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Application of K-Ar and fission-track dating to the metallogeny of porphyry and related mineral deposits.. Christopher, Peter Allen 1973

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APPLICATION OF K-Ar AND FISSION-TRACK DATING TO THE METALLOGENY OF PORPHYRY AND RELATED MINERAL DEPOSITS IN THE CANADIAN CORDILLERA  by PETER ALLEN CHRISTOPHER B.Sc,  State University of New York at Fredonia, 1966  M.A., Dartmouth College, Hanover, New Hampshire, 1968  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in the Department of Geological Sciences  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA . May, 1973  In presenting  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the Library 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 reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may by h i s representatives.  be granted by the Head of my Department or I t i s understood that copying or p u b l i c a t i o n  of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission.  Department of The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada  ii.  .  ABSTRACT .  This study evaluates the concept of metallogenic epochs as it applies to porphyry mineral deposits of the Canadian Cordillera, extends the study of the age of porphyry mineral deposits into northern British Columbia and the Yukon Territory, evaluates the usefulness of the fission-track dating method in determining the age and history of porphyry mineral deposits, and demonstrates the usefulness of an Ar^ total vs %K isochron plot. Samples were obtained from six areas in the Canadian Cordillera: the Syenite Range and Burwash Landing area in the Yukon Territory and Cassiar area, Adanac Property, Granisle Mine, and Copper Mountain area in British Columbia. Apatite was separated from the samples for use in fission-track analysis, and co-genetic biotite or hornblende was separated in order to obtain K-Ar checks on the fission-track ages. A comparison of fifteen apatite fission-track ages with K-Ar ages demonstrates that the apatite fission-track method can be used to age date porphyry mineral deposits, however the K-Ar method is generally more suitable in terms of cost and reliability.  Discordant apatite fission-track and  biotite K-Ar ages obtained from the Copper Mountain area and Granisle Mine suggest that apparent apatite fission-track ages from highly altered rocks or thermally complex areas should be checked by using another dating method (e.g. K-Ar). Radiometric dating of the Cassiar Molybdenum, Adanac, Mt. Reed and Mt. Haskin porphyry mineral deposits in northern British Columbia suggests that the Early Tertiary metallogenic.epoch- for porphyry deposits in central British  iii.  Columbia and south-eastern Alaska, can be extended through northern British Columbia. Post-Eocene intermittent subduction of the Juan de Fuca plate below Vancouver Island and transverse motion along the Fairweather-Queen CharlotteShakwak-Denali Fault system with subduction into the Aleutian Trench are consistent with present plate-tectonic theory and the distribution of postEocene calc-alkalihe igneous rocks in the Canadian Cordillera.  If porphyry  mineral deposits form in calc-alkaline igneous rocks above active subduction zones, then the youngest porphyry deposits i n the Canadian Cordillera should occur west of the Fairweather-Queen Charlotte-Shakwak-Denali  fault system,  on Vancouver Island and in the Cascade Mountains. The relatively young 26.2 m.y. biotite K-Ar age determined for the Burwash Creek porphyry west of the Shakwak Trench i n the Yukon Territory is consistent with the evolution of porphyry mineral deposits above an active subduction zone. Comparison of K-Ar ages obtained for this study with published K-Ar ages suggests that metallogenic epochs for porphyry mineral deposits i n the Canadian Cordillera occurred at approximately 195 m.y. and 150 + 10 m.y. for deposits of the plutonic and volcanic porphyry classes; and at approximately 100 m.y.,  80 nwy., 65 m.y.,  the phallic porphyry class.  50 m.y.,  35r40 m.y. and 26 m.y. for deposits of  iv.  ACKNOWLEDGMENTS  Support for this study was provided through grants to Drs. A.J. Sinclair and W.H. White from the National Research Council of Canada and the Geological Survey of Canada.  The writer was supported by  teaching assistantships and a university fellowship from the University of British Columbia. The writer appreciates the assistance and co-operation of mining companies involved in exploration in northern British Columbia and the Yukon Territory. G. Brett (Brettland Mines), R..Oddy (Imperial O i l ) , W. Sirola (Kerr Addison Mines), G. Lamont (Delia Mines), and G. LeCheminant (Amax Exploration Inc.) were especially helpful. Several geologists employed by the British Columbia Department of Mines and by the Geological Survey of Canada provided helpful discussions of the geological settings of porphyry deposits in the Canadian Cordillera. Dr. V.A. Preto and N.C.  Carter (B.C. Dept. Mines) and Drs. H. Gabrielse  and J.W.H. Monger (Geological Survey of Canada) were especially helpful. The late Drs. J.A. Gower and W.H. White were instrumental in stimulating the writers interest in porphyry mineral deposits of the Canadian Cordillera.  Their advice and encouragement contributed greatly to  this study. Drs. A.J. Sinclair, H.R. Wynne-Edwards, A.E. Soregaroli and W.F. Slawson made suggestions for improvement of the original manuscript. Drs. A.J. Sinclair and H.R. Wynne-Edwards supervised the study. Numerous members of the Departments of Geological Sciences and  Geophysics helped with useful discussion and advice. Miss Yvonne Colasanti, Mr. G. Cargill, Mr. B. Ryan, and Mr. J. Blenkinsop were especially helpful. analyses.  Mr. J.E. Harakal supervised the potassium and argon  CONTENTS  Page INTRODUCTION 1.1  SCOPE  1  1.2  PORPHYRY MINERAL PROPERTIES STUDIED  3  POTASSIUM-ARGON DATING 2.1 INTRODUCTION  7  2.2, K-AR METHOD  8  2.3 GRAPHICAL INTERPRETATION OF K-AR DATA  11  2.4 APPLICATION OF ISOCHRON METHOD  14  2.4.1 A r  4 0  total vs %K Isochrons  Case I.  1 7  Cape Breton Whole-Rock Samples  Case II. Tulameen Complex Hornblende Samples 2.5  SUMMARY  21  2.6 EVALUATION OF ISOCHRON METHOD  22  FISSION TRACK DATING 3.1 INTRODUCTION  23  3.2  FISSION TRACK METHOD  24  3.2.1  Procedure  25  3.2.2  Flux Determination  3.3. EVALUATION OF FISSION TRACK METHOD 3.4 PRESENTATION OF DATA 3.5 DISCUSSION OF FISSION TRACK RESULTS  27 28 32 34  3.6  COMPARISON OF K-AR AND FISSION TRACK DATING TECHNIQUES37  3.7  SUMMARY AND CONCLUSIONS  40  AREAS STUDIED 4.1 INTRODUCTION 4.2  SYENITE RANGE, YUKON TERRITORY 4.2.1  Introduction  4.2.2  General Geology and Geochronology  4.2.3 Radiometric dating 4.2.4 4.3  Discussion  CORK (BURWASH CREEK) Cu-Mo PROSPECT 4.3.1  Introduction  4.3.2  Potassium-Argon Results  4.3.3  Fission Track Results  4.3.4  Discussion  4.4 NORTHERN BRITISH COLUMBIA 4.4.1  Introduction  4.4.2  Cassiar Area Cassiar Molybdenum Property Mt. Haskin Mo and Mt. Reed Mo-W Properties Discussion  4.4.3 Atlin Area Adanac Mo Property 4.5  GRANISLE MINE, BABINE LAKE AREA, BRITISH COLUMBIA 4.5.1  Introduction  4.5.2  Potassium-Argon Dating  4.5.3  Fission Track Dating  4.5.4  Discussion  viii. Page 4.6 COPPER MOUNTAIN AREA, BRITISH COLUMBIA 4.6.1  5.  Introduction  63 63  4.6.2 General Geology  63  4.6.3 Fission Track Dating  66  4.6.4  68  Summary  REVIEW OF METALLOGENY AND METALLOGENIC EPOCHS FOR PORPHYRY MINERAL DEPOSITS OF THE CANADIAN CORDILLERA  69  5.1 INTRODUCTION  69  5.2 METALLOGENY AND METALLOGENIC EPOCHS  69  5.3 TECTONIC SETTING  71  5.4 AGE DATING AND METALLOGENIC EPOCHS  77  5.5 PLATE TECTONICS AND METALLOGENY OF PORPHYRY MINERAL DEPOSITS 85 6. CONCLUSIONS  88  REFERENCES  93  APPENDIX A. DESCRIPTION OF SAMPLES USED FOR K-Ar AND FISSION TRACK AGE DETERMINATIONS  104  APPENDIX B. POTASSIUM-ARGON DATING B.1 PROCEDURE  110  B.2 PRECISION AND ACCURACY  110  B.3 ATMOSPHERIC CONTAMINATION  112  B. 4 APPLICATION OF A r  (rad.) vs %K ISOCHRONS TO  PUBLISHED DATA  112  B.4.1  Guichon Batholith  112  B.4.2 Topley Intrusions  116  B.4.3  116  Summary  APPENDIX C. FISSION TRACK DATING C. l  4 0  Introduction  118 118  Page C.2 Procedure  1  1  8  APPENDIX D. TABLE OF PUBLISHED K-Ar AGES REVIEWED FOR THIS REPORT  132  X.  LIST OF TABLES Page Table 1-1  Classification of deposits studied.  6  2-1  Potassium-argon analytical data (ages obtained for this study).  9  2-2  Isotopic abundance of potassium and argon.  10  2-3  Analytical data and ages of Cape Breton whole rock samples.  18  2- 4  Analytical data and ages of hornblende from Tulameen Complex.  3- 1  Fission track analytical data and ages.  33  4- 1  Fission-track and K-Ar ages obtained for granitic rocks in the Syenite Range, Yukon Territory. Fission-track and K-Ar ages obtained for granitic rocks in the Burwash Landing area, Yukon Territory.  45  4-3  Fission-track and K-Ar ages obtained for granitic rocks in northern British Columbia.  54  4-4  Fission-track and K-Ar ages for granitic rocks in the Copper Mountain area, British Columbia.  68  B-l  Potassium-argon data for Guichon Creek Batholith.  113  B-2  Potassium-argon data for the Topley Intrusions.  114  C-l  Frantz separation settings for desired mineral separation.  120  C-2  Etching techniques used for materials studied.  125  C-3  Etching conditions for fission-track counting.  124  D-l  Published K-Ar ages referred to in this report.  132  4-2  49  XI.  LIST OF FIGURES Page Figure 1-1  Location map of areas studied.  5  2-1  Isochron plots for quartz latite porphyry near Burwash Creek, Yukon Territory.  15  2-2  Isochron plots for Mt. Reed and Mt. Haskin porphyries.  16  2-3  Total and corrected A r whole-rock K-Ar data.  2- 4  Comparison of Ar ^ total isochron with Ar^O corrected isochron diagram for K-Ar hornblende data from the Tulameen Complex, British Columbia.  20  3- 1  Graphical comparison of apatite fission-track and  35  40  vs %K isochrons for  4  19  biotite potassium-argon apparent ages. 3- 2  Track-loss curves for epidote, sphene, and apatite.  38  4- 1  General geology and geochronology of the Syenite Range, Yukon Territory. General geology and geochronology in the Burwash Landing area, Yukon Territory.  43  4-2  47  4-3  General geology and geochronology of the Cork prospect.47  4-4  General geology and geochronology in the Cassiar area, 52 B.C., Mt. Haskin Mo property and Mt. Reed Mo-W property.  4-5  General geology and geochronology in the Atlin area and of the Adera Claims - Adanac Mo property.  4-6  Geochronology and general geology of the Granisle Mine 61 pit.  4- 7  General geology of the Copper Mountain area, British Columbia.  64  5- la  Tectonic setting of porphyry mineral deposits in the Canadian Cordillera (49-52°N).  72  5-lb  Tectonic setting of porphyry mineral deposits in the Canadian Cordillera (52-56°N).  73  5-lc  Tectonic setting of porphyry mineral deposits in the Canadian Cordillera (56-64°N).  74  53  xii.  LIST OF FIGURES (Cont.) Page Figure 5-2  Tectonic map of the Canadian Cordillera.  76  5-3  K-Ar age determinations for igneous rocks in the Canadian Cordillera.  79  5-4  K-Ar age determinations for igneous rocks in segments 80 of the Canadian Cordillera between 49-52°N, 52-56°N and 56-64°N.  5-5  K-Ar age of porphyry mineral deposits in the Canadian82 Cordillera.  5-6  Triassic lavas and the Triassic and Jurassic porphyry83 deposits.  5-7  Early Tertiary volcanic rocks and porphyry deposits. 84  B-l  Estimated precision for determining the ^kr/^K ratio as a function of the atmospheric correction.  B-2a  Isochron plots for data from the Guichon Batholith, 115 Topley Intrusions, and sample T68-33 from the Topley Intrusions.  B-2b  Isochron plot for the Witches Brook Phase of the Guichon Batholith.  115  C-l  Flowsheet for mineral separating.  119  111  LIST OF PLATES Plate  1  Microphotograph showing spontaneous fission-tracks in standard apatite sample Me/G-1. 128  2  Microphotograph showing induced tracks in standard apatite Me/G-1.  128  3  Microphotograph showing spontaneous fission-tracks in sphene sample JH5. 128  4  Microphotograph showing faint induced fission-tracks in sphene sample JH5. 130  5  Microphotograph showing induced fission-tracks produced in standard glass used to calibrate reactor run. 130  6  Microphotograph showing induced fission-tracks in standard glass used to calibrate a reactor run.  130  LIST OF PLATES  (Cont.)  Microphotograph showing central part of a rectic used for measuring area from which track count was obtained.  1.  1. INTRODUCTION  1.1 SCOPE The purpose of this study is to investigate the age of porphyry mineral deposits in northern British Columbia and southwestern Yukon Territory, and wherever possible, to compare the relatively new fissiontrack method with the well-known potassium-argon method. In addition to dating samples from northern British Columbia and the Yukon Territory, where only reconnaissance radiometric dating is available, samples previously dated by the potassium-argon method were obtained from the Copper Mountain area, Brenda Mine and Granisle Mine to compare apatite and (or) sphene fission track ages for these samples. The isochron method is applied to potassium-argon data obtained for this study and published potassium-argon data from the Topley Intrusions and Guichon Batholith to evaluate the effect of excess initial argon on potassium-argon age determinations. A new A r ^ total vs %K, method of plotting isochrons is presented and evaluated. Finally, the concept of metallogenic epochs is evaluated for porphyry and related mineral deposits in the Canadian Cordillera in the light of the age determinations reported and the new global tectonics. Six samples from the Burwash Landing area and six samples from the Cassiar area were collected by the writer during the 1969 field season. A sample from the Granisle Mine and ten samples from the Copper Mountain area were obtained from the British Columbia Department of Mines. A sample of coarse alaskite from the Adanac Mine was obtained from W. Sirola of Kerr Addison Mines and two samples of quartz monzonite from the Syenite Range were collected for the writer by C. Godwin and K. Dawson of Atlas Exploration.  2.  Biotite, hornblende, apatite, sphene and zircon were separated from the samples for dating.  A sphene concentrate from quartz diorite at Brenda  Mines was provided by Dr. W.H.  White.  Fifteen biotite K-Ar ages, two  hornblende K-Ar ages and fifteen apatite fission-track ages were determined by the writer at the University of British Columbia in geochronology laboratories of the Departments of Geological Sciences and Geophysics. Parts of this study have been published: Christopher, P.A., White, W.H., and Harakal, J.E. , 1972a. K-Ar dating of the 'Cork' (Burwash Creek) Cu-Mo prospect, Burwash Landing area, Yukon Territory. Can. J. Earth Sci., 9, pp. 918-921. , 1972b. Age of molybdenum and tungsten mineralization in northern British Columbia. Can. J. Earth Sci., 9, pp. 1727-1734. Christopher, P.A., 1972. Metallogenic epochs for "porphyry type" mineral deposits in the Canadian Cordillera (Abstr.). In Proceedings of the 9th. Annual Western Inter-University Geological Conference, Vancouver, B.C. p. 15. , 1973. Application of apatite fissiontrack dating to the study of porphyry mineral deposits. Can. J. Earth Sci., 10, May, in press.  3.  1.2  PORPHYRY MINERAL PROPERTIES STUDIED The term porphyry copper refers to large low-grade copper deposits  that are spatially, temporally and genetically related to porphyritic intrusive rocks.  Porphyry mineral deposits in the Canadian Cordillera  include mineral deposits of copper, molybdenum and (or) tungsten with one or more of these metals of economic interest. Sutherland Brown (1972) suggested that the porphyry deposits of the Canadian Cordillera have the following unifying characteristics: 1) Porphyry deposits consist of pervasive primary mineralization sparsely distributed in fracture or veinlet stockworks, breccias, or disseminations that are intimately related to porphyritic plutons. 2) Mineralization and alteration are distributed in porphyry or host in zonal patterns. 3) Plutons may be formed from magma of either granitic or syenitic affiliations. Sutherland Brown used variation within these unifying characteristics to classify porphyry deposits as: 1) phallic, 2) volcanic and 3) plutonic porphyry deposits.  The criteria used to classify a porphyry deposit are:  1) size and shape of pluton, 2) position and distribution of mineralization and alteration, 3) stage in orogenic cycle, and 4) age relationship of deposit and host.  The f i r s t two criteria can be evaluated from careful  empirical observation and routine laboratory investigation.  The last two  criteria require sophisticated isotopic analysis of samples of the intrusive and host rocks.  These later criteria, the evaluation of the age and geologic  setting of porphyry mineral deposits, were investigated during this study.  4.  The K-Ar method i s extremely useful in age dating igneous rocks of Mesozoic and Cenozoic age. Porphyry mineral deposits i n the Canadian Cordillera are of Mesozoic and Cenozoic age, and therefore, the K-Ar method i s suitable for dating the age of porphyry mineral deposits.  The  apatite fission-track method is also useful for dating Mesozoic and Cenozoic rocks, and this method of dating porphyry mineral deposits i s evaluated in sections 3.3 and 3.5. Areas studied by K-Ar and fission-track dating methods are located on Figure 1-1.  The Burwash Landing area, Syenite Range, Cassiar area, and  Adanac property were selected to extend the dating of porphyry mineral deposits into northern British Columbia and the Yukon Territory.  Samples  previously dated by the biotite K-Ar method were obtained from the Copper Mountain area (Preto et a l . , 1971) and the Granisle Mine (Carter, 1972b) to compare biotite K-Ar ages with apatite fission-track ages.  Table 1-1 i s  an application of Sutherland Brown's (1972) porphyry classication to the deposits studied.  5.  1. SYENITE  RANGE  2. BURWASH  LANDING  CORK 3. CASSIAR  PROPERTY AREA  MT. H A S K I N "MT. REED CASSIAR 4. GRANISLE 5. COPPER 3A. A D A N A C /  ^  c >  MOLYBDENUM MINE  MOUNTAIN PROPERTY  YUKON l«-  Figure 1 - 1 .  @j  3A  PROPERTY  PROPERTY  2  ^  AREA  B.C.  Location map for areas studied.  AREA  Table 1-1.  Classification of deposits studied  Age m.y.  Host Age  Mineralization  3000' Qtz. x 1000'? latite  26.2  Permian & Triassic  Cu, Mo in stock late and host  6000' Alaskite x 3500'?  62.0  P e rmo-P enn- Mo, W in stock sylvanian & Jurassic  Mt. Haskin Omineca  4000' Granite x 4000' porphyry  50.1  Cambrian  Mo in stock and late host  Phallic  Mt. Reed  1000' Granite x 3000'? porphyry  49.5  Cambrian  Mo, W in stock and host  late  Phallic  Cassiar Omineca Molybdenum  2000' x 500'  less 70.0  Cretaceous 70.0 m.y.  Mo, Cu i n stock late and host  Phallic  Granisle  2000' Bio.-Feld. x 1500' porphyry  51.2  Triassic & Jurassic  Cu in stock and late host  Phallic  complex  193  Late Triassic  Cu in stock and early host  Volcanic  Deposit  Tectonic Belt  Burwash Creek  Insular  Adanac  Intermontane  Omineca  Intermontane  Copper Intermontane Mountain & Ingerbelle  Shape  Pluton Composition  Latite  Syenite to Diorite  Stage  late  Type  Phallic Phallic(?)  7.  •2.  POTASSIUM-ARGON DATING  2.1 INTRODUCTION The K-Ar method has been reviewed by Hamilton (1965), Damon (1968), Dalrymple and Lanphere (1969) and York and Farquhar (1972). York and Farquhar (1972) and York (1970) reviewed recent developments in K-Ar dating that include the K-Ar isochron method. The problem of radiometric dating of porphyry mineral deposits in the Canadian Cordillera involves the dating of events that occurred during Mesozoic and Cenozoic time.  The K-Ar method has been extensively used for  this purpose because: 1)  It is suitable for dating events that occurred during the time span being investigated.  2)  Most porphyry deposits contain mineral or whole-rock samples suitable for K-Ar dating.  3)  The precision and accuracy required is obtained at a reasonable cost.  K-Ar ages obtained for this study are used to extend the study of age of porphyry mineral deposits into northern British Columbia and the Yukon Territory and as a reference for comparing fission-track ages. In this chapter the K-Ar data is presented and examined by using the isochron method and a new Ar^® total vs %K isochron plot is suggested and evaluated.  Application of the Ar ^ rad. vs %K isochron method (section 4  2.3) to published K-Ar data from the Topley Intrusions and Guichon Batholith are presented in Appendix B.  2.2  K-Ar METHOD The K-Ar method of dating depends upon the decay of K^  of which must be measured for an age to be calculated.  to A r ^ , both  Standard analytical  techniques used for measuring potassium and argon have been described i n detail by Hamilton (1965) , Dalrymple and Lanphere (1969) and York and Farquhar (1972). In the .present s.tudy, biotite and hornblende apparent ages were determined in K-Ar laboratories operated jointly by the Departments of Geophysics and Geological Sciences, University of British Columbia, using procedures and equipment previously described (White et a l . , 1967).  In  addition to the normal procedure, the sample and entire fusion system were baked at 130°C for 16 hours which effectively eliminates atmospheric argon contamination in the system (Roddick and Farrar, 1971).  Isotopic ages of  the seventeen analyzed samples are plotted on Figures 4-1 to 4-7 and analytical data given in Table 2-1. Isotopic abundances of potassium and atmospheric argon normally used for K-Ar dating were determined by Neir (1950) and are listed in Table 2-2. The assumptions made in using isotopic values have been reviewed by Dalrymple and Lanphere (1969).  -  9.  TABLE 2-1  Potassium-Argon Analytical Data  (ageg o b t a i n e d f 40  o rt h i s  stU  dy)  A0  40 A6 u rad** A rad. A^rad. K 4 ATTC A total (10-5Cc K ° 5 3 xlO STP/g) xlO"  Ar«° I P *3 xlO  Apparent Age (m.y.)  1.535  26.0+1.0  1.570  10.4016 1.915  26.7+1.2  0.776  1.541  10.3722 1.885  26.2+1.0  0.83 0.757  1.533  9.2347  1.704  0.190  6.943  0.5344  0.6619 115 ±4.0  0.181  7.038  0.2343 0.4590 117 +4.0  6.51*0.02  0.75 1.357  3.081  2.7009  1.111  51.9*2.0  Biotite  7.24±0.03  0.90 1.584  3.232  7.5150 2.711  54.5±2.0  PC9 Lat. 59*20'25" Mt. Eaakln Granite Long. I29°30'22" porphyry porphyry  Biotite  7.51±0.02  0.93  1.508  2.944  11.8377 3.764  49.7±1.5  PC10 Lat. 59*22*42" Mt. Haskin Granite long. 129*30'39" porphyry porphyry  Biotite  7.31*0.01  0.93  1.483  2.996  11.9294 3.853  50.5+1.5  PCU Lat. 59*17*58" Mt. Reed Long. 129*25'18" porphyry  Granite porphyry  Biotite 7.78*0.05  0.84  1.521  2.888  5.0408  1.740  48.7*1.9  PC12 U t . 59*18'00" Mt. Reed Long. 129*25'19" porphyry  Granite porphyry  Biotite  7.75*0.03  0.89  1.491  2.979  8.0373  2.679  50.2+1.6  PC13 U t . 59°12'12" Cassiar Long. 129*50'23" batholith  Qtz. Monzonite  Biotite  6.52*0.01  0.83  1.886  4.274  3.1785 1.644  71.7*2.6  PC14 U t . 59*13'29" Cassiar Long. 129°50'10" batholith  Qtz. Monzonite  Biotite 7.60*0.03  0.85  2.093  4.068  4.1202  1.963  68.3*2.7  PC15 Lat. 59*42'30" Mt. Leonard coarse Long. 133*23'24" Boss Alasklte  Biotite 5.16*0.04 <5Z Chi.)  0.89  1.287  3.685  6.2809  2.597  62.0*2.2  PC16 Lat. 63*58'10" Syenite Long. 137*18'10" RanRe Intrualons  Qtz. Honzonlte  Biotite  0.94  2.391  5.104  8.0164  4.364  85.3*2.7  PC17 U t . 63*57*55"  Qtz. Monzonite  Biotite 7.10*0.03  0.96 2.576  5.361  11.0437 6.183  89.5±2.7  Unit  Rock Type  Mineral  Tertiary plug?  Qtz. latite porphyry  Biotite  7.06±0.05  0.81  0.733  1.534  PC 2 Lat. 61*22'17" Tertiary Long. 139*18'10" plug?  Qtz. latite porphyry  Biotite  6.75*0.05  0.85  0.717  PC3 Lat. 61"22'30" Tertiary Long. 139*25'55" plug?  Qtz. latite porphyry  Biotite  7.44*0.03  0.85  Tertiary plug?  Qtz. latite porphyry  Biotite  7.30+0.03  Kluane PC 5 Lat. 61*22'00" Long. 139*25'09" Range Intrusions  Gabbro  Hbl.  0.404*.001 0.56  PC 6 Lat. 61* 22 '05" Kluane Long. 139*25'09" Range Intrusions  Gabbro  Hbl.  0.379+.002 0.36  PC7 Lat. 61*32*36" Ruby Range Biotite Long. 138*32*38" batholith Granodiorite  Biotite  PC8 U t . 61"32'36" Ruby Range Bio.-Hbl. Long. 138*45'30" batholith Granodiorite  Spec men Ko. PCI  location  U t . 61*22'18" long. 139°18'20"  PC4 U t . 61*22'30" Long. 139°26'08"  *  Syenite Range Intrusions  ZKis*  6.92*0.03  8.1274  26.0*1.0  Potassium analyses by P. Christopher, J.E. Karakal and V. Boblk using KV and KY-3 flame photometers, a-standard deviation of quadruplicate analyses. ** Argon analyses by J.E. Harakal and P. Christopher using MS-10 mass spectrometer. 1 10 Constants used in model age calculations:} e - 0.585 x 10" y" " *.72 x lO-iOy" . *°K/K - 1.1B1 x 10"*.  10.  Table 2-2. Isotopic abundance of potassium and atmospheric argon (Data from Neir, 1950).  Isotope  Relative atomic abundance (per cent)  Ar  4 0  99.600  Ar  3 8  0.063  Ar  3 6  0.337  K  41  6.91 + 0.04  K  40  0.0119 + 0.0001  K  39  93.08 + 0.04  In order to determine the absolute age of a single mineral or rock sample, i t i s necessary to assume that a l l argon in the rock or mineral i s either radiogenic or argon with the present atmospheric ratio (i.e. Ar ^ 4(  total = Ar rad.+ A r 4o  4 0  with Atm. ratio).  Because the A r / A r 4 0  3 6  atmospheric  ratio is 295.5 (Neir, 1950), the conventional method of correcting for 'atmospheric argon' i s to assume that Ar rad.= Ar ^total - 295.5 (Ar ^) . 40  4(  3  However, subsequent workers have shown variation in the i n i t i a l Ar ^/Ar ^ 4(  3  ratio and an alternative graphical approach to determine the i n i t i a l argon ratio has been suggested.  This method i s outlined below.  11.  2.3  GRAPHICAL INTERPRETATION OF K-Ar DATA Investigation of argon content of biotite (Wanless, Stevens and  Loveridge, 1969; G i l e t t i , 1971), hornblende (Roddick and Farrar, 1971), pyroxene (Hart and Dodd, 1962), plagioclase feldspar (Laughlin, 1966; Livingston et a l . , 1967), and nepheline (Macintyre, York and Gittens, 1969) shows that excess i n i t i a l Ar ^ can occur in most datable minerals. 4  Thus samples must be treated in a manner that does not assume that i n i t i a l argon has the present atmospheric ratio i f the K-Ar method is to be of use in establishing trends in age of intrusions and age of mineral deposits. The K-Ar isochron method (York et al. , 1969; McDougall et a l . , 1969; Roddick and Farrar, 1971; Hayatsu and Carmichael, 1970) provides a method of determining the i n i t i a l argon ratio. The data necessary for determining isochron ages i s essentially the same as the data needed for the conventional K-Ar age calculation.  The  isochron method requires that for each rock unit dated at least two and preferably a minimum of three analyses are available from phases or minerals differing by at least 50 per cent in potassium content. In addition to the added analyses required, the entire fusion system must be baked overnight at a temperature that w i l l remove loosely held atmospheric argon, but w i l l not  cause loss of i n i t i a l or radiogenic argon. The temperature required to  clean samples properly has been empirically determined to be 130°C for 16 hours (Roddick, 1970; Roddick and Farrar, 1971). Ar ^/Ar 6 vs K^O/Ar-^ and A r ^ radiogenic vs per cent potassium 4  3  4  diagrams are plotted and the method of least squares (York, 1966) is used to f i t the best straight line to the points.  The lines produced are called  isochrons and the slope of the line i s used to calculate an isochron age.  12.  The ( A r / A r ) vs ( K / A r ) isochron equation i s : 40  (Ar ) = Ar T  36  40  X e Xg+ Xe  40  J b  36  . (e  -1) K Ar  X t  +  4Q  (Ar ) Ar36 i 40  J b  (2.1)  Where (Ar ) Ar^b T  =  the total A r to total A r in the mineral at present.  (Ar ) Ar^6 i  =  the i n i t i a l value of the ratio at t=0.  ( K ) Ar  = present-day ratio of K mineral  40  40  40  J b  X =  4 0  40  3 6  ratio found  to A r  3 6  in the  Ae + Xg  Xe = decay constant for electron capture by K (0.585 x 1 0 - y r ) . 