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SR isotopic study of ultramafic nodules from Neogene alkaline lavas of British Columbia, Canada and Josephine… Sun, Min 1985

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SR ISOTOPIC STUDY OF ULTRAMAFIC NODULES FROM NEOGENE LAVAS  OF B R I T I S H COLUMBIA, CANADA SOUTHWESTERN  AND JOSEPHINE  PERIDOTITE,  OREGON, U.S.A.  by MIN /SUN B. S c . P e k i n g  University,  1982  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in THE FACULTY OF GRADUATE Department  We a c c e p t to  of G e o l o g i c a l  this  thesis  the r e q u i r e d  THE UNIVERSITY  Sciences  conforming  standard  OF BRITISH COLUMBIA  August ©  as  STUDIES  1985  M i n Sun, 1985  ALKALINE  In  presenting  requirements  this  Columbia,  freely  available  permission  scholarly  I agree for  purposes or  understood  that gain  that  partial  by  may his  copying  shall  the  reference  for extensive  Department  financial  in  not  be or  of G e o l o g i c a l  The U n i v e r s i t y o f B r i t i s h 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  D a t e : 29 A u g u s t  1985  Library and s t u d y .  of  the  this  granted  by  the  allowed  Columbia  Head  of t h i s  without  of it  agree  thesis  representatives.  or p u b l i c a t i o n  Sciences  make  I further  of  her  be  shall  copying  permission.  Department  fulfilment  f o r an a d v a n c e d d e g r e e a t t h e The U n i v e r s i t y  British  that  thesis  of It  for my is  thesis for my  written  ABSTRACT  Twelve of  British  Nodules Ti  and  and from the  u l t r a m a f i c nodules Columbia  are Na  depleted  abundance  either the  depleted Pyroxene and  temperature, from  a  used  Sr  and  for  depth  10-20  compositions  of  whole  (ol,  cpx  and  opx)  host  and  associated  similar  have  host to  with  small  and  are  respect  enstatite  to  even  more  Cr,  formula  Al, unit,  Four  samples  depleted  than  Ti-metasomatism. (Mercier,  calculations.  km  from  1980)  was  ortho-pyroxene  depth  (936-l008°C, a  mantle  average  Rb  and  rock,  equilibrium Nodules  9-15.5  depth  acid  whole  of  came  kb).  30-65  km  Rb  blank  contents  leachate  and  the  rock " b a s a l t s , and and  opx)  Sr  mineral  from  from  of  0.26  isotopic separates  nodules, acid  the  ng  eleven  leached  Josephine  analysed.  but  very  ppm,  of  Sr  total  acid-leached  ( o l , cpx  This  degree  peridotite.  unmetasomatised.  an  b a s a l t s have  r a t i o s '(12.7-62.1 respectively).  ng,  been  MORB,  with  lavas  kb)  establishing  separates  alkaline  series  or  and  30-50  came  3.3  The  clino-  of  of  Peridotite  or  lack  and  blank  mineral  diopside  Peridotite  pressure  (1003-1042°C,  and  per  Peridotite  After  undepleted  geothermobarometry  mantle  Josephine  or  nodules  Neogene  Cr-diopside  Ti-metasomatised  Josephine  modified  are  from  8  7  Sr/  much  702-1514  8  6  or i i  (0.70238-0.70289)  higher ppm  is attributed melting  Sr  to  Rb,  and a  melting  Sr  and  8 7  Rb/  8 7  Sr  0.028-0.138, low  8  7  Sr/  after  8  6  Sr  recent  mantle  metasomatism  by a  ne  alkali  normative Diopside  0.125-3.47  in  0.23-0.38 least  Rb  in  and  Rb/  and Sr ppm and  6  Sr  fluid.  carrier and ppm  low  7  0.7089-0.7133  Sr/  7  Peridotite).  8  6  Sr  S r /  8  6  only in  ppm  0.256-0.582  S r  ratio  i n nodules  Sr =  the  and  0.11-3.5  ppm  Peridotite)  ( 0 . 7 0 3 6 - 0 . 7 197  0.8-1.73  and  contain  in nodules  Peridotite)  and  ppm  in Josephine  i n Josephine  ratios  (Rb = in Josephine  Olivines  Peridotite,  ppm  in nodules  and  (0.004-0.1  in Josephine  (0.19-2.06  8  ppm  0.7054-0.7063  ratio  0.153-0.305  and Sr  i n nodules  and  in Josephine  8  o f Rb  0.023-0.076  with  Sr  Nodules occur  and b a s a n i t e s .  (Rb = 0 . 0 5 5 - 0 . 2 7  the h i g h e s t  ratios  8 6  i n Josephine  nodules  give  9.3-239  8 7  8  basalts  i n nodules  and  0.084-0.102  Sr/  Peridotite),  (0.7022-0.7041 Peridotite)  7  i n nodules  Sr =  Josephine  8  i s t h e main  ppm  Peridotite,  low  and  in  8 7  and  nodules  Rb/  8 6  Sr  in Josephine  Per i d o t i t e ) . Nodules undepleted  from  Jacques  i n major  elements,  mantle.  Other  nodules  mantle.  Whole  rock  corresponding due  material  having  calculated ratios  than  from host  a  could  data  Rb/Sr  fall  on  ratio.  isochrons, this  nodules  and  basalts  Together  supports are not  less  Sr-depleted  or o f f the  latter with  phenomenon  have  with  whole  higher  the well  the conclusion cognate.  is  interstitial  "Synthetic"  leached-mineral data, basalts.  MORB-source-type  somewhat  recent contamination high  i n Sr and  be a  i s o c h r o n s . The  mineral  host  depleted  represent  nodule  mineral  to relatively  Lake,  8  7  rocks,  S r /  8  6  defined that  the  S r  Equigranular isochron  date  (1518-1537  Protogranular (  8  (  8  (  B  7  7  7  Sr/  8  Sr/  8  Sr/  8  6  6  6  nodules show (  8  7  nodules  8  Ma  give  0.7037.  Sr)  0  =  0.7024-0.7032)  Sr)  0  =  0.7029) define  Sr)  0  Depleted mineral  of =  dates  have  the  same  (at  8  Sr)  6  dates. mineral  least  =  0  0.70185).  (645  Ma  and  ( 2 7 6 - 5 7 6 Ma  Mesozoic  Peridotite (366-441  in c o n f l i c t  Peridotite  implies  isochron  age  Sr/  Paleozoic  and  reliable  7  Precambrian  early-mid  Josephine  isochron  This  8  mineral  (104  Ma  and  and  Porphyroclastic isochrons,  560-790  Ma  but  also  and  0.7028-0.7030).  0.7038-0.7041), Josephine  old  mid-Proterozoic (  late  =  not  a  and  0  do  6  give  Sr)  evidence  Sr/  nodules  that age  the as  was  with  Ma  and  the  generated  ophiolite  gives 8  7  in Late  base  Sr/  general  does  overlying volcanic  iv  (  middle 8  6  Paleozoic Sr)  view  0  that  Jurassic not  rocks  = the  time.  necessarily and  dykes.  Table  of C o n t e n t s  ABSTRACT L I S T OF FIGURES L I S T OF TABLES ACKOWLEDGEMENTS I.  i i vii viii ix  INTRODUCTION G e n e r a l Statement U l t r a m a f i c Nodules A l p i n e O r o g e n i c and O p h i o l i t e  Peridotite  1 1 ...2 9  11 .  GENERAL GEOLOGY 11 — 1. U l t r a m a f i c N o d u l e s i n B r i t i s h C o l u m b i a G e o l o g i c a l and T e c t o n i c S e t t i n g P r e v i o u s Work Samples S t u d i e d ( 1 ) . J a c q u e s Lake (2) . B i g T i m o t h y M o u n t a i n (3) . K e t t l e R i v e r ( 4 ) . L a s s i e Lake 11-2. J o s e p h i n e P e r i d o t i t e of S o u t h e r n Oregon  12 12 12 15 20 20 21 24 26 27  III.  CHEMICAL MINERALOGY 01 i v i n e C l i n o p y r o x e n e and O r t h o p y r o x e n e Spinel P r e s s u r e and T e m p e r a t u r e E s t i m a t e s  30 32 32 39 39  IV. RB-SR ISOTOPE ANALYTICAL METHOD I V - 1 . Sample P r e p a r a t i o n . . (1) . Nodules (2) . J o s e p h i n e P e r i d o t i t e IV- 2. C h e m i c a l P r o c e d u r e s ( 1 ) . L a m i n a r Flow Hood (2) . R e a g e n t s (3) . Rb and Sr S p i k e s (4) . Sample D i s s o l u t i o n (5) . C h e m i c a l S e p a r a t i o n (6) . Mass S p e c t r o m e t r y (7) . B l a n k s (8) . D a t a r e d u c t i o n (9) . N.B.S. S t a n d a r d SRM987 Measurements ( 1 0 ).. I s o c h r o n C a l c u l a t i o n and P l o t  46 46 46 47 48 48 49 52 53 54 57 60 65 67 67  V.  Rb-Sr ISOTOPE RESULTS V- 1. N o d u l e s and H o s t B a s a l t s V-2. Josephine P e r i d o o t i t e  69 69 70  VI.  DISCUSSION General Considerations Basalts  90 90 91  v  U l t r a m a f i c Nodules ( 1 ) . Jacques Lake (2). B i g Timothy Mountain ( 3). Kettle River ( 4 ) . L a s s i e Lake Josephine P e r i d o t i t e Mantle Growth Curve Summary REFERENCES APPENDIX APPENDIX APPENDIX APPENDIX APPENDIX APPENDIX APPENDIX  93 94 95 95 97 98 99 100 102  1. PROBE A N A L Y T I C A L DATA OF NODULE M I N E R A L S 116 2. F e + + a n d F e + + + IN S P I N E L C A L C U L A T I O N 119 3. PROBE A N A L Y T I C A L D A T A FOR J O S E P H I N E P E R I D O T I T E PYROXENES 120 4. C A L C U L A T E D T E M P E R A T U R E , P R E S S U R E , D E P T H FROM J.V.ROSS 121 5. PROGRAM "RBSR" 122 6. ( a ) PROGRAM "YORK" 127 ( b ) PROGRAM " P L R B S R " 131 7. D U P L I C A T E D RB-SR DATA 133  L I S T OF FIGURES Figure Page 2-1. L o c a t i o n map o f t h e J u a n de F u c a P l a t e S y s t e m 13 2-2. C r u s t a l S t r u c t u r e of t h e s o u t h e r n C a n a d i a n Cordillera. . ' 14 2-3. L o c a l i t i e s of u l t r a m a f i c nodules i n B r i t i s h Columbia 16 2-4. Sample c l a s s i f i c a t i o n b a s e d on m o d a l m i n e r a l o g y 22 2-5. C o m p o s i t i o n of c l i n o p y r o x e n e and o r t h o p y r o x e n e i n u l t r a m a f i c nodules from B r i t i s h Columbia 23 2- 6. G e n e r a l i z e d t e c t o n i c s k e t c h map o f t h e J o s e p h i n e Peridotite 28 3- 1. T i - C r p l o t s of d i o p s i d e s and e n s t a t i t e s .34 3-2. (a) C r / ( C r + A l ) x l O O v s . A l p l o t of e n s t a t i t e s .36 (b) C r / ( C r + A l )x 1 00 v s . A l p l o t o f d i o p s i d e s 37 3-3. C r / ( C r + A l ) x 1 0 0 v s . Mg/(Mg+Fe)x100 p l o t o f d i o p s i d e s and e n s t a t i t e s ......38 3-4. ( a ) Mg/(Mg+Fe)x100 v s . C r / T i p l o t o f e n s t a t i t e s 40 (b) Mg/(Mg+Fe)x100 v s . C r / T i p l o t o f d i o p s i d e s 41 3- 5. Mg/(Mg+Fe++)xl00 v s . C r / ( C r + A 1 ) x 1 0 0 p l o t o f s p i n e l s . 4 2 4- 1. E l u t i o n c u r v e s f o r Mg, Rb, C a , S r a n d Sm on l a r g e column 56 4-2. E l u t i o n c u r v e s f o r Rb, Ca a n d S r on s m a l l c o l u m n s . . . 5 8 4- 3. ( a ) T o t a l Rb b l a n k s .63 (b) T o t a l S r b l a n k s ..64 5- 1. JL1 m i n e r a l i s o c h r o n 75 5-2. J L 1 4 m i n e r a l i s o c h r o n ...76 5-3. JL15 mineral isochron 77 5-4. J L 1 8 m i n e r a l i s o c h r o n 78 5-5. BM1 1 m i n e r a l i s o c h r o n 79 5-6. BM16 m i n e r a l i s o c h r o n ..80 5-7. BM55 m i n e r a l i s o c h r o n 81 5-8. KR1 m i n e r a l i s o c h r o n ..82 5-9. KR2 m i n e r a l i s o c h r o n 83 5-10. KR35 m i n e r a l i s o c h r o n 84 5-11. LL1 m i n e r a l i s o c h r o n 85 5-12. LL14 m i n e r a l i s o c h r o n 86 5-13. JM5 m i n e r a l i s o c h r o n 87 5-14. JM14 m i n e r a l i s o c h r o n 88 5- 15. JM15 m i n e r a l i s o c h r o n . . . 89 6- 1. Earth e v o l u t i o n curves 101  LIST  OF  TABLES  Table Page 2-1. V i s u a l e s t i m a t e d m o d a l m i n e r a l o g y o f t h e s a m p l e s 22 2-2. Chemical c o m p o s i t i o n s of t h e host and a s s o c i a t e d basalts 25 2- 3. C o n c e n t r a t i o n s o f t r a c e e l e m e n t s i n h o s t a n d associated basalts 26 3- 1. N o d u l e m i n e r a l c o m p o s i t i o n s 31 3-2. Josephine P e r i d o t i t e pyroxene compositions 33 3-3. Comparation of pyroxenes of d e p l e t e d and undepleted nodules and Josephine P e r i d o t i t e 33 3- 4. C a l c u l a t e d T, P, D e p t h .44 4- 1. R e a g e n t B l a n k s 51 4-2. I s o t o p i c c o m p o s i t i o n o f N . B . S . S r s p i k e SRM-988 53 4-3. Total blanks 62 4-4. Comparation of t o t a l blanks with other labs 65 4- 5. 8 7 S r / 8 6 S r r a t i o s o f N.B.S. SRM-987 68 5- 1. R b - S r d a t a o f h o s t b a s a l t s 71 5-2. Rb-Sr i s o t o p e d a t a of J a c q u e s Lake n o d u l e s 71 5-3. Rb-Sr i s o t o p e d a t a of B i g Timothy M o u n t a i n 72 5-4. R b - S r i s o t o p e d a t a o f West K e t t l e R i v e r 72 5-5. Rb-Sr i s o t o p e d a t a of L a s s i e Lake 73 5-6. Rb-Sr i s o t o p e d a t a of J o s e p h i n e P e r i d o t i t e 73 5-7. Summary o f m i n e r a l i s o c h r o n s 74  viii  Acknowledgements  I Lee  wish  to  Armstrong,  supervision, Many J.V.  express  I Knight  thesis  advice  samples  Ross.  and  Dr.  and  are  also  for  his  encouragement obtained  also  due  to  thank  like  J.  appreciation  supervisor,  were  Thanks  would  sincere  for  K.  Dr.  the  for  assistance  grateful  for  help  S.  and  the  study.  courtesy  valuable  Scott,  Rice,  Richard  support,  throughout  through him  to  of  Dr.  discussion.  Horsky,  guidance  J. in  the  laboratory. I R.L. and  am  also  Chase, other  Dr.  faculty  Finally, Academia Yang  (67-8841)  to  notably  and  support  L.  is  was  J.  discussions  Mortenson,  with  Prof.  Dr.  R.G.  Sun  students. from  Prof.  Xia,  Engineering R.  Dr.  inspiration  Juanjuan  Financial and  Michael, members  the  Sinica,  Yu and  Sciences  P.  and  Institute  Molan  also  Armstrong.  ix  Prof.  Geology,  Xinhua  Zhou,  acknowledged.  provided  Research  E,  of  by  a  Council  Canadian  Natural  Operating  Grant  I.  This isotope  t h e s i s e x a m i n e s Rb  composition  settings: Columbia  nodules and  Josephine  of  and  from  several  the  theory  plates  depends to physical  temperature, knowledge  that  large  i s based  on  high  1975),  the  plate  d e g r e e on  and  our  geophysical  data,  pressure  studies 1959;  of  (e.g.  studies  lunar  lherzolite  basalts,  geochemical, mantle  samples  in kimberlite  These  Ringwood,  on  studies  and  and  that  the  1975;  (ol-opx-cpx±plagioclase,  1  the earth's mantle  current Present  results under  of  high  Ito,  1972;  samples  Larimer,  isotopic,  1971;  and  petrological, experimental  nodules  the  the  knowledge of  ( a l p i n e p e r i d o t i t e and and  of  the  meteoritic  1962,  i s o t o p i c and  pipes,  reveal  and  Kennedy and  1972), p e t r o l o g i c a l , g e o c h e m i c a l ,  nodules  ophiolitic  velocity structure.  Gast,  natural  British  move o v e r  h i s t o r y , and  Macdonald,  on  different  lithosphere  tectonics  (e.g.  structural,  Sr  Oregon.  i n f e r r e d mantle compositions  t e m p e r a t u r e and  experimental  of  alpine  o v e r l i e and  properties,  pressure,  e x p e r i m e n t s on  Ringwood,  basalts  Mesozoic  divides  asthenosphere. Understanding  chemistry,  and  statement  tectonics  into  concentrations  s p i n e l p e r i d o t i t e from two  P e r i d o t i t e , southwestern  Plate  evolution  Sr  from Neogene a l k a l i  samples  General  earth  INTRODUCTION  mantle  studies  ophiolite,  in a l k a l i  basalts).  is typically  s p i n e l , or  garnet)  a  2 (Ringwood,  1975).  Ultramafic Early led  nodules  studies  of u l t r a m a f i c  t o the c o n c l u s i o n  (Wagner,  1928).  r e v i e w e d by Wyllie plate  that  Early  work on  tectonics  Kuno  i n the  petrology  MacGregor,  1974;  (e.g. Ross, Basu  1979)  and  1971;  Stueber  S r , Nd  a l . , 1977;  and  1980;  Bielski-Zyskind  and  The  olivine, workers  fields  (1965,1967,),  introduction  1977;  1977;  1978;  Menzies  rheology  and  Murthy,  (e.g. Paul,  and M u r t h y , 1980;  ultramafic  b a s a l t s are dominantly  O'Nions 1980;  Cohen e t a l . ,  B e t t o n and G i v e t t a , The  1973;  B u r w e l l , 1975;  Jagoutz et a l . , 1984;  -  Jagoutz et a l . ,  geochemistry  1974;  of  nodules  1980);  (e.g. G r i f f i n  Basu,  isotope  on  ( e . g . Boyd,  M e r c i e r , 1976,  elements  basalts is  are d i v e r s e  1984; nodules in and  spinel  eclogite lherzolite  1975). of a l k a l i  lherzolite  basalts  n o d u l e s have a s i m p l e m i n e r a l o g y o f  o r t h o p y r o x e n e , c l i n o p y r o x e n e and are  mantle  Kuno  pipes are mainly garnet l h e r z o l i t e  nodules  Spinel  1975;  e t a l . , 1984).  those i n a l k a l i  (Ringwood,  F o r b e s and  study  Ikramuddin,  Mengel e t a l . ,  kimberlite  Pb  Kramers,  Stosch et a l . , 1984;  and  the  in a l k a l i  thermodynamics  trace  and M u r t h y ,  kimberlites  1960's, numerous p a p e r s  and  Wood,  1983);  1968;  et  nodules  (1969). S i n c e the  have been p u b l i s h e d . The including  from  t h e y come from  Ross et a l . ( l 9 5 4 ) ,  (1967) and  nodules  i n f a v o u r of a c o g n a t e  spinel.  relationship  of  Some the  3 nodules  with  their  host  rock  ( e . g . O'Hara,  they a r e cumulates  from  the ascending  1967, 1968), i . e .  magma. Many  others  (Ross  e t a l . , 1954; W i l s h i r e  and B i n n s ,  1967)  agree  a r e s a m p l e s of t h e m a n t l e ,  accidently  that  the nodules  caught  up i n t h e a s c e n d i n g  Partial  m e l t i n g of s p i n e l  produce  a silica  lherzolite  1961; H a r r i s  basaltic  undersaturated basalt  a n d l e a v e a more  lherzolite,  (Kushiro,  1969). D i f f e r e n c e s i n t h e c h e m i s t r y  cognate same  h a r z b u r g i t e or dunite as residue  may be due t o o r i g i n a l  different  degrees  o r c o n d i t i o n s of p a r t i a l  and a c c i d e n t a l  of l h e r z o l i t e  h e t e r o g e n e i t y as w e l l as  ultramafic  nodules  melting.  Both  may c o e x i s t  atthe  locality. Ross e t a l . ( l 9 5 4 ) emphasized  mineralogy  and c h e m i s t r y  that  nodules  these  by W h i t e that  magma.  i n t h e m a n t l e may  magnesian  nodules  et a l . ,  (1966),  series,  series  Jackson  The s e c o n d  clinopyroxene  dunite  types of nodules  mantle.  in alkali  basalt, a  series  names  was a l s o  named a s b l a c k  type, pyroxene  (Wilshire  and g a b b r o  suite  and S h e r v a i s ,  and o t h e r 1975). The  - w e h r l i t e - p y r o x e n i t e and gabbro s u i t e s and the s p i n e l  and  t o be m a n t l e  eclogite  Work  (1969) h a s shown  by a m i n o r i t y o f e c l o g i t e  t o be o f c u m u l a t e o r i g i n  1966).  and s u g g e s t e d  a uniform  (1968) and Kuno  type, b l a c k  less descriptive  nodules  and a d u n i t e - w e h r l i t e - p y r o x e n i t e  accompanied  nodules.  of u l t r a m a f i c  were d e r i v e d from  t h e r e a r e two main  lherzolite  the u n i f o r m i t y i n  a r e thought  a r e thought  lherzolite  fragments  suites  (White,  4 From m i n e r a l nodules,  group i s c h a r a c t e r e d  comparatively  group and  Fe-rich olivine  dominanted  by A l and T i - r i c h  by M g - r i c h  by a u g i t e - r i c h v a r i e t i e s .  - rich  olivine  The C r - d i o p s i d e  clinopyroxene  and o r t h o p y r o x e n e ,  lherzolites  augite,  and o r t h o p y r o x e n e , and A l - r i c h  i s c h a r a c t e r i z e d by C r - r i c h  olivine The  two s o r t s o f u l t r a m a f i c  A l - a u g i t e and C r - d i o p s i d e , were d i s t i n g u i s h e d . The  Al-augite  spinel,  chemistry,  and s p i n e l  d o m i n a t e d by  ( W i l s h i r e and S h e r v a i s ,  1975).  A l - a u g i t e g r o u p was a s c r i b e d by most w o r k e r s t o a  cumulus p r o c e s s . olivine-rich  Nevertheless  members of t h i s  Jackson  (1968), Trask  dunites  were c o n s i d e r e d  produced  tholeiitic  interpreted melting other  g r o u p were r e c o g n i z e d  (1969) and F u s t e r t o be r e s i d u e s  lavas  (Jackson  as C r - d i o p s i d e  t e x t u r e s of  of p a r t i a l  and W r i g h t ,  peridotite  the Cr-diopside  workers t o r e p r e s e n t  modified  amounts o f b a s a l t i c Cr-diopside  group,  liquid  From textural  segregation  that  by  partial  1975). On t h e by most  from w h i c h v a r i a b l e removed. W i t h i n t h e  l e s s deformed p y r o x e n e - r i c h  to represent  Al-augite  have been  melt  1970) o r  g r o u p was c o n s i d e r e d  mantle m a t e r i a l  by  e t a l . (1970). These  and r e a c t i o n ( W i l s h i r e and S h e r v a i s ,  hand,  thought  metamorphic  of melts  like  members a r e those  of t h e  group. structural-fabric g r o u p s have been  studies, three  recognized  important  ( M e r c i e r and  Nicolas,1975): (a). size  Protogranular:  (5-10 mm),  with  c h a r a c t e r i z e d by a c o a r s e  the c u r v i l i n e a r  boundaries  grain  between t h e  5 principal  minerals,  have a l m o s t of  any  no  such  that  large  or  (1mm)  and  and  and  the  exsolution the  The  seem t o be  diopside  are  always  texture  of  pressure  through  1976). The  nodules with  from a  the  static  original  during  the  garnet/spinel this  part  of  texture the  strained porphyroclasts  polygonal  strain-free  neoblasts  lineation.  olivine This  and  texture  deformed mantle.  (Ross,  (c) . E q u i g r a n u l a r : having grain in  almost  the  triple  facies are  recrystallization mantle  levels  (Ross,  1983).  that  and are  with  texture  by  from  could  take  place  boundary  of  (Green,  i n t e r p r e t e d as (Ross,  and  1983).  large  small  olivine  and  marked by  a  i s i n t e r p r e t e d as  and  generally  foliation  with  a  spinel  characteristic  of  1983). c h a r a c t e r i z e d by  typically  points. This  are  to  results  e n s t a t i t e together  same shape and  boundaries are  of  of  o r t h o p y r o x e n e . Hand s p e c i m e n s a r e by  are  upward m i g r a t i o n  mantle  elongated  contact  magmatic  (b) . P o r p h y r o c l a s t i c : c h a r a c t e r i z e d by  outlined  devoid  spinel  is believed  of more a l u m i n o u s p y r o x e n e . T h i s  lowering  and  in direct  symplectitic spinel  peridotite  coming  The  m i n o r m o d i f i c a t i o n of  melting.  nodules  crystals  r e l a t i o n s h i p s between them  enstatite grains. This  partial  o r t h o p y r o x e n e . The  the  lineation.  both minerals  represent  by  elongation  foliation  much s m a l l e r  olivine  texture  small  size  straight results  a l l the  and  phases  (l-2mm).  