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

melt inclusions in pegmatite quartz complete miscibility between silicate melts and hydrous fluids at low pressure fluorine boron and phosphorus rich pegmatites of the variscan ehrenfriedersdorf complex crystallized over a temperature range from about 700 to 500 c at a pressure of about 1 kbar pegmatite quartz crystals continuously trapped two different types of melt inclusions during cooling and growth a silicate rich h2o poor melt and a silicate poor h2o rich melt both melts were simultaneously trapped on the solvus boundaries of the silicate fluorine boron phosphorus water system the partially crystallized melt inclusions were rehomogenized at 1 kbar between 500 and 712 c in steps of 50 c by conventional rapid quench hydrothermal experiments glasses of completely rehomogenized inclusions were analyzed for h2o by raman spectroscopy and for major and some trace elements by emp electron microprobe both types of melt inclusions define a solvus boundary in an xh2o t pseudobinary system at 500 c the silicate rich melt contains about 2 5 wt h2o and the conjugate water rich melt about 47 wt h2o the solvus closes rapidly with increasing temperature at 650 c the water contents are about 10 and 32 wt respectively complete miscibility is attained at the critical point 712 c and 21 5 wt h2o many pegmatites show high concentrations of f b and p this is particularly true for those pegmatites associated with highly evolved peraluminous granites the presence of these elements dramatically reduces the critical pressure for fluid melt systems at shallow intrusion levels at t 720 c water is infinitely soluble in a f b and p rich melt simple cooling induces a separation into two coexisting melts accompanied with strong element fractionation on the water rich side of the solvus very volatile rich melts are produced that have vastly different physical properties as compared to normal silicate melts the density viscosity diffusivity and mobility of such hyper aqueous melts under these conditions are more comparable to an aqueous fluid

late collisional granites in the variscan erzgebirge germany the late collisional erzgebirge granites 325 318 ma were introduction emplaced at shallow crustal levels in the variscan metamorphic the erzgebirge is a ne sw trending antiformal structure basement shortly after large scale extension caused by orogenic exposing variscan crystalline basement rocks at the northcollapse these granites comprise mildly peraluminous transitional ern margin of the bohemian massif the region is famous i s types and strongly peraluminous s type rocks which can be among economic geologists for its extensive and highly subdivided into three major groups low f biotite granites low f variable metallic ore deposits which have been mined two mica granites and high f high p2o5 li mica granites the since the middle ages e g stemprok seltmann 1994 highest degree of differentiation is reached in the li mica granites tischendorf forster 1994 and for the classic studies which exhibit strongly elevated concentrations of p f li rb cs in the fields of economic geology mining and metallurgy ta sn w and u but very low ti mg co ni sr ba y zr chemistry and mineralogy e g werner 1791 breithaupt hf th and rare earth elements crystal melt fractionation is the 1849 agricola 1974 dominant process controlling the bulk composition of all groups of as in many of the other variscan provinces in central granites however metasomatic processes involving late stage residual europe granitic rocks make up a large proportion of the melts and high t orthomagmatic fluids became increasingly more exposed rocks in the erzgebirge and a great variety of important in highly evolved units and have modified the abundances compositional and textural types occur fig 1 knowof mobile elements p f li rb cs ba sr in the li mica ledge of the processes involved in the generation and granites particularly isotopic and geochemical characteristics suggest evolution of these silicic magmas is essential for underthat the three granite groups cannot be derived from a common standing heat and mass transport during the variscan precursor magma their discrete compositions are source related orogeny and also for the formation of metallic ore and are attributed to melting of quartzo feldspathic and pelitic deposits several lines of evidence indicate that early crustal lithologies in different proportions granites are common in high temperature sn w deposits are associated with the the central european variscides but the erzgebirge is unusual for emplacement of highly evolved volatile rich granitic the predominance of evolved li mica granites associated with melts tischendorf 1986 forster tischendorf 1992 economically important sn w and u deposits the abundance of stemprok 1993 the role of the granites in formation of li mica granites is attributed to a combination of favourable factors later permian u pb zn and younger ore mineralization 1 low degrees of anatectic melting of crustal protoliths 2 wide f ba is controversial but good evidence exists that the distribution of fertile lithologies rich in large ion lithophile elements vein type u deposits owe their uranium to leaching from and ore elements 3 extended magmatic differentiation by crystal the uraninite rich granites e g tischendorf forster melt fractionation and subsequent autometasomatism 1994

quartz and feldspar zoning in the eastern erzgebirge volcano plutonic complex germany czech republic evidence of multiple magma mixing abstract zoned quartz and feldspar phenocrysts of the upper carboniferous eastern erzgebirge volcano plutonic complex were studied by cathodoluminescence and minor and trace element profiling the results verify the suitability of quartz and feldspar phenocrysts as recorders of differentiation trends magma mixing and recharge events and suggest that much heterogeneity in plutonic systems may be overlooked on a whole rock scale multiple resorption surfaces and zones element concentration steps in zoned quartz ti and feldspar phenocrysts anorthite content ba sr and plagioclase mantled k feldspars etc indicate mixing of silicic magma with a more mafic magma for several magmatic phases of the eastern erzgebirge volcano plutonic complex generally feldspar appears to be sensitive to the physicochemical changes of the melt whereas quartz phenocrysts are more stable and can survive a longer period of evolution and final effusion of silicic magmas the regional distribution of mixing compatible textures suggests that magma mingling and mixing was a major process in the evolution of these late variscan granites and associated volcanic rocks quartz phenocrysts from 14 magmatic phases of the eastern erzgebirge volcano plutonic complex provide information on the relative timing of different mixing processes storage and recharge allowing a model for the distribution of magma reservoirs in space and time at least two levels of magma storage are envisioned deep reservoirs between 24 and 17 km the crystallisation level of quartz phenocrysts and subvolcanic reservoirs between 13 and 6 km deflation of the shallow reservoirs during the extrusion of the teplice rhyolites triggered the formation of the altenberg teplice caldera above the eastern erzgebirge volcano plutonic complex the deep magma reservoir of the teplice rhyolite also has a genetic relationship to the younger mineralised a type granites as indicated by quartz phenocryst populations the pre caldera biotite granites and the rhyodacitic schonfeld volcanic rocks represent temporally and spatially separate magma sources however the deep magma reservoir of both is assumed to have been at a depth of 24 17 km the drastic chemical contrast between the pre caldera schonfeld westfalian b c and the syn caldera teplice westfalian c d volcanic rocks is related to the change from late orogenic geotectonic environment to post orogenic faulting and is considered an important chronostratigraphic marker

