fluid inclusion characteristics and geological significance of the dajinshan w sn polymetallic deposit in yunfu guangdong province abstract the dajinshan tungsten tin polymetallic deposit is a quartz vein type ore deposit located in western guangdong province the ore bodies show a fairly simple shape and mainly occur as tungsten tin polymetallic bearing sulfide quartz veins including quartz vein quartz greisens and sulfide quartz veins and their distribution is spatially related to dajinshan granitoids the formation of the deposit experienced three stages a wolframite molybdenite quartz stage a wolframite cassiterite sulfide quartz stage and a fluorite calcite carbonate stage based on detailed petrographic observations we conducted microthermometric and raman microspectroscopic studies of fluid inclusions formed at different ore forming stages in the dajinshan tungsten tin polymetallic deposit identifying four dominant types of fluid inclusions aqueous two phase inclusions co2 bearing inclusions solid or daughter mineral bearing inclusions and gas rich inclusions the gas compositions of ore forming fluids in the dajinshan tungsten tin polymetallic deposit are mostly co2 ch4 and h2o the hydrogen oxygen and sulfur isotopic data imply that the ore forming fluids in the dajinshan tungsten tin polymetallic deposit were mainly derived from magmatic fluids mixed with meteoric water in the ore formation process these results indicate that the fluid mixing and boiling led to the decomposition of the metal complex in ore forming fluids and ore deposition

gold bearing mesothermal veins from the gubong mine cheongyang gold district republic of korea fluid inclusion and stable isotope studies the gubong deposit consists of five massive gold bearing mesothermal quartz veins that fill fractures oriented northeast and northwest along fault shear zones over an area of 14 km2 in precambrian metasedimentary rocks of the gyeonggi massif the veins are divided into three groups based on their orientation and location they have a ribbon texture that is interpreted to result from repeated hydraulic fracturing events mineral deposition was associated with hydrothermal fluid overpressuring within and below the active fault shear zones the vein mineralogy and paragenesis of the veins allow two separate discrete mineralization episodes to be recognized separated by a major faulting event the ore minerals are contained within quartz and calcite associated with fracturing and healing of veins that occurred during both mineralization episodes wall rock alteration minerals during stage i the main ore stage include sericite chlorite and minor pyrite and carbonates sulfide minerals deposited along with electrum during this stage include arsenopyrite pyrite pyrrhotite sphalerite marcasite chalcopyrite galena and argentite electrum also was deposited during stage ii mineralization in the one group of veins along with pyrite sphalerite chalcopyrite and galena but the second stage of deposition in other veins was barren petrographic examination of textural relationships among sulfides fluid inclusions microfracturing and quartz shows chronological and genetic relationships between gold deposition and fluid entrapment systematic studies of fluid inclusions in stage i vein indicate two contrasting events a relatively high temperature 203 432 c and pressure 943 2 098 bars event related to early sulfide deposition and associated with h2o co2 ch4 nacl n2 fluids less than about 13 4 wt nacl and a lower temperature 202 399 c and pressure 670 850 bars late sulfide depositional event involving h2o nacl fluids 3 9 17 3 wt nacl the h2o nacl fluid involved in ore related stage ii mineralization had a salinity of 0 4 to 4 2 wt percent nacl and a homogenization temperature of 201 to 378 c the calculated sulfur isotope compositions of hydrothermal fluids from the stage i veins 34sh2s 3 5 10 5 indicate that ore sulfur was derived mainly from a magmatic source but also in part from sulfur contained in the host rocks the calculated and measured oxygen and hydrogen isotope compositions of the ore forming fluids stage i 18oh2o 1 1 9 0 d 92 to 21 stage ii 18oh2o 0 1 to 0 3 d 95 to 93 indicate that the fluids were derived from magmatic and or deep seated metasedimentary rocks stage i and evolved by mixing with local meteoric water stage ii by limited water rock exchange and by degassing during mineralization in uplift zones the h2o nacl fluids involved in the stage i development of these veins represent fluids that evolved either through unmixing of h2o co2 ch4 nacl n2 fluids following a decrease in fluid pressure or through mixing with deeply circulating meteoric waters possibly as a result of uplift and or unloading during mineralization the h2o nacl fluid involved in stage ii was derived from meteoric water early deposition of gold in stage i was caused by a decrease in sulfur fugacity h2s loss that accompanied the immiscible separation of carbonic vapor from h2o co2 ch4 nacl n2 fluids gold in late stage i and stage ii veins was precipitated from h2o nacl fluids by cooling and by dilution caused by mixing with meteoric water

origin and evolution of the ore forming fluids of the erdaogou and xiaobeigou gold deposits jiapigou gold province ne china abstract the jiapigou gold province located in the eastern part of the northern margin of the north china craton includes the erdaogou and xiaobeigou gold deposits which are hosted in amphibolites amphibolitic gneisses and tonalite trondhjemite granodiorite gneisses of the jiapigou group the gold deposits occur as gold bearing quartz veins and disseminated and veinlet type mineralization orebodies are strictly controlled by nw se trending secondary faults four stages of mineralization have been identified in the erdaogou gold deposit 1 milky quartz 2 pyrite quartz 3 native gold quartz pyrite and 4 quartz carbonate in the xiaobeigou gold deposit five stages of mineralization have been identified 1 milky quartz 2 pyrite sericite quartz 3 pyrite quartz 4 native gold quartz pyrite and 5 quartz carbonate three fluid inclusion populations have been identified in the deposits co 2 h 2 o c type aqueous w type and pure co 2 pc type c type w type and pc type fluid inclusions are observed in the erdaogou gold deposit whereas c type and w type fluid inclusions are dominant in the xiaobeigou gold deposit microthermometric data indicate that the fluid inclusions of the deposits homogenize at 128 370 c 0 18 15 35 wt nacl equivalent pressures estimated from fluid inclusion data cluster into two populations at 140 165 mpa and 60 80 mpa indicating that mineralization occurred at a depth of 5 1 8 0 km the o isotope ratios 18 o h2o of ore forming fluids in the xiaobeigou gold deposit range from 1 84 to 1 14 with d of 102 whereas late stage fluids have 18 o h2o of 9 40 to 9 20 and d of 78 integrated c h o s pb isotope data suggest that the initial ore forming fluids of the deposits consisted of magmatic water produced by the partial melting of lower crustal material containing a mantle component water rock interaction occurred in the early mineralization stage fluid immiscibility resulted in rapid gold deposition regional and deposit geology fluid inclusions and stable isotopes indicate that the erdaogou and xiaobeigou gold deposits are mesothermal related to subduction of the paleo pacific plate the jiapigou gold province has significant potential for deep seated mineralization and should be the focus of future exploration

