Water content of granitic melts from Cornwall and Erzgebirge: A Raman spectroscopy study of melt inclusions

Water content of granitic melts from Cornwall and ErzgebirgeA Raman spectroscopy study of melt inclusions

AXEL MUumlLLER1 RAINER THOMAS2 MICHAEL WIEDENBECK2 REIMAR SELTMANN1 and KAREL BREITER3

1Natural History Museum Department of Mineralogy Cromwell Road London SW7 5BD UKCorresponding author present address Norges geologiske undersoslashkelse 7491 Trondheim Norway

e-mail AxelMullernguno2GeoForschungsZentrum Potsdam Telegrafenberg 14473 Potsdam Germany

3Czech Geological Survey Prague Geologicka 6 15200 Prague 5 Czech Republic

Abstract Melt inclusions (MIs) occurring in quartz of late-Variscan Sn-specialized granites from the Landrsquos End pluton in SWEngland and from the eastern Erzgebirge volcano-plutonic complex in Germany were analyzed by Raman spectroscopy secondaryion mass spectrometry and electron microprobe Crystallized MIs were homogenized using cold-sealed autoclaves operating at850degC and 2 kbar for 24 hours The H2O concentration of homogenized MIs from the Landrsquos End granites determined by confocalRaman spectroscopy range between 15 and 54 wt Several MIs from the Landrsquos End granites contain a hypersaline fluid with 182to 386 wt H2O Such mixed fluid and silicate-MIs are typical for magmas that were oversaturated in volatiles The ratio of silicateglasssaline phase decreases with increasing degree of differentiation of the granite host The H2O content of MIs from theNiederbobritzsch granite Schoumlnfeld rhyodacite Teplice rhyolite Altenberg-Frauenstein microgranite and Schellerhau granite in theeastern Erzgebirge varies between 07 and 119 wt The MIs from the volcanic rocks have more variable concentrations than theMIs from the granites The high chemical discrepancies between MIs and whole rock suggest that the quartz phenocrysts in theSchoumlnfeld rhyodacite were injected into a stratified magma chamber during the course of multiple recharge events at the chamberrsquosbase MIs from granites from the eastern Erzgebirge do not contain hypersaline fluids however they have F concentrations of up to112 wt The Li Be and B contents of representative homogenized MIs were determined by SIMS The light lithophile elementratios of MIs are constant for each magmatic province despite different fractionation degrees of the host rocks MIs from rocks of theeastern Erzgebirge volcano-plutonic complex are relatively enriched in Li and Be whereas MIs in granites of the Landrsquos End plutonhave higher B contents The distinctive ratio of light lithophile elements of the silicate melt is also reflected in the light lithophileelement ratio of the magmatic host quartz

Key-words melt inclusion Raman spectroscopy SIMS granite Cornwall Erzgebirge

1 Introduction

Melt inclusions (MIs) are micro samples of magmatic meltentrapped in crystals which can provide unique information ofthe pre-eruptive dissolved volatile content (H2O B F Cl CS) of volcanic rocks and the volatile content of granitic mag-ma from distinct stages of their evolution Quartz crystals infelsic igneous rocks are relative stable and incompressiblehosts of MIs shielding MIs against degassing and preventingother mass flows into or out of the MI system (see Lowen-stern JB 2003) Dissolved volatiles greatly influence therheological properties of the magma thus determining the ex-plosive behaviour of volcanic eruptions The enrichment of BF Cl and H2O in the apical part of a magma chamber has anacceleration effect on the fractionation of the melt and on theenrichment of metals (eg Webster et al 1997 Audetat et al2000 Lehmann et al 2000 Thomas et al 2003 Webster etal 2004 Thomas et al 2005) which may result in rare and

precious metal mineralization Thus the chemical character-ization of MIs can be used to address fundamental questionsregarding the origin and evolution of the magma and the pro-cesses of magma recharge crystallization volatile and metalenrichment degassing and ultimately eruption which takeplace in shallow felsic magma chambers (eg De Vivo ampBodnar 2003 and references therein)

The present study documents the H2O contents and to alesser extent the concentrations of major minor elementsand light lithophile elements (LLE Li Be and B) in MIs oflate-Variscan granites and rhyolites from the Landrsquos Endpluton in Cornwall and the eastern Erzgebirge volcano-plu-tonic complex These granite complexes are well document-ed in terms of their origin and evolution (eg Charoy 1979Van Marcke de Lummen 1986 Powell et al 1999 Muumllleret al 2006 for the Landrsquos End pluton and Tischendorf1989 Breiter 1997 Foumlrster et al 1999 Breiter et al 2001Muumlller et al 2000 Stemprok et al 2003 Muumlller et al

Eur J Mineral2006 18 429ndash440

DOI 1011270935-122120060018-04290935-1221060018-0429 $ 540

ˇ 2006 E Schweizerbartrsquosche Verlagsbuchhandlung D-70176 Stuttgart

2005 for the eastern Erzgebirge) Given this volume of pre-vious work we have a solid foundation from which to assessthe significance of our data and to evaluate the applicabilityof MIs to petrogenetic interpretations This current studysupplements Muumlller et al (2006) and Muumlller et al (2005)which document the magmatic evolution of the Landrsquos Endpluton and the eastern Erzgebirge volcano-plutonic com-plex respectively

The application of the Raman spectroscopy has advantagesover other methods of H2O determination in silicate glassessuch as Karl Fisher titration and Fourier transform infrared(FTIR) spectroscopy due to its non-destructive in situ natureand its ability to acquire data rapidly (Thomas 2000 and2002 Chabiron et al 2004 Thomas et al 2006) The deter-mination of H2O concentration in MIs by Raman spectrosco-py is the focus of this study which is augmented by secondaryion mass spectrometry (SIMS) and electron microprobe anal-yses (EPMA) of element concentrations in MIs H2O concen-trations in MIs determined by both Raman spectroscopy andEPMA by using the ldquoH2O by differencerdquo method (Devine etal 1995) are compared This study also aims to determine theextent to which the H2O Li Be B Cl concentrations of MIsdiffer between the Landrsquos End (Cornwall) and eastern Erzge-birge rare metal districts The small size of our dataset is dueto both the rareness of well-preserved MIs in granites as wellas the difficult preparation procedures (including homogeni-zation in autoclaves and MI exposure by hand grinding) re-quired before running the actual analyses

2 Geologic background

The Landrsquos End pluton forms part of the late-Variscan Cornu-bian batholith and it is a composite pluton hosting the Sn-Cumineralizations of the St Just mining district The pluton hasan age of 2745plusmn14 Ma (U-Pb monazite age Chen et al1993) and consists of early megacrystic fine-grained biotite(Mg-siderophyllite) granites and younger Li-siderophyllitegranites tourmaline granites a massive quartz-tourmalinephase (MQT) and albite microgranites (Muumlller et al 2006) Inthis study we investigate MIs found in the megacrystic fine-grained biotite granite in the Li-siderophyllite granite and inthe MQT These granites are peraluminous (ACNK = 11ndash14) high-K calc-alkaline rocks with low phosphorus con-tents (lt04 wt) They are genetically related via continuousfractional crystallization from a common magmatic reservoir(Muumlller et al 2006) The younger intrusive units of theLandrsquos End pluton are enriched in B due to melting of B-richpelitic protoliths intense fractionation and filter pressing(Jackson et al 1982 Charoy 1979 Van Marcke de Lummen1986 Muumlller et al 2006) Sample locations are shown inFig 1 and Fig 2 in Muumlller et al (2006)

The second study area reported on here is the Upper Car-boniferous eastern Erzgebirge volcano-plutonic complex ineastern Germany The Altenberg-Teplice caldera forms aneruptive centre with several tin granites which were intrud-ed after caldera collapse These late granites host the histori-cally important Zinnwald Krupka and Altenberg Sn-W de-posits From this complex we studied MIs from the Nieder-bobritzsch granite massif the Schoumlnfeld rhyodacites the