converge at  from h i g h  120°  temperature  i s i n t e r p r e t e d t o have f o r m e d b o t h d e f o r m e d and  The  in  exceptionally  hot.  6 Since  the  e l e m e n t s and on  the  1970's, many s t u d i e s of t r a c e and  of  S r , Pb  and  Nd  i s o t o p e s have been c a r r i e d  u l t r a m a f i c n o d u l e s . . The  Al-augite  wehrlitic  cognate  (a few  from  earlier  an  lherzolite The  nodules  are  with  and  the host  al.,  ratios  1984). The  basalt  and  enriched  i n Rb  nodule,  and  (e.g. G r i f f i n  upper  the  not  and  8 7  Sr/  Burwell,  8 6  Sr  in  ratios  1975;  proven  in equilibrium  Murthy,  mantle.  Sr c o n c e n t r a t i o n s  l e a c h m a t e r i a l has  Sr and  cumulates  i s g e n e r a l l y not  with  (e.g. Paul,1971;  acid  the  whole-rock  are g e n e r a l l y n e i t h e r c o r r e l a t e d w i t h Rb/Sr  acquired  mostly  t h a t most C r - d i o p s i d e  f r a g m e n t s of  nodule  out  t h a t most  r e p r e s e n t cumulates,  magmatic e v e n t )  lherzolite  equilibrium  work c o n f i r m s  represent a c c i d e n t a l l y  nodules  rare earth  1968;  Mengel et  to  be  with  Basu and  nor  the Murthy,  1977). Acid  washed m i n e r a l  orthopyroxene  and  a u t h o r s . The basalt  and  olivine,  minerals are  some m i n e r a l  example, S t u e b e r from  Mt.  with  (  Hole, (  8 7  8 7  Sr/  8 6  ages a r e  8 6  Sr)  not  0  lithosphere  with  0  giving  a date  = 0.7020 ± 0.0002 and a date  t o t h e age  of  of  the  are c o n s i s t e n t with i s being  the  i s o c h r o n s have been o b t a i n e d .  one  1270  of  cases  underlying  the  Ma  host For  isochron,  610  from  ± 230  = 0.7024 ± 0.0002. In t h o s e  similar  basement and  in equilibrium  by s e v e r a l  e t a l . (1974) d e r i v e d a m i n e r a l  Mexico, g i v i n g  Sr)  clinopyroxene,  have been a n a l y s e d  Aldaz, Anctarctica,  New  Sr/  separates,  ±  110  Ma  Kilbourne with  the  isochron  crustal  idea that c o n t i n e n t a l  s a m p l e d . B a s u and  Murthy  (1977) d e r i v e d  7 a mineral  i s o c h r o n , from  California,  3400 ± 300 Ma w i t h  (  is  any n e a r b y c r u s t a l  much o l d e r t h a n  reported  some m i n e r a l  (e.g. Stuber The mantle  8 7  mantle"  Sr)  between  has  element  be e n r i c h e d  compared  m e l t i n g . The  and i s o t o p e c o m p o s i t i o n f o r  indicators  the M e r c i e r  mantle has undepleted Nd/ ""Nd 1  respectively). LREE,  The " d e p l e t e d  eNd = +10  (<0.7030).  mantle" elements,  s e l e c t e d as  by d i f f e r e n t  ( e v i d e n t on a C r v s . T i p l o t ) .  1ft3  nonvolatile  authors.  Ross  (1976) c h e m i c a l d e p l e t i o n  rare e a r t h elements or i s o t o p i c  0 (i.e.  i n many  earth".  e l e m e n t s have been  depletion/enrichment  criteria  c o n s i s t e n t with the  low c o n c e n t r a t i o n s o f i n c o m p a t i b l e  t o the "bulk  (1983) a d o p t e d  "undepleted  m e t e o r i t e s , and c l o s e t o  a b u n d a n c e s and r a t i o s .  Different  "undepleted"  i n t h e m e l t s and  that geochemically  earth" chemical  relatively  1980).  i n s t u d i e s of the mantle.  Rb-Sr a n d U-Pb and c l o s e t o c h o n d r i t i c trace  It i s also  and A l l e g r e ,  i n the r e s i d u e s of p a r t i a l  "bulk  rocks.  " d e p l e t e d " and  Sm-Nd e v o l u t i o n o f c h o n d r i t i c presumed  a date of  = 0.70057 ± 0.00004, which  0  achievement  elements w i l l  i s the mantle  giving  s e p a r a t e s do n o t d e f i n e an i s o c h r o n  i s an i m p o r t a n t  depleted  8 6  e t a l . , 1974; P o l v e  distinction  Incompatible  Sr/  Baja  ratios,  Many a u t h o r s use i . e . undepleted  r a r e e a r t h p a t t e r n , eNd = 0 and eSr =  = 0.51187 and  B 7  Sr/  8 6  Sr  = 0.7045, t o d a y ,  The d e p l e t e d m a n t l e h a s low c o n c e n t r a t i o n o f ( Jacobson  e t a l . , 1984) a n d low  8 7  Sr/  B 6  Sr  8  A few character  spinel  (e.g. " p r i m i t i v e  lherzolite The  lherzolite  n o d u l e s " of J a g o u t z ,  1979).  Most  n o d u l e s have a d e p l e t e d c h a r a c t e r .  mantle  depletion  c o n t i n u o u s or e p i s o d i c lithosphere multiple  n o d u l e s have u n d e p l e t e d  (Allegre  process i s interpreted  accretion  of the  e t a l . , 1982),  stage e x t r a c t i o n  of m e l t  or  to occur  by  continental i n terms  fraction  of a  (Jacobsen et a l . ,  1984). The from an the  "undepleted mantle"  previous separation  The  White  1982; and  source  Patchett,  i s o t o p e s of  Lupton, the  S r , Pb and  "primitive" reactive air,  Nd  gases  Continental  be  derived  after  o r as a  (White,  White  enriched  subducted  1981;  Hofmann  and Hofmann,  basalts  inert  1982;  studies  et al.,1983; s i m u l t a n e o u s l y meet  gas c r i t e r i a  He,  among t h e  for a least  in trace q u a n t i t i e s  indicator  r o c k s a r e d e p l e t e d i n He, 3  and  plume  i s s u p p o r t e d by  (e.g. A l l e g r e  present only  important  from  of  1983).  concept  1985).  fluid,  a lower m a n t l e  Vollmer,  and  t o be a r e s u l t  Chase,  from  the H a w a i i a n  of g a s e s and  and m a n t l e ,  metasomatic  1981;  or  mantle"  isotope  source  i s t h e most  1968,  1983;  inert  1983). O n l y  may  1984),  "primitive  The  e t a l . , 1982;  (e.g. Lupton,  The of  Zindler  resulting  i n the mantle  is interpreted  i n the mantle.  (e.g. Armstrong,  as  mantle.  incompatible elements,  White,  interpreted  of t h e c r u s t  " e n r i c h e d " mantle  metasomatism  crust  be  incompatible-element enrichment  "primitive/primordial"  in  can  of a p r i m i t i v e  in  source.  but MORB g l a s s e s  have  9 excess the  3  H e . No mechanism h a s been  non-radiogenic  3  He/"He r a t i o s f o u n d  m a n t l e . The d e t e c t i o n only  be i n t e r p r e t e d  "primitive" surface (White,  o f e x c e s s He 3  as evidence  with  orogenic  tectonic  i n the earth's  f o r the existence  the  European Alps.  the fluxes  of other  Alpine  to the elements  orogenic  b e l t s and i s l a n d a r c s .  hundred m i l e s ,  m a n t l e . Steinmann  Hess  (1926 and 1927) i n  t o t h e a x e s o f maximum d e f o r m a t i o n  been c o n t r o l l e d by major  Intrusion  f a u l t s with  which almost  ultramafic  (1938) s u g g e s t e d  r e s u l t of the d i r e c t  that  has  proposed  cumulates  the a l p i n e  i n j e c t i o n of a p r i m a r y  association  of a l p i n e  with  i t was a l s o p r o p o s e d  andesitic  represent  submarine  ultramafic  credence  today.  peridotites that the  the cumulate or r e s i d u a l p o r t i o n of  magmas b r o u g h t  Osborn,  into  p e r i d o t i t e s were  B a s e d on t h e p e r s i s t e n t  peridotites  up t o  that  from  little  andesite,  frequently  c e r t a i n l y extend  magma b u t s u c h h y p o t h e s e s a r e g i v e n  orogenic  along  s t r i k e lengths  (1927) o r i g i n a l l y  represented  peridotite  peridotitescharacteristically  close  peridotites  orogenic  by S t e i n m a n n  intruded  1955;  of  i t s transfer  s i g n i f i c a n c e of a l p i n e  o p h i o l i t e was r e c o g n i z e d  the  produce  and o p h i o l i t e p e r i d o t i t e  and  lava.  could  1985).  The  the  that  i n t h e MORB s a m p l e s c a n  m a n t l e He. In many c a s e s  may be u n c o u p l e d  Alpine  several  found  to the surface  1969; C h a l l i s ,  by f a u l t i n g  1969; M i y a s h i r o ,  1973).  (Hess,  10 Ophiolites several by  into mafic  and d o l e r i t i c pillow  radiolarian  peridotites  their  affinities.  n o t h i n g more t h a n  to  proposed  part  represent  metamorphic  alkali  that  a r e now r e g a r d e d a s complexes.  of the o p h i o l i t i c of t h e o c e a n  ophiolites  sequence floor,  represent  lithosphere  setting  of o c e a n i c  crust  1971). O t h e r s  residual  1970). A l p i n e foliated  but s u r r o u n d i n g g r a d e . The b a s a l  petrology, mineralogy  1975), b u t t h e t r e n d  ( i . e . Davies,  1971). Some w o r k e r s c o n s i d e r e d t h e  the formation  tectonites,  temperature,  associated  h a s been t o u n d e r l i n e  section  oceanic  1964,1967,1969; M c T a g g a r t ,  in  upward  alpine  zones of o p h i o l i t e  t o be f o r m e d by c r y s t a l  Dickey,  overlain  grade  frequently  peridotites  vertical  1968 and 1971; Coleman,  1964;  studies  by t h e s i m i l a r i t y  fragments of the a n c i e n t  peridotites  i n turn  (Ringwood,  the basal  many i n v e s t i g a t o r s  magma d u r i n g  thick  t h e d i s t i n c t i o n s between  Alpine  the h y p o t h e t i c a l  peridotites  from  cherts.  and d e t a i l e d  Impressed  layers  kilometers  rocks which  and o p h i o l i t e s  more r e c e n t  ultramafic  l a v a s and b r e c c i a s ,  Hess e m p h a s i z e d  of  of basal  hundred meters t o s e v e r a l  gabbroic  with  consist  from a b a s a l t i c (Thayer,  suggested the  mantle material  peridotites  ( e . g . Hess,  and o p h i o l i t e s a r e  and d e f o r m e d a t h i g h rocks are often ultramafic  and s t r u c t u r a l  o f v e r y low  rocks are s i m i l a r i n  features  t o nodules i n  basalts.  Mainly  because of the h i g h l y  Alpine peridotites,  altered  t h e r e a r e fewer  nature  of the  g e o c h e m i c a l and i s o t o p i c  11 studies of  on  them t h a n  a well-preserved  nodules  in that  lithologies  All  ophiolitic (e.g.  suboceanic same  (Richard simple  r e l a t i o n s between  studies  that  (e.g.  Allegre,  progressively recycled  history  et  more and was  advantage  over  various aid  in  hypothesis the  that  upper  1980). G e o c h e m i c a l and s u i t a b l e t o be  M e n z i e s and  Murthy,  as  idea  partial that  the  more d e p l e t e d  proposed  (Polve  a l . (1984) p o s t u l a t e d  for T r i n i t y p e r i d o t i t e .  and  be  alpine  mantle  isotopic  1978),  they  explained and  oceanic  mantle  that  Allegre,  a multiple  have  basalts  melting  and  -  depleted  oceanic  1980). Many c a n n o t  s i n g l e s t a g e m o d e l s of  Jacobson  the  eNd-eSr c o r r e l a t i o n l i n e and  the  t h i s may  f r a g m e n t s of  some a r e  c o n t a m i n a t i o n . Thus t h e  and  support  Allegre,  mantle  and  the  study  origin.  p e r i d o t i t e s are  reveal  n o d u l e s . However,  p e r i d o t i t e has  preserved,  their  P o l v e and  studies  the  be  recent  ultramafic  Alpine  field  can  interpreting  on  by  (or) is  i t i s mixed 1980). partial  melting  1 2 11.  11 — 1 U l t r a m a f i c  nodules  Geological An off  and  -transform Pacific,  triple  The  Juan  collision  i s the r i d g e  between  lithospheric  plate  which  i s one  25 and  150  trench  the Juan plates  de  near  last  de F u c a  northeast Explorer  plate  relative 6.0  broke  overriden  by  with the (Ma)  at about  continues  to subduct  (Riddihough,  t o Moho and  t o the America  plate.  Juan  Vancouver  de F u c a  The  Juan  American  l e d to the  and  Since  there  Island zone  motion  plate  was  3 Ma, plate  de  and  and of  to the  was  plate  4 cm/yr  Benioff  (Rodgers,  has  the  Fuca  at about  de F u c a p l a t e  t o t h e low v e l o c i t y  The  20 Ma.  7 t o 4 Ma,  to the n o r t h e a s t  1984). The  15° e a s t w a r d under  from  o f f from J u a n  margin  and c l o c k w i s e r i d g e  cm/yr. Between 4 and  the American  remnants of  ridge  de F u c a p l a t e  For the p e r i o d  a t about  2-1).  years.  y e a r s ago  in spreading rate  plate  the  million  i t s s o u t h e r n edge has m i g r a t e d n o r t h w a r d  rotation.  Fuca,  (Figure  of the  - Farallon  30 m i l l i o n  of t h e J u a n  -  situation  converged with the western  over the l a s t  of t h e P a c i f i c  been a r e d u c t i o n  Juan  setting  a t a p p r o x i m a t e l y 51°N  plate,  between  isolation  junction  de F u c a  of N o r t h A m e r i c a  Columbia  of t h e p r e s e n t t e c t o n i c  of Canada  margin  the F a r a l l o n  plate  tectonic  and A m e r i c a n  continental  then  in B r i t i s h  important feature  t h e west c o a s t  plate  G E N E R A L GEOLOGY  zone  1983).  dips  Depth  a r e shown i n F i g u r e  F i g 2-1.  L o c a t i o n map of the Juan de Fuca p l a t e system (from Riddihough, 1984).  14  Fig. 2-2 Crustal s t r u c t u r e of the s o u t h e r n Canadian Cordillera. S t r u c t u r e c o n t o u r s a t 5 km i n t e r v a l s g i v i n g d e p t h t o t h e M o n o . S t i p p l e d p a t t e r n shows zone of g e o m a g n e t i c s t a t i o n s marking t r a n s i t i o n between h i g h l y c o n d u c t i v e c r u s t and upper mantle to the southwest, and l e s s c o n d u c t i v e c r u s t and upper mantle to the northeast. S t r u c t u r e s e c t i o n W-E s h o w i n g P - w a v e v e l o c i t y 1n k m / s . Q u a r t e r n e r y and Recent v o l c a n i c rocks occur at the localities marked by s o l i d t r i a n g l e s labelled "v" The t h i n - s k i n n e d thrust faults of the Rocky Mountain B e l t a r e shown s c h e m a t i c a l l y e a s t of the s o u t h e r n Rocky Mountain Trench (RMT). and the general outline of the d e e p l y r o o t e d Shuswap M e t a m o r p h i c Complex (SMC) 1s s h o w n schematically west of the Rocky mountain T r e n c h (from Monger and Price. 1979). 87Sr/86Sr c o n t o u r s of Mesozoic Igneous rock are a l s o shown ( A r m s t r o n g , 1985, p e r s . comm.). Nodule sample l o c a l i t i e s a r e shown w i t h Inverted triangles: <JL f r o m Jacques Lake, BM f r o m B 1 g T i m o t h y M o u n t a i n , KR f r o m W e s t K e t t l e River, LL from L a s s i e Lake.  15 Recent belts  volcanic  (Figure  southwestern of  is  2 - 3 ) . The G a r i b a l d i British  the Cascade  plate.  trending  t h e Anahim B e l t ,  Columbia  Columbia  Belt  trace.  confined  volcanic  a r e the northern  a r c a n d o c c u r above  The E-W  a hot spot  centers are largely  volcanic  considered  The S t i k i n e  continuation  a t a p p r o x i m a t e l y 52°N  by B e v i e r  i s t h o u g h t t o be r i f t  centers in  t h e s u b d u c t e d J a n de F u c a  belt  Belt  to three  e t a l . (1979)  in northern  related  t o be  British  (Souther and H i c k s o n ,  1984). Throughout are  isolated  basalt  the Intermontane  cinder  of B r i t i s h  c o n e s a n d f l o w s of a l k a l i c  e r u p t e d from Neogene t h r o u g h R e c e n t  W.H.Mathews u n p u b l i s h e d d a t a ; volcanic 2-3  Belt  f l o w s and cones c o n t a i n  shows t h e l o c a l i t i e s  nodules  Bevier,  in British  Previous  Columbia  olivine  time  ( R o s s , 1983;  1983). Many o f t h e s e  peridotite  nodules. Figure  of b a s a l t s c o n t a i n i n g  ultramafic  Columbia.  work  Soregaroli  (1968)  described  n o d u l e s from B i g T i m o t h y  Mountain. Littlejohn of  spinel  lherzolite  and N i c o l a  Castle  They  of iron  (1974)  analysed  the minerals  n o d u l e s from J a c q u e s L a k e , C a s t l e  Lake. Temperatures  distribution olivine.  and Greenwood  were c a l c u l a t e d  Rock  from  a n d magnesium between s p i n e l a n d  concluded that  Rock and J a c q u e s Lake  m a n t l e , whereas t h e N i c o l a  the l h e r z o l i t e  nodules of  a r e p r o b a b l y from t h e upper  Lake  lherzolites  are probably  17  crystal  c u m u l a t e s . They  saw  no e v i d e n c e of r e g i o n a l c h e m i c a l  variations. Fujii  and  Kettle River. southern  that  within are  They  British  but c o n t a i n s and  Scarfe  (1982)  studied  concluded that  Columbia  i s dominanted  the chemical v a r i a t i o n s  small  t h e upper m a n t l e  some b a n d i n g on a s c a l e  individual even  equilibration geothermometer  (30-60  when b a n d i n g  i s present.  temperatures, using of W e l l s  the  lherzolite  minerals  diopside  series  Calculated  two-pyroxene  ( 1 9 7 7 ) , r a n g e d between  920  and  b a s e d on p u b l i s h e d  inferred  between  phase  10 t o 18  kbar  km). (1983)  d i d numerous c h e m i c a l and  a n a l y s e s o f n o d u l e s from West K e t t l e Lightening L a k e , and  C a s t l e Rock. He  profiles  localities  separated  the f o l l o w i n g Al-augite  ultramafic  and  deviatoric  and p o s t u l a t e d  beneath B r i t i s h  nodules in B r i t i s h  (black clinopyroxene) s e r i e s :  (a) . M g - r i c h w e h r l i t e s .  Metacumulates.  (b) . F e - r i c h  Cumulate.  Summit  vs. depth  s i x groups:  wehrlites.  Lake,  Jacques Lake,  rate/viscosity  model o f t h e upper m a n t l e  Ross  Lassie  p r e s e n t e d geotherms  strain  f o r a l l t h e above  rheological  River,  Peak, B i g T i m o t h y M o u n t a i n ,  s t r e s s v s . d e p t h and  into  spinel  beneath  of c e n t i m e t r e to metres  n o d u l e s of t h e c h r o m i a n  e x p e r i m e n t s , were  Ross  dynamic  by  of c o n s t i t u e n t  980°C. P r e s s u r e s of e q u i l i b r a t i o n , stability  n o d u l e s f r o m t h e West  a  Columbia. Columbia  18 Cr-diopside  series  (most a b u n d a n t  type)  Magmat i c — (c) . Dark e m e r a l d - g r e e n d i o p s i d e - b e a r i n g  Ti-rich  lherzolites. Metamorphic, with (d) . D e p l e t e d  bright  lherzolite,  (ej.  Undepleted  (f).  Coarse-grained  all  with  without  h a r z b u r g i t e and  homogeneous w e b s t e r i t e .  plastic  magmatic  textures with  e t a l . (1984) s t u d i e d n o d u l e s  indicate  equilibrated. the  t h a t the  1080  to  kbar.  temperatures  the  nodules  a Cordilleran  of o t h e r  Summit Lake s u i t e  source  region  i n the  geotherm v a r i e d Brearley amphiboles trapped  with  and  (1977),  indicated  the o t h e r phases  using  ranged  than  the  10  to  20  estimates  They c o n c l u d e d  that  from  a deeper  Late  Cenozoic  either  space.  (1984) s t u d i e d  pargasitic  i n a chrome d i o p s i d e - b e a r i n g alkali  mineral  equilibration,  somewhat h i g h e r  upper m a n t l e or  Scarfe  the  Summit  temperatures,  r e p r e s e n t s samples  and  on  the  g e o t h e r m , were between  localities.  i n time  w i t h i n an  Peak. They  are  of  from  generally well  of W e l l s  1100°C. P r e s s u r e s  from  The  are  data  Calculated equilibration  estimated  from  nodules  t w o - p y r o x e n e geothermometer  between  or  deformation.  Lake b a s a n i t o i d flow. T h e i r microprobe phases  dunite.  lherzolite.  recrystallised  Brearley  emerald-green d i o p s i d e —  basaltic  lava  spinel  flow at L i g h t e n i n g  t h a t the p a r g a s i t e i s i n in spinel  lherzolite  lherzolite  and  equilibrium probably  19 crystallized  within  the spinel  stability  mantle  from a v o l a t i l e - r i c h  always  shows e v i d e n c e o f m e l t i n g .  melting  i n the pargasite  processes:  superheating  decompression  metasomatic  within  by t h e h o s t  t h e upper  partial  melting  fluid.  The p a r g a s i t e  i n t e r p r e t e d the  alkali  basalt,  or _in s i t u  m a n t l e . They  p r o v i d e s a p o s s i b l e mechanism  partial  concluded that the  of a m p h i b o l e - b e a r i n g s p i n e l  alkaline  o f t h e upper  a s c a u s e d by one of t h r e e  a s t h e magma a s c e n d e d ,  melting  Cenozoic  They  field  lherzolite  f o r the generation  magmas of t h e I n t e r m o n t a n e  of l a t e  Belt  of B r i t i s h  Columbia. Fieshinger nodules Lake  and N i c h o l l s  in Kostal  Lake  and B i g Timothy  described  described  the ultramafic  and Takomkane M o u n t a i n  Mountain)  the u l t r a m a f i c  L a k e , J a c q u e s Lake  (1977)  and N i c h o l l s  nodules i n Castle  and B i g Timothy  (near Jacques  e t a l . (1982) Rock,  Mountain  Nicola  in their  basalt  papers. Maxwell nodules  (1976)  analysed  Rb a n d S r i s o t o p e s  from J a c q u e s L a k e a n d one from B i g T i m o t h y  w i t h poor d a t a r e p r o d u c i b i l i t y . reruns  o f t h e same m i n e r a l  are  up t o ± 0 . 0 0 3  for  c l i n o p y r o x e n e . Maxwell  overleaching,  attributed  errors,  n o d u l e f r o m J a c q u e s Lake (  8 7  Sr/  8 6  of  8 7  30% and o f  Rb/ 8 7  Mountain, 8 6  Sr  Sr/  8 6  in  Sr  and o r t h o p y r o x e n e a n d ±0.001  s e p a r a t e s used  spiking  2000 ± 100 Ma w i t h  Differences  a r e about  forolivine  batches of mineral  One  i n two  this  f o r repeat  and e r r a t i c gave  Sr)  0  to different analyses,  l a b contamination.  a mineral  isochron  d a t e of  = 0.7024 ± 0.0001. The o t h e r  20  J a c q u e s Lake not  give  evidence (  8 7  Sr/  that and  8 6  n o d u l e and t h e B i g T i m o t h y  i s o c h r o n s , , but t h e y  of great  ± 2400 and 4400 + 2500 Ma w i t h  0  age  (4700  = 0.7020-0.7006, r e s p e c t i v e l y .  the apparent  isochron  t h e lower d a t e  c a u s e of d i s e q u i l i b r i u m but  represents in other  have  The new  been  decay  a "mantle  two n o d u l e s was  t o o low b e c a u s e  suggest that  of  8 7  Rb  e v e n t " . The  i n t h e m a n t l e may  analyses  show  He c o n c l u d e d  i s due t o in_ s i t u  he t h o u g h t metasomatism  explanation. may  nodule d i d  reasonable mineral  Sr)  that  Mountain  unknown,  be a  h i s Rb  of o v e r e s t i m a t i o n  possible analyses  o f t h e Rb  blank.  Samples  studied  Samples  for this  Timothy  M o u n t a i n , West K e t t l e  chemical shown  s t u d y a r e from J a c q u e s L a k e , B i g  c o m p o s i t i o n s of the host  and L a s s i e  L a k e . The  and a s s o c i a t e d  basalts are  i n T a b l e s 2-2 and 2-3. ( 1 ) . J a c q u e s Lake The  basaltic south  J a q u e s Lake tuff,  series  (5 on F i g . 