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Li Distribution Between Chlorite and Albite in a Common Vapor Phase

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Li Distribution Between Chlorite and Albite in a Common Vapor Phase LI DISTRIBUTION BETWEEN CHlORITE AND ALBITE IN A COMMON VAPOR PHASE By PE.TER VIlKS t B•SC • A Thesis i , - / Submitted to the School of Graduate Studies in Partial Fulfilment of the Requirements for the J;)egree Maste~ of Science • McMaster University March 1981 MASTER OF SCIENCE (1981) McMASTER UNIVERSITY " (Geology) Hamilton, Ontario . TITLE: Li.Distribution between Chlorite and Albite in a Common Vapor Phase AUTHOR: Peter Vilks, B.Sc. (Dalhousie University) .. SUPERVISOR: Denis M. Shaw NUMBER OF PAGES: i-x, 1-95 • ii A·,BSTRACT This stooy a.ttempted to examine the process of L1 enrichment in spilites by testing the hypothesis that 1i is concentrated in meta- morphosed basa~ts,from hydrothermal solutions in the temperature ran~e \ ".! 0 400 to 700QC and at.a 1.5 kb pressure. Using a double-capsule technique I 1i was partitioned between albite and chlorite in a common vapor phase. These minerals were used since they are commonly found in the greenschist facies and chlerite is susJ;ected to be the main Li host. The chlorite (clinochlore) and albite were grown from synthetic gels. A few exper~ . ,- " L iments were also attempted with a 'natural albite and 'hatural Fe-chlorite• • 11 analysts was carried out by atomic absorption and neutron activation. A variation between temperature and the partition coefficient of 1i between albite and chlorite could not be resolved. Therefore, the average partition coefficlent from all synthetic experimen~s was Dalb-enl = 0.,56 :!: .06. The p::trtition coeft;icient in the natural system was not ,..J'-"" significantly higher, (na.lb-chl..= 0.81 ! .46).' Considerable doubt exists . as to the accuracy, of the vapor-mineral partition coefficients because of the poor Li mass balance. A range of ~ssible vapor-mineral distri­ butions was obtained: measured predicted from Li mass balance Dvap-alb 2.77 :!: 6.45 S.97:!: 7.99 Dvap..ehl 1.10 .! 2.31' 2.89 :!: 3.J4 iii The measured Li partition coefficients do not 'explain the behavior of Li in spilites because too much Li went into the albite, and vap,-chl the D' was not less than 1.00 so ~~t most hydrothermal waters do not contain enough Li to produce the observed enrichment in'spilites. Lithium may be precipitat:ed in spilites at lower temperatures or' pres- sures thari those in this study. I "J , ',' iv • ". ACKNOWLEIXiEMENTS \ \ ,. i I am very grateful to my supervisor, Dr. Denis Shaw, for Z introducing me to my thesis topic and for providing valuable guidance through out the project. I am also indebted to Dr.. Brian Burley for supervis~he hydrothermal synthesi~ and for making available the equipmen~of his experimental laboratory. .1I.. I would also like to thank Pat Fung for introducing.me to the laboratory hydrothermal. proceed~es. Dr. James Kramer provided me with a very useful insight into aqueous chemistry. I also appreciate {' the help, otto Mudroch gave me fe>r the EDAX analysis and I would like to thank Dan Thompson for a sample of chlorite from Whitefish Falls. Finally I would like to thank Gary Beakhouse for calmly acceptiDg the presence o~ hydrothermal bombs in his office• .. v -' 'I'ABLE OF CONTENTS Page CHAPrJt:;R I INTRODUCTION .1 I-I Introduction 1 i 1-2 Previous work on Li distribution. 2 1-3 Geochemistry of Li 4 1-4 Definitions 6 1-5 Measurement of distribution coefficients 10 CHAPTER II EXPERIMENTS AND, DATA PROCESSING 13 11-1 Experimental proceedure 13 II-2 Analytical errors 15 I II-:3 Experimental errors 20 11-4 Li mass balance and calculation of Li vapor concentrations 21 CHAPl'ER III DATA AND DATA EVALUATION 25 111-1 Was equilibrium achieved? 25 ' 111-2 Lithium distributions 29 111-), Analytical uncertainty ,and variation,of Dalb-chl 43 I1I~ Location of 'lithium in the mineral phases 46 CHAPl'ER IV CONCLUSIONS 49 IV-l Statement on measured Li distributions 49 IV-2 Comparison to published Li distributions between vapor and minerals 50 IV-3 Comparison. to Li. concentration'in natural chlorite and albite 52 ·IV::l}--Alternate mechanisms of Li enrichment in spilites :A- vi Page ~ CHAPI'ER A APPENDIX .56 A-I Experimental proceedure .56 A-2 Preparation of"gels and Li standard gels 60 A-J P.roceedures with atomic absorption 62 A-4 Alpha track Li 'analysis. 64 ~~. A-5 Natural chlorite and albite 72 A-6 Lithium concentrations in the vapor phase and lithium vapor-mineral distributions 74 ( A-7 NatUre af tl)e vapor ~hase in equilibrium with the minerals 77 '( ! -.. C'" .