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UBC Theses and Dissertations

Model for the evolution of the chemical systems of the earth’s crust and mantle defined by radiogenic… Athaide, Dileep Joseph Anthony 1976

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A MODEL FOR THE EVOLUTION OF THE CHEMICAL SYSTEMS OF THE EARTH'S CRUST AND MANTLE DEFINED BY RADIOGENIC STRONTIUM DISTRIBUTION, AND THE RUBIDIUM-STRONTIUM GEOCHEMISTRY OF THE SHULAPS RANGE AND OTHER ULTRAMAFIC BODIES IN AND NEAR SOUTHWESTERN BRITISH COLUMBIA by DILEEP J A ATHAIDE B.Sc.(Hon), M c G i l l U n i v e r s i t y , 1971 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of G e o l o g i c a l Sciences We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA December 1975 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r ee t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r ag ree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y pu rpo se s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Dileep J A Athaide Department o f Geological Sciences The U n i v e r s i t y o f B r i t i s h Co l umb i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date December 5 , 1975 F r o n t i s p i e c e . Jim Creek area, southwest Shulaps Range. In the background, to the n o r t h e a s t , i s Shulaps Range proper. C e n t r a l p r o t r u d i n g mass ( e l e v a t i o n 7500 ft/2886 m) i s gabbro, s i t e of samples SH-12,13. Range trends southeast to Shulaps Peak, not f a r o f f the r i g h t edge of the photograph. Foreground shows l o c a t i o n of s e r p e n t i n i t e and s e r p e n t i n i z e d h a r z b u r g i t e samples SH-1,2,3. Claim-post (with "no t r e s p a s s i n g " sign) staked i n 1971, ap p a r e n t l y f o r a n i c k e l p r o s p e c t . Photograph taken i n l a t e May; snow on range o f t e n p e r s i s t s up to J u l y . ABSTRACT I n i t i a l strontium isotopic r a t i o s have contributed much to our understanding of the chemical, and related tectonic, evolution of the earth. Improved a n a l y t i c a l techniques have recently provided a flood of precise strontium analyses which are very useful i n the determination of the genesis of various rocks. The theories of sea-floor spreading and plate tectonics have prompted a new interpretation of the earth's chemical evolution, based on the tracer properties of radiogenic stront-ium. Strontium i s o t o p i c r a t i o s are considered for rocks of various composition, environment and age: stony meteorites, oceanic and continental basalts, i s l a n d arc and andesitic v o l -canics, anorthosites, carbonatites and alk a l i n e i n t r u s i v e s , and g r a n i t i c and sedimentary rocks. Special emphasis i s placed on ultramafic rocks, believed i n some circumstances to provide d i r e c t samples of the mantle regions of the earth. Here the rubidium-strontium geochemistry i s studied for the d i f f e r e n t petrogenetic categories: oceanic ultramafics, alpine-type intrusions, concentrically-zoned bodies, nodules i n a l k a l i basalts and i n kimberlites, and the layered ultramafic zones i n major intrusions. Patterns revealed by the strontium d i s t r i b u t i o n lead to a unique d e f i n i t i o n of the major chemical systems of the earth. These systems, and the ranges of t h e i r c h a r a c t e r i s t i c present-day Sr87/Sr86 r a t i o s are: the lower (deep) mantle (0.701 to 0.703), the oceanic upper mantle (0.707 to 0.715), the con-t i n e n t a l upper mantle (0.703 to 0.706), and the continental crust (0.701 to 0.703+). The source of a l l surface magmatic rocks can be attributed to one or a combination of these reser-v o i r s . Several mechanisms are proposed for the transfer of material from the i n t e r n a l to surface systems. A model, together with a computer-plot, i s presented for radiogenic strontium evolution i n the earth's major chemical systems. I t includes the following present-day conditions: (1) an alpine-type ultramafic zone constituting primarily the ocean-i c , rather than the continental, upper mantle; (2) a common deep-mantle source for both oceanic t h o l e i i t i c and alkaline basalts; and (3) the p o s s i b i l i t y of at l e a s t two, and perhaps three, d i s t i n c t reservoirs contributing to igneous a c t i v i t y from d i r e c t l y below the continental crust. A rubidium-strontium geochemical study was undertaken for the Shulaps Range and other ultramafic bodies i n and near southwestern B r i t i s h Columbia. The Shulaps rocks, predominantly serpentinized harzburgites, y i e l d Rb and Sr concentrations aver-aging 0.2 ppm and 4.2 ppm respectively, as determined by x-ray fluorescence analysis. The corresponding Rb/Sr r a t i o of 0.05 i s f a i r l y t y p i c a l of alpine-type intrusions. Mass spectrometer analysis gives an average Sr87/Sr86 r a t i o of 0.7064 for these whole-rocks. This i s just s l i g h t l y below the range which i s normally observed for alpine-type ultramafic bodies and which i s believed to represent the oceanic upper mantle system. i v TABLE OF CONTENTS page F r o n t i s p i e c e i A b s t r a c t i i Table of Contents i v L i s t of Tables v i i i L i s t of F i g u r e s • x L i s t of P l a t e s x i i Acknowledgements x v I. INTRODUCTION 1 I I . GEOCHEMISTRY AND PETROGENETIC SIGNIFICANCE OF 3 RUBIDIUM AND STRONTIUM A. Geochemistry of Rubidium 3 B. Geochemistry of Strontium 5 C. Rubidium and Strontium Abundances 7 D. Rubidium/Strontium R a t i o 8 E. P e t r o g e n e t i c S i g n i f i c a n c e of I n i t i a l Strontium 9 R a t i o s I I I . STRONTIUM ISOTOPE ANALYSES OF ULTRAMAFIC ROCKS IN 12 AND NEAR SOUTHWESTERN BRITISH COLUMBIA A. I n t r o d u c t i o n 12 B. D e s c r i p t i o n of Study Areas 15 1. The Shulaps Range U l t r a m a f i c Body 15 a. L o c a t i o n and Access 15 b. General Geology 16 c. The U l t r a m a f i c Mass 16 d. Areas Examined and Samples C o l l e c t e d 18 2. Other U l t r a m a f i c Bodies Examined 19 a. The C o q u i h a l l a S e r p e n t i n i t e B e l t 21 V b. The Trapping Creek Gabbro-Peridotite 21 Complex c. The Twin Sisters Dunite 24 C. A n a l y t i c a l Techniques 27 1. Sample C o l l e c t i o n and Preparation 27 2. Petrography 27 a. X-Ray D i f f r a c t i o n I d e n t i f i c a t i o n of 29 Mineral Phases b. Hand-Specimen and Thin-Section Analyses 31 3. X-Ray Fluorescence Determination of Rb and 31 Sr Concentrations 4. Chemical Dissolution of Samples 39 5. Strontium Isolation by Ion Exchange 41 6. Mass Spectrometric Analyses of Sr87/Sr86 42 Ratios and Total Sr Concentrations by Isotope D i l u t i o n D. Summary and Discussion of Results 43 E. Conclusions Regarding the Origin of the 47 Ultramafic Bodies IV. STRONTIUM ISOTOPE VALUES FOR ROCKS OF VARIOUS 57 COMPOSITION, ENVIRONMENT AND AGE — EXCLUSIVE OF ULTRAMAFIC ROCKS A. Stony Meteorites: The Primeval Ratio 57 B. Oceanic Basalts 58 C. Continental Basalts 60 D. Island Arc and Andesitic Volcanics 60 E. Anorthosites, Carbonatites and Alkaline Intrusives 61 F. Granitic and Sedimentary Rocks 62 G. Summary of Recorded Isotopic Variations for 63 Non-Ultramafic Rocks V. COMPILATION OF ALL REPORTED RUBIDIUM AND STRONTIUM 64 CONCENTRATIONS AND STRONTIUM ISOTOPE DATA FOR ALL TYPES OF OCCURRENCES OF ULTRAMAFIC AND RELATED ROCKS v i A. Oceanic Ultramafic Rocks (Dredged, Cored, 66 and Oceanic Islands) B. Alpine-Type Ultramafic Intrusions 70 C. Concentrically-Zoned Ultramafic Bodies 76 D. Ultramafic Nodules i n Oceanic and Continental 80 A l k a l i Basalts E. Kimberlites (Ultramafic Inclusions) 90 F. Layered Gabbro-Norite-Peridotite i n Major 94 Intrusions G. Summary of Recorded Isotopic Variations for 100 Ultramafic and Related Rocks VI. INTERPRETATION OF THE REPORTED ISOTOPE VARIATIONS 101 AND THEIR PETROGENETIC IMPLICATIONS A. Basalts 101 B. Island Arc and Andesitic Volcanics 103 C. Anorthosites, Carbonatites and Alkaline Intrusives 104 D. Ultramafic and Related Rocks 105 1. Oceanic Ultramafic Rocks 105 2. Alpine-Type Ultramafic Intrusions 107 3. Concentrically-Zoned Ultramafic Bodies 107 4. Ultramafic Nodules i n A l k a l i Basalts 108 5. Ultramafic Inclusions i n Kimberlites 109 6. Layered Ultramafic Zones i n Major Intrusions 109 7. Summary of the Petrogenetic Implications of 110 Isotopic Variations i n Ultramafic Rocks VII. A MODEL FOR THE DEVELOPMENT OF THE CHEMICAL SYSTEMS 114 OF THE EARTH'S CRUST AND MANTLE DEFINED BY RADIOGENIC STRONTIUM DISTRIBUTION A. D e f i n i t i o n of the Earth's Major Chemical Reservoirs 114 B. Discussion: Further Characteristics of the 118 Chemical Systems, Their Products, and Their Strontium Isotopic Development with Time v i i C. Computer Plot Model for Radiogenic Strontium 123 Evolution i n the Earth's Major Chemical Systems VIII. CONCLUDING STATEMENT AND SUGGESTIONS FOR FURTHER WORK 132 LITERATURE CITED 134 APPENDIX I. PETROGRAPHIC DESCRIPTIONS OF ANALYZED ROCKS 146 APPENDIX I I . COMPUTER PROGRAM AND OUTPUT LISTING 152 LIST OF TABLES v i i i page I. Physical and chemical properties of the a l k a l i 4 metals, as compiled by FAURE and POWELL (1972). II. Physical and chemical properties of the alk a l i n e 4 earths, as compiled by FAURE and POWELL (1972). I I I . Average concentrations of rubidium and strontium 8 in t e r r e s t r i a l rocks and chondritic meteorites; from FAURE and POWELL (1972). IV. Summary of the samples c o l l e c t e d and t h e i r respective 20 locations within the Shulaps Range ultramafic body. V. Operating parameters used in the whole-rock powder 30 x-ray d i f f r a c t i o n study. VI. Operating parameters of the x-ray fluorescence unit. 30 VII. Rubidium concentration (in ppm) of the U.S.G.S. rock 33 standards as reported i n recent studies, and as used here. VIII. Strontium concentration (in ppm) of the U.S.G.S. 34 standards as reported i n recent studies, and values used here. References as i n table VII. IX. Mass absorption c o e f f i c i e n t values (^u.) used for the 34 U.S.G.S. standard rocks (after BLENKINSOP, 1972). X. Replicate x-ray fluorescence determination of Rb 36 concentrations (ppm). A. Using a l l seven U.S.G.S. standards (values as i n table VIII). B. Using only standards GSP-1, BCR-1, AGV-1, G-2, and W-l. C. Using only standards W-l, DTS-1, and PCC-1. XI. Replicate x-ray fluorescence determination of Sr 37 concentrations (ppm). A, B, C: as i n table X. XII. Best x-ray fluorescence-determined values for Rb and 38 Sr concentrations and corresponding Rb/Sr r a t i o s . XIII. Parameters and equations used i n the c a l c u l a t i o n of 44 Sr87/Sr86 and t o t a l Sr concentrations from mass i x spectrometer data. XIV. Mass spectrometric r e s u l t s . 46 XV. Summary of recorded strontium i s o t o p i c variations 63 for non-ultramafic rocks. XVI. Compilation of a l l reported rubidium and strontium 65 concentrations and strontium isotope data and related information for a l l types of occurrences of u l t r a -mafic and related rocks. Pages 66 to 99. XVII. Summary of recorded i n i t i a l Sr87/Sr86 r a t i o s f or 100 ultramafic and associated rocks of various types of occurrence. The mean (x) and variance (s) values are calculated from the detailed l i s t i n g s appearing i n table XVI. XVIII. Dimensions of the earth's major chemical reservoirs 115 as defined i n the radiogenic strontium evolution model. XIX. Proposed d e f i n i t i o n of the earth's major chemical 116 systems, t h e i r Sr87/Sr86 r a t i o s and reasons for these c h a r a c t e r i s t i c values. XX. Magmatic rock types supplied by the earth's major 122 chemical reservoirs as defined i n table XIX, and mechanisms for the transfer of magma from each reservoir to the earth's surface. XXI. Rubidium-strontium data provided to the computer, 125 and Sr87/Sr86 values returned by the computer (in brackets) i n the p l o t of the model for the growth of radiogenic strontium i n the chemical systems of the earth's crust and mantle (see figure 10). The actual computer program and output data for every 25 my i n t e r v a l appear i n appendix II. X LIST OF FIGURES page 1. D i s t r i b u t i o n of ultramafic bodies and major s t r u c t u r a l 11 trends i n B r i t i s h Columbia, southeast Alaska, and northernmost Washington State. After KING (1969), STOCKWELL (1967), TAYLOR and NOBLE (1960), and WHITE (1966). 2. General geology of the Shulaps Range (after LEECH, 14 1953). Also shown are the locations of samples co l l e c t e d for t h i s study. 3. The Trapping Creek gabbro-peridotite complex. Geology 23 according to PEARSE (1971). Sample locations approximate. 4. The Twin Si s t e r s Dunite, Washington, showing sample 25 locations and major geological features of the area. Adapted aft e r RAGAN (1963), MOEN (1969) and MISCH (1952, 1960). 5. Summary of a n a l y t i c a l procedures. 28 6. Variations of Sr87/Sr86 and K 20/(K 20 + Na 20) i n oceanic 59 b a s a l t i c rocks. From PETERMAN and HEDGE, 1971. 7. Hypothetical Sr87/Sr86 development i n alpine-type u l t r a - 113 mafic material according to STUEBER and MURTHY (1966). 8. STUEBER and MURTHY's (1966) proposed relationships of 113 ultramafic rocks to present mantle-crust structure. 9. BONATTI et a l ' s (1970) schematic and q u a l i t a t i v e model 113 of the crust and upper mantle i n the equatorial A t l a n t i c . A zone of upper mantle enriched i n r e s i d u a l , alpine-type p e r i d o t i t e i s intruded by r i s i n g b a s a l t i c material below the axis of the ridge, r e s u l t i n g i n the formation of a peridotite-gabbro-basalt complex. 10. Computer p l o t of model for radiogenic strontium evol- 124 ution i n the chemical systems of the earth's crust and mantle. Parameters shown i n table XXI and appendix I I , and discussed i n text. x i 11a to l i e . Schematic representation of the radiogenic 127, strontium model depicting the chemical and tectonic 129 evolution of the earth's major magmatic reservoirs as defined i n tables XVIII and XIX and figure 10. 12a to 12c. Schematic representation of t y p i c a l present-day 131 intra-plate and plate-boundary magmatic a c t i v i t y , corresponding to the radiogenic strontium evolution model proposed here. LIST OF PLATES page Frontispiece. Jim Creek area, southwest Shulaps Range. i In the background, to the northeast, i s Shulaps Range proper. Central protruding mass (elevation 7500 f t / 2886 m) i s gabbro, s i t e of samples SH-12, 13. Range trends southeast to Shulaps Peek, not far o f f the r i g h t edge of the photograph. Foreground shows location of serpentinite and serpentinized harzburgite samples SH-1, 2, 3. Claim-post (with "no trespassing" sign) staked in 19 71, apparently for a n i c k e l prospect. Photograph taken i n late May; snow on range often p e r s i s t s up to July. I. a. Blue Creek area, i n the northcentral part of the 49 Shulaps ultramafic body. I l l u s t r a t e d i s the t y p i c a l topography of the broad U-shaped valleys separating subdued mountains, often with steep talus slopes. Elevation i s about 6000 f t (1830 m) . I. b. Blue Creek area, Shulaps Range, showing location of 49 serpentinite sample SH-4, at the top of the talus slope seen i n plate l a . I. c. Lake La Mare area, southeast corner of Shulaps Range. 49 Location of serpentinized p e r i d o t i t e sample, SH-9. Foreground shows nature of t y p i c a l outcrop. Elevation i s 4500 f t (1370 m). I. d. Serpentinite shear zone, c h a r a c t e r i s t i c of f a u l t - 49 bounded periphery of the Shulaps ultramafic mass. Col l e c t i o n s i t e of sample SH-11, near Lake La Mare. II. a. Hand-specimen of serpentinite, SH-1. Shows conspicuous 51 bastites ( r e l i c t enstatites) within a dark serpentine matrix. Scale marker = 1.0 cm (for every photograph in plate I I ) . II. b. Hand-specimen of serpentinized harzburgite, SH-3. A 51 very conspicuous checkered appearance, with large cream-x i i i green pyroxene grains set within a dark grey serpentine matrix. Weathered rim constitutes sample SH-3A. II. c. Hand-specimen of serpentinite, SH-4. I l l u s t r a t e s 51 the common enamel-like faces. II. d. Hand-specimen of serpentinite, SH-6. A very f i n e - 51 grained rock, with subconchoidal fracture. II . e. Hand-specimen of serpentinite, SH-7. Very tiny t a l c 51 needles c l e a r l y v i s i b l e , within a darker serpentine matrix (see also Plate IVa). II. f. Hand-specimen of Twin Si s t e r s dunite (saxonite), 51 TSD-1. Extremely fresh, equigranular yellow-green o l i v i n e . II. g. Weathered surface of Twin Sisters dunite (saxonite), 51 TSD-1. Very conspicuous (darker) enstatite grains protrude the less r e s i s t a n t o l i v i n e . I I . h. Hand-specimen of Twin Si s t e r s serpentinized l h e r z o l i t e , 51 TSS-1. Dark green pyroxene c r y s t a l s dominate within a subsidiary grey-black serpentinized o l i v i n e matrix. III . a. Photomicrograph of serpentinite, SH-1. Cross-polarized 53 l i g h t . Shows a bastite (enstatite altered to antigorite) grain within a mesh of randomly-oriented l i z a r d i t e laths. Tiny v e i n l e t s at top l e f t of photograph are c h r y s o t i l e . Scale, 1:40. III. b. Photomicrograph of serpentinite, SH-4. Cross-polarized 53 l i g h t . Shows p a r t i a l l y - s e r p e n t i n i z e d ( l i z a r d i t e ) o l i v i n e , e x h i b i t i n g c h a r a c t e r i s t i c "stained glass" texture. Crystal at extreme r i g h t i s a s l i g h t l y altered orthopyroxene. III. c. Photomicrograph of harzburgite, SH-5. Cross-polarized 53 l i g h t . Olivine only very s l i g h t l y altered (compare with plate I l l b ) . C r y s t a l at top l e f t i s unaltered e n s t a t i t e . IV. a. Photomicrograph of serpentinite, SH-7. Cross-polarized 55 l i g h t . Talc needles, with accompanying c h l o r i t e and minor carbonate set within a mesh-like serpentine matrix. xiv Scale, 1:40. IV. b. Photomicrograph of serpentinized harzburgite, SH-8. 55 Cross-polarized l i g h t . Enstatite grain with rim of tiny clinopyroxene (diopside) c r y s t a l s with a matrix of serpentinized o l i v i n e . Compare with SH-1 (plate I l f ) where the pyroxene i s t o t a l l y serpentinized to ba s t i t e . IV. c. Photomicrograph of Twin Sisters dunite (saxonite), 55 TSD-1. Cross-polarized l i g h t . Large e n s t a t i t e grain shows s l i g h t l y deformed (bent) lamellae, and has tiny o l i v i n e inclusions. The anhedral o l i v i n e grains are extremely fresh, with no sign of serpentinization whatsoever. X V ACKNOWLEDGEMENTS The thesis was written under the supervision of Professor W.F. Slawson of the Department of Geophysics and Astronomy. His understanding and advice throughout the duration of t h i s study i s greatly appreciated. The thesis has i n part been c r i t i c a l l y read by Drs. R.L. Armstrong and R.L. Chase of the Department of Geological Sciences; t h e i r suggestions for improvement of the paper are gr a t e f u l l y acknowledged. Several useful comments on an e a r l i e r version of the isotopic model were provided by Dr. R. Doig of McGill University. However the author alone assumes responsi-b i l i t y for the ideas presented here. Former fellow-graduate students, Drs. J. Blenkinsop and B.D. Ryan supplied invaluable assistance with the mass spectrometer and x-ray fluorescence techniques, respectively. Another colleague, Dr. G. Noury helped write the computer program for the strontium evolution p l o t . A s p e c i a l note of thanks i s due Dr. R.D. Hyndman of the Earth Physics Branch (Federal Department of Energy, Mines and Resources, V i c t o r i a ) , who acted as the writer's adviser i n his f i r s t year of graduate studies, and whose perpetual enthusiasm and encouragement during his term as v i s i t i n g professor at UBC w i l l long be remembered. Samples of the Trapping Creek ultramafic complex were supplied by Dr. A. LeCheminant. Dr. J.A. Chamberlain provided xvi the sample of the Coquihalla serpentinite. Dr. A. Onyeagocha of the University of Washington accompanied the author on his v i s i t to the Twin Sisters Dunite. Financial assistance for f i e l d and laboratory work was provided by National Research Council Grant No. A013 to Dr. Slawson. The mass spectrometer laboratory i s supported by National Research Council Grant No. A0720 to Dr. R.D. Russ-e l l of the Department of Geophysics and Astronomy. Expenses entailed i n the actual preparation of the thesis, however, have been borne e n t i r e l y by the author. 1 I. INTRODUCTION While almost a l l geologists are f a m i l i a r with the Rb-Sr dating technique, only a minority are f a m i l i a r with the petrogenetic s i g n i f i c a n c e of i n i t i a l strontium i s o t o p i c r a t i o s . Radiogenic strontium i s useful as a tracer i n the determination of the genesis of various rocks, and on a broad scale, i n i t i a l strontium isotopic r a t i o s have contributed much to our under-standing of the chemical, and related tectonic, evolution of the earth. Improved a n a l y t i c a l techniques have provided a flood of precise strontium analyses, f a c i l i t a t i n g the recognition of d i s t i n c t v a r i a t i o n s i n the r a t i o s for rocks from presumedly d i f f e r e n t sources. New ideas concerning the tectonic evolution of the earth — such as sea-floor spreading and plate tectonic theories — have prompted me to make a new inter p r e t a t i o n of the earth's evolutionary history, based on radiogenic strontium d i s t r i b u t i o n . I believe that ultramafic rocks are of utmost importance, as i n some circumstances they provide us with d i r e c t samples from the mantle. This report w i l l discuss observed strontium isotope r a t i o v a r i a t i o n s , define the chemical systems of the earth, suggest mechanisms for the transfer of material from i n t e r n a l to surface systems, and present a model for the evolution of radiogenic strontium. This model i s believed to be consistent with meteorite geochemical data, t e r r e s t r i a l potassium/rubidium r a t i o s , rare-earth element d i s t r i b u t i o n s , lead isotopes, heat-2 flow patterns, seismic studies of crust and mantle structure, and current concepts of igneous ( p a r t i c u l a r l y oceanic) p e t r o l -ogy. Whole-rock i n i t i a l strontium isotopic r a t i o s were determined for a few ultramafic bodies i n and near southwest-ern B r i t i s h Columbia. In addition to y i e l d i n g s i g n i f i c a n t r e s u l t s , t h i s experience provided the author with a greater appreciation for, and better understanding of, the reported strontium r a t i o s compiled for t h i s study from a review of the l i t e r a t u r e . 3 I I . GEOCHEMISTRY AND PETROGENETIC SIGNIFICANCE OF RUBIDIUM AND STRONTIUM I t i s f e l t t h a t a b r i e f d i s c u s s i o n of the geochem-i s t r y of rubidium and s t r o n t i u m i s e s s e n t i a l i n f a c i l i t a t i n g a c l e a r understanding of the v a r i a t i o n s of s t r o n t i u m i s o t o p i c r a t i o s . Much of the f o l l o w i n g review i s taken l a r g e l y from a r e c e n t book on s t r o n t i u m i s o t o p e geology by FAURE and POWELL (1972) . A. Geochemistry of Rubidium Rubidium i s an a l k a l i metal which together w i t h l i t h i u m , sodium, potassium, cesium and francium, as w e l l as hydrogen, c o n s t i t u t e Group IA of the P e r i o d i c Table. The p r o p e r t i e s of the a l k a l i metals are summarized i n Table I. The atoms of these elements are r e l a t i v e l y l a r g e , and they r e a d i l y l o s e t h e i r s i n g l e valence e l e c t r o n . T h i s ease of o x i d a t i o n dominates t h e i r geochemical behavior. The oxides of the a l k a l i metals are e s s e n t i a l l y i o n i c compounds, wi t h the degree of i o n i c c h a r a c t e r of the bonds i n c r e a s i n g w i t h the atomic weight. The a l k a l i metals are thus c h e m i c a l l y " o x y p h i l e " , and are markedly co n c e n t r a t e d i n the c o n t i n e n t a l crust(HEIER and ADAMS, 1964). The d i s t r i b u t i o n of rubidium i n nature i s c o n t r o l l e d by the f a c t t h a t the Rb + i o n (r = 1.48 A) i s s m a l l enough to . be admitted i n t o K + s i t e s (r = 1.33 A) i n a l l the important potassium-bearing rock-forming m i n e r a l s . Rubidium a c t s as Table I. P h y s i c a l and chemical p r o p e r t i e s of the a l k a l i metals, as compiled by FAURE and POWELL (1972). P r o p e r t i e s L i Na K Rb Cs Atomic number 3 11 19 37 55 12 Atomic weight (based on C ) 6. 939 22. 9898 39. 102 85. 467 132. 905 I o n i c r a d i u s (A) (Pauling) 0. 60 0. 95 1. 33 1. 48 1. 69 Radius r a t i o ( 0 2 ~ = 1.40 A) o: 43 0. 68 0. 95 1. 06 1. 21 C o o r d i n a t i o n number i n i o n i c c r y s t a l s 6 6, 8 8, 12 8, 12 12 E l e c t r o n e g a t i v i t y (Pauling) 1. 0 0. 9 0. 8 0. 8 0. 7 2— Percent i o n i c c h a r a c t e r of bond wi t h 0 82 83 87 87 89 Table I I . P h y s i c a l and chemical p r o p e r t i e s of the a l k a l i n e e a r t h s , as compiled by FAURE and POWELL (1972). P r o p e r t i e s Be Mg Ca Sr Ba Atomic number 4 12 20 38 56 12 Atomic weight (based on C ) 9. 012 24. 312 40. 08 87. 62 137. 34 I o n i c r a d i u s (A) (Pauling) 0. 31 0. 65 0. 99 1. 13 1. 35 Radius r a t i o ( O 2 - = 1.40 A) 0. 22 0. 46 0. 71 0. 81 0. 96 C o o r d i n a t i o n number i n i o n i c c r y s t a l s 4 6 6, 8 8 8, 12 E l e c t r o n e g a t i v i t y (Pauling) 1. 5 1. 2 1. 0 1. 0 0. 9 Percent i o n i c c h a r a c t e r o f bond wi t h O 2 - 63 71 ;79 82 84 5 a trace element, as i t i s never concentrated s u f f i c i e n t l y to form i t s own minerals. The r a t i o K/Rb i s i t s e l f an important petrogenetic tracer, as i s discussed b r i e f l y i n the l a s t chapter of t h i s paper. The main rubidium-bearing minerals are the micas," ( b i o t i t e , muscovite and l e p i d o l i t e ) and the potass-ium feldspars (orthoclase and microcline). Some pegmatites have l e p i d o l i t e that may contain several percent rubidium (FAURE and POWELL, 197 2). Rubidium has two naturally-occurring isotopes: stable Rb8 5 and radioactive Rb87. In addition, about twenty other short-lived rubidium isotopes are a r t i f i c i a l l y produced. The r e l a t i v e abundances of Rb85 and Rb87 are 72.1654 + 0.0132% (2<r) and 27.8346 + 0.0132% respectively, as determined by CATANZARO et a l (1969), corresponding to a Rb85/Rb87 r a t i o of 2.59265 + 0.00170. Regardless of environment, the isotopic composition of naturally-occurring rubidium i s constant, within the l i m i t s of measurement error. This was established by SHIELDS et a l (1963) who determined the isotopic composition i n twenty-seven s i l i c a t e minerals ranging i n age from 20 to 2600 my. B. Geochemistry of Strontium Strontium i s a member of Group I l a of the Periodic Table, together with the other a l k a l i n e earths: beryllium, magnesium, calcium, barium, and radium. The properties of these elements are l i s t e d i n table II. The atoms of the alkaline earths have two valence electrons i n the i r outer s 6 o r b i t a l , and r e a d i l y form ions with a 2+ charge. Like the a l k a l i metals, the Group IIA elements have low electronegativ-i t i e s , thus forming i o n i c bonds with non-metallic elements, including oxygen. 2+ 2+ In nature, Sr substitutes for Ca i n calcium-bearing minerals, and may also be captured i n place of K + ions by potassium-feldspar. FAURE and POWELL (1972) point out 2+ that while the i o n i c radius of Sr (1.13 A) i s merely 15% 2+ 2-greater than that of Ca (0.99 A), i t s radius r e l a t i v e to 0 2+ 2+ i s 0.81 compared with 0.71 for Ca . So while Ca can occupy 2+ both s i x - and e i g h t - f o l d coordination positions, Sr prefers e i g h t - f o l d coordination. Strontium acts as a dispersed trace element i n igneous rocks, but unlike rubidium, can often be concentrated enough to form i t s own minerals i n hydrothermal deposits and carbonate rocks. VLASOV (1964) l i s t s twenty-five strontium minerals i n addition to the well known c e l e s t i t e (SrSO^) and s t r o n t i a n i t e (SrC0 3) . The main strontium-bearing minerals i n igneous rocks are plagioclase-feldspar and apatite (a calcium phosphate), 2+ 2+ where Sr replaces Ca ions. In pyroxenes, calcium has s i x -f o l d coordination, and consequently the strontium concentration 2+ i s low. In potassium-feldspar, Sr can be captured i n place of K+, probably accompanied by the replacement of S i ^ + by Al"^ + to maintain e l e c t r i c a l n e u t r a l i t y . K + i n micas has twelve-fold 2+ coordination, and so substitution by Sr i s not favoured here. 7 Strontium has four stable isotopes: Sr88, Sr87, Sr86 and Sr84. In addition, there are fourteen short-lived isotopes produced as a r e s u l t of a r t i f i c i a l nuclear reactions. These include the very dangerous Sr90, a product of nuclear f i s s i o n of uranium. The isotopic abundances of strontium are not constant i n nature because of the radiogenic production of Sr87 from the decay of Rb87. The r a t i o s for p u r i f i e d strontium metal are: Sr87/Sr86 = 0.7119 (depending however upon the source material); Sr86/Sr88 = 0.1194; and Sr84/Sr88 = 0.0068. The corresponding r e l a t i v e abundances are: Sr84 = 0.56%, Sr86 = 9.9%, Sr87 = 7.0% and Sr88 = 82.6%. C. Rubidium and Strontium Abundances The average concentrations of rubidium and strontium i n t e r r e s t r i a l rocks and chondritic meteorites are shown in table III. The "average" nature of these values must be stressed as large variations e x i s t among the rock types l i s t e d . D. Rubidium/Strontium Ratio The average Rb/Sr r a t i o s of the various rock types are also shown i n table I I I . During f r a c t i o n a l c r y s t a l l i z a t i o n of magma, rubidium i s concentrated i n the residual f l u i d , eventually entering potassium minerals. Strontium tends to separate from the l i q u i d phase, into the early-formed calcium-plagioclase (anorthite). So for igneous rocks, the greater the degree of d i f f e r e n t i a t i o n , the larger the Rb/Sr r a t i o ; t h i s f a c t can be recognized i n the corresponding r a t i o s l i s t e d 8 Table I I I . Average c o n c e n t r a t i o n s of rubidium and s t r o n t i u m i n t e r r e s t r i a l rocks and c h o n d r i t i c m e t e o r i t e s ; from FAURE and POWELL (1972). Rb Sr Rb/Sr Chondrites 2. 3 10 0.23 C r u s t 90 375 0. 24 U l t r a b a s i c rocks 0.077 - 7.75 2.32 - 72.4 0.007 - 1 B a s a l t 30 465 0.06 Syenite 110 300 0.37 G r a n o d i o r i t e 120 450 0. 27 Gr a n i t e 150 285 0.53 Shale 140 300 0.47 Greywacke 120 450 0. 27 Q u a r t z i t e 30 - -Limestone 5 500 0.01 9 for the igneous rocks i n table I I I . E. Petrogenetic Significance of I n i t i a l Strontium Ratios Since the beginning of the earth's history, the radioactive decay of Rb87 has resulted i n an increase i n the abundance of Sr87, conventionally expressed as the Sr87/Sr86 r a t i o . In any chemical system or reservoir closed to rubidium and strontium, the rate of increase i n the Sr87/Sr86 r a t i o i s sole l y dependent on the i n i t i a l quantity of rubidium and strontium i n that system. In 1963 Faure and Hurley proposed that because of chemical d i f f e r e n t i a t i o n processes r e s u l t i n g i n the p r e f e r e n t i a l concentration of rubidium i n the upper regions of the continental crust, the rate of increase of the Sr87/Sr86 r a t i o has been greater i n the crust than i n the \ upper mantle. They therefore maintained that " i f the r e s u l t i n g difference i n the Sr87/Sr86 r a t i o s i n the two environments i s measurable, the o r i g i n of in t r u s i v e igneous rocks now e x i s t i n g i n the d i f f e r e n t i a t e d s i a l i c crust can be determined from the values of t h e i r Sr87/Sr86 r a t i o s at the time of c r y s t a l l i z a t i o n " (FAURE and HURLEY, 1963, p 32). In the l a s t ten years, a large number of strontium analyses have been made on a variety of rock types, and obser-ved differences i n the i n i t i a l r a t i o s suggest a considerably more complicated development than that f i r s t envisaged by Faure and Hurley. I t appears to the author that the dominant early (post-core-formation) chemical d i f f e r e n t i a t i o n of the earth resulted not primarily i n the formation of the continental crust, but i n a global-wide "proto-crust" or upper mantle several hundred kilometers thick. Parts of t h i s upper mantle then s e l e c t i v e l y d i f f e r e n t i a t e d to form early continental crust, leaving corresponding areas of depleted upper mantle. These trends constitute a major precept of the evolutionary model to be presented here. Figure 1. Distribution of ultramafic bodies and major structural trends in Br i t i s h Columbia, southeast Alaska, and northernmost Washington State. After KING (1969), STOCKWELL (1967), TAYLOR and NOBLE (1960), arid WHITE (1966). 