evolution of metamorphic fluids in shear zones the record from the emeralds of habachtal tauern window austria fluid inclusions in emeralds from the habachtal central tauern window have been studied by microthermometry results allow a detailed reconstruction of trapping history and evolution of the metamorphic fluids during the middle alpine tauernkristallisation metamorphic event and some of the subsequent cooling period five different types of fluid inclusions corresponding to at least five trapping periods have been distinguished in general the earliest primary type 1 inclusions which occur as negative crystals or thin long tubes are represented by low salinity 10 wt nacl equivalent aqueous fluids with or without co2 with up to xco2 0 04 later primary type 2 inclusions are distinguished by different morphologies and distribution patterns lower salinity co2 free brines and co2 bearing denser inclusions with higher co2 contents up to xco2 0 11 are characteristic of this stage the type 2 inclusions may also occur as pseudosecondary arrays the effects of necking have been studied and found to be considerable in the type 1 primary inclusions this mechanism has occasionally resulted in the appearance of almost pure co2 fluids the possibility of fluid immiscibility has been examined and rejected for the apparent coexistence of primary brine and co2 bearing inclusions instead mixing of fluids which fluctuated between two different compositions is proposed the fluctuation was probably due to the sequence of hydration reactions during the tauernkristallisation maximum trapping pressures 3 6 kbar obtained for stage 1 of the tauernkristallisation are thought to represent a situation where sublithostatic fluid pressures exested in shear zones during the crystallisation period of many of the emerald cores and coexisting biotite and actinolite maximum fluid pressures of 7 kbar were obtained from the type 2 inclusions this is similar to pressure estimates obtained from mineral equilibria at least four phases of deformation are indicated by the trapping history a pressure temperature time path for the tauernkristallisation and the subsequent cooling uplift period has been constructed for the habachtal area using the maximum pressure estimates obtained in this work together with previously existing data in the cooling period fluid pressures lower than the lithostatic load again prevailed this difference about 1 2 kbar was probably due to late stage fracturing and or the development of an open system at least two more phases of minor deformation and three more stages of entrapment have been defined for this period during this time fluids gradually evolved towards more co2 poor and less saline compositions the present work shows that the possibility of fluctuations in fluid pressures must be considered seriously when attempting to define the pt cooling path from fluid inclusions in metamorphic rocks especially those in shear zones postulations of retrograde pt paths based on fluid inclusions alone may result in pressure estimates which are too low

physico chemical conditions of ore forming fluids associated with genesis of the kalahari goldridge deposit kraaipan greenstone belt south africa abstract the kalahari goldridge deposit is an archaean lode gold deposit in the northwest province of south africa sub greenschist facies banded iron formation bif dipping approximately 65 e host the gold mineralisation the d zone orebody of the deposit is stratabound and varies from about 15 to 45 m in width along a strike length of approximately 1 5 km mineralisation is associated with two subhorizontal quartz carbonate groups of veins iia and iib which dip approximately 20 to 40 w group iia are ladder veins preferentially developed in centimetre scale fe rich mesobands group iib consists of large quartz carbonate veins which crosscuts the entire orebody and extends into the footwall and hanging wall in places fluids responsible for gold deposition have low salinity h 2 o co 2 ch 4 compositions with elevated ch 4 contents attributed to localised hydrolysis reactions with interbedded carbonaceous sediment and ore fluid the fluid has a significant co 2 content x co 2 0 06 to 0 19 and salinities below 7 0 wt nacl equivalent average of 3 5 and 3 0 wt nacl equiv for the first and second episodes of the mineralisations respectively calculated values of f o 2 range from 10 33 8 to 10 30 5 bars i e 4 to 5 log units below the qfm buffer boundary indicate strongly reducing conditions of the ore fluid at deposition calculated total sulphur contents in the ore fluid range from 0 014 to 0 051 m and are consistent with the range 10 3 5 to 10 1 m reported for sub amphibolite facies ore fluids the close association between sulphides and gold together with the nature of the fluid indicate that au was carried in solution as a au hs 2 complex extensive epigenetic replacement of magnetite and chlorite in bif and other meta pelitic sediments in the deposit by sulphides and carbonates indicates that interaction of a co 2 and h 2 s bearing fluid with the fe rich host rocks facilitated au precipitation by destabilisation of the reduced gold bisulphide complexes local f o 2 gradients may also account for gold precipitation within carbonaceous metasedimentary rocks evidence from light stable isotopes and fluid inclusions suggests that the mineralised veins crystallised from a homogeneous fluid under similar physicochemical conditions during the two episodes of mineralisation deposition occurred at temperatures ranging from 350 to 400 c and at fluid pressures ranging from 0 6 to 2 0 kbar calculated isotopic values of the ore fluid at these p t conditions are in the following ranges 18 o 6 7 to 10 5 13 c 6 0 to 8 0 and 34 s 1 7 to 4 0 these data do not offer conclusive evidence for the source of mineralising fluid in the d zone at the kalahari goldridge deposit as they overlap the range suggested for fluid derived from prograde metamorphism and magmatic hydrothermal activity

low thermal gradient hercynian metamorphism in the eastern pyrenees fluids with compositions in the system co2 h2o nacl were trapped in quartz veins enclosed in low grade metamorphic rocks chlorite zone on the southern flank of the canigo massif eastern pyrenees the veins which also contain arsenopyrite crystals were formed contemporaneously with the main hercynian foliation and metamorphism volumetric properties of the fluid and the results of arsenopyrite geothermometry suggest p t trapping conditions of 4 6 6 kbar and 450 530 c this implies that an episode of metamorphism with an average geothermal gradient of 25 c km 1 occurred during the main deformation event this episode preceded the low p high t metamorphism described around domes and to date considered as characteristic of the hercynian orogeny in the pyrenees

multi scale dynamical analysis msda of sea level records versus pdo amo and nao indexes herein i propose a multi scale dynamical analysis to facilitate the physical interpretation of tide gauge records the technique uses graphical diagrams it is applied to six secular long tide gauge records representative of the world oceans sydney pacific coast of australia fremantle indian ocean coast of australia new york city atlantic coast of usa honolulu us state of hawaii san diego us state of california and venice mediterranean sea italy for comparison an equivalent analysis is applied to the pacific decadal oscillation pdo index and to the atlantic multidecadal oscillation amo index finally a global reconstruction of sea level jevrejeva et al in geophys res lett 35 l08715 2008 and a reconstruction of the north atlantic oscillation nao index luterbacher et al in geophys res lett 26 2745 2748 1999 are analyzed and compared both sequences cover about three centuries from 1700 to 2000 the proposed methodology quickly highlights oscillations and teleconnections among the records at the decadal and multidecadal scales at the secular time scales tide gauge records present relatively small positive or negative accelerations as found in other studies houston and dean in j coast res 27 409 417 2011 on the contrary from the decadal to the secular scales up to 110 year intervals the tide gauge accelerations oscillate significantly from positive to negative values mostly following the pdo amo and nao oscillations in particular the influence of a large quasi 60 70 year natural oscillation is clearly demonstrated in these records the multiscale dynamical evolutions of the rate and of the amplitude of the annual seasonal cycle of the chosen six tide gauge records are also studied