Teplice rhyolites the Altenberg-Frauenstein microgranitesand the tin-specialized Schellerhau granites The postkine-matic Niederbobritzsch granites belong to a group of low-Fbiotite monzogranites and form a multiphase intrusion witha transitional I- to S-type character (Foumlrster et al 1999)The Schoumlnfeld rhyodacites represent a relatively primitivecalc-alkaline magma whose chemical evolution was proba-bly uncoupled from the overlaying Teplice rhyolites (Brei-ter et al 2001) The Teplice rhyolites are high-K calc-alka-line in character (Breiter 1995 1997 Breiter et al 2001)The eruption of the Teplice volcanic rocks led to the col-lapse of the Altenberg-Teplice caldera with N-S elongatedring fractures that were subsequently filled by multiple in-trusions of the porphyritic Altenberg-Frauenstein micro-granite (Muumlller amp Seltmann 2002) The topaz-bearing raremetal granites (post-caldera stage) are represented by theSchellerhau granite complex which is situated in the centreof the Altenberg-Teplice caldera and which consists of bio-tite syeno- to monzogranites and seriate albite granites(Muumlller et al 2000) These rocks are P-poor and Li-F-en-rich and show some A-type traits (Foumlrster et al 1995 Brei-ter et al 1999) For location of sample from the Erzgebirgewe refer to Fig 1 in Muumlller et al (2005)

3 Description of melt inclusions

Crystallized MIs from the Landrsquos End pluton are rare andthey are hard to identify due to the dense network of fluid in-clusion trails which frequently penetrate the host quartzThe spherical to hexagonal MIs of the megacrystic biotitegranite and Li-siderophyllite granite are usually 5 to 35 micromin diameter commonly multiphase with a small volatilebubble and occasionally visible crystals (eg biotiteFig 1a) Crystallized MIs of the MQT have irregular shapesand are commonly 5 to 20 microm in size frequently contain avapour phase and occasional halite crystals (Fig 1c)

MIs in the Niederbobritzsch granite are rare The crystal-lized and spherical MIs are 8 to 15 microm in diameter and mostof them contain a vapour bubble (Fig 1e) MIs of theSchoumlnfeld rhyodacite can be either crystallized or glassy(Fig 1g) Up to 10 inclusions have been noted in a fragmentof a single phenocryst The size of the hexagonal and spheri-cal MIs is between 8 and 35 microm The hexagonal MIs of theTeplice rhyolite (TR2b) contain glass a vapour bubble andone or more crystals The size ranges from 8 to 110 microm butmost of the MIs have a diameter of 10 to 45 microm (Fig 1i)Approximately two thirds of the MIs are glassy and onethird are crystallized MIs of the Schellerhau granite rangefrom 5 microm to 120 microm in diameter are commonly sphericalMIs containing a vapour phase Large MIs sometimes con-taining visible apatite and mica crystals

4 Methods

41 Melt inclusion selection and sample preparation

MIs were examined in quartz crystals of doubly polishedthick (~500 microm) wafers Crystals containing MIs were mil-

430 A Muumlller R Thomas M Wiedenbeck R Seltmann K Breiter

halite

a CW3221ordmC b CW321030ordmC c CW0221ordmC d CW02930ordmC

e NB0121ordmC f NB01980ordmC g TR1721ordmC h TR171130ordmC

i TR3121ordmC j TR31680ordmC k TR31930ordmC l TR311130ordmC

Li-siderophyllite granite MQT

Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n

Niederbobritzsch granite NB2 Schonfeld rhyodacite

Teplice rhyolite TR2b

Fig 1 Transmitted-light photograph showing textural characteristics and homogenization behaviour of MIs from the Landrsquos End pluton andthe eastern Erzgebirge volcano-plutonic complex during heating at 1 atm Scale bars are 20 microm The temperature given for each image indi-cates the temperature step after which the photograph was taken These temperatures do not necessarily correspond to the homogenizationtemperature of MI a b ndash Li-siderophyllite granite Landrsquos End The homogenized MI is significantly larger than the originally crystallizedinclusion c d ndash MQT Landrsquos End Crystallized MI with halite crystal and shrinkage bubble The MI could not be homogenized and was notmeasured due to leakage e f ndash Niederbobritzsch granite NB2 eastern Erzgebirge The crystallized MI contains a shrinkage bubbleg h ndash Schoumlnfeld rhyodacite eastern Erzgebirge The glass of the homogenized MI shows a marginal ldquoshadowrdquo (arrow) indicating that the MIis not completely homogenized The margin has higher SiO2 resulting from incomplete homogenization indashl ndash Teplice rhyolite TR2b easternErzgebirge The MI size increases slightly with increasing temperature

led out from the wafer using grinding diamond (06 mm indiameter) of a modified H2O-cooled CNC milling machineThe thin section was aligned with an optical centring micro-scope The resulting quartz disks were 42 mm in diameter

42 Homogenization of melt inclusions for Ramanspectroscopy and EPMA

The homogenization of the crystallized MIs which were se-lected for Raman spectroscopy and SIMS measurementswas performed at the Hydrothermal Laboratory of the Geo-ForschungsZentrum Potsdam (Germany) The quartz diskswere enclosed in 6 mm diameter ~20 mm long gold cap-

sules The sample bearing capsules were heated in cold-sealed autoclaves operating at 850degC and 2 kbar for 24hours The isobar heating of 100degC10 min and subsequenttemperature stabilization was controlled by a thermocouplelocated next to the capsule The maximum temperature vari-ation within the capsule was 3degC The samples were isobar-ically cooled (quenched) to room temperature CO2 wasused as pressure medium to exclude influx or escape of H2Oinfrom the MIs during treatment Examples of MIs treatedin the cold-sealed autoclave are shown in Fig 2 Most of theMIs were homogenized to a clear homogeneous glassyphase with one or several vapour bubbles Inclusion sizesand shapes appear unaffected A change in linear dimensionof more than 5 would have been obvious Several MIs in

Water content of melt inclusions 431

saline phase

with crystalsaline phase

with crystal

silicate glass

silicate glass

vapour

phase

vapour

phase

a CW32-8 b CW25-3e c CW02-8

Li-siderophyllite biotite granite MQTgranite

Schonfeld Teplice Schellerhaurhyodacite rhyolite TR2b granite SG2

d TR17-10 e TR31-3b f SHX-8

Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n

Fig 2 Homogenized MIs treated at850degC and 2 kbar for 24 h in autoclavesScale bars are 20 microm a ndash Li-siderophylli-te granite Landrsquos End b ndash Megacrysticfine-grained biotite granite Landrsquos Endc ndash MQT Landrsquos End d ndash Schoumlnfeldrhyodacite e ndash Teplice rhyolite f ndash De-vitrified fluorine-rich MI of the Scheller-hau granite exposed at the surface of thequartz disk

the MQT and biotite granite from the Landrsquos End plutoncontain additionally a saline phase with salt crystals (haliteor sylvite Fig 2b c) Newly formed opaque crystals wereobserved in a number of MIs from the Altenberg-Frauen-stein microgranite A few vapour bubbles in treated MIsfrom the Schoumlnfeld rhyodacite are enveloped by low-vol-ume meniscus presumably of CO2 MIs that were intersect-ed by cracks as a result of heating procedure may have lostvolatiles and were not analyzed

43 Step heating of melt inclusions

To assess the homogenization behaviour of crystallizedMIs some of quartz disks were chosen for homogenizationexperiments at atmospheric pressure (Fig 1) The experi-ments were run in an electric muffle furnace (Lenton Ther-mal Designs) MIs were step heated in 50degC increments to630degC and were then held at temperature for 24 hours Aftereach heating step the MIs were examined to determine thedegree of homogeneity until complete homogenization wasachieved Inclusion sizes and shapes were occasionally af-fected and the shape of the inclusions became more angularduring the repeated heating (Fig 1a b) Fig 1h shows aglassy ldquotwo-phaserdquo MI which reflects an incomplete ho-mogenisation None of the MIs homogenized by step heat-ing at atmospheric pressure were not used for analytical pur-poses

