a simple method for the precise determination of -40 trace elements

8/10/2019 A Simple Method for the Precise Determination of -40 Trace Elements

1/16

n Zi-ELS EV IER Chemica l Geology 134 (1997) 311-326

C H E M I C LG E O L O G Y

IN LUDING

ISOTOPE GEOSCIENCE

A sim ple m ethod for the precise determination of > 40 traceelements in geological samples by ICPMS using enriched isotope

internal standardisation

S.M . Eggin s *'1, J.D. W ood hea d 2, L.P.J. K insley, G.E. Mortim er, P. Sylves ter,M .T. McC ulloch, J.M. Hergt 3, M .R. Hand ler

Research School of Earth Sciences Australian National University Canberra A.C.T. 0200 Australia

Received 9 A ugust 1995; accepted 22 June 1996

A b s t r a c t

Th e co mb i n a t i o n o f en r i ch ed i so t o p es an d co n v en t i o n a l e l emen t a l in t e rn a l s tan d a rd s p e rmi t s t h e p rec i se d e t e rmi n a t io n> 4 0 t race e lemen t s b y ICPM S i n a b ro ad sp ec t ru m o f g eo l o g i ca l ma t ri x e s . En r i ch ed i so t o p es ex p an d t h e su i t e o f av a i l are fe ren ce i so t o p es sp aced t h ro u g h t h e mass sp ec t ru m, so t h a t t h e co mp l ex mass -d ep en d en t v a r i a t i o n s i n sen s i t i ven co u n t e red d u r in g ICPM S an a l y s i s c an b e m o n i t o red an d d eco n v o l v ed . Th e m e t h o d we h av e d ev e l o p ed i s s t ra ig h t fo rwen t a i li n g s i mp l e samp l e p rep a ra t i o n , i n s t ru men t ca l i b ra t i o n , an d d a t a red u c t i o n p ro ced u re s , a s we l l a s p ro v i d i n g ex t ene l emen t co v e rag e , i mp ro v ed p rec i s i o n , an d b o t h t i me an d co s t b en e f i t s co mp ared t o a l t e rn a t i v e an a l y t i ca l s t ra t eg iAn a l y t i ca l p rec i s i o n n ear o r b e t t e r t h an 1 % RS D ( re l a ti v e s tan d a rd d ev i at i o n ) i s a ch i ev ed fo r mo s t d e me n t s wi t h mass >amu an d b e t ween 1 % an d 4 % (RS D) fo r e l emen t s wi th mass < 8 0 amu , wh i l e ma i n t ai n i n g l o w d e t ec t i o n l i mi t s (< 1< 1 0 n g g - l fo r e l emen t s wi th mass > 8 0 amu an d < 1 0 n g g - i to 1 Ixg g - i fo r e l emen t s wi th mass < 8 0 amu ) . Thsu b t l e g eo ch em i ca l d i ffe ren ces wh i ch can b e re so l v ed u s in g t h i s me t h o d a re d emo n s t ra t ed b y an a l y se s o f Nb , Ta , Z r, an d i n mag mas f ro m o cean i s l an d s an d su b d u c t i o n zo nes . Th ese d a t a rev ea l s i g n if i can t d ep a r t u res f ro m ch o n d r i t i c Z r / H f aN b / T a v a l u es , an d sy s t ema t i c t r en d s wh i ch a re co n s i s t en t wi th g rea t e r i n co mp a t i b i l i t y o f Z r re l a t iv e to H f an d a l so o f re l a t i v e t o Ta d u r i n g m e l t i n g o f t h e u p p e r man t l e . Th e o ccu r ren ce o f s ig n i f i can tl y su b ch o n d r i ti c Z r / H f an d N b / T a ra t i oNb -p o o r su b d u c t i o n zo n e mag mas , su p p o r t s t h e n o t i o n t h a t t h e d ep l e t i o n o f h i g h - f i e l d s t ren g t h e l emen t s i n su b d u c tmag m as i s d u e t o t h e i r r emo v a l f ro m t h e m an t l e wed g e b y p r i o r me l t i n g ev en ts .

Keywords: Inductively coupled plasma m ethods; Mass spectrometry; Trace e leme nt analysis; Subdu ction zones; Par t ia l melt ing

I . I n t r o d u c t i o n

* Corresponding author.t Present address: DepaJament of Geology, Australian National

University, Canberra, A.C.T. 0200, Australia.2 Present address: School of E ar th Sciences, Universi ty of

Melbourne, Parkeville, Vic. 3052, Australia.3 Prese nt address: DepaJ:tment of Geology, Au stralian Nationa l

University, Canberra, A.C.T. 0200, Australia.

I C P M S ( i n d u c t i v e ly c o u p l e d p l a s m a m a s s s p e c -t r o m e t r y ) h a s r a p i d l y b e c o m e e s t a b l i s h e d a s a p r e -f e r r e d m e t h o d f o r t h e a n a l y s i s o f t r a c e e l e m e n t s i ng e o l o g i c a l s a m p l e s , o f f e r i n g r a p i d a n a l y s i s c a p a b i l i -t i es , a n a b i l i t y t o m e a s u r e m o s t e l e m e n t s , r e l a t i v e l ys t r a i g h t f o r w a r d s a m p l e p r e p a r a t i o n , v e r y l o w d e t e c -

0009-2541/97/$17.00 Copyright 1997 Elsevier Science B.V. All r ights reserved.PH S 0 0 0 9 - 2 5 4 1 ( 9 6 ) 0 0 1 0 0 - 3


2/16

312 S .M . E g g i n s e t a l. / Ch emi ca l Geo l o g y 1 3 4 1 9 9 7 ) 3 11 -3 2 6

t ion l imi ts , a large dynamic range, and largely in ter-feren ce-f ree spectra . How eve r, i t i s increas ing ly ap-p a ren t t h a t fu l ly qu an t i ta t iv e m easu rem e n t b y IC P M Scan b e co m p ro m ised b y v a r i a tio n in in s t ru m en t sen -s i t iv i ty dur ing the course o f an analy t ica l run andwith the in t roduct ion o f d i fferen t sample matr ixes .A ccu ra t e an d p rec i se d a ta m ay o n ly b e o b ta in ed i fth ese e f f ec t s can b e m in im ised o r, m o n i to red an dcorrected fo r.

The adverse effects o f sensi t iv i ty var ia t ions dur-in g IC P M S an a ly s i s can b e av o id ed o r m in im ised b yemploy ing e i ther s tandard add i t ion o r i so tope d i lu -tion (e.g., Jenner et al., 1990; Xie et al., 1994).H o w ev er, t h ese m e th o d s h av e d raw b ack s w h ichcompromise the inheren t capab i l i t ies o f ICPMS. Iso -tope d i lu t ion requ ires accurate ly p repared and main-ta ined enr iched iso tope sp ikes , and op t imal "sp ik -ing " o f ind iv idual samples . Fur the rmo re , it is limi tedto mul t i - i so tope e lements and , when app l ied to al a rg e n u m b e r o f e l em en t d e te rm in a tio n s , is ex p en s iv eand t ime consuming . S tandard add i t ion l ikewise re-qu i res p reparat ion o f accurate e lemental s tandardso lu t ions , employment o f op t imal sp ik ing s t ra teg ieson a sample by sample bas is , and the a l iquo t ing o fsample so lu t ions in o rder to conduct the mul t ip leanalyses necessary fo r analy te determinat ion .

Faced wi th the r igors o f s tandard add i t ion and

i so to p e d i lu t io n , m an y IC P MS lab o ra to r i e s h av e r e -so r ted to ex ternal ca l ib ra t ion (us ing e i ther syn thet ico r n a tu ral r e fe ren ce m a te r ia l s ) w i th in t e rn a l an d /o rex ternal s tandard isa t ion . These a l ternate s t ra teg iesoffer considerab le time, sam ple p reparat ion , and costb en ef i t s b u t u n t i l n o w h av e n o t d e l iv e red g o o d an a -ly t ica l rep roducab i l i ty due to the complex sensi t iv i tyvar ia t ions encoun tered dur ing analys is . The s t ra te-g ies em ploye d wi th mo st success to date include: (1 )the use o f mul t ip le e lemental in ternal s tandards(Thompson and Houk , 1987 ; Doher ty, 1989) ; (2 )

re la t ively shor t analy t ica l p rocedu re durat ion ; and (3 )ex ternal s tandard isa t ion based on mul t ip le repeats o fthe same so lu t ion run a t in tervals dur ing an analy t i -cal proce du re (e.g . , Cheath am et al. , 1993), or acom binat ion o f the above (e .g . , Schonberg , 1993).

I t shou ld be no ted that most ex is t ing mul t i -e le-ment ICPMS s tud ies on geo log ical samples fa l l wel lshor t o f the analy t ica l p recis ion capab i l i t ies o f mod-em IC P MS in s t ru m en t s . T h e ab i l i t y to m easu re i so -to p e ra t io s to a p rec i s io n o f ~ 0 .2 -0 .3 % R S D ( re l a -

t ive s tandard dev ia t ion) , shou ld t rans la te in to anab i li ty to rep roduce me asurem ents to + 1% or bet ter,g iven cumulat ive sample p reparat ion , analy t ica lmethodo logy, and coun t ing s ta t i s t ic er ro rs . Th is canbe compared to repor ted p recis ion usual ly in therange 3 - 5% RS D (Jenn er e t a l. , 1990; Cheatham etal., 1993; Sc ho nb erg , 1993; X ie et al., 1994), andso m et im es > 1 0% o r 2 0 % d esp i t e f av o u rab le co n -cen tra t ion levels .