fluid inclusion characteristics of hematite bearing quartz vein from the daenam mine republic of korea abstract the daenam mine which produced over 9250 tons of iron oxide ore from 1958 to 1962 is situated in the early cretaceous yeongyang subbasin of the gyeongsang basin it consists of two lens shaped hematite bearing quartz veins that occur along faults in cretaceous leucocratic granite the hematite bearing quartz veins are mainly composed of massive and euhedral quartz and hematite with minor amounts of pyrite pyrrhotite mica feldspar and chlorite fluid inclusions in quartz can be divided into three main types co2 rich co2 h2o and h2o rich hydrothermal fluids related to the formation of hematite are composed of either h2o co2 nacl ch4 homogenization temperature 262 455 c salinity

geological and geochemical constraints on the genesis of the bengge gold deposit in the yidun terrane se tibet abstract the bengge gold deposit is one of a small number of deposits in the zhongdian muli region which is part of the southern segment of the yidun terrane in the eastern tibetan plateau the deposit is hosted in a late triassic alkaline igneous complex comprising mainly biotite pyroxene syenite and quartz syenite emplaced into triassic slate these syenites show phyllic alteration with mineral association of quartz sericite pyrite carbonate the main gold mineralization occurs in fault zones as gold sulfide quartz veins in altered syenite as telluride in veinlets and as fissure filling gold in disseminated pyrite four stages of veins are recognized sheeted k feldspar quartz magnetite veins dikes stage i quartz carbonate k feldspar veins with sericite quartz pyrite alteration haloes stage ii polymetallic sulfide telluride sericite quartz veins with pervasive phyllic alteration stage iii and quartz carbonate stibnite veins stage the stage ii and iii veins are closely related to gold mineralization 40ar 39ar dating of hydrothermal sericites from the phyllic alteration zone which are intergrown with gold bearing pyrite and telluride yielded an age of 126 ma indicating the mineralization event occurred in the cretaceous extensional setting raman spectroscopy and microthermometry study for fluid inclusions in quartz from stage ii revealed heterogeneous trapping of low salinity 0 14 6 63 wt nacl equivalent and mesothermal 270 300 c co2 h2o nacl ore forming hydrothermal fluids the calculated fluid trapping pressures range mainly from 750 to 850 bar 18o values of quartz from the gold mineralization stage stage ii vary between 15 21 and 19 35 the 18o values for waters in equilibrium with quartz vary from 6 96 to 10 73 which are consistent with values for magmatic waters we propose that the auriferous fluids were derived from an underlying intrusion during the cretaceous the geological characteristics low salinity and mesothermal co2 h2o nacl fluids and the magmatic source of the ore forming fluids all support the hypothesis that the bengge deposit is an intrusion related gold deposit

fluid regimes during late stages of a continental collision physical chemical and stable isotope measurements of fluid inclusions in fissure quartz from a geotraverse through the central alps switzerland fluid evolution during neo alpine metamorphism during late stages of the continental collision between europe and africa was studied by analyzing fluid inclusions in alpine fissure quartz collected in forty nine localities along a geotraverse through the central alps switzerland the methods employed include microthermometry micro raman spectroscopy k na thermometry and stable isotope analysis early fluid inclusions provide evidence of close to peak metamorphic temperatures of the late tertiary or neo alpine metamorphic event fluid composition evolved along the geotraverse from north to south as follows higher hydrocarbons were dominant in the low and medium grade diagenetic zones methane was the main volatile in the high grade diagenetic and low grade anchizone water dominated in the highgrade anchizone and low grade epizone with co2 10 mol in the high grade epizone and in the mesozone higher hydrocarbons and ch4 were the products of kerogen maturation and cracking of preexisting petroleum large water supplies originated from the dehydration of cooler metasedimentary rocks that were overthrust by crystalline basements of the lepontines aar and gotthard massifs carbon isotope analyses suggest that the co2 component was derived from oxidation of graphitic matter especially in the vicinity of sulfate bearing metasediments and from decarbonation reactions in the aar and gotthard massifs as well as in the helvetic axen nappe and its underlying north helvetic flysch high fluid pressures prevailed and favored nappe transport by contrast in the southern lepontine area very low early fluid pressures were probably related to dry rocks and scarce metasediments and to high geothermal gradients that resulted from intense uplift and erosion between 26 and 18 ma retrograde fluid evolution was recorded by a succession of fluid inclusion populations in each alpine fissure it was controlled by uplift and cooling and characterized by decreasing contents of volatiles and an increase in 18o of host quartz tectonic activity led to episodic pressure drops of at least 0 5 to 2 kbar and promoted fluid unmixing channelized flow and rapid growth of skeletal quartz channelized rather than pervasive fluid migration at temperatures 450 c and under conditions of brittle deformation is documented by episodic increases in salinity and by fluid flushing through the massifs there is stable isotope evidence for involvement of meteoric water only in late crystallizing quartz formation of alpine fissures and fissure minerals was the result of a unique coincidence of late continental collision 450 c fluid expulsion from overthrust metasediments uplift and erosion

ice core data evidence for a prominent near 20 year time scale of the atlantic multidecadal oscillation 1 using five ice core data sets combined into a single time series we provide for the first time strong observational evidence for two distinct time scales of arctic temperature fluctuation that are interpreted as variability associated with the atlantic multidecadal oscillation amo the dominant and the only statistically significant multidecadal signal has a time scale of about 20 years the longer multidecadal variability of 45 85 years is not well defined and none of the time scales in this band is statistically significant we compare these observed temperature fluctuations with results of coupled climate model simulations hadcm3 and gfdl cm2 1 both the 20 25 year and a variable longer amo time scale are prominent in the models long control runs this periodicity supports our conjecture that the observed ice core fluctuations are a signature of the amo the robustness of this short time scale period in both observations and model simulations has implications for understanding the dominant amo mechanisms in climate