44 Raman spectroscopy

The H2O contents of MIs were determined with a Dilor XYLaser Raman Triple 800 mm spectrometer equipped with anOlympus optical microscope using a long distance 80x ob-jective The spectra were acquired with a Peltier cooledCCD detector The 488 nm line of a Coherent Ar+ LaserModel Innova 70-3 operating at between 50 and 1200 mWdepending on the H2O content were used for sample excita-tion The linear relationship between the H2O content of thesilicate glass and the integral intensity of the asymmetric O-H stretching Raman band between 3100 and 3750 cm-1 withthe maximum at 3550 cm-1 was utilized (Thomas 2002Thomas et al 2006) The acquisition time was 200 s 3 ac-cumulations were used for each determination and a base-line correction was performed using a first-degree polyno-mal Because the Raman signal decreases as a function ofMI depth a linear correction function (depth vs log intensi-ty) was derived which gives the percentage weakening ofthe Raman intensity with depth (5 to 120 microm) The calcula-tion of H2O in MIs is based on calibration curves derivedfrom synthetic glasses with various H2O contents between 0and 25 wt (Thomas 2002) The depth-depending func-tion of the Raman signal was directly applied to each stan-dard measurement Using this approach all measurement ar-tefacts which might disturb the H2O Raman signal wereeliminated (Thomas et al 2006) Final H2O concentrationsgiven in Table 1 are the average of 5 measurements of one


MI Only MIs which were not exposed at the sample surfacewere measured Fluorescence was not observed in our sam-ples

45 Electron probe microanalysis

For electron microprobe and ion microprobe measurementsthe quartz disks containing homogenized MIs were grounddown in 5-microm steps after Raman spectroscopy investiga-tions until the selected MI were exposed at the surface(Fig 2f)

Homogenized silicate-MIs were analyzed for Si Al TiFe Mg Mn Ca K Na Rb Cr Sn P Cl and F by electronprobe microanalysis (Cameca SX 50) An accelerating volt-age of 15 kV a low beam current of 10 nA a beam diameterof 5 microm and a counting time of 10 or 20 s were chosen toavoid volatilization of the alkalis from the MI Na was mea-sured first Between one and six spots were analyzed on theglass in each inclusion To avoid overlap with the hostquartz during analyses measurements were made near thecentre of the MIs

We used the electron microprobe to verify if the H2O con-centrations determined by Raman spectroscopy are in therange of volatile values which can be calculated from elec-tron microprobe data H2O in MIs can be indirectly deter-mined by EPMA applying the ldquoH2O by differencerdquo methodwhereby the oxide totals are subtracted from 100 wt (egDevine et al 1995 Hanson et al 1996 Morgan amp London1996) assuming that the difference between the sum of allelement oxides and 100 gives the total volatile contentThe accuracy of the volatile content depends mainly on theaccuracy of the major elements (O) Si Al Na and K Themethod is feasible for MIs containing gt1 wt H2O (Devineet al 1995)

46 Secondary ion mass spectrometry (SIMS)

Secondary ion mass spectrometry (SIMS) is a sensitive andpowerful micro-beam technique which allows high spatialresolution measurements of LLE in minerals and glasses(Zanetti et al 2000 Herd et al 2002 Vannucci et al2003) Surface-exposed MIs which had been previouslyanalysed using Raman spectroscopy andor EPMA were se-lected for SIMS We used a Cameca ims 6f SIMS at GFZPotsdam to measure the abundances of the light elements LiBe and B Prior to SIMS measurements the samples were ul-trasonically cleaned for five minutes in ethanol and coatedwith a ca 35-nm-thick conductive film of high-purity Au A2 nA nominally 125 kV 16O- primary beam was focused toa ~10 microm diameter spot Sputtered positive ions were accel-erated through a 10 kV secondary extraction field In orderto eliminate isobaric interference we operated the massspectrometer at a mass resolution M 2 M raquo 1900 in conjunc-tion with a 60 microm field-of-view (FOV) and a 50 V energybandpass FOV is the area on the samplersquos surface which isimaged by the mass spectrometer The diameter of the FOVis determined by the size of the field aperture and the magni-fication of the transfer optics Each analysis consisted of a 3

min unrastered preburn and 20 cycles of the peak-steppingsequence 095 background 7Li (10 s) 9Be (10 s) 11B (10 s)and 30Si (2 s) For those inclusions where we appeared tohave accurately targeted the primary beam we calculatedthe absolute abundances of the LLE For Li Be and B weused NIST 610 glass as the reference sample using the con-centration data from Pearce et al (1997) The diameters anddepths of the SIMS craters were measured using the Detak 3stylus profilometer The profilometer has the ability to de-termine the crater depth with a reproducibility on the orderof 1 nm

5 Results of melt inclusion analysis


The results from the determination of the H2O content ofMIs by Raman spectroscopy are given in Table 1 The H2Ocontent of the glass in the rehomogenized MIs from theLandrsquos End granites ranges between 15 and 54 wt Theaverage values of 41 wt H2O and 38 wt were deter-mined for the older biotite granite (CW25) and the Li-side-rophyllite granite (CW32) respectively Silicate glass fromthe MQT contained lower H2O contents of about 32 wtwhich seems to contradict the fact that the MQT is chemi-cally more evolved than either the biotite granite or the Li-siderophyllite granite Some MIs of the biotite granite con-tain a saline phase and a vapour phase in addition to theglassy phase The saline phase in MIs of the biotite graniteforms a low-volume meniscus around the gas bubble InMIs of the MQT the saline phase is the main phase The ratioof silicate glasssaline phase decreases with the differentia-tion degree of the granite host The H2O content of the salinephase in the MIs of the biotite granite consists of 263 wtH2O The majority of the inclusions of the younger MQTcontain a saline phase with 182 to 386 wt H2O

H2O concentrations in MIs from the rocks of the easternErzgebirge volcano-plutonic complex are much more vari-able between the magmatic facies than the H2O contents ofMIs from the Landrsquos End pluton Glass from MIs of the old-er Niederbobritzsch granite (NBO-01) have relatively con-stant H2O concentrations of around 40 wt These con-centrations correspond to values determined by Thomas(1992) using homogenization temperature of the fluid phasein MIs according to the method of Naumov (1979) The H2Oconcentration of MI glass from the Schoumlnfeld rhyodacite(TR17) ranges from 24 to 97 wt MIs of the slightlyyounger and more evolved Teplice rhyolite (phase TR2b)exhibit the lowest H2O concentrations of 07 to 20 wtAn exceptionally high H2O of 119 wt was measured ona large MI (TR31-2 102 microm) The average H2O content ofMIs in the subvolcanic Altenberg-Frauenstein micrograniteis 40 wt Rehomogenized glass from MIs from thechemically highly evolved Schellerhau granites has H2Oranging between 41 and 70 wt MI SHX-8 with 70wt H2O devitrified after the treatment in the autoclaveand it may represent a different MI population from theglassy and clear MI SHX-9 and SHX-10 The extrusiveSchoumlnfeld rhyodacites and Teplice rhyolites have MIs with


variable H2O contents whereas the subvolcanic and graniticrocks contain MIs with more consistent H2O concentra-tions

52 Electron probe microanalyses

The EPMA determined compositions of representative MIsare given in Tables 2a and 2b The total volatile contents ofMIs as determined by subtraction from 100 is for the Cor-

nubian granites and Schellerhau granite 16 to 25 wthigher than the H2O concentration determined by Ramanspectroscopy The large MI TR31-2 of the Teplice rhyoliteyields ldquoH2O by differencerdquo of 49plusmn02 wt but the concen-tration determined by Raman spectroscopy amounts 119wt In the case of the Schoumlnfeld rhyodacite the H2O con-centrations of both methods are in agreement

The MIs are geochemically similar to the correspondingwhole rock sample but the former often contain more F andCl and less FeO MgO TiO2 Na2O and K2O The SiO2 con-

Table 1 Raman spectroscopy data from MIs of granitoid rocks of Cornwall and eastern Erzgebirge

Rock type amp phase meltinclusion

Characteristics Mesured phase Size (microm) Depth (microm) Meanplusmn1 c(wt H2O)

Landrsquos End pluton

megacrystic fine-grainedbiotite granite

CW25-3b glass+vapor glass 11 20 42 bdquo 02CW25-3d glass+vapor glass 8 24 28 bdquo 02CW25-3e glass+saline phase+vapor glass 21 14 54 bdquo 03CW25-3e glass+saline phase+vapor saline phase 21 14 263 bdquo 12

