold some early bornite occurs over a narrow range of decreasing fluid temperature with cooling from 400 to 305 c the cu concentration in the brine drops by about one order of magnitude to less than 0 07 wt percent without a proportional decrease in major salt components ore mineral precipitation extracts 85 percent of the cu and au from the fluid it is associated with potassic alteration as shown by a concomitant decrease in the k na ratio of the cooling magmatic brine and by an increase in its ba and sr concentrations elements which are probably liberated in the destruction of calcic igneous minerals the fluid chemical data demonstrate that the metal ratios in this and probably many other porphyry style ore deposits are primarily controlled by the magmatic source of the ore brines on the other hand the final hypogene ore grade of the deposit is controlled by the efficiency of ore mineral precipitation at alumbrera metal extraction is governed by the efficiency of cooling a high flux of magmatic fluid within a small rock volume dilution of residual magmatic fluids as recorded by aqueous fluid inclusions of decreasing salinities and temperatures below 295 c follows after the main stage of copper introduction and is associated with feldspar destructive phyllic alteration geometric relationships fluid analyses and stable isotope data together indicate that phyllic alteration results from postmineralization hydrothermal activity involving minor mixing between meteoric water residual brine and a waning input of magmatic vapor

a numerical model to estimate trapping conditions of fluid inclusions that homogenize by halite disappearance abstract fluid inclusions fi that homogenize by halite disappearance are common in some geological environments and interpretation of microthermometric data from these inclusions has been limited by the lack of a model describing the pvtx relationships over the complete range of ptx conditions found in nature in this study a system of equations has been developed that can be used to estimate salinity pressure and density of fi that homogenize by halite disappearance the salinity pressure density and d p d t slope of the fi isochore are calculated as functions of liquid vapor homogenization temperature th and halite dissolution temperature tm the equations are based on a numerical model describing the isochoric pressure temperature trajectory followed by halite saturated fluids during heating the model is valid for th and tm from 100 to 600 c and for pressures along the liquid vapor halite curve to 300 mpa

reconciling fluid inclusion types fluid processes and fluid sources in skarns an example from the bismark deposit mexico the bismark deposit 8 5 mt at 8 zn 0 5 pb 0 2 cu and 50 g t ag located in northern mexico is an example of a stock contact skarn end member of a continuum of deposit types collectively called high temperature carbonate replacement deposits the deposit is hosted by massive sulfide within altered limestone adjacent to the bismark quartz monzonite stock 42 ma and the bismark fault alteration concurrently developed in both the intrusion and limestone the former contains early potassic alteration comprising k feldspar and biotite which was overprinted by kaolinite rich veins and alteration and later quartz sericite and pyrite with minor sphalerite and chalcopyrite prograde exoskarn alteration in the limestone consists of green andradite and diopside and transitional skarn comprising red brown andradite green hedenbergite and minor vesuvinite calcite fluorite and quartz the main ore stage post dates calc silicate minerals and comprises sphalerite and galena with gangue pyrite pyrrhotite calcite fluorite and quartz the entire hydrothermal system developed synchronously with faulting fluid inclusion studies reveal several distinct temporal compositional and thermal populations in pre syn and post ore quartz fluorite and calcite the earliest primary fluid inclusions are coexisting vapor rich type 2a and halite bearing type 3a type 3b contain sylvite brine inclusions 32 to 60 total wt salts that occur in pre ore fluorite trapping temperatures are estimated to have been in excess of 400 c under lithostatic pressures of 450 bar 1 5 km depth primary fluid inclusions trapped in syn ore quartz display critical to near critical behavior type 1c have moderate salinity 8 4 to 10 9 wt nacl equiv and homogenization temperatures th ranging from 351 to 438 c liquid rich type 1a and 1b calcite bearing inclusions occur as primary to secondary inclusions predominantly in fluorite and show a range in th 104 336 c and salinity 2 7 11 8 wt nacl equiv which at the higher th and salinity ranges overlap with type 1c inclusions oxygen isotope analysis was carried out on garnet quartz and calcite plus carbon isotopes in pre syn post ore and peripheral veins pre ore skarn related garnets have a 18omineral range between 3 9 and 8 4 quartz from the main ore stage range between 13 6 and 16 0 calcite from the main ore stage has 13c values of 2 9 to 5 1 and 18o values of 12 3 to 14 1 which are clearly distinct from post ore veins and peripheral prospects that have much higher 18o 16 6 27 3 and 13c 1 3 3 1 values despite the numerous fluid inclusion types only two fluid sources can be inferred namely a magmatic fluid and an external fluid that equilibrated with limestone furthermore isotopic data does not indicate any significant mixing between the two fluids although fluid inclusion data may be interpreted otherwise thus the various fluid types were likely to have formed from varying pressure temperature conditions through faulting during exsolution of magmatic fluids late stage hydrothermal fluid activity was dominated by the non magmatic fluids and was post ore