fluid immiscibility in natural processes use and misuse of fluid inclusion data ii interpretation of fluid inclusion data in terms of immiscibility abstract phase equilibrium analysis of the relevant systems together with the application of the principles of chemical equilibrium put severe constraints on the interpretation of fluid inclusion data in terms of immiscibility in part i following from that point the major limits on the accuracy and even the validity of fluid inclusion quantitative data and their interpretation in terms of fluid composition and density are briefly discussed the practical implications of the general constraints temperature pressure topology of the fluid systems are envisaged emphasis is laid on some important consequences such as the use of isochore intercepts and the possible resulting interpretation of fluid mixing rather than unmixing the case of highly saline inclusions the identification and interpretation of heterogeneous trapping the composition and density constraints on coexisting fluids are presented and illustrated by natural examples taking into account all the measurable parameters in fluid inclusions volume temperature and nature of phase transitions more or less complete individual spectroscopic analyses all the available experimental data and all the theoretical constraints may be long and difficult however it is most generally very informative and productive although part of these data is often sufficient to deny unmixing nevertheless a final example on metamorphic fluids demonstrates how such an approach can prove and also characterize a fluid unmixing during a geologic process

is there a 60 year oscillation in global mean sea level 1 we examine long tide gauge records in every ocean basin to examine whether a quasi 60 year oscillation observed in global mean sea level gmsl reconstructions reflects a true global oscillation or an artifact associated with a small number of gauges we find that there is a significant oscillation with a period around 60 years in the majority of the tide gauges examined during the 20th century and that it appears in every ocean basin averaging of tide gauges over regions shows that the phase and amplitude of the fluctuations are similar in the north atlantic western north pacific and indian oceans while the signal is shifted by 10 years in the western south pacific the only sampled region with no apparent 60 year fluctuation is the central eastern north pacific the phase of the 60 year oscillation found in the tide gauge records is such that sea level in the north atlantic western north pacific indian ocean and western south pacific has been increasing since 1985 1990 although the tide gauge data are still too limited both in time and space to determine conclusively that there is a 60 year oscillation in gmsl the possibility should be considered when attempting to interpret the acceleration in the rate of global and regional mean sea level rise

recent global sea level acceleration started over 200 years ago 1 we present a reconstruction of global sea level gsl since 1700 calculated from tide gauge records and analyse the evolution of global sea level acceleration during the past 300 years we provide observational evidence that sea level acceleration up to the present has been about 0 01 mm yr2 and appears to have started at the end of the 18th century sea level rose by 6 cm during the 19th century and 19 cm in the 20th century superimposed on the long term acceleration are quasi periodic fluctuations with a period of about 60 years if the conditions that established the acceleration continue then sea level will rise 34 cm over the 21st century long time constants in oceanic heat content and increased ice sheet melting imply that the latest intergovernmental panel on climate change ipcc estimates of sea level are probably too low

a 20th century acceleration in global sea level rise 1 multi century sea level records and climate models indicate an acceleration of sea level rise but no 20th century acceleration has previously been detected a reconstruction of global sea level using tide gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea level rise but no significant acceleration over this period here we extend the reconstruction of global mean sea level back to 1870 and find a sea level rise from january 1870 to december 2004 of 195 mm a 20th century rate of sea level rise of 1 7 0 3 mm yr 1 and a significant acceleration of sea level rise of 0 013 0 006 mm yr 2 this acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed if this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm consistent with projections in the ipcc tar

geology mineralization and fluid inclusion characteristics of the kensu w mo skarn and mo w cu au alkalic porphyry deposit tien shan kyrgyzstan the kensu deposit is located within a large metallogenic belt of w mo cu mo w au au and pb zn deposits along the late paleozoic active continental margin of tien shan the deposit is related to a small late carboniferous to early permian multiphase gabbro monzonite syenite granite pluton representing an alkaline potassic shoshonitic suite the igneous rocks are related to a deep rooted magmatic source but the pluton emplacement corresponds to shallow porphyry levels the deposit represents an example of a complex w rich alkalic magmatic hydrothermal system that complements the typical mineral deposits related to shoshonitic igneous suites it contains large bodies of w mo skarn of the oxidized type with abundant andradite garnet scapolite k na feldspars and fe oxides magnetite hematite the skarns are overprinted and surrounded by extensive halos of stockwork disseminated porphyry style mo w mo w cu pb zn and au w mineralization with propylitic chlorite amphibole epidote dominated and phyllic quartz sericite carbonate sulfide alteration assemblages consistent with the oxidized nature of the major mineral assemblages the deposit may represent the oxidized lithophile w mo cu au metallogenic type the hydrothermal stages alternate with magmatic phases and fluid inclusion data show the predominance of high temperature 550 450 c high pressure 1 200 700 bars and high salinity 60 45 wt nacl equiv magmatic hydrothermal fluid at prograde and early retrograde skarn stages with its possible direct exsolution from crystallizing magma the general trend of cooling and dilution was complicated by the influx of higher temperature and higher salinity fluid that correlates to the intrusion of quartz monzonite and the initial stages of its degassing and cooling this more advanced phase of magmatic differentiation likely corresponded to the enrichment of residual melt and related magmatic fluids in w and mo intense fluid boiling and phase separation triggered the deposition of molybdoscheelite in skarns that formed at t 625 500 c and p 510 300 bars and continued to a nonboiling fluid at t 420 370 c and p 1 150 750 bars mineralization in propylitic alteration zones was formed by highly to moderately saline nonboiling fluids late quartz sericite carbonate sulfide stage involved both high to low salinity aqueous fluids and co2 rich fluids under decreasing temperature from 400 c to 200 300 c and varying pressure from 1 200 bars to 750 600 bars