Li-siderophyllite granite CW32-3 glass+vapor glass 44 50 15 bdquo 01CW32-7 glass glass 19 20 33 bdquo 02CW32-8 glass+vapor glass 34 45 44 bdquo 02CW32-9 glass glass 18 14 38 bdquo 02

MQT CW02-1 saline phase+vapor saline phase 16 31 182 bdquo 09CW02-5 saline phase+vapor saline phase 12 44 250 bdquo 12CW02-7 saline phase+glass glass 18 12 32 bdquo 02CW02-7 saline phase+glass saline phase 18 12 386 bdquo 18CW02-8 saline phase+vapor saline phase 11 10 262 bdquo 12

Eastern Erzgebirge volcano-plutonic complex

Niederbobritzsch granite NB2 NBO1-1 glass+vapor glass 10 65 50 bdquo 02NBO1-6 glass+vapor glass 15 35 34 bdquo 02NBO1-7 glass+vapor glass 11 58 35 bdquo 02

Schoumlnfeld Rhyodacite TR17-4 glass+vapor glass 28 120 97 bdquo 05TR17-5 glass+vapor glass 29 53 42 bdquo 02TR17-7 glass+meniscus +vapor glass 43 68 62 bdquo 03TR17-7 glass+meniscus+ vapor meniskus 43 68 24 bdquo 02TR17-10 glass+vapor glass 22 82 67 bdquo 03TR17-11 glass glass 21 99 75 bdquo 04TR17-12 glass+vapor glass 32 23 54 bdquo 03TR17-13 glass+meniscus+ vapor glass 30 20 52 bdquo 03TR17-13 glass+meniscus+ vapor meniskus 30 20 59 bdquo 03TR17-14 glass+vapor glass 22 33 33 bdquo 02

Teplice rhyolite TR2b TR31-1 glass+vapor glass 18 97 07 bdquo 01TR31-2 glass+vapor glass 102 109 119 bdquo 06TR31-3b glass+vapor glass 27 12 20 bdquo 01TR31-3a glass+vapor glass 7 7 09 bdquo 01TR31-4a glass+vapor glass 11 88 13 bdquo 01

Altenberg-Frauensteinmicrogranite GP1

TR18-1 glass+solids glass 28 76 55 bdquo 03TR18-3a glass+solids glass 17 58 30 bdquo 02TR18-3b glass+solids glass 11 38 48 bdquo 03TR18-3c1 glass+solids glass 16 19 33 bdquo 02TR18-10 glass glass 13 27 35 bdquo 02

Schellerhau granite SG2 SHX-8 glass (devitrified) glass 24 67 70 bdquo 04SHX-9 glass+vapor glass 13 11 40 bdquo 02SHX-10 glass+solid+vapor glass 30 68 41 bdquo 02

Notes The ldquoMeanrdquo results from five H2O measurements of the same MI ldquoSizerdquo is the largest and smallest MI diameter divided by 2 ldquoDepthrdquocorresponds to the focal depth of the laser


Table 2a Major and minor element data (electron probe microanalyses) of homogenized MIs and whole rock analyses (wt) for samplesfrom the Landrsquos End pluton

Megacrystic fine-grainedbiotite granite (CW25)

Li-siderophyllite granite (CW32) MQT (CW02)

MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4

SiO2 7638 7267 7788plusmn016 7546 7855plusmn015 7663TiO2 011 034 009plusmn001 0153 010plusmn004 008Al2O3 1246 1400 1239plusmn004 1345 1141plusmn012 1343FeO 080 209 094plusmn008 149 069plusmn016 380MgO 014 048 004plusmn001 018 008plusmn001 017MnO lt009 003 lt009 002 lt009 005CaO 081 081 043plusmn004 042 033plusmn002 043K2O 134 524 052plusmn004 496 123plusmn014 014Na2O 127 280 141plusmn008 262 17plusmn006 070Rb2O lt014 004 lt014 006 lt014 0P2O5 lt012 024 lt012 023 lt012 025Cl 033 004 027plusmn002 002 027plusmn001 002F lt010 020 lt010 025 lt010 037B 0005 gt01 gt01Li 0006 0008 0006Be 00002 00002 00005O=ClF 007 009 006 011 006 016

Total 9363 9890 9395 9931 943 959

H2O 64plusmn01 60plusmn01 57plusmn01H2O 42plusmn02 44plusmn02 32plusmn02

Notes The MI number in brackets corresponds to the MI number in Table 1 Whole rock data are from Muumlller et al (2006) n ndash number ofanalyses WR ndash whole rock MI ndash melt inclusion homogen ndash homogenized H2O ndash H2O determined by ldquoH2O by differencerdquo method H2Ondash H2O determined by Raman spectroscopy

Table 2b Major and minor element data (electron probe microanalyses) of homogenized and unheated MIs and whole rock analyses (wt)for samples from the eastern Erzgebirge volcano-plutonic complex

Schoumlnfeld rhyodacite (TR17) Teplice rhyolite TR2b(TR31)

Schellerhau granite SG2(SHX)

MI (5) homogen MI unheated WR MI (2) homogen WR MI (8) homogen WR

n 2 3 3 2

SiO2 7714plusmn006 7683plusmn056 6665 7277plusmn031 7652 6548plusmn014 7293TiO2 006plusmn0 006plusmn002 066 006plusmn0 012 006plusmn001 009Al2O3 1310plusmn001 1288plusmn005 1577 1471plusmn019 1217 1593plusmn006 1384FeO 057 008plusmn001 251 082plusmn014 093 062plusmn009 152MgO 005plusmn002 lt004 141 lt004 009 lt004 017MnO lt009 lt009 004 lt009 002 056plusmn005 005CaO 064plusmn002 073plusmn005 131 07plusmn002 054 005plusmn001 071K2O 305plusmn011 273plusmn017 413 294plusmn011 567 071plusmn005 509Na2O 137plusmn016 172plusmn031 341 204plusmn023 233 114plusmn008 347Rb2O lt014 lt014 002 lt014 003 016plusmn001 01P2O5 lt012 lt012 024 lt012 002 013 004Cl lt007 lt007 nd 014plusmn001 nd 054 ndF lt010 lt010 008 152plusmn008 007 1021plusmn099 082O=ClF 001 001 003 067 003 442 034Total 9595 9501 9620 9508 9848 9117 9848

H2O 41plusmn01 50plusmn02 49plusmn02 88plusmn028H2O 42plusmn02 119plusmn06 70plusmn04

Notes The MI number in brackets corresponds to the MI number in Table 1 Whole rock data are from Muumlller et al (2005) n ndash number ofanalyses within one MI WR ndash whole rock MI ndash melt inclusion homogen ndash homogenized nd ndash not determined H2O ndash H2O determinedby ldquo H2O by differencerdquo method H2O ndash H2O determined by Raman spectroscopy


00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz

Li-siderophyllite granite

(CW32-1)

MQT (CW02-1)

quartz around CW32-1


Landrsquos Endpluton

Eastern Erzgebirge

EasternErzgebirge

Teplice rhyolite (TR31-1)

Teplice rhyolite (TR31-2-1)


Schellerhau granite (SHX-3)

quartz around SHX-3

tents of MIs from Landrsquos End granites are consistently 3 to5 wt higher than the whole rock value The alkali concen-trations of MIs from the biotite granite and Li-siderophyllitegranite are lower than the whole rock content (Na 50 Al90 and K 10-25 of the whole rock content) In contrastMIs of the MQT have much higher Na and K than the wholerock The silicate glass of MIs from the three Landrsquos Endgranites exhibit elevated Cl concentrations of about 03wt whereas F is below the detection limit of 01 wt

SiO2 in MIs of the Schoumlnfeld rhyodacite is about 10 wthigher than in the whole rock indicating a more silicic envi-ronment during the MI entrapment than the whole rockcomposition reflects The MIs of the Teplice rhyolite andSchellerhau granite contain 15 and 102 wt F respective-

Fig 3 Diagram of the BBe vs LiB ratio in MIs and host quartz de-termined by SIMS (Table 3)