crystallization of the little three layered pegmatite aplite dike ramona district california subhorizontally layered pegmatite aplite bodies are characterized by fine grained sodic to granitic aplite that is usually juxtaposed abruptly above by much coarser grained commonly graphic potassic pegmatite although well studied there currently is little concensus as to how such dikes form the little three dike near ramona california is representative of such zoned bodies in this and other regions and contains discontinuous miarolitic pockets near the base of the graphic pegmatite zone tourmaline garnet biotite and muscovite show no changes in major or minor element compositions indicative of progressive magmatic fractionation until the immediate vicinity of the main miarolitic zone where they record abrupt and extreme enrichments in li f and mn there is no correlation of chemical changes in the dike with the appearance of small miarolitic vugs well below the main miarolitic zone nor is there any indication that the aplite graphic pegmatite or miarolitic pockets represent separate magma injections the chemistries of tourmaline garnet and micas however preclude conventional models of rayleigh fractionation or traditional zone refining textural features and modeled cooling histories indicate that the dike cooled quickly and might have solidified partially or totally to glass before crystallization commenced geothermometry based on the compositions of coexisting plagioclase and homogeneous nonperthitic k feldspar indicates inward crystallization of the dike from 400 435 c at the margins to 350 390 c within 20 30 cm of the pocket horizon then a sharp decrease to 240 275 c in the pockets where k feldspar is perthitic we interpret the feldspar geothermometry except perhaps in the miarolitic cavities to reflect the temperatures at crystallization fronts that advanced into the pegmatite first from the foot wall and eventually joined by a similar front downward from the hanging wall crystallization down from the hanging wall may have commenced after 70 80 of the foot wall aplite had crystallized the very abrupt increases of li mn and f in tourmaline and garnet near the miarolitic zone appear to be explained best by the process of constitutional zone refining in which a fluxed crystallization front sweeps an incompatible element enriched boundary layer through a solid or semi solid after these two highly fluxed boundary layers merged near the main miarolitic zone compositional evolution could have proceeded by crystal melt fractionation

behavior of trace elements in quartz from plutons of different geochemical signature a case study from the bohemian massif czech republic article i nfo in this study the trace element content in igneous quartz from granitoids of different geochemical types was investigated using the laser ablation icp ms technique the variscan granitoids in the bohemian massif pro vide an excellent opportunity to study the chemical composition of magmatic quartz from the following granite types 1 geochemically primitive i type tonalites and granodiorites 2 peraluminous s type two mica granites 3 moderately fractionated a type volcano plutonic complexes of the teplice caldera and 4 highly fractionated s and a type rare metal granites this diversity of granitoids permitted the study of the chemical composition of magmatic quartz as the result of i different magma protoliths and ii variable degrees of differentiation there were only small differences in the quartz trace element con tents ranging from weakly to moderately differentiated plutons of all geochemical types al mostly in the range between 20 and 250 ppm ti mostly 20 110 ppm b b13 ppm be b0 7 ppm ge b1 ppm li b30 ppm and rb b2 ppm only the s type granites from western erzgebirge contain al enriched quartz mostly 200 400 ppm al since the beginning of its evolution however quartz from the highly fractionated granites group 4 differs significantly this quartz is generally poor in ti b20 ppm ti and enriched in al up to 600 ppm in a type and up to 1000 ppm in s type granites be up to 3 2 ppm ge up to 5 7 ppm li up to 132 ppm particularly in the s type granites and rb up to 15 ppm the contents of the analyzed lithophile elements in the quartz from the highly fractionated granites are similar to the contents reported to be present in evolved complex pegmatites although the input of ti into quartz is controlled mainly by the temperature and pressure of quartz crystallization the entry of al into quartz increases as a function of the water and fluorine content of the residual melt the contents of ge and li increase significantly with the fractionation of parental melt the concentrations of these elements in quartz from highly fractionated granites are controlled by the order of crystallization of the major minerals comb quartz crystallizing before li mica is strongly li enriched whereas groundmass and snowball quartz crystallizing after mica is relatively enriched in ge

liquid immiscibility and its role at the magmatic hydrothermal transition a summary of experimental studies several types of fluid immiscibility may affect the evolution of volatile rich magmatic systems at the magmatic hydrothermal transition the topology of silicate salt h2o systems implies that three fluid immiscibility silicate melt hydrosaline melt vapour should be stable in a broad range of compositions and p t conditions the most important factor controlling the immiscibility appears to be the coulombic properties electric charges z and ionic radii r of the main network modifying cations and the capacity for immiscibility appears to decrease in the following sequence mg ca sr ba li na k liquid immiscibility is enhanced in peralkaline compositions and in the presence of nonsilicate anions such as f cl co32 and bo33 in volatile rich magmatic systems the h2o is likely to react with the chloride fluoride borate and carbonate species and the chemical effects of high temperature hydrolysis may be greatly enhanced by phase separation in systems with multiple immiscible fluid phases natural granitic magmas can thus exsolve a range of chemically and physically diverse hydrosaline liquids and the role of these fluid phases is likely to be especially significant in pegmatites and li f rare metal granites

