Analcime Phenocrysts in Igneous Rocks: Primary Or Secondary?

American Mineralogist, Volume 76, pages 189-199, 1991

Analcime phenocrysts in igneous rocks: Primary or secondary?

Hanc,Loun R. Knnr,ssoN* Department of the GeophysicalSciences, The University of Chicago,Chicago, Illinois 60637, U.S.A. Ronrnr N. Cr..lvroN Enrico Fermi Institute, Department of Chemistry, and Department of the Geophysical Sciences, The University of Chicago,Chicago, Illinois 60637, U.S.A.

Ansrru,cr The origin of analcime phenocrystsin volcanic rocks is problematic. Are they primary minerals crystallized directly from melts or are they secondary minerals formed from preexisting igneousminerals such as leucite?To addressthis question, we have obtained stable isotope (H, N, O), electron microprobe, and ion microprobe data for analcime- bearing samplesfrom the Crowsnest Formation in Canada and the Colima volcanic complex in Mexico. Isotopic ratios were obtained for the framework (6'tO) and the channel water (0"O*, 6D) for two Crowsnest samplesand one Colima sample. Both O and H isotopic ratios of channel water in all three samples fall on the meteoric water line, reflecting local meteoric water, and are clearly not magmatic. The dt8O,values for Crowsnest(13.6 and 14.2V*)and Colima (8.78@)indicate that these analcime sampleshave either exchanged with external fluids at subsolidustemperatures or have formed from a preexistingigneous mineral such as leucite. Elevated D'8Ovalues of sanidine phenocrysts(8.2 and 10.9E@) demonstrate O isotopic exchange with an external reservoir in two Crowsnest trachytes. Evidence of low-temperature water-rock interaction is also found in the Colima minette SAY-104. Its whole-rock D'8Ovalue (7.6E@)is significantly higher than those of associated basanitesand leucite basanites(5.2-6.18@), and the hlgh N content (6 ppm) and low 6'5N value (3.4Vu) imply interaction with water either during magma genesis, transport, or postextrusion. The glass matrix in the Colima minette is also unusually HrO rich (4 wt%) suggestingposteruption, glass-fluid interaction. Collectively our data for the Crowsnest and Colima samples favor a secondary origin for analcime in these rocks.

