major types and time space distribution of mesozoic ore deposits in south china and their geodynamic settings the ore deposits of the mesozoic age in south china can be divided into three groups each with different metal associations and spatial distributions and each related to major magmatic events the first event occurred in the late triassic 230 210 ma the second in the mid late jurassic 170 150 ma and the third in the early mid cretaceous 120 80 ma the late triassic magmatic event and associated mineralization is characterized by peraluminous granite related w sn nb ta mineral deposits the triassic ore deposits are considerably disturbed or overprinted by the later jurassic and cretaceous tectono thermal episodes the mid late jurassic magmatic and mineralization events consist of 170 160 ma porphyry skarn cu and pb zn ag vein deposits associated with i type granites and 160 150 ma metaluminous granite related polymetallic w sn deposits the late jurassic metaluminous granite related w sn deposits occur in a ne trending cluster in the interior of south china such as in the nanling area in the early mid cretaceous from about 120 to 80 ma but peaking at 100 90 ma subvolcanic related fe deposits developed and i type calc alkaline granitic intrusions formed porphyry cu mo and porphyry epithermal cu au ag mineral systems whereas s type peraluminous and or metaluminous granitic intrusions formed polymetallic sn deposits these cretaceous mineral deposits cluster in distinct areas and are controlled by pull apart basins along the south china continental margin based on mineral assemblage age and space time distribution of these mineral systems integrated with regional geological data and field observations we suggest that the three magmatic mineralization episodes are the result of distinct geodynamic regimes the triassic peraluminous granites and associated w sn nb ta mineralization formed during post collisional processes involving the south china block the north china craton and the indo china block mostly along the dabie sulu and songma sutures jurassic events were initially related to the shallow oblique subduction of the izanagi plate beneath the eurasian continent at about 175 ma but i type granitoids with porphyry cu and vein type pb zn ag deposits only began to form as a result of the breakup of the subducted plate at 170 160 ma along the nne trending qinzhou hangzhou belt also referred to as qin hang or shi hang belt which is the neoproterozoic suture that amalgamates the yangtze craton and cathaysia block a large subduction slab window is assumed to have formed in the nanling and adjacent areas in the interior of south china triggering the uprise of asthenospheric mantle into the upper crust and leading to the emplacement of metaluminous granitic magma and associated polymetallic w sn mineralization a relatively tectonically quiet period followed between 150 and 135 ma in south china from 135 ma onward the angle of convergence of the izanagi plate changed from oblique to parallel to the coastline resulting in continental extensional tectonics and reactivation of regional scale ne trending faults such as the tan lu fault this widespread extension also promoted the development of ne trending pull apart basins and metamorphic core complexes accompanied by volcanism and the formation of epithermal cu au deposits granite related polymetallic sn w deposits and hydrothermal u deposits between 120 and 80 ma with a peak activity at 100 90 ma

drav model and its application in assessing groundwater vulnerability in arid area a case study of pore phreatic water in tarim basin xinjiang northwest china according to the characteristics of groundwater in arid area this paper proposes drav model for groundwater vulnerability assessment where d is groundwater depth r is the net recharge of aquifer a is the aquifer characteristics and v is the lithology of vadose zone as a case study the paper assesses the vulnerability of pore phreatic water in tarim basin of xinjiang china by using the drav model the results indicate that the areas of phreatic water with vulnerability index ranges of 2 4 4 6 6 8 and 8 accounting for 10 1 80 4 9 2 and 0 2 of the total plain area of the tarim basin respectively and the areas with the latter two vulnerability ranges 6 8 and 8 are mainly located in the irrigation districts with thin soil layer 20 30 cm thick surface soil of vadose zone mainly with underlying sandy gravel and with silty and fine sand layer such vadose zone generally lacks sandy loam and clayey soil and has larger recharge by infiltration of irrigation water

application of inverse modeling in a study of the hydrogeochemical evolution of karst groundwater in the jinci spring region northern china this study explores the hydrogeochemical evolution of karst groundwater in the jinci spring region shanxi province northern china during 2015 karst groundwater samples collected from 24 sampling points along several profiles that follow the groundwater flow direction were subjected to hydrochemical analysis reaction paths and mineral phases for the hydrogeochemical modeling were determined based on the analysis results and in conjunction with the regional geology and hydrogeology the phreeqc hydrogeochemical modeling software was used to perform mass balance and reaction path modeling of the hydrogeochemical evolution of the spring region the modeling results showed that from the recharge area through the runoff area to the drainage area the hydrogeochemical processes occurring in the karst water vary widely between the northeastern central and southwestern parts of the spring region and across the piedmont discharge area additionally hydrodynamic fields and geological structures were found to have significant control over the hydrogeochemical reactions occurring within the spring region s karst groundwater

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

progressive 18o depletion during co2 separation from a carbon dioxide rich hydrothermal fluid evidence from the grey river tungsten deposit newfoundland oxygen isotope data for the grey river tungsten prospect newfoundland canada indicate a progressive depletion in 18ofluid during mineralization early veins with pegmatitic affinities were deposited at 470 c and pressures greater than 1 kbar 100 mpa from a fluid with a 18o composition of 7 4 presumed to be of magmatic origin successive vein deposition at progressively lower temperatures and pressures culminated in the precipitation of wolframite bearing veins at a temperature of 300 c and pressures of 150 320 bar 15 32 mpa from a low salinity fluid with a 18o composition in the range 3 2 1 6 low values of 18o and dfluid are recorded in many vein tungsten deposits and are normally interpreted as reflecting mixing of isotopically light meteoric fluids or formation brines with magmatic fluids however fluid inclusion evidence for the grey river mineralization indicates that a 40 mol co2 loss occurred by immiscibility and retrograde boiling of the hydrothermal fluid between 420 and 3

geochemistry of fluoride rich groundwater in kolar and tumkur districts of karnataka groundwater is a significant water resource in india for domestic irrigation and industrial needs by far the most serious natural groundwater quality problem in india in terms of public health derives from high fluoride arsenic and iron concentrations hydrogeochemical investigation of fluoride contaminated groundwater samples from kolar and tumkur districts in karnataka are undertaken to understand the quality and potability of groundwater from the study area the level of fluoride contamination the origin and geochemical mechanisms driving the fluoride enrichment majority of the groundwater samples did not meet the potable water criteria as they contained excess 1 5 mg l fluoride dissolved salts 500 mg l and total hardness 75 924 mg l hydrogeochemical facies of the groundwater samples suggest that rock weathering and evaporation crystallization control the groundwater composition in the study area with 50 67 of samples belonging to the ca hco3 type and the remaining falling into the mixed ca na hco3 or ca mg cl type the saturation index values indicated that the groundwater in the study area is oversaturated with respect to calcite and under saturated with respect to fluorite the deficiency of calcium ion concentration in the groundwater from calcite precipitation favors fluorite dissolution leading to excess fluoride concentration

stockwork tungsten scheelite molybdenum mineralization lake george southwestern new brunswick scheelite molybdenite stockwork mineralization constitutes one component of the lake george polymetallic sb w mo au base metal deposit a complex hydrothermal center of late silurian ca 412 m y age in the fredericton trough of the northern appalachians the stockwork hosted by silurian graywackes in part calcareous is spatially and temporally related to a postkinematic cupola of biotite monzogranite and its formation overlapped in time with the emplacement of monzogranitic porphyry dikes mineralogical and textural evidence indicates that contact metamorphism associated with the cupola had ceased before the initiation of w mo mineralization and that it occurred at pressures of less than 1 75 kb in two stages a peak stage t 600 degrees c evident only in rocks of pelitic composition and a lower temperature reequilibration t 500 degrees c recorded in rocks of both pelitic and marly compositions the w mo deposit comprises three different scheelite and or molybdenite bearing veinlet types type 1 bodies the earliest formed are calc silicate granditic garnet wollastonite clinopyroxene and calcic amphibole quartz veinlets with ubiquitous ca and h metasomatic alteration envelopes mineralogical and fluid inclusion relationships indicate that the fluids ranged in temperature from 550 degrees to 228 degrees c and that temperature decreased away from the cupola the succeeding type 2 veinlets comprise quartz and lesser amounts of perthitic alkali feldspar muscovite calcite scheelite molybdenite and pyrite fluid inclusion evidence shows that mineralization dominantly occurred from 400 degrees to 175 degrees c under a confining pressure of 1 3 kb higher grade scheelite and molybdenite deposition was focused in a lower temperature zone to the north of the cupola in which co 2 effervescence occurred type 3 veinlets the last to form consist of prehnite molybdenite and quartz and represent a volumetrically minor mineralization type in both type 1 and 2 systems scheelite and molybdenite deposition appears to have been controlled by decreasing temperature and increasing ph temperature was a function of distance from the cupola for both veinlet types but the controls on ph were specific to each thus the ph of type 1 fluids was controlled by wall rock interaction h metasomatism whereas that of type 2 fluids was controlled by co 2 effervescence the economic stibnite quartz veins scratch et al 1984 occupy fractures which transect and therefore postdate all stages of w mo mineralization