a petrologic assessment of internal zonation in granitic pegmatites abstract cameron et al 1949 devised the nomenclature and delineated the patterns of internal zonation within granitic pegmatites that are in use today zonation in pegmatites is manifested both in mineralogy and in fabric mineral habits and rock texture although internal zonation is a conspicuous and distinctive attribute of pegmatites there has been no thorough effort to explain that mineralogical and textural evolution in relation to the zoning sequence presented by cameron et al 1949 or in terms of the comprehensive petrogenesis of pegmatite bodies pressure temperature and whole rock composition this overview of internal zonation within granitic pegmatites consists of four principal parts 1 a historic review of the subject 2 a summary of the current understanding of the pegmatite forming environment 3 the processes that determine mineralogical and textural zonation in pegmatites and 4 the applications of those processes to each of the major zones of pegmatites based on the concepts presented in london 2008 the fundamental determinates of the internal evolution of pegmatite zones are 1 the bulk composition of melt 2 the magnitude of liquidus undercooling prior to the onset of crystallization 3 subsolidus isothermal fractional crystallization by which eutectic or minimum melts fractionate by sequential non eutectic crystallization 4 constitutional zone refining via the creation of a boundary layer liquid chemically distinct from but continuous with the bulk melt at the crystallization front and 5 far field chemical diffusion the long range and coordinated diffusion of ions particularly of alkalis and alkaline earths through melt

formation of extremely f rich hydrous melt fractions and hydrothermal fluids during differentiation of highly evolved tin granite magmas a melt fluid inclusion study quartz crystals from topaz zinnwaldite albite granites from zinnwald erzgebirge germany contain in addition to primary and secondary fluid inclusions fis abundant crystalline silicate melt inclusions mis with diameters up to 200 m these mis represent various stages of evolution of a highly evolved melt system that finally gave rise to granite related sn w mineralization the combination of special experimental techniques with confocal laser raman microprobe spectroscopy and empa permits precise measurement of elevated contents of h2o f and b in re homogenized mis the contents of h2o and f were observed to increase from 3 to 30 and 1 9 to 6 4 wt respectively during magma differentiation however there is a second mi group very rich in h2o with values up to 55 wt h2o and an f concentration of approximately 3 wt ongoing enrichment of volatiles h2o f b and cl and of cs and rb can be explained in terms of magma differentiation triggered by fractional crystallization and thus is suggested to reflect elemental abundances in natural magmas and not boundary layer melts partitioning between melt and cogenetic fluids has further modified the magmatic concentrations of some elements particularly sn the coexistence of two types of mis with primary fis indicates fluid saturation early in the history of magma crystallization connected with a continuous sequestration of sn f and b the results of this study provide additional evidence for the extraordinary importance of the interplay of h2o f and b in the enrichment of sn during magma differentiation by decreasing the viscosity of and increasing the diffusivity in the melts as well as by the formation of various stable fluoride complexes in the melt and coexisting fluid

distribution and petrogenetic behaviour of trace elements in granitic pegmatite quartz from south norway the present study documents that the trace element distribution in granitic quartz is highly sensitive to cafc processes in granitic melts igneous quartz efficiently records both the origin and the evolution of the granitic pegmatites aluminium p li ti ge and na in that order of abundance comprises 95 of the trace elements most samples feature 1 ppm of any of these elements the remnant 5 includes k fe be b ba and sr whereas the other elements are present at concentrations lower than the detection limit potassium fe be and ti are relatively compatible hence obtain the highest concentrations in early formed quartz phosphorous ge li and al are relatively incompatible and generally obtain the highest concentrations in quartz that formed at lower temperatures from more evolved granitic melts the ge ti the ge be the p ge and the p be ratios of quartz are strongly sensitive to the origin and evolution of the granitic melts and similarly the rb sr and the rb k ratios of k feldspars may be utilised in petrogenetic interpretations however the quartz trace element ratios are better at distinguishing similarities and differences in the origin and evolution of granitic melts after evaluating the different trace element ratios the ge ti ratio appears to be most robust during subsolidus processes in the igneous systems hence probably should be the preferred ratio for analysing and understanding petrogenetic processes in granitic igneous rocks

origin of ti rich rims in quartz phenocrysts from the upper bandelier tuff and the tunnel spring tuff southwestern usa four compositionally zoned melt inclusion bearing quartz phenocrysts from the upper bandelier tuff new mexico and the tunnel spring tuff utah were examined in detail by cathodoluminescence laser ablation icp ms and titanium in quartz titaniq thermobarometry in order to reconstruct the conditions of quartz crystallization temperature and tio2 activity atio2 in the magma were estimated from melt inclusion compositions by means of zircon saturation thermometry and an experimentally calibrated tio2 solubility model whereas pressure was estimated with the most recent calibration of the titaniq thermobarometer on the host quartz next to the analyzed melt inclusions all four investigated quartz phenocrysts display a low luminescent ti poor core overgrown by a high luminescent ti rich rim reconstructed p t atio2 conditions suggest that the rimward increase in the ti content of the two quartz crystals from the upper bandelier tuff is due to a combination of increasing temperature increasing atio2 and decreasing pressure with the temperature effect being dominant in one crystal and the atio2 effect being dominant in the other crystal in the two crystals from the tunnel spring tuff the rimward increase in ti content is mostly due to increasing temperature but in one of them a negative pressure change played an equally important role this study demonstrates that in rapidly cooled peraluminous or metaluminous rhyolites the crystallization conditions of quartz phenocrysts can be reconstructed at the scale of individual growth zones which allows to investigate the origin and evolution of such magmas in great detail

implications from inclusions in topaz for greisenisation and mineralisation in the hensbarrow topaz granite cornwall england textural and geochemical studies of inclusions in topaz from greisens in the hensbarrow topaz granite stock st austell cornwall are used to constrain the composition of fluids responsible for late stage greisening and mineralisation the topaz contains an abundant and varied suite of inclusions including aqueous liquid vapour l v quartz zinnwaldite albite k feldspar muscovite ilmenorutile apatite columbite zircon varlamoffite sn fe o oh 2 and qitianlingite fe 2 mn 2 2 nb ta 2w 6o10 primary l v inclusions in topaz show relatively high th mainly 300 to 500 c and a narrow range of salinities 23 30 wt nacl equivalent compared with those in greisen quartz 150 450 c 0 50 wt nacl equivalent textures indicate that topaz formed earlier than quartz and the fluid inclusion data are interpreted as indicating a cooling of the hydrothermal fluids during greisenisation mixing with meteoric waters and a decrease in pressure causing intermittent boiling the presence of early formed albite and k feldspar as inclusions in the topaz is likely to indicate that the greisen forming fluid became progressively more acid during greisenisation the most distinctive inclusions in the topaz are wisp and bleb shaped quartz 50 m in size which show textural characteristics indicating former high degrees of plasticity they often have multiple shrinkage bubbles at their margins rich in sn fe mn s and cl and more rarely contain euhedral albite k feldspar stannite or pyrrhotite crystals up to 40 m in size the quartz inclusions show similar morphologies to inclusions in topaz from quartz topaz rocks elsewhere which have been interpreted as trapped silicate melt their compositions are however very different to those expected for late stage topaz normative granitic melts from their textural and chemical characteristics they are interpreted as representing crystallised silica colloid probably trapped as a hydro gel during greisenisation there is also evidence for the colloidal origin of inclusions of varlamoffite in the topaz these occurrences offer the first reported evidence in natural systems for the formation of colloids in high temperature hydrothermal fluids their high ore carrying potential is suggested by the presence of varlamoffite and the occurrence of stannite pyrrhotite and sncl within the quartz inclusions