Table 3 SIMS analyses of light lithophile elements and water of glass of homogenized MIs and quartz hosting the MIs Known whole rockvalues of Li Be and B are in brackets

MI Li (ppm) Be (ppm) B (ppm)

melt inclusion analyses

Li-siderophyllite granite CW32-1 21 (80) 2 (2) 142 (gt1000)MQT CW02-1 3 (60) 3 (5) 223 (gt1000)Teplice rhyolite TR2b TR31-1 15 (lt20) 8 22

TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52

Schellerhau granite SG2 SHX-3 104 (75) 60 184

quartz analyses

Li-siderophyllite granite CW32-1-qz 46 01 84Schellerhau granite SG2 SHX-3-qz 58 09 34

Notes Two analyses were obtained from the MI TR31-2 MI ndash melt inclusion number ndash Minimumconcentrations of MI where the beam sputtered not only MI glass but also portions of the quartz host

ly which are much higher than F in whole rocks The rela-tively low silica and alkali concentrations in MI SHX-8 ofthe Schellerhau granites are mainly caused by the high Fcontent of 102 wt

53 Secondary ion mass spectrometry

The Li Be and B concentration of representative MIs weredetermined by SIMS on six homogenized MIs The diame-ters of homogenized and exposed MIs were between 15 and45 microm in diameter at the sample surface Analytical difficul-ties were encountered both in accurately targeting the entireprimary beam on the selected inclusion and when analyseswere necessarily conducted too close to gas bubbles (emp-ty) because of the limited inclusion size The ion beam sput-tered holes between 8 and 10 microm in diameter and up to 3 to4 microm depth Thus the beam sputtered not only glass of MIsbut also the host quartz which caused the proportional low-ering of the LLE concentrations For these reasons many ofthe analyses did not produce usable quantitative data Aftercompleting analyses the sputter craters were studied andmeasured using a petrographic microscope and the Detak 3stylus profilometer Those analyses which appear to havegiven reliable quantitative results are included in Table 3

The analyses of three MIs of the Teplice rhyolite (TR31)reveal Li Be B ratios which vary by ca 10 (Fig 3)Based on the constant element ratios of three MIs from thesame sample and on the observed stability of the secondaryion signals we conclude that the relative abundances of thefour light elements are reliably determined for all five inclu-sions studied by SIMS even if the absolute abundances areuncertain For those analyses which were not accurately tar-geted in the MI glass the given light element concentrations(Table 3) are taken to be minimum concentrations Theanalysis TR31-2-2 gives absolute LLE concentrations of theMI glass

The Li Be B ratios from the MIs plot in two fieldsclearly distinguishing between the two magmatic provinces(Fig 3) The LLE signature of MIs is distinctive for eachmagmatic province despite different fractionation degrees


of the host rocks Different H2O concentrations in MIs donot affect the LLE ratio The variability of absolute concen-trations of LLE in MIs eg of the Teplice rhyolites (TR31-2-2) and of the Schellerhau granite (SHX-3) appears to haveno influence on the LLE ratios MIs from granitic rocks ofthe eastern Erzgebirge are relatively enriched in Li and Be incomparison to MIs from granites of the Landrsquos End plutonThe most abundant LLE in MIs from the Landrsquos End gran-ites is B which is also reflected by the whole rock chemis-try LLE ratio of the MIs from the MQT is shifted to higherB ratios in comparison to the MIs of the biotite granite TheB content in the MIs from the MQT is lower than B contentof the whole rock

To establish the extent to which the LLE contents of MIsare affected by the LLE content of the host quartz we ana-lyzed quartz (Table 3) The concentrations of Be and B areat least ten times lower than their concentration in the MIscomparing the minimum concentrations in MIs and the ab-solute concentrations in quartz from the samples CW32-1and SHX-3 Li which is a typical trace element in quartz(eg Perny et al 1992) is relatively enriched in comparisonto Be and B and thus the Li Be B ratio in the quartz is shift-ed significantly towards Li (Fig 3) The LLE signature ofMIs which seems to be distinctive for the magmatic prov-ince is also reflected in the LLE ratio of the magmatic hostquartz

6 Discussion

61 Landrsquos End pluton

The narrow range of moderate H2O concentrations deter-mined for the silicate glass in the MIs from the Landsrsquos Endgranites are consistent with the high degrees of differentia-tion of the three investigated granites (Muumlller et al 2006)The good level of reproducibility within this data set is alsoan indication for the robustness of the Raman spectroscopymethod The magma system of the Landrsquos End pluton wasnot affected by mixing with mafic magmas at least duringits evolved stage (Muumlller et al 2006) which could inducelarge variations in the H2O content of the melt

The saline phase and silicate glass did not homogenize at850degC and 2 kbar for 24 h indicating immiscibility betweenthe silicate melt and hypersaline fluids Such mixed fluidand silicate-MIs are common for magmas which were satu-rated in volatiles (eg Frezzotti 1992 2001) The explana-tion for the observed high occurrence of a saline phase inMIs could be that immiscible melt droplets were preferen-tially entrapped because high saline phases form a verysmall portion of the magma The abundance of high salinephase in MIs of the MQT suggests an enrichment of immis-cible saline phase in the latest stage of magma evolution

One possible explanation for the systematically higherSiO2 contents of MIs than the whole rock value of theLandrsquos End granites is that the concentration shift in favourof silica is caused by melting of disproportionate amounts ofquartz from the walls of the MIs thereby generating glasscompositions that are artificially high in silica and therebylower in all other constituents However a comparison of

the element concentrations in a homogenized and an unheat-ed glassy MI (Table 2b) determined by EPMA reveals thatthere is no difference in silica and alkali content between un-heated and heated (homogenized) MIs Thus it seems un-likely that the observed concentration differences are gener-ated during the homogenization procedure

The high Na and K contents in MIs relative to the corre-sponding whole rock of the MQT imply that K and Na werehighly mobile during the evolution of the MQT reflectingthe transitional magmatic-hydrothermal origin of the rockMQT genesis was dominated by a silica-rich melt which toa lesser extend involved an aqueous dominated fluid (Muumll-ler et al 2006) whereby phase separation late-magmaticvolatile enrichment and late- to post-magmatic fluid circula-tion within the MQT may have remobilized the alkali ele-ments

62 Erzgebirge

The large variability in H2O contents of MIs from the east-ern Erzgebirge and in particular for those from the effusiverocks may reflect multiple magma sources andor mixing offelsic and mafic magmas Furthermore analytical uncer-tainties must take into account which is especially the casefor MIs with high H2O concentrations MIs with H2O con-centration gt9 wt may easily lose H2O during thermal andphysical treatments (Holtz pers comm 2003) The expo-sure of MIs by grinding due to sample preparation for EP-MA could result in substantial H2O loss after the Ramananalysis (Holtz pers comm 2003) Such H2O loss duringthe opening of the MI might explain the much higher Ra-man-determined H2O concentration in the large MI TR31-2of the Teplice rhyolite (119 wt) as compared to that ob-tained from EPMA using ldquoH2O by differencerdquo (49 wt)The in situ H2O determination of ldquounopenedrdquo MIs is the ma-jor advantage of Raman spectroscopy over EPMA SIMSFTIR and older near-surface Raman methods

As compared to the other investigaged samples the con-trast between MI composition and whole rock chemistry ofthe Schoumlnfeld rhyodacite is extraordinarily high The majorelement concentrations of MIs in the Schoumlnfeld rhyodaciteindicate that at the time of their entrapment the quartz phe-nocrysts were in a much more evolved magma than that re-flected by the rhyodacitic bulk chemistry Muumlller et al(2005) describe resorption surfaces revealed by cathodolu-minescence of MI-bearing quartz phenocrysts and inverselychemically zoned plagioclases in the rhyodacite Such ob-servations in conjunction with the data set presented heresuggest that quartz and feldspar phenocrysts were highlymobile within a stratified magma chamber which resultedfrom multiple recharge events which occurred during theevolution of the Schoumlnfeld magma reservoir Anderson et al(2000) and Peppard et al (2001) describe chemical con-trasts between MIs within single quartz phenocrysts fromthe Bishop Tuff which are interpreted as the result of sink-ing of quartz phenocrysts over several kilometres within astratified magma chamber due to an observed increase in thegas-saturation pressure of CO2 in MIs from phenocryst fromthe core to phenocryst rim However simple crystal settling


without thermal induced convection is an unlikely explana-tion for the resorption features visible in CL images becauseof the small density contrast between quartz crystals and fel-sic magma The variability of the H2O in MIs from theSchoumlnfeld rhyodacite support the idea of quartz phenocrystmovement in a stratified reservoir with magmas of differentH2O content