fluid inclusion study of the ballinglen w sn sulphide mineralization se ireland scheelite mineralized microtonalite sheets occur on the se margin of the end caledonian leinster granite in se ireland scheelite polymetallic sulphides and minor cassiterite occur in veins in the microtonalites disseminated throughout the greisened microtonalite sheets and in the adjacent wallrocks two major mineralized vein types occur in the microtonalite sheets 1 scheelite arsenopyrite pyrrhotite occur in quartz fluorite veins generally without a muscovite selvage 2 sphalerite chalcopyrite pyrite galena cassiterite stannite occur in quartz fluorite veins with a coarse muscovite selvage and are often intergrown with the muscovite quartz hosted fluid inclusions were examined from representative samples of both vein types using petrographic microthermometric and laser raman spectroscopic techniques three distinct types of fluid inclusions have been recognized primary vapour rich type 1 inclusions in quartz from the scheelite mineralized veins are of h2o co2 ch4 n2 h2s nacl composition and formed between 360 530 c primary and secondary liquid rich type 2 fluid inclusions in the base metal sulphide mineralized veins are of h2o ch4 n2 h2s nacl composition and formed between 340 480 c they also occur as pseudosecondary and secondary inclusions in scheelite mineralized veins late dilute low temperature h2o nacl kcl fluid inclusions may be related to late caledonian convection of meteoric waters around the cooling leinster granite batholith

re os isotopic chronology of molybdenites in huangshaping lead zinc deposit southeast hunan and its geological implications the huangshaping lead zinc polymetallic deposit in southeast hunan is genetically related to the intrusion of huangshaping granitic rocks and occur in the contact zone between the granodioritic porphyry and the limestone of lower carboniferous shidengzi formation as well as in the neighboring bedding plane fault zone previously the metallogenic epoch of the deposit was indirectly deduced by the ages of such nearby granitic rocks as granite porphyry and quartz porphyry or altered minerals based on the re os isochron method of molybdenites this paper measured directly the ore forming age from skarn ore in the huangshaping deposit and got a re os age of 153 8 4 8 ma which is in accordance with the previous k ar age of 153 157 ma obtained from phlogopite in the ore bearing skarn of the deposit combined with related rare earth element and trace element geochemistry of huangshaping granites and ore bearing skarn it is concluded in this paper that the age of 154 ma should represent the metallogenic epoch of the deposit and that there existed a close relationship between the ore forming process of the deposit and the granite porphyry which were both formed during the peak stage of early yanshanian large scale rock forming and ore forming activities in south china

isotopic geochemistry zircon u pb ages and hf isotopes of a type granites from the xitian w sn deposit se china constraints on petrogenesis and tectonic significance abstract zircon u pb geochronological geochemical and petrological analyses have been carried out on the xitian granite emplaced in the middle part of shi hang zone which is closely related to the economically important xitian tungsten tin deposit in hunan province southeast china la icp ms zircon u pb dating of two representative samples yielded weighted means 206 pb 238 u age of 151 7 1 2 ma and 151 8 1 4 ma these granites are comprised mainly of k feldspar quartz plagioclase fe rich biotite and minor fluorite and are characterized by enrichments in rb th rees total ree 159 351 ppm and hfses e g zr and y but depletions in ba sr p eu and ti they are metaluminous to weakly peraluminous and show a clear a type granite geochemical signature with high sio 2 73 44 78 45 wt total alkalis na 2 o k 2 o 2 89 8 98 wt fe 2 o 3 mgo ratios and low p 2 o 5 cao mgo and tio 2 contents in situ zircon hf isotope analysis suggests their e hf t values ranging from 7 43 to 14 69 sr nd isotope data show their e nd t values in the range of 9 2 to 7 3 with corresponding t dm2 ages of 1 72 1 56 ga these characteristics indicate that the xitian granite originated from partial melting of metamorphic basement rocks with a certain amount of mantle derived materials combined with previous geochemical and isotopic data it is derived that mantle crust interaction was gradually enhanced from the early to late stages of magmatism the ore forming materials and fluids of the xitian w sn deposit are mainly produced by the early yanshanian granitic magmatism which is also responsible for the late jurassic ca 152 ma a type granitic rocks that host the w sn polymetallic deposits distributed along the shi hang zone implying a significant mesozoic extensional event in southeast china likely caused by the subduction of the paleo pacific plate

regional and local variations in the composition of the wolframite series from sw japan and possible factors controlling compositional variations the regional and local variations in the composition of the wolframite series associated with the ilmeniteseries and magnetite series granitoids in the inner zone of sw japan were investigated using x ray diffraction and microprobe analyses it is concluded that the variation in mn fe ratios in the source materials granitic magmas in most cases is the dominant factor controlling the regional variation in the wolframite compositions while as exemplified by the kaneuchi mine kyoto prefecture the wallrock chemistry and ph of ore fluids are responsible for the local variation within a single vein system within a fresh euhedral crystal from the mine only slight compositional variation of less than 3 mole mnwo4 is found in the form of oscillatory zoning this study combined with the fluid inclusion research indicates that the wolframite compositions mn fe ratios cannot be used as a geothermometer

geology and genesis of the hehuaping magnesian skarn type cassiterite sulfide deposit hunan province southern china abstract magnesian skarn type tin deposits are relatively rare in the world the hehuaping cassiterite sulfide deposit in southern china having a total reserve of approximately 130 000 t of tin 50 000 t of lead and 10 000 t of zinc is identified as such type the deposit is related to the late jurassic 157 ma hehuaping medium to coarse grained biotite granite that intruded the middle devonian qiziqiao dolomite formation and the tiaomajian sandstone formation four paragenetic stages of skarn and ore formation have been recognized i prograde stage ii retrograde stage iii cassiterite sulfide stage and iv carbonate stage alteration zoning between fresh granite and unaltered country rocks can be identified the skarn are typified by mg mineral assemblages of forsterite spinel diopside tremolite serpentine talc and phlogopite the geochemistry of various skarn minerals shows a gradually decrease of mg end member and correspondingly an increase of fe and especially mn end members along the process of skarn alteration tin mineralization developed during the late retrograde stage resulted in cassiterite magnetite diopside skarn however the deposition of cassiterite occurred predominantly as cassiterite sulfide veins along fractures and interlayer fracture zones during stage iii the petrogeochemistry of hehuaping granite as well as s and pb isotopic analyses suggest that the ore forming elements have a magmatic source originated from the upper crust the h o isotopic and fluid inclusion analyses indicate that high temperature ore forming fluids in early anhydrous skarn stage stage i are also magmatic origin in comparison the retrograde fluids are characterized by relatively low salinity 2 to 10 wt nacl equiv and low temperature 220 to 300 c suggesting a mixed origin of meteoric waters with magmatic fluids the major ore forming stage iii fluids are characterized by lower temperature 170 to 240 c and salinity 1 to 6 wt nacl equiv indicating fluid mixing could be an efficient tin mineralizing mechanism meteoric waters are dominant in stage iv resulting in a further lowering of temperature 130 to 200 c and salinity 0 4 to 1 wt nacl equiv