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

ore genesis and hydrothermal evolution of the baiyinnuo er zinc lead skarn deposit northeast china evidence from isotopes s pb and fluid inclusions the baiyinnuo er zinc lead deposit 32 74 mt at 5 44 zn 2 02 pb and 31 36 g t ag located in the south segment of the great xing an range is the largest zn pb deposit in northern china skarn and orebodies mainly occur between the different units of the huanggangliang formation or within the contact zone between the intrusions and permian marble several phases of igneous rocks exposed within the mining areas and among them the yanshanian plutonic rocks which intruded into limestone of the early permian huanggangliang formation are interpreted to be the source of ore since their pb isotope compositions 206pb 204pb 18 25 18 35 207pb 204pb 15 50 15 56 and 208pb 204pb 38 14 38 32 are highly consistent with the sulfides including sphalerite galena and chalcopyrite 206pb 204pb 18 23 18 37 207pb 204pb 15 47 15 62 and 208pb 204pb 37 93 38 44 sulfur isotope values of the sulfides give a narrow 34s interval of 6 1 to 4 6 mean 5 4 n 15 suggesting the ore forming fluid is of magmatic origin three main paragenetic stages of skarn formation and ore deposition have been recognized based on petrographic observation which are the preore stage garnet clinpyroxene wollastonite magnetite sulfides the synore stage sulfides epidote quartz calcite garnet and the postore stage calcite chlorite quartz fluorite several fluid evolution episodes can be inferred from microthermometric results at the baiyinnuo er zn pb deposit 1 immiscibility preore stage coexistence of halite bearing brine inclusions s1 type 44 wt nacl equiv and vapor rich fluid inclusions v type sharing the same homogenization temperatures 470 c confirms that fluid unmixing occurred under lithostatic pressures of 400 bars 1 5 km and the brine is considered to account for most prograde skarn minerals e g clinopyroxene 2 overpressure trapping preore stage brine inclusions homogenized by halite dissolution s2 type postdated the immiscible assemblages this type of inclusions is characterized by high but variable minimum trapping pressures 150 3 000 bars relative to s1 type inclusions and can be explained as a result of entrapment under overpressuring condition 3 boiling the presence of both vapor and liquid inclusions i e v and l type in the same assemblages within synore stage quartz calcite and sphalerite indicates the occurrence of fluid boiling 350 c at hydrostatic pressures of 150 bars and depth of 1 5 km which resulted in large scale mineralization in the baiyinnuo er zn pb deposit 4 mixing with external fluids fluid inclusions scattered within postore stage calcite or secondary trails in synore stage minerals show low homogenization temperatures 260 c and both decreasing for l type and increasing for cacl2 bearing inclusions i e lc type trends for salinities as homogenization temperatures decrease implying addition of both meteoric water low temperature low salinity and basinal brines low temperature ca rich respectively systematic fluid inclusion studies also indicate that the mineralization related fluid is of magmatic origin prograde minerals formed during the preore stage fluid immiscibility while sulfides deposition occurred during the synore stage fluid boiling mixing with external fluids began as the hydrothermal system cooled to 300 c when the main metal precipitation process had ended