H ere in w e d esc r ib e a s t r a ig h tfo rw ard m e th o d em -p loy ing ex ternal ca l ib ra t ion a long wi th a combina-t ion o f ex ternal s tandard isa t ion and mul t ip le in ternals tandard isa t ion , us ing bo th e lemental and enr ichediso tope in ternal s tandards . Improved p recis ion andex ten d ed e l em en t co v erag e (> 4 0 e l em en t s ) is a t -t a in ed c o m p ared to o th e r IC P M S an a ly ti ca l s tr a teg iesrep o r t ed to d a te . M o reo v er, b ecau se m ass -d ep en d en tvar ia t ions in ins t rum ent sensi t iv i ty are m oni to red andd eco n v o lv ed o n a sam p le b y sam p le b as is , t h e m e th o dis matr ix to leran t and does no t necess i ta te s t r ic tmatr ix -match ing p ro toco ls . I t has been app l ied suc-cess fu l ly to p e r id o t i te s , a sp ec t ru m o f m ag m a ty p esrang ing f rom komat i i te th rough basal t to rhyo l i te ,g ran i t ic samples , banded i ron fo rmat ions , and min-era l separates includ ing o l iv ine , pyroxene, sp inel ,fe ldspar, var ious ox ide phases , and apat i te .

2. Mass-dependent sensitivity variation duringICPM S analysis

In i t ia l exper ience wi th our ins t rument (F isonsPQ 2 + ) em ploy in g a s ing le in ternal s tandard (e le-mental In ) revealed an inab i l i ty to rep roduce deter-minat ions on the same sample wi th in analy t ica l er-ro r, even dur ing a s ing le analy t ica l run . The re la t ived i f f e ren ces b e tw een rep ea ted an a ly ses w ere fo u n d tob e a sy s t em at ic b u t o f t en co m p lex fu n c t io n o f m ass .

T h i s b eh av io u r i s sy m p to m at i c o f v a r i a t io n s o ccu r-r ing in ins t rument sensi t iv i ty as a funct ion o f masswi th t ime (F ig . 1 ) , and has been descr ibed in deta i lby Cheatham et a l . (1993) fo r the res t r ic ted massreg io n sp an n ed b y B a an d th e r a re -ea r th e l em en t s(R E E ) . We h av e fo u n d th a t t h e m ag n i tu d e an d co m -p lex i ty o f these sensi t iv i ty var ia t ions can be severew h ere th e an a ly sed i so to p es sp an th e en t i r e m asssp ec t ru m , p a r t i cu la r ly in th e lo w -m ass r eg io n (< 8 0amu) . In teres t ing ly, i t appears that th is p rob lem is


3/16

S.M. Eggins e t al . / Chemical Geology 134 1997) 311- 326 3 1 3

~ 1 .0-~

~ 0 .95

---~ 0.90O ~

Q .O0 0.85

0 .80._>

n 0.75,-

CO 0.70

. _ >- , , - - 0 6 5

r' 0.60

aU In tscnalS tsndards ~ S r R h In 47E;m Tm Re ~ ~ SU

" I

" O t ~ ~ ~ a g a ~ m o-t~ ...................................................................... .......... .............................................................

=.~................. -~ . -~ ' ............. ............................ . --~ ,~v -i ........................

i I 5 l i:_._;.._._._1._ . . . . ~ . ~ ............... ............................ . . . . . . . # 12I..:

~71 ~i ~: I # 191 :

- , ' , , U i - , , , , 'i . . . . i . . . . . . . . "50 100 150 2 0 0 2 5 0

a t o m i c m a s s u n i t s

F i g . 1 . R e l a t i v e s e n s i t iv i t y c h a n g e s f o r i n te r n a l s t a n d a r d a n d

a n a l y t e i s o t o p e s d u r i n g t h e c o u r s e o f a n a n a l y t i c a l r u n , b a s e d o nr e p e a t a n a l y s e s o f t h e s a m e s o l u t i o n a t i n t e r v a l s d u r i n g t h e r u n .# n d e n o t e s t h e a n a l y s i s n u m b e r o f e a c h r e p e a t m e a s u r e m e n tw i t h i n t h e a n a l y s i s s e q u e n c e . T h e c o n t i n u o u s l in e i s a l i n e a ri n t e r p o l a t i o n b e t w e e n i n t e r n a l s t a n d a r d i s o t o p e s f o r a n a l y s i s # 1 9 .T h i s c o m p a r e s t o t h edashed curve,w h i c h i s a c l o s e r a p p r o x i m a -t i o n t o t h e a c t u a l s e n s i t iv i t y c h a n g e s , p a r t i c u l a r l y i n th e l o w - m a s sr e g i o n b e t w e e n 6 L i a n d 8 4 S r .

t h e p r i n c i p a l l i m i t a t i o n t o q u a n t i t a t i v e a n a l y s i s o fm a n y l o w- m a s s e l eme . n ts r a th e r t h a n m o l e c u l a r i n t e r -f e r e n c e s .

G i v e n t h e c o m p l e x n a t u r e o f t h e s e n s i t iv i t y v a r ia -t ions i l lu s t r a ted in Fig . 1 , i t can be r ead i ly apprec i -a t e d t h a t t h e c o n v e n t i o n a l u s e o f a s i n g l e o r e v e ns e v e r a l e l e me n t a l i n t e r n a l s t a n d a r d s w i l l b e i n a d e -q u a t e t o mo n i t o r a n d d e c o n v o l v e t h e s e v a r i a t i o n sd u r i n g t h e c o u r s e o f a n a n a l y t ic a l r u n . I f i n t e rn a ls t a n d a r d i s a t i o n i s t o b e e f f e c t i v e i n s u c h c a s e s t h e nmu l t i p l e i n t e r n a l s t a n d a r d s , s p a c e d a t a p p r o p r i a t ei n t e r v a l s t h r o u g h t h e e n t ir e ma s s s p e c t r u m ( i. e . ~ 2 0mass un i t s apa r t ) , a re r equ i red . Th i s p re sen t s ani n s u r mo u n t a b l e d i f fi c u l t y f o r c o n v e n t i o n a l i n t e rn a l

s t a n d a r d i s a t i o n u s i n g mo d e r n h i g h - s e n s i t i v i t y i n s t r u -me n t s , a s e l e me n t a l i n t e r n a l s t a n d a r d s a r e l a rg e l yres t r i c t ed to u l t r a - t r ace e lemen ts ( e .g . , Rh , In , Re ,B i ) wh o s e n a t u r a l a b u n d a n c e s d o n o t c o n t r i b u t e s i g -n i f i c a n tl y ( i d e a l l y < 0 . 1 - 0 . 2 % ) t o a n y a d d e d i n t e r -na l s t anda rd .

En r i c h e d i s o t o p e s n o t o n l y e x p a n d t h e p o o l o fu s e a b l e i n t e r n a l s t a n d a r d s b u t e n a b l e t h e a b u n d a n c eo f t h e ir p a r e n t e l e me n t s t o b e d e t e r mi n e d . T h e u s e o fpa r t i cu la r en r i ched i so topes i s sub jec t to the i r pos i -

t ion and spac ing wi th in the mass r ange , s t ab i l i ty ind i lu te n i t r i c ac id so lu t ions , cos t , and the l imi ta t ionswh i c h t h e y c a n p l a c e o n t h e d y n a mi c r a n g e a n dd e t e c t i o n l i m i t s o f p a r e n t e l e me n t a n a l y t e i s o t o p e s .Th e l a t t e r is a p rod uc t o f the unce r ta in i t i e s a r i s ingf r o m s u b t r a c t i n g t h e n a t u r a l a n d e n r i c h e d i s o t o p ec o n t r i b u t io n s f r o m t h e i n t e rn a l s t a n d a r d a n d a n a l y t ei so topes , r e spec t ive ly.

Mul t ip le in te rna l s t anda rds a l so con t r ibu te to im-p r o v e d a n a l y t i c a l p r e c i s i o n b y o f f s e t t i n g t h e e f f e c t so f h i g h e r f r e q u e n c y n o i s e in I CPM S. Fo r e x a m p l e ,w i t h a ty p i c a l ma s s s p e c t r o me t e r s we e p t i m e o f 1 st o t r a v e r s e t h e ma s s s p e c t r u m, t e n u n i f o r ml y s p a c e din te rna l s tanda rd s wi l l acco un t fo r no i se o f < 10 H zwhereas a s ing le in te rna l s t anda rd wi l l be l imi ted to< 1 H z .

3 . A n a l y t i c a l t e c h n i q u e

3 1 Sample preparation and introduction

S a m p l e s a n d g e o c h e m i c a l r e f e r e n c e m a t e r ia l s a r ed i s s o l v e d b y c o n v e n t i o n a l d i g e s t i o n me t h o d s , u s i n gc o n c e n t ra t e d H F - H N O 3 m i x tu r e s ( 1 0 : 1) i n 2 5 - m lSa v i l l e x s c r e w- t o p Te f l o n b e a k e r s . Se v e r a l t ime s

d u r i n g t h e d i g e s t i o n , t h e b e a k e r s a r e p l a c e d i n a nu l t r a s o n i c b a t h i n o r d e r t o d i s a g g r e g a t e g r a n u l a rma t e r i a l a n d r e n d e r i t mo r e s u s c e p t i b l e t o a c i d a t -t a c k . I n t h e c a s e o f s a mp l e s c o n t a i n i n g r e s i s t a n tp h a s es , s u ch a s z i rc o n , m i c r o w a v e o r " b o m b " d i -g e s t i o n s a r e e mp l o y e d t o e n s u r e c o mp l e t e d i s s o l u -t i o n . Fo l l o wi n g d i g e s t i o n t h e s a mp l e s a r e e v a p o r a t e dt o i n c i p ie n t d r y n e s s , r e f l u x e d i n 6 N HN O 3 , t a k e na g a i n t o i n c i p i e n t d r y n e s s , a n d t h e s a mp l e c a k e t h e nd i s s o l v e d i n 2 m l o f c o n c e n t r a t e d H N O 3. F i n a l s a m -p l e p r e p a r a t i o n i s u n d e r t a k e n , f o l l o wi n g t r a n s f e r t o