empirical models of calculating phreatic evaporation from bare soil in tarim river basin xinjiang based on the experimental data at the akesu water balance experimental station awbes from 1990 to 1996 the control conditions of establishing calculation models of phreatic evaporation have been analyzed the empirical formulae for calculating the phreatic evaporation have been presented the results show that as for a given phreatic depth the phreatic evaporation increases nonlinearly with pan evaporation when pan evaporation reaches the infinity the phreatic evaporation is close to limiting phreatic evaporation the new models overcome the disadvantages of phreatic evaporation overestimation when atmospheric evaporation demand is great and the linear relationship between phreatic evaporation and pan evaporation with a high accuracy the new models are appropriate to be applied in similar regions without observed data

the changes of groundwater chemistry of semi confined buried valley aquifer during one decade of water exploitation this article presents the analysis of the temporal changes in water chemistry in a semi confined aquifer wielkopolska buried valley aquifer poland during one decade of water exploitation it is shown that the groundwater contamination as documented in a previous work still persists and has lead to steady groundwater quality deterioration the most intensive changes in water chemistry due to contamination are observed in the regions recognized earlier as the most vulnerable parts of the aquifer the influence of contamination is effective despite implementation of groundwater protection activities the travails of groundwater quality protection of the confined or semi confined aquifers were accented

a precise u pb age on cassiterite from the xianghualing tin polymetallic deposit hunan south china we report the first precise u pb isotope data on cassiterite from the large xianghualing tin polymetallic deposit in the central nanling district south china the results show that four separates from sample xf 51 have a relatively narrow range of 206pb 238u apparent ages varying from 152 to 157 ma and the three 206pb 238u apparent ages yield a weighted average value of 156 4 ma mswd 0 32 separates from two other cassiterite samples do not have sufficient radiogenic pb to generate a reliable 206pb 238u age seven separates from the above three cassiterite samples define a well constrained 238u 206pb isochron corresponding to an age of 157 6 ma mswd 34 a comparison of the u pb cassiterite ages with published ar ar dates on muscovite from this deposit and k ar age data on biotite from the pluton genetically related to the tin mineralization in this area demonstrates that the u pb isotope system of cassiterite is a potential geochronometer combined with the ar ar dates of muscovite from this deposit we can constrain the absolute age of tin polymetallic mineralization in xianghualing at 154 157 ma the dates obtained in this study consistent with the published geochronological results from other important deposits in this region reveal that the large scale tungsten tin mineralization in the central nanling region was predominantly emplaced during 150 161 ma

mesozoic metallogeny in east china and corresponding geodynamic settings an introduction to the special issue abstract the giant east china mesozoic metallogenic province hosts some of the world s largest resources of tungsten tin molybdenum antimony and bismuth ores of gold silver mercury lead zinc copper uranium and iron are also of major importance the province and its constituent metallogenic belts or regions south china middle lower yangtze river valley east qinling dabie interior of north china craton yan liao and north east china are the products of several pulses of igneous activity and mineralisation between 240 and 80 ma each successive stage has produced a distinctive suite of deposits that can be readily related to the geodynamic evolution of the region during the mesozoic this geodynamic evolution is linked to a complex series of tectonic events involving far field subduction plate collisions crustal thickening post collision collapse and rifting

hydrothermal alteration veining and fluid inclusion characteristics of the kalzas wolframite deposit yukon kalzas is a sheeted vein and stockwork wolframite deposit crosscutting continental margin sedimentary rocks of the proterozoic windermere supergroup in central yukon mineralization is synchronous with cretaceous post tectonic granites of the selwyn plutonic suite parallel sets of planar quartz veins contain coarse euhedral wolframite and are generally oriented perpendicular to southeast plunging fold axes widespread alteration of the host rocks and intense stockwork veining surround the veins alteration and mineralization show a distinct concentric zonation across a 2 5 km long southeast trending oval the core zone is characterized by orthoclase contained within quartz tourmaline wolframite veins minor phases include apatite molybdenite bismuthinite pyrite chalcopyrite and pyrrhotite host rocks are prevasively tourmalinized and sericitized hydrothermal alteration here at the core of the system overprints early biotitization of the host rocks the biotitization appears to have been the result

delineation of temporal variability and governing factors influencing the spatial variability of shallow groundwater chemistry in a tropical sedimentary island summary an attempt has been made to delineate the temporal variability and factors governing the shallow groundwater chemistry using analysis of variance anova and multivariate analysis notably r mode factor fa and hierarchical cluster analysis hca subsequently geostatistical isoplethic maps were applied to convey better understanding on the distribution of selected groundwater parameters the manukan island s shallow aquifer with sedimentary setting that constantly abstracted for freshwater supply has been selected for this study one way anova suggested that neither changes of tide level nor rainfall volume appeared to exert significant influence on the groundwater chemistry of the small island rather the groundwater chemistry was greatly governed by influence from seawater intrusion which characterized by considerable amount of ca na and cl such condition was well explained by a piper diagram where most plots were situated at the middle diamond shaped diagram indicating mixing condition fa likewise revealed that the shallow groundwater receives marked influence from carbonate dissolution and silicate weathering processes especially boreholes located in the inland area this can be clearly noted from the distinct groupings of relationships among different factors hca classified boreholes into three groups according to their locations in the coastal area suggesting significant chemical variations between boreholes with distance from coast such distribution pattern was particularly evident in the isoplethic map overall it appears that the shallow groundwater in the tropical island is not an appropriate source for drinking water in concern to its exceptionally high salinity and several elevated minor elements mn pb and se for this it is suggested that efforts in exploring other alternative sources should be performed outright

fluid inclusion studies of longshang tin polymetallic deposit in xitian ore field eastern hunan province the longshang ore deposit is a large size tin polymetallic deposit in the xitian ore field eastern hunan province fluid inclusions in fluorite and quartz from the skarn and fracture zone altered rocks of the longshang tin polymetallic deposit were studied by such means as petrography microthermometry and laser raman spectrometer analysis the results show that fluid inclusions are composed of nacl h2o type fluid inclusions type a co2 rich two phase inclusions type b and co2 bearing three phase inclusions type c type a comprises single phase liquid inclusions a1 and two phase liquid vapor inclusions a2 type b includes co2 rich two phase inclusions and type c consists of co2 bearing three phase inclusions which have been homogenized into lh2o c1 and co2 bearing three phase inclusions which have been homogenized into vco2 c2 the homogenization temperatures of the three ore forming stages are 290 380 for stage i 210 240 for stage ii and 90 190 for stage iii at the early stage of the ore forming process stage i fluid inclusions of co2 nacl h2o and nacl h2o cacl2 types which had close homogenization temperatures were associated with each other and the main ore forming fluids were co2 and nacl h2o with small amounts of h2s and ch4 at the late stages of the ore forming process stage ii iii the main ore forming fluid was nacl h2o according to characteristics of the fluid inclusions high 3he 4he ratios and the existence of lots of mafic microgranular inclusions the authors consider that the ore forming materials of the longshang tin polymetallic deposit were derived from multiple sources the ore forming fluids were mixed with mantle crust and atmospheric water under the control of igneous and surrounding rocks the mantle ore forming fluids played a key role in mineralization at the early stage of the ore forming process

variation of groundwater hydrochemical characteristics in the plain area of the tarim basin xinjiang region china groundwater hydrochemistry could reveal the interaction mechanism between groundwater and the environment which provides a scientific basis for environmental resources management in this study shukaliefu s classification method and piper diagram were adopted to determine the hydrochemical types of groundwater in the tarim basin of xinjiang china the method of one vote veto was applied to evaluate the quality of groundwater phreeqc software was used to calculate the saturation indices of calcite and fluorite in groundwater by comparing groundwater quality data of 2003 and 2011 we characterized the variations in hydrochemical types and water quality types salinization of groundwater and fluoride geochemistry of the plain area of the tarim basin results show that the primary anion in phreatic water in the plain area of the tarim basin changed from hco3 to so4 2 or cl on the contrary the primary anion in confined water changed from so4 2 or cl to hco3 in 2003 63 1 of the sampling points in the study area exceeded the class iii water quality standard of china in 2011 the proportion increased to 82 5 in addition severe groundwater salinization was found at 19 7 of the sampling points some of the deep groundwater samples were salinized as well in the aksu area at the north west part of the tarim basin f concentration exceeding the standard limit 1 mg l was found to be 55 0 of the groundwater samples tested based on these findings it is concluded that the phreatic water in the study area was severely influenced by the industrial wastewater and domestic sewage related to human activities while the confined water was less affected the general quality of groundwater was in an aggravation trend and the groundwater salinization was in a severe condition in this area the ca2 na ionic exchange the unsaturated fluorite and oversaturated calcite in the aquifer of the aksu area are proposed to cause f enrichment in groundwater of this area