a fluid inclusion study of the suicide ridge breccia pipe cloncurry district australia implication for breccia genesis and iocg mineralization abstract the suicide ridge barren breccia pipe 1527 4 ma is one of numerous breccia occurrences that characterize the cloncurry district australia interest in breccia systems in the cloncurry district is related to their possible link with iron oxide copper gold deposits the suicide ridge barren breccia pipe is temporally and spatially associated with a granite that outcrops at its southwestern boundary and which is ascribed to the williams and naraku magmatic event ca 1550 1500 ma the breccia is characterized by clasts of variable dimensions degree of rounding and composition that includes dominant calc silicate clasts of the corella formation that underlie rocks of the soldiers cap group that host the pipe indicating a dominant upward transport of the fragments other breccia fragments include granite bodies characterized by albite quartz mineralogy and textures typical of the magmatic hydrothermal transition these rocks are interpreted to have formed in a fractionated granite carapace during the exsolution and accumulation of volatiles associated with the cooling magma two dominant types of inclusions have been identified at the suicide ridge barren breccia pipe these include early primary and pseudosecondary carbonic fluid inclusions observed only in magmatic hydrothermal transitional textures of granite breccia clasts and secondary sodic calcic brine inclusions that occur in all the collected samples variable homogenization temperatures in the primary and pseudosecondary pure co2 fluid inclusions indicate that they were trapped under different pressure conditions pressures estimated from the primary co2 fluid inclusions suggest that they were trapped at 4 2 kbar at least 1 kbar above the inferred lithostatic pressure this likely represents the overpressuring produced by release of co2 rich volatiles during the crystallization of magma and which ultimately caused the subsequent brecciation estimated pressures for pseudosecondary co2 fluid inclusions indicate pressure entrapment conditions around 2 7 kbar similar to the lithostatic pressure and 1 5 kbar lower than pressures recorded by type ia fluid inclusions this significant drop of pressure likely represents the sudden pressure depression occurring in response to brecciation evidence from field relationships breccia characteristics mineralogy and textures of granite clasts within the pipe and fluid inclusion studies support an origin of the suicide ridge barren breccia pipe in response to overpressuring generated by the release expansion and possibly phase separation of fluids of dominant carbonic composition from a crystallizing magma beneath and adjacent to the pipe sodic calcic fluid inclusions represent a later influx of fluids in the breccia system that produced widespread albitization significantly high temperature ultrasaline multisolid fluid inclusions abundant in iocg deposits and considered to be samples of the mineralizing fluid were not observed at the suicide ridge breccia pipe their absence in the barren systems suggests that they were critical for the formation of iocg deposits

the evolution of cloud to ground lightning within a portion of the 10 11 june 1985 squall line abstract the character of cloud to ground lightning is examined during the life cycle of a distinct mesoscale segment of the 10 11 june 1985 mesoscale convective system mcs three phases of lightning activity are identified and related to both the radar observed structure of the convection and to the severe weather produced by the mcs positive strikes to ground are dominant when the mcs is first developing negative strikes then dominate during a period of intense leading line convective activity with high storm tops finally a period of relatively frequent positive strikes within the trailing stratiform region occurs during the demise of the mcs this last phase begins after the vertical extent of the leading convective line decreases rapidly and markedly with moderate intensity echoes i e 30 40 dbz occurring mostly below the freezing level the first period of frequent positive flashes results from the lightning associated with a single severe thunderstorm in southwest kansas however a second