40  Xg =  10  _1  decay constant for beta emission by K ° (4.72 x 1 0 - y r ) . 4  10  _1  For equation 2.1 to be applicable to a set of samples, the samples must have:  1) the same age, 2) the same i n i t i a l argon ratio and 3) essentially  no atmospheric argon contamination. The A r  4 0  rad. vs %K isochron equation i s :  A r r a d . = 6.835 x I O 40  -4  m (%K) + A r i (I - 295.5) (2.2) 3 6  Where A r r a d . = radiogenic argon 40 expressed in cc/gm 40  at S.T.P. and calculated assuming (Ar °i + A r 0 4  m =  X e  4  .)/(Ar 6 3  Atm  i  + A r  3  ^ ) = 295.5  (e * t-1)  slope = 6.835 x 10" m, (Roddick, 1970, p. 59) 4  I = initial Ar /Ar 4 o  3 6  ratio, and  A r ^ ; Ar ^^ = i n i t i a l concentration. 3b  4  For equation 2.2 to be applicable to a set of samples, the following criteria  13.  must apply: 1) samples have the same age, 2) samples have the same i n i t i a l argon ratio, and 3) samples have the same amount of i n i t i a l argon. An exception to criterion three occurs when the i n i t i a l argon ratio i s 295.5. 4  Roddick and Farrar (1971) refer to the Ar ^rad. vs %K diagram as an i n i t i a l argon diagram and Roddick (1970) suggested that: "Minerals having different crystal structures w i l l probably incorporate different amounts of i n i t i a l argon. Therefore, only the same type of minerals can be plotted on an i n i t i a l argon diagram". 40  4v  40  3b  Because Ar rad. is calculated assuming (Ar \ + Ar Atm.)/(Ar ^ + Ar36  40  36  Atm.) = 295.5, the y-intercept of the Ar rad. vs %K diagram is A r ^ 40  (I - 295.5) (Roddick and Farrar, 1971) and not i n i t i a l Ar rad. as the A r rad. vs %K plot seems to suggest. A positive intercept occurs on the A r  40  40  axis when I>295.5 and a negative intercept occurs when I<295.5. 40  Roddick and Farrar (1971) suggest that unlike the A r / A r 3  Ar ^  36  40  vs K /  4  isochron, the Ar ^ rad. vs %K isochron yields the correct age of the  mineral when atmospheric argon i s present in the system. However, the presence of atmospheric argon in the system eliminated any possibility of obtaining quantitative information on the i n i t i a l argon ratio and the i n i t i a l concentration of argon in the sample. The assumptions necessary for a complete K-Ar isochron determination 40  (both A r / A r 1)  36  40  vs K /Ar  36  and A r  40  rad. vs ZK) are:  the baking procedure essentially eliminates atmospheric argon from the system, and  2)  the absolute amount of A r  40  40  i = initial Ar /Ar  36  ratio and age of the samples are the same. 4  If these assumptions hold, then an Ar ^ total vs %K plot w i l l be a valid  14.  .isochron plot. The A r Ar  4 0  4 0  total vs %K isochron equation i s :  total = 6.835 x 10~  4  m (%K) + A r i  (2.3)  4 0  Where Ar " total = total A r 4u  4 0  measured by mass spectrometry,  slope = 6.835 x IO" m 4  Ar *-^ = i n i t i a l A r 4  4 0  in sample at t=0 = intercept on y axis.  The y-intercept for this diagram yields the absolute amount of i n i t i a l Ar ^. 4  2.4  APPLICATION OF ISOCHRON METHOD Ages shown in table 2-1 were calculated assuming that A r  = Ar  4 0  radiogenic + A r  4 0  with atmospheric ratio.  4 0  total  Four samples from quartz  latite porphyry near Burwash Creek (PCI to PC4) and four samples from granite porphyry on the Mt. Reed and Mt. Haskin properties provided independent checks on the age of these units.  Isochron plots were  constructed for these samples to check the i n i t i a l A r / A r ^ ratio and to 40  3  compare isochron results with conventional determinations obtained using the assumed 295.5 i n i t i a l argon ratio. Isochron ages for these units have large uncertainties due to the small spread in potassium content of analyzed biotite concentrates. Isochron ages shown for samples PCI to PC4 in Figure 2-1 and PC9 to PC13 in Figure 2-2 show much greater uncertainty than the respective mean ages of 26.2 + 0.3 m.y.  and 49.8 + 0.7 m.y.  for the samples.  I n i t i a l argon ratios  obtained for these samples both overlap the 295.5 value within the limits of error and therefore, the isochron result is consistent with the use of the 295.5 value.  15.  Regression Results  i  0  1  ',.  i  0.4 ^0  K  0  Fig. 2-i  0  2  i  1  /Ar  36  x  0.8 6  i  i  1.2  1 0  k  6  Isochron plots for quartz l a t i t e porphyry near Burwash Creek, Yukon Territory.  8  Fig.  2-2  Isochron plots for Mt. Reed and Mt. Haskin porphyries.  17.  2.4.1  Ar  4 0  total vs %K Isochrons  40 The Ar total vs %K isochron approach was checked by using published data from Hayatsu and Carmichael (1970) and Roddick and Farrar (1971) that 40 was unsuitable for Ar Case I  rad. vs %K plots.  Cape Breton Whole-Rock Samples  A recalculated isochron for whole-rock K-Ar data obtained by Hayatsu and Carmichael (1970) i s compared with a plot of total A r  4 0  vs %K.  Argon  measurements have been converted from moles/gm. to CC.STP/gm. in order to allow comparison.  Data is presented in Table 2-3 and the isochron plots  are shown in Figure 2-3.  Discordant whole-rock K-Ar data yielded a  40 concordant Ar rad. vs %K isochron age of 391 + 5 m.y. for samples from Cape Breton Island, Nova Scotia (see Hayatsu and Carmichael, 1970) 40 with a positive intercept on the Y axis that indicated an i n i t i a l Ar / Ar ^ ratio greater than 295.5. An A r total vs %K plot yields an isochron 40 parallel to the Ar corrected vs %K plot and an isochron age of 391 + 7 m.y. 40 40 The total Ar plot also has a positive intercept on the Ar axis and this 3  4 0  value is the absolute amount of i n i t i a l A r  4 0  plus a small increment of atmos-  40 pheric Ar (less than 10%). 40 This example shows that an Ar total vs. %K isochron can correct for discordant whole-rock K-Ar data and provides a one step method of obtaining 40 the i n i t i a l Ar Case II  content of a set of samples.  Tulameen Complex Hornblende Samples  A recalculated isochron for hornblende K-Ar data obtained by Roddick and Farrar (1971) i s compared with a plot of total A r . 40  Data is  presented in Table 2-4 and the isochron plots are shown in Figure 2-4. Discordant hornblende K-Ar data yields a concordant A r  4 0  rad. vs %K isochron  18.  TABLE 2-3  Analytlc.nl data and ages of Cape Breton whole rook samples (data from Hayatsu Carmlohael, 1970). Units for Ar^° were converted from raoles/gm to oo. STP/gm. 4o  K (*)  36  +  Age ( x l 0 ° 00. (m.y.) STP/gm.)  A r -total" 6 (xlO 00. STP/gm.)  Ar"* (xl0 3 moles/gm.)  0.066  3.611  2.39  2.148  680  Basalt  0.363  9.677  2.72  8.019  485  Red felslte  0.777  16.442  3.54  14.246  412 411  Sample No.  Book Type  CB-18  Basalt  17 12  -1  -  9  Crystal l l t h l o tuff  0.931  19.219  3.54  17.024  8  Greywacke  1.52  28.582  1.49  27.686  409  7  Red f e l s l t e (quartz keratophyre7)  0.040  3.237  2.30  1.830  691  IA  Greymoke  1.64  30.598  2.05  29.322  402  IB  Greywacke  1.57  29.277  2.08  28.000  401  Amygdaloidal basalt  0.098  4.771  2.47  3.024  644  2  3  Basalt  0.270  6.406  1.38  5.555  456  it  Basalt  0.261  6.406  1.43  5.533  455  5  Bed f e l s l t e  0.595  14.381  3.22  12.365  460  f 4 0 A r spike.  ••3^Ar spike subtracted. Uo  •Values of constants used are Xo= O.566, K/& •= 1.18 x 10"*(4).  TABLE 2-4  Sample Bo.  Analytical data and ages of hornblende from Tulameen Complex (data from0 Roddick and Farrar, 197D. Ar^° total was calculated using the values for Ax* rad. and percent atmospheric argon reported by Roddick and Farrar,  K  *°Ar total" (xl0~° c c . STP/gm.)  W  % Atmoa.  ^ r a- 6 d ( x l O CO. STP/gm.)  (^0Ar/36Ar)T  Age and Error (m.y.)  2H-2  I.63  13.55  13.14  3.0  9803  2H-3 5H-3  1.63  13.61  13.15  3 . 5  8330  191.6 ± 2 . 9  1.19  9.16  9.86  3 . 4  8631  196.6 ± 3.0  5 H - 4  1.19  10.22  9.99  3.8  7682  199.1  8H-2  1.016  10.37  8.731  4.8  6152  203.5 ± 3 . 1  Xe-  10  1  0.584 x IO' .*!-- !  - 4.72 x 1 0  - 1 0  yr 36  -1  4  4  t °K = 1.22 x IO" g/g K.  * Calculated assuming ( ^ A r j + **°Ar.) / ( A r j +  36  Ar.) - 295.5.  191.5  ±2.9  ±3.0  19.  32  Regression  Results  Intercept 2.742±0.4623  Slope 17.18±0.3528 Total  1.246*0.2634  17.21+0.2012  Corrected  38  24  -I & 20  CO  16  o VO  I  12  O  *.Total • Corrected  0.2  Fig. 2-3  OA  Cv6  CX8  1.0  1.2  M  1.6  T o t a l a n d c o r r e c t e d A r 4 0 v s %K i s o c h r o n s f o r w h o l e - r o c k K - A r data. C o r r e c t e d I s o c h r o n i s r e c a l c u l a t e d from H a y a t s u and C a r m i c h a e l ' s (1970) d a t a .  zo.  Regression  Results  Intercept 1.645 ± 0.3846  Slope 7.31 + 0.166 Total  1.331 +0 2556  7 24± 0.110  Corrected  Total Corrected  02  Fig. 2-4  0/  06  0.8  1.0  12  14  HU Comparison of A r 4 0 total isochron with Ar-40 corrected isochron diagram for K-Ar hornblende data from the Tulameen Complex, British Columbia (data from Roddick and Farrar, 1 9 7 1 ) .  —i 16  21.  age of 175 + 3 m.y.  for samples from the Tulameen Complex, British Columbia  (see Roddick and Farrar, 1971) and an A r isochron parallel to the A r + 4 m.y.  4 0  total vs %K plot yields an  rad. vs %K plot and an isochron age of 176  The y-intercept for the A r  amount of i n i t i a l A r  4 0  4 0  total isochron is the absolute  plus a small increment of atmospheric  4 0  Ar . 40  This example suggests that the total argon plot yields essentially the same results as the A r initial Ar yield A r  4 0  4 0 i  4 0  rad. vs %K plot, and that the absolute amount of  i s obtained directly by using the A r values of 1.6 x IO  samples, but the A r  4 0  -6  4 0  approach. Both plots  CC.STP/gm. for the Tulameen hornblende  total vs %K plot does not require the plotting of  an A r / A r ^ vs K^/Ar ^ isochron in order to obtain the A r ^ value. 40  2.5  3  3  4  SUMMARY Hayatsu and Carmichael (1970) and Roddick and Farrar (1971) have 40  shown that the K-Ar isochron method corrects for excess i n i t i a l Ar a mineral sample.  in  Since the isochron method can yield more meaningful  ages, an attempt should be made to apply the method to K-Ar data. At least three samples from a single igneous event are necessary in order to establish an isochron.  Samples PCI to PC4 and PC9 to PC13 were  analyzed in a manner suitable for isochron determinations (Roddick and Farrar, 1971), but the narrow range of potassium values for the samples leads to isochron ages with large uncertainties (Figure 2-1 and 2-2). Isochron plots of A r  4 0  total vs %K yield the same age as A r  %K plots, and in addition, the A r  4 0  rad. vs  total vs %K plot provides a one step  approach to obtaining the absolute value of i n i t i a l A r 2-4) .  4 0  4 0  (Figures 2-3 and  22.  2.6  EVALUATION OF ISOCHRON METHOD The graphical approach to potassium-argon age dating provides a  new approach to data treatment and interpretation.  Advantages of the  graphical approach are: 1)  In order to obtain meaningful ages for minerals of low K content and (or) young age, the i n i t i a l argon ratio of the minerals must be determined.  In theory, the Ar^/Ar *^ vs 3  K /Ar 6 plot w i l l yield the i n i t i a l argon ratio of properly 4o  3  treated samples of related age and history. 2)  Isochron plots are useful visual and interpretative aids, these diagrams emphasize irregularities and trends in K-Ar data.  3) As information on i n i t i a l argon accumulates, i t w i l l add to our  understanding of the argon retentivity of various minerals  and the origin of excess argon (Hayatsu and Carmichael 1970). 4)  Provides a method of correcting for high i n i t i a l argon ratios (e.g.  Hayatsu and Carmichael, 1970 and Roddick and Farrar, 1971).  Disadvantages of the graphical approach are: 1)  Several samples must be analyzed in order to determine the i n i t i a l argon ratio.  2)  Mineral samples that are from the same intrusive phase often contain similar potassium content and therefore are not suitable for isochron plots,  ( e.g Samples PCI to PC4 and samples PC9  to PC13 section 2.4) . r  3)  For an A r  4 0  vs %K plot to apply, samples must contain the same  amount of excess argon.  It is unlikely that this assumption w i l l  generally hold for more than one mineral phase.  23.  3. 3.1  FISSION TRACK DATING  INTRODUCTION Recent work has established the feasibility of using the fission-  track technique for dating common accessory minerals (Fleischer and Price, 1964a; Naeser, 1967b; Wagner, 1968; Christopher, 1969; Naeser and Dodge, 1969; Naeser and McK.ee, 1970); however, most of the studies to date have been carried out on samples that are from unaltered rocks that yield clean concentrates of datable major and accessory minerals.  These studies  have shown that the fission-track method can be used as a dating tool and does provide information on the age and crystallization history of a mineral or rock unit. The Canadian Cordillera has been established as a porphyry copper and molybdenum mineral province (Sutherland Brown et a l . , 1971; Sutherland Brown, 1969a) with low grade (porphyry type) mineral deposits of the 'paramagmatic class' (White, Harakal and Carter, 1968).  Most examples of  porphyry copper deposits exhibit a characteristic sulfide and alteration zoning that was formed in an epizonal to mesozonal environment during Mesozoic and Cenozoic times (Lowell and Guilbert, 1970; Rose, 1970). Naeser (1967a) concluded that: "...apatite, because of i t s property of low temperature track annealing i s a very sensitive temperature monitor.  It  is most useful in looking at events in the Mesozoic and Cenozoic, where effects of burial are minimal".  Porphyry deposits of the Canadian Cordillera  should provide an ideal setting for fission track age determinations on apatite. In this chapter the fission-track method is reviewed, and the application of apatite fission-track dating to the study of porphyry mineral  24.  deposits i s evaluated by comparing apatite fission-track and K-Ar ages for co-genetic minerals. 3.2  FISSION-TRACK METHOD Following the discovery by K.A. Petrzhak and G.N. Flervo in the  U.S.S.R. in 1940 that uranium undergoes spontaneous fission, many scientists looked for tracks of radiation damage recorded in crystal structures.  Fission-tracks were f i r s t detected in irradiated flakes of  the mineral muscovite by Silk and Barnes (1959). The most direct method for observing tracks i s to examine irradiated solids with an electron microscope at high magnification (50,000x). This method of observing fission-tracks limited their u t i l i t y until the discovery of chemical etching techniques by P.B. Price and R.W. Walker (1962) permitted the study of fission-tracks with the optical microscope. The discovery of etch techniques for revealing fission-tracks was followed by the development of the fission-track technique for dating minerals and glass (Price and Walker, 1963, p. 4847; Fleischer and Price, 1964a, p. 331 and 1964d. p. 1705). produced by the fission decay "of U  Spontaneous fission-tracks can be 238  , U  2 3 5  , and T h  2 3 2  , but Price and  Walker (1963) calculated that in most cases spontaneous fission of U  2 3 8  is the only likely source of fission-tracks.  Therefore, the parent  material for the fission-track method i s U  and the daughter products of  a spontaneous decay are represented by a damaged t r a i l (fission-track). The increase i n the spontaneous fission-track density i s a measure of the build-up of the daughter products and the spontaneous fission-track density is directly related to the age and U  2 3 8  content of a mineral  or material.  25.  The fission-track method has been applied to the dating of metamorphic and igneous events ranging in age from historic times to the Precambrian. Minerals suitable for fission-track dating include: biotite, hornblende, apatite, zircon, muscovite (Fleischer and Price, 1964b) , sphene (Naeser, 1967b) and epidote (Naeser, Engels, and Dodge, 1970).  Glass ( B r i l l et a l . ,  1964; Fleischer and Price, 1964a and b) can also be dated and most plastics are excellent track detectors. 3.2.1  Procedure  The procedure for determining fission-track ages involves: a)  determining the spontaneous fission-track density on an etched interior surface of a mineral.  b)  using the calculated value for spontaneous fission decay constant ( X F),  c)  TOO  determining the U  content.  An accurate, indirect determination of the U^-^ content can be made by exposing an annealed portion of the sample to a known dose of thermal neutrons (Fleischer et a l . , 1964).  Thermal neutron induced fission takes  place i n IT*^-*, b t not i n U^-^, and therefore, the induced track density u  ( p i ) w i l l be a function of the thermal neutron flux, the cross section capture area of U^35 f  o  r  thermal neutrons, and the concentration of 11^35.  Once the values necessary for determination of the U"235 content are obtained, the U^38 content can be found by using the constant isotope ratio (U235/ ij238  _ 1/137.7). From an induced track count, a spontaneous track count,  and a flux determination, the age of a.mineral can be obtained from the following equation (Fleischer et a l . , 1965a, p. 389):  26.  A =  1  In [1 + ( ps X Da Id))] pi A F  * D Where A = age in years;  ps = spontaneous track density (natural tracks from spontaneous decay of U  2 3 8  );  p i = induced track density (tracks caused by neutron induced fission of U ^); 23  AD = total decay constant for U  (1.54 x l C T ^ y r " ) ;  2 3 8  1  a = thermal neutron cross section for fission of U ^ (582 x I O 23  - 2 4  cm ) ; 2  4> = total thermal neutron dose (nvt) ; I = 1/137.7 = isotope ration U  2 3 5  AF = fission decay constant for U  /U  2 3 8  2 3 8  (7.26 x I O ) ; -3  (6.85 x 1 0  _ 1 7  yr ) _ 1  (Fleischer and Price, 1964a, p. 63). By substituting values for the constants, the equation reduces to (Naeser, 1967b, p. 1523): A = 6.49 x 10  In [1 + (9.45 x 10"  18  p_s ) ] yr. pi  The various steps involved in a fission-track age determination are outlined i n detail in Appendix C. The reader i s referred to descriptions of the analytical procedure presented by Lahoud et a l . (1966), Naeser (1967a and b) and Christopher (1969).  27.  3.2.2  Flux Determination  The largest analytical uncertainty in determining a fission-track age generally involves the determination of the neutron flux obtained during sample irradiation.  The reactor irradiation is used for  determining uranium content of samples and a neutron flux in the order of 10"^ to  nvt* i s required for the uranium determination.  The most  accurate method for determining the flux obtained during a reactor run i s to include a calibrated standard with either a known uranium content or known fission-track age and count fission-tracks produced in the standard. A glass standard calibrated by Dr. C.W. Naeser of the United States Geological Survey to contain 0.4 ppm uranium was included i n the reactor run along with standard apatite Me/G-1 that has concordant 120 m.y. biotite potassium-argon  and 119 m.y. apatite fission-track ages.  Three independent checks were used to determine the flux obtained: 1) a flux of 1.31 x lO-L^ nvt was determined for the standard glass; 2) a flux of 1.31 x 10^ nvt was obtained by comparing track density produced i n the U.B.C. reactor run with the track density of the same standard glass included in the Dartmouth reactor run 1 (Christopher 1968 and 1969); and 3) a flux of 1.30 x 10 ^  nvt was calibrated by using 120 m.y. as  the age of standard apatite Me/G-1. Although the standard deviation of three independent checks of the flux is less than one per cent, an error of 5% was assigned to the 1.31 x 1 0 n v t flux because of uncertainty in the track density produced i n the standard.  * nvt = total thermal neutron dose.  28.  3.3  EVALUATION OF THE FISSION TRACK METHOD Several assumptions must be made in calculation of fission-track  ages, many of which cannot be assigned an absolute error.  Possible  sources of error in each fission-track age include determination of (1) fossil track density, ( ps), (2) induced track density ( p i ) , and (3) neutron dose ( t t ) .  In addition, incomplete knowledge of the physical  and geochemical properties of uranium may also be a source of error. The ability to distinguish tracks from inclusions, dislocations, and other imperfections in crystals has been discussed by Fleischer and Price (1964 d).  The five characteristics used in identification of  fission-tracks are: 1) they form line defects, 2) they are straight, 3) they are randomly oriented, 4) they are of limited length (typically of the order of 5 to 20 microns or 5 to 20 x 1 0  -3  mm), and 5) they can be  caused to disappear by suitable heating (Fleischer and Price, 1964 d; Wagner, 1968; Naeser and Faul, 1969).  The spontaneous and induced track  counts are substituted in the dating equation as a ratio, and therefore, consistent application of the above 5 criteria in the counting of both the natural and induced tracks w i l l help eliminate counting error. In natural mineral samples, the uranium isotope U element for which spontaneous fission i s significant. of U ^ and T h 23  2 3 2  2 3 8  is the only  Spontaneous fission  also occur, but U ^ would account for less than 0.5 23  per cent of the spontaneous fission tracks in a mineral and Th  would  make a 50 per cent contribution only i n a substance in which i t was approximately 100',000 time more abundant than uranium (Faul, 1966).  Cosmic-ray  interaction could produce radiation damage similar to fission-tracks, but the effect of the cosmic ray flux on buried terrestrial samples is considered to be negligible because of strong attenuation by rock or s o i l  29.  (Price and Walker,  1963).  Uranium in nature is predominately composed of two radioactive 235  238  isotopes U  and U  . These two isotopes have always been found  to occur together in nature with the phases intimately mixed and in a 235  fixed proportion (U 235  U 10  8  238  /U  =  1/137.7  +  0.3)  (Senftle et a l . ,  1957).  238  and U yrs. and  also decay by alpha emission with half lives of 7 . 1 3 x 9 4.51 x 10 yrs. respectively. Price and Walker ( 1 9 6 3 )  calculated that the effect of parent reduction because of alpha decay is 9  significant when the time involved is greater than approximately 1 0 yrs. 238  The value of the fission decay constant for U  directly controls  the accuracy of ages calculated by the fission-track method (Price and Walker, 1 9 6 3 ) . Fleischer and Price ( 1 9 6 4 a and c) determined a weighted -17  average value of 6.85 + 0 . 2 0 x 1 0  yr  -1  for the decay constant for  238  spontaneous fission of U  ( ?F).  This average value was obtained by  using two track counting methods that gave concordant results.  The  first  value, / I F = 6 . 9 x 1 0 ~^yr \ was obtained by requiring that ages of a large number of minerals determined by using the fission-track method agree with ages determined by decay of 7lF = 6 . 6 + 0 . 8  x 10  yr  and Rb^.  The second value,  , was determined by counting fission-tracks  recorded in mica SSTR held against a sheet of uranium f o i l for six months. Fleischer and Price's weighted average value for /IF = 6 . 8 5 + 0..20 x 1 0 yr ^ is supported by a value of  /IF  =  7 . 0 3 + 0 . 1 1  x  10  "^yr  ^ (Roberts et a l . ,  1 9 6 8 ) determined using standard mica SSTR against uranium f o i l , and a value of 6 . 8 + 0 . 6 x 1 0 "^yr ^ (Kleeman and Lovering, 1 9 7 1 ) determined by accumulating fission fragment tracks in Lexan plastic held adjacent to  30.  uranium metal for one year.  Values for A-p ranging from 8.27 to 8.42  x l O ' - ^ y r have been determined by Spadavecchia and Hahn (1967) and -1  Galliker et a l . (1970), using a 'spinner' apparatus.  The larger values  are not commonly used for fission-track dating and the weighted value of Ap = 6.85 +0.20 x 1 0 " y r 17  average  (Fleischer and Price, 1964 a and  -1  c) was used in this study. A closed system for uranium i s assumed. This assumption can be checked by careful observation of the position of natural and induced tracks in a substance.  Irregularities in the uranium distribution are  also detectable during fission-track counting.  If extreme irregularities  are found (e.g. sphene sample JH5 from Brenda Mine), the sample cannot be age dated by random counting methods. The accuracy of the flux determination has been discussed by Fleischer, Price and Walker (1964).  A value of 1.31 + 0.07 x 10^  n  v  t was  determined for the reactor run used for irradiating samples studied by the writer.  Fleischer, Price and Walker (1964) showed that flux variation over  a 5 cm length is about 10% and they estimated that the total error in the flux determination i s about 15%.  Samples used in this study were irradiated  over a tube length of less than 2 centimeters and therefore flux variation should be about 3%.  Error in the flux determination i s caused by  uncertainty in the uranium content of the standard, variation of the flux within the reactor, counting error, and uncertainty in constants assigned to isotope ratios and capture cross sections. Naeser (1967b) suggested that the number of tracks counted provided the major source of error in a fission-track age determination.  If a  minimum of 400 fossil and induced tracks are counted, the error for each  31.  slide i s + 5%, a value obtained by assuming a Poisson distribution, (i.e. the standard deviation of the track counts i s the square root of the number of tracks counted). Empirically, Naeser and Dodge (1969) determined that + 10 per cent is a good estimate of the standard deviation of a fission-track age, assuming at least 250 counts of both fossil and induced tracks.  For this  study an error of + 10 per cent i s considered to be a good estimate of the standard deviation of a fission-track age when at least 400 counts of both fossil and induced tracks are obtained.  When total counts are less  than 400, the standard deviation was calculated by taking the square root of the sum of the squares of the estimated error (10%) and the standard deviations of counting error for natural and induced tracks.  32.  3.4  PRESENTATION OF DATA Analytical data and the calculated fission-track ages measured on  fifteen apatite concentrates from five localities (Figure 1-1) in the Canadian Cordillera are shown in Table 3-1.  Analytical data for standard  apatite samples Me/G-1 and Me/N-1 are also presented (see Christopher 1968 and 1969). K-Ar ages obtained at the University of British Columbia on co-genetic biotite are shown for comparison.  The biotite K-Ar ages are  believed to represent the time at which the rock cooled to a temperature at which biotite retains argon (about 150°C) , and for high-level epizonal and mesozonal igneous bodies, the time of emplacement and time of setting of the biotite K-Ar clock should be relatively close. Seven sphene and two zircon samples were also prepared for fissiontrack dating but etched grain mounts revealed extreme irregularities in uranium content, and the sphene and zircon samples could not be dated by using random track counting methods.  An alternate procedure for dating  minerals with non-uniform uranium content has been described by Naeser (1967 a and b), but samples were not irradiated in a manner suitable for treating samples with non-uniform uranium content.  TABLE 3-1 Sample No.  15  FISSION TRACK ANALYTICAL DATA AND AGES (thermal neutron flux - 1.31 X IO )  Unit  Minerals Tracks Traok Tracks Track Uranium Etch Fission Dated Counted Density Counted Density Content Time Traok Sts f\ In ppm (seo.) Age (counts/cm') (counts/cm') (m.y.) 5 xl05 xlO  K-Ar Age (m.y.)  BURWASH LANDING AREA PCI  Tertiary plug?  Apatite Biotite  PC2  Tertiary plug?  Apatite Apatite Biotite  PC3  Tertiary plug?  Apatite Biotite  PC8  Ruby Range batholith  Apatite Biotite  86  1.08  296  2.04  5.6  15  42±7  1.53  466  0.91  301  2.27 2.10  6.3 5.8  10 15  5^±6 " 35±5  419  2.03  428  3.48  9.6  10  47±5  170  1.94  411  3.17  8.7  10  49+7  310 336  4.28 3.89  11.8 10.7  15 12  48±6 60±8  593  4.04  11.1  13  54±7  1094  5.87  16.2  10  6?