revisiting complete miscibility between silicate melts and hydrous fluids and the extreme enrichment of some elements in the supercritical state consequences for the formation of pegmatites and ore deposits abstract using water and major and trace element data obtained from melt inclusions primarily in pegmatite quartz we have shown in this and previous papers that melt melt fluid immiscibility is widespread and an important process during the generation of granitic pegmatites furthermore we have shown that the formation of pegmatites actually begins in the supercritical melt fluid stage in this study we extend previous work and in particular explore the behavior of 10 different elements be f p s cl as rb sn cs and ta in the supercritical range from preliminary studies we suggest that other elements such as b na k zn nb and sb will behave similarly near the solvus crest of a generalized pseudo binary melt water system this provides important evidence that pegmatite forming processes have already begun at high temperatures in the range of 850 750 c and that may require a re think on the partitioning behavior of metals in late stage residual melts exsolved from granitic magmas the existence of this parental supercritical silicate melt fluid although derived from granitic magmas imposes significant constraints of its own so drawing conclusions about pegmatite forming processes from data gained from slightly modified granite compositions becomes highly problematic we propose that the extremely high concentration of some elements over a small but well defined water concentration range symmetrically distributed around the critical point of the pseudo binary solvus must be derived from the unusual properties of the near critical or supercritical phases these unusual properties include extremely low density viscosity and surface tension and high diffusivity reactivity and mobility these are exactly the qualities that make such supercritical fluids an excellent medium for the formations of pegmatites by reactions with the existing matrix melt crystal mush and for the extreme enrichment of some ore forming elements highly soluble in alkali and water rich supercritical fluids a very important point in mineral crystallization is the non uniform local enrichment of rare and economically significant elements at specific locations in pegmatites granites and other rocks given the properties of the supercritical phase identified from melt inclusions the process of ostwald ripening can operate very effectively the driving force for ostwald ripening arises because the concentration of solute in the vicinity of small crystals or clusters is greater than and in the vicinity of larger crystals or clusters less than the average supersaturation the solute in the supercritical fluid therefore flows from the small crystals to the larger crystals and permits the growth of very large crystals at the expense of smaller ones this is favored by the extraordinary properties of supercritical fluids given the low surface tension the supercritical fluid can move also through grain boundaries and small channels or dislocation pipes aiding incompatible element transport additionally their consequences for the formation of some important granite related ore deposits are briefly outlined

water in granite and pegmatite forming melts article i nfo in this paper we have compiled water concentration data obtained from melt inclusion in minerals mostly quartz and topaz from granites and pegmatites a small number of data come from analysis of natural glasses about 4600 melt inclusions are from granites and about 2100 melt inclusions are from pegmatites another 4159 values are from melt inclusions and glasses of rocks with more than 66 g g sio2 are added belonging to a recent compilation the total of 10 859 melt inclusions provides a statistically significant basis from which to derive some conclusions generally the water concentration in granite melt inclusion is b10 g g with three maxima at 4 0 1 3 5 9 1 2 and 8 1 1 1 g g water for pegmatites a larger range of water contents was found from 2 to more than 50 g g water with two distinct maxima at 10 5 8 1 and 26 2 14 3 g g we show that the great spread and the generally high water content of the pegmatite forming melts as sampled by melt inclusions are the result of melt melt immiscibility pro cesses connected with the formation of conjugate melt fraction with contrasting physical and chemical char acteristics which have also a major influence on the element partitioning between such fractions in this paper we also discuss viscosity as an important transport property of natural silicate melts and we show that due to high primary water concentration in the pegmatite forming melts their viscosity is very low over a wide range of temperatures in the case of water rich peralkaline melt fractions the viscosity can decrease still further together these suggest that liquidus undercooling as the major cause of pegmatite textures is redundant furthermore we demonstrate that the effect of boron carbonates and bicarbonates on pegmatite melts these two last mostly ignored in the past have a large influence on the melt structure and they enable pegmatite formation in the absence of the usual discussed fluxing elements such as f and p

trace element evolution of quartz in the charnockitic kleivan granite sw norway the ge ti ratio of quartz as an index of igneous differentiation article i nfo trace element analyses of quartz from the layered charnockitic kleivan granite in the rogaland igneous province rogaland municipality sw norway reveal that the trace element composition of quartz can track igneous evolution during differentiation of the magma combined sem cl imaging and la icp ms analyses allow identification and analysis of primary igneous quartz al ti li and ge are the most abundant trace elements in the kleivan quartz and each element shows a characteristic evolution during differentiation of the granitic magma the ge ti ratio of quartz is a reliable index of the magmatic evolution of granitic igneous systems since ti and ge show pronounced compatible and incompatible characteristics respectively the temperature of the quartz crystallisation varies from 850 c during charnockite formation to 645 c in the most evolved aplitic granite and granitic pegmatite therefore the regular evolution of ti and ge in quartz during cooling of the melt may be used as an igneous geothermometer the li evolution pattern of quartz is mostly controlled by the li content of the melt hence by the absence or presence of li bearing phases forming during solidification of the melt al in quartz is controlled by the aluminium saturation index of the melt accordingly al in quartz is constant during crystallisation of a metaluminous magma and increases during peraluminous conditions the study of rock mineralogy and whole rock geochemistry are not the only methods that can be used to assess the petrogenesis of silica oversaturated rocks the purpose of this study is to demonstrate that the trace element chemistryof quartz and inparticular the ge ti ratio can be used as a petrogenetic tool to characterise an evolving igneous system and can provide information that otherwise may be difficult to obtain quartz is a good mineral for recording and storing the differentiation processes in granitic systems compared to other