1 2 5 -ml p o l y p r o p y l e n e b o tt l e s a n d a d d i t io n o f ak n o w n we i g h t o f i n t e rn a l s t a n d a r d s o l u ti o n , b y d i l u -t io n w i th u l tr a p u r e H 2 0 t o a s a m p l e / s o l u t i o n w e i g h tr a t io o f 1 : ~ 1 0 0 0 - 1 2 5 0 ( i .e . ~ 8 0 - 1 0 0 - r a g s a mp l ein 100 g o f fina l so lu t ion ) . T h i s d i lu t ion fa c to r i s ac o m p r o m i s e b e t w e e n s a m p l e - s iz e r e l a te d h e t e ro g e n e -i ty, e a s e o f d i g e st i o n , a v a i l a b i l i t y o f l a rg e v o l u me s o fc l e a n r e a g e n t s , r e q u i r e d d e t e c t i o n l i m i t s , a n d a n a l y t es u p p r e s s i o n e f f e c t s wh i c h c a n b e s e v e r e wh e r e t o t a ld i s s o l v e d s o l i d c o n t e n ts e x c e e d 0 . 2 %. A l l r e a g e n t s


4/16

314 S.M. Eggins et al. / Chemical Geology 134 1997) 311-326

Ta b le 1Internal s t a nda rd a nd a na ly te i s o tope s , i n t e r fe re nc e s , a nd in t e rna ls t a nda rd c onc e n t ra t ions

Ana ly te I s o tope S ign i f i c a n t in t e r fe re nc e s a 6 (n g / g )

In t. S td . 6Li 6 L i na tu r a l 7 10

L i 7 L i I n t . S t d .B e 9S c 4 5 C O O H ?Ti 4 9V 51C r 5 3C o 5 9Ni 60 44 CAO49C u 6 5 TiO , 4s TiOHSOZn 66 " r io , 49 TiOH I42G a 7 1 C e z + ,142Nd2+In t . S td . 84Sr 8484 Sr na tu r a l , s 4 Kr 16R b 8 5S r 8 6 S r I n t . S t d ., ~ K rY 89Zr 91N b 9 3M o 9 8Int . Std . Rh 103 n4 5C d 11 4 S nInt. Std. In 115 10Sn 120Sb 121Cs 133Ba 137La 139C e 140

Pr 141N d 146 147Int . Std . 147Sm 147 S m na tu ra l 149 10S m 1 4 9 S m I n t . S t d . 13 sEu 151 BaO and 134BaOH143Tb 159 Nd O 144Gd 160 SmO , 144NdO, 16097145Dy 161 Nd O 149H o 1 65 S m OEr 167 t51 Eul6 OI69

I n t. S t d. T m 1 6 9 T m n a t u r a l 1 0Y b 1 73 1 5 7 G d OLu 175 J59TbOH f 178 162DyOTa 181 ~65HoOInt . Std . Re 187 5T1 205P b 2 0 8Int . Std . Bi 209 10T h 2 3 2 235Int . Std . Z35U 235 U na tu ra l 23a 2 .5U 238 Uspike

Ta b le 1 (c on t inue d)

Ana ly te I s o tope S ign i f i c a n t in t e r fe re nc e s a (n g / g )

Other possible internal standards:

6J Ni 61 44 Ca OHt34Ba 134135Ba 1352a pb 204

a Bold typeface ind ic a te s c o r re c te d in t e r fe re nc e s .

are p repa red us ing dou b le-d is t i l led concen tra ted acidsa n d u l tr a p u r e w a t e r ( > 1 8 M I I ) .

S am p le in t ro d u c t io n to th e IC P MS i s au to m atedv ia a G i l so n A u to sam p le r a t a r a t e o f ~ 1 m l / m in - 1.The up take t ime is se t to fac i l i ta te s tab le analy tes ignals p r io r to analys is ( typ ical ly 90 -1 20 s). Aw ash o u t p ro ced u re in co rp o ra t in g a d i lu t e su r fac t an t( e .g . , ~ 0 .5 % T r i to n X -1 0 0 o r D E C O N ) an d su ff i -c ien t wash t ime is cr i t ica l to ach iev ing adequateins t rument b lank levels . A p rocedure appropr ia te fo rm o s t ap p l i ca tio n s in v o lv es a 6 0 -9 0 s su r fac t an t w ashan d a 1 8 0 s w ash w i th 2 % H N O 3. T h e to t al tim e fo ranalys is o f a s ing le sam ple so lu t ion i s ~ 10 -12 min ,r e su lt in g in ty p ica l ru n t im es o f b e tw een 3 an d 7 h rfo r th e an a lys i s o f 1 8 - 3 6 so lu tio n s , o f w h ich 1 2 -2 8are u n k n o w n s , 2 a re ca lib ra tio n so lu t io n s, 2 - 4 p ro ce -dural b lanks , and an ins t rument sensi t iv i ty moni to r-

in g so lu tio n w h ich i s r ep ea ted ev e ry 5 -7 so lu tio n s .To assu re lo w in s t ru m en t b l an k l ev e l s , p a r t i cu -

l a r ly fo r t h e an a ly si s o f l o w - lev e l co n cen t ra tio n s o fe l em en t s w h ich h av e p o o r w ash o u t ch a rac te r i s t i c s(e .g . , Nb and Ta) , p r io r analys is o f samples wi thh ig h co n cen t ra t io n l ev e l s o f su ch e l em en t s i s av o id ed .T h e sp ray ch am b er an d n eb u l i se r a re a l so c l ean edand rep laced regu lar ly a long wi th the sample in t ro -duct ion tub ing . Ex ternal ly lubr icated s i l icone tub ingi s em p lo y ed o n th e p e r i s t a lt i c p u m p in p re fe ren ce toTy g o n tu b in g , w h ich d ev e lo p s in t e rn a l c rack in g a f t e r

a sh o r t p e r io d o f u se . I t sh o u ld b e n o ted th a t m ea-su red r eag en t b l an k l ev e l s fo r m an y e l em en t s w i thpoor-washou t character is t ics are o f ten no t a t ruere f l ec tio n o f in s t ru m en t b l an k l ev e l s d u r in g th e in t ro -d u c t io n o f an a ly te so lu t io n s, a s t h ese e l em en t s can b em o re e f f i c i en t ly scav en g ed f ro m th e sam p le in t ro -d u c t io n s y s t e m t ha n b y " b l a n k " 2 % H N O 3 a c idsolutions (see also Xie et al . , 1994).


5/16

S.M. Eggins e t a l . / Chemical Geology 134 1997) 311- 326 315

3.2. Inte rna l standard ~

T h e e l em en ta l an d en r i ch ed i so to p es w e em p lo yfor in terna l standardi:sation are l isted in Tab le 1 ,a long w i th several o~Lers that we hav e iden t i f ied asbeing su i tab le . The enr iched iso topes we use arere la t ively inexpensive wi th the excep t ion o f 84Sr,th o u g h ev en w i th in c lu s io n o f th is i so to p e th e co s t o fin ternal s tandard isa t ion per sample i s on ly a minorf rac t io n o f th e to ta l co s t o f each an a ly s is ( ~ 1 U S $ ).

In conven t ional e lemental in ternal s tandard isa t ionth e n a tu ra l i so to p e ab u n d an ce n eed s to b e o v e r-w h e lm ed b y th e ad d ed in t e rn a l s t an d ard , t h o u g h insom e case s i t ca n be ., sub t racted f r om the in ternals tandard i so tope s ignal (e .g . , na tu ra l 169Tm evalu atedf ro m E r an d Y b co n cen t ra t io n s ) . Wi th en r i ch ed i so -tope in ternal s tandard isa t ion the op t imal concen tra-t io n l ev e l t o " s p ik e" a sam p le can b e d e te rm in edfrom the re la t ionsh ip :

R i / . j . / ] g i / j . i p i / - f - -mtxtu re ----" V~"s pike "~sam ple

w h e r e R i / j i s the ra t io o f i so tope i to j in the sp ike ,sam p le an d m ix tu re . A n y g iv en co n cen t ra t io n o f anen r i ch ed i so to p e p resen t s an e f f ec t iv e " d y n am icran g e" o v e r w h ich b o th i t ( t h e in t e rn a l st an d ard ) an dan y asso c ia t ed an a ly te i so to p es can b e m easu red

p rec i se ly. T h i s d y n am ic r an g e can b e u sed to t a ilo r apar t icu lar in ternal s t~mdard sp ike so lu t ion fo r theran g e in e l em en t co n cen t ra t io n s l ik e ly to b e en c o u n -tered . With carefu l se lect ion , a par t icu lar en r iched-i so to p e co n cen t ra t io n can b e em p lo y ed to q u an t i fy alarge con cen tra t ion r~mge in assoc ia ted ana ly te i so -topes , such that a s ing le se t o f in temal s tandardc o n c e n t ra t io n s m a y b e e m p l o y e d t o m e a s u r e a b r o a dsp ec t ru m o f co m p o s i t io n s l i k e ly to b e en co u n te red .We ty p ica l ly em p lo y o n ly tw o se t s o f i n t e rn a l s t an -d a rd co n cen t ra t io n s , o n e to m easu re b asa l t i c an dd i f f e ren t ia t ed m a g m a co m p o s i t io n s an d an o th e r tom easu re lo w - lev e l sam p les , su ch as m an t l e p e r i -do t i tes and cer ta in mineral phases .

3 .3 . Cor rec t ion fo r m~ss -dep enden t sens i t iv i ty va r i a -t ion

S en s i t iv ity v a r ia t io n s o ccu r r in g d u r in g th e co u r seo f an an a ly t i ca l ru n a re m o n i to red b y r a t io in g th eco u n t r a t e o f each in t e rn a l s t an d ard i so to p e (o r e l e -

ment) in each so lu t ion analysed , re la t ive to thatm eas u red in th e in i ti a l so lu t io n o f each ru n . T h erec ip ro ca l o f t h ese r a t io s i s u sed to co r rec t t h e co u n tra tes o f each in ternal s tandard , so that they areequ ivalen t to that dur ing the f i rs t analys is o f eachrun . Coun t ra tes fo r the analy te i so topes , which l ieb e tw een in t e rn a l s t an d ard m asses , a re co r rec t ed b asedon a l inear in terpo la t ion o f the in ternal s tandardcorrect ion facto rs as a funct ion o f m ass (see F ig . 1 ),and are ca lcu la ted on- l ine us ing the F isons ' so f tware .T h i s p r im ary co r rec t io n p ro ced u re d eco n v o lv es sen -s i t iv i ty var ia t ions o f bo th matr ix and ins t rument o r i -gin .