±7 -  734  4.85  13.4  10  6o±6' '••  22.5  10  '.76±8..  17.9  15  121±l6  26.Oil.0  26.7±1.2 26.2±1.0 5^.5+2.0  CASSIAR AREA PC9  Bt. Haskin porphyry  Apatite Apatite Biotite  416  316  2.58 2.92  PC12  Kt. Reed porphyry  Apatite Biotite  144  2.71  PC13  Cassiar Intrusions  Apatite Biotite  880  4.90  PC14  Cassiar Intrusions  Apatite Biotite  660  3.59  49.7+1.5 50.2+1.6 ?1.7±2.6 68.3±2.7  SYENITE RANGE PC16  PCI?  Syenite .. Range Intrusions  Apatite Biotite  702  Syenite Range Intrusions  Apatite Biotite  187  7.74  934  8.18  9.92  468  6.48  85.3±2.7  89.5+2.7  COPPER MOUNTAIN AREA KA1  Lost Horse intrusion  Apatite Biotite  616  9.17  472  6.25  17.2  10  117±12  XA4  Verde Creek Apatite qtz. monz. Biotite  571  7.50  52  4.64  12.8  10  129+23  KA9  Lost Horse (dike)  Apatite Biotite  326  3.27  428  2.67  7.4  12  101±12  KA10  Lost Horse intrusion  Apatite Apatite Biotite  381 292  5.02 6.02  271 151  3.97 3.77  10.9 10.4  10 15  101±13 127±18  194+8 101±4 197±8  195+8  GRAN ISLE MINE HC-69-8apatlte bearing vein  Apatite Biotite  231  3.09  191  6.39  23.1  10  13.6 15.1 17.7  10 10 13-15  30±4 '.  50.2±2.1  STANDARD APATITE Ke/G-1  Ke/N-1  * **  Apatite 859 Apatite* 1120 Apatite* 2087 Biotite Apatite** Apatite Apatite• ApaKlte* Apatite* Apatite**  7.46  9.12 9.61  •558-.  879  816  1588  4.95 6.4o 7.52  120+.12 133+20 119±18 113  761 " " 6.38  504 •  606  5*45 -7.27' 5.58  456 434 579 588  3.34' 3.79 5.71' 3.89  9.2 10.4 13.4 9.6  10" 15 - '1-5 15  152±15 115112 119±18 , 134±13 101  Ages determined by the writer at Dartmouth College (Christopher 1968 and I 9 6 9 ) . Ages determined at Dartmouth College (personal communication J.B. Lyons 1971).  120  34.  .3.5  DISCUSSION OF FISSION TRACK RESULTS Figure 3-1 is a graphical comparison of the results obtained for  biotite K-Ar and apatite fission-track methods.  It demonstrates that  fission-track ages for apatite from the Burwash Landing area, Cassiar area and Syenite Range are consistent and i n general concordant with K-Ar ages determined on co-genetic biotite; and that one sample from a mineralized potassic-zone vein at the Granisle Mine and four samples from the Copper Mountain area show discordant results. Thin section investigation revealed that co-genetic  minerals  obtained from weakly altered (potassic zone) rocks give concordant results and that discordant results are obtained from strongly altered propylitic and potassic zone rocks.  Alteration of apatite makes track distinguishing  more d i f f i c u l t , thus eliminating the possibility of using several of the apatite concentrates prepared for this study from the Copper Mountain intrusions. Thermal events have been suggested by Naeser (1967a), Naeser and McKee (1970), and Wagner and Reimer (1972) to explain apatite fissiontrack ages that are younger than the biotite K-Ar age for the sample. Annealing studies on apatite by Naeser (1967a), Naeser and Faul (1969) and Wagner (1968) show that fission-tracks i n apatite are very sensitive to thermal events, and that a temperature of less than 75°C i s necessary for complete track retention.  Concordant apatite fission-track and  biotite K-Ar ages suggest that the rock unit cooled from greater than 150°C (Damon 1968) to less than 75°C (Naeser and Faul 1969; Wagner, 1968) within a length of time less than the experimental error of the techniques. apatite fission-track age younger than a biotite K-Ar age for a unit  An  35.  Fig. 3-1  Graphical comparison of apatite fission-track and biotite pottasiumargon apparent ages. Potassium-argon ages determined at the University of British Columbia have been shown to be accurate within 3 per cent (J. Harakal personal communication).  36.  indicates that either slow cooling or mild reheating in the temperature range 150°C to 75°C annealed fission-tracks from apatite while argon was being retained by biotite.  If apatite fission track ages are older than  K-Ar ages on co-genetic biotite, the discrepancy is d i f f i c u l t to explain. A mean apatite fission-track age of 111 + 7 m.y. from samples KA1, KA9, and KA10 from the Copper Mountain intrusions i s considerably younger than the mean biotite K-Ar age of 195 + 2 m.y. for the samples. The consistently low ages obtained for apatite from the Copper Mountain intrusions suggest a thermal event that was strong enough to reset the apatite fission-track clocks but not the biotite K-Ar clocks.  A temperatur  between 150°C and 75°C associated with a Cretaceous thermal event would account for the difference in apparent apatite fission-track and biotite K-Ar ages. Concordance of apatite fission-track and biotite or hornblende K-Ar ages increases the r e l i a b i l i t y of an absolute age determination. Samples from the Cassiar area, Syenite Range, and Burwash Landing area generally have concordant biotite K-Ar and apatite fission-track ages.  These  findings suggest that the apatite fission-track method is a suitable absolut age dating method for late Mesozoic and Cenozoic igneous events i n the Cassiar area, Burwash Landing area and Syenite Range.  37.  3.6  COMPARISON OF K-Ar AND FISSION-TRACK DATING TECHNIQUES Apatite fission-track ages of samples dated in this study are both  concordant and discordant with K-Ar dates on co-genetic biotite or hornblende from the same sample.  Young apatite fission-track ages have  been attributed to the sensitive annealing character of fission-tracks in apatite (Naeser, 1967 a and b; Wagner, 1968; Christopher, 1969; Engels and Crowder, 1971).  Apatite maintained at a temperature in excess  of 50°C for a million years w i l l lose 10 per cent of i t s tracks, and i f the temperature is maintained in excess of 175°C, a l l accumulated fissiontracks w i l l be annealed (Naeser and Faul, 1969) . Each mineral suitable for fission-track dating has a different temperature range for track annealing (Fleischer et a l . , 1965b; Naeser and Faul, 1969; Wagner, 1968). studies.  Figure 3-2 is a summary of annealing  In principle, dating a suite of minerals from the same site  allows a thermal history to be constructed (e.g. Naeser, 1967 a and b; Engels and Crowder, 1971). Lowering of K-Ar ages can also be caused by heating, but for biotite and hornblende, the loss of argon does not begin until a temperature of approximately 150°C i s reached (Damon, 1968).  Hornblende is more resistant  to argon loss than biotite, but for either mineral, essentially a l l argon w i l l be retained when fission-tracks are being annealed from apatite at temperatures between 75 and 175°C.  K-Ar ages, obtained in conjunction with  apatite or other fission-track ages, help resolve the thermal history of an area. The simplicity of the apatite fission-track method i s an appealing  38.  T E M P E R A T U R E (°C) 800 700 600  10"  r  -i  10' y n  o • o J *  10' y r i -  in*  400  300  w l T  V  /////••  win/ Win/  io°L  o.i  /  /  /  /  100  1.2  1.4  //  .  /  7^  T  7"  y—7—y  /  y—f  / EXPLANATION Epidott  / '  Sphtnt  -6  Apotitt Circlid points from Wogntr (1968)  •// 1.6  SO  / 7  /  l . t  £.0  TEMPERATURE  Pig. (3-2).  150  /  iv / ^7-  I0 yrt  10*  ZOO  // / / / »'  4 i -  10' yr«-  .-  300  2.2  2.4  2.6  2.S  3.0  3.2  ( - ! f £ S )  Track-loss curves f o r epidote, sphene, and apatite (from Naeser and Dodge, 1969).  39.  feature.  Because normal laboratory equipment is used for fission-  track dating, the experimental costs are minimal.  The main cost of  a fission-track determination involves the thermal neutron irradiation. Neutron irradiation services are commerically available, and by including several samples i n a reactor run, the cost per sample i s less than ten dollars. After obtaining mounted and polished thin sections for normal and irradiated sample portions, the time needed for making a fission-track age determination w i l l depend upon the fission-track density. An apatite fission-track age determination should take between 2 and 6 hours (Naeser and McKee, 1970) i f between 10 and 20 grains are examined. this study, track counting time was between 4 and 8 hours.  For  The time  necessary for a complete K-Ar analysis, including both potassium and argon analysis, i s about 6 to 10 hours.  In addition, the K-Ar analysis  must be spread over several days. Because only a few grains of sample are necessary for a fissiontrack determination, the mineral separation time i s short and mineral concentrates can be obtained as by-products of mica and amphibole mineral separations.  Rocks that are poor in micas and amphiboles are not easily  dated by K-Ar and Rb-Sr methods, but should be datable by the fissiontrack method. For samples with less than 50% atmospheric argon contamination, the precision of replicate K-Ar age determinations in the University of British Columbia K-Ar laboratory i s within 1% and the accuracy within 3% (J.A. Harakal, personal communication, 1972). The amount of analytical  40.  uncertainty is greater for fission-track age determinations.  Empirically,  Naeser and Dodge (1969) have determined that + 10% i s a good estimate of 1 standard deviation in a fission-track age determination.  Accuracy  estimates for fission-track age determination cannot be made because of lack of interlaboratory 3.7  comparison.  SUMMARY AND CONCLUSIONS Fifteen apatite fission-track ages were obtained for apatite  concentrates from six areas in British Columbia and the Yukon Territory. Apatite fission-track ages obtained from epizonal and mesozonal intrusions with porphyry mineral deposit affinity are consistent and generally concordant with biotite K-Ar ages where alteration i s weak. Apatite samples from the Copper Mountain area and from the Granisle Mine were d i f f i c u l t to date using the fission-track method because of the altered nature of the apatite. Three apatite fission-track ages from the Copper Mountain intrusions have a mean age of 111 + 7 m.y.  This mean age is interpreted to reflect  a heating event that is related to Early to Middle Cretaceous granitic intrusion.  Because biotite K-Ar ages in the Copper Mountain area are  affected only by contact thermal events, and apatite fission-track ages appear to be regionally reset, temperatures between the minimum annealing temperature of apatite (approximately 75°C) and the minimum temperature for argon loss from biotite (approximately 150°C) are suggested for a regional thermal event of Cretaceous age.  Without additional geologic and geochronologic evidence, apatite fission-track ages from the Copper Mountain area and the Granisle Mine give misleading results with resulting misinterpretation of thermal history.  Therefore, in cases where alteration i s involved or thermal  events are suspected, apatite fission-track ages should be checked by using another more refractory mineral or another radiometric clock. A comparison of fifteen apatite fission-track ages with K-Ar ages (Figure 3-1) demonstrates that the apatite fission-track method can be used to age date porphyry mineral deposits, however the K-Ar method is generally more suitable in terms of cost and r e l i a b i l i t y .  4.  4.1  AREAS. STUDIED  INTRODUCTION Areas studied are located on Figure 1-1.  This chapter outlines  the geologic setting and age of the areas studied. In addition the K-Ar and fission-track methods are compared for these areas.  4.2  SYENITE RANGE, YUKON TERRITORY 4.2.1  Introduction  Syenite Range i s located about 60 miles southeast of Dawson City, Yukon Territory and 50 miles west-northwest  of Mayo, Yukon Territory  in the Yukon Plateau near the northeast flank of the Tintina Trench. Along the Tintina Trench and near i t s northeast flank are many bodies of course light grey granite commonly containing abundant feldspar phenocrysts (Bostock, 1948).  These granitic bodies have been mapped by  Bostock (1964) as Jurassic and (or) Cretaceous Coast Intrusions.  The  Syenite Range is composed of a composite stock of these coarse-grained granitic and syenitic rocks arranged in concentric zones with an outer zone of porphyritic syenite and a core of porphyritic granite (Bostock, 1948).  4.2.2  General Geology and  Geochronology  Figure 4-1 shows the general geology and geochronology of the Syenite Range.  Granitic rocks that compose the Syenite Range intrude Paleozoic  sedimentary rocks.  Similar granitic rocks of Cretaceous age occur i n the  Mayo Lake, Scougale Creek and McQuesten Lake map areas (Green, 1971).  43.  137°30'  Figure 4-1.  137°15'  General geology and geochronology of the Syenite Range, Yukon Territory (geology after Bostock, 1964).  44. A Cretaceous age f o r g r a n i t i c rocks of the Syenite Range i s supported by f i e l d relationships  and a number of radiometric age determinations.  To  the north and east of the Syenite Range, similar g r a n i t i c rocks intrude the Keno H i l l Quartzite of probable Early Cretaceous age (Green, 1971) and about 50 miles west of the Syenite Range i n the Tintina Trench, s i m i l a r g r a n i t i c debris i s present i n Tertiary conglomerates (Green, 1972).  4.2.3  Radiometric Dating  Table 4-1 summarizes f i s s i o n - t r a c k and K-Ar ages obtained f o r co-genetic b i o t i t e and apatite samples PC16 and PC17.  Both rock  samples contain about 5% .biotite that i s weakly altered along cleavage edges and grain boundaries to c h l o r i t e .  B i o t i t e K-Ar ages of 85.3 +  2.7 m.y. and 89.5 + 2.7 m.y. were obtained for specimens PC16 and PC17 respectively.  These ages are similar to b i o t i t e K-Ar ages of 85 +  7 m.y. (GSC 65-50) from a quartz monzonite stock about 25 miles south of the Syenite Range and 8 1 + 5 m.y. (GSC 65-49) from quartz porphyry i n the Keno H i l l area about 50 miles northeast of the Syenite Range. An apatite f i s s i o n - t r a c k age of 7 6 + 8 m.y. for sample PC16 i s concordant with the 85.3 +2.7 m.y. b i o t i t e K-Ar age f o r the sample. An apatite f i s s i o n - t r a c k age of 121 + 16 m.y. for sample PC17 i s discordant with the 89.5 +2.7 m.y. b i o t i t e K-Ar age f o r the sample.  The large  uncertainty f o r the apatite f i s s i o n - t r a c k age (16 m.y.) i s caused by the small number (187) of spontaneous f i s s i o n - t r a c k s  4.2.4  counted.  Conclusions  The b i o t i t e K-Ar ages (85.3 + 2.7 and 89.5 + 2.7 m.y.) and apatite f i s s i o n - t r a c k ages (76 + 8 and 121 + 16 m.y.) are mainly Late Cretaceous as defined i n Wanless et a l . (1972).  These ages are i n agreement with  45.  others (Gabrielse, 1967, p. 286),obtained from an arc of relatively small granitic intrusions strung out along the northeast side of the Tintina Trench.  Table 4-1 Fission-track and K-Ar ages obtained for granitic rocks in the Syenite Range, Yukon Territory.  Sample Number  Unit  PC16  PC17  Rock Type  Mineral dated  Fissiontrack age* (m.y.)  Syenite Range intrusions  Qtz. monz.  apatite biotite  76 + 8  Syenite Range intrusions  Qtz. monz.  apatite biotite  121 + 16  K-Ar age** (m.y.)  85.3 ±  89.5 ±  2  -  7  2  -  7  * Fission-track analyses by P.A. Christopher. Constants used in model age calculations:X p U = 6.85 x 1 0 " Y r ; \ for U = 1.54 x lO-iOyr ; a for U = 582 x 10 cm^. f o r  2 3 8  17  _1  2 3 8  D  -1  2 3 5  _24  ** Argon analyses by J . E . Harakal and P.A. Christopher using MS-10 mass spectrometer. Constants used in model age calculations:X = 0.585 x 1 0 - y r ; Ag = 4.72 x 1 0 ~ y r ; 40K/K = 1.181 x I O . e  10  4.3  -1  10  -1  -4  CORK (BURWASH CREEK) Cu-Mo PROSPECT 4.3.1 Introduction Eight K-Ar and four apatite fission-track ages were obtained from  granitic and porphyritic textured intrusive rocks in the Burwash Landing area of southwestern Yukon Territory.  Six of the samples were selected  because of their spatial relationship to a porphyry Cu-Mo prospect on Burwash Creek, and two samples were collected to check the age of the Ruby  46.  Range batholith to the east of Burwash Landing. Figures 4-2 and 4-3 show sample locations and outline the geology in the Burwash Landing area.  The Cork property lies in the northern  segment of the Insular tectonic belt (Sutherland Brown et a l . , 1971). The area is part of the St. Elias Fold Belt, and consists of an eugeosynclinal assemblage of sedimentary, volcanic and intrusive rocks with ages ranging from Devonian to Tertiary. High level porphyritic intrusive rocks near Burwash Creek have been mapped as Tertiary age by Muller (1967) on the basis of their chemical and textural similarity to s i l l s , dikes, and small stocks that cut Tertiary sediments in the St. Elias Fold Belt.  The Cork Cu-Mo prospect occurs in  and around a body of quartz latite porphyry that intrudes sedimentary and volcanic rocks of late Paleozoic (Cache Creek Group) and early Mesozoic age (Mush Lake Group).  An unmineralized gabbroic stock, mapped as part of  the Cretaceous (?) Kluane Range intrusions (Muller, 1967), occurs along the southern margin of the Cork property. Shakwak Trench, a major transcurrent fault zone, separates mainly volcanic and sedimentary rocks of the St. Elias Mountains to the southwest (Insular Belt) from mainly granitic and metamorphic rocks of the Yukon Plateau to the northeast (Coast Crystalline Belt) . The Yukon Complex and the Ruby Range batholith are the major components of the Coast Crystalline Belt in the Burwash Landing area.  The Ruby Range batholith is considered  by Muller(1967) as part of the Coast Intrusions. The age of the Ruby Range batholith cannot be determined directly by i t s relationship to fossiliferous beds (Muller, 1967).  Biotite K-Ar age determinations on quartz monzonite  LEGEND  fyj  FELDSPAR PORPHYRY  LIMIT OF ROCK EXPOSURE  HORNFELS  GEOLOGIC CONTACT  RUBY RANGE BATHOLITH  THRUST FAULT G S C  ICEFIELD RANGE INTRUSIONS gH^j KLUANE RANGE INTRUSIONS fjli 1  MUSH LAKE GROUP  *S!~M'Y  %%'  s a m p l e  LOCATION AND AGE (Lowden I960)  SAMPLE LOCATION AND AGE IN M.Y. (this report)  | PERIDOTITE AND GABBRO CACHE CREEK GROUP  t&$| YUKON COMPLEX FIG.4-2 General geology and geochronology in the Burwash Landing area, Yukon Territory. Geology after Muller (1967).  FIG. 4-3 General geology and geochronology of the Cork prospect (for legend see Fig.2-3.  48.  and granodiorite from the Ruby Range batholith have yielded early Tertiary and Jurassic ages (Lowden, 1960; 1961).  A 58 m.y. biotite  K-Ar age was obtained from gneissic biotite granodiorite east of Burwash Landing.  4.3.2  Potassium-Argon Results  Isotopic age of the.8 analyzed samples are plotted on Figures 4-2 and 4-3. Table 4-2 summarizes K-Ar and apatite fission-track aged obtained for granitic rocks from the Burwash Landing area. Specimens PC3 and PC4 were collected from a mineralized quartz latite porphyry stock located on the Cork property.  Specimens PCI and PC2 were  collected from a chemically and texturally similar but unmineralized stock 3 miles east of" the Cork property.  These porphyritic rocks contain from  1 - 4 % biotite as phenocrysts with minor chlorite alteration along cleavage planes and crystal boundaries.  Unaltered hornblende concentrates were  obtained from gabbro specimens PC5 and PC6 from the Cork property, and unaltered biotite concentrates were obtained from granodiorite specimens PC7 and PC8 from the Ruby Range batholith.  4.3.3  Fission-Track Results  Apatite concentrates were obtained from samples PCI, PC2, PC3, and PC8. The 48.9 + 6.6 m.y. apatite fission-track age.-determined for sample PC8 from the Ruby Range batholith is concordant with and provides support for the 54.5 + 2.0 m.y. biotite K-Ar age determined for this sample. Apatite fission-track ages ranging from 42.4 to 46.6 m.y. (PCI to PC3) were obtained for the porphyritic rocks near Burwash Creek.  These age are  Table 4-2.  Fission-track and K-Ar ages obtained for granitic rocks in the Burwash Landing area, Yukon Territory.  Sample Number  Rock Type  Unit  Mineral dated  Fissiontrack age* (m.y.)  K-Ar age (m.y.)  PCI  Tertiary stock (?)  Qtz. latite porphyry  apatite biotite  42 + 7  PC2  Tertiary stock (?)  Qtz. latite porphyry  apatite apatite biotite  54 + 6 35 + 5  PC3  Tertiary stock (?)  Qtz. latite porphyry  apatite biotite  47 + 5 ~  PC4  Tertiary stock (?)  Qtz. latite porphyry  biotite  26.0 + 1.0  PC 5  Kluane Range Intrusions  Gabbro  hbl.  115  PC6  Kluane Range Intrusions  Gabbro  hbl.  117 + 4.0  PC7  Ruby Range batholith  Bio. granodiorite  biotite  51.9 + 2.0  PC8  Ruby Range batholith  Bio.-Hbl. granodiorite  apatite bio.  Note:  *  26.1 + 1.0  26.7 + 1.2 26.2 + 1.0  49+7  +4.0  54.5 + 2.0  Porphyritic latite sample CKD-1 from the Cork property has a K-Ar age of 26.2 +0.4 m.y. and hornblende diorite sample JCD-1 from the Kluane Range intrusions on the Cork property has a K-Ar age of 111.7 + 2 m.y. (D.C. Way written communication, December 1972). Samples CKD-1 and JCD-1 were analysed by Dr. E. Farrar of the Department of Geological Sciences, Queen's University, Kingston, Ontario.  Fission-track analyses by P.A. Christopher. Constants used in model age calculations: °r U = 6.85 x 1 0 y r ; A for U = 1.54 x 1 0 - y r ; a for U 35 = 582 x I O cm . f  2 3 8  _17  _:L  2 3 8  D  10  -1  2  - 2 4  2  ** Argon analyses by J.E. Harakal and P.A. Christopher using MS-10 mass spectrometer. Constants used in model age calculations: A = 0.585 x  io-io -i. y r  A g =  4 > 7 2  x  1 0  -i  0 y r  -i.  4 0 K / K  m  1 1 8 1  x  10  _4>  e  50.  consistently older than the mean 26.2 +0.3 m.y. biotite K-Ar age determined for samples PCI to PC4, but both methods support the Tertiary age assigned to this unit by Muller (1967). The reason for consistently older apatite fission-track ages is not clear.  Older apatite fission-track apparent ages relative to biotite  K-Ar apparent ages are d i f f i c u l t to explain because argon is retained i n biotite at a temperature that w i l l cause annealing of fission-tracks in apatite (Naeser, 1967a; Naeser and Faul, 1969).  It i s unlikely that  secondary biotite could have formed without the annealing of primary apatite grains and the discrete biotite grains and books appear to be primary biotite.  If weathering was important in lowering the K-Ar age,  i t is not indicated by the small deviation in the four biotite K-Ar apparent ages, in thin section examination of rocks, or microscopic examination of biotite concentrates. The most likely explanation for the discrepancy is a slight bias in counting which might result because of the extremely low spontaneous track density and the small spontaneous to induced track density ratio.  A consistent bias could explain the older ages.  4.3.4 Discussion The 26.2 + 0.3 m.y. mean biotite K-Ar age determined for quartz l a t i t e porphyry (PCI - PC4) i s the best age for emplacement of this unit. Samples were analyzed in a manner suitable for isochron determinations (Roddick and Farrar, 1971), but the narrow range of potassium values for the samples leads to isochron ages with large uncertainties (see section 2.4). The 115 + 4 m.y. and 117 + 4 m.y. hornblende K-Ar ages determined for Kluane Range Intrusions on the Cork property agree with the Cretaceous age  51.  assigned to this unit by Muller (1967).  The 51.9 + 2.0 m.y. and 54.5  +2.0 m.y. biotite K-Ar ages determined for the Ruby Range batholith are slightly younger than the Geologic Survey of Canada age of 58 m.y. (Lowdon, 1961). Tertiary apatite fission-track ages determined for quartz latite porphyry near Burwash Creek and for one sample (PC8) from the Ruby Range batholith are consistent with biotite K-Ar ages and the Tertiary ages suggested for these units by Muller (1967). Both mineralized and barren quartz latite porphyry near Burwash Creek yield ages which are identical within the limits of detection and precision of the K-Ar method. This agrees with the findings of White et al. (1968) that for many British Columbia porphyry mineral deposits, mineralization is an integral feature of a magmatic event. The Cork prospect is in a large belt of Tertiary volcanic and intrusive rocks which extend through the St. Elias Mountains and adjacent Alaska Range (Muller, 1967 p. 102).  This belt may contain other similar  Tertiary porphyry type mineral deposits.  4.4. NORTHERN BRITISH COLUMBIA 4.4.1  Introduction  Seven biotite K-Ar ages and four apatite fission-track ages (Table 4-3) were determined for porphyritic intrusions in northern British Columbia (Figures 4-4 and 4-5).  Samples were selected because of their spatial and  temporal relationship to Mo and Mo-W deposits in the Cassiar and Atlin areas. Sutherland Brown et al. (1971) suggested that an area extending from the Coast Crystalline Belt-Intermontane Belt boundary in the Atlin area across  52.  PC  L E GEND GRANITE PORPHYRY  ATAN GROUP I  | CHERT and OUARTZITE  IjjijjiJ LIMESTONE, DOLOMITE and SKARN  tggSI 1  METASEOIMENTS  and UNDIVIDED SEDIMENTS  SAMPLE LOCATION AGE in M.Y.  and  lllllillfc  L EGEND f O CASSIAR INTRUSIONS PTI ULTRAMAFICSftSERPENTINE £3 SYLVESTER GROUP MM POST ATAN GROUP ^ SEDIMENTS (UNDIVIDED! E33 ATAN GROUP EJJJGOOD HOPE GROUP  l =^«&3's1fr<*  50.2*1.6 ^agi:::::;;y!! si.-S-S-iiS..  Figure 4-4. General geology and geochronology in the Cassiar area, B.C. (after Gabrielse, 1963), Mt. Haskin Mo Property (after G. Lamont, 1971, unpublished mapping) and Mt. Reed Mo-W property (after P. Hirst, 1969, unpublished mapping).  LEGEND TERTIARY  PORPHYRY  JURASSIC  fj3  {.ft**  :\MOLLY  COARSE A L A S K I T E PTT3 Q T Z ^  .....  ^te?-'>&7t*  SPARSE PORPHYRY CROWDED  L  MONZONITE PORPHYRY  FOURTH  of J U L Y  CREEK  CARBONIFEROUS £2*] ©  CACHE CREEK P C 15  62.0*2.2  GROUP  SAMPLE LOC.  and A G E in M.Y  "WW W U * » . « ¥ v W ' / < V V V V V V » V V V V V V V V V V » » SCXfJ'OvvvVVVVVVVVVV VV' ^VVVVVVVVVVVVVVVVVVVV" V V V V V V V V V V V V V V V vr v v v v v v v v v v v v v v v v v v v v v v SCALE IN FEET •VVVVVVVVVVVW , VVVVVVVVVVVVVVVVVVVVVVVV, —  •< V V v v v V V vv>>0 V V V VV V V V V V V V V V V V V V V V V V V ' / •vvvvvvv •Vvvvvvvvvvvvvvvvvvvvvvvv . ' V V V VV" v v v v v v v v v v v v v v v v v v v v v v v v v / • ' V ^ v v v v v v v v v v v - v p c 15 ' W W W ' JVVVVVS 'vvvvvy R  O  I  J  Figure 4-5. General geology and geochronology in the Atlin Area (after Aitken, 1959) and of the Adera Claims - Adanac Mo property (after Sutherland Brown, 1969b) CO  54.  Table 4-3. Fission-track and K-Ar ages of granitic rocks in northern British Columbia.  Unit  Sample Number  Rock Type  Mineral dated  Fission- .K-Ar age** track age* (m.y.) (m.y.)  CASSIAR AREA Mt. Haskin porphyry  PC9  Granite porphyry  apatite apatite biotite  48 + 6 60+8 49.7 + 1.5  PC10  Mt. Haskin porphyry  Granite porphyry  biotite  50.5 + 1.5  PC11  Mt. Reed porphyry  Granite porphyry  biotite  48.7 + 1.9  PC12  Mt. Reed porphyry  Granite porphyry  apatite biotite  54 + 7  PC13  Cassiar intrusions  Quartz monzonite  apatite biotite  67 + 7  PC14  Cassiar intrusions  Quartz monzonite  apatite biotite  60+6  50.2 + 1.6 71.7 +2.6 68.3 + 2.7  ATLIN AREA Mt. Leonard Boss  PC15  coarse Alaskite  62.0 + 2.2  biotite  * Fission-track analyses by P.A. Christopher. Constants used in model age calculations: XF ° U = 6.85 x l O ' l A r r ; ^for U =6.85 x 1 0 " y r ~ l ; \ D for U = 1.54 x 10- yr ; a for U = 582 x IO" cm' f  17  r  2 3 8  2 3 8  - 1  2 3 8  10  1  2 3 5  '**' Argon analyses by J.E. Harakal and P.A. Christopher using MS-10 mass spectrometer. Constants used in model age calculations: X E = 0.585 x 1 0 - y r ; Ag= 4.72 x 1 0 - y r ; 40K/K - 1.181 x I O . 10  -1  10  _1  -4  24  the Stikine Arch into the Omineca Belt i n the Cassiar area contains one of the three major molybdenum concentrations i n the Canadian Cordillera. The general geology of the Cassiar and Atlin areas is described below.  4.4.2 Cassiar Area * The Cassiar Batholith (Figure 4-4) has a mean K-Ar age of 102 + 3 m.y.  Late Cretaceous igneous activity along the western margin of the  Cassiar Batholith is indicated by mean ages of 96 + 3 m.y. from the Seagull Batholith and 76.5 + 4 m.y. from the Glundebery  Batholith, and  by K-Ar ages of 78 + 4 m.y. from the Parallel Creek Batholith and 71 m.y. from a quartz monzonite north of Dease Lake.  