melt inclusions in quartz from an evolved peraluminous pegmatite geochemical evidence for strong tin enrichment in fluorine rich and phosphorus rich residual liquids abstract we have investigated the magmatic evolution of a late stage f and p rich pegmatite forming aluminosilicate liquid and the geochemical controls on magmatic mineralizing processes by remelting totally crystallized melt inclusions in quartz and analyzing the quenched glass by epma and sims the quartz phenocrysts were sampled from a pegmatite that occurs in a variscan granite genetically associated with cassiterite and wolframite mineralized greisen veins at the ehrenfriedersdorf sn w deposit central erzgebirge se germany the melt inclusion compositions imply that the pegmatite forming liquid achieved extreme levels of chemical differentiation it contained high abundances of sn f p li rb cs nb ta and be and abnormally low concentrations of ca y sr and ree for a granite and it was strongly peraluminous the molar al 2 o 3 cao na 2 o k 2 o ranged from 1 3 to 2 0 fractions of the pegmatite forming liquid were extremely enriched in p 2 o 5 f al 2 o 3 and the molar abundances of f p in the glasses correlate strongly with moles of network modifying al ions implying that the bulk liquid included f p and al bearing complexes formation of these complexes reduced the activities of f p and al in bulk liquid suppressed the crystallization of magmatic topaz and p rich minerals and allowed the liquid to become enriched in these constituents some fractions of the ehrenfriedersdorf aluminosilicate liquid contained 1000 2000 ppm sn these levels of sn enrichment were up to 2 orders of magnitude greater than that ever reported for nonmineralized metaluminous and peraluminous igneous materials and are consistent with some experimentally derived sn solubilities in cassiterite saturated granitic liquids at geologically relevant pressures and temperatures this concordance implies that cassiterite could have crystallized directly from this highly evolved p and f rich peraluminous granitic liquid without the involvement of hydrothermal fluids

rutile solubility in hydrous rhyolite melts at 750 900 c and 2 kbar with application to titanium in quartz titaniq thermobarometry abstract the solubility of rutile in water saturated haplogranite melts with molar al na k ratios ranging from 0 84 to 1 25 was determined at 750 900 c and 2 kbar in cold seal pressure vessel experiments due to the low diffusivity of ti at these conditions a new method was developed to determine tio2 solubility in this method glasses with tio2 gradients were used as starting material and after the experiments the tio2 content was measured at the contact between rutile bearing and rutile free glass the glasses were either directly equilibrated at the desired p t conditions i e crystallization experiments or first treated at 50 150 c lower temperatures and then subjected to the desired conditions i e dissolution experiments the results obtained in crystallization and dissolution experiments agree well with each other suggesting that equilibrium was attained rutile solubility in peralkaline melts strongly increases with temperature and the amount of excess alkalies according to the relation log tio 2 wt 1 8 ank 0 53 10 000 t 12 8 ank 4 3 in which ank is the deviation of the molar al na k ratio from unity and t is given in kelvin excess alumina does not seem to promote tio2 solubility for natural melt compositions it was found that if ca mg and fe are assumed to be 10 times less effective in promoting tio2 solubility than excess na and k good fits to previous solubility data in silicic 70 wt sio2 melts at upper crustal pressures 10 kbar are obtained application of this extended tio2 solubility model to natural melt inclusions in quartz phenocrysts from five silicic volcanic systems returns tio2 activities that are similar to those calculated with a previous experiment based model and to those calculated from pairs of coexisting fe ti oxides but are up to 2 9 times higher than those calculated with melts and rhyolite melts pressures calculated from ti concentrations in the host quartz using the most recent calibration of the titaniq thermobarometer are in good agreement with independent pressure estimates suggesting that at upper crustal conditions this calibration is valid

titaniq a titanium in quartz geothermometer titanium is one of many trace elements to substitute for silicon in the mineral quartz here we describe the temperature dependence of that substitution in the form of a new geothermometer to calibrate the titaniq thermometer we synthesized quartz in the presence of rutile and either aqueous fluid or hydrous silicate melt at temperatures ranging from 600 to 1 000 c at 1 0 gpa the ti contents of quartz in ppm by weight from 13 experiments increase exponentially with reciprocal t as described by text log left x text qtz text ti right 5 69 pm 0 02 frac 3765 pm 24 t k application of this thermometer is straightforward typically requiring analysis of only one phase quartz this can be accomplished either by epma for crystallization temperatures above 600 c or by sims for temperatures down to at least 400 resulting temperature estimates are very precise usually better than 5 c potentially allowing detailed characterization of thermal histories within individual quartz grains although calibrated for quartz crystallized in the presence of rutile the thermometer can also be applied to rutile absent systems if tio2 activity is constrained

petrological and geochemical evolution of the kymi stock a topaz granite cupola within the wiborg rapakivi batholith finland abstract the 6 3 km kymi monzogranite stock represents the apical part of an epizonal late stage pluton that was emplaced within the 1 65 to 1 63 ga wiborg rapakivi batholith the stock has a well developed zonal structure from the rim to the center stockscheider pegmatite equigranular topaz granite porphyritic topaz granite the contact between the two granites is usually gradational within a few centimeters but local inclusions of the porphyritic granite in the equigranular granite indicate that the latter solidified later hydrothermal greisen and quartz veins some of which contain genthelvite beryl wolframite cassiterite and sulfides cut the granites of the stock and the surrounding country rocks the equigranular granite contains 1 to 4 vol topaz and its biotite is lithian siderophyllite the porphyritic granite has 0 to 3 vol topaz and the mica is siderophyllite the equigranular granite is geochemically highly evolved with elevated li rb ga ta and f and very low ba sr ti and zr the ree patterns show deep negative eu anomalies and tetrad effects indicating extreme magmatic fractionation and aqueous fluid rock interaction the zonal structure of the stock is interpreted as a result of differentiation within the magma chamber internal convection in the crystallizing magma chamber and upward flow of residual melt as a boundary layer along sloping contacts resulted in accumulation of a layer of highly evolved volatile rich magma in the apical part of the chamber crystallization of this apical magma produced the stockscheider pegmatite and the equigranular granite the underlying crystal mush solidified as the porphyritic granite much of the crystallization took place from volatile saturated melt and episodic voluminous degassing expelled fluids into opened fractures where they or their derivatives reacted with country rocks and caused alteration and mineralization