fluid inclusion microthermometry and the p t evolution of gold bearing hydrothermal fluids in the niuxinshan gold deposit eastern hebei province ne china niuxinshan is a typical example of the numerous mesothermal gold deposits formed during mesozoic tectono magmatic reactivation of the archean north china craton in eastern hebei province gold occurs in quartz sulfide lodes in archean amphibolites and also in greisen zones in the mesozoic niuxinshan granite stock four mineralization stages can be recognized from early to late 1 quartz k feldspar 2 quartz pyrite 3 quartz polysulfide and 4 quartz carbonate gold mineralization mainly occurs in stages 2 and 3 fluid inclusions in quartz and fluorite from greisen zones in the niuxinshan granite and inclusions in vein quartz and sphalerite from stages 1 to 3 in the amphibolites have been studied by microthermometry three compositional types of inclusions are recognized type 1 tp1 are h2o co2 bearing inclusions and include primary tp1 p and secondary tp1 s inclusions these are found in quartz and fluorite from the greisen zones as well as in vein quartz and sphalerite from stages 1 to 3 the tp1 p inclusions are considered to represent the gold bearing hydrothermal fluids type 2 tp2 s are secondary h2o co2 solid phase inclusions in fluorite from the greisen zones type 3 tp3 s are secondary aqueous inclusions with a solid phase which coexist with the tp2 s in fluorite from the greisen zones the tp1 p inclusions show variable vco2 commonly 0 3 to 0 6 and xco2 values mainly 0 1 to 0 4 the salinities of inclusions cluster around 3 to 11 wt nacl equivalent and their homogenization temperatures to the liquid phase th l fall dominantly in the range of 260 to 360 c the compositional variations of inclusions in stage 1 probably result from exsolution of magmatic fluids at various stages immiscibility or boiling of the fluids can be ruled out the compositional variations of inclusions in the greisen zones and in vein stages 2 and 3 are attributed to cooling mixing dilution and necking down of the fluids the tp1 s and tp2 s inclusions show salinities of 3 to 6 wt nacl equivalent and xco2 values of 0 04 to 0 17 th l clusters at 240 to 260 c the tp3 s inclusions have salinities of 3 to 6 wt nacl equivalent and th l of 170 to 240 c isochoric reconstructions combined with oxygen and sulfur isotope geothermometry of mineral pairs give trapping p t conditions for the gold bearing fluids the greisen zones formed at 310 to 460 c and 1 3 to 3 7 kbar stage 1 veins at 300 to 430 c and 1 2 to 3 7 kbar stage 2 veins at 290 to 380 c and 1 to 3 kbar stage 3 veins at 250 to 350 c and 1 to 3 kbar h2o co2 fluids with low to moderate salinities and moderate to high densities 0 66 to 1 01 g cm3 dominated at early mineralization stages and evolved towards h2o richer and co2 and less saline fluids through time the retrograde p t evolution probably resulted from regional uplift and cooling of gold bearing hydrothermal fluids the gold bisulfide complex was dominant in the fluids during mineralization and gold deposition was mainly induced by decreases of temperature and pressure as well as destabilization of the bisulfide complex during sulfidization of wall rocks

the role of vapor in the transportation of tin in hydrothermal systems experimental and case study of the dachang deposit china abstract in order to understand metal transportation by vapor which was found by detecting volcanic gases authors performed vapor liquid separation experiments at sub critical states the experiments indicate that the metal transportation by vapor of hydrothermal systems is derived from the liquid and vapor separation occurred in the transitions from a supercritical state to liquid vapor immiscibility field at a sub critical state of metal bearing hydrothermal fluids of nacl h 2 o the data of the fluid inclusions in minerals suggest that major ores were deposited in the temperature range from 300 to 500 c in hydrothermal systems the study on fluid inclusions in minerals of hydrothermal deposits provides evidence that the principal ore minerals of the deposits precipitated in the period from a supercritical state to a sub critical state of the nacl h 2 o a case study of fluid inclusions in minerals of the dachang tin deposit china indicates the evolution of ore forming fluids occurred in the l v immiscibility field of nacl h 2 o the experiments of liquid and vapor two phase immiscibility field of a tin bearing fluid show that sn was redistributed in vapor phase and liquid phase when the tin bearing supercritical fluid nahco 3 hcl h 2 o separates into liquid and vapor phases for a decreasing in temperature or pressure the experiments prove that tin could be transported by vapor phase in hydrothermal systems

reply to comment by a e williams jones and s a wood on fluid inclusion studies of the rodeo de los molles ree and th deposit las chacras batholith central argentina this paper is in response to a rebuttal made against these authors original research on hydrothermal sytem mineralization of rare earth elements ree the original text was regarding physiochemical characteristics of bastnaesite and fluorite which are the principal ree minerals in hydrothermal environments this paper reviews all the procedures regarding the temperature and pressure of formation calculations reaching in the authors previous research

fluid inclusion microthermometry in be ta li sn bearing pegmatites from the borborema province northeast brazil abstract fluid inclusions in be ta li sn bearing pegmatites have been reported in the literature as hypersaline aqueous brines or low salinity aqueous or aqueous carbonic fluids the evolution paths of volatile fluids in equilibrium with the different crystallizing phases of rare element pegmatites do not seem to be unique the aim of this work is to contribute to this discussion on the basis of fluid inclusion information from the borborema pegmatite province bpp in northeast brazil some well known heterogeneous be ta li sn mineralized pegmatites of this province were systematically sampled along cross sections with the purpose of studying the fluid inclusions in the different pegmatite zones i muscovite rich contact zone ii homogeneous or graphic pegmatite iii blocky feldspar zone and iv quartz core the observed fluid inclusions mainly in quartz were almost always secondary or pseudosecondary grouped along healed fractures with random orientation even some trails paralleling quartz grain limits were not undoubtedly primary almost all these fluid inclusions were filled with low salinity aqueous or aqueous carbonic fluids primary inclusions were recognized only in some well formed crystals from druses with erratic distribution in the pegmatites microthermometric data from these samples confirm that the various crystallizing phases of the pegmatites were in equilibrium with low salinity aqueous or aqueous carbonic fluids with insignificant n 2 or ch 4 contents with frequent accidentally trapped solids the various types of primary inclusions found in these crystals compare well with the types of secondary inclusions of the samples from the systematic cross sections the relative age of the crystals hosting primary fluid inclusions the relative age of primary inclusion types in successive crystal growth zones the relative age of secondary fluid inclusion trails and the corresponding microthermometric data allowed to establish the most probable evolution of the fluid characteristics during pegmatite crystallization an early low salinity aqueous carbonic fluid with co 2 contents of 20 mol was present during the crystallization of early minerals such as garnet and tourmaline of the border zone and graphic quartz beryl manganotantalite and blue tourmaline of zones ii and iii the end of zone iii crystallization occurred in the presence of a low salinity aqueous fluid with very low co 2 contents as indicated by inclusions in the smoky core of quartz crystals at the limit between zones iii and iv later aqueous fluids barren in co 2 and with salinities increasing from 5 to 20 coexisted with the formation of the pegmatite nucleus and replacement bodies as indicated by inclusions in the border of these crystals and in euclase the estimated trapping conditions of 3 5 kbar and 580 c for the earliest inclusion types agree with the regional metamorphic conditions and with the known liquidus conditions of rare element bearing pegmatite crystallization the trapping conditions of inclusions in euclase and coexisting quartz crystal rims in the pegmatitic core at 3 5 kbar and 400 c are slightly below the conditions admitted for the solidus of rare element pegmatites and indicate an isobaric cooling during pegmatite crystallization