2-3)  locality  Pleistocene  o f Q u e s n e l Lake  adhering  in central  t o nodule JL14 i s s o d i c  ankaramite  (Armstrong,  throughout size  diameter  the t u f f .  cone  (Campbell, British alkali  121°9.4'W)  of c o a r s e 1978),  4 miles  C o l u m b i a . The olivine  lava  basalt  1985, p e r s . comm.).  Ultramafic  rocks are s c a t t e r e d  The n o d u l e s a r e s u b - r o u n d e d  from 2 t o 35 cm. Most (Littlejohn  (52°28.6'N  i s a small  i n age  n o d u l e s and f r a g m e n t s o f o t h e r  in  River  are less  and Greenwood,  than  1974).  and range  15 cm i n  21 Four JL18)  nodules  were  lherzolite  f r o m J a q u e s Lake  selected for this region  study.  interlocking colorless thin  range up t o 4 mm. mosaic  to pale  yellow  perfect  cleavage,  yellow  in thin  grains,  b r i g h t emerald  in  s e c t i o n . New  thin  clinopyroxene,  irregularly-shaped  intergranular Somewhat  as subhedral i n hand  green  i n hand  Table  nearly  olivine  grains  with  s p e c i m e n and p a l e forms s m a l l  anhedral  specimen and p a l e  green  spongiform m i c r o c r y s t a l l i n e  due t o p a r t i a l  around c l i n o p y r o x e n e  orthopyroxene,  brown  i n most  s e c t i o n . Clinopyroxene  grains,  ( F i g u r e 2-4;  i n hand s p e c i m e n a n d c o l o r l e s s i n  occurs  dark  i n the  O l i v i n e forms an  s e c t i o n . K i n k bands a r e o b s e r v e d Orthopyroxene  fall  t e x t u r e . O l i v i n e and  of e q u i d i m e n s i o n a l  grains.  found  They  i n OL-OPX-CPX t r i a n g l e  2-1) a n d a r e a l l of p r o t o g r a n u l a r orthopyroxene  ( J L 1 , J L 1 4 , J L 1 5 and  melting,  occurs  g r a i n s . S p i n e l s occur  grains  inside  some s u b h e d r a l partial  as  or i n c o n t a c t  spinel  commonly  with  grains c r y s t a l l i z e d in  melt.  equigranular  and p o r p h y r o c l a s t i c t e x t u r e  were  i n J L 1 5 and J L 1 8 , r e s p e c t i v e l y . The  clinopyroxene  enstatite  (Table  (2).  i s d i o p s i d e and o r t h o p y r o x e n e i s  3-1, F i g u r e 2 - 5 ) .  B i g Timothy Mountain  (4 on F i g . 2-3)  (52°63'N,  121°9.4'W) Big cone  T i m o t h y M o u n t a i n , n o t f a r from J a q u e s L a k e ,  (600 m e t e r s  (adhering  i n d i a m e t e r ) of p o t a s s i c s e r i e s  t o n o d u l e BM11  and BM26) t o p i c r i t i c  isa  alkali  alkali  Fig  2-4  Sample c l a s s i f i c a t i o n b a s e d on mooai m i n e r a l o g y i n terms of o l i v i n e , o r t h o p y r o x e n e and c l i n o p y r o x e n e .  23 CoMgSi 0 2  6  MgSiO,  Fig  (adhering 1985,  2-5  C o m p o s i t i o n o f c11nopyroxene a n d o r t h o p y r o x e n e u l t r a m a f i c nodules from B r i t i s h Columbia.  t o nodule BM55) b a s a l t or basanite  p e r s . comm.), P l e i s t o c e n e  in  (Armstrong,  i n age (Campbell,  1978). The  u l t r a m a f i c nodules a r e round and subround, they range i n s i z e from 5 t o 50 cm, and comprise from 1 t o 25% of the lavas  ( S o r e g a r o l i , 1968). Three nodules from t h i s l o c a l i t y  (BM11, BM16 and BM55)  were s e l e c t e d for t h i s study. BM11 i s l h e r z o l i t e and BM16 and  BM55 a r e o l i v i n e w e b s t e r i t e  ( F i g u r e 2-4, Table 2-1).  BM11 and BM55 e x h i b i t p r o t o g r a n u l a r  t e x t u r e as observed  at Jacques Lake. BM55 o l i v i n e d i s p l a y s s p e c t a c u l a r  kink  bands i n l a r g e g r a i n s . BM16 e x h i b i t s e q u i g r a n u l a r  t e x t u r e . O l i v i n e and  orthopyroxene g r a i n s a r e l e s s than  1.5 mm a c r o s s , with 120°  24 triple mm  j u n c t i o n s . Subhedral clinopyroxene  and  spinel  are  0.5  across. The  clinopyroxene  enstatite  (Table  is diopside  3-1,  Figure  ( 3 ) . West K e t t l e R i v e r  and  orthopyroxene  is  2-5). (1  on  F i g . 2-3)  (49°46.9'N,  119°4.0'W) There are  four  field.  lower  three  are  layer  i s 11  m e t e r s t h i c k . The  about  observed, short  1982). The  olivine  2-2).  layer.  This  and  The  that  section.  the  dates  lower  no  basanite  1980;  from  nodules  lherzolite  c o l u m n s . The 2 t o 25 (KR1,  (Figure  are The  strung [010]  out of  series alkali  pers.  comm.)  only  i n the  top  columnar  joints  with  nodules are  sub-rounded  cm.  KR2  and  2-4,  KR35) s e l e c t e d f o r  Table  foliation  parellel olivine  Ma  Stevens et a l . ,  1985,  to  i n hand that  i s oblique  this  2-1).  exhibits porphyroclastic texture. a  a  2.8±1.5  i s sodic  found  rubbly  within  b a s a l t s are  (Armstrong,  n o d u l e s were  by  top  z o n e s were  were e r u p t e d  l a y e r shows w e l l d e v e l o p e d  in size  separated  layer  The  t h i c k , the  calc-alkaline  top  Kettle  concordantly.  weathering  (Boyle,  l a y e r s are  Ultramafic  are  f o r nearby  the  i n West  2 meters  flows  4.2±0.5 Ma  orthopyroxene give  spinels  stacked  flows  t h i c k , but  b a s a l t s , while  three  are KR2  and  l a y e r s are  a v e r a g e w i d t h s of  range  study  and  b a s a l t or  (Table  cm  K-Ar  three  subalkaline  50  10 cm  suggesting  1980)  l a y e r s found  each a p p r o x i m a t e l y  t i m e . Two  (Church,  four  flow  River  horizons  The  lava  Elongated  olivine  specimen,  and  foliation to  the  in  thin  foliation  by  Table  S102 T102 A 1203 Fe203T  2-2  Chemical  compositions  WKR1B  WKR2B  WKR3B  WKR4B  KR35B  48 .86 2 . 35 16 . 4 1  49 .31 2 . 22 16 . 6 7 12 . 4 9  49 .61 2 . 17 16 . 6 2 1 1. 6 7  45 .01 2 .94 14 . 6 5  44 2 14 14  12 . 5 3  13 . 4 5  .83 .57 .60  0 . 19 4 .89 9 81 3 . 17  K20 P205  1 . 26 0 . 52  0 . 17 4 . 59 9 . 33 3 . 39 1 . 32 0 . 52  0 . 16 4 .99 9 .66 3 . 35 1 . 26 0 .51  0 8 9 3  . 18 .53 . 29 .46  1 .64 0 .85  and  associated  basalts  (wt%)  LL1B  LL14B  JL14B  BM11B  BM26B  BM55B  47 . 5 9 2 .36 15 8 3 1 1. 6 6  46 . 75 2 . 33 14 . 3 6 13 . 0 4  42 2 13 14  4 1. 80 3 . 19 13 . 0 3 15 . 2 6  43 . 36 3 . 16 13 . 3 8  41 . 4 0 3 . 16 12 . 9 5 15 . 8 3  19. 86 7 13  0 0 4 . 02 4 . 25  0. 0 1 1 4. 2 7 . 69  0. 0 1 1 .5 8 9 . 07  O 0  O .0  O. 0  Hy-En  0. 0 3 75 3 . 93 7 . 80 2 . 79  Hy-Fs  2 . 92  3 . 24 3 . 66 6 . 98 2 6 1 2 . 95  3 3 7 3 2  5 . 23 3 . 19 8 . 86 O. 0 0. 0  Dt - F s DI -Wo  8 . 79 3 .04 1 .99 0 .64  26 . 89 0. 0  0. 0 0. 0 4 . 00 4 . 98  -Fo -Fa -Ca - En  0 .80  0 . 17 7 .94  9 82 16 . 51  0. 0 0. 0 4 . 06 4 . 70  Ne Lc  9 .20 3 .43 1 .44  0 .21 9 .50 4 . 20 1 .65 0 . 79  CIPW n o r m 1 . 88 1 .8 3 1 .50 4 .53 4 .95 5 . 93 5 4 1 2 . 84 2 .28 8 63 9 75 1 1 89 12 . 9 2 17 . 0 5 22 48 14 . 7 5 2 3 . 94 2 0 . 48 1 .9 1 6 .7 1 12 . 2 5  2 7 . 16  1 .2 2 4 52 2 45 7 . 54 2 7 . 15  0 . 19 8 . 44  1 .2 0 4 . 17 2 . 28 7 . 53 2 8 . 67  1 .22 4 .. 2 7 2 . 44 7 . 89 29 . 03 26 . 6 9  01 01 01 D(  44 . 5 3 . 12 14 . 1  host  .21 .58 . 27 .50  13 . 3 1  3 . 73 8 .52  MnO MgO CaO Na20  I 1 Mt Or Ab An  KRB  .50  Fe203 FeO  Ap  of  . 80 . 64 . 60 03 . 91  2 .00 5 . 66 2 63  0. 4 . 3 . 8 .  0 80 42 57  0. 0 0. 0  0. 0 1 1 .0 3 4 . 01  0. 0 1 1 .2 3 7 . 27  0. 0 7 . 92  0. 0 3 . 97 2 . 33 6 . 65  2 . 61 1 1 .4 7 0. 0 0. O  0. 0 0. 0  0 10 7 3  . 18 .50 .93 . 17  1 . 19 0 . 56  1 ,31 4 .. 4 8 2 . 55 7 . 12 24 . 94 21 . 71 1 .2 0 0. 0 1 5 . 94 9 . 04 0. 0 3 . 74 1 .9 2 6 . 02 0. 0 0. 0  0 . 18 7 . 32 15 . 4 3 2 . 14 1 .69 0 .69  1 62 4 97 2 84 0  0  O. . 0 21 . 9 2 9 95 7 . 94 5 . 55 5 . 00 1 . 12 10. 57 8 64 19 . 8 4 0. 0 0. 0  0 . 20 10 6 4 9 .01 3 . 40 2 .60 0 . 87  2 . 6 . 2 . 15.  05 15 99 28  0. 0 12 . 8 1 15 . 8 2 0 . 25 14 . 1 1 8 . 75 0. O 6 . 77 3 . 81 1 1 .19 0. 0 0. 0  0 . 19 .64  10 8 3 2  .95 . 35  0 .21 1 1. 18 8 88 3 . 29  . 79 0 . 87  2 . 29 0 . 83  2 .. 0 4 6 . 08 2 60 16 7 0 3 2 1 13 . 4 1  1 .9 5 6 . 10 3 . 10 13 7 5 0 . 76  13 . 8 2  14 . 0 2 14 . 91  0. 0 14 . 0 0 7 . 25  0. 0 15 . 3 6 9 55  0. 0 6 . 86 3 . 22 10. 78 0. 0 0. 0  0. 6 . 3. 10.  0 37 59 53 O. 0 0. 0  Comment:  KRB d a t a f r o m Fuj11 & Scarfe (1982), others from Armstrong W K R 1 B . WKR2B a n d WKR3B a r e l o w e r l a y e r s of t h e West K e t t l e sequence. They a r e nephelIne-norm f r e e s u b a l k a l i n e b a s a l t s Others are a l k a l i basalts that contain nodules.  (1985, pers. comm.). River eruption that lack nodules.  Method:  A r m s t r o n g ' s d a t a a r e d e r i v e d f r o m XRF a n a l y s e s o f p r e s s e d p o w d e r p e l l e t s using an automated P h i l l i p s X-ray spectrometer in the Oceanography Department of U.B.C. Results are oxidized, anhydrous, a n d n o r m a l i z e d t o 100 p e r c e n t totals. Trace e l e m e n t a n a l y s e s of t h e same p e l l e t s u s i n g t h e same e q u i p m e n t a r e r e p o r t e d in t a b l e 2-3. Major and t r a c e element c o n c e n t r a t i o n s a r e based on c o m p a r i s o n with USGS a n d o t h e r w i d e l y a n a l y s e d I g n e o u s r o c k s t a n d a r d s . M a s s absorption coefficients are c a l c u l a t e d from major element compositions.  26 Table  Ba Cr Nb N1 Rb Sr  an  Concentrations of trace elements-in (from Armstrong, 1985, pers. comm.)  WKR1B  WKR2B  WKR3B  WKR4B  316 81 34  328 103 32 49 17  293 137  470 23 1 66 164  215 23  676 2 17 22  628 204  210  200  49 17 844  V Y Zr  2-3  angle  3 1 48 17  2 1 193  KR35B 397  29 914  803  2 16 25  220 24  319  281  exhibits  protogranular  exhibits  eguigranular  806 149 24 244  to  b a s a l t s (ppm)  J L 14B  L L 14B 4 15 376 48 378  416 324 48 273 29  383 56 270 26  15° t o 3 0 ° , due  of  LL1B  host  2 1 714  569 445 59 386 13 1444  163 23 237  122 28 367  BM1 1B  BM26B 873 454  932 433  BM55B 891 44 1 94  95 335 57  90 397 52  355 54  1231 219 26  1203 24 1 24  1218 268 27  401  391  395  intra-cry s t a l l i n e  glide.  KR 1  t o p o r p h y r o c l a s t i c t e x t u r e . KR35 texture  and shows i n c i p i e n t  m e l t i n g of  clinopyroxene. The  clinopyroxene  enstatite. (Table  i s d i o p s i d e and o r t h o p y r o x e n e i s  O l i v i n e has t h e c o m p o s i t i o n  o f Fo = 90.3-90.6.  3-1, F i g u r e 2 - 5 ) .  (4).  L a s s i e Lake  (2 on F i g . 2-3) ( 4 9 ° 3 5 . 8 ' N ,  118°55.3'W) Lassie  Lake  i s near  n o d u l e s a r e exposed basalt K-Ar  from nearby b a s a l t  (Christopher, 5.9±0.6 Ma inferred  The  nodules,  Kettle  River,  alkali  picriic  field  (Christopher,  work. T h r e e  1977,1978) and  t h e same age a s t h e West  olivine  basalt  in size  t o n o d u l e LL1 i s  b a s a l t and t h a t  (Armstrong,  w e a t h e r e d and s m a l l e r range  by L a s s i e L a k e . No  a r e 4.7±0.2 Ma  l a v a s . The l a v a a d h e r i n g  series  l o c a l i t y . The  1980, S t e v e n s e t a l . , 1982). The l a v a i s  t o have a p p r o x i m a t e l y  series  during  flows  1978), 5.0+0.2 Ma  (Boyle,  River  potassic sodic  on a g r o u p o f h i l l s  s t r a t i g r a p h y was o b s e r v e d  dates  Kettle  t h e West K e t t l e R i v e r  than  t o LL14 i s  1985, p e r s . those  f r o m 2 t o 15 cm.  comm.).  from West  The Table  two  2-1)  texture. average  lherzolite  selected  LL1  nodules  for this  (LL1  study  and  exhibit  shows c o n s i d e r a b l e m e l t ,  brownish  alteration  LL14)(Figure  protogranular  LL14  (iddingsite?)  2-4,  has on  more  than  grain  boundaries. The  clinopyroxene  enstatite. (table  11-2.  Olivine  3-1,  Figure  Josephine The  (Figure  lithic  Irwin's  western  wide and  over  variety  of  The west w i t h and  km  of  lies  Belt.  There belts  of  89.7  and  along  the  margin  of  km  s h a l e , greywacke, Rogue F o r m a t i o n s , River  included  a  Gabbro.  c o n t a c t on  F r a n c i s c a n t e r r a n e s of t h e  Ranges. T h e s e  (i960,  some 8 t o 32  Illinois  is in fault  south  Irwin  the western  the G a l i c e and  Peridotite  Coast  California  s i x major n o r t h -  i s composed of  r o c k s , and  t h e Dothan and  limestone  =  i n Klamath  Northern  This belt,  d i s r u p t e d melange of g r e y w a c k e , chert,  of Fo  have been d e s c r i b e d by  long,  rocks  intrusive  California  Oregon and  Peridotite  Josephine  is  Oregon  is situated  mountains  Jurassic  metavolcanic  the composition  of S o u t h e r n  Peridotite  belts  320  orthopyroxene  2-5).  In t h e s e  1972). J o s e p h i n e  and  has  southwestern  2-6).  elongated  of LL1  Peridotite  Josephine  M o u n t a i n s of  i s d i o p s i d e and  the Oregon  tectonically  shale, metavolcanic  rocks,  serpentinite.  i s g e n e r a l agreenment  that rocks  the Klamath Mountains r e p r e s e n t  i n the  arcuate  f r a g m e n t s of  island  28  Fig. 2-6  a r c s and o c e a n  Generalized tectonic sketch P e r i d o t i t e and i t s v i c i n i t y • - sample l o c a l i t i e s .  basins  that c o l l i d e d  margin  (e.g., Hamilton,  Cowan,  1974).  The  Josephine  extending  continuously  with  1969; I r w i n ,  Peridotite,  map o f t h e (from Dick.  the c o n t i n e n t a l  1972, S c h w e i c k e r t  covering  f o r almost  Josephine 1975).  nearly  150 km a l o n g  650 km  and  2  and  the western  edge o f t h e K l a m a t h S t r u c t u r a l A r c , i s one o f t h e l a r g e s t bodies  of u l t r a m a f i c rock  The fresh  peridotite  peridotite  i n the world.  i s commonly  10 t o 30% s e r p e n t i n i z e d . The  consists largely  o n l y a m i n o r amount o f i r r e g u l a r l y volumetrically An  insignificant  of h a r z b u r g i t e ; t h e r e i s distributed  orthopyroxenite  e x t e n s i v e l y p e t r o l o g i c study  d u n i t e and  and  was c a r r i e d  lherzolite. o u t by  Dick  29 (1975) i n t h e a r e a is  the  in  t h e m a n t l e and  stages  s a m p l e d . He  r e s i d u e of a t  of  least  that  two  suggested  t h a t the  episodes  i t i s the  of p a r t i a l  relict  t h e c o n s t r u c t i o n of a c i r c u m  peridotite  of  the  melting  earliest  - oceanic volcanic  sequence. Four for  this  samples study.  from  Josephine  Peridotite  They a r e a l l h a r z b u r g i t e  were  selected  ( F i g u r e 2-4,  Table  2-1). JM2  from  Vulcan  protogranular  Peak  (42°11.0'N,  t e x t u r e . There  123°59.0'W)  i s moderate  serpentinization  along mineral  cracks. Original  minerals  boundaries  are mainly  exhibits  (~15%) and  olivine  mineral and  orthopyroxene. JM14  from  Eight Dollar  Mountain  (42°15.4'N,  exhibits  porphyroclast texture. Elongated  prefered  orientation  clasts minor  are  products  and of  obvious  kink  fragmentation.  olivine  bands.  123°41.0'W) has  Orthopyroxene  Serpentinization is  (2-3%). JM5  original  and  JM15,  from  Eight Dollar  Mountain,  p r o t o g r a n u l a r t e x t u r e o v e r p r i n t e d by  fragmentation. Diopside abundance  also  S e r p e n t i n i z a t i o n i s minor occurs  as  small anhedral  i n a l l samples.  later  (~5%)  grains in  low  exhibit  30  I I I . CHEMICAL MINERALOGY  Three prepared the  polished  for  wavelength  University  section,  two  Laboratories  Knight Ross  were  15 J.  kv  40  and  J.  Knight.  repeated  at  5  Appendix  1 and  contents  of  formula  6  The In  2).  the  chemical  composition.  used  the  following  nodules  in  this  Clinopyroxene (Appendix same  manner  (Table those  3)  3-2).  were as  to  and  the  in  our  No  points. in  grains  The  plots  Sr  J.  prepared  by  J.  were  Table  3-1.  Fe  a  M  chemical  grains  2  and  +  2 +  M  in  gave for  in  3 +  Fe  each  or  each  the  3 +  0„  zonation  and,  analyses  p r o v i d e d by data  mineral  are  isotope  discussion  by  are  thin  same mineral  from study,  because  the  for  was  several  J.V.Ross.  from  Dick  (1975)  compositions  Columbia nodule data  guided  data  orthopyroxene  the  and  calculations.  were  to  was  The  orthopyroxene study  thin  Research  analyses  value  and  at  Quantameter  were  analysed  average  were  polished  assuming  mineral  ,  clinopyroxene  work  the  LL1  analysis  Applied  used  significant  B r i t i s h  this  The  calculated  calculated  Although  involved  pertinent  and  an  grain,  formulae  mineral  Clinopyroxene other  each  within  section,  for  A l ) .  and  each  Microprobe  standards  were  found two  (on  scattered  spinel  was  nA  In  spinel,  using  Electron  KR2  microprobe  Columbia.  olivine,  mineral  (Appendix  variation  of  KR1,  dispersive  analysed,  Rice.  to  sections,  B r i t i s h  Scanning  at  and  of  grains  orthopyroxene  operated  thin  mineral  samples they  in  analyses  other  are  Josephine  the  than  s t i l l Peridotite  rr 73 73 ~~ r o O O  i cn i n  o oo  1 C/) i —•  _k ~ j cn CO CJ ro O  O O  O O b O  u  O  i  >  —  ->  5  ~* r o  o o  o o  o  to to ro — — 01 CO CO u i o  O  o O o to o  O  b O b o CO Ul Ul  -n ID + +  + +  &  o  o  O O O O o O o o o ro ro O o  O O b O O o CO CO 00  i.  00 CO CD CO O O CO CD  •o. ~4 oo 03 CO IO  ~J  cocooococoooooao  O O O O O O O O O O  O  — — r o — — M-k — r O W — oorocnroco^ooo —  — r o c j r o — CJ CJ CJ 4 . 0 0 O — -J. r o r o —  O O O O O O O O O O  O  O O O O O O O O O O O O O O O O O O O O Oro-fc-o — c j r o c j c o c j  o b o o o b o o o o - o o - - — o o o i r o o i r o o o i  ^ 2  CQ + Tl  IS X  co — CO  o 1  > • — X  8  O  O  O  O  O  O  O  O  O  O  O  O  O  O O O O O O O O o b b b b b b b -joooo-jcncooooo oi-4-.OJ^O~Jlo  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  b b b b o b b b b o  b o o b b g b b  O  O O O O O O O O C J C J C J C J r o c j c j r o  O  O  O  O  O  O  O  O  O  jk.u.fc.u.uai.c.OT-fc-ui  O  O  O  O  O  O  O  O  -ocncn^i^icncncncncn £>oico.b0~>cooocncn^i  O O 0 1 U b - > I C D  O  O  O  O  O  O  O  O  O  O  O  o o b o o o b b b o u u u r j u & u r o u u — 0 0 0 1 — rO — O l - U C O - E i  C O C D - J O O O D C O ^ J - J  O  O  O  O  O  O  O  00 -g oo 00 ~ j -g 01 co c o c o c o c n c o O  O  0  — .  01  —  O —  O  O  O  O  O  O  o b - :o Co co ro co 0001C0O1-403  O O O O O O O O O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  O  01  ro ro —  O  O  4^  —  —. — co  o o o o b b o b c o r o r o r o c o — roro o i oo — - J o -4 O w O O O O O O O O  O  O  O  O  O  O  O  O  o o b o o b o o b b o o o cn  cnoidioioioicnoicncn  o  . CO — co 01 TO  O  — — — — — — r o r o — r o cnOOCD^lOlCOOCJCOO C D O ^ — 00£». — . U C J O  O O O O O O O O Q O  cnoicncncncncncn  aicn~si^i~joioo~4  o o  ^ O C D * - O I ~ J O O O O  O O O O O O O O O O  O O O O O O O O O O 0 0 0 0 0 0 0 - - 0 coaicocnoi-j^joocxj  "1  2 CQ  o T j c . 3 3 2 1 Ol — — u i cn -u  cocooococooococsoooo co — oo — c o o o r o c o c o - o .  O O O O O O O O O O  o  £.  o  •n  o o O ro CO 01 01 ro  01 — -1  CO CO  o O o o O o CO CO CO  O  r - r - x x x c n 1 - 1 - 7 3 7 3 7 — CJ . ui ro —  —. o  CO O CO CO O CO CO 00 01  •o. oo oo 00 o Ol oo 3E CO  r r X T v X o i i B c c c i - i - 7 3 73 73 S 2 r - r - r — cn to — cn — oo oi .u  • _^  Q b b O o 5 ro r o &  -j -j ~i co CO  73  -* r o  O  O O o  -  r~  O  O  b b b o o g  r  aiuico — — rooorooioo  ai co co co co  OOOOOOCQCOOOOOOOCDOO C O O O - J O O ~ J ~ J 0 1 C D - J  i D o ^ a o o a i c n ^  -JCO-J —  ro.&^icnro^i  O O C O O O O O O O O r O O O  MOAombcnMuui  — O  COCOroOI&CS-JUl  •COl-fcACOOlOIOl —. ro co  — >i t u  6  32  has  limited All  variation  in mineral  the analyses  percent  total  composition.  r e p o r t e d sum  t o 98.1-101.0  weight  oxide.  01ivine The and from and  composition  Josephine  Peridotite  F o  8  9  7  ,  i n B r i t i s h Columbia  i s s t r i k i n g l y uniform.  KR1,KR2 and LL1 have respectively  have a range with  of o l i v i n e  f o r s t e r i t e contents  an a v e r a g e  F o  9  0  (Dick,  . 3  from  and  Clinopyroxene  and o r t h o p y r o x e n e  Peridotite  Fo  F o  B  9  5  9 0  .6 > Fo  9  0  olivines to Fo , 9  7  ,  orthopyroxene both  i n nodules  a r e C r - d i o p s i d e s and  enstatite,  and i n  respectively. Clinopyroxene  i n nodules  En=46.7 t o 49.3, Fs=3.7 Peridotite  varies  Fs=3.5 t o 4.6  Wo=45.7 t o 48.1, in Josephine  Wo=45.9 t o 46.9, En=48.7 t o 50.4, and 3 - 2 ) .  i n nodules  Peridotite  90.6 and Fs=8.0  varies  varies  t o 9.0  from  ( T a b l e 3-1  T i p e r d i o p s i d e and e n s t a t i t e  ploted  from  from  Wo=1.1  t o 90.2 and Fs=8.6 t o 12.2. O r t h o p y r o x e n e  Josephine  and  varies  t o 5.4. C l i n o p y r o x e n e  ( T a b l e s 3-1  Orthopyroxene En=86.6  from  i n F i g u r e 3-1  . 3  1975).  Clinopyroxene  Josephine  Olivines  (Table 3-1). Josephine  of f o r s t e r i t e c o n t e n t  nodules  (after  t o 2.2, in  Wo=1.2 t o 3.5, En=87.7 t o a n d 3 - 2 ) . Numbers  of Cr  formula  been  Ross,1983).  unit  have  Table 3-2 •Josephine P e r i d o t i t e pyroxene compositions  (data from Dick,1975)  SI  Al  TI  Fe  Mg  Ca  Cr  0  Wo  En  Fs  J28f J871 J120 J120  1 .89 1 .92 1 .89 1 .93  0 168 0 099 0..209 0 090  0 0011 0 OOOB 0 .0041 0 .0014  0 0854 0. 0730 0 .0848 0 .0699  0.93 1 OO 0.90 0.99  0 89 0 91 0 .85 0 .92  0.043 0.029 0.032 0.020  6 6 6 6  46.9 45 9 46 4 46 5  48 7 50 4 49 0 49.9  4 5 3 7 4.6 3.5  Opx  SI  Al  TI  Fe  Mg  Ca  . Cr  0  Wo  En  Fs  6 6 6 6 6 6 6  3 3 2 2 2 1 1  Cpx  J28f J46h J46h J871 J114 J120 J46g  1 .90 1 .92 1 .90 1 .94 1 .90 1 .91 1.93  0 . 146 0 .0005 0. 134 0. 0010 0. 131 0.O010 0. 094 0 0003 O.085 0 OOOS 0. 093 0 0005 0. 039 0 OOOB  0 . 1756 1.71 0 .063 0.025 0. 1662 1 .69 0. 067 0.024 0. 1685 1 .74 0. 052 0.023 0. 1653 1 .75 0 041 0.015 0. 1775 1 82 0 041 0.014 0. 1793 1 .82 0 022 0.012 0. 