metamorphosed pb zn ag ores of the keketale vms deposit nw china evidence from ore textures fluid inclusions geochronology and pyrite compositions abstract the keketale pb zn deposit is located in the devonian volcanic sedimentary maizi basin of the altay orogenic belt the mineralization at keketale is hosted in marbles and deformed volcanic tuffs and biotite garnet chlorite schists folded into a series of overturned synclines formed in multiple deformation events keketale contains economic amounts of pb 0 89 mt 1 51 wt zn 1 94 mt 3 16 wt and ag 650 t 40 g t detailed petrographic studies have defined two main generations of sulfide development the banded pyrite of the early stage a is commonly stratiform with minor galena sphalerite and chalcopyrite stage b is characterized by a large amount of polymetallic sulfides including pyrrhotite chalcopyrite sphalerite and galena with minor pyrite hosted in quartz veins three types of fluid inclusions fis including mixed carbonic aqueous c type pure carbonic pc type and aqueous w type have been recognized in quartz of stage b the c type fis have homogenization temperatures of 150 326 c and salinities of 0 2 16 6 wt nacl equivalent the pc type fis are dominated by co2 with minor ch4 and n2 and have initial ice melting temperatures of 57 5 to 56 7 c co2 homogenization temperatures of 11 14 1 c the w type primary fis were completely homogenized at temperatures of 124 359 c with salinities of 5 0 14 6 wt nacl equivalent such co2 rich fluid inclusions are consistent with those discovered in orogenic type deposits in the altay area and elsewhere muscovite separates from the polymetallic quartz veinlets of stage b yield a well defined 40ar 39ar isotopic plateau age of 259 33 2 56 ma with an isochron age of 259 62 2 65 ma this age is coeval with the closure of the paleo asia ocean and reactivation of the ertix fault system la icp ms analyses of two generations of pyrite indicate that the banded pyrite of stage a is relatively depleted in metallic elements and contains low contents of cu 0 39 ppm ag 0 20 ppm au below the detection limits pb 17 43 ppm and zn 14 38 ppm whereas the pyrite in quartz polymetallic sulfide veinlets of the stage b is relatively rich in metallic elements e g cu 2 56 ppm ag 3 07 ppm au 0 01 ppm pb 1047 ppm and zn 1136 ppm the trace amounts of cu pb zn au and ag are interpreted to have been initially locked in the lattice of type a pyrite and then liberated and precipitated as micromineral inclusions with type b pyrite during subsequent metamorphism and deformation two key factors are considered vital to the formation of economic ores of the keketale pb zn deposit namely the original devonian banded pyrite formed in a vms system and subsequent permian deformation and metamorphic processes that liberated cu pb zn au and ag from the lattice of type a pyrite to form galena sphalerite and chalcopyrite with minor muscovite in quartz veinlets the model provides a new interpretation of vms pb zn deposit occurring in back arc basin environments followed by collision and new insights into the unique regional fe cu pb zn au mineralization in the altay orogenic belt

fluid evolution and mineralization in a subvolcanic granite stock the mount pleasant w mo sn deposits new brunswick canada in the fire tower zone at mount pleasant new brunswick porphyry style w mo stage i and stanniferous polymetallic vein and replacement stage ii mineralization is hosted principally by a complex hydrothermal breccia pipe which overlies a subvolcanic fine grained granite stock wolframite and molybdenite of stage i occur in quartz or topaz and or fluorite veinlets and breccia matrices and as disseminations in altered wall rocks quartz and topaz with lesser green biotite chlorite and k feldspar are the main alteration minerals sericite occurs as a late alteration product in the main ore zone stage ii comprises mineralogically complex sn bearing sulfide vein and replacement bodies that contain abundant fluorite and chlorite the stage ii mineralization has been superimposed on stage i and is spatially related to later dikes of granite porphyry quartz fluorite and topaz contain three types of fluid inclusions type 1 are low salinity mostly 10 equiv wt nacl cacl 2 liquid vapor inclusions which homogenize to liquid type 2 are vapor rich inclusions that homogenize to vapor and type 3 are high salinity 30 60 equiv wt nacl liquid vapor solid inclusions most of which homogenize to the liquid phase by solid generally halite disappearance all three inclusion types are found in minerals from stage i whereas only type 1 is found in minerals from stage ii crystallization of the fine grained granite resulted in the generation of a subcritical mixture of orthomagmatic low salinity vapors and high salinity liquids the increase in volume associated with the separation of these fluids caused overpressuring in the apical portions of the fine grained granite magma which resulted in failure of the overlying sequence and in the formation of the breccia pipe the resultant decrease in pressure caused adiabatic cooling of the fluid and explains some of the observed salinity variations a consideration of phase equilibria in aqueous salt systems indicates that the high salinity liquids must have cooled approximately isobarically to produce the observed fluid inclusions this cooling is thought to have been achieved through mixing with ground waters the high salinity fluids were responsible for the precipitation of the bulk of the stage i quartz and associated wolframite and molybdenite and for silica topaz and biotite alteration the later intrusion of the granite porphyry and or porphyritic granite provided a second generation of subcritical orthomagmatic fluids which may have been responsible for tin greisen mineralization located at depth in the porphyritic granite after each of these orthomagmatic events low to moderate salinity ground waters dominated the system in both cases these late fluids deposited fluorite and sulfides and caused chloritic alteration in the latter event they formed the stage ii sn bearing polymetallic zones

trace and minor elements in sphalerite from base metal deposits in south china a la icpms study laser ablation icp mass spectroscopy has been used to investigate the geochemistry of sphalerite in a range of nine zn pb deposits in south china the deposits which are of different ages and belong to different metallogenic provinces have been assigned to the following genetic types skarn hetaoping luziyuan syngenetic massive sulphide dabaoshan laochang and bainiuchang and mississippi valley type huize mengxing niujiaotang based on the features of the ore even though their origin is heavily debated based on other criteria the giant jinding deposit is considered separately sphalerite from each genetic class of deposit shows a distinct chemical signature sphalerite from the skarn deposits is characterised by elevated lattice bound concentrations of co and mn the distal character of these skarn systems is reflected by the low in content of sphalerite the three syngenetic massive sulphide deposits feature sphalerite strongly enriched in in sn and ga whereas the deposits of mvt type are typically enriched in ge cd tl and as these divergent characters are reflected in absolute element abundances as well as in element ratios time resolved depth profiles for sphalerite from the chinese deposits confirm the presence of elements such as co in ge ga and cd in solid solution but the dataset expands the understanding of sphalerite mineral chemistry by also indicating that other elements whose ability to enter the crystal structure of sphalerite has been previously debated ag sn tl sb may also be in solid solution sphalerite is a refractory mineral and trace element analysis of sphalerite shows promise as a tracer of ore genesis even in overprinted ores systematic work on larger sample suites may help define the geochemical signature of different metallogenic epochs in regions as geologically complex as south china and help resolve the mechanism by which many of the debated ore deposits were formed