A seco n d co r rec t io n b ased o n ex te rn a l s t an d ard is -a t ion i s su b seq u en t ly ap p l ied o ff - l i n e to r em o v e an yres idual sensi t iv i ty d i fferences that remain fo l lowingin ternal s tandard isa t ion . Th is need ar ises because thein ternal s tandard correct ion , which is model led as al inear in terpo la t ion betw een in ternal s tandard m asses ,i s u n ab le to acco u n t fo r t h e o ccu r ren ce o f m o recomplex non- l inear sensi t iv i ty var ia t ions as a func-t ion o f mass (see F ig . 1 ). In reg ions o f the m assspect rum where in ternal s tandards are su ff ic ien t lyclosely spaced , the l inear in temai s tandard correct ionp ro v id es a c lo se ap p ro x im at io n to an y co m p lex sen -s i t iv i ty var ia t ion and a secondary correct ion i s usu-a l ly u n n ecessa ry. H o w ev er, w h ere in t e rn a l s t an d ard s

are separated by large re la t ive mass d i fferences ,par t icu lar ly between 6L i and 84Sr, and be twe en l lS Inand 147Sm, large ex ternal s tand ard-based c orrect ions

1.0

.-- 0.95_ ~

~ 0.90

::z.~ 0 . 85

nn 0.80

0 5 10 15 20 25 30

Analysis # (sequence)

Fig . 2 . A g ra ph ic a l i l l u s t ra t ion o f the e x te rna l - s t a nda rd i s a t ionproc e dure , u s ing e i the r a po lynom ia l f i t t o , o r l i ne a r in t e rpo la t ionbe twe e n , the in t e rna l - s t a nda rd c o r re c te d c oun t ra te s fo r a n a na ly tei s o tope ( in th i s c a s e B e ) a s a func t ion o f the a na lys i s s e que nc e[s e e t e x t a nd a l s o C he a th a m e t a l . (1993) , fo r de ta il s ].


6/16


are sometimes needed (see Fig. 1) . The externals tandard isat ion procedure em ployed i s s imi lar to thatdescr ibed by Cheatham et a l . (1993) . A po lynomialf i t o r l inear in terpo lation i s es tab l ished based on thein ternal s tandard-corrected count ra te ra t ios fo r eachanaly te i so tope as a funct ion of the analys is se-quence, us ing a reference so lu t ion measured repeat -ed ly a t in tervals (every 5-7 so lu t ions) th rough eachrun (Fig. 2) . Several cri teria are em ploy ed to val idatethe integri ty of these external-standard correct ions,nam ely that neighbour ing i so tope masses shou ld havesimi lar correct ion factors and , that the magni tude ofthe correct ion should decrease to zero as i so topesapproach the mass o f any in temal s tandard .

3 .4 . Ins t rument opera t ing param ete rs and per form a n c e

Typical ins t rum ent operat ing parameters are l i s tedin Table 2 a long w i th rou t ine performance cr i ter ia.

3.5. Instrument cal ibrat ion

Ins t rumen t cal ib ra tion i s per formed u s ing a s ing lecal ib ra t ion so lu t ion (which i s analysed in dupl icate)and by forcing the w eigh ted l inear regress ion th roughthe or ig in fo l lowing b lank sub t ract ion . This s imples t ra tegy i s sound , g iven the wel l -es tab l i shed l ineard y n amic r an g e o f t h e ICPMS, wh ich ex ceed s 6orders o f magn itude (e.g ., Jarvis et al ., 1992 ). Cali-

b rat ion i s rou t inely under taken us ing the naturalreference materia l BHV O-I fo l lowing a d iges t ionprocedure iden t ical to that employed for the un-knowns. The use o f a natural reference mater ia lo ffers several advantages over syn thet ic so lu t ionsinclud ing : ( l ) a s imple , equ ivalen t , and reproducib lepreparat ion procedure fo r bo th samples and s tan-dards; (2 ) avo idance o f po ten t ia l analy te con tamina-t ion th rough s tandard so lu t ion impur i t ies ; and (3)long shel f lives o f a t leas t 2 months bu t comm onlylonger. The pr incipal d raw back o f cal ib ra t ing agains tnatural reference mater ia l s i s the incorporat ion ofsys temat ic analy t ical b ias due to dev ia t ion of theadopted cal ib ra t ion concen t ra t ions f rom t rue values .Our p refer red concen t ra t ion values fo r BHV O-1 (Ta-ble 3) are based on a select ion of published (e.g . ,Glad ney and Roeland ts , 1988; Govindaraju , 1989)and unpubl i shed data (W.F. McDonough , pers . com-mun. , 1994). In the event of future change to theseBHVO-1 values , any ex is t ing data need on ly to becorrected by the ra t io o f the new and o ld values .

3 .6 . I sobar ic and molecu la r in te r fe rence cor rec t ions

Interference correct ions are routinely applied tocorrect analy te i so topes fo r molecu lar and i sobar icinterferences, and are also used to subtract the natu-ral isotope contributions to the enriched isotope in-ternal s tandards (see Table 1 ) . The generat ion ofox ide and d oubly-charge d species , and the mass

Table 2Ins t rumenta l ope ra t i ng cond i t i ons

Ins t rument F i sons VG Pla smaQuad PQ2 + STE

F o r w a r d p o w e rRef l ec t ed power

Nebul i se rNebu l i se r ga s f l ow ra t eCoolan t ga s f l ow ra t eAuxi l iary gas f low ra teSpray chamberDe tec to rSensi t ivi tyIon col lec t ionD w e l l t im e a a n d p o i n t s / p e a kAna lys i s t ime

1300 W< 3 W

Meinha rd t0 .85 1 /min14 1 /m in1 1 / m i nSco t t doub le -pass wa te r coo led (~ I C)ETP D inode ope ra t i ng in PC and Ana logue(2-5 ) x 107 coun t s pe r sec ond /pp m nSIn and 238Upeak hopp ing2 .56-20 .48 ms , 3 po in t s /pe ak sepa ra t ed by 5 DAC un i t s90-s acquisi t ions ( ~ 60 sw eeps) , 4 repeats

Qua r t z V-groove0 . 9 2 l / m i n1 4 1 / m i n1 l / m i n

Dwel l t imes a re va r i ed accord ing to i nd iv idua l i so tope abundances and e l em ent re sponse fac to r s , t o m in imi se coun t ing s t a t i s ti c e r ro rs


7/16


8/16

318

Table 3 (continued)

S.M. Eggins et al. / Chemical Geology 134 1997) 311- 326

QLO-1n=2

PreferredValue

Li 27.2B e 2.31 1.89Sc 8.7 8.9Ti 3358 3741V 48 54Cr 1 3.2Co 7.4 7.2Ni 5.8Cu 25 29Zn 57 61Ga 17.3 17.0Rb 72.2 74.0Sr 329 336Y 25.8 24.0Zr 194 185Nb 10.8 10.3M o 2.59 2.60CASn 2.91 2.3S b 2 . 0 0 2 . 1

C s 1 . 6 7 1 . 7 5

B a 1 4 2 9 1 3 7 0

La 26.5 27.0Ce 50.4 54.6Pr 5.99 6.00

N d 22.9 26.0Sin 4.60 4.88Eu 1.203 1.43Gd 4.17 4.70Tb 0.658 0.71Dy 3.90 3.80H o 0.828 0.86Er 2.40 2.30Yb 2.39 2.32

Lu 0.390 0.37Hf 4,68 4.60T a 0,845 0.82TI 0.25 0.22Pb 23.9 20.4Th 4.88 4.50U 1.83 1.94

R G M - 1 P r e f e r re d

n = 7 Value63.0 57.02.93 2.374.7 4.4

1940 160112 134.9 3.72.1 2.03.7 4.411 1230 32

15.9 15.0154.7 149102,4 1 0 8

25.1 25.0241 2199.57 8.902.54 2.30

0.090 0 . 0 6 55 . 3 5 4 . 1 0

1.53 1.2610.45 9.60831 807

23.16 27.045.9 47.05.32 5.3019.08 19.03.94 4.30

0.547 0 . 6 63.56 3.70

0.605 0.663.60 4.08

0369 0.952.33 2.602.47 2.60

0.386 0.415 . 8 1 6.20

0.965 0.950.93

24.2 24.015.05 15.15.56 5.80

STM-1 Prefexgedn=7 Value37.5 32.011.4 8.61.7 0.7

942 8090.2 2.02.30.7 0.71.53.4 4.5200 23734.8 36.0117.7 117.0690 71049.4 42.51441 1280289 2495.19 5.200.24 0.279.87 6 . 8 01.61 1 . 6 6

1.573 1.54577 560

153.2 150264 25926.2 25.580.8 82.412.34 11.33.35 3.358.83 9 741.454 1.3907.92 7.751.543 1,5004.35 4.194.25 4.13

0.623 0.64027.3 29.618.71 17.9

0.2617.73 16.331.2 28.48.53 8.46

PCC-I R S D Literaturen=12 V a l u e

0.9 8.5 1.20.001 171 0.050

9.0 7.6 8.423 12.6 7527 12.5 31

2168 37 2730105 4 4 112

2052 13.9 23807 13.9 1031 13.2 42

0.48 13.9 0.640,058 19.7 0,0660.33 22 0.380.087 5.3 0.0870.191 18.6 0,2000.011 16.3 0.0400.032 55 0.0200.022 2,4 0.020

1 . 2 4 7.0 1.601 36 6.3 1.400

0.0045 13 .6 0.0 0550.76 8.0 0 900.029 7.4 0.0350.053 9.7 0,072

0.0068 8.3 0.00860.025 6.4 0.03500.005 50 .2 0.(}066

0 .0011 40 ,8 0 .00120.0061 19.70.0012 25.0 0. 00 150.0087 14.1 0.0110.0027 13 .8 0.0 0290.0113 10.8 0.0120.0213 6.7 0,024