1636 1 .86 O 030 0.015  Table 3-3 Comparison of pyroxenes of d e p l e t e d and undepleted Mg/(Mg+Fe)x100 Cr/(Cr+A1)xlOO D e p l e t e d nodules Diopside 92.2-92.9 E n s t a t i t e 91. 1-91 .3 * Undepleted Diopside Enstatite  nodules 89.8-90.5 87.7-90 2  Josephine p e r i d o t i t e Diopside 91.4-93.4 Enstatite 90.7-91.9  11.4- 19.7 6.8-15 5.0- 9.1 4.1- 6.1  Cr/TI  Al  nodules  2 5 6 1 0 1 4  87 87 88 89 89 90 90  and Josephine  T1  9 O 8 6 8 6 8 4 8 7 8 9 8.0  7 8 8 5 3 0 6  Peridotite  Cr  Na  7 .6-13.5 0 . 14-0 21 0.001-0 .005 0 .027 -0 .038 0 .050 0 099 12-40 0 . Il-O 15 0.0004-0 0O2 0 O i l -0 .024 O .003- 0 007 1 .4-3.5 3-3.7  0 .28-0. 32 0 .18-0. 23  0.008-0 .016 0 .017 -0 .028 0. 111- 0 138 0.002-0 .004 0 .009 -0 .012 0. 006- 0. 010  13.1-22.6 7 .7-39.4 0. 09-O. 21 0.001-0. 004 0. 020 0. 043 11.3-27.7 23 .6-50.4 0. 04-0. 15 O.OO03-0.001 0. 012 -0. 025  Fig.  3-1  Ti-Cr  plots  of  dioosides  a"<s  e n s t a t i tes  35 From F i g u r e a.  Most  3-1, we d e r i v e  of d i o p s i d e  the f o l l o w i n g  underwent more  conclusions:  intensive Ti  metasomatism than e n s t a t i t e . b.  LL14 and KR2 a r e d e p l e t e d m e t a s o m a t i s m . KR1 Ti  c ..  nodules without T i  and BM11  are depleted  nodules  metasomatism.  BM16  i s undepleted  JL14  and BM55 a r e u n d e p l e t e d  without  T i metasomatism,  with  d.  unspecified to lack  falls  data.  on t h e boundary  of d e p l e t e d  u n d e p l e t e d . E n s t a t i t e i n d i c a t e s somewhat character.  Because e n s t a t i t e c o n t a i n s  than d i o p s i d e , probably e.  The  the c o n t r a s t  and  depleted  l e s s Cr and T i  i n assignment i s  not s i g n i f i c a n t .  A l l pyroxenes strongly  nodules  T i metasomatism, t h e u n c e r t a i n t y  of d i o p s i d e  LL1 d i o p s i d e  KR35,  nodules with T i  m e t a s o m a t i s m . J.L15 and J L 1 8 a r e u n d e p l e t e d  due  with  f r o m J o s e p h i n e P e r i d o t i t e a r e of  depleted  character  d e g r e e of d e p l e t i o n  without  T i metasomatism.  i s l a r g e r than  that  of t h e  nodules. In  graphs of C r / ( C r + A l ) x 1 0 0 v s . A l ( F i g u r e  Mg/(Mg+Fe)xl00 v s . C r / ( C r + A l ) x 1 0 0 undepleted In (Figure diopside are  groups a r e s h a r p l y  (Figure  3-3), depleted  the d e p l e t i o n  trend  i s well  diagram  defined.  Mg/(Mg+Fe)x100 v s . C r / T i d i a g r a m d e p l e t e d  somewhat more s c a t t e r e d  and  separated.  t h e e n s t a t i t e Mg/(Mg+Fe)x100 v s . C r / T i 3-4(a)),  3-2) and  (Figure  3-4(b)),  In t h e  nodules  p r e s u m a b l y due  Al o  ,  0.10 1—  Atoms per  0.14  Formula 0.18 i  1  0.22 I  •  u  c .r—  I  ro I  S  * (  roo ~~  0.26 I  0.10 I  I  00  ui »  rt l»  a.  TO  K>'  O  to A  i  1* *. a1 3=  1  »—  rt  >  X  o o  1 "* x  Ft  o  / / /  a.  c  r r  j 1  XI  /  O O  1  / /  /  " <  z  OJ  ai  37  Dlopside  •JL  • KR3S bt\dep l a t e d  •A,  \ \  * — LO  15  3-2(b)  Cr/(Cr+Al)x100  vs.  Al p l o t  of  —  20  Cr/(Cr+Al)xl00 Fig.  -  T —  I  diopsides  /  Dlopside  I  •KR i ,  ,--"/ /  Djpl«t«<l  No4ul»  /.  •1-KR2  ' !  /  , , ,  /  'LL14 ,  "/  ,  '  do»«phln«  Perl dot  11«  "  «'  .'•KR35\ '.BM55 B M 1 6 !  -'jL1-4'  15  10  _  -0  25  Cr/<Cr*Al)xl00  Enstat 1 te  ____  ~  -  4  — -  "  . -LL1  B M 1  ,. f-KR35 ~JL 14  .BM11  6  J L 18  5  15  !0  JO  25  50  Cr/(Cr»»l)«100  3-3 C r / ( C r + A l ) x 1 0 0  vs  Mg/(Mg+Fe)x100 p l o t  of d i o p s i d e s  and enstatlt«a  39 to v a r i a b l e The  c o m p o s i t i o n ranges of pyroxenes  undepleted Table  T i metasomatism.  n o d u l e s and J o s e p h i n e P e r i d o t i t e  3-3. In e v e r y c a s e t h e a s s i g n m e n t  specimens  i n d e p l e t e d and  c a n be made w i t h o u t  of  are given i n individual  contradiction.  Spinel Only  three  composition. spinel was  There  grains  was no s i g n i f i c a n t  a n a l y s e d i n each  chemical variation  (Table  among s p i n e l s  between two  (Appendix  1 and 2),nor  from t h r e e  In  the Cr/(Cr+Al)x100 v s . Mg/(Mg+Fe *)xl00 p l o t 2  the nodule  spinels  l i e on t h e l o w e r  of the Josephine P e r i d o t i t e  trend.  and t e m p e r a t u r e e s t i m a t e s  Pyroxene  g e o t h e r m o m e t r y and g e o b a r o m e t r y  ultramatic Mercier  parageneses  and C a r t e r ,  theoretical involving  (Wood a n d Banno,  1975; M e r c i e r ,  derivations  enstatite,  techniquesf o r  1973; Wood, 1975;  1976) a r e b a s e d on  f o r s e t s of e q u i l i b r i u m  diopside  (Figure  (less depleted)  Pressure  spinel  nodules.  t o 0.265, Cr=0.266 t o 0.647.  2 +  3-5),  nodule  variation  3 - 1 ) : Al=1.319 t o 1.729, Mg=0.742 t o 0.789,  Fe =0.213  end  n o d u l e s were a n a l y s e d f o r s p i n e l  and ah a l u m i n o u s  reactions phase,  either  or garnet.  Based  on w o l l a s t o n i t e  Al-concentration generalized  solid-solution  in co-existing  the pyroxene  enstatite,  i n d i o p s i d e and Mercier  techniques to derive  both  (1976)  Cr/Tl 10 I  20 __1  30  i  AO  Diopside  '  N  / • \ L U 4  ^ '\  I \ I I \ I I 1 II  \  I  s  \  I  9C  \  o  I I I  I  \  \ \  \  \  • KR2 \  \  ' \  \  Undeleted JL14  88  39  /  §  M , '  L 6  L  ,  \  V.-.BM55*-90  I "--VKR1  R35  91  92  Mg/(Mg+Fe)xl00  g.  3-4(b)  Mg/(Mg+Fe)x100 v s . Cr/T1 p l o t  of d l o p s i d e s  93  42  MO to •0  70  •  •0 -  Cr x 100 Cr + AI  so  40  10  SO  10  100  60  40  Mg x 100 Mg + F . F1g.  temperature analysis, inferred  3-5 Mg/(Mg+Fe++)x100 v s . C r / ( C r + A I ) x 1 0 0 p l o t o f s p i n e l ( J o s e p h i n e P e r i d o t i t e d a t a f r o m D i c k , 1975)  and p r e s s u r e the composition  from  on t h e b a s i s  this analysis  c o e f f i c i e n t s . This  partially  altered  p y r o x e n e s and s p i n e l by M e r c i e r  (1980).  and from  single-pyroxene phases  empirically  being  determined  method c a n be a p p l i e d t o  or r e e q u i l i b r a t e d  assuming  of a  of t h e c o - e x i s t i n g  partition  xenocrysts,  + +  f a c i e s and t o  original equilibrium or garnet.  between two  The method has been  revised  43 Temperature obtained  and p r e s s u r e e s t i m a t e s a r e i n d e p e n d e n t l y  t h r o u g h t h e use  of t h e g e n e r a l  equations  (Mercier,  1976): T =  [AH  P = [AH in  a  (v'+v"lnK')-AH (v'+v"lnK')]/D ww w w a a a  a  (RlnK'+AS )-AH w w w  which,  D=  (RlnK'+AS ) (v ' + v" InK ' ) -•( RlnK' +AS ) ( v ' + v " l n K ' ) a a ww w w w a a a pertinent  coefficients  thermodynamic  K' and w  Mercier's been of  used  British  Data  pyroxene  T,  P,  do  systematically  J  by J.V.  were u s e d  depth c a l c u l a t e d  h i g h e r v a l u e s than p r e s s u r e and  p o i n t s . There  is likewise  partition  inconsistency  may  and  o r due  enstatite  coefficients  Considering Chapter V ) , the  the w e l l  and  be due  from  through  in Table  3-4. for diopside  calculation  gives  d e p t h v a l u e s from J.V.  analytical  between d i o p s i d e  has  diopside.  from d a t a  diopside  (1980)  calculation.  seperately  4) were d e r i v e d  The  (1980)  Ross.  f o r the  (Appendix  inconsistency  partition  t e m p e r a t u r e and p r e s s u r e  not a g r e e : e n s t a t i t e  Temperature,  the  thermobarometry  and d e p t h a r e l i s t e d  P and  enstatite  by M e r c i e r  equilibrium  "PGEOTH" p r o v i d e d  T,  and  n o d u l e s and J o s e p h i n e P e r i d o t i t e  i n T a b l e 3-1  Calculated The  refined  Columbia  parameters  K' a r e g i v e n a  to c a l c u l a t e  the program  and  (RlnK'+AS ) ] / D a a  for  Ross  individual  a degree  of  enstatite. to d i s e q u i l i b r i u m  to s i g n i f i c a n t  between  deviation  of  t h o s e of M e r c i e r ( 1 9 8 0 ) .  defined  inconsistency  mineral isochrons  seems u n l i k e l y  (see  t o be due  to  44  Table  3-4 C a l c u l a t e d  Mercler CPX P  T  D  disequilibrium In  1006 1002 1057 1089 1062 1025 1093 113 1  Modi f i e d  OPX P  0  16 . 75 55 16 .82 55 18 . 10 59 20 . 18 65 18 . 16 59 17 . 18 56 13 . 37 44 20.,97 67  12 15 1 123 998 1114 1235 1 169  20. 79 23 .97 18 .79 24 .50 22 .67 19. 27  CPX I?  T .0 . 2 . 1 . 4 . 3 .3 .8 . 8  1 1 . 49 14 .43 13 . 42 13 . 76  936 975 999 995  937  1 105 19 . .21 62 . 5 1068 19. 1 1 62., 1  between  Mercier's  P ( k b ) a n d Depth(km)  (1980)  T  KR#1 9 4 0 1 1 . 7739.9 KR#2 929 1 1 .49 39 . 1 LL#1 1004 13. 72 45 .8 JL14 995 13 . 74 45.9 JL15 JL18 8M1 1 BM1S 9.81 34 .0 940 BM55 1053 16.95 55 . 6 949 10.90 37 . 3 KR35 L L 1 4 1012 16.52 54 . 3 Josephine p e r i d o t l t e J 2 8 f 1000 11 . 34 38.6 J871 1040 19.67 63.9 J 1 2 0 1010 20. 46 66 . 3 J114 J46h J46h  T(°C),  39 48 44 45  OPX  1P  T . 1 .0 .9 .9  9 . 56 33 .2  936 974 998 995  12 14 14 13  D  .02 40.. 7 . 88 49 . 3 .03 46 . 8 .64 45 ..6  939  7 . 92 28 .2  ' 947 10 . 77 36 .9 950 1009 16 . 34 53 8 1008  8 . 70 30. 6 15 . 18 50. 3  67 .. 2 76 ..9 61 . 2 78,.5 72 .9 62 ,6  1005 1042 1013  diopside  D  1 1 .62 39.. 5 1002 7 .62 27 .3 19 . 80 64 .. 2 104 1 18 . 38 60. 0 20 . 72 67 .0 101 1 19 . 72 G4 .0  and e n s t a t i t e .  thermobarometer,  thepartition coefficient  K' f o r E n a n d D i s o l i d - s o l u t i o n s w Mg Si 0 2  2  Di  is  Mg Si 0 2  En  ss  given  where, the  =  6  by K ; = ( X ^ ) d i / ( X ^ ) e n  W = Ca/(Ca+Mg+Mn+Fe  plotting  qot ^  a value  for  enstatite,  for  diopside, If  of W  data  e n  )  2 arises  from  solution. inW  /(0.5-w,.)=0.333 en d i  v s . 0.5-W ,  g n  di  Mercier  for spinel-facies.  Thus  K' =6.000W(1-2W) w  i sa large  will  calculation  d  ) and the factor  of Fe s o l i d mineral  ( i-2W . )/(1 -2W  w  difference  diopside  ++.  =  K =(1-2W)/(0.667+0.667W).  there  enstatite the  6  ss  consideration By  the  2  between  deviation  from  calculated  w e  n  from d i o p s i d e  be s i g n i f i c a n t . F o r e x a m p l e ,  calculation gives  gives  K =0.07i5, w  / ( 0 . ) = 0 . 3 3 3 , and from  f o r n o d u l e LL14,  but the enstatite  45 K'=0.0989. T h i s w  difference  i s t h e main  source  of the  inconsistency. When c o e x i s t i n g available, reliable.  F o r example,  w  s i n g l e pyroxene  thermobarometer  has been  pyroxenes data are  = (1-2W,.)/(1-2W ) . O t h e r w i s e , we w di en c a l c u l a t e , f o l l o w i n g M e r c i e r , IT =6. 000W( 1-2W) f o r e n s t a t i t e and K'=(l-2W)/(0.667+0.667W) f o r d i o p s i d e . The r e s u l t s w derived  we t a k e K  be more  f o r n o d u l e L L 1 4 , K =0.072.  f o r t h i s s t u d y . When c o e x i s t i n g  availble,  data are  c a l c u l a t e d K'=(1-2W,.)/(1-2W ) will w di en  Thus M e r c i e r ' s modified  e n s t a t i t e and d i o p s i d e  1  by t h i s m o d i f i c a t i o n  are also  listed  i n Table  3-4.  46 IV. Rb-Sr  IV-1.  ISOTOPE ANALYTICAL METHOD  Sample p r e p a r a t i o n  (1 ). N o d u l e s Only study.  relatively  Small  removed by  basalt  fresh  hand p i c k i n g  after  the  to  16 mesh, and  than  whole r o c k  was  split  further  was  mesh and than  then  about The  150  used  The  Rb  40-16  crushed  ground  Quartz  and  Sr  than  on  a hot  process  1  to get  procedure  fraction  r e s i d u e was  of  s e p a r a t i o n . The steel  removed  mortar  mortar  the whole  rock  to pass  40  mortar  for doing  to  less  was  while heated  allowed  washed w i t h Q u a r t z  to stand  H 0  H 0  were d r i e d .  The  resulting  2  is defined in section  three  2  and  for  the  the  grams of d r y for 6 hours  i n a pyrex  HC1  This  s u r f a c e s of  values  20  2  t o 80°C  the  contains  this i s :  H 0,  1  minerals.  from  true chemical  p l a t e . The  "Quartz-"  fraction  the p r i s t i n e  washing w i t h Q u a r t z  HC1  mesh  m a t e r i a l in u l t r a m a f i c rocks  i n order  mesh s i z e  were  mesh.  minerals  After  nodules  in a s t e e l  i n a motor d r i v e n a g a t e  must be c o m p l e t e l y  The  this  crushing using a  reduced  i n the  material  minerals.  to the  for  5 gram samples were s e t a s i d e f o r  for mineral  interstitial  much h i g h e r  initial  same sample was  analysis.  remainder  were s e l e c t e d  fragments adhering  hammer. Next less  nodules  used  times  in  6N  After  i t was  2-(2).  were u s e d  the  dried  in this cleaning  chlorides  IV  beaker.  40-16  for  47 "acid-leach weights LL14  material"  a n a l y s e s . The a c i d - l e a c h  of J L 1 4 , J L 1 5 , J L 1 8 , BM11,  were t a k e n as t h e w e i g h t  before  and a f t e r  weights  o f KR1,  BM16,  BM55, KR35,  difference  and  between t h e sample  t h e l e a c h i n g . The a c i d - l e a c h KR2  material  and LL1 were d i r e c t l y  material  weighed  from  dried  chlor ides. From  the d r i e d  orthopyroxene binocular free  for  analysis.  that  no f i n e  H 0 2  and e x s o l u t i o n  E a c h m i n e r a l s e p a r a t e was  (e.g. magnetite  an hour  i n an u l t r a s o n i c  on a h o t p l a t e  (80°C)  and  chosen  in a  t o ensure  spinel) ) were l e a c h e d  i n small  pyrex  and  beakers f o r  t o remove any c o n t a m i n a t i o n from h a n d l i n g  hand p i c k i n g .  the agate mortar  The r e s i d u e s were washed w i t h  to less  h o o d . The a g a t e m o r t a r  than  Quartz  were t h e n g r o u n d i n  150 mesh i n a l a m i n a r a i r f l o w  was washed w i t h u l t r a p u r e  acetone  samples.  (2). Josephine Approximately  Peridotite 50 grams of e a c h  t h r o u g h a jaw c r u s h e r and r o t a r y than  surfaces  l a m e l l a e were then ground  a  b a t h f o r 15 m i n u t e s  t h r e e t i m e s and d r i e d . The r e s i d u e s  between  olivine,  under  with c l e a r  t o 100-40 mesh and r e e x a m i n e d  inclusions  6N Q u a r t z HC1  during  those g r a i n s  The p u r e m i n e r a l s e p a r a t e s ( >99.5%  then p l a c e d half  inclusions  agate mortar  remained. with  from  2 t o 4 grams o f  and c l i n o p y r o x e n e were hand p i c k e d  microscope. Only  and  clean  l e a c h e d sample  40 mesh s t a r t i n g  sample were p r o c e s s e d  pulverizer  to give  m a t e r i a l . The 80-40 mesh s i z e  less fraction  48 was  passed  through a Carpco  remove m a g n e t i t e density  iron  roll  fraction  Four  fractions  Examination  (from the c r u s h e r s ) .  u s i n g methylene  Different  iodide  diluted  by  lower  density  were  of s u c c e s s i v e l y  under  fraction  a binocular  was  free  of  a c c e s s o r y m i n e r a l s . I t was  microscope  used  for further  s e p a r a t o r . The  c o n s i s t e d mainly  of c l i n o p y r o x e n e ; t h e  olivine;  and  the  Unwanted m i n e r a l s i n t h e n e a r l y removed by hand p i c k i n g . concentrates grinding  The  pure  t h e n went t h r o u g h  procedure  pure  that  with  fraction  "magnetic"  fraction,  the  other  separation  fraction,  orthopyroxene.  m i n e r a l s e p a r a t e s were  (>99%) m i n e r a l  t h e same l e a c h i n g  as d e s c r i b e d  collected.  and  "non-magnetic"  "weak m a g n e t i c "  80-40  acetone.  indicated  serpentine, spinel  a Franz magnetic  of  separator to  f r a c t i o n s were s e p e r a t e d f r o m a w a t e r - w a s h e d  mesh  second  and  magnetic  and  for mineral separates  from  nodules. Evaporation out  in a laminar  IV-2.  and  grinding  f l o w hood t o a v o i d  Chemical  ( 1 ) . Laminar The  final  were  carried  contamination.  Procedures  f l o w hood  l a m i n a r f l o w hood was  e v a p o r a t i o n s and  procedures  filament  from  the dust  seen  i n T a b l e s 4-1  loading  i n t h e a i r . The and  4-3  used  and  for a l l acid  to avoid  blank  contamination  improvement  can  F i g u r e s 4 - 3 ( a ) and  been  4-3(b).  49 (2).  Reagents  B e c a u s e o f low Rb and S r c o n c e n t r a t i o n s i n u l t r a m a f i c rocks,  contamination  dissolution to  reduce  double  "Quartz"-  glass  still.  quartz glass  f o r sample  h a s t o be m i n i m i z e d .  In o r d e r  Vycor  -  HC10, and " Q u a r t z " - and "2B"- r e a g e n t s refers  to reagents d i s t i l l e d  "2B"- r e f e r s  temperature  Quartz  used  c o n t a m i n a t i o n , o n l y G. F. S m i t h  distilled  used.  is  reagents  and column e l u t i o n  this  subboiling  from  2  still.  i n a quartz  to reagents d i s t i l l e d at  in two-bottle teflon  H 0: prepared  were  by r e d i s t i l l i n g  Rb b l a n k  stills.  distilled  H 0  in a  2  i s 0.013 ± 0.003 n g / g , S r b l a n k  0.072 ± 0.002 n g / g . 6.2 N Q u a r t z  reagent then 0.015  HC1: p r e p a r e d  by d i l u t i n g  analysed'  HC1 w i t h an a p p r o p r i a t e q u a n t i t y o f d i s t i l l e d  distilled  in a quartz glass  ng/g, Sr blank 2.5 N Q u a r t z  still.  confirmed  HC1: p r e p a r e d  by 1N NaOH t i t r a t i o n .  Sr blank  2  i s 0.020 ±  by d i l u t i n g  6.2 N Q u a r t z  HC1  H 0 . The n o m a l i t y was  Rb b l a n k  2  i s 0.014 ± 0.010  i s 0.17 ± 0.02 n g / g .  1.5 N Q u a r t z  HC1: p r e p a r e d  by d i l u t i n g  w i t h a p p r o p r i a t e q u a n t i t y of Quartz confirmed  Rb b l a n k  H 0,  i s 0.64 ± 0.32 n g / g .  w i t h an a p p r o p r i a t e q u a n t i t y o f Q u a r t z  ng/g,  'Baker  by 1 N NaOH  6.0 N Q u a r t z  HC1  H 0 . The 1.5 N v a l u e was 2  titration.  HC1: p r e p a r e d  by d i l u t i n g  w i t h a p p r o p r i a t e q u a n t i t y of Quartz c o n f i r m e d by 1 N NaOH  6.2 N Q u a r t z  titration.  6.2 N Q u a r t z  HC1  H 0 . The 6.0 N v a l u e was 2  50 2B  HF:  Reagent still. 0.21  HF Rb  prepared  at s u b b o i l i n g blank  temperature  i s 0.051  Analytical  in two-bottle  ± 0.032 ng/g,  Sr b l a n k  teflon  i s 0.27  ±  HClO«  was  ng/g. H C 1 0 « : G.  used.  Rb  0.20  F.  blank  Smith  Vycor  - double  i s 0.020 ± 0.011  ng/g,  distilled Sr b l a n k  i s 0.39  ±  ng/g. All  Rb  by d i s t i l l i n g M a l l i n c k r o d t  and  N HC1  reagent  Sr  s p i k e s were m i x e d w i t h  was  loaded  used  into  separation. include  b l a n k s were d e t e r m i n e d  to take  a large  up  large-column  resin and  From T a b l e  4-1  we  reach the  (a) . T w o - b o t t l e  distillation  an  average  v a l u e o f 0.17  from  an  average  v a l u e of  26  o f HF  t o 0.26  from  an a v e r a g e  v a l u e of  blank  from  an  v a l u e of 2.5  average  average  the d r o p p e r  improved  bottle  Sr blank  from  i s 0.020 ng/g  dropper  the  the average  i s 3.5  bottle  here  had  ng/g.  measurements.  reduces ng/g  and  t h e Rb Sr  and  H 0 2  t o of 0.072 teflon  This  blank  reduces ng/g  Rb and  bottle  Sr b l a n k  is  f o r H C l O . From  blank  ft  i s 0.22  indicated  been s i g n i f i c a n t l y  Sr  ng/g.  source  average  blanks Rb  blank  ng/g.  0.056 t o of 0.013  (c) . U s i n g HC10„ d i r e c t l y  glass  and  for chemical  of d i s t i l l e d  blank  significantly  2.5  conclusions:  t o 0.051  distillation  ng/g)  dried.  materals  blank  following  from  blank  dilution.  blanks.  shows a l l t h e r e a g e n t  Rb  and  Sr b l a n k s r e p o r t e d  4-1  (average  reagent  column  Table  (b) . Q u a r t z  isotope  the p r e c i p i t a t e d  cation  So a l l t h e Rb  the  by  that  ng/g HC10  0.39 the and  fl  contaminated.  in  Table Reagent  D1st11 l e d H20  0-H20  Date(Yr/Mo/Da)  N  2.5 N 0-HC1  2B-HF  HC104  Rb b l a n k ( n g / g )  Sr blank(ng/g)  average  0 .056 ± 0 .024  0.62  84/5/14 84/7/13 84/7/13  3 . 47 ± 0 .05 0 .015 0 .000 0 .01 1 ± 0 .000  16.4 ± 11.6 0.07 ± 0.02 0.07 0.01  of  7/13  0..013  i  0..003  (6.15 0.40) 0.61 ± 0.07 0.04 0. 63  0.07  0. 95 ± 0.02 0.03 0.31  average  0..020 + 0..015  0.63  84/5/14 84/7/13 84/7/13  + 0 .09 8 .52 0..023 ± 0 .000 0..006 ± 0. OOO  2.65 ± 0. 75 0. 15 ± 0.00 0.18 ± 0.01  0..014  0.17  7/13  0,.01 1  84/5/14 84/6/13 84/6/19  76 1 0..095 + 0 005 0.. 24 ± 0..01  avg.  0. 17  6/13-19  ± 0. 10  18  26 ±  0. 051  84/5/14 84/6/13 84/6/19 84/7/27  9. 5 ± 0. 1 0. 003 0. 103 0. 04 0. 42 0. 123 0. 001  avg.6/13-7/27  0. 22  84/8/2 84/8/2 84/8/2  0. 01 1 ± 0. 0 0 0 0. 032 ± 0. 0 0 0 0. 018 0. 0 0 0  0. 20 ± 0.01 0 . 59 ± 0.03 0. 39 ± 0.02  0. 0 2 0 ± 0. 01 1  0. 39 ± 0. 20  of  8/2  *  10 140 39 ± 4 1 . 3 ± 0. 1  avg.6/13-7/27  0. 18  *  0.02  3 . 72 0..06 0,.080 ± 0,.001 O. 057 i. 0. 0 1 0 0. 017 ± 0. 0 0 0  ±  abnormal  0.45  84/5/14 84/6/13 84/6/19 84/7/27  ± 0. 032  Sr  ± 0.00  0 .030 i 0 .001 0..009 ± 0 .OOO  of  comment  ± 0.05  84/7/13 84/7/13  average coment:  Blanks  0 .045 ± 0 .003 0 .083 ± 0 .001 0 .040 ± 0 . 002  avg.  Reagent HF  Reagent  84/6/13 84/6/13 84/6/19  avg.  6.5  4-1  4.8  2. 5  0.4 1 0.03 0.12 ± 0.01 0. 27 ± 0.2 1 220 ± 140 7 . 2 ± 0.6 1 . 48 ± 0.04 002 1 . 70 3. 5  i  3. 2  * *  * - a c i d e v a p o r a t i o n i n l a m i n a r f l o w hood, p l a n c h e t t e e v a p o r a t i o n and f i l a m e n t l o a d i n g i n open a i r .  o t h e r w i s e a l l e v a p o r a t i o n and f i l a m e n t l o a d i n g i n l a m i n a r f l o w hood. ** - a p p l i e d t o HC104, f r o m t e f l o n s o u r c e b o t t l e , o t h e r w i s e f r o m gl-ass d r o p p e r bottle, a l l t h e b l a n k s went t h r o u g h l a r g e i o n e x c h a n g e c o l u m n s , s o "reagent b l a n k " i n c l u d e s l a r g e column blank.  52 (d). There values used  is a significant  f o r a l l the reagents  for a l l evaporations  reduction  i n the blank  when t h e l a m i n a r  and f i l a m e n t  flow  hood  was  loading.  ( 3 ) . Rb and S r s p i k e s  The  Diluted  8 7  Rb  was u s e d  measured  8 5  Rb/  8 7  Rb  was  f o r Rb  the  to determine  s p i k e was m i x e d w i t h  solution  was u s e d t o d e t e r m i n e  be  0.01069 ± 0.00007 Mmoles  given  8  analysis.  8 7  Sr/ *Sr 8  = 0.00111  certificate; common Sr The 0.00001 first  Sr/ *Sr 8  Sr spike  RbCl  composition  ratios  f o r Sr  isotopic  used  (  8 6  Sr/  isotope ratios are 8 f t  Sr =  = 0.01244 ± 0.00012 and  ± 0 . 0 0 0 0 5 ) were d e r i v e d  f r o m N.B.S.  1984 and 1985 m e a s u r e m e n t s and c o n s i d e r a t i o n o f  concentration  of t h e  8 < t  Sr  jumoles Sr/gm d e t e r m i n e d  prepared  i n Feburary  using  gravimetricly  0.01130 ± when i t was  replicated  Sr s o l u t i o n  o f 0.01130  1976). D u r i n g  s p i k e was  o f 1974. By  a standard  a concentration  (Maxwell,  spike,  contamination.  calibrations 987),  Rb  8 7  was c a l c u l a t e d t o  988) was u s e d  The m e a s u r e d  8 8  of  Rb/gm.  4-2. The i s o t o p e  0.00202 ± 0 . 0 0 0 0 1 ;  ± 0.004%.  the i s o t o p e  The Rb s p i k e c o n c e n t r a t i o n  " S r (N.B.S. SRM  in Table  o f 0.803  Rb  9 8 4 ) . A N.B.S.-type mass  the mixture.  dilution  Rb  the concentration  of  Diluted  8 5  8 7  a w e i g h e d amount o f s t a n d a r d  (N.B.S. s t a n d a r d  spectrometer  analysis.  0.00809 ± 0.00004, g i v i n g  abundance o f 99.20 ± 0.01% a n d In o r d e r  isotope d i l u t i o n  (N.B.S.  Mmoles Sr/gm was  the course  of t h i s  work  standard determined  replicate  53  Table Date  of  4-2  Isotoplc  composition  measurement  N.B.S. c e r t i f i c a t e of analysis 1976 (R.Maxwell) 1978 ( R . L . A . ) 1984  (RIA  &  1985  (RLA  &  calibrations standard  as  procedure as  MS) P.Michael)  of  the  was  used  f o r Sr  f o r Rb.  8 4  the  with  concentration increase  0.000098 0.00032 0.00061 0.00124 0.00107 ±0.00010  s p i k e were done u s i n g  the  new for  difference  that  the  0.011533 A value  during  calibrations  has  The same  Mmoles of  0.01150  s p i k e c o n c e n t r a t i o n was  largely  lies  this  i s good.  used  work. The  i n the  gradual  occured  over  ten years  carried  out  in  the  flask.  sample d i g e s t i o n  dissolution  dissolution  clinopyroxene  or o l i v i n e  vessel  Sr  same  essentially  calibrations.  original  (a),  10  was  0.011475 and  8 f t  the  calibrations.  calculations  Sample  Mettler  initial  of  (4).  teflon  of  0.000386 0.0029 0.0086 0.01374 0.01244 ±0.00088  i n the  i n common S r  storage  of  the  SRM-988  0.000589 0.00093 0.00162 0.00217 0.00202 ±0.00001  isotope d i l u t i o n  Agreement  spike  87Sr/84Sr  spike c a l i b r a t i o n  by  Sr  88Sr/84Sr  Sr  ± 0.00003 Mmoles Sr/gm for  N.B.S.  86Sr/84Sr  Concentrations  Sr/gm were g i v e n  of  with  teflon  o r whole r o c k ,  were w e i g h e d d i r e c t l y  Ho 2  Mg.  vessel  was  8 7  balance. Rb  and  8 f t  via capillary  spike bottles,  then  The Sr  balance  and  has  t u b e s mounted the  sample. The  Savilex  screw c a p .  400-500 mg  into  s p i k e s were  in a  the  200-300  mg  orthopyroxene  vessel  on  a  a maximum s e n s i t i v i t y  first  added  to  i n t h e c a p s of w e i g h t s of  the teflon  sample  and  54 s p i k e s were c a l c u l a t e d evaporation in  this  during weighing,  work was  a group  by d i f f e r e n c e .  By o b s e r v i n g t h e s p i k e  the p r e c i s i o n  e s t i m a t e d t o be ± 0.0001  of a l l weighing gms(la).  Normally  o f 10 samples p l u s b l a n k s were p r o c e s s e d a t one  time. (b) . A f t e r  approximately  HCIO, were a d d e d capped  tightly  temperature  t o the sample,  the t e f l o n  and p l a c e d on a h o t p l a t e  for at least  (c) . A f t e r dryness  5 ml o f 2B HF and 1 ml of  at b o i l i n g  t h e s a m p l e s were e v a p o r a t e d t o  f l o w hood and t h e n a l l o w e d t o c o o l .  (d) . The samples were r e d i s s o l v e d HCl  and c e n t r i f u g e d  i n pyrex  The  sample  was  solution  were  4 days.  digestion,  i n a laminar  beakers  i n 5 ml 2.5N  centrifuge  immediately  tubes  for 4  loaded onto  Quartz minutes.  i o n exchange  columns.  (5).  Chemical s e p a r a t i o n  Elements cation  resin  were column  200-400 mesh AG elution.  initially  (20cm l o n g ,  50W-X8 r e s i n ) .  1cm d i a m e t e r , 2.5 N H C l was  The Rb and Sr were c o l l e c t e d  measurements o r f u t h e r The  s e p a r a t e d by u s i n g a  calibration  purification,  of e a c h  large  filled  with  used f o r  f o r mass  spectrometer  respectively.  c o l u m n was c a r r i e d  out i n three  ways: (a).  2 drops  of r a d i o a c t i v e  t h e c o l u m n . By u s i n g a G e i g e r determined  8 9  Sr  counter  tracer B 9  Sr  was  loaded  into  c o n c e n t r a t i o n was  i n s u c c e s s i v e 5 ml e l u a n t a l i q u o t s ,  and t h e S r  55 peak p o s i t i o n  thus  (b) . 5 ml mg  SrC0  using  and  3  2.5N  0.8  an a t o m i c  concentrations In  this  The  way  that  HC1  mg  2.5N  mg  t h e column  6.ON  HC1  concentration  Sm  used  Sm  0.2  and  0.05  and  determined curves are sample Rb t o the  and  eluant  by  0.4  By  Ca aliquot.  determined.  t h i s means a g r e e d  nodule  mg 100  lab standard  were m i x e d w i t h  S m 0 , and 2  ml  An  P-1  3  2.5N  then  HC1  and  0.1  loaded then  50ml  atomic a b s o r p t i o n Rb,  S r , Mg  and  The  Sm  result  gave  peaks.  and  was  found  i n Rb,  the u l t r a m a f i c  loading  shown  Sr and  p e a k s were  eluant aliquot.  t h e Sr peak by  RbCl,  the column.  5 ml  o f UBC  to determine 5 ml  mg  tracer.  difference  between P-1  position  according  Sr  elution  2 ml  The  3  i n each  and  8 9  for e l u t i o n .  peak was  elution  by  respectively.  significant  elution  elution  H'Cl s o l u t i o n s  SrC0  s p e c t r o m e t e r was  No  Ca  i n each  of u l t r a m a f i c  were u s e d  S r , Mg  loaded into  o f t h e Sr peak d e t e r m i n e d  into  Rb,  Sr and  determined  0.2  containing  a b s o r p t i o n s p e c t r o m e t e r , Rb,  ( g r a n o d i o r i t e ) and RbCl,  was  3  were d e t e r m i n e d  (c) . 5 ml  mg  solution  CaC0  t h e Rb,  position  with  determined.  3 ml  in Figure  sample.  earlier  with pure  S r , Mg But  compared  elements.  and the  Rb  to the The  4-1.  Sr, during t h i s  "rock m a t r i x " e l u t i o n  work, were results  collected  f o r each  column. Despite by a  the e f f e c t i v e  going through  chemical separation  t h e l a r g e column, Rb  s e r i o u s problem.  Significant  spike  o f Rb  interference 8 7  Rb  and  was  would be added  Sr  still to  Sr I  Rb  10  20  30  40  50  Ca  60  70  Sr  80  90  100  0  10 mis  mis  2.5  N  Quartz  HC1  6.0  20  N  Quartz  30 HC1  40  elutant  elutant  Fig. 4-1 E l u t i o n c u r v e s f o r M g . R b , C a , S r a n d Sm o n l a r g e c o l u m n 1. Peaks were determined d u r i n g I n i t i a l column c a l i b r a t i o n by collecting the eluant i n 5 ml a l i q u o t s . I indicates c a l i b r a t i o n by 89Sr tracer loading; II indicates calibration by loading pure reagents; III indicates l o a d i n g of elements in a rock solution matrix. Relative elemental concentrations in the a l i q u o t s were measured by atomic absoptton spectrometry and Gelger c o u n t e r . Fe c u r v e i s from Maxwell (1976).  Ul  57  8 7  Sr  during  to give  an  Sr  isotope  incorrect  spectrometer  was  Rb  ratio,  spiked  to  for  second  a  done by  samples  order  Sr/  8 6  Sr  Sr measurement  correction isotope  8 7  mass s p e c t r o m e t e r measurement  solve  i.e.  using  measuring 8 5  During  program Rb  8 5  and  Rb  c o r r e c t i o n would  this  problem,  separation  10  small  "UBCSSR", the  But  8 7  be  for  8 7  8 7  Rb  natural  Rb  i n c o r r e c t . In  c o l u m n s were  to e l i m i n a t e  as  mass  assuming a  Rb/ Rb=2.59265.  this  Sr  value.  so  spike  prepared  Rb  interference. The with  N  a  N and  are  second  collected was  1.5  RbCl,  i n each  shown Sr  2 ml  from  12.5 to  to  less  to  decimal  ( 6 ) . Mass  cm  diameter,  4-2.  than so  8 7  and  Sr  filled  this  8 6  was  ratios  Rb  was  are  used  Sr  i n t e r f e r e n c e on  Sr  atomic  elution  work and  the  with  Ca  N Q u a r t z HCl  Rb  Sr/  eluting  and  a l i q u o t . The  0.0009 and 8 7  3  r e s p e c t i v e l y . An  1.5  ml.  CaC0  f o r Rb,  eluant  is 8 7  Sr  of  reliable  place.  spectrometry  i s o t o p e measurement  spectrometer  with  digital  aquisition  computer.  and  3  used  20.0  normal c o m p o s i t i o n  data  0.5  column e l u t i o n d u r i n g  nearly  Rb  SrC0  was  in Figure  thus reduced  4th  long,  N Q u a r t z HCl  spectrometer  determination curves  (8 cm  50W-X8 r e s i n ) were c a l i b r a t e d by  s o l u t i o n of  , 2.0  absorption  for  columns  200-400 mesh AG  loading 2.5  small  was  done on  programmable m a g n e t i c  a N.B.S.-type mass field  control  l i n k e d to a Hewlett-Packard  and  HP85  58  Rb c« Sr  2.9  Rb  Ca  N  Sr  2.0  0  5  ml  1  15  10  .5  N  N  elutant  Fig. 4-2 E l u t i o n curves f o r Rb, Ca and Sr on small columns. Peaks were determined d u r i n g initial c a l i b r a t i o n by c o l l e c t i n g t h e eluan't i n 2 . 5 ml a l i q u o t s . R e l a t i v e element concentration m the aliquots were measured by atomic absoptlon spectrometry. 1 . 5 N Q-HC1 1s s e l e c t e d f o r s e c o n d S r column e l u t i o n a n d S r Is c o l l e c t e d from 1 2 . 5 to 20 m l .  (a) . S i n g l e tantalum  f i l a m e n t s mounted on N.B.S.  f i l a m e n t b l o c k s were baked out f o r 15 minutes under < 3.0 X 10~  5  t o r r vacuum and a t 3.2 amps c u r r e n t . (b) . One drop of sample, taken  up i n Quartz H 0, was 2  loaded on the f i l a m e n t ribbon a t 1.5 amps c u r r e n t . (c) . The loaded  f i l a m e n t was then heated  to a d u l l red  glow f o r 10 seconds. (d) . the f i l a m e n t was then spectrometer.  loaded  i n t o the mass  The sample a n a l y s i s was only s t a r t e d when the  vacuum i n the mass spectrometer  was l e s s than  10"  T h i s took about 2 hours by using r o t a r y , vacsorb,  7  torr.  and then  ion pumps. (e) . The f i l a m e n t c u r r e n t was i n c r e a s e d u n t i l intense Rb peak ( u s u a l l y  87  the more  R b ) was f i r s t d e t e c t e d on 30 mV  59 s c a l e . The collected Using  signal on  100  was mV  the. p r o g r a m  followed  by  or  300  4 pairs  of  and  1a e r r o r  8 5  Rb  and  8 7  was  digital  as  Data  were  individual blocks.  each  Rb  b l o c k 3 backgrounds  p e a k s were measured,  were done and  printed.  8 5  Rb/  8 7  Rb  B l o c k s were r e p e a t e d  to  precision.  i s o t o p e measurement was  mass s p e c t r o m e t e r and  scale  statistics  achieve acceptable o v e r a l l Sr  mV  "NBSRB2", w i t h i n  then c a l c u l a t i o n s r a t i o with  f o c u s e d t o maxmum i n t e n s i t y .  done on a VG  ISOMASS  w i t h a programmable magmatic  data a c q u i s i t i o n  linked  to a  54R  field  control  Hewlett-Packard  HP85 c o m p u t e r . (a) . S i n g l e filament  tantalum  f i l a m e n t s mounted on  b e a d s were b a k e d out  i n the  same way  Cathodion as  Rb  f ilaments. (b) . A t i n y t h e baked  2  5  s u s p e n s i o n was  p l a c e d on  filament.  (c) . Two were d r i e d second  b i t of m i l k y T a 0  drop  on  drops the  o f a sample, d i s s o l v e d  filament  at  1.5  o n l y b e i n g added a f t e r  (d) . The  filament  was  heated  in Quartz  H 0, 2  amps f o r 5 m i n u t e s , the  first  the  d r o p had  t o a r e d glow  for  dried.  10  seconds. (e) . 6 f i l a m e n t s were mounted on mass s p e c t r o m e t e r . The rotary started  and  source  r e g i o n was  t h e n T i s u b l i m a t i o n and  only after  pumped t o below  10"  the c a r o u s e l i n t h e  i o n pumps. A n a l y s i s  t h e mass s p e c t r o m e t e r 6  mbar.  pumped down by  s o u r c e had  was  been  60 (f).  A n a l y s i s was c o m p l e t e d  The after  filament current  the  current  8 5  was  detected  s c a l e by u s i n g  background, pairs  of  reports Sr/  Rb,  Sr  8 t t  the  Sr  8 6  8 5  "short  8 7  Sr/  8 5  Rb,  8 6  8 6  Sr  Sr  Sr  signal  stage,  block"  8 8  Sr  and  8 6  8  Sr  8 6  = 8.3752 a n d c o r r e c t e d  Sr  and  Sr,  ratios,  t o r u n on X10 s c a l e u s i n g  8 6  Sr,  background,  b a c k g r o u n d , and  measurements. T h i s statistics pairs 8  "Sr/  of 8 S  8 < t  Sr  a summary correction  and  ratios. for to  Rb  8 6  to  "long  current  block"  5 p a i r s of  5 p a i r s of  8 B  8 7  mode. In Sr  Sr  and  and  8 6  Sr  f u r t h e r measurement  of 5  and p r i n t o u t of the n o r m a l i z e d  After Sr  then  by p r i n t o u t o f r a t i o s and  optionally,  Sr  Rb,  bracket  i s followed  and then, Sr  8 5  8 5  by 4  f o r n a t u r a l Rb. A f t e r 4 t o  increased  block",  Sr,  8 6  normalized  a summary was made and t h e f i l a m e n t  "long  on  block"  followed  6 blocks,  each  was  focused to  "short  m e a s u r e m e n t s . The computer and " S r /  Sr  8 8  was c o l l e c t e d  mode. E a c h 8 7  the  was t h e n  data  4 p a i r s of  4 p a i r s of  and  8 8  2 amps,  the filament  t o 3.0 t o 3.2 amps u n t i l  At t h i s  background,  i n c r e a s e d t o about  f o u n d and f o c u s e d ,  s c a l e . The  X1000  intensity.  contains  8 8  peak was  increased  on  a maximum X100  Rb  was  as f o l l o w s :  10 t o 15 " l o n g  8 7  Sr/  8 6  8 7  Sr  > 0.0009 o r w i t h  block"  was done. Any b l o c k a for  8 7  measurements,  with Sr/  B 6  8 7  Sr  Rb > 0.0010  was r e j e c t e d .  (7).  Blanks  Low b l a n k s extremely  were e s s e n t i a l  low c o n c e n t r a t i o n s  f o r the determination  of t h e  o f Rb a n d S r i n m i n e r a l s o f  61 ultramafic Rb  rocks. During  b l a n k s and  are given  30  total  the c o u r s e  i n T a b l e 4-3  in this After  l a b and  May  of  e v a p o r a t i o n s and HC10„  directly  and  digestion,  Rb  and  labs are given  loading,  i t s teflon  and  and  total  previous  in Table  f l o w hood  u s i n g 2B  source  results  4-4.  Sr b l a n k s w i t h  using laminar  filament  the Rb  F i g u r e s 4-3  other  1984,  from  work, 24  Sr b l a n k s were m e a s u r e d . The  C o m p a r i s o n s of t o t a l work  of t h i s  for a l l  HF,  bottle  and  for  Sr b l a n k s were r e d u c e d  4-4.  by  taking  sample a  factor  of  10. Average t o t a l total  Sr blank  levels  achieved  laboratories UBC  was  blank  Rb  blank  3.3  i n the  levels  8 7  Sr/  8 6  blank  The  Sr  average  ratio  Sr  less  Average the  lunar-sample-oriented clean  labs,  total  A.N.U. N e v e r t h e l e s s  to the  level  Rb  (1978) and and  the  of o t h e r  good  (1974,  1975),  i . e . of B r u e c k n e r  & Murthy  Mengel et a l .  Sr b l a n k s and  (0.714 ± 0.016) were u s e d  samples a r e  in olivine.  clinopyroxene  The  i s 6 ng  Thus t h e l a r g e s t  about  ng.  T h o s e v a l u e s a r e above  l o w e s t c o n c e n t r a t i o n s o f Rb  Peridotite  ng.  ± 0.13  blank  f o r Rb  and  Sr  corrections. The  ppm  ng.  are comparable  (1978), Menzies  (1984).  ± 2.2  0.26  of C . I . T . , U.C.S.D. and  earth-sample-oriented Basu  was  5%. than  0.02  Rb  Sr  for Josephine  i n c l i n o p y r o x e n e and  minimum q u a n t i t y of Rb and  blank  For the n o d u l e s , 1%.  ppm  and  Sr from  500  corrections Rb  and  mg  from  300  of o l i v i n e  f o r Rb  Sr b l a n k  and  Sr  0.12 mg  i s 60 are  corrections  are  of  Table Date yr/mo/da 84/4  ng  Total  Rb b l a n k s nanomoles  3.3 17 32 8 .3  0 0 0 0  84/5/14  0.94  84/6/13  84/6/19  84/7/5  4-3  Sr b l a n k s 87Sr/86Sr ng nanomoles 1 1 24 39 8  0 0 0 0  0 .011  7.0 6.8  0 .079 O .078  0 . 726 o . 777  0.12 0.27  0 .0015 0 .0032  1 . 30 2.8 9 . 1  0 .015 0 .032 0 . 10  0 . 700 0 .700 0.. 708  0.40 0. 36 0. 27 0. 20 0.27  0 .0047 0 .0042 0 .0031 0 .0023 0..0031  2.13 1 .09 7. 1 6 . 3 2.2 5.8 3.3  O 0 0 0 0 0 0  0. 22 0. 39  .04 . 19 . 37 .097  0 .0026 0,,0046  .  ( 1 68) O. 36  . 127 . 25 .41 .9  .024 .012 .081 .072 .025 .067 .038  0 0 0 0  comment  ** * * *  .718 . 725 .717 . 700  ** * * ** * *  (O .68) (0..692) (0..691 ) 0..711 0. 701 0. 718 0. 731 0.. 752  fc  +* * ** sma11 •*  0 .018  0. 78 3.64  0 .009 0..042  ( 0 65) ( 0 . 808 )  0.. 004 2  3.98 3.2  0 .045 0 . 037  0. 709 0. 705  * Rb abnorma1 *  * S r abnorma1  sma11  co1umn  sma11  co1umn  84/8/2  0. 18  O. 0021  1.19  0..018  0. 712  *  84/8/17  0. 44 0.45 0. 24  0 .0052 0..0052 0. 0 0 2 9  7. 2 3 . 87 3. 1  0 .083 0 .044 0..035  0. 708 0. 706 0. 705  * •* ** **  84/10/9  0. 33 0. 49  0. 0038 0. 0057  1.6 1. 1  0. 012 0. 018  0. 716 0. 7 14  84/12/19  0.11  0. 0013  2. 1  0. 024  0. 738  85/2/1  0.11  0. 0013  2. 2  0. 025  0. 747  85/5/24  0.12 0.09 0.12  0. 0014 0. 0 0 1 0 0. 0014  2 . 25 6.16 1 . 55  0. 026 0. 070 0. 018  0. 699 0. 703 (0. 683)  average 0. 26 0. 0031 a f t e r 8 4 / 5 / 1 4 ± 0 . 1 3 +0. 0015 comment:  co1umn  1 . 56 ( 106)  84/7/18  84/7/27  Blanks  ±2  3.3 . 2  0. 038 ± 0 . 025  0. 7 14 ± 0 . 016  ** +*  tt *  * **  *  abnormal blanks exc1uded  * - s 1 n g 1 e c o l u m n f o r Rb a n d S r . ** - s i n g l e c o l u m n f o r Rb, d o u b l e c o l u m n f o r Sr. B l a n k s i n 84/4: u s i n g o r d i n a r y HF and HC104 f r o m d r o p p e r b o t t l e r , e v a p o r a t i o n i n open a i r . B l a n k s o n 8 4 / 5 / 1 4 : u s i n a 2B-HF a n d HC104 f r o m d r o p p e r b o t t 1 e , e v a p o r a t i o n i n l a m i n a r f l o w hood. planchette e v a p o r a t i o n and f i l a m e n t l o a d i n g i n open a i r . B l a n k s a f t e r 84/5/14: u s i n g 2B-HF a n d HC104 f r o m s o u r c e b o t t l e , o p e r a t i o n i n l a m i n a r f l o w hood.  84/4  i  '  i  R a n g e o f p r e v i o u s Rb b l a n k s  1  i  '  84/5/14  84/6/13  84/6/19 0Q  84/7/05 I  t H O rr  £L  o  84/7/18  > H rt  84/7/27  cr  ^  84/8/02  D  84/8/17  84/10/09  84/12/19  85/2/01 OJ  85/5/24  ng Sr  i  84/4  1  +-—i  1  84/5/14 •4  84/6/13 ** 4  84/6/19  84/7/05  84/7/18  84/7/27 -  «-'./«/02  84/8/17  -  84/10/09  84/12/19 |_  85/2/01 85/524  4  «  1—-i  "  1—i  1  1  I  i  I -  '  1  *  65 Table Lab  4-4-  Companslon  year  Rb  UBC UBC Miami U. UCLA C . I .T .  1984 197S 1974  1.7  ANU WAIT  1971  C .I . T .  1984  U.  1978  and  10  difference be  what  small the from 1.0  amount  reagent  Rb  0.059  blanks,  column  are  the  be  step  This column  a  Burwell (1973) Jacobsen et al.(l984) A l l e g r e et a l . (1982)  ng  and  greater  must  1.4  0.42  calculated  in  -  for  Rb  and  the is  5 ml  reagent  2B-HF,  3.4  total  observed  small  blank  from  lowest  than  means  source  Compston et a l . ( l 9 7 l ) DeLaeter et at.(1970) Brueckner ( 1974) Brueckner (1975) Carlson (1980) M e n z t e s e t . a l . ( 1978) B a s u ( 1978) Mengel e t al.(1984)  calculated  are  Data  ng  blanks  blanks. blanks  column  blank  "total  blanks"  less  than  Sr.  0.2  The  must Since  by  a  included are ng  1ml  Rb  in  mainly and  reduction  Sr  data  reduction  revised  from  BASIC  The  AF  0.19  0. 1 0.045 - 00. .111177  HCl,  blanks.  and  (Appendix  carried  0.7  Data  Sr.  (8).  "RBSR"  1.0  -  there  reagents, ng  -  2.5N  blanks  -  2  total  i s added  - 70 2 0.2  0.90  labs  This work Maxwell (1976) Steuber at al.(1974) Mark e t a l . ( 1973) Papanastasslou e t . a l . (1973)  0. 1  0.015  ml  3 . 4 - 34  0. 1  between  calculated  10  0 0 7 0.07  other  blank(ng)  14  0.14  with  100 1 10 1 0.2 0.5 1  0.8  Synthetic  HC10,  -  10 0.3 0.3 -  1975  Paris  Sr  0.3 8.9  0.45  1973 1980 '1978 1984  blank(ng)  blank  0.02  1970 1974  G .I . G. Oxford Polytec.  total  4 - 1 0 2  1973 1973  Lamont Lamont UCSO Minesota  of  done  programs  by  a  "RBSPK3"  FORTRAN and  program  "SRSPK3"  5). total  error  through  the  =  was  •Kll O A  (la),  calculation  AX.) , 2  •  1  based  (Nunes,  on  a l l uncertainties  i s given 1980)  by  66 where AF i s t h e f i n a l ith  e r r o r , AX^  i s the e r r o r  v a r i a b l e , and F = F(X,,X ,...,X  )  2  The computer  i n the  performs the p a r t i a l  differentiation for  each v a r i a b l e : •gjj ^  F ( X , . . . X ^ , . . . X^ ) .  -  l f  All thesis  F ( X . . . X ^ +AX^ , . . . X^)  =  errors listed  are-la  1  i n t a b l e s , t e x t , or diagrams i n t h i s  or standard  e r r o r o f t h e mean  f o r averaged  numbers. (a) .Rb d a t a  reduction  Rb mmoles = C  -W  sp  Rb(Aimoles/gm) (umoles)]/(sample Rb  (PP )  a  m  s a m p l e  8 5  8 5  = [ Rb(.umoles) - Rb  8 7  blank  weight) = Rb(Mmoles/gm)  m  s  •(R • P - P ) / ( P - R -P ) m t t s m s 8 7  sp  p  l  e  s a m p l e  .atomic  weight of  Rb, where R  m  = measured  8 5  Rb/  ratio,  8 7  = % abundance  of  8 7  Rb  in spike.  P  8 5  = % abundance  of  8 5  Rb  in spike.  8 7  = % n a t u r a l abundance  of  8 7  Rb.  = % n a t u r a l abundance  of  8 5  Rb.  = spike concentration  (/umoles/gm) .  P  s 8 S  s  C p g  = s p i k e weight (b) . S r d a t a 8 8  ratio  Sr/  8 6  Sr  different 8 6  Sr  8 8  Sr  ratio  and  (grams).  reduction was n o r m a l i z e d  o f 8.3752 d u r i n g  contains  Sr/  Rb  P  P  8 4  B 7  8 6  Sr  data  8 7  Sr/  8 6  Sr  collection.  in a proportion  from t h e n a t u r a l and  to the n a t u r a l  8 8  Sr/  ratios  8 6  Sr  However  8 < t  8 8  Sr  Sr/  8 6  Sr  spike  significantly  ratio.  