12 II I . STRONTIUM ISOTOPE ANALYSES OF ULTRAMAFIC ROCKS IN AND  NEAR SOUTHWESTERN BRITISH COLUMBIA A. Introduction Selected ultramafic rocks from l o c a l i t i e s i n and near southwestern B r i t i s h Columbia were analyzed for t h e i r rubidium and strontium concentrations and strontium isotopic r a t i o s . The only published r a t i o for ultramafic rocks i n B r i t i s h Col-umbia i s a single value obtained for a dunite sample from the Tulameen complex, a concentrically-zoned ultramafic body (STUEBER and MURTHY, 1966) (see figure 1, and table XVI). For the present study, rather than analyzing random samples from a great variety of ultramafic masses, the author chose a p a r t i c u l a r body and sampled i t i n d e t a i l . This was the Shulaps Range ultramafic body of southwestern B r i t i s h Columbia, one of the largest alpine-type serpentinite masses i n the province. In addition, i s o l a t e d samples from three other ultramafic bodies were analyzed. These are the Coqui-h a l l a alpine-type serpentinite b e l t and the Trapping Creek concentrically-zoned gabbro-peridotite complex of southern B r i t i s h Columbia, and the Twin Sisters Dunite of northernmost Washington State. The extremely low strontium concentrations of the ultramafic rocks proved a major d i f f i c u l t y i n a l l aspects of the a n a l y t i c a l work. The mass spectrometry, i n p a r t i c u l a r , posed a s i g n i f i c a n t l y greater problem than had been anticipated. Kli.ES UJ Marshall U k e LEGEND CRETACEOUS (?) AND TERTIARY BLUE CREEK (north) and REXMONT (south) PORPHYRIES Quartz d i o r i t e and d i o r i t e LOWER CRETACEOUS greywacke, shale, conglomerate, limestone, chert UPPER TRIASSIC OR (?) LATER gabbro and diopside-pyroxenite Shulaps ul t r a b a s i c rocks andesitic lava, breccia, and l a p i l l i - t u f f UPPER TRIASSIC HURLEY GROUP: argillaceous and tuffaceous s i l t s t o n e and sandstone, conglomerate, limestone, chert TRIASSIC AND/OR EARLIER greenstone, a r g i l l i t e , chert and c h l o r i t i c p h y l l i t e s UNKNOWN AGE greywacke, a r g i l l i t e , s i l t s t o n e , conglomerate, limestone, chert undifferentiated sedimentary and volcanic rocks greenstone-gabbro complex: andesite and/or basalt, d i o r i t e s c a r c i t y of outcrop Figure 2. General geology of the Shulaps Range (after LEECH, 1953). Also shown are the locations of samples c o l l e c t e d for this study. 15 Although the exact nature of the a n a l y t i c a l d i f f i c u l t i e s has been recognized, time permitted only a few of the abundant possible solutions to be implemented. This part of the M.Sc. project should thus be considered as only a preliminary invest-igation of the strontium isotope d i s t r i b u t i o n of the ultramafic rocks of the Shulaps Range. The forthcoming a v a i l a b i l i t y of more sensi t i v e equipment would f a c i l i t a t e more extensive i s o -topic analyses of these and other ultramafic and related rocks, as:a. possible follow-up project. B. Description of the Study Areas 1. The Shulaps Range Ultramafic Body a. Location and Access The ultramafic body, located 120 miles north-northeast of Vancouver, comprises most of the Shulaps Range of southwest-ern B r i t i s h Columbia (figure 1). Also known as the Yalakom mass (McTAGGART, 1972), i t was chosen for detailed study because of i t s easy access, r e l a t i v e l y large s i z e , and setting t y p i c a l of the alpine-type ultramafic bodies i n the Canadian C o r d i l l e r a . Access to the f i e l d area i s from the town of L i l l o o e t , 20 miles southeast of the body, or from the Bralorne/Gold Bridge mining d i s t r i c t , an equivalent distance to the southwest. The Shulaps Range drains to the Yalakom River on the northeast and to Carpenter Lake (Bridge River) v i a Marshall Creek on the southwest. Good dry-weather roads follow these major val l e y s along the periphery of the body, with abundant branch t r a i l s leading to the central parts of the range. b. General Geology The Shulaps intrusion l i e s within the Intermontane physiographic b e l t , just east of the Coast Plutonic Complex of the Canadian C o r d i l l e r a . The northwest-trending l e n t i c u l a r body mapped by LEECH (1953), i s about 15 miles (24 km) long and from 3 to 7 miles (5 to 11 km) wide. A major f a u l t zone along the valley of the Yalakom River forms i t s northeast boundary, separating i t from Jurassic and Lower Cretaceous greywackes. The serpentinized body, believed to be Upper T r i a s s i c i n age, intrudes metasediments and mafic volcanics of the late Paleozoic Cache Creek type to the South, and i s i t s e l f intruded by small d i o r i t i c plugs of Cretaceous - Tertiary age (figure 2). The general geology shown i n figure 2 has been adapted from LEECH (19 53). A more detailed synopsis of the surrounding geology does not seem relevant to the current project. c. The Ultramafic Mass Due to the very b r i e f nature of the author's f i e l d study, the discussion here i s li m i t e d to a summary of Leech's regional findings, supplemented by only a few personal observ-ations. The petrography of the i n d i v i d u a l samples analyzed i n th i s study i s found i n a following chapter, and i n appendix I. 17 The c l e a r l y distinguishable contacts, as on the north-eastern side of the body, are the r e s u l t of f a u l t i n g . Elsewhere, the contacts are defined by highly serpentinized, often brecc-iated rock (see plate Id), which does not permit delineation of a d e f i n i t e f a u l t . Leech was not able to determine the dips of most contacts, p a r t i c u l a r l y with the gabbro on the southwest side of the ultramafic body. Along i t s western edge, the u l t r a -mafic mass and adjacent rocks are disrupted by numerous f a u l t s of widely d i f f e r e n t attitudes. Lenses of serpentinite appear within shear zones and f a u l t s , and along contacts between d i f f -erent rock types i n t h i s v i c i n i t y (see also NAGAL, 1975). Harzburgite i s the dominant ultramafic rock, estimated by Leech to have o r i g i n a l l y constituted 85% of the mass. The re s t of the rock i s mainly dunite which, together with some very minor enstatite-pyroxenite, occurs as lenses and i r r e g u l a r pods within the otherwise homogeneous harzburgite. S l i g h t composit-ional layering i s l o c a l l y v i s i b l e , caused by p a r a l l e l zones of contrasting amounts of pyroxene c r y s t a l s . The layers are norm-a l l y a few inches thick, and while often r e p e t i t i v e , show no d e f i n i t e pattern of recurrence. The layering never p e r s i s t s for distances over 100 feet. It i s quite consistent i n i t s attitude, s t r i k i n g north-northwest arid dipping 65 degrees south-westward to v e r t i c a l (LEECH, 1953). Variable stages of serpentinization are prevalent over the entire extent of the ultramafic mass. Carbonatization and s t e a t i z a t i o n are prominent along the northwest-trending borders of the i n t r u s i o n . These al t e r a t i o n s are discussed for the 18 i n d i v i d u a l samples analyzed, i n the petrographic section of th i s report. d. Areas Examined and Samples Collected A t o t a l of s ix days i n June 1972 was spent examining the ultramafic mass i n three areas: (1) i n the southwest, i n the v i c i n i t y of Jim Creek, between Marshall Lake and Shulaps Peak; (2) i n the central-northeast sector, along Blue Creek; and (3) i n the extreme southwest portion of the body, between Shulaps Creek and Lake La Mare (figure 2). In addition, a week-end f i e l d t r i p with J.W.H. Monger, of the Geological Survey of Canada, was devoted to a study of the geological setting of the intr u s i o n . In the Jim Creek section, the ultramafic rocks exam-ined are mainly serpentinized harzburgites (SH-1,2,3,15). Also i n t h i s area i s a major coarse-grained meta-gabbroic lens (SH-12), together with some associated very fine-grained (hypabys-sal?) meta-diorite (SH-14). In addition, a sample of roddingite ("white-rock", SH-13) was obtained from a small i s o l a t e d patch of t h i s rock occurring near the poorly defined contact of the main ultramafic mass and the gabbroic lens. The foreground i n the frontispiece shows the t y p i c a l outcrop surface sampled. Blue Creek p a r a l l e l s the road heading from the Yalakom Valley to the old gold-mining camp at Elizabeth, i n the north-central part of the ultramafic body. Plates l a and lb show the t y p i c a l topography, characterized by broad U-shaped valleys separating subdued mountains often with steep talus slopes, a l l 19 above the 6000-foot t r e e - l i n e . Several serpentinized harzburg-i t e s were sampled along t h i s section of the body (SH-4,5,7,8). In addition, a major (BCP-3) and two minor (BCP-1,2) in t r u s i v e plugs belonging to the group .of Blue Creek Porphyries were inspected. A sample of a c h i l l e d r e c r y s t a l l i z e d serpentinite, i n contact with one of the minor intrusives was also c o l l e c t e d (SH-6). Along the extreme southeast edge of the body, a sample of serpentinized pe r i d o t i t e (SH-9) was col l e c t e d near Lake La Mare (plate I c ) . A specimen of serpentinite breccia set i n a carbonate matrix (SH-10) was taken from a narrow zone that possibly defines a major northwest-trending f a u l t (see figure 2). Nearby, along Shulaps Creek, a serpentinite "boulder" (SH-11) was col l e c t e d from a shear zone t y p i c a l of the f a u l t -bounded periphery of the Shulaps mass (plate Id). A summary of the samples c o l l e c t e d and t h e i r respect-ive locations i s shown i n table IV. 2. Other Ultramafic Bodies Examined In addition to the Shulaps Range ultramafic body, several other ultramafic intrusions of southern B r i t i s h Columbia and northernmost Washington State were studied. Some of the ultramafic rocks of the Bridge River area (WRIGHT, 1974), just southwest of the Shulaps Range (see figure 1), were examined in the f i e l d . These included the serpentinite pods of the Gold Bridge quarry, and at Haylmore. Although sampled, these small bodies were not analyzed due to the extremity of the serpentin-20 Table IV. Summary of the samples c o l l e c t e d and respective locations within the Shulaps Range ultramafic body. Sample No. Location F i e l d Name SH-1 SH-2 SH-3 SH-3A SH-4 SH-5 SH-6 SH-7 SH-8 SH-9 SH-10 SH-11 SH-12 SH-13 SH-14 SH-15 BCP-1 BCP-2 BCP-3 Jim Greek serpentinite H i i " serpentinized p e r i d o t i t e " weathered surface of SH-3 serpentinized p e r i d o t i t e II serpentinite contact with BCP-2 serpentinite serpentinized p e r i d o t i t e II serpentinite-carbonate breccia serpentinite "boulder", shear-W of Shulaps peak meta-gabbro zone " roddingite SW of Shulaps peak meta-diorite " serpentinite Blue Creek granodiorite " quartz d i o r i t e Elizabeth d i o r i t e Blue Creek II II E l i z a b e t h H Lake La Mare t i Shulaps Creek 21 i z a t i o n and unusually advanced surface weathering. a. The Coguihalla Serpentinite Belt A sample of the Coquihalla serpentinite provided by J.A. Chamberlain was analyzed for i t s rubidium and strontium contents. The Coquihalla b e l t i s located i n the Yale D i s t r i c t of southern B r i t i s h Columbia, just 10 miles east of Hope ( f i g -ure 1). I t i s a very thin l e n t i c u l a r alpine-type body, over 30 miles i n length and never more than 2 miles wide. The Coq-u i h a l l a l i e s at the southern end of the northwest trending b e l t of ultramafic bodies which terminates at i t s northern edge as the Shulaps Range (figure; 1). Like the Shulaps body, the Coq-u i h a l l a l i e s within the Cache Creek volcanics which as Late Paleozoic are believed to be considerably older than the i n t r u s -ives (CAIRNES, 1930). This fault-bounded body i s composed of almost e n t i r e l y serpentinized rock of p e r i d o t i t i c composition, without any apparent zoning. b. The Trapping Creek Gabbro-Peridotite Complex The Trapping Creek ultramafic i n t r u s i v e of the Beaver-d e l l area of southcentral B r i t i s h Columbia was also analyzed for i t s rubidium and strontium contents. The samples of t h i s body, located 20 miles east of Penticton, were provided by A. LeCheminant. The gabbro-peridotite i n t r u s i v e appears to f a l l i n the category of concentrically zoned ultramafic comp-lexes. 22 The ultramafic rock i s described by PEARSE (1971) as an o l i v i n e - p l a g i o c l a s e bearing pegmatitic hornblende p e r i d o t i t e . The periphery rocks of the complex include gabbro, hornblendized gabbro and hornblende d i o r i t e . Contact relationships indicate that these periphery rocks are s l i g h t l y older than the u l t r a - . mafic core. The entire complex l i e s within the Lower Paleozoic Anarchist metasediments and mid-Mesozoic Nelson meta-diorites (figure 3). S i m i l a r i t i e s between the Trapping Creek and Duke Island Complex i n Alaska include the almost i d e n t i c a l plagioclase comp-ositi o n s of comparative zones, and the occurrence of very sim-i l a r Fe-rich o l i v i n e . Pearse c i t e s three notable differences between the Trapping Creek intrusion and the t y p i c a l zoned Alaskan-type complexes: (1) the presence of orthopyroxene as a primary phase; (2) the presence of Ni-Cu sulphides; and (3) the presence of plagioclase i n olivine-pyroxene rocks. The inner dunitic and p e r i d o t i t i c zones of t y p i c a l c o n c e n t r i c a l l y -zoned complexes are absent at Trapping Creek, as i n some of the smaller Alaskan ultramafic plugs. Very s i m i l a r mineralog-i c a l and textural features are observed i n the Giant Mascot intrusion and the Tulameen Complex, both near the Coquihalla b e l t at Hope (figure 1). Figure 3 locates the ultramafic and gabbro samples analyzed and t h e i r respective zones within the intrusion, as shown on the summary geological map of PEARSE (1971) . 23 metres Ultramafic rocks Gabbro and related rocks Nelson f o l i a t e d d i o r i t e s a Anarchist metasediments Figure 3. The Trapping Creek gabbro-peridotite complex. Geology according to PEARSE (1971). Sample locations approx-imate. 24 c. The Twin Sisters Dunite The Twin Sisters Dunite i s located 80 miles south of the Canadian border, 24 miles east of Bellingham. Straddling the Whatcom and Skagit counties of northern Washington State, the e l l i p t i c a l body i s 10 miles long and averages 3^ miles i n width. The intrusion forms the north-northwest trending Sisters Mountain Range which reaches a maximum al t i t u d e of almost 7000 feet (2435 m) at the South Twin. This rock, w e l l -exposed above the 4000-foot (1220 m) contour l i n e , forms a s t r i k i n g l y b r i l l i a n t orange-red surface v i s i b l e for several miles i n a l l d i r e c t i o n s . Best access to the ultramafic mass i s by a complex mesh of recent logging roads leading east from the small town of Acme (figure 4). GAUDETTE (1963) shows that the Twin Sisters i s composed of 80-90% dunite, which i s f o r s t e r i t e (Fog4_9o^• Saxonite (olivine + 10-20% orthopyroxene + opaque oxides) makes up about 10% of the body, occurring as blocks with i n d e f i n i t e boundaries. Serpentinite and veins and pods.' of chromite form the remainder of the body. The serpentinite occurs mainly as a marginal r i n d as much as | mile wide, and as veins along fracture zones within the central dunite mass. The remarkably fresh dunite i s holo-c r y s t a l l i n e , containing anhedral grains of pale yellow-green o l i v i n e ranging from less than 0.1 mm to greater than 8 mm i n diameter; e n s t a t i t e , chromite, magnetite and serpentine are also present (MOEN, 1969). Gaudette's modal analyses of 38 specimens y i e l d s an average of 93.1% o l i v i n e , 4.7% enstatite (of the same Mg/Fe r a t i o as the o l i v i n e ) , 1.9% chromite, and Deming AcmeTfc LEGEND Terti a r y (?) dunite Pre-Upper Jur a s s i c low-grade metamorphic rocks (mainly p h y l l i t e ) . I n c l -udes patches of sandstone and conglomerate of the Swauk or Chuckanut form-ation of upper-most Cret-aceous - Paleocene age Carboniferous - Permian sedimentary and volcanic rocks of the Chilliwack Group Thrust f a u l t scale 8 km Figure 4. The Twin Si s t e r s Dunite, Washington, showing sample locations and major geo l o g i c a l features of the area. Adapted a f t e r RAGAN (1963), MOEN (1969) and MISCH (1952, 1960). 26 0.8% others, mainly serpentine. The dunite appears to have been emplaced along the Shuksan thrust (figure 4). Contacts are poorly exposed. The block east of the f a u l t i s composed of Carboniferous-Permian sedimentary and volcanic rocks of the Chilliwack Group, consist-ing mainly of greywacke, s i l t s t o n e , a r g i l l i t e and minor altered b a s a l t i c rock. To the west, pre-Jurassic graphitic and quartz-ose p h y l l i t e dominate (figure 4). Also around the western edge of the dunite are i s o l a t e d outcrops of pre-Carboniferous altered gabbroic rocks and pyroxenite, as well as small bodies of sand-stone and conglomerate of the Late Cretaceous-Paleocene Chuck-anut or Swauk Formation (MOEN, 1969; RAGAN, 1967). As the dunite i s found to intrude the Chuckanut Formation, a l l workers agree to a post-Paleocene age for the Twin Sisters (see also MISCH, 1952). A gravity survey by THOMPSON (1963) indicates an aver-age depth of only 1200 to 1600 meters. Thompson also suggests that the dunite i s replaced by serpentinite at depth. RAGAN (1967) stresses the absence of zoning, any d i f f e r e n t i a t i o n or other igneous character, or evidence for the existence of a c r y s t a l mush or magma. I t should be pointed out, however, that abundant (60%) clinopyroxene was found i n the marginal serpent-i n i t e analyzed i n thi s study. The t o t a l absence of clinopyrox-ene i n the central dunite appears to indicate some sort of zoning i n the body. This aspect i s further discussed within the petrography section of t h i s paper. 27 Only the extreme northwest corner of the d u n i t e body was examined as p a r t of the pr e s e n t study. Samples analyzed are of the p e r i p h e r y s e r p e n t i n i t e and the i n n e r d u n i t e o b t a i n e d from the l o c a t i o n s shown i n f i g u r e 4. C. A n a l y t i c a l Techniques A flow c h a r t f o r sample treatment i s shown i n f i g u r e 5. 1. Sample C o l l e c t i o n and P r e p a r a t i o n As a g e n e r a l r u l e , 10 to 20 l b s (4.5to 9.1kg) of f r e s h rock were c o l l e c t e d a t each l o c a l i t y . For each sample, two l a r g e p i e c e s were chosen as hand-specimens, one of which was used t o p r o v i d e a t h i n - s e c t i o n . Any a l t e r e d s u r f a c e s were removed and the sample was crushed i n a jaw-crusher, and subseq-u e n t l y i n a cone-crusher, to a g r a i n - s i z e of about 2 mm i n diameter. From t h i s a 250 gm a l i q u o t was p u l v e r i z e d t o a 100-mesh s i z e (0.174 mm) powder. Some of the p l a t y m a t e r i a l had t o be f u r t h e r ground i n a Spex m i l l , to ensure t h a t a l l the mater-i a l passed through the 100-mesh s e i v e . 2. Petrography The petrography of the rocks was s t u d i e d through hand-specimen and t h i n - s e c t i o n examinations, and q u a l i t a t i v e powder whole-rock x-ray d i f f r a c t i o n a n a l y s i s . No attempt i s made a t an o v e r a l l m i n e r a l o g i c a l o r t e x t u r a l a n a l y s i s of the u l t r a m a f i c b odies. Rather, d e s c r i p t i v e p e t r o g r a p h i c notes are i n c l u d e d Sample (5 to 10 kg of fresh material collected i n the f i e l d ) hand-specimens and thin-sections petrographic study removal of a l l weathered surfaces crushed (to about 2 mm diameter) 250 gm aliquot ground to 100 mesh (0.174 mm) sli d e s for XRD analysis p e l l e t s for XRF analysis i d e n t i f i c a t i o n of mineral phases Rb and Sr concentration and Rb/Sr r a t i o determined addition of Sr84 spike to sample (both c a r e f u l l y weighed) sample dissolution using digestion bombs i s o l a t i o n of Sr concentrate by ion exchange mass spectrometer run, to determine the Sr87/Sr86 r a t i o and t o t a l Sr content Figure 5. Summary of a n a l y t i c a l procedures. 29 here p r i m a r i l y to l e n d f u r t h e r i n f o r m a t i o n on the i n d i v i d u a l samples whose rubidium and s t r o n t i u m geochemistry was s t u d i e d . a. X-Ray D i f f r a c t i o n I d e n t i f i c a t i o n of M i n e r a l Phases The mineralogy of the u l t r a m a f i c whole-rocks was checked by q u a l i t a t i v e x-ray d i f f r a c t i o n a n a l y s i s . Table V shows the parameters used i n the a n a l y s e s . The d i f f r a c t i o n t r a c e s were compared w i t h standard t r a c e s o b t a i n e d from the ASTM powder d i f f r a c t i o n f i l e . ZUSSMAN e t a l (1957) and AUMENTO (1970) among o t h e r s , have t r i e d to d i s t i n g u i s h between the s e r p e n t i n e m i n e r a l s by x-ray d i f f r a c t i o n techniques. Aumento, i n p a r t i c u l a r , succeeded i n d i f f e r e n t i a t i n g the most common m i n e r a l s c h r y s o t i l e , l i z a r d -i t e and a n t i g o r i t e , on the b a s i s of d i f f r a c t i o n t r a c e s of n e a r l y pure s e r p e n t i n i t e s . The complex mineralogy of p a r t i a l l y s e r p -e n t i n i z e d rocks makes i t d i f f i c u l t to t e l l the s e r p e n t i n e m i n e r a l s apart; but, f o r some samples t e n t a t i v e i d e n t i f i c a t i o n s were p o s s i b l e . In a d d i t i o n to s e r p e n t i n e , other a l t e r a t i o n m i n e r a l s r e c o g n i z e d i n the d i f f r a c t i o n t r a c e s are c h l o r i t e , t a l c , magnet-i t e , magnesite, and p o s s i b l y b r u c i t e . A l s o found are the primary u l t r a m a f i c m i n e r a l s o l i v i n e , e n s t a t i t e , and d i o p s i d e , and chromite. R e s u l t s of the x-ray d i f f r a c t i o n analyses are i n d i c a t e d w i t h the p e t r o g r a p h i c d e s c r i p t i o n s i n appendix I. Among the s e r p e n t i n e m i n e r a l s , l i z a r d i t e appears to be dominant, as i s to 30 Table V. Operating parameters used i n the whole-rock powder x-ray d i f f r a c t i o n study. sample p r e p a r a t i o n r a d i a t i o n f i l t e r x-ray tube v o l t a g e x-ray tube amperage c h a r t speed scan speed s c a l e time c o n s t a n t b a s e l i n e window acetone + glue Cu Ni 40 kV 20 mA 2 cm/min 2° 2 /min 2 x 10 2 1 sec 400 V 100 V Table VI. Operating parameters of the P h i l l i p s x-ray f l u o r e s c e n c e u n i t . t a r g e t m a t e r i a l , x-ray tube x-ray tube v o l t a g e x-ray tube amperage p u l s e h e i g h t a n a l y z e r a t t e n u a t i o n lower l e v e l v o l t a g e window time c o n s t a n t c r y s t a l c o l l i m a t o r s e t t i n g molybdenum 50 kV 30 mA 5 270 V 400 V 0.5 sec l i t h i u m f l u o r i d e (d 200) f i n e 31 be expected f o r the low-'temperature emplaced a l p i n e - t y p e u l t r a m a f i c rocks (AUMENTO, 1970). Dio p s i d e s u r p r i s i n g l y i s i d e n t i f i e d i n s e v e r a l t r a c e s where e n s t a t i t e i s not, although corresponding t h i n - s e c t i o n s i n d i c a t e the dominance of o r t h o -pyroxene over c l i n o p y r o x e n e . D e l i n e a t i o n of v a r i o u s m i n e r a l phases by the q u a l i t -a t i v e powder x-ray d i f f r a c t i o n technique thus appears to have been most v a l u a b l e i n c o n f i r m i n g t h i n - s e c t i o n m i n e r a l i d e n t -i f i c a t i o n s . b. Hand-Specimen and T h i n - S e c t i o n Analyses Macroscopic (hand-specimen) and m i c r o s c o p i c ( t h i n -s e c t i o n ) d e s c r i p t i o n s o f the rocks analyzed are giv e n i n app-endix I. 3. X-ray F l u o r e s c e n c e Determination of Rb and Sr Co n c e n t r a t i o n s Rubidium and s t r o n t i u m c o n c e n t r a t i o n s were determined u s i n g standard x-ray f l u o r e s c e n c e techniques, m o d i f i e d f o r use a t U.B.C. by B.D.Ryan. E x c e l l e n t d i s c u s s i o n s as to the g e n e r a l theory and procedures may be found i n CHAPPELL e t a l (1969), COMPSTON e t a l (1969), DOERING (1968), FAIRBAIRN and HURLEY (1971), JENKINS and DEVRIES (1967), LEAKE e t a l (1969), NORRISH and CHAPPELL (1967) and most r e c e n t l y , PANKHURST and O'NIONS (1973). S p e c i f i c l a b o r a t o r y techniques as used here are e x h a u s t i v e l y d i s c u s s e d i n RYAN (1973). E s s e n t i a l l y no modif-i c a t i o n s were made i n Ryan's procedures. A P h i l l i p s x-ray f l u o r e s c e n c e spectrometer was used. The o p e r a t i n g parameters of the u n i t are shown i n t a b l e VI. Samples were analyzed i n the form of p e l l e t s c o n t a i n i n g 4 to 5 gm of <100-mesh rock powder. The rubidium and s t r o n t i u m c o n c e n t r a t i o n s were d e t e r -mined by comparing the unknown samples wi t h U n i t e d S t a t e s Geol-o g i c a l Survey standards. Because of the extremely low Rb and Sr c o n c e n t r a t i o n s of the u l t r a m a f i c rocks s t u d i e d , the U.S.G.S. standards W-l (diabase), PCC-1 ( p e r i d o t i t e ) , and DTS-1 (dunite) were used in.' a d d i t i o n to h i g h - c o n c e n t r a t i o n standards GSP-1 ( g r a n o d i o r i t e ) , BCR-1 ( b a s a l t ) , AGV-1 ( a n d e s i t e ) , and G-2 (gran-i t e ) . Reported c o n c e n t r a t i o n s of Rb and Sr f o r the standards vary q u i t e s i g n i f i c a n t l y , as shown i n t a b l e s V I I and V I I I . The more accurate determinations appear to have been made by i s o t o p e d i l u t i o n mass s p e c t r o m e t r i c a n a l y s e s . Most of the i n t e r l a b o r -a t o r y v a r i a t i o n s q u i t e probably r e f l e c t i m p e r f e c t homogeneity of the samples handled. Tables VII and V I I I a l s o i n d i c a t e the c o n c e n t r a t i o n v a l u e s used i n t h i s study, chosen l a r g e l y on the b a s i s of r e s u l t s of the most r e c e n t i s o t o p e d i l u t i o n analyses of the u l t r a m a f i c standards, and i n t e r n a l c o n s i s t e n c y o b t a i n e d by Ryan f o r the h i g h e r - c o n c e n t r a t i o n standards. The mass a b s o r p t i o n c o e f f i c i e n t v a l u e s {JJL) used f o r the standards are shown i n t a b l e IX. These f i g u r e s were based on d i r e c t l y meas-ured r e s u l t s which, as BLENKINSOP (1972) p o i n t s out, are b e l -i e v e d to be b e t t e r determined than c a l c u l a t e d /x* s which are s e n s i t i v e t o u n c e r t a i n t i e s i n the measurement of i n d i v i d u a l elements wi t h h i g h yu v a l u e s . However, wit h r e g a r d t o the 33 Table V I I . Rubidium c o n c e n t r a t i o n s ( i n ppm) of the U.S.G.S. rock standards as r e p o r t e d i n r e c e n t studies-, and as used here. GSP.-l BCR-1 AGV-1 G-2 W-l DTS-1 PCC-1 Ref 273 52 74 189 2 1 1 254.5 46.9 66.6 167.6 0.050 0.062 2 250 48.2 67.0 169 3 254.7 47.3 67.1 169.3 0.057 0.055 4 254 46.6 67 168 21 0.053 0.063 5 255 48.2 67.0 169 6 261 48. 2 67 171 21.6 7 0.053 0.064 8a 0.062 0.077 8b 0.073 0.075 9 21.6 10 255.0 48.2 67.0 169.0 21.6 0.05 0.06 11 Reference A n a l y t i c a l Method 1. F r a n z a n i e t a l , 1972 2. DeLaeter and Abercrombie, 1970 3. F a i r b a i r n and Hurley, 1971 4. Pankhurst and O'Nions, 1973 5. Flanagan, 1973 6. Blenkinsop, 1972 7. Ryan, 1973 8a. C h a p p e l l e t a l , 1969 8b. 9. Stueber and Ikramuddin, 1974 10. Chaudhuri and Faure, 196 7 11. Values chosen i n p r e s e n t study x-ray f l u o r e s c e n c e i s o t o p e d i l u t i o n c o m p i l a t i o n , i n c l u d e s r e f e r e n c e s 1, 2, 3 s e l e c t e d from r e f e r e n c e s 2 and 3, and the i n t e r n a l c o n s i s t e n c y o f x-ray f l u o -rescence analyses a t U.B.C, based mainly on i n t e r n a l c o n s i s t e n c y of x-ray f l u o -rescence analyses a t U.B.C. i s o t o p e d i l u t i o n x-ray f l u o r e s c e n c e i s o t o p e d i l u t i o n 34 Table V I I I . Strontium c o n c e n t r a t i o n s ( i n ppm) of the U.S.G.S. standards as r e p o r t e d i n r e c e n t s t u d i e s , and va l u e s used here. References as i n t a b l e V I I . GSP-1 BCR-1 AGV-1 G-2 W-l DTS-1 PCC-1 Ref 243 332 696 500 8 7 1 233. 2 331. 5 656. 6 474.8 0.39 0.42 2 235 332 659 478 3 233.1 332.1 662 476.3 0.31 0.36 4 233 330 657 479 190 0.35 0.41 5 235 331 663 480 6 235 331 663 480 190 7 0.31 0.38 8a 0.38 0.37 8b 0.245 0.369 9 189.8 10 235.0 331.0 663.0 480.0 190.0 0.35 0.41 11 Table IX. Mass a b s o r p t i o n c o e f f i c i e n t v a l u e s (jX) used f o r the U.S.G.S. standard rocks ( a f t e r BLENKINSOP, 1972). GSP-1 6.760 BCR-1 9.612 AGV-1 7.412 G-2 6.075 W-l 9.225 DTS-1 6.800 PCC-1 7.213 r e l a t i v e l y low l e v e l of accuracy (because of the e x t r a o r d i n a r y minute c o n c e n t r a t i o n s ) of the x-ray f l u o r e s c e n c e analyses done i n t h i s study, s l i g h t d e v i a t i o n s i n theyuvalues are of no s i g n i f i c a n c e . The e n t i r e s e t of u l t r a m a f i c samples was analyzed as a batch, the process t a k i n g a f u l l uninterrupted day. T r i p l i c -ate a n a l y t i c a l runs were s u c c e s s f u l l y accomplished. F o r each run, the unknown c o n c e n t r a t i o n s were c a l c u l a t e d (A) u s i n g a l l seven U.S.G.S. standards; (B) u s i n g o n l y the h i g h - c o n c e n t r a t i o n standards GSP-1, AGV-1, BCR-1, G-2 and W-l; and (C) u s i n g o n l y the l o w - c o n c e n t r a t i o n standards W-l, DTS-1 and PCC-1. The r e s u l t s are shown i n t a b l e s X and XI. Very good r e p r o d u c i b i l i t y was o b t a i n e d between runs. For the d i f f e r e n t s e t s of standards used, (A) and (B) gave e s s e n t i a l l y the same r e s u l t s . The t h i r d s e t (C), y i e l d e d s l i g h t l y lower c o n c e n t r a t i o n s , s i g n i f i c a n t l y d i f f e r e n t o n l y i n the case of Sr. The v a l u e s chosen as r e p r e s -e n t i n g the most accurate c o n c e n t r a t i o n s are shown i n t a b l e X I I . The f i g u r e s are the mean v a l u e s o b t a i n e d f o r the t h r e e runs c a l c u l a t e d on the b a s i s of the low c o n c e n t r a t i o n standards (C) alone. The Trapping Creek r o c k s , w i t h t h e i r much h i g h e r Rb and Sr c o n c e n t r a t i o n s , d i c t a t e d the use o f a l l seven U.S.G.S. standards. A l s o shown i n t a b l e XII are the corresponding c a l c -u l a t e d Rb/Sr r a t i o s f o r the samples. RYAN (1973) estimates t h a t the p r e c i s i o n of the conc-e n t r a t i o n s o b t a i n e d by the x-ray f l u o r e s c e n c e procedures used a t U.B.C. as about 1.5%. He a l s o a p p l i e s the c o n d i t i o n t h a t the Rb and Sr c o n c e n t r a t i o n s measured be more than 40 ppm (re-36 Table X. R e p l i c a t e x-ray f l u o r e s c e n c e d e t e r m i n a t i o n of Rb c o n c e n t r a t i o n s (ppm) . A. Using a l l seven U. S • G. S. standards (values as i n t a b l e VII) B. Using o n l y standards GSP -1, BCR -1, AGV-1, ' G-2, and W-l • C. Using o n l y standards W-l , DTS-1 , and PCC-1 • A B C Sample Run 1 2 3 Run 1 2 3 Run 1 2 3 SH-1 0.0 0.0 0.4 0.0 0.0 0.4 0.0 0.0 0.4 SH-1 1 0.0 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.1 SH-2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 SH-3 0.3 0.0 0.5 0.3 0.0 0.5 0.2 0.0 0.5 SH-3A 0.0 0.2 0.0 0.2 0.0 0.2 SH-4 0.1 0.7 0.0 0.1 0.7 o.oc 0.1 0.7 0.0 SH-5 0.2 0.4 0.0 0.2 0.4 0.0 0.2 0.4 0.0 SH-6 0.2 0.5 0.0 0.2 0.5 0.0 0.1 0.5 0.0 SH-7 0.4 0.0 0.8 0.4 0.0 0.8 0.3 0.0 0.8 SH-8 0.2 0.2 0.3 0.2 0.2 0.3 0.2 0.2 0.3 SH-9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 TSD-1 0.0 0.4 0.0 0.0 0.4 0.0 0.0 0.4 0.0 TSS-1 0.4 0.1 0.6 0.4 0.1 0.6 0.3 0.1 0.6 TSS-2 0.1 0.4 0.2 0.1 0.4 0.2 0.0 0.3 0.2 CO-1 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.1 0.0 TC-U 6.2 5.8 6.3 6.3 5.8 6.3 5.0 5.4 6.0 TC-G 0.9 1.9 0.8 0.9 1.9 0.8 0.7 1.8 0.8 (DTS-1) 0.2 0.1 0.3 (PCC-1) 0.6 0.4 0.2 37 Table X I . R e p l i c a t e x-ray f l u o r e s c e n c e d e t e r m i n a t i o n o f Sr c o n c e n t r a t i o n s (ppm). A , B , C : as i n t a b l e X . A B C Sample Run 1 2 3 Run 1 2 3 . Run 1 2 3 SH-1 4.2 4.0 4.5 4.2 4.1 4.5 3.4 3.3 3.7 SH-1 1 4.2 4.0 4.4 4.2 4.0 4.5 3.4 3.2 3.7 SH-2 5.9 5.8 5.8 6.0 5.8 5.8 4.8 4.7 4.8 SH-3 6.5 6.6 7.0 6.6 6.7 7.1 5.3 5.3 5.8 SH-3A 7.0 6.9 7.1 7.0 5.7 5.7 SH-4 4.4 4.5 4.4 4.5 4.5 4.4 3.6 3.6 3.6 SH-5 2.5 3.5 2.7 2.5 3.5 2.7 2.0 2.8 2.2 SH-6 7.5 7.3 7.3 7.6 7.3 7.4 6.1 5.9 6.1 SH-7 7.4 7.9 7.8 7.5 8.0 7.9 6.1 6.4 6.5 SH-8 2.8 2.9 2.6 2.9 3.0 2.6 2.3 2.4 2.1 SH-9 3.1 3.2 3.2 3.2 3.2 3.2 2.5 2.6 2.6 TSD-1 3.6 3.5 3.1 3.6 3.6 3.1 2.9 2.8 2.5 TSS-1 19. 