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

geochemistry of fluid inclusions from the mcintyre hollinger gold deposit timmins ontario canada type 1 h 2 o co 2 type 2 h 2 o co 2 type 3 ch 4 co 2 h 2 o and type 4 ch 4 fluid inclusions type 1 type 3 and some type 2 inclusions are primary or pseudosecondary in origin whereas type 4 and most type 2 inclusions are secondary the primary or pseudosecondary type 1 and 2 inclusions homogenized at temperatures of 220 degrees to 385 degrees c secondary type 2 inclusions homogenized at 160 degrees to 215 degrees c crushing tests confirm the presence of co 2 in samples with type 1 and 2 inclusions visually estimated x co2 values in type 1 inclusions range from 3 to 24 mole percent with bulk molar volumes of 19 to 28 cm 3 mole mineralizing fluids were at equilibrium with graphite at temperatures of 380 degrees to 480 degrees c and pressures of 1 to 3 kb calculated oxygen fugacities lie near the quartz fayalite magnetite buffer the mineralizing fluids differ compositionally from fluids in other types of ore deposits but resemble fluids derived from metamorphic rocks and deep level felsic intrusions modified journal abstract

isotope systematics and fluid inclusion studies of the qiyugou breccia pipe hosted gold deposit qinling orogen henan province china implications for ore genesis abstract the qiyugou gold deposits henan province are hosted in breccia pipes within the xiong er terrane qinling orogen on the southern margin of the north china craton in these deposits three paragenetic assemblages have been recognized an early k feldspar epidote quartz pyrite a middle quartz polymetallic sulfide and a late quartz carbonate adularia in this paper we review and interpret fluid inclusion and stable and radiogenic isotopic data of host rocks and ores fluid inclusions in quartz and calcite include water rich co 2 rich and daughter crystal bearing the co 2 rich and daughter mineral bearing fluid inclusions are common in the early stage quartz and absent in the late stage quartz and calcite which only contain water rich fluid inclusions accordingly the early stage ore fluids are magmatic in origin and characterized by high temperature 350 c high salinity 30 wt nacl equiv and are co 2 rich fluid boiling in the middle ore stage resulted in co 2 release decreasing oxygen fugacity and rapid precipitation of ore materials the late stage fluids have low temperature low salinity are co 2 poor and lack daughter minerals these fluids are probably sourced from meteoric water h o c isotope systematics confirm that the ore fluid system evolved from magmatic to meteoric the carbon and lead isotope ratios indicate that the meso neoproterozoic sequence south of the xiong er terrane was the likely source of the ore forming materials the qiyugou breccia pipes and their associated gold ores were emplaced during an extensional regime following a transition from collision to rifting tectonics linked to collision and subduction of the yangtze plate beneath the north china craton geochronological studies show that mesozoic magmatism in the region occurred between the triassic and cretaceous the triassic to jurassic magmas were mostly derived from partial melting of ancient crust whereas the cretaceous magmas show juvenile signatures indicating mantle derived components processes of fragmentation of lithospheric roots crustal and lithospheric thinning extension and rifting were probably associated with the subducting pacific izanagi plate these crust mantle geodynamic processes were responsible for the development of anorogenic granitic melts that interacted with the meso neoproterozoic volatile rich sedimentary successions producing a flow of gas rich hydrothermal fluids that resulted in the emplacement of the qiyugou auriferous breccia pipes we conclude that the qiyugou gold deposits are intrusion related explosive breccia pipe type that evolved from hypothermal through mesothermal to epithermal

determining phase volumes of mixed co 2 h 2 o inclusions using microthermometric measurements a new graphical technique has been developed which permits the composition and volumetric properties of mixed co2 h2o inclusions to be determined using microthermometric measurements if the values of only two of the four variables 1 density of the co2 phase derived from the temperature and mode of partial homogenization 2 temperature and mode of total homogenization 3 volume fraction of the co2 phase at 40 c and 4 molar fraction of co2 of a mixed co2 h2o inclusion are known the values of the other two variables can be taken from a diagram depicting the relationships between all four variables the diagram can be used to derive the volume fraction of the co2 phase from measurements of the partial and total homogenization temperature it can also be employed in the opposite sense for determining the theoretical homogenization temperature of an inclusion which decrepitates before reaching total homogenization provided a good visual phase volume estimate is available the graphical technique can also be applied to mixed co2 h2o inclusions which contain 6 wt nacl

meteoric incursion and oxygen fronts in the dalradian metamorphic belt southwest scotland a new hypothesis for regional gold mobility post metamorphic quartz veins which occur over hundreds of square kilometres in the biotite zone of the dalradian metamorphic belt consist of three principal types anhedral quartz with pyrite anhedral quartz with hematite and prismatic quartz with hematite or rutile the oxide minerals in anhedral veins have formed by oxidation of pre existing sulphides and gold was mobilized during this oxidation anhedral quartz veins formed from an aqueous fluid with up to 5 wt dissolved salts and 16 wt co2 at about 300 c texturally later prismatic quartz crystals formed from a compositionally similar fluid which was undergoing phase separation at the h2o co2 solvus at 160 200 c and 500 to 1200 bars fluid pressure oxygen isotope ratios for quartz from the veins range from 12 0 to 15 3 with hematite bearing veins generally isotopically heavier than pyrite bearing veins calculated fluid oxygen isotope ratios range from 8 for pyrite bearing veins to 2 for late prismatic crystals the mineralizing fluid contained a substantial component of meteoric water whose isotopic and chemical composition evolved with progressive water rock interaction evolution of meteoric fluid composition involved migration of oxidation and oxygen isotope fronts in the down flow direction as head driven water passed through structurally controlled fractures in the schist pile a gold solubility trough occurs for the observed fluid in the oxidation frontal zone gold remobilization and reprecipitation occurred progressively as the oxidation front migrated through the schist pile

mixing of h2o co2 in fluid inclusions geobarometry and archean gold deposits abstract a modified redlich kwong mrk equation of state for h 2 o and co 2 was used to calculate bulk molar volumes mole fractions and co 2 densities for mixed volatile fluid inclusions the results allow very useful p t diagrams to be constructed for fixed co 2 density and contoured with volume percent co 2 observed in the laboratory these diagrams permit rapid qualitative or quantitative determination of the p t path for a bulk inclusion isochore above the solvus in the system h 2 o co 2 nacl the calculations suggest peak metamorphic pressures of 3 5 kb for some archean greenstone gold deposits insights gained from this work may require reinterpretation of pressure estimates in published fluid inclusion studies