The high H2O content of the MI TR31-2 (119 wt)contrasts with both the generally low H2O contents of MIs inthe Teplice rhyolite and with the major element compositionof the MI (Table 2b) This one MI has a more primitive com-position than MIs in the Schoumlnfeld rhyodacite and Scheller-hau granite The more primitive MI composition corre-sponds to the generally low H2O content of MIs in the Tepli-ce rhyolite Based on the available data we can not explainwhy the extraordinary large MI TR31-2 contains 10 timesmore H2O than the other MIs in the same phenocrystthough one possibility would be that it represents an H2O-rich melt droplet

High F (102 wt) in MI SHX-8 of the Schellerhaugranite may be responsible for the devitrification of the MIshortly subsequent to autoclave treatment The extreme Fcontent is cannot reflect a homogenization of F-rich mineralinclusions (eg topaz fluorite or Fe- and Li-rich micas) be-cause Li2O CaO Al2O3 and FeO do not correlate with FThe P2O5 abundances of the MIs are far too low to suggestthat apatite grains were melted during MI homogenizationUp to 14 wt F can be dissolved in a peraluminous melt(IV Veksler pers comm 2003) High F in MI seems to bea common feature of the highly differentiated granites of theErzgebirge 64 wt F were found in MIs from the Zinn-wald microgranite (eastern Erzgebirge Thomas et al2005) and 89 wt F in MIs of the Podlesı granite (westernErzgebirge Breiter et al 1997) The trend towards higher Fand Cl in MIs beginning from the older Schoumlnfeld rhyodaci-tes and ending with the Schellerhau granites reflects a con-tinuous magmatic evolution in the eastern Erzgebirge volca-no-plutonic complex However the enrichment of H2O inMIs involves only the last three magmatic stages the Tepli-ce rhyolite the Altenberg-Frauenstein microgranite and theSchellerhau granite all of which are assumed to have origi-nated from the same magma source (Muumlller et al 2005)

7 Summary

We presented H2O concentrations of homogenized MIs ingranites and rhyolites from Cornwall and Erzgebirge deter-mined by confocal Raman spectroscopy The study demon-strates the potential of confocal Raman spectroscopy for thequantitative analysis of dissolved H2O in silicate glasses andsaline phases of MIs over a concentration range from 07 to39 wt These results demonstrate that Raman spectrosco-py is both an effective and a non-destructive analytical tech-nique for the in situ study of the H2O contents of MIs

Our sample suite indicates that the H2O content of MIsfrom volcanic rocks is more variable than is the case for plu-tonic rocks This can be mainly attributed to the fact that theselected volcanic rocks from the eastern Erzgebirge volca-

no-plutonic complex were derived from stratified magmachambers and were overprinted by magma mixing prior toeruption The differences in both the major and minor ele-ment composition between MIs and their whole rock hostsindicate that MIs were not only trapped at the final stage ofmagma evolution but also at earlier crystallization stages ofthe quartz phenocrysts

The H2O concentration of the saline phase in MIs fromthe Landrsquos End granites ranges between 18 and 39 wtThe coexistence of hypersaline fluids with a silicate meltseems to be a characteristic feature of granites from theLandrsquos End pluton Such hypersaline fluids are highly effi-cient at dissolving Sn from both the magma and its countryrocks (Heinrich 1990 Lehmann 1990 Keppler amp Wyllie1991 Taylor amp Wall 1993 Muumlller amp Seward 2001) Suchhypersaline constituents may have contributed to the Sn-Cumineralization of the St Just mining district in which is ge-netically related to the Landrsquos End pluton Another charac-teristic feature of MIs in the Landrsquos End granites is the ab-sence of fluorine In contrast the tin-rich Schellerhau gran-ites of the eastern Erzgebirge contain MIs with up to 10wt F

The relative abundances of Li Be and B in MIs deter-mined by SIMS suggest that these ratio are distinctive forspecific magmatic provinces MIs from rocks of the easternErzgebirge volcano-plutonic complex are relatively en-riched in Li and Be in comparison to MIs from granites ofthe Landrsquos End pluton B is the most abundant LLE in MIsfrom the Landrsquos End pluton which is also reflected in thewhole rock chemistry The high B concentrations in MIs ofthe Landrsquos End granites and of the highly evolved granitesof the eastern Erzgebirge volcano-plutonic complex suggestthat the enrichment of B originates from melting of proto-liths and long-term differentiation of large-volume magmasThe generally higher abundance of B in the Cornubian gran-ites is caused by the relatively high initial B content of ~100ppm in the Devonian metasediments (Hall 1990) which areconsidered to have been the dominant source rock for theCornubian magmas In contrast to the Cornubian graniteswhere tourmaline may reach the importance of a rock-form-ing mineral the highly evolved granites of the eastern Erz-gebirge are Li-mica-rich topaz-albite granites with only ac-cessory tourmaline reflecting the proportional prevalence ofLi and F against B

Acknowledgements This study was supported by both theDeutsche Forschungsgemeinschaft (MU 17172-1) and theNatural History Museum of London We greatly appreciatethe assistance of M Kreplin operating the CNC milling ma-chine for quartz disk preparation We thank H Steigert andR Schulz for performing high-pressure homogenization ex-periments in autoclaves of the Hydrothermal Laboratory atthe GeoForschungsZentrum Potsdam Germany We thankJ Koepke of the University of Hannover for the hydratedNIST 610 reference samples Technical support was provid-ed by J Spratt and T Wighton (NHM London) Inspiringdiscussions and field introduction by Chris Halls are highlyappreciated The reviews by Jacob Lowenstern and JayThomas greatly improved this paper


References

Anderson AT Davis AM Lu F (2000) Evolution of Bishop tuff

rhyolitic magma based on melt and magnetite inclusions andzoned phenocrysts J Petrol 41 449-473

Audetat A Guumlnther D Heinrich CA (2000) Magmatic-hydro-thermal evolution in a fractionating granite A microchemicalstudy of the Sn-W-F-mineralized Mole Granite (Australia) Geo-chim Cosmochim Acta 64 3373-3393

Breiter K (1995) Geology and geochemistry of the Bohemian partof the Teplice rhyolite and adjacent post-rhyolite granites TerraNostra 7 20-24

ndash (1997) The Teplice rhyolite (Krusne Hory Mts Czech Republic)ndash chemical evidence of a multiply exhausted stratified magmachamber Vıstnık Eeskeho geologickeho ustavu 72 205ndash213

Breiter K Fryda J Seltmann R Thomas R (1997) Mineralogi-cal evidence for two magmatic stages in the evolution of an ex-tremely fractionated P-rich rare-metal granite The PodlesıStock Krusne Hory Czech Republic J Petrol 38 1723-1739

Breiter K Foumlrster H-J Seltmann R (1999) Variscan silicic mag-matism and related tin-tungsten mineralization in the Erzgebirge-Slavkovsky les metallogenic province Mineral Deposita 34505-531

Breiter K Novak JK Chulpacova M (2001) Chemical evolu-tion of volcanic rocks in the Altenberg-Teplice Caldera (EasternKrusne Hory Mts Czech Republic Germany) Geolines 1317-22

Chabiron A Pironon J Massare D (2004) Characterisation ofwater in synthetic rhyolitic glasses and natural melt inclusions byRaman spectroscopy Contrib Mineral Petrol 146 485-492

Charoy B (1979) Definition et importance des phenomenes deute-riques et des fluides associes dans les granites consequences me-tallogeniques Sciences de la Terre Nancy Mem 37 1-364

Chen Y Clark AH Farrar E Wasterneys HAHP HodgsonMJ Bromley AV (1993) Diachronous and independent histo-ries of plutonism and mineralisation in the Cornubian Batholithsouthwest England J Geol Soc London 150 1183-1191