< \ ~ .. vii I / Llsr OF TABLES Page TABLE I-I Properties of Li, Na, K, Rb, Cs, and Mg 5 II-I International reference samples .16 II-2 Li det~ction limits with atomic a~sorption 17 II-J Li detection limits wi~h activation analysis 19 n-4 Li mass balance and vapor composition 23' III-l Diffractograms of albite and chlorite grown from the same gel 26 0 III-2 Av~~e ~istribution coefficient, at 500 C 29 III-3 Lithium distributions, )0 III-4" Average Li distributions 32 I,II-5 T stati&tio for two means J3 IV-l Li/K exhhange isotherms be~ween sanidine and muscovite and sanidine and ph1ogopite 50 A-I Gold tubing and pressure vessels 56 A-2 Materials used in gel preparation 60 A-3 Lithium-gel standards 62 " A.:J+ Alpha counts of Li standards and calibration line regression coefficients 69 A-5 Alpha counts per area.. and Li concentrations 70 ,A-6 .. Measured Li in Ab-l and chlorite from Whitefish Falls 72 A-7 Analysis o~ chlorite from Whitefish Falls using' the energy dispersive system (EDAX) on the electron I microscope .' 73 ~. , . vi'ii Page A~ X-ray diffraction study on Ab-l and Fe-chlorites 7) A-9 Li concentrations in vapor and vapor-mineral Li distributions calculated from measured and ¥ . predicted Li amounts in the yapor· i 75 A-IO Averaged vapor-mineral partition coefficients 77 A-II Mg, Fe, Al and Na analysis of international reference samples 78 A-12 Molalities of major cations in vapor 80 ) A-I) Reactions shown in figure A-) 8) A-14 Activity coe~ficients and activi~y ratios 86 A-15 Variations-of activity ratios with temperature 90 Q , ~• ix , " Q LIST OF FIGURES Page FIGURE I-I Li/K exchange isotherms between sanidine and muscovite and a vapor at 600o C and 1 kb. I-Z Li/K exchange isotherm between sanidine and 0 '\ muscovite at 600 and 1 kb. 3 1-3 Li/K exchange isotherm between vapor and phlogopite 0 at 600 C and 1 kb. 3 11-1 Cali',,!ation line-for sample group P 18- III-l Individual lithium partition coefficients betwe~n o ' albite and chlorite at 500 C ¥ersus time 27 0 III-Z Li in albite versus Li in chlorite at 400 C 35 0 1II-3 Li in albite v~~ 11 in chlorite at 500 C J6 '-c 0 1II4 L1 in albite versus Li in chlorite at 600 C 37 111-5 Li in albite versus Li in ~hlorite at 7qoO C 38 1II-6 Li in albite versus,Li in chlorite at all temperatures 39 1II-7 Li in albite versus Li -in chlorite in the natural system 40 111-8 Li partition coefficfent between albite and.chlorite • 1 . versus.1onic ~rength of the vapor ~ 1V-l Li/K parti~!fp_coefficient betwee~ vapor and minerals versus the Li/K ratio in the'vapor 51 A-I Selected calibration curves relating alpha C. counts to ppm L1 68 A-:) Activity diagram in the, system Na 0-MgO-Al 0 - z z 3 SiOz-HzO' 88 '1 , I '.1.' \ I / \ \X, ',' , , .. .. CHAPl'ER I e_' INTRODUCTION I-I Purpose of the study Shaw et. a1. (1977) have shown that ~pilitised basalts contain more Li ( average::: 75 ppn ) than fresh basalts ( averag~ ::: 12 ppn ). 'Lithium was show!V,to increase with weight percent ,H 0 and ( 2 "', with a decrease i~ the ratio caO/A1 0 . Since H 0 increases and CC?-0 2 3 2 decreases wtth spilitisation' of basalts Shaw et. a1. (1977) sugge!3t chara~teristic that Li increase is .,;.. of spilitization• Shaw et. al. (1977) predicted the Li/Na ~tio of the fluid~ which produce spilitisation. These predictions were limited because r ' the mechanism of Li uptake in spilites is not clearly understood~ Floyd (1977) indicated that Li was enriched in chlorite-rich p;l..tphes. Unpublished. ion probe data of J. V. Smith also show that ti is c.on­ centrated in chlorite. The purpose of this study is to improve our understanding of Li behavior during spilitisation. Two essent\al secondary minerals. :'(1,) in spilites are chlorite and albite. Therefor'e, this study wili try to determine the distribution of Li between these two minerals" in a cOlllJl1on vapor phase. This ~ould'demonstrate 'whether' or not Li prefers to enter chlorite. The Li/Na'raj;.io <?f. t~e hYdrotbermal fluid and the. effect' of' temperature will also be st~led. I .. 2 In summary, this study will test ~he hypothesis that Li distribution be~ween albite and chlorite in a common, vapor phase at 400 to 700°· C ?llq 1.5 kb can explain 11 u~ake in spilitised ~salts. '\ ~2 Previous work on Li distribution Volfinger (1970) measured Li and K exchange between mus­ covite and vapor, and sanidine an~" vapor at 600° C and 1 kb. !'1uscovite - '\, might be considered as a mica analogue to. chlorite, and sanidine as an analogue to albite. The.
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