the lower changjiang yangzi yangtze river metallogenic belt east central china intrusion and wall rock hosted cu fe au mo zn pb ag deposits abstract the lower valley of changjiang from wuhan of the hubei province in the west to zhenjiang of the jiangsu province in the east contains more than 200 polymetallic cu fe au mo zn pb ag deposits and is one of the most important metallogenic belts in china this metallogenic belt situated at the northern margin of the yangzi craton and bordered by the dabieshan ultrahigh pressure metamorphic belt to the north consists mainly of cambrian triassic marine clastic sedimentary rocks and carbonate and evaporite rocks which overlay a precambrian basement and are intruded by yanshanian 205 to 64 ma granitoid intrusions and subvolcanic complexes repeated tectonism from late proterozoic to triassic resulted in extensively developed networks of faults and folds involving the cambrian triassic sedimentary strata and the precambrian basement the yanshanian granitoid intrusions and subvolcanic complexes in the lower changjiang metallogenic belt are characterized by whole rock 18 o of 8 to 10 initial 87 sr 86 sr of 0 704 to 0 708 and ndt from 10 to 17 and have been interpreted to have originated from mixing between juvenile mantle and old crustal materials also the yanshanian granitoids exhibit eastward younging and increase in alkalinity i e from older calc alkaline in the west to younger subalkaline alkaline in the east which are related to oblique collision between the yangzi and sino korean cratons and tectonic evolution from early compressional to late extensional or rifting regimes most polymetallic deposits in the lower changjiang metallogenic belt are clustered in seven districts where the yanshanian magmatism is particularly extensive from west to east edong jiurui anqing guichi luzhong tongling ningwu and ningzhen mineralization is characterized by the occurrence of three distinct types of orebodies in individual deposits orebodies in yanshanian granitoid intrusions skarn orebodies at the contact zones between the yanshanian intrusions and late paleozoic early mesozoic sedimentary rocks and stratabound massive sulfide orebodies in the late paleozoic early mesozoic sedimentary strata the most important host sedimentary strata are the middle carboniferous huanglong formation lower permian and lower middle triassic carbonate and evaporite rocks the intrusion hosted and skarn orebodies exhibit well developed zonation in alteration assemblages metal contents and isotopic compositions within individual deposits and apparently formed from hydrothermal activities related to the yanshanian magmatism the stratabound massive sulfide orebodies in the late paleozoic early mesozoic sedimentary strata have long been suggested to have formed from sedimentary or volcano sedimentary exhalative processes in shallow marine environments however extensive research over the last 40 years failed to produce unequivocal evidence for syngenetic mineralization on the basis of geological relationships and isotope geochemical characteristics we propose a carbonate hosted replacement deposit model for the genesis of these stratabound massive sulfide orebodies and associated skarn orebodies this model suggests that epigenetic mineralization resulted from interactions between magmatic fluids evolved from the yanshanian intrusions with carbonate and evaporite wall rocks mineralization was an integral but distal part of the larger hydrothermal systems that formed the proximal skarn orebodies at the contact zones and the intrusion hosted orebodies the stratabound massive sulfide deposits of the lower changjiang metallogenic belt share many features with the well studied high temperature carbonate hosted replacement deposits of northern mexico and western united states particularly with respect to association with small shallow granitoid complexes structural and stratigraphic controls on mineralization alteration assemblages geometry of orebodies metal association metal zonation and isotopic systematics

analysis of a small vigorous mesoscale convective system in a low shear environment part i formation radar echo structure and lightning behavior the evolution of a small vigorous mesoscale convective system mcs over northern alabama is described using doppler radar goes satellite surface mesonet lightning and sounding data the mcs formed near noon in a relatively unstable environment having weak synoptic forcing and weak shear the initiation of separate lines and clusters of deep convection occurred in regions exhibiting cumulus cloud streets horizontal variations in stratocumulus cloud cover and variations in inferred soil moisture mcs growth via merger of storms within clusters and lines and among the clusters was accomplished largely through intersection of storm scale and mesoscale outflow boundaries the mcs maximum anvil area 60 000 km2 at 220 k and lifetime 8 h were about 50 that of the typical great plains mesoscale convective complex mcc despite its smaller size this mcs displayed many aspects that typify the mostly nocturnal great plains mcs the precipitation output was highly variable due to the transient nature of the intense convective elements many of which produced microbursts the radar measurements documented the formation of a stratiform region along the trailing side of an intense convective line this stratiform region formed as decaying convective cores coalesced rather than through advection of precipitation particles directly from the convective region combined goes ir imagery and radar reflectivity analyses within the stratiform region show a sinking anvil cloud top in the presence of increases in the vertical radar reflectivity gradient within the cloud during the maturation of the stratiform region during its intense developing stages the mcs generated a peak cloud to ground cg flash rate of 2400 h 21 comparable to rates produced by larger mccs early on positive cg flashes were most prevalent around intense convective core regions exhibiting strong divergence at anvil level during the latter stages the emergence of positive cg was coincident with the formation of a prominent radar bright band within the stratiform region thus a bipole was established but its length was quite short at approximately 50 km 25 50 of the distance documented in other mcss