To o b t a i n  of the sample-spike  true  mixture,  67 the  Sr/  8 8  derived  8 6  Sr  ratio  from  (  was  Sr/  8 8  renormalized  Sr)  8 6  , /(  Sr/  8 8  iteratively 8 6  Sr)  C a 1C  iteration [ (  8  8  S r / B  [ ( B 8  S  r  /  8 6  was 6  r )  S  S  r  stopped c  a  l  / (  c  8  8  S  6  S  / 8 6  r  S  to those  used  evaluated  i n the  weight  87.62 was  r  taken  value  t o be  m  e  a  ] ],  s  <0.00000l.  f o r Rb.  calculated The  same manner as used  f o r the  total  average  of  SRM987  value  of  a l l the  8 7  have been a d j u s t e d by  (10) . I s o c h r o n A revised isochron 6-a).  8 7  slope,  Rb/  were r e a d  using  8 6  Sr  adding  ratios a  and  of  from  the  8 7  Sr/  8 6  output  points with  a FORTRAN p r o g r a m  and Sr  of d a t a  one  their  Sr  is  an  (Table  4-5).  in this  work  0.00003.  used  f o r Rb-Sr  calculation one  sigma  bars  (Appendix  (Appendix  errors  r e d u c t i o n program  sigma e r r o r  "PLRBSR"  8 6  plot  the date and  Sr/  work gave  reported  factor  calculation  intercept and  Sample d a t a  Sr/  atomic  reported.by  = 0.71017 ± 0.00004  YORK REGRESSION program was  Sr  8 6  Sr  8 7  the v a l u e s  average  8 6  was  SRM987 measurements  A c t u a l measurements d u r i n g t h i s Sr/  f o r Sr  A common Sr  labs.  8 7  formulae  calculation.  N.B.S. s t a n d a r d  0.71020, an  error  f o r Rb.  f o r Sr ppm  using  several  Accordingly,  The  i  )  then  (9) . N.B.S. s t a n d a r d The  ratio.  m  meas i-1  Sr c o n c e n t r a t i o n was  of  factor  IT163 S  r )  8  calc  similar  a  when  S r /  / ( 8 8  )  by  "RBSR".  were p l o t e d by  6~b) .  Table  Date(yr/mo/da)  4-5 8 7 S r / 8 6 S r r a t i o s o f N.B.S. SRM-987 ( K . S c o t t , p e r s . comm., 1985) No.  of  Blocks  87Sr/86Sr  + /-  1984/8/8  6 15 15 9 13 18  0. 71002 0. 71016 0. 70967 0. 71007 0..71032 0 71026  0.00012 0.00010 0.00018 0.00009 0.00005 0.00009  1984/9/1 1  16 18 16 17 16 15  0..71028 0. 71017 0. 71030 0. 71017 0. 70999 0. 71017  0.00009 0.00007 0.00008 0.00009 0.00013 0.00013  1984/10/ 10  34  0. 71022  0.00006  1984/1 1/12  40  0. 71018  0.00012  1985/1/3  18 18 19 19 16 18  0. 71017 0. 7 1007 0. 71007 0..71021 0. 71014 O. 71023  0.00007 0.00005 0.00005 0.00005 0.00004 0.00005  1985/3/29  9 10  . 0.7 1013 0. 71020  0.00004 0.00007  1985/4/15  18 16 18 19  0. 71022 0. 7 1017 0. 71018 o. 71020  0.00006 0.00003 0.00002 0.00002  1985/5/22  17 19 19 18 17 18  0. 71019 0. 7 1022 0. 71015 0. 71014 0. 7 1023 0. 7 102 1  O.00005 0.00006 0.00005 0.00004 0.00003 0.00003  A v e r a g e v a l u e = 0.71017 a n a l y s e s and I n d i v i d u a l  +/- 0.00004 errors.  w e i g h t e d by number o f  69 V.  V-1.  Nodules and host Olivine,  separates, nodules Sr  Rb-Sr  basalts  orthopyroxene  whole r o c k ,  and  and c l i n o p y r o x e n e  and a c i d  have been a n a l y s e d  isotope composition.  Lake,  ISOTOPE RESULTS  Of t h e s e ,  8 7  Sr/  8 6  these  Sr  host  a r e from  Jacques  3 f r o m West K e t t l e  b a s a l t s were a l s o a n a l y s e d  River,  (1) . J a c q u e s  (Appendix 7 ) .  a r e used  for further  u n c e r t a i n t y was c a l c u l a t e d by  isochrons are defined.  ( J L 1 , J L 1 4 , J L 1 5 and J L 1 8 ) m i n e r a l  i s o c h r o n s a r e shown on F i g u r e s i n Table  (2) . B i g T i m o t h y  data  <6%  5%,  Lake  Jacques Lake nodule  mineral  Sr  this  (see I V - 2 - ( 8 ) ) .  A number o f m i n e r a l  Big  8 6  w e i g h t e d mean v a l u e s  t h e mean v a l u e  are l i s t e d  during  f o r Rb i s 1-2%, f o r Sr a b o u t 8 7  Nunes' e q u a t i o n  (Table 5-1).  repeatedly analysed  0.0005, and f o r R b /  samples,  discussion,  The  4 nodules  2 from L a s s i e L a k e .  work. The r e p r o d u c i b i l i t y  data  12  f o r Rb a n d Sr c o n c e n t r a t i o n a n d  Some s a m p l e s have been  For  l e a c h m a t e r i a l from  3 from B i g T i m o t h y M o u n t a i n ,  Eleven  for  mineral  5-1, 5-2, 5-3 and 5-4. The  5-2.  Mountain  Timothy Mountain  nodule  (BM11, BM16 and BM55)  i s o c h r o n s a r e shown on F i g u r e s are l i s t e d  i n Table  (3) . West K e t t l e  River  5-3.  5-5, 5-6, a n d 5-7.  70 West K e t t l e  R i v e r nodule  (KR1, KR2, and KR35)  mineral  i s o c h r o n s a r e shown on F i g u r e s 5-8, 5-9, and 5-10. The d a t a are  listed  i n Table  (4).  5-4.  L a s s i e Lake  Lassie  Lake nodule  (LL1 and L L 1 4 ) m i n e r a l  shown on F i g u r e s 5-11, and 5-12. The d a t a Table  V-2.  are l i s t e d i n  5-5.  Josephine Mineral  Peridotite  separates  from  4 samples  JM2) have been a n a l y s e d . The d a t a Mineral  For Table  isochrons are  (JM5, JM14, JM15 and  are l i s t e d  i n Table  5-6.  i s o c h r o n s a r e shown on F i g u r e 5-13, 5-14, a n d 5-15.  comparison, the  5-7.  m i n e r a l i s o c h r o n s a r e summarized i n  71  Table Samples JL14 BM11 BM55 BM26  BAST BAST BAST  KR  B-1 B-2 B-3 B-4  KR KR KR KR35 LL 1 LL14  BAST  BAST BAST BAST  Rb  5- 1  Samples JL18 Acid leach Whole rock Syn. wr 0 1 o p s 1de Enstat1te 011v1ne JL15 Acid leach Whole rock Syn. wr Diopside Enstat1te 01 1 v 1 n e II  UL  */-  ppm  12. 7 54. 9 45. 5 62. 1 17. 1 17. 2 17. 5 21 . 5 31 . 8 18. 5  Rb  ppm  1, 2 2 0. 252 0..208 0..348 0. 259 0., 153 0..546 0. 0958 0 . , 161 0 ..281 0. 260 0. 0842  Sr  5-2  of  ppm  host  and  associated  basalts  +/-  87Sr/86Sr  +/0 00014 0 .00010 0 .. 0 0 0 0 6  87Rb/86Sr  0. 1 1 .8 2.8  1297 1514  16 51  0 .70254 0 .70264  1276  0. 1  1303 859 712  33 6  0 .. 7 0 2 7 2 0 .70269  19 4 19  0 .70318 0., 7 0 3 6 0 0. 70291  9  0.. 7 0 2 8 9  0 .. 0 0 0 0 5 0. 00014  23 8 34  0. 70262 0. 70330 0. 70238  0. 00012 0. 00011 0. 0OO05  0.5 0.5 0.2 0.6  30. 4  Table  Rb-Sr data  642 951  1.6 0.4  842 840  0.8  702  Rb-Sr +/-  0 ..02 0..001 0,.001 0.. 0 0 3 0. 002 0 .001 O .. 0 0 5 0.. 0 0 0 7 0..001 0.. 0 0 3 0. 002 O .. 0 0 0 9  isotope Sr  ppm  0 .00004 0 .00009 0 .. 0 0 0 1 4  data  of  Jacques  +/-  87Sr/86Sr  Lake  +/-  0.028 0 . 105 0 . 103  0 .001 0 .005 0 .007  0 . 138  0 .001 0 .001 0 .001  0.058 0.070 0.079 0.092 0.074 0 . 110 0.076  0 .002 0,.001 0 .. 0 0 6 0 ..001 0 .005  nodules  +/-  87Rb/86Sr  +/-  0 .0007 0 .0002 0 .0001 0 .00004 0 .002  78 .9 3 8 ..5 4 0 .6 2 3 8 .7 4 .20 2 .32  0, 8 0. 3 0 . 1 0 .9 0 .02 0 .01  0. 7029 0. 7024 0. 7026 0.,7026 0. 7034  0 .0003 0,. 0 0 0 2 0 0O01 0 .0001 0, 0O04  0. 7036  0 .0006  0,. 0 4 4 7 0 .,0191 o,,0148 0 .. 0 0 4 2 1 0 , 178 0 , . 191  7.. 6 5 8. 95 9 .58 54 .3  0 .. 0 2 0,.03 0 .05 0 .3  0. 0. 0. 0. 0. 0.  7030 7029 7029 7026 7051 7086  0 .0004 0,.0001 0 ..0001 0,.0001 0. 0009 0, 0004  0,.206 0,.0310 0.,0485 0 0150 0. 273 0 ., 7 4 9  0,. 0 0 2 0 .0003 0 .0004 0 .0002  0 . 7031  0. 0004 0,.0003 0, 0001 0,.0001 0. 0005 0 ., 0 0 0 4 5  0 . 161 0. 0613 0. 0619 0. 0139 0. 438 0. 483  0 .003 0,. 0 0 0 5 0 ,0001 0. 0O01 0 ., 0 0 5 0 ., 0 0 5  0. 0O02 0 .. 0 0 0 2 0. 0002 0, 0O06  0. 0. 0. 0.  0. 0002 0 ., 0 0 0 0 8 0. 0006 0. 021  2.. 7 6 0 .325  0 .,01 0, O07  0 .002  0 .003 0 .017  \ A  1  4  Acid leach Whole rock Syn. wr D1 o p s 1 d e Enstat1te 01 1 v 1 n e O11L l 4  Syn. wr D 1 o p s 1de Enstat1te 011 v i n e  1. 7 6 0. 0. 0.. 0. 0..  179 146 154 191 104  0. 0912 0 .. 125 0. 0191 0 . , 1 16  0..03 0..001 0.,001 0..001 0..002  3 1 .. 7 8 .44 6 82  0.,001  32 . 1 1 .2 6 0 .624  0. 0002 0. 002 0. 0006 0 ..001  13, 2 76 .5 2. 81 0 .344  0,, 1 0, 04 0, 02 0 .. 1 0 .,01 0 .0 0 5  0. 7030 0. 7028 0. 7025 0 . 7051 0. 7056  0., 1 0 .,4 0..02 0 ., 0 0 7  0. 0. 0. 0.  7030 7029 7029 7106  0200 00475 0197 977  72  Table  5-3  Rb-Sr  Rb  ppm  +/-  Samples  Isotope Sr  data  ppm  of +/-  Big  Timothy  Mountain  87Sr/86Sr  nodules  +/-  87Rb/8SSr  +/-  0,.718  0, 016  0 .. 7 0 2 9 0..7036  0 .0001 0 .0001 0,.0001 0 .0001 0 .0004  0 . , 128 0 .,131 0,.0322 0 .. 2 6 0  0.,002 0. 001 0,, 0 0 0 3 0 ., 0 0 2  BM1 1 A d d  leach  2 .79 1 .. 13 0.. 4 1 0 0 .. 6 0 9 0..936  0 0 0 0  .01 .002 .005 .007  1 1. 2 5 25 .6 9 .06 54 .7 1 0 .. 4 0  011v t ne BM16 A d d leach  0.,232  0 .002  3 .52  0..716  Whole rock Syn. wr Diopside  0.. 2 8 0 0..113 0 . 160 0.. 0 7 3 0 0 . 102  0 .009 0 .006 0 .001 0..001 0 ..0OO6 0 ..001  3 .66 4 .61 3 .49  2 . 84  0 ..06  0. 326 0 . 159 0 . 140 0. 252 0. 0701  0 ., 0 1 0  1 0 .. 2 5 1 1 .. 7  0,.001 0..001 0..001 0 .. 0 0 0 4  1 0 .. 7 3 3 3 ., 4 5 0.,749 0 , 260  Whole rock Syn. wr Diopside Enstat1te  Enstat1te 01ivlne BM55 Acid leach Whole rock Syn. wr Diopside Enstat1te 01 W i n e  0 .0634  Table  5-4  Rb-Sr  Rb  ppm  +/-  Samples KR35 Acid leach Whole rock Syn. wr  0..253 0 .. 125 0 , , 158  1 0 ., 2 5 0 .408 0,,457  isotope  0 .003 0 .001 0 .001 0 .002 0 .002 0,.001  Diopside Enstatite 011v1ne KR 1  0. 278 0 . . 192 0., 100  A d d leach Whole rock Syn. wr D1 o p s 1 d e Enstatite 01 W i n e  0..293 0., 385 0.,111 0 ., 149 0 . 139 0. 0994  0 .002 0,.0051 0,0 0 1 0. 003  0 . 164 0. 272 O. 0982 0 . 162 0 . 122 0. 0797  0..001 0.,002 0. 0005 0..003 0. 001 0. 0O07  I/O rxK  o ^  Acid leach Whole rock Syn. wr D 1 o p s 1de Enstatite 011v1ne  0.,001 0. 0008  Sr  0 .. 7 0 3 3 0 .. 7028 0. 7033  0..7036  0 .0002  0 . 191  0,,002  0 .01 0 .02 0,.01 0 .. 0 3 0,.008 0..007  0.,7044 0 ., 7 0 3 5  0 .0002 0 . 0001  0 ..007 0 .004  0. 7039 0. 7027 0.,7157 0. 7153  0 .. 0 0 0 5 0,, 0 0 0 5 0 .0009 0 .0004  0. 565 0 . 176 0,.0932 0.,0451  0,.03  0. 7033 0. 7027  0 .0002  0 .. 8 0 2  0,.0001 0,. 0 0 0 2 0 .. 0 0 0 2 0,, 0 0 0 3 0,. 0 0 0 5  0. 0818  0 ,.3 0,.02 0 ..07 0. 005 0 .. 0 0 5  data  ppm  4. 28 1 0 .. 5 3 9 ., 3 9 5 5 ..6 0 .,931 0.. 369 1 .4 7 5 4 , 33 2 . 85 24 . 5 0 . 288 0 . 145 6. 9. 0. 9.  0 .03 0 .2 0 .02 0 .2 0 .. 0 3 0..02  16 41 761 31 0. 416 0 . 112  of +/-  0. 7035 0. 7033 0. 7086 0. 7084  West  Kettle  87Sr/86Sr  0 .01 0 .09 0 .04 0 .2 0 .054 0. 008  0 , 7053 0,.7022 0, 7029 0,,7022 0,, 7 1 4 0 0. 7197  0,.007 0.,03 0 ..02 0 .. 1  0.,7067 0. 7040 0. 7037 0 . 7031  0.,009 0. 008  River +/-  0,. 5 1 9 0 ..641  0,. 0 4 2 9 0 . , 0 1 19 0. 975 0 .. 8 2 6  0 .. 0 0 0 6 0 .. 0 0 0 4 0 .011 0 ..011 0 .. 0 1 6 0 .. 0 0 1 5 0 .. 0 0 0 2 0 ..0001 0 ., 0 0 8 0  020  nodules 87Rb/86Sr  +/-  0 .0O01 0 .0001 0 .O002 0 .0003 0 .0003 0,. 0 0 0 4  0 . 171 0 .0343 0 .0486 0 .0144 0 .597 0 .. 7 9 5  0 .002 0 .O0O4  0. 7147 0. 7162  0 .. 0 0 0 6 0 .. 0 0 0 2 0 .0002 0 ., 0 0 0 2 0,.0002 O .0003  0 .. 5 7 4 0 ..261 0 .. 1 1 3 0 .. 0 1 7 6 1 .40 1, . 9 9  0,. 0 0 5 0.,004 0,,001 0 . OO04 0 ..04 0. 1 1  0. 03 0.,03 0. 006 0. 03  0. 0. 0. 0.  7055 7037 7058 7032  0 .. 0 0 0 6 0 .,0001 0.0 0 0 3 0 ., 0 0 0 3  0.0 0 0 8 0. 0007 0. 004 0. 0008  0. 009 0. 008  0. 7123 o . 7142  0. 0006 0. 0001  0,.0768 0,,0837 0.,373 0,,0502 0. 848 2 . 06  0 0OO3 0 .0001 0 .035 0,.018  0. 020 0 . 15  Table Samples LL 1 A d d leach Whole rock Syn.  wr  Diopside Enstat1te 01 1 v 1 n e LL14 Acid leach Whole rock Syn. wr D1ops1de Enstat1te • 11 v i n e  Rb  ppm  Rb-Sr +/-  0. 02 0 . 13  0 .957 3 .. 4 7 1 ..0 5 0,. 2 7 4  0 .. 0 0 6 0..03 0 . 01 0.,002  3 .24 0 .769 0 . 197 0.. 2 3 3 0 . 154  0 . , 13 0 .. 0 0 7  0 .0546  Rb  ppm  Isotope  Sr  2. 8 7 6. 05  Table Samples  5-5  0..001 0..002  56. 3 51 . 1 16, 9  Lassie  Lake  nodules  +/-  87Sr/86Sr  +/-  87Rb/86Sr  +/-  0. 2 1.3  0. 0003 0. 0002 0 .. 0 0 0 2 0,, 0 0 0 2 0 ..0001 0 .. 0 0 0 4  0 . 147 0 . 342 0 . 164 0 . . 102 1 ,.0 2 0. 995  0 . 001 0 . 011 0,.001 0,.001 0 .01 0 .013  9 8 ..5 2, 9 3 0,. 798  0 .. 1 0 ,,4 0 ..02 0 .008  4 1 ,. 0 8 . 77 10 . 7 9 1 6 .. 9  0. 6 0 .04 0,.03 0..05  0. 7047 0. 7037 0. 7042 0..7041  0..0002 0 .. 0 0 0 1 0 .. 0 0 0 2 0 .0002  0.,235 0 .. 2 5 4 0 .0528 0 .0398  0 0 0 0  0,. 0 0 7 0 O06  0.. 7 0 8 9 0..7074  0 .0003 0. 0 0 2 0  0 .. 5 6 0 0 .. 3 1 7  0 .006 0 .005  0 .797 0,.498  Rb-Sr  +/-  of  0. 7045 0. 7036 0..7031 0. 7030 0..7043 0,. 7 0 4 7 .  0,.001 0. 0005  5-6  ppm  data  isotope  Sr  ppm  data +/-  of  Josephine  87Sr/86Sr  .004 .003 .0004 .0004  Peridotite  +/-  87Rb/86Sr  +/  JM14 Syn.  wr  Diopside Enstat1te 011vlne-1  0 0 0 0 0  .0733 . 116 .084  0 .0008 0 .001 1 0 .001 0,.001 0,.001  .0918 .0761  0 .. 4 4 9 0,.582 0 .825 0, 283 0,. 305  0 0 0 0 0  .008 .028 .024 .006 .009  0 .. 7 0 7 3 0..7063 0 .7053 0..7111  0 .592 0 . 379 0 .257 1 . 19  0. 7089  0 .0005 0 .0015 0 .0008 0 .0009 0 .0004  0 .80  0 0 0 0 0  .012 .014 .008 .03 .01  011v1ne-2 JM2 Enstat1te JM15 Syn. wr Diopside Enstat1te  0 .0322  0,.0003  0., 130  0,.008  0. 7087  0 .. 0 0 1 5  0 .784  0 .. 0 3 2  0 .0525 0.. 0 2 3 3 0 .0293  0 .0006 0. 0007 0,.0007  0 ., 143 0. 256 0 ., 126  0,. 0 1 0 0 .. 0 1 2 0,.015  0,.0013  0 ., 153  0,. 0 1 5  0.. 230 0. 676 1. 7 3  0,,07 0. 030 0. 082  0 .0912  0,.0011 0 .. 0 0 0 5 0 .. 0 0 2 0 0 .. 0 0 0 8  1 ..0 7  011v1ne  0. 7091 0. 7054 0. 7064 0. 7133  0 . 116 0,. 0 5 5 7 0, 1518 0 .. 102  0,.001 0..0015 0. 0012  0. 323 0. 456 0. 418 0. 267  0..015 0. 006 0. 013  0. 7095 0. 7056 0. 7099 0. 7096  0. 001 1 0. 0005 0. 0006 0. 0031  0. 348 1. 0 5 1. 1 0  . IH Urn  0. 2  cs 3  Syn. wr Diopside Enstatite 01 1 v 1 n e  0..001  0,.008  1. 0 4  0. 03 0. 012 0. 02 0. 05  Table Sample  ( 8 7 S r / 8 6 S r ) +/-  5-7  Summary  D a t e ( M a ) + /-  of mineral  Petrology  Isochrons Texture  Chemistry  Depth(km)  uL1 JL14 JL15 JL18  0 0 0 0  . 7028 .7024 .7025 . 7026  0 .0001 0 .0001 0 .0001 0 .O001  560 450 576 34 1  47 55 41 137  Lherzol1te Lherzol1te Lherzol1te Lherzol1te  Protogranular Protogranu1ar Protogranular Protogranu1ar  Undepleted Undepleted Undepleted  46 <vJL14 <JL 15  BM 1 1 BM16 BM55  0 . 7028 O 7019 0 . 7032  0 .0001 0 .0016 0 .0002  276 1518 396  82 24 1 27  Lherzol1te 011v-Lherz 011v-Lherz  Protogranu1ar Equ1granular Protogranular  Depleted Undepleted Undepleted  <BM16 30 >BM16  KR 1 KR2 KR35  0.. 7030 0 . 7028 0 7018  0 .0007 0 .0001 0 .0001  561 792 1537  63 58 74  Lherzol1te Lherzol1te Lherzol1te  Proto-porph Porphyroclast1c Equ1granular  Depleted Depleted Undepleted  40 49 33  LL1 LL14  0. 7029 0. 7037  0 .0002 0 .0002  101 645  18 50  Lherzol1te Lherzol1te  Protogranular Protogranular  Depleted Depleted  46 52  JM5 JM14 JM15  0. 7035 0. 7038 O. 704 1  0. 0008 0. 0009 0. 0006  428 441 366  78 85 64  Harzburglte Harzburglte 01Iv-Harzb.  Protogranular Porphyroclast1c Protogranular  Depleted Depleted Depleted  35-63  75  Fig.  5-1  J L 1 m i n e r a l I s o c h r o n d e f i n e d by D i , En, 0 1 . ( 8 7 S r / 8 6 S r ) , = 0.7028+/-0.0001, s l o p e = 0.0080+/-0.0007 R b - S r d a t e = S59+/-47 Ma.  F1g.  5-2  J L 1 4 m i n e r a l I s o c h r o n d e f i n e d by WR, D i , En, 01. ( 8 7 S r / 8 6 S r ) „ = O.7024+/-O.0001, s l o p e = 0.00G4+/-O.0008 R b - S r d a t e = 450+/-55 Ma.  77  Fig.  5-3  JL15 mineral i s o c h r o n d e f i n e d by WR, ( 8 7 S r / 8 6 S r )« = 0.7025+/-0.0001. s l o p e R b - S r d a t e = 576+/-41 Ma.  D i , En, 0 1 . = 0.0082+/-0.0005  78  Fig.  5-4  JL18 mineral i s o c h r o n d e f i n e d by D i , E n . 0 1 . ( 8 7 S r / 8 6 S r )„ = 0.7026+/-0.0001. s l o p e = 0.0049+/-0.0019 R b - S r d a t e = 341+/-137 Ma.  79  F1g.  5-5  BM11 m i n e r a l I s o c h r o n d e f i n e d by D t . En, 0 1 . ( 8 7 S r / 8 6 S r ) = O.7028+/-O.OOO1. s l o p e = O.0039+/-O.0009 R b - S r d a t e = 275+/-82 Ma. 0  80  81  Fig.  5-7  BM55 m i n e r a l i s o c h r o n d e f i n e d b y D i , En, 0 1 . ( 8 7 S r / 8 6 S r )„ = 0.7032 + /-0.0002, s l o p e = 0.0056+/-0.0003 R b - S r d a t e = 396+/-27 Ma.  Fig.  5-8  KR1 m i n e r a l I s o c h r o n d e f i n e d b y D i . En, 0 1 . ( 8 7 S r / 8 G S r ). = O.7030+/-0.0007. s l o p e = 0.0080+/-O.0003 R b - S r d a t e = 561+/-63 Ma.  Fig.  5-9  KR2 m i n e r a l I s o c h r o n d e f i n e d by WR. D i . En. ( 8 7 S r / 8 6 S r ) „ = 0 . 7 0 2 8 + / - 0 . O O O 1 . s l o p e = 0.0113+/-0.0008 R b - S r d a t e = 792+/-58 Ma.  84  Fig.  5-10  KR35 m i n e r a l I s o c h r o n d e f i n e d b y WR, 0 1 , E n . 0 1 . ( 8 7 S r / 8 6 S r )„ = 0.7018+/-0.0004. s l o p e = 0.0221+/-0.0007 R b - S r d a t e = 1537+/-74 Ma.  A  -  •  -  0 t o p s tote Enstatite  * - 01 1 v 1 n e o - S y n . WR •  -  Whole  0 V  -  Acid Host  rock leachate basal t  0  0.25  Fig.  0.5  5-11  0.75  1 0  1 .25  l .5  2.25  2.5  "Rb/^'Sr  LL1 m i n e r a l i s o c h r o n d e f i n e d by WR, D 1 . En. 01. ( 8 7 S r / 8 6 S r ) „ = O.7029+/-0.0002, s l o p e = 0.0014+/-0.0002 R b - S r d a t e = 101+/-18 Ma. T h i s s a m p l e i s p a r t i a l l y m e l t e d . The a s s o c i a t e d b a s a l t h a s g a i n e d 8 7 S r .  * • *  O(ops)de Enstatite 01ivine o - S y n . WR * - Whole rock 0 - Acid leachate V - Host basalt  o.o  0.25  Fig.  0.5  5-12  0 75  I 25  I 5  -  2.25  "Rb/^Sr  LL14 m i n e r a l i s o c h r o n d e f i n e d by 0 1 . En. 0 1 . ( 8 7 S r / 8 6 S r ) » = 0.7037+/-O.OO01. s l o p e = O.0092+/-0.0006 R b - S r d a t e = 645+/-49 Ma.  2 5  87  Fig.  5-13  JM5 m i n e r a l i s o c h r o n d e f i n e d by O i , En. 0 1 . ( 8 7 S r / 8 6 S r )„= O.7035 + /-O.0008, s l o p e = O.0061+/-O.0011 R b - S r d a t e = 428+/-78 Ma.  88  Fig.  5-14  JM14 m i n e r a l i s o c h r o n d e f i n e d by D i , En, 0 1 . ( 8 7 S r / 8 6 S r ) » = 0.7038+/-0.0009. s l o p e = 0.0063+/-0.0011 R b - S r d a t e = 441+/-85 Ma.  89  Fig.  5-15  JM15 m i n e r a l I s o c h r o n d e f i n e d by D i . En. 0 1 . ( 8 7 S r / 8 6 S r ) = 0 . 7041+/-0.0006. s l o p e = 0.0052+/-0.0008 R b - S r d a t e = 366+/-64 Ma. 0  90 VI.  General Mid  considerations  ocean  contents  ridge basalt  a n d low Rb/Sr  , Sr = 90-200 ppm, 0.0029-0.058), and Volcanism typical If  Study  Sr  Project,  Sr/  8 6  Sr  8 7  Sr/  8 6  sample  flood  =  (Basaltic  i s n o t so d e p l e t e d i n  or " e n r i c h e d "  (Basaltic  mantle.  alkali  = 0.703-0.707  i n t e r p r e t e d as showing 1984) o r o r i g i n  Rb and S r c o n t e n t s  i . e . Rb>l0 ppm, (Basaltic  present,  i t i s inferred  from  Sr  Study  region  i s from an  i n the mantle, and  a r c b a s a l t has Rb c o n c e n t r a t i o n 8 6  ppm  i s no c o n t i n e n t a l c r u s t  due t o s m a l l d e g r e e s o f p a r t i a l  Sr/  and  Sr = 400-4000  Volcanism  that the b a s a l t source  8 7  Study  1985).  1981). B e c a u s e t h e r e  S r 135 - 540 ppm,  and  b a s a l t and some c o n t i n e n t a l  ratios,  or e n r i c h e d  Volcanism  (Carlson,  Project,  and  Sr  8 6  b a s a l t s have h i g h Rb, Sr c o n t e n t s  Sr  Island  Rb/  i t i s ascribed to c r u s t a l  8 6  enriched  8 7  mantle.  Sr/  undepleted  (or  i . e . Rb<10 ppm  1981), and i s v i e w e d a s from a  b a s a l t s have h i g h Sr  ratios,  = 0.702-0.703  from t h e c r u s t  island  Sr  =0.001-0.02  l i t h o s p h e r e (Church,  middling  further  8 6  1981) and a r e most o f t e n  within-plate  8 7  8 7  = 0.70369-0.70503  Ocean  and  Sr/  (MORB) has low Rb a n d S r  o r an " u n d e p l e t e d "  contamination ancient  8 7  elements,  Continental 8 6  Rb/Sr  a mantle-derived  contamination  Sr/  and  Project,  "depleted"  incompatible  8 7  DISCUSSION  melting.  o f 2.4 - 32  = 0.70328 ± 0.00015  ppm  91 (Basaltic is  Volcanism  i n f e r r e d to  Study  Project,  originate  from m e l t i n g  subducted  basaltic layer  without  s e d i m e n t a r y component  a  Boettcher,  1977;  melting  the  (e.g.  of  Nicholls  peridotite from  the  now  of  and  the  oceanic  and  Ringwood,  crust,  by  oceanic  1973). In  any  case  (e.g.  to  of  1968;  hydrous  subducted  of  slab  of  water or  Nicholls  the  or  from m e l t i n g  i t s enrichment  universally attributed  with  from  the  introduction  crust  basalt  Ringwood,  1978); or  1973); or  arc  dehydration  ( G r e e n and  Wyllie,  mantle m o d i f i e d  subducted  and  p e r i d o t i t e wedge o v e r l y i n g  subducted  Ringwood, is  Stern  1981). I s l a n d  melt  and  in LIL  contamination  and  8 7  Sr  with  material.  Basalts (1) . J a c q u e s Lake and Basalts have v e r y normal are  high  relatively  a  uniform  859 8 7  ppm  Rb/  from  8 6  Sr  contents,  Rb,  12.7  low,  Rb  of Sr  layers  River  1 to  3  1 down t o  increases  0.7036 t o  continental  - 62.1  concentration  layer  1276  -  Big  Timonthy  1514  ppm.  ppm,  Their  and  Lassie  8 7  Mountain  but Sr/  rather B 6  Sr  ratios  or  Lake  i n West K e t t l e of  17  642  slightly  ppm.  ppm  of  i s l a n d arc  River  Their  Sr  layer  3.  upwards but  0.7029. T h e s e b a s a l t s  flood  Mountain  0.70254-0.70301.  West K e t t l e  Basalt  Timothy  from J a c q u e s Lake and  r a n g e of  (2)  Big  are  basalts.  8 7  Sr/  quite  locality varies  have  from  Accordingly, 8 6  Sr  decreases  similar  to  92 Basalt section, higher all,  8 7  layer  4, t h e t o p l a y e r  h a s a much h i g h e r Rb/  8 6  Sr  0.70289,  of  a low  8 7  Sr/  Rb, h i g h e r  ratio.  Its  implying  this  i n t e n s i v e metasomatism 8 6  Sr  KR35 has s i m i l a r  i n t h e West K e t t l e  8 7  Sr/  8 6  Sr  layer  mantle  source.  c h a r a c t e r , with  Sr c o n c e n t r a t i o n , a n d ratio  i s the lowest  resulted  or u n u s u a l l y  River  from  recent  of  more  s m a l l degree of m e l t i n g  Basalt adhering even  lower  8 7  to nodule  Sr/  Sr  8 6  ratio,  0.7026. Basalt  adhering  concentrations, low  8 7  Sr/  8 6  The has  Sr  18.5 a n d 701 ppm  ratio,  8 7  Sr/  8 6  Sr  I t i s most l i k e The  Sr/  ocean  8 6  Sr  island  basalts 0.703  ratio,  t o n o d u l e LL1  ratio, ocean  nodule-bearing  nodule LL1) a r e very 8 7  respectively,  and a v e r y  0.70254.  basalt adhering  a higher  ppm.  t o n o d u l e LL14 has c o m p a r a b l e Rb and Sr  i s an e x c e p t i o n . I t  0.7033, Rb=31.8 ppm and Sr=840  island  alkali  b a s a l t s (except  similar  basalt. that adhering  t o mid ocean  ridge basalt in  b u t Rb and S r c o n c e n t r a t i o n s a r e more  (Armstrong,  in British  Columbia  have  8 7  p e r s . comm., 1985) so t h e s e  Sr/  8 6  Sr  with  are q u i t e e x c e p t i o n a l . Nodules, nomative n e p h e l i n e ,  The  mantle" or c r u s t a l  metasomatism the  subducted  these  above  nodules a n d non  Sr a r e a l l a s s o c i a t e d .  