occurrence and formation of high fluoride groundwater in the hengshui area of the north china plain although high f groundwater was observed in the hengshui of the north china plain the depth dependence of groundwater f and its relation to aquifer sediments remains unknown both shallow groundwater and deep groundwater were collected for chemical and isotopic characterization sediments were taken from different depths down to 130 m for total element analysis and f form determination with sequential extraction procedure results show that f concentration ranges from 0 37 to 3 28 mg l and from 0 28 to 3 6 mg l in shallow and deep groundwater respectively high f water from shallow aquifers are of cl so4 na mg hco3 cl so4 na and so4 cl na mg types while hco3 so4 cl na and cl so4 na types are from deep aquifers high f waters are mainly found at the depths of 50 200 and 300 m along the flow path groundwater shows an increasing trend in f concentration from the northwest to the southeast isotopes of 18o and d in deep groundwater are more depleted in comparison with shallow groundwater suggesting that shallow and deep groundwater replenish through different ways with longer retention time of deep groundwater 13c of dissolved inorganic carbon are between 11 9 and 8 8 in shallow groundwater and between 10 6 and 7 5 in deep groundwater respectively which indicates that groundwater dic comes from both rock weathering and biodegradation of organic matter fluoride content in the sediment ranges from 140 to 1690 mg kg showing a decreasing trend with depth good correlations between f and al2o3 and fe2o3 are observed demonstrating that f contents in sediments are significantly influenced by the minerals containing fe2o3 and al2o3 in terms of adsorption sequential extraction procedure shows that exchangeable f form f1 and fe mn oxides bound f f3 generally decrease with depths while organic matter or sulfide bound f f4 keeps relatively stable and carbonate bound f f2 exhibits highly variable the relationships between f concentration and fe or mn imply that f in f1 is more inclined to be scavenged by fe and mn oxides hydroxides which have a stronger affinity for f although a variety of hydrogeochemical processes affected f concentrations dissolution precipitation is a vital process in the study area in comparison with shallow groundwater cation exchange may exhibit more significantly effect on f enrichment in deep groundwater competitive adsorption of hco3 and oh with f leads to the release of f from aquifer matrix into solution which increases groundwater f concentration evaporation is another control on f concentration especially in shallow groundwater

ore forming mechanism of quartz vein type w sn deposits of the xitian district in se china implications from the trace element analysis of wolframite and investigation of fluid inclusions abstract the xitian w sn district is located in eastern hunan province of se china and comprises the heshuxia goudalan and longshang w sn deposits our study on the occurrence mineral assemblage and geochemistry of the orebodies shows that quartz vein orebodies are dominant mode of mineralization and can be divided into three stages stage i quartz molybdenite wolframite i stage ii quartz wolframite ii polymetallic sulfides and stage iii quartz pyrite fluorite the elements nb ta sc sn zn cr v mo cu and zr are abundant in both wolframite i and wolframite ii wolframite i contains higher concentrations of nb 1408 9245 ppm ta 241 2407 ppm and sc 123 521 ppm than wolframite ii nb 144 1080 ppm ta 3 76 315 ppm and sc 1 86 11 44 ppm these results indicate that wolframite i was formed closer to the host rock and at a greater ore forming depth than wolframite ii the total ree concentrations of wolframite i and ii range from 34 96 to 133 36 ppm and 21 30 to 43 73 ppm respectively both wolframite i and wolframite ii have low lree concentrations 0 00 0 05 and 0 08 8 18 ppm respectively and high hree concentrations 34 96 133 31 and 21 23 41 87 ppm respectively the enrichment of hrees in wolframite may be due to the fact that the sizes of the hrees3 0 94 1 02 a in combination with nb5 or ta5 0 72 a are closer to that of w6 0 68 a in combination with ca2 1 08 a or mg2 0 80 a than that of the lrees3 1 03 1 13 a making the coupled substitution easier a study of fluid inclusions in the coexisting gangue minerals shows that the homogenization temperatures of the fluid inclusions decrease from stage i to stage iii stage i 187 382 c average 275 c stage ii 122 278 c average 175 c stage iii 92 172 c average 139 c whereas the salinities of the fluid inclusions increase from stages i to ii and decrease from stages ii to iii stage i 1 8 18 2 wt nacleqv average 10 3 wt nacleqv stage ii 7 3 24 4 wt nacleqv average 14 9 wt nacleqv stage iii 0 2 5 3 wt nacleqv average 1 5 wt nacleqv raman spectroscopy reveals that the fluid inclusions mainly contain h2o co2 is minor and h2s ch4 and n2 are rare we conclude that the formation of wolframite was driven by post magmatic thermodynamic processes the ore forming fluid flowed through a multi fractured low pressure zone in the fault system in the district and a temperature pressure decrease led to fluid immiscibility characterized by co2 escaping in a low ph and high eh environment in stage i crust mantle mixed fluid and meteoric water mixing in stage ii and natural cooling of the fluid system in stage iii

fluid regime and ore formation in the tungsten yttrium deposits of kyzyltau mongolian altai evidence for fluid variability in tungsten tin ore systems abstract the kyzyltau ore field is located in the northern part of the mongolian altai mountains w y be mo mineralization occurs in veins and stockworks in granites felsic volcanics basaltic flows and conglomerates the main ore minerals in the veins are wolframite fluorite beryl and minor molybdenite inclusions in hydrothermal quartz fluorite and beryl from veins as well as in magmatic quartz in vein hosting granites of the ulaan uul buraat uul and tsunkheg deposits were investigated using microthermometry and laser raman spectroscopy pseudosecondary primary inclusions in the kyzyltau ore veins are predominantly liquid rich aqueous inclusions containing variable amounts of co 2 as the main gas component and showing n 2 ch 4 ratios 1 secondary inclusions contain no or only trace concentrations of gases as indicated by clathrate melting the t h values of pseudosecondary primary inclusions in veins are between 180 and 433 c fluid inclusion data indicate that phase separation processes leading to fluid immiscibility occurred in vuggy quartz ii and green fluorite ii in the ulaan uul and buraat uul ore veins phase separation pressures of 100 350 bars were estimated fluorite i from the kyzyltau ore field shows a strong enrichment of hree and a strong negative eu anomaly common for rare metal bearing ore systems fluorite ii from buraat uul and tsunkheg is characterized by a change in the incorporation of rare earth elements ree with decreasing hree contents and a decreasing eu anomaly the ree distribution patterns in fluorite ii from ulaan uul remained unchanged compared with fluorite i despite a strong increase in the total ree content a review of the literature shows that from high temperature fe rich k dominated brines cassiterite ores can precipitate in quartz veins together with fe chlorite and fe tourmaline bolivian type if phase separation of a gas rich low salinity and fe rich fluid occurs cassiterite wolframite ores may be deposited cornwall devon type the deposits of kyzyltau are characterized by low fe alteration assemblages a predominance of sodium over potassium high contents of ree and y and a lack of extended tin mineralization despite the tin potential of the ore systems fluid inclusion data as well as geochemical and geological indications suggest formation of the tungsten deposits near the tops of li f rich sub volcanic intrusions we interpret the ph of the mineralizing fluid to be the main factor controlling wolframite precipitation in the kyzyltau ore field fluid wall rock interactions a lowering of the temperature and unmixing processes in the ore fluid generated contributions to neutralization and buffering of the acid co 2 bearing fluid into a ph range where tungstates were precipitated it can be inferred that formation of tungsten ores without precipitation of extended tin mineralization is possible in deposits characterized by high potential tin and tungsten according to this inference tin mineralization may be found in a more favourable setting in the vicinity of the kyzyltau deposits

invisible gold in arsenian pyrite and arsenopyrite from a multistage archaean gold deposit sunrise dam eastern goldfields province western australia the sunrise dam gold mine 11 1 moz au is the largest deposit in the archaean laverton greenstone belt eastern goldfields province yilgarn craton western australia the deposit is characterized by multiple events of fluid flow leading to repeated alteration and mineralization next to a major crustal scale structure the au content of arsenian pyrite and arsenopyrite from four mineralizing stages d1 d3 d4a and d4b and from different structural and lithostratigraphic environments was measured using in situ laser ablation inductively coupled plasma mass spectrometry pyrite contains up to 3 067 ppm au n 224 whereas arsenopyrite contains up to 5 767 ppm n 19 gold in arsenopyrite d4a stage was coprecipitated and remained as invisible gold nanoparticles and or lattice bound during subsequent deformation events in contrast gold in pyrite is present not only as invisible gold but also as micrometer size inclusions of native gold electrum and au ag tellurides pristine d1 and d3 arsenian pyrite contains relatively low au concentrations 26 ppm the highest au concentrations occur in d4a arsenian rich pyrite that has recrystallized from d3 pyrite textures show that this recrystallization proceeded via a coupled dissolution reprecipitation process and this process may have contributed to upgrading au grades during d4a in contrast au in d4b pyrite shows grain scale redistribution of invisible gold resulting in the formation of micrometer scale inclusions of au minerals the speciation of au at sunrise dam and the exceptional size of the deposit at province scale result from multiple fluid flow and multiple au precipitating mechanisms within a single plumbing system