INrnonucnoN spar phenocrystshandpicked from four Crowsnestrocks Analcime phenocrysts occur most commonly in vol- were analyzed for O isotope ratios (le, PN-398, WR-4, canic alkalic rocks such as phonolites and lamprophyres. and WR-l l). Additional data were also collected for the The origin of these phenocrystshas perplexed geologists Colima sample, including whole-rock O and N isotope since the turn of the century (Kmght, 1904;Daly, l9l2; analysis, electron and ion microprobe measurementsof phases Washington,l9l4; MacKeruie, l9l5;' Prisson,l9l5). Did various in SAY-104, including HrO content and the crystals grow as a primary phasefrom a melt or did major- and trace-elementconcentrations. they form as a secondaryphase as a result of postmag- matic alteration? If the analcime is magmatic, then HrO- Pnrpu.ny rcr{Eous vs. sEcoNDARy rich magmas are implied. REPLACEMENT HYPIOTHESES In an attempt to place quantitative constraints on the Two hypotheseshave emergedto explain the origin of origin of analcime in volcanic rocks, stable isotope analcime phenocrystsin igrreousrocks: the primary ig- (H, N, O), electron microprobe, and ion microprobe data neoushypothesis and the secondaryreplacement hypoth- were collected from two well-documented analcime oc- esis. In the primary igneoushypothesis, analcime is pos- currences: Crowsnest Formation, Alberta, Canada and tulated to crystallize directly from a silicate melt without Colima volcanic complex, Jalisco, Mexico. O isotope the formation of any intermediate minerals. Proponents analyseswere obtained of analcime frameworks, and both of the igneous hypothesis (Larsen and Buie, 1938; Wil- O and H isotope analyses were obtained ofchannel water kinson, 1968; Pearce,19701, Cundari, 1973; Roux and from two Crowsnest samples,2a and PN-39E, and one Hamilton, 1976;Woolley and Symes,1976; Ferguson and Colima analcime separatefrom sample SAY-104. Feld- Edgar,1978; Church, 1978,1979;Edgar,1979;Luhr and Carmichael, 198l) give one or more of the following as * Present address:Planetary ScienceBranch, Code SN2, NASA evidencefor a primary igneousorigin: (l) the crystalsare Johnson SpaceCenter, Houston, Texas 77058, U.S.A. euhedral, (2) the host rock is fresh and other associated 0003404x/9 I /0 I 02-OI 89$02.00 189 190 KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME igneous phases,in particular glassand olivine, show no which clearly deviate from that of ideal analcime, visible signsof alteration, (3) other hydrous minerals such lNa(AlSi,Ou).H,Ol, in which the Si/Al ratio is 2. Saha as amphibole are present, suggestinga hydrous magma, (1961) suggestedthat the SilAl ratio of natural analcime (4) differentiation trends are controlled by Na enrich- might be a useful geothernometer, although, as he point- ment, and (5) analcime can crystallize from liquids in ed out, the apparentcorrelation of Si/Al with temperature simple experimental systems.The following evidence is might be spurious sincehis experimentswere unreversed. used against an igneous origin: (l) the host rock is fre- Indeed, Coombs and Whetten (1967) concluded on the quently altered, (2) the experimentally determined sta- basis of about 50 analcime samples from a variety of bility of analcime is relevant within extremely limited paragenesesthat the silica content of analcime is influ- rangesin pressure,temperature, and whole rock compo- enced by the chemical environment in which analcime sition, (3) other igneoushydrous minerals are absent,in- crystallizes as well as by the temperature. On the other dicating absenceof HrO, and (4) the differentiation trends hand, Ferguson and Edgar (1978) argued that the Si/Al are not controlled by Na enrichment (Nakamura and ratio of analcime could still be used to characterizepri- Yoder, 1974;Wilkinson, 1977;Henderson, 1984). mary analcime, even though they were unable to separate An alternative explanation for the origin of analcime igneousanalcime from diageneticanalcime (seeFig. 3 in in igneousrocks is that the analcime is secondaryand has Fergusonand Edgar, 1978). formed from a preexisting igneous mineral, most likely Luhr and Kyser (1989) suggestedthat primary igneous leucite. According to the leucite transformation hypoth- analcime is generallyhigher in Fe than secondaryhydro- esis,the analcime is formed by the ion exchangereaction thermal analcime (see Fig. 4 in Luhr and Kyser, 1989). leucite + Na* + HrO : analcime + Kt at subsolidus It is likely, however, that the apparent difference in Fe temperatures.This transformation can occur either dur- contentsreflects impurities (e.g.,oxide inclusions)as not- ing cooling of the magma or after the host rock has solid- ed by Coombsand Whetten(1967). ified. It has been known since the experiments of km- A few workers have searchedfor clues to the origin of berg (1876) that this reaction can occur rapidly in salt analcime among minor and trace elementssuch as K, Ba, solutions at low temperatures. Gupta and Fyfe (1975) Cs, Sr, Rb, and Li that can substitute for the Na atoms recently demonstratedthat the leucite transformation can located in the channelsof the analcime structure 0.arsen go to completion in a matter of days even in dilute salt and Buie, I 938; Lyons, I 944; Fergusonand Edgar, I 978; solutionsat 150 "C. Barberi and Penta, 1984; Keith et al., 1983; Luhr and Proponents of the leucite transformation hypothesis Kyser, 1989). Based on the results of experimental ion (Prisson, l9l5; Gupta and Fyfe, 1975; Taylor and exchangestudies, the large ion lithophile (LIL) elements MacKenzie, I 9 75 ; Wilkinson, I 977; Comin-Chiaramonti le.g.,K* (1.33A), Ba2'(1.34A), and Cs* (1.82A)l enter et al., 1979) give the following argumentsin its favor: (l) analcime channels only at elevated temperatures(>200 experiments show that leucite can be transformed into "C) (Barrer, 1978;Keith et al., 1983),so that abnormally analcime by simple ion exchangewith Na-rich fluids, and high concentrations of LIL elements would support a (2) the transformation is extremely rapid even on a lab- magmatic origin. Becauseof a lack of data, however, no- oratory time scaleand should therefore easily go to com- body knows what constitutes "abnormally high." More- pletion over short geological time scales.Opponents of over, these elementsmay have been inherited from pre- the leucite transformation hypothesis(MacKenzie, 19l5; existing minerals (e.g., nepheline or leucite). Ferguson and Larsen and Buie, 1938; Lyons, 1944; Wilkinson, 1968; Edgar (1978) argued against a secondaryorigin ofanal- Pearce, 1970; Woolley and Symes, 1976; Ferguson and cime from the CrowsnestFormation becauseit has very Edgar, 1978; Luhr and Carmichael, l98l) argue against low Rb contents (37 ppm) relative to analcime formed it for the following reasons:(l) leucite and analcime are from leucite at Vico Volcano, Italy (4003 ppm). Com- rarely seen in the same rock and partially transformed parison of trace elements in analcime from different lo- leucite is quite rare, (2) analcime occurs in rocks where calities is inappropriate as the trace element concentra- there is no obvious sourceof Na-rich fluids, (3) the trans- tions depend on the concentration in the host rock and formation of leucite to analcimeis accompaniedby a l0o/o possibly the precursor mineral. volume increaseso there should be expansion cracks in Studies of the equilibrium phase relations in the qua- the vicinity of the analcime and disruption of inclusions rernary sysremnepheline (NaAlSio,)-kalsilite (KAlsio.)- originally present in the leucite and that these are not silica (SiOr)-HrO(Ne-Ks-Si-HrO) and its subsystems observed, and (4) differentiation trends should be con- indicate that the conditions under which analcime can trolled by leucite crystallizatioo, €.8., K depletion. coexistwith a melt are very restrictedin terms of pressure (5-12 kbar P"ro), temperature, and melt composition Pnrvrous woRx (Peterset al., 1966; Kim and Burley, l97l; Roux and Many workers have attempted to link the chemistry Hamilton, 1976;Znng and MacKenzie, 1984). This re- and the origin of analcime, motivated primarily by the stricts magmatic analcime crystallization from a hydrous experimentalwork of Saha(1959, l96l). He synthesized magma at depths of 20-50 km and at 600-660'C which analcime in the systemNaAlSiOo (nepheline)-NaAlsi3os poses a serious problem to those proposing an igneous (albite)-HrO with SilAl ratios ranging from -1.4 to 3, origin of analcime phenocrystsin extrusive rocks. Rapid KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME l9l transport from depth of such HrO-rich magmas would require explosive volcanism. Church (1978) has argued IGNEOUS that analcime could not survive such violent treatment = ( N 3) colima crowsnest without rounding or shattering.It should be noted, however, that the synthetic systemsare highly simplified and N NN do not include important chemical components such as Mg, Fe, Ca, F, or Cl. It is unclear whether or not the HYDROTHERMAL addition of these components could raise the liquidus (N=40) temperature of analcime by 450 "C, lower the liquidus NN pressureby 5 kbar, or both. N NNNN Karlssonet al. (1985)and Luhr and Kyser (1989)proposed that primary igneous and secondaryanalcime might SEDIMENTARY (N=6) N have distinctive framework O isotope ratios (6'sO). Be- N NNN causeof the structural and chemical similarities between analcime and albite, it is reasonableto assumethat they should have similar O isotopic fractionation curyes. Hence, primary igneous analcime should have D'8O,val- 510152025 uesbetween 6 andTVu analogousto igneousalbite. Karls- 6'b ft.)"uo* DehydratedAnalcime son et al. (1985) determined6'80, values ranging from 8.87o to 24.lvm in sevenanalcime samplesfrom igneous, Fig. l. Rangeof O isotoperatios of analcimeframeworks hydrothermal, and sedimentary environments with 6'sO, from various environments(adapted from Karlssonand Clay- values correlated to formation temperature. Luhr and ton, 1990a).The figuredemonstrates that the origin ofigneous Kyser (1989) obtained a similar range in 6'80r (9.2- analcimecannot be uniquelydetermined solely on the basisof 2l.OV-) for six analcime samples.Based on their data and O isotopes. that of Karlsson et al. (1985), Luhr and Kyser (1989) concluded that purportedly primary igneousanalcime, such as those at Colima, cannot be distinguished from hydro- perature dehydration was complete. Analcime loseslittle thermal analcime based on O isotopes alone. Karlsson or no channelwater up to I 50'C even under high vacuum and Clayton (1990a) reported 61tO,values ranging from and must be heated to at least 350 "C to ensurecomplete 4.3Vulo 26.6Vofor roughly 50 analcime samplesfrom a dehydration (Karlsson, 1988; Karlsson and Clayton, variety of geologic environments. Their results, repro- 1990a).During dehydration, the channel water (1.4-3.3 duced in Figure l, clearly show that D'8O,of primary ig- mg) was collected by condensing it into a cold-trap at neous analcime and secondary hydrothermal or sedimen- liquid N temperaturesthus isolating it for isotopic anal- tary analcime all overlap. ysis. O, was extracted from feldspars and dehydrated analcime usingthe BrF, method ofClaytonand Mayeda(1963). M.trnRrAl,s AND METHoDS Channel water was either reacted with BrF, to liberate O, following O'Neil and Epstein (1966) or equilibrated with Samples small quantities of CO2 using the procedures of Kishima Descriptions of samplesand their localities are given by: and Sakai (1980). H, was releasedfrom channel water by Pearce(1970) for PN-39E; Ferguson(1977) and Ferguson reaction with U at 700 rC (see,e.9., Bigeleisen et al.,1952). and Edgar (1978) for 2a, le, WR-4, and WR-ll; Luhr For the whole-rock O and N isotope analysesof sample ( I 980), Luhr and Carmichael ( I 98 I ), and Luhr and Kyser SAY-104, a rock chip was finely ground (60-200 mesh) (1989)for SAY-104. and splits ofthe powder taken for each isotope analysis. Prior to analysis, both powders were outgassedunder high Stable isotope analysis dynamic vacuum (-t0-' torr) at 350 "C in order to rid Details of the experimental procedures are given by the analcime of channel water, which might otherwise Karlsson(1988) and Karlssonand Clayton (1990a).Fol- interfere with the O isotope results. Details of methods lowing Karlsson (1988), framework and channel water used for extraction and analysis ofN, content and isotope constituents were separated by dehydrating analcime ratios are given by Zhang (1988). samples in a separatevacuum line outside the fluorina- Isotopic measurementswere obtained with ratio iso- tion lines. Karlsson (1988) showed that negligible O isotope mass spectrometers.The stable isotope results are tope exchangeoccurs between framework and channel reported in the conventional D-notation (Craig, 1957). water upon dehydration. Hence, it is possible to obtain Values for D'8Oand dD are relative to SMOW, whereas not only precise(lo < 0.2V-), but also accuratedr8O,. val- 6'5N values are relative to AIR. ues for analcime. Powdered samples (10-80 mg) were loaded into a special dehydration vessel, evacuat€d at Electron microprobe analysis room temperature for I h, and then heated to 2-4 "C/ Back-scatteredelectron images (BSE) and X-ray ele- min to 450 "C under vacuum (- t0-' torr), at which tem- mental maps (K and Na) were obtained for sample SAY- r92 KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANATCIME

104 using a Cameca SX-5 electron microprobe with an Within the Crowsnest volcanics, there is widespread operating voltage of 15 kV and beam currents ranging evidence of low-temperature alteration in veins carrying from 0.7 to 6 nA. Spot analysis of individual phasesare secondaryminerals such as zeolitesand by the alteration consistent with those reported by Luhr and Carmichael of primary igneous minerals such as sanidine to albite (1981)and by Luhr and Kyser(1989). and olivine to iddingsite (Pearce,1970; Fergusonand Ed- gar, 1978).Leucite, nepheline and hydrous igneousmin- Ion microprobe analysis erals are notably absent in the Crowsnest volcanics Major oxide compositions, trace element concentra- (Pearce,1970; Ferguson and Edgar, 1978). tions, and HrO content of some groundmassglass, analcime, olivine, and pyroxenein sample SAY-104 were de- Results and discussion termined using an AEI-IM2O ion microprobe. Analyses The results of our isotopic work on minerals from the were performed with a 25 pm diameter primary beam of Crowsnest Formation are summarized in Table l. The 160- ions. Secondaryions of high energy(35-50 eV) were analcime framework D'8Ovalues, which are intermediate, used during analysis in order to minimize interferences 13.6-l4.3Vm(Fig. l), clearly lie within the rangeobserved from molecular ions. Synthetic borosilicate glasses,nat- for hydrothermal analcime (4-27EN)as shown by Karls- ural analcime (SAY-104), natural staurolite, natural ap- son (1988)and Karlssonand Clayton(1990a). Hence the atite, and CaF, were used as standardsfor oxides, H, Li, analcime phenocrystshave either undergone subsolidus Cl, and F, respectively.Ion yields ofthe borosilicateglasses exchangeor formed from a preexisting igneous mineral were normalized to the ion yield of Si. The oxide con- such as leucite (Karlsson et al., 1985; Karlsson, 1988). centrations in analcime, glass, and anhydrous minerals Data from Luhr and Kyser (1989) on secondaryanalcime were normalized to 9l wto/0,95 wto/o,and 100 wt0/0,re- from Roccamonfina,Italy, srrggestthat conversion of leu- spectively. In the calculations it was assumed that ion cite to analcime is accompanied by partial O isotopic yields for HrO were similar for the glassand for the anal- exchangeof the leucite framework. Subsolidusexchange clme. could have occurred during cooling, later during the low- temperature metamorphic event, or during both. The CnowsNpsr ANATTTME rapid exchangerates observed between analcime and HrO Introduction at 300 oC are consistent with either type of subsolidus The Crowsnest Formation in southwestern Alberta, exchange(Karlsson et al., 1988; Karlsson and Clayton, Canada,is renownedfor the occurrenceofabundant anal- 1990b).Ferguson and Edgar (1978) concludedthat the cime phenocrystsin its volcanics (MacKenzie, l9l5; Crowsnest rocks had not exchangedO isotopes with an Pearce, 1970; Fergusonand Edgar, 1978). The analcime external reservoir becausepyroxene from the formation phenocrystsreach a diameter of 3 cm and the total amount have normal igneousvalues of d'8O(5.1-5.67m). Pyrox- of analcime in these rocks can locally be as high as 60 ene, however, is among the most resistant silicates to O volo/o(Pearce,1970; Ferguson and Edgar, 1978). isotope exchangewhereas feldspars, feldspathoids, and The formation, which is of Lower Cretaceousage, con- analcime exchange much more readily (Taylor and sists mainly of agglomerates,volcanic sandstones,and Forrester,l97l; Karlsson and Clayton, 1990b).To test tuffs, all of which are interbedded with rare lava flows the possibility that O isotopes in the feldsparsand anal- and are intruded locally by dikes. The volcanic rocks in cime in the Crowsnestvolcanics were much more exten- lower parts of the formation are dominantly trachyte; sively exchangedthan pyroxene, we analyzed four sani- blairmorite occurs in the upper and younger parts of the dine separates(Table l). Since sanidine and albite have formation. Although analcime is pervasivein the ground- identical O isotope fractionation curves, it is possible to massof most rocks throughout the CrowsnestFormation, usethe albite-diopsideequation ofChiba et al. (1989)to analcime phenocrystsare found primarily in the analcime check the potassium feldspar data. According to this phonolites and blairmorites. Blairmorite is an extrusive equation, the sanidine-pyroxenefractionation is l.l%mat rock type characterizedby the predominanceof analcime magmatic temperatures(1300 K) and hence sanidine in as phenocrysts and in the matrix, with only minor equilibrium with pyroxene of 5.6V- should have a d'8O amounts of sanidine, pyroxene, and garnet phenocrysts. value of 6.7V*. The observedvalues ranging between 6.6 Analcime phonolite is distinguished from blairmorite by and l0.87oo(Table l) indicate that sanidinein le and PN- having abundant phenocrystsof sanidine, in addition to 39E shows effectsof low-temperature exchangewhereas analcime (Pearce,1970). The predominance of pyroclas- sanidine in WR-4 and WR-l I does not. The variation in tics in the CrowsnestFormation, suggeststhat the erup- the 6'80 values may reflect the varying extent to which tive style was predominantly explosive rather than effu- the potassium feldspars have been albitized. In sample sive. The formation is usually interpreted as having PN-39E, where O isotope ratios are available both for the resultedfrom the eruption of volcanoeslocated on a flood potassiumfeldspar and the analcime,the analcimeis 5.4Vm plain. The presenceofwater is inferred from the occur- more enriched in D'8Othan is the associatedpotassium rence of sandstones and water-worked volcanic tuffs and feldspar. This result is in good agreementwith experi- agglomerates,although it is not known whether it was mental data showing that analcime exchangesO isotopes primarily marine or fresh. more readily than feldspars do (Karlsson and Clayton, KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME r93