0.0046 13.3 0.0057O.0054 36 .7 0.0 0600.002 41. 2 0.0020

8.0 4.4 8.50.0115 10 .2 0.0 1000 . 0 0 3 9 1 0 . 3 0 . 0 0 4 3

DTS-In=22.0

0,0025.3199

535

0.390.0780,31

0.0380.2530.012

L i t e a ' a t u r e

Value2 . 1

3 . 5

i i

3 9 9 0

1 3 7

2 3 6 0

7

4 6

0 . 5 0

0 . 0 5 8

0 . 3 2

0 . 0 4

4 . 0 0

2 . 2 0

0 . 1 4

0.99 0.550.500

0.0073 0.00580.33 1.70

0.0246 0.0290.100 0.072

0.0063 0.00630 0234 0 029

0.0031 0.00460.0013 0.00120.0044 0.00380.0007 0.00080.0038 0.00300.0014 0.00130.0050 0.00400.11090 0.0100.0019 0.00240.{)069 0.0150,002 0,039

13.06 12.000 .009~ 0 .01000.0018 0.0036

f r a c t i o n a t i o n f a c t o r s n e c e s s a r y t o c o r r e c t t h e e n -r i ched i so tope in te rna l s t anda rd s igna l s fo r i soba r ici n t e r f e r e n c e s a r e mo n i t o r e d o n a r u n - t o - r u n b a s i su s i n g s t o c k s o l u t io n s . Th e r e m o v a l o f c o n t ri b u t i o n st o a n a l y t e i s o t o p e s f r o m t h e a d d e d e n r i c h e d i s o t o p e si s u n d e r t a k e n v i a b l a n k s u b t r a c ti o n . Ox i d e f o r m a t i o nl e v e l s a r e r o u t i n e l y ma i n t a i n e d n e a r 1 % La O r e l a t i v et o La , a l e v e l wh i c h n e c e s s i t a t e s c o r r e c t io n s t o o n l y ah a n d f u l o f i s o t o p e s / e l e m e n t s , t h e m o s t c r it ic a l o fwh i c h a r e u s u a l l y t h e mi d d l e REE ( Eu , Gd , a n d Tb ) ,

a n d Cu a n d Zn . Le s s s i g n i f i c a n t c o r r e c t i o n s a r e a l s oa p p l i e d t o a n u mb e r o f o t h e r i s o t o p e s , a s d e t a i l e d i nTab le 1 .

4 . R e s u l t s

T h e m e a su r e d c o n c e n t r a t io n s o f > 4 0 t r a c e e l e -ments in a range o f in te rna t iona l and labora to ryreference mater ia ls a re repor ted in Tab le 3 . Also


9/16

S . M . E g g i n s e t a l. / C h e m i c a l G e o l o g y 1 3 4 (1 9 9 7 ) 3 11 - 3 2 6 319

Table 3 (continued)

Bit %RSD Pref med SY-2 %RSD Prefen'ed WSEn=8 Value n=3 Value n=5

Li 14.9 1.1 13.0Be 2.23 2A 1.50Sc 23.4 2A 25.0Ti 16194 7.2 15587V 240 7.1 235Or 368 2.1 380Co 56 6.4 52H i 263 3.4 260C u 71 4 3 72Zn 172 4,4 160G a 1 7 . 1 4 . 1 1 9 . 0

Rb 48.7 1,1 47.0Sr 1364 1.3 1320Y 31.5 1.4 30Zt 283 1.2 250Nb 119.3 1.1 98Mo 2.17 2.3 2.4CdSn 2.24 7.6 2.50Sb 0.137 7.7 0.30Cs 0.823 2.8 1.00Ba 1082 1.4 1050La 82.1 12 82Ce 152.2 1.6 151Pt 17.36 0.7Nd 66.1 02 65Sm 12.11 0.6 12.0Ea 3.58 l.l 3.70Gd 9.57 1.0 9.50Tb 1.29 1.. 1.25Dy 6.30 0.~; 6.20Ha 1.0~/ 0,gEr 2.59 0.6 2.40Y b 1.806 1 . 0 1.90L u 0 . 2 5 1 1.] 0 . 2 5Hf 5.62 1.:; 5.40Ta 5.79 1.0 6.201 1 0.074 2.6 0.05OPb 4.77 3 0 8.00Th 10,87 0.11 I I . 0 0U 2.46 1 . 2 2 . 5 0

95 5.2 95.027 4.0 22.06.9 5.1 7.0

770 7.7 83949 3.74.9 14.3 9.512 673 8.611 9.93 27.3 5.2

222 5.1 24828.0 2.4 29.0225 1.5 2172 7 1 2 . 5 2 7 1

1 4 4 2 . 0 1 2 8 . 0

3 1 4 3 . 1 2 8 0 . 0

32.3 2.3 290.82 1.80

6.15 5.700.219 0.2502.805 3.1 2.400453 0.6 46069.2 0.9 75.0161.1 0.6 175.020.1 1.1 18.8076.5 1.3 73.016.2 0.8 16.102.40 0.7 2.4216.7 3.3 17.003.08 1.9 2.5020.4 1.8 18.004.84 1.2 3.8015.59 0.7 12.4018.07 0.2 17.003.06 1.4 2.708.65 1.3 7.701 . 9 7 1 4 2.012.00 1.8 1.5053.4 0.6 85.0333 12.4 379247 6.0 284

PMS 93-1489n=2 n=23

13.6 5.2 7.5 4.81 . 2 6 5.7 0.37 0.91828.0 3.8 32.4 31.6

14198 6 4 9 14362347 181 301

95 2.1 315 47143 10.1 45 5154 2.4 120 16065 4.1 57 123115 6.1 56 10421.6 2.7 14.5 19.226.0 0.8 0.915 7.15403 0.9 270 31733,6 1.7 11.37 27,0212 0.7 36.1 147.2

18.98 1.0 2.41 13.243.18 1.57 0.74

0.06416.24 5.28 1.720.077 0.023 0.0330.480 2.4 0.347 0.074337 0.9 146.3 99.926.7 0.7 2.57 11.2059.3 0.6 6.52 27.97.80 0.6 1.051 4.1132.5 1.5 5.46 19.218.76 1.8 1.798 5.212.16 0 . 5 1.053 13837.06 1.3 2.04 5.591.074 0.3 0.338 0.8785.98 0.5 2.05 4.961.176 0.8 0 . 4 2 5 0 . 9 6 63.08 0.3 1.169 2.512.50 0.6 0.984 1.974

0.359 1.6 0.145 0.2795.03 1.6 1.033 3.581.140 0.9 0.176 0.8200.230 0.051 0.02213.4 8.6 3.51 0.953,13 1.8 0 044 0.853

0.628 0.6 0.014 0.274

%RSD Tafahi %RSDn=12

1.4 3.52.3 3,01.7 3.0

2.5 6.64.3 .72.5 2.12.3 5.81.7 1.92.6 3.31 . 5 6.00.8 1.01 .8 1 .80.7 1.00.5 0.90.5 1.60.6 0.85.5 3 . 313.5 3.12.7 9.373 9.53.9 3.O0.5 1.20.6 1.40.5 1.10.6 2.00 7 1.40.8 1 . 80.5 1.20.9 1.40.8 2.70.5 1.10.8 1.00.5 0.91.0 1.21.2 1.70.8 1.01.0 3.83.9 4.32.7 2.31.0 2.10.6 1.3

4.O0.18545.5

2279298

53412512864

13.131350138.99.1112.070.4560.440.031O.24

0.0240.06640.3

0.9382.22

0.3611.93

0.7220.3051.0690.2071.3840.3220.9800.9920.1530.3950.02190.0142

O.950.120

0 0728

l i s t e d a r e r e l a t i v e s t a n d a r d d e v i a t i o n ( RSD) v a l u e s

b a s e d o n mu l t i p l e d e t e r mi n a t i o n s ma d e i n i n d e p e n -d e n t a n a l y t i c a l p r o c e d u r e s , a n d i n mo s t c a s e s in c o r -p o r a t e m u l t i p l e d i g e s t io n s o f e a c h r e f e r e n c e m a t e r i a l.Th e p r e f e r r e d v a l u e s l i s t e d f o r e a c h r e f e r e n c e ma t e -r i a l p r o v i d e a g u i d e t o t h e a c c u r a c y o f th e m e t h o d ,i ts d y n a mi c r a n g e , a r id t h e a b i li t y to m e a s u r e a b r o a dr a n g e o f ma t r i x c o mp o s i t i o n s .

Th e p r e c i s i o n a b l e t o b e a t t a i n e d u s i n g o u r t e c h -n i q u e i s i n d i c a t e d b y t h e RSD v a l u e s l i s t e d f o r o u rl a b o r a t o r y s t a n d a r d 9 3 - 1 4 8 9 , a K i l a u e a t h o l e ii t e s i m i -

l a r t o BHVO- 1 . Th e d a t a f o r t h i s r e f e r e n c e ma t e r i a l

we r e a c q u i r e d i n 2 3 s e p a r a t e a n a l y t i c a l p r o c e d u r e sa n d o n n o l e s s t h a n 1 5 s e p a r a t e s a mp l e d i g e s t i o n so v e r a p e r io d b e t w e e n M a y 1 9 94 a n d F e b r u a r y 1 9 95 .T h e R S D v a l u e s f o r m o s t e l e m e n t s w i t h m a s s > 8 0a mu a r e < 1 %, a n d b e t we e n 1 % a n d 4 % f o r e l e -me n t s w i t h ma s s < 8 0 a mu ( F ig . 3 ). No t a b l e e x c e p -t i o n s o c c u r w i t h Mo , Cd , Sn , Sb , Cs , T1 a n d Pb ,wh i c h c a n b e a t t r i b u t e d e i t h e r t o c o u n t i n g s t a t i s t i cl i m i t a ti o n s a t l o w a b u n d a n c e l e v e l s i n 9 3 - 1 4 8 9 o r t heBHVO- 1 c a l i b r a t i o n s o l u t i o n ( e . g . , Be , Mo , Cd , Sb ,