Early Tertiary igneous  activity to the west of the Cassiar Batholith is indicated by concordant K-Ar ages of 48 + 4 m.y. on hornblende and 4 6 + 2 m.y. on biotite from a small quartz diorite pluton that intrudes the Christmas Creek Batholith. A young stock, that occurs within the Cassiar Batholith to the northwest of the area shown in Figure 4-4 has yielded biotite K-Ar ages of 5 8 + 3 m.y. and 5 3 + 3 m.y.  The Blue Light property, located in this young quartz  monzonite body, contains tungsten and beryllium minerals  (Mulligan, 1969).  A muscovite K-Ar age of 57 m.y. was obtained from granitized terrain exposed about 10 mi. northeast of Mt. Haskin in the Horse Ranch Range. Gabrielse (in Lowdon et a l . , 1963b) suggested that this age might date the emplacement of post-tectonic plutons and metamorphic rocks  recrystallized  to some extent at that time. Because ,the youngest rocks intruded by the Cassiar intrusions i n the area shown in Figure 4-4, are of Devono-Mississippian *  See Appendix D (Table D-l) for review of ages cited  age (Gabrielse, 1963),  time of intrusion cannot be dated accurately by stratigraphic methods. Samples PC9 to PC14 (Figure 4-4) were collected from: (1)  a quartz monzonite porphyry stock that intruded Paleozoic sedimentary and volcanic rocks to the east of the Cassiar Batholith and  (2)  small granite porphyry stocks, s i l l s and dikes that intruded sedimentary and metasedimentary rocks of the Atan Group. Cassiar Molybdenum Property The Cassiar Molybdenum property (Figure 4-4) occurs within a young  quartz monzonite that cuts the Cassiar Batholith along i t s eastern border (Campbell, 1968).  Stockwork and disseminated molybdenite are related  spatially and probably genetically to a late, fine-grained phase of the young quartz monzonite. Samples PC13 and PC14 were collected from the early, pre-mineralization phase of the quartz monzonite stock.  Biotite concentrates from  these samples contain less than 2% chlorite as alteration along cleavage planes.  Quartz monzonite samples PC13 and PC14 have consistent biotite  K-Ar ages of 71.7 + 2.6 m.y.  and 68.3 + 2.7  Mt. Haskin Mo and Mt. Reed Mo-W  m.y. Properties  Granite porphyry intruded sedimentary and metasedimentary rocks of the Atan Group on both the Mt. Haskin Mo and Mt. Reed Mo-W shown in detail on Figure 4-4).  properties (areas  Stockwork and disseminated molybdenum  and tungsten bearing minerals are found in both the granite porphyry and contact altered metasedimentary rocks.  Mineralization is believed to be  temporally related to the granite porphyry.  Granite porphyry samples PC9 and PC10 are from a small stock on the Mt. Haskin property and granite porphyry samples PC11 and PC12 are from a texturally and chemically similar stock on the Mt. Reed property. Biotite contents of samples PC9-PC12 range from 1 to 4%.  Chlorite content  of the analyzed biotite concentrates i s less than 5%. Granite porphyry samples PC9 to PC12 from Mt. Haskin Mo and Mt. Reed Mo-W  properties have biotite K-Ar ages ranging from 48.7 to 50.5  and a mean K-Ar age of 49.8 +0.7  m.y.  m.y.  Reliable isochron ages could not  be obtained from the granite porphyry (see section 2.4) because of the small differences in potassium content of the biotite concentrates PC9 to PC12. Discussion Ages obtained for quartz monzonite and granite porphyry in the Cassiar area suggest that molybdenum and associated tungsten mineralization occurred after the emplacement of the Cassiar Batholith (102 + 3. m.y.). The 71.7 + 2.6 m.y. and 68.3 +2.7  m.y. ages obtained for a young phase of  the Cassiar intrusions place an upper limit on the age of mineralization on the Cassiar Molybdenum property. Because both mineralized and barren granite porphyry samples from the Mt. Reed and Mt. Haskin properties yield the same age within analytical limits, mineralization on these properties is considered to be an integral part of an early. Tertiary magmatic event. The Late Cretaceous and early Tertiary ages obtained for quartz monzonite porphyry and granite porphyry phases of the Cassiar intrusions are consistent with a trend from older, more basic, granitic phases to younger, more acid, porphyritic bodies.  58.  Apatite fission-track ages obtained from the Cassiar area are in good agreement with K-Ar ages for oogenetic biotite.  Figure 3-1  demonstrates the K-Ar ages and apatite fission-track ages for samples PC8, PC12, PC13 and PC14 are the same within analytical limits.  Because apatite  fission-track and biotite K-Ar ages are concordant, the apatite fissiontrack method is considered to be useful in age dating Late Cretaceous and Tertiary units in the Cassiar area. 4.4.3.  Atlin Area  No radiometric ages are available for intrusive rocks in the Atlin area.  Ages ranging from 54 m.y.  to 70 m.y. were reported from the Bennett  area to the west and adjacent parts of the Alaska Panhandle (Cristie in Lowdon et a l . , 1963a), and an age of 69 m.y. was obtained from quartz monzonite in the Tulsequah area to the south.  Souther (in Lowdon et a l . ,  1963b) reported that discordant quartz monzonite stocks along the eastern contact of the Coast Crystalline Belt in western British Columbia and southeastern Yukon are part of the youngest phase of the Coast Intrusions. More recently, K-Ar whole-rock and biotite ages ranging from 46.9 to 52.8 m.y. were obtained from quartz monzonite of the East Marginal Pluton of the Coast Intrusions in the Juneau Ice Field area (Forbes and Engles, 1970).  These data reinforce the early Tertiary K-Ar ages for granitic  rocks along the eastern margin of the Coast Intrusions.  Adanac Mo Property Figure 4-5 shows the location and general geology of the Adanac area. The Adanac Mo property i s on upper Ruby Creek, and molybdenum with minor  tungsten is found in granitic rocks that are part of the Mt. Leonard Boss mapped by Sutherland Brown (1969b). The Mt. Leonard Boss intrudes a sequence of rocks ranging i n age from Permo-Pennsylvanian Cache Creek metavolcanic rocks to the Fourth of July Batholith which has been assigned a Jurassic (?) age (Aitken, 1959). Sutherland Brown (1969b) suggested that the midCretaceous (?) Mt. Leonard Boss i s in a l l probability connected to the main Suprise Lake Batholith and that a l l phases of the stock are as closely related i n age as they are in chemistry. One sample (provided by W. Sirola) was available from the Mt. Leonard Boss. This sample contained about 1% biotite with 15% chlorite alteration. A biotite concentrate containing about 5% chlorite was obtained from the sample. Low potassium content of the biotite (5.16 + 0.04%) is caused by chlorite alteration.  A 62.9 + 2.2 m.y. K-Ar age was obtained for the biotite  concentrate. The 62.9 + 2.2 m.y.  age for the alaskite phase of the Mt. Leonard Boss  is consistent with the young age of discordant quartz monzonite stocks along the eastern contact of the Coast Crystalline Belt (Souther in Lowdon et a l . , 1963a; Forbes and Engles, 1970). 4.4.4  Conclusions Late Cretaceous and early Tertiary ages obtained for the Adanac Mo  property, Cassiar Mo property, Mt. Haskin Mo property, and Mt. Reed  Mo-W  property, and early Tertiary ages reported for quartz monzonite and pegmatite associated with the Blue Light tungsten property (Wanless et a l . , 1970) indicate a Late Cretaceous to early Tertiary metallogenic epoch for molybdenum and tungsten in northern British Columbia.  The existence of a  60.  Late Cretaceous to early Tertiary metallogenic epoch for porphyry mineral deposits has previously been suggested for central British Columbia (Carter, 1970; 1972a) and for southeastern Alaska (Reed and Lanphere, 1969).  4.5 GRANISLE MINE, BABINE LAKE AREA, BRITISH COLUMBIA 4.5.1  Introduction  Copper deposits of the Babine Lake area are related to small, highlevel, subvolcanic porphyritic intrusions of early Tertiary age that intrude Mesozoic volcanic and sedimentary rocks of the Hazelton Group (see Carter, 1972b, Fig. 12, page 28; Carter, 1970). northwesterly  The intersection of  and northeasterly striking faults may have controlled  emplacement of Tertiary intrusions.  Porphyry copper deposits are  associated with dykes and plugs of biotite-feldspar porphyry of quartz diorite composition.  Biotite K-Ar ages obtained for 10 samples from  porphyries have yielded a mean age of 51.2 + 2 m.y. (Carter 1972b). The Granisle Mine has been classified as an elaborate porphyry deposit (Sutherland Brown, 1969a) because of the several phases and pulses of biotite-feldspar porphyry that are spatially and temporally associated with copper mineralization.  An oval zone of potassic alteration is roughly  coincident with the ore zone and a number of north 50° east striking bornitechalcopyrite-quartz-biotite-apatite veins occur i n the potassic zone (Carter, 1972b).  4.5.2. Potassium-Argon Dating A mean biotite potassium-argon age of 51.2 + 2 m.y. was determined for  61.  J—I—L.  4 0 0 feet  m A ^ l  BIO.-FELD. PORPHYRY undivided INTRUSIVE BRECCIA  P7~] BIO-FELD. PORPHYRY gray massive m L_—I  BIO.-FELD. PORPHYRY fractured,mineralized  / / / / n/v Vt  contact; defined, assumed fault edge of open pit  • N C 6 9 - 8 Sample Location 50.2 ± 2 . 1 K-Ar Age m.y. FT30±4 Fission-Track Age m.y.  |~2~| QUARTZ DIORITE |  Figure 4-6.  T | METAMORPHIC ROCKS  Geochronology and general geology of the Granisle Mine pit (geology from Carter, 1972b).  three samples of biotite-feldspar porphyry and one sample (NC-69-8) of a quartz-chalcopyrite-bornite-apatite vein from the Granisle Mine (Carter, 1972b).  Biotite from sample NC-69-8 has a K-Ar age of 50.2 + 2.1 m.y.  (N.C. Carter personal communication, 1972). 4.5.3  Fission-Track Dating  Part of sample NC-69-8 was obtained from N.C. Carter to obtain apatite for a fission-track age determination.  Apatite grain mounts used  to determine the fission-track age revealed two generations of apatite; 1) minor very clear and relatively unaltered apatite, (selectively counted), and 2) highly altered grains containing fluid, chalcopyrite and altered silicate inclusions. Only a few useable grains could be obtained by scanning the grain mounts at low power. A fission-track age of 29.6 + 4.1 m.y. obtained for this sample is discordant with the 51.2 + 2 m.y. biotite K-Ar age, but the apatite fission-track age does reflect the young Tertiary age. 4.5.4  Discussion  The 50.2 + 2.1 m.y. biotite K-Ar age of sample NC-69-8 (Figure 4-6) is supported by mean K-Ar ages of 51.2+2 m.y. for four samples from the Granisle Mine and 51.2 + 2 m.y. for ten K-Ar age for porphyries in the Babine Lake area (Carter, 1972b).  The 3 0 + 4 m.y. apatite fission-track  age i s young and could be a reset age, but alteration of apatite grains made track distinction d i f f i c u l t and the error in this determination may be larger than the counting error.  63.  -4.6  COPPER MOUNTAIN AREA, BRITISH COLUMBIA 4.6.1  Introduction  The Copper Mountain and Ingerbelle mineral deposits, which are located on opposite sides of the Similkameen River, about 10 miles south of Princeton, British Columbia, occur in syenitic stocks and volcanic rocks of the Upper Triassic and Lower Jurassic Nicola Group.  These 'syenitic'  deposits have been classified on the basis of structure as complex porphyry deposits (Sutherland Brown, 1969a) and on the basis of the highlevel of emplacement of an associated and genetically related variable shaped pluton as volcanic porphyry deposits (Sutherland Brown, 1972). Copper deposits of the 'syenitic' volcanic porphyry class appear to be restricted to the intermontane tectonic belt of the Canadian Cordillera. Comprehensive geologic reports on the geology of the Copper Mountain area by Dolmage (1934), Rice (1947), Fahrni (1951, 1962, 1966), Montgomery (1967) and Preto (1972a and b) and K-Ar age dating studies by Sinclair and White (1967) and Preto et a l . (1971) support the geologic interpretation presented in Figure 4-7. Table 4-4 i s a l i s t i n g of the apatite fission-track ages obtained for samples previously dated by the biotite K-Ar method. 4.6.2  General Geology  Figure 4-7 shows the general geology of the Copper Mountain area and the location of the Ingerbelle and Copper Mountain mineral deposits. The oldest rocks in the area are part of the Upper Triassic Wolf Creek Formation of the Nicola Group (Rice, 1947).  In the Copper Mountain area the Wolf  Creek Formation is predominately andesite, tuff and volcanic clastic sediments  64.  FIGURE2-7  GENERAL GEOLOGY OF T H E COPPER MOUNTAIN AREA BRITISH COLUMBIA PRINCETON GROUP  MONZONITE  VERDE CREEK QTZ. MONZ. NICOLA GROUP  LOST HORSE INTRUSION PERTHOSITE PEGMATITE 4  CM-I2-65 I82«8  VP-69AK-I ' 194  *a  SAMPLE LOCATION AND AGE IN M.Y( Preto et al..1971)  SAMPLE LOCATION AND AGE IN M.Y. (Sinclair and White, I968) FTt01*12  FISSION-TRACK AGE M.Y. (this report)  65.  that generally display very mild metamorphism and deformation, except in the immediate vicinity of intrusive bodies (Preto, 1972b). A number of quartz-poor plutons, collectively known as the Copper Mountain intrusions (Montgomery, 1967) are spatially and genetically related to the mineral deposits.  The largest, the Copper Mountain stock, i s a concentrically  differentiated intrusion, e l l i p t i c a l in plan and about 6.5 square miles in area.  It ranges in composition from diorite at i t s outer edge through  monzonite to syenite and perthosite pegmatite at the core (Montgomery, 1967). Preto et a l . (1971) divide the Copper Mountain intrusions into the zoned Copper Mountain stock, the satellite Smelter Lakes and Voigt stocks, and the Lost Horse intrusions (Figure 4-7).  Northeast of Copper Mountain,  diorite of the Voigt stock and volcanic rocks of the Nicola Group are cut by a body of younger quartz monzonite that was named the Verde Creek granite by Dolmage (1934) and believed by Rice (1947) to be correlative with the Otter intrusions of.Upper Cretaceous or younger age.  K-Ar age dating by  Preto et a l . (1971) supports the Cretaceous age assigned to the Verde Creek body. In the vicinity of the Copper Mountain and Ingerbelle mineral deposits alkali metasomatism has produced a distinctive mineral assemblage characteristic of copper deposits of the Nicola Belt.  Alteration is most  intense in the Lost Horse intrusions and bears a close spatial relationship to faults and fractures (Preto, 1972a). Successive stages of alteration recognized by Preto (1972a) are: 1)  Development of biotite that has been partly destroyed by later alteration.  66.  2)  Development of albitlc plagioclase and epidote that was accompanied by removal of biotite and of disseminated magnetite, and bleaching of pyroxene.  Secondary sphene,  apatite and pyroxene are locally developed. 3)  Development of pink potash and plagioclase feldspar along fractures that was accompanied by sulfide-bearing pegmatite veins characterized by selvages of coarse biotite along the edges and bornite, chalcopyrite, potash feldspar, and calcite at the center.  4)  Development of late scapolite veins that are most prominent in the Ingerbelle area.  Because biotite and apatite used for some of the age dating was developed during the alteration stages, the interpretation of radiometric ages would be tenuous without the detailed description of alteration provided by Preto (1972a and b). 4.6.3  Fission-Track Dating  Ten samples (VP69 (KA1 to KA10) ) from the Copper Mountain area that had previously been dated by the biotite K-Ar method (Preto et a l . 1971) were obtained from the British Columbia Department of Mines. Apatite concentrates were obtained from eight of the ten samples, but intense alteration of apatite grains eliminated the possibility of using four of the eight apatite concentrates for fission-track dating.  Sample KA4 from  the Verde Creek quartz monzonite in the Copper Mountain area gave discordant 101 + 4 m.y. biotite K-Ar and 129 + 23 m.y. apatite fission-track apparent  67  ages. The minor discordance is attributed to the altered nature of the apatite grains. Samples KA1, KA9 and KA10 from the Copper Mountain intrusions yield a mean apatite fission-track age of 111 + 7 m.y. and a mean biotite K-Ar age of 195 + 2 m.y. Biotite K-Ar ages for samples KA1, KA9 and KA10 are in close agreement with mean biotite K-Ar age of 193 + 8 m.y. reported by Preto et al. (1971) for eleven samples from Copper Mountain. The Copper Mountain intrusions are believed to be co-magmatic with the Upper Triassic to Lower Jurassic Nicola volcanics, and since extensive K-Ar dating supports an Upper Triassic or earliest Lower Jurassic age for the Copper Mountain intrusions (Preto et al. 1971; Sinclair and White 1968), the Cretaceous apatite fission-track ages for the Copper Mountain intrusions probably represent reset ages or thermally lowered ages. A widespread Cretaceous thermal event in the Copper Mountain, area is suggested by: 1)  the average age of 99.5+4 m.y. determined by Preto et a l . (1971) for the Verde Creek quartz monzonite.  2) a 104 m.y. age suggested for the major phases of the Eagle granodiorite lying to the west of Copper Mountain (Roddick and Farrar, 1972), and 3) an Early to Middle Cretaceous thermal event dated about 100 m.y. in northcentral Washington (Hibbard, 1971). . The consistent low ages obtained for apatite from the Copper Mountain intrusions suggest a thermal event that was strong enough to reset the apatite fission-track clocks but not the biotite K-Ar clocks. A temperature between  68.  about 75°C (Naeser and Faul, 1969; Wagner 1968) and 150°C (Damon, 1968) associated with a Cretaceous thermal event would account for the difference in apparent fission-track and biotite K-Ar ages. 4.6.4 Summary A 129 + 23 m.y. apatite fission-track age for the Verde Creek quartz monzonite supports the Cretaceous age for this unit.  A mean apatite  fission-track age of 111 + 7 m.y. for samples KA1, KA9 and KA10 from the Copper Mountain intrusions reflect a heating event that i s related to Early to Middle Cretaceous granitic intrusion.  Table 4-4. Fission-track and K-Ar ages obtained for granitic rocks i n the Copper Mountain area, British Columbia. (K-Ar ages are from Preto et a l . , 1971) Sample Number  Unit  Mineral dated  Fissiontrack age (m.y.)*  KA1  Lost Horse intrusion  apatite biotite  117 + 12  KA4  Verde Creek qtz. monz.  apatite biotite  129 + 23  KA9  Lost Horse intrusion (dike)  apatite biotite  101 + 12  KA10  Lost Horse intrusion  apatite apatite biotite  101 + 13 127 + 18  K-Ar age (m.y.)  194 + 8 101 + 4 197 + 8  195 + 8  * Fission-track analyses by P.A. Christopher, Constants used in model age calculations: /| for U = 6.85 x 1 0 ~ y r ; / i for U = 1.54 x l O - ^ y r " ; o-for U = 582 x 10 cm . 2 3 8  17  F  1  _1  2 3 8  D  2 3 5  _24  2  69.  5. REVIEW OF METALLOGENY AND METALLOGENIC EPOCHS FOR PORPHYRY MINERAL DEPOSITS OF THE CANADIAN CORDILLERA  5.1 Introduction In this chapter the K-Ar ages obtained for this study and published ages are used to place porphyry mineral deposits of the Canadian Cordillera in a tectonic-stratigraphic-lithologic framework; the concept of metallogenic epochs is evaluated for porphyry and related mineral deposits; and the concept of metallogenic epochs for porphyry deposits is examined in terms of global tectonics. 5.2 Metallogeny and Metallogenic Epochs Metallogeny is concerned with the genesis of mineral deposits and with their distribution in space and time. Metallogenic provinces and metallogenic epochs reflect an uneven distribution of various types of mineral deposits in space and time. The first statement of the concept of metallogenic provinces and metallogenic epochs was presented by De Launay (1913). As the result of his regional studies of mineral deposits in France, De Launay suggested that each metallogenic province belongs to a definite regional type depending on the tectonics and that the nature of each province may be forecast, to a certain extent, by the knowledge of the latter. This is a very comprehensive and concise statement of the problem encountered by the geologist attempting to outline a genetic model for a metallogenic province. Lindgren (1933) discussed the factor of time as i t concerns the mineral deposits of a metallogenic province, and Petrascheck (1965) credits Lindgren  70.  with the introduction of the concept of a metallogenic epoch. Lindgren's examples suggest that metallogenic epochs coincide with the major orogenic epochs in the earth's history.  Turneaure (1955)  used the term metallogenic epoch to designate periods during which mineralization was most pronounced. Petroscheck (1965) restricted metallogenic epochs to tectonic metallogenic intervals within a major tectonic unit (e.g. orogenic belt, shield area, or craton). If the concept of a metallogenic epoch i s to be of use in classification and exploration of mineral prospects, a metallogenic epoch must be applied to a stage or interval within a tectonic cycle. The idea of relating mineral deposits to stages of development of orogenic belts was developed i n the U.S.S.R. by Bilibin (1955).  Bilibin's i n i t i a l  work was concerned with endogenous (hypogene) mineral deposits. Semenov and Serpuklov (1957) added a study of exogenous (sedimentary and supergene) deposits to the regional metallogenic analysis. In Canada, the application of a tectonic approach to the study and classification of ore deposits i s more recent.  C.J. Sullivan's (1948)  paper entitled "Ore and Granitization" was an early step toward a tectonic cycle approach.  Sullivan emphasized the composition of the stratigraphic  column through which intrusions make their way upward.  Sullivan's (1957)  classification of metalliferous provinces and deposits stresses field association and a "source bed" approach i s used in his classification. McCartney and Potter (1962) and McCartney (1965) reviewed metallogeny of the Canadian Appalachians using Russian metallogenic concepts. In  71.  these reviews the emphasis i s on type of magmatic activity and related mineral deposits typical of successive stages of folded belt development. Sutherland Brown et a l . (1971) related the general distribution of mineral deposits i n the Canadian Cordillera to tectonic evolution. Porphyry mineral deposits of the Canadian Cordillera f i t into a generalized tectonic scheme (Figures 5-la, b and c) that shows the distribution of porphyry mineral deposits in time and space within the Canadian Cordillera.  A.Y. Bilibin (1955) and A.I. Semenov and V.I.  Serpuklov (1957) applied a similar approach to mineral deposits i n folded belts of the U.S.S.R., and W.D. McCartney and R.R. Potter (1962) applied the tectonic concepts developed in the U.S.S.R. to mineral deposits of the Canadian Appalachians.  The classic geosyncline model ( S t i l l e , 1936  and Kay, 1951) used by these workers has been replaced by a plate-tectonic approach.  The general idea of cyclic development of a mobile belt holds,  but cyclic development should only apply to well-defined segments of recrystallized s i a l (Monger et a l . , 1972), segments with different metallogenic and tectonic development may now be contiguous belts. An hypothesis that can be applied to the metallogeny or tectonics of one part of a tectonic belt may not be valid once a major fault is crossed or an apparent unconformity is encountered in the stratigraphic section. 5.3 Tectonic Setting Sutherland Brown et a l . (1971), Souther (1970), Wheeler (1970), Hodder and Hollister (1972) and Monger et a l . (1972) have described the tectonics and (or) mineral deposits of the Canadian Cordillera in terms of five distinct geological and physiographical belts.  These are (from east  72. Figure 5 - l a .  Tectonic s e t t i n g of porphyry m i n e r a l deposits the Canadian C o r d i l l e r a ( 4 9 - 5 2 ° N ) .  in  DIORITE - SYENITE CLANS QUARTZ DIORITE-GRANITE C L A N S GABBRO AND ULTRAMAFE ROCKS BASIC VOLCANICS ISLAND ARC VOICANISM mainly andesite CONTINENTAL VOLCANISM mainly dacite & rhyofite PLATEAU4VALLEY BASALT NO LINKAGES KNOWN BETWEEN TECTONIC BELTS (alter MONGER et a.,1972)  ANGULAR UNCONFORMITY, NONCONFORMA8LE. or UNCONFORMABLE  NOT IN CONTACT, or FAULT CONTACT j y UPLIFT \ \ SUBSIDENCE — CONFORMABLE ISLAND COPPER Cu;Mo HEP Cu;Uo CATFACE Cu;Mo MT. WASHINGTON Cu;Mo TOFINO Mo CORRIGAN C K . Cu;Mo GREENDROP LK_ Cu;Mo GUICHON BATHOLITH Cu.Mo COPPER MOUNTAIN Cu IRON MASK Cu MAGGIE Cu: Mo McBRIDE CK. Cu;Mo LOSTCK. Mo RED MOUNTAIN Mo Brenda Mo.Cu  570  Figure 5-lb. Tectonic setting of porphyry mineral deposits in the Canadian Cordillera (52-56°N). Canadian m.y.  INSULAR  Cordillera  COAST  52-56°N  INTERMONTANE  A  (Cu.Ag massive sulfide)  A  40-50  5354  -65  60-69  GG  64-79 HyOx 8 0 v  98-105  BM  138-143 ^8P  I f — !  J H A Z E L J O N ^ Lr A  MAUDE  - 190195  205  -  215  •225  -  280  325 345  395  "  500  5 70  EASTERN MARGINAL PROPERTIES Lr LORRAINE Cu E EN0AKO Ma BM BOSS MOUNTAIN Mo Hy HUCKLEBERRY Cu:Mo Ox OX LK. Cu;Mo GG GLACIER GULCH MO;W BCM BRITISH COLUMBIA MOLYBDENUM Ma Nm NEWMAN Cu Gt GRANISLE Cu Bg BERG Cu;Mo SG SAM GOOSLY  3738  -  OMINECA  HOGEM  •• • KARMUTSEN*  E  Figure 5-lc.  Tectonic setting of porphyry mineral deposits in the Canadian Cordillera (56-64°N).  PROPERTIES BC BURWASH Ck CuMo Ad Adanac Mo:W Sk STIKINE COPPER Cu LC LIARD COPPER Cu Cs CASINO Cu;Mo;W MR MT. REED Mo;W MH MT. HASKIN Mo Ct CANTUNG (skarn) MT MACTUNG (W skam) W  <-570  C  u  75.  to west): (1)  Eastern Marginal Belt,  (2)  Omineca Belt,  (3)  Intermontane Belt,  (4)  Coast Crystalline Belt, and  (5)  Insular Belt.  The terminology and belt configuration (Figure 5-2) used in this discussion follows Sutherland Brown et a l . (1971).  Because mineral  deposits appear to be characteristic of individual belts, the configuration of belts shown in Figure 5-2 is applicable to a discussion of the distribution of endogenic mineral deposits in space and time. Monger et a l . (1972) suggested that from the record in the Canadian Cordillera the present configuration of five geologic belts was only obtained by late Mesozoic time.  Clastic wedges shed from the Omineca  Belt during the Caribooan Orogeny (Antler Orogeny in the western United States) indicate that the Omineca Belt existed as a positive feature by late Devonian time.  A l l the present tectonic elements were in existence  by late Triassic time and common stratigraphic units linked the northern parts of the Omineca, Intermontane and Coast Crystalline belts by Upper Triassic time (Monger et a l . , 1972). In late Cretaceous and early Tertiary time the Canadian Cordillera represented a mobile belt similar to the present-day Andes (Monger et a l . , 1972) with great volumes of subaerial volcanic rocks.  These volcanics  represent the cover into which many small, calc-alkaline, epizonal,  76.  SIMPLIFIED TECTONIC MAP OF THE CANADIAN CORDILLERA LATE TERTIARY PLATEAU BASALTS  14-/-, '  / NORTHERN -.-—...YUKON | \ \ / / § ' MTS \  JURA-CRETACEOUS CLASTIC ROCKS OF BOWSER BASIN  i •  ) i — h  s—I"  GRANITIC ROCKS OF COAST CRYSTALLINE BELT TRIASSIC MARINE BASALT OF INSULAR BELT LOWER PALEOZOIC SEDIMENTARY ROCKS OF OMINECA 8 EASTERN MARGINAL BELT HELIKIAN a HAORYNI AN M ETAS EDI MENTARY ROCKS OF OMINECA BELT BOUNDARIES OF TECTONIC BELTS BOUNDARIES OF MINERALIZED REGIONS  11  PROJECTIONS OF MAJOR CRATONIC FRACTURES  Miles 100  100  N, r"' \  1  Figure 5-2. Tectonic Map (from Sutherland Brown et a l . , 1971).  77.  subvolcanic stocks and some alkaline epizonal stocks were emplaced. Following the mid-Eocene volcanic events, most of the four eastern belts were inverted from a mobile belt under compressional stress to a stable continent edge.  Souther (1970) suggested that onset of relaxation by  late Eocene time was accompanied by a complete change in the structural style, volcanism and plutonism indicated by: 1)  structural trend switching from predominately west-northwesterly to northerly,  2)  acid volcanism replacing andesitic island-arc volcanism,  3)  block faulting replacing elongate grabens and,  4)  high-level intrusions of granitic plutons and dikes.  