h i g h Rb a n d S r c o n t e n t s  "primitive  like  - within plate continental basalts. Plateau  in general  radiogenic  to  c a n n o t be e x p l a i n e d by a  contamination  i n which the metasomatic sediments or a l t e r e d  mechanisms w i l l  fluid  or the i s derived  from  b a s a l t , b e c a u s e any o f  lead to d i s t i n c t l y  higher  8 7  Sr/  8 6  Sr  93 ratios  t h a n MORB.  One that  hypothesis  they are  subduction oceanic. first arc to  and  the  Sr/  B 6  Sr  alternate in  this  Sr/  Rb  8 6  was  generated  small  so  that  under  layer  explanation  by  for a l k a l i  ratio.  This  i s not  8 7  Sr/  with  low  8 7  Sr/  basalts fluid  but  of  previously  8 6  n o d u l e s has  Sr  ppm)  and  high  acid-leach  interstitial  material,  and  etched  material  leaching. 0.7084 and one  The 8 7  glass  Rb/  sample  8 6  Sr  adhering  from has  the  Sr  0.36  Rb/Sr  and  of an  require low  Big and  ppm  Sr,  loss  of  weight  Compared  Lassie  of  weathering  3.6  high  ratio;  ppm  1 mg.  is  relative  beaker  i s about  low  ratio  i s a mixture  basalt,  Rb,  degree  would  pyrex g l a s s  = 0.288. The  leaching  Sr  in K e t t l e River  material  more  the  0.703 i n J a q u e s L a k e and  0.705-0.706  (0.7030  recognized.  the  Lake n o d u l e s . The  Sr  unusually  from  i s about  were  plume/metasomatism  material  ratio  8 7  high  Acid-leach  Sr  typically  Garibaldi  and  nodules  8 6  is  is  plate  (0.7025) was  Ultramafic  (4-78  Fuca  the  melting  basalts  basalts  downgoing p l a t e  have h i g h e r  mantle c h a r a c t e r i z e d  T i m o t h y M o u n t a i n and  for  the  partial  de  Fuca p l a t e  melting  basaltic  bearing  Juan  were g e n e r a t e d . R e c e n t  (0.2-3 ppm), Sr/  partial  s t a g e s of  of  J u a n de  case a plume/metasomatic  Sr  nodule  a result  2-1).  oceanic  ratio  a depleted  8 7  basalts  in l a t e r  melting  as  the  s e d i m e n t s on  i n the  0.7036). The  of  8 7  Figure  oceanic  involved  involved  8 7  generated  (see  The  to e x p l a i n  products  during 8 7  Sr/  the to  8 7  Sr  glass the  =  94 amounts o f Rb a n d S r i n t h e a c i d - l e a c h m i x t u r e the  Rb a n d S r c o n t r i b u t e d by t h e g l a s s i s i n s i g n i f i c a n t . (1). An  Jacques  early  Lake  t o mid P a l e o z o i c i s o t o p i c  miminum age a r e r e c o r d e d Ma), The  with  by f o u r m i n e r a l  low S r i s o t o p e i n i t i a l  and  8 7  Rb/  8 6  Sr  ratio  acid-leaching  m a t e r i a l from  corresponding  mineral  interstitial nodule  isochrons.  Rb, S r a n d  isochrons,  m a t e r i a l s might  while  have been  weathering  because  the  to  the depleted-source  in  the nodules  disply  8 7  8 6  Sr  on t h e  in equilibrium events JL15  ratio.  as l a t e r  Sr/  Sr  MORB t o d a y . The  The a c i d - l e a c h m a t e r i a l from  i n c o n t a c t with molten  8 6  implying that the  m i n e r a l s d u r i n g the mantle  c a n be i n t e r p r e t e d  Sr/  8 7  Sr i s o t o p e  and J L 1 8 p l o t  JL14  (576-341  (0.7024 t o 0.7028).  are like  t h e i s o c h r o n due t o h i g h Rb/Sr  ratio or  ratios  isochrons  w i t h m e a s u r e d whole r o c k . Whole r o c k  composition  on  e q u i l i b r a t i o n or  s y n t h e t i c whole r o c k h a s i d e n t i c a l  ratio  the  of c h l o r i d e s ,  recorded  ratio  characteristic an u n d e p l e t e d  by t h e  does not p l o t  The h i g h  metasomatism  basalt,  with  Rb/Sr  i n the mantle  but not t o i s low.  In c o n t r a s t  of the Sr,  pyroxenes  major e l e m e n t  chemistry  and  J L 1 4 d i o p s i d e i n d i c a t e s T i - m e t a s o m a t i s m . Thus t h e m a n t l e  (40  km, 9 9 5 ° C ) r e p r e s e n t e d  MORB s o u r c e . and and if  8 7  Sr/  lies  8 6  Sr  The b a s a l t ratio  nodules  i sa suitable  adhering  t o J L 1 4 has s i m i l a r  t o the nodule  d i o p s i d e a n d whole  on t h e i s o c h r o n . But t h e y  so, the mineral  melting  by t h e s e  i s o c h r o n would  a r e not cognate be r e s e t  a n d g i v e t h e same age a s t h e h o s t  during basalt.  Rb, S r rock  because partial The n o d u l e  95 is  i n t e r p r e t e d a s an a c c i d e n t a l i n c l u s i o n ;  resulted  from m e l t i n g  of a mantle  (2) . B i g T i m o t h y Mid-Proterozoic 276  and m i d - P a l e o z o i c  - 396 Ma), a r e g i v e n  to  measured  by t h r e e  Sr/  8 6  has a high  Sr  oceanic  ratios,  island  Pyroxenes  Rb/Sr  layer  or lens  protogranular  data  plot  be due t o t h e  the a c i d - l e a c h  The s y n t h e t i c whole  element  chemistry.  depleted  rock  an e q u i g r a n u l a r  may have  mid-Paleozoic  mantle  b a s a l t from B i g T i m o n t h y the nodule m i n e r a l  f r o m t h e same m a n t l e  nodules.  The e x p l a n a t i o n  lain  depleted  mantle  underlying  nodules a r e extracted. (3) . K e t t l e R i v e r  i n BM11  n o t . We c a n mantle  between  or l a t e r  Mountain  as that  a less  in  l a y e r s or t h e younger  isochrons.  i s that  but  mid-Proterozoic  (30km, 9 4 0 ° C )  mantle.  Pyroxenes  b u t BM16 does  a r e r e s e t by a m i d - P a l e o z o i c  right-below  the  ratio.  rock  with  0.7033 t o 0.7039, a r e i n t h e r a n g e of  major  that either  derived  whole  i n BM16 and BM55 d i s p l a y an u n d e p l e t e d ,  infer  Host  i s consistent  m a t e r i a l , because  BM55 show T i - m e t a s o m a t i s m  isochrons  rocks  (1518 Ma a n d  isochrons.  b a s a l t s from o n l y , s l i g h t l y  BM11 a d e p l e t e d , and  mineral  t h e i s o c h r o n s . T h i s might  of i n t e r s t i t i a l  material  to the nodules.  dates  r o c k s . The measured  the right-below  effect  8 7  whole  basalt  Mountain  None o f t h e s y n t h e t i c whole the  similar  the host  event.  plots  I t c o u l d n o t be  represented  the host depleted  by t h e  b a s a l t came f r o m a mantle  from  which  96 An by  equigranular  m a n t l e was d a t e d  KR35. T h i s m a n t l e has t h e same d a t e ,  texture,  depth,  i n major  T i - m e t a s o m a t i s m . The whole  8 7  t h e b o u n d a r y between d e p l e t e d  types.  The measured whole r o c k  synthetic adhering  whole r o c k , t o KR35  non-cognate basalt.  during  the event  KR2  Sr/  this  material  8 7  Rb/  8 6  S r are  mantle with the  implying a  have been recorded  mantle  i s on t h e m i n e r a l  i n e q u i l i b r i u m with  l a y e r , the mantle  defined  mineral  isochron  KR2 a r e t o o s c a t t e r e d t o g i v e KR1 and KR2 g i v e Precambrian.  dates  Ignoring  384 Ma, m i d d l e deviated  deformation  mineral  right-below cognate with  an i s o c h r o n .  they  Ignoring  nodules.  from  olivine,  r e s p e c t i v e l y , Late give dates  implying  or l o n g e r  o f 466  that  mantle  exposure t o  has r e s u l t e d i n p a r t i a l  the nodule mineral  gives  respectively. Olivines are  temperature  Host  by KR1  d a t e of 561 Ma. D a t a  orthopyroxene,  isochrons.  the  represented  of p y r o x e n e s . KR1  from t h e i s o c h r o n s ,  temperatures  the m i n e r a l s  i n Sr i s o t o p e s b u t  o f 588 and 799 Ma,  Paleozoic,  or higher  isochron,  by t h e i s o c h r o n .  a poorly  these  and  and show  b u t i s on t h e i s o c h r o n . The b a s a l t  i n major e l e m e n t c h e m i s t r y  elevated  chemistry  i s not i d e n t i c a l  i s p o r p h y r o c l a s t i c , undepleted  seriously  Sr  as BM16.  and u n d e p l e t e d  depleted  and  8 6  ratio,  r e l a t i o n s h i p between t h e n o d u l e and t h e h o s t  i t could  Under  element  i s n o t on t h e i s o c h r o n ,  Acid-leaching  implying  and  rock  Proterozoic  Sr i n i t i a l  and e q u i l i b r i u m t e m p e r a t u r e  Pyroxenes are undepleted  on  as M i d d l e  r e s e t t i n g of  b a s a l t s from K e t t l e R i v e r isochrons,  they  are not  plot  97 ( 4 ) . L a s s i e Lake A protogranular LL14 and in  t o be 645 Ma,  mantle  late  (52 km,  Precambrian.  triplicate,  i t plots  could only a f f e c t  reason  why  not  clear.  isotope with  w e l l below  the nodule,  implying  nodule  came.  event,  Considering section  trend, this  melting  nodule-bearing  isochron,  event.  Sr 8 7  r a t i o , the  Rb/  B 6  Sr  ratio i s Sr  i s not i n e q u i l i b r i u m from a d e p l e t e d  from w h i c h t h e  (46 km,  was r e c o r d e d visible  date  Middle  miogeoclinal Mountain B e l t  may  995°C) the  by L L 1 .  i n the t h i n  The h o s t B 7  Sr/  8 6  be d r a s t i c a l l y basalt adhering  Sr  b a s a l t s . Although  the nodule  because the observed  Belt,  8 6  and t h a t t h e p y r o x e n e s a r e n o t on t h e magmatic  partial  The  analysed  has u n d e p l e t e d  mantle  the c o n s i d e r a b l e melt  n o d u l e has e x c e p t i o n a l h i g h  the  Sr/  depth of the mantle  101 Ma, M e s o z o i c ,  crystallization  other  8 7  t h e b a s a l t came  u n d e r l y i n g the undepleted  In a s h a l l o w e r  has been  has h i g h  basalt  mantle  yougest  rock  The s y n t h e t i c whole r o c k  c h a r a c t e r . The h o s t  by  t h e i s o c h r o n . The h o s t  the nodule  t h e n o d u l e whole r o c k  was d a t e d  Pyroxenes are d e p l e t e d  l a c k T i - m e t a s o m a t i s m . The whole  basalt  the  1008°C),  ratio  occurred  P r o t e r o z o i c to middle  wedge o c c u p i e s  most  t h e b a s a l t p l o t s on  about  the b a s a l t 5 Ma a g o .  Paleozoic  of the c o r e  (Monger a n d P r i c e ,  i n the Intermontane  1979). The Omineca w e s t e r n  Cordilleran  o f t h e Rocky  and u n d e r l i e s p a r t s o f t h e Omineca  but i t i s not o b s e r v e d  to the  compared t o  i s not cognate with  melting  r e s e t by  Crystalline Belt  exposures of  98 basement and  stratigraphic  contain  evidence  Duncan,  1978;  intrusion, the  Mid-Paleozoic explanations record they  f o r the nodule  Proterozoic  time  Josephine The  others,  related  a r e a l l about 1976;  Hotz,  (1984) i n f e r r e d ago  has  to  1971;  160  r o c k s or  reset  to  they  that  from a  at l e a s t  been  single In  any  the  of Ma  by  Coleman  e t a l . , 1982).  and  Harper  generated  157  spreading.  i s dated  three mineral  gabbro  (Harper,  ( D i c k , 1973;  was  on  are  formation  s t a g e s of b a c k - a r c  Ma,  dates  which  Peridotite  Peridotite  dated  isotopic  suite,  Saleeby  the Josephine  t o 441  not  work. The  150  However, J o s e p h i n e 366  that  of c r y s t a l l i z a t i o n .  t o i t s age  in the e a r l i e s t  Paleozoic,  Alternative  mantle  recently  t r o n d h j e m i t e of the o p h i o l i t e  1984),  nodule  Belt.  Peridotite  before t h i s  traditionally  the  Peridotite  Josephine  isotopically  1975),  to m i d - P r o t e r o z o i c to  l i t h o s p h e r e must e x t e n d  edge of t h e Omineca  synchronous  isochrons are  only involved  to Middle  to  history.  mineral  and  o l d mantle  granitic  related  related  - partially  western  Ma  be  geological  that  (e.g.  deformation. C o n s i d e r i n g that  are h y b r i c  Early case  regional  the e v e n t s  e t a l . , 1975)  (e.g. B u r w e l l ,  i s o c h r o n d a t e s may  locally  p e r s . comm.) and  be d i r e c t l y  crust  wedge  Late Precambrian  1985,  metamorphism and  in o v e r l y i n g  mineral  and  (e.g. O k u l i t c h  i s o c h r o n d a t e s may  events  to  of M i d d l e  Armstrong,  mid-Paleozoic  e q u i v a l e n t s of t h i s  t o be  middle  i s o c h r o n s . The  99 discrepancy  between  the a s s o c i a t e d not  rocks  necessarily  r o c k s and  obvious  how  that  same age  Peridotite  the o p h i o l i t e  as o v e r l y i n g  I t p r e s e r v e s . e v i d e n c e of an  rocks  mid-Paleozoic  of J o s e p h i n e  indicates  have t h e  dykes.  event. Other  the d a t e s  i n the Klamath  metamorphic  t h e s e can  be  or  intrusive  related  dates  to the  base  does  volcanic  older  region also  and  mantle  give but  i t i s not  Josephine  Peridotite. Josephine so t h a n 8 7  Sr/  the  8 6  Rb,  Sr  Peridotite  compared  r o c k s were l a s t  Josephine large  degree  arc  basalt  for  multiple  Dick  nodules.  than  and  lack  of m e l t  8 7  Rb/  Sr  8 6  today,  pyroxenes  and and  when  display  Ti-metasomatism. may  and  Both  The  be  interpreted  extraction,  ratio  d e p l e t e d i n S r , more  the nodules,  equilibrated.  Peridotite  Rb/Sr  Sr  and  isotopic  e p i s o d e s of p a r t i a l  as a r e s i d u e o f  the m e l t  had  composition.  m e l t i n g was  island Evidence  r e c o g n i z e d by  (1975).  Mantle The ratios 6-1).  to the  a r e much h i g h e r  extreme d e p l e t i o n  a  i s extremely  growth  fifteen  curve  mineral  have been p l o t A l l nodules  Most n o d u l e s  on  are near  8 7  Sr/  B 6  LL14  "bulk e a r t h "  with  prehistory.  The  curve,  Josephine  initial (Figure  the bulk  evolution  MORB. Some d e v i a t e from evolution  Sr  S r diagram  the depleted-mantle  BABI and  undepleted  a Time -  a r e d e p l e t e d compared  connecting i s on  i s o c h r o n d a t e s and  this  curve  curve.  indicating  Peridotite  earth.  has  an  Only  100 undepleted But  character,  near  t o bulk  earth  evolution  curve.  i t s e x t r e m e Rb and Sr d e p l e t i o n e l i m i n a t e s t h e  "primitive  mantle" e x p l a n a t i o n .  environment Paleozoic,  Considering  i t s island arc  i n t h e J u r a s s i c and p e r h a p s a l s o the high  8 7  Sr/  8 6  Sr  i n the  must be due t o  from  subducted m a t e r i a l during  with  rising  partial  contamination  melting,  and r e a c t i o n  v o l c a n i c a r c magmas.  Summary J a c q u e s Lake n o d u l e s source-type depleted mineral  mantle,  other  represent nodules  mantle. Equigranular isochron  Precambrian,  date  early-mid  Porphyroclastic  mantle with  nodules give  . Protogranular Paleozoic  somewhat a  or o l d e r  nodules give  i n age. Host  o f low  date  f o r the Josephine  Peridotite  view  that  i t was g e n e r a t e d  Orogeny.  8 7  Sr/  or with 8 6  Sr  i s o c h r o n s , but b a s a l t s a r e not 8 7  Sr/  8 6  Sr  recent  ratio.  A Paleozoic  i s in conflict  i n the l a t e  late  dates.  t h e n o d u l e s and come from a low s m a l l d e g r e e of m e l t i n g  less  mid-Proterozoic  and M e s o z o i c  m e t a s o m a t i s m by f l u i d s  Nevadan  represent  n o d u l e s do n o t d e f i n e m i n e r a l  must a l s o be P a l e o z o i c cognate with  a d e p l e t e d MORB  with the  J u r a s s i c just  before  101  1 * ^ 10 13  °-°  5  0  0  1  0  0  0  1 5  0  0  2  -  0  LL 1 J114 KR39 JL 1 JM14  0  0  2 S 8 11 14  -  " 0 0  BM11 JL15 BM5S KR 2 JM 5  3 6 9 12 IS  3000  -  JL18 BM16 KR 1 JM19 LL14  3 5 00  DATE (Ma)  Fig.  6-1  Earth  evolution  curves  ,  0  0 0  4500  5000  102  REFERENCES A l l e g r e , C . J . , Shimizu, N . and Rousseau, D. of t h e c o n t i n e n t a l lithosphere recorded x e n o l i t h s . Nature, 296, 732-735.  (1982) H i s t o r y by u l t r a m a f i c  Allegre,Staudacher, T . , Sarda P . and Kurz, M . 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W y l l i e , P . J . (1967) M a f i c a n d u l t r a m a f i c n o d u l e s i n t r o d u c t i o n . I n : P . J . W y l l i e ( e d . ) U l t r a m a f i c and r e l a t e d r o c k s . W i l e y , New Y o r k , 327-328. Wood, B . J . and Banno, S. (1973) G a r n e t - o r t h o p y r o x e n e and c l i n o p y r o x e n e - orthopyroxene r e l a t i o n s h i p s i n simple and complex s y s t e m s . C o n t r i b u t i o n s t o M i n e r a l o g y and P e t r o l o g y , 42, 109-124. Wood, B . J . (1975) The a p p l i c a t i o n o f t h e r m o d y n a m i c s t o some subsolidus e q u i l i b r i a involving s o l i d solutions. F o r t s c h r i t t e M i n e r a l o g i e , 52, 21-45. Z i n d l e r , A., J a g o u t z , E . and G o l d s t e i n , S. (1982) Nd, S r and Pb i s o t o p i c s y s t e m a t i c s i n a t h r e e - c o m p o n e n t m a n t l e : a new p e r s p e c t i v e . N a t u r e , 298, 519-523.  APPENDIX  CPX  MgO  KR1  15.71  3.89 3.99 3.90 3.99 3.97 4.06  1 5 .. 15 1 5 .. 0 4 14 . 9 3 1 5 .. 2 1 15 . 6 8 1 5 .. 5 3 15 . 3 7 15 . 1 9  14 . 9 3 14 . 8 7 14 . 8 2 1 4 .. 6 8 14 . 6 0 14 . 7 6 14 . 5 5 14 . 8 3 14 . 6 3  4 .80 5 .06 4 86 4 98 4 .68 4 .69 5 .00 5 .05  6 6 6 6 6 6 6  .60 .40 .60 .76 .75 .80 .45  6 .45 6 .25  MgO  A1203  34 .08 32 82 35 .06 3 4 ,. 8 0 34  PROBE ANALYTICAL DATA OF NODULE  A1203  15.45 15.66 15.02 14.82 15.86  OPX  1  89  3 5 ,. 0 0 34 .33 3 3 ,. 8 1 33 .98 3 4 , 51  33 93 34 ,03 3 4 .. 0 1 33 .70 3 4 . 28 3 3 .. 9 9 33 .51 33 .28 34 . 44 34 . 33  2 . 75 2 .82 2 .80 2 .83 2 84 2 . 77 2 .76 2 .90 2 .92 2 .88  3 71 3 82 3 . 64 3 . 66 3 . 82 3 68 3 . 79 3 . 74 3 . 72 3 .65  Na20  S102  1.41 1 . 32 1 . 36 1 .64  CaO  K20  FeO  0.02  2 .09 2.06 2 .06 2 . 16 2.12 2 . 13  54.05  21.12  0  .53.47 54 . 54  21 . 4 2 21 . 2 0 2 0 . 41  0 0 0 0  55 . 22 54 . 1 1  Cr203  53.57  21 . 3 6 21 . 3 5  1 . 17  54 .46  21 . 4 2  0  2 . 35  1 . 18 1 .26  5 3 .. 9 4 53 .76  0 .. 0 2  1 . 24 1 .25  5 3 . 12 53 .29 5 4 .. 0 4 51 . 5 7  21 21 21 21  2 .33 2 .35 2 .33 2 .31 2 .27 2 . 30 2 . 28  1 .42 1 . 36  1 .20 1 .21 1 . 29  1 .58 1 .63 1 .67 1 . 58 1 .58 1 . 54 1 . 49 1 .65 1 . 49  5 3 .. 6 2  52 .85 5 3 . 13 5 3 .01 52 .43 52 .92 51 . 5 5 51 . 8 3 51 . 7 6 51 . 8 6  .32 .59  .39 .36 21 . 4 4 21 . 4 7 21 . 2 6  20. 20. 20. 20. 20. 19. 20.  10 04 14  0 .01 0 0 0 . .01 0 0  0 . .01 0  2 0 . 12 2 0 . 12  0 . ,01 0 . 01 0 0 0 . .01 0 . 01 0 01  15 02 95 04  Na20  S102  CaO  FeO  0 .. 0 8 0 . . 12 0. 05 0 .. 0 5  5 6 ,, 4 0 5 5 , 42 56 ,44 56 , 29  0 . 61 0 .. 5 9 0. 59 0. 59  5 .. 9 0 5 .91 5 . 90 5 80  0. 07 0 .. 0 4 0 . 16 0 .. 0 9 0. 06 0 . . 12  5 6 , 41 5 6 . 19 56 . 75 5 6 ,. 72  0. 0. 0. 0.  56 32 5 5 ,, 7 6  0. 09 0 .05 0 07  55. 67 5 6 . 10 5 5 . 14 55 . 49 55 . 78 5 6 . 15 5 5 .. 7 5 5 5 .. 8 4 53. 60 55 . 26  O .09 0 .04 O . 10 0 .08 0 .05 0 09 0 .07  2 2 2 2 2 2 2  .85 88 92 83 . 97 .. 8 7 . 88 2 . 77 2 . 78  MnO  Total  1 . 27 0.21 1 . 4 5 0 . 18 1 . 18 0 . 19 1 . 13 0 . 15 1 . 28 0 . 2 0 1 . 4 2 0 . 17  0.08  99.83  0.08 0.05 0.05  99.43 100.13 99.76 99 .47  0. 84 0. 97  0 .. 0 8 0. 08  0 .. 0 9  100. 36  0 98 1 .0 2 0, 86 0. 88 1.. 0 2 1. 0 4  0 .. 0 6 0 .. 0 8 0 . . 11  0 .. 0 5 0 .. 0 4 0 0 9 0 ,. 1 0 0 . 10 0 . 0 4 0 .. 0 8 0 .. 0 9 0 . . 1 10 . 11  1 0 0 . .01 9 9 87  1 .00 0. 96 0. 9 9 0 ,, 9 8 0 ,98 0 ,. 9 4 0 .95 1,, 0 3  0. 0. 0. 0. 0. 0. 0. 0. 0.  0  Cr203 0 ,. 5 3 0 . 54 0, 58 0 . 53  0 . 61 0 . 58  5 . 87 5 .. 8 1 5 . 82 5 . 87 5 . 87 5 . 74  0, 55 0. 5 0 0. 5 1 0. 5 2 0. 5 4  0 . 57 0 .. 5 5 0 . 58 0 ,. 5 7  6 07 5 . 94 5 . 89 5 . 85  0 . 53 0 . 58 0 . 61 0 .. 6 0 0 . 58  5 5 5 5 5 5  0. 0. 0 . 0. 0. 0 .  60 61 59 61  0 .. 5 9  . 91 93 88 , 95 . 95 .9 1  MINERALS  0. 5 1  39 39 34 40 44 47  0. 38 0 . 38 0 45 0 4 1  92  T102  26 31  0.09 0 . 11  0 .06  100.05  99 .46 99. 63 100. 20 9 8 . 11 99. 93  32 38 44 34 27  0 ., 1 0 0 .08 0 ., 0 9 0 . . 12 0 ., 0 8 0 . . 14  100. 23 100. 32 1 0 0 ., 5 5 99. 89 100. 38 9 8 . 84 98 .64  28 25  0 . , 13 0 .. 0 9  99. 0 9 8 .. 4 5  Ti02  MnO  Total  0 .02 0 .04 0 .03 C ,03  0 . 14 0 . 16 0 . 18 0 . 16  100 . 5 1 9 8 .41  0  0 . 15 0 . 14 0 . 15 0 . 15 0 . 17 0 : 14  0 0. o. 0 0.  0 0 0 0 0 0 0 0 0 0  06 06  06 03 05 06  .03 .00 .00 .03 .01 .01 .01 .01 .02 ,02  0. 0. 0. 0. 0. 0. 0. 0. 0. 0.  13 19 14 15 12 14 20 15 13 17  101 . 6 3 101 . 0 9 101 4 4 101 .. 12 101 . 12 100. 69 9 9 . 52 100. 29  100 . 5 9 101 . 0 7 9 9 81 99 .94 100 .93 101 0 6 1 0 0 . 21 1 0 0 . 01 9 8 . 98 100. 42  OOOIOO~-I-JOO-JCD10 1  ( 0 ( 0 ( 0 0 ( 0 0 0 0 0 0  i  --i-jCD~jj)*kcnuicnui  0 0 0 0 ( 0 0 0 ( 0 ( 0 1 0 0 1 O u u —(oucncncDOOM i uiOdi-JO-JtuoiOu i  --.^-o--->oo ^CDUifeOfe^icJcnio Oioaicn — o - O o o c o  O O O O O O O O O O O  i  O O O O O O O O O O i  O O O O O O O O O O  o - o o o o o o o - o i u>0(oaoouioo(o-~iO(o i  O O O O O O O O O O i  O O O O O O O O O O a)uicnb(ji<n~jcncncn  i i  fflCtUUOMalU-JCI  LL1  I  OL  CD^4*4CI)^l~<lCDCDC0GDa) 1 O^cjiouicoa)0->icnu  KR 1  LL1  T;  X) 1 K> 1  X i IQ i O i  coo  m 1  mUUIUIMilOllit'l'MIl — cn*»cjcnui — c n c o t o c o u i  O l IO 1  1 01 1 O 1 O  —  ui  —  —  —  C O O I M C D ^ I  -J.UlfOCD-1^1 — ~ J < T > O C 0 M  o o o o o o o o o o o o - 0 0 0 0 - - 0 0 - - O a> co CO (0 O — c o c a o o o uimuiuiuiuiuiuiuiinuiui Ul{i{tGJcnUIU!&UI»UIUI r o t n o f c O ( J u i ^ — lococn conoiouiOuiaa)«oin  o o o o o o o o o o o o (0(0(0(0(0(0(0(0(0(0(0 t  (0(0(01010(010(0(0(0 1  (0(0(0(0(010(0(0(0(0  •n i 1 O i  cj(OcnoA&K>&cn~icno>  (D  COCDCOOOIOCOCDCO^IGOGO 1 ' - l U U U ' U O U - J H 1  M O  — ai^towai-.*.  cncFicncncncncncncncncficn — cotoMuoobjucouiui-i  OOOOOOOOOOOi cnurocDtkCJO^cjino  O O O O O O O O O O i  O O O O O O O O O O i  O O O O O O O O O O  O(oooto(0(ococo(o i O(OO-»GD(0(0(0(0(O l  o o o o g o o o g o  cj~j<n(0an-.cnmcom  cnuiui&~j<»ui--.«CD  i  Toti  a>MOcDO->ucncju} — > uiui^imroOO>ocncD-» i  Z  i  a i  i  t0(0lO(0(O<O(OlO(O(0(Q 1 CDCDCDCDCDCOCDCDOOCDtO 1  Z l  o o o o o o o o o o o o  O 1  i  OOOOOOOOOOO i mO«aou>ioi»-o>o  O O O O O O O O O O  o o o o o o o o o o o o o o o o o o o o o o o o  o»M^jMi»~4or>cn(o~»-j-i  o o o o o o o o o o o o  OlOlOlO(0<0(OIOU>(000 O(0a>03(0(0(0CDCDCDOO U I - I C J — c j ^ i c n o i c o c d — a> UO)I0O«<]1-'UO1>IOM  SP  MgO  A1203  S102  FeO  Cr203  MnO  T1203  total  KR1 17.45 17.56 17.69 17.76 17:60 17.64 17.54  38.44 39.65 38.58 40.00 40.01 40.25 39.84  0.04 0.06 O.OO 0.00 0.00 0.04 0.05  13 . 