10/16

3 2 0 S.M. Eggins et aLI Chemical Geology 134 1997) 311-326

Anal~ical PrecisionI I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I I I I I I

i i i i i i i i i i i i i i i i , i i i i i i i l . . . . . . . . . . . . i i

10 iiiiii ................................ii ...................... iiii i i i i i i i i i i i l i l i * ~ i ~ i i i i i i i i i i i i i i i i i i i ii i i i O ii i i l i i ~ i i i i i i i i l i ~ ii i l i ~ i i i i i i i i i i i i i i l i i i i i i i i i i i i i i l i i i

i i + , l . , i i i i i i i i i i f i i i i l l l i i i i i i i i i + i l- - : : : i , i : ~ i ~ i i i i i : i f i ~ i i ~ i l ; l : : l : : : : :

i i6 i i i ' ~ i i l l i i f i i i i i ~ i i i i i i i i i i i i i i i i i ii l + l i l + 9 i i i i i i i i ~ i i i ~ i i i i i i i i i i i i i i i i i i l~ ~ ~ i i i i i i i i i i i i i i i i i , i i i i i i i i i i i i i l i i i i ~ i

1 . 0 - ~ - ~ i . . ~ i ~ . . . f . ~ . ~ . . . f . . ~ . - i . . . ? . - r. i . . . i . . . . ; . - ~ . . . i . . . i . - . ~ . . . ~ . . ~ . i . . . i . - i . . . i . . . i . . . i . . . i ~ . . ~ - ~ . . i ~ . ~ i - ? . . i . . ~ x . . ~~ i i i i i o i i i i i i i i 1 9 i i i l O i i O i i ~ i gi i i i i i i i i i i i T ~ , i i i i i i i i l ' i . : i . i A i ~ i i i i ~ i i

I .L i ii ii i ii .L l ii i, , , i li li i* ' 1 3 i3 , H ~8 : ~ V GrOoNiCuZ~lRbSr Y ZrNbM~SnSbCl~CePrNd$~uGdTb~Ho~ ~ H f~ TIPb~ U

ElementR g . 3 . A n ~ y ~ c a l p ~ c i s i o n v ~ u e s ( % R S D ) ~ r e a c h e l e m e n t u s i n g e n r i ch e d - is o t o p e i n ~ m a l - s t a n d ~ d i s m i o n , b a se d o n t h e r e p r ~ u c ~ i l i ~ o f

multiple in ~ n d e n t me~u~m ents (n = 23) o f our l~ora to~ s tandard 93-1489. T~ se va lues a~ compared to t~ ~e o~ t ic~ prec i

l i ~ t estimated from ~p~ al counting stmist ics. No ~ that ~eroret ical values ~l in g ~l ow ~ 0.3% are n~ shown as ~ey are unable tach~ved due to in ~ns ic instrument noise.

C s , T 1 ; c f . t h e o r e t i c a l p r e c i s i o n l i m i t s b a s e d o nc o u n t i n g s t a t i s t i c s i n F i g . 3 ) , o r t o m i n o r e n v i r o n -m e n t a l c o n t a m i n a t i o n d u r i n g s a m p l e p r e p a r a t i o n a n da n a l y s i s ( s p e c i f i c a l l y P b ) . I n a d d i t i o n , s o m e e l e m e n t sa r e p r o n e t o i n s t a b i l i t y i n d i l u t e n i t r ic a c i d s o l u t i o n s( e . g ., M o ) , a n d o t h e r s t o v o l a t i l i ty d u r i n g t h e d i g e s -

t i o n p r o c e d u r e ( e .g . , S n , S b ). T h e u p w a r d b o w i n

R S D v a l u e s b e t w e e n t h e w i d e l y s p a c e d i n t e r n a l s t a n -d a r d s a t l o w m a s s p r i n c i p a l l y re f l e c t s a n i n a b i l i t y t od e c o n v o l v e a c c u r a t e l y t h e c o m p l e x s e n s i t i v i ty v a r i a -t i o n s t h a t o c c u r i n t h a t r e g i o n , t h o u g h u n c e r t a i n t i e si n th e d e t e c t o r c r o s s - c a l i b r a t i o n b e t w e e n p u l s e - c o u n t -i n g a n d a n a l o g u e m o d e s a n d t h e l e ss p r e c i s e m e a -

s u r e m e n t s a b l e to b e m a d e i n a n a lo g u e m o d e a l s o

Inter Laboratory Com parison

I ~ I r r T r l l l l f r l r l r l l I I , ~i i O i i i i i i i i i i i i i i i i ' i i i i i|- i .] ~ ~ ~ ,ta~ k t~ , ~...LL L.1....i-~-i.-i--j....~.-.i...~...i...~-~.... .... ....~-. ....

i i i i ~ i O ' ' i ' i ~ Y: : : ' 0 : :

I i + i Z i * r i r* O ? ; i i i i l l| i i i i i i i i i i i i ~ i ~ i i i i i i i ~ i ~ i i i ~ i i i i i i i i ~ i1 . 0 ~ . . - . . r - ~ - ~ - ~ - ~ - i . - ~ . . .. . .. . .. . . . . - . ~ - - ~ . ~ - ~ - ~ . . . ~ . . . i . . . .. . . .. . . .. . . .. . . .. . .? . , . ~ - . t - i . ~ - ~ . . r - r ~ . . - ~ e - ~ . . . ? . . * . . ~ , -

~i i + ~ Y e i ~ i i i i i i i i i i i ~[ i i i l l i i i i i i l $ i l i l i i l ~ i i * i i ? l i i i i l i l i

i i i i i i i i i i i i i i i i i i i i i i i ~ i i i i i i i i l i i i i i ~h i i i i i i i i i i i i i i i i i i i i i i i l l l l i i i i i i i i i i l i

H ~Sc ~ i C rColiCuZnGiRbSr Y ~ l l ~d S n tC s l ~C e Pr ldSntEuGd~Ho ~ HI~ ~ Pb~ U

Element~g . 4. C om p~s on of an~ytical precision (in %R SD ) ~po ~ed by laboratories employing muhi-element ~P M S an~ysis strategiegeo l~ica l samples. No ~ ~a t d i ~ n c e s in instrument sensit ivi ty and the number ~ elements determined in these cases have ~e n offsfar as ~ss iM e ~ c o l l~ dam only for ~ re n e e mater iMs wi~ h igh trace e lement abund~ces .


11/16

S.M. Eggins et al. / Chemical Geology 134 1997) 311-3 26 321

affect the high abundance elements . The steady in-crease in RSD va lues f rom the l ight REE to heavyREE i s cons i s ten t wi th decreas ing concent ra t ion l ev-

els and a corresponding count ing stat is t ic baseddegradat ion of precis ion (see Fig. 3) . Similar pat ternsof prec i s ion have been obta ined for o ther in te rna-

o


12/16


t ional and laborato ry reference mater ia ls , though a tm arg in a l ly p o o re r l ev e l s t h an o b ta in ed fo r 9 3 -1 4 8 9(Table 3 , Fig . 3 , and also Fig . 5a below).

4.1. Accuracy and detection limits

A ssessm en t o f t h e m e th o d ' s accu racy i s i n h e r-en t ly l imi ted by the accuracy to which e lementalconcen tra t ions are known in in ternat ional referencem ate r i a l s . Mo s t m easu red v a lu es sh o w reaso n ab leagreem ent (ge neral ly to be t ter than ___ I - 3 % ) wi thpreferred values fo r the in ternat ional reference mate-r ia ls (Tab le 3 ) , par t icu lar ly fo r those e lements whichare re la t ively wel l know n (e .g ., Rb , S r, Y, Zr, Pb ,Th , U and the mul t i - i so top ic REE). The p r incipalso u rce o f i n accu racy w i th o u r t ech n iq u e s t em s f ro mth e ca l ib ra t io n v a lu es ad o p ted fo r B H V O -1 , w h ichb ias a l l determ inat ions w here these cal ib ra t ion valuesdev ia te f rom t rue values .

D e tec t io n l im i t s v a ry f ro m e lem en t to e l em en t d u eto a var ie ty o f fac to rs , bu t fo r most h igh masse lem en t s (> 8 0 am u ) ty p ica l ly f a l l w i th in a r an g ef r om < 1 t o 1 0 p g g - I ( < 1 - 1 0 n g g - 1 s a m p leeq u iv a len t ) an d fo r l o w er-m ass e l em en t s b e tw een 1 0p g g - 1 a n d 1 n g g -~ ( 1 0 n g g - ~ - I tx g g - I s a m p leequ ivalen t ) .

5 . D i s c u s s io n

5.1. Comparison with otherI C P M S analytical techniques

T h e an a ly t i ca l p rec i s io n o b ta in ed u s in g o u rm eth o d m ay b e co m p ared w i th th e so f a r l im i t edd a ta r ep o r t ed b y o th e r IC P MS lab o ra to r i e s th a t em -p lo y m u l t i - e l em en t an a ly t i ca l m e th o d s . In m ak in gsuch a co mpa r ison , the d i fferen t ca l ib ra t ion s t ra teg ies

an d d r i f t co rrec t io n tech n iq u es ad o p ted b y th e v a r i -ous laborato r ies shou ld be borne in mind , as wel l asthe inheren t l imi ta t ions s temming f rom d i fferen t in -s t ru m en t p e r fo rm an ce , p a r t i cu la r ly in cases w h ereo lder, less sensi t ive ins t ruments are employed . Mostlaborato r ies repor t analy t ica l p recis ion between 3%and 10% (e.g . , Jen ne r et al. , 1990; Ch eath am et al. ,1993; Poitrasson et al . , 1993; Schonberg, 1993;Hrmond et al . , 1994; Xie et al . , 1994; see Fig . 4)th o u g h so m e n o tab le ex cep t io n s d o o ccu r. F o r ex am -

p ie , Xie e t a l . (1994) repor t p recis ion bet ter than+ 1% for some e lemen ts in cer ta in sam ples , bu tu p w ard s o f + 5 % an d o ccas io n a l ly a s m u ch as + 2 0 %for o ther e lements in the same sample (e .g . , Hf , Ta,T h an d U in B IR -1 ) . In co m p le te w ash o u t o f p rev io u ssample s ignals p r io r to analys is i s o f ten responsib lefo r su ch p o o r p rec i s io n an d can r e su l t i n m easu redconcen tra t ions that are h igher than accep ted values .