evolution and paragenetic context of low δd hydrothermal fluids from the panasqueira w sn deposit portugal new evidence from microthermometric stable isotope noble gas and halogen analyses of primary fluid inclusions abstract the evolution paragenetic context and origin of remarkably low d hydrothermal fluids from the hercynian panasqueira w sn cu ag deposit have been investigated through a combined microthermometric stable isotope halogen and noble gas fluid inclusion study large variations in d between 60 and 134 have been observed in primary fluid inclusions from growth zones in a quartz crystal pa66 paragenetically constrained to the main sulfide stage mss of ore formation the same fluids exhibited relatively constant fluid inclusion homogenisation temperatures 254 to 260 c salinities 7 4 to 8 7 wt nacl equivalent and calculated fluid 18o 3 8 to 4 4 all the fluids exhibited 40ar excesses mean molar br cl and i cl ratios varied from 2 3 10 3 4 2 10 3 and 8 10 4 10 10 4 respectively with the more br rich fluids being associated with the more deuterium depleted fluids the low palaeolatitude of panasqueira throughout the main stages of ore formation and the overwhelming predominance of meteoric fluids in the main late and post ore mineralising fluids with d of 40 to 65 lends little support for any models involving low d palaeometeoric water the limited range of 40ar cl ratios 1 1 10 5 1 6 10 5 also precludes boiling during the mss or mixing of meteoric water with highly fractionated deuterium depleted magmatic waters as viable mechanisms for producing the low d fluids the high br cl and i cl of the mss fluids indicate significant fluid interactions with organic rich sediments or metasediments in particular regionally abundant carboniferous coals or coaly sediments that are inferred to be depleted in deuterium by around 85 compared to palaeometeoric water the large range of d observed in the mss fluids may be explained by isotopic exchange of palaeometeoric water with these coals at varying water rock wt wt ratios between 0 02 and 0 002 with fluid oxygen isotopic compositions controlled by exchange with the beira schists such a model is consistent with the requirements that any satisfactory model must take into account viz i the relative constancy of temperature salinity 40ar and fluid 18o during excursions to low d ii the high i cl and br cl ratios observed and iii the coincidence of these low d fluids with the onset of precipitation of polymetallic sulfides and phosphates under reducing conditions the model indicates that meta sedimentary sources of ore forming components became increasingly important during the evolution of the panasqueira sn w deposit and accounts in part for the observed progression from oxide dominated to base metal sulfide dominated parageneses

precise molybdenite re os and mica ar ar dating of the mesozoic yaogangxian tungsten deposit central nanling district south china the yaogangxian deposit in the central nanling region south china consists of vein type ore bodies hosted in cambrian to jurassic strata and mesozoic granitic intrusions wolframite and molybdenite are the dominant ore minerals intergrown with gangue minerals of quartz feldspar phlogopite and muscovite we have carried out molybdenite re os and phlogopite and muscovite 40ar 39ar dating to better understand the timing and genesis of mineralization re os dating of eight molybdenite samples yielded model ages ranging from 152 0 3 5 to 161 1 4 5 ma with an average of 156 0 ma the re os analyses give a well defined 187re 187os isochron with an age of 154 9 2 6 ma mswd 2 4 hydrothermal phlogopite and muscovite display extremely flat 40ar 39ar age spectra phlogopite yields a 40ar 39ar plateau age of 153 0 1 1 ma whereas muscovite yields a plateau age of 155 1 1 1 ma both 40ar 39ar ages are in good agreement with the re os ages placing the timing of tungsten mineralization at about 154 ma this age is consistent with the field relationships our new data when combined with published geochronological results from other major deposits in this region suggest that large scale w sn mineralization occurred throughout the central nanling region in the late jurassic

zircon u pb molybdenite re os and muscovite ar ar isotopic dating of the xitian w sn polymetallic deposit eastern hunan province south china and its geological significance the xitian tungsten tin w sn polymetallic deposit located in eastern hunan province south china is a recently explored region containing one of the largest w sn deposits in the nanling w sn metallogenic province the mineral zones in this deposit comprise skarn greisen structurally altered rock and quartz vein types the deposit is mainly hosted by devonian dolomitic limestone at the contact with the xitian granite complex the xitian granite complex consists of indosinian late triassic 230 215 ma and yanshanian late jurassic early cretaceous 165 141 ma granites zircons from two samples of the xitian granite dated using laser ablation inductively coupled mass spectrometer la icpms u pb analysis yielded two ages of 225 6 1 3 ma and 151 8 1 4 ma representing the emplacement ages of two episodic intrusions of the xitian granite complex molybdenites separated from ore bearing quartz veins yielded a re os isochron age of 149 7 0 9 ma in excellent agreement with a weighted mean age of 150 3 0 5 ma two samples of muscovites from ore bearing greisens yielded 40ar 39ar plateau ages of 149 5 1 5 ma and 149 4 1 5 ma respectively these isotopic ages obtained from hydrothermal minerals are slightly younger than the zircon u pb age of 151 8 1 4 ma of the yanshanian granite in the xitian area indicating that the w sn mineralization is genetically related to the late jurassic magmatism the xitian deposit is a good example of the early yanshanian regional w sn ore forming event 160 150 ma in the nanling region the relatively high re contents 8 7 to 44 0 ppm average of 30 5 ppm in molybdenites suggest a mixture of mantle and crustal sources in the genesis of the ore forming fluids and melts based upon previous geochemical studies of early yanshanian granite and regional geology we argue that the xitian w sn polymetallic deposit can be attributed to back arc lithosphere extension in the region which was probably triggered by the break off of the flat slab of the palae pacific plate beneath the lithosphere

origin and evolution of w mo producing fluids in a granitic hydrothermal system geochemical studies of quartz vein deposits around the susan granite hwanggangri district republic of korea the hwanggangri mineralized district is located approximately 130 km southeast of seoul within the paleozoic ogcheon belt of south korea the jungbo suri and deogman mines in the district occur around the late cretaceous whole rock k ar age 89 0 or 2 0 ma susan granite and are located on w mo bearing quartz veins these veins fill fractures in the granite and its host rocks which comprise early paleozoic limestone rich sedimentary rocks the k ar date of vein muscovite 88 58 or 1 95 ma is very similar to that of the susan granite 89 04 or 1 95 ma indicating that w mo mineralization was associated with intrusion of the granite molybdenite and wolframite rich deposits occur within or near 285 degrees c from h 2 o co 2 fluids with salinities of 0 4 to 9 7 wt percent nacl equiv probably in response to ph increase due to boiling including co 2 unmixing of the hydrothermal fluid at pressures between 150 and 220 bars following w mo deposition the high temperature fluids gave way to progressively cooler more dilute fluids associated with scheelite base metal sulfide deposition 200 degrees 320 degrees c 0 7 7 2 wt nacl equiv and carbonate fluorite deposition 105 degrees 225 degrees c 0 0 3 2 wt nacl equiv these trends are interpreted as the result of progressive mixing of magmatic fluids with cooler more dilute meteoric waters there is a systematic decrease in the measured and calculated isotopic compositions of hydrothermal waters with increasing paragenetic time and decreasing temperature stage i delta 18 o water 8 0 to 1 5 per mil and delta d water 56 to 74 per mil stage ii delta 18 o water 1 9 to 5 6 per mil and delta d water 88 to 95 per mil stage iii delta 18 o water 0 9 to 3 0 per mil and delta d water 93 to 97 per mil the trend reflects the progressive increase of meteoric water involvement in the mineralizing system during the cooling history of the susan granite stock molybdenum and tungsten were partitioned preferentially into a coexisting magmatic hydrothermal fluid delta 18 o 8ppm delta d 56 to 72ppm sulfur isotope analyses of hydrothermal sulfide minerals suggest an igneous source of sulfur with a delta 34 s sub sigma s value near 4 per mil following deposition of molybdenite and wolframite from magmatic fluids wolframite was dissolved or replaced by scheelite in the outer and or shallower portions of the hydrothermal system this remobilization of tungsten and later redeposition as scheelite at temperatures of 200 degrees 280 degrees c from fluids with delta 18 o 1 2ppm accompanied mixing with low temperature meteoric fluids increasing involvement of progressively larger volumes of meteoric water resulted in successive deposition of base metal sulfides fluorite and carbonates