giant porphyry deposits characteristics distribution and tectonic controls more than half of the 25 largest known porphyry copper deposits defined in terms of contained copper metal formed during three time periods the paleocene to eocene eocene to oligocene and middle miocene to pliocene these giant deposits are clustered within three provinces central chile northern chile and southwest arizona northern mexico other giant deposits occur in montana utah panama peru argentina irian jaya mongolia and iran compressive tectonic environments thickened continental crust and active uplift and erosion were associated with the formation of many of these deposits calc alkalic magmas are most favorable for the formation of giant porphyry copper deposits although several of the largest systems are associated with high k calc alkalic intrusions the 25 largest gold rich porphyry deposits are concentrated in the southwest pacific and south america with other occurrences in eurasia british columbia alaska and new south wales many of the deposits formed in the last 13 m y the largest of the deposits are associated with high k calc alkalic intrusions many calc alkalic porphyritic intrusions have also produced giant gold rich porphyries in the last 20 m y the formation of giant porphyry copper molybdenum and copper gold deposits in the circum pacific region has been closely associated with subduction of aseismic ridges seamount chains and oceanic plateaus beneath oceanic island and continental arcs in several examples these tectonic perturbations have promoted flat slab subduction crustal thickening uplift and erosion and adakitic magmatism coeval with the formation of well endowed porphyry and or epithermal mineral provinces similar tectonic features are inferred to be associated with the giant porphyry copper molybdenum provinces of northern chile eocene oligocene and southwest united states cretaceous paleocene topographic and thermal anomalies on the downgoing slab appear to act as tectonic triggers for porphyry ore formation other factors such as sutures in the overriding plate permeability architecture of the upper crust efficient processes of ore transport and deposition and in some cases formation and preservation of supergene enrichment blankets are also vital for the development of high grade giant ore deposits a low grade geochemical anomaly may be the final product of mineralization if ore forming processes do not operate efficiently even in the most favorable geodynamic settings

geological and geochemical studies of the shujiadian porphyry cu deposit anhui province eastern china implications for ore genesis abstract most porphyry deposits in the world occur in magmatic arc settings and are related to subduction of oceanic plates a small proportion of porphyry deposits occur in intracontinental settings however they are still poorly understood shujiadian a newly discovered porphyry cu deposit is located in the middle lower yangtze river valley metallogenic belt and belongs to the intracontinental class the deposit has classic alteration zones defined by a core of potassic alteration and local ca silicate alteration which is overprinted by a feldspar destructive alteration zone and cut by veins containing epidote and chlorite wallrocks of the deposit are unreactive quartz rich sedimentary rocks three main paragenetic stages have been recognized based on petrographic observations silicate stage quartz sulfide stage and sulfide carbonate stage quartz pyrite chalcopyrite molybdenite veins and quartz chalcopyrite pyrite veins of the quartz sulfide stage contribute most of the copper and chalcopyrite chlorite pyrite pyrrhotite quartz illite veins of the sulfide carbonate stage also contribute part of the copper all the mineralized veins are associated with feldspar destructive alteration investigations on the fluid inclusions in shujiadian indicate that the ore forming fluids had four evolutionary episodes immiscibility and overpressure in the silicate stage boiling in the quartz sulfide stage and mixing with meteoric water in the sulfide carbonate stage sulfur and strontium isotope studies suggest that ore metals were mainly derived from magmatic hydrothermal fluids and combined with our study of fluid inclusions we infer that decompression changes in oxygen fugacity and sulfur content were the main factors that caused cu precipitation compared with porphyry deposits in magmatic arc settings there are some differences in the ore bearing rock alteration and the composition of ore forming fluids