2 18.9 19.1 19. 5 19.3 19.4 15.4 15.0 15.4 TSS-2 17.0 17.3 17. 2 17.3 17.6 17.6 13.6 13.7 13.9 CO-1 6.9 6.7 6.3 7.0 6.8 6.4 5.6 5.5 5.2 TC-U 267.2 266.0 268.8 273.2 272. 2 274.6 211.6 207.1 214.1 TC-G 535.6 541.7 540.9 548.6 555. 8 553.6 421.9 418. 6 427.8 (DTS-1) (PCC-1) 3.7 3.1 3.9 3.4 4.1 3.2 38 Table XII. Best x-ray f l u o r e s c e n c e - determined v a l u e s f o r Rb and Sr c o n c e n t r a t i o n s and corresponding Rb/Sr r a t i o s . Sample Standards used Rb(ppm) Sr(ppm) Rb/Sr (tab l e XI) SH-1 C 0.1 3.5 0.03 SH-1' C <0.1 3.4 <0.03 SH-2 C <0.1 4.8 <£0.02 SH-3 C 0.2 5.5 0.04 SH-3A C 0.1 5.7 0.02 SH-4 C 0.3 3.6 0.08 SH-5 C 0.2 2.3 0.09 SH-6 C 0.2 6.0 0.03 SH-7 C 0.4 6.3 0.06 SH-8 C 0.2 2.3 0.09 SH-9 C <0.1 2.6 <0.04 TSD-1 C 0.1 2.7 0.04 TSS-1 C 0.3 15.3 0.02 TSS-2 C 0.2 13.7 0.02 CO-1 C <0.1 5.4 <0.02 TC-U B 6.1 273.3 0.02 TC-G B 1.2 552.7 0.00. c a l l however, t h a t he d i d not use the l o w - c o n c e n t r a t i o n U.S.G.S. s t a n d a r d s ) . For the p r e s e n t study, based on the c l o s e s i m i l a r -i t y i n r e s u l t s f o r the three separate runs, and very f a v o u r a b l e comparison w i t h the Sr c o n c e n t r a t i o n s o b t a i n e d by the i s o t o p e d i l u t i o n technique (see the mass spectrometry s e c t i o n ) , the p r e c i s i o n i s judged t o be w i t h i n 0.5 ppm f o r both Rb and Sr. Because of the exceedingly lcw.Rb c o n c e n t r a t i o n s ( a l l l e s s than 1 ppm f o r the u l t r a m a f i c r o c k s ) , the c a l c u l a t e d Rb/Sr r a t i o s should o n l y be c o n s i d e r e d as order-of-magnitude f i g u r e s . 4. Chemical D i s s o l u t i o n of Samples The procedure f o r sample d i s s o l u t i o n used i n t h i s study was an adapti o n of the Un i t e d States G e o l o g i c a l Survey's method (PETERMAN e t a l , 1967), as m o d i f i e d by RYAN (1973) and f u r t h e r by t h i s author. About 1 gm of p r e c i s e l y - w e i g h e d sample (< 100-mesh s i z e powder) was mixed w i t h a few drops of d o u b l e - d i s t i l l e d water, 1 ml of 48% h y d r o f l u o r i c a c i d , 2 ml of 9 molar s u l p h u r i c a c i d , and 1 ml of n i t r i c a c i d . To t h i s , the p r e c i s e l y - w e i g h e d Sr84 s p i k e was added, the mixture being p l a c e d w i t h i n a 12 ml c a p a c i t y ( h a l f - f u l l ) t e f l o n - l i n e d a c i d d i g e s t i o n bomb, manu-f a c t u r e d by the Parr Instrument Company of I l l i n o i s . The amount of spike added was determined by the Sr content of the sample, so t h a t a Sr84/Sr86 r a t i o g r e a t e r than 1 but not more than 3 was a t t a i n e d f o r the s o l u t i o n (see l a t e r d i s c u s s i o n ) . A 2.5 cc p l a s t i c s y r i n g e was employed here, being c a r e f u l l y weighed be f o r e and a f t e r d e l i v e r y of the Sr84 s p i k e . The 40 advantage of adding the spike a t t h i s e a r l y p r e - d i s s o l u t i o n stage i s t h a t , i n case of any sample l o s s i n l a t e r h a n d l i n g of the s o l u t i o n , the r e l a t i v e p r o p o r t i o n of rock t o spike remains u n a l t e r e d . T h i s i s a c r i t i c a l n e c e s s i t y f o r the ac c u r -ate d e t e r m i n a t i o n o f t h e - t o t a l s t r o n t i u m content o f the rock, through the i s o t o p e d i l u t i o n technique. The bomb was then heated i n an oven f o r about 40 hours a t approximately 130° C. Next, the sample was q u a n t i t a t i v e l y t r a n s f e r r e d t o a 100 ml t e f l o n e v a p o r a t i n g d i s h and taken to dryness. T h i s e v a p o r a t i o n was repeated twice w i t h the a i d of u l t r a - p u r e water, and the use of an i n f r a - r e d lamp p l a c e d above the t e f l o n - c o v e r e d d i s h . Because of the very low s t r o n t i u m c o n c e n t r a t i o n o f the u l t r a m a f i c r o c k s , i t was necessary t o process two, and i n l a t e r cases three separate 1 gm a l i q u o t s . T h i s means t h a t each sample was d i s s o l v e d i n up to three separate bombs, the r e s u l t i n g f r a c t i o n s being combined p r i o r to e v a p o r a t i o n . The sample was then r e - t r a n s f e r r e d t o a 50 ml t e f l o n beaker and d i s s o l v e d i n 10 ml of 6 molar h y d r o c h l o r i c a c i d . A t t h i s stage i t was ready t o be c e n t r i f u g e d and passed through the ion-exchange columns, i n order t o e x t r a c t the s t r o n t i u m c o n c e n t r a t e . In the sample d i s s o l u t i o n p r o c e s s , the primary r e a c t -i o n i s the breakdown of s i l i c a t e s by h y d r o f l u o r i c a c i d , as i n : S i 0 2 + 4HF — > S i F 4 + 2H 20. S i l i c o n t e t r a f l u o r i d e escapes as a gas. The r e s u l t a n t c a t i o n f l u o r i d e s a l t s then r e a c t w i t h the s u l p h u r i c and n i t r i c a c i d s to form the more s o l u b l e s u l p h -ates and n i t r a t e s , r e s p e c t i v e l y . These are f u r t h e r converted t o the even more s o l u b l e c h l o r i d e s . The t o t a l c o n v e r s i o n o f any remaining sulphates to c h l o r i d e s i s accomplished i n the p r e l i m i n a r y p a r t o f the ion-exchange procedure d e s c r i b e d next. 5. Strontium I s o l a t i o n by Ion Exchange F o l l o w i n g chemical d i s s o l u t i o n of the sample, i o n exchange columns were used t o i s o l a t e the s t r o n t i u m . The theory of c a t i o n exchange chromatography i s w e l l e x p l a i n e d by MAYER and TOMKINS (1947), and d e t a i l s as to the p r e p a r a t i o n of the columns i n the U.B.C. l a b o r a t o r y have been d e s c r i b e d by RYAN (1973). The sample was f i r s t e l u t e d through about 10 gm of Dowex 50-8X i o n exchange r e s i n , w i t h 6 molar h y d r o c h l o r i c a c i d . The 25 t o 65 ml "cut" of e l u a n t was r e t a i n e d . T h i s 40 ml of s o l u t i o n c o n t a i n i n g both rubidium and s t r o n t i u m was then taken to dryness and r e - d i s s o l v e d i n 5 ml of 2 molar h y d r o c h l o r i c a c i d . T h i s s o l u t i o n was then passed through a s i m i l a r r e s i n column, t h i s time w i t h 2 molar h y d r o c h l o r i c a c i d . The 80 ml to 120 ml c u t of e l u a n t was r e t a i n e d . The cu t s were based on the c a r e f u l c a l i b r a t i o n o f the i o n exchange columns by Ryan. The f i n a l s o l u t i o n , r e p r e s e n t i n g the s t r o n t i u m c o n c e n t r a t e i n the form of s t r o n t i u m c h l o r i d e , was then t r a n s f e r r e d and evap-o r a t e d t o dryness i n a 5 ml t e f l o n beaker. The sample c o u l d then be s t o r e d f o r up to s e v e r a l weeks bef o r e mass»'spectrometer a n a l y s i s . 42 6. Mass Spect r o m e t r i c Analyses of Sr87/Sr86 R a t i o s and T o t a l  Sr C o n c e n t r a t i o n s by Isotope D i l u t i o n A l l a n a l y s es were made on a 30 cm, 90° s i n g l e - f o c u s i n g mass spectrometer. The t r i p l e - f i l a m e n t technique was used, w i t h the s t r o n t i u m c h l o r i d e being loaded onto rhenium f i l a m e n t s . D e t a i l s as t o the procedure used i n the mass spectrometer analyses can be found i n BLENKINSOP (1972). I t was Blenkinsop who f o s t e r e d the mass spectrometer and i n t r o d u c e d the author t o i t s o p e r a t i o n . His a n a l y t i c a l procedures were i d e n t i c a l l y f o l l o w e d w i t h the e x c e p t i o n t h a t the analyses were made a t much highe r temperatures, corresponding to supply c u r r e n t s o f up t o 5.0 A and 2.5 A f o r the ce n t r e and s i d e f i l a m e n t s r e s p e c t i v e l y . These h i g h temperatures were necessary t o i o n i z e s u f f i c i e n t l y d e t e c t a b l e s t r o n t i u m . As the sample was spik e d , a l l scans i n c l u d e d the r e c o r d i n g of Sr88, Sr87, Sr86 as w e l l as Sr84. When a p p r o p r i a t e , a Rb85 peak was measured i n order to c o r r e c t f o r any rubidium t h a t may have c o n t r i b u t e d to the 87-mass peak. Each "run" comprised a b l o c k o f 6 to 10 c o n s e c u t i v e scans. Because of the very s m a l l amount of s t r o n t i u m loaded on the f i l a m e n t s (estimated never t o have exceeded 2 ug), the analyses c o u l d not be monitored i n the f a s h i o n d e s c r i b e d by Blenkinsop, so as t o o b t a i n any pre-determined d e s i r e d p r e c i s -i o n . S t a b i l i t y o f . t h e mass peaks a t such extreme a n a l y t i c a l temperatures was understandably q u i t e low. The r a t i o o f succ-e s s f u l analyses compared wi t h t o t a l attempts (about 1:4) a t t r i b -utes to the d i f f i c u l t y a s s o c i a t e d w i t h simply o b t a i n i n g a d e f i n -i t e r e s u l t . N e v e r t h e l e s s , very good p r e c i s i o n was i n f a c t 43 obtained f o r the few s u c c e s s f u l runs (see t a b l e XIV). The main d i f f i c u l t y with the mass spectrometer stemmed from the f a c t t h a t i t was not being employed on a f u l l - t i m e b a s i s . For s e v e r a l samples a s u f f i c i e n t amount of s t r o n t i u m f o r a s u c c e s s f u l run was detected,* however some phase of the mass spectrometer^.instrumentation such as the magnet c u r r e n t , the vacuum pumps or the o n - l i n e computer f a c i l i t y would break down and the sample would be l o s t . Anomalous rubidium i n the source a l s o l e a d to the l o s s of one sample. For each run, d e f i n e d by a b l o c k of scans, the mass spectrometer y i e l d s the Sr88/Sr86, Sr87/Sr86 and Sr84/Sr86 r a t i o s f o r the mixture of sample and s p i k e analyzed. The parameters and equations then used i n the c a l c u l a t i o n of the Sr87/Sr86 r a t i o and the Sr content of the sample are shown i n t a b l e X I I I . The r e s u l t s are shown i n t a b l e XIV. D. Summary and D i s c u s s i o n of R e s u l t s The u l t r a m a f i c rocks of the Shulaps Range y i e l d Rb and Sr c o n c e n t r a t i o n s averaging 0.2 ppm and 4.2 ppm r e s p e c t -i v e l y , as determined by x-ray f l u o r e s c e n c e a n a l y s i s . T h i s corresponds to a Rb/Sr r a t i o of 0.05 ( t a b l e X I I ) . Not much v a r i a t i o n from these average v a l u e s was o b t a i n e d , and no c o r r e l -a t i o n w i t h m i n e r a l content c o u l d be e s t a b l i s h e d . S i m i l a r Rb and Sr v a l u e s were measured f o r the C o q u i h a l l a s e r p e n t i n i t e , w h i le the Twin S i s t e r s samples y i e l d e d s l i g h t l y h i g h e r Sr contents. C o n s i d e r a b l y g r e a t e r Sr c o n c e n t r a t i o n s are shown 44 Table X I I I . Parameters and equations used i n the c a l c u l a t i o n of Sr87/Sr86 and t o t a l Sr c o n c e n t r a t i o n s from mass spectrometer data. (A) "Common" Sr and Kb constants Sr86/Sr88 = 0.1194 (Sr88/Sr86 = 8.375) Sr84/Sr86 = 0.0570 Sr84/Sr88 = 0.0068 Sr85/Sr87 = 2.593 (B) Sr84 spike data (from RYAN, 1973) t o t a l c o n c e n t r a t i o n : 0.0235 umoles gm + 0.02% c-components : Sr84 1.972 ugm/gm 81.8% wt Sr86 0.0386 1.6 Sr87 0.0904 3.7 Sr88 0.3117 12.9 i s o t o p i c r a t i o s : Sr86/Sr84 = 0.0448 + 0.3% o~ Sr87/Sr84 = 0.01892 + 0.3%o-Sr88/Sr84 = 0.1509 + 0.1%«r-(C) N o r m a l i z a t i o n equation ( t o c o r r e c t f o r f r a c t i o n a t i o n ) Sr88/Sr86 = (S r 8 8 / S r 8 6 ) M + [ ( S r 8 8 / S r 8 6 ) M - (Sr88/Sr86)g] ( S r 8 4 / S r 8 6 ) M - (Sr84/Sr86) n . [ - , ] ( S r 8 4 / S r 8 6 ) s - (Sr 8 4 / S r 8 6 ) M where, s u b s c r i p t s M = measured r a t i o of mixture of sample and sp i k e S = r a t i o o f sp i k e C = r a t i o of "common" s t r o n t i u m ( S r 8 8 / S r 8 6 ) M and (S r 8 4 / S r 8 6 ) M are r e p e a t e d l y c o r r e c t e d ( i t e r a t e d ) t i l l Sr88/Sr86 = 8.375 = (Sr88/Sr86) c. We thus o b t a i n the normalized v a l u e s , ( S r 8 8 / S r 8 6 ) N and 45 Table XIII (continued) (Sr87/Sr86) N and a corresponding (Sr87/Sr86) N o b t a i n e d from: (Sr87/Sr86) = [(Sr87/Sr86)„] . [1 + 1 [ ( S r 8 6 / S r 8 8 ) M ] }  w Z ('Sr86/Sr88) (D) F i n a l c a l c u l a t i o n of Sr87/Sr86 of sample , ( S r 8 7 / S r 8 6 ) s a m p l e = ( S r 8 7 / S r 8 6 ) N + j.(Sr87/Sr86)^ - ( S r 8 7 / S r 8 6 ) s ( S r 8 4 / S r 8 6 ) N - ( S r 8 4 / S r 8 6 ) s . [ ( S r 8 4 / S r 8 6 ) c - (Sr84/Sr86) ] (E) T o t a l Sr c o n c e n t r a t i o n of sample Sr86 (umoles/sample) = [umoles (Sr84) s] . [1 - (Sr.8.4/.Sr.8.6)M (Sr86/Sr84) ] [ ( S r 8 4 / S r 8 6 ) M - (Sr84/Sr86) c] then, Sr86(ug/sample) = ( S r 8 6 ) u m o l e s • [ a t - w t « o f Sr86] (Sr86) , umole; (Sr86/Sr88) and, Sr88(ug/sample) = [ v ; u m o l e s ] . [at. wt. of Sr88] C Sr87 (ug/sample) = M S r 8 6 j < m o l e s ] . [|||2sample] . [at. wt. of Sr87] Sr84 (ug/sample) = . 1 ^ 8 6 ) ^ ^ ] . [ (Sr84/Sr85) c] so, t o t a l Sr(ug/g or ppm) = (Sr88 + Sr87 + Sr86 + Sr84) [at. wt. of Sr84] ug/sample weight of sample d i s s o l v e d (gm) Table XIV. Mass s p e c t r o m e t r i c r e s u l t s . Sample Sr87/Sr86* 2o~(mean) Sr (ppm)** SH-1 0.7070 SH-3 0.7062 SH-6 0.7063 SH-7 0.7062 + 0.0013 1.12 + 0.0004 3.90 + 0.001 4.43 + 0.0003 4.75 * normalized t o Sr88/Sr86 = 8.375 (Sr86/Sr88 = 0.1194). Eimer and Amend SrCO^ standard analyzed by J . Blenkinsop has a value of 0.7082 + 0.0001 (2<r) . ** c o r r e c t e d f o r a blank (reagents without sample) run t h a t y i e l d e d a t o t a l Sr content of 0.50 ug. T h i s v a l u e was the cumulate contamination of : (1) the combination of contents of two d i g e s t i o n bombs ( i . e . the e q u i v a l e n t of 2 gm of sample and accompanying a c i d s ) ; (2) the p a s s i n g o f the s o l u t i o n through 2 molar and 6 molar i o n exchange columns; (3) samples s i t t i n g on h o t - p l a t e s d u r i n g e v a p o r a t i o n processes; (4) f i l a -ment l o a d i n g procedures; and (5) the mass-spectrometer source i t s e l f . by the Trapping Creek rocks, r e f l e c t i n g t h e i r h i g h p l a g i o c l a s e content (see t a b l e XII and appendix I ) . The mass spectrometer r e s u l t s f o r the Shulaps Range samples y i e l d a mean Sr87/Sr86 value of 0.7064 and an average t o t a l Sr c o n c e n t r a t i o n of 3.73 ppm. No s i g n i f i c a n t i n t e r n a l v a r i a t i o n s i n the r a d i o g e n i c s t r o n t i u m d i s t r i b u t i o n are d e t e c t -ed, and no c o r r e l a t i o n to m i n e r a l content can be drawn. The Sr c o n c e n t r a t i o n s as determined by i s o t o p e d i l u t i o n appear i n each case to be about 1 ppm l e s s than the corresponding v a l u e s o b t a i n e d by x-ray f l u o r e s c e n c e a n a l y s i s (compare t a b l e s XII and XIV). E. C o n c l u s i o n s Regarding the O r i g i n of the U l t r a m a f i c Bodies N e i t h e r the Rb/Sr r a t i o s nor the i n i t i a l Sr87/Sr86 valu e s of the Shulaps Range u l t r a m a f i c rocks supply the nec-e s s a r y evidence to allow c a t e g o r i z a t i o n of the magmatic source of t h i s a p p a r e n t l y a l p i n e - t y p e i n t r u s i o n . The i s o t o p i c r a t i o s are c o n s i d e r a b l y lower than the average value of 0.7119 o b t a i n e d f o r world-wide occurrences of a l p i n e - t y p e u l t r a m a f i c i n t r u s i o n s . Rather, they appear to be c l o s e r to the average v a l u e of 0.7057 shown by the c o n c e n t r i c a l l y zoned u l t r a m a f i c plugs (see t a b l e XVII). The g l o b a l averages f o r these two groups roughly c o r r e s -pond to the r a t i o s proposed to r e p r e s e n t the o c e a n i c and cont-i n e n t a l upper mantle systems r e s p e c t i v e l y , as d i s c u s s e d i n chapters VI and V I I . The present-day Rb/Sr ra'tios- of these systems are b e l i e v e d to be 0.09 and 0.03 r e s p e c t i v e l y , as d e t a i l e d i n the computer model presented l a t e r (see t a b l e XXI 48 and f i g u r e 10). The Shulaps Range u l t r a m a f i c body i s c o n s i d e r e d t o be an a l p i n e s e r p e n t i n i t e r e p r e s e n t i n g oceanic l i t h o s p h e r e t e c t -o n i c a l l y emplaced i n the s o l i d s t a t e as suggested as e a r l y as 1963 by DIETZ, but more a c c o r d i n g to the mechanisms proposed by COLEMAN (1971) and a m u l t i t u d e of more r e c e n t students of o p h i o l i t e assemblages. A schematic r e p r e s e n t a t i o n of the ob-d u c t i o n process of emplacement of a l p i n e - t y p e u l t r a m a f i c bodies appears i n f i g u r e 12c. The Twin S i s t e r s Dunite and the C o q u i h a l l a s e r p e n t i n -i t e are both b e l i e v e d t o have a s i m i l a r o r i g i n . The Trapping Creek zoned g a b b r o - p e r i d o t i t e complex, on the other hand, i s more l i k e l y to have o r i g i n a t e d as a hot u l t r a m a f i c i n t r u s i o n (again see f i g u r e 12c), as opposed t o the c o l d t e c t o n i c emplace-ments. However, the Rb-Sr data produced here provide" no a c t u a l evidence to support t h i s h y p o t h e s i s . N e i t h e r c o n f i r m a t i o n nor d i s p u t e of an Upper T r i a s s i c age f o r the Shulaps body, as proposed by LEECH (1953), can be o f f e r e d . V a r i a t i o n s i n the Rb/Sr r a t i o s w i t h i n the u l t r a m a f i c body are not l a r g e enough to a l l o w d e t e r m i n a t i o n of Rb-Sr dates. A K-Ar age d e t e r m i n a t i o n was attempted f o r a g r a n o d i o r i t e sample (BCP-1) of the Blue Creek Porphyry which i n t r u d e s the u l t r a m a f i c mass, but here too the K content of the m i n e r a l separates was not h i g h enough f o r t h i s purpose. 49 P l a t e I. a. Blue Creek area, i n the n o r t h c e n t r a l p a r t of the Shulaps u l t r a m a f i c body. I l l u s t r a t e d i s the t y p i c a l topography of broad U-shaped v a l l e y s s e p a r a t i n g subdued mountains, o f t e n w i t h steep t a l u s s l o p e s . E l e v a t i o n i s about 6000 f t (1830 m) . b. Blue Creek area, Shulaps Range, showing l o c a t i o n of s e rp-e n t i n i t e sample SH-4, a t the;top of the t a l u s s lope seen i n p l a t e l a . c. Lake La Mare area, southeast corner of Shulaps Range. L o c a t i o n of s e r p e n t i n i z e d p e r i d o t i t e sample, SH-9. Foreground shows nature of t y p i c a l outcrop. E l e v a t i o n i s 4500 f t (1370 m). d. S e r p e n t i n i t e shear zone, c h a r a c t e r i s t i c of fault-bounded p e r i p h e r y of the Shulaps u l t r a m a f i c mass. C o l l e c t i o n s i t e of sample SH-11, near Lake La Mare. 50 51 P l a t e I I . a. Hand-specimen of s e r p e n t i n i t e , SH-1. Shows conspicuous b a s t i t e s ( r e l i c t e n s t a t i t e s ) w i t h i n a dark s e r p e n t i n e m a t r i x . Scale marker = 1.0 cm ( f o r every photograph i n p l a t e I I ) . b. Hand-specimen of s e r p e n t i n i z e d h a r z b u r g i t e , SH-3. A very conspicuous checkered appearance, w i t h l a r g e cream-green pyroxene g r a i n s s e t w i t h i n a dark grey s e r p e n t i n e m a t r i x . Weathered r i m c o n s t i t u t e s sample SH-3A. c. Hand-specimen of s e r p e n t i n i t e , SH-4. I l l u s t r a t e s the common enamel-like f a c e s . d. Hand-specimen of s e r p e n t i n i t e , SH-6. A very f i n e - g r a i n e d rock, w i t h subconchoidal f r a c t u r e . e. Hand-specimen of s e r p e n t i n i t e , SH-7. Very t i n y t a l c needles c l e a r l y v i s i b l e , w i t h i n a darker s e r p e n t i n e m a t r i x (see a l s o p l a t e IVa). f . Hand-specimen of Twin S i s t e r s d u n i t e ( s a x o n i t e ) , TSD-1. Extremely f r e s h , e q u i g r a n u l a r yellow-green o l i v i n e . g. Weathered s u r f a c e o f Twin S i s t e r s d u n i t e ( s a x o n i t e ) , TSD-1. Very conspicuous (darker) e n s t a t i t e g r a i n s protrude the l e s s r e s i s t a n t o l i v i n e . h. Hand-specimen o f Twin S i s t e r s s e r p e n t i n i z e d l h e r z o l i t e , TSS-1. Dark green pyroxene c r y s t a l s dominate w i t h i n a s u b s i d -i a r y g r e y - b l a c k s e r p e n t i n i z e d o l i v i n e m a t r i x . 52 53 P l a t e I I I . a. Photomicrograph of s e r p e n t i n i t e , SH-1. C r o s s - p o l a r i z e d l i g h t . Shows a b a s t i t e ( e n s t a t i t e a l t e r e d to a n t i g o r i t e ) g r a i n w i t h i n a mesh of randomly-oriented l i z a r d i t e l a t h s . Tiny v e i n l e t s a t top l e f t of photograph are c h r y s o t i l e . S c a l e , 1:40 [ 0.2 mm ]. i • i b. Photomicrograph of s e r p e n t i n i t e , SH-4. C r o s s - p o l a r i z e d l i g h t . Shows p a r t i a l l y - s e r p e n t i n i z e d ( l i z a r d i t e ) o l i v i n e , e x h i b i t i n g c h a r a c t e r i s t i c " s t a i n e d - g l a s s " t e x t u r e . C r y s t a l a t extreme r i g h t i s a s l i g h t l y a l t e r e d orthopyroxene. c. Photomicrograph of h a r z b u r g i t e , SH-5. C r o s s - p o l a r i z e d l i g h t . O l i v i n e o n l y v e r y s l i g h t l y a l t e r e d (compare with p l a t e I l l b ) . C r y s t a l a t top l e f t i s u n a l t e r e d e n s t a t i t e . P l a t e IV. a. Photomicrograph of s e r p e n t i n i t e , SH-7. C r o s s - p o l a r i z e d l i g h t . T a l c needles, w i t h accompanying c h l o r i t e and minor carbonate, s e t w i t h i n a mesh-like s e r p e n t i n e m a t r i x . S c a l e , 1:40 [ 0.2 mm ]. b. Photomicrograph of s e r p e n t i n i z e d h a r z b u r g i t e , SH-8. C r o s s - p o l a r i z e d l i g h t . E n s t a t i t e g r a i n w i t h r i m of t i n y c l i n o p y r o x e n e (diopside) c r y s t a l s w i t h a ma t r i x of s e r p e n t i n -i z e d o l i v i n e . Compare w i t h SH-1 ( p l a t e I l i a ) where the p y r o -xene i s t o t a l l y s e r p e n t i n i z e d t o b a s t i t e . c. Photomicrograph of Twin S i s t e r s d u n i t e ( s a x o n i t e ) , TSD-1. C r o s s - p o l a r i z e d l i g h t . Large e n s t a t i t e g r a i n shows s l i g h t l y deformed (bent) l a m e l l a e , and has t i n y o l i v i n e i n c l u s i o n s . The anhedral o l i v i n e g r a i n s a re extremely f r e s h , w i t h no s i g n of s e r p e n t i n i z a t i o n whatsoever. 56 57 IV. STRONTIUM ISOTOPE VALUES FOR ROCKS OF VARIOUS COMPOSITION,  ENVIRONMENT AND AGE — EXCLUSIVE OF ULTRAMAFIC ROCKS A b r i e f p r e s e n t a t i o n of the v a r i a t i o n s i n the s t r o n t i u m i s o t o p i c r a t i o s observed f o r v a r i o u s rock types f o l l o w s . Other than i n the case of u l t r a m a f i c r o c k s , d e a l t w i t h i n the next chapter, the i s o t o p i c v a l u e s c i t e d here are not a t a l l intended t o r e p r e s e n t a complete l i t e r a t u r e survey, but r a t h e r j u s t an i n d i c a t i o n of the c h a r a c t e r i s t i c ranges observed f o r the d i f f -e r e n t rock groups. More complete c o m p i l a t i o n s can be found i n FAURE and POWELL (1972). Unless otherwise s t a t e d , a l l Sr87/Sr86 v a l u e s d i s -cussed are i n i t i a l r a t i o s . In s p i t e of the use of the Eimer and Amend SrC0 3 standard (Sr87/Sr86 = 0.7080), s l i g h t v a r i a t -i o ns i n accuracy and p r e c i s i o n o b v i o u s l y e x i s t between meas-urements made a t d i f f e r e n t l a b o r a t o r i e s . A. Stony M e t e o r i t e s : The Primeval R a t i o A long accepted e x t r a p o l a t i o n of the i s o c h r o n d e t e r -mined f o r stony m e t e o r i t e s g i v e s an i n i t i a l Sr87/Sr86 r a t i o of 0.698 + 0.001 and an age of 4.5 by (GAST, 1961; PINSON e t a l , 1965; SHIELDS, 1964). T h i s f i g u r e has been suggested to be i d e n t i c a l w i t h the p r i m o r d i a l e a r t h Sr87/Sr86 r a t i o (GAST, 1960; HEDGE and WALTHALL, 1963). A more r e c e n t , extremely p r e c i s e i n i t i a l r a t i o o b t a i n e d f o r a b a s a l t i c a c h o n d r i t e i s 0.698990 + 0.000047, with an age 58 of 4.55 by (PAPANASTASSIOU and WASSERBURG, 1969). T h i s i s the v a l u e used as the p r i m e v a l r a t i o i n the s t r o n t i u m e v o l -u t i o n a r y model developed l a t e r i n t h i s t h e s i s . HURLEY (196 8a, 1968b) has proposed a present-day r a t i o of 0.7047 f o r the t o t a l crust-mantle system, w h i l e GAST (1960) est i m a t e s a sim-i l a r v a l u e of 0.7045. B. Oceanic B a s a l t s PETERMAN and HEDGE (1971) summarize the v a l u e s o b t a i n e d f o r oceanic b a s a l t i c r o c k s . The range observed i s from 0.7012 to 0.7057. A d i s t i n c t i n c r e a s e i n Sr87/Sr86 i s found going from ocean-ridge t h o l e i i t e s t o i s l a n d t h o l e i i t e s and a l k a l i b a s a l t s , to p o t a s s i c i s l a n d b a s a l t s . T h i s i n c r e a s e corresponds to an i n c r e a s e i n " t h e potassium content of the r o c k s ( f i g u r e 6), as should be expected because of the geochemical coherence of potassium and rubidium. T h i s c o r r e l a t i o n has more s p e c i f i c a l l y been shown f o r b a s a l t s of the P a c i f i c Ocean B a s i n (HEDGE and PETERMAN, 1970). In f a c t , s m a l l but d i s t i n c t d i f f e r e n c e s have been noted between t h o l e i i t i c and a l k a l i b a s a l t s of the Hawaiian I s l a n d s (POWELL e t a l , 1965; HEDGE, 1966; POWELL and DE LONG, 1966). PETERMAN and HEDGE (1971) f u r t h e r p o i n t out t h a t w i t h i n i s l a n d b a s a l t s , a c l e a r t r e n d e x i s t s between the Sr87/Sr86 r a t i o and potassium content, the h i g h e s t s t r o n t i u m v a l u e s being r e p r e s e n t e d by the p o t a s s i c m afic l a v a s of T a h i t i , Gough, T r i s t a n da Cunha, and Samoa ( f i g u r e 6). B-fo 70j erosof 0 7050 0-7040! S " i . 0.7030 0.7020 ® O AD © A . f t 0 © ® ^ A ® ^ A A A 0° ° <? 0 , 0.7010 0.7000' <—' 1 1 -0.10 • 0.40 0.20 0.30 K 2 0 / ( K j O + NajO) KEY' Ocean ridge tholeiites O ; Hawaiian Islands O'• 1' Koolau Series, 2 • Tholeiites on Hawaii, 3 • Waianae Series, 4'Honolulu Series, 5 • Kula Series, 6 'A lka l ine Series on Maui, 7 'Haulalai Series; Easter 0 ; Guadalupe * ; Galapagos © ; Eniwetok © ; Tahiti A ; Samoa ®; Gough O; St. Helena tSrj Tristan da Cunha O; Iceland Reunion ® ; Ascension O 0.50 F i g u r e 6. V a r i a t i o n of Sr87/Sr86 and K 20/(K 2o'+ Na 20) i n ocea n i c b a s a l t i c r o c k s . From PETERMAN and HEDGE, 1971. 60 C. C o n t i n e n t a l B a s a l t s I n i t i a l Sr87/Sr86 r a t i o s o b t a i n e d f o r c o n t i n e n t a l b a s a l t s g e n e r a l l y f a l l w i t h i n the range 0.703 to 0.706 (HEDGE and WALTHALL, 1963; FAURE and HURLEY, 1963 — v a l u e s c o r r e c t e d to the Eimer and Amend standard; HURLEY, 1967; and LEEMAN, 1970). C o n s i d e r a b l y h i g h e r v a l u e s and l a r g e r v a r i a t i o n s are f r e q u e n t l y observed, but these are g e n e r a l l y a t t r i b u t e d t o contamination or the e f f e c t s of metamorphism. While i t does appear l i k e l y t h a t these v a r i a t i o n s cannot always be e x p l a i n e d by such p r o c e s s e s , the number of h i g h - p r e c i s i o n v a l u e s i s not s u f f i c i e n t to enable d e l i n e a t i o n of the v a r i a t i o n s , and poss-i b i l i t i e s of a heterogeneous source (eg. HEDGE and LIPMAN, 1972). D. I s l a n d Arc and A n d e s i t i c V o l c a n i c s PUSHKAR (1968) r e p o r t s i n i t i a l Sr87/Sr86 r a t i o s f o r s e v e r a l n o n - i g n i m b r i t e c a l c - a l k a l i n e v o l c a n i c rocks from Saipan, C e n t r a l America, and the Le s s e r A n t i l l e s i n the range 0.703 t o 0.705. A more d e t a i l e d study o f th r e e b a s a l t - a n d e s i t e c e n t r e s along the L e s s e r A n t i l l e s a r c by HEDGE and LEWIS (1971) y i e l d e d v a l u e s of 0.7038 f o r Mt. Misery on the i s l a n d o f St. K i t t s , 0.7041 f o r S o n f r i e r e on the i s l a n d of St. V i n c e n t , and 0.7053 f o r C a r r i a c o u , an i s l a n d of The Grenadines. A l l the r a t i o s w i t h i n each i n d i v i d u a l c e n t r e were the same, i n s i d e the a n a l -y t i c a l u n c e r t a i n t y of + 0.0002. PETERMAN e t a l (1970) ob t a i n e d v a l u e s r a n g i n g from 61 0.7030 t o 0.7043 f o r Quaternary l a v a s from the Cascade Range of n o r t h e r n C a l i f o r n i a which vary i n composition from o l i v i n e b a s a l t t o r h y o l i t e . In a geochemical study of the Taupo V o l c a n i c Zone, LEWIS (1968) found the s t r o n t i u m r a t i o s t o va r y from 0.7047 f o r b a s a l t t o 0.7066 f o r r h y o l i t e . In a d d i t i o n to the s t r o n t i u m i s o t o p i c data, p e t r o g r a p h i c s t u d i e s and t r a c e element d i s t r i b u t i o n s determined by Lewis support h i s h y p o t h e s i s t h a t these v o l c a n i c s belong t o a continuous chemical sequence ( b a s a l t - a n d e s i t e - d a c i t e - c a l c a l k a l i n e - r h y o l i t e ) having a s u b s i a l i c source. E. A n o r t h o s i t e s , C a r b o n a t i t e s and A l k a l i n e I n t r u s i v e s Because of t h e i r p e r s i s t e n t l y c o n t r o v e r s i a l o r i g i n , s e v e r a l s t r o n t i u m i s o t o p i c s t u d i e s have been made on these P l u t o n i c r o c k s . HEATH (1967) measured the Sr87/Sr86 r a t i o s of a n o r t h o s i t e s c o l l e c t e d from throughout North America and Norway. He o b t a i n e d a very c l o s e grouping of low valu e s from 0.703 to 0.706 f o r a t o t a l o f more than f i f t y samples, e l i m i n -a t i n g the p o s s i b i l i t y of a n o r t h o s i t e s b e i n g formed by meta-morphism or a n a t e x i s of sediments ( a l l these processes normally being r e f l e c t e d by Sr87/Sr86 r a t i o s ^ 0.710). The o r i g i n o f c a r b o n a t i t e s has s i m i l a r l y been a c o n t r o -v e r s i a l s u b j e c t , the main p o s s i b i l i t i e s f o r i t being (1) as x e n o l i t h s of limestone; (2) the r e s u l t of p a r t i a l m e l t i n g o f s i a l i c m a t e r i a l ; and (3) o r i g i n a t i n g i n the same r e g i o n as b a s a l t s . Sr87/Sr86 v a l u e s ranging from 0.7016 to 0.7057 (aver-aging 0.7035) f o r c a r b o n a t i t e s from worldwide l o c a l i t i e s v i r t -u a l l y confirm, a source r e g i o n s i m i l a r to b a s a l t (POWELL, 1966). Another important q u e s t i o n i s t h a t of c a r b o n a t i t e s being comagmatic w i t h the a l k a l i n e i n t r u s i v e s they are o f t e n found w i t h . The a l k a l i n e rocks a t Oka, Quebec (the Monteregion P r o v i n c e ) , Magnet Cove, Arkansas and Iron H i l l , Colorado are a l l found t o have s t r o n t i u m r a t i o s i d e n t i c a l w i t h t h a t of the c a r b o n a t i t e s they are a s s o c i a t e d w i t h , i n d i c a t i n g s i m i l a r o r i g i n s i n each case (POWELL, 196 6; see a l s o FAURE and HURLEY, 1963). E. G r a n i t i c and Sedimentary Rocks Compared wi t h b a s a l t s , g r a n i t e s have a much g r e a t e r range of i n i t i a l Sr87/Sr86 r a t i o s , from va l u e s as low as i n b a s a l t s up to 0.730 and higher; most r a t i o s , however, are l e s s than 0.710 (HEDGE and WALTHALL, 1963; HURLEY e t a l , 1965; FAIRBAIRN e t a l , 1964a, 1964b). With the e x c e p t i o n of l i m e s t o n e s , sedimentary rocks have hi g h Rb/Sr r a t i o s and hence develop h i g h Sr87/Sr86 r a t i o s w i t h time (HEATH, 1967). While limestones have i n i t i a l i s o t o p i c v a l u e s corresponding to sea-water a t t h e i r time of p r e c i p i t a t i o n , i t has been found t h a t the s t r o n t i u m i n the d e t r i t a l component of s h a l e s does not e q u i l i b r a t e w i t h sea-water, and so the Sr87/ Sr86 r a t i o s i n newly d e p o s i t e d s h a l e s range both upward and downward from the r a t i o f o r sea-water (present-day v a l u e of 0.709) (DASCH e t a l , 1966). Reported v a l u e s f o r s h a l e s v a r y 63 from 0.710 to 0.720 (COMPSTON and PIDGEON, 1962; FAURE and HURLEY, 1963; WHITNEY and HURLEY, 1964). Ba"sed on measurements on fresh-water c a l c a r e o u s s h a l e s , FAURE e t a l (1963) estimate the Sr87/Sr86 r a t i o i n the Canadian S h i e l d as about 0.710. G. Summary of Recorded I s o t o p i c V a r i a t i o n s f o r Non-Ultramafic Sr87/Sr86 r a t i o s o b t a i n e d f o r the v a r i o u s n o n - u l t r a m a f i c rock types i s shown i n t a b l e XV. D i s c u s s i o n w i t h r e s p e c t to the i n t e r p r e t a t i o n s o f these i s o t o p i c v a r i a t i o n s , and t h e i r p e t r o -Table XV. Summary of reco r d e d s t r o n t i u m i s o t o p i c v a r i a t i o n s f o r n o n - u l t r a m a f i c r o c k s . Rocks A summary of the c h a r a c t e r i s t i c ranges o f i n i t i a l g e n e t i c i m p l i c a t i o n s , appear i n chapter VI. Rock type I n i t i a l Sr87/Sr86 range stony m e t e o r i t e s 0.699 t h o l e i i t i c b a s a l t s , and some c a r b o n a t i t e s 0.701 - 0.703 a l k a l i b a s a l t s , most c o n t i n e n t a l b a s a l t s , i s l a n d a r c and a n d e s i t i c v o l c a n i c s , a n o r t h o s i t e s , most carbon-a t i t e s and a l k a l i n e i n t r u s i v e s 0.703 - 0.706 g r a n i t i c and sedimentary rocks 0.701 - 0.730 + 64 V. COMPILATION OF ALL REPORTED RUBIDIUM AND STRONTIUM CONCENTRATIONS AND STRONTIUM ISOTOPE DATA FOR ALL TYPES  OF OCCURRENCES OF ULTRAMAFIC AND RELATED ROCKS Rubidium and s t r o n t i u m data f o r a l l types of o c c u r r -ences of u l t r a m a f i c and r e l a t e d rocks have been compiled f o r t h i s t h e s i s by a survey c o v e r i n g l i t e r a t u r e t i l l mid-1974. The importance of t h i s v e r y comprehensive d a t a - c o m p i l a t i o n w i l l be apparent i n the d i s c u s s i o n s t h a t f o l l o w i n the next two c h a p t e r s . The u l t r a m a f i c rocks are c o n s i d e r e d w i t h i n s i x d i s t -i n c t environments, the groupings being based on p e t r o l o g i c a l and i s o t o p i c c r i t e r i a . The d i v i s i o n s are as f o l l o w s : (A) oceanic u l t r a m a f i c rocks; (B) a l p i n e - t y p e i n t r u s i o n s ; (C) c o n c e n t r i c a l l y - z o n e d bodies; (D) nodules i n a l k a l i b a s a l t s ; (E) i n c l u s i o n s i n k i m b e r l i t e s ; and (F) l a y e r e d u l t r a m a f i c zones i n major i n t r u s i o n s . The c o m p i l a t i o n i s presented i n t a b u l a r form ( t a b l e XVI). For each sample, the t a b l e i n c l u d e s whenever a v a i l a b l e : (1) the l o c a t i o n and g e o l o g i c a l s e t t i n g of the u l t r a m a f i c body; (2) the exact type of rock or m i n e r a l separate, (3) the Rb and Sr c o n c e n t r a t i o n s and Rb/Sr r a t i o , and the Sr87/Sr86 i s o t o p i c r a t i o ; (4) the source r e f e r e n c e ; (5) the p r e c i s i o n accompanying the data and the value o b t a i n e d by the l a b o r a t o r y f o r the Eimer and Amend standard; and f i n a l l y (6) any p e r t i n e n t a d d i t i o n a l notes on the i s o t o p i c data and g e o l o g i c a l r e l a t i o n -s h i p s . 