rutile saturation in hydrous siliceous melts and its bearing on ti thermometry of quartz and zircon the tio2 solubility of rutile saturated hydrous siliceous melts has been investigated at p 1 gpa and t 650 1000 c for several representative felsic compositions the dissolution of a rutile crystal into a tio2 undersaturated melt provides information on both tio2 solubility and ti diffusion results of this study confirm that tio2 solubility is strongly dependent on both temperature and melt composition but not on the amount of h2o present for a given t t io2 content decreases as the melts become more felsic the solubility of tio2 is given by log ti ppm 7 95 5305 t 0 124fm

variscan silicic magmatism and related tin tungsten mineralization in the erzgebirge slavkovský les metallogenic province integration of geochemical mineralogical isotopic and geochronological data with geodynamic considerations suggests that the variscan granites in the erzgebirge slavkovsk les domain originated from repeated melting events and were emplaced over a period of about 40 ma 330 290 ma several lines of evidence exist supporting the idea that erzgebirge granites assigned to different types biotite granites two mica granites strongly peraluminous p rich li mica granites and slightly peraluminous p poor granites are in most cases not genetically related via continuous fractional crystallization from a common magmatic reservoir the genesis of the slavkovsky les granites however might be discussed in terms of an uninterrupted fractionation series geological models of sn w deposits based upon geochemical and structural results imply that the main ore depositional events followed immediately the emplacement and solidification processes of melt via fluid melt immiscibility breccia pipe formation and or pervasive rock fluid interactions

crystallization conditions and evolution of magmatic fluids in the harney peak granite and associated pegmatites black hills south dakota evidence from fluid inclusions abstract a microthermometric study of inclusions in granites and pegmatites in the proterozoic harney peak granite system identified four types of inclusions type 1 inclusions are mixtures of co2 and h2o and have low salinities on average 3 5 wt nacleq type 2 inclusions are aqueous solutions of variable salinities from 0 to 40 wt nacleq type 3 inclusions are carbonic dominated by co2 with no detectable water and type 4 inclusions consist of 20 to 100 solids with the remaining volume occupied by a co2 h2o fluid many inclusions have a secondary character however a primary character can be unambiguously established in several occurrences of the type 1 inclusions these inclusions were trapped above the solidus and represent the exsolved magmatic fluid the secondary populations of types 1 2 and 3 probably formed as a result of reequilibration and unmixing of the type 1 fluid that progressively changed composition and density with decreasing temperature and pressure and was finally trapped along healed microfractures under subsolidus conditions type 4 inclusions are primary and are interpreted to be trapped fluid bearing complex silicate melts that subsequently solidified or underwent other posttrapping changes it is demonstrated that primary type 1 fluid inclusions that coexist with crystallized melt inclusions in the complex li bearing tin mountain pegmatite were trapped along the two fluid phase boundary in the system co2 h2o nacleq consequently the temperature and pressure conditions of trapping are identical to the bulk homogenization conditions on average 340 c and 2 7 kbar these conditions indicate that this li cs rb p and b rich pegmatite crystallized at some of the lowest known temperatures for a silicate melt in the crust an internally consistent empirical solvus surface in p t xco2 coordinates was generated for the pseudobinary co2 h2o 4 3 wt nacleq pegmatite fluid system distribution coefficients for the major species co2 h2o nacl and ch4 between the immiscible co2 rich and h2o rich fluid phases as a function of pressure and temperature were extracted from data for the two cogenetic fluid inclusions types

genesis of the proterozoic mangabeira tin indium mineralization central brazil evidence from geology petrology fluid inclusion and stable isotope data abstract the mangabeira deposit is the only known brazilian tin mineralization with indium it is hosted in the paleo to mesoproterozoic mangabeira within plate granitic massif which has geochemical characteristics of nyf fertile granites the granitic massif is hosted in archean to paleoproterozoic metasedimentary rocks ticunzal formation paleoproterozoic peraluminous granites aurumina suite and a granite gneiss complex the mineralized area comprises evolved li siderophyllite granite topaz albite granite li f rich mica greisens and a quartz topaz rock similar to topazite two types of greisens are recognized in the mineralized area zinnwaldite greisen and li rich muscovite greisen formed by metasomatism of topaz albite granite and li siderophyllite granite respectively cassiterite occurs in the quartz topaz rock and in the greisens indium minerals such as roquesite cuins2 yanomamite inaso4 2h2o and dzhalindite in oh3 and in rich cassiterite sphalerite stannite group minerals and scorodite are more abundant in the quartz topaz rock and are also recognized in albitized biotite granite and in li rich muscovite greisen the host rocks and mineralized zones were subsequently overprinted by the brasiliano orogenic event primary widespread two phase aqueous and rare coeval aqueous carbonic fluid inclusions are preserved in quartz from the topaz albite granite in quartz and topaz from the quartz topaz rock and in cassiterite from the li rich muscovite greisen eutectic temperatures are 25 c to 23 c allowing modeling of the aqueous fluids in the system h2o nacl kcl rare three phase h2o nacl fluid inclusions 45 50 wt nacl equiv are restricted to the topaz albite granite salinities and homogenization temperatures of the aqueous and aqueous carbonic fluid inclusions decrease from the topaz albite granite 15 20 wt nacl equiv 400 c 450 c to the quartz topaz rock 10 15 wt nacl equiv 250 c 350 c and to the greisen 0 5 wt nacl equiv 200 c 250 c secondary fluid inclusions have the same range of salinities as the primary fluid inclusions and homogenize between 150 and 210 c the estimated equilibrium temperatures based on 18o of quartz mica pairs are 610 680 c for the topaz albite granite and 285 370 c for the li rich muscovite greisens these data are coherent with measured fluid inclusion homogenization temperatures temperatures estimated using arsenopyrite geothermometry yield crystallization temperatures of 490 530 c for the quartz topaz rock and 415 505 c for the zinnwaldite greisens the fluids in equilibrium with the topaz albite granite have calculated 18o and d values of 5 6 7 5 and 67 to 58 respectively estimated 18o and d values are mainly 4 8 7 9 and 60 to 30 respectively for the fluids in equilibrium with the quartz topaz rock and zinnwaldite greisen and 3 4 3 9 and 25 to 17 respectively for the li rich muscovite greisen fluid 34s data on arsenopyrite from the quartz topaz rock vary from 1 74 to 0 74 consistent with a magmatic origin for the sulfur the integration of fluid inclusion with oxygen isotopic data allows for estimation of the minimum crystallization pressure at ca 770 bar for the host topaz albite granite which is consistent with its evolved signature based on petrological fluid inclusion and isotope data it is proposed that the greisens and related mangabeira sn in mineralization had a similar hydrothermal genesis which involved exsolution of f rich sn in bearing magmatic fluids from the topaz albite granite early formation of the quartz topaz rock and zinnwaldite greisen progressive cooling and li rich muscovite greisen formation due to interaction with meteoric water the quartz topaz rock is considered to have formed in the magmatic hydrothermal transition the mineralizing saline and co2 bearing fluids are interpreted to be of magmatic origin based on the isotopic data and paragenesis which has been documented as characteristic of the tin mineralization genetically related to proterozoic within plate granitic magmatism in the goias tin province central brazil