TABLE1. Values for d18Oof minerals from the Crowsnest For- mation

6100(9o) relative to SMOW -50 Colima(Luhl B Potas- Anal- Anal- =o l stum cime cime I Rock type Sample feldspar frw cw* a ,100 I bfairmorite 2a 14.3 -20.4 o blairmorite WR-4 6.6 tO analcimeohonolite WR-11 6.6 -150 trachyte 1e 10.9 trachyte PN€gE 8.2 13.6 -22.2* -200 Note; The abbreviationsfrw and cw refer to framework and channel water, respectively. -20 -10 +10 ' Precision(esd; + 9.37-. ** -166 dD measuredfor the same H.O sample is + 3q". 5ttg {%.)"ro* Fig.2. Relationshipbetween d'EO and dD in analcimechan- nel water.MWL : meteoricwater line (Craig,196l). Envelope 1990b). The main argument leveled against the forma- enclosescompositions of secondaryhydrothermal and sedimen- tion of analcime from leucite is that Na was not available tary analcimeanalyzed by Luhr and Kyser(1989) and Karlsson for the conversion to analcime since the water in conracr andClayton (1990a). Field of magmaticwater is from Sheppard with these rocks was nonmarine (MacKenzie, l9l5; (1986).Error bar showsla standarddeviation. Pearce,1970; Fergusonand Edgar, 1978).Albitization of sandine,however, showsthat Na must have been mobile and phlogopite in their groundmasswhereas the minettes in these rocks during the low-grade metamorphism contain analcime in their groundmass and phlogopite (Pearce,1970). The channelwater 6'80 (-228@)and 6D phenocrysts. Analcime and leucite have not been ob- (-166V@)values of Crowsnestanalcime (seeTable l) fall served together in the same sample. Petrographically closeto the meteoric water (Craig, line l96l), well outside analcime and leucite cannot be distinguished from one the field proposed for magmatic water (Fig. 2), indicating another since they have the same appearanceand mode a secondary origin ofthe channel water. This result agrees of occurrencein thin section. Both minerals occru as round with those of Karlsson (1990a) and Clayton who showed to euhedral microphenocrysts,reaching -0.1 mm, in the that analcime channel water reflects the meteoric water groundmassand both contain pyroxene and titanomag- of the sample locality. To conclude,the O isotope results netite inclusions. Luhr and Carmichael (1981) thus failed indicate that the analcime phenocrysts in the Crowsnest to find any characteristic textural features that distin- Formation have either sufferedsubsolidus O isotope ex- guished the two minerals. They could be identified only changeor formed from the transformation of leucite or by electron microprobe analysis. nepheline to analcime. The absenceof hydrous primary The presenceof highly forsteritic (Fono-ro)olivine phe- igneous minerals such as mica or amphibole indicates nocrystswith chrome-spinelinclusions in the Colima mi- that the magma was not HrO saturated suggestingthat nettessuggests that the minettes are mantle-derived mag- the formation of analcime from leucite is a more viable mas (Luhr and Carmichael, 1987). Maximum depth of explanation. origin is limited to about 100 km by the top of the subducted Cocos plate (Heatherington et al., 1987), Cor.rnnl ANArrcrME One particular minette sample, SAY-104, has drawn Introduction considerable attention (Luhr and Carmichael, l98l; The Colima minettes provide an unparalleled oppor- Karlsson et al., 1985; Hay, 1986; Karlsson, 1988; Luhr tunity to determine whether or not analcime can crystal- and Kyser, 1989). The sample contains analcime micro- lize directly from hydrous silicate melts. The analcime phenocrystsup to 0. 16 mm in diameter relatively free of occurs in rock serieswhose mineralogy, petrochemistry, inclusions and enclosedin glass,which appearsfresh (Figs. and geochemistry have been thoroughly documented 3a,3b). Hay (1986) concludedthat sampleSAY-104 gives (Luhr, 1980; Luhr and Carmichael,1981, 1987; Heath- unequivocal proof of igneous origin. Luhr and Carmi- erington et al., 1987).The Colima volcanic complex, sit- chael (1981) and Luhr and Kyser (1989) advocatedan uated in the Colima graben in southern Jalisco, Mexico, igneousorigin (melt temperatures:ll25-l150 'C) for the includes Late Quaternary (<20000 years)cinder and lava Colima analcime, although the former did not rule out coneswhich form a transitional basic alkalic suite ofbas- leucite transformation as long as the transformation took anites, leucite basanites,and analcime-bearingminettes. place during the late stagesof the crystallization of a hy- Volatile and incompatible element concentrations are high drous melt. in theserocks, especiallyin the latter two rock types.The whole-rock compositions and mineralogiesof the leucite Results basanitesand the minettes are virtually identical, the only O and H isotopes.Results ofO isotope analysesfor the differencebeing that the leucite basanitescontain leucite analcime framework are given in Table 2. Also included t94 KARISSON AND CLA,YTON: PRIMARY OR SECONDARY ANALCIME