direct evolution of brine from a crystallizing silicic melt at the questa new mexico molybdenum deposit molybdenum mineralization in the southwest orebody at the questa deposit is associated with crystallization of aplite porphyry explosive brecciation and exsolution of magmatic hydrothermal fluids quartz k feldspar fluorophlogopite and molybdenite precipitated from exsolving aqueous fluids and cemented aplite porphyry and andesite wall rock clasts forming a magmatic hydrothermal breccia ore fluid inclusions in quartz in the breccia matrix trapped aqueous fluids that transported and precipitated molybdenum two fluid inclusion populations associated with molybdenite mineralization were identified the largest population commonly contains liquid vapor halite sylvite and one or more opaque daughter crystals these inclusions homogenize between 200 degrees and 500 degrees c and have a prominent mode at 360 degrees to 400 degrees c salinities vary from 31 to 57 wt percent nacl equiv low first ice melting temperatures suggest that additional fluid components possibly calcium or magnesium chlorides may be present approximately 80 percent of these inclusions homogenize by halite dissolution phase equilibria constraints require that these inclusions trapped fluids in the vapor absent field the remaining saline inclusions homogenize to liquid at temperatures above halite dissolution temperatures significantly the saline fluid did not coexist with a low density aqueous fluid a second population of inclusions contains fluids with salinities of 2 7 to 25 0 wt percent nacl equiv and homogenizes by vapor bubble disappearance vapor bubble expansion or critical behavior textural relationships and phase behavior during microthermometry indicate that these inclusions constitute a single population which formed as pressure and temperature fluctuated at near critical conditions pressure changes related to brecciation followed by crystallization and system resealing produced the observed fluids saline fluids were trapped as the system sealed following a major brecciation event these high salinity fluids were produced as the melt under pressure that increased from hydrostatic to lithostatic partitioned increasing amounts of chlorine into the exsolving aqueous fluid renewed fracturing and abrupt pressure decrease to hydrostatic conditions reduced the mass of chlorine partitioning to the exsolving fluid lower salinity fluids exsolved at near critical conditions and were trapped by inclusions that homogenize to liquid to vapor or by critical behavior the lack of cogenetic liquid and vapor rich fluid inclusions and phase equilibria constraints indicate that high salinity fluids or 57 wt nacl equiv were generated directly by the crystallizing magma and were not a product of aqueous fluid immiscibility

a tectono genetic model for porphyry skarn stratabound cu au mo fe and magnetite apatite deposits along the middle lower yangtze river valley eastern china abstract the middle lower yangtze river valley metallogenic belt yrb situated along the northern margin of the yangtze craton is characterized by porphyry skarn stratabound cu au mo fe deposits in the areas of uplift and magnetite apatite deposits in cretaceous fault basins following detailed field investigations and a review of published data we recognize two episodes of magmatism and mineralization in the yrb 1 156 137 ma high k calc alkaline granitoids associated with 148 135 ma porphyry skarn stratabound cu au mo fe deposits and 2 135 123 ma shoshonitic series associated with 134 9 122 9 ma magnetite apatite deposits a type granitoids and associated alkaline volcanic have a small age range from 126 5 to 124 8 ma and are temporally spatially and genetically associated with the second episode the geodynamic history of the yrb did not experience the paleozoic to mesozoic lithospheric thickening that took place in the north china craton this process is inferred to be linked to partial melting of the delaminated lower crust at high pressures resulting in the development of c type adakitic rocks the petrochemical and sr nd isotopic data show that both the shoshonitic series and a type granitoids are quite different from adakites with only some of the k calc alkaline granitoids having adakitic signatures previous ore genesis models were established based on an assumed relationship with adakites and a continuous tectono thermal evolution from 150 to 100 ma all data obtained for the middle lower yangtze river region consistently show that the tan lu regional strike slip fault zone initiated at 233 6 to 225 6 ma from the collision between the north china and yangtze cratons and was reactivated at ca 160 ma the tan lu fault was caused by the oblique subduction of the izanagi plate which along the yrb the low angle subducted slab and the overlying crust was disrupted or broken due to the disharmonious movement of the two blocks the high k calc alkaline granitoids magmas were derived from melting of the subducted slab with some input of crustal material these magmas were emplaced at the intersections between ne and ew trending faults and formed porphyry skarn stratabound cu au mo fe deposits between 156 and 137 ma after 135 ma the subducted plate changed its direction of motion to northeast now running parallel to the eurasian continental margin and leading to large scale continental extension the shoshonitic series and subsequent a type granitoids magmatism and the development of magnetite apatite ores in the yrb took place in both fault basins and ne trending rifts between 135 and 124 ma