trace elements and cathodoluminescence of quartz in stockwork veins of mongolian porphyry style deposits the combination of scanning electron microscope cathodoluminescence cl fluid inclusion analysis and high resolution electron probe microanalysis of al ti k and fe in vein quartz has yielded results permitting a greater understanding of the complex mineralisation of the central oyu tolgoi and zesen uul porphyry style deposits southern mongolia these data demonstrate the relationship between quartz precipitation dissolution and ore deposition as the mineralising fluid chemistry changed through time four major quartz generations are identified in the a type veins from the stockworks of both the central oyu tolgoi oti to otiv and zesen uul deposits zui to zuiv despite differences in the associated alteration and mineralisation style the observed cl textures and trace element signatures of the quartz generations are comparable between deposits the oti and zui stage formed both the primary network of a type veins and pervasive silicification of the host rock using the ti in quartz geothermometer crystallisation temperatures for oti and zui of between 598 c and 880 c are indicated the main stage of sulphide mineralisation was accompanied by the dissolution of pre existing quartz oti and zui and precipitation of a weakly luminescent generation of quartz otii and zuii with a low ti content reflected in a calculated temperature drop from approximately 700 c to 340 c in central oyu tolgoi and 445 c in zesen uul otii and zuii stage quartzes show high and variable al concentrations the next stage of quartz in both deposits otiii and zuiii forms a fine network of veins in cracks formed in pre existing quartz otiii and zuiii quartz contain measurable fluid inclusions of moderate salinity 3 17 1 wt nacl eq entrapped in the temperature range 256 c to 385 c otiii and zuiii are not related to any sulphide mineralisation the final otiv and zuiv stages are characterised by quartz calcite micro breccias that penetrate the a type veins based on the calculated entrapment temperatures the otiv zuiv stage crystallised between 212 c and 335 c and the quartz is characterised by elevated but variable al and fe contents the cl and trace element signatures of the oti to otiii and zui to zuiii stages of the two mongolian porphyries show similar features to those observed in porphyry style deposits from other regions this suggests that a common sequence of quartz crystallisation occurs during the formation of early veins in many porphyry copper systems

magmatic hydrothermal transition of mo w mineralized granite pegmatite greisen system recorded by trace elements in quartz krupka district eastern krusne hory erzgebirge abstract magmatic hydrothermal transition of highly evolved granitic melts enriched in volatile and incompatible elements can involve disequilibrium intermediate products between aluminosilicate melt and hydrothermal fluid hydrosilicate liquids with high ore forming potential we investigate evolution from li f rich granites through pegmatites greisens and quartz veins in a composite stock at knottel in the krupka district eastern krusne hory erzgebirge mountain range by monitoring trace element variations in quartz interelemental correlations reveal si4 li al3 and likely si4 h al3 to be the most important substitution mechanisms variations in ti vs li be and al define distinct evolutionary trends i magmatic high li ti or al ti trend granites aplites k feldspar pegmatite ii transitional medium li ti trend quartz megacrysts and pegmatite lenses in granite quartz protolithionite pegmatite iii hydrothermal low li ti or al ti trend stockwork of coarse grained hydrothermal quartzites and quartz veins quartz replacement in greisens the medium li ti trend represents hydrosilicate liquid an h2o and sio2 rich medium with low density and effective viscosity that was probably formed during disequilibrium crystallization in front of rapidly propagating solidification front thermal evolution of the magmatic hydrothermal system was monitored by ti in quartz thermometry calculated rutile activity of the granites is very low 0 3 0 05 but it increases up to 1 that is saturation towards pegmatites and hydrothermal veins magmatic crystallization granites and aplites is constrained to 700 580 c pegmatite and bulk greisenization stage occurred at 600 500 c followed by a late hydrothermal stage associated with the formation of distal quartz veins at 500 390 c the granite pegmatite systems at knottel and in erzgebirge in general reach extremely high al li rb and ge and low ti concentrations in quartz in comparison with igneous rocks worldwide the knottel stock belongs to p poor a type granites in the erzgebirge and is linked with them by similar evolutionary trends in quartz trace elements furthermore the knottel system exhibits be enrichment in quartz probably related to high contents of f and this appears to be typical feature of mo w mineralized systems in general the hydrothermal phase with mo w mineralization at knottel is closely related to the magmatic phase of parental granite body which seems to be an important condition for mo w mineralization formation