Atwater (1970) suggested that intrusion and eruption of calc-alkaline magmas of predominately intermediate and s i l i c i c compositions should have existed above formerly active Benioff zones and should have ceased when subduction ceased.  The 25-30 m.y. paucity of volcanism between Late Eocene  and Miocene time suggests a major change in the plate interactions. 5.4 Age Dating and Metallogenic Epochs The importance of isotopic age dating in establishing metallogenic epochs and concepts of metallogeny has been stressed by White (1966), White et a l . (1968), and Livingston et a l . (1968).  Several authors (White et a l . ,  1968; Livingston et a l . , 1968; Moore et a l . , 1968; Fyles et a l . , 1973) have demonstrated the close association of intrusion and mineral deposition in Cordilleran porphyry mineral deposits by showing that the ages of the mineral deposit and the host or associated intrusion are within the limits of detection of the K-Ar method. The sub-volcanic setting for porphyry mineral  78.  deposits has been suggested by White (1966), Carter (1970 and 1972b), Sutherland Brown et al. (1971), Northcote and Muller (1972) and others. Therefore, by obtaining the age of the porphyritic mineral deposit, the deposit can be placed in the proper lithologic-tectonic-stratigraphic environment. The K-Ar dating method has been extensively used for determining the apparent age of intrusive rock in the Canadian Cordillera.  Since  the early 1960s several hundred K-Ar determinations have been published. Published age determinations that form a basis for this review are listed in Appendix D.  Age patterns for intrusive rocks are examined by plotting  histograms (Figures 5-3 and 5-4) of K-Ar ages published after 1965 and ages obtained by Mathews (1964) that are in close agreement with fossil evidence.  Many ages reported before 1965 have been found to be unreliable  and therefore, ages reported before 1965 are not used in histogram plots. Variation in apparent age of plutonic rocks is examined by plotting histograms for segments parallel to the north-westerly trend of the Canadian Cordillera (tectonic belts) and normal to the trend of the Canadian Cordillera (arbitrary segmenting by latitude).  Figure 5-3 shows  the variation of K-Ar ages for tectonic belts and Figure 5-4 shows variation of K-Ar ages for southern, central and northern segments of the Canadian Cordillera. 50 m.y.,  The total plot of K-Ar ages has concentrations at about 26  78 m.y.,  98 m.y.,  140 m.y.  m.y.,  and 198 m.y. but only the 50 m.y. peak  consistently appears in the various tectonic segments.  Age plots appear to  reflect both a geographic bias and a mineral deposit bias.  The Late  Triassic (Guichon Batholith and Copper Mountain intrusions), Late Jurassic  25  INTERMONTANE  BELT  20  15 r-i  10  5  JQ=L  f~l  n  10  n INSULAR BELT  r-i  r-  r-n  49-5l"N  1 r~i~-i  ; '-J^L  n  51-56°N  n  n r  l—i  56-64° N  I  •I II  20  OMINECA BELT  15  10  r - i r -j—Ii r - i  I I• r-i—i  i  i i  U  JI  1  II  ; i  n 1  r-  —1  1  i r-i  .  r--52-56°N  m  n  -  —  r—i  n  pur 10  ,—  5  I  1  -'"1  COAST CRYSTALLINE BELT  1  !  r-H 49-52°N  i  1  1  1  r—I  r-i  52-56° N —  n  r—1  56-64°N  20  Figure 5-3.  r ^ n 60 40  80  100  120  age in m.y.  140  160  180  200  220  K-Ar age determinations for igneous rocks in the Canadian Cordillera. Dashed line represents total for tectonic belt.  80.  Figure 5-4.  K-Ar age determinations for igneous rocks in segments of the Canadian Cordillera between 49-52°N, 52-56°N and 56-64°N.  81.  (Topley Intrusions) and in part the Eocene peaks reflect vigorous collecting of samples that are from porphyry mineral, deposits and the Isotopic Age Map of Canada (Wanless, 1969) shows concentrations of samples in south-central British Columbia, the Skeena Arch area and the Cassiar Mountains. Gilluly (1973) suggested that, "taking the Cordillera as a whole, magmatism was roughly constant except for the apparent low about 115 to 125 m.y. ago".  This low in number of K-Ar ages for igneous rocks is  especially apparent in the Canadian Cordillera (Figure 5-4) and may represent a time of major change in either direction or rate of plate motion.  Evolution of the continental margin from an Indonesian type  island arc to an Andean type margin (Wheeler et a l . , 1972) occurred during early Cretaceous time and may be related to rebound of light s i a l i c material consumed during early Mesozoic subduction. Gilluly's (1973) suggestion that episodic magmatism is a local phenomenon and that magmatism was roughly constant in the Cordillera, appears to hold for early Mesozoic time in the Canadian Cordillera but his suggestion i s not supported by the low in early Cretaceous K-Ar ages or by the widespread pulse of Eocene igneous activity.  The apparent early Cretaceous change  in the pattern of K-Ar ages for igneous rocks may represent either a reduction in the effect of burial on the apparent K-Ar age of igneous rock emplacement or a more uniform history for the various tectonic belts that were completely linked by Cretaceous time (Monger et a l . , 1972). Metallogenic epochs for porphyry mineral deposits are also examined by plotting a histogram (Figure 5-5).  For porphyry deposits, the number of  significant mineral deposits is plotted against the K-Ar age.  Porphyry  (^^approximate number of  K-Ar ages  •Phallic  Class-  •20  Plutonic & Volcanic Classes  15 RS T B9  cT  10  NIH MR RM  ©  s  ©  > i  7  ©  Ad Ca M OO 20  40  60  © [ic] 80  100 age in m.y.  120  140  160  180  Figure 5-5. K-Ar age of porphyry mineral deposits in the Canadian Cordillera. GD - Greendrop Lk.; BC - Burwash Ck. ; CC - Corrigan Ck.; MW - Mt. Washington; S - Serb; RB - Red Bird; T Tofino Mo.; Bg - Berg; Cf - Catface; MH - Mt. Haskin;,MR - Mt. Reed; Ad - Adanac; M - Maggie; Cs - Casino; GG - Glacier Gulch; LCK - Lost Ck.; BM - Boss Mtn.; E - Endako; B - Brenda; IC Island Copper; Lr - Lorraine; LC - Liard Copper; CM - Copper Mountain.  200  83.  Figure 5-6. Triassic lavas and the Triassic and Jurassic porphyry deposits (from Sutherland Brown et a l . , 1971). IC - Island Copper; CM - Copper Mountain and Ingerbell; Ba - Brenda; HV - Highland Valley; CB - Cariboo Bell; E - Endako; Lr - Lorraine; Sk - Stikine Copper; GL - Gnat Lake.  84.  Figure 5-7. Early Tertiary volcanic rocks and porphyry deposits (modified from Sutherland Brown et al. 1971). Cs - Casino; BC Burwash Creek; Ad - Adanac; BEM - British Columbia Molybdenum; Gi Granisle; GG - Glacier Gulch; Bg - Berg; Cf - Catface; GD - Greendrop Lake.  85.  mineral deposits f i t into several age groupings that show consistent metal content and geologic setting. K-Ar dating of porphyry mineral deposits indicates metallogenic epochs at about 195 m.y. 10 m.y.  and 150 +  for deposits that f i t in Sutherland Brown's plutonic and volcanic  classes; and 26 m.y.  and at about 100 m.y.,  80 m.y.,  65 m.y.,  50 m.y.,  35-40 m.y.  for deposits that f i t into Sutherland Brown's phallic class.  Porphyry mineral deposits are distributed throughout the four western tectonic belts.  Porphyry copper deposits are associated with Triassic  to Miocene intrusions and volcanic rocks (Figures 5-6 and 5-7) of the Insular and Intermontane belts and porphyry molybdenum and tungsten deposits are associated with Jurassic to Eocene intrusions into metasedimentary and sedimentary rocks of the Coast Crystalline Belt, Intermontane Belt and Omineca Belt.  The 50 m.y.  metallogenic epoch is the only mineralizing  event that has been documented and is significant in the four western tectonic belts. Porphyry deposits of the plutonic and volcanic classes have received the most attention from exploration and research projects because they are the major producers and contain the major proven reserves of copper and molybdenum in the Canadian Cordillera. 5.5.  PLATE TECTONICS AND METALLOGENY OF PORPHYRY MINERAL DEPOSITS The relationship of porphyry mineral deposits to paleo-Benioff zones  has been discussed on a global basis by S i l l i t o e (1972 a and b), Guild (1971 and 1972), and Mitchell and Garson (1972).  These authors generally  conclude that porphyry copper deposits are derived from materials regenerated in subduction zones and emplaced at high levels in the crust with stocks of  86.  calc-alkaline affinity.  An eastern migration of intrusive centers has  been suggested for western South America (Farrar et a l . , 1970; Ruiz et a l . , 1965) and S i l l i t o e (1972) suggests that the age of porphyry deposits show a similar age distribution in the Cordillera of the United States and Mexico.  Age patterns for porphyry mineral deposits in the  Canadian Cordillera do not show a simple trend.  Deposits range i n age  from Jurassic (Island Copper) to Miocene (Burwash Creek) i n the Insular belt and from Triassic (Copper Mountain, Bethlehem, Lornex, Stikine Copper etc.) to Eocene (B.C. Molybdenum, Granisle, Bell etc.) in the Intermontane Belt. The age pattern of mineral deposits does support a basic difference between the pattern of development of porphyry deposits in the Intermontane and Insular belts.  Triassic 'syenitic' volcanic porphyry deposits are  restricted to the Intermontane belt and porphyry deposits of the volcanic class are associated with a middle Jurassic island arc assemblage (Bonanza Group)on Vancouver Island.  Post-Eocene porphyry deposits are restricted to  the Insular tectonic belt and Cascade Mountains and in particular to areas that appear to be affected by post-Eocene subduction.  Atwater (1970)  and Grow and Atwater (1970) suggest post-Eocene underthrusting of the Farallon Plate and Kula Plate below Vancouver Island and the Aleutian Arc respectively.  The timing and direction of underthrusting of these plates  is supported by the young age of the Mt. Washington and Corrigan Creek porphyry deposits on Vancouver Island (Carson, 1969), the Greendrop Lake property in the Cascades, and the Burwash Creek porphyry deposit southwest of the Shakwak Trench in the Yukon Territory.  Widespread Eocene igneous  87.  activity in the Canadian Cordillera suggests that subduction was occuring along the western margin of the continent until about 45 m.y.  Post-  Eocene transform motion from north of Vancouver Island to the Aleutian Trench would explain the distribution of igneous activity and the presence of younger porphyry mineral deposits on Vancouver Island, in the Cascade Mountains and in the St. Elias Fold Belt.  88.  6. CONCLUSIONS  The following conclusions are based on fission-track and K-Ar dating of intrusive rocks from the Syenite Range and Burwash Landing area in the Yukon Territory and from the Cassiar area, Adanac property, Granisle Mine and Copper Mountain area i n British Columbia; and on a review of published K-Ar ages for igneous rocks in the Canadian Cordillera. 1.  A 26+0.3 m.y. mean K-Ar age was determined for four biotite concentrates from quartz latite porphyry near Burwash Creek, Yukon Territory.  This apparent age for  mineralized porphyry represents the youngest documented porphyry prospect i n the Canadian Cordillera. 2.  The 115 + 4 m.y. and 117 + 4 m.y. hornblende K-Ar ages determined for Kluane Range intrusions on the Cork (Burwash Creek) property agree with the Cretaceous age assigned to this unit by Muller (1967) .  3.  The 51.9 + 2.0 m.y. and 54.5 + 2.0 m.y. biotite K-Ar ages determined for the Ruby Range batholith east of Burwash Landing agree with a previous 58 m.y. K-Ar age (Muller in Lowdon, 1960) for a marginal phase of the batholith. Muller (in Lowdon, I960; p. 9) described the 58 m.y. age as unexpected, but concordant biotite K-Ar and apatite fission-track ages of 54.5+2.0 m.y. and 48.9 +6.6 m.y. respectively for granodiorite sample PC8 provides convincing support for the early Tertiary apparent age for at least  part of the Ruby Range batholith. Granite porphyry on the Mt. Haskin Mo and Mt. Reed Mo-W properties east of Cassiar, British Columbia has four biotite K-Ar ages ranging from 48.7 to 50.5 m.y. and a mean biotite K-Ar age of 49.8+0.7 m.y. Apatite fission-track ages of 4 8 + 6 m.y. and 60 + 8 m.y. for granite porphyry sample PC9 from the Mt. Haskin property and an apatite fission-track age of 5 4 + 7 m.y. for granite porphyry sample PC12 from the Mt. Reed property provide an internal check on the K-Ar age of these bodies. Mineralized and barren quartz latite porphyry near Burwash Creek and mineralized and barren granite porphyry from the Mt. Reed and Mt. Haskin properties yield ages that are identical within the limits of precision of the K-Ar method.  This agrees with the findings of White et.  a l . (1968) that for many British Columbia porphyry deposits, mineralization is an integral feature of a magmatic event.  On radiometric evidence these porphyry  deposits f i t into the paramagmatic class of mineral deposits suggested by White. Biotite K-Ar ages of 71.7 + 2.6 m.y. and 68.3 + 2.7 m.y. obtained from a young phase of the Cassiar intrusions, place an upper limit on the age of the molybdenum mineralization on the Cassiar Molybdenum property.  90.  7.  A 62.0 + 2.2 m.y.  age, determined for a biotite  concentrate from the coarse alaskite phase of the Mt. Leonard Boss, dates the molybdenum mineralization on the Adanac property. 8.  Late Cretaceous and Early Tertiary ages obtained for the Adanac Mo property, Cassiar Molybdenum property, Mt. Haskin Mo property, and Mt. Reed Mo-W  property  and Early Tertiary ages reported for quartz monzonite and pegmatite associated with the Blue Light tungsten property (Wanless et a l . , 1970) indicate that the Early Tertiary metallogenic epoch, documented in central British Columbia and southeastern Alaska, can be extended through northern British Columbia. 9.  Apatite fission-track ages from the Burwash Landing area, Cassiar area and Syenite Range are consistent and in general concordant with K-Ar ages determined on co-genetic biotite.  These results suggest that the  apatite fission-track method is a suitable method for dating late Mesozoic and Cenozoic igneous and metamorphic events in the Burwash Landing area, Cassiar area and Syenite Range. 10.  One sample from a mineralized potassic-zone vein at the Granisle Mine has respectively 3 0 + 4 m.y. 50.-2 + 2.1 m.y. ages.  and  apatite fission-track and biotite K-Ar  Discordant results is attributed to the altered  nature of the apatite.  91.  11.  Apatite fission-track ages from the Copper Mountain intrusions are consistently younger than K-Ar ages on co-genetic biotite.  The fission-track ages are  interpreted to reflect a heating event that i s related to Early to Middle Cretaceous granitic intrusions. Because biotite K-Ar ages are affected only by contact events, and apatite fission-track ages appear to be regionally reset, temperatures below approximately 150°C are suggested for a thermal event of Cretaceous age. 12.  Without additional geologic and geochronologic evidence, apatite fission-track ages from the Copper Mountain area and the Granisle Mine give misleading results with resulting misinterpretation of the thermal history. 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Age determinations and geological studies, K-Ar isotopic ages, Report 7. Geol. Surv. Can. Paper 66-17. 1968. Age determinations and geological studies, K-Ar isotopic ages, Report 8, Geol. Surv. Can. Paper 67-2, Part A. , and Delabio, R.N., 1970. Age determinations and geological studies, K-Ar isotopic ages, Report 9. Geol. Surv. Can. Paper 69-2A.  103.  1972. Age determinations and geological studies, K-Ar isotopic ages, Report 10. Geol. Surv. Can. Paper 71-2. Wheeler, J.O., 1970. Summary and discussion. In Structure of the Southern Canadian Cordillera. Geol. Assoc. Can., Special Paper No. 6, pp. 155-166. Wheeler, J.O., Aitken, J.D., Berry, M.J., Gabrielse, H., Hutchinson, W.W., Jacoby, W.R., Monger, J.W.H., Niblett, E.R., Norris, D.K., Price, R.A., and Stacey, R.A., 1972. The Cordilleran Structural Province. In Variations in Tectonic Styles in Canada (R.A. Price and R.J.W. Douglas (Eds.)), Geol. Assoc. Can., Special Paper 2., pp. 1-82. White, W.H., 1966. Summary of tectonic history of B.C. In Tectonic history and mineral deposits of the western Cordillera. C.I.M.M. Spec. Volume No. 8, pp. 185-189. White, W.H., Erickson, G.P., Northcote, K.E., and Harakal, J.E., 1967. Isotopic dating of the Guichon batholith, B.C. Can. J. Earth Sci., 4, pp. 677-690. White, W.H., Harakal, J.E., and Carter, N.C., 1968. Potassium-argon ages of some ore deposits in British Columbia. Can. Inst. Min. Met. Bull., 61, pp. 1326-1334. White, W.H., Sinclair, A.J., Harakal, J.E.,.and Dawson, K.M., 1970. Potassium-argon ages of Topley Intrusions near Endako, British Columbia. Can. J. Earth Sci., 7, No. 4, pp. 1172-1178. Wilkening, L., Lai, D., and Reid, A.M., 1971. The evolution of the Kapoeta Howardite based on fossil track studies. Earth Planet. Sci. Letters, 10, pp. 334-340. York, D., 1966, Least squares fitting of a straight line. Can. J . Phys., 44, p. 1079. , 1970. Recent developments i n potassium-argon dating. Comments Earth Sci. - Geophysics, 1, No. 2, pp. 47-54. York, D., Macintyre, R.M., and Gittins, 1969. Excess radiogenic A r ^ in cancrinite and sodalite. Earth Planet. Sci. Letters, 7, pp. 25-28. York, D.,,and Farquhar, R.M., 1972. The earth's age and geochronology. Pergamon Press, Toronto, 178 p.  104.  APPENDIX A - DESCRIPTION OF SAMPLES USED FOR K-AR AND FISSION TRACK AGE DETERMINATIONS Burwash Creek, Yukon Territory (Fig. 4-2 & 4-3) PCI Quartz Latite Porphyry Sample is from recent road cut in barren, quartz-feldspar-biotite porphyry located three miles each of the Cork property.  The rock  contains 40% phenocrysts that are 65% plagioclase feldspar (zoned An3QAn3g), 20% quartz, 6% biotite, 3% amphibole and 5% carbonate in a microgranular matrix of plagioclase, quartz and k-feldspar. Accessories are apatite, zircon and limonite after magnetite. Alteration Biotite is generally fresh but some grains show weak chlorite alteration along edges and limonite replacing magnetite inclusions. Amphibole i s pseudomorphicly replaced by tremolite and iron oxide. Carbonate replaces cores of plagioclase phenocrysts and occurs along microfractures. PC2 Quartz Late Porphyry Sample i s from recent cut about 500' east of PCI. The sample i s similar i n texture and mineralogy to PCI, but altered plagioclase phenocrysts have chlorite cores rimmed by carbonate and amphibole i s replaced by carbonate, tremolite and iron oxides. PC3 Quartz Latite Porphyry Sample is from a recent cut near the West Fork of Johnson's Creek in the mineralized zone on the Cork property. Hand specimen contains molybdenite, pyrite and chalcopyrite in quartz veinlets and along "dry" fractures. The rock contains 20% phenocrysts that are 85% plagioclase  105.  (about Ari25)»  quartz "eyes", 3% biotite, and 1% amphibole in a  microgranular matrix of plagioclase, k-feldspar, quartz and biotite. Accessories are iron-oxide, sphene, epidote and apatite. Alteration' Biotite is altered to chlorite in the matrix but the biotite phenocrysts show only weak chlorite alteration along cleavage planes. Amphibole i s altered to carbonate and chlorite. PC4 Quartz Latite Porphyry Sample is from barren quartz-feldspar-biotite porphyry from recent cut on the Cork property. The sample is similar in mineralogy and texture to PCI and PC2 with 1% biotite as phenocrysts altering to chlorite along cleavage planes. PC5 Gabbro Sample i s from barren gabbro along Johnson's Creek. Hypidiomorphic granular textured rock containing plagioclase (60% AngQ), hornblende (18%), orthopyroxene (3% hypersthene), clinopyroxene (13% augitic), magnetite (5%) and apatite (tr). PC6 Gabbro Sample i s from the Cork property 500' south of PC5. Hypidiomorphic granular textured rock containing plagioclase (60%-Ango)» hornblende (20%) , pyroxene (8% mainly augitic), magnetite (5%), and apatite (tr) . Chlorite and carbonate (1%) occurs as alteration along fractures. Ruby Range Batholith, Yukon Territory (Fig. 4-2) PC7 Biotite Granodiorite Medium grained, hypidiomorphic granular textured rock contains 36%  plagioclase  (A1120)  > 38% orthoclase, 19% quartz, 6% biotite and  accessory apatite and sphene. Biotite shows minor alteration to chlorite along cleavage planes and edges. PC8 Biotite - Hornblende Granodiorite Medium grained, hypidiomorphic granular textured rock contains 58% plagioclase (An38), 10% orthoclase, 18% quartz, 8% biotite, 4% hornblende, 2% sphene and accessory apatite and magnetite.  Biotite shows minor  alteration to chlorite along cleavage planes and edges and plagioclase cores show minor alteration to sericite. Mount Haskin, British Columbia (Fig. 4-4) PC9 Granite Porphyry (ref. Gabrielse 1963, p. 94) Mineralized sampleMs from outcrop along southern edge of small "stock" on Mt. Haskin Mo property. The rock contains 60% phenocrysts that are 45% orthoclase, 25% quartz, 22% plagioclase (zoned albite) and 3% biotite in a micro-crystalline groundmass of K-feldspar-plagioclasequartz-biotite.  Apatite, zircon and pyrite occur as accessory minerals,  and the hand specimen i s cut by 1/4" molybdenite bearing quartz vein. Biotite contains inclusions of apatite and zircon and i s altered to chlorite. PC10 Granite Porphyry Sample of barren d r i l l core (hole DM 68-16) is from northern edge of small "stock" on Mt. Haskin Mo property. The rock contains 35% phenocrysts that are 40% orthoclase, 40% quartz, 16% plagioclase (zoned oligoclase), and 4% biotite in a microcrystalline groundmass of K-feldspar-quartzplagioclase. Garnet occurs as an accessory mineral.  A quartz vein and  quartz-carbonate-K-feldspar coatings along hairline fractures compose 20% of the thin section. Biotite phenocrysts are fresh, but a finer, felted secondary biotite, that is associated with fractures, i s altered to chlorite. Mt. Reed, British Columbia (Fig. 4-4) PC11 Granite Porphyry Sample is from a barren "stock" on the Mt. Reed Mo-W  property.  The rock contains 60% phenocrysts that are 70% orthoclase, 20% quartz and 10% albite in a phaneritic groundmass of K-feldspar-albite-quartzbiotite.  Sphene, apatite and magnetite occur as accessory minerals.  Biotite shows 5% alteration to chlorite along cleavage planes and edges. PC12 Granite Porphyry Sample i s from the central mineralized part of the small "stock" on the Mt. Reed Mo-W  property.  The specimen contains 80% phenocrysts  that are 50% orthoclase, 25% quartz, 20% albite and 5% biotite in a microcystalline groundmass of quartz-K-feldspar-plagioclase-biotite. Apatite, sphene, and magnetite occur as accessory minerals.  Biotite-  shows minor chlorite alteration along edges. Cassiar Area, British Columbia (Fig. 4-5) (young phase of Cassiar Intrusions that cuts Cassiar Batholith) PC13 Quartz Monzonite Medium grained, hypidiomorphic granular rock contains 32% plagioclase (An3Q, 30% K-feldspar-(microperthite), 30% quartz, and 8% biotite. sphene and magnetite occur as accessory minerals.  Apatite  Biotite i s 10% altered  108.  to green biotite and chlorite. PC14 Quartz Monzonite Medium grained, hypidiomorphic granular rock contains 35% quartz, 30% plagioclase (An3 ), and 24% K-feldspar (microperthite). Sphene (1%), 0  apatite (1/2%), zircon (tr) and magnetite (tr) occur as accessory minerals.  Biotite is 10% altered to chlorite along cleavage planes and  edges. Adera Claims - Adanac Mo Property Atlin Area, British Columbia (Fig. 4-5) PC15 Coarse Alaskite (ref. Sutherland Brown 1969, pp. 29-35 Coarse grained, hypidiomorphic granular rock contains 30% K-feldspar (perthite), 38% quartz, 27% plagioclase (zoned oligoclase), 2% carbonate, 1% biotite and 1% allamite.  Molybdenite, pyrite, zircon, sphene and  apatite occur as accessory minerals.  Biotite is 20% altered to chlorite.  Syenite Range, Yukon Territory (Fig. 4-1) PC16 Quartz Monzonite Coarse-grained, hypidiomorphic granular rock contains up to 3/4" crystals of K-feldspar (40%) in finer-grained, phaneritic quartz (15%), plagioclase (An28 30%), hornblende (7%), biotite (5%), sphene (1%), -  apatite (1%) and accessory zircon, fluorite, magnetite and allanite. Alteration Biotite shows minor chlorite alteration and contains inclusions of apatite, sphene, quartz and other accessories. Hornblende shows stronger alteration to chlorite, carbonate, epidote and biotite.  PC17 Quartz Monzonite Although this specimen was obtained from the margin of a small stock, mapped by Bostock "(1948) as zoned from a granite core (PC16) to a syenite outer rim, the specimen i s texturally and mineralogically similar to sample PC16.  Samples PC16 and PC17 were collected by K.  Dawson and C. Godwin. Copper Mountain, B.C. (Fig. 4-7) KA1 to KA11 Samples KA1 to KA11 inclusive were obtained from Dr. V. Preto. Specimens and K-Ar ages obtained on biotite concentrates are described by Preto et a l . (1971). Granisle, Central British Columbia (Fig. 4-6) NC-69-8 Sulfide Rich Vein This sample is from a biotite (25 to 50% altered to chl.)-quartzfeldspar-apatite-bornite-chalcopyrite vein that was exposed in the Granisle open-pit in 1969.  N. Carter collected the sample and has obtained a K-Ar  biotite age of 50.2+2.1 m.y. for this sample (N. Carter personal communication). Brenda Mines, Southern British Columbia JH5-68 Quartz Diorite (ref. Oriel 1972) This sample i s from the speckled quartz diorite phase of the Brenda stock.  Dr. W.H. White provided a 90% sphene concentrate from this sample.  Concordant ages of 174 + 7 m.y. on biotite and 177 + 7 m.y. on hornblende have been obtained for this sample (J. Harakal personal communication).  110.  APPENDIX B - POTASSIUM-ARGON METHOD B.l  PROCEDURE Biotite and hornblende potassium-argon ages were determined i n  laboratories of the Department of Geology, University of British Columbia, using procedures and equipment previously described (White et a l . 1967, p. 683; Northcote 1969, pp. 61-65).  In addition to the  normal procedure, the sample and entire fusion system were baked at 130°C for 16 hours which effectively eliminates atmospheric argon contamination in the fusion system (Roddick and Farrar 1971). Analytical data and K-Ar isotopic ages are given in Table 2-1. B.2 PRECISION AND ACCURACY The precision and accuracy of the potassium-argon age determinations must be continually monitored to determine r e l i a b i l i t y of potassium-argon model ages.  Interlaboratory standard mineral and rock samples are  analyzed i n the U.B.C. potassium-argon laboratory to establish the accuracy of the equipment and replicate analyses of minerals are used to determine the precision of the equipment (see White et a l . 1967, and Northcote, 1969).  J. Harakal runs periodic checks on the Ar^°/Ar 6 ratio 3  of atmospheric argon and on the argon isotope ratios in the spike system as measured on the U.B.C. MS-10 mass spectrometer. For samples containing less than 50% atmospheric argon contamination, U.B.C. results are internally consistent within 1% and a limit of error in an age determination (accuracy) is within 3% of the calculated age (J. Harakal, personal comm. June 1972).  rOO  90  c o 08O  s  "I IO  Figure (B-l).  20  30 40 Atmospheric  50. 60 70 correction ( ° / o )  SO  90  (OO  Estimated p r e c i s i o n f o r determining the ^°Ar/*°K r a t i o as afunction of the atmospheric correction (from Damon, 1968).  112.  B.3 ATMOSPHERIC CONTAMINATION The atmospheric argon correction often introduces the largest error in the precision of the calculated age.  The percentage standard deviation  in a potassium-argon age as a function of the fraction of radiometric argon is shown in Figure B-l.  This diagram demonstrates the effect of  subtracting a large percentage of atmospheric argon from the total A r ^ 4  measured. Error increases rapidly once atmospheric contamination reaches about 70% and therefore, the baking procedure described above should be used even i f samples are not likely to be suitable for isochron determinations. B.4 APPLICATION OF A r  4 0  (RAD.) VS %K ISOCHRONS TO PUBLISHED DATA  K-Ar data (Table B-2) from the Topley Intrusions and (Table B-l) from the Guichon Batholith was evaluated using Ar*-* radiogenic vs %K 4  diagrams.  