constraints on magma degassing beneath the far southeast porphyry cu au deposit philippines k silicate alteration in the far southeast fse porphyry cu au introduction deposit formed at 1 4 ma concentric to dikes of quartz diorite magmas become saturated with volatile components as porphyry at 2 km paleodepth the hydrothermal system consisted they ascend in the crust and either erupt or crystallize of magmatic hypersaline liquid and vapor at 550 c and 50 at depth saturated magmas that remain at depth exsolve mpa lithostatic pressure advanced argillic alteration formed at an aqueous fluid that forms a hydrothermal system on the same time over the deposit at 1 km paleodepth from acidic separation from the magma chamber burnham 1979 condensates of the vapor at 1 3 ma k silicate alteration was although part of the exsolved fluid a low density vapor overprinted by 350 c magmatic liquid 5 wt nacl equiv may discharge to the surface from passively degassing at hydrostatic pressure sericite alteration and much of the cu au volcanoes hedenquist 1995 part will remain at depth mineralization formed at this later stage evolution of the magmatic and this dense residual magmatic liquid may be asfluid composition was simulated with a magma chamber cryssociated with hydrothermal mineralization in the portallization model homogeneous crystallization during early stage phyry ore environment hedenquist lowenstern convection is assumed whereas at 50 vol crystals the chamber 1994 becomes stagnant and crystallizes from rim to core over a narrow in this paper we use evidence from a porphyry ore crystallization interval the model calculation based on a magma deposit in the philippines to determine the composition chamber with 2 km thickness at 6 km depth 150 mpa and of the fluid that exsolved from the deeper parent magma 800 c saturated melt composition at 30 vol crystals 5 the evolving composition of the magmatic fluid at the wt h2o 0 2 wt cl and dd of 40 can reproduce the depth of the ore body can then be used to place constraints chemical and isotopic compositions of the early and late magmatic on the nature of the evolved magma chamber far below fluids the most critical factor controlling the compositional evolution the porphyry ore body this approach differs from that of the model hydrothermal system is the transition from convective of other studies where a portion of the parent magma to stagnant magma chamber crystallization there is also a sharp chamber is available to study directly e g at yerington decrease in the rate of fluid exsolution associated with this transition nevada dilles 1987 which can account for the thermal collapse of the fse porphyry the far southeast fse porphyry cu au deposit system from k silicate to sericite alteration and overlying lepanto epithermal cu au ore body are

chemistry of inclusion fluids stockwork molybdenum deposits from questa new mexico hudson bay mountain and endako british columbia molybdenum mineralization and coextensive alteration in the questa hudson bay mountain and endako stockwork molybdenum deposits occur in single and composite veinlets which exhibit an ordered sequence of emplacement fluid inclusions in the deposits can be classified as liquid rich types a liquid vapor c liquid vapor halite d liquid vapor halite sylvite and e h 2 o rich liquid co 2 rich liquid co 2 vapor and as vapor rich type b study of these inclusions in the evolving fracture controlled alteration mineralization shows that type d inclusions are found with potassic alteration assemblages and type c inclusions occur with phyllic alteration assemblages salinities are divided into three compositionally distinct groups early fluorine rich biotitestable alteration at questa and hudson bay mountain is associated with hypersaline 40 70 nacl kcl type d inclusions which homogenize most frequently by halite dissolution homogenization temperatures uncorrected for pressure range from 320 degrees to 600 degrees c type d inclusions from both deposits fall along similar linear compositional trends in the nacl kcl h 2 o system regardless of temperature or behavior of homogenization the bulk of the molybdenite deposition coincides with quartz sericite pyrite alteration and with either moderate to high salinity 30 60 nacl equivalent type c inclusions which homogenize by halite dissolution or vapor disappearance or with low to moderate salinity 5 15 nacl equivalent type a inclusions evidence for local intermittent boiling is present throughout the questa and hudson bay mountain but not the endako hydrothermal systems homogenization temperatures for type a and c inclusions vary from 300 degrees to 600 degrees c with definite modes at about 390 degrees c the inclusion data are accepted as evidence for evolution from magmatic to meteoric hydrothermal conditions hypersaline type d solutions were precursors to the actual oreforming fluids and evolved directly from granitic source intrusions fluid reequilibration with the granitic intrusions and or dissolution of nacl precipitated by earlier hypersaline solutions along the halite trend are possible origins of the saline type c inclusion fluids salinity enhancement by boiling or mixing of hypersaline with meteoric fluids is not supported by the data pressures appear to have fluctuated between lithostatic and hydrostatic load and intermittent overpressures with adiabatic decompression are suggested