65 A summary of the data appears i n t a b l e XVII. The va l u e s f a l l i n t o a t l e a s t two d i s t i n c t groups : a s e t of h i g h r a t i o s f o r o c e a n i c u l t r a m a f i c s and a l p i n e - t y p e i n t r u s i o n s ; and d i s t i n c t l y lower v a l u e s f o r the u l t r a m a f i c rocks from concent-r i c a l l y zoned bo d i e s , nodules i n b a s a l t s , and the l a y e r e d zones of major i n t r u s i v e complexes. The u l t r a m a f i c i n c l u s i o n s i n k i m b e r l i t e s occupy a somewhat i n t e r m e d i a t e numerical p o s i t i o n . Table XVI. Co m p i l a t i o n o f a l l r e p o r t e d rubidium and s t r o n t i u m c o n c e n t r a t i o n s and s t r o n t i u m i s o t o p e data and r e l a t e d i n f o rm-a t i o n f o r a l l types of occurrences of u l t r a m a f i c and r e l a t e d r o c k s . Pages 66 to 9 9. T O P A T T O N A N D ULTRAMAFIC WHOLE ROCKS , .. ^ ^ ° C A ™ N AND MINERAL SEPARATES, , R B , , S R , RB/SR S IIL REF GEOLOGICAL SETTING RELATED ROCKS ( p p m ) ( p p m ) S R 8 6 A. OCEANIC ULTRAMAFIC ROCKS (DREDGED, CORED, AND OCEANIC ISLANDS) Oceanic p e r i d o t i t e s (and a s s o c i a t e d mafics) from the M i d - A t l a n t i c Ridge where i n t e r s e c t e d by the Chain, Romanche and St. Paul f r a c t u r e d s e c t i o n s of the r i d g e between 6° and 8° N. The u l t r a m a f i c rocks are mainly harzbur-g i t e s , but l h e r z o l i t e s , d u n i t e s , and p l a g i o c l a s e -p e r i d o t i t e s are a l s o pres-ent — however, exact c l a s s i f i c a t i o n of each p e r i d o t i t e i s not g i v e n . V a r y i n g degrees of s e r p -e n t i n i z a t i o n observed. p e r i d o t i t e St. Peter and Paul Rocks p e r i d o t i t e s ( c e n t r a l A t l a n t i c ) M y l o t i n i z e d p e r i d o t i t e s from S t . Paul Rocks b a s a l t s and gabbros amphibolite i i nepheline gabbro II p e r i d o t i t e II II p e r i d o t i t e s (4) 0.55 11.45 0.048 0.7069 0.55 16.9 0.030 0.7063 0.49 9.6 0.051 0.7227 0. 22 64.7 0.003 0.7067 <0.1 6.3 <0.016 0.7114 0.77 7.6 0.101 0.7076 2.28 18.5 0.123 0.7111 0.48 7.5 0.064 0.7089 0.10 4.1 0.024 0.7138 6.4 0.7113 0.50 103 0.005 0.7022 6.4 122 0.052 0.7035 1.7 125 0.014 0.7020 2 217 0.009 0.7041 0.74 158 0.005 0.7026 10.8 214 0.050 0.7028 0.67 128 0.005 0.7042 0.19 147 0.001 0.7052 62 281 0.221 0.7038 54 276 0.196 0.7026 4.2 0.73 5.75 0.7034 1.7 8.2 0.207 0.7067 1.06 51.4 0.201 0.7042 .25 to 8.0 to 0.016 t o 0.703 to 1.70 90 0.042 0.705 0.40 0.7085 REFERENCE PRECISION AND VALUE FOR E&A STANDARD OCEANIC ULTRAMAFIC ROCKS (DREDGED B o n a t t i e t a l , Rb: + 2 % 1 9 7 0 Sr: + 1.5% Sr87/Sr86: + 0.0015 B o n a t t i e t al, as i n r e f . 1 1970 Hart, 1964 not r e p o r t e d ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS CORED, AND OCEANIC ISLANDS) - p e r i d o t i t e s : from the deepest dredge hauls from the f r a c t u r e zones; some a l s o obtained from the w a l l of the c e n t r a l r i f t v a l l e y i n an u n f r a c t u r e d p o r t i o n of the r i d g e . Rocks range from completely f r e s h to t o t a l l y s e r p e n t i n i z e d . Most of the rocks e x h i b i t s l i c k e n s i d e d s u r f a c e s , s t r e s s f a b r i c s and/or c a t a -c l a s t i c s t r u c t u r e s . - gabbroic r o c k s : from the deeper dredge hauls w i t h i n the f r a c t u r e zones. - b a s a l t s and n o r i t e s : dominate the upper s l o p e s of the f r a c t u r e zones and of the w a l l s of the cen-t r a l r i f t v a l l e y s . Most are low-potassium o l i v i n e t h o l e i i t e s ; however, a l k a l i b a s a l t s a l s o r e c o v e r e d . - amphibolites and less-metamorphosed e q u i v a l e n t s : found mainly a t i n t e r m e d i a t e l e v e l s i n the f r a c t u r e zones and towards the base of the w a l l s of the cen-t r a l r i f t v a l l e y . - summarizing, approximate s t r a t i g r a p h y : 1-2 km of b a s a l t s gradedownward i n t o gabbro and a metamorphic s e r i e s i n c l u d i n g greenschists and a m p h i b o l i t e s . The base of the exposed s e c t i o n s c o n s i s t s of p e r i d o t i t e s which were observed to outcrop f o r a t h i c k n e s s of a t l e a s t 3.5 km i n one area. - the p e t r o l o g y of St. Peter and St. Paul massif sugg-e s t s t h a t s e v e r a l types of p e r i d o t i t e s are p r e s e n t , and t h a t a t l e a s t one type could p o s s i b l y be a parent m a t e r i a l f o r the b a s a l t . - p e r i d o t i t e s f a l l i n t o two d i s t i n c t groups of Rb/Sr and Sr87/Sr86 r a t i o s . ULTRAMAFIC WHOLE ROCKS g 7 / CSSSTW* AND MINERAL SEPARATES, R B , , S R . RB/SR cVQa REF GEOLOGICAL SETTING RELATED ROCKS ( p p m ) ( p p I t l ) S R 8 6 S t . Paul Rocks p e r i d o t i t e mylonite P e r i d o t i t e m y lonites from St. Paul Rocks S e r p e n t i n i t e from the AMSOC core hole near Mayaguez, Puerto Rico M i n e r a l separates from a l h e r z o l i t e sample dredged from a c r o s s - f r a c t u r e zone about 17°S on the Mid-A t l a n t i c Ridge. A l s o whole-rock and m i n e r a l separates o f b a s a l t from the same l o c a t i o n Fantoche Mine, N.W. c o a s t of New Ca l e d o n i a Drumbea Creek, New Caledonia p e r i d o t i t e mylonite p e r i d o t i t e mylonite s e r p e n t i n i z e d d i o p s i d e h a r z b u r g i t e a t depths of 174, 120, and 304m, resp, l h e r z o l i t e separates : p l a g i o c l a s e garnet c l i n o p y r o x e n e b a s a l t s p e r i d o t i t e d u n i t e d u n i t e 0.341 11.8 0.029 0.7046 4 0.90 34.4 0.026 0.7051 5 0. 250 9.06 0.028 - 0.7043 0.321 8.04 0.040 0.7083 0.346 10.08 0.034 0.079 14.62 0.005 0.7046 0.195 24.2 0.008 0.7044 0.376 10.06 0.037 0.7052 2.65 16.7 0.159 0.7042 3.36 40. 5 0.083 0.7047 0.048 6.85 0.007 0.7053 6 0.041 4.92 0.008 0.7058 0. 298 7.71 0.039 0.7067 7 0. 45 700 0.0006 0.70895 0. 22 975 0.0002 0.70887 0. 55 8.9 0.062 0.7067 0.7023 to 0.7051 8.35 13.7 0.609 0.7066 8 0.073 0.523 0.15 0.7079 0.147 0.499 0. 295 0.7127 Papua, New Guinea duni t e 0.302 6.28 0 . 0 4 8 0 . 7 0 7 8 9 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 4. Hurley e t a l , 1964; and Roe, 19 64 5. Melson et. a l , 1972 Sr87/Sr86: + 0.004; va l u e s c o r r e c t e d to E&A = 0.7080 Sr87/Sr86: + 0.001 (2o-) E&A = 0.7080 6. Hurley e t a l , 1964; and Roe, 1964 7. Hart, 1972a, and 1972b as i n r e f . 4 Sr87/Sr86: + 0.00015 to + 0.00006 (2<r) r e l a t i v e t o E&A = 0.70800 8. Roe, 1964 as i n r e f . 4 9. Stueber and Sr87/Sr86: + 0.001 Murthy, 1966 E & A : 0.7081 + 0.001 (2o-) ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS Sr i s o t o p e s p a r t of a major study o f the p e d o -genesis, r a d i o m e t r i c ages, and i m p l i c a t i o n s on sea-f l o o r spreading, of the St. Paul's Rocks. tex t u r e of l h e r z o l i t e suggests s t r o n g r e c r y s t a l l i z a t i o n ; no evidence f o r a cumulate o r i g i n . Fantoche Mine, p e r i d o t i t e : very f r e s h ( l e s s than 10% s e r p e n t i n i z e d ) , 60% o l i v i n e , 20% pyroxene, minor c a l c i c p l a g i o c l a s e , accessory chromite. Dunite: 60% s e r p e n t i n i z e d , with a c c e s s o r y c h l o r i t e Dumbee Creek, d u n i t e : 30% s e r p e n t i n i z e d , 10% pyro-xene with accessory chromite. Dun Mountain d u n i t e : extremely pure o l i v i n e ; Sr87/ Sr86 measurement not p o s s i b l e due t o extremely low Sr c o n c e n t r a t i o n . LOCATION AND ^ n ^ ^ r ^ SSLSSSf GEOLOGICAL SETTING ^ J , 1 ^ ^ ^ ^ * ' AND RELATED ROCKS B. ALPINE-TYPE ULTRAMAFIC INTRUSIONS Twin S i s t e r s , Washington Seneca, Oregon Balsam Gap, North C a r o l i n a Lowe11, Vermont Black Lake, Quebec du n i t e p y r o x e n i t e d u n i t e s e r p e n t i n i t e p e r i d o t i t e Dun Mountain, New Zealand d u n i t e K a l g o o r l i e , A u s t r a l i a C a n t w e l l , A l a s k a Mt. A l b e r t , Quebec Addie-Webster, North C a r o l i n a B e t t ' s Cove, Newfoundland S i o r a e s s u i t , Greenland Konya, Turkey Almklovdalen, Norway ' Dun Mountain, New Zealand Shikoku, Japan s e r p e n t i n i t e d u n i t e p e r i d o t i t e d u n i t e s e r p e n t i n i t e d u n i t e d u n i t e d u n i t e d u n i t e d u n i t e RB (ppm). SR (ppm) RB/SR SR87/ SR86 0.050 0.142 0.35 0.110 8.88 0.013 0.7151 0.079 0.803 0.097 0.7125 0.201 1.46 0.138 0.7104 0.380 0.307 0.787 3.60 0.484 0.089 0.7149 0.7096 0.091 0.314 0. 287 0.284 6.89 0.041 0.7152 0.072 2.32 0.031 0.7101 0.158 5.52 0.029 0.7109 0.077 2.99 0.026 0.7156 1.036 8.36 0.124 0.7113 2.42 14.7 0.165 0.7290 0.140 4.28 0.033 0.7272 0.131 9.89 0.013 0.7078 0.111 4.39 0.025 . 0.7091 0.099 8.10 0.012 0.7063 REF ° PRECISION AND VALUE ADDITIONAL NOTES ON ISOTOPIC DATA FOR E&A STANDARD AND GEOLOGICAL RELATIONSHIPS B. ALPINE-TYPE ULTRAMAFIC INTRUSIONS 10. Roe, 1964 as i n r e f . 4 - Twin S i s t e r s : very pure du n i t e with o n l y minor s e r p -e n t i n i z a t i o n and accessory chromite; i s o t o p i c r a t i o indeterminable due to extremely low Sr c o n c e n t r a t i o n . - Seneca: dominantly pyroxene with minor amphibole; 30% s e r p e n t i n e a l t e r a t i o n . - Balsam Gap: few percent c h l o r i t e , v e r m i c u l i t e , and chromite w i t h i n the dominant o l i v i n e . - L o w e l l : completely s e r p e n t i n i z e d , w i t h a c c e s s o r y chromite. - Black Lake: f i r s t p e r i d o t i t e has 50% o l i v i n e , 15% pyroxene, 5% f e l d s p a r , accessory chromite, and 30% s e r p e n t i n e ; the o l i v i n e i s badly crushed and v e i n e d w i t h s e r p e n t i n e . Second p e r i d o t i t e composed o f s e r p e n t i n e - v e i n e d o l i v i n e (80%) and a n t i g o r i t e f l a k e s , with 10% pyroxene rimming o l i v i n e g r a i n s , and accessory chromite. 11. Stueber and as i n r e f . 9 - authors contend t h a t the Newfoundland s e r p e n t i n i t e Murthy, 1966 and the Greenland d u n i t e a p p a r e n t l y d i d not remain c l o s e d systems. - B e t t ' s Cove s e r p e n t i n i t e has a high t a l c c ontent, and was near the sheared c o n t a c t w i t h the country rock. - S i o r a r s s u i t dunite was subjected to g r a n u l i t e f a c i e s r e g i o n a l metamorphism and has a metamorphic a u r e o l e , with p h l o g o p i t e observed i n t h i n - s e c t i o n . LOCATION AND GEOLOGICAL SETTING F i v e c l o s e l y r e l a t e d u l t r a m a f i c i n t r u s i o n s i n western North C a r o l i n a : Balsam Gap (BG), Dark Ridge (DR), Addie-Webster (AW), Buck Creek (BC), and Day Book (DB). Both whole-rock and m i n e r a l separate analyses U.S.G.S. standards DTS-1 (Twin S i s t e r s Dunite, Washington) and PCC-1 (stream boulders from the Cazadero u l t r a m a f i c mass, Sonoma County, C a l i f o r n i a ) ULTRAMAFIC WHOLE ROCKS AND MINERAL SEPARATES, AND RELATED ROCKS AW p y r o x e n i t e e n s t a t i t e d i o p s i d e AW p e r i d o t i t e o l i v i n e pyroxenes DR p e r i d o t i t e o l i v i n e e n s t a t i t e d i o p s i d e BG d u n i t e s e r p e n t i n i t e DB d u n i t e BC d u n i t e " u l t r a m a f i c rock" DTS-1, duni t e PCC-1, p e r i d o t i t e U l t r a m a f i c rocks from Burro Mountain, C a l i f o r n i a . P a r t of the F r a n c i s c a n o p h i o l i t e b e l t (ppm) (ppm) R B / S R S RSR86 R E F 0. 122 5.27 0.023 0. 715 0. 130 0. 213 0.610 0. 125 9.05 0.014 0. 7090 0. 048 2.06 0.023 0. 7109 0. 019 0.391 0.049 0. 083 6.83 0.012 0. 7087 0. 222 1.05 0.211 0. 7241 0. 085 0.174 0.491 0. 7238 0. 257 0.494 0.520 0. 7243 0. 999 0.503 0.198 0. 7233 0. 034 0.406 0.084 0. 7175 0. 054 1.25 0.043 0. 7177 0. 013 0.126 0.103 0. 084 5.17 0.016 0. 7067 12 0.7045 13 0.057 0.055 0.31 0.36 0.184 0.153 0.7147 14 0.7109 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 12. Stueber, Sr87/Sr86: + 0.001 1967 and Stueber, 1969 13. Davis and Sr87/Sr86 r a t i o i s an T i l t o n , 1973 i n i t i a l r a t i o , c o r r -e c t e d f o r an age of 1,100 my + 100 my 14. Pankhurst Sr87/Sr86: and O'Nions, DTS-1: + 0.0004 1973 PCC-1: + 0.0008 Co n c e n t r a t i o n s of Rb and Sr extremely p r e -c i s e l y determined by i s o t o p e d i l u t i o n ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS d i o p s i d e g e n e r a l l y has an order of magnitude more Sr than e i t h e r e n s t a t i t e or o l i v i n e ; t h i s f o l l o w s from the f a c t t h a t diopdide i s the only m i n e r a l with s i g n i f i c a n t Ca content ( f o r which Sr s u b s t i t u t e s ) . from the Balsam Gap i n t r u s i o n , a s e r p e n t i n i t e con-s i s t i n g l a r g e l y of s e r p e n t i n e , t a l c and c h l o r i t e was found to have an i d e n t i c a l s t r o n t i u m i s o t o p i c composition as an a s s o c i a t e d dunite which appears to be pure o l i v i n e i n t h i n - s e c t i o n , the o n l y p o s s i b l e suggestion as t o a secondary o r i g i n of r a d i o g e n i c s t r o n t i u m would be r e l a t e d t o a r e g i o n a l metamorphism about 350 my ago which w i t -nessed the i n t r u s i o n of pegmatites i n t o the u l t r a -mafics and country rock; however, no r e a l evidence a t a l l f o r t h i s source of contamination i s p r e s e n t . K/Rb r a t i o s a l s o s t u d i e d . In g e n e r a l , low r a t i o s obtained, i n the range 67 - 754. However, no d i s t -i n c t c o r r e l a t i o n between K/Rb and Rb/Sr or Sr87/ Sr86 data. very p r e c i s e a n a l y t i c a l work. The o n l y l a b o r a t o r y able to determine the Sr87/Sr86 r a t i o s f o r these low-Sr standard rocks. DTS-1: 99% o l i v i n e , minor o r t h o - and c l i n o - p y r o x e n e , disseminated chromite and t r a c e amphibole. PCC-1: 58% o l i v i n e , 9% orthopyroxene, 32% mesh-s t r u c t u r e serpentine replacement, t r a c e s of chromite secondary magnetite, and t a l c and carbonate m a t e r i a l ULTRAMAFIC WHOLE ROCKS , r ^ ° C A ™ N AND AND MINERAL SEPARATES, , R B . , S R , RB/SR SR*Z' REF GEOLOGICAL SETTING RELATED ROCKS (P p I t l ) ( P p m ) S R 8 6 Ophiolite.complexes a t Canyon Mountain, Oregon and Red Mountain, C a l i f -o r n i a c l i n o p y r o x e n e from pyrox-e n i t e s i n the u l t r a m a f i c complexes Canyon Mtn. gabbro, a l b i t e g r a n i t e and keratophyre hornblende and/or p l a g -i o c l a s e from the gabbro and cumulus p e r i d o t i t e i n the gabbro complex a t Red Mtn. Red Mtn. keratophyre >0.708 15 0.7031 to 0.7044 0.7030 to 0.7041 0.7052 Shulaps Range u l t r a m a f i c body, c e n t r a l south-western B r i t i s h Columbia s e r p e n t i n i t e 0.1 s e r p e n t i n i z e d harzburgiteO.2 s e r p e n t i n i t e II s e r p e n t i n i t e s and s e r p e n t i n i z e d h a r z b u r g i t e s (7) 0, 0, <0, to 3 3.5 5.5 6.0 6.3 2.3 to 5.7 0.03 0.04 0.03 0.06 <0.02 to 0.09 0.7070 0.7062 0.7063 0.7062 16 C o q u i h a l l a s e r p e n t i n i t e b e l t , south c e n t r a l B r i t i s h Columbia s e r p e n t i n i t e <0.1 5.4 <0.02 Twin S i s t e r s Dunite, Washington. Dunite from the core o f the body; s e r p e n t i n i t e from the p e r i p h e r y d u n i t e (saxonite) 0.1 s e r p e n t i n i z e d l h e r z o l i t e 0.3 0.2 2.7 15.3 13.7 0.04 0.02 0.02 REFERENCE PRECISION AND VALUE FOR E&A STANDARD Lanphere, not r e p o r t e d 1973 A thaide, Sr87/Sr86: {2a-) 1975 X * / D SH-1: + 0.0013 SH-3: + 0.0004 SH-6: + 0.001 SH-7: + 0.0003 E&A: 0.7082 + 0.0001 (2a-) ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS Sr i s o t o p i c r e l a t i o n s suggest t h a t the u l t r a m a f i c complexes of both l o c a l i t i e s have a d i f f e r e n t h i s t -ory from the o v e r l y i n g p a r t s of these o p h i o l i t e s . Thus, the u l t r a m a f i c complexes are regarded as blo c k s of mantle m a t e r i a l independant i n o r i g i n from the o v e r l y i n g gabbroic and v o l c a n i c r o c k s . Shulaps Range u l t r a m a f i c rocks are a l l h i g h l y s e r p e n t i n i z e d . Modes: SH-1: 95 serp e n t i n e (70 l i z a r d i t e , 5 c h r y s o t i l e , 20 b a s t i t e ) , t r a c e c h l o r i t e , 3 magnetite. SH-3: t r a c e o l i v i n e , 20 e n s t a t i t e , 10 d i o p s i d e , 69 s e r p e n t i n e (50 l i z a r d i t e , 5 c h r y s o t i l e , 5 b a s t i t e ) , t r a c e b r u c i t e (?), 10 magnetite. SH-6: 60 serp e n t i n e (50 l i z a r d i t e , 10 c h r y s o t i l e , b a s t i t e ( ? ) ) , 40 magnetite. SH-7: 45 serpentine (45 l i z a r d i t e , c h r y s o t i l e ( ? ) ) , 5 c h l o r i t e , 30 t a l c , t r a c e magnesite, t r a c e b r u c -i t e , 20 chromite ( a l t e r i n g t o mag n e t i t e ) . C o q u i h a l l a sample i s t o t a l l y s e r p e n t i n i z e d . Twin S i s t e r s d u n i t e (saxonite) i s extremely f r e s h . I t s mode: 85 o l i v i n e , 14 e n s t a t i t e , 1 magnetite. Mode f o r the s e r p e n t i n i z e d l h e r z o l i t e , from the pe r i p h e r y of the body: 5 o l i v i n e , 20 e n s t a t i t e , 60 d i o p s i d e , 10 s e r p e n t i n e ( l i z a r d i t e + a n t i g o r i t e ( ? ) ) , 5 magnetite. LOCATION AND ULTRAMAFIC WHOLE ROCKS _ n ^ ™ T I O N AND AND MINERAL SEPARATES, , R B . , , RB/SR clC REF GEOLOGICAL SETTING RELATED ROCKS ( p p m ) ( p p m ) S R 8 6 A zoned o l i v i n e - c h l o r i t e -t r e m o l i t e v e i n w i t h i n a du n i t e l e n s i n the core zone of the Norwegian Caledonides — Ba s a l Gneiss r e g i o n , southern Norway (u n c e r t a i n t h a t the u l t r a -m a f ic rocks f a l l i n the category of a l p i n e - t y p e i n t r u s i o n s ) u l t r a m a f i c s eparates: d i o p s i d e 0. 008 to 23.6 to 0. 7012 0.046 112 to 0.7029 e n s t a t i t e 0. 002 to 0.13 to 0. 7026 0.005 0.42 to 0.7047 garnet 0. 001 to 0.05 to 0. 7033 0.013 1.1 to 0.7058 v e i n (whole) 0. 7075 a c t i n o l i t e 0. 7077 o l i v i n e 0. 7089 to 0.7093 surrounding c r u s t a l 0. 711 rocks C. CONCENTRICALLY-ZONED ULTRAMAFIC BODIES 17 N i z h n i T a g i l (dunite) d u n i t e and Berezovo ( s e r p e n t i n i t e ) , U r a l s , Russia s e r p e n t i n i t e 0.094 0.083 4.84 0.019 0.914 0.091 0.7087 18 0.7077 Tulameen complex, southern d u n i t e B r i t i s h Columbia 0.130 10.2 0.013 0.7103 19 T i n a q u i l l o , Venezuela p e r i d o t i t e 0.093 3.89 0.024 0.7084 Trapping Creek gabbro-p e r i d o t i t e complex, south-c e n t r a l B r i t i s h Columbia o l i v i n e gabbro 6.1 173.3 0.02 hornblende d i o r i t e 1.3 552.7 0.002 20 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 17. Brueckner, 1973 not r e p o r t e d C. CONCENTRICALLY-ZONED ULTRAMAFIC BODIES 18. Roe, 1964 as i n r e f . 4 19. Stueber and Murthy, 196 6 20. A t h a i d e , 1975 as i n r e f . 9 Rb: +0.5 ppm Sr: + 0.5 ppm ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS the o l i v i n e - c h l o r i t e - t r e m o l i t e v e i n g i v e s a c h l o r i t e -whole rock age of 408 my. supporting g e o l o g i c a l evidence suggests t h a t the v e i n formed i n f r a c t u r e s by r e a c t i o n of the u l t r a -mafic rock with hydrous, c a t i o n - b e a r i n g s o l u t i o n s emanating from the country rocks d u r i n g Caledonian metamorphism. Sr87/Sr86 r a t i o s i n d i c a t e t h a t the v e i n f l u i d s con-t a i n e d s t r o n t i u m with the ambient Sr87/Sr86 r a t i o of the surrounding c r u s t a l rocks. however, the'low Rb and Sr contents o f the m i n e r a l separates of the u l t r a m a f i c lens suggests contam-i n a t i o n by the e n c l o s i n g rocks as an u n l i k e l y poss-i b i l i t y . d u n i t e : 40% s e r p e n t i n i z e d , with a c c e s s o r y chromite. s e r p e n t i n i t e : t o t a l l y s e r p e n t i n i z e d rock, w i t h accessory chromite. o l i v i n e gabbro mode: 55 o l i v i n e , 2 e n s t a t i t e , 5 se r p e n t i n e , 20 hornblende, 10 p l a g i o c l a s e (30% of which has a l t e r e d t o z e o l i t e ) , 5 b i o t i t e , t r a c e p h l o g o p i t e , t r a c e carbonate, 2 p y r r h o t i t e . hornblende d i o r i t e mode: 75 p l a g i o c l a s e ( a n o r t h i t e , 10% o f which has a l t e r e d t o z e o l i t e ) , 20 hornblende, 2 orthopyrdxene; 1 clinopyroxene, 2 s u l p h i d e ( p y r r h o t i t e ? ) . LOCATION AND ULTRAMAFIC WHOLE ROCKS , r p n 7 n r T r a ? QSSSriar AND MINERAL SEPARATES, , . , S R , RB/SR IVQC REF GEOLOGICAL SETTING RELATED ROCKS ( P P m ) { P P m ) S R 8 6 "Duke I s l a n d type" zoned u l t r a m a f i c complexes from the 560km-long b e l t i n southeastern A l a s k a . Four bodies were examined: Haines (H), Blashke I s l a n d (BI), Union Bay (UB), and Duke I s l a n d (DI) H pyroxene 2. 26 140. 0 0. 016 0. 7033 b i o t i t e 332. 0 132. 0 2. 50 0. 7155 BI d u n i t e 13. 1 0. 7068 o l i v i n e pyroxenite 0. 080 40. 8 0. 022 0. 7047 UB o l i v i n e p y r oxenite 0. 075 76. 8 0. 075 0. 7040 pyroxene 0. 7044 DI d u n i t e 1. 33 6. 33 0. 21 0. 7026 II 1. 80 1. 50 1. 20 0. 7030 p e r i d o t i t e 0. 704'3 o l i v i n e p y r oxenite 1. 01 64. 4 0. 016 0. 7041 21 U l t r a m a f i c rocks of the Lake Chatuge D i s t r i c t , Georgia, North C a r o l i n a . C l a s s i f i e d by the authors as " a l p i n e - t y p e " r o c k s ; however, match the c h a r a c t -e r i s t i c s o f c o n c e n t r i c a l l y -zoned u l t r a m a f i c bodies. The complex i s p a r t o f the narrow u l t r a m a f i c b e l t t h a t extends from Newfoundland southward t o Alabama. Va r i o u s mafic and u l t r a -mafic rock types, as w e l l as the surrounding g n e i s s and s c h i s t were analyzed s e r p e n t i n i z e d dunite o l i v i n e separate s e r p e n t i n i z e d c h l o r i t i c d u n i t e s e r p e n t i n i z e d w e h r l i t e s e r p e n t i n i z e d dunite s e r p e n t i n i t e o l i v i n e gabbro c o r o n i t e t r o c t o l i t e II d i a l l a g e - b y t o w n i t e v e i n hornblende-andesine v e i n meta-gabbro (amphibolite) garnet pyroxene gneiss b i o t i t e gneiss garnet muscovite gneiss 0.7069 0.7023 0.7036 0.7041 0.7058 0.7058 0.7029 0.7027 0.7025 0.7031 0.7036 0.7031 0.7047 0.7047 0.7039 0.7321 0.7258 22 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 21. Lanphere Sr87/Sr86: + 0.001 1968 (la-) E&A: 0.7079 22. Jones e t a l , Sr87/Sr86: + 0.0003 1973 E&A: 0.7079 + 0.0001 (2cr-) ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS where Rb and Sr values are determined, the Sr87/ Sr86 r e p o r t e d i s an i n i t i a l r a t i o , c o r r e c t e d f o r K-Ar dates f o r the bodies, b e l i e v e d t o be e a r l y Cretaceous, 100 - 110 my o l d . K/Rb r a t i o s were a l s o measured: v a l u e s show a range from 300 to 1200, and no c o r r e l a t i o n w i t h the str o n t i u m data. the major body i s a " c o n c e n t r i c a l l y - z o n e d s i l l " , showing the f o l l o w i n g zones (from c e n t r e t o p e r i -phery) : - p a r t l y s e r p e n t i n i z e d d u n i t e - c o r o n i t e t r o c t o l i t e ( l o c a l l y ) , w i t h commonly - observed rhythmic banding: a l t e r n a t i n g o l i v i n e and p l a g i o c l a s e l a y e r s separated by a r e a c t i o n zone of orthopyroxene-amphibole-spinel. A l s o a garnet-pyroxene gneiss near the c e n t r e of the i n t r u s i o n - o l i v i n e gabbro - amphibolite (metagabbro) the higher Sr87/Sr86 r a t i o s (0.7058 t o 0.7069) f o r s e r p e n t i n i t e rocks of t h i s s u i t e are assumed, by the authors, to r e f l e c t the i n f l u x of r a d i o g e n i c Sr87 from the surrounding gneisses and s c h i s t s d u r i n g s e r p e n t i n i z a t i o n . However, note the low r a t i o s o b tained f o r the s e r p e n t i n i z e d w e h r l i t e samples. LOCATION AND ULTRAMAFIC WHOLE ROCKS _ „ _ ^ ™ T I O N AND AND MINERAL SEPARATES, , , S R , RB/SR Hie REF GEOLOGICAL SETTING RELATED ROCKS ( p p m ) ( p p m ) S R 8 6 D. ULTRAMAFIC NODULES IN OCEANIC AND CONTINENTAL ALKALI BASALTS Kerguelen I s l a n d s , South p e r i d o t i t e 0. 420 10. 8 0. 039 0. 7080 Indian Ocean Ross I s l a n d , A n t a r c t i c a d u n i t e 1. 15 13. 2 0. 087 0. 7058 Galapagos I s l a n d p e r i d o t i t e 0. 352 35. 1 0. 010 0. 7036 hos t b a s a l t 58. 9 435 0. 135 0. 7035 Hawaiian I s l a n d s 1801 p e r i d o t i t e 0. 7064 host b a s a l t 0. 7054 K a p f e n s t e i n , A u s t r i a p e r i d o t i t e 0. 271 5. 69 0. 048 0. 7067 Chihuahua, Mexico II 0. 413 15. 0 0. 029 0. 7045 Ludlow, C a l i f o r n i a II 0. 398 13. 3 0. 030 0. 7062 Monduli, New Zealand II 3. 67 34. 2 0. 107 0. 7046 Kakanui, New Zealand garnet p e r i d o t i t e 1. 73 32. 7 0. 053 0. 7083 Mt. Leura, a Quaternary p e r i d o t i t e 0. 099 21. 1 0. 005 0. 7036 s c o r i a cone l o c a t e d near o l i v i n e separate 0. 087 1. 15 0. 076 0. 7053 Camperdown, A u s t r a l i a e n s t a t i t e separate 0. 206 5. 00 0. 041 0. 7048 d i o p s i d e separate 0. 212 194 0. 001 0. 7038 host b a s a l t 35. 2 959 0. 037 0. 7039 P e r i d o t i t e i n c l u s i o n and w e h r l i t e ( p l a g i o c l a s e 0. 352 35. 1 0. 010 0. 7036 host a l k a l i - o l i v i n e bearing) b a s a l t from C h a r l e s 58. I s l a n d , Galapagos ho s t a l k a l i - o l i v i n e b a s a l t 9 435 0. 135 0. 7035 REFERENCE PRECISION AND VALUE FOR E&A STANDARD ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS D. ULTRAMAFIC NODULES IN OCEANIC AND CONTINENTAL ALKALI BASALTS 23. Stueber and as i n r e f . 9 - d i s t i n c t i o n between the p e r i d o t i t e s and t h e i r h o s t Murthy, 1966 b a s a l t s on the b a s i s of Sr87/Sr86 r a t i o s i s d i f f -i c u l t ; however, a l l nodules appear t o have h i g h e r s t r o n t i u m r a t i o s than the normal range f o r b a s a l t s . - K/Rb r a t i o s were a l s o measured; g e n e r a l l y a low range, 115 to 542; no c o r r e l a t i o n w i t h Rb-Sr r e l -a t i o n s h i p s . 24. Stueber, 1969 Sr87/Sr86: + 0.001 25. McBirney and not r e p o r t e d W i l l i a m s , 1969 p e r i d o t i t e s and host b a s a l t s appear to have e s s e n t -i a l l y s i m i l a r Sr87/Sr86 r a t i o s . the u l t r a m a f i c i n c l u s i o n s are found o n l y w i t h i n the a l k a l i - o l i v i n e b a s a l t . the Sr87/Sr86 r a t i o s suggest a c l o s e g e n e t i c r e l -a t i o n s h i p between the i n c l u s i o n and i t s h o s t . ULTRAMAFIC WHOLE ROCKS 8 7 / S p i n e l p e r i d o t i t e xeno-l i t h s and host a l k a l i b a s a l t s from the M a s s i f C e n t r a l , France. The o l i v i n e - o r t h o p y r o x e n e -c1inopyroxene-sp ine1 assemblage x e n o l i t h s occur as bombs i n b a s a l t i c p y r o c l a s t i c d e p o s i t s , and as b l o c k s i n b a s a l t i c rocks of Late T e r t i a r y or Quaternary age M i n e r a l separates from a l h e r z o l i t e i n c l u s i o n w i t h i n Quaternary b a s a l t s of southeastern C a l i f o r n i a — extending from Barstow, San F r a n c i s c o County to the C a l i f o r n i a - N e v a d a State l i n e U l t r a m a f i c x e n o l i t h s i n a t u f f , and r e l a t e d b a s a l t i c flows from the Honolulu V o l c a n i c S e r i e s p e r i d o t i t e 0. .43 host b a s a l t 40. .6 p e r i d o t i t e .0. ,89 host b a s a l t 40. .9 p e r i d o t i t e 0. ,80 host b a s a l t 51. .0 p e r i d o t i t e 0. ,39 host b a s a l t 56. ,0 p e r i d o t i t e 0. ,49 II 0. ,98 o l i v i n e 1. ,5 chrome d i o p s i d e 1. ,0 orthopyroxene 1. ,2 hos t b a s a n i t e 62 r e l a t e d t r a c h y b a s a l t s g r a n o d i o r i t e x e n o l i t h 167 t o n a l i t e x e n o l i t h 58 garnet w e b s t e r i t e 0. 92 ( s p i n e l - b e a r i n g ) 0. 17 garnet w e b s t e r i t e 0. 54 nepheline m e l i l i t e 21 b a s a l t II 21 16.3 0.026 0.7060 26 765 0.053 0.7035 79.5 0.011 0.7093 736 0.056 0.7038 25.5 0.031 0.7106 846 0.060 0.7036 3.48 0.112 0.7061 887 0.063 0.7043 7.45 0.066 0.7096 40.4 0.024 0.7037 11 0.14 0.7087 27 74 0.014 0.7016 2.4 0.5 0.708 940 0.066 0.7031 0.7029 to 0.7052 287 0.582 0.7177 250 0.231 0.7097 286 0.0032 0.7031 28 82 0.0021 0.7035 63 0.0086 0.7029 570 0.037 0.7036 1117 0.019 0.7033 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 26. Leggo and E&A: 0.7091 + 0.0010 Hutchison, 1968 27. Peterman e t Sr87/Sr86: + 0.0002 a l , 1970 (2 ) value s c o r r e c t e d t o E&A = 0.7080 28. O'Neil e t Sr87/Sr86: + 0.0003 — ' 1 9 7 0 E&A: 0.7080 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS p o s s i b l e to p l a c e the p e r i d o t i t e s i n t o two groups: (a) w i t h Sr87/Sr86 r a t i o s i n the range 0.708 t o 0.710; and (b) with r a t i o s o f about 0.706 of l e s s . the l h e r z o l i t e was remarkably f r e s h w i t h no v i s i b l e s igns of secondary minerals or a l t e r a t i o n . the major strontium phases, o l i v i n e and chrome d i o p s i d e are not i n i s o t o p i c e q u i l i b r i u m w i t h one another, nor wit h the e n c l o s i n g b a s a n i t e . s t r o n t i u m i s o t o p e s i n d i c a t e a g e n e t i c r e l a t i o n s h i p between the x e n o l i t h s and host b a s a l t s . LOCATION AND GEOLOGICAL SETTING ULTRAMAFIC WHOLE ROCKS AND MINERAL SEPARATES, AND RELATED ROCKS RB (ppm) SR (ppm) RB/SR SR87/ SR86 REF U l t r a m a f i c x e n o l i t h s and host rocks o f the"Lashaine volcano, Tanzania L h e r z o l i t e and w e h r l i t e -c l i n o p y r o x e n i t e i n c l u s i o n s i n b a s a l t from D r e i s e r Weiker, Germany garnet l h e r z o l i t e (5) cl i n o p y r o x e n e (2) s p i n e l l h e r z o l i t e (6) cl i n o p y r o x e n e (2) mica-dunite (2) w e h r l i t e (3) s p i n e l h a r z b u r g i t e (3) hos t ankaramite c a r b o n a t i t e t u f f l h e r z o l i t e o l i v i n e separate l h e r z o l i t e o l i v i n e separate c l i n o p y r o x e n e separate orthopyroxene " w e h r l i t e II II c l i n o p y r o x e n i t e h o s t b a s a l t U l t r a m a f i c i n c l u s i o n s i n v o l c a n i c rocks from Deception I s l a n d , A n t a r c t i c a " average" "average i n c l u s i o n " v o l c a n i c 2.7 18.5 0.143 0.7050 0.77 146.2 0.005 0.7060 4.3 22.8 0.189 0.7052 1.38 113.6 0.012 0.7059 13.6 10.8 1.259 0.7039 5.9 25.9 0.226 0.7030 2.8 20.3 0.136 0.7036 20.6 510 0.040 0.7029 1.4 1069 0.001 0.7045 0.40 40.49 0.01 0.7039 0. 