silicothermal fluid a novel medium for mass transport in the lithosphere new experimental data from synthetic fluid inclusion studies in the system k 2 o co 2 sio 2 h 2 o kcsh show that a potassic silica rich 90 wt sio 2 fluid can coexist immiscibly with a supercritical alkaline aqueo carbonic fluid and quartz from temperatures as low as 300 c to more than 750 c at relatively low geologic pressures 2 rich fluids if they form in the lithosphere are likely to be important in the mobilization and transport of silica and large ion lithophile elements e g k cs ba and metals of economic significance e g au ag u

latest precambrian cadomian zircon ages nd isotopic systematics and p t evolution of granitoid orthogneisses of the erzgebirge saxony and czech republic single zircons from two orthogneiss complexes the grey gneiss and red gneiss the lowermost tectonic units in the erzgebirge were dated the grey freiberg gneiss is of igneous origin and has a 207pb 206pb emplacement age of 550 7 ma a quartz monzonite from lauenstein contains idiomorphic zircons with a mean 207pb 206pb age of 555 7 ma as well as xenocrysts ranging in age between 850 and 1910 ma red gneisses from the central erzgebirge contain complex zircon populations including numerous xenocrysts up to 2464 ma in age the youngest idiomorphic zircons in all samples yielded uniform 207pb 206pb ages between 550 9 and 554 10 ma nd isotopic data support the interpretation of crustal anatexis for the origin of both units nd t values for the grey gneisses are 7 5 and 6 0 respectively mean crustal residence ages of 1 7 1 8 ga the red gneisses have a wider range in nd t values from 7 7 to 2 8 tdm ages of 1 4 1 8 ga the zircon ages document a distinct late proterozoic phase of granitoid magmatism similar in age to granitoids in the lusatian block farther north east however palaeozoic deformation as well as medium pressure metamorphism 8 kbar 600 650 c are identical in both gneiss units and distinguish these rocks from the lusatian granitoids the grey and red gneisses were overthrust by units with abundant high pressure relicts and a contrasting p t evolution zircon xenocryst and nd model ages in the range 1000 1700 ma are similar to those in granitoid rocks of lusatia and the west sudetes and document a pre cadomian basement in parts of east central europe that chronologically has similarities with the sveconorwegian domain in the baltic shield

trace element composition of quartz from the variscan altenberg teplice caldera krusne hory erzgebirge mts czech republic germany insights into the volcano plutonic complex evolution abstract in this study the internal structures and appropriate trace element distributions within quartz grains were investigated using a laser ablation icp ms technique combined with a hot cathode and scanning cathodoluminescence analysis the studied variscan magmatic suite is located in the altenberg teplice caldera eastern krusne hory erzebirge along the czech republic germany border and composed of co magmatic volcanics peraluminous basal rhyolite and associated dacite overlying three units of subaluminous teplice rhyolite and granite porphyry and plutonic granites two intrusions of a type biotite and zinnwaldite granites the trace element distribution in the granite porphyry and rhyolite quartz demonstrates a distinct zoning in the cathodoluminescence images and chemical compositions the core is poor in ti the outer rim zones are enriched in ti and the trends recorded for al are opposite to those of ti the quartz from granites is either very weakly zoned or homogeneous based on the chemical composition of quartz and its zoning we assume that the quartz crystals began to crystallize gradually in the primary deep seated magma chamber with a p t condition of 10 kbar and 750 c and in an environment with an increasing concentration of al and decreasing concentration of ti the early stage was followed by the subsequent adiabatic ascent into a shallow magma chamber estimated by the ti in quartz thermobarometry at approximately 700 c 2 kbar during which crystal rims rich in ti formed and then extruded after the caldera collapse part of the magma intruded as granite and in the environment of the residual melt rich in water and flux agents late quartz grew in the form of snowball quartz with an increased al content and decreased ti content

genetic significance of the trace element content in metamorphic and hydrothermal quartz a reconnaissance study abstract a reconnaissance study on trace elements in metamorphic and hydrothermal quartz was carried out using quartz samples from the tin district erzgebirge germany the gold mineralization at kasperske hory czech republic and the gold quartz vein deposits muruntau and myutenbai uzbekistan a new method of sample preparation has been developed to prepare pure quartz samples by combining conventional hand picking with microscopic and spectroscopic studies as well as acid wash etch procedures preparation of monomineralic samples was followed by sample dissolution and measurement by icp ms the metamorphic quartz has very low concentrations of li 0 4 ppm al 30 ppm k 35 ppm rb 50 ppb sr 0 3 ppm and y 15 ppb moreover it is characterized by light rare earth element enriched lanthanide distribution patterns lacking eu anomalies the low element concentrations in metamorphic quartz are interpreted to result from recrystallization metamorphic quartz from alteration halos enveloping tin and gold deposits has distinctly different trace element signatures these differences are related to the hydrothermal overprint of the pre existing metamorphic quartz by the mineralizing fluids hydrothermally altered metamorphic quartz from tin deposits has elevated concentrations of li 0 9 ppm al 50 ppm k 45 ppm rb 250 ppb and y 40 ppb whereas altered metamorphic quartz from gold deposits is characterized by elevated concentrations of sr 0 5 ppm the rare earth element distribution patterns of altered metamorphic quartz show variable enrichments of the heavy rare earth elements and frequently display positive eu anomalies hydrothermal vein quartz from the gold deposits usually has elevated al 50 ppm and sr 0 6 ppm contents the lanthanide distribution patterns exhibit variable enrichments of the heavy rare earth elements and commonly show positive eu anomalies the elevated sr concentrations in the quartz from gold deposits are best explained by sr release during feldspar alteration in the wall rocks this mechanism may also account for the relative enrichment of eu in the mineralizing fluids although other processes may not be unambiguously ruled out

comment on crustal structure of the british isles and its epeirogenic consequences by m w davis n j white k f priestley b j baptie and f j tilmann while davis et al provide convincing evidence for dynamic support of modern topography in nw scotland we take issue with their claims that the spatial distribution of cenozoic denudation correlates poorly with the pattern of upper crustal shortening and that the magnitude of shortening is insufficient to cause the observed denudation we disagree with davis et al s map of denudation which forms the basis of their claims and believe that their conclusions seriously downplay the widely documented contribution of crustal shortening to cenozoic denudation of many areas of the british isles