in Table 2 are O isotope data from Luhr and Carmichael (1981)and Luhr and Kyser (1989).The whole-rockD'80 value for SAY-104 (7.6Vm)is somewhat higher than that of other minettes(5.3 and 6.4%m),basanites(5.7 arrd6.lE*), or leucite basanite(5.2E@). Except for analcime, 6'80 values of mineral separatesranging from 4.8 to 6.l%u are similar to those observedin other igneousrocks (Taylor, 1968). Our d'sO value of 8.7Vmfor the analcime framework of sample SAY-104 is in excellent agreementwith results of Luhr and Kyser (1989) after allowance for differencein SMOW standards(see note in Table 2). O and H isotope ratios for the analcime channel water are given in the last footnote in Table 2. Isotopic ratios of channel lvater were also reported by Luhr and Kyser (1989) for this same sample. Although our dD value, - l08%m,agrees well with the value, - I 197m,obtained by Luhr and Kyser (1989), our 6180.-value, -13 + 0.39* (lo) is considerably higher than theirs, -26 + lVu (lo) (Fig. 2). This discrepancyin 6'80"* values is far outside the analytical errors and must stem from diferences in sample dehydration. We consider our value for D'8O.*to be more appropriate than Luhr and Kyser's since the SAY- 104 sample analyzedby Luhr and Kyser (1989) behaved somewhatunusually compared to other analcimesin that most of the channel water degassedabruptly at 400-450 'C instead ofbetween 300 and 350'C (J.F. Luhr, personal communication, 1989).This suggeststhat Luhr and Kyser (1989) heated their sample too fast inducing O isotope exchange between the channel water and framework. In our experimentsmost of the channelwater degassedgrad- ually between 150 and 300 rc (Karlsson, 1988).The isotopic composition of channel water is close to the meteoric water line as has been observed for other analcime samples as shown in Figure 2 {Karlsson, 1988; Luhr and Ky- ser, 1989; Karlsson and Clayton, 1990a), and our measured DtsO* value is in good agr€ement with a value calculated through mass balance from measured hydrated and dehydratedanalcime SAY-104 (Karlsson, 1988).Ac- cording to Luhr and Kyser (1989) the 6'tO oflocal ground water at Colima is -8.57oo.Based on experimentally determined partitioning of O isotopes between analcime channel water and bulk water in the temperature range 25-400 'C, channel water in analcime is depleted in '8O relative to bulk water by a constant value of -57o essen- tially independent of temperatrue (Karlsson et al., 1988; Karlsson and Clayton, 1990b).Hence, ifthe channelwater Fig. 3. Microphotographs of Colima minette SAY-104. (a) is in isotopic equilibrium with the local ground water it Backscattered-electronimage. Microphenocrysts of analcime (an) should have a value of -13.5V-, in excellent agreement and augite (cpx) along with apatite (a) and titanomagnetite (m) with D'EO*value observed in this study. groundmass glass (gl). in a of Note that major fractures appear N isotopesand concentration.Sample SAY-104 has 6.0 to radiate from analcime grains (expansion cracks?). (b) Back- + 0.3 ppm N, and a 6'sN value of 3.4 + 0. l7-. The N' scatteied-electron image. Close-up of an analcime micropheno- i5 higher than that of midocean ridge cryst (an). (c) X-ray elemental map. Concentration of K in the content significantly same region shown in b. K is most concentrated in glass (7 wt%) basalts (MORBs) and the 6'5N value is somewhat lower whereas little K occurs in the analcime (0.3 wt%). K is eveoly (Fig. a). distributed throughout glass and zoning is absent. Similar results Ion microprobe.The resultsof ion microprobe analyses were obtained on a large scale and for Na. Precision + 0.5 wt%. of four analcime samples,three glasses,two augites,and one olivine in sample SAY-104 are shown in Tables 3- KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME 195

Taete2. Compilation of d18Ovalues of rocks and mineralsfrom the Colima volcanic complex

6"0 (V*) relativeto SMOW' Rock type Sample grm phlog Source leucite basanite SAY.5A 5.2 basanite 510 5.7 5.5 5.0 ; basanite s00 6.1 5.6 4.8 5.4 t minette 8H 5.3 4.9 5.0 5.5 t minette 7E 6.4 6.2 5.2 6.1 6.0 t minette sAY-104 7.6 8.7t This work

Note.'The 6'80 values obtained from others have been lowered by 0.59- in order to readjust their numbers to an c(COr-HrOlol 1.O4O7used in this study. t Abbreviations:wr : whole rock, grm : groundmass,ol : olivine,cpx : clinopyroxene,an - analcime,phlog : phlogopite. Precisionof analysis + O.2Va. -- Analysis of T.K. Kyser. J.F. Luhr (personalcommunication 1989). f Analysesby T.K. Kyserand J.R. O'Neil.From Luhr and Carmichaet(1981). + Framework. lsotopic measurementson the same channelwater sample yield 5teg* : - l! + 0.3Vaand dD : -108 + 37-.