Plotting of A r / A r ^ vs K /Ar ^ diagrams is not attempted 40  3  40  3  because the fusion system had not been baked prior to each analysis. B.4.1  Guichon Batholith  Figure B-2a contains a plot of A r samples from the Guichon Batholith.  4 0  rad. vs %K data for 18 biotite  A mean of the individual K-Ar ages  of 199 + 4 is in good agreement with the isochron age of 196 + 5 m.y. and the intercept near zero suggests that the use of the present atmospheric Ar^O/Ar ^ ratio in the correction for i n i t i a l argon is reasonable. Figure 3  B-2b i s a plot of Ar ^ rad. vs %K data for 6 biotite samples from the 4  Witches Brook phase of the Guichon Batholith.  The isochron age of 189 +  9 m.y. for the Witches Brook phase i s consistent with the composite isochron age and with the mean biotite K-Ar age of 199 + 5 m.y. for the Witches Brook  TABLE B-l  Potassium-argon data f o r Guiohon Creek B a t h o l i t h (Northcote, e t a l . 19671 Blanchflower, 1971).  Sample No. (Isochron No.) K64-102  (1)  19691 White  40  Rook Unit . Witches Brook.  Mineral analyzed* Biotite  4o Ar*» A r * * » Apparent trr,— (10~ co A g e * * * * Total A r STP/gm) (m.y.) 5  K±s(J*)*» .  4.91 ±0.03 4.91 ±0.03  u  .  0.87 0.91  • 4.055 4.077  198±8 199+8  K64-105-1 (2)  Witches Brook  Biotite  6.53 ±0.04  0.90  5.442  198±S  K63-171  (3)  Witches Brook  Biotite  6.59 +0.06  0.75  5.263  192±8  K64-203  (4)  Witches Brook  Biotite  4.42 ±0.02 4.42 ±0.02  0.64  0.79  3.759 3.750  203±8 203±8  K64-17  (5)  Witches Brook  Biotite  3.59 +0.02  0.74  3.093  206±8  K63-222  (6)  Wltohes Brook  Biotite  7.16 +0.01  0.87  5.903  198±8  K63-223  (7)  Guichon  Biotite  5.77 ±0.02  0.87  4.689  195+8  GD12  (8)  Guichon  Biotite Hb.(alt.)  5.56 +0.01 0.424±0.004  0.83 0.60  4.663 0.3629  201+8 205±8  (9)  Chataway  Biotite .  5.24  +0.04  0.77  4.358  199±8  K63-220  (10)  Chataway-Leroy  Biotite  5.20 +0.02 5.20 ±0.02  0.92 0.30  4.325 5.390  199±8 201±10  K63-37  (11)  Leroy  Biotite  6.42 ±0.03 6.42 ±0.03  0.78 0.85  5.385 3.795  201±8 202±8  K64-101  (12)  Leroy  Biotite  5.16 +0.05  0.90  4.295  199+8  (13)  Hybrid  Biotite  4.49 ±0.02 4.49 ±0.02  0.91 0.52  3.716 5.776  198±8 206±8  K64-156a (14)  Hybrid  Biotite  6.73 ±0.01  0.93  5.659  198±8  K64-98-1 (15)  Gump Lake  Biotite  5.95 +0.01 5.95 ±0.01  0.37 0.91  4.817 4.919  194+10 198+8  K63-I87  (16)  Bethsalda  Biotite  4.48 ±0.02 4.48 ±0.02  0.80 0.88  3.573 3.648  192+8 195±8  K63-231  (17)  Bethsalda  Biotite  5.86 +0.07  0.86  5.044  205+8  K63-240  199+8  K64-ll6a  K63-13  (18)  Brecola  Biotite  5.60 ±0.01  0.84  4.643  K63-II5  (19)  Bethlehem  Biotite  5.90 ±0.07  0.90  4.307  195+8  GD-10  (20)  P3 Porphyry  Hb.(alt.)  0.292±0.002  0.53  0.2432  199+8  GD-102  (21)  P3 Porphyry  Hb.(alt.)  0.140±0.001 0.140±0.001  0.24 0.39  0.09845 0.09879  170±12 171±12  Bethlehem  Biotite  1.87 ±0.01 1.87 ±0.01  O.83 0.27  1.644 1.634  210+12 212±12  K64-186a (22) GD-5  (23)  D a c l t e Porphyry B i o t i t e  5.56 ±0.03  0.50  4.717  203+8  GD-lla  (24)  Bethlehem  Hb.(alt.)  o.l6i±o.oo  0.44  O.1305  194±10  GD-4  (25)  Guichon  Hb.(alt.)  O.I69+.O.OOI  0.60  0.1474  208+8  K63-114  (26)  V o l c a n i c dike  Biotite  6.99 ±0.02 6.99 A0.02  0.88 O.83  1.389 1.433  49±3 51±3  • H b . ( a l t . ) = a l t e r e d hornblende • * Potassium analyses by Wm. H. White, J . E . Harakal and others using KY and KY-3 flame photometers, s-standard d e v i a t i o n o f quadruplicate a n a l y s e s . • • • Argon analyses by J . E . Harakal and others u s i n g MS-10 mass spectrometer. » • « * Constants used i n model age c a l c u l a t i o n s 1 iC = 0.585 x l 0 - 1 0 y - l , a = It.72 x l 0 l ° y _  40KA = 1.181 X 10-*.  '  p  •"  n  114.  Potassium-argon data for the Topley Intrusions (from White et a l t , 19?0, and White et a l . , 1968).  TABLE B-Z  40^. Apparent (10"-" 00 Age**« (m.y.) Total ^ ° A r STP/gm)  Sanrple No, f T or»r« h r n n  No.  Rook unit  Mineral analyzed  Type  *°Ar*  K±s(#)*  T66-15 (1)  Endako  Qtz. Monzonite  Biotite  5.6710.07  0.82  3.328  14316  T66-14 (2)  Endako  Qtz. Monzonite  Biotite  6.4610.03  0.85  3.748  14115  T65-3  Endako  Qtz. Monzonite  Biotite  5.8110.04  0.70  3.318  140t6  (3)  T66-21 (4)  Nlthl  Qtz. Monzonite  Biotite  5.13±0.04  0.89  2.974  I4lt6  T66-20 (5)  Nithl  Qtz. Monzonite  Biotite  5.80±0.03  0.78  3.281  13815  T66-25 (6)  Glenannon  Qtz. Monzonite  Biotite  4.58+.0.03  0.75  2.639  140±6  T67-29 (7)  Glenannon  Qtz. Monzonite  Biotite  4.3910.02 4.3910.02  O.65 0.87  2.419 2.423  134i5 13515  T66-10 (8)  Tatln  Qtz. Monzonite  Biotite  5.6910.04  0.73  3.327  I42t6  T66-27 (9)  Tatln  Qtz. Monzonite  Biotite  6.59±0.02  O.65  3.687  13615  T66-18 (10) Casey  Qtz. Monzonite  Biotite  5.*>6±o.03  0.80  3.118  139±5  T66-26 (11) Casey  Qtz. Monzonite  Biotite  6.34±0.06  0.68..  3.558  137t6  T67-3I (12) Francois  Granite  Biotite  6.0610.03  0.80  3.408  137±5 137+6  T67-3O (13) Francois  Qtz. Monzonite  Biotite  5.3l±o.05  0.76  2.993  T66-16 (1*) Stellako  Qtz. Monzonite  Biotite  4.9910.03  0.65  2.804  I37t5  (15) Stellako  Qtz. Monzonite  Biotite  3.70±0.03  0.57  2.063  136t5  T66-11 116) Triangle  Qtz. Monzonite  Biotite  6.2110.01 6.2210.01  0.85 0:78  3.393 3.403  13315 133+5  T65-4  Qtz. Monzonite  Biotite  7;054±o,026  0.85  4.099  14115  T66-23 (18) Casey  Qtz. -Biotite dike  Biotite  ?.03±o.o6  0.58  4.012  13916  T65-6  (19)  Qtz. Monzonite  Biotite  6.90310.025  0.88  3.961  14015  T66-12 (20)  Qtz. Monzonite  Biotite  6.94+.0.03  0.82  4.064  14215  T66-13 (21)  Bio.  Biotite  6.5310.02  0.74  3.808  14215  T68-33 (22) Simon Bay  Diorite  Hb.  1.2110.01  0.62  0.7745  155+8  T68-33 (23) Simon Bay  Diorite  Biotite  3.7210.07  0.86  2.221  14518  T68-33 (24) Simon Bay  Diorite  Plagioclase  1.78+0.01  0.70  1.007  13816  T66-22 [25) Simon Bay  Qtz. Monzonite  Biotite  6.7610.105 6.7610.105  0.78 0.85  4.313 4.317  155+6 155±6  T66-28 [26) Late dike  Daclte  Biotite  6.25+0.04 6.2510.04  0.58 0.65  1.264 1.277  50+2 51±2  T65-I  Qtz. Monzonite  Biotite  5.23+0.02 5.23+0.02  0.58 0.40  2.424 2.385  114±4 11214  T65-2  (17) Casey  [27) Praaer  Kith  qtz.-  rnoly vein  *  Potassium analyses by Wm. H. White, T. Richards, and I. Semple using KY photometers, s.-standard deviation of quadruplicate analyses.  **  Argon analyses by J , E . Harakal using M3-10 mass spectrometer.  •»* constants used i n model age calculations. *°K/fc - 1.181 x 10-4.  10  1  and KI-3 flame  10  -1  /)_- O..585 1 IO" /" , J V - 4.72 x 10" y , e J'fi  115.  Regression Results Intercept  Slope  0.08321 ±0.2 236 0.8176*0.02321 .Guichon 0.01572*0.1615 0.5895+0.04017 T68-33 •0.1293* 0.1670 0.5930*0.01645 Topley  Regression Intercept 0.2579*0.3592  8  3  Results Slope 0.7853*0.03714  3  \  P-< EH CO  O o o  2  % 10  2.0  4.0  5.0  6.0  7.0  a. Isochron p l o t s f o r data from the Guichon B a t h o l i t h , • Topley Intrusions, and sample T 6 8 - 3 3 from the Topley Intrusions. b. Isochron p l o t f o r the Witches Brook Phase of the Guichon B a t h o l i t h .  116.  phase of the batholith . . B.4.2 Topley Intrusions K-Ar data for the Topley Intrusions near Endako, British Columbia has been interpreted by White et a l . (1970) to indicate either one protracted perhaps intermittent magmatic event culminating in early Late Jurassic or three separate and unrelated events.  Isochron plots of the  Topley data were attempted in order to evaluate the two alternatives. The Triangle, Stellako, Francois, Casey, Tatin, Glenannon, Nithi and Endako phases of the Topley Intrusions have biotite K-Ar ages ranging from 133 m.y. to 143 m.y. and a mean age of 138 + 3 m.y.  The Simon Bay  phase has a 155 m.y. age for biotite from sample T66-22 and from sample T68-33 discordant ages of 155, 145 and 138 m.y.  The Topley isochron  shown in Figure B-2a is from data (Table B-2) used to obtain the 138 + 3 m.y. mean age and the isochron age of 144 + 4 m.y. i s consistent with the mean age.  Hornblende, biotite and plagioclase data for sample T68-33  plots on an isochron that is parallel to the Topley isochron and has an isochron age of 143 + 10 m.y. For both the Topley isochron and sample T68-33 isochron, the isochron age and mean age of the conventional K-Ar determinations are consistent. Since the isochron and mean ages overlap, the isochron plots cannot be used to distinguish between continuous igneous activity or an intrusive pulse model. B.4.3  Summary  Application of A r ^ (rad) vs %K isochron plots to data from the 4  Topley Intrusions and Guichon Batholith supports the conventional age  117.  determinations.  In both cases the mean age of the conventional  determinations i s consistent with the isochron age.  For both the Topley  Intrusions and the Guichon Batholith the i n i t i a l argon ratio i s essentially the same as the present-day value ( A r / A r ^ = 295.5). 4o  3  118.  APPENDIX C - FISSION TRACK DATING C.l  INTRODUCTION Fission track dating provides a method for using normal laboratory  equipment for determining the age of nonconductors.  Once polished  section mounts are obtained, track counting and age determination takes only a few hours for materials with suitable age to uranium ratios. Unfortunately, i n this study pre-counting steps consumed a majority of the time. C.2  PROCEDURE Fission track dating involves: (a)  determining the spontaneous fission track density (p s) on an etched interior surface of a mineral or other nonconductor,  (b)  using the calculated value for fission decay of U  (c)  2 3 8  ( Ap), and  determining the U  2 3 8  content.  Step 1. MINERAL SEPARATION Concentrates of the mineral to be used for fission track dating are obtained using standard mineral separation methods (see flow sheet Fig. C-l and Table C-l).  Care must be taken during mineral separation and  subsequent steps to ensure that tracks are not annealed by heating. Step 2. DIVISION OF SAMPLE The mineral concentrates (65-95%) pure are split to obtain two portions.  One portion is*_used to obtain the spontaneous (natural) track  density, and this sample is saved t i l l Step 6.  119.  Figure C-1  iiHimiiiiim  Flowsheet  separating  v  Jaw Crusher  _____ I  Gyratory  for mineral  *  Crusher  Cone  Crushers  Primary  — »  Secondary  J  I  Pulverizer  mesh Screens  I -28+35 4- high surface | - 3 5 + 4 8 - — area minerals -48 + 65-  > 28 mesh  __r  |Save -65~  J  Dryer • ur 50°c  Water  |\~/Bromoform  i  V X j±  -*  Dryer <50°c  Remove Magnetite with Hand Magnet  Magnetic Cleaner -  c^C^n „ . Acetone S.G.>2.8^Aceton_  co  Save? Feldspar, Quartz, etc.  I N - / ' Metheline N  H' S-G.>3.2 Magnetite, Zircon, Sphene, Epidote, etc. Apatite, Biotite, Hornblende Acetone Wash * u CJ to  Acetone Wash  I See Table C-1  Iodide  120.  TABLE C-l  FRANTZ SEPARATION SETTINGS FOR DESIRED MINERAL SEPARATION (ROSENBLUM, 1958, p. 171)  Mineral  Current amps  Fraction used  Magnetite Ilmenite Pyrrhotite  less 0.2  heavies  Hornblende Pyroxene  0.2-0.5  Cross t i l t  Flow t i l t  II  Biotite  lights  Sphene  0.6-1.0  Zircon Molybdenite Pyrite  greater 1.2  heavies  n  Fluorite Apatite  lights ti  Step 3.  PREPARATION OF SAMPLES FOR IRRADIATION  The second portion obtained from the split is placed i n a porcelain crucible.  This portion of each sample was annealed in an  electric oven for 24 hours at 650 + 25°C. Naeser (1967 p. 54) determined that annealing for one hour at 350°C and 625°C for apatite and sphene respectively w i l l cause 100% track destruction. Therefore i t i s assumed that a l l spontaneous tracks were destroyed i n the annealing procedure used by the writer. Annealed apatite and sphene samples weighing between 0.01 and 0.2 gm. (minimum of 100 grains but generally several hundred) were next wrapped in high purity aluminum f o i l (provided by Mr. F.T. Murphy of AECL). Glass standards* weighing between 0.1 and 0.2 gm. (1mm x 5mm. x 5mm) * Standard glass used to calibrate UBC reactor run 1 was provided by Dr. Charles Naeser of the U.S. Geological Survey.  were prepared i n two d i f f e r e n t ways. foil.  A second standard was  One standard was  i n aluminum  cleaned i n a sequence of reagent grade  s o l u t i o n s , including 50% ammonium hydroxide, acetone benzene and rinsed i n deionized water, and then wrapped i n a p l a s t i c detector which has been cleaned i n reagent grade n i t r i c a c i d , and rinsed i n deionized water (Lahoud et a l . , 1966).  The sample with the p l a s t i c detector was  also  wrapped i n aluminum f o i l . Step 4.  SAMPLE IRRADIATION  Wrapped mineral samples and glass standards' were placed i n an aluminum capsule.  The capsule was sealed and i r r a d i a t e d by Atomic  Energy of Canada Limited i n the self-serve unit of a NTX Reactor.  A  flux of 1.2 x l O ^ n v t was requested and a cobalt tag included i n the run was 10  15  calibrated by the laboratory to have received a f l u x of 1.05  nvt (1.35 x 10 Step 5.  12  n/cm  2  x  /sec for 13 minutes).  FLUX DETERMINATION  Mr. F.T. Murphy of AECL (personal communication) suggested that the flux determined using the cobalt tag should be within 5% of the actual value, but Dr. C.W.  Naeser (personal communication) has found that  standards containing known uranium contents provided a more accurate determination. for  Three separate determinations provide independent support  a flux value of 1.31 (1)  x l O ^ n v t + 5%.  These determinations include:  count of induced tracks produced i n standard glass included i n the reactor run,  (2)  comparison of the r a t i o of tracks/area i n the standard glass included i n the U.B.C. reactor run with the r a t i o of tracks/area i n a piece of the same.  122.  standard glass included in the Dartmouth reactor run 1 (flux of 1.A6 x lO-^nvt was calculated by Dr. C.W. Naeser for the Dartmouth reactor run) and (3)  count of induced tracks/area produced in standard apatite Mc/G-1 that has a mean fission track apatite age of 120 m.y. and a concordant biotite K-Ar age of 120 m.y. (Christopher 1968).  Step 6. MOUNTING AND POLISHING In order to handle 28-100 mesh mineral grains during fission track analysis, i t is necessary for them to be mounted. The sample preparation procedure described by Naeser (1967, pp. 75-76 and 1967b, p. 1524) was used as a guide in preparing mounts. At least 100 grains from each mineral concentrate are placed on a teflon sheet.  The grains are then covered with a few drops of freshly  mixed epoxy resin, and a labelled glass microscope slide is placed on top of the resin.  The thickness of the epoxy wafer i s gauged by placing a  0.1 to 0.5mm spacer at each end of the slide.  Placing an iron weight on  each mount eliminates bubbles from the mounts and produces an epoxy wafer of uniform thickness.  After allowing the resin to dry for about 12 hours,  the mounted sections are removed from the teflon sheet. The mineral grains in the epoxy wafer must be polished to expose a fresh smooth interior surface.  The grinding and polishing employed standard  manual methods. An attempt was made to produce identical mounts of natural and irradiated mineral samples.  Lack of a mechanical method for producing  polished thin sections is considered to be one of the major problems in  123.  application of the fission track method. After spending over two hours (average) per polished section, variability in sections is considered to be one of the major sources of error. The glass standard is mounted and polished in the same manner as the mineral grains. Other laboratories (Rensselaer and General Electric) have used fracturing methods for preparing the glass standard. Step 7. ETCHING Two slides of each mineral concentrate must be used to obtain an age. One slide is made from the natural mineral concentrate (Plates 1 and 3). A second slide is made from the annealed and irradiated portion (Plates 2 and 4). The two slides are placed back to back and dipped in an appropriate etchant (see Tables C-2 and C-3). For minerals with variable composition (e.g. apatite, epidote or micas), the etching has to be done in steps and the tracks examined at intervals to obtain the proper etch time.  *  The track density in the glass before irradiation is essentially zero, and therefore only the irradiated glass standard is mounted, polished to expose an interior surface and etched (Plates 5 and 6). A Makrofol KG plastic detector (polycarbonate) was also used to detect induced fission in the glass. Unfortunately the plastic detector was over etched. Step 8. COUNTING TRACKS Track densities for etched apatite and sphene samples were determined by observation using a polarized-light-microscope at about 1500x (magnification obtained from Zeiss lOOx oil immersion objective, 12.5x eyepiece and 1.25x  TABLE C-3.  ETCHING CONDITIONS FOR FISSION-TRACK COUNTING.  Material  Etchant  Temp.  Apatite  HN0 (65%)  25°C  Zircon (prism face)  NaOH (100N)  3  220°C  Time  Reference  Comments  15 sec. Reimer et a l . 1970 9 hrs.  Glass (micros- HF (48%) cope slide)  25°C  5 sec.  Muscovite (001) HF (48%)  25°C  15 min.  25°C  14 min.  6:3:2:1 H 0:HC1:HN0 : HF  20°C  1- 5 min. Naeser and McKee, 1970  Muscovite  HF (48%)  20°C  7-9 min.  Zircon  100M NaOH  220°C  4- 6 hrs.  Apatite  HNO3 (5%)  20°C  25 sec.  Apatite  HNO3  23°C  5- 30 sec.Fleischer and Price,  Glass  HF (48%)  23°C  Fluorite  H S0 (98%)  23°C  Makrofol (KG)  NaOH 6N  23°C  Apatite  HNO3 (70%)  20°C  Sphene  HCl (37%)  90°C  15-60 min.  Muscovite  HF (48%)  20°C  5-15 min.  Epidote  NaOH 50N  140°C  1/2-2 hr.Naeser, Engels and Dodge, 1970  Allanite  NaOH 50N  140°C  2-60 min.  Garnet  50N NaOH  140°C  30-120 min.  Glass  24% HBF4,  25°C  35-50 min.  Sphene  1HF, 2HN0 , 3  3HC1, 6H2O  Sphene  2  2  3  4  5% HNO3,  0.5% CH C0 H 3  1964d 5 sec. 10 min. " 2- 2-1/2 ' Lahoud et a l . , 1966 hrs. 5-20 sec.Naeser and Dodge, 1969, unpublished  11  "  "  Macdougall, 1971  2  Pyroxene  6 g. NaOH, 4 co H2O  boiling 50 min. point  Plagioclase  6 g. NaOH, 8 co H 0  boiling 12 min. point  2  "  Wilkening et a l . , 1971  compares other etchants  125.  setting on an optivar magnification changer).  Track densities for  etched glass standards were determined by observation using a reflectedlight microscope at about lOOOx (magnification obtained from a Zeiss 40x objective, 12.5x eyepiece and 2.Ox setting on an optivar magnification changer).  Tracks are counted in the field of view  covered by a square reticle (Plate 7). The number of fields counted varied with the track density. Since the counting error decreases with increase i n the number of tracks counted, a minimum of 400 counts i s desirable.  The standard deviation of the track counts i s taken as the  square root of the number of tracks counted (Naeser 1967b). This formula yields a counting error of + 5% for 400 counts.  TABLE C-2  Material  ETCHING TECHNIQUES USED FOR MATERIALS STUDIED  Etchant  Etch Time  Temp.  Apatite  65-70%  5-30 sec.  23°C  Glass slide (standard)  48% HF  5 sec.  23°C  Sphene  6:3:2:1 H20:HCL: HN0 :HF  1-5 min.  20°C  Zircon  100M. NaOH  4-6 hrs.  220°C  Makrofol (K6)  6N NaOH  2-2-1/2 hr. 23°C  Reference Fleischer and Price, 1964d  Comments Time varies with composition  Naeser et a l . 1970  3  Naeser and McKee, 1970 Lahoud et a l . 1966  Step 9. URANIUM DETERMINATION By using a ratio of spontaneous tracks to induced tracks, the  determination of absolute uranium content can be bypassed i n the age calculation.  Lahoud et a l . (1966) suggest that the fission-track method  is 10,000x more sensitive than other analytical methods of determining uranium content.  In theory, i t i s possible to determine concentrations  as low as 10~5ppb.  The only limitation on the sensitivity i s the effect  of extremely large neutron doses on the sample and the availability of standards for determining the flux. In order to calculate the uranium concentration in a mineral phase, i t i s necessary to know the induced track density and the neutron dose which produced the tracks. The formula i s (Naeser 1967a): C(ppm U where  238  ) =  F p / $ N a ±  IR  y  238 (atomic weight of  Q  TJ  2 3 8  )  x No. atoms in  mineral formula x 10^  F  molecular weight of mineral pi =  induced track density:  I =  U  a =  thermal neutron cross section for fission of U  235  /U  2 3 5  238  , (7.26 x IO" ); 3  (5.83 x 10" cm ); 22  2  3  N  v  =  number of atoms per cm  of sample;  R  Q  =  average fission fragment range (either 8 x 10~  4  i f new surface i s exposed and etched after irradiation, or 4 x I O  -4  cm i f an old surface i s  used. By substituting values for constants, the equation reduces to: C =  3.61 x 1 0  10 P  i  for apatite when F = 9.80 x 10 and 6  N  v  = 0.8010 x I O  atoms/cc  23  and to: C =  3.33 x 1 0  10 P  i  for sphene when F = 9.71 x 10 and 6  N  v  =  .8603 x I O  23  atoms/cc  128.  Plate 1. Microphotograph showing spontaneous (natural) fissiontracks in standard apatite sample Me/G-1. Apatite from this sample has a spontaneous track density of 8.73 + 5  2  1.12 x 10 tracks/cm  and a uranium content of 15.5 +  1.9 ppm. Scale 1 inch = 22 microns Plate 2. Microphotograph showing induced tracks in standard apatite Me/G-1. Annealed apatite grains were exposed to a thermal neutron flux of 1.535 x lO-^. The induced track density produced was about 6.96 x 10^ tracks/cm . 2  Scale 1 inch =  22 microns.  Plate 3. Microphotograph showing spontaneous (natural) fission-tracks in sphene sample JH5. problems  Cracks in sphene grains cause counting  but can generally be distinguished from tracks of  uniform size and characteristic shape.  Scale 1 inch = 15 microns,  Plate 4. Microphotograph showing faint induced fission-tracks in sphene sample JH5.  Lines which cross entire plate are scratches  produced during polishing.  Scale 1 inch = 15 microns.  .130.  Plate 5.  Microphotograph showing induced fission-tracks produced in standard glass used to calibrate U.B.C. reactor run. Glass contains 0.4 ppm uranium and was radiated to a flux of 1.31 x 10  Plate 6.  15  nvt.  Scale 1 inch = 22 microns.  Microphotograph showing induced fission-tracks produced in standard glass used to calibrate a reactor run. Glass contains 0.44 ppm uranium and was irradiated to a flux of 8 x 10  16  nvt (flux determined by S. Barr). Scale 1 inch = 22  microns.  Plate 7.  Microphotograph showing central part of a reticle used for measuring area from which track count was obtained. Scale 1 inch = 15 microns.  132.  APPENDIX D TABLE OF PUBLISHED K-Ar AGES REVIEWED FOR THIS REPORT Published K-Ar ages referred to In this report.  TABLE D-l Report No.  Reference Number and Mineral Dated  Age in m.y.  Rook Type  Unit  Location  Referenoe  CASSIAR BATHOLITH - MEAN AGE 102 ± 3 m.y. 1  AK50  Bio  101  • Quartz monzonite  Cassiar Batholith  , 60°04'N. 130°29'W.  Baadsgaard, et a l . . 1961  2  GSC60-28 Bio  98  Blotltegranodlorlte  Batholith  32«N. 131 °29*W.  GSC Paper 6 l - 1 7  3  GSC67-12  105±5  Granltlo gneiss  margin of Cassiar Batholith  6o°00'N. 130°44'W.  GSC Paper 69-2A, p. 9-10  4 GSC67-15 Bio  105*5  Quartz monzonite  Cassiar Batholith  58°49'N. 129°52'W.  GSC Paper 69-2A, p. 11  5 GSC70-35  102t5  Quartz monzonite  Cassiar . 58°42.5'N. Batholith 128°43.5'W.  Muso  Bio  LATE CRETACEOUS AGES  1  p. 17  GSC Paper 71-2, pp. 21-22  WEST OF CASSIAR BATHOLITH  6  GSC67-14  Bio  78±4  Granite  Parallel Creek Batholith  59°13.5'N. 130°23.5'W.  GSC Paper 69-2A, p. 1 0  7  GSC66-1  Hb  79±11  Granite  Glundebery Batholith  59°14'N. 130°49'S.  GSC Paper  8  GSC70-4  Hb  7^+4  Granite  Glundebery Batholith  60°12'N. 131°06«W.  GSC Paper 7 1 - 2 , pp. 7 - 8  71  Quartz monzonite  unnamed  GSC Paper 61-17, P. 1 5 58°53 49"N. 130 01'28"W.  98±5  Leuooquartz monzonite  Seagull Batholith  GSC Paper 7 1 - 2 , p. 3 1 60°02'32"N. 131°10 11"W.  Leueoquartz monzonite  Seagull Batholith  60°04.5'N. 131°09'W.  9 GSC60-25 10  Bio  GSC70-49 Bio (replaces GSC59-14)  11 GSC70-50  Bio  97±5 92±4  67-2A,  p.  1 1  ,  6  ,  GSC Paper  71-2,  pp.  32-33  EARLY TERTIARY AGES - WEST OF CASSIAR BATHOLITH 12  13 14  GSC67-9  GSC67-IO  G S C 7 0 - 1 9  Hb  Bio Bio  48±4 46t2  Quartz diorite  unnamed  59°23'45"N. GSC Paper 69-2A, pp. 8-9 ^l^O'SO"*.  58*18  Quartz diorite  Mount McMaster Stock  59°22'N. 0 133 12'W.  GSC Paper 71-2, P. 14  EARLY TERTIARY AGES - BODY INTRUDES CASSIAR BATHOLITH 15 G S C 6 7 - 1  Muso  58±3  Quartz monzonite  unnamed stook?  59°39'N. 130°20.5'W.  GSC Paper 69-2A, p. 6  16  Muso  53±3  Pegmatite  •  59°39'N. 130 27.5*W.  GSC Paper 69-2A, p. 6  GSC67-2  6  EARLY  17  GSC62-74  Muso  * See referenoe.  57  TERTIARY ACE - EAST OP CASSIAR BATHOLITH GnelBS  Horse Ranch 5 9 ° 3 0 , 4 0 " N . G8C Paper 63-17, p. Group 128°55'45"W.  48  133.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Beport No.  Reference Number and Mineral Dated  Age In m.y.  Hook Type  Unit  Referenoe  Location  NOME LAKE AND SIMPSON PEAK BATHOLITHS, NORTHERN B.C. 18 19  CSC67-3 GSC67-4  Hb Bio  20 21  GSC67-5 GSC67-6  Hb Bio  ,181±14 . Quartz 165±8 monzonite  Simpson Peak Batholith  59°44'N. 131026*45"W.  GSC Paper 69-2A , pp. 6-7  Quartz monzonite  Nome Lake Batholith  130 53.5'W.  59°37'N. 6  GSC Paper 69-2A . P. 7  183±9 183±8  PLATE CHEEK STOCK, NORTHERN B.C. 22  GSC70-23  Hb  184*10  Quartz diorite  Plate Creek59°53'N. Stock 130°45.5'W.  GSC Paper 71-2, p. 16  23  GSC67-11  Hb  159±10  Quartz diorite  Plate Creek Stook  GSC Paper 69-2A . P. 9  24  GSC70-24  Bio  87+4  Quartz monzonite  Kllnket Batholith  59°28'N. 131°13'W.  GSC Paper 71-2, pp. 16-17  25  GSC67-13  Bio  92*5  Granite  Tuya Batholith  59°04.3'N. 130°43'W.  GSC Paper 69-2A  p. 10  6  GSC67-14  Bio  78*4  Granite  Parallel Creek Batholith  59°13.5'N. 130°23.5'W.  GSC Paper 69-2A  p. 10  59°52'30"W. 6 130 45'W.  PARALLEL CREEK, KLINKET AND TUYA BATHOLITHS, NORTHERN B.C.  CHRISTMAS CHEEK BATHOLITH, NORTHERN B.C. 26  GSC70-20  Hb  177±9  Quartz diorite  Christmas Creek Batholith  59°18'N. 131°40.5'W.  GSC Paper 71-2, P. 15  27 28  GSC67-7 GSC67-8  Hb Bio  128*6 56*3  Quartz diorite  Christmas Creek Batholith  59°22'30"N.  GSC Paper 69-2A, PP. 7-8  29 30  GSC66-2 GSC66-3  Hb Bio  146*17 73+5  Quartz diorite  Christmas Creek Batholith  59°16'N. 131°29"W.  GSC Paper 67-2A, pp. 11-12  31 32  GSC70-27  Hb Bio  147±8 139+6  Granodiorite  Hotalluh Batholith  58°09.6'N. 129°51.9'W..  33  GSC70-29  I66t8 157*11 193  Hotalluh Batholith  GSC62-71  Hb Hb Bio  Granite  34  58°08'30"N. GSC Paper 71-2, p. 18 129°52*00"W. GSC Paper 63-17, pp. 45-46  35  GSC70-30  Hb  155±8  Quartz monzonite  Hotalluh Batholith  58°10.5'N. 129°38.5'W.  GSC Paper 71-2, p. 19  3« 37  GSC70-31 GSC70-32  Hb Bio  163±9 163*7  58°07.5*N. 129°30'W.  GSC Paper 71-2, P. 19  38  GSC70-33  Hb Hb  215±H 215tH  Monzonite/ Hotalluh quartz Batholith monzonite  58°10'N. 129°39'W.  GSC Paper 71-2, p. 20  39  GSC70-34  Hb Hb  217*11 217*11  Diorite  Hotalluh Batholith  58oo4.5«N.  GSC Paper 71-2, p. 20  4o 41  GSC70-25 GSC70-26  Hb Bio  161*8 141*7  Quartz monzonite  Hotalluh 58°15.5'N. Batholith? •130°15.5*W.  HOTAILUH BATHOLITH, NORTHERN BRITISH COLUMBIA GSC70-28  * See referenoe.  Quartz Hotalluh monzonite / Batholith granodiorite  GSC Paper 71-2, pp. 17-18  GSC Paper 71-2, P. 17  134.  TABLE D-l  (cont'd)  Report No.  P u b l i s h e d K-Ar ages r e f e r r e d t o i n t h i s r e p o r t .  Referenoe Number and Mineral Dated  Age i n m.y.  Rook Type  Location  Unit  Referenoe  EARLY CRETACEOUS STOCK, NORTHERN B.C. Hb Hb  112*28 120t26  Biotite quartz diorite  GSC70-22  Bio  137±6  Hornblende T a c h l l t a quartz Lake diorite stook  44 GSC70-11  Bio  122±6  Granite  Hogem Batholith  56°20'113'N. 125°49'W.  GSC Paper 71-2, p . 11  45 K65-1  Bio  1?0±8  Syenite  Hogem Batholith  55°56'N. 125°28'W. Lorraine  White e t a l . 1968» Koo,  42  43  GSC70-21  Tachllta Lake stock  .58°38.5'N. 130 56'W. 6  *  .GSC Paper 71-2, p . 15  GSC Paper 71-2, p p .15-16  HOGEM BATHOLITH, NORTHERN B.C.  1968  LATE CRETACEOUS AND EARLY TERTIARY AGES COAST INTRUSIONS, NORTHERN B.C. AND SOUTHEASTERN ALASKA GSC61-39  Bio  54  Biotite granodiorite  Coast Intrusions  47 GSC61-38  Bio  65  Biotite granodiorite  «  590^7130"N. GSC Paper 62-17, P . 23 135000'30"W.  48  GSC61-46  Bio  65  r.  59°34'N. 6 135 ll'W.  GSC Paper 62-17. P .29  49  GSC61-47  Bio  70  f.  59°30'30"N. 135°13'30"W.  GSC Paper 62-17. P .29  50 GSC60-26  Bio  61  Granite  59°37'N. 1350o8-w..i_  GSC Paper 61-17. P .  51 GSC60-27  Bio  68  Biotite  59°50'30"N. 135 01'W.  GSC Paper 61-17, p .16  52 GSC62-75  Bio  69  Quartz monzonite  53 GSC66-6  Bio  44±2  Granodiorite  "  mouth of Soud R i v e r -  White et a l . 1 9 6 8  54  GSC60-34  Bio  30  Quartz diorite  *  59*18'N. 135°20'W.  GSC Paper 61-17, p . 20  55  PM3-1  Bio  48.7±1.8 Monzonite  1 East Marginal Pluton  56 PM3-2  Bio  52.8±2.6 Quartz monzonite  m  57 EN-2  Whole  46  Granite Biotite granodiorite  59°44'N. 134059'W.  GSC Paper 62-17, P . 23-24  15-16  O  m  58°34'24"N. GSC Paper 63-17, p . 49 133°18' 00"W.  EARLY TERTIARY AGES - EAST MARGINAL PLUTON (ALASKA)  R 51.Itl.5 Quartz monzonite  58 EN-3  Whole  59 EN-4  Bio  60 EN-5  Whole  61 EN-6  Bio  R 46.9±1.4 Quartz  R 51.011.0 Quartz  .  • See referenoe.  58°43'N. 133°55'W. 58°43'N. 133058'W.  N  58°4l'N. 133°59'W.  M  58°40'30"N. 134oo4'W.  w  58°39'N. 134°18'W.  monzonite  4 7 . O t l . 6 Quartz monzonite  58°43« 30"N.  133°52'30"W.  n  monzonite 49.6±1.4 Quartz monzonite  58°44'N. 133°51'w.  Porbes and E n g e l s ,  1970  135.  TABLE D-l  (cont'd)  Report No.  Published K-Ar ages referred to In this report.  Referenoe Number and Mineral Dated  Age In m.y.  Rook Type  Unit  Looatlon  Referenoe  KING SALMON LAKE AREA, B.C. 62  GSC62-76  Bio  22?  63  GSC62-77  Bio  206  58°34'40"N. GSC Paper 6 3 - I 7 , PP. 4 9 - 5 0 133°02'30"W.  Granodiorite boulder i n oong.  GSC Paper 63-I7, p. 50  STIKINE COPPER, NORTHERN B.C.  64 GC66-1  Bio  65 GC66-2  Bio  66  GC66-5  67  GC66-7  68  69  174±9  Central ore White et a l . , 1 9 6 8 zone DDH GC193 8 400' Central ore zone DDH GC148 @ 519'  I89+9  Bio 182±9 (chlorltlc)  Granite  »  Bio  177+9  Syenite  Copper Canyon syenite  A64-1  Bio  198+7  GSC64-1  Whole R  "  Central ore zone  BLUE RIVER ULTRAMAFIC INTRUSIONS, NORTHERN B.C. 245±80  Amphibolite  •  59°32'N. 129058'W.  GSC Paper 6 5 - 1 7 , p. 7  CASSIAR INTRUSIONS NEAR DALL LAKE, B.C. 70  GSC62-68  Muse  71  GSC62-69  Bio  72 73  GSC62-72 GSC62-73  Bio Muso  74  GSC62-70  Muse,  75  GSC70-9  Whole R  49±5  Tuff  Sustut Group  57°19'N. 127°40'W.  GSC Paper 7 1 - 2 , pp. 9 - 1 0  76  GSC70-10  Whole R  53±6  Tuff  Sustut Group  126°56'W.  56°54'H.  GSC Paper 7 1 - 2 , p. 1 0  Quartz monzonite  59 27'N. 127°42'W.  GSC Paper 6 3 - 1 7 , pp. 4 4 - 4 5  124 194  Gneiss  59°57"N. 131°58«W.  GSC Paper 6 3 - 1 7 , pp. 46-47  178  Gneiss  58°58'36"N. 130°01'24"W.  GSC Paper 6 3 - 1 7 , p. 4 5  139 123  0  Oblique Creek*  SUSTUT GROUP, NORTHERN B.C.  WOLVERINE COMPLEX, NORTHERN B.C 77 GSC70-14 78 GSC70-15  Muso Bio  4713 43±3  79 GSC70-12 80 GSC70-13  Muso Bio  128l6 124±6  Granite  Wolverine Complex  56°23'N. 125°21.5'W.  GSC Paper 71-2. p . 12  INGENIKA GROUP, NORTHERN B.C.  • See reference.  Sohlst  Ingenlka Group  ,  56°23 N. 125°21.5'W.  GSC Paper 7 1 - 2 , pp. 1 1 - 1 2  136.  TABLE D-l Beport No.  (oont'd)  Published K-Ar ages r e f e r r e d t o In t h i s r e p o r t .  Referenoe Number and Mineral Dated  Age I n m.y.  Rook Type  Reference  Looatlon  Unit  POLARIS ULTRAMAFIC COMPLEX, NORTHERN B.C. 81 82  CSC66-18 GSC66-19  Hb Bio  152±15  l64±9  P e r i d o t i t e P o l a r i s S6°Z6'H. Ultramaflo 125°35'W. Complex  CASSIAR BATHOLITH 83  GSC?0-48  Huso  84  GSC61-45  Bio  126  85  GSC60-30  Bio  98  86  GSC60-29 B i o  8?+4  GSC Paper 67-2A, p . 21-22  1  Granodiorite Cassiar (cataclastlo) Batholith  69°04 47"N. 130°49*35"W. ,  GSC Paper 71-2. pp. 30-31*  MARKER LAKE BATHOLITH  66  G r a n o d i o r i t e Marker Lake 6o°33'N. Batholith 130°57'W. Schist  east of 60°37'N. Harker Lake 130°47*W. Batholith  Granodiorite unnamed stock *  6l°07'N. 130°51'W.  GSC Paper 62-17, p . 28 GSC Paper 61-17, P . 17-18  GSC Paper 61-17, P . 17  AGES SOUTHWEST OP TINTINA TRENCH, YUKON TERRITORY (NASINA SERIES, YUKON GROUP, BRICK CREEK SCHIST) 87  GSC66-60  Hb  199+34  Granitic cobble i n conglom.  214  Schist  Laberge Group  6l°37'N. 135 53'W.  GSC Paper 67-2A, pp. 55-56  60-6l°N. 132-134°W.  GSC Paper 60-17, p . 7  6  88  GSC59-9  89  GSC59-11  Bio  140  Schist  Yukon Group  6l 17'N. 138°07'W.  GSC Paper 60-17. p.8  90  GSC61-41  Bio  147  Schist  Yukon Group  6l°l4'N. 136°57'W.  GSC Paper 62-17, PP. 25-26  91  GSC61-42  222  Schist  Yukon Group  60°00'30"N. 132°08'20"W.  GSC Paper 62-17, PP. 26-27  Huso  Muso  0  KLONDIKE SCHIST 92  GSC60-33  Muse  138  Schist  Klondike schist  63 54'N. 138°52'W.  GSC Paper 61-17, p . 19  93  GSC61-40  Muse  175  Schist  Kondike schist  64°07'N. 140°48*W.  GSC Paper 62-17, P. 25  64°02'00"N. 140°23'20"W.  GSC Paper 63-17, pp. 53-54  0  FELLY GNEISS 94  GSC62-82  Bio  202  Granodiorite P e l l y gneiss  95 96  GSC64-24 GSC 64-25  Bio Hb  187 161  Gneiss  Pelly gneiss  62°53i'N. 138°51'W.  GSC Paper 65-17, p . 22  97 98  GSC64-26 GSC64-27  Muso Bio  178 182  Granitic gneiss  Pelly gneiss  63°o6 45"N. 139°29'30"W.  GSC Paper 65-I7, pp. 23-25  ,  * Bee r e f e r e n c e , 1 T h i s sample I s not Included i n mean age since Poole (1972) considers the age t o be young.  137.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report Referenoe Ko. Number and Mineral Dated  Age In m.y.  Unit  Rook Type  Looatlon  Referenoe  GRANITIC ROCKS Granodiorite  *  Quartz monzonite  *  60°53*N. 135°33'W.  GSC Paper 6o-17t PP. 7-8  6l°21'N.  GSC Paper 60-17, PP. 8-9  6l°25'N. 138°45'W.  GSC Paper 60-17, p. 9  99  GSC59-10  Bio  223  100  GSC59-12  Bio  176  101  CSC59-13  Bio  58  102  GSC60-31  Bio  65  Quartz Ruby Range 6l°05'N. monzonite Batholith 136°59'W.  GSC Paper 61-17, pp. 18-19  103  GSC60-32  Bio  58  Granodiorite Ruby Range 6l°01'N. Batholith 138°08'W.  GSC Paper 61-17, pp. 18-19  Granodiorite Yukon Group  138°03'W.  NORTH-BIG SALMON RIVER CRYSTALLINE BELT 104  GSC65-34  Bio  90±6  Quartz Big Salmon 6 l ° 3 5 ' 3 0 " N, ,. GSC Paper 6 6 - 1 7 , pp. 3 5 - 3 6 monzonite R. Crystal- 133°26'30 W. line Belt  105  GSC65-35  Bio  90±6  Granite  106  GSC65-36  Bio  91±5  Schist  107  GSC65-37  Amphibole83±26  6l°46'N. 133°26'30"W.  GSC Paper 6 6 - 1 7 , PP. 3 5 - 3 6  6l°40'N.  GSC Paper 6 6 - 1 7 , pp. 36*37  6l°4l'N. 133016'w.  GSC Paper 6 6 - 1 7 , pp. 37-38  133°20'W.  Gneiss  CANADIAN CREEK, YUKON TERRITORY (CASINO DEPOSIT) 108  CP-25-69  69±3  Porphyritic daoite  «  62°43'N. 138°49'W.  109  CP-2-69  71±3  Porphyritic  •  62 43'N. 138°49'W.  110 GSC67-45  Hb Bio  99+6 95+5  dacite  0  62°42.9'N. 138°50.8'W.  Granodiorite  Phillips and Godwin, 1 9 7 0 , P. 3  GSC Paper 69-2A, p. 2 7  SELHYN BASIN NEAR YUKON TERRITORY - MACKENZIE TERRITORY BOUNDARY GSC67-65  Hb  80±5  112 GSC67-66  Bio  87±4  113  GSC67-49  Bio  88±4  114 GSC62-88  Bio  110  111  115  AK 1 2 5  Bio  96  116  AK 1 0 7  Bio  94  117  CSC65-45  Bio  Quartz monzonite Schist  • See referenoe.  GSC Paper 69-2A, p. 37  6l°39'40"N. T?RO-»)Lion"u. 128°34'00"W  GSC Paper 69-2A, pp. 28-29  Quartz Pyramid 6l 53'03"N. GSC Paper 6 3 - 1 7 , p. 58 monzonite Mtn. stock 127°58'52"W. o  65°55'N.  130°10'W.  Baadsgaard et a l . , 1961 a and b  Quartz Nahannl monzonite  62°05'N.  Baadsgaard et a l . , 1 9 6 l b ,  Schist  6l°23'N. 130°33'W.  GSC Paper 6 6 - 1 7 , pp. 4 3 - 4 4  Granodiorite Itsl  Mountains  Pluton  99±5  62°51'25"N.  128°49'30"tf.  •  pp. 4 5 8 - 4 6 5  138.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report ReferenoeAge No. Number and In m.y.Mineral Dated  Rook Type  Unit  Location  Reference  NORTHERN YUKON TERRITORY 118 GSC63-15  Bio  119 AK 108 Bio  121 AK 51  Bio  122  Hb  123 AK 110 124  GSC65-51  125 AK 105  Porphyrltio Old Crow granite Batholith  67°42'N. 140°42'W.  GSC Paper 6 4 - 1 7 (Part 1), p. 22  Old Crow Batholith  67°44>N. 139°50'W.  Baadsgaard et a l . , 1961b, pp. 458-465  220  120 GSC63-15  GSC63-I6  265±12  67°42'N. 370±l6 Porphyrltio Mount granite Fllton stock 140°42'W. 353  68°30'N. , 138°01 W.  Baadsgaard, et a l . , 196la, pp. 689-702  Porphyritic Mount granite Sedgwick stock  68°55'N. 139°07'W.  GSC Paper 64-17 (Part 1), P. 23  Porphyrltio granite  68 51'N. 139°07*W.  Baadsgaard et a l . , 1961b, pp. 458-465  Quartz monzonite  355  Bio 95 (ohlorltic) Whole R 237+47 Whole R 312  GSC Paper 64-17 (Parti), P. 22-23  "  0  ,  69°01 N. 141°05'W.  Basalt  GSC Paper 66-17, P. 49  65°19'N. Baadsgaard et a l . , 196lb, 130°48'W. pp. 458-465 ( D . of Mackenzie)  Syenite dike  KENO. HILL AREA, YUKON TERRITORY  126  GSC65-46  Muse  84±8  Schist  Yukon Group  63°55'15"N. GSC Paper 66-17, P. 44 135°26'W. (Galena Hill)  127 GSC65-47  Muse  93±12  Schist  Yukon Group  64°11'N. GSC Paper 66-17, P. *5 135°21'30"W.  128  GSC65-48  Huso  101±6  Schist  Yukon Group  63°47'30"N. GSC Paper 66-17, PP. 45-46 135°4l'45"w.  129 GSC70-4?  Muso  64±3 70±3  Schist  Yukon Group  , 63 23'N. 136°40 W.  130  GSC65-49  Bio  81±5  Quartz porphyry  *  63°51'05"N. GSC Paper 66-17, P. 47 135°51'20"W.  131 GSC65-50  Bio  85+7  Quartz monzonite  •  0 63°29'N. 136 58'W.  132  GSC62-78  Bio  102  Quartz monzonite  133 GSC62-8O  Bio  106  Granodiorite  * •  134 GSC62-81  Bio  81  Porphyrltio • quartz diorite  0  GSC Paper 71-2. P. ] 29 :  GSC Paper 66-17, pp . 47-48  64°01'50"N. GSC Paper 63-17. P. 51 135°25'50*W. 64°02'N. 135°50«w.  GSC Paper 63-17, p. 52  63°53*55*N. GSC Paper 63-17, PP. 52-53 134°46 i5-w. ,  TOMBSTONE STOCK (SIMILAR AGE BODIES) NORTH OF TINTINA TRENCH, YUKON TERRITORY  135 GSC66-58 Bio 136 GSC66-59 Hb  91±5 80±13  Quartz Tombstone monzonite stock  64°27"13"N. GSC Paper 67-2A, pp. 54-55 138°33'00"W.  137 GSC62-79 Bio  134  Blofeldspar porphyry  64°09*25"N. GSC Paper 63-17, p. 51 137°40'00"W.  • flee reference.  139.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report,  Report Referenoe No, Number and Mineral Dated  Ago In m.y.  Rook Type  Unit  Location  Referenoe  ANVIL AREA, YUKON TERRITORY 138  GSC61-43  Bio  100  Porphyritic daoite  139  GSC61-44  Bio  117  Porphyritic daoite  140 GSC65-44  Bio  86+6  Daoite  • •  Tay Formation  62°31'N, 131°51'W.  GSC Paper 62-17, P. 27  62°27>N.  GSC Paper 6 2 - 1 7 , P. 27  62°15'30"N. 132°03 30"W,  GSC Paper 6 5 - 1 7 , PP. 42-43  62°57*N. 132 30'W.  GSC Paper 6 6 - 1 7 , P. 38  62°54'N. . 132 27'W.  GSC Paper 6 6 - 1 7 , P. 9  62°56'N. 132°27*W.  GSC Paper 6 6 - 1 7 , PP. 38-40  132°18'W. ,  MOUNT SELOUS PLUTON 141 GSC65-38 142 GSC65-39  Bio Bio  83+7  Quartz monzonite  Mount Selous Pluton  81±10  Granodiorite  w  &  D  143  GSC65-4O  Bio  74+7  Quartz monzonite  •  144  GSC65-41  Bio  90+5  Quartz monzonite  Anvil Batholith  62°27'N. 133 27 30"W.  GSC Paper 6 6 - 1 7 , P. 40  Anvil Batholith  62°17'N. 133°03'W.  GSC Paper 6 6 - 1 7 , PP. 40-42  62°22'N. thermal metamorphosed 133 23'W. contact zone  GSC Paper 69-2A, PP. 27-28  146 G S C 6 5 - 4 3  GSC65-42  Muso Bio  79+6 87+5  Quartz monzonite  147 GSC 67 148 GSC67-48  Muse Bio  99+5 93+4  Schist  149 GSC70-45 150 GSC70-46  Huso Bio  94+5 94±5  Granodiorite Anvil (sheared) Batholith  145  O  ,  0  62°17.5'N. 133°l6.5'W.  GSC Paper 71-2, PP. ; 28-29  INSULAR BELT (51°-56°N.) - •QUEEN CHARLOTTE. ISLANDS,B.C. JURASSIC AGES (SYNTECT0NIC AND POST-TECTONIC?) 151 G S C 7 0 - 1  Hb  152  GSC67-20  Hb  153  GSC70-3  Hb  154  GSC66-14  Hb  Granodiorite Kano (gneissic) Batholith San 142*14 Quartz diorite Chrlstoval Batholith Chlnukudl I56+IO Quartz Pluton diorite I43t8  142±37 Granodiorite  Burnaby Island Pluton  53°17.5'N. 132°38.5'W.  GSC Paper 71-2, P. 6  52°34 30"N. 5 131 40'W.  GSC Paper 69-2A, P. 13  53°19'N. 131°58'W.  GSC Paper 71-2, P. 7  52°22*N. 131°15'W.  GSC Paper 67-2A, P. 19  ,  MID-TERTIARY (POST-TECTONIC) 155  GSC70-2  Bio  30±3  Granodiorite Central Kano Batholith  156 157  GSC67-16 GSC67-17  Hb Dlo  26±6 29±2  Granodiorite  158 GSC67-18  Hb Bio  38±2 39±2  Granite  Bio  62±3  159  GSC67-19  160  AK 378  n  Pocket Batholith  53°13'N. 132°29'W. 53°17' ' 132°26'W. N  52°34'N. 0 131 48'W.  GSC Paper 71-2, PP. 6-7 GSC Paper 6 9 - 2 A , PP. 11-12 GSC Paper 6 9 - 2 A , PP. 12-13  TERTIARY ACIDIC VOLCANIC ROCKS  * See referenoe.  Porphyry sill(?)  Massett formation  53°24.2' 132°23.1'  Mathews, 1 9 6 4 , pp. 4 6 5 - 4 6 8  140.  TABLE D-l  (oont'd)  Beport No.  Published K-Ar ages r e f e r r e d to In t h i s r e p o r t .  Referenoe Number and Mineral Dated  Age i n m.y.  Rock Type  Unit  Location  Reference  COAST CRYSTALLINE BELT OF BRITISH COLUMBIA BETWEEN LATITUDES 52.°N t o 56°N 161 162  GSC66-11 GSC66-12  Hb Bio  133+22 139+7  Quartz diorite  163  GSC67-24  Bio  104±4  164  GSC67-23  Bio  165 166  GSC64-5 GSC64-6  167 168  *  53°09*N 129°35'W.  GSC Paper 67-2A, P. 16  Quartz diorite  53°15'N. 129°35'W.  GSC Paper 69-2A, P. 15  115±6  Quartz monzonite  53 03'N 129°27*w.  Bio  103+.6 111+6  Granodiorite  »  GSC66-17 GSC66-16  Bio Hb  • 88±5 87±11  Granodiorite  *  I69  GSC67-21  Bio  84±4  Granodiorite M e l v i l l e 54°24'N. I s l . stock 130°44'W..  170  GSC66-4 GSC 66-5  Bio Hb  96+5 101+15  Granodiorite  1 7 1  172  GSC67-26  Bio  109+5  Granodiorite  173 176  GSC67-27 GSC67-28  Hb Bio  100+6 90±4  Gabbro  175 176  GSC67-29 GSC67-30  Hb Bio  87±5 81±4  Andeslte  177  GSC64-11  Bio  67+5  Quartz diorite  GSC66-13 GSC 66-12  Bio Hb  70±4 87+15  1 8 1  GSC67-33 GSC67-34  Hb Bio  182  GSC65-31  I83  GSC64-8  184  GSC64-7  185  GSC67-25  Bio  1 8 6  GSC64-12  I87 188  o  0  • • •  GSC Paper 69-2A, PP. 14-15  53 3l'N. 130°01*W.  GSC Paper 65-17, PP. 10-11  52°34'N. 6 128 4l'W.  GSC Paper 67-2A, P. 20  54°29'N. 130°57*W.  GSC Paper 69-2A, pp. 13-14 GSC Paper 67-2A, P. 12  52°45« 30"N. GSC Paper 69-2A, PP. 16-17 129°22'30"«. 52°06'30"N. 128°17'00"W.  *  GSC Paper 69-2A, P.  J  7  o  52 13'00"N. GSC Paper 69-2A, PP. 17-18 127°50'30"w.  »  53°28'N. 128°51'W.  GSC Paper 65-17. pp. 13-14  Granodiorite E c s t a l l Pluton  53°4l'N. 129°30'W.  GSC Paper 67-2A, P. 17-18  79+5 75+5  Granodiorite  52°10'N. o 128 00'W.  GSC Paper 69-2A, PP. 20-21  Bio  64±8  Quartz diorite  54°13'N. 130°O4'W.  GSC Paper 66-17, PP. 32-33  Bio  -.{-4+14, mesh)  .77+5  Quartz diorite  52°32*N. 6 128 02'W.  GSC Paper 65-17, P.  B i o 77+5 (-100+150. mesh)"  Quartz diorite  *  52°32"N. ^ooi'SS'w.  GSC Paper 65-17, PP. 11-12  49±4  Quartz diorite  *  53°l6'N. 128°l6'W.  GSC Paper 69-2A, P. 16  Bio  48±5  Biotite schist  *  53°38'N. 128°52'W.  GSC Paper 65-17, P. 14  GSC66-15  Bio  47±4  Granodiorite  *  54°54'N. 129°25'W.  GSC Paper 67-2A, pp. 19-20  GSC66-9 GSC66-8  Bio Hb  44±5 49±7  Quartz diorite  Quottoon Pluton  54°35'N. o l30 ll'W.  GSC Paper 67-2A, P. 15  191  GSC66-6 GSC66-7  Bio Hb  50±5 48t9  Quartz diorite  Quottoon Pluton  54°21 N. 129°52'W.  192  GSC65-29  Bio  43*5  Quartz diorite  GSC Paper 66-17, PP. 30-31  193  CSC65-30  Bio  44±4  ••  54 17«N.  G r a n o d i o r i t e A l a s t a i r . 54°05'N. Lake 129°01'W. Pluton  GSC Paper 66-17, PP. 31-32  194  GSC65-32  Bio  46±10  Granodiorite  178 179 180  189  190  * See reference.  «  .  • »  •  ,  0  ,  54°38 H. 129°02'W.  11  GSC Paper 67-2A, PP. 13-14  GSC Paper 66-17, PP. 33-34  141.  TABLE D-l  (cont'd)  Report No.  Reference Number and Mineral gated.  195  Published K-Ar ages referred to In this report.  In  Age m.y.  Rook Type  Looatlon  Labouohere Pluton  55°13'N. 129°51'W.  GSC Paper 65-17, p. 12  52°49'N.  GSC Paper 66-17, P. 23  52°07'N. 126°18'W.  GSC Paper 66-17, p. 30  Bio  45+12  Quartz monzonite  196 GSC65-19  Bio  47±5  Granodiorite  197  GSC65-28  Bio  70±14  Granodiorite War Drum Pluton  198  GSC64-10  Bio  57+6  Quartz monzonite  199  GSC66-20  Muso  51±6  Quartz monzonite  200  NC67-8  Bio  54±3  Quartz diorite  201  NC67-12  GSC64-9  Reference  Unit  126°38'W.  Labouohere Pluton  127°l4'W. 52°25'N. 127°l4'W.  GSC Paper 65-17, p. 13 GSC Paper 67-2A, pp. 22-23  BERG "Cu-Mo" PROPERTY 5 3  r,  127°  White, Harakal and Carter (1968)  Hornfels  Whole R 53±3  202 NC67-IO  Bio  48±2  Quartz monzonite (porphyry)  203  NC67-9  Bio  44+2  Latite porphyry dike  204  GSC67-22  Bio  37+2  Pegmatite  53°47'N. 129°02'W.  GSC Paper 69-2A, p. 14  205  GSC67-3I  Whole E 14.5±1  Gabbro  52^09.'15"N. 128°04'00"W.  GSC Paper 69-2A, p. 18  206  GSC67-32  Whole R 12.5±2.7 Diabase  207  NC67-15  208 Serb Creek  52°12'15"N. GSC Paper 69-2A, pp. 19-20 128°08'00"W.  Bio  179±8  Granodiorite  Luoky Ship White, Harakal and Carter (54°N, 127°W.) (1968)  Bio  4l±3  Porphyritic Quartz monzonite  54°N. N , W 127°W. *  INTERMONTANE BELT  52° - 56°N.  TOPLEY INTRUSIONS (see Table  Baadsgaard et a l . , 196la  «  53°42'N. 124°02'W.  GSC Paper 62-17, P. 21  Topley  54°31'N. 124 52'W.  GSC Paper 62-17, P. 22  Bio  163  Granite  210  GSC61-34  Bio  63  Diorite (non-follcated)  211  GSC61-35  Bio  Diorite  )  54°04'N. 124°4l'W.  209 AK23  178  Amax Expl. Ltd., Det. by Geochron Labs., Inc.  Topley  6  212 GSC6I-36  Bio  138  Granite  Topley  54°05'N. 125002'W.  GSC Paper 62-17. P. 22  213 GSC61-37  Bio  154  Granite  Topley  54°02'N. 125°02'W.  GSC Paper 62-17, P. 22  GLACIER GULCH MOLYBDENUM DEPOSIT - SMITHS RS • B. C.  214 GSC67-35  Bio  67t5  Quartz monzonite (porphyry)  GSC67-36  Bio  60±5  Quartz latite (porphyry)  215  * See referenoe.  54°49'30"N. GSC Paper 69-2A, p. 21 127°18'W. 2,782-2,851' DDH28 54°49'30"N. 127°18'W.  GSC Paper 69-2A, p. 22  142.  TABIE D-l  (cont'd) Published K-Ar ages referred to in this report,  Report No,  Reference Number and Mineral Dated  Age In m.y.  Rook Type  Unit  Location  Referenoe  216  GSC6?-37  Bio  63±4  Qtz-Bio veinlets  54°49'30"N. 127°18'W.  GSC Paper 69-2A, pp. 22-23  217  GSC67-38  Hb  65+6  Qtz-HbSulphlde veinlets  54°49'30"N. 127°18'W.  GSC Paper 69-2A, p. 23  218  NC67-41  Bio  69±3  Bio i n quartz molybdenum seam  219  BM65-1  Bio  105+4  Quartz diorite  220  BM65-3  Bio  98+4  Altered dike  White et a l . , 1968  221  BM65-4  Bio  104±4  Dike fragment In breccia ore  White et a l . , 1968  222  GSC62-64  Bio  I87  Granodiorite Takomkane 52°06 00"N. GSC Paper 63-I7, p. 42 Batholith 120°55'03"W.  223  AK302  Bio  53+2  Daclte  224  AK395  Bio  48+2  225  NC69-6  56.2±3  Biotite granitic stook  226  NC69-7  48.8±3  Syenomonzonite  White et a l . , 1968  B0S3 MOUNTAIN MINE, B. C «  White et a l . , 1968  5045 Level  TAKOMKANE BATHOLITH - CARIBOO DISTRICT, B. C. ,  CENOZOIC VOLCANIC ROCKS T-Allln  54°03.5"N. 125057.1"W.  Endako Group  54°07.3'N. 125°19.0'W.  Mathews, 1964, pp. 465468  SAM GOOSLEY PROPERTY, CENTRAL B.C 54°11'N. 126oi6'W.  OMINECA BELT 227  GSC70-40  Bio  44*4  228  GSC70-41  Muso  46±  229  GSC70-43  Muso  •  Church 1970, (G.E.M.) pp. 119-125  54°11'N. 126°l6'W.  52Q - S6°  WOLVERINE METAMORPHIC COMPLEX Gneiss Wolverine 55°07'35"N. GSC Paper 71-2. pp. 23-24 Complex 123029'15"W. Gneiss  Wolverine Complex  55°07'35"N. GSC Paper 71-2, p. 24 123°29'15"W.  40±2  Granite grelsen  Wolverine Complex  55°07'35"N. GSC Paper 71-2, PP. 24-25 123°29'15"W.  230 GSC70-42 Bio  43±4  Gneiss  Wolverine Complex  55°32'10"N. GSC Paper 71-2, p. 24 123°52'40"W.  231 GSC70-44  Bio  45±2  Amphibolite Wolverine Complex  55°32'10"N. GSC Paper 71-2, p. 25 123°52'40"W.  3  232  GSC70-37  Muso  45±3  Schist  Wolverine Complex  55°23'30"N. GSC Paper 71-2, p. 22 123°39'50"W.  233  GSC70-38  Muso  50±6  Pegmatltlo granite  Wolverine Complex  55°23'30"N. GSC Paper 71-2, p. 23 123°39'50"W.  * See referenoe.  143.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report No.  Referenoe Number and Mineral Dated  Ago In m.y.  Rook Type ;  Unit  Looatlon  Referenoe  234  GSC70-39  Muso  47±3  Gneiss  Wolverine Complex  55°19'N. 123O30'W.  GSC Paper 71-2, P. 23  235 236  GSC61-31 GSC61-32  Muso Bio  75 77  Sohist  Wolverine Complex  55°23'30"N. * GSC Paper 62-17, P. 19-20 123°39*50"W.  237  GSC61-30  Bio  69  Gneiss  Wolverine Complex  55°33'N. 123°56'w.  GSC Paper 62-17, P. 19  238  GSC61-33  Muso  71  Gneiss  Wolverine Complex  55°19'N. 123°30'W.  GSC Paper 62-17, P. 20-21  239  GSC60-23  Muso  22  Pegmatitlo granite  •  55°24'N. 123°39'W.  GSC Paper 61-17, P. 14  240  GSC60-24  Bio  29  Marble  *  55°27'N. 123°34'W.  GSC Paper 61-17, P. 14  241  GSC62-67  Bio  78  Granite  •  55°5'20"N. GSC Paper 63-17, PP . 43-44 123°18'50"W.  Malton gneiss  55°25*N. 118°42'W.  GSC Paper 71-2, P. 13  MALTON COMPLEX 242 GSC70-16 243 GSC70-17  Muse Bio  60±3 66±3  chips of gneiss and schist  244 GSC70-18  Bio  57±3  Granite  Malton gneiss  52°22.5'N. U8°38.5'W.  GSC Paper 71-2,  245 GSC67-43  Bio  53±4 59±5  Gneiss  Malton gneiss  52°36'00"N. 119°01'20"W.  GSC Paper 69-2A, P. 25  246 GSC67-44  Hb  H4tl2  ta  GSC Paper 69-2A, P. 26  24? GSC65-24  Bio  GSC67-40  249 GSC67-41  248  P. 13-14  m  «  72+5  Gneiss  »  52°38'N. 118°59'W.  GSC Paper 66-17, PP . 26-27  Bio  36+3  Quartz diorite  54°06'N.  GSC Paper 69-2A, P. 24  Bio  93±4  Quartz monzonite  • •  53°38'N. 122°38*W.  GSC Paper 69-2A, PP . 24-25  MISINCHTKKA SCHIST 250 251  GSC62-65 GSC62-66  Bio Muso  143 136  Sohist  Misinchlnka 55°10'49"N. GSC Paper 63-17. PP . 42-43 schist 122°45'55"W.  252  GSC66-21  Bio  105±6  Granite boulder  *  53°42'N. 122°4l'W.  GSC Paper 67-2A, PP . 23-24  253  G3C66-22  Bio  98t5  Quartz monzonite  •  53°41'N. 122°4l'W.  GSC Paper 67-2A, PP . 23-24  254  GSC66-23  Bio  104±5  Quartz monzonite  •  53°18'N. 122°22'W.  GSC Paper 67-2A, P. 24  255  GSC66-24  Bio  107±6  Quartz monzonite  •  53°25'N. 122°l4'W.  GSC Paper 67-2A, P. 24-25  256  GSC66-25  Hb  176+20  Granite  •  53°44'N. 122°20'W.  GSC Paper 67-2A, PP . 25-26  257  GSC66-26  Bio  106±6  Granodiorite *  52°04'N. 122°35'W.  GSC Paper 67-2A, P. 26  PRINCE GEORGE QUESNEL AREA*  • See referenoe.  144.  TABLE 0-1  (oont'd) Published K-Ar ages referred to in this report.  Report Referenoe No. Number and  mineral,. Pat so.  Age in m.y.  Rook Type  Unit  Looatlon  Referenoe  MIETTE GROUP 258 GSC66-47  Bio  111±5 Quartzose phylllte  Hiette Group  52°32'34"N. GSC Paper 67-2A, pp. 43-44 llS^l'Se-W.  KAZA GROUP 259  GSC64-4  Muso  260 261  GSC64-13 GSC64-14  Bio 51±6 Huso 54±6  85+15  Granite pegmatite  Kaza Group  52°54'N.  GSC Paper 65-I7, p. 9  52°21,40"N. 119°39'00"W.  GSC Paper 65-I7, pp. 15-16  l^^l'W.  CARIBOO GROUP  262 GSC63-6  Bio  143±14  Quartz monzonite  Cariboo Group  Granodiorite  *  52°34 00"N. GSC Paper 64-17, Part 1, 120°02'30"W. pp. 15-16 ,  INSULAR BELT - VANCOUVER ISLAND 263 K-Ar-1652  Phlogo-181±8 pite 178±8  Empire Dev.& Carson et a l . , 1971 Coast Copper  Skarn  BRYNNOR MINE GSC 64-2  Bio  167+10  Granodiorite  *  49 03«N. 125°25'W.  GSC Paper 65-17, PP. 7-8  265 GSC64-3  Bio  121±35  Feldspar porphyry dyke  *  49°03'N. 125 26'W.  GSC Paper 65-17, pp. 8-9  264  266 K-Ar-1716 Bio  47+3  267  166±8  (GSC70-1716)  o  0  Carson et a l . , 1971  UCONA BATHOLITH GSC65-I8  Bio  Granodiorite Ucona Batholith  268  GSC65-17  Bio  162±9  Granodiorite Ucona  49°43'30"N. 125°56'25"W.  49°49'15"N.  GSC Paper 66-17, P. 22 GSC Paper 66-17, P. 21  Batholith 125°58«25"W.  NIMPKISH IRON MINE 269 270  GSC65-14 G3C65-15  Bio Hb  151±l4 l43±60  Granodiorite Nlmpklsh 50°l6'35"N. GSC Paper 66-17, pp. 18-20 Batholith 126°51'21"W.  271  GSC66-27  Bio  150±8 152±7  Quartz monzonite  272  GSC66-28  Nlmpklsh  Batholith  50 22'15"N. GSC Paper 6?-2A, p. 27 126°45'40"W. o  ZEBALLOS IRON MINE Phlogo-l48±8  plte  Skarn  »  50 02'58"N. GSC Paper 67-2A, p. 28 126°49'56"W. o  TEXADA MINES 273 K-Ar-1698 Hb  * See referenoe.  I65+9  Granodiorite Gllles stock  49°42'N. 124°33'H.  Carson et a l . , 1971  145.  TABLE D-l  (cont'd) Published K-Ar ages referred to In this report,  Report Referenoe No. Number and tUnera!, gated 2?4  GSC67-39  Bio  Age In m.y. 120±6  Rock Type  Unit  Location  Referenoe-  Granodiorite Pocahontas 49°43'25"N. GSC Paper 69-2A, pp. Stock 124°24'30"W.  275 K-Ar-15*H(2) Bio 110+5 276 K-AT-1541A Hb Il4il5  Granodiorite Pocahontas Stock  Carson et a l . , 1971  277 K-Ar-1778A Bio 278 K-Ar-1778 Bio 279 K-Ar-1?77 Hb  Granodiorite East Stook  Carson et a l . , 1971  155+8  280  GSC66-33  160+8  281  GSC66-34  Bio  111+6 106±4  Whole R 163*20  49°05'15"N. GSC Paper 67-2A, pp. 32-33 124°l6'15"W.  Granodiorite Sohist  Sicker Group Catfaoe Stook  282 GSC65-II  Bio  48+.12  Quartz diorite  283  GSC66-31  Bio  50+5  Granodiorite  284  GSC66-32  Bio  59+3  Quartz monzonite  285  GSC70-36. , Hb.  23-24  48°52'00"N. GSC Paper 67-2A, pp. 33-34 123°47'30"W. 0 (Twin J) 49 l4'35"N. GSC Paper 66- 1 7 , P. 15 125°57'00"W. (Catface) o  44±6  49°oi'25"N. GSC Paper 67-2A, pp. 31-32 125029'10"W. (Brynnor Mine)*  Orebody  48°27'N. . 124°03'W. (Sunro Mine)  48°26'55"N. GSC Paper 66-17, PP. 17-18 124°00'00"W. (Faith Lake)  286 GSC65-13  Bio  39+10  Quartz diorite  287 GSC65-12  Bio  38±4  Quartz diorite  288  GSC66-29  Bio  39*7  Quartz diorite  289 GSC66-30  Bio  35+6  Quartz diorite  38+2  Quartz diorite  290 GSC69-I653 Bio  49 09'25"N. GSC Paper 67- 2A, pp. 30-31 125°55'30"W.  Zeballos Batholith  GSC Paper 71-2, p. 22  50°02'07"N. GSC Paper 66-17, PP. 16-17 126°47*04"W.  49°39'12"N. GSC Paper 67T2A, P. 29 125°24'4l"W. (Forbidden Plateau) Mount  49°46'04"N.  Washington 125°17'24"W.  stook  GSC Paper 67-2A, pp. 29-30  (Mt. Washington Mine) cr  49 01'N.  124°39'W.  Carson, D.J., I969, p. 518  (Corrlgan Creek) 49° - S2°N.  COAST CRYSTALLINE BELT AND CASCADE MOUNTAINS CHILLIWACK BATHOLITH  Chllliwack 49°03'N. Batholith 121°19'W.  291 10  Bio  29tl  Gabbro  292 11  Bio  28±1  Quartz diorite  49°05'N. 121<>26'W.  293 12  Bio  26±1  Quartz monzonite  49°06'N. 121°27'W.  294  13  Bio  26+.1  Quartz monzonite  49°02*N. 121°23'W.  295  14  Bio  26tl  Quartz monzonite  296 15  Mafic 24+.1 cono.  * See referenoe.  Quartz diorite  " Williams Peak Stock  49°02'N. 121°23'W. •  Richards & White, 1970, p. 1206  146.  TABLE D-l  (cont'd)  Report No.  Referenoe Number and Mineral Dated  297 16a  Published K-Ar ages r e f e r r e d t o In t h i s r e p o r t . Age In m.y.  :  Rook Type  Unit  Looatlon  Referenoe  Bio Bio  24±1 24+.1  Quartz diorite  Hioks Stock  17  Bio  21±1  Granophyre  Mount Barr Batholith  49°19'N. 121°27'W.  m  299 18  Bio  18_1  Grano diorite  Mount Barr Batholith  49°l4'N. 121°35'W.  M  300 19  Bio  16+1  Quartz monzonite  Mount Barr Batholith  49°15'N. 121°33'W.  301 AK-31  Bio  18  Quartz diorite  Mount Barr Batholith  49°15*N. 121°40'W.  302 AK-45  Bio  18  Quartz diorite  Mount Barr Batholith,  49°l4'N. 121°4o'W.  303  Bio  32  Chllliwack Batholith  48°38'N. 121°21'W.  UBC Guidebook, 1968  304  Bio  23  Granodiorite  *  49°20'N. 121°38'W.  Richards, 1971  20  Quartz diorite  49°30'N. 121°02'W.  Misch, 1966  39+4  Granite  49°30'30"N.  GSC Paper 66-17, p. 11  40±5  Daoite  51°23'N. 120°58'W.  GSC Paper 66-17, P . 28  Hell's Gate  49°47'N. 121°27'W.  Baadsgaard, 1961  Hell's Gate  49°46'N. 121°26'W.  reported by R i c h a r d s , 1<  Sliver 49°23'N. Creek Stock 121°20'W.  Richards & White, 1970, p. 1206  b  298  305 306 GSC65-8 307 GSC65-26  Bio Bio  Cascade Pass stock  * •  Rlohards & White, p. 1206  1970,  Baadsgaard, I96I  121°10'W.  HELL'S GATE STOCK 308  AK-24  309  GSC70-1736 Hb  Bio  35  Granodiorite  40  HOPE PLUTONIC COMPLEX  310 9  Hb  35±2  Quartz diorite  VATJI INTRUSIONS  311 8  Bio  35+2  Quartz diorite  Ogllvle Stock  49°20'N. 121°27'W.  Richards & White, 1970, p . 1206  312 7  Bio  4l±2  Quartz monzonite  Coqulhalla Stock  49°22'N. 121°22'W.  «  313 4a  Bio Bio  59+3 59±3  49°19'N. 121°21'W.  H  b  G r a n o d i o r i t e -Berkey Creek  CUSTER RIDGE MICA-HORNBLENDE PERIDOTITE  314 6  Hb  315 GSC70-1737 Bio •See referenoe.  44±3  44  Hbite  Skagit Mica Perldotite  49°01'N. 121°18'W.  49°46'N. 121°26'W.  Richards .& White, 1970, p. 1206  147.  TABLE D-l  (oont'd)  Published K-Ar ages referred to in this report.  Report No.  Referenoe Number and Mineral Dated  Age i n m.y.  316  GSC70-1728 Bio  70  49°50'N. 121°4l'W.  317  GSC70-1731 Hb  72  49°55'N. 12l°34'W.  a  318  GSC?0-1734 Hb  73  49°4l'N. 121°29'W.  •t  319  GSC70-1735 Bio  74  49°4l'N. 121°29'W.  a  320 321  ' Hb Bio  80 80  Quartz diorite  49°23'N. 121°28'W.  Richards, 1971  322  Bio  82  Quartz diorite  49°22'N. 121°29'W.  Richards, 1971  49°12'N. 121°05'W.  GSC Paper 6 6 - 1 7 , PP. 13-  49°l6'45"N. 120°46'W.  GSC Paper 66-1?, pp. 12-  49°14'N. 123°08'H.  White, 1968  Rook Type  Unit  • •  Location  323  GSC65-10  Bio  84±6  Granodiorite  Dewdney Creek Group  324  GSC65-9  Bio  98±6  Granodiorite  *  325  Bio  92  Granodiorite  326  Bio  95  Quartz diorite  *  49°5l'N. & 123 11'W.  327  Hb  97  Quartz diorite  Bio  97  • •  49°43'N. 123°06'W.  328  KA-126  329 330  GSC66-47  331  Granodiorite  Bio  102  Quartz diorite  Bio  111±5  Quartzose Phylllte  Bio  158  Quartz diorite  *  Hlette Group  49°22'N. 123°l6«W. 0  Reference unpublished  m  a Baadsgaard, 1961  49 21'N. 12l°34'w.  Richards, 1971  52°32'34"N. 118°4l'56"W.  GSC Paper 67-2A, p. kj-i  49°54'N. 123 07'W.  White, 1968  D  SPUZZUM INTRUSIONS 332  la b  Bio Bio  103±5 103±5  Quartz diorite  333  2a  Bio  79+4  Quartz diorite  334  3  Bio  77±3  Quartz diorite  Hb Bio  76 76  Quartz diorite  Bio  253  *  335 336  337 338  ••  Whole R 258  • See referenoe.  •  Richards &. White, 1970, p. 1206  • •  a a  49°36'N. 121°27'W.  McTaggart & Thompson, (1967)  Oroas Island  48°39'N. 6 12 01'W.  UBC Guidebook, 1968  Vedder Mountain  49°04'N. 122°03'W.  Ross i n UBC Guidebook, 1968  148.  TABUS D-l  (oont'd)  Published K-Ar  Report Ho.  Hel'eronoe Number and Mineral Dated  Age i n m.y.  ages r e f e r r e d t o i n t h i s r e p o r t .  Rook Type  Looatlon  Unit  INTERMONTANE BELT  -  Reference  •52°- 49°  TERTIARY AGES »  339  AK-116  A0±2  Basalt  340  AK-268  12±2  Basalt  *  341  AK-100  13t2  Basalt  342  CSC65-26 B i o  40i5  Daoite  343  AK-117  Bio  45±2  Trachyte  • •  Kamloops Group  Bio  46  Quartz diorite  C a s t l e Peak 48°59*N. Stock 120°52'W.  344 345  347  AK-99  348 349  47±2  Breccia  Kamloops Group  Bio  47  Basalt  Bio  48t2  Volcanic ash  Bio  49  Basalt  Bio  49±2  Dolerite  AK-149  346  AK-118  Bio  350  50°58.5'N. 120°58.8'W.  »  50  Mathews, 1964  51°54.9*N. 0 12301.9*M..  *  51°53.2'N. 122°49.5'tf.  •  5l°23'N. 120°58'W.  GSC Paper 66-17, pp . 28-29  50°43'N. 120°49'W.  Mathews, 1964  ,  GSC Paper 67-2A, p .39  50°08.3 N. 119°37.5'W.  Mathews, 1964  «  49°29«N. 120°46'W.  UBC Guidebook, 1968(map)  Princeton Group  49°27*N. 120°32'W.  Mathews, 1964  50°48'N. 121°10'W.  Mathews, 1964  • • •  Kamloops Group  50°44'N. o°33'w.  •  12  49°26'N. 120°30'W. ,  UBC Guidebook, 1968(map) rj  351  Bio  50  352  GSC69-1444 B i o  64  353  AK-625 Andeslne  50  Hornblendeandeslte  *  354  AK-626  48  Andesite  «  n  -  •• • • •• • • •  •  •  Hb  •  355  AK-627  Hb  52  Andeslte  356  AK-628  Bio  50  Ash  357  AK-629  Andeslne  48  Ash  358  AK-631  359  AK-632  Bio  50  Rhyolite Lava  360  AK-633  Andeslne  49  a  361  AK-634 Sanldine (fine)  47  Lapllll Tuff  362  AK-635  Sanldine (coarse)  50  Lapllll Tuff  363  AK-636  Andeslne  51  Ash  364 365  AK-637 AK-638  Glass 22 • ..shards  Bio  Bentonite  Ash 56 Ash  Sanldine  * See r e f e r e n c e .  56  «  «  49°14 N. 120°36'W. 51°28°N. , 122°58 «.  unpublished  Sunday Summit  H i l l s £ Baadsgaard, 1967  KcAbee M  Qullchena  •  •  *  Allenby H  Sunday Creek  *  Sunday Creek HcAbee  •  m  *  m  •  .  149.  TABLE D-l  (oont'd)  Published K-Ar ages referred to In this report.  ReportReferenoeAge No. Number and In m.y, Mineral Dated  366 AK-640  367  Rook Type  Ollgo- .51 olase  AK-641 Sanldlne  • •  Ash  50  Ash  Looatlon  Unit  Battle Bluff  Reference H i l l s 4 Baadsgaard,  -  •  m  368 AK-642  Bio  50  Ash  369 AK-656  Bio  48  Ash  370  Bio  47  Bentonite  «  Collins Gulch  M  371 AK-630 Sanldlne  79*  Bentonite  m  372 GSC67-42  •  Qullchena  73+4  AK-643  Hb  M  Granodiorite  China Head Mtn. stock  ft  51°10'N. 122°23'W.  GSC Paper 69-2A, P.  MAGGIE MINE (Cu-Mo Porphyry)  373  MM16  Whole R  6l.2±2  Biotite porphyry  «  50°52.3-55.5'N. McMilllan, 1970, 6 12123.1-23.7'W. pp. 324-325 (Haggle)  Unmlnerallzed volcanic strata that unc onformably overlie mineralized Nicola rocks - Cralgmont  37* 375  GSC61-29  Bio  80 (108)*  Lava,.  376 GSC65-27  Bio  100±6  Quartz diorite  377  GSC65-25  Bio  166±11  Quartz diorite  «  378 GSO65-23  Bio  105+.9  Quartz monzonite  •  50°12'N. I20°55'w.  boulder i n 51°11'N.  eonglomeratel22°35'W. 5l°15'N. 120°58'W.  GSC Paper 62-17, P. unpublished  GSC Paper 66-17, P. GSC Paper 66-17, P.  51°4l'20"N.  GSC Paper 66-17, P.  49°l6'45"N. 120°46'W.  GSC Paper 66-17,  4 9 ° 361 ' N .  GSC Paper 63-17,  ,  120°0725"W.  EAGLE GRANODIORITE Bio  98±6  Granodiorite  *  380 GSC62-56  Bio  143  Granodiorite  381 E-la b  Bio Bio  103tl.6 ., 106.2±1.7  H  382 E-2-1 2  Bio Bio  99.1±1.6 96.4±1.5  m  383 E - 3  Kusc 71.7±1.2 Muso 71.8+1.2  Pegmatite  384 E - 4  Bio  Granodiorite  • * • •*  379  GSC65-9  85.4±1.4  385 E-5  Bio  102.±1.6  m  386 E-6  Hb  104.5±1.7  u  387 E-7  Bio  106.2+1.7  m  •See reference.  *  • •  120 55'W.  • • •  Roddick, 1970 m  m  »  m  • •  m  •  m  m  150.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report Referenoe Ho. Number and Mineral Dated 388  E-8-1 2  389  Hb Bio  GSC65-22 Bio (see 378)  Age In m.y.  Rook Type  Unit  Looatlon  111.4+1.8 111.7±1.7 112.1±1.8  Granodiorite  •  *  «  •  14019  Quartz monzonite  •  51°49'N. 120°03'30"W.  GSC Paper 66-17, P. 25  »  51°15'N. 120°58'W.  GSC Paper 66-17, P. 2 8  390 GSC65-25  Bio 166+.11  Quartz diorite  391 G S C 6 6 - 4 1  Bio 176±8  Pegmatite  Referenoe Roddick, 1970  IRON MASK BATHOLITH Iron Mask  50°35'N. GSC Paper 67-2A, p. 39 120°21'W. (Fargo Mineral Claim)  BRENDA MINES (see Oriel 1972) 392 W67-3  Bio 1 4 8 + 6 Hb 168±8  Granodiorite Okanagan Batholith  Brenda Pit  393 V67-4  Bio 14815 Hb I66t8  Granodiorite Okanagan Batholith  Brenda Pit  394 H-l  Bio 154.5+2.4 Granodiorite Similkameen  White et a l .  a  SIMILKAMEEN BATHOLITH  a  395 H-2  Hb 152.2+2.4 Bio 1 4 9 . 5 + 2 . 3  396 H-3  Bio 156.9+2.4  m .  397 H-4  Bio 156.4+2.4  398 H-10  Bio 156.1+2.4  a a-  a a a  Roddick, 1970 «  • -* •  • •  HEDLEY COMPLEX Hb Hb  170.7+2.7 179.5*3.7  Diorite  4oo H-8  Hb  183.2±2.9  Diorite  401 H-11L  Hb  170.812.6  Diorite  402 H-11H  Hb  176.2±2.9  Diorite  403 H-12. 404 H-14  Hb  188.313.0  Gabbro  Hb  190.213.0  Diorite  405 GSC62-55  B i o 186  TULAMEEN COMPLEX Pyroxenlte Tulameen  406 T - l a  Bio 68.011.2  Pyroxenlte  Roddlok, 1970  Bio  81.9H. 3  Pyroxenlte  Roddick & Farrar, 1 9 7 1  Hb  286  Pyroxenlte  H-6a  407  IB  405a GSC62-57  • See referenoe.  Hedley Complex  • • • • •  399 H-6  a a a a a  Roddick 1970  «  49°34'N. 120°54'W.  49°26'N.  120O48'W.  GSC Paper 63-17, p. 38  GSC Paper 6 3 - 1 7 , p. 39  151.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report,  Report ReferenoeAge No. Number and In m.y. Mineral Dated  Rook Type ' Unit  408  2H-1 2 3  Hb Hb Hb  192.5+2.9191.5+2.9 191.6±2.9  Diorite  409  3B  Bio  127.4±2.0  Diorite  Hb Hb Hb Hb  201.5+3.0 200.4+3,0 196.6+3.0 199.1±3.0  Hornblendlte  410 5H-1 2  I 411  7W  Whole R 1?8.1±7.2 Bio  412 8B  151.5±2.3  «  w  •  m  M  Hb ollnopyroxenite  8V  414  8P  415  8H-1 -2  Hb Hb  206.4±3.1 203.5±3.1  M  •  416  9H  Hb  209.6+3.5  It  m  Bio 171.5+2.6  • • • •  M  Pyroxenlte  Roddlok & Farrar,  •1  H  Pyrox 922.3tl3.2 Hb ollnopyroxenlte  Referenoe  M  413  41? 10B  •  Tulameen  Amphibolite  Whole R 198.2±3.2  Location  U  N  M  M  M  • • •  m  m  COPPER MOUNTAIN, B.C. 418 CM-ore-65 Bio 194±7  Biotite velnlet with ohaloopyrlte  49°19'N. 120°32'W.  Wolf Creek  419 CM-F20a-65 Bio 199+7  Monzonite - Copper Mtn. Stock  420 CM-AL7-65 Bio 194+8  Monzonite  421 CM-E2a-65 Bio 151+6 Clino- 150+.9 pyroxene 422 CM-12-65  Bio 182±8  423 VP-69KA-1 Bio  194±8  Diorite hydrothermally altered Gabbro  m  * »  m m  •  • m  «  Latlte porphyry  Lost Horse  424 VP-69KA-2 Bio 197+8  Diorite  Smelter Lakes  425 VP-69KA-3 Bio  Diorite  Sinclair 4 Wh  49°19*N.» 120°32'W.  "  Preto et al.» m  m  n  Quartz monzonite  Verde Creek  m  42? VP-69KA-5 Bio 98+4  Quartz monzonite  Verde Creek  m  428 VP-69KA-6 Bio 181±7  Diorite .  Volgt  Diorite  Volgt  m  Mleromonzonlte Lost porphyry Horse  m  426 VP-69KA-4  200±8  Bio 101±4  429 VP-69KA-7  Bio 194+7  430 VP-69KA-8  Bio 194+8  431 VP-69KA-9 Bio 197+8 432 VP-69KA-10 Bio 195±8  Latlte porphyry  Mleromonzonlte Lost porphyry Horse  433 VP-69KA-13 Bio I89+.8 Biotlte-sulphlde pegmatite vein * See referenoe.  Lost Horse dike  •  m  m  m  m  152.  TABLE D-l  (oont'd) Published K-Ar ages referred to in this paper,  Report Ko.  Referenoe Number a n d M i n e r a l Dated  Ago  In m.y.  Rook Type  Looatlon  Unit  Referenoe  434 1DB70  Seriolte  GUICHON BATHOLITH -• HIGHLAND VALLEY, B. C.• « 196±6 Bethsalda Blanohflower, 1971 Quartz diorite  435 2DB70  Seriolte  195+6  Bio  189+6  a  a  203+6  a  a  «  Bio  198+6  M  a  •  439 K63-240  Bio  199±8  Breccia  Iona Breccia  440 CSC66-37  Bio  184t8  Quartz diorite  Gulohon Batholith  441 GSC66-38  Hb  189±20  Quartz diorite  M  50°29'20"N. GSC Paper 67-2A, PP. 36-37 120°51'55"w.  442 GSC66-40  Quartz diorite  50 34'45"N. GSC Paper 67-2A, PP. 37-38 121°13'25"W.  444  Hb 187+27 Bio 197±10 (Replaces GSC63-3)* AK-44 Bio 186  H  443 GSC66-39  Quartz diorite  II  50°29'N. 120°58'W.  W  50°29'10"N. GSC Paper 63-17, pp. 41-42 121°03'20"W.  436  3DB70  437 4DB70 438  5DB70  Bio  445 GSC62-63  Bio  224**  Granodiorite  446 GSC62-59  Bio  227»*  Quartz diorite  447 GSC62-61  Bio  230*» 237*«  Quartz diorite  448 CSC62-60  Bio  237**  Quartz diorite  449 GSC62-62  Bio  242«*  Granodiorite  450 GSC62-58  Bio  245»*  Quartz diorite  451 GSC63-2  Bio  242±12 Granodiorite *«  452 GSC63-3  Bio  265±l4«»  Quartz diorite  453 GSC63-4  Bio  240±12** Quartz diorite  454 GSC63-5  Bio  248±12 Granodiorite  455 GSC66-35  Bio Hb  194+10 Granodiorite 198tl2  GSC66—36 (see 389)  • •  N  „..!*.  * See reference. •» Values considered to be high (see reference).  «  m M  ft  •  White in Northoote, 1969  50°29'20"N. GSC Paper 67-2A, PP. 35-36 120°51'55"W.  o  «  120°55'05"W.  Baadsgaard, 1961  GSC Paper 63-I7, p. 40  50°28«55"N. GSC Paper 63-17, pp. 40-41 i20°55'4o"w. •  m  50°29'N. GSC Paper 63-17, p. 40 120°55'W. 59°29'10"N. GSC Paper 63-17. p. 41 121°03'30"W.  m  50°30«03"N. GSC Paper 63-17, P. 39 120°56'25"W.  M  50°26'N. GSC Paper 64-17, (Pt. 1), o p. 12 121 l4'20"H. 50°34'45"N. GSC Paper 64-17, (Pt. 1), 121 13'25"W. pp. 12-13  ft  6  «  •  o  50 29*20"N. GSC Paper 64-17, (Pt. 1), P. 13 120°51'55"W. 50°13'10°N. GSC Paper 64-17, (Pt. 1), 120°55«00"W. pp. 13-15 (Craigmont Open Pit) 51°20'40"N. GSC Paper 6?-2A, PP. 34-35 120°24'00"W.  153.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report Referenoe No. Number and Mineral Dated  Age In m.y.  Rook Type  Unit  Looatlon  Referenoe  TERTIARY AGES AK-25  Bio  45? AK-27  Bio  36  Granite  Casoade  49°01'N. 118°18'W.  Baadsgaard. et a l . i 196  8  Granite  Nelson(?) Batholith  50°00'N. 118°06'W.  M  CORYELL 458 AK-28  Bio  54  Syenite  459 AK-26  Bio  58  Syenite  Coryell  49°03'N. 118°03'W. 49°04'N. 11?°58'W.  460  GSC60-20  Bio  27  Leuorosyenite  "  49°24'N. GSC Paper 61-17, pp. 12 118°02'30"W.  461  GSC61-13  Bio  32  Granite  *  49°50'30"N.  462  GSC61-12  Bio  53  Granite  463 CX70-17  Bio  50.6±1.5 Monzonite  49°05'N. 117°15'W.  464 CX70-21  Bio  49.5±1.5 Lamprophyre dike  49°05'N. 117°15'W.  465 R70-1  Bio  48.9±1.4  466 B70-5  Bio  49.0+1.5 Monzonite  Monzonite  H7056'30»w.  49°49'15"N. GSC Paper 62-17, P. 10 117°56«20"W.  -  •  • • • *  467 B70-18  Bio  48.3±1.4 Syenite  468 R70-12  Bio  48.1+1.5 Gabbro  Diorite dyke  Bio Hb  46.4+1.5 Lampro48.4+.1.5 phyre  Spokane dyke  58.1±2.0 Lampro60.5+2.0 phyre  Conglomerate dyke  *  469  R70-3  470 R70-4  Whole R  *  471 R70-7  Bio  49.0±1.4 Lamprophyre  Mayflower dyke  «  B70-9  Bio  48.8+1.6 Lamprophyre  Nickel Plate dyke  *  473 B70-11  Bio  49.2tl.4  Dyke  B70-13  Bio  48.1+1.6 Lamprophyre  • •• • • • •  472  474  475 B70-14 Whole H  Lamprophyre  47.0+.1.8 Hornfels  Headwall dyke  •  B70-15  Bio  48.7+1.5 Quartz diorite  Rainy Day Stook  477 R70-16  Bio  50.5+1.5 Granodiorite  Trail Batholith  B70-1?  Bio  49.5±1.4 Granodiorite  Trail Batholith  Bio  47.3+1.5  476  478  479 R70-2  • See referenoe.  Monzonite  GSC Paper 62-17, P. 11  RosBland Monzonite  Macdonald, 1972, in pre paration  Fyles, et a l . , 1 9 7 t i m m  Fyles, et a l . , 197  154.  TABLE D-l  (oont'd) Published K-Ar ages referred to in this report,  Beport Referenoe No. Number and Mineral Dated 4 8 0 R70-6 Bio Bio 481  B?l-1  Age in m.y.  Rook Type  Bio  89.7+2,8 90.8+2.0 58.8+1.8  Unit  Monzonite  Rossland Monzonite  Monzonite  Rossland Monzonite  Location  Referenoe Fyles, et a l . , 1973,  POST-TECTONIC INTRUSIONS 49°07'24.4"N. GSC Paper 67-2A, pp. 44-45 118°23'14"W.  482  GSC66-46  Bio  46+3  Quartz monzonite  483  CSC66-45  Bio  39±5  Quartz monzonite  49°02'49.3" ..'GSC Paoer 6?-2A, pp. 41-42 118°21'43"W.  484  GSC63-1  41+10  Lamprophyre  51°17'N. 118°28'W.  GSC Paper 64-17, (Pt. 1), p. 11  485  GSC63-7  Phlogoplte Bio  Granite  50°00'N. 123°58'W.  GSC Paper 64-17, (Pt. 1), p. 16  56±8  TERTIARY VOLCANICS 486 F69-203 Whole R 51.6+1.7 Latlte 487 AK-112  Bio  49+2  488 AK-I50  Bio  48+2  489 AK-151  Bio  46+2  490  *  Bio  OK Volcanic  Fyles, et a l . , 1973,  Ash  Midway  49°03.8*N.  Pulasklte porphyry  Kettle River  49°02.8'N.  Daclte  Kettle River  49°48'N. 119°06.l'W.  U8°58.4'W.  Mathews, 1964  118°53.1'W.  Marron East of 1970, In (GEM), Formation Yellow Lake* Church, p. 397 (Kitley Lake member)  51.6*1.8  OKANAGAN  491 W65-6 492 W65-5 493 W65-7 494 W65-4 495 W66-7 496 W65-3 497 W67-I  Muse  139+5  Granite  Muse  144+6  Granite  Sericite 140+6  »  Okanagan  1968  *  M  Footwall alteration  N .  #  Bio  82t3  Granite  ft  •  Bio  99+4  Granite  ft  Bio  118±4  Granite  *  tl  •  fl  Sericite 114*5  White et al.,  •  • •  • "  NELSON BATHOLITH  498 GSC66-50 499 GSC63-10  Hb Bio  500, GSC66-51 Hb  501 GSC66-52  Hb  141+16 Quartz Ruby diorite 123+20 Stock 136±14 Granodiorite Nelson 146+10 Granodiorite Nelson (porphyrltio)  502  GSC66-53 Hb  l4l±24  «  Nelson  503 504  GSC62-27 Bio  159 152tl0  *  Nelson  CSC66-54  GSC62-5  Hb Bio  * See reference.  128  Granodiorite Porcupine stock  50°04'57.5"N. GSC Paper 67-2A, 117°43'59"W.  p p .  49°47.0'N.  GSC Paper 67-2A,p .  49°49'N.  GSC Paper  117°22.4'W.  67-2A,  117°12'W. 49°46.4'N. GSC Paper 67-2A, 117°04.5'W.  p p .  p .  II  49°15'N. 11?°05'W.  46-47  47 47-48 48  CSC Paper 67-2A,p . 20 CSC Paper GSC Paper  67-2A, 63-17,  p p .  p p .  48-49  7-8  155. (oont'd) Published K-Ar ages referred to in this report;  TABLE D-l  Report Reference No. Number and Mineral Dated  Age In m.y.  Rock Type  Unit  Location  Reference  505 GSC62-5  Bio  128  Granodiorite  Porcupine stook  49°15'N. 117°05'W.  506 c  Bio  150+6  Quartz monzonite  Nelson  . 49°53 45"N. Nguyen, et a l .1968 U7°l4'23"W.  507  D  Bio  I69t6  Lamprophyre  Dike (outs 49°53'49"N. Nelson) 117°l4'23"W.  508  K  Hb  l6l±6  Quartz monzonite  Mt. Carlyle 49°54 , 58"N. stook in^Ok'lB'V.  509 L-236  Bio  135+5  Hornfels  Zenollth in 49 52'20"N. Nelson 117°06'57"W. Batholith  510 R-ll  Bio  120t5  Granodiorite Nelson (porphyritic)  49°53'15"N. 117°6'25"W.  511 R-12  Bio  146+5  Quartz diorite  w  49°52'56"N. 117°6'38"W.  512 R-13  Bio  130+5  Granodiorite (porphyritic)  m  49°43«58"N. 117°9"45"H.  513 8  Hb  150±5  Quartz monzonite  m  49°57*29"N. 117°21'l6"w.  514 GSC61-17 Bio  131-  Granodiorite  m  49°51'30"N. GSC Paper 62-17. P« 13 117°02,48"W.  515 CSC62-27 Bio  159  Granodiorite  m  49°46'24"N. GSC Paper 117°04'30"W.  516 GSC62-29 Bio  163  Granodiorite  m  49°46« 54"N. GSC Paper 63-I7, P. 21 117 20'18"W.  517 GSC62-26 Bio  165  Granodiorite  m  49°45'48"N. GSC Paper 117°13'30"W.  518 GSC62-28 Bio  171'  Granodiorite  m  , 49°47*N. GSC Paper 63-17, PP . 20-21 117°22 24"W.  519 GSC62-30 Bio  171  Granodiorite  m  5 49°56 N. 117 08'W.  GSC Paper  63-I7,  PP . 7-8  ,  o  ,  •  *  63-17,  63-17,  P. 20  P. 20  GSC Paper  63-17,  P. 21  GSC Paper  61-17,  P. 13  AGES PREVIOUSLY. ASSIGNED TO NELSON BATHOLITH 520 GSC60-21 Bio  49  Quartz monzonite  Nelson  49°42'N. 117°19'W. ,  49°36 N. 117 15'W.  Bio  55  Granodiorite (porphyritic)  522 GSC62-32 Bio  63  Granodiorite  «  49°29'18"N. GSC Paper 117°20'30"W.  523 GSC59-1  Bio  86  Granodiorite  M  49°29'N. 117 20«W.  524  Bio  521  GSC60-22  GSC62-31  0  GSC Paper 61-17, PP . 13-14 63-I7,  Leuoogranlte  m  22-23  GSC Paper  60-17,  P. 5  49°36'36"N. GSC Paper 117007'54"w.  63-17,  P.  o  105  PP .  22  POST TECTONIC INTRUSIONS (see 482-485 and referenoe) GSC 64-22  Bio  52i6  Syenite  526 GSC64-15  Bio  96+5  Quartz monzonite  527 GSC64-16 Bio  80+6  Granodiorite  525  •  See r e f e r e n o e .  • • •  51°55.5*N. 118°10.5»W.  GSC Paper 65-17, P. 20  51°27'N. 119°56'W.  GSC Paper 65-17, P. 16  51 17'20"N.  GSC Paper 65-17, PP . 16-17  O  156.  (oont'd)  TABLE D-l  Published K-Ar ages referred to In this report.  Report Referenoe No. Number and Mineral Dated  Age In m.y.  528. GSC67-42 Hb .  73+>  Rook Type  Location  Unit  Referenoe  CHINA HEAD MOUNTAIN STOCK Granodiorite  • -  51°10'N. 122°23'W.  GSC Paper 69-2A, p. 25  50°05'N. 116°51'W.  GSC Paper 61-17, P. 11  FRI CHEEK BATHOLITH 529 530  GSC60-18 GSC60-19  Bio Muso  45 63  Quartz monzonite  531  GSC62-12  Bio  76  Quartz monzonite  "  49°52'N. ll6°34'W.  GSC Paper 63-I7, PP. 10-11  532  GSC62-8  Muso  83  Quartz monzonite  "  49°59'N. 116 44'12^W.  GSC Paper 63-17, P. 9  533 534  GSC62-11 Bio GSC62-10 Muse  86 91  Quartz monzonite  "  50°05'24"N. 116°33'24"W.  GSC Paper 63-I7, p. 10 GSC Paper 63-17, P. 9-10  535  GSC62-9  Muso  97  Quartz monzonite  "  50°Q1'54"N. GSC Paper 63-17, p. 9 116°39'42"W.  536  GSC62-7  Bio  33  Granodiorite  Bayonne 49°l6'30"N. Batholith . li,6°39'W.  53? KA 118  Bio  77  Granodiorite  Kootenay Lake  49°15'N. 116°39'W.  538  GSC62-6  Bio  100  Quartz monzonite  Bayonne Batholith  GSC Paper 63-17, p. 8 49°24'30"N. 116°44'18"W.  539  GSC62-43 Bio  118  Granodiorite  Fry Creek  0  BAXONNE BATHOLITH GSC Paper 63-17, pp. 8-9 Baadsgaard et a l . , 1961  ANGUS CREEK STOCK Angus Creek  49°33'N. GSC Paper 63-17, p. 30 116°08'36"W.  LOST CREEK STOCK  540 GSC62-4  Bio 119  Quartz monzonite  541  Bio  Granite  49°05'36"N. 117°10'12°W.  GSC Paper 63-17, p. 7  49°05'N. 117°15'W.  Macdonald, 1972, In prep.  50°4l'N. 117°53'M.  GSC Paper 63-17, pp. 24-25  50°25*15"N. 117°20'50"W.  GSC Paper 67-2A, pp. 44-45  Baadsgaard, et a l . , 196la  DODGER STOCK CX-70-19  100±3  Dodger Stock  KUSKANAX BATHOLITH 542 543  GSC62-33 GSC62-34  544  GSC66-48 Muso  Bio Muso  66 90  Quartz monzonite  137t7  Feldspar porphyry  Kuskanax  ICE RIVER COMPLEX  545  AK  46  Bio  355  Jaoupiranglte Ice Blver  51°10'N. 116°23'W.  546  AK 83  Bio  360  Mlnette  51°08'N. 116°24'H.  54?  AK  84  Bio  304  Pegmatite  51°11'N. 116°27'W.  • See referenoe,.  ,  - 7  157.  TABLE D-l  (cont'd)  Published K-Ar ages r e f e r r e d t o i n t h i s r e p o r t ,  Report Referenoe No. Number and Mineral Dated  Age In m.y.  Rook Type  Unit  Looati on  Referenoe  r  548 CSC59-7  Bio  340  Syenite  Ice River  51°12'N. U6°29'W.  GSC Paper 60-17, PP . 6-7  549 GSC59-8  Bio  330  *  N  51°12'N. 116°29'W.  GSC Paper 60-17, P . 7  550  Pyroxenlte 392  551  Bio  336  Biotite pegmatite  552  Bio  327  Mlnette sill  *  • • •  Biotite pyroienlte  •*  Rapson, 1963, pp . 116-124  a  TOBY STOCK 553 GSC66-49 Eb  162*8  Granodiorite  Toby  50°13'N. 116°34'W.  GSC Paper 67-2A, PP . 45-46  554 GSC62-14 Bio  179  Granodiorite gneiss  Toby  50°11'N. 116°34'W.  GSC Paper 63-17, PP . 12-13  Bio  232  Granodiorite  Toby  50°12'36"N. GSC Paper 63-17, PP . 13-14 116°33'24"W.  555 G S C 6 2 - 1 3  ADAMANT BATHOLITH Monzonite  Adamant Pluton  55? GSC61-24 Bio  Granodiorite  Adamant  Granodiorite  Adamant  5l°44'30"N. 118°44'W.  GSC Paper 63-17, PP . 18-19  Pegmatite  Adamant  51°42'40"N.  GSC Paper 62-17, P . 15  90  559  GSC62-24 K 92 feldspar GSC61-22 Bio 131  560 561  GSC61-23 Bio Hb  200 116  Granodiorite  Adamant  GSC62-25  562  GSC61-21 Bio  281  Granodiorite  Adamant  558  51°44'N. 117°55'W.  GSC Paper 65-17, PP . 20-21  556 GSC64-23 ,Whole R 97+12  0  •-5i 46*8"iJ. GSC Paper 62-17, PP . 16-17 U7°54'20"w.  117°50'30"W.  51°46'8"N.  117°51'30"W.  GSC Paper 62-17, PP . 15-16 GSC Paper 63-17, P . 19  51°42'40"N. CSC Paper 62-17, P . 15 11?°50'30"W,  WHITE CREEK BATHOLITH 49°53'N. 116°22'W.  GSC Paper 61-17, P . 6  49°50'N.  GSC Paper 61-17, PP. , 6-7  49°48'N.  GSC Paper 61-17, P . 7  49°51'N. 116°14'W.  GSC Paper 61-17, P . 7  563  GSC60-3  Bio  18  Quartz monzonite  564  GSC60-4  Bio  29  Quartz monzonite \.  «  565  GSC60-5  Bio  56  Maflc-rlch inclusion  m  566  GSC60-6  Bio  60  Quartz monzonite  56?  GSC61-9  Bio  73  Granodiorite  «  49°48'33'*N. GSC Paper 62-17, P . 9 116°13'10"W.  568  GSC60-7  Bio  79  Granodiorite  N  49°48«N. 116°13'W.  569 570  GSC61-11 GSC61-10  Huso Bio  80 82  Quartz monzonite  if  49°51'10"N. GSC Paper 62-17, P . 10 116°16'40"W. f P. 9  571  GSC 62-2  Bio  126  Metadlorlte  H  49°47'18"N. GSC Paper 63-17, P . 5 116°18'54"W.  * See reference.  White Creek  116°17'W. 116°16'W.  GSC Paper 61-17, PP. . 7-8  158.  TABLE. D-l  (oont'd) Published K-Ar ages referred to in this report.  Beport Reference No. . Number and Mineral Dated 572  GSC62-3  Bio  Age in m.y. 138  Rock Type Quartz diorite sill  Unit White Creek  Location 49°45'42"N. 116°19'48"W.  Referenoe GSC Paper 63-I7.  PP. 7-8  HOBSETHIEF CREEK BATHOLITH Quartz monzonite  573  GSC62-16  Bio  108  574  GSC61-19  Bio  205  Granite  96+16 55+8  Schist  575 GSC65-21 Bio 576 GSC65-20 Muso  Horsethlef 50°36'12"N. GSC Paper 63-17, P. 14 Creek ll6 30'42"W. 6  GSC Paper 62-17, pp. 13-14 50°38'6"N. 1I6°35'42°W. 51°48'N.  GSC Paper 66-17, pp. 24-25  51°20'N. 117°50'W.  GSC Paper 63-17, p. 18 GSC Paper 71-2, p. 8  51°03'N. 117°30'W.  GSC Paper  U7°58'W.  FANG CREEK STOCK  '578 GSC62-23 Bio 579 GSC70-5  Hb  168 164+9  Granodiorite Fang stook  BATTLE BATHOLITH 580  GSC62-21  581  GSC62-20  Muse Bio  91 92  Quartz monzonite  Battle Batholith  63-17,  p.  . P.  17 16  582 GSC62-19 Bio 94  Quartz monzonite  51°03'N. 117°30'W.  GSC Paper  63-17,  583 GSC62-22 Muse  120  Pegmatite  51°03'N. 117°30'W.  GSC Paper  63-17, ppJ.7-18  584 GSC61-20 Bio  100  Granodiorite  585 GSC62-17 Bio 586 GSC62-18 Muso  132 138  Quartz monzonite  p.  16  BUGABOO BATHOLITH  587  GSC61-18  588  GSC62-15 Bio  Bio  127  145  Bugaboo Batholith  GLACIER CREEK STOCK Granodiorite Glacier Creek Granodiorite  "  50°44'6"N. GSC Paper 62-17, p. 14 116°55'30"W. 50°45'36"N. GSC Paper 63-17, p. 15 116°49'6"W. , pp. 15-16  50°23'12"N.  GSC Paper 62-17, P. 13  50°23'12"N.  GSC Paper 63-17, p. 13  H  116°47'49 W.  116°47'42"W.  SHUSWAP METAMORPHIC COMPLEX (After Gabrielse & Reesor, 1 9 6 4 ) VALHALLA COMPLEX GSC59-5  B i o  11  590 GSC59-4  Bio  13  589  Granitegneiss  Valhalla  49°51*N. 117°4l'W.  GSC Paper 60-17, p. 6  Granodiorite gneiss  49°51'N. GSC Paper 60-17, p. 6 117 37'30"W.  Granltegnel88  49°57'N. GSC Paper 61-17, p. 8 117°35'10"W.  o  591 GSC60-8  Bio  15  GSC59-6  B i o  16  Granodiorite gneiss  49°51'30"N. 117°37'W.  Bio  25  Granitic gneiss  49 52*30"N. GSC Paper 61-17, P . 8 117°4l'15"W.  592  593 CSC60-9  * See referenoe.  o  GSC Paper 60-17, P . 6  159.  TABLE D-l  (oont'd) Published K-Ar ages referred to In this report.  Report ReferenoeAge No, Number and In m.y. Mineral nat.nd  Rook Type  Unit  Looatlon  Referenoe  Valhalla  49°37'N. 117°48'W.  GSC Paper 61-17, PP. 8-9  49°47'30"N. 117°37'W.  GSC Paper 61-17, P. 9  594 CSC60-10 31o .  28  595 GSC60-II Bio  31  596  CSC60-12  Bio  42  Granite  49°48'N. GSC Paper 61-17, p. 9 117°49'40"W.  597  CSC6O-13 Bio  46  Pegmatite  49°42'53"N. GSC Paper 61-17. PP. 9-10 117°42'20"W.  598  GSC60-14 Bio  47  Gneiss  49°46'N. 117°29'W.  GSC Paper 61-17, p. 10  599 CSC60-15 Bio  58  Gneissic Granite  49°53'13"N. 117°42'W.  GSC Paper 61-17, P. 10  600  CSC61-16 Bio  58  Granite  49°48'N. 117°54'W.  GSC Paper 62-17, P. 12  601 GSC61-15 Bio  59  Granitegneiss  49°42 25"N. 117°54'W.  602  GSC60-I6  Bio  60  Granitegneiss  4o°53'47"N. GSC Paper 6l-17, PP. 10-11 117°37'20"W.  603  GSC60-17  Bio  62  Gneiss  49°42'N. 117°36'W.  GSC Paper 61-17, p. 11  66  Granite  49°44'N. 117°58'W.  GSC Paper 62-17, P. 11  Quarts monzonite  49°59«l4"N, 117°50'H.  GSC Paper 63-17, PP. 26-29  Quartz monzonite  GSC Paper 64-17, Pt. 1, 50°l'23"N. 117°42'23"W. p. 19  604 GSC61-14 Bio 605  CSC62-39 Bio  606 CSC63-II  Bio  69 107±6  Quartz monzonite (gneiss) Granite gneiss  607 GSC63-IO Bio  123±20 Diorite  608 GSC63-12 Bio  74+4  ,  GSC Paper 62-17, P. 12  50°4'57.5"N. GSC Paper 64-17, Pt. 1, p. 18 117°43'59"M. GSC Paper 64-17, Pt. 1, 50°2'17"N, 117°35'19"W. p. 20  Quartz monzonite  GSC Paper 64-17, Pt. 1, pp. 16-17  609 GSC63-8  Bio 110±6  Granite*  610 A  Bio  Nguyen, et a l . , 1968 Granodiorite Fennell Cr. 49°53'12"N. , (porphyritic) Stock 117°l4 ll"W.  149±5 6l_6  Granodiorite gneiss  Shuswap  50°34'N. 118°9'W.  612 GSC66-44 Hb 613 GSC62-35 Bio  79±8 64  Granodiorite gneiss  Shuswap  50°33'12"N. GSC Paper 67-2A, p. 41 , 118°o4 54"W. GSC Paper 63-17, pp. 25-26  614 AK 25  36  Gneissic granite  611  GSC66-43  Hb  GSC Paper 67-2A, pp. 40-41  M0NASHEE GROUP Bio  615  GSC61-5  Bio  52  6 1 6  C S C 6 1 - 4  Bio  57  617 AK 29  Bio  618 GSC60-1  Bio 6 2  * See reference.  57  49°1'N. 118018^.  Baadsgaard et a l . , 1961  50°34'N. 118°43'W.  GSC Paper 62-17, P. 6  Pegmatite  50°34'N. 118°43'w.  GSC Paper 62-17, P. 6  Granodiorite  51°08'N. 118°11'H.  Baadsgaard et a l . , 1961  Gneiss  50°15'N. 119°9'w.  GSC Paper 61-17, P. 5  Gneiss  Honashee  160.  TABLE (oont'd) Published K- Ar ages referred to In this report. D-l Beport ReferenoeAge No. Number and In m.y. Rook Type Unit Location Mineral Dated  Reference  50°49'13"N. 118°15'9"W.  GSC Paper 63-I?, p. 31  Pegmatite  50°56'N. 118°27'W.  GSC Paper 62-17. P. 7  Quartzite  GSC Paper 63-I7, PP. 31-32 50°49'N. 118°15'30"W.  Granite  GSC Paper 63-I7, p. 32 50°47'24"N. 118°15'16"W.  Pegmatite  GSC Paper 62-17, PP. 8-9 50°49'3"N. 118°15'48"W.  Paragneiss  GSC Paper 63-17, PP. 32-34 50°46'44"N. 118°l4'l6"M.  89  Gneiss  50°32'N. 118°2'W.  102  Paragneiss  50 S6'N. 118°27'W.  GSC Paper 62-17, PP. 7-8  Granite  50°00'N. 118°06'W.  Baadsgaard et a l . , 1961  96  Granite (porphyrltio)  49°58'N. 118°18'V.  Baadsgaard et a l . , I96I  630 GSC62-37 Bio  127  Leucooratlo rock  50°46'N. 119020'H.  GSC Paper 63-17, p. 26  631 GSC61-2 632 GSC61-3 633 GSC61-1  1?6  Sohist  , 50°48«N. 118°42 W.  GSC Paper 62-17, p. 5 1 P. 6  140  Gneiss  50°47'30"N. 118°40'W.  GSC Paper 62-17, p. 5  6 1 9 GSC62-45 Muso 6 5 620 GSC62-44 Bio 70 621 GSC61-6  Bio  71  622 GSC62-46 Huso  73  623 GSC62-4? Bio  76  624 GSC61-8  Muso 8 1  625  GSC62-48  626  GSC62-36 Bio  627  GSC61-7 Bio  628  AK 2?  629  AK  4?  Bio  81  Bio Bio  Quartzite  Monashee  GSC Paper 63-17, p. 26  o  MT. IDA GROUP  Bio Muso Bio  l4o  METAMORPHIC ROCKS NORTH AND SOUTH OF ADAMANT BATHOLITH 634 GSC62-49 Bio 635 GSC62-50 Muse 636 GSC61-28 Muse  73 72 107  637 638 639 640  119 124 146 205  GSC62-51 GSC62-52 GSC62-53 GSC62-54  Bio Muse Bio Muso  D 51°54'10"N. 117 56'8"W.  GSC Paper 63-17, p. 34  Pegmatite  51°48'N. 117°57'W.  GSC Paper 62-17, p. 18  Schist  51°34'55 N. " ~'4"W. II7038  Schist  .0 6 51°34'5"N. GSC Paper 63-17, p. 36 117 33'30"W. . PP. 37-38  Schist  *  U  GSC Paper 63-17, P. 35  UNDIFFERENTIATED METAMORPHICS 641 GSC64-18 Phlogoplte  51+10  Marble  642 GSC64-19 Bio 6 4 3 GSC64-20 Muso  67+10  58+6  Quartzite  6 Chancellor 51°58'N. Formation 118 1.5'W.  51°47'N. 117°43'H.  GSC Paper 65-17, p. 1 8 GSC Paper 65-17, P. 1 8  161. TABLE D-l  (oont'd.) Published K-Ar ages refered to In this report.  Report Referenoe No. Number and Mineral Pitted  Age In m.y.  Rook Type  Unit  Location  Reference  Vancouver Island (Supplement) E. Straggling Island  644 KN-68-158 Whole R 32.3*1.6 Dike  Unpublished K. Northoote B.C. Dept. Mines 4 Pet. Res. "  645 PN-70- 124A Bio  50.6ti. .7 Intrusive  Hepler Creek  646 KN-69- 10 Whole R  103*4  Rhyodaolte  East side of mouth of Hansons Lagoon  "  Rhyollte  Cape Soott  *  6 4 8 KN-69--98 Whole R 139*4 VI 649 PN-70-•124A Bio 145*5  Rhyodaclte  East side of mouth of Hansons Lagoon  *  Intrusive  Helper Creek  "  650 KN-69-.327 Whole H  l45±6  Rhyodaolte  Radar Domes San Josef  "  651 KN-68-•177A Bio  15**6  Intrusive  East End Rupert Inlet  "  652 CN-70-•152 Bio  159*5  Intrusive  Southeast of Nahwittl  "  64? KN-69-8  Whole R  134*4  Lake  653 KH-68.•168 Whole R  l6ii6  654 KN-69'•234 Bio  163*6  655 CN-70 -204B Bio  l66±5  656 KN-69-264A Bio  169*6  65?  Whole R 182*6  Bonanza Granitic Intrusive  Apple Bay North of Nahwittl Lk. Ridge east of Stranby & south of Irony North of west end of Nahwittl Lake  " "  Shaft Creek (Llard unpublished age Copper) B.C. Dept. Mines & Pet.  

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