De Vivo B amp Bodnar RJ (2003) Melt inclusions in volcanic sys-tems Developments in Volcanology 5 Elsevier Amsterdam258 p

Devine JD Gardner JE Brack HP Layne GD RutherfordMJ (1995) Comparison of microanalytical methods for estimat-ing H2O contents of silicic volcanic glasses Amer Mineral 80319-328

Foumlrster H-J Seltmann R Tischendorf G (1995) High-fluorinelow phosphorus A-type (post-collision) silicic magmatism in theErzgebirge Terra Nostra 7 32-35

Foumlrster H-J Tischendorf G Trumbull RB Gottesmann B(1999) Late-collisional granites in the Variscan Erzgebirge Ger-many J Petrol 40 1613-1645

Frezzotti M-L (1992) Magmatic immiscibility and fluid phaseevolution in the Mount Genis granite (southeastern Sardinia Ita-ly) Geochim Cosmochim Acta 56 21-33

ndash (2001) Silicate-melt inclusions in magmatic rocks applications topetrology Lithos 55 273-299

Hall A (1990) Geochemistry of the Cornubian tin province Miner-al Deposita 25 1-6

Hanson B Delano JW Lindstrom DJ (1996) High-precisionanalysis of hydrous rhyolitic glass inclusions in quartz pheno-crysts using the electron microprobe and INAA Amer Mineral81 1249-1262

Heinrich CA (1990) The chemistry of hydrothermal tin-tungstenore deposition Econ Geol 90 705-729

Herd C Treiman A McKay G Shearer C (2002) Evaluatingevidence for magmatic water in Martian basalts SIMS analysesof Li and B in experimental and natural phases 2002 MeetingGeol Soc America Abstracts with Programs 34 82

Jackson NJ Halliday AN Sheppard SMF Mitchell JG(1982) Hydrothermal activity in the St Just Mining DistrictCornwall England in ldquoMetallization associated with acid mag-matismrdquo Evans AM ed John Wiley and Sons Ltd London137-179

Keppler H amp Wyllie PJ (1991) Partitioning of Cu Sn Mo W Uand Th between melt and aqueous fluid in the systems haplogra-nite-H2O-HCl and haplogranite-H2O-HF Contrib Mineral Pet-rol 109 139-150

Lehmann B (1990) Metallogeny of tin Springer Verlag Berlin211 p

Lehmann B Dietrich A Heinhorst J Metrich N Mosbah MPalacios C Schneider H-J Wallianos A Webster J Winkel-mann L (2000) Boron in the Bolivian tin belt Mineral Deposi-ta 35 223-232

Lowenstern JB (2003) Melt inclusions come of age volatiles vol-canoes and Sorbyrsquos legacy in ldquoMelt inclusions in volcanic sys-tems ndash methods applications and problemsrdquo De Vivo B Bod-nar RJ eds Elsevier Science BV 1-21

Morgan GB amp London D (1996) Optimizing the electron micro-probe analysis of hydrous alkali aluminosilicate glasses AmerMineral 81 1176-1185

Muumlller A amp Seltmann R (2002) Plagioclase-mantled K-feldsparin the Carboniferous porphyritic microgranite of Altenberg-Frau-enstein Eastern ErzgebirgeKrusne Hory Bull Geol Soc Fin-land 74 53-79

Muumlller A Seltmann R Behr H-J (2000) Application of catho-doluminescence to magmatic quartz in a tin granite ndash case studyfrom the Schellerhau Granite Complex Eastern Erzgebirge Ger-many Mineral Deposita 35 169-189

Muumlller A Breiter K Seltmann R Pecskay Z (2005) Quartz andfeldspar zoning in the eastern Erzgebirge volcano-plutonic com-plex (Germany Czech Republic) evidence of multiple magmamixing Lithos 80 201-227

Muumlller A Seltmann R Halls C Jeffries T Dulski P Spratt JKronz A (2006) The Landrsquos End granite Cornwall the evolu-tion of a composite and mineralised pluton Ore Geol Rev 28329-367

Muumlller B amp Seward TM (2001) Spectrophotometric determinationof the stability of tin(II) chloride complexes in aqueous solution upto 300 degrees C Geochim Cosmochim Acta 65 4187-4199

Naumov VB (1979) Determination of concentration and pressureof volatiles in magmatic melts based on the study of inclusions inminerals Geochimija 7 997-1007

Pearce NJG Perkins WT Westgate JA Gorton MP JacksonSE Neal CR Chenery SP (1997) A compilation of new andpublished major and trace element data for NIST SRM 610 andNIST SRM 612 glass reference materials Geostandard Newslet-ter 21 115-144

Peppard BT Steele IM Davis AM Wallace PJ AndersonAT (2001) Zoned quartz phenocrysts from the rhyolitic BishopTuff Amer Mineral 86 1034-1052

Perny B Eberhardt P Ramseyer K Mullis J Pankrath R(1992) Microdistribution of aluminium lithium and sodium in aquartz possible causes and correlation with short lived cathodo-luminescence Amer Mineral 77 534ndash544

Powell T Salmon S Clark AH Shail RK (1999) Emplace-ment styles within the Landrsquos End Granite Cornwall Geosc SWEngland 9 333-339


Stemprok M Holub FV Novak JK (2003) Multiple magmaticpulses of the Eastern Erzgebirge Volcano-Plutonic ComplexKrusne horyErzgebirge batholith and their phosphorus con-tents Bull Geosc 78 277-296

Taylor JC amp Wall VJ (1993) Cassiterite solubility tin speciationand transport in magmatic acqueous phase Econ Geol 88 437-460

Thomas R (1992) Results of investigations on melt inclusions invarious magmatic rocks from the northern border of the Bohemi-an Massif in ldquoProceedings of the 1st International Conferenceabout the Bohemian Massif Prague 1988rdquo Kukal Z ed CzechGeological Survey Prague 298-306

ndash (2000) Determination of water contents of granite melt inclusionsby confocal Raman microprobe spectroscopy Amer Mineral85 868-872

ndash (2002) Determination of water contents in melt inclusions by laserRaman spectroscopy in ldquoMelt inclusions methods applicationsand problems Proceedings of the workshop on volcanic systemsgeochemical and geophysical monitoringrdquo De Vivo B amp Bod-nar RJ eds De Frede Editore Napoli Napoli 211-216

Thomas R Foumlrster H-J Heinrich W (2003) The behaviour ofboron in a peraluminous granite-pegmatite system and associatedhydrothermal solutions a melt and fluid inclusion study ContribMineral Petrol 144 457-472

Thomas R Foumlrster H-J Rickers K Webster JD (2005) Forma-tion of extremely F-rich hydrous melt fractions and hydrothermalfluids during differentiation of highly evolved tin-granite mag-mas a meltfluid-inclusion study Contrib Mineral Petrol 148582-601

Thomas R Kamenetsky D Davidson P (2006) Laser Ramanspectroscopic measurements of the water in unexposed glass in-clusions Amer Mineral 91 467-470

Tischendorf G (ed) (1989) Silicic magmatism and metallogenesisof the Erzgebirge Veroumlffentlichungen Zentralinstitut fuumlr Physikder Erde 107 52-60

Van Marcke de Lummen G (1986) Geochemical variation of theLandrsquos End granite (south-west England) in relation to its tin po-tential in the light of data from western marginal areas Proc Us-sher Soc 6 398-404

Vannucci R Tiepolo M Zanetti A (2003) Light lithophile ele-ments (Li Be and B) determination in amphiboles a comparisonbetween LA-ICP-SFMS and SIMS Geochim Cosmochim ActaSuppl 1 67 A511

Webster JD Thomas R Rhede D Foumlrster H-J Seltmann R(1997) Melt inclusions in quartz from an evolved peraluminouspegmatite Geochemical evidence for strong tin enrichment influorine-rich and phosphorus-rich residual liquids GeochimCosmochim Acta 61 2589-2604

Webster J Thomas R Foumlrster H-J Seltmann R Tappen C(2004) Geochemical evolution of halogen-enriched granite mag-mas and mineralizing fluids of the Zinnwald tin-tungsten miningdistrict Erzgebirge Germany Mineral Deposita 39 452-472