08 12.72 12.82 12.32 12.72 12.19 12.72  29.63 29.03 29.55 28.44 29.01 28.35 28.38  0.15 0.15 0.19 0.17 0.17 0.16 0.17  0.09 0.09 0.07 0.06 O.10 0.10 0.05  98.88 99.27 98.91 98.75 99.61 98.74 98.75  KR2 20.15 19.84 19.87 19.74 20.03  53.24 53.52 53.41 53.43 52.80  0.04 0.03 0.05 0.06 0.00  10.06 10.08 10. 13 10.05 10.06  15.05 15.27 15.32 15.40 15.37  0.13 0.12 0.09 0.13 0.07  0.00 0.07 0.02 0.00 0.00  98.67 98.93 98.88 98.82 98.34  LL1 19.93 20.09 20.05 19.91 20.05  55.77 55.87 55.77 55.49 55.87  0.06 0.07 0.09 0.07 O.OO  9.45 9.73 9.56 9.70 9.85  12.80 12.86 12.95 12.66 12.74  0.12 0.12 0.11 0.11 0.09  0.07 0.11 0.22 0.01 0.20  98.21 98.84 98.75 97.95 98.79  119  APPENDIX 2 Fe *  and F e *  2  KR1  3  Sp.Mg  oxide  in Spinel  Al  Calculation  (KR1 a s an e x a m p l e )  Si  Fe  Cr  Mn  Ti  Total  17.61 39.54  0.027  12.65  28.94  0.166 0.08  99.01  0.742  0.00080.300  0.647  0.004 0.0017  3.014  wt.% # of  1.319  ions Formula  (Mg,Fe,Mn)(Al,Cr,Fe) 0„ 2  Mg + Mn + F e *  = 0.742 + 0.004 + 0.254 = 1  Al  = 1.319 + 0.647 + 0 . 0 3 4  2  Total and  Fe * 3  + Cr + F e * 3  Fe w i l l  be p a r t i t i o n e d  according to the r a t i o  into  the formular as F e * 2  Fe */Fe * 2  = 2  3  = 0.254/0.034.  Therefore Fe *  = 0.300x0.254/(0.254+0.034) = 0.265  Fe *  = 0.300x0.034/(0.254+0.034) = 0.035  2  3  Accordingly,  m i n e r a l c o m p o s i t i o n has been  to:  ion Mg Al Si Fe * Fe * Cr Mn Ti 2 3  #  0.742 1.319 0.0008 0.265 0.035 0.647 0.004 0.0017 Total  o x i d e wt. o x i d e wt% 29.9 67.2 0.048 19.04 2.79 49.2 0.28 0.14 168.6  17.73 39.86 0.0003 11.3 1 .65 29. 18 0. 166 0.08 99.97  recalculated  120  APPENDIX 3 PROBE ANALYTICAL DATA FOR JOSEPHINE PERIDOTITE PYROXENES ( f r o m D i c k , 1975)  CPX  FeO  J28f U87 1 J120 J120  2.88 2 . 43 2.91 2.30  OPX  FeO  J28f J46h J46h J871 J 1 14 J120 J46g  6 01 5. 83 5. 79 5 . 84 6*. 02 6 . 17 5 . 58  MgO 16 . 98 18.55 17 . 30 18 . 27 MgO 32 33 33 34 34 35 35  83 . 37 63 78 . 70 08 64  S i02 5 1 . 24 52 .96 54 .04 53 . 45  CaO 22 . 73 23.42 22.73 23.77  5 102  CaO  54 56 54 57 54 55 55  1 .73 1 .83 1 39 1 ,,1 1 1 .04 0. 55 0 .79  . 31 . 30 . 6 1 . 28 01 .01 09  A1203 3.84 2.36 5.11 2 . 10 A1203 3 3 3 2 2 2 0  56 34 18 .37 .05 27 .95  Cr203  T102  Total  004 0.03 0 . 16 0.05  9 9 . 15 100.75 103.35 100.63  CT203  T102  Total  0 91 0. 89 0 85 0, 55 0 49 0. 43 0 .55  0 .02 0..04 0 .04 0 .01 0 .01 0..02 0 .03  1 . 46 1 .00 1 . 10 0.69  99 101 99 101 98 99 98  . 37 . 60 . 49 94 32 53 62  121  APPENDIX 4 CALCULATED TEMPERATURE , PRESSURE, DEPTH FROM J.V .ROSS T°C  DIOPSIDE P(kb)  D(km)  JL1 5  T°C  ENSTATITE P(kb) D(km)  1063 1 051 1071 1059 1 072  18.61 17.98 17.73 17.71 19.50  60.6 58.7 58.0 57.9 63.3  1011 1013 .995 992  14.47 14.57 14.84 12.67  48. 1 48.4 49.2 42.6  1053 1 034 1 059 1 067  18.13 17.49 17.89 17.57  59.2 57.3 58.5 57.5  JL18  1 003 1017  14.74 14.73  48.9 48.9  1 024 1018 1 025 1 034 1 040  1 7.28 1 6.32 17.87 17.69 17.85  56.6 53.7 58.4 57.9 58.3  BM55  1038 1 067  16.05 17.76  52.9 58. 1  BM1 6  935 943  9.27 10.41  32.3 35.8  1 1 87 1 064 1145 1 083 117 1  25.70 1 6.62 21 .70 17.74 23.46  82. 1 54.6 70.0 58.0 7 5.4  1 093  1 3.37  44.8  BM1 1 LL1 4  1 024 998  KR35  922 973  17.49 , 15.70  57.3 51 .8  1055 1 067 1 074 1068 1 068  1 7.28 1 7.72 20.51 1 9.07 18.10  56.6 57.9 66.4 62.0 59. 1  8.76 13.06  30.8 43.8  1 058 1 051 1039 1 1 27  1 6.44 15.55 14.10 19.91  54. 1 51.4 47.0 64.6  122  APPENDIX 5 C C C C C C C C C C C C C C C  PROGRAM  "RBSR"  PROGRAM "RBSR" REWRITTEN FROM BASIC PROGRAMS "RBSPK3" AND "SRSPK3" BY MIN SUN, 1984. THIS PROGRAM IS FOR SPIKED RB,SR DATA REDUCTION. TO RUN IT,2=(DATAFILE),GETTING SAMPLE NAME,WEIGHT,RB SPIKE WEIGHT, RB85/87,+/-,SR SPIKE WEIGHT,4/6,+/-,7/6,+/-. BLANK VALUES HAVE BEEN PUT INTO THE PROGRAM. TO CHANGE THEM, JUST CORRECT X R B ( 5 ) , Y R B ( 5 ) , X S R ( 6 ) , Y S R ( 6 ) , X S R ( 7 ) , Y S R ( 7 ) . RB,SR SPIKE VALUES HAVE BEEN PUT IN THE PROGRAM. TO CHANGE THEM, JUST CORRECT X R B ( I ) , Y R B ( I ) , 1 = 2 - 4 , X S R ( J ) , Y S R ( J ) , J = 2 - 5 WEIGHING ERRORS ARE .0001. SR88/86=8.3752+/-.00001.  DIMENSION X R B ( 9 ) , Y R B ( 9 ) , E R B ( 4 ) , S R B ( 4 , 9 ) , 1 XSR(12),YSR(12),T(11),F(11),SSR<6,12),ESR(6) WRITE(7,10) WRITE(8,11) WRITE(9,12) 10 FORMAT(//'RB SPIKE CONC(MICMOL/G) = .01069+/-.00007 */ 1'%87=99.2+/-.0l, %85=0.803+/-.004*/'RB BLANK=.0000036+/-*, 1 '.0000012 MOCROMOLES'//15X,'RBMICMOL/G',4X,'+/-', 1 6X,'RBPPM*,5X,'+/-',3X,'RB87MICMOL/G*,2X,'+/-',6X,'%BLANK', 1 3X,'RB87/SR86 +/-*) 11 FORMAT(//'SR SPIKE CONC(MICMOL/G) = .01150 + /-.00003 */ 1 'SR6/4=.00202+/-.00001,8/4=.01244+/-.00012,7/4=.00111+/-.00005' 1 'SR BLANK=.000047+/-.000032 MICROMOLES, 7/6=.7114+/-.0054'// 1 1X,'SRMICMOL/G',4X,'+/-',6X,'SRPPM',6X,'+/-',3X,'SR86MICMOL' 1 ,'/G',2X,'+/-',5X,'7/6 NORM',4X,'+/-',2X,'7/6 NORM-BLK', 1 3X,'+/-',5X,'%BLANK',3X,'86/88 MIX',2X,'CONV.CYS') 12 FORMAT(//l8X,'RBPPM',6X,'+/-',6X,'%BLANK',4X,'SRPPM',6X, 1 '+/-',5X,'SR87/86',6X,'+/-',5X,'%BLANK',3X,'RB87/SR86 +/-') IC=0 READ(2,20)CH1,CH2,CH3,XRB(7),XRB(6),XRB(8),YRB(8),XSR(11), 1 XSR(8),YSR(8),XSR(9),YSR(9) IF(IC.EQ.0)GOTO 17 20 FORMAT(///A4,1X,A4,1X,A4,F9.5,4F8.5,F10.5,F9.5,2F8.5) C 20 FORMAT(A4,1X,A4,1X,A4,F9.5,4F8.5,F10.5,F9.5,2F8.5) 15 READ(2,21)CH1,CH2,CH3,XRB(7),XRB(6),XRB(8),YRB(8),XSR(11), 1 XSR(8),YSR(8),XSR(9),YSR(9) 21 FORMAT(A4,1X,A4,1X,A4,F9.5,4F8.5,F10.5,F9.5,2F8.5) 17 WRITE(6,20)CH1,CH2,CH3,XRB(7),XRB(6),XRB(8),YRB(8),XSR(11), 1 XSR(8),YSR(8),XSR(9),YSR(9) DATA BLAN/'BLAN'/ IF(CH2.EQ.BLAN)GOTO 18 XRB(5)=0.0000036 YRB(5)=0.0000012 XSR(6)=0.000047  123  YSR(6)«0.000032  GOTO 19 18  c  XRB<5)-0.00000001 YRB(5)»0.000000005 XSR(6)»0.0000001 YSR(6)=0.00000005 19 XSR(7)=»0.7114 YSR(7)»0.0054 * * * * * * * * * * * * g DATA REDUCTION*********************** XSR(2)=0.0115 YSR(2)=.00003 XSR(3)=.00202 YSR(3)=.00001 XSR(4)=.01244 YSR(4)=.00012 XSR(5)=.00l11 YSR(5)=.00005 XSR(10)=8.3752 YSR(10)=.00001 YSR(11)=.00001 YSR(12)=.00001 XSR(12)«XRB(7) XSR(12)=XRB(7) XSR(1)=0.0 YSR(1 )=0.0 CALCULATION DO 150 1=1,12 XSR(I)=XSR(I)+YSR(I) C SPIKE (4 + 6 + 8 ) / ( 4 + 6+7 + 8) A=(XSR(3)+XSR(4)+1.0)/(XSR(3)+XSR(4)+XSR(5)+1.0) W=A*XSR(2)*XSR(11) C SPIKE 4/(4 + 6 + 8) A4=1/(XSR(3)+XSR(4)+1) C SPIKE 6/(4 + 6 + 8) A6=XSR(3)/(XSR(3)+XSR(4)+l) C SPIKE 8/(4 + 6 + 8) A8=XSR(4)/(XSR(3)+XSR(4)+1) R1=XSR(8) F(1)=XSR(10) C ITERATION FOR FRACTIONATION DO 100 J=2,11 C..COMMON SR 4/6=.056584,8/6=8.3752 SO 6/(4+6+8)=0.106024 C 4/(4 + 6 + 8) = .005999,8/(4+ 6 + 8) = .887976 C SAMP+BLK (4 + 6+8) T(J)=W*(A4-R1*A6)/(R1*0.106024-0.00 5999) C SAMP + BLK 86 B6=T(J)*0.106024 C SAMP + BLK 88 B8=T(J)*0.887973 C SAMP + BLK 88/86 CAL C=B8/B6 C SAMP + B L K + SP 88/86 C A L R3=(B8+A8*W)/(B6+A6*W) R  c  124  C  SAMP+BLK+SP ( 8 8 / 8 6 ) C A L / ( 8 8 / 8 6 ) M E A S F(J)-R3/XSR(10) F2-F(J)-0.5*(F(J)-1.0) R1-XSR(8)*(1/F(J)) R2«XSR(9)*F2 K-J-1 I F ( A B S ( F ( J ) - F ( K ) ) . L T . 0 . 0 0 0 0 0 1 ) GOTO 110 100 CONTINUE CALCULATION C S S R ( L , 1 ) = F ( X 2 , . . . X 1 2 ) VALUES WITHOUT ERRORS C . . . . . S S R ( L , 2 ) » F ( X 2 + D X 2 , . . . X 1 2 ) VALUES WITH ERRORS 110 SSR(1,I)-T(J) C 6/8 MIX I F ( I . E Q . 1 ) R4-1/R3 C SAMP+BLK+SP 87 G»R2*(B6+A6*W) C. .. . SAMP+BLK 87 B7»G-XSR(2)*XSR(11)*XSR(5)/(XSR(3)+XSR(4)+XSR(5)+1.0) C SR MICMOL/G SSR(2,I)=(T(J)+B7-XSR(6))/XSR(12) C SR PPM (COMMON SR ATMWT=87.62) SSR(3,I)=SSR(2,I)*87.62 C BLANK 87 C7=XSR(6)*XSR(7)/(XSR(7)+0.056584+1+8.3752) C BLANK 86 C6=C7/XSR(7) C SR86 MICMOL/G SSR(4,I)=(B6-C6)/XSR(12) C SR87/86 SSR(5,I)=B7/B6 C SR87/86 (-BLK) SSR(6,I)*(B7-C7)/(B6-C6) XSR(I)=XSR(I)-YSR(I) 150 CONTINUE ERRORS C DELTF=SORT(SIGMA(DF/DXI*DXI)**2) C DF/DX2*DX2 = F(X2+DX2, . . .XI 2 ) - F ( X 2 XI 2) DO 170 J=2,6 ESR(J)=0 DO 160 1=2,12 ESR(J)=ESR(J) + (SSR(J, I )-SSR(J, 1 ) ) * * 2 160 CONTINUE ESR(J)=SQRT(ESR(J)) 170 CONTINUE Q— — RESULTS — BLKSR=XSR(6)/(SSR(1,1)+B7)*l00 WRITE(8,180)CHI,CH2,CH3,SSR(2,i),ESR(2),SSR(3,1),ESR(3), 1 SSR (.4 , 1 ) ,ESR( 4 ) ,SSR( 5, 1 ) ,ESR( 5) , SSR( 6, 1 ) , ESR ( 6 ) , BLKS 1 R4,K 180 FORMAT(A4,1X,A4, 1 X , A 4 / 2 F 1 0 . 6 , 2 F i 0 . 5 . 2 F 1 0 . 7 , 6 F 1 0 . 5 , 6 X , I 2) Q * * * * * * * * * * * * * g DATA REDUCTION * * * * * * * * * * * * * * * * * * * * * * * * * XRB(2)=.01069  c  c  R  125  YRB(2)-.00007 XRB(3)-99.2 YRB(3)«.0l XRB(4)«.803 YRB(4)=.004 YRB(6)=.0001 YRB(7)=.000l C...  c  C C  C  40 C C C  50 c  C C  60 C 70 C  200  FRACTIONATION  FACTOR  XRB(9)-1.0 YRBC9)».003 CALCULATION S ( J , 1 ) = F ( X 2 , . . . X 9 ) VALUES WITHOUT ERRORS S(J,2)=F(X2+DX2,...X9) VALUES WITH ERRORS XRB(l)-0 YRB(1)»0 DO 50 1 = 1,9 XRB(I)»XRB(I)+YRB(I) XRB(8)=XRB(8)*XRB(9) MMOL RB(SAMP+BLK) SRB(1,I)=(XRB(3)*XRB(8)-XRB(4))/(72.1654-XRB(8)*27.8346 1 )*XRB(2)*XRB(6) I F ( S R B ( 1 , 1 ) . L T . 0 . 0 ) WRITE(6,40) FORMAT('WARNING!! UNDERSPIKED...RB<0') MMOL/G RB (SAMP) SRB(2,I)=(SRB(1,I)-XRB(5))/XRB(7) • PPMRB S R B ( 3 , I ) = S R B ( 2 , I )*85.48 RB87 MMOL/G SRB(4,I)-SRB(2,I)*0.278346 XRB(I)=XRB(I)-YRB(l ) CONTINUE ERRORS DELTF=SQRT(SIGMA(DF/DXI*DXI )**2) DF/DX2*DX2=F(X2+DX2, . . . X 9 ) - F ( X 1 X9) DO 70 J=2,4 ERB(J)=0.0 DO 60 1=2,9 ERB(J)=ERB(J)+(SRB(J,I)-SRB(J, 1 ))**2 CONTINUE ERRORS ERB(J)= SQRT(ERB(J)) CONTINUE RESULTS RBBLK=XRB(5)/SRB(1 ,1 ) * 1 00 RBTSR=SRB(4,1)/SSR(4, 1 ) ERBSR=SQRT(ERB(4)**2/SRB(4,1)**2+ESR(4)**2/SSR(4,1)**2) 1*RBTSR WRITE(9,200)CH1,CH2,CH3,SRB(3,1),ERB(3),RBBLK,SSR(3,1), 1 ESR(3),SSR(6,1),ESR(6),BLKSR,RBTSR,ERBSR FORMAT(A4,1X,A4,1X,A4,1 OF 10.5) WRITE(7,80)CHI,CH2,CH3,SRB(2,1).ERB(2).SRB(3.1).ERB(3).  126  80  1 SRB(4, 1 ) ,ERB(4) ,RBBLK,RBTSR,ERBSR FORMAT(A4,1X,A4,1X,A4,2F10.7,2F10.6,2F10.7,3F10.6) IF(CH1.NE.END)GOTO 15 STOP END  127  APPENDIX 6-a C  c c c c c c c c c c c c c c.  PROGRAM "YORK"  REVISED FOR RB-SR ISOCHRONS IN JAN., 1985 BY MIN SUN. B= APPROX. SLOPE, N = NO. OF POINTS X = 87RB/86SR, P = 1/SIGMA SQUARED OF X Y = 87SR/86SR, Q = 1/SIGMA SQUARED OF Y (THUS EACH POINT IS INDIVIDUALLY WEIGHTED ACCORDING TO ITS ACCURACY) FOR PB, WHEN R=1 ALL ERROR IS ASSUMED TO BE IN THE 204 MEASUREMENT WHEN R=0 , RANDOM ERRORS ARE ASSUMED : THIS IS EQUIVALENT TO THE OLD LEAST SQUARES CUBIC RESULTS. INTERMEDIATE VALUES OF R ASSIGN ERRORS PROPORTIONALLY BETWEEN THESELIMITS FOR RB-SR, R=0  DIMENSIONX(100),Y(100),U(100),V(100),P(100),Q(100),Z(100), 1R(100),F(100),G(100),ZIP(100),DX(100),DX2(100),ZAP(100), 2DY2(100),DAX(100),SDAX(100),DAY(100),SDAY(100),RESX(100), 3C(100),EX(100),EY(100),SANO(100),CH1(100),CH2(100), 4AL(100),DY(100),RESY(100),CH3(100) 100 WRITE(6,99) 99 FORMAT('INPUT # OF P O I N T S ( I 3 ) , T I T L E ( A 1 2 ) ' ) READ(5,1)N,TITLE1,TITLE2,TITLE3 1 FORMAT(13,1X,A4,A4,A4) IF(N.EQ.O) GOTO 300 DO 110 1=1, N R(I)=0.0 READ(2,7) C H 1 ( I ) , C H 2 ( I ) , C H 3 ( I ) , Y ( I ) , E Y ( I ) , X ( I ) , E X ( I ) 7 FORMAT(A4,1X,A4,1X,A4,50X,2F10.5,10X,2F10.5) P(I)=1/EX(I)**2 Q(I)=1/EY(I)**2 110 CONTINUE B=(Y(N)-Y(1))/(X(N)-X( 1 ) ) EPS=0.0001 ITMAX=10 ITER-0 SLOPE=B WRITE(7,50)TITLE1,TITLE2,TITLE3 50 FORMAT(//40X,'YORK REGRESION FOR ',3A4/) 10 B=SLOPE WRITE(7,55)B 55 FORMAT( 1 OX, 'TRIAL SLOPE=*,F10.5) ITER=ITER+1 SUMZ = 0 . 0 XBAR = 0 . 0 YBAR = 0 . 0 BE = 0.0 D = 0.0 E = 0.0  128  ZU2 = 0 . 0 SUMT - 0 . 0  SUMS » 0 . 0 SUMF = 0 . 0  SUMG = 0 . 0  ZIPS = 0 . 0 DXS = 0 . 0 ZAPS = 0 . 0 DYS = 0 . 0 DBS = 0 . 0 SZUM = 0 . 0 SDAXS = 0 . 0 SDAYS = 0 . 0 ALPHA = 0 . 0 DUJB = 0 . 0 DVJB = 0 . 0 BETA = 0 . 0 SUPER=0.0 RENO=0.0 DO 2 1 = 1 ,N AL(I) = SQRT(P(I)*Q(I)) Z<I) = P ( I ) * Q ( I ) / ( B * B * Q ( I ) + P ( I ) - 2 . 0 * B * R ( I ) * A L ( I ) ) 2 SUMZ = SUMZ + 2 ( 1 ) DO 3 I = 1 , N XBAR = XBAR + Z ( I ) * X ( I ) / S U M Z 3 YBAR = YBAR + Z ( I ) * Y ( I ) / S U M Z DO 4 1 = 1 , N U ( I ) = X ( I ) ~ XBAR V ( I ) = Y ( I ) - YBAR BE = BE + ( Z ( I ) * * 2 ) * ( ( U ( I ) * * 2 ) / Q ( l ) - ( V ( I ) * * 2 ) / P ( I ) ) D = D + (Z(I)**2)*(U(I)*V(I)/P(I)-R(I)*(U(I)**2)/AL(I)) ZU2 = ZU2 + Z ( I ) * U ( I ) * U ( I ) SUMT = SUMT + Z ( I ) * X ( I ) * X ( I ) F(I)=(Z(I)**2)*V(I)*(U(I)/Q(I)+B*V(I)/P(I)"R(I)*V(I)/AL(I)) G(I)=(Z(I)**2)*U(I)*(U(I)/Q(I)+B*V(I)/P(I)-B*R(I)*U(I) 1/AL(I)) SUMF = SUMF + F ( I ) SUMG = SUMG + G ( I ) 4 E = E + (Z(I)**2)*(U(I)*V(I)/Q(I)-R(I)*(V(I)**2)/AL(I)) SLOPE = (-BE + SQRT(BE**2 + 4.0*D*E))/(2.0*D) IF(ITER.GT.ITMAX) GOTO 101 I F ( A B S ( S L O P E - B ) . G T . A B S ( E P S * S L O P E ) ) GOTO 10 SLOPE2 = SUMF/SUMG DO 5 I = 1,N 5 SUMS = SUMS + Z ( I ) * ( ( V ( I ) - S L O P E * U ( I ) ) * * 2 ) CINT = YBAR - SLOPE*XBAR VARB = 1.0/ZU2 SIGMAB = SQRT(VARB) VARA = VARB*SUMT/SUMZ SIGMAA = SQRT(VARA) DO 80 I = 1 ,N ZIP(I) = Z(I)**2*(SLOPE**2*V(I)/P(I)-2.0*(SLOPE**2)* 1R(I)*U(I)/AL(I) + 2.0*SLOPE*U(I)/Q(I) - V ( I ) / Q ( I ) )  129  ZAP(I) = Z(I)**2*(SLOPE**2*U(I)/P(I)-2.0*SLOPE*V(I) 1/P(I)-U(I)/Q(I) + 2.0*R(I)*V(I)/AL(I)) ZIPS = ZIPS + Z I P ( I ) ZAPS = ZAPS + Z A P ( I ) ALPHA=ALPHA+4.0*(Z(I)**3*(R(I)*AL(I)-SLOPE*Q(l))* 1(SLOPE*U(I)-V(I)) 1*(U(I)/Q(I)+SLOPE*V(l)/P(l)-R(l)*(SLOPE*U(I)+V(l))/ 2AL(I)))/AL(I)**2 DUJB=DUJB+2.0*Z(I)**2*U(I)*(SLOPE*Q(I)-R(I)*AL(I))/ 1(SUMZ*AL(I)**2) DVJB=DVJB+2.0*Z(I)**2*V(I)*(SLOPE*Q(I)-R(I)*AL(I ))/ 1(SUMZ*AL(I)**2) 80 DBS = DBS +• Z ( I ) * * 2 * ( U ( I )**2*( 1 . 0/Q (I )-2 . 0*SLOPE*R( I ) / 1AL(I)+V(l)*(2.0*SLOPE*U(I)-V(l))/P(l)) DO 81 I = 1 , N D X ( I ) = Z I P ( I ) - Z(I)*ZIPS/SUMZ DX2(I) = D X ( I ) * * 2 / P ( I ) DXS = DXS + D X 2 ( I ) D Y ( I ) = Z A P ( I ) - Z(I)*ZAPS/SUMZ DY2(I) = DY(I)**2/Q(I) BETA=BETA+Z(I)**2*(DUJB*(SLOPE**2*V(I)/P(I)+2.0*SLOPE* 1U(I)/Q(I)-V 1(I)/Q(I))+DVJB*(SLOPE**2*U(I)/P(l)-2.0*SLOPE*V(I)/P(I) 1- U ( I ) / Q ( I ) ) 2- 2 . 0 * R ( l ) * ( S L O P E * * 2 * U ( I ) * D U J B - V ( I ) * D V J B ) / A L ( I ) ) 81 DYS = DYS+DY2(I) DCS = ALPHA + BETA DDS = DBS+DCS DO 82 I = 1,N 82 SZUM = SZUM + Z ( I ) * * 2 * ( R ( I ) * A L ( I ) ~ S L O P E * Q ( I ) ) * ( V ( I ) 1SLOPE*U(I))/(AL(I))**2 DO 83 I = 1,N DAX(I) = -SL0PE*Z(I)/SUMZ + (2.0*SZUM/SUMZ-XBAR)*(1DX(I)/DDS) SDAX(I) = D A X ( I ) * * 2 / P ( I ) D A Y ( I ) = Z(I)/SUMZ + (2.0*SZUM/SUMZ-XBAR)*(-DY(I)/DDS) SDAY(I) = D A Y ( I ) * * 2 / Q ( I ) SDAXS = SDAXS + SDAX(I) SDAYS = SDAYS + SDAY(I) SUPER=SUPER+DX(I)*DY(I)*R(I)/AL ( I ) 83 RENO=RENO+DAX(I)*DAY(I)*R(I)/AL(I) ERRAA = SQRT(SDAXS + SDAYS) ERRAB=(SQRT(DXS DYS))/DDS E5=ERRAB*SQRT(SUMS/(N-2)) E6=ERRAA*SQRT(SUMS/(N-2)) DO 84 1=1,N C(I)=R(I)*AL(I) RESX(I)=Z(I)*(CINT+SLOPE*X(I)-Y(I))*(C(I)-SLOPE*Q(I)) 1/(P(I)*Q(I)) 84 R E S Y ( I ) = Z ( I ) * ( C I N T + S L O P E * X ( I ) - Y ( I ) ) * ( P ( I ) - S L O P E * C ( I ) ) / 1(P(I)*Q(I)) TEMP=SUMS/(N-2) WRITE(7,52)TEMP +  130  52 FORMAT(78X,6HMSWD= ,F15.8) WRITE(7,60)SLOPE2,SLOPE,SIGMAB,ERRAB,E5,CINT,SIGMAA, 1 ERRAA,E6 60 FORMAT(1 OX,8HSLOPE2= ,F15.8,5X,7HSLOPE= ,F15.8,10X, 1'EST SIGMA=',F15.8/ 1 6 8 X , ' E X A C T SIGMA=' ,F15.8,' OR' ,F15.8//1OX,'INTERCEPT* ' , 1, F15.8,35X 2, 'EST SIGMA=',F15.8/68X,'EXACT SIGMA=',F15.8,' 0R',F15.8) WRITE(7,56) 56 F0RMAT(/15X,'SECOND RESULT APPLIES I F MEAN SQUARE WEIGHTED 1 DEVIATES > 1') WRITE(7,70)XBAR,YBAR,ITER 70 FORMAT(//1OX,6HXBAR- ,F15.8,5X,6HYBAR- ,F15.8,1 OX,'ITER-',I 5) A2=100000*ALOG(1+SLOPE2)/l.42 IF(TEMP.GT.1.0) ERRAB-E5 A3-100000*ALOG(1+ERRAB)/1.42 WRITE(7,71)A2,A3 71 FORMAT(//'Rb-Sr date=',F10.5,'+/-',F10.5,'Ma') IF(TEMP.GT.1.0) ERRAA=E6 WRITE(7,72)CINT,ERRAA 72 FORMAT('INITIAL 8 7 S r / 8 6 S r = ' , F 1 0 . 5 , ' + / - ' , F I 0 . 5 ) WRITE(7,65) WRITE(7,66)(CH1(I),CH2(l),CH3(I),X(I),EX(I),P(I),RESX(I),Y(I), 1EY(I),Q(I),RESY(I),1=1,N) 65 FORMAT(///17X,'Rb87/Sr86 +/WEIGHTS RESIDUALS', 1 ' Sr87/Sr86 +/WEIGHTS RESIDUALS') 66. FORMAT(A4,1X,A4,1X,A4,2F10.5,E15.5,3F10.5,E15.5,F10.5) GO TO 200 101 WRITE(7,95) 95 FORMAT(25X,22HDATA DID NOT CONVERGE.//) 200 GO TO 100 300 STOP END  131  APPENDIX 6-b PROGRAM  "PLRBSR"  C PROGRAM PLRBSR. WRITTEN BT MIN SUN, 1984. C THIS PROGRAM PLOTS RB-SR ISOCHRON BY INPUTTING C 2=(OUTPUT 9 OF PROG. "RBSR")  10 20 30  100 13 11 12  120  DIMENSION X ( 3 ) , Y ( 3 ) K=0 WRITE(6,10) FORMAT('INPUT #(12) OF POINTS,MAX OF RB87/SR86, 1 MAX OF SR87/86') READ(5,20)NPOINT,RSMAX,SSMAX FORMAT(12,1X,2F1 0.5) DO 100 1=1,NPOINT READ(2,30)A2,B,A1,C FORMAT(64X,2F10.5,10X,2F10.5) X(1)=A1-C ' X(2)=A1 X(3)=A1+C Y(1)=A2 Y(2)=A2 Y(3)=A2 CALL POINTS(X,Y,K,RSMAX,SSMAX) K= 1 X(1)=A1 X(2)=A1 X(3)=A1 Y(1)=A2-B Y(2)=A2 Y(3)=A2+B CALL POINTS(X,Y,K,RSMAX,SSMAX) CONTINUE WRITE(6,11) FORMAT ( ' INPUT INTERCEPT ( F 1 5 . 8 ) S, SLOPE ( F 1 5 . 8 ) , IF N 1'ISOCHRON IS PLOTED, PUT 0 . 0 , 0 . 0 ' ) READ(5,12)CINT,SLOPE F0RMAT(2F15.8) IF(CINT.EQ.0.0)GOTO 120 X(1)-0.0 Y(1)=CINT X(2)=0.5*RSMAX Y(2)=0.5*RSMAX*SLOPE+CINT X(3)=RSMAX Y(3)=RSMAX*SLOPE+CINT CALL POINTS( X , Y , K ,RSMAX,SSMAX) GOTO 13 CALL PLOTND STOP END  132  Q *****************************pr QT POINTS************ SUBROUTINE POINTS(X,Y,K,RSMAX,SSMAX) DIMENSION X ( 3 ) , Y ( 3 ) IF(K.NE.0)GOTO 100 CALL ALSCAL(0.0,RSMAX,0.700,SSMAX) CALL A L S I Z E ( 1 0 . 0 , 1 0 . 0 ) CALL ALAXIS('RB87/SR86',9,'SR87/SR86',9) 100 CALL ALGRAF(X,Y,-3,0) RETURN END J  APPENDIX 7  Rb  Sample BM55  BAST  ppm  4 3 ..5  +/•-  DUPLICATED RB-SR DATA  S r ppm  2 .8  1276  33  average BMS5 W R average BMS3  0.. 3 3 2 0 . 0 1 3 0.. 3 2 4 0 . 0 0 3 0 .. 3 2 6 0 . 0 1 0  DIOP  0 . 142 0.001 0.. 1 3 8 0 . 0 0 1  Sr87/86  +/-  Rb87/Sr86  +/-  0. 70258 0. 70310 0. 70272  0 00005 0 .0OO18 0 .00006  0 .. 1 0 3  0 .. 0 0 7  0 .0791 0 .0031 0 .. 0 8 2 7 0 .0010 0 . 0 8 1 8 • 0 .. 0 0 1 5  12 . 1 11 3 11 ,. 7  0 .05 0 .08 0 ,. 3 3  0 70270 0 .. 7 0 2 6 3 0. 70267  0 .00011 0 00009 0 0OO10  33 3 33 , 1  0 ., 7 0 3 7 4 0. 7 0 2 6 7  0 .00066 0 .00022  34. 9  0 . 1 1 0 . 10 0 , . 15  3 3 .,5  .0001  0 .0124 0.0114  0  0 .00022  0 ., 0 1 1 9  0 .0001  0. 70931  0 .00093 0 .00091  0. 883 0 .769  0 .028 0 .025  0. 7 0 3 0 7 0. 7 0 3 7 0  0 .00038 0 .00027  0 .07  0. 70333 0. 70983  0 .0001  average  0.. 1 4 0 0 . 0 0 1  BMS5  0..070 0 . 0 0 0 6 0.. 0 6 9 0 . 0 0 0 7 0.. 0 7 1 0 . 0 0 0 7  0. 229 0. 260 0 ., 2 9 1  0 .007 0 .008 0 O08  0 ., 7 0 7 5 4  0 .00057  average  0..070 0 . 0 0 0 4  0. 260  0, 005  0. 70835  0 .00050  0. 826  0 .020  BM55  0 .. 2 5 1 0 .254 0 254  0 .002 0 .002 0 .002  0. 735 0. 762  0 ,. 0 0 7 0, 006  0. 70738 0. 70899  0 .00057 0 ,. 0 0 0 2 8  0 ,. 9 8 6 . 0. 964  0 .012 0 .011  average  0. 252  0 ,. 0 0 1  0. 749  0 .. 0 0 5  0. 70869 0. 70857  0 .00019 0 .00029  0 ., 9 7 5  0 .0082  BM11  1.. 14 1 .. 12  0 .02 0 .02  25. 2 25. 7  0 ., 7 0 2 2 1 0. 70297  1 . 13  0 .01  25. 6  0. 70282  0 .00034 0 .00008 0 ,. 0 0 0 1 4  0. 130 0 . 126 0 .. 1 2 8  0 .004  average  0 .6 0 .. 1 0. 2  JL18  average  0. 252 0. 252 0. 252  0 ,. 0 0 2 0 ,. 0 0 2 0 001  38. 7 37 . 0 38. 5  0 .. 1 0. 7 0, 3  0. 70195 0. 70381 0. 70242  0 .00013 0 ,. 0 0 0 4 0 0 0OO2O  0. 0188 0. 0197 0. 0191  0 ., 0 0 0 2 0. 0004 o. 0 O O 2  JL14  o.  8. 37 8 . 47 a. 4 4  0. 08 0 .. 0 3 0 04  0. 70358 0. 70290 0. 70298  0 .. 0 0 0 8 8 0 ,. 0 0 0 1 1 0 00032  0. 0624 0. 0602 0. 0613  0. 0008 0. 0005 0. 0O05  0. 617 0. 630 0. 624  0. 008 0. 007 0 .. 0 0 5  0. 70539 0. 70658 0. 70563  0. 00049 0. 00205 0, 00045  0. 439 0. 526 0. 483  0. 007 0. 007 0. 005  0. 7 0. 5 0. 4  0. 70300 0. 70258 0. 70286  0. 00012 0. 0002 1 0, 00022  0. 00475  0.  0 . 01  0. 70392 o. 7 0 5 2 4 0. 70505  0. 00231  0. 273  0. 003  o.0 0 0 3 8  0. 70791 0. 70876 0. 70859  0. 00095 0. 00020 0. 00037  0. 749  0. 017  01IV  OPX  WR  WR  WR  average JL14  OLIV  average JL1  181 0 . 176 0 . 179  0. 001 0 .001 0 .001  0. 0 9 4 0 001 0 . 1 15 0 . 0 0 1 0 104 0 001  DIOP  0. 1 2 5  0 .. 0 0 2  0. 260  0 .. 0 0 2  average JL15  OPX  77. 1 76 . O 76 . 5 2 . 76  average JL15  OLIV  average  0 ., 0 8 4  0  001  0. 325  0. 007  *  *  *  *  0 .002 0 ,. 0 0 2  ooooa  0. 00086  134  LL14  WR  average  0. 774 0. 765 0. 767 0..769  LL14  0 . 233 0 .002  OIOP  0 .008 0 .007 0 .008 0 .007  9 8 8 8  .05 .70 .55 .77  16 .9  0 .07 0 .03 0 .04 0 .04  0 .70388 0..70347 0 . 70362 0 .70366  0 0 0 0  0 .06  0 .70422 0. 70402 0,.70409  0 .00029 0 .00015 0 .00017  0 .0398  0, 0O04  0..70113 0.. 70255 0. 70220  0 .00049 0 .00017 0 .00025  0,.0144  0, 0001  average KR33 OIOP KR3S OIOP  0 . 278 0 .002  55 .6  0 .2  average . KR3S  OLIV  average KR 1 WR  DIOP  average JM14 OPX  OPX  average  0.,71969  0 .00036  0,.795  0..0178  0 . 385 O .005  4 26 4 . 39  0 .03 0,.03  .00030 .00041 .00015 .00020  0 .004  0..03  0 0 0 0  0,.261  4 . 33  0.. 70358 0 . 70407 0 . 70416 0.. 70399  0,,416 0.,009  0 . 71253 0 . 71228 0. 71232  0 00175 0 00026 0 .00059  0..848  0..0196  0 . 078 0 .001 0 . 074 0 002 0 . 0 7 6 0 .001  0 . 593 0..033 0 ..571 0. 0 4 0 0.. 582 0 028  0 . 70631 0 . 70577 0.. 70628  0 00117 0. 0 0 3 4 7 0 .00150  0..381  0..376 0 . 379  0..022 0, 027 0 .014  0 . 0 7 3 0 . 001  0 . 825 0 .024  0 . 70609 0. 70513 0. 70529  0. 00241 0,.00050 0,.00080  0..257  0,.008  0 . 032 0 ..0004  0 .. 171 0..008 0. 099 0..020 0.. 1 190 0 0 5 0,. 130 0 .008  0. 70845  0 .00199  0 ..70903 0..70874  0 .00133 0 .00150  0..784  0, 032  0. 7 1330  0, 0008 1  1 .73  0.. 16  0 . 00352 0 00142 0 00200  o. 683 o. 670  0, 13 0. 087  0. 676  0. 082  0 00247 0 00039 0 00050  0. 348  0. 012  0 . 122 0 . OOI  0 . 032 0. 0003 0 . 032 0, 0 0 0 3  0 . 091 0 . 0 0 1 3  0. 154 0 . 02 0 153 0 ..01 0 . 153 0. 01  JM1S OPX  0 . 031 0. 001 0 . 028 0 . 001  0 . 130 0 . 025 0 . 121 0. 015  average  0 . 0 2 9 0. 001  0. 126 0. 015  0. 70792 0. 70564 0. 70640  0 . 056 0 . 001  0. 449 0. 019 0. 463 0. 010 0 . 456 0. 015  0. 7 0 6 4 2 0. 7055 1 0. 70563  JM15  OLIV  average  JM3  DIOP  average *  --  0..003 0,,002 0 003 0,.002  0..369 0..008  average 0M2  .247 .254 .259 .254  0 . 0 9 9 0 001 0 . 100 0 OOI  average JM14  0 0 0 0  0. 101 0 .001  average KR2 OPX  .00013 .00010 .00010 .00010  unsplked  run  *  •  *  *  

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