5. Olivine and pyroxene were analyzed in order to mea- (1990a) and Chiba et al. (1989). Karlsson and Clayton sure background concentration of HrO and in order to (1990b) showedthat analcime-HrO fractionation curve is investigatethe partitioning of trace elementsamong var- similar to that of calcite-HrO. Assuming that analcime ious phasesin sample SAY-104 (Table 5). Electron mi- was in equilibrium with pyroxene with 6'80 of 6.lVu (ta- croprobe analysesof the analcime and the glassfrom Luhr ble 2) and given that the calcite-diopside fractionation and Kyser (1989) are included for comparison. Given the (Chiba et al., 1989) is l.4V- at magmatic temperatures limitations of the standardsfor the ion probe, the agree- (1300 K), the analcime should have framework D'8O: ment betweenmajor element concentrationsas obtained 7.S%u.Theobserved framework DrEOvalue,8.7Vu (Fig. l), with the electron probe is satisfactory. is somewhat higher than the 7.5E@value, suggestingthat Ion microprobe analysis of the glassyields HrO con- the analcime has either undergone subsolidus exchange tents ranging from 2.9 to 4.3 wto/o(Table 4). The HrO or formed from a preexisting igneous mineral such as values are consideredreliable to +500/oor better. Minor leucite. As in the case of Crowsnest, evidence for low- and trace elements are in good agreementexcept for Sr temperature water-rock interaction can also be found in and Cl where the electron microprobe values are higher. sampleSAY-104. Li was not detected in either glass or minerals. Small Both the concentrationand isotopic composition ofN, amounts of B in the glass(-30 ppm) and in the analcime in sample SAY-104 are indicative of interaction with wa- (-15 ppm) are most likely contamination introduced ter. Recently,Thanget al. (1987) andZhangand Clayton during the sample preparation. Rb is concentratedin the (1988) showed that the content and isotopic ratios of N, analcime (189 ppm) relative to other phases(Rb - 82 in igreous rocks can be a useful indicator of water-rock ppm in the glassand not detectedin olivine and augite). interaction. Mantle-derived rocks such as MORB typi- Sr, F, and Cl are strongly enriched in the glass(Sr: 3600 cally contain small amounts of N, (<1 ppm) and their ppm; F : 4100 ppm; Cl : 700 ppm) relative to other 6'5N (relative to AIR) values range from 7 to -ll1Vm phases(s310 ppm). (Zhang, 1988). Any subsequentinteraction with atmo- Electron microprobe.Results of the back-scatteredim- spheric N, (Dr5N: 0.0E*) through contact with water or aging and elemental mapping are shown in Figure 3. assimilation of Nr-rich sediments will therefore result in Analcime crystalsstand out in the BSEphotomicrographs an increase in the N, content and a lowering of the drsN becauseof their low mean atomic weight relative to other value. The high concentration of N2 indicates substantial phasespresent (Figs. 3a, 3b). The X-ray map reveals no interaction with a Nr-rich source (Fig. a). There are three significant zonation in Na and K either in the glassor in possible N, sources.First, N, could have been added to the analcime. the rock at the source region by fusion of Nr-rich sediments on top of the subducted Cocos plate. Second,N, could have been introduced into the magma during its Discussion ascent to the surface from its source region by interaction The 6180and DDvalues (- l3Vu, -108V*) of the anal- with waters or assimilation ofNr-rich country rocks. Third, cime channel water fall close to the meteoric water line N, could have been incorporated into the rock after ex- and well outside the range of magmatic water composi- trusion during hydration of the glass. Posteruption hy- tions (Craig, 1961), indicating that the channel water is dration ofthe glassis supported by the increasedwhole- ofmeteoric origin and almost certainly not magmatic (Fig. rock D'8Ovalue reliativeto the basanites,leucite basanite, 2). It is possible to estimate what the framework d'8O of and other minettes (Table 2). Such increasesin 6'80 val- analcime SAY-104 as a primary igneousmineral should ues have commonly been observed for rocks undergoing be by combining the results of Karlsson and Clayton hydration (see,e.g., Muehlenbachs, 1987). Sample SAY- 196 KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME

ue would have been lowered rather than increased.Ifthe posteruption hydration hypothesis is correct then a considerable amount of HrO must have entered the glass while leaving no visible trace of alteration. In fact, the glass in sample SAY-104 contains an unusually high amount of HrO, 4 wto/o(Table 4), which supports a posteruption hypothesis. Unfortunately, data on HrO solubilities in phonolitic melts are scanty and none have been obtained at I 100 "C. There is only a single low-temperature measurementby Dingwell et al. (1984). They found that a synthetic phonolite can incor- porate up to 5 wto/oHrO at I kbar and 800'C. Since the solubility of HrO in melts generally decreaseswith in- creasing temperature (Burnham and Jahns, 1962; Mc- Millan and Holloway, 1987), it seemsreasonable to as- sume that pressureshigher than I kbar are needed to dissolve 4 wto/oin phonolitic melts at I100 "C. By comparison it would require pressuresin excessof 1.5 kbar o24681012 to dissolve the same amount of HrO in a basaltic melt at 1100 "C (Burnham and Jahns, 1962; Hamllton et al., Nitrogen(ppm) 1964). Although some HrO must have been present in Fig. 4. Relationshipbetween 615N and N, concentrationin the magma, as is evidenced by the existenceof hydrous Colima sampleSAY-104. MORB is averagemid oceanridge igneous minerals such as phlogopite, the bulk of HrO in basalt.The figuresuggests that sampleSAY-104 has interacted sample SAY-104 must have been added after the erup- with a Nr-rich and dtsNJowsource such as water,sediments, or tion, otherwise the eruptive mode would have been ex- (adapted both from Zhang,1988). plosive rather than eftrsive. In conclusion, the whole-rock N, O isotope data and 104 has sufferedsome loss of olivine crystals (Luhr and the HrO content of the glasscollectively suggestthat mi- Carmichael, l98l). However, removal of olivine from nette sample SAY-104 has interacted \Mith water at one the minettes cannot account for the observed D'8Oen- stageor another in its posteruptive history and that the richment of 1.2-2.3Vm,since the difference between the analcime is secondary.The most likely precursormineral 6'80 of the olivine (mean: +5)8@) and the groundmass is leucite as this phase is present in nearby leucite bas- d'8O (mean: +5.68@)is small. Addition of HrO directly anites. Both rock types have very similar compositions into the magma is also unlikely; sinceground watersnor- and mineralogies.Leucite in the basanitesis petrograph- mally have negatived'8O values, the whole-rock d'EOval- ically indistinguishable from analcime in the minettes.

TABLE3. Results of ion microprobe analysis of analcimein sample SAY-104

IMPA-

Oxide (wt7") !1o U.o n.d.l n.d. n.d. n.d. Bro" <0.0003 <0.0007 <0.00044 0.0005 0.0002 Naro 12.2 12.1 11.7 12.0 0.26 12.40 Mgo 0.026 0.03it 0.037 0.032 0.006 Alro3 19.9 20.0 20.1 20.0 0.1 21.59 sio, 57.7 57.3 57.7 57.57 o.23 s5.66 KrO 0.523 0.473 0.457 0.49 0.03 0.30 CaO 0.161 0.226 o.2't3 0.200 0.03 o.23 Tio, 0.183 0.157 0.146 0.162 0.019 MnO 0.029 0.021 0.027 0.026 0.0042 FeO 0.9 0.8 o.74 0.81 0.08 1.17+ Rbro n.d. n.d. 0.0189 0.0189 SrO n.d. n.d. 0.031 0.031 0.12 Total 91.3it 91.48 F <0.0007 0.0026 <0.0005 <0.0072 0.0119 0.00 cl <0.011 <0.022 n.d. <0.015 0.006 0.00 H.o$ 8.66 8.52 * lon microprobe analysis. For experimentalcuditions see text. .- Electron microprobe analysis by Luhr and Carmichael(1981) who also reported BaO content of 0.01 wt%. f n.d. : not detect€d. { FeO as Fe.O". $ By difierence. KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME t97