T h e co m p ara t iv e ly p o o r p e r fo rm an ce o f ex i s t in gmul t i -e lement ICPMS analys is s t ra teg ies p robab lyref lec ts the d i ff icu l ty o f under tak ing op t imum sp ik -ing in the case o f s tandard add i t ion o r fa i lu re toad eq u a te ly co r rec t fo r m ass -d ep en d en t sen s i t i v i tyv a r i a tio n s in th e case o f p ro ced u res em p lo y in g ex te r -nal s tandard isa t ion and /o r e lemental in ternal s tan -dard isa t ion . The la t ter are read i ly demonst ra ted bycompar ing the p recis ion ob ta ined i f ex ternal s tan -d a rd i sa t io n a n d /o r e l em en ta l i n t e rn a l s t an d ard isa t io na re u sed as a l te rn a t iv e m ean s to co r rec t o u r p r im arydata se t (F ig . 5a-c) . E x ternal s tandard isa t ion wi thou tin ternal s tandard isa t ion resu l ts in a con sis ten t analy t -i cal p rec is io n o f ~ 4 - 6 % R S D fo r v i rtu a l ly a lle l em en t s (F ig . 5 b ) . T h e m ag n i tu d e an d u n i fo rm i ty o fth i s p rec i s io n m a tch es c lo se ly th a t d em o n s t ra t ed b yCheatham et a l . (1993) us ing the same techn ique (cf .F ig . 5b and 4 ) , and is 5 -1 0 t imes poore r thanach ieved wi th the same data us ing enr iched iso tope

in ternal s tandard isa t ion (cf . F ig . 5a and b ) .The combinat ion o f a s ing le in ternal s tandard wi th

secondary ex ternal s tandard isa t ion d ramat ical ly im-proves analy t ica l p recis ion , par t icu lar ly fo r e lementswhich are near the in ternal s tandard mass (F ig . 5c) .Analy t ica l p recis ion i s reduced to between + 1% and+ 5% for most e lements us ing In , wi th the improve-m en t b e in g m o s t n o tab le fo r an a ly te m asses n ea res tthe in ternal s tandard . Clear ly, fu r ther improvementscan be ob ta ined wi th add i t ional in ternal s tandardsspaced th rough analy te mass range, and can be op t i -

mised wi th the use o f en r iched iso tope in ternal s tan -dards (see Fig . 5a).

5.2. Applications

The ab i l i ty to measure rap id ly and p recise ly al a rg e n u m b er o f e l em en t s o v e r a co n cen t ra t io n r an g ef ro m th e n g g -1 to % l ev e l, i n a b ro ad sp ec t ru m o fm at r ix es , m ak es IC P MS a p o w er fu l t o o l fo r t h eEar th sc iences . The ar ray o f po ten t ia l app l ica t ions o f


13/16


14/16


sured fo r these samples are p lo t ted in F ig . 6 agains tthei r Nb concen tra t ions . Nb is chosen here fo r i t sty p ica l ly h ig h ly in co m p a t ib l e b eh av io u r d u r in g m an -t ie mel t ing and because i t i s un l ikely to have beenadded in s ign i f ican t quan t i t ies to the mant le sourcereg io n o f su b d u c t io n zo n e m ag m as .

Z r /H f r a t io s are fo u n d to in c rease s ig n if i can t lyand sys temat ical ly wi th increas ing Nb concen tra t ion ,f ro m su b ch o n d r i t i c v a lu es n ea r 3 0 fo r t h e m o s t i n -co m p a t ib l e e l em en t -p o o r su b d u c t io n zo n e b asa lt s u pto v a lu es ap p ro ach in g 6 0 fo r t h e m o s t i n co m p a t ib l ee l em en t - r i ch o cean i s l an d m ag m as . T h i s n o t o n lyco n f i rm s th e t r en d o b se rv ed b y D u p u y e t a l . (1 9 9 2 )b u t ex ten d s i t ac ro ss th e co m p o s i t io n a l sp ec t ru m o fm an t l e -d e r iv ed m ag m as . I t i s n o tab le th a t o ceani s lan d b asal ts (O IB ) h av e su p erch o n d r i ti c Z r /H f v a l -

u es an d an av e rag e v a lu e o f 4 4 .6 + 2 .3 ( l c r ) w h ereassubdu ct ion zon e basal t s (SZ B) averag e 37 .2 + 4 .1 ,an d r an g e d o w n to v a lu es a s lo w as 3 0 fo r t h e m o reN b -p o o r sam p les .

N b /T a r a t io v a r ia t io n t en d s to m im ic th a t o fZ r / H f a t le a s t f o r t h e S Z B , o f w h i c h th e m o s tN b -p o o r t en d to h av e su b ch o n d r i t i c v a lu es an d th emore Nb-r ich to have s l igh t ly superchondr i t ic values .OIB clus ter t igh t ly abou t the chondr i t ic value a t16 .7 _ 1 .2 ( l t r ) , wi th the exce p t ion o f several h igh lys i l i ca -u n d er sa tu ra t ed m ag m as f ro m A i tu t ak i (C o o k

Is lands , Po lynesia) which have d is t inct ly superchon-dr i t ic values near 22 . In teres t ing ly, our laborato rys tandard , a Nb-poor i s land arc tho le i i te f rom nor thTo n g a , a lo n g w i th o th e r sam p les f ro m th e sam ereg ion , h av e an o m alo u s su p erch o n d r it i c N b /T a v a l -ues which range to wel l above 20 (F ig . 6 , midd le) .

Y / H o r at io s, un li ke Z r / H f a n d N b / T a , p lo t v e r yt igh t ly abou t the chondr i t ic value (F ig . 6 , bo t tom).Vir tual ly a l l samples have values between 27 and 30 ,wi th s imi lar m ean values fo r S ZB (29 .0 + 1.15),bac k-arc basin basalts (B A B B = 28.4 __+ 1.05) and

O IB (2 8 . 8 _ 1 .1 0) . D ep ar tu re f ro m th e ch o n d r i t i cv a lu e i s u n co m m o n an d i s u su a l ly fo u n d o n ly inso m e h ig h ly d i f f e ren t ia t ed m ag m as w h ich t en d toh av e su p erch o n d r i t i c v a lu es ex ceed in g 3 0 ( see F ig .6 , top) . The la t ter ind icates sub t le d i fferences in thep ar t it i o n in g o f Y an d H o b e tw een c ry s t a l li s in g p h asesan d m el t d u r in g p ro t r ac t ed m ag m at i c d i f fe ren t ia t ion .

T h e sy s t em at i c in c rease in Z r /H f v a lu es a lo n gw i th N b co n cen t ra t io n s in b asa lt ic m ag m a s in d ica t esth a t Z r i s m o re in co m p a t ib l e th an H f d u r in g u p p er

mant le mel t ing . Th is i s consis ten t wi th most exper i -mental and natu ra l e lement par t i t ion ing s tud ies be-t w e e n c l i n o p y r o x e n e - m e l t , g a r n e t - m e l t a n d a m p h i -bo le- m el t (e .g . , Ulm er, 1989 ; Ha r t and Dunn , 1993 ;Green , 1994 ; Adam et a l . , 1995) . Nb has a lso beensh o w n to b e m o re in co m p a t ib l e th an T a fo r c l in o p y -r o x e n e - m e l t a n d g a r n e t - m e l t p a ir s , b u t n ot f o r a m -p h ib o le -m el t an d ru t i l e -m e l t p a i r s ( e .g . , J en n er e tal. , 1993; Gre en, 1994). T he lat ter is of in terestb ecau se th e o ccu r ren ce o f am p h ib o le an d /o r ru t i l ed u r in g m an t l e -w ed g e m e l t in g co u ld ex p la in th es t ro n g ly su b ch o n d r i t i c N b /Ta v a lu es o b se rv ed inso m e su b d u c t io n zo n e m ag m as . H o w ev er, b o th N ban d Ta a re r e l a t iv e ly in co m p a t ib l e in am p h ib o le(e .g ., Gree n , 1994) , and so the p resen ce o f th is phasei s u n ab le to acco u n t fo r t h e v e ry lo w N b an d Ta

ab u n d an ces w h ich ch a rac te r i ses th ese su b d u c t io nzo n e m ag m as . Mo reo v er, t h ese p a r t i cu la r m ag m asare a lso h igh ly dep le ted in o ther t race e lements ,in c lu d in g th e L R E E an d T h , w h ich can n o t b e a t -t r ib u ted to th e p resen ce o f am p h ib o le an d /o r fu t i l edur ing p ar t ia l mel t ing .

D esp i t e p o ss ib l e d i f f e ren ces in b u lk m an t l e -m e l tpar t i t ion coeff ic ien ts fo r Nb and Ta i t wi l l be in t r in -s i ca lly m o re d i f f icu l t to f r ac t io n a te N b f ro m Ta th anZ r f ro m H f in m an t l e -d e r iv ed m ag m as d u e to th em u ch sm al l e r m ag n i tu d e o f b u lk p a r t i t i o n co e ff i -

c i en t s fo r t h e fo rm er e l em en t s , u n less an accesso ryphase such as ru t i le i s p resen t . Any f ract ionat ion o fN b /Ta f ro m th e m an t l e so u rce r a t io i s m o s t l i k e lyon ly a t t iny degrees o f par t ia l mel t ing . Th is mayacco u n t fo r t h e w id esp read d ev e lo p m en t o f su p er-c h o n d r i t i c Z r / H f v a l u e s b u t n o t N b / Ta v a l u e s .