the malanjkhand copper molybdenum deposit india mineralization from a low temperature ore fluid of granitoid affiliation copper and subordinate molybdenum mineralization at malanjkhand occurs within a fracture controlled quartz reef enclosed in a pink granitoid body surrounded by grey granitoids constituting the regional matrix sulfide bearing stringers pegmatites with only quartz microcline and sulfide disseminations all within the pink granitoid represent other minor modes of occurrences despite this diversity in mode of occurrence the mineralogy of ores is quite consistent and conform to a common paragenetic sequence comprising an early ferrous stage of precipitation of magnetite i and pyrite i and the main stage chalcopyrite mineralization with minor sphalerite pyrite ii magnetite ii molybdenite and hematite both stages witnessed continuous precipitation of quartz microcline chlorite biotite and epidote the enclosing pink granitoid and the regional grey granitoids display alteration features such as saussuritization of plagioclase breakdown of hornblende and chloritization of biotite on a regional scale indicating interaction with a pervasive fluid quartz and microcline precipitation mostly restricted within the pink granitoid postdates this alteration four types of primary inclusions were encountered in quartz from ore samples 1 type i aqueous biphase l v inclusions the commonest variety in all ore types 2 type ii aqueous carbonic laq lcarb vcarb 3 type iii pure carbonic lcarb vcarb type ii and iii being restricted to stringer and pegmatitic ores and 4 rare polyphase laq vaq calcite gypsum inclusions quartz in granitoids contain primary type i inclusions only type i inclusions from ore samples furnish a temperature range after a rough pressure correction to the th maxima of 140 180 c of 150 275 c and a moderately low salinity of 4 12 wt nacl equivalent this is inferred to represent the signature of the major component f2 of the ore fluid a few type i inclusions of higher tm up to 380 c and low salinity and density represent the other f1 identifiable component of the ore fluid present in low proportion the th maxima and the total range in salinity of type i inclusions in quartz from granitoids are strikingly similar to those from the ore samples composition of syn ore chlorites furnished a temperature range of 185 327 c which conforms to the fluid inclusion microthermometric data pressure estimates using standard fluid inclusion geobarometric methods vary from 550 to 1790 bar in the stringer ores observed temperature salinity density relationships are best explained by a two stage evolution model of the ore fluid the first stage witnessed mixing of the two components f1 and f2 in unequal proportion bringing about mineralization the second stage of evolution was marked by the separation of a carbonic component on continued sulfide precipitation and attendant increase in salinity of the fluid the f1 component emerged as a distinct heated and co2 s charged entity due to steam heating and contamination of the early ingressed f2 fluid at the fracture zone the pervasive fluid phase in the surrounding granitoids contributed the f2 component

adaptation of an isopycnic coordinate ocean model for the study of circulation beneath ice shelves abstract much of the antarctic coastline comprises large floating ice shelves beneath which waters from the open ocean circulate the interaction of the seawater with the base of these ice shelves has a bearing both on the rate at which antarctic bottom water is formed and on the mass balance of the ice sheet an isopycnic coordinate ocean general circulation model has been modified so as to allow the incorporation of a floating ice shelf as an upper boundary to the model domain the modified code admits the introduction of an arbitrary surface pressure field and includes new algorithms for the diagnosis of entrainment into and detrainment from the surface mixed layer special care is needed in handling the cases where the mixed layer and isopycnic interior layers interact with surface and basal topography the modified model is described in detail and then applied to an idealized ice shelf ocean geometry simple tests with zero surface buoyancy forcing indicate that the introduction of the static s

mineralogical fluid inclusion and stable isotope constraints on mechanisms of ore deposition at the samgwang mine republic of korea a mesothermal vein hosted gold silver deposit the samgwang mine is located in the cheongyang gold district cheonan metallogenic province of the republic of korea it consists of eight massive gold bearing quartz veins that filled ne and nw striking fractures along fault zones in precambrian granitic gneiss of the gyeonggi massif their mineralogy and paragenesis allow two separate vein forming episodes to be recognized temporally separated by a major faulting event the ore minerals occur in quartz and calcite of stage i associated with fracturing and healing of veins hydrothermal wall rock alteration minerals of stage i include fe rich chlorite fe fe mg ratios 0 74 0 81 muscovite illite k feldspar and minor arsenopyrite pyrite and carbonates sulfide minerals deposited along with electrum during this stage include arsenopyrite pyrite pyrrhotite sphalerite marcasite chalcopyrite galena argentite pyrargyrite and argentian tetrahedrite only calcite was deposited during stage ii fluid inclusions in quartz contain three main types of c o h fluids co2 rich co2 h2o and aqueous inclusions quartz veins related to early sulfides in stage i were deposited from h2o nacl co2 fluids 1 500 5 000 bar average 3 200 with thtotal values of 200 c to 383 c and salinities less than about 7 wt nacl equiv late sulfide deposition was related to h2o nacl fluids 140 1 300 bar average 700 with thtotal values of 110 c to 385 c and salinities less than about 11 wt nacl equiv these fluids either evolved through immiscibility of h2o nacl co2 fluids as a result of a decrease in fluid pressure or through mixing with deeply circulated meteoric waters as a result of uplift or unloading during mineralization or both measured and calculated sulfur isotope compositions 34sh2s 1 5 to 4 8 of hydrothermal fluids from the stage i quartz veins indicate that ore sulfur was derived mainly from a magmatic source the calculated and measured oxygen and hydrogen isotope compositions 18oh2o 5 9 to 10 9 d 102 to 87 of the ore forming fluids indicate that the fluids were derived from magmatic sources and evolved by mixing with local meteoric water by limited water rock exchange and by partly degassing in uplift zones during mineralization while most features of the samgwang mine are consistent with classification as an orogenic gold deposit isotopic and fluid chemistry indicate that the veins were genetically related to intrusions emplaced during the jurassic to cretaceous daebo orogeny

thermal regime in the central alpine fault zone new zealand constraints from microstructures biotite chemistry and fluid inclusion data abstract the thermal state within plate boundary fault zones is likely to influence the dimensions of large co seismic fault ruptures and strain localisation in underlying mylonitic shear zones vein microstructures biotite chemistry and fluid inclusion data offer new insights into the thermal structure of the mylonitic shear zone down dip of the alpine fault the main pacific australian plate boundary structure through southern new zealand quartz veins within the fault rocks were formed and deformed at temperatures ranging from 500 c to immediately above that of the brittle viscous transition 325 c illustrating that fluids are present throughout the fault zone microthermometric data from primary mixed co 2 h 2 o fluid inclusions in boudin neck quartz carbonate veins indicate that these inclusions were trapped at temperatures of 325 15 c and pressures of c 40 mpa vein microstructures indicate that fluid temperatures were equal to rock temperatures assuming hydrostatic fluid pressure the veins were trapped at depths of 2 o co 2 fluids in the shallower crust of 500 kg m 3 biotite grains in the mylonites are a mixture of porphyroclastic grains with high r ti mg inherited from the parent alpine schist and smaller low r grains that recrystallised during mylonitisation particularly those that are found within syn mylonitic shear bands assuming a simple step function model approximating diffusive equilibration the changes in biotite chemistry indicate t during mylonitic deformation of 340 c according to the ti in biotite thermometer of henry et al 2005 a best fit uplift p t path to existing data and these new results indicate that the uplift path p t gradient of fault zone rocks above the brittle viscous transition is of the order of 40 c km 1 below the brittle viscous transition the uplift path p t gradient is 10 c km 1 the p t profile within the fault rocks is comparable to that in the immediate hanging wall alpine schist indicating there is no peak in the crustal isotherms in the fault hanging wall as was indicated by previous numerical models and analyses that did not consider data from the fault rocks themselves