Tlele 4. Results of ion microprobe analysis of glass in sample SAY-104

IMPA' Oxide (wt%) X1o

LirO n.d.f n.d. n.d. BrO" <0.0031

Such similarities, especiallyin the mode of occuffenceof The leucite-analcime transformation is accompanied by leucite and analcime, seem highly fortuitous if the melts a l0o/ovolume increase. If the mineral transformation that generatedthese rocks differed only in their H'O con- occurred after the glasshad solidified, as has been main- tents, but would be expectedif the analcime formed from tained here, then some expansion cracks could have re- the leucite. The transformation ofleucite to analcime must sulted. Although Figure 3 shows that cracks are indeed have occurred at some stageduring cooling of the lava presentin sample SAY-104, it remains to be determined flow after eruption. The question is when and how the whether they could have resulted from such an expan- hydration of the glassfits into this scheme.Since glassis sion. If the leucite was transformed to analcimein sample present,the lava must have cooled rapidly. However, this SAY-104 it must have done so without leaving obvious does not imply that the lava temperature fell abruptly remnants of the preexisting leucite or marked traces of from -1100 'C to ambient temperature, but only that K- or Na-zoning in the glass(Figs. 3b, 3c). the temperature dropped sharply below the transition The two most serious objections that can be raised to point of the glass.Hence, the lava may have first cooled rapidly by several hundred degreesand then cooled at a slower rate. Thus, there could have been sufficient time Tlele 5. Resultsof ion microprobeanalysis of olivineand py- to allow the leucite-analcime transformation to go to roxenein sampleSAY-I04 (197 completion. Taylor and MacKenzie 5) demonstrated Pyroxene experimentally that this transformation can occur upon Oxide cooling. They held chargesof the appropriate composi- (wto/o) tions such that leucite was stable in the Ne-Ks-Si system Li,O n.d.* n.d. n.d. for number of hours. B.o" n.d. n.d. n.d. aL2kbar Prroand 840 "C a specified Naro 0.o2 o.44 0.15 Subsequentlythe sampleswere cooled to room temper- Mgo 39.1 12.5 16.4 ature at varying rates. In all their experiments they ob- Alro3 0.03 5.86 1.48 sio, 4s.9 43.8 51.8 served glass and leucite in the products. Moreover, the KrO 0.02 0.17 0.02 leucite was in varying stagesof reactingto analcime.Tay- Cao 0.23 24.1 21.5 lor and MacKenzie (1975) noted that the exsolution rate Tio, o.02 1.88 o.71 MnO 0.29 0.18 0.20 was very fast and might ultimately lead to the generation FeO* 14.9 11.4 7.73 of analcime phenocrysts.However, such subsolidus RbrO n.d. n.d. n.d. probably did not SrO n.d. n.d. n.d. transformation of leucite into analcime Total 100.2 100.3 100.0 occur in minette SAY-104 since the scheme of Taylor F < 0.0006 <0.013 <0.0039 and MacKenzie (1975) requires a high initial concentra- ct < 0.0050 <0.0024 <0.0050 H"o <0.048 <0.36 <0.090 tion of HrO in the melt. It is more likely that the leucite- 'n.d. analcime transformation in SAY-104 and the hydration : not detected. " FeO as Fe2Os. of the glasswere contemporaneous. 198 KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME

the hypothesis of post-hydration transformation of leu- Barrer, R.M. (1978) Zeolitesand clay minerals as sorbentsand molecular cite to analcime are the apparent freshnessof the glass sieves,497 p. Acadernic Press,New York. and the survival of leucite in the leucite basanites.As was Bigeleisen,J., Pearlman, M.J., and Prosser,H.C. (1952) Conversion of hydrogenic materials to hydrogen for isotopic analysis. Anall.tical discussedearlier, there are no visible signs of alteration Chemistry, 24, 1356-1357. in sample SAY-104 in either the primary minerals or the Burnham, C.W., and Jahns, R.H. (1962) A method for determining the glass.However, hydration and increasesin 6'80 in vol- solubility ofwater in silicate melts. American Journal ofScience, 274, canic glassescan occur with no petrographically detect- 902-940. Chiba, H., Chacko,T., Clalton, R.N., and (1989) able alteration(see, e.g., Kyser et al., 1986and Muehlen- Goldsmith, J.R. Oxygen isotope fractionations involving diopside, forsterite, magnetite and cal- bachs,1987). cite: Application to geothermometry. Geochimica et Cosmochimica A second objection involves survival of leucite in the Acta. 53. 2985-2995. leucite basanites.A possible explanation is that the leu- Church, B.N. (1978)Shackanite and relatedanalcite-bearing lavas in Brit- cite basanitesunderwent lessposteruption hydration than ish Columbia. Canadian Journal ofEarth Sciences,15,1669-1672. Church, B.N. (l 979) Shackaniteand relatedanalcite-bearing lavas in Brit- the minettes. A whole-rock wet chemical analysis (see ish Columbia: Reply. Canadian Joumal ofEarth Sciences,16, 1229- Table 3 in Luhr and Carmichael,l98l) and the low whole- t302. rock D'8Ovalue of leucite-basaniteSAY-5A both suggest Clalton, R.N., and Mayeda, T.K. (1963) The use of bromine pentafluo- negligible hydration (Table 2). Modal analysis by Luhr ride in the extraction ofoxygen from oxides and silicates for isotopic analysis.Geochimica (1980)and Luhr and Carmichael(1981) et Cosmochimica Acta, 27, 43-52. revealedthat the Comin-Chiaramonti, P., Meriani, P., Mosca, R., and Sinigoi, S. (1979) leucite basanitescontain little or no glassin their ground- On the occurrence ofanalcime in the northeastern Azarbaijan volcanics masswhile at leasthalf of the minettes contain glass.The (northwesternIran). Lithos, 12, 187-198. differencein the hydration levels ofthe leucite basanites Coombs, D.S., and Whetten, J.T. (1967) Composition of analcime from may thus stem from the amount of glasspresent. A leu- sedimentary and burial metamorphic rocks. Geological Society of America Bulletin 78, 264-282. glass cite enclosedin hydrous is presumably much more Craig, H. (1957) Isotopic standards for carbon and oxygen and correction readily transformed into analcime than a leucite located factors for mass-spectrometric analysis of carbon dioxide. Geochimica in holocrystalline matrix of ferromagnesian minerals, et Cosmochimica Acta, 12, 133-149. principally becausethe raw material necessaryto com- Craig, H. (1961) Isotopic variations in meteoric waters. Science, 133, t702-1703. plete the leucite-analcimetransformation is more readily Cundari, A. (1973) Petrology of the leucite-bearinglavas in New South available in a glassthan in a holocrystalline matrix. Fur- Wales. Journal of the Geological Society of Australia, 20, 465-492. ther studies of the leucite-analcime transformation are Daly, R.A. (1912) The geologyof the North Arnerican Cordillera ar the neededin order to clarify the transformation process. forty-ninth parallel. GeologicalSurvey ofCanada Memoir 3E, l-857. Dingwell, D.B., Harris, D.M., and Scarfe,C.M. (1984) The solubility of HrO in melts CoNcr-usroNs of the system SiOr-Al,Or-Na.O-KrO at I to 2 kbars. Journal of Geology, 92, 387-395. Our results show that the Crowsnestand Colima anal- Edgar,A.D. (1979) Shackaniteand related analcite-bearinglavas in Brit- cime sampleshave either undergonesubsolidus O isoto- ish Columbia: Discussion. Canadian Joumal of Earth Sciences,16, 1298- 1299. pic exchangeor formed from preexisting leucite crystals. Ferguson,L.J. (1977) Petrogenesisofthe analcime-bearingand associated Evidence exists for low-temperature water-rock interac- volcanic rocks of the CrowsnestPass area, Alberta. M.Sc. thesis,Uni- tion in analcime-bearing rocks from both locales. At versity of Western Ontario, Ontario- Crowsnest,primary igneous6t8O values of some sanidine Ferguson,L.J., and Edg;arA.D. (1978) The petrogenesisand origin ofthe analcime in volcanic phenocrysts have been perturbed. At Colima, minette the rocks of the Crowsnest Formation, Alberta. Canadian Journal of Earth Sciences. 15. 69-77 . SAY-104 has an elevatedwhole-rock dr8Ovalue com- Gupta, A.K., and Fyfe, W.S. (1975) kucite survival: The alteration to pared to associatedbasanites and leucite basanitesand a analcime. Canadian Mineralogist, 13, 361-363. high whole-rock N, content coupledwith a low 6rsNvalue Hamilton, D.L., Burnham, C.W., and Osborn, E.F. (1964) The solubility compared to MORB. Its glassis unusually rich in HrO. of water and effects of oxygen fugacity and lvater content on the crys- raflization in mafic magmas.Journal of Petrology, 5, 21-39. AcrNowr,rncvrnNrs Hay, R.L. (1986) Geologic occurence of zeolites and some associated minerals. Pure and Applied Chemistry,58, 1319-1342. This work was a portion ofthe senior author's Ph.D. dissertation and Heatherington, A., Bowering, S.A., and Luhr, J. (1987) Petrogenesisof was funded by NSF grant EAR-8616255 to R.N. Clayton. We are in- calc-alkaline and alkaline volcanics from the western Mexican volcanic debted to James F. Luhr (SAY-104), Thomas H. Pearce(pN-39E), and belt-Pb isotopes. Geological Society of America Abstracts with Pro- Alan D. Edgar (2a, I e, WR- I , WR- I I ) for donation of samples. Luhr also grarn,19, 698. generously supplied unpublished whole-rock O isotope data for SAy-5A. Henderson, C.M.B. (1984) Feldspathoid stabilities and phase inver- N isotope and ion microprobe analyses were generously provided by Da- sions-a review. In W.L. Brown, F-d.,Feldspars and feldspathoids,p. chun Zhang and Richard Hinton, respectively, at the University of Chi- 47 1- 499. Reidel, Dordrecht. cago. We are grateful to Toshiko K. Mayeda, who performed the O iso- Karlsson, H.R. (1988) Oxygen and hydrogen isotopegeochemistry ofze- tope analyses of the Crowsnest feldspars and to Andrew M, Davis, for his olites, 288 p. Ph.D. thesis,University ofChicago, Chicago. help with the electron microprobe work. Discussions with John R. Beckett Karlsson,H.R., and Clayton, R.N. (1990a)Oxygen and hydrogenisotope and rewiews by Jarnes F. Luhr and an anonymous reviewer greatly im- geochemistry of zeolites. Geochimica et Cosmochimica Acta,54, 1369- proved the manuscript. l 386. Karlsson, H.R., and Clayton, R.N. (1990b) Oxygenisotope fractionation Rnr,nnrxcBs crrED between analcime and water: An experimental study. Geochimica et CosmochimicaActa, 54, 1359-1368. Barberi, M., and Penta,A. (1984) Relationship betweenlithium content Karlsson, H.R., Clayton, R.N., and Mayeda, T.K. (1985) Analcime-a and genesis of analcime in some sedimentary rocks. Chemie der Erde, potential geothermometer?Geological Society of America Abstract with 43, 197-203. Program, 17, 622. KARLSSON AND CLAYTON: PRIMARY OR SECONDARY ANALCIME 199

Karlsson, H.R., Clayton, R.N., and Mayeda, T.L (1988) Fractionation Pearce,T.H. (1970) The analcite-bearingvolcanic rocks ofthe Crowsnest and kinetics of oxygen isotope exchange between analcime and water Formation, Alberta. Canadian Journal ofEarth Sciences,7,46-66. (abs.).Eos, 69, 527. Peteru,T., Luth, W.C., and Tuttle, D.F. (1966) The melting of analcime Keith, T.E.C., Thompson, J.M., and Mays, R. (19E3) Selectiveconcen- solid solutions in the system N&{lSiO.-NaAlSirOs-HrO. American tration of cesium in analcime during hydrothermal alteration, Yellow- Mineralogist, 51, 736-7 5t. stone National Park, Wyoming. Geochimica et Cosmochimica Acta, Prisson,L.V. (1915) The Crowsnestvolcanics. Ameriean Joumal of Sci- 47,795-804. ence.39. 222-221. Kim, K.-I., and Burley, B.J. (1971) Phaseequilibria in the system Na- Roux, J., and Hamilton, D.L. (1976) Primary igneousanalcite-an ex- AlSirOs-NaAlSiOo-HrO with special ernphasis on the stability of anal- perimental study. Journal of Petrology, 17, 244-257. cire. Canadian Joumal of Earth Sciences,8, 3 I l-337. Saha, P. (1959) Geochemical and X-ray investigation ofnatural and syn- Kishima, N., and Sakai, H. (1980) Oxygen-lE and deuterium determi- thetic analcimes. American Mineralogist, 44, 30U313. nation on a single water sample of a few milligrams. Analyfical Chem- Saha, P. (1961) The system NaAlSiO" (nepheline)-NaAlsips (dbite)-H,O. istry, 52, 356-358. American Mineralogist, 46, 859-8E4. Knight, C.W. (1904) 661"i1"-,tuchyte tuffs and breccias from south-west Sheppard, S.M.F. (1986) Characterization and isotopic variations in nat- Alberta, Canada.Canadian Record of Science,9, 265-27E. ural waters. In J.W- Valley, H.P. Taylor, Jr., and J.R. O'Neil' Eds.' Kyser, T.K., Cameron,W.E., and Nisbet, E.G. 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