29 15.49 0.002 0.7040 0.45 11. 26 0.04 0.7044 0. 55 5.30 0.10 0.7051 0.31 2.64 0.12 0.7067 0.13 0.76 0.17 0.7095 0. 27 69.88 0.004 0.7022 1.79 0.7089 0.85 71.91 0.01 0.7028 0. 29 60.74 0.005 0.7035 0.49 93.24 0.005 0.7039 0.95 198.90 0.005 0.7040 41.37 1002.2 0.04 0.7036 42.83 1022.3 0.04 0.7035 0.7033 0.7036 29 30 31 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 29. Hutchison and Dawson, 1970 Sr87/Sr86: + 0.0005 t o + 0.0008 (2<r) E&A (4) = 0.7090 + 0.0006 87/86 values c o r r -e c t e d t o 0.7080 f o r E&A 30. P a u l , 1971 E&A = 0.7089 + 0.0003 a l l 87/86 r a t i o s c o r r e c t e d t o an E&A value of 0.7080 31. Faure e t a l , Sr87/Sr86: + 0.0010 1971 (2<r) E&A = 0.7082 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS appear t o be two groups of u l t r a m a f i c i n c l u s i o n s : the high Sr87/Sr86 r a t i o l h e r z o l i t e s , and the lower r a t i o d u n i t e , w e h r l i t e , and h a r z b u r g i t e ; the authors suggest t h a t the l a t t e r have a g e n e t i c r e l a t i o n s h i p with the ankaramite, while the former are a c c i d e n t a l the authors suggest t h a t the high r a t i o s f o r the c a r b o n a t i t e are p o s s i b l y the r e s u l t o f the v o l a t i l e carbonate f r a c t i o n accumulating a t the top of the ankaramite magma body and i n t e r a c t i n g with- c r u s t a l r o c ks, with the r e s u l t a n t occurrence o f i s o t o p i c exchange. apparent age of 550 my (+ a l a r g e u n c e r t a i n t y ) shown by the l h e r z o l i t e s ; b e l i e v e d t o r e p r e s e n t a mantle event. the l h e r z o l i t e i n c l u s i o n s show a d i s t i n c t d i f f e r e n c e i n t h e i r Sr87/Sr86 r a t i o s , compared w i t h t h e i r h o s t s the w e h r l i t e - c l i n o p y r o x e n i t e s , on the o t h e r hand, have strontium r a t i o s i n the same range as t h e i r hosts. the separated minerals have q u i t e v a r i e d s t r o n t i u m r a t i o s , but show no i s o c h r o n r e l a t i o n s h i p . The author suggests t h a t t h i s c o u l d i n d i c a t e some k i n d of isotope-exchange-contamination process i n the h i s t o r y of the rock s . the v o l c a n i c rocks vary i n composition from a l k a l i o l i v i n e b a s a l t to t r a c h i t e . ULTRAMAFIC WHOLE ROCKS R 7 / ^ ^ ° ^ I O N AND AND MINERAL SEPARATES, R B . , S R , RB/SR IIL ^ F GEOLOGICAL SETTING RELATED ROCKS ( p p m ) ( p p I t l ) S R 8 6 L h e r z o l i t e i n c l u s i o n s i n r e d - s p i n e l l h e r z o l i t e 20 0.7045 32 b a s a l t i n a c i n d e r e r u p t i o n II 25 0.7049 of Bandera C r a t e r , New II 100 0.7055 Mexico. Two types of g r e e n - s p i n e l l h e r z o l i t e 38 0.7023 i n c l u s i o n s are s t u d i e d : II 110 0.7040 r e d - s p i n e l l h e r z o l i t e s and II 47 0.7023 g r e e n - s p i n e l l h e r z o l i t e s n host b a s a l t •I II 108 430 390 620 0.7031 0.7030 0.7034 0.7028 L h e r z o l i t e i n c l u s i o n s l h e r z o l i t e 2. 8 3. 2 0. 875 0.7089 33 from the Puerco Necks, II 0. 8 5. 9 0. 136 0.7083 New Mexico II 0.7069 o l i v i n e separate 1. 2 2. 9 0. 414 0.7083 e n s t a t i t e " 0.7084 w e b s t e r i t e 2. 0 10. 05 0. 199 0.7069 hos t b a s a l t 25 430 0. 058 0.7039 II 0.7040 II 0.7041 Coarse-grained l h e r z o l i t e l h e r z o l i t e s 0.7027 t o 34 i n c l u s i o n s from s c o r i a 0.7107 cones of l a t e P l i o c e n e -P l e i s t o c e n e nepheline h a w a i i t e s and b a s a n i t e s h o s t nepheline h a w a i i t e s and b a s a n i t e s 0.7038 to 0.7045 of Newer V o l c a h i c s , V i c t o r i a , A u s t r a l i a O l i v i n e - r i c h l h e r z o l i t e l h e r z o l i t e s (2) t r a c e 4 to 22 0.7043 , 35 nodules i n the Malapai H i l l b a s a l t , Joshua Tree N a t i o n a l Monument, C a l i f . h o s t a l k a l i n e - o l i v i n e b a s a l t s 0. 04 0.7030 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 32. L a u g h l i n Sr (ppm): + 5% e t a l , 1971 S r 8 7 / S r 8 6 : +0.0005 E&A (3) = 0.7083 33. Kudo e t al, E&A = 0.7080 1972 34. Dasch and not r e p o r t e d Green, 1972 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS r e d - s p i n e l l h e r z o l i t e : 83 o l i v i n e , 10 c l i n o p y r o x e n e , 5 orthopyroxene, and 2 r e d - s p i n e l . g r e e n - s p i n e l l h e r z o l i t e : 15 o l i v i n e , 59 c l i n o p y r o -xene, 10 orthopyroxene, and 1 g r e e n - s p i n e l , b a s a l t : 9 o l i v i n e , 20 pyroxene, 50 g l a s s , 13 p l a g -i o c l a s e , and 8 opaques. c l e a r l y , the r e d - s p i n e l l h e r z o l i t e s and the green-s p i n e l l h e r z o l i t e s d e f i n e two d i s t i n c t groups of Sr87/Sr86 r a t i o s , the l a t t e r with v a l u e s s i m i l a r to the b a s a l t range. the i n c l u s i o n s have d i s t i n c t l y h i g h e r Sr87/Sr86 r a t i o s than t h e i r host b a s a l t s . f o r the l h e r z o l i t e i n c l u s i o n f o r which m i n e r a l -separate data e x i s t , the c o n s t i t u e n t m i n e r a l s are not i n i s o t o p i c e q u i l i b r i u m as they do not d e f i n e an i s o c h r o n . A l s o noteworthy i s the s i m i l a r i t y between the i s o t o p i c composition of the i n d i v i d u a l m i n e r a l s , but t h e i r d i f f e r e n c e from (higher r a t i o s than) the whole rock which i n c l u d e s chrome d i o p s i d e which normally has a much lower Rb/Sr r a t i o and much higher Sr content than o l i v i n e and orthopyrox-ene . h i g h e r , and a much wider range of Sr87/Sr86 v a l u e s obtained f o r the l h e r z o l i t e i n c l u s i o n s , compared with t h e i r h o sts. data f o r separated m i n e r a l s show t h a t the i n c l u s -i o ns are r e l i c t and t h a t the minerals do not form a c l o s e d system, at l e a s t w i t h r e s p e c t to o l i v i n e . LOCATION AND ULTRAMAFIC WHOLE ROCKS r F n ^ r T P AT 9FTTTNr A N D M I N E R A L SEPARATES, GEOLOGICAL SETTING AND RELATED ROCKS Dunite nodule, E x e c u t i v e Committee Range, A n t a r c t i c a M i n e r a l separates from,a l h e r z o l i t e nodule from Mt. A l d a z , A n t a r c t i c a M i n e r a l separates from a l h e r z o l i t e nodule from K i l b o u r n e Hole, New Mexico M i n e r a l separates from two l h e r z o l i t e nodules from San C a r l o s , A r i z o n a M i n e r a l separates from a w e h r l i t e nodule from H u a l a l a i 1801, Hawaii d u n i t e h o s t b a s a l t c l i n o p y r o x e n e orthopyroxene o l i v i n e h o s t b a s a l t c1inopyroxene orthopyroxene o l i v i n e a u g i t e x e n o c r y s t h o s t b a s a l t c l i n o p y r o x e n e orthopyroxene o l i v i n e c l i n o p y r o x e n e orthopyroxene o l i v i n e h o s t b a s a l t c l i n o p y r o x e n e o l i v i n e h o s t b a s a l t M i n e r a l separates from a c l i n o p y r o x e n e w e h r l i t e nodule from C r a t e r o l i v i n e 160, San F r a n c i s c o v o l c a n i c f i e l d , A r i z o n a h o s t b a s a l t RB (ppm) SR (ppm). RB/SR SR87/ SR86 0. 208 1.06 0.197 0.7051 0.7025 0.153 16.0 0.010 0.7022 0.146 0.97 0.152 0.7058 0.074 0.305 0.240 0.7077 26.0 807 0.032 0.7030 0.067 43.7 0.002 0.7025 .0.079 1.17 0.067 0.7058 0.073 1.01 0.071 0.7060 0.165 33. 6 0.005 0.7026 27.0 540 0.050 0.7032 0. 221 224 0.001 0.7030 0.121 1. 46 0.083 0.059 0. 234 0.250 0.120 24.6 0.005 0.7025 0. 299 3.01 0.099 0.7080 0.130 1.65 0.079 0.7096 28.7 872 0.033 0.7028 0.823 47.9 0.017 0.7030 0.104 0. 783 0.133 0.7043 23.3 506 0.046 0.7030 0.132 53.1 0.003 0.7033 0.085 1.62 0.052 0.7043 17.7 785 0.022 0.7031 PRECISION AND VALUE REFERENCE FOR E&A STANDARD Stu.ll and Davis, 1973; S t u l l and McMillan, 1973 Stueber and Ikramuddin, 1974 Sr87/Sr86 + 0.0008 (2o~) E&A = 0.7080 Sr87/Sr86: + 0.0003 E&A (8) = 0.7078 to 0.7080 f o r the extremely low Rb and Sr con-c e n t r a t i o n samples, the Rb/Sr r a t i o may vary as much as 25% ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS a l l o t r i o m o r p h i c - g r a n u l a r t e x t u r e and t e c t o n i c f a b -r i c o f the nodules argue s t r o n g l y a g a i n s t t h e i r cognate o r i g i n . the l h e r z o l i t e nodules are t y p i c a l l y c o a r s e - g r a i n e d , with xenomorphic-granular t e x t u r e ; they appear extremely f r e s h with no s i g n s of secondary m i n e r a l s or g l a s s , and no evidence of r e c r y s t a l l i z a t i o n . Modal compositions a r e : - Mt. A l d a z : 53 o l i v i n e , 29 orthopyroxene, 14 c l i n o -pyroxene, and 4 s p i n e l . - K i l b o u r n e Hole: 56 o l i v i n e , 33 orthopyroxene, 9 clin o p y r o x e n e , 2 s p i n e l . - San C a r l o s : 62 o l i v i n e , 24 orthopyroxene, 12 clinopyroxene, and 2 s p i n e l . the w e h r l i t e nodules both c o n t a i n t r a c e amounts of opaque m i n e r a l s . The Hawaiian nodule i s a s m a l l , medium-grained aggregate w i t h xenomorphic g r a n u l a r t e x t u r e . The l a r g e nodule from A r i z o n a shows hyp-id i o m o r p h i c - g r a n u l a r t e x t u r e with some p o i k i l i t i c o l i v i n e i n clinopyroxene. S e v e r a l of the o l i v i n e g r a i n s have r e a c t i o n rims. Modal compositions f o r the w e h r l i t e s a re: - H u a l a l a i 1801: 80 o l i v i n e , 20 c l i n o p y r o x e n e . - C r a t e r 160: 71 o l i v i n e , 29 c l i n o p y r o x e n e . the authors attempt to c o r r e l a t e v a r i a t i o n s i n the Sr87/Sr86 r a t i o s with the Rb87/Sr86 r a t i o s f o r the l h e r z o l i t e m i n e r a l s ; they obtained apparent i s o c h r o n r e l a t i o n s h i p s f o r the Mt. Aldaz and K i l b o u r n e Hole nodules, which they suggest r e p r e s e n t r e l i c t mantle events. LOCATION AND GEOLOGICAL SETTING ULTRAMAFIC WHOLE ROCKS AND MINERAL SEPARATES, AND RELATED ROCKS E. KIMBERLITES (ULTRAMAFIC INCLUSIONS) Kimberley, South A f r i c a k i m b e r l i t e (whole) W e l l i n g t o n Pipe, S. A f r i c a p e r i d o t i t e B u l t f o n t e i n P i pe, S. A f r i c a p e r i d o t i t e V i s s e r Pipe, Tanganyika Whole-rock and m i n e r a l separates from k i m b e r l i t e pipe e c l o g i t e s from, the Roberts V i c t o r Mine, South A f r i c a M i n e r a l separates from k i m b e r l i t e p e r i d o t i t e s from : (1) DuToit's Pan Mine, South A f r i c a (2) Wesselton Mine, South A f r i c a (3) -Roberts V i c t o r Mine, South A f r i c a (4) Dodoma, Tanzania e c l o g i t e e c l o g i t e omphacite separate garnet " e c l o g i t e omphacite separate garnet " mica i n c l u s i o n (1) d i o p s i d e garnet mica (2) d i o p s i d e (3) d i o p s i d e garnet mica (4) d i o p s i d e garnet R B S R DD/CD SR87/ R E p (ppm) (ppm) R B / S R SR86 62. 8 488. 7 0.129 0. 7050 4. 48 72. 4 0.062 0. 7064 2. 03 58. 6 0.035 0. 7049 7. 52 46. 7 0.061 0. 7046 6. 04 159. 3 0.038 0. 707 0. 68 227. 5 0.003 0. 702 1. 00 6. 43 0.155 0. 712 19. 56 150. 5 0.130 0. 709 0. 966 191. 5 0. 004 0. 701 1. 008 13. 27 0.076 0. 708 561. 2 76. 86 7.302 0. 738 1. 28 586. 3 0.002 0. 705 4. 06 33. 87 0.120 0. 712 210. 9 58. 96 ^3.577 0. 718 2. 80 853. 2 0.003 0. 707 2. 62 293. 6 0.009 0. 708 <•: 4. 46 22. 5 0.198 212. 7 180. 7 0.177 0. 712 38 39 40 0.725 0.81 148. 2 7.10 0.005 0.114 0.706 0.710 REFERENCE PRECISION AND VALUE FOR E&A STANDARD 37. Roe, 1964 as i n r e f . 4 38. Stueber and as i n r e f . 9 Murthy, 1966 39. A l l s o p p e t Sr87/Sr86: + 0.001 a l , 1969 to + 0.003 E&A = 0.708 + 0.001 40. A l l s o p p e t as i n r e f . 39 a l , 1969 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS k i m b e r l i t e composed of o l i v i n e and p h l o g o p i t e w i t h some s e r p e n t i n i z a t i o n ; may c o n t a i n some fragments of the invading rock. K/Rb r a t i o s a l s o determined; i n g e n e r a l , the v a l u e s are q u i t e low, and very low f o r the omphacites; these r a t i o s show no c o r r e l a t i o n w i t h the Rb-Sr data. K/Rb r a t i o s are o v e r a l l q u i t e low, and extremely low f o r the omphacites; they show no c o r r e l a t i o n with the Rb-Sr data. T r v , A m T r k M A l v T T, ULTRAMAFIC WHOLE ROCKS D T 3 C D C D Q V r J S c S T H r AND MINERAL SEPARATES, , . , S R . RB/SR S R 8 7 / REF GEOLOGICAL SETTING AND RELATED ROCKS ( p p m ) ( p p m ) S R 8 6 E c l o g i t e s and a garnet p e r i d o t i t e from a k i m b e r l i t e i n t r u s i o n , Roberts V i c t o r Mine, South A f r i c a Whole-rock South A f r i c a n k i m b e r l i t e s o f both f i s s u r e and pipe type k i m b e r l i t e (whole) 113 2040 0.-055 0.7077 e c l o g i t e 5 .4 141 0.038 0.7072 II 13 133 0.094 0.7096 II 28 230 0.122 0.7081 II 3 .9 370 0.010 0.7039 H 2 .1 346 0.006 0.7040 garnet p e r i d o t i t e 6 .9 108 0.062 0.7070 Swartruggens (calcareous 20 to 274 to 0.075 t o 0.7087 t o micaceous k i m b e r l i t e ) ( 9 ) 265 1498 0.237 0.7163 Wesselton (pipe)(6) 80 to 751 to 0.064 to 0.7078 to 122 1472 0.112 0.7123 " ( l a t e stage dyke)(2) 94 to 1232 to 0.073 t o 0.7118 to 95 1282 0.077 0.7154 " (garnet mica p e r i d o t i t e ) 20 83 0.242 0.7058 " ( e c l o g i t e ) 7 68 0.108 0.7123 Premier (3) 5. 6 to 48 to 0.053 to 0.7156 to 18 284 0.182 0.7214 Monastry 5 .3 592 0.009 0.7067 Du t o i t s p a n 4 . 5 994 0.005 0.7063 B u l t f o n t e i n 64 569 0.113 0.7058 Doornkloof 109 1883 0.058 0.7152 K i r k l a n d Lake 205 1302 0.157 0.7082 41 PRECISION AND VALUE REFERENCE FOR E&A STANDARD 41. Manton and Tatsumoto, 1971 42. M i t c h e l l and Sr87/Sr86: + 0.0001 Crocket, 1971 to + 0.0007 ( l < r ) E&A = 0.7083 + 0.0006 (2sr) ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS mainly a Pb-isotope study two d i s t i n c t groups of Sr87/Sr86 v a l u e s r e c o g n i z e d f o r the e c l o g i t e s . Authors c l a i m t h a t the lower values probably r e p r e s e n t " o r i g i n a l rock", w h i l e the h i g h e r r a t i o s r e f l e c t contaminated samples, most of the Sr being i n t r o d u c e d from the k i m b e r l i t e . Note, however, the c o n t r a d i c t o r y evidence p r o v i d e d by the t o t a l Sr contents of the two groups of samp-l e s . both f i s s u r e and pipe-type k i m b e r l i t e s y i e l d s i m i l a r s trontium r a t i o s . authors conclude t h a t the hig h r a t i o s are not due to bulk a s s i m i l a t i o n of the g r a n i t i c m a t e r i a l . they suggest a theory of k i m b e r l i t e p e t r o g e n e s i s i n v o l v i n g p a r t i a l m e l t i n g of a f i v e - p h a s e garnet mica p e r i d o t i t e to g i v e a k i m b e r l i t e of h i g h or low Sr87/Sr86 r a t i o w i t h p o s s i b l e m o d i f i c a t i o n o f low r a t i o s by s e l e c t i v e e x t r a c t i o n of r a d i o g e n i c Sr87 by l a t e - s t a g e k i m b e r l i t e f l u i d s . T „ ^ m T r t M ULTRAMAFIC WHOLE ROCKS D T, C T 3 COOT/ VD ^ ^ ^ C S S S T X ^ AND MINERAL SEPARATES, , . , S R . RB/SR S R ^ / , REF E GEOLOGICAL SETTING AND RELATED ROCKS ( p p m ) ( p p m ) S R 8 6 "Fresh" South A f r i c a n k i m b e r l i t e s U l t r a m a f i c and g r a n u l i t e x e n o l i t h s from the b a s i c b r e c c i a p i p e s a t Delegate, E a s t e r n A u s t r a l i a D u t o i t s p a n Mine (600 m depth) II De Beers Mine (surface) A l t e r e d k i m b e r l i t e s : De Beers Mine (300m) Robert V i c t o r Mine (near s u r f a c e ) two-pyroxene g r a n u l i t e s p i n e l p y r o x e n i t e f o s s a i t e e c l o g i t e h o r n b l e n d e - f o s s a i t e e c l o g i t e b a s a l t ( n e p h e l i n i t e ) pipe f i l l i n g 74 60 30 80 5 9.30 3.3 4.79 5.46 14.2 744 790 1680 464 1168 355 131 125 162 1446 0.099 0.076 0.018 0.172 0.006 0.026 0.025 0.038 0.034 0.010 0.7037 0.7046 0.7040 0.7068 0.7083 0.7065 0.7057 0.7052 0.7046 0.7047 43 44 F. LAYERED GABBRO-NORITE-PERIDOTITE IN MAJOR INTRUSIONS Skaergaard i n t r u s i o n , East Greenland Skaergaard i n t r u s i o n , t r a v e r s e from the i n n e r gabbro outward t o the host g r a n i t i c g n e i s s Sudbury I r r u p t i v e , O n t a r i o " b a s i c r o c k s " gabbro g r a n i t i c g n e i s s n o r i t e 30. 3 365.7 0.083 0.7065 0.706 0.715 0.704 45 46 47 PRECISION AND VALUE ADDITIONAL NOTES ON ISOTOPIC DATA FOR E&A STANDARD AND GEOLOGICAL RELATIONSHIPS 43. Berg and A l l s o p p , 1972 Sr87/Sr86: + 0.0005 (2o-) E&A = 0.7083 + 0.0007 - Sr87/Sr86 values c o r r e c t e d f o r an age of 100 my, 44. Compston and Sr87/Sr86: + 0.0005 Lo v e r i n g , 1969 based on Pb data (LOVERING and TATSUMOTO, 1968), the f o s s a i t e e c l o g i t e i n c l u s i o n appears t o have an " a c c i d e n t a l " o r i g i n . the authors p o i n t out t h a t the a l k a l i abundances measured i n the t o t a l - r o c k cannot be accounted f o r by the a l k a l i abundances measured i n the major mi n e r a l phases, so they c l a i m that i t i s d i f f i c u l t to envisage the t o t a l rock as c h e m i c a l l y c l o s e d to Rb d u r i n g pipe formation or f o r a leng t h y p e r i o d p r i o r to t h i s event. F. LAYERED GABBRO-NORITE-PERIDOTITE IN MAJOR INTRUSIONS 45. Hamilton, Sr87/Sr86: + 0.002 1963 Sr87/Sr86 i n c r e a s e s p r o g r e s s i v e l y from the gabbro to the g n e i s s . elemental and i s o t o p i c data c o l l e c t i v e l y p o i n t t o a marked, complex i n t e r a c t i o n between the ga b b r o i c magma and the host g r a n i t e g n e i s s . 47. Faure e t a l , E&A = 0.7090 - Sr87/Sr86 i s an i n i t i a l r a t i o corresponding t o an 1964 87/86 r a t i o s c o r r e c t e d age of about 1730 my, and a present-day measured to E&A va l u e o f 0.7080 r a t i o of 0.7128. 46. Leeman e t a l , 1973 LOCATION AND GEOLOGICAL SETTING ULTRAMAFIC WHOLE ROCKS AND MINERAL SEPARATES, AND RELATED ROCKS RB (ppm) SR (ppm) RB/SR SR87/ SR86 REF Duluth Gabbro, Minnesota n o r i t e 0.7055 48 Endion S i l l , Minnesota diabase 0.7046 49 S t i l l w a t e r Complex, Montana h a r z b u r g i t e II 2. 55 0.72 0. 54 27.1 39.4 14.6 0.094 0.017 0.036 0.7090 0.7060 0.7059 50 n o r i t e n o r i t i c h a r z b u r g i t e 1.49 1.21 18.3 70.7 0.084 0.017 0.7110 0.7058 a n o r t h o s i t e II 3.9 6.59 158.0 155.8 0.025 0.039 0.7056 0.7072 U l t r a m a f i c zone, S t i l l w a t e r Complex, Montana p e r i d o t i t e 0.382 13.36 0.028 0.7029 51 Hoghwood Mountains, Montana p e r i d o t i t e (?) 142 1784 0.079 0.7062 Muskox I n t r u s i o n , North-west T e r r i t o r i e s s e r p e n t i n i z e d dunite p y r o x e n i t e 7.75 3.47 5.85 114 1.32 0.03 0.7864 0.7101 Mt. N i t t i s d r i l l h o l e , Monchegora p l u t o n , Kola P e n i n s u l a , Russia p y r o x e n i t e 0.12 50.5 0.022 0.7034 Great Dyke of Southern "whole r o c k s " -0.90 0.7010 52 Rhodesia: u l t r a m a f i c rocks w i t h the assemblage o l i v i n e - c l i n o p y r o x e n e -o r t h o p y r o x e n e - b i o t i t e -p l a g i o c l a s e - o p a q u e s REFERENCE PRECISION AND VALUE FOR E&A STANDARD 48. Faure e t a l , Sr87/Sr86: + 0.0003 1 Qf.q E&A = 0.7082 + 0.0004 49. Faure e t a l , Sr87/Sr86: + 0.0006 1969 E&A = 0.7082 + 0.0004 50. Fenton and E&A (15) = 0.7083 Faure, 1969 51. Stueber and as i n r e f . 9 Murthy, 1966 52. A l l s o p p , 1965 Sr87/Sr86: + 0.0019 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS Sr87/Sr86 i s an i n i t i a l r a t i o o b t ained from a whole-rock i s o c h r o n y i e l d i n g an age of 1115 + 14 my. Sr87/Sr86 i s an i n i t i a l r a t i o obtained from a whole-rock i s o c h r o n with an age of 109 2 + 15 my. the l a s t f i v e samples d e f i n e an i s o c h r o n w i t h an age of 2450 + 210 my, and an i n i t i a l Sr r a t i o o f 0.7029 (+ 0.0006). the f i r s t two h a r z b u r g i t e s from the b a s a l zone are s e r p e n t i n i z e d . They do not f i t the i s o c h r o n and have q u i t e high Sr87/Sr86 r a t i o s (0.7192 and 0.7075 r e s p e c t i v e l y , b efore the age c o r r e c t i o n i s a p p l i e d ) . There i s no evidence f o r contamination f o r these two anomalous h a r z b u r g i t e s . the o n l y i n i t i a l r a t i o i s t h a t f o r the S t i l l w a t e r Complex, c o r r e c t e d f o r an age of 1700 my. the high Sr87/Sr86 and Rb/Sr r a t i o s i n the Muskox s e r p e n t i n i z e d d u n i t e are due to the presence of approximately 3% accessory b i o t i t e i n t h i s r o c k . a very l a r g e c o r r e c t i o n a p p l i e d to the Sr87/Sr86 r a t i o , corresponding to an age of 2500 + 25 my. samples i n which orthopyroxene g r e a t l y exceeds clinopyroxene e x h i b i t much higher Rb/Sr and Sr87/ Sr86 r a t i o s . LOCATION AND GEOLOGICAL SETTING ULTRAMAFIC WHOLE ROCKS AND MINERAL SEPARATES, AND RELATED ROCKS Bushveld Complex, S. A f r i c a Great Dyke, Rhodesia Losberg Complex, S. A f r i c a Trompsburg Complex, S. A f r i c a Usushwana Complex, S. A f r i c a p e r i d o t i t e group (4) The Insch mass of the Caledonian B a s i c igneous p r o v i n c e of NE Sc o t l a n d gabbro group (3) ferr o g a b b r o group (3) syenogabbro group (8) The B e l h e l v i e mass of the Caledonian b a s i c p r o v i n c e of NE S c o t l a n d p e r i d o t i t e group (2) t r o c t o l i t e group (2) hypersthene-gabbro group (2) o l i v i n e - g a b b r o group ( RB SR pn/cp SR87/ (ppm) (ppm) R B / S R SR86 R E F 0.7065 53 0.7024 0.7064 0.7043 0.7031 0.17 to 2.7 to 0. 062 to 0.7045 54 0.33 177 0.002 to 0.7082 0.8 to 258 to 0. 003 t o 0.7032 7.0 471 0.026 to 0.7114 3.1 to 359 to 0. 008 to 0.7110 7.7 403 0.019 to 0.7122 11.3 to 118 t o 0. 047 t o 0.7101 94.1 304 0.782 to 0.7122 0.51 to 4.1 to 0. 06 to 0.7051 0.55 9.8 0.12 to 0.7069 2.2 to 447 to 0. 005 to 0.7022 2.7 467 0.006 to 0.7075 3.5 to 204 to 0. 013 to 0.7078 11.6 269 0.057 to 0.7084 0.6 to 257 to 0. 002 to 0.7041 3.6 358 0.010 to 0.7063 wwwTxn-* PRECISION AND VALUE REFERENCE FOR E&A STANDARD 53. Davies e t a l , 1970 (data o b t a i n e d from Faure and Powell, 1972 54. Pankhurst, Sr87/Sr86: + 0.007 1969 (2c-) E&A = 0.70843 + 0.00052 a l l 87/86 r a t i o s c o r r e c t e d t o an E&A of 0.70800 ADDITIONAL NOTES ON ISOTOPIC DATA AND GEOLOGICAL RELATIONSHIPS a l l r a t i o s r e p o r t e d are i n i t i a l r a t i o s . f o r each of the South A f r i c a n l a y e r e d mafic i n t r u s -i o n s , the Sr87/Sr86 r a t i o s o f the a c i d and mafic rock types o v e r l a p , although only s l i g h t l y f o r the Bushveld Complex. Sr87/Sr86 are i n i t i a l r a t i o s , c o r r e c t e d f o r an age of 510 + 13 my (Insch mass) and about 500 my ( B e l -h e l v i e mass). Insch mass: among the p e r i d o t i t e s , the sample w i t h the h i g h e s t r a t i o , an o l i v i n e m e l a n o r i t e , has by f a r the h i g h e s t Sr content; i t i s t h e r e f o r e u n l i k e l y t h a t the s i g n i f i c a n t v a r i a t i o n i s due simply to p o s t -c o n s o l i d a t i o n contamination. B e l h e l v i e mass: as i n the Insch mass, a marked i n c r -ease i n the i n i t i a l Sr87/Sr86 r a t i o s accompanies the incoming of abundant cumulus p l a g i o c l a s e . The o l i v i n e - g a b b r o group y i e l d s s i g n i f i c a n t l y lower r a t i o s than those obtained f o r the t r o c t o l i t e s and the hypersthene-gabbros, suggesting d i f f e r e n t times of formation, f o r which p e t r o g r a p h i c evidence a l s o e x i s t s . Thus, a m u l t i p l e - i n t r u s i o n i s suggested. vo Type of occurrence U l t r a m a f i c whole-rocks x s U l t r a m a f i c m i n e r a l separates A s s o c i a t e d b a s a l t i c and g a b b r o i c rocks x A. Oceanic 1. A l l u l t r a m a f i c s 0.7075 0.0007 2. St. Peter and 0.7052 0.0004 St. Paul Rocks 3. U l t r a m a f i c s e x c l u d - 0.7094 0.0010 i n g St. Peter and St. Paul Rocks B. A l p i n e - t y p e i n t r u s i o n s 0.7119 0.0013 C. C o n c e n t r i c a l l y - z o n e d 0.7057 0.0005 plugs D. Nodules i n a l k a l i 0.7052 0.0003 b a s a l t s E. I n c l u s i o n s i n kimber- 0.7075 0.0006 l i t e s F. Layered zones i n major 0.7058 0.0005 i n t r u s i o n s 0.7082 0.0006 0.7162 0.0031 0.7063 0.0027 0.7054 0.0005 0.7084 0.0013 0.7033 0.0003 0.7041 0.0004 0.7034 0.0003 0.7036 0.0001 Table XVII. Summary of recorded i n i t i a l Sr87/Sr86 r a t i o s f o r u l t r a m a f i c and a s s o c i a t e d rocks of v a r i o u s types of occurrence. The mean (x) and v a r i a n c e (s) values are c a l c u l a t e d from the d e t a i l e d l i s t i n g s appearing i n t a b l e XVI. 101 VI. INTERPRETATION OF THE REPORTED ISOTOPE VARIATIONS AND  THEIR PETROGENETIC IMPLICATIONS P r i o r t o the p r e s e n t a t i o n of my model f o r the chem-i c a l e v o l u t i o n of the e a r t h d e f i n e d by r a d i o g e n i c s t r o n t i u m d i s t r i b u t i o n , v a r i o u s i n t e r p r e t a t i o n s of the d i f f e r e n c e s i n i s o t o p i c r a t i o s presented i n the p r e v i o u s two chapters are now d i s c u s s e d . A. B a s a l t s E a r l i e s t s t r o n t i u m i s o t o p e analyses on b a s a l t s had suggested a r e l a t i v e l y homogeneous upper mantle source (FAURE and HURLEY, 1963; HEDGE and WALTHALL, 1963). The i s o t o p i c v a r i a t i o n s l a t e r diagnosed i n o c e a n i c b a s a l t s were i n t e r p r e t e d as r e f l e c t i n g p a r t i a l m e l t i n g a t d i f f e r e n t depths i n a u n i f o r m l y s t r a t i f i e d upper mantle i n which the Rb/Sr r a t i o decreased w i t h depth. The g e n e r a l l y s l i g h t l y h i g h e r v a l u e s o b t a i n e d f o r cont-i n e n t a l b a s a l t s were i n i t i a l l y , and i n most cases s t i l l a re, a s c r i b e d to contamination by c r u s t a l m a t e r i a l b e a r i n g much highe r i s o t o p i c r a t i o s , or the e f f e c t s of low-grade metamorphism (see HEATH, 19 67). As mentioned e a r l i e r , i t has not been poss-i b l e t o d e c i p h e r a c l e a r p a t t e r n f o r v a r i a t i o n s i n the data obtained f o r c o n t i n e n t a l b a s a l t s . However, wi t h r e s p e c t to o c e a n i c b a s a l t s , a d i s t i n c t d i f f e r e n c e has now been e s t a b l i s h e d between the r a t i o s f o r t h o l e i i t e s and a l k a l i b a s a l t s , as noted i n f i g u r e 6 and the r e l a t e d d i s c u s s i o n . GAST (1968) has proposed t h a t ocean-ridge t h o l e i i t e s are d e r i v e d from zones t h a t have p r e v i o u s l y produced 102 a l k a l i b a s a l t s through an e a r l i e r stage of p a r t i a l m e l t i n g . I t should be emphasized, however, t h a t i f such be the case, the time i n t e r v a l between p e r i o d s of magma g e n e r a t i o n must be l o n g , g because of the 4.7 - 5.0 x 10 year h a l f - l i f e of Rb87. TATSUMOTO e t a l (1965) noted t h a t the Rb/Sr r a t i o s of ocean-ridge t h o l e i i t e s are not h i g h enough to e x p l a i n even the u n u s u a l l y low Sr87/Sr86 i n a c l o s e d system model. These authors were the f i r s t to suggest a two-stage h i s t o r y , w i t h the source r e g i o n having a h i g h e r Rb/Sr r a t i o p r i o r to d i f f e r -e n t i a t i o n 1 by o r more ago. Based on HURLEY 'S (1968a, 1968b) p o s t u l a t i o n t h a t v o l c a n i s m and concomitant c o n t i n e n t a l growth have s i g n i f i c a n t l y lowered the Rb/Sr r a t i o of the mantle as a whole, PETERMAN and HEDGE (1971) propose t h a t the b a s a l t s w i t h the h i g h e s t Sr87/ Sr86 r a t i o s r e p r e s e n t p r i m i t i v e or undepleted mantle. They suggest t h a t t h o l e i i t i c b a s a l t s form o n l y from mantle t h a t has undergone severe p r e v i o u s d e p l e t i o n , w h ile the h i g h l y a l k a l i n e b a s a l t s w i t h the very h i g h Sr87/Sr86 r a t i o s are a r e s u l t of processes t h a t l o c a l l y i n c r e a s e the Rb/Sr r a t i o i n the mantle even though the main process i s one of Rb/Sr decrease. A more promising s u g g e s t i o n by Peterman and Hedge, i n t h i s w r i t e r ' s o p i n i o n , i s t h a t the t h o l e i i t i c b a s a l t s are d e r i v e d from the deep mantle which has been d e p l e t e d i n Rb/Sr, w h i l e the a l k a l i b a s a l t s are d e r i v e d from a d i s t i n c t l y d i f f e r e n t upper mantle source. 103 B. I s l a n d Arc and A n d e s i t i c V o l c a n i c s The f a c t t h a t rocks of the c a l c - a l k a l i n e s e r i e s gener-a l l y have s t r o n t i u m i s o t o p i c r a t i o s i n the range of b a s a l t s (table XV), i s i n t e r p r e t e d by PUSHKAR (1968) as an i n d i c a t i o n of t h e i r formation without contamination of the magmas w i t h c o n t i n e n t a l m a t e r i a l . However, i n a study of the Le s s e r A n t i l r . l e s A rc, PUSHKAR (1968) o b t a i n e d anomalously h i g h s t r o n t i u m r a t i o s f o r d a c i t i c r o cks, r e l a t i v e t o much lower v a l u e s y i e l d e d by a n d e s i t i c l a v a s of the same p r o v i n c e ; i n t h i s case he sugg-e s t e d t h a t the h i g h v a l u e s were due to contamination by sedim-entary m a t e r i a l s which form the upper basement rocks o f the ar c . For the Taupo V o l c a n i c Zone, the s t r o n t i u m i s o t o p i c r a t i o s i n d i c a t e t h a t the s i l i c i c rocks are not products o f f u s i o n o f o l d s i a l or reworked s i a l i c m a t e r i a l , promoting a common source f o r both the s i l i c i c and mafic rocks of t h a t p r o v i n c e (LEWIS, 1968). S i m i l a r l y , HEDGE e t a l (1970) f e e l t h a t the r o l e p l a y e d by c r u s t a l rocks i n the g e n e r a t i o n of the an d e s i t e s and d a c i t e s of Oregon and Washington i s minor or no n e x i s t e n t . HEDGE (1966) had e a r l i e r concluded t h a t most c o n t i n e n t a l f e l s i c v o l c a n i c s are e n r i c h e d i n r a d i o g e n i c s t r o n t -ium, suggesting an o r i g i n w i t h i n the c r u s t , o r a p p r e c i a b l e contamination by c r u s t a l m a t e r i a l . In a more r e c e n t study of the Lesser A n t i l l e s A r c , HEDGE and LEWIS (1971) i n t e r p r e t the constancy of s t r o n t i u m i s o t o p i c data w i t h i n each c e n t r e as su p p o r t i n g the h y p o t h e s i s , based on p e t r o g r a p h i c and major- and minor-element data, t h a t 104 b a s a l t s and a n d e s i t e s f o r each c e n t r e are generated from the same source. They i n t e r p r e t a l a c k of c o r r e l a t i o n between Rb/Sr and Sr87/Sr86 among the v a r i o u s s u i t e s as suggesting t h a t e i t h e r the r e s p e c t i v e source m a t e r i a l s are so o l d t h a t the i s o t o p i c d i f f e r e n c e c o u l d be generated by s m a l l d i f f e r e n c e s i n the Rb/Sr r a t i o which were obscured by p r e v i o u s volcanism, or t h a t the Rb/Sr of the source m a t e r i a l s was a l t e r e d by a p r e v i o u s p e r i o d of volcanism. Furthermore, they found t h a t the more p o t a s s i c l a v a s of C a r r i a c o u I s l a n d have the h i g h e r Sr87/Sr86 r a t i o s , mimicking the t r e n d observed f o r o c e a n i c b a s a l t s . In a comprehensive review of the s t r o n t i u m i s o t o p e data f o r v o l c a n i c a r c s , DICKINSON (1970) observed the mean SR87/Sr86 r a t i o f o r the a n d e s i t i c s u i t e s from the Marianas, New B r i t a i n , Izu I s l a n d s , Cascade Range, and C e n t r a l America to be c l e a r l y w i t h i n the range f o r o c e a n i c i s l a n d b a s a l t s . C r u s t a l contamination would be r e f l e c t e d by s i g n i f i c a n t l y h i g h e r v a l u e s , s u g g e s t i n g t h a t such a process i s e i t h e r very minor or completely n o n e x i s t e n t i n these cases. Sharp c o n t r a r y evidence, however, has been p r o v i d e d by h i g h e r Sr87/Sr86 r a t i o s o b t a i n e d f o r a n d e s i t e s from o t h e r a r e a s , p a r t i c u l a r l y New Zealand (EWART and STIPP, 1968; DICKINSON, 1970). C. A n o r t h o s i t e s , C a r b o n a t i t e s and A l k a l i n e I n t r u s i v e s Since the Sr87/Sr86 r a t i o s f o r most a n o r t h o s i t e s and c a r b o n a t i t e s and a s s o c i a t e d a l k a l i n e i n t r u s i v e s f a l l i n the range o b t a i n e d f o r c o n t i n e n t a l b a s a l t s , i t has been suggested 105 t h a t these rocks are d e r i v e d from a s i m i l a r magma source (HEATH, 1967; POWELL, 1966). However, there appears to be some s i g n i f i c a n c e to the f a c t t h a t some c a r b o n a t i t e s have y i e l d e d vary low i s o t o p i c r a t i o s , s i m i l a r to those c h a r a c t e r -i z i n g t h o l e i i t i c b a s a l t s . But, as i n the case of c o n t i n e n t a l b a s a l t s , i t has not been p o s s i b l e to d e c i p h e r a reasonable p a t t e r n f o r the v a r i a t i o n s observed i n the r a t i o s of these p l u t o n i c r o c k s . D. U l t r a m a f i c and R e l a t e d Rocks Some d i s c u s s i o n of the v a r i a t i o n s observed i n the s t r o n t i u m i s o t o p i c r a t i o s of u l t r a m a f i c rocks was i n c l u d e d i n t a b l e XVI. As i n d i c a t e d i n t a b l e XVII, the r a t i o s f a l l i n t o a t l e a s t two d i s t i n c t groups : a s e t of v a l u e s around 0.709 to 0.711 f o r o c e a n i c u l t r a m a f i c s and a l p i n e - t y p e i n t r u s i o n s ; and a d i s t i n c t l y lower grouping around 0.705 to 0.706 f o r u l t r a m a f i c rocks from c o n c e n t r i c a l l y zoned bod i e s , the nodules i n a l k a l i b a s a l t s , and from the b a s a l l a y e r e d zones i n major i n t r u s i o n s . The u l t r a m a f i c i n c l u s i o n s i n k i m b e r l i t e s y i e l d s t r o n t i u m i s o t o p i c r a t i o s t h a t p l a c e somewhere i n between the two groups. More d e t a i l e d o b s e r v a t i o n s concerning the s i g n i f -i c a n c e of the r a t i o v a r i a t i o n s f o l l o w , with i n d i v i d u a l c o n s i d -e r a t i o n g i v e n to each type of u l t r a m a f i c occurrence. 