geological fluid inclusion and stable isotope studies of mo mineralization galway granite ireland mo mineralization within the galway granite at mace head and murvey connemara western ireland has many features of classic porphyry mo deposits including a chemically evolved i type granite host associated k and si rich alteration quartz vein mace head and granite hosted murvey molybdenite chalcopyrite pyrite and magnetite mineralization and a gangue assemblage which includes quartz muscovite and k feldspar most fluid inclusions in quartz veins homogenize in the range 100 350 c and have a salinity of 1 13 eq wt nacl they display th salinity covariation consistent with a hypothesis of dilution of magmatic water by influx of meteoric water co2 bearing inclusions in an intensely mineralized vein at mace head provide an estimated minimum trapping temperature and pressure for the mineralizing fluid of 355 c and 1 2 kb and are interpreted to represent a h2o co2 fluid weakly enriched in mo produced in a magma chamber by decompression activated unmixing from a dense mo bearing nacl h2o co2 fluid 34s values of most sulphides range from c 0 at murvey to 3 4 at mace head and are consistent with a magmatic origin most quartz vein samples have 18o of 9 10 3 and were precipitated from a hydrothermal fluid with 18o of 4 6 6 7 some have 18o of 6 7 and reflect introduction of meteoric water along vein margins quartz muscovite oxygen isotope geothermometry combined with fluid inclusion data indicate precipitation of mineralized veins in the temperature range 360 450 c and between 1 and 2 kb whole rock granite samples display a clear 18o d trend towards the composition of connemara meteoric waters the mineralization is interpreted as having been produced by highlyfractionated granite magma meteoric water interaction postdates the main mineralizing event the differences between the mace head and murvey mineralizations reflect trapping of migrating mineralizing fluid in structural traps at mace head and precipitation of mineralization in the granite itself at murvey

geology and fluid characteristics of the ulu sokor gold deposit kelantan malaysia implications for ore genesis and classification of the deposit abstract the ulu sokor gold deposit is one of the most famous and largest gold deposits in malaysia and is located in the central gold belt this deposit consists of three major orebodies that are related to ns and ne striking fractures within fault zones in permian triassic meta sedimentary and volcanic rocks of the east malaya block the faulting events represent different episodes that are related to each orebody and are correlated well with the mineralogy and paragenesis the gold mineralization consists of quartz dominant vein systems with sulfides and carbonates the hydrothermal alteration and mineralization occurred during three stages that were characterized by i silicification and brecciation ii carbonatization sericitization and chloritization and iii quartz carbonate veins fluid inclusions in the hydrothermal quartz and calcite of the three stages were studied the primary co 2 ch 4 h 2 o nacl fluid inclusions in stage i are mostly related to gold mineralization and display homogenization temperatures of 269 389 c salinities of 2 77 11 89 wt nacl equivalent variable co 2 contents typically 5 29 mol and up to 15 mol ch 4 in stage ii gold was deposited at 235 398 c from a co 2 ch 4 h 2 o nacl fluid with a salinity of 0 83 9 28 wt nacl equivalent variable co 2 contents typically 5 63 mol and up to 4 mol ch 4 the 18 o h 2 o and d values of the ore forming fluids from the stage ii quartz veins are 4 5 to 4 8 and 44 to 42 respectively and indicate a metamorphic hydrothermal origin oxygen fugacities calculated for the entire range of t p x co 2 conditions yielded log f o 2 values between 28 95 and 36 73 for stage i and between 28 32 and 39 18 for stage ii these values indicate reduced conditions for these fluids which are consistent with the mineral paragenesis fluid inclusion compositions and isotope values the presence of daughter mineral bearing aqueous inclusions is interpreted to be a magmatic signature of stage iiia combined with the oxygen and hydrogen isotopic compositions 18 o h 2 o 6 8 to 11 9 d 77 to 62 these inclusions indicate that the initial fluid was likely derived from a magmatic source in stage iiib the gold was deposited at 263 to 347 c from a co 2 ch 4 h 2 o nacl fluid with a salinity of 5 33 to 11 05 wt nacl equivalent variable co 2 contents typically 9 15 mol and little ch 4 the oxygen and hydrogen isotopic compositions of this fluid 18 o h 2 o 8 1 to 8 8 d 44 to 32 indicate that it was mainly derived from a metamorphic hydrothermal source the co 2 h 2 o ch 4 nacl fluids that were responsible for gold deposition in the stage iiic veins had a wide range of temperatures 214 483 c salinities of 1 02 to 21 34 wt nacl equivalent variable co 2 contents typically 4 53 mol and up to 7 mol ch 4 the oxygen and hydrogen isotopic compositions 18 o h 2 o 8 5 to 9 8 d 70 to 58 were probably acquired at the site of deposition by mixing of the metamorphic hydrothermal fluid with deep seated magmatic water and then evolved by degassing at the site of deposition during mineralization the log f o 2 values from 28 26 to 35 51 also indicate reduced conditions for this fluid in stage iiic moreover this fluid had a near neutral ph and 34 s values of h 2 s of 2 32 to 0 83 which may reflect the derivation of sulfur from the subducted oceanic lithospheric materials the three orebodies represent different gold transportation and precipitation models and the conditions of ore formation are related to distinct events of hydrothermal alteration and gold mineralization the gold mineralization of the ulu sokor deposit occurred in response to complex and concurrent processes involving fluid immiscibility fluid rock reactions and fluid mixing however fluid immiscibility was the most important mechanism for gold deposition and occurred in these orebodies which have corresponding fluid properties structural controls geologic characteristics tectonic settings and origins of the ore forming matter these characteristics of the ulu sokor deposit are consistent with its classification as an orogenic gold deposit while some of the veins are genetically related to intrusions