relationships between precipitation soil water and groundwater at chongling catchment with the typical vegetation cover in the taihang mountainous region china vegetation cover plays an important role in the process of evaporation and infiltration to explore the relationships between precipitation soil water and groundwater in taihang mountainous region china precipitation soil water and water table were observed from 2004 to 2006 and precipitation soil water and groundwater were sampled in 2004 and 2005 for oxygen 18 and deuterium analysis at chongling catchment the soil water was sampled at three sites covered by grass carex humilis and carex lanceolata acacia and arborvitae respectively precipitation is mainly concentrated in rainy seasons and has no significant spatial variance in study area the stable isotopic compositions are enriched in precipitation and soil water due to the evaporation the analysis of soil water potential and isotopic profiles shows that evaporation of soil water under arborvitae cover is weaker than under grass and acacia while soil water evaporation under grass and acacia showed no significant difference both delta o 18 profiles and soil water potential dynamics reveal that the soil under acacia allows the most rapid infiltration rate which may be related to preferential flow in the process of infiltration after a rainstorm antecedent water still takes up over 30 of water in the topsoil the soil water between depths of 0 115 cm under grass has a residence time of about 20 days in the rainy season groundwater recharge from precipitation mainly occurs in the rainy season especially when rainstorms or successive heavy rain events happen

zircon u pb geochronology and hf isotopic compositions of ore related granites from huangshaping polymetallic deposit of hunan province u pb radioactive age and hf isotope composition were systematically determined by means of la mc icp ms for zircons from granophyre granite porphyry and quartz porphyry in the huangshaping polymetallic deposit of hunan province which is distributed in the west of the qianlishan qitianling ore forming belt and in the north of the nanling mountains granite belt la icp ms analysis shows that the crystallization ages of ore related porphyries are 150 1 0 4 ma 150 2 0 4 ma and 155 3 0 7 ma respectively suggesting a middle yanshanian emplacement the in situ hf isotope analysis reveals that these ore related porphyries were derived from the mixed sources of the lower crust and the mantle based on this study in combination with the tectonic background the authors hold that the formation process of huangshaping ore related porphyries might have been related to some mantle materials and formed under an extensional regime which had to do with middle late jurassic farallon izanagi triple ridge subduction and transform faults subduction

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

constraints of in situ zircon and cassiterite u pb molybdenite re os and muscovite 40ar 39ar ages on multiple generations of granitic magmatism and related w sn mineralization in the wangxianling area nanling range south china abstract the nanling range in south china hosts numerous w sn rare metal deposits associated with several cycles of polygenetic granitic intrusions in the wangxianling area of the middle nanling range igneous intrusions include the wangxianling and hehuaping granite plutons and more than 20 granite porphyry dykes the wangxianling pluton has a central phase of medium grained tourmaline two mica granite and a marginal phase of medium grained tourmaline muscovite granite the pluton hosts several tungsten deposits including shuiyuanshan and yejiwo mineralization type is dominantly scheelite greisen with subordinate scheelite skarn and wolframite quartz veins the hehuaping pluton composed of coarse grained biotite granite and granite porphyry dykes to the east of the wangxianling pluton have an associated hehuaping tin deposit with tin skarn and subordinate porphyry and greisen mineralization in situ zircon and cassiterite u pb dating molybdenite re os and muscovite 40ar 39ar dating techniques are used to refine the age spectra of granitic rocks and w sn mineralization in the wangxianling area granites of the wangxianling pluton have zircon u pb ages of 224 ma tungsten bearing quartz veins from both the shuiyuanshan and yejiwo tungsten deposits have an average molybdenite re os isochron age of 224 ma and muscovite of scheelite greisen from the shuiyuanshan tungsten deposit yields a 40ar 39ar plateau age of 214 ma the two mineralization ages are consistent with the zircon u pb age of the wangxianling pluton indicating a close association between pluton emplacement and w mineralization in the late triassic both the hehuaping pluton and granite porphyry dykes have zircon u pb ages of 156 ma in situ la icp ms u pb dating of cassiterite in both the tin skarn and tin greisen yields an average age of 156 ma showing that the sn mineralization occurred at a similar time to the late jurassic granitic magmatism thus two mineralization events are identified in the wangxianling area and include an earlier w dominant mineralization event and a later sn dominant mineralization event the earlier event is related both spatially and temporally to intrusion of the late triassic s type wangxianling granite pluton whereas the later mineralization is associated both spatially and temporally with intrusion of the late jurassic hehuaping a2 type granite pluton and a2 type granite porphyry dykes

a seismodynamical model of lithosphere deformation development of continental and oceanic rift networks seismicity and lithosphere extension on the scale of a tectonic plate are investigated in two horizontal dimensions and time using a dynamical model for a thin plate overlying a viscoelastic channel the plate consists of two layers a brittle elastic plastic crust that deforms as a result of earthquakes along faults and a strong viscoelastic layer representing the aseismic creeping lower lithosphere numerical experiments of lithosphere rifting are performed for one and two layer lithosphere models using two different rupture criteria in all the calculations earthquakes and faults of various sizes may form anywhere in the numerical domain as a result of the constitutive formulation the differences between the one and two layer model results suggest a mechanical explanation for the difference between continental and oceanic rifting when the lower lithosphere is absent a small number of faults dominate the deformation and a relatively simple narrow rift zone develops corresponding to oceanic rifting when a highly viscous lower lithosphere is included a complex distributed network of faults develops similar to continental rifting the complexity of the fault system also depends on the yield criterion in the crustal layer in our simulations complexity is greater for a yield criterion with strong shear stress dependence than for one with mainly extensional stress dependence whether a result of lower lithosphere stretching crustal heterogeneity or the yield criterion higher complexity increases the timescale for fault development increases self similarity in fault system geometry and stress and strain time series and results in power law moment frequency earthquake size scaling

pyrite and pyrrhotite textures and composition in sediments laminated quartz veins and reefs at bendigo gold mine australia insights for ore genesis the various types textures and compositional zoning of pyrite in the gold bearing saddle reefs quartz veins and surrounding sedimentary rocks provide new information on the potential source and timing of gold and arsenic and related fluid processes responsible for mineralization at bendigo nodular diagenetic pyrite in the black shale tops to sandstone turbidites is enriched in invisible gold and arsenic with mean values of 0 61 ppm au 1 300 ppm as and au ag 1 based on la icpms analyses other elements enriched in the diagenetic pyrite within the organic rich shales are mn zn mo cu v ba ag cd tl co ni bi pb and te in contrast euhedral and growth zoned hydrothermal pyrite in the turbidites and bedding parallel laminated quartz veins contains lower contents of most trace elements but has higher contents of invisible au and as especially on the outermost rim of the pyrite the gold rich pyrite rims generally become thicker a few to hundreds of microns in proximity to the gold bearing saddle reefs pyrite in the reef commonly has the highest levels of invisible au and as and the lowest levels of other trace elements it is characterized by au ag 1 and au pb 0 01 in the deepest stratigraphic levels below known productive gold reefs diagenetic pyrite in the most carbonaceous shales has been replaced by pyrrhotite during metamorphism la icpms analyses reveal that the disseminated pyrrhotite contains similar levels of ni and co to the diagenetic pyrite but is strongly depleted in as and au the spatial relationships between organic rich shales folded bedding parallel laminated quartz veins and gold arsenic bearing saddle reefs combined with the consistent trends in the trace element composition of pyrite hosted by these three geological elements is interpreted to indicate that the black shales were an initial source of au and as and the laminated quartz veins acted as the initial pathways for hydrothermal fluid flow carrying au and as from the source shales to the saddle reefs maximum gold and arsenic input into the reefs principally as free gold plus arsenopyrite occurred late during deformation toward the end of the hydrothermal cycle and is expressed by the au as rich rims to hydrothermal pyrite in the sedimentary host rocks laminated quartz veins and reefs this corresponds with final fold lockup and the development of through going fault arrays linking adjacent anticlines the source of au and as for this final and most economically important fluid flow event is considered to be from carbonaceous shales deeper in the basin where original gold bearing diagenetic arsenian pyrite reacts with organic matter and is converted to pyrrhotite with release of au as and s to the metamorphic fluid