1. Oceanic U l t r a m a f i c Rocks The o c e a n i c u l t r a m a f i c rocks i n c l u d e dredged bottom-s u r f a c e samples as w e l l as s u r f a c e rocks from o c e a n i c i s l a n d s , 106 and s t i l l o t h e r s o b t a i n e d from d r i l l - c o r e r e p r e s e n t i n g depths of up t o 300 m. The rocks e x h i b i t a broad range o f u l t r a m a f i c compositions and v a r y i n g degrees of a l t e r a t i o n i n the form of m y l o n i t i z a t i o n and s e r p e n t i n i z a t i o n . The s t r i k i n g d i f f e r e n c e i n i s o t o p i c r a t i o s y i e l d e d by the u l t r a m a f i c rocks on the one hand, and t h e i r a s s o c i a t e d b a s a l t i c and gabbroic rocks on the oth e r , b e t r a y a d i s t i n c t ^ i s s i m i L a r i t y i n parent magma of these two rock groups. As w i l l be expounded and r e f i n e d l a t e r , the w r i t e r proposes t h a t indeed the b a s a l t s and gabbros r e p r e s e n t a magma source d i f f e r e n t from t h e i r now-adjacent u l t r a m a f i c c o u n t e r p a r t s , the former from a deep-mantle r e s e r v o i r . An odd group of u l t r a m a f i c rocks c o n s i s t s o f the p e r i d o t i t e s o b t a i n e d from the St. Peter and S t . Paul Rocks of the c e n t r a l A t l a n t i c Ocean. With a few ex c e p t i o n s , these samples y i e l d r a t i o s c l o s e r t o those o f the b a s a l t s , r a t h e r than t h e i r o t h e r o c e a n i c u l t r a m a f i c c o u n t e r p a r t s . P e t r o l o g i c a l s t u d i e s i n d i c a t e the presence o f s e v e r a l types o f p e r i d o t i t e s among these r o c k s , w i t h perhaps the m a j o r i t y of the analyzed samples r e p r e s e n t i n g the same parent m a t e r i a l as the o v e r l y i n g b a s a l t s — as c e r t a i n l y suggested by the f r e q u e n t l y observed cumulate t e x t u r e s seen i n these p e r i d o t i t e s (BONATTI e t a l , 1970). Indeed, i n the case o f the p e r i d o t i t e s analyzed by HART (1964), two d i s t i n c t groups of Rb/Sr and Sr87/Sr86 r a t i o s were obta i n e d , perhaps r e p r e s e n t i n g two d i f f e r e n t magma sources. 2. Alpine-Type U l t r a m a f i c I n t r u s i o n s 107 As i n the case of the oceanic u l t r a m a f i c s , the s t r o n t -ium i s o t o p i c r a t i o s here c l e a r l y suggest an independent o r i g i n f o r the u l t r a m a f i c rocks and t h e i r a d j a c e n t l y - o c c u r r i n g b a s a l t i c c o u n t e r p a r t s . The numerous samples from v a r i o u s world-wide occurrences r e p r e s e n t i n g t h i s g e o l o g i c a l s e t t i n g , u nquestionably e s t a b l i s h t h i s g e n e t i c d i f f e r e n c e . Only one value l e s s than 0.706 has emerged f o r the u l t r a m a f i c rocks from t h i s type of environment, w h i l e the a s s o c i a t e d b a s a l t i c rocks p e r s i s t e n t l y y i e l d r a t i o s around 0.704. Once again, the range of analyzed u l t r a m a f i c rocks encompasses extreme degrees of s e r p e n t i n i z a t i o n and i n i t i a l u l t r a m a f i c mineralogy, as i n d i c a t e d i n t a b l e XVI. 3. C o n c e n t r i c a l l y - Z o n e d U l t r a m a f i c Bodies In marked c o n t r a s t to the ocea n i c u l t r a m a f i c rocks and those from a l p i n e - t y p e i n t r u s i o n s , the c o n c e n t r i c a l l y - z o n e d u l t r a m a f i c bodies y i e l d samples w i t h low s t r o n t i u m i s o t o p i c r a t i o s averaging 0.7057, not much hi g h e r than t h a t of t h e i r e n c i r c l i n g g a bbroic and b a s a l t i c rocks ( t a b l e XVII). I t i s p o s t u l a t e d t h a t the source of the u l t r a m a f i c magma i n these cases i s i n the c o n t i n e n t a l upper mantle, d i s t i n c t l y d i f f e r e n t from the oceanic upper mantle source t h a t s u p p l i e s the oc e a n i c and a l p i n e - t y p e u l t r a m a f i c s . As w i l l be shown i n the next chapter, i t i s q u i t e p o s s i b l e f o r the ocea n i c upper mantle t o provide the parent magma f o r some of these c o n c e n t r i c a l l y - z o n e d b o d i e s , and t h i s perhaps e x p l a i n s the hig h s t r o n t i u m r a t i o s sometimes obtained, such as f o r the Tulameen complex of B r i t i s h 108 Columbia, Venezuela's T i n a q u i l l o body, and the rocks from the U r a l Mountains. 4. U l t r a m a f i c Nodules i n A l k a l i B a s a l t s The u l t r a m a f i c x e n o l i t h s found i n a l k a l i b a s a l t s y i e l d an average s t r o n t i u m i s o t o p i c r a t i o o f 0.7057, not extremely, although perhaps s i g n i f i c a n t l y , d i f f e r e n t from the mean value 0.7034 ob t a i n e d f o r t h e i r h o s t s . C e r t a i n l y the i s o t o p i c data i n d i c a t e a g e n e t i c a f f i n i t y between these u l t r a m a f i c s and those found i n c o n c e n t r i c a l l y zoned b o d i e s , r a t h e r than w i t h the u l t r a m a f i c rocks of the f i r s t two environments d i s c u s s e d . A few h i g h r a t i o s , t r e n d i n g toward the range of va l u e s e x h i b i t e d by the ocea n i c and a l p i n e - t y p e u l t r a m a f i c s , have been obtained f o r some u l t r a m a f i c nodules. As can be seen from t a b l e XVI, these h i g h v a l u e s i n v a r i a b l y occur i n nodules found i n o c e a n i c i s l a n d s . T h i s f i t s the hyp o t h e s i s t h a t these p a r t -i c u l a r nodules r e p r e s e n t a magma o r i g i n a t i n g i n the ocea n i c upper mantle, which i s a l s o the proposed - r e s e r v o i r f o r the dredged o c e a n i c u l t r a m a f i c s and the a l p i n e - t y p e i n t r u s i o n s . S e v e r a l l o c a l i t i e s y i e l d nodules w i t h two d i s t i n c t groups o f Sr87/Sr86 r a t i o s . T h i s a p p l i e s t o the s p i n e l p e r i d -o t i t e x e n o l i t h s o f the Massif C e n t r a l i n France (LEGGO and HUTCHINSON, 1968); the u l t r a m a f i c i n c l u s i o n s of the Lashaine volcano i n Tanzania (HUTCHINSON and DAWSON, 1970); and the r e d -s p i n e l l h e r z o l i t e on the one hand, and g r e e n - s p i n e l l h e r z o l i t e s on the oth e r , from Bandera C r a t e r , New Mexico. I t i s p o s t u l a t e d t h a t such cases i n v o l v e the tapping o f two d i s t i n c t u l t r a m a f i c 109 r e s e r v o i r s , an oce a n i c upper mantle and a c o n t i n e n t a l upper mantle. 5. U l t r a m a f i c I n c l u s i o n s i n K i m b e r l i t e s The mean value o b t a i n e d f o r the i n i t i a l s t r o n t i u m r a t i o s of k i m b e r l i t e s i s 0.7075 (ta b l e XVI). In many cases, the high v a l u e s are due t o extreme whole-rock a l t e r a t i o n , and a s s i m i l a t i o n of g r a n i t i c m a t e r i a l . However, i n g e n e r a l , i t seems t h a t the i s o t o p i c r a t i o s f o r k i m b e r l i t e s are d i s t i n c t l y h i g h e r than those o b t a i n e d f o r most c o n t i n e n t a l b a s a l t s , and so a s i m i l a r magmatic source i s not suggested. N e v e r t h e l e s s , a t t e n t i o n must be drawn to BERG and ALLSOPP"s (1972) study where a s e t of both f r e s h and a l t e r e d k i m b e r l i t e s was analyzed, the former y i e l d i n g s t r o n t i u m r a t i o s around 0.7040, while the l a t t e r produced s i g n i f i c a n t l y h i g h e r v a l u e s of about 0.7070. Th i s suggests t h a t perhaps i f many more f r e s h k i m b e r l i t e s were analyzed, the s t r o n t i u m r a t i o s f o r t h i s type of u l t r a m a f i c occurrence may i n f a c t t u r n out to be i n the same range as f o r most c o n t i n e n t a l b a s a l t s , thus i n s i n u a t i n g an i d e n t i c a l r e s e r v o i r source. 6. Layered U l t r a m a f i c Zones i n Major I n t r u s i o n s U l t r a m a f i c rocks from a g r e a t v a r i e t y of the world's major i n t r u s i v e complexes give a mean i n i t i a l s t r o n t i u m i s o t o p i c r a t i o of 0.7058. The few i n s t a n c e s where l e s s - m a f i c r e l a t e d rocks o f these bodies were a l s o analyzed i n d i c a t e the absence of i s o t o p i c d i f f e r e n c e s between the u l t r a m a f i c s and t h e i r 110 c o u n t e r p a r t s . I t can s a f e l y be concluded t h a t the chemical system t h a t s u p p l i e s the magma f o r these bodies i s the same source as t h a t o f most u l t r a m a f i c nodules and c o n t i n e n t a l b a s a l t s , as w e l l as the m a j o r i t y of the c o n c e n t r i c a l l y zoned u l t r a m a f i c bodies and i n c l u s i o n s i n k i m b e r l i t e s — t h a t i s , a c o n t i n e n t a l upper mantle system. C l e a r l y these u l t r a m a f i c environments c o l l e c t i v e l y i n d i c a t e a much lower range of s t r o n t -ium i s o t o p i c r a t i o s , and hence a d i f f e r e n t magmatic source than t h a t of the oce a n i c u l t r a m a f i c s and a l p i n e - t y p e i n t r u s i o n s . 7. Summary of the P e t r o g e n e t i c I m p l i c a t i o n s of the I s o t o p i c  V a r i a t i o n s i n U l t r a m a f i c Rocks I n i t i a l s t r o n t i u m i s o t o p i c r a t i o s c l e a r l y imply t h a t there i s no contemporary g e n e t i c a f f i n i t y between the oce a n i c u l t r a m a f i c rocks and a l p i n e - t y p e u l t r a m a f i c i n t r u s i o n s on the one hand, and the u l t r a m a f i c rocks from the zoned p l u g - l i k e i n t r u s i o n s , s t r a t i f o r m d i f f e r e n t i a t e s , nodules i n a l k a l i b a s a l t s , and f r e s h k i m b e r l i t e s . I t i s p o s t u l a t e d t h a t the u l t r a m a f i c rocks of the former group o r i g i n a t e i n an oceanic upper mantle, while those o f the l a t t e r group have a c o n t i n e n t a l upper mantle r e s e r v o i r as t h e i r source. The c o n t i n e n t a l upper mantle i s recommended t o be the same chemical system t h a t y i e l d s b a s a l t s and most other c o n t i n e n t a l magmatic r o c k s . However o c e a n i c b a s a l t s , p a r t i c u l a r l y the t h o l e i i t i c type, are b e l i e v e d to o r i g -i n a t e i n the lower or deep mantle from a r e s e r v o i r d i s t i n c t l y d i f f e r e n t from the oce a n i c upper mantle t h a t produces t h e i r a s s o c i a t e d u l t r a m a f i c r o c k s . More exact c h a r a c t e r i s t i c s of I l l these chemical systems w i l l be p o s t u l a t e d i n d e t a i l i n the next chapter. STUEBER and MURTHY (1966) c l a i m t h a t the h i g h Sr87/ Sr86 r a t i o s i n the a l p i n e u l t r a m a f i c s , which appear to be r e s i d u a l i n nature, r e q u i r e a two-stage e v o l u t i o n — based on the f a c t t h a t the rubidium content of these u l t r a m a f i c s i s not s u f f i c i e n t f o r the growth of the high s t r o n t i u m r a t i o s s i n c e the time of formation of the e a r t h . They suggest t h a t d u r i n g an i n t e r m e d i a t e stage between core formation (4.5 by ago) and c r u s t f o r m a t i o n (at 3.5 b y ) , i n which the upper mantle was e n r i c h e d i n rubidium, the r a d i o g e n i c s t r o n t i u m i n what i s now the a l p i n e u l t r a m a f i c r e s i d u a l l a y e r grew to n e a r l y i t s p r e s e n t abundance ( f i g u r e 7). Subsequent c r u s t a l d i f f e r e n t i a t i o n lowered the rubidium content of t h i s r e s i d u a l zone, but r e t a i n e d the h i g h Sr87/Sr86 r a t i o . Thus these authors have an a l p i n e -type u l t r a m a f i c r e s i d u e e x i s t i n g o n l y below the s i a l i c c r u s t ( f i g u r e 8). Such a model i s however not compatible w i t h the lower Sr87/Sr86 r a t i o s o b t a i n e d f o r other c o n t i n e n t a l u l t r a -m afic r o c k s . Based on the h i g h r a t i o s o b t a i n e d f o r u l t r a m a f i c rocks dredged from the deep f r a c t u r e zones i n t e r s e c t i n g the M i d - A t l a n t i c Ridge, BONATTI et. a l (1970) l i k e w i s e propose a zone of r e s i d u a l a l p i n e - t y p e p e r i d o t i t i c m a t e r i a l , l e f t over s i n c e the d i f f e r e n t i a t i o n of a s i a l i c c r u s t . However, they promote the h i g h l y u n l i k e l y s i t u a t i o n where the a l p i n e p e r i d -o t i t e zone has somehow p e r s i s t e d i n the upper mantle below the e q u a t o r i a l M i d - A t l a n t i c Ridge, having been formed as a r e s i d u a l 112 of p r e - d r i f t c o n t i n e n t a l d i f f e r e n t i a t i o n ( f i g u r e 9 ) . B o n a t t i f u r t h e r c i t e s the l a c k of r e c o v e r i e s of p e r i d o t i t e s from f r a c t -ure zones i n the e a s t P a c i f i c as s i g n i f y i n g t h a t a s i a l i c c r u s t never e x i s t e d i n the e a s t P a c i f i c , and thus the r e s i d u a l p e r i d -o t i t e zone d i d not develop i n the mantle t h e r e . However, p e r i d -o t i t e s have i n f a c t been dredged from the f r a c t u r e zones of the e a s t P a c i f i c (THOMLINSON, 1972; see a l s o HAWKINS e t al, 1972; and HEEZEN e t a l , 1966). The p o s s i b i l i t y t h a t the h i g h Sr87/Sr86 r a t i o s i n a l p i n e - t y p e and o c e a n i c u l t r a m a f i c s are simply the r e s u l t of s e r p e n t i n i z a t i o n has been c o n s i d e r e d . However, prime evidence a g a i n s t such a form of contamination l i e s i n the f a c t t h a t most of these u l t r a m a f i c s (both whole-rocks and m i n e r a l separates) have s t r o n t i u m r a t i o s h i g h e r than t h a t of sea-water (about 0.709). Furthermore, the g r e a t number of t o t a l l y u n s e r p e n t i n -i z e d u l t r a m a f i c samples y i e l d i n g very h i g h Sr87/Sr86 r a t i o s (see t a b l e XVI) negates such a form of a l t e r a t i o n as the major c o n t r i b u t o r t o the anomalously h i g h v a l u e s . 113 Core Mojor Crustal Formot ion Formation 3 0 2 0 Time (b.y.) F i g u r e 7. H y p o t h e t i c a l Sr87/Sr86 development i n a l p i n e - t y p e u l t r a m a f i c m a t e r i a l according to STUEBER and MURTHY (1966). P r i m a r y Mant le Ma te r i a l garnet pe r i do t i t e ( ? ) P y r o l i t e (?). Figure 8. STUEBER and MURTHY1s (1966) proposed r e l a t i o n s h i p s of u l t r a m a f i c rocks to present mantle-crust s t r u c t u r e . Figure 9. BONATTI e t a l ' s (1970) schematic and q u a l i t a t i v e model of the c r u s t and upper mantle i n the e q u a t o r i a l A t l a n t i c . A zone of upper mantle enriched i n r e s i d u a l , a l p i n e - t y p e p e r i d -o t i t e i s in t r u d e d by r i s i n g b a s a l t i c m a t e r i a l below the a x i s of the r i d g e , r e s u l t i n g i n the formation of a p e r i d o t i t e - g a b b r o -b a s a l t complex. 114 V I I . A MODEL FOR THE DEVELOPMENT OF THE CHEMICAL SYSTEMS: OF  THE EARTH'S CRUST AND MANTLE DEFINED BY RADIOGENIC  STRONTIUM DISTRIBUTION A. D e f i n i t i o n of the Earth ' s Major Chemical R e s e r v o i r s The concept of g l o b a l - or p l a t e - t e c t o n i c s allows a new d e f i n i t i o n o f the chemical systems of the e a r t h ' s c r u s t and mantle. No longer can a petrochemist r e s t r i c t h i m s e l f t o o n l y two c l o s e d systems — the c r u s t and the mantle. Four d i s t i n c t magmatic r e s e r v o i r s are d e f i n e d i n the model presented here : the c o n t i n e n t a l c r u s t , the c o n t i n e n t a l upper mantle, the o c e a n i c upper mantle, and the lower o r deep mantle. The dimensions of the r e s e r v o i r s are shown i n t a b l e XVIII. P a r t i c u l a r a t t e n t i o n i s drawn t o the d e f i n i t i o n s of the " c o n t i n e n t a l upper mantle" system which i s r e s t r i c t e d to the r i g i d non-convecting s u b - s i a l i c l i t h o s p h e r i c p l a t e s , and the "oceanic upper mantle" system which i n c l u d e s the s u b - l i t h o s p h e r i c c o n v e c t i n g upper mantle below c o n t i n e n t a l a r e a s . The c h a r a c t e r i s t i c Sr87/Sr86 r a t i o s of the major systems have been b r i e f l y d i s c u s s e d i n the p r e v i o u s chapter, and are l i s t e d i n t a b l e XIX. A l s o o u t l i n e d i n t h i s t a b l e are the reasons f o r the development of the c h a r a c t e r i s t i c i s o t o p i c v a l u e s of these r e s e r v o i r s ; these reasons are more e l a b o r a t e l y presented l a t e r i n t h i s paper. With r e s p e c t to magma supply, i t i s proposed t h a t the oceanic upper mantle i s the source f o r most of the ocean-ridge u l t r a m a f i c r o c k s , a l p i n e - t y p e u l t r a m a f i c i n t r u s i o n s , and those RESERVOIR DESCRIPTION , VOLUME DENSITY MASS (cnw) x IO^D (gm/cmJ) (gm) x 10^° A. Lower (deep) mantle non-convecting global-wide deep mantle, from depths of about 700 km down to the core boundary a t 2900 km; a l s o r e p r e s -ented by the t h i n s u r f a c e l a y e r of oceanic c r u s t 5.898 4.80 28.310 B. Oceanic upper mantle C o n t i n e n t a l upper mantle e n t i r e c o n v e c t i n g upper mantle i n oceanic areas, to a depth not exceeding 700 km. A l s o i n c l u d e s the s u b - l i t h o s p h e r i c con-v e c t i n g upper mantle of c o n t i n e n t a l areas uppermost mantle i n c o n t i n e n t a l areas; l i m i t e d t o the s u b - s i a l i c l i t h o s p h e r i c p l a t e s w i t h a depth of about 150 km. Considered a r i g i d non-convecting zone, having no mass interchange with the c o n v e c t i n g mantle below or the o v e r l y i n g c r u s t 2.947 0.2155 3.75 3.42 11.053 0.7370 D. C o n t i n e n t a l c r u s t s i a l i c c r u s t c o v e r i n g 1/3 of the earth's s u r f a c e , extending to an average depth of 35 km 0.0595 2.85 0.1696 (core) ( t o t a l e arth) 1.758 10.878 11.25 5.52 19.774 60.047 Table XVIII. Dimensions of the e a r t h ' s major chemical r e s e r v o i r s , as d e f i n e d i n the r a d i o -g enic s t r o n t i u m e v o l u t i o n model. CHEMICAL SYSTEM/RESERVOIR SR87/SR86 RATIOS REASONS FOR CHARACTERISTIC ISOTOPIC VALUES A. Lower (deep) mantle 0.701 to 0.703 B. Oceanic upper mantle 0.707 t o 0.715 C. C o n t i n e n t a l upper mantle 0.703 to 0.706 D. C o n t i n e n t a l c r u s t 0.701 to 0.730+ - the low values are a r e s u l t o f severe d e p l e t -i o n o f Rb r e l a t i v e t o Sr d u r i n g the e a r l y formation of the p r o t o - c r u s t or upper-mantle - high Sr87/Sr86 due to a very e a r l y ( p r e - s i a l i c c r u s t formation) d i f f e r e n t i a t i o n t h a t produced a global-wide p r o t o - c r u s t w i t h h i g h Rb content - Rb/Sr p r o p o r t i o n a l i t y has s i n c e been decreased due to s e l e c t i v e l o s s of Rb to the c o n t i n e n t a l c r u s t system, v i a p l a t e boundaries ( p a r t i c u l -a r l y subduction zones) - the Rb/Sr r a t i o was probably s l i g h t l y h i g h e r a t the time o f formation of the p r o t o - c r u s t , but underwent immediate subsequent d e p l e t i o n d u r i n g the e a r l y formation ( d i f f e r e n t i a t i o n ) of s i a l i c c r u s t - the Sr87/Sr86 r a t i o s are b e l i e v e d t o be very s i m i l a r t o the present-day t o t a l crust-mantle system - the high values are due to the p r e f e r r e d c o n c e n t r a t i o n of Rb over Sr i n t h i s system, by d i f f e r e n t i a t i o n processes throughout g e o l o g i c time Table XIX. Proposed d e f i n i t i o n of the e a r t h ' s major chemical systems, t h e i r Sr87/Sr86 r a t i o s , and reasons f o r these c h a r a c t e r i s t i c v a l u e s . 117 u l t r a m a f i c x e n o l i t h s w i t h h i g h Sr87/Sr86 r a t i o s found i n a l k a l i b a s a l t s . The c o n t i n e n t a l upper mantle i s suggested t o be the source o f the s t r a t i f i e d d i f f e r e n t i a t e s , most c o n c e n t r i c a l l y -zoned u l t r a m a f i c p l u g s , and the u l t r a m a f i c x e n o l i t h s w i t h low Sr87/Sr86 r a t i o s i n the range of t h e i r host b a s a l t s which are a l s o b e l i e v e d to o r i g i n a t e i n many cases w i t h i n t h i s system. I t i s proposed t h a t the deep mantle i s the source o f a l l o c e a n i c t h o l e i i t i c b a s a l t s , and the u l t i m a t e source of oceanic a l k a l i b a s a l t s as w e l l , although the l a t t e r group i s c o n s i d e r e d to r e f l e c t contamination by the ocea n i c upper mantle system — as w i l l be d i s c u s s e d l a t e r . A s i m i l a r deep mantle source may a l s o p r o v i d e the o r i g i n a l magmatic supply f o r most c o n t i n e n t a l bas-a l t s , although the o p p o r t u n i t i e s f o r contamination i n c o n t i n -e n t a l areas are f a r g r e a t e r than w i t h i n the sub-oceanic e n v i r o n -ment. As was e x p l a i n e d i n chapter VI, the s t r o n t i u m r a t i o s f o r a n o r t h o s i t e s , c a r b o n a t i t e s , and r e l a t e d a l k a l i n e i n t r u s i v e s do not r e v e a l any d i s t i n c t p a t t e r n , but i t i s q u i t e probable t h a t t h e i r magmatic source i s a l s o the deep mantle, w i t h p e r v a s i v e e f f e c t s of upper mantle contamination. The same o r i g i n c o u l d apply to the u l t r a m a f i c i n c l u s i o n s i n most " f r e s h " k i m b e r l i t e s , although the s u b - c o n t i n e n t a l "oceanic upper mantle" system may be a s i g n i f i c a n t c o n t r i b u t o r here. The c o n t i n e n t a l c r u s t system w i t h i t s s i a l i c rocks and c h a r a c t e r i s t i c a l l y broad range o f Sr87/Sr86 r a t i o s i n v a r -i a b l y does a c t as a d i r e c t magma s u p p l i e r , but i t s more import-ant r o l e i s b e l i e v e d to be one of contamination of magma o r i g -i n a t i n g i n the systems below i t . As d i s c u s s e d i n chapter VI, the c o n t r i b u t i o n made by t h i s r e s e r v o i r to the v o l c a n i c rocks 118 of i s l a n d - a r c areas has been the t o p i c o f abundant i s o t o p i c and p e t r o g e n e t i c s t u d i e s . An a d d i t i o n a l chemical system, not i n c l u d e d i n t h i s model i s the hydrosphere. Although not a source of magma, t h i s system w i t h a c u r r e n t Sr87/Sr86 r a t i o of 0.709, makes s i g n i f -i c a n t c o n t r i b u t i o n s t o metamorphic processes through hydrous i s o t o p i c exchange mechanisms. I t a l s o d i c t a t e s the s t r o n t i u m i s o t o p i c r a t i o s of limestones and other p r e c i p i t a t e s t h a t form w i t h i n i t s environment. With i t s r e l a t i v e l y s m a l l mass of strontium, the hydrosphere c o u l d simply be c o n s i d e r e d a sub-system w i t h i n the c o n t i n e n t a l c r u s t r e s e r v o i r . B. D i s c u s s i o n : F u r t h e r C h a r a c t e r i s t i c s of the Chemical  Systems, T h e i r Products, and T h e i r Strontium I s o t o p i c  Development wi t h Time The model o f f e r s three new suggestions as to the i n t e r p r e t a t i o n of Sr87/Sr86 v a r i a t i o n s : (1) an a l p i n e - t y p e u l t r a m a f i c zone c o n s t i t u t i n g p r i m a r i l y the oc e a n i c , r a t h e r than the c o n t i n e n t a l , upper mantle; (2) a common deep mantle source f o r both oceanic t h o l e i i t e s and a l k a l i n e b a s a l t s ; and (3) the p o s s i b i l i t y of a t l e a s t two, and p o s s i b l y t h r e e , d i s t -i n c t r e s e r v o i r s c o n t r i b u t i n g to igneous a c t i v i t y from d i r e c t l y below the c o n t i n e n t a l c r u s t . The i d e a t h a t the ocea n i c upper mantle might be the zone of high Sr87/Sr86 r a t i o s , c h a r a c t e r i s t i c of a l p i n e - t y p e u l t r a m a f i c s , was o r i g i n a l l y formulated by the w r i t e r i n d i s -c u s s i o n s w i t h R.D. Hyndman. The i n t e r p r e t a t i o n by STUEBER and 119 MURTHY (1966) and BONATTI e t a l (1970) t h a t a r a d i o g e n i c s t r o n t i u m - e n r i c h e d a l p i n e u l t r a m a f i c r e s i d u a l l a y e r l i e s below c o n t i n e n t a l c r u s t (see f i g u r e s 8 and 9) i s s t r i k i n g l y c o n t r a d -i c t o r y t o the o b s e r v a t i o n of low r a d i o g e n i c s t r o n t i u m c ontents i n the s t r a t i f i e d d i f f e r e n t i a t e s of major i n t r u s i v e complexes, the zoned p l u g - l i k e u l t r a m a f i c i n t r u s i o n s , and most u l t r a m a f i c i n c l u s i o n s i n c o n t i n e n t a l b a s a l t s and k i m b e r l i t e s . Obviously the r e s e r v o i r s u p p l y i n g these o t h e r u l t r a m a f i c rocks i s d i s t i n c t -l y d i f f e r e n t from the zone of h i g h Sr87/Sr86 a l p i n e p e r i d o t i t e s . The f a c t t h a t h i g h s t r o n t i u m r a t i o s have been o b t a i n e d f o r ocean-ridge u l t r a m a f i c s supports the i d e a t h a t the o c e a n i c upper mantle i s the a l p i n e u l t r a m a f i c zone. A l l the a l p i n e -type i n t r u s i o n s are found emplaced w i t h i n o r o g e n i c b e l t s a d j a c -ent to c o n t i n e n t a l margins. These oro g e n i c b e l t s can a l l be r e l a t e d t o p r e s e n t or p a s t subduction/obduction zones, w i t h the s u r f a c e t r a n s f e r of o c e a n i c upper mantle m a t e r i a l e a s i l y p o s s i b l e , as per suggestions by DIETZ (1963) and by a m u l t i t u d e of other r e c e n t authors (e.g. COLEMAN, 1971) on the b a s i s of p l a t e t e c t o n i c theory. The few u l t r a m a f i c i n c l u s i o n s t h a t have been found t o possess Sr87/Sr86 v a l u e s approaching the range of a l p i n e u l t r a -m afic i n t r u s i o n s are a l l from oc e a n i c a l k a l i b a s a l t s t h a t are presumed to have i n c o r p o r a t e d the x e n o l i t h s w h i l e p a s s i n g through the o c e a n i c upper mantle r e s e r v o i r on t h e i r way to the s u r f a c e from t h e i r deep mantle source. S i g n i f i c a n t contamin-a t i o n by the h o s t b a s a l t s would e x p l a i n the i n c l u s i o n s ' s l i g h t l y lower Sr87/Sr86 v a l u e s which are, however, d i s t i n c t l y h i g h e r 120 than the r a t i o s o b t a i n e d f o r the u l t r a m a f i c nodules c o n t a i n e d i n most c o n t i n e n t a l b a s a l t s and f r e s h k i m b e r l i t e s . In the i n t e r e s t i n g case of the two d i s t i n c t assemblages of p e r i d o t i t e x e n o l i t h s found i n the b a s a l t i c rock o f the Mass i f C e n t r a l i n France (LEGGO and HUTCHISON, 1968), the assemblage w i t h the hi g h e r Sr87/Sr86 r a t i o s may r e p r e s e n t the oce a n i c a l p i n e u l t r a -mafic zone t h a t was subducted northward near the Mediterranean Sea as p a r t of the a n c i e n t Tethyan oceanic l i t h o s p h e r i c p l a t e ; w h i l e the lower s t r o n t i u m r a t i o s o f the other p e t r o l o g i c a l l y d i f f e r e n t assemblage may r e f l e c t the tapp i n g of the European c o n t i n e n t a l upper mantle r e s e r v o i r . The r a d i o g e n i c s t r o n t i u m e v o l u t i o n model presented here proposes the formation of a global-wide upper-mantle or p r o t o - c r u s t , p r o g r e s s i v e l y e n r i c h e d i n Rb87 and hence w i t h Sr87, d u r i n g the p e r i o d between core f o r m a t i o n (4.55 by) and i n i t i a l s i a l i c c r u s t a l f ormation (3.75 b y ) . Th i s process r e s u l t e d i n the cor r e s p o n d i n g d e p l e t i o n o f Rb r e l a t i v e t o Sr i n the deep mantle. D i f f e r e n t i a t i o n processes c r e a t i n g the c o n t i n e n t a l s h i e l d areas are b e l i e v e d to have o c c u r r e d almost e n t i r e l y w i t h i n the time p e r i o d from about 3.7 5 by to 2.50 by. During t h i s time, the areas o f the former " p r o t o - c r u s t " immediately below the newly formed c o n t i n e n t a l s h i e l d s underwent a severe r e d u c t i o n i n t h e i r Rb/Sr r a t i o , p r o v i d i n g the p r e s e n t c o n t i n -e n t a l upper mantle w i t h an i s o t o p i c c h a r a c t e r d i s t i n c t l y d i f f -e r e n t from the r e l a t i v e l y unchanged upper mantle i n o c e a n i c areas. The o c e a n i c upper mantle, meanwhile, has experie n c e d a f a i r l y s l i g h t but continuous decrease i n i t s Rb/Sr r a t i o s i n c e 121 the o r i g i n a l f ormation of the global-wide p r o t o - c r u s t , through i n t e r a c t i o n w i t h the c o n t i n e n t a l c r u s t and upper mantle systems. T h i s r e s e r v o i r y i e l d s magma wit h Sr87/Sr86 r a t i o s d i s t i n c t l y h i g h e r than t h a t o f the c o n t i n e n t a l upper mantle system and f a r above the range of va l u e s c h a r a c t e r i s t i c o f the global-wide deep-mantle system. I t i s proposed t h a t both the oc e a n i c t h o l e i i t e s and the a l k a l i b a s a l t s o r i g i n a t e i n the non-convecting lower mantle, a t a minimum depth of c l o s e t o 700 km. The primary deep mantle i s b e l i e v e d t o be f a i r l y homogeneous, with a Sr87/Sr86 r a t i o of l e s s than 0.702. T h o l e i i t e s tend to r e t a i n these low v a l u e s because o f t h e i r uncontaminated d i r e c t path to the c r u s t a l s u r f a c e . The a l k a l i b a s a l t s , on the other hand, are thought of as r e p r e s e n t i n g magma t h a t has been s i g n i f i c a n t l y contamin-ated by the upper mantle r e s e v o i r because of i t s time-delayed route t o the s u r f a c e , r a i s i n g the Sr87/Sr86 r a t i o t o a range of 0.703 to 0.706. The mechanisms suggested f o r the t r a n s f e r of magma from the v a r i o u s r e s e r v o i r s to the s u r f a c e are o u t l i n e d i n t a b l e XX. Lower mantle m a t e r i a l i s b e l i e v e d to r i s e t o the s u r f a c e by c o n v e c t i v e plumes, as proposed by MORGAN (1971, 1972). T h i s h y p othesis has deep-mantle magma r i s i n g a d i a b a t i c a l l y to upper-mantle l e v e l s where i t p a r t i a l l y f r a c t i o n a t e s i n t o a l i q u i d and a r e s i d u a l , the former immediately proceeding upward and e x t r u d i n g as t h o l e i i t i c b a s a l t . The r e s i d u a l m a t e r i a l f o l l o w s l a t e r , but o n l y a f t e r having been contaminated with the much hi g h e r r a d i o g e n i c content of the c o n v e c t i n g oceanic l i t h o s p h e r e -RESERVOIR SURFACE ROCK (MAGMA). TYPES MECHANISMS FOR MAGMA TRANSFER TO SURFACE B. ocean i c t h o l e i i t e s b a s a l t s oceanic a l k a l i b a s a l t s most c o n t i n e n t a l b a s a l t s u l t r a m a f i c i n c l u s i o n s i n " f r e s h " k i m b e r l i t e s a n o r t h o r i t e s , c a r b o n a t i t e s , and a l k a l i n e i n t r u s i v e s ocean-ridge u l t r a m a f i c rocks a l p i n e - t y p e u l t r a m a f i c i n t r u s i o n s some u l t r a m a f i c x e n o l i t h s i n a l k a l i b a s a l t s s t r a t i f i e d d i f f e r e n t i a t e s of -major i n t r u s i v e complexes most c o n c e n t r i c a l l y - z o n e d u l t r a m a f i c plugs some u l t r a m a f i c x e n o l i t h s i n a l k a l i b a s a l t s some c o n t i n e n t a l b a s a l t s s i a l i c " g r a n i t i c " rocks most s h i e l d metamorphic rocks oceanic t h o l e i i t e s r e p r e s e n t the l e a s t a l t e r e d magma, rea c h i n g the s u r f a c e by deep mantle plumes oceanic a l k a l i b a s a l t s f o l l o w an i n d i r e c t ( s p a t i a l and/or time) route t o the s u r f a c e , a l l o w i n g s i g n i f -i c a n t magmatic a s s i m i l a t i o n from the upper mantle system a l l the c o n t i n e n t a l rocks u s u a l l y i n v o l v e s i g n i f -i c a n t i n c o r p o r a t i o n of upper mantle m a t e r i a l as they approach the su r f a c e v i a plume-like c o n d u i t s oceanic u l t r a m a f i c s are exposed below b a s a l t i c c r u s t a l m a t e r i a l only a t the i n t e r s e c t i o n of the ri d g e with deep f r a c t u r e zones, and r a r e l y a t the base of the median r i f t v a l l e y a l p i n e - t y p e u l t r a m a f i c bodies are emplaced i n oro-genic b e l t s through the subduction o r obduction of oceanic l i t h o s p h e r i c p l a t e s u l t r a m a f i c nodules are i n c o r p o r a t e d w i t h i n i n t r u d i n g a l k a l i b a s a l t i c magma o r i g i n a t i n g i n the deep mantle system the major i n t r u s i v e complexes and b a s a l t s are the r e s u l t of simple igneous a c t i v i t y the zoned u l t r a m a f i c plugs r e f l e c t p a r t i a l m e l t i n g w i t h i n t h i s reservoir,, adjacent to subducted o c e a n i c l i t h o s p h e r i c p l a t e s u l t r a m a f i c x e n o l i t h s . are i n c l u d e d i n i n t r u d i n g b a s a l t i c magma o r i g i n a t i n g i n the deep mantle major source of d e t r i t a l m a t e r i a l f o r sedimentary rocks Table XX. Magmatic rock types s u p p l i e d by the eart h ' s major chemical r e s e r v o i r s , as d e f i n e d i n t a b l e XIX, and mechanisms f o r the t r a n s f e r of magma from each r e s e r v o i r t o the ea r t h ' s s u r f a c e . 