Zanetti A Oberti R Piccardo GB Vannucci R (2000) Light li-thophile elements (Li Be and B) volatile (H F and Cl) and traceelement composition of mantle amphiboles from Zabargad peri-dotite Insights into the multistage subsolidus evolution of sub-continental mantle during Red Sea rifting J Conf Abstr 51120

Received 10 November 2004Modified version received 28 February 2006Accepted 18 April 2006


2005 for the eastern Erzgebirge) Given this volume of pre-vious work we have a solid foundation from which to assessthe significance of our data and to evaluate the applicabilityof MIs to petrogenetic interpretations This current studysupplements Muumlller et al (2006) and Muumlller et al (2005)which document the magmatic evolution of the Landrsquos Endpluton and the eastern Erzgebirge volcano-plutonic com-plex respectively

The application of the Raman spectroscopy has advantagesover other methods of H2O determination in silicate glassessuch as Karl Fisher titration and Fourier transform infrared(FTIR) spectroscopy due to its non-destructive in situ natureand its ability to acquire data rapidly (Thomas 2000 and2002 Chabiron et al 2004 Thomas et al 2006) The deter-mination of H2O concentration in MIs by Raman spectrosco-py is the focus of this study which is augmented by secondaryion mass spectrometry (SIMS) and electron microprobe anal-yses (EPMA) of element concentrations in MIs H2O concen-trations in MIs determined by both Raman spectroscopy andEPMA by using the ldquoH2O by differencerdquo method (Devine etal 1995) are compared This study also aims to determine theextent to which the H2O Li Be B Cl concentrations of MIsdiffer between the Landrsquos End (Cornwall) and eastern Erzge-birge rare metal districts The small size of our dataset is dueto both the rareness of well-preserved MIs in granites as wellas the difficult preparation procedures (including homogeni-zation in autoclaves and MI exposure by hand grinding) re-quired before running the actual analyses

2 Geologic background

The Landrsquos End pluton forms part of the late-Variscan Cornu-bian batholith and it is a composite pluton hosting the Sn-Cumineralizations of the St Just mining district The pluton hasan age of 2745plusmn14 Ma (U-Pb monazite age Chen et al1993) and consists of early megacrystic fine-grained biotite(Mg-siderophyllite) granites and younger Li-siderophyllitegranites tourmaline granites a massive quartz-tourmalinephase (MQT) and albite microgranites (Muumlller et al 2006) Inthis study we investigate MIs found in the megacrystic fine-grained biotite granite in the Li-siderophyllite granite and inthe MQT These granites are peraluminous (ACNK = 11ndash14) high-K calc-alkaline rocks with low phosphorus con-tents (lt04 wt) They are genetically related via continuousfractional crystallization from a common magmatic reservoir(Muumlller et al 2006) The younger intrusive units of theLandrsquos End pluton are enriched in B due to melting of B-richpelitic protoliths intense fractionation and filter pressing(Jackson et al 1982 Charoy 1979 Van Marcke de Lummen1986 Muumlller et al 2006) Sample locations are shown inFig 1 and Fig 2 in Muumlller et al (2006)

The second study area reported on here is the Upper Car-boniferous eastern Erzgebirge volcano-plutonic complex ineastern Germany The Altenberg-Teplice caldera forms aneruptive centre with several tin granites which were intrud-ed after caldera collapse These late granites host the histori-cally important Zinnwald Krupka and Altenberg Sn-W de-posits From this complex we studied MIs from the Nieder-bobritzsch granite massif the Schoumlnfeld rhyodacites the

Teplice rhyolites the Altenberg-Frauenstein microgranitesand the tin-specialized Schellerhau granites The postkine-matic Niederbobritzsch granites belong to a group of low-Fbiotite monzogranites and form a multiphase intrusion witha transitional I- to S-type character (Foumlrster et al 1999)The Schoumlnfeld rhyodacites represent a relatively primitivecalc-alkaline magma whose chemical evolution was proba-bly uncoupled from the overlaying Teplice rhyolites (Brei-ter et al 2001) The Teplice rhyolites are high-K calc-alka-line in character (Breiter 1995 1997 Breiter et al 2001)The eruption of the Teplice volcanic rocks led to the col-lapse of the Altenberg-Teplice caldera with N-S elongatedring fractures that were subsequently filled by multiple in-trusions of the porphyritic Altenberg-Frauenstein micro-granite (Muumlller amp Seltmann 2002) The topaz-bearing raremetal granites (post-caldera stage) are represented by theSchellerhau granite complex which is situated in the centreof the Altenberg-Teplice caldera and which consists of bio-tite syeno- to monzogranites and seriate albite granites(Muumlller et al 2000) These rocks are P-poor and Li-F-en-rich and show some A-type traits (Foumlrster et al 1995 Brei-ter et al 1999) For location of sample from the Erzgebirgewe refer to Fig 1 in Muumlller et al (2005)

3 Description of melt inclusions

Crystallized MIs from the Landrsquos End pluton are rare andthey are hard to identify due to the dense network of fluid in-clusion trails which frequently penetrate the host quartzThe spherical to hexagonal MIs of the megacrystic biotitegranite and Li-siderophyllite granite are usually 5 to 35 micromin diameter commonly multiphase with a small volatilebubble and occasionally visible crystals (eg biotiteFig 1a) Crystallized MIs of the MQT have irregular shapesand are commonly 5 to 20 microm in size frequently contain avapour phase and occasional halite crystals (Fig 1c)

MIs in the Niederbobritzsch granite are rare The crystal-lized and spherical MIs are 8 to 15 microm in diameter and mostof them contain a vapour bubble (Fig 1e) MIs of theSchoumlnfeld rhyodacite can be either crystallized or glassy(Fig 1g) Up to 10 inclusions have been noted in a fragmentof a single phenocryst The size of the hexagonal and spheri-cal MIs is between 8 and 35 microm The hexagonal MIs of theTeplice rhyolite (TR2b) contain glass a vapour bubble andone or more crystals The size ranges from 8 to 110 microm butmost of the MIs have a diameter of 10 to 45 microm (Fig 1i)Approximately two thirds of the MIs are glassy and onethird are crystallized MIs of the Schellerhau granite rangefrom 5 microm to 120 microm in diameter are commonly sphericalMIs containing a vapour phase Large MIs sometimes con-taining visible apatite and mica crystals

4 Methods

41 Melt inclusion selection and sample preparation

MIs were examined in quartz crystals of doubly polishedthick (~500 microm) wafers Crystals containing MIs were mil-


halite





Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n









saline phase


with crystal

silicate glass

silicate glass

vapour

phase

vapour

phase

a CW32-8 b CW25-3e c CW02-8




Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n














































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References























































halite





Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n









saline phase


with crystal

silicate glass

silicate glass

vapour

phase

vapour

phase

a CW32-8 b CW25-3e c CW02-8




Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n














































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References























































saline phase


with crystal

silicate glass

silicate glass

vapour

phase

vapour

phase

a CW32-8 b CW25-3e c CW02-8




Easte

rnE

rzg

eb

irg

eL

an

drsquos

En

dp

luto

n














































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References





























































































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References
















































































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References


























































MI (3b)homogen

WR MI (8)homogen

WR MI (7)homogen

WR

n 1 2 4


Total 9363 9890 9395 9931 943 959







n 2 3 3 2





00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References























































00

05

10

15

20

0 50

BBe

LiB

CW32

CW02

TR31-1

TR31-2-1

TR31-2-2

SHX-8

CW32-quartz

SHX-2-quartz


(CW32-1)

MQT (CW02-1)




Eastern Erzgebirge

EasternErzgebirge





quartz around SHX-3








TR31-2-1 36 (lt20) 16 47TR31-2-2 44 (lt20) 19 52


quartz analyses











6 Discussion







62 Erzgebirge







7 Summary








References

























































6 Discussion







62 Erzgebirge







7 Summary








References


























































7 Summary








References























































References







































































Documents

Water content of granitic melts from Cornwall and Erzgebirge: A Raman spectroscopy study of melt inclusions