the p v t x f o2 evolution of h2o co2 ch4 bearing fluid in a wolframite vein reconstruction from fluid inclusion studies aqueous carbonaceous and later pure aqueous fluid inclusions in quartz from a ferberite fe 95mn 05 wo4 vein within the low grade metamorphic aureole of the borne granite french massif central have been studied by microthermometry and raman spectrometry the bulk v x properties of the aqueous carbonaceous inclusions have been derived using the equation of state of heyenet al 1982 for the low temperature co2 ch4 system a p t path has been proposed for their trapping using the equations of state of jacobs and kerrick 1981a for the h2o co2 ch4 system two main episodes were reconstructed for the history of the aqueous carbonaceous fluid 1 primary h2o co2 ch4 vapourrich inclusions in quartz indicated the early circulation of a low density fluid 65 mole h2o 34 mole co2 1 mole ch4 and traces of n2 d 0 35 gcm 3 at around 550 50 c and 700 100 bar fluid cooled approximately isobarically to 450 400 c and was progressively diluted by h2o with a concomitant increase in density the fo2 of the h2oco2 ch4 fluid estimated from the equilibrium co2 2h2o ch4 2o2 first ranged from 10 22 to 10 27 bar close to the q f m buffer within analytical errors these values were consistent with the presence of graphite in equilibrium with the fluid 2 a drop in pco2 and therefore a drop in fo2 was recorded by the secondary liquid rich inclusions in quartz the inclusions formed at and below 400 c were composed of h2o and ch4 only and fo2 at that stage was below that fixed by the graphite fluid equilibrium this second episode in the fluid rock system could be explained by the drop of temperature below the blocking temperature of the graphite fluid equilibrium according to this interpretation the blocking of the graphite fluid equilibrium occurred at t 370 c and probably at 400 c on account of the pressure correction mass spectrometric data show that ferberite contains h2o co2 and ch4 in fluid inclusions which lie in the gap of the v x properties of the aqueouscarbonaceous fluid in quartz deposition of ferberite probably occurred at around 400 c the previously inferred blocking temperature resulting from either the drop in pco2 the drop fo2 and or the related ph increase it is concluded that the existence of a blocking temperature for the graphite fluid chemical equilibrium may be a critical factor for maintaining a stable fluid pressure gradient in geothermal systems occurring under greenschist facies conditions in graphite bearing rocks

la icp ms trace element analysis of pyrite from the xiaoqinling gold district china implications for ore genesis abstract the xiaoqinling district the second largest gold producing district in china is located on the southern margin of the north china craton it consists of three ore belts namely the northern ore belt the middle ore belt and the southern ore belt pyrite from the dahu gold deposit in the northern ore belt and wenyu and yinxin gold deposits in the southern ore belt were investigated using a combination of ore microscopy and in situ laser ablation inductively coupled plasma mass spectrometry la icp ms a range of trace elements was analyzed including au te ag pb bi cu co ni zn mo hg as and si the results show that there are no systematic differences between the trace element compositions of pyrite in the three deposits from different ore belts in general au concentrations in pyrite are low from 2 rich ore fluids spatial association with large scale compressional structures of the qinling orogen 18 o and d data suggestive of mixing between metamorphic and meteoric waters 34 s and pb isotopic data that point to a mixed crustal mantle source all point to typical orogenic type gold deposits high ni concentrations up to 8425 ppm of pyrite possibly linked to deep seated mafic ultramafic metamorphic rocks provide further evidence on the orogenic gold deposit affinity but against the model of a granitic derivation of the mineralizing fluid as previously suggested by some workers generally low au concentration in pyrite is also consistent with those from worldwide orogenic gold deposits therefore the gold mineralization in the xiaoqinling district is described as orogenic type and is probably related to indosinian collision between the north china craton and the yangtze craton

fluid evolution in the w cu zn pb san cristobal vein peru fluid inclusion and stable isotope evidence abstract the zn pb ag cu san cristobal district is located 100 km east of lima in the western cordillera of peru it is centred around the chumpe intrusion and is composed of vein and carbonate replacement ore types the main san cristobal vein presents a paragenesis that can be divided into three stages a an early wolframite quartz pyrite stage b a quartz base metal stage and c a late quartz carbonate barite stage fluid inclusions in quartz from the tungsten stage are biphase lv at room temperature and homogenise to the liquid phase between 146 and 257 c their salinities range between 2 1 and 5 1 wt nacl equiv rare inclusions contain an additional crystal of halite and have salinities of 46 54 wt nacl equiv data of the first two stages show a decrease in homogenisation temperatures concomitant with a salinity decline fluid inclusions in quartz from the late stage homogenise at higher temperatures between 252 and 323 c with salinities ranging between 4 6 and 6 7 wt nacl equiv hydrogen and oxygen isotope data indicate a two stage evolution isotopic compositions of the fluid associated with the first two stages define a trend with constant 18 o values and decreasing d values 18 o 3 2 to 5 0 v smow and d 60 to 112 v smow which is interpreted as mixing of a dominantly magmatic component with minor meteoric water that had equilibrated with the host rocks this interpretation is supported by sulphur and lead isotopic data from previous studies by contrast the quartz carbonate barite stage bears isotopic characteristics defining a trend with a coupled decrease of 18 o and d 18 o 8 1 to 2 5 v smow and d 57 to 91 v smow and is explained by addition of meteoric water to the system and subsequent mixing with a less important magmatic component different fluid origins are confirmed by laser ablation icp ms analyses of the triphase lvh and biphase lv primary inclusions the concentrations of the major ore elements i e w cu zn and pb decrease throughout the paragenesis w and to a lesser extent cu show significant variations associated with a steep decrease in their concentration the decreasing concentrations can be explained by mineral deposition and dilution by the meteoric fluid differences in the rate of decrease indicate selective precipitation of w fluid inclusions of the quartz carbonate stages show an abrupt increase in ba and sr concentrations this is interpreted to reflect a higher volume of host rock silicate alteration probably due to the increasing size of the fluid flow cell and is explained by the input of a third fluid of unknown origin la icp ms analyses show that the fluids were already depleted in w and cu before reaching the emplacement of carbonate replacement ore type whereas zn and pb were still present in considerable amounts this is again due to selective precipitation and is consistent with the interpretation that the economically interesting metals were dominantly introduced by magmatic fluids

distribution of groundwater arsenic in xinjiang p r china although potential contamination of groundwater as is expected to occur in xinjiang p r china few data are available for the regional distribution of groundwater as in this study the spatial distribution of groundwater as was investigated in the chepaizi cpz n and shihezi shz n areas of northern xinjiang the balikun yiwu basin by e in eastern xinjiang and the tarim trm s and yanqi yq s basins in southern xinjiang arsenic concentrations greater than 10 g l were found in 12 of analyzed groundwaters all groundwater samples collected in cpz n had as concentrations greater than 10 g l 25 185 g l 30 in shz n 10 g l was found in the eastern and southern trm s and yq s distribution of groundwater as showed a tremendous spatial variability which greatly varied over a short distance horizontally arsenic concentration generally increased with increasing sampling depth the spatial distribution of groundwater as would be regulated by as source and hydrogeochemical processes higher ph and or lower orp values were generally observed in high as groundwater 10 g l in comparison with low as groundwater 10 g l arsenic mobility in shz n and cpz n may result from as desorption under relatively high ph conditions and more tentatively from reductive dissolution of fe iii oxides in by e and trm s however detailed mechanisms of as mobilization in these regions need further investigation