123 asthenosphere system. T h i s i s c o n s i s t e n t w i t h the "cap rock" form of occurrence u s u a l l y e x h i b i t e d by the a l k a l i b a s a l t s of oceanic i s l a n d s , r e f l e c t i n g the l a t e s t stage o f v o l c a n i c c y c l e s . B r i e f p e t r o l o g i c a l c o n s i d e r a t i o n s of t h i s magmatic process appear i n a f o l l o w i n g s e c t i o n . C. Computer P l o t Model f o r Radiogenic Strontium E v o l u t i o n i n  the E a r t h ' s Major Chemical Systems A computer p l o t has been produced to i l l u s t r a t e the trends of r a d i o g e n i c s t r o n t i u m growth i n the e a r t h ' s major r e s e r v o i r s as d e f i n e d i n the chemical e v o l u t i o n model p r e s e n t e d here. Radiogenic s t r o n t i u m growth i s shown i n a p l o t o f Sr87/ Sr86 versus time ( f i g u r e 10). Three d i s t i n c t time p e r i o d s are co n s i d e r e d : (I) 4,550 my to 3,750 my; (II) 3,750 my to 2,500 my; and (III) 2,500 my to 0 (p r e s e n t ) . The rubidium-strontium data p r o v i d e d to the computer i s shown i n t a b l e XXI. A l s o shown i n t h i s t a b l e are the Sr8 7/ Sr86 val u e s r e t u r n e d by the computer. The a c t u a l computer program and output l i s t i n g of r a d i o g e n i c s t r o n t i u m growth i n each system f o r every 25 my i n t e r v a l are presented i n appendix I I . Reasons as to the chosen v a r i a t i o n s i n the Rb/Sr v a l u e s f o r the chemical systems are given i n the t e c t o n i c and i s o t o p i c notes accompanying the schematic r e p r e s e n t a t i o n s i n f i g u r e s 11a to l i e . F i g u r e s 12a to 12c show present-day magmatic a c t -i v i t y as envisaged i n the st r o n t i u m e v o l u t i o n model. 0.725 0.722 0.719 0.716 0.713 0.710 0.707 0.704 0.701 «?SR 8 6 SR _ -2UU0 TIME(MY) -jjO.698 CHEMICAL INITIAL FINAL INITIAL FINAL INITIAL FINAL SYSTEM TIME TIME RB/SR RB/SR SR87/SR86 SR87/SR86 I A I B II A II B II C II D VIII A I I I B I I I C I I I D 4 550 my 3750 2500 3750 my 2500 0.025 0.010 0.050 0.050 0.050 0.005 0.070 0.025 0.180 0.010 0.050 0.005 0.070 0.025 0.180 0.004 0.090 0.030 0.150 0.6990 II (0.6996) (0.7003) (0.7003) (0.7003) (0.7000) (0.7035) (0.7023) (0.7065) (0.6996) (0.7003) (0.7000) (0.7035) (0.7023) (0.7065) (0.7005) (0.7120) (0.7052) (0.7240) Table XXI. Rubidium-strontium data p r o v i d e d to the computer, and Sr87/Sr86 v a l u e s r e t u r n e d by the computer ( i n brackets) i n the p l o t of the model f o r the growth of r a d i o g e n i c s t r o n t i u m i n the chemical systems of the earth's c r u s t and mantle (see f i g u r e 10). The a c t u a l computer program and output data f o r every 25 my i n t e r v a l appear i n appendix I I . r - 1 M cn 1 2 6 127 F i g u r e s 11a to l i e . Schematic r e p r e s e n t a t i o n of the r a d i o g e n i c s t r o n t i u m model, d e p i c t i n g the chemical and t e c t o n i c e v o l u t i o n of the e a r t h ' s major magmatic r e s e r v o i r s , as d e f i n e d i n t a b l e s XVIII and XIX and f i g u r e 10. 11a: By 4,550 my - the p r i m o r d i a l s o l i d e a r t h . - formation of a dense core; probably a very r a p i d p r o c e s s . l i b : By 3,750 my - immediately f o l l o w i n g core f o r m a t i o n , and p o s s i b l y t r i g g -ered by i t : the d i f f e r e n t i a t i o n o f the mantle i n t o an upper-mantle or " p r o t o - c r u s t " and a lower- or deep-mantle; a global-wide process c o v e r i n g the time span of about 800 my. - geochemical tendencies f o r the c o n c e n t r a t i o n of " s i d e r o -p h i l e " elements i n the core, " c h a l c o p h i l e s " i n the lower mantle, and " l i t h o p h i l e s " i n the upper mantle. 11c: By 2,500 my - processes over the preceding 1,250 my r e s u l t i n the form-a t i o n of a l l s i a l i c c r u s t , c o v e r i n g about o n e - t h i r d of the e a r t h ' s s u r f a c e , and probably a t o n l y two major c e n t r e s ( " p r o t o - c o n t i n e n t s " ) . - the s i a l i c c r u s t , formed p r i m a r i l y by v e r t i c a l t r a n s p o r t / exchange, i s c h a r a c t e r i z e d by extreme hi g h c o n c e n t r a t i o n of l i t h o p h i l e elements (eg. Rb) r e l a t i v e t o c h a l c o p h i l e s (eg. Sr) - the upper mantle i n " c o n t i n e n t a l areas" (and, t o a l e s s e r degree, the e n t i r e upper mantle) i s g r e a t l y d e p l e t e d i n l i t h o p h i l e s . - an a d d i t i o n a l l e s s s i g n i f i c a n t process i s the p o s s i b l e s l i g h t f u r t h e r d i f f e r e n t i a t i o n of the lower mantle prod-u c i n g two or more " l a y e r s " , or more l i k e l y a simple grad-a t i o n a l i n c r e a s e , i n the c h a l c o p h i l e / l i t h o p h i l e (Rb/Sr) r a t i o with depth; however, c o n v e c t i o n c u r r e n t s appear not to a l l o w f o r any major d i f f e r e n t i a t i o n of t h i s s o r t . I I B II A I I I D I I I C I I I B I I I A l i e 129 F i g u r e s 11a to l i e (cont'd). l i d : At 2,500 my - no f u r t h e r "primary" formation of s i a l i c c r u s t . - formation of the l i t h o s p h e r e — i . e . e x t e r n a l g l o b a l p l a t e ( s ) . - non-1ithbsphere ( i . e . asthenosphere) p a r t of the c o n t i n -e n t a l upper mantle i s "open" and s u b j e c t to mixing w i t h the upper mantle of "oceanic" r e g i o n s which due to convect-ion/mixing i s r e l a t i v e l y c h e m i c a l l y homogeneous between l i t h o s p h e r e and asthenosphere p a r t s . - the l i t h o s p h e r e i s 100 to 150 km t h i c k ; the asthenosphere, c o n s t i t u t i n g the remaining p a r t of the mantle i s 300 to 500 km t h i c k . l i e :;• S h o r t l y a f t e r 2,500 my to Present - deep-seated v e r t i c a l processes p e r s i s t , but now g i v e r i s e to more dominant l a t e r a l movements. - plumes t r a n s p o r t m a t e r i a l from the deep-mantle to the s u r f a c e ; i n c o n t i n e n t a l areas, l i n e a r s e r i e s of plumes may cause the r i g i d l i t h o s p h e r e to s p l i t . - c o n v e c t i o n i s r e s t r i c t e d t o the upper mantle, decoupled a t the l i t h o s p h e r e - a s t h e n o s p h e r e boundary. - the c o n t i n e n t a l l i t h o s p h e r e i s r i g i d — i t s c r u s t and upper mantle systems remain e s s e n t i a l l y c h e m i c a l l y i s o l a t e d ; the lower (asthenosphere) p a r t of the upper mantle here i s s u b j e c t t o global-wide mixing w i t h the e n t i r e upper mantle of o c e a n i c areas. - the primary t h o l e i i t e of the o c e a n i c c r u s t r e p r e s e n t s the deep mantle system; the a l k a l i b a s a l t s r e p r e s e n t a mixture of deep mantle m a t e r i a l contaminated by the upper mantle system; most o c e a n i c u l t r a m a f i c rocks r e p r e s e n t s o l e l y the o c e a n i c upper mantle and hence are c h e m i c a l l y d i s t i n c t from the o c e a n i c b a s a l t s . - i n c o n t i n e n t a l areas, d i s t i n c t i o n between an upper mantle and a deep mantle source i s d i f f i c u l t because of complex contamination of the m a t e r i a l s b e f o r e r e a c h i n g the s u r f a c e . - e x t e n s i v e chemical exchange (mixing) between the l i t h o -sphere and the r e s t of the upper mantle occurs o n l y when the l i t h o s p h e r e i s subducted i n t o the asthenosphere, a process more or l e s s r e s t r i c t e d to oceanic p l a t e s . 130 131 F i g u r e s 12a to 12c. Schematic r e p r e s e n t a t i o n of t y p i c a l present-day i n t r a - p l a t e and plate-boundary magmatic a c t i v i t y , c o rresponding to the r a d i o g e n i c s t r o n t i u m e v o l u t i o n model proposed here. 12a: Oceanic and c o n t i n e n t a l i n t r a - p l a t e a c t i v i t y . - o c e a n i c : main magmatic source i s the deep mantle, w i t h v a r y i n g degrees of contamination by the upper mantle system ( t h o l e i i t e to a l k a l i b a s a l t ) ; some independant a c t i v i t y o r i g i n a t e s w i t h i n the upper mantle r e s e r v o i r . - c o n t i n e n t a l : three d i s t i n c t l y d i f f e r e n t mantle sources; however, d i f f i c u l t to d i s t i n g u i s h them because of f r e q -u e n t l y severe c r u s t a l contamination. 12b: Ocean-ridge spreading c e n t r e . - spreading c e n t r e i s the r e s u l t of a l i n e a r c h a i n o f "plumes" o r i g i n a t i n g i n the non-convecting lower (deep) mantle. - i f uncontaminated route t o s u r f a c e , the plumes extrude the deep mantle magma as "primary" t h o l e i i t i c b a s a l t . Magma contaminated by the upper mantle system i s e n r i c h e d i n l i t h o p h i l e s and takes the form of a l k a l i b a s a l t . - note: the ocea n i c c r u s t (above the Moho) c o n s i s t s o f the t y p i c a l " o p h i o l i t e " sequence w i t h a lower-most s e c t i o n of u l t r a m a f i c rock t h a t i s c h e m i c a l l y d i s t i n c t (deep mantle source) from the u l t r a m a f i c m a t e r i a l immediately under-l y i n g the Moho ( i . e . upper-most p a r t o f the upper mantle system). 12c: Oceanic p l a t e / c o n t i n e n t a l p l a t e convergence (subduction and a s s o c i a t e d o b d u c t i o n ) . - a v a r i e t y of i n t e r a c t i o n s producing u l t r a m a f i c hot i n t r u s -i o n s and c o l d emplacements, a n d e s i t i c volcanism, and melanges. 132 V I I I . CONCLUDING STATEMENT AND SUGGESTIONS FOR FURTHER WORK As mentioned a t the o u t s e t of t h i s t h e s i s , the model presented here f o r the development of the chemical systems of the e a r t h ' s c r u s t and mantle d e f i n e d by r a d i o g e n i c s t r o n t i u m d i s t r i b u t i o n i s c o n s i s t e n t w i t h the r e s t r a i n t s p r o v i d e d such g l o b a l e v o l u t i o n hypotheses by s e v e r a l o t h e r geochemical and g e o p h y s i c a l s t u d i e s . During the p r e p a r a t i o n o f t h i s t h e s i s , the author has independently w r i t t e n on the e a r t h ' s geochemical e v o l u t i o n w i t h r e s p e c t to potassium-rubidium r a t i o s , l e a d i s o t o p e s and r a r e -e a r t h element d i s t r i b u t i o n s . S i m i l a r s t u d i e s were made on t e r r -e s t r i a l heat flow p a t t e r n s and u l t r a m a f i c and ocea n i c p e t r o l o g y . So, w h i l e no d i r e c t r e f e r e n c e to these areas i s made here, they have indeed been c o n s i d e r e d i n f o r m u l a t i n g the g l o b a l e v o l u t i o n model f o r r a d i o g e n i c s t r o n t i u m . F u r t h e r development of t h i s model would undoubtedly i n v o l v e , as suggested by R.L. Armstrong, an a d d i t i o n a l numerical dimension i n the form of mass-balance c a l c u l a t i o n s f o r the Rb-Sr d i s t r i b u t i o n s i n the chemical r e s e r v o i r s . With r e s p e c t t o the l a b o r a t o r y a n a l y s e s , w h i l e i t i s b e l i e v e d t h a t a s i g n i f i c a n t c o n t r i b u t i o n has been made here, numerous suggestions can be p r o v i d e d f o r f u r t h e r work. B e t t e r l a b o r a t o r y f a c i l i t i e s w i l l soon p r o v i d e f o r c o n s i d e r a b l y more abundant r o u t i n e r a d i o m e t r i c analyses of u l t r a m a f i c r o c k s . T h i s would a l l o w f o r more d e t a i l e d examinations of p o s s i b l e v a r i a t -i o n s i n r a d i o g e n i c s t r o n t i u m d i s t r i b u t i o n s w i t h i n u l t r a m a f i c 133 b o d i e s . Furthermore, the way w i l l be paved f o r comparisons between the s t r o n t i u m i s o t o p i c r a t i o s f o r v a r i o u s u l t r a m a f i c bodies of d i f f e r e n t types of occurrence — the a l p i n e - t y p e and c o n c e n t r i c a l l y - z o n e d b o d i e s , as w e l l as the u l t r a m a f i c nodules found i n v a r i o u s r e g i o n s of the Canadian C o r d i l l e r a (see once again f i g u r e 1). 134 LITERATURE CITED A l l s o p p , H. L. 1965. Rb-Sr and K-Ar measurements on the Great Dyke of Southern Rhodesia : J . Geophys.'Res., v 70, p 977-984. A l l s o p p , H.L., L.O. N i c o l a y s e n , and P. Hahn-Weinheimer, 1969. 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Mtg., New D e l h i , 1964, Papers and Proc. New D e l h i , I n d i a , M i n e r a l . Soc. I n d i a , p 58-66. Powell, J.L. and S.E. DeLong, 1966. I s o t o p i c composition of 143 s t r o n t i u m i n volcanic rocks £xorn Oahu : Science, y 153, p 1239-1242. Powell, J.L., G. Faure and P.M. Hurley, 1965. Strontium 87 abundance i n a: s u i t e of Hawaiian v o l c a n i c rocks of v a r y i n g s i l i c a content : J . Geophys. Res., v 70, p 1509-1513. Pushkar, P. 1968. Strontium i s o t o p e r a t i o s i n v o l c a n i c rocks of three i s l a n d a r c areas : J . Geophys. Res., v 73, p 2701-2714. Ragan, D.M. 1963. Emplacement of the Twin S i s t e r s d u n i t e , Washington : Amer. J . S c i . , v 261, p 549-565. Ragan, D.M. 1967. The Twin S i s t e r s d u n i t e , Washington : In, U l t r a m a f i c and R e l a t e d Rocks (P.J. W y l l i e , e d i t o r ) , Wiley & Sons, New York, p 160-167. Roe, G.D. 1964. Rubidium-strontium analyses of u l t r a m a f i c rocks and the o r i g i n of p e r i d o t i t e s : MIT 12th Ann. Prog. Rept., p 159-190. Ryan, B.D. 1973. S t r u c t u r a l Geology and Rb-Sr Geochemistry of the A n a r c h i s t Mountain Area, South C e n t r a l B r i t i s h Columbia : Ph.D. t h e s i s , Univ. of B r i t i s h Columbia. S h i e l d s , R.M. 1964. The Rb87-Sr87 age of stony m e t e o r i t e s : Ph.D. t h e s i s , Mass. I n s t . Tech. S h i e l d s , W.R., E.L. Garner, C.E. Hedge and S.S. G o l d i c h , 1963. Survey of Rb85/Rb87 r a t i o s i n m i n e r a l s : J . Geophys. Res., v 68, p 2331-2334. St o c k w e l l , C.H. and committee, 1967. T e c t o n i c map of Canada, s c a l e 1:5,000,000 (approx. 1"=80 mi) : Geol. Surv. Can. manuscript map. Stueber, A.M. 1967. Potassium, rubidium, and s t r o n t i u m i n u l t r a -mafic rocks and m i n e r a l s : Carn. I n s t . Wash. Yearbook 66, p 42-44. Stueber, A.M. 1969. Abundances of K, Rb, Sr and Sr i s o t o p e s i n u l t r a m a f i c rocks and m i n e r a l s from western North C a r o l i n a : Geochim. Cosmochim. A c t a , v 33, p 543-553. 144 Stueber, A.M. and M. Ikramuddin, 1974. Rubidium, s t r o n t i u m and the i s o t o p i c composition of s t r o n t i u m i n u l t r a m a f i c nodule m i n e r a l s and host b a s a l t s : Geochim. Cosmochim. A c t a , v 38, p 207-216. Stueber, A.M. and V.R. Murthy, 1966. Strontium i s o t o p e and a l k a l i element abundances i n u l t r a m a f i c rocks : Geochim. Cosmochim. Ac t a , v 30, p 1243-1259. S t u l l , R.J. and T.E. Davis, 1973. Strontium i s o t o p i c and chem-i c a l composition of l h e r z o l i t e nodules and a l k a l i o l i v i n e b a s a l t from Malapai H i l l , C a l i f o r n i a ( a b s t r a c t ) : Geol. Soc. Amer. Abs. with Prog., v 5, p 113. S t u l l , R.J. and K. McMillan, 1973. O r i g i n of l h e r z o l i t e i n c l u s -i o ns i n the Malapai H i l l b a s a l t , Joshua Tree Monument, C a l i f -o r n i a : Geol. Soc. Amer. B u l l . , v 84, p 2343-2350. Tatsumoto, M., C.E. Hedge and A.E.J. Engel, 1965. Potassium, rubidium, s t r o n t i u m , thorium, uranium, and the r a t i o of strontium-87 to strontium-86 i n oceanic t h o l e i i t i c b a s a l t : Science, v 150, p 886-888. T a y l o r , H.P., J r . and J.A. Noble, 1960. O r i g i n of the u l t r a -mafic complexes i n southeastern A l a s k a : I n t ' l . Geol. Cong. 21st Sess. Rept., Pt. 13, p 175-187. Thomlinson, A. 19 72. P e r s o n a l communication, Univ. of B r i t i s h Columbia. Thompson, G.A. 1963. G e o p h y s i c a l i n v e s t i g a t i o n s a t Twin S i s t e r s , Washington ( a b s t r a c t ) : Geol. Soc. Amer. Spec. Paper 76, p 227-228. Vla s o v , K.A. ( e d i t o r ) , 1964. Geochemistry and mineralogy of r a r e elements and g e n e t i c types of t h e i r d e p o s i t s . Volume I I . Mineralogy of r a r e elements. T r a n s l a t e d by Z. Lerman (1966), I s r a e l Program f o r S c i e n t i f i c T r a n s l a t i o n s , Jerusalem. White, W.H. 1966. T e c t o n i c map of the Western C o r d i l l e r a , B r i t -i s h Columbia and neighbouring p a r t s of the U n i t e d S t a t e s s c a l e 1:2,534,000 (1" = 40 mi) : Can. I n s t . Min. and Met. Spec. V o l . 8, f i g . 10-1. 145 Whitney, P.R. and P.M. Hurley, 196 4. The problem of i n h e r i t e d r a d i o g e n i c s t r o n t i u m i n sedimentary.age det e r m i n a t i o n s : Geochim. Cosmochim. Ac t a , y 28, p .425-436. Wright, R.J. 1974. The Geology of the Pioneer U l t r a m a f i t e , B r a l o r n e , B.C. M.Sc. t h e s i s , Univ. of B r i t i s h Columbia. Zussman, J . , G.W. B r i n d l e y and J . J . Comer, 1957.. E l e c t r o n d i f f -r a c t i o n s t u d i e s o f s e r p e n t i n e m i n e r a l s : Amer. M i n e r a l o g i s t , v 42, p 133-153. 146 APPENDIX I. PETROGRAPHIC DESCRIPTIONS: OF ANALYZED ROCKS Hand-specimen and t h i n - s e c t i o n d e s c r i p t i o n s o f the analyzed u l t r a m a f i c r o c k s . The mode i n each case i s determined by t h i n - s e c t i o n v i s u a l e s t i m a t e s . A s t e r i s k s (*) i n d i c a t e the c o n f i r m a t i o n of m i n e r a l i d e n t i f i c a t i o n by x-ray d i f f r a c t i o n a n a l y s i s . Text r e f e r e n c e i s s e c t i o n IIIC2. SH-1 : s e r p e n t i n i t e macro' : grey-green i n c o l o u r w i t h a few enamel-like shear f a c e s ; p a l e green c l e a v a g e - s u r f a c e d b a s t i t e s conspicuous (see p l a t e I l a ) . micro' : rock i s t o t a l l y s e r p e n t i n i z e d ; o r i g i n a l o l i v i n e : e n s t a t i t e r a t i o approximately 4:1; pyroxene e x s o l u t i o n l a m e l l a e s t i l l p r e s e r v e d as r e l i c t t e x t u r e w i t h i n the b a s t i t e s , which are u s u a l l y 1 to 3 mm i n diameter; l i z a r d i t e has a mesh t e x t u r e r e s u l t i n g from randomly-oriented l a t h s , about 0.1 mm i n l e n g t h ; c h r y s o t i l e occurs as minor v e i n l e t s (see p l a t e I l i a ) ; a l l o r i g i n a l chromite converted t o magnetite. mode (%) : 95 s e r p e n t i n e (70 l i z a r d i t e * , 5 c h r y s o t i l e * , 20 b a s t i t e ( a n t i g o r i t e * ) ) ; t r a c e c h l o r i t e ; 3 magnetite*. SH-1' : s e r p e n t i n i t e macro' : as i n SH-1 micro' : as i n SH-1 mode (%) : 95 s e r p e n t i n e (65 l i z a r d i t e , 10 c h r y s o t i l e , 20 b a s t i t e ) ; t r a c e c h l o r i t e ; 3 magnetite. SH-2 : s e r p e n t i n i t e macro' : as i n SH-1 micro' : as i n SH-1; some of the b a s t i t e s appear t o have been c l i n o p y r o x e n e s , although orthopyroxene s t i l l dominates the o r i g i n a l rock; s e r p e n t i n e g r a i n s g e n e r a l l y appear s l i g h t l y c o a r s e r than i n SH-1; l i z a r d i t e l a t h s are about 0.15 mm i n le n g t h ; about h a l f the chromite has changed to magnetite, t h i s 147 a l t e r a t i o n being v e r y d i s t i n c t i n t h i n - s e c t i o n . mode (%) : 95 s e r p e n t i n e (65 l i z a r d i t e * , 10 c h r y s o t i l e , 20 b a s t i t e ) ; 5 chromite ( a l t e r i n g t o magnetite*). SH-3 : s e r p e n t i n i z e d h a r z b u r g i t e macro' : rock has a conspicuous checkered appearance w i t h l a r g e (commonly up to 0.5 cm) cream-green pyroxenes s e t w i t h i n a dark grey s e r p e n t i n e matrix ( p l a t e l i b ) . micro' : although the rock has a s i g n i f i c a n t c l i n o p y r o x e n e content, i t i s s t i l l c a l l e d a h a r z b u r g i t e because orthopyroxene dominates; c l i n o p y r o x e n e occurs mainly as s m a l l (0.5 mm) euhed-r a l c r y s t a l s rimming the l a r g e r (up to 0.5 cm) orthopyroxenes, a few of which have been a l t e r e d to b a s t i t e ; l i z a r d i t e r e p r e s -ents a l l the o r i g i n a l o l i v i n e t h a t once composed h a l f the rock. mode (%) : t r a c e o l i v i n e ; 20 orthopyroxene ( e n s t a t i t e * ) ; 10 cli n o p y r o x e n e ( d i o p s i d e * ) ; 60 s e r p e n t i n e (50 l i z a r d i t e * , 5 c h r y s o t i l e * , 5 b a s t i t e ) ; t r a c e b r u c i t e * ( ? ) ; 10 magnetite*. SH-3A : weathered s u r f a c e of SH-3; no t h i n - s e c t i o n made. In hand-specimen, most of the s e r p e n t i n e appears to have undergone secondary a l t e r a t i o n to t a l c and p o s s i b l y some carbonate ( p l a t e l i b ) . SH-4 : s e r p e n t i n i t e macro' : v a r i o u s shades of green, w i t h b a s t i t e s c l e a r l y v i s i b l e ; abundant enamel-like shear f a c e s ( p l a t e l i e ) . micro' : rock almost t o t a l l y s e r p e n t i n i z e d ; o r i g i n a l l y a h a r z -b u r g i t e w i t h an o l i v i n e : o r t h o p y r o x e n e r a t i o o f about 4:1; some of the b a s t i t e s appear t o have been c l i n o p y r o x e n e s ; s e r p e n t i n e ( l i z a r d i t e ) e x h i b i t s more of a " s t a i n e d g l a s s " t e x t u r e ( p l a t e I l l b ) , r a t h e r than o c c u r r i n g as mesh-like l a t h s (as i n p l a t e I l i a ) . mode (%) : t r a c e o l i v i n e ; 85 s e r p e n t i n e (60 l i z a r d i t e * , 10 c h r y s o t i l e * (?), 15 b a s t i t e ) ; 15 magnetite*. 148 SH-5 : h a r z b u r g i t e macro' : d u l l green c o l o u r w i t h c l e a r l y v i s i b l e pyroxenes w i t h i n what appears to be a s e r p e n t i n e matrix. micro' : rock i s much l e s s s e r p e n t i n i z e d than the hand-specimen i n d i c a t e s ; pyroxenes have not been a l t e r e d a t a l l ; the r a t i o o f orthopyroxene to cl i n o p y r o x e n e i s about 3:1; l i k e SH-3, the rock i s not f a r from being c a l l e d a l h e r z o l i t e ; d i o p s i d i c l a m e l l a e and b l e b s are commonly observed w i t h i n the e n s t a t i t e g r a i n s ; o r i g i n a l o l i v i n e : p y r o x e n e r a t i o not much above 1:1; about a t h i r d of the o l i v i n e has been s e r p e n t i n i z e d ; few f i b r o u s e r p e n t i n e ( c h r y s o t i l e ) v e i n l e t s present; •rock i s q u i t e c o a r s e -g r a i n e d , w i t h both pyroxene and o l i v i n e c r y s t a l s (the l a t t e r r e c o g n i z e d by o p t i c a l c o n t i n u i t y ( s i m i l a r e x t i n c t i o n ) of serp-e n t i n i z e d patches, commonly a t t a i n i n g diameters of 0.5 cm (see p l a t e I I I c ) . mode (%) : 40 o l i v i n e * ; 25 orthopyroxene ( e n s t a t i t e * ) ; 10 c l i n o pyroxene ( d i o p s i d e ) ; 20 s e r p e n t i n e (15 l i z a r d i t e * , 5 c h r y s o t i l e (?); 3 chromite. SH-6 : s e r p e n t i n i t e macro' : hand-specimen q u i t e s t r o n g l y magnetic; v e r y f i n e -g r a i n e d b l a c k rock, w i t h sub-conchoidal f r a c t u r e ( p l a t e l i d ) . m i c r o 1 : a very f i n e - g r a i n e d rock; i m p o s s i b l e t o decipher o r i g -i n a l mineralogy; p r e s e n t l y o n l y d i s s e m i n a t e d magnetite and se r p e n t i n e v i s i b l e ; s e r p e n t i n e appears to be mainly l i z a r d i t e , but p o s s i b l y some a n t i g o r i t e as w e l l , as suggested by x-ray d i f f r a c t i o n t r a c e s ; a few v e i n l e t s of f i b r o u s c h r y s o t i l e . mode (%) : 60 s e r p e n t i n e (50 l i z a r d i t e * , 10 c h r y s o t i l e , b a s t i t e ( ? ) ) ; 40 magnetite*. SH-7 : s e r p e n t i n i t e macro' : uniform dark grey c o l o u r w i t h n o t i c e a b l e t i n y (1 mm) t a l c needles ( p l a t e l i e ) . micro' : no o r i g i n a l mineralogy whatsoever, except f o r a few 149 t r a c e s of chromite not completely a l t e r e d to magnetite; e x t e n -s i v e s t e a t i z a t i o n evidenced by hig h t a l c content, i n the form of i r r e g u l a r l y r a d i a t i n g n e edles, w i t h a s s o c i a t e d magnesite and p o s s i b l y b r u c i t e ; c h l o r i t e accompanies the magnetite, o f t e n rimming i t (pl a t e IVa). mode (%) : 45 s e r p e n t i n e (45 l i z a r d i t e * , c h r y s o t i l e ? ) ; 5 c h l o r -i t e * ; 30 t a l c * ; t r a c e carbonate (magnesite); t r a c e b r u c i t e * ; 20 chromite ( a l t e r i n g to magnetite*). SH-8 : s e r p e n t i n i z e d h a r z b u r g i t e macro' : as i n SH-5 micro' : a r e l a t i v e l y f r e s h rock, q u i t e s i m i l a r t o SH-5, wit h about h a l f the o l i v i n e s e r p e n t i n i z e d ; very minor a l t e r a t i o n of some orthopyroxene to b a s t i t e ; a few cli n o p y r o x e n e g r a i n s are of the same s i z e as the e n s t a t i t e s (up to 0.5 cm), but they mainly occur as f i n e (1 to 2 mm) c r y s t a l s c l u s t e r i n g around l a r g e r orthopyroxenes; o p t i c a l e x t i n c t i o n p a t t e r n s suggest t h a t the o r i g i n a l o l i v i n e g r a i n s were of the same s i z e as the o r t h o -pyroxenes; most of the chromite has a l t e r e d t o magnetite (see p l a t e IVb). mode (%) : 25 o l i v i n e * ; 25 orthopyroxene ( e n s t a t i t e * ) ; 5 c l i n o -pyroxene ( d i o p s i d e * ) ; 35 s e r p e n t i n e (30 l i z a r d i t e * , t r a c e c h r y -s o t i l e , 5 b a s t i t e ) ; t r a c e t a l c * ( ? ) ; t r a c e b r u c i t e * ; 10 chromite ( a l t e r i n g to magnetite). SH-9 : h a r z b u r g i t e macro' : as i n SH-5 micro' : fre s h n e s s of rock midway between SH-5 and SH-8, and g e n e r a l l y q u i t e s i m i l a r to both those samples; l e s s than h a l f the o l i v i n e i s s e r p e n t i n i z e d ; e s s e n t i a l l y no pyroxene a l t e r a t i o n to b a s t i t e ; v ery d i s t i n c t d i o p s i d i c l a m e l l a e and b l e b s w i t h i n the l a r g e (up to 0.5 cm) e n s t a t i t e c r y s t a l s ; o n l y s l i g h t a l t e r -a t i o n of chromite t o magnetite. mode (%) : 40 o l i v i n e * ; 20 orthopyroxene ( e n s t a t i t e * ) ; 5 c l i n o -pyroxene ( d i o p s i d e ) ; 30 s e r p e n t i n e (30 l i z a r d i t e * , c h r y s o t i l e ? ) ; 150 5 chromite.. TSD-1 : dunite (saxonite) macro' : very f r e s h e q u i g r a n u l a r (1 to 2 mm) yellow-green o l i v i n e ; weathered s u r f a c e c h a r a c t e r i z e d by orange (dun) c o l o u r and p r o t r u d i n g r e s i s t a n t e n s t a t i t e g r a i n s ( p l a t e s I l f and I l g ) . micro' : simple mineralogy; no s e r p e n t i n i z a t i o n whatsoever of the anhedral o l i v i n e g r a i n s ; a l l pyroxene appears to be e n s t a t -i t e which o f t e n e x h i b i t s deformed (bent) l a m e l l a e (plate I V c ) . mode (%) : 85 o l i v i n e * ; 14 orthopyroxene ( e n s t a t i t e * ) ; 1 magnet i t e . TSS-1,2 : s e r p e n t i n i z e d l h e r z o l i t e macro' : dark rock composed of green pyroxene c r y s t a l s s e t w i t h i n a matrix o f grey-black s e r p e n t i n e - o l i v i n e ( p l a t e I l h ) . micro' : e q u i g r a n u l a r subhedral c r y s t a l s averaging 0.5 mm i n diameter; most of the o l i v i n e i s s e r p e n t i n i z e d ; pyroxenes are u n a l t e r e d , w i t h about three times as much c l i n o p y r o x e n e as orthopyroxene. mode (%) : 5 o l i v i n e ; 20 orthopyroxene ( e n s t a t i t e ) ; 60 c l i n o -pyroxene ( d i o p s i d e * ) ; 10 s e r p e n t i n e (10 l i z a r d i t e * , a n t i g o r i t e * 5 magnetite. CO-1 : s e r p e n t i n i t e macro' : very uniform f i n e - g r a i n e d dark grey rock. micro' : rock t o t a l l y s e r p e n t i n i z e d w i t h a very f i n e mesh t e x t -ure; some r e l i c t pyroxene t e x t u r e s r e c o g n i z a b l e , but im p o s s i b l e to estimate the o r i g i n a l pyroxene content. mode (%) : 95 s e r p e n t i n e (90 l i z a r d i t e * , a n t i g o r i t e ? ) ; t r a c e c h l o r i t e ; 5 chromite, a l t e r i n g to magnetite. TC-U : o l i v i n e gabbro macro' : f i n e l y g r a n u l a r dark green-black rock w i t h about 2% v i s i b l e disseminated p y r r h o t i t e . 151 micro' : h a l f the rock i s composed of anhedral o l i v i n e g r a i n s , 1 to 2 mm i n diameter; l a r g e o p t i c a l l y continuous prisms of hornblende p o i k i l i t i c a l l y e n c l o s e the p l a g i o c l a s e and o r t h o -pyroxene; no clino p y r o x e n e i s r e c o g n i z a b l e ; about a t h i r d o f the p l a g i o c l a s e has a l t e r e d to z e o l i t e . mode (%) : 55 o l i v i n e ; 2 orthopyroxene ( e n s t a t i t e ? ) ; 5 se r p e n t -i n e ; 20 hornblende; 10 p l a g i o c l a s e (30% of which has a l t e r e d to z e o l i t e ) ; 5 b i o t i t e ; t r a c e p h l o g o p i t e ; t r a c e carbonate; 2 p y r r h o t i t e . TC-G : hornblende d i o r i t e macro' : a very homogeneous-looking, f i n e l y g r a n u l a r , dark grey rock w i t h about 2% disseminated s u l p h i d e s . micro' : rock predominantly composed of subhedral to euhedral a n o r t h i t e g r a i n s , 0.1 to 1 mm i n l e n g t h , w i t h prominant C a r l s b a d and a l b i t e twins; h a l f the hornblende i s o p t i c a l l y zoned and appears to be r e p l a c i n g pyroxene. mode (%) : 75 p l a g i o c l a s e ( a n o r t h i t e , 10% of which has a l t e r e d to z e o l i t e ) ; 20 hornblende; 2 orthopyroxene; 1 cl i n o p y r o x e n e ; 2 s u l p h i d e ( p y r r h o t i t e ? ) . 