T h e o c c u r r e n c e o f s u b c h on d r it ic Z r / H f a n dN b / Ta v a l u e s i n c e r t a i n m a n t l e - d e r i v e d m a g m a s ,p a r t icu la r ly th e m o s t N b -p o o r su b d u c t io n zo n es m ag -m as , can b e m o s t s im p ly ex p la in ed b y d ep le t io n o fN b re l a t iv e to Ta an d Z r r e l a t iv e to H f in th e i r

mant le sources . Th is i s consis ten t wi th the expectedd ep le t io n o f th ese e l em en t s a r i s in g f ro m p rev io u smel t ing o f the mant le source . A s imple two-s tagem an t l e m e l t in g m o d e l ( c f . F ig . 6 ) can r ep ro d u ce th eo b se rv ed t r en d s an d th e ab so lu te e l em en t co n cen t ra -t io n s . T h i s su p p o r t s t h e h y p o th es i s o f Wo o d h ead e ta l. (1 9 9 3 ) th a t t h e lo w H F S E ab u n d an ces in su b d u c-t io n zo n e m ag m as i s d u e to so u rce d ep le t io n . T h elow N b co ncen tra t ions (_< 1 p~g g - l ) occurr ing inm an y su b d u c t io n zo n e m ag m as as se r t t h is co n c lu s io n


15/16

S.M. Eggins e t aL / Chemical Geology 134 1997) 311- 326 325

fo r t h ey can n o t b e p ro d u ced b y r easo n ab le am o u n t so f m e l t in g o f a f e r t i l e m an t l e so u rce w i th a p r im i t iv em an t l e N b co n cen t ra t io n ( i. e. 0 .7 1 g g - Z ; S u n an dMcD o n o u g h , 1 9 8 9 ) , n o r m e l t in g o f a g eo ch em ica l ly" d ep le t e d " N -MO R ]3 -1 ik e so u rce m an t l e w ith a N bco n cen t ra t io n o f ~ 0 .2 - 0 .4 i~ g g -1 ( a s su m in g 1 0 %m e l t i n g t o p r o d u c e t h e a v e r a g e N - M O R B N b c o n -cen t ra t io n s o f H o fm an n (1 9 8 8 ) ) an d S u n an d Mc-D o n o u g h (1 9 8 9 ) . G iv en a l i k e ly m ax im u m l im i t o f2 0 % p ar t i a l m e l t in g , t h e m an t l e so u rce o f t h e m o s tN b -p o o r su b d u c t io n zo n e m ag m as , i s e s t im a ted toco n ta in n o m o re th arL 4 0 n g g -1 N b . T h e n a tu re an ds ig n i fi can ce o f t h e su p erch o n d r i t ic N b /T a v a lu e o b -t a in ed fo r sam p les f ro m n o r th To n g a i s t h e su b jec t o fa con t inu ing invest igat ion .

6. Conclus ions

T h e n o v e l u se o f en r i ch ed i so to p es a lo n g w i thcon ven t ional e lemenlLal in ternal s tandards enab les theco m p lex sen s i t i v ity v a r i a tio n s th a t a re o f t en en co u n -t e red d u r in g IC P MS an a ly s i s t o b e m o n i to red an dd eco n v o lv ed . T h i s p ro v id es th e b as i s fo r a ro u t in em e th o d fo r th e an a ly s is o f > 4 0 t r ace e l em en t s ,spann ing the en t i re mass range, in a b road spect rumo f sam p le m a t r ix es . T h e m e th o d d e l iv e r s im p ro v ed

p r e c is i o n a n d e x t e n d e d e l e m e n t c o v e r a g e c o m p a r e dto ex is t ing ICPMS analy t ica l s t ra teg ies , whi le main-ta in ing low detect ion l imi ts . These capab i l i t ies ared em o n s t ra t ed b y th e m easu rem en t o f su b t l e b u t s ig -n i f ic a n t d e v i at io n s o f Z r / H f a n d N b / T a r a ti o s f r o mch o n d r i t i c v a lu es in m an t l e -d e r iv ed b asal ti c m ag m as ,an d th e o cc u r ren ce o f sy s t em at ic v a r i a t io n s in th esera t ios wi th vary ing i incompat ib le e lement concen tra-t ions . Th is behav iour ind icates g reater incompat ib i l -i t y o f N b th an T a an d o f Z r th an H f d u r in g m an t l em el t in g , an d su p p o r l s t h e n o t io n th a t t h e cau se o f N b

an d o th e r H F S E d ep le t io n s in su b d u c t io n zo n e m ag -m as i s d u e to th e g eo ch em ica l d ep le t io n o f th em an t l e w ed g e b y p r io r m e l t in g ev en t s .

A c know le dge me n t s

We are in d eb ted to B i l l McD o n o u g h fo r h i s a s -sessm ent o f p referr,~d values fo r BHV O- 1 and theo ther in ternat ional s tandards , and to bo th he and

R o b er t a R u d n ick fo r t h e i r o n g o in g in t e res t i n an dcr it i ca l a s sessm en t o f o u r IC P M S tech n iq u e an d d a ta .Mik e S h e l l ey h as sh a red w i th u s h i s m u ch v a lu edk n o w led g e o f an d r em ed ies fo r p ro b lem s asso c ia t edw i th IC P sam p le in t ro d u c t io n sy s tem s .

References

Adam, J . , Green, T.H. and Sie , S.H. , 1995. Proton microprobedetermined par t i t ioning of Rb, Sr, Ba, Y, Nb and Ta betw eenexper imenta lly produced amphiboles and si l ica te melts withvar iable F content . Chem. Geol., 109: 29-4 9.

Cheatham , M.M., Sangrey, W.F. and W hite , W .M., 1993. Sourcesof error in external ca libra t ion ICPM S analysis of geologicalsamples and an im proved no n-l inear dr if t correction proce-dure . Spectrochim. Acta , 48B: E487-E 506.

Doherty, W. , 1989. An internal s tandardization procedure for thedetermination of yt tr ium an d the rare ear th e lemen ts in geolog-ica l mater ia ls by inductively coupled-mass spectrometry.Spectrochim. Acta , 44B: 263-28 0.

Dupuy, C. , Liotard, J .M. and Dosta l , J . , 1992. Z r / H f f rac tionationin intrapla te basalt ic rocks: Carbonate metasomatism in themantle source . Geochim. Cosmochim. Acta , 56: 2417-2423.

Gladney, E.S. and Roeland ts, I. , 1989. 1987 compila t ion data forUS GS BIR-1, DNC-1 and W-2. Geo stand. Newslett. , 12:63-118 .

Govindaraju, K. , 1989 . 1989 compila t ion of working values andsample description for 272 geostandards. Geo stand . Newslett.,13: 1-113.

Green, T.H. , 1994. Exper imenta l s tudies of trace-e lement par t i-t ioning applicable to igneous petrogenesis - - Sedona 16 yearslater. Chem. Geol. , 117: 1-36.

Hart, S.R. an d Dunn, T. , 1993. Exper iementa l cp x/m elt par t i t ion-ing of 24 trace eleme nts. Contrib. Mineral. Petrol. , 113: 1-8 .

Htm ond , C. , Devey, C.W. an d Chauvel, C. , 1994. Source compo-sit ions and melt ing processes in the Socie ty and Austra lplumes (South Pacif ic Ocean) : Element and isotope (Sr, Nd,Pb, Th) geochemistry. Che m. Geol., 115: 7- 45 .

Hofm ann, A.W., 1988 . Chem ical differentia t ion of the Ear th:re la t ionship between mantle continenta l and oceanic crust .Ear th Planet. Sci . Lea . , 90: 297-3 14.

Jarvis, K.E., Gray, A.L. and Houk, R.S., 1992. Hand book of

Inductively Coupled Plasma M ass Spectrometry. Blackie ,Glasgow, 299 pp.Jenner, G.A., Longerich, H.P., Fryer, B.J. and Jackson, S.E.,

1990. Inductively coupled plasm a-m ass spectrometr ic analysisof geological samples: a critical evalu ation base d on casestudies. Chem. Geol. , 83:105-118.

Jenner, G.A., Foley, S.F., Jackson, S.E., Green, T.H., Fryer, B.J.and L onger ich, H.P. , 1993. Determination of par t it ion coeff i-c ients for trace e lements in high pressu re- tempe rature experi-menta l run produc ts by la ser ab la t ion m ic roprobe - induc t ive lyc o u p l e d p l a s m a m a s s s p e c t r o m e t r y ( L A M - I CP- M S) .Geochim. Cosmochim. Acta , 57: 5099-5103.


16/16


Jochu m, K.P., Seufert, H.M ., Spettel, B. and Palme, H., 1986 . Thesolar-system abundances of Nb, Ta, and Y and the re la t iveabund ances of refractory l i thophile e lements in d ifferentia tedplanetary bodies. Geochim. Cosmochim. Acta , 50:117 3-11 83.

Poitrasson, F. , Pin, C., Telouk, P. and Imb ert, J.L., 1993 . Assess-ment o f a s imple me thod for the de te rmina tion of Nb and Taat the sub Ixg/g level in silicate rocks by ICPMS. Geostand.Newslett. , 17: 20 9-2 15.

Schonberg, G., 1993. Simultaneous determ ination of thirty-seve ntrace e lements in twenty-e ight international rock standards byICPMS . Geostand. Newslett. , 17: 81 -97 .

Sun, S. -s . and McDonough, W.F. , 1989. Chemical and isotopicsystematics of oceanic basalts: implications for mantle compo-sition and processes. In: A.D. Saunders and M.J. Norry (Edi-tors) , Ma gmatism in the Ocean Basins. Geol. Soc. Lon don,London , pp. 3 13-345 .

Thom pson, J .J . and H ouk, R .S., 1987. A study of internal s tan-dardization in inductively coupled p lasm a-m ass spectrometry.Appl. Spectrosc. , 41: 801-806.

Ulmer, P. , 198 9. Par t i t ioning of high f ie ld strength e lementsam ong olivine, pyroxenes, garne t and calcalkalin e picro-basalt:Exp erimen tal results and an application. An nu. Rep. Dir.Geophys. Lab. , 1988/1989: 42-47.

Woodhead, J . , Eggins, S. and G amble , J ., 199 3. High f ie ldstrength and transit ion e lement systematics in is land arc andback-arc basain sa l ts : ev idence for m ult i-phase melt extrac tionand a depleted man tle wedge. E arth Planet. Sci. Lett. , 114:491-504 .

Xie, Q., Jain, J. , Sun, M., Kerrich, R. an d Fan, J. , 1994 . ICP MSanalysis of basalt BIR-1 for trace elements. Geostand.Newslett. , 18: 53 -63 .

a simple method for the precise determination of -40 trace elements

Documents