macflincor and its application to fluids in archean lode gold deposits abstract macflincor was developed to process laboratory data gathered on fluid inclusions and to calculate isochores for geologically important fluids composed of h2o c02 ch4 nacl and n2 within the program interactive diagrams are available to describe those chemical systems which cannot be adequately constrained numerically the user can choose from various published equations of state describing fluid behavior and can easily compare the results obtained by using different equations the program once the basic fluid parameters have been established allows the data to be used to determine the p t trapping conditions to evaluate possible pressure corrections and to compare different depths of formation based on the pressure calculations and given geothermal gradients for illustrative purposes macflincor has been utilized here to constrain different physical chemical parameters of fluid inclusions trapped in ore related quartz veins and breccias of archean lode gold deposits in western australia inferred pressures from individual deposits show a wide range of values which may be due to post entrapment modifications and or observational uncertainties including estimation of liquid vapor ratios

synthetic fluid inclusions in natural quartz ii application to pvt studies synthetic fluid inclusions have been used to determine volumetric properties of h2o and a 20 wt kcl solution from 300 700 c and 1 3 kb comparison of results obtained for h2o with previously published data indicates that the synthetic fluid inclusion technique provides pvt data that are within a few percent of those obtained from conventional pvt studies this technique thus provides a fast relatively simple means of determining pvt properties of many fluids of geologic interest

distribution of porphyry deposits in the eurasian continent and their corresponding tectonic settings in the eurasian continent there are three huge metallogenic belts of cu and mo porphyry deposits comprising the paleozoic central asian ore belt in the north the tethyan eurasian ore belt of jurassic to cenozoic age in the southwest and the east margin ore belt of the eurasian continent of jurassic to cretaceous age in the east the latter is considered to be part of the vast circum pacific ore belt some of the main features of the spatial temporal distribution of cu and mo porphyry systems and related geodynamic processes of the three metallogenic belts are described in particular the key role of postsubduction related porphyry ore systems is emphasized comprising collisional and post collisional cu mo porphyry deposits during the geological history of the eurasian continent the recurrent feature of these ore systems and related felsic rocks is their derivation from partial melting of stagnant or residual oceanic slabs and mixing with a variable amount of crustal material during magma ascent to shallower levels 2013 published by elsevier ltd

cathodoluminescence fluid inclusion and stable c o isotope study of tectonic breccias from thrusting plane of a thin skinned calcareous nappe basal hydraulic breccias of alpine thin skinned mura nappe were investigated by means of cathodoluminescence petrography stable isotope geochemistry and fluid inclusions analysis our study reveals an unusual dynamic fluid regime along basal thrust plane during final episode of the nappe emplacement over its metamorphic substratum basal thrusting fluids enriched in 18o silica alumina alkalies and phosphates were generated in the underlying metamorphosed basement at epizonal conditions corresponding to the temperatures of 400 450 c the fluids fluxed the tectonized nappe base leached evaporite bearing formations in hangingwall whereby becoming oversaturated with sulphates and chlorides the fluids further modified their composition by dedolomitization and isotopic exchange with the host carbonatic cataclasites newly formed mineral assemblage of quartz phlogopite albite potassium feldspar apatite dravite tourmaline and anhydrite precipitated from these fluids on cooling down to 180 200 c finally the cataclastic mush was cemented by calcite at ambient anchizonal conditions recurrent fluid injections as described above probably enhanced the final motion of the mura nappe