152 APPENDIX I I . COMPUTER PROGRAM AND OUTPUT LISTING The computer program used to produce the p l o t (figure 10) that i l l u s t r a t e s the trends of rad i o g e n i c strontium growth i n the earth's major reservoirs according to the chemical e v o l -u t i o n model. Also included here i s the computer output l i s t i n g of radiogenic strontium growth i n each system f o r every 25 my i n t e r v a l . Text reference i s section V I I C REAL** X I 2 5 0 ) , Y ( 2 5 0 > , R B S R < 2 5 0 ) , T I M E ( 4 5 0 ) , R B ( 4 5 0 ) , SRI 450) C ALL TIMES ARE GIVEN IN MILLIONS OF YEARS C C SYSTEMS 1A AND IB C J=0 PRINT 2005 2005 FCRMAT(1H1) 0C 30 1 1 = 1 , 2 R E A D ! 5 , 1 ) T I N E I , T I M E F , S R A T 1 0 , R B S R I , R B S R F 1 FORMAT15F10.0 ) M = l T1=TIMEI T2=T1 C S T A N T = 4 . 2 5 4 E - l l X (1 )=T IMEI Y (1 ) = SRATI0 RBSRI I )=RBSRI 00 40 1 * 2 . 3 3 M=M + 1 T2=T2+25. R B S R I I ) = ( R B S R F - R B S R I ) / ( T I H E F - T I H E I ) * ( r 2 - T l ) + R B S R I Y ( I ) = Y ( I - 1 ) + C S T A N T * R B S R ( I ) * 2 5 i 0 E + 0 6 X ( I ) = T 2 4 0 CONTINUE DO 210 K = l , 3 3 T IM£(K+J*33 ) = X ( K ) RB(K+J*33)=RBSR(K) SR(K+J*33I=YIKI 210 CONTINUE I F ( I I . E Q . l ) SR1=Y(33> SR2=Y(33) J = J + l CALL L A P L 0 T ( X , Y , M , J ) 30 CONTINUE -PRINT 2 0 0 6 2006 FORMAT! IH , • SYSTEM IA SYSTEM I B M . PRINT 2007 2007 FORMAT{IH , • TIME RB/SR SR87/SR86 TIME RB/SR SR8 C7/SR86 « I 0 0 220 K=l , 3 3 220 WRITE ( 6 , 69) T IME ( K ) , RB (K ) ,SR IK) , T IME ( K + 33 ) , R B IK + 33) , SR (K+33) 69 F 0 R M A T ( 4 ( F 9 . 0 , F 9 . 5 , F 9 . 5 , 6 X ) ) C C SYSTEMS 11 A , I I B , I I C . I I O C J=0 PRINT. 2 0 0 5 SR22=SR2 DO 50 11=1,4 R £ A D ( 5 » 2 ) T I H E I » T I P E F , R B S R I , R B S R F 2 F O R M A T ( 2 F 1 0 . 0 , 1 0 X , 2 F 1 0 . 0 ) M = l T1«=TIMEI T2=T1 SRATI0=SR22 1F< I I . E Q . 1)SRATI0«=SR1 X ( 1 ) = T ! M E I Y l l ) = S R A T I O RBSR(1)=RBSRI DO 60 1=2,51 H » M * l T2=T2+25. RBSRI I )= IRBSRF-RBSRI ) /J T lM E F - T I M E I ) * (T2-T1 l+RBSR I Y ( I ) = Y ( I - l )+CSTANT*RBSR( l " l*25 .0E*06 X CI) = T2 60 CCNTINUE 00 230 K = l , 5 1 T IM£(K+J*51 1=X(K) RBIK»J*5lI 'RBSRIK) . " • SRIX*J*51)=Y(K) 230 CCNTINUE I F ( I I . E O . l ) SK1=Y(51> I F d l . E U . 2 l SR2=Y(51> I F M I . E 0 . 3 ) SR3=Y<51) I F I I I . E Q . 4 ) SR4=Y(51I J = J U CALL L A P L O T ( X , Y , M ,J) 50 CCNTINUE PRINT 2008 2008 FORMAT(IH SYSTEM I IA SYSTEM I IB C SYSTEM IIC SYSTEM 110 ' I PRINT 2009 2009 FORMATtlH , M * TIME RB/SR SR87/SR86 •>) DO 240 K = l , 5 1 2*0 W R I T E I 6 , 6 9 ) T I M E { K ) , R B ( K ) , S R ( K ) , T I ME(K + 51! ,RBIK*51>,SR(K+51>.TIHEIK C*102) ,RB1K+102) ,SRIK*102) ,T IMEIK+153>,RB {K*153),SR (K>1531 C C SYSTEMS I I I A . I I I B . I I I C I I I D C J=0 -PRINT 2005 OC 10 11 = 1,4 , READ(5.2)T IMEI ,T IMEF,RBSRI ,RBSRF H = l TI=TIKEI T2=Tl I F I I I . E O . l ) SRATI0=SR1 I F I I I . E 0 . 2 ) SRATI0=SR2 I F I I I . E 0 . 3 ) SRATI0=SR3 IF) I I . EU .4 > SRATIU=SR4 Y ( l )=SRATlO X f l l = T I M E l RRSR ( 1 )=RBSRI DO 20 1=2,IC1 ' M=M*l T2=TZ*25. R B S R ( I l = < R B S R F - R B S R I ) / (T I M E F -T I M E I )» (T2-T1 ) *RBSR I Y( I > = Y< I -1MCSTANT*RBSR (1 l* 2 5 .0E*06 X<I) = T2 20 CCNTINUE DO 250 K=l,101 T I M E ( K » J * 1 0 1 ) » X ( M . RB(K+J*101)=RBSR(K) S R ( K » J » 1 0 1 ) « Y ( K > 250 CCNTINUE J » J * I CALL LAPLOT{X,Y f M , J> 10 CCNTINUE PRINT 2010 2010 FORMAT!1H SYSTEM 111A SYSTEM 11 IB C SYSTEM I I IC SYSTEM 11 ID* C) PRINT 2009 DO 260 K M , 101 260 W R I T E ( 6 . 6 9 ) T I K E ( K ) , R B I K ) , S R ( K | , T I M E I K * 1 0 1 ) , R B I K » 1 0 I > , S R I K , 1 0 1 1 , T I M CE(Kt2 02 1,R8(K + 202) ,SRIK + 2 0 2 ) , T I K E < K * 3 0 3 ) . R B I K » 3 0 3 > , S R C K O 0 3 > CALL PLOTND STOP END SUBROUTINE L A P L O T ( X , Y , M , J ) DIMENSION X ( M ) , Y ( M ) , X X ( 2 ) , Y Y ( 2 ) REAL*4 NUMB R C C PLOT THE FRAKe, THE A X I S , AND WRITE THE AXIS LABELS C I F 1 J . N E . 1 ) GO TO 100 XXI11=0. XXI?) - -10. YY I I )=0 . YYI2)=0. CALL L I N E I X X , Y Y , 2 , 1 ) X X ( l ) = 1 0 . YY(2I=10.0 CALL L I N E I X X , Y Y , 2 , 1 ) X X ( l ) = 0 . YYCI 1 = 1 0 . 0 CALL L I N E I X X , Y Y , 2 , 1 1 XX!2)=0. YY(21=0. CALL L I N E I X X , Y Y , 2 , l ) C C WRITE X SCALE AND X LABEL C CALL N U M B E R l - O . 3 4 , - 0 . 1 6 , 0 . 1 4 , - 5 0 0 0 . , 0 . 0 , - 1 ) CALL NUMBER I t l . 6 8 , - 0 . 1 6 , 0 . 1 4 , - 4 0 0 0 . , 0 . 0 , - 1 1 CALL NIJMBERl + 3 . 6 8 , - 0 . 1 6 , 0 . 1 4 , - 3 0 0 0 . , 0 . 0 , - 1 ) CALL SYMnOL(+4.38,-0.48,0.28, •TI ME ( M Y ) • , 0 . 0 , 8 1 CALL N U M B E R ( * 5 . 6 8 , - 0 . 1 6 , 0 . 1 4 , - 2 0 0 0 . , 0 . 0 , - 1 ) CALL NUMBER 1 * 7 . 6 8 , - 0 . 1 6 , 0 . 1 4 , - 1 0 0 0 . , 0 . 0 , - I ) CALL NUMtlER (•9.92,-0.16, 0 . 1 4 , 0 . , 0 . 0 , - 1 ) C WRITE Y SCALE AND Y LABEL C X X ( l ) = 1 0 . 0 7 Y Y I 1 ) = - 0 . 0 7 NUMBR = 0 . 6 9 8 0 DC 10 1=1,10 . • . ' CALL N U M B t R f X X C 1 ) , Y Y ( 1 ) , 0 . 1 4 , N U M B K , 0 . 0 , 3 ) YYI1 ) = YY( 11*1.0 NUMBR=NUMnR«0.003 10 CONTINUE CALL N U M R C R I 1 0 . 7 0 . • 4 . 7 3 , 0 . 1 4 , 8 7 . , 0 . 0 , - 1 ) CALL S Y M B O L ( 1 1 . 0 4 , + 4 . 6 4 , 0 . 2 8 , • S R ' , 0 . 0 , 2 ) X X ( l ) = 1 0 . 7 0 XX(2) = U . 4 6 YY(1)=4.5 Y Y I 2 I - 4 . 5 CALL L I N E ( X X , Y Y , 2 , l ) CALL N U M B E R ( 1 0 . 7 0 , * 4 . 2 8 . 0 . 1 4 , 8 6 . , 0 . 0 , - 1 ) CALL SYMBOL!11.04,+4.U,0.28,"SR",0.0,21 100 CONTINUE c C SCALE THE DATA POINTS C CALL S C A L E X ( X . M ) CALL S C A L E Y ( Y . M ) C C PLOTTING START C CALL L I N E I X , Y . M . I ) 900 RETURN END SUBROUTINE S C A L E X I X . H ) DIMENSION XIM) X P I N - - 5 0 C O . XMAX=0. S U E = 1 0 . 0 OX=IXMAX-XMIN)/SIZE DO 10 1=1,M 10 X (I ) = IX( I ) -XMIN)/DX RETURN END . SUBROUTINE S C A L E Y I Y»M) DIMENSION Y (M) Y H I N = 0 . 6 9 8 0 YMAX=0.7250 S I Z E = 9 . 0 DY=<YMAX-YHIN)/SIZE 00 10 1=1,M 10 V!I )=<Y(II -VMIN>/OY RETURN END SSIG SYSTEM IA TIME RB/SR SR87/SRB6 - 4 5 5 0 . 0 . 0 2 5 0 0 0 . 6 9 9 0 0 - 4 5 2 5 . 0 . 0 2 4 5 3 0 . 6 9 9 0 3 - 4 5 0 0 . 0 . 0 2 4 0 6 - 0 . 6 9 9 0 5 - 4 4 7 5 . 0 . 0 2 3 5 9 0 . 6 9 9 0 8 - 4 4 5 0 . 0 . 0 2 3 1 2 0 . 6 9 9 1 0 - 4 4 2 5 . 0 . 0 2 2 6 6 0 . 6 9 9 13 - 4 4 0 0 . 0 . 0 2 2 1 9 0 . 6 9 9 1 5 - 4 3 7 5 . 0 . 0 2 1 7 2 0 . 6 9 9 1 7 ^ 4 3 5 0 . 0 . 0 2 1 2 5 0 . 6 9 9 1 9 - 4 3 2 5 . 0 . 0 2 0 7 8 0 . 6 9 9 2 2 - 4 3 0 0 . 0 . 0 2 0 3 1 0 . 6 9 9 2 4 - 4 2 7 5 . 0 . 0 1 9 8 4 0.69926 - 4 2 5 0 . 0 . 0 1 9 3 3 0 . 6 99 28 - 4 2 2 5 . 0 . 0 1 8 9 1 0 . 6 9 9 3 0 - 4 2 0 0 . 0 . 0 1 8 4 4 0 . 6 9 9 3 2 - 4 1 7 5 . 0 . 0 1 7 9 7 0 . 6 9 9 3 4 - 4 1 5 0 . 0 . 0 1 7 5 0 0 . 6 9 9 3 6 - 4 1 2 5 . 0 . 0 1 7 0 3 0 . 6 9 9 3 8 - 4 1 0 0 . 0 . 0 1 6 5 6 0 . 6 9 9 3 9 - 4 0 7 5 . ' 0 . 0 1 6 0 9 0.699*1 - 4 C 5 0 . 0 . 0 1 5 6 2 0 . 6 9 9 4 3 - 4 0 2 5 . 0 . 0 1 5 1 6 0 . 6 9 9 4 4 - 4 0 0 0 . 0 . 0 1 4 6 9 0 . 6 9 9 4 6 - 3 9 7 5 . 0 . 0 1 4 2 2 0 . 6 9 9 4 7 - 3 9 5 0 . 0 . 0 1 3 7 5 0 . 6 9 9 4 9 - 3 9 2 5 . 0 . 0 1 3 2 8 0 . 6 9 9 5 0 - 3 9 0 0 . 0 . 0 1 2 8 1 0 . 6 9 9 5 2 - 3 8 7 5 . 0 . 0 1 2 3 4 0 . 6 9 9 5 3 - 3 H 5 0 . 0 . 0 1 1 8 8 0 . 6 9 9 5 4 - 3 B 2 5 . 0 . 0 1 1 4 1 0 . 6 9 9 5 5 - 3 8 0 0 . 0 . 0 1 0 9 4 0 . 6 9 9 5 6 - 3 7 7 5 . 0 . 0 1 0 4 7 0 . 6 9 9 5 8 - 3 7 5 0 . 0 . 0 1 0 0 0 0 . 6 9 9 5 9 SYSTEM IB TIME RB/SR SRH7/SRR6 - 4 5 5 0 . 0 . 0 2 5 0 0 0 . 6 9 9 0 0 - 4 5 2 5 . 0 . 0 2 5 7 8 0 . 6 9 9 0 3 - 4 5 0 0 . 0 . 0 2 6 5 6 0 . 6 9 9 0 6 - 4 4 7 5 . 0 . 0 2 7 3 4 0 . 6 9 9 0 e - 4 4 5 0 . 0 . 0 2 8 1 2 0 . 6 9 9 1 I - 4 4 2 5 . 0 . 0 2 H 9 1 0 . 6 9 9 1 5 - 4 4 0 0 . 0 . 0 2 9 6 9 0 . 6 9 9 1 8 - 4 3 7 5 . 0 . 0 3 0 4 7 0 . 6 9 9 2 1 - 4 3 5 0 . 0 . 0 3 1 2 5 0 . 6 9 9 ? * - 4 3 2 5 . 0 . 0 3 2 0 3 0 . 6 9 9 2 8 - 4 3 0 0 . 0 . 0 3 2 8 1 0 . 6 9 Q 3 1 - 4 2 7 5 . 0 . 0 3 3 5 9 0 . 6 9 9 35 - 4 2 5 0 . 0 . 0 3 4 3 7 0 . 6 9 9 3 8 - 4 2 2 5 . 0 . 0 3 5 1 6 0 . 6 9 9 * 2 - 4 2 0 0 . 0 . 0 3 59' , 0 . 69')*6 - 4 1 7 5 . 0 . 0 3672 0 . 6 9 9 5 0 - 4 1 5 0 . 0 . 0 3 7 5 0 0 . 6 9 9 5 4 - 4 1 2 5 . 0 . 0 3 P 2 H 0 . 6 9 9 5 R - 4 1 U 0 . 0 . 0 3 ^ 0 6 0 . 6 9 9 h 2 - 4 0 7 5 . 0 . 0 3 9 H 4 0 . 6 ^ 9 6 6 - 4 0 5 0 . 0 . 0 4 0 6 2 0 . 6 9 9 7 I - 4 0 2 5 . 0 . 0 4 1 ' . 1 0 . 6 ' 1 9 7 5 - 4 0 0 0 . 0 . 0 4 2 1 9 0 . 6 9 9 7 9 - 3 9 7 5 . 0 . 0*297 0 . 6 9 9 B 4 - 3 9 5 0 . 0 . 0 * 3 7 5 0 . 6 9 9 3 9 - 3 9 2 5 . 0 . 0 4 4 5 3 0 . 6 9 9 9 3 - 3 9 0 0 . 0 . 0 4 5 3 1 0 . 6 9 9 9 8 - 3 8 7 5 . 0 . 0 4 6 0 9 0 . 7 O 0 0 3 - 3 8 5 0 . 0 . 0 4 6 8 7 0 . 7 0 0 0 8 - 3 8 2 5 . 0 . 0 4 7 6 6 0 . 7 0 0 1 3 - 3 8 0 0 . 0 . 0 4 e 4 4 0 . 7 0 0 1 8 - 3 7 7 5 . 0 . 0 4 9 2 2 0 . 7 0 0 2 * - 3 7 5 0 . 0 . 0 5 0 0 0 0 . 7 0 0 2 9 cn TIME 3 7 5 0 . 3 7 2 5 . 3 7 0 0 . 3 6 7 5 . 3 6 5 0 . 3 6 2 5 . ' 3 6 0 0 . 3 5 7 5 . 3 5 5 0 . 3 5 2 5 . 3 5 0 0 . 3 4 7 5 . 3 4 5 0 . 3 4 2 5 . 3 4 0 0 . 3 3 7 5 . 3 3 5 0 . 3 3 2 5 . 3 3 0 0 . 3 2 7 5 . 3 2 5 0 . 3 2 2 5 . 3 2 0 0 . 3 1 7 5 . 3 1 5 0 . 3 1 2 5 . 3 1 0 0 . 3 0 7 5 . 3 0 5 0 . 3 0 2 5 . 3 0 0 0 . 2 9 7 5 . 2 9 5 0 . 2 9 2 5 . 2 9 0 0 . 2 8 7 5 . 2 6 5 0 . 2 0 2 5 . 2 8 0 0 . 2 7 7 5 . 2 7 5 0 . ' - 2 72 5 . - 2 7 0 0 . - 2 6 7 5 . - 2 6 5 0 . - 2 6 2 5 . - 2 6 0 0 . - 2 5 7 5 . - 2 5 5 0 . - 2 5 2 5 . ' - 2 5 0 0 . SYSTEM II RP/SR 0 . 0 1 0 0 0 0 . 0 0 9 9 0 0 . 0 0 9 8 0 0 . 0 0 9 7 0 0 . 0 0 9 6 0 0 . 0 0 9 5 0 0 . 0 0 9 4 0 0 . 0 0 9 3 0 0 . 0 0 9 2 0 0 . 0 0 9 1 0 0 . 0 0 9 0 0 0 . 0 0 8 9 0 0 . 0 0 8 8 0 0 . 0 0 8 7 0 0 . 0 0 8 6 0 0 . 0 0 8 5 0 0 . 0 0 8 4 0 0 . 0 0 8 3 0 0 . 0 0 8 2 0 o . o o e i o 0 . 0 0 8 0 0 0 . 0 0 7 9 0 0 . 0 0 7 8 0 0 . 0 0 7 7 0 0 . 0 0 7 6 0 0 . 0 0 7 5 0 0 . 0 0 7 4 0 0 . 0 0 7 3 0 0 . 0 0 7 2 0 0 . 0 0 7 1 0 0 . 0 0 7 0 0 0 . 0 0 6 9 0 0 . 0 0 6 8 0 0 . 0 0 6 7 0 0 . 0 0 6 6 0 0 . 0 0 6 5 0 0 . 0 0 6 4 0 0 . 0 0 6 3 0 0 . 0 0 6 2 0 0 . 0 0 6 1 0 0 . 0 0 6 0 0 0 . 0 0 5 9 0 0 . 0 0 5 8 0 0 . 0 0 5 7 0 0 . 0 0 5 6 0 0 . 0 0 5 5 0 0 . 0 0 5 4 0 0 . 0 0 5 3 0 0 . 0 0 5 2 0 0 . 0 0 5 1 0 0 . 0 0 5 0 0 SR87/SR86 0 . 6 9 9 5 9 0 . 6 9 9 6 0 0 . 6 9 9 6 1 0 . 6 9962 0 . 6 9 9 6 3 0 . 6 9 9 6 4 0 . 6 9 9 6 5 0 . 6 9 9 6 6 0 . 6 9 9 6 7 0 . 6 9 9 6 8 0 . 6 9 9 6 9 0 . 6 9 9 7 0 0 . 6 9 9 7 1 0 . 6 9 9 7 1 0 . 6 9 9 7 2 6 9 9 7 3 6 9 9 7 4 6 9 9 7 5 6 9 9 7 6 6 9 9 7 7 0 . 6 997 8 0 . 6 9 9 7 8 0 . 6 9 9 7 9 0 . 6 9 9 8 0 0 . 6 9 9 8 I 0 . 6 9 9 8 2 0 . 6 9 9 8 2 0 . 6 998 3 0 . 6 9 9 8 4 0 . 6 9 9 3 5 0 . 6 9 9 8 6 0 . 6 9 9 8 6 0 . 6 9 9 3 7 0 . 6 9 9 8 8 0 . 6 9 9 3 8 0 . 6 9 9 8 9 0 . 6 9 9 9 0 0 . 6 9 9 9 0 0 . 6 9 9 9 1 0 . 6 9 9 9 2 0 . 6 9 9 9 2 0 . 6 9 9 9 3 0 . 6 9 9 9 4 0 . 6 9 9 9 4 0 . 6 9 9 9 5 0 . 6 9 9 9 5 0 . 6 9 9 9 6 0 . 6 9 9 9 7 0 . 6 9 9 9 7 0 . 6 9998 0 .69998 SYSTEM I IH TIME RI'./SR SRB7/SR86 - 3 7 5 0 . 0 . 0 5 0 0 0 0 . 7 0 0 2 9 - 3 7 2 5 . 0 . 0 5 0 4 0 0 . 7 0 0 3 4 - 3 7 0 0 . 0 . 0 5 0 8 0 0 . 7 0 0 4 0 - 3 6 7 5 . 0 . 0 5 1 2 0 0 . 7 0 0 4 5 - 3 6 5 0 . . 0 . 0 5 1 6 0 0 . 7 0 0 5 1 - 3 6 2 5 . 0 . 0 5 2 0 0 0 . 7 0 0 5 6 - 3 6 0 0 . 0 . 0 5 2 4 0 0 . 7 0 0 6 2 - 3 5 7 5 . 0 . 0 5 2 8 0 0 . 7 0 0 6 7 - 3 5 5 0 . 0 . 0 5 3 2 0 0 . 7 0 0 7 3 - 3 5 2 5 . 0 . 0 5 3 6 0 0 . 7 0 0 7 9 - 3 5 0 0 . 0 . 0 5 4 0 0 0 . 7 0 0 8 4 - 3 4 7 5 . 0 . 0 5 4 4 0 0 . 7 0 0 9 0 - 3 4 5 0 . 0 . 0 5 4 8 0 0 . 7 D C 9 6 - 3 4 2 5 . 0 . 0 5 5 2 0 0 . 7 0 1 0 2 - 3 4 0 0 . . 0 . 0 5 5 6 0 0 . 7 0 1 0 8 - 3 3 7 5 . 0 . 0 5 6 0 0 0 . 7 0 1 1 4 - 3 3 5 0 . 0 . 0 5 6 4 0 0 . 7 0 1 2 0 - 3 3 2 5 . 0 . 0 5 6 B 0 0 . 7 0 1 2 6 - 3 3 0 0 . 0 . 0 5 7 2 0 0 . 7 0 1 32 - 3 2 7 5 . 0 . 0 5 7 6 0 0 . 7 0 1 3 8 - 3 2 5 0 . 0 . 0 5 H 0 0 0 . 7 0 1 4 4 - 3 2 2 5 . 0 . 0 5 8 4 0 0 . 7 0 1 5 0 - 3 2 0 0 . 0 . 0 5 H 8 0 0 . 7 0 1 5 7 - 3 1 7 5 . 0 . 0 5 9 2 0 0 . 70163 - 3 1 5 0 . 0 . 0 5 9 6 0 0 . 70169 - 3 1 2 5 . 0 . 0 6 0 0 0 0 . 7 0 1 7 6 - 3 1 0 0 . 0 . 0 6 0 * 0 0 .701 .12 - 3 0 7 5 . 0 . 0 6 0 B O 0 . 7 0 1 B 8 - 3 0 5 0 . 0 . 0 6 1 2 0 0 . 7 0 1 9 5 - 3 0 2 5 . ' 0 . 0 6 1 6 0 0 . 7 0 2 0 1 - 3 0 0 0 . 0 . 0 6 2 0 0 0 . 7 0 2 0 8 - 2 9 7 5 . 0 . 0 6 2 4 0 0 . 7 0 2 1 5 - 2 9 5 0 . 0 . 0 6 2 8 0 0 . 7 0 2 2 1 - 2 9 2 5 . 0 . 0 6 3 2 0 0 . 7 0 2 2 R - 2 9 0 0 . 0 . 0 6 3 6 0 0 . 7 0 2 3 5 - 2 8 7 5 . 0 . 0 6 4 0 0 0 . 7 0 2 4 2 - 2 8 5 0 . 0 . 0 6 4 4 0 0 . 7 0 2 4 9 - 2 8 2 5 . 0 . 0 6 4 8 0 0 . 7 0 2 5 5 - 2 8 0 0 . 0 . 0 6 5 2 0 0 . 7 0 2 6 2 - 2 7 7 5 . 0 . 0 6 5 6 0 0 . 7 0 2 6 9 - 2 7 5 0 . 0 . 0 6 6 0 0 0 . 7 0 2 7 6 - 2 7 2 5 . 0 . 0 6 6 * 0 0 . 7 0 2 8 3 - 2 7 0 0 . 0 . 0 6 6 8 0 0 . 70290 - 2 6 7 5 . 0 . 0 6 7 2 0 0 . 7 0 2 9 8 - 2 6 5 0 . 0 . 0 6 7 6 0 0 . 7 0 3 0 5 - 2 6 2 5 . 0 . 0 6 8 0 0 ' 0 . 7 0 3 1 2 - 2 6 0 0 . 0 . 0 6 8 4 0 0 . 7 0 3 1 9 - 2 5 7 5 . 0 . 0 6 8 8 0 0 . 7 0 3 2 7 - 2 5 5 0 . 0 . 0 6 9 2 0 0 . 7 0 3 3 4 - 2 5 2 5 . 0 . 0 6 9 f , 0 0 . 7 0 3 4 1 - 2 5 0 0 . 0 . 0 7 0 0 0 0 . 7 0 3 4 9 SYS I tM 1IC SYSTEM I ID T IPE xn/sw SR67/SR66 TIKE RU/SR S R 8 7 / S R 8 6 - 3 7 5 0 . 0 . 0 5 0 0 0 0 . 70029 - 3 7 5 0 . 0 . 0 5 0 0 0 0 . 7 0 0 2 9 - 3 7 2 5 . 0 . 0 4 9 5 0 0 . 7 0 0 3 4 - 3 7 2 5 . 0 . 0 5 2 6 0 0 . 7 0 0 3 4 - 3 7 0 0 . 0 . 0 4 9 0 0 0 . 7 0 0 3 9 - 3 7 0 0 . 0 . 0 5 5 2 0 0 . 7 0 0 4 0 - 3 6 7 5 . 0 . 0 4 8 5 0 0 . 7 0 0 4 4 - 3 6 7 5 . 0 . 0 5 7 6 0 0 . 7 0 0 4 6 - 3 6 5 0 . •0.04800 0 . 7 0 0 5 0 - 3 6 5 0 . 0 . 0 6 0 4 0 0 . 7 0 0 5 3 - 3 6 2 5 . 0 . 0 4 7 5 0 0 . 7 0 0 5 5 - 3 6 2 5 . 0 . 0 6 3 0 0 0 . 7 0 0 6 0 - 3 6 0 0 . 0 . 0 4 7 0 0 0 . 7 0 0 6 0 - 3 6 0 0 . 0 . 0 6 5 6 0 0 . 7 0 0 6 7 - 3 5 7 5 . 0 . 0 4 6 5 0 0 . 7 0 0 6 5 - 3 5 7 5 . 0 . 0 6 8 2 0 0 . 7 0 0 7 4 - 3 5 5 0 . 0 . 0 4 6 0 0 0 . 7 0 0 6 9 - 3 5 5 0 . 0 . 0 7 0 8 0 0 . 7 0 0 8 1 - 3 5 2 5 . 0 . 0 4 5 5 0 0 . 7 0 0 7 4 - 3 5 2 5 . 0 . 0 7 3 4 0 0 . 7 0 0 8 9 - 3 5 0 0 . 0 . 0 4 5 0 0 0 . 7 0 0 7 9 - 3 5 0 0 . 0 . 0 7 6 0 0 0 . 7 0 0 9 7 - 3 4 7 5 . 0 . 0 4 4 5 0 0 . 7 0 0 8 4 - 3 4 7 5 . 0 . 0 7 8 6 0 0 . 7 0 1 0 6 - 3 4 5 0 . , 0 . 0 4 4 0 0 0 . 7 0 0 8 8 - 3 4 5 0 . 0 . 0 8 1 2 0 0 . 7 0 1 1 4 - 3 4 2 5 . 0 . 0 4 3 5 0 0 . 7 0 0 9 3 - 3 4 2 5 . 0 . 0 8 3 8 0 0 . 7 0 1 2 3 - 3 4 0 0 . 0 . 0 4 300 0 . 7 0 0 9 8 - 3 4 0 0 . 0 . 0 8 6 4 0 0 . 7 0 1 3 2 - 3 3 7 5 . 0 . 0 4 2 5 0 0 . 7 0 1 0 2 - 3 3 7 5 . 0 . 0 8 9 00 0 . 7 0 1 4 2 - 3 3 5 0 . 0 . 0 4 2 0 0 . 0 . 7 0 1 0 7 - 3 3 5 0 . 0 . 0 9 1 6 0 0 . 7 0 1 5 1 - 3 3 2 5 . 0 . 0 * 1 5 0 0 . 7 0 1 1 1 - 3 3 2 5 . 0 . 0 9 * 2 0 0 . 7 0 1 6 1 - 3 3 0 0 . 0 . 0 4 1 0 0 0 . 7 0 1 1 5 - 3 3 0 0 . O . 0 9 6 B 0 0 . 7 0 1 7 2 - 3 2 7 5 . 0 . 0 4 0 5 0 0 . 7 0 1 2 0 - 3 2 7 5 . 0 . 0 9 9 * 0 0 . 7 0 1 8 2 - 3 2 5 0 . 0 . 0 4 000 0 . 7 0 1 2 4 - 3 2 5 0 . 0 . 1 0 2 0 0 0 . 7 0 1 9 3 - 3 2 2 5 . 0 . 0 3 9 5 0 0 . 7 0 1 2 3 - 3 2 2 5 . 0 . 1 0 * 6 0 0 . 7 0 2 0 4 - 3 2 0 0 . 0 . 0 3 9 0 0 0 . 7 0 1 3 2 - 3 2 0 0 . 0 . 1 0 7 2 0 0 . 7 0 2 16 - 3 1 7 5 . 0 . 0 3 8 5 0 0 . 7 0 1 3 6 - 3 1 7 5 . 0 . 1 0 9 8 0 0 . 7 0 2 2 7 - 3 1 5 0 . 0 . 0 3 8 0 0 0 . 7 0 1 4 0 - 3 1 5 0 . 0 . 1 1 2 * 0 0 . 7 0 2 3 9 - 3 1 2 5 . 0 . 0 3 7 5 0 0 . 7 0 1 4 4 - 3 1 2 5 . 0 . 1 1 5 0 0 0 . 7 0 2 52 - 3 1 0 0 . 0 . 0 3 7 0 0 0 . 7 0 1 4 8 - 3 1 0 0 . 0 . 1 1 7 6 0 0 . 7 0 2 6 4 - 3 0 7 5 . 0 . 0 3 6 5 0 0 . 7 0 1 5 2 - 3 0 7 5 . 0 . 1 2 0 2 0 0 . 702 77 - 3 0 5 0 . 0 . 0 3 6 0 0 0 . 7 0 1 5 6 - 3 0 5 0 . 0 . 1 2 2 80 0 . 7 0 2 9 0 - 3 0 2 5 . 0 . 0 3 5 5 0 0 . 7 0 1 6 0 - 3 0 2 5 . 0 . 1 2 5 * 0 0 . 7 0 3 0 3 - 3 0 0 0 . 0 . 0 3 5 0 0 0 . 7 0 1 6 4 - 3 0 0 0 . 0 . 1 2 0 0 0 0 . 7 0 3 1 7 - 2 9 7 5 . 0 . 0 3 4 5 0 0 . 7 0 1 6 7 - 2 9 7 5 . 0 . 1 3 0 6 0 0 . 7 0 3 3 1 - 2 9 5 0 . 0 . 0 3 4 0 0 0 . 7 0 1 7 1 - 2 9 5 0 . 0 . 1 3 3 2 0 0 . 7 0 3 4 5 - 2 9 2 5 . 0 . 0 3 3 5 0 0 . 7 0 1 7 4 - 2 9 2 5 . 0 . 1 3 5 8 0 0 . 7 0 3 5 9 - 2 9 0 0 . 0 . 0 3 3 0 0 0 . 7 0 1 7 8 - 2 9 0 0 . • 0 . 1 3 8 * 0 0 . 7 0 3 7 4 - 2 8 7 5 . 0 . 0 3 2 5 0 0 . 7 0 1 8 1 - 2 8 7 5 . 0 . 1 * 1 0 0 0 . 7 0 3 09 - 2 8 5 0 . 0 . 0 3 2 0 0 0 . 7 0 1 8 5 - 2 8 5 0 . 0 . 1 * 3 6 0 0 . 7 0 4 0 * - 2 8 2 5 . 0 . 0 3 150 0 . 7 0 1 8 8 - 2 8 2 5 . 0 . 1 * 6 2 0 0 . 7 0 * 2 0 - 2 8 0 0 . 0 . 0 3 1 0 0 0 . 7 0 1 9 1 - 2 8 0 0 . 0 . 1 * 8 8 0 0 . 7 0 * 3 6 - 2 7 7 5 . 0 . 0 3 0 5 0 0 . 7 0 1 9 5 - 2 7 7 5 . 0 . 1 5 1 4 0 0 . 70*52 - 2 7 5 0 . 0 . 0 3 0 0 0 0 . 7 0 1 9 8 - 2 7 5 0 . 0 . 1 5 4 0 0 0 . 70468 - 2 7 2 5 . 0 . 0 2 9 5 0 0 . 7 0 2 0 1 - 2 7 2 5 . 0 . 1 5 660 0 . 7 0 4 8 5 - 2 7 C C . O . C 2 9 0 0 0 . 7 0 2 0 4 - 2 7 0 0 . 0 . 1 5 9 2 0 0 . 7 0 5 0 2 - 2 6 7 5 . C . C 2 8 5 0 0 . 7 0 2 0 7 - 2 6 7 5 . 0 . 1 6 1 8 0 0 . 7 0 5 1 9 - 2 6 5 0 . 0 . 0 2 8 0 0 0 . 7 0 2 1 0 - 2 6 5 0 . 0 . 1 6 4 * 0 0 . 7 0 5 3 6 - 2 6 2 5 . 0 . 0 2 7 5 0 0 . 7 0 2 1 3 - 2 6 2 5 . 0 . 1 6 7 0 0 0 . 7 0 5 5 4 - 2 6 0 0 . 0 . 0 2 700 0 . 7 0 2 1 6 - 2 6 0 0 . 0 . 1 6 9 6 0 0 . 7 0 5 7 2 - 2 5 7 5 . 0 . 0 2 6 5 0 0 . 7 0 2 1 9 - 2 5 7 5 . 0 . 1 7 2 2 0 0 . 7 0 5 9 1 - 2 5 5 0 . 0 . 0 2 6 0 0 0 . 7 0 2 2 1 - 2 5 5 0 . 0 . 1 7 4 8 0 0 . 7 0 6 0 9 - 2 5 2 5 . 0 . 0 2 5 5 0 0 . 7 0 2 2 4 - 2 5 2 5 . 0 . 1 7 7 4 0 0 . 7 0 6 2 8 - 2 5 0 0 . 0 . 0 2 5 0 0 0 . 7 0 2 2 7 - 2 5 0 0 . 0 . 1 8 0 0 0 0 . 7 0 6 4 7 T I M E 2 5 0 0 . 2 4 7 5 . 2 4 5 0 . 2 4 2 5 . 2 4 0 0 . 2 3 7 5 . 2 3 5 0 . 2 3 2 5 . 2 3 0 0 . 2 2 7 5 . 2 2 5 0 . 2 2 2 5 . 2 2 0 0 . 2 1 7 5 . 2 1 5 0 . 2 1 2 5 . 2 1 0 0 . 2 0 7 5 . 2 0 5 0 . 2 0 2 5 . 2 0 0 0 . 1 9 7 5 . 1 9 5 0 . 1 9 2 5 . 1 9 0 0 . i e 7 5 . 1 8 5 0 . 1 8 2 5 . 1 8 0 0 . 177 5. : 1 7 5 0 . 1 7 2 5 . 1 7 0 0 . ' 1 6 7 5 . 1 6 5 0 . 1 6 2 5 . 1 6 0 0 . 1 5 7 5 . 1 5 5 0 . 1 5 2 5 . 1 5 0 0 . 1 4 7 5 . 1 4 5 0 . 1 4 2 5 . 1 4 0 0 . 1 3 7 5 . 1 3 5 0 . 1 3 2 5 . 1 3 0 0 . 1 2 7 5 . 1 2 5 0 . 1 2 2 5 . 1 2 0 0 . 1 1 7 5 . 1 1 5 0 . 1 1 2 5 . 1 1 0 0 . : S Y S T E M I I R B / S R 0 . 0 0 5 0 0 0 . 0 0 4 9 9 0 . 0 0 4 9 8 0 . 0 0 4 9 7 0 . 0 0 4 9 6 0 . 0 0 4 9 5 0 . 0 0 4 9 4 0 . 0 0 4 9 3 0 . 0 0 4 9 2 0 . 0 0 4 9 1 0 . 0 0 4 9 0 0 . 0 0 4 8 9 0 . 0 0 4 8 8 0 . 0 0 4 8 7 0 . 0 0 4 8 6 0 . 0 0 4 8 5 0 . 0 0 4 8 4 0 . 0 0 4 8 3 0 . 0 0 4 8 2 0 . 0 0 4 8 1 0 . 0 0 4 8 0 0 . 0 0 4 7 9 0 . 0 0 4 7 8 0 . 0 0 4 7 7 0 . 0 0 4 7 6 0 . 0 0 4 7 5 0 . 0 0 4 7 4 0 . 0 0 4 7 3 0 . 0 0 4 7 2 0 . 0 0 4 7 1 0 . 0 0 4 7 0 0 . 0 0 4 6 9 0 . 0 0 4 6 8 0 . 0 0 4 6 7 0 . 0 0 4 6 6 0 . 0 0 4 6 5 0 . 0 0 4 6 4 0 . 0 0 4 6 3 0 . 0 0 4 6 2 0 . 0 0 4 6 1 0 . 0 0 4 6 0 . 0 . 0 0 4 5 9 0 . 0 0 4 5 8 0 . 0 0 4 5 7 0 . 0 0 4 5 6 0 . 0 0 4 5 5 0 . 0 0 4 54 0 . 0 0 4 5 3 0 . 0 0 4 5 2 0 . 0 0 4 5 1 0 . 0 0 4 5 0 0 . 0 0 4 4 9 0 . 0 0 4 4 8 0 . 0 0 4 4 7 0 . 0 0 4 4 6 0 . 0 0 4 4 5 0 . 0 0 4 4 4 I A SRP7/SR86 0 . 6 9 9 9 8 0 . 6 9 9 9 9 0 . 6 9 9 9 9 0 . 7 0 0 0 0 0 . 7 0 000 0 . 7 0 0 0 1 0 . 7 0 0 0 1 0 . 7 0 0 0 2 0 . 7 0 0 0 2 0 . 7 0 0 0 3 0 . 7 0 0 0 3 0 . 7 0 0 0 4 0 . 70004 0 . 7 0 0 0 5 0 . 7 0 0 0 5 0 . 7 0 0 0 6 0 . 7 0 0 0 6 0 . 7 0 0 0 7 0 . 7 0 0 0 7 0 . 7 0 0 0 8 0 . 7 0 0 0 8 0 . 7 0 0 0 9 0 . 7 0 0 0 9 0 . 7 0 0 1 0 0 . 7 0 0 1 0 0 . 7 0 0 1 1 0 . 7 0 0 1 1 0 . 7 0 0 1 2 0 . 7 0 0 1 2 0 . 7 0 0 1 3 0 . 7 0 0 1 3 0 . 7 0 0 1 4 0 . 7 0 0 1 4 0 . 7 0 0 1 5 0 . 7 0 0 1 5 0 . 70016 0 . 7 0 0 1 6 0 . 7 0 0 1 7 0 . 7 0 0 1 7 0 . 7 0 0 1 8 0 . 7 0 0 1 8 0 . 7 0 0 1 9 0 . 7 C 0 1 9 0 . T 0 0 2 0 0 . 7 0 0 2 0 0 . 7 0 0 2 1 0 . 7 0 0 2 1 0 . 7 0 0 2 2 0 . 7 0 0 2 2 0 . 7 0 0 2 3 0 . 7 0 0 2 3 0 . 7 0 0 2 4 0 . 7 0 0 2 4 0 . 7 0 0 2 5 0 . 7 0 0 2 5 0 . 7 0 0 2 6 0 . 7 0 0 2 6 T I ME - 2 5 0 0 . - 2 4 7 5 . - 2 4 5 0 . - 2 4 2 5 . - 2 4 0 0 . - 2 3 7 5 . - 2 3 5 0 . - 2 3 2 5 . - 2 3 0 0 . - 2 2 7 5 . - 2 2 5 0 . - 2 2 2 5 . - 2 2 0 0 . - 2 1 7 5 . - 2 1 5 0 . - 2 1 2 5 . - 2 1 0 0 . . - 2 0 7 5 . - 2 0 5 0 . - 2 0 2 5 . - 2 0 0 0 . - 1 9 7 5 . - 1 9 5 0 . - 1 9 2 . 5 . - 1 9 0 0 . - 1 8 7 5 . - 1 8 5 0 . - 1 8 2 5 . - 1 6 0 0 . - 1 7 7 5 . - 1 7 5 0 . - 1 7 2 5 . - 1 7 0 0 . - 1 6 7 5 . - 1 6 5 0 . - 1 6 2 5 . - 1 6 0 0 . - 1 5 7 5 . - 1 5 5 0 . - 1 5 2 5 . - 1 5 0 0 . - 1 4 7 5 . - 1 4 5 0 . - 1 4 2 5 . - 1 4 0 0 . - 1 3 7 5 . - 1 3 5 0 . - 1 3 2 5 . - 1 3 0 0 . - 1 2 7 5 . - 1 2 5 0 . - 1 2 2 5 . - 1 2 0 0 . - 1 1 7 5 . - 1 1 5 0 . - 1 1 2 5 . - 1 1 0 0 . S Y S T E M n i n Rli/ C ,R SR8 0 . 0 7 0 0 0 0 . 0 . 0 7 0 2 0 0 . 0 . 0 7 0 4 0 0 . 0 . 0 7 0 6 0 0 . 0 . 0 7 0 8 0 0 . 0 . 0 7 1 0 0 0 . 0 . 0 7 1 2 0 0 . 0 . 0 7 1 4 0 0 . 0 . 0 7 1 6 0 0 . 0 . 0 7 1 8 0 0 . 0 . 0 7 2 0 0 0 . 0 . 0 7 2 2 0 0 . 0 . 0 7 2 4 0 0 . 0 . 0 7 2 6 0 0 . 0 . 0 7 2 8 0 0 . 0 . 0 7 3 0 0 0 . 0 . 0 7 3 2 0 0 . 0 . 0 7 3 4 0 0 . 0 . 0 7 3 6 0 0 . 0 . 0 7 3 8 0 0 . 0 . 0 7 4 0 0 0 . 0 . 0 742 0 0 . 0 . 0 7440 0 . 0 . 0 7 4 6 0 0 . 0 . 0 7 4 8 0 0 . 0 . 0 7 5 0 0 0 . 0 . 0 7520 0 . 0 . 0 7 5 4 0 0 . 0 . 0 7 5 6 0 0 . 0 . 0 7 5 8 0 0 . 1 0 . 0 7 6 0 0 0 . 0 . 0 7 6 2 0 0 . 0 . 0 7640 0 . 0 . 0 7 6 6 0 0 . 0 . 0 7 6 8 0 0 . 0 . 0 7 7 0 0 0 . 0 . 0 7 7 2 0 0 . 0 . 0 7 7 4 0 0 . 0 . 0 7 7 6 0 0-0 . 0 7 7 8 0 0 . 0 . 0 7 8 0 0 0 . 0 . 0 7 8 2 0 . 0 . 0 . 0 7 8 4 0 0 . 0 . 0 7 8 6 0 0 . ' 0 . 0 7 8 8 0 0 . 0 . 0 7 9 0 0 0 . 0 . 0 7 9 2 0 0 . 0 . 0 7 9 4 0 0 . 0 . 0 7 9 6 0 0 . 0 . 0 7 9 8 0 0 . 0 . 0 8 0 0 0 0 . 0 . 0 8 0 2 0 0 . 0 . 0 8.04 0 0 . 0 . 0 8 0 6 0 0 . 0 . 0 8 0 8 0 0 . 0 . 0 8 1 0 0 0 . 0 . 0 8 1 2 0 0 . 7/SPR6 70349 70356 70364 70371 70379 70386 70394 70401 70409 704 1 7 70424 704 3 2 704 4 0 704 4 7 70455 70463 70471 704 79 70486 70494 70502 70510 7051 8 70526 705 34 70542 70550 70558 70566 70574 70582 70590 70598 70606 70614 7062 3 70631 70639 7064 7 70656 70664 706 72 70681 70689 , 70697 ' 70706 70714 70 72 3 70731 707 4 0 70748 70 757 70765 70774 70782 70791 7 0 7 9 9 1 0 7 5 . 0 . 0 0 4 4 3 0 . 7 0 0 2 7 - 1 0 7 5 . 0 . 0 8 1 4 0 0 . 7 0 8 0 8 1 0 5 0 . 0 . 0 0 4 4 2 0 . 7 C 0 2 7 - 1 0 5 0 . 0 . 0 8 1 6 0 0 . 7 0 8 17 1 0 2 5 . 0 . 0 0 4 4 1 0 . 7 0 0 2 7 - 1 0 2 5 . 0 . 0 8 1 8 0 0 . 7 0 0 2 6 •1000. 0 . 0 0 4 4 0 0 . 7 0 0 2 8 - 1 0 0 0 . 0 . 0 8 2 0 0 0 . 7 0 8 3 4 - 9 7 5 . 0 . 0 0 4 3 9 0 . 7 0 0 2 8 - 9 7 5 . 0 . 0 8 2 2 0 0 . 7 0 8 4 3 - 9 5 0 : 0 . 0 0 4 3 8 0 . 7 0 0 2 9 - 9 5 0 . 0 . 0 8 2 4 0 0 . 7 0 8 5 2 - 9 2 5 . 0 . 0 0 4 3 7 0 . 7 0029 - 9 2 5 . 0 . 0 8 2 6 0 0 . 7 0 R 6 1 - 9 0 0 . 0 . 0 0 4 3 6 0 . 7 0 0 3 0 - 9 0 0 . 0 . 0 8 2 8 0 0 . 7 0 8 6 9 - 8 7 5 . 0 . 0 0 4 3 5 0 . 7 0 0 3 0 - 8 7 5 . 0 . 0 8 3 0 0 0 . 7 C M 7 8 - 8 5 0 . 0 . 0 0 4 3 4 0 . 7 0 0 3 1 - 8 5 0 . 0 . 0 8 3 2 0 0 . 7 3 8 8 7 - 8 2 5 . 0 . 0 0 4 3 3 0 . 7 0 0 3 1 - 8 2 5 . 0 . 0 8 3 4 0 0 . 7 0 B 9 6 - 8 0 0.' 0 . 0 0 4 3 2 0 . 7 0 0 3 2 - 8 0 0 . 0 . 0 8 3 6 0 0 . 7 0 9 0 5 - 7 7 5 . 0 . 0 0 4 3 1 0 . 7 0 0 3 2 - 7 7 5 . 0 . 0 8 3 8 0 0 . 7 0 9 1 4 - 7 5 0 . 0 . 0 0 4 3 0 0 . 7 0 0 3 2 - 7 5 0 . 0 . 0 8 4 0 0 0 . 7 0 9 2 3 - 7 2 5 . 0 . 0 0 4 2 9 0 . 7 0 0 3 3 - 7 2 5 . 0 . 0 8 4 2 0 0 . 7 0 9 3 2 - 7 0 0 . 0 . 0 0 4 2 8 0 . 7 0 0 3 3 - 7 0 0 . 0 . 0 8 4 4 0 0 . 70940 - 6 7 5 . 0 . 0 0 4 2 7 0 . 7 0034 - 6 7 5 . 0 . 0 8 4 6 0 0 . 7 0 9 4 9 - 6 5 0 . 0 . 0 0 4 2 6 0 . 7 0 0 3 4 - 6 5 0 . 0 . 0 8 4 0 0 0 . 7 0 9 5 9 - 6 2 5 . 0 . 0 0 4 2 5 0 . 7 0 0 3 5 - 6 2 5 . 0 . 08 r>00 0 . 7 0 9 6 8 - 6 0 0 . 0 . 0 0 4 2 4 0 . 7 0 0 3 5 - 6 0 0 . 0 . 0 8 5 2 0 0 . 7 0 9 7 7 - 5 7 5 . 0 . 0 0 4 2 3 0 . 7 0 0 3 6 - 5 7 5 . 0 . 0 8 5 4 0 0 . 7 0 9 3 6 - 5 5 0 . 0 . 0 0 4 2 2 0 . 7 0 0 3 6 - 5 5 0 . 0 . 0 8 5 6 0 0 . 7 0 9 9 5 - 5 2 5 . 0 . 0 0 4 2 1 0 . 7 0 0 3 7 - 5 2 5 . 0 . 0 8 5 8 0 0 . 71 004 - 5 0 0 . 0 . 0 0 4 2 0 0 . 7 0 0 3 7 - 5 0 0 . 0 . 0 0 6 0 0 0 . 7 1 0 1 3 - 4 7 5 . 0 . 0 0 4 1 9 0 . 7003 7 - 4 7 5 . 0 . 0 8 6 2 0 0 . 7 1 0 2 2 - 4 5 0 . 0 . 0 0 4 1 0 0 . 7 0 0 3 8 - 4 5 0 . 0 . 0 8 6 4 0 0 . 7 1 0 3 1 - 4 2 5 . 0 . 0 0 4 1 7 0 . 7 0 0 3 8 - 4 2 5 . 0 . 0 866 0 0 . 7 1 0 4 1 - 4 0 0 . 0 . 0 0 4 1 6 0 . 7 0 0 3 9 - 4 0 0 . 0 . 0 8 6 8 0 0 . 7 1 0 5 0 - 3 7 5 . 0 . 0 0 4 1 5 0 . 7 0 0 3 9 - 3 7 5 . 0 . 0 8 7 0 0 0 . 7 1 0 5 9 - 3 5 0 . 0 . 0 0 4 1 4 0 . 7 0 0 4 0 - 3 5 0 . 0 . 0 8 7 2 0 0 . 7 1 0 6 8 - 3 2 5 . 0 . 0 0 4 1 3 0 . 7 0 0 4 0 - 3 2 5 . 0 . 0 B 7 4 0 0 . 7 1 0 7 8 - 3 0 0 . 0 . 0 0 4 1 2 0 . 7 0 0 4 0 - 3 0 0 . 0 . 0 8 7 6 0 0 . 71 08 7 - 2 7 5 . 0 . 0 0 4 1 1 0 . 7 0 0 4 1 - 2 7 5 . 0 . 0 . 6 7 8 0 0 . 7 1 0 9 6 - 2 5 0 . 0 . 0 0 4 1 0 0 . 7 0 0 4 1 - 2 5 0 . 0 . 0 P 8 0 0 0 . 7 1 1 0 6 - 2 2 5 . 0 . 0 0 4 0 9 0 . 7 0 0 4 2 - 2 2 5 . 0 . 0 0 8 2 0 0 . 7 1 1 1 5 - 2 0 0 . 0 . 0 0 4 0 8 0 . 7 0 0 4 2 - 2 0 0 . 0 . O B 8 4 0 0 . 7 1 1 2 4 - 1 7 5 . 0 . 0 0 4 0 7 0 . 7 0 0 4 3 - 1 7 5 . 0 . 0 8 8 6 0 0 . 7 1 1 3 4 - 1 5 0 . 0 . 0 0 4 0 6 0 . 7 0 0 4 3 - 1 5 0 . 0 . 0 8 8 8 0 0 . 7 1 1 4 3 - 1 2 5 . 0 . 0 0 4 0 5 0 . 7 0 0 4 4 - 1 2 5 . 0 . 0 8 9 0 0 0 . 7 1 1 5 3 - 1 0 0 . 0 . 0 0 4 0 4 0 . 7 0 0 4 4 - 1 0 0 . 0 . 0 8 9 2 0 0 . 7 1 1 6 2 - 7 5 . 0 . 0 0 4 0 3 0 . 7 0 0 4 4 - 7 5 . 0 . 0 8 9 4 0 0 . 7 1 1 7 2 - 5 0 . 0 . 0 0 4 0 2 0 . 7 0 0 4 5 - 5 0 . 0 . 0 8 9 6 0 0 . 7 1 1 8 1 - 2 5 . 0 . 0 0 4 0 1 0 . 7 0 0 4 5 - 2 5 . 0 . 0 8 9 8 0 0 . 7 1 1 9 1 0. ' 0 . 0 0 4 0 0 0 . 7 0 0 4 6 0 . 0 . 0 9 0 0 0 0 . . 7 1 2 0 0 SYSTCM 111C TIME « B / S R S R B 7 / S R 8 6 - 2 5 0 0 . 0 . 0 2 5 0 0 0 . 7 0 2 2 7 - 2 4 7 5 . 0 . 0 2 5 0 5 0 . 7 0 2 2 9 - 2 4 5 0 . 0 . 0 2 5 1 0 0 . 7 0 2 3 2 - 2 4 2 5 . 0 . 0 2 5 1 5 0 . 7 0 2 3 5 - 2 4 0 0 . 0 . 0 2 5 2 0 0 . 7 0 2 3 7 - 2 3 7 5 . 0 . 0 2 5 2 5 0 . 7 0 2 4 0 - 2 3 5 0 . 0 . 0 2 5 3 0 0 . 7 0 2 4 3 - 2 3 2 5 . 0 . 0 2 5 3 5 0 . 7 0 2 4 6 - 2 3 0 0 . 0 . 0 2 5 4 0 0 . 7 0 2 4 8 - 2 2 7 5 . 0 . 0 2 5 4 5 0 . 7 0 2 5 1 - 2 2 5 0 . 0 . 0 2 5 5 0 0 . 7 0 2 5 4 - 2 2 2 5 . C . 0 2 5 5 5 0 . 7 0 2 5 6 - 2 2 0 0 . 0 . 0 2 5 6 0 0 . 7 0 2 5 9 - 2 1 7 5 . 0 . 0 2 5 6 5 0 . 7 0 2 6 2 - 2 1 5 0 . 0 . 0 2 5 7 0 0 . 7 0 2 6 5 - 2 1 2 5 . 0 . 0 2 5 7 5 0 . 7 0 2 6 7 - 2 1 0 0 . 0 . 0 2 5 8 0 0 . 7 0 2 7 0 - 2 0 7 5 . 0 . 0 2 5 6 5 0 . 7 0 2 7 3 - 2 0 5 0 . 0 . 0 2 5 9 0 0 . 7 0 2 7 5 - 2 0 2 5 . 0 . 0 2 5 9 5 0 . 7 0 2 7 8 - 2 0 0 0 . 0 . 0 2 6 0 0 0 . 7 0 2 8 1 - 1 9 7 5 . 0 . 0 2 6 0 5 0 . 7 0 2 8 4 - 1 9 5 0 . 0 . 0 2 6 1 0 0 . 7 0 2 8 7 - 1 9 2 5 . 0 . 0 2 6 1 5 0 . 7 0 2 8 9 - 1 9 0 0 . 0 . 0 2 6 2 0 0 . 7 0 2 9 2 - 1 8 7 5 . 0 . 0 2 6 2 5 0 . 7 0 2 9 5 - 1 8 5 0 . 0 . 0 2 6 3 0 0 . 7 0 2 9 8 - 1 8 2 5 . 0 . 0 2 6 3 5 0 . 7 0 3 0 0 - 1 R 0 0 . 0 . 0 2 6 4 0 0 . 7 0 3 0 3 - 1 7 7 5 . 0 . 0 2 6 4 5 0 . 7 0 3 0 6 - 1 7 5 0 . 0 . 0 2 6 5 0 0 . 7 0 3 0 9 - 1 7 2 5 . 0 . 0 2 6 5 5 0 . 7 0 3 1 2 - 1 7 0 0 . 0 . 0 2 6 6 0 0 . 7 0 3 1 5 - 1 6 7 5 . 0 . 0 2 6 6 5 0 . 7 0 3 1 7 - 1 6 5 0 . 0 . 0 2 6 7 0 0 . 7 0 3 2 0 - 1 6 2 5 . 0 . 0 2 6 7 5 0 . 7 0 3 2 3 - 1 6 0 0 . 0 . 0 2 6 8 0 0 . 7 0 3 2 6 - 1 5 7 5 . 0 . 0 2 6 B 5 0 . 7 0 3 2 9 - 1 5 5 0 . 0 . 0 2 6 9 0 0 . 7 0 3 3 2 - 1 5 2 5 . 0 . 0 2 6 9 5 0 . 7 0 3 3 4 - 1 5 0 0 . 0 . 0 2 7 0 0 0 . 7 0 3 3 7 - 1 4 7 5 . 0 . 0 2 7 0 5 0 . 7 0 3 4 0 - 1 4 5 0 . 0 . 0 2 7 1 0 0 . 7 0 3 4 3 - 1 4 2 5 . 0 . 0 2 7 1 5 0 . 7 0 3 4 6 - 1 4 0 0 . 0 . 0 2 7 2 0 0 . 7 0 3 4 9 - 1 3 7 5 . 0 . 0 2 7 2 5 0 . 7 0 3 5 2 - 1 3 5 0 . 0 . 0 2 7 3 0 0 . 7 0 3 5 5 - 1 3 2 5 . 0 . 0 2 7 3 5 0 . 7 0 3 5 8 - 1 3 0 0 . 0 . 0 2 7 4 0 0 . 7 0 3 6 0 - 1 2 7 5 . 0 . 0 2 7 4 5 0 . 7 0 3 6 3 - 1 2 5 0 . 0 . 0 2 7 5 0 0 . 7 0 3 6 6 - 1 2 2 5 . 0 . 0 2 7 5 5 0 . 7 0 3 6 9 - 1 2 0 0 . 0 . 0 2 7 6 0 0 . 7 0 3 7 2 - 1 1 7 5 . 0 . 0 2 7 6 5 0 . 7 0 3 7 5 - 1 1 5 0 . 0 . 0 2 7 7 0 0 . 7 0 3 7 8 - 1 1 2 5 . 0 . 0 2 7 7 5 0 . 7 0 3 8 1 - 1 1 0 0 . 0 . 0 2 7 8 0 0 . 7 0 3 8 4 S Y S T E M I I 1 0 T I M E R B / S R S K 8 7 / S K 8 6 - 2 5 0 0 . 0 . 1 8 0 C O 0 . 7 0 6 4 7 - 2 4 7 5 . 0 . 1 7 9 7 0 0 . 7 0 6 6 6 - 2 4 5 0 . 0 . 1 7 9 4 0 0 . 7 0 6 3 5 - 2 4 2 5 . 0 . 1 7 9 1 0 0 . 7 0 7 0 4 - 2 4 0 0 . 0 . 1 7 8 8 0 0 . 7 0 7 2 3 - 2 3 7 5 . 0 . 1 7 B 5 0 0 . 7 0 7 4 2 - 2 3 5 0 . 0 . 1 7 8 2 0 0 . 7 0 7 6 1 - 2 3 2 5 . 0 . 1 7 7 9 0 0 . 7 0 7 8 0 - 2 3 0 0 . 0 . 1 7 7 6 0 0 . 7 0 7 9 9 - 2 2 7 5 . 0 . 1 7 7 3 0 0 . 7 0 8 1 8 - 2 2 5 0 . 0 . 1 7 7 0 0 0 . 7 0 8 3 7 - 2 2 2 5 . 0 . 1 7 6 7 0 0 . 7 0 8 5 6 - 2 2 0 0 . 0 . 1 7 6 4 0 0 . 7 0 8 7 4 - 2 1 7 5 . 0 . 1 7 6 1 0 0 . 7 0 8 9 3 - 2 1 5 0 . 0 . 1 7 5 8 0 0 . 7 0 9 1 2 - 2 1 2 5 . 0 . 1 7 5 5 0 0 . 7 0 9 3 0 - 2 1 0 0 . 0 . 1 7 5 2 0 0 . 7 0 9 4 9 - 2 0 7 5 . 0 . 1 7 4 9 0 0 . 7 0 9 6 8 - 2 0 5 0 . 0 . 1 7 4 6 0 0 . 7 0 9 8 6 - 2 0 2 5 . 0 . 1 7 4 3 0 0 . 7 1 0 0 5 - 2 0 0 0 . 0 . 1 7 4 0 0 0 . 7 1 0 2 3 - 1 9 7 5 . 0 . 1 7 3 7 0 0 . 7 1 0 4 2 - 1 9 5 0 . 0 . 1 7 3 4 0 0 . 7 1 0 6 0 - 1 9 2 5 . 0 . 1 7 3 1 0 0 . 7 1 0 7 9 - 1 9 0 0 . 0 . 1 7 2 B 0 0 . 7 1 0 9 7 - 1 8 7 5 . 0 . 1 7 2 5 0 0 . 7 1 1 1 5 - 1 8 5 0 . 0 . 1 7 2 2 0 0 . 7 1 1 3 4 - 1 8 2 5 . 0 . 1 7 1 9 0 0 . 7 1 1 5 2 - I 8 0 0 . 0 . 1 7 1 6 0 0 . 7 1 1 7 0 - 1 7 7 5 . 0 . 1 7 1 3 0 0 . 7 1 1 8 8 • - 1 7 5 0 . 0 . 1 7 1 0 0 0 . 7 1 2 0 6 - 1 7 2 5 . P . 1 7 0 7 0 0 . 7 1 2 2 5 - 1 7 0 0 . 0 . 1 7 0 4 0 0 . 7 1 2 4 3 - 1 6 7 5 . 0 . 1 7 0 1 0 0 . 7 1 2 6 1 - 1 6 5 0 . 0 . 1 6 9 8 0 0 . 7 1 2 7 9 - 1 6 2 5 . 0 . 1 6 9 5 0 0 . 7 1 2 9 7 - 1 6 0 0 . 0 . 1 6 9 2 0 0 . 7 1 3 1 5 - 1 5 7 5 . 0 . 1 6 0 9 0 0 . 7 1 3 3 3 - 1 5 5 0 . 0 . 1 6 8 6 0 0 . 7 1 3 5 1 - 1 5 2 5 . 0 . 1 6 8 3 0 0 . 7 1 3 6 9 - 1 5 0 0 . 0 . 1 6 0 0 0 0 . 7 1 3 8 7 - 1 4 7 5 . 0 . 1 6 7 7 0 0 . 7 1 4 0 4 - 1 4 5 0 . 0 . 1 6 7 4 0 ' 0 . 7 1 4 2 2 - 1 4 2 5 . 0 . 1 6 7 1 0 0 . 7 1 4 4 0 - 1 4 0 0 . 0 . 1 6 6 8 0 0 . 7 1 4 5 8 - 1 3 7 5 . 0 . 1 6 6 5 0 0 . 7 1 4 7 5 - I 3 5 0 . 0 . 1 6 6 2 0 0 . 7 1 4 9 3 - 1 3 2 5 . 0 . 1 6 5 9 0 0 . 7 1 5 1 1 - 1 3 0 0 . 0 . 1 6 5 6 0 0 . 7 1 5 2 8 - 1 2 7 5 . 0 . 1 6 5 3 0 0 . 7 1 5 4 6 - 1 2 5 0 . 0 . 1 6 5 0 0 0 . 7 1 5 6 3 - 1 2 2 5 . 0 . 1 6 4 7 0 0 . 7 1 5 8 1 - 1 2 0 0 . 0 . 1 6 4 4 0 0 . 7 1 5 9 8 - 1 1 7 5 . 0 . 1 6 4 1 0 0 . 7 1 6 1 6 - 1 1 5 0 . 0 . 1 6 3 8 0 0 . 7 1 6 3 3 - 1 1 2 5 . 0 . 1 6 3 5 0 0 .71651 - 1 1 0 0 . 0 . 16320 0 . 7 1 6 6 8 - 1 0 7 5 . 0 . 0 2 7 8 5 0 . 7 0 3 3 7 - 1 0 7 5 . 0 . 1 6 2 9 0 0 . 7 1 6 8 5 - 1 0 5 0 . 0 . 0 2 7 9 0 0 . 7 0 3 9 0 - 1 0 5 0 . 0 . 1 6 2 6 0 0 . 7 1 7 0 3 - 1 0 2 5 . 0 . 0 2 7 9 5 0 . 7 0 3 9 3 - 1 0 2 5 . 0 . 1 6 2 3 0 0 . 7 1 7 2 0 - 1 0 0 0 . 0 . 0 2 8 0 0 0 . 7 0 3 9 6 - 1 0 0 0 . 0 . 1 6 2 0 0 0 . 7 1 7 3 7 - 9 7 5 . 0 . 0 2 h<J 5 0 . 7 0 3 9 9 - 9 7 5 . 0 . 1 6 1 7 0 0 . 7 1 7 5 4 - 9 5 0 . 0 . 0 2 8 1 0 0 . 7 0 4 0 2 - 9 5 0 . 0 . 1 6 1 4 0 0 . 7 1 7 7 1 - 9 2 5 . 0 . 0 2 ( 1 1 5 0 . 7 0 4 0 5 - 9 2 5 . 0 . 1 6 1 1 0 0 . 7 1 7 8 9 - 9 ( 1 0 . 0 . 0 2 8 2 0 0 . 7 0 4 0 8 - 9 0 0 . 0 . 1 6 0 8 0 0 . 7 1 8 0 6 - 8 7 5 . 0 . 0 2 8 2 5 0 . 7 0 4 1 1 - 8 7 5 . 0 . 1 6 0 5 0 0 . 7 1 8 2 3 - 8 5 0 . 0 . 0 2 8 3 0 0 . 7 0 4 1 4 - 8 5 ( 1 . 0 . 1 6 0 2 0 0 . 7 1 8 4 0 - 8 2 5 . 0 . 0 2 8 3 5 0 . 7 0 4 1 7 - 8 2 5 . 0 . 1 5 9 9 0 0 . 7 1 0 5 7 - 8 0 0 . 0 . 0 2 H 4 0 0 . 7 0 4 2 0 - 8 0 0 . 0 . 1 5 9 6 0 0 . 7 1 8 7 4 - 7 7 5 . 0 . 0 2 8 4 5 0 . 7 0 4 2 3 - 7 7 5 . 0 . 1 5 9 3 0 0 . 7 1 8 9 1 - 7 5 0 . 0 . 0 2 8 5 0 0 . 7 0 4 2 6 - 7 5 0 . 0 . 1 5 9 0 0 0 . 7 1 9 0 8 - 7 2 5 . 0 . C 2 8 5 5 0 . 7 0 4 2 9 - 7 2 5 . 0 . 1 5 8 7 0 0 . 7 1 9 2 5 - 7 0 0 . 0 . 0 2 8 6 0 0 . 7 0 4 3 2 - 7 0 0 . 0 . 1 5 8 4 0 0 . 7 1 9 4 1 - 6 7 5 . 0 . 0 2 8 6 5 0 . 7 0 4 3 5 - 6 7 5 . 0 . 1 5 8 1 0 0 . 7 1 9 5 8 - 6 5 0 . 0 . 0 2 R 7 0 0 . 7 0 4 3 8 - 6 5 0 . 0 . 1 5 7 8 0 0 . 7 1 9 7 5 - 6 2 5 . 0 . 0 2 8 7 5 0 . 7 0 4 4 1 . - 6 2 5 . 0 . 1 5 7 5 0 0 . 7 1 9 9 2 - 6 0 0 . 0 . 0 2 8 8 0 0 . 7 0 4 4 4 - 6 0 0 . 0 . 1 5 7 2 0 0 . 7 2 0 0 8 - 5 7 5 . 0 . 0 2 8 6 5 0 . 7 0 4 4 7 - 5 7 5 . 0 . 1 5 6 9 0 0 . 7 2 0 2 S - 5 5 0 . 0 . 0 2 8 9 0 0 . 7 0 4 5 0 - 5 5 0 . 0 . 1 5 6 6 0 0 . 7 2 0 4 2 - 5 2 5 . 0 . 0 2 8 9 5 0 . 7 0 4 5 3 - 5 2 5 . 0 . 1 5 6 3 0 0 . 7 2 0 5 8 - 5 0 0 . 0 . 0 2 9 0 0 0 . 7 C 4 5 6 - 5 0 0 . 0 . 1 5 6 0 0 0 . 7 2 0 7 5 - 4 7 5 . 0 . 0 2 9 0 5 0 . 7 0 4 6 0 - 4 7 5 . 0 . 1 5 5 7 0 0 . 7 2 0 9 2 - 4 5 0 . 0 . 0 2 9 1 0 0 . 7 0 4 6 3 - 4 5 0 . 0 . 1 5 5 4 0 0 . 7 2 1 0 8 - 4 2 5 . 0 . 0 2 9 1 5 0 . 7 0 4 6 6 - 4 2 5 . 0 . 1 5 5 1 0 0 . 7 2 1 2 5 - 4 0 0 . 0 . 0 2 9 2 0 0 . 7 0 4 6 9 - 4 0 0 . 0 . 1 5 4 8 0 0 . 7 2 1 4 1 - 3 7 5 . 0 . 0 2 9 2 5 0 . 7 0 4 7 2 - 3 7 5 . 0 . 1 5 4 5 0 0 . 7 2 1 5 7 - 3 5 0 . 0 . 0 2 9 3 0 0 . 7 0 4 7 5 - 3 5 0 . 0 . 1 5 4 2 0 0 . 7 2 1 7 4 - 3 2 5 . 0 . 0 2 9 3 5 0 . 7 0 4 7 8 - 3 2 5 . 0 . 1 5 3 9 0 0 . 7 2 1 9 0 - 3 0 0 . 0 . 0 2 9 4 0 0 . 7 0 4 8 1 - 3 0 0 . 0 . 1 5 3 6 0 0 . 7 2 2 0 7 - 2 7 5 . 0 . 0 2 9 4 5 0 . 7 0 4 8 4 - 2 7 5 . 0 . 1 5 3 3 0 0 . 7 2 2 2 3 - 2 5 0 . 0 . 0 2 9 5 0 0 . 7 0 4 8 8 - 2 5 0 . 0 . 1 5 3 0 0 0 . 7 2 2 3 9 - 2 2 5 . 0 . 0 2 9 5 5 0 . 7 0 4 9 1 - 2 2 5 . 0 . 1 5 2 7 0 0 . 7 2 2 5 5 - 2 0 0 . 0 . 0 2 7 6 0 0 . 7 0 4 9 4 • 2 0 0 . 0 . 1 5 2 4 0 0 . 7 2 2 7 2 - 1 7 5 . 0 . 0 2 9 6 5 0 . 7 0 4 9 7 - 1 7 5 . 0 . 1 5 2 1 0 0 . 7 2 2 8 8 - 1 5 0 . 0 . 0 2 9 7 0 0 . 7 0 5 0 0 - 1 5 0 . 0 . 1 5 1 P 0 0 . 7 2 3 0 4 - 1 2 5 . 0 . 0 2 9 7 5 0 . 7 0 5 0 3 - 1 2 5 . 0 . 1 5 1 5 0 0 . 7 2 3 2 0 - 1 0 0 . 0 . 0 2 9 8 0 0 . 7 0 5 0 6 - 1 0 0 . 0 . 1 5 1 2 0 0 . 7 2 3 3 6 - 7 5 . 0 . 0 2 9 8 5 0 . 7 0 5 1 0 - 7 5 . 0 . 1 5 0 9 0 0 . 7 2 3 5 2 - 5 0 . 0 . 0 2 9 9 0 0 . 7 0 5 1 3 - 5 0 . 0 . 1 5 0 6 0 0 . 7 2 3 6 8 - 2 5 . 0 . 0 2 9 9 5 0 . 7 0 5 1 6 - 2 5 . 0 . 1 5 0 3 0 0 . 7 2 3 8 4 0 . 0 . 0 3 0 0 0 0 . 7 0 5 1 9 0 . 0 . 1 5 